Coastal upwelling fluxes of O2, N2O, and CO2 assessed from continuous atmospheric observations at Trinidad, California

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T. J. Lueker

2004-01-01

Full Text Available Continuous atmospheric records of O2/N2, CO2 and N2O obtained at Trinidad, California document the effects of air-sea exchange during coastal upwelling and plankton bloom events. The atmospheric records provide continuous observations of air-sea fluxes related to synoptic scale upwelling events over several upwelling seasons. Combined with satellite, buoy and local meteorology data, calculated anomalies in O2/N2 and N2O were utilized in a simple atmospheric transport model to compute air-sea fluxes during coastal upwelling. CO2 fluxes were linked to the oceanic component of the O2 fluxes through local hydrographic data and estimated as a function of upwelling intensity (surface ocean temperature and wind speed. Regional air-sea fluxes of O2/N2, N2O, and CO2 during coastal upwelling were estimated with the aid of satellite wind and SST data. Upwelling CO2 fluxes were found to represent ~10% of export production along the northwest coast of North America. Synoptic scale upwelling events impact the net exchange of atmospheric CO2 along the coastal margin, and will vary in response to the frequency and duration of alongshore winds that are subject to climate change.

Determination of the Anthropogenic Carbon Signal to the Total Change in Dissolved Carbon in the Coastal Upwelling Region Along the Washington-Oregon-California Continental Margin

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Feely, R. A.

2016-02-01

The continental shelf region off the Washington-Oregon-California coast is seasonally exposed to water with a low aragonite saturation state by coastal upwelling of CO2-rich waters. To date, the spatial and temporal distribution of anthropogenic CO2 (Canthro) contribution to the CO2-rich waters is largely unknown. Here we use an adaptation of the linear regression approach described in Feely et al (2008) along with the GO-SHIP Repeat Hydrography data sets from the northeast Pacific to establish an annually updated relationship between Canthro and potential density. This relationship was then used with the NOAA Ocean Acidification Program west coast cruise data sets from 2007, 2011, 2012 and 2013 to determine the spatial variations of Canthro in the upwelled water. Our results show large spatial differences in Canthro in surface waters along the coast with the lowest surface values (40-45 µmol kg-1) in strong upwelling regions of off northern California and southern Oregon and higher values (50-70 µmol kg-1) to the north and south. Canthro contributes an average of about 70% of the increased amount of dissolved inorganic carbon in the upwelled waters at the surface. In contrast, at 50 m the Canthro contribution is approximately 31% and at 100 m it averages about 16%. The remaining contributions are primarily due to respiration processes in the water that was upwelled and transported to coastal regions or underwent respiration processes that occurred locally during the course of the upwelling season. The uptake of Canthro has caused the aragonite saturation horizon to shoal by approximately 30-50 m since preindustrial period so that the undersaturated waters are well within the regions that affect the biological communities on the continental shelf.

On the presence of coastal upwelling along the northeastern Tyrrhenian coast

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Martellucci, Riccardo; Melchiorri, Cristiano; Costanzo, Lorenzo; Marcelli, Marco

2017-04-01

The Mediterranean region shows a high climate variability due to the interactions between mid-latitude and tropical processes. This variability makes the Mediterranean a potentially vulnerable region to climatic changes. The present research aims to investigate the hydrographical response to Northerly wind in the northeastern Tyrrhenian coast, to identify the relations between upwelling events and teleconnection patterns. In the Tyrrhenian basin northerly winds flow between North-East and North-West and could be considered upwelling favorable winds. This atmospheric circulation can causes a divergent flow near the coast that generates a subsurface water flows inshore toward the coast up to the surface layer that is upwelling. This phenomenon strongly influence the marine ecosystems, contributing to the supply of nutrients and affecting the primary producers. In this context multi-platform observing system is an important tool to follow the evolution of these phenomena. Sea temperature and wind field acquired by the C-CEMS Observing system were used to identify upwelling phenomena between 2012 and 2016, in the coastal area of Civitavecchia, Northern Tyrrhenian sea, Italy. Moreover a thirty years' wind-driven upwelling conditions have been studied in the area. ERA-Interim (ECMWF) wind data for the period 1982-2012 have been used to compute the distribution of upwelling favorable wind events. These have been compared to "Copernicus Marine Environment Monitoring Service" Sea Surface Temperature (SST) to compute upwelling events. Upwelling favorable wind has been defined in the sector between Northwest and Northeast (Wd >330°N & Wd analysis. An increase of upwelling events in the Tyrrhenian coast is observed in the last thirty years; the occurrence of upwelling events has a seasonal oscillation, with a maximum frequency during winter and spring seasons. In the last decade an increase of these events in winter and a decrease in spring is observed; also a recurrence of

Gradients in microbial methanol uptake: productive coastal upwelling waters to oligotrophic gyres in the Atlantic Ocean

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Dixon, Joanna L; Sargeant, Stephanie; Nightingale, Philip D; Colin Murrell, J

2013-01-01

Methanol biogeochemistry and its importance as a carbon source in seawater is relatively unexplored. We report the first microbial methanol carbon assimilation rates (k) in productive coastal upwelling waters of up to 0.117±0.002 d−1 (∼10 nmol l−1 d−1). On average, coastal upwelling waters were 11 times greater than open ocean northern temperate (NT) waters, eight times greater than gyre waters and four times greater than equatorial upwelling (EU) waters; suggesting that all upwelling waters upon reaching the surface (⩽20 m), contain a microbial population that uses a relatively high amount of carbon (0.3–10 nmol l−1 d−1), derived from methanol, to support their growth. In open ocean Atlantic regions, microbial uptake of methanol into biomass was significantly lower, ranging between 0.04–0.68 nmol l−1 d−1. Microbes in the Mauritanian coastal upwelling used up to 57% of the total methanol for assimilation of the carbon into cells, compared with an average of 12% in the EU, and 1% in NT and gyre waters. Several methylotrophic bacterial species were identified from open ocean Atlantic waters using PCR amplification of mxaF encoding methanol dehydrogenase, the key enzyme in bacterial methanol oxidation. These included Methylophaga sp., Burkholderiales sp., Methylococcaceae sp., Ancylobacter aquaticus, Paracoccus denitrificans, Methylophilus methylotrophus, Methylobacterium oryzae, Hyphomicrobium sp. and Methylosulfonomonas methylovora. Statistically significant correlations for upwelling waters between methanol uptake into cells and both chlorophyll a concentrations and methanol oxidation rates suggest that remotely sensed chlorophyll a images, in these productive areas, could be used to derive total methanol biological loss rates, a useful tool for atmospheric and marine climatically active gas modellers, and air–sea exchange scientists. PMID:23178665

Coastal upwelling in the Gelendzhik area of the Black Sea: Effect of wind and dynamics

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Silvestrova, K. P.; Zatsepin, A. G.; Myslenkov, S. A.

2017-07-01

Long series data of a thermistor chain in the Black Sea coastal zone near Gelendzhik were analyzed. A thermistor chain installed 1 km offshore and at a depth of 22 m. There are full and incomplete upwelling events observed. The study of upwelling genesis based on: wind speed data from the NCEP/CFSR reanalysis and Gelendzhik weather station, velocity and direction of coastal currents measured by ADCP profiler moored on the bottom near the thermistor chain. Over the whole observation period (warm seasons of 2013-2015), more than 40 events of upwelling were registered four of them were full upwellings, when presence of under-thermocline water was observed near the sea surface. For every upwelling event, conditions prior to the changes in thermic structure, were analyzed. It is found that full upwelling generally occur under synergistic wind and current forcing. Fairly strong forcing of one of these factors is sufficient for partial upwelling to occur.

Interactions between trophic levels in upwelling and non-upwelling regions during summer monsoon

Digital Repository Service at National Institute of Oceanography (India)

Malik, A; Fernandes, C.E.G.; Gonsalves, M.J.B.D.; Subina, N.S.; Mamatha, S.S.; Krishna, K.S.; Varik, S.; RituKumari; Gauns, M.; Cejoice, R.P.; Pandey, S.S.; Jineesh, V.K.; Kamaleson, A; Vijayan, V.; Mukherjee, I.; Subramanyan, S.; Nair, S.; Ingole, B.S.; LokaBharathi, P.A

Coastal upwelling is a regular phenomenon occurring along the southwest coast of India during summer monsoon (May–September). We hypothesize that there could be a shift in environmental parameters along with changes in the network of interactions...

Relative contributions of local wind and topography to the coastal upwelling intensity in the northern South China Sea

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Wang, Dongxiao; Shu, Yeqiang; Xue, Huijie; Hu, Jianyu; Chen, Ju; Zhuang, Wei; Zu, TingTing; Xu, Jindian

2014-04-01

Topographically induced upwelling caused by the interaction between large-scale currents and topography was observed during four cruises in the northern South China Sea (NSCS) when the upwelling favorable wind retreated. Using a high-resolution version of the Princeton Ocean Model, we investigate relative contributions of local wind and topography to the upwelling intensity in the NSCS. The results show that the topographically induced upwelling is sensitive to alongshore large-scale currents, which have an important contribution to the upwelling intensity. The topographically induced upwelling is comparable with the wind-driven upwelling at surface and has a stronger contribution to the upwelling intensity than the local wind does at bottom in the near-shore shelf region. The widened shelf to the southwest of Shanwei and west of the Taiwan Banks intensifies the bottom friction, especially off Shantou, which is a key factor for topographically induced upwelling in terms of bottom Ekman transport and Ekman pumping. The local upwelling favorable wind enhances the bottom friction as well as net onshore transport along the 50 m isobath, whereas it has less influence along the 30 m isobath. This implies the local wind is more important in upwelling intensity in the offshore region than in the nearshore region. The contribution of local upwelling favorable wind on upwelling intensity is comparable with that of topography along the 50 m isobath. The effects of local upwelling favorable wind on upwelling intensity are twofold: on one hand, the wind transports surface warm water offshore, and as a compensation of mass the bottom current transports cold water onshore; on the other hand, the wind enhances the coastal current, and the bottom friction in turn increases the topographically induced upwelling intensity.

Future changes in coastal upwelling ecosystems with global warming: The case of the California Current System.

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Xiu, Peng; Chai, Fei; Curchitser, Enrique N; Castruccio, Frederic S

2018-02-12

Coastal upwelling ecosystems are among the most productive ecosystems in the world, meaning that their response to climate change is of critical importance. Our understanding of climate change impacts on marine ecosystems is largely limited to the open ocean, mainly because coastal upwelling is poorly reproduced by current earth system models. Here, a high-resolution model is used to examine the response of nutrients and plankton dynamics to future climate change in the California Current System (CCS). The results show increased upwelling intensity associated with stronger alongshore winds in the coastal region, and enhanced upper-ocean stratification in both the CCS and open ocean. Warming of the open ocean forces isotherms downwards, where they make contact with water masses with higher nutrient concentrations, thereby enhancing the nutrient flux to the deep source waters of the CCS. Increased winds and eddy activity further facilitate upward nutrient transport to the euphotic zone. However, the plankton community exhibits a complex and nonlinear response to increased nutrient input, as the food web dynamics tend to interact differently. This analysis highlights the difficulty in understanding how the marine ecosystem responds to a future warming climate, given to range of relevant processes operating at different scales.

Upwelling regions, the most fertile of the seas' habitats, are also ...

African Journals Online (AJOL)

spamer

apply to dinoflagellate bloom events in coastal upwelling systems. * Graduate School of ..... exclusive of coccolithophorids (Smayda 1997b). Group. Daily growth rates ..... route taken partly dependent on the duration of the upwelling relaxation ...

How coastal upwelling influences spatial patterns of size-structured diversity of copepods off central-southern Chile (summer 2009)

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Hidalgo, Pamela; Escribano, Ruben; Fuentes, Marcelo; Jorquera, Erika; Vergara, Odette

2012-01-01

This study assessed the structure of the copepod community in the upper 200 m of the coastal upwelling region off central-southern Chile in late summer 2009. Vertically stratified zooplankton samples and hydrographic variables were obtained from 42 stations over the continental shelf and oceanic areas. The survey took place during active upwelling, reflected by a cold upwelling plume extending out to 150 km offshore. A total of 62 copepod species were found. Of these, Oithona similis and Paracalanusindicus accounted for ca. 60% of the whole community. Species richness ( R) and the Shannon-Wiener diversity index ( H‧) were estimated, and the latter was additionally modified to incorporate the effect of copepod size on diversity ( H‧ s). Samples were analyzed for two depth strata (0-50, 50-200 m) and for day vs. night conditions. Significant effects of day vs. night and strata on R, H‧ and H‧ s indicated that diel vertical migration between these two layers was an important source of variation in the zooplankton community. H‧ s seemed to represent copepod diversity better than R and H‧ over the spatial scale. H‧ s was also closely linked to colder upwelled water and the depth of the oxygen minimum zone following a principal component analysis. A positive relationship was even detected between depth of the oxygen minimum zone and H‧ s when strata and day/night effects were excluded. Our findings suggested that the coastal upwelling process could be an important driver of copepod diversity in this region. Upwelling leads to changes in the depth of the oxygen minimum zone and these changes impact the community composition due to species-dependent tolerances to low oxygen water.

Trends in the number of extreme hot SST days along the Canary Upwelling System due to the influence of upwelling

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Xurxo Costoya

2014-07-01

Full Text Available Trends in the number of extreme hot days (days with SST anomalies higher than the 95% percentile were analyzed along the Canary Upwelling Ecosystem (CUE over the period 1982- 2012 by means of SST data retrieved from NOAA OI1/4 Degree. The analysis will focus on the Atlantic Iberian sector and the Moroccan sub- region where upwelling is seasonal (spring and summer are permanent, respectively. Trends were analyzed both near coast and at the adjacent ocean where the increase in the number of extreme hot days is higher. Changes are clear at annual scale with an increment of 9.8±0.3 (9.7±0.1 days dec-1 near coast and 11.6±0.2 (13.5±0.1 days dec-1 at the ocean in the Atlantic Iberian sector (Moroccan sub-region. The differences between near shore and ocean trends are especially patent for the months under intense upwelling conditions. During that upwelling season the highest differences in the excess of extreme hot days between coastal and ocean locations (Δn(#days dec-1 occur at those regions where coastal upwelling increase is high. Actually, Δn and upwelling trends have shown to be significantly correlated in both areas, R=0.88 (p<0.01 at the Atlantic Iberian sector and R=0.67 (p<0.01 at the Moroccan sub-region.

Phytoplankton community and environmental correlates in a coastal upwelling zone along western Taiwan Strait

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Wang, Yu; Kang, Jian-hua; Ye, You-yin; Lin, Geng-ming; Yang, Qing-liang; Lin, Mao

2016-02-01

Upwelling system in western Taiwan Strait is important for facilitating the fishery production. This study investigated hydro-chemical properties, phytoplankton biomass, phytoplankton species composition, three-dimensional (horizontal, vertical and transect) distribution of phytoplankton abundance, as well as phytoplankton annual variation and the correlation of phytoplankton community with the upwelling of underlying current and nutrients according to samples of Fujian-Guangdong coastal upwelling zone in western Taiwan Strait from August 27 to September 8, 2009. The results manifest that the nutrient-rich cold and high salinity current on the continental shelf of South China Sea upwells to the Fujian-Guangdong coastal waters through Taiwan Bank and the surging strength to surface is weak while strong at 30-m layer. The thermohaline center of coastal upwelling shifts to the east of Dongshan Island and expanded to offshore waters in comparison with previous records. A total of 137 phytoplankton species belonging to 59 genera in 4 phyla are identified excluding the unidentified species. Diatom is the first major group and followed by dinoflagellate. Cyanobacteria mainly composed by three Trichodesmium species account for a certain proportions, while Chrysophyta are only found in offshore waters. The dominant species include Thalassionema nitzschioides, Pseudo-nitzschia pungens, Thalassionema frauenfeldii, Pseudo-nitzschia delicatissima, Rhizosolenia styliformis, Chaetoceros curvisetus, Diplopsalis lenticula and Trichodesmium thiebautii. Phytoplankton community mainly consists of eurythermal and eurytopic species, followed by warm-water species, tropic high-salinity species and oceanic eurythermic species in order. Phytoplankton abundance ranges from 1.00 × 102 ind./L ~ 437.22 × 102 ind./L with an average of 47.36 × 102 ind./L. For vertical distribution, maximum abundance is found at 30 m-depth and the surface comes second. Besides, the abundance below 30 m

Ecological features of harmful algal blooms in coastal upwelling ...

African Journals Online (AJOL)

The mass mortalities that accompany anoxia, common to the Benguela and Peru upwelling systems, may be a trophic control mechanism to maintain biogeochemical balance and regional homeostasis, which are vital to upwelling ecosystem dynamics. Some traditional concepts of phytoplankton ecology may not completely

Changes in the partial pressure of carbon dioxide in the Mauritanian–Cap Vert upwelling region between 2005 and 2012

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M. González-Dávila

2017-08-01

Full Text Available Coastal upwellings along the eastern margins of major ocean basins represent regions of large ecological and economic importance due to the high biological productivity. The role of these regions for the global carbon cycle makes them essential in addressing climate change. The physical forcing of upwelling processes that favor production in these areas are already being affected by global warming, which will modify the intensity of upwelling and, consequently, the carbon dioxide cycle. Here, we present monthly high-resolution surface experimental data for temperature and partial pressure of carbon dioxide in one of the four most important upwelling regions of the planet, the Mauritanian–Cap Vert upwelling region, from 2005 to 2012. This data set provides direct evidence of seasonal and interannual changes in the physical and biochemical processes. Specifically, we show an upwelling intensification and an increase of 0.6 Tg yr−1 in CO2 outgassing due to increased wind speed, despite increased primary productivity. This increase in CO2 outgassing together with the observed decrease in sea surface temperature at the location of the Mauritanian Cap Blanc, 21° N, produced a pH rate decrease of −0.003 ± 0.001 yr−1.

Atmosphere-ocean feedbacks in a coastal upwelling system

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Alves, J. M. R.; Peliz, A.; Caldeira, R. M. A.; Miranda, P. M. A.

2018-03-01

The COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) modelling system is used in different configurations to simulate the Iberian upwelling during the 2012 summer, aiming to assess the atmosphere-ocean feedbacks in the upwelling dynamics. When model results are compared with satellite measurements and in-situ data, two-way coupling is found to have a moderate impact in data-model statistics. A significant reinforcement of atmosphere-ocean coupling coefficients is, however, observed in the two-way coupled run, and in the WRF and ROMS runs forced by previously simulated SST and wind fields, respectively. The increasing in the coupling coefficient is associated with slight, but potentially important changes in the low-level coastal jet in the atmospheric marine boundary layer. While these results do not imply the need for fully coupled simulations in many applications, they show that in seasonal numerical studies such simulations do not degrade the overall model performance, and contribute to produce better dynamical fields.

Short-term meso-scale variability of mesozooplankton communities in a coastal upwelling system (NW Spain)

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Roura, Álvaro; Álvarez-Salgado, Xosé A.; González, Ángel F.; Gregori, María; Rosón, Gabriel; Guerra, Ángel

2013-02-01

The short-term, meso-scale variability of the mesozooplankton community present in the coastal upwelling system of the Ría de Vigo (NW Spain) has been analysed. Three well-defined communities were identified: coastal, frontal and oceanic, according to their holoplankton-meroplankton ratio, richness, and total abundance. These communities changed from summer to autumn due to a shift from downwelling to upwelling-favourable conditions coupled with taxa dependent changes in life strategies. Relationships between the resemblance matrix of mesozooplankton and the resemblance matrices of meteorologic, hydrographic and community-derived biotic variables were determined with distance-based linear models (DistLM, 18 variables), showing an increasing amount of explained variability of 6%, 16.1% and 54.5%, respectively. A simplified model revealed that the variability found in the resemblance matrix of mesozooplankton was mainly described by the holoplankton-meroplankton ratio, the total abundance, the influence of lunar cycles, the upwelling index and the richness; altogether accounting for 64% of the total variability. The largest variability of the mesozooplankton resemblance matrix (39.6%) is accounted by the holoplankton-meroplankton ratio, a simple index that describes appropriately the coastal-ocean gradient. The communities described herein kept their integrity in the studied upwelling and downwelling episodes in spite of the highly advective environment off the Ría de Vigo, presumably due to behavioural changes in the vertical position of the zooplankton.

Discriminating the biophysical impacts of coastal upwelling and mud banks along the southwest coast of India

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Karnan, C.; Jyothibabu, R.; Arunpandi, N.; Jagadeesan, L.; Muraleedharan, K. R.; Pratihari, A. K.; Balachandran, K. K.; Naqvi, S. W. A.

2017-08-01

Coastal upwelling and mud banks are two oceanographic processes concurrently operating along certain stretches of the southwest (Kerala) coast of India during the Southwest Monsoon period (June-September), facilitating significant enhancement in plankton biomass. Mud banks have scientific and societal attention from time immemorial, predominantly due to the large fisheries associated with them. In this paper, for the first time, the specific biophysical roles of these oceanographic processes have been discriminated, based on a focused 18 weekly/fortnightly time-series study (April to September 2014) in a mud bank-upwelling area (off Alappuzha, southwest coast of India). In conjunction with standard hydrographical and satellite remote sensing data, we utilised a FlowCAM to track the biophysical linkage in terms of plankton composition abundance and size structure at three locations (M1, M2 and M3) in the study area. During the Pre-Southwest Monsoon (April-May), the entire study area was warmer with low nitrate concentration in the surface waters, which caused lower biomass of autotrophs compared to the Southwest Monsoon (June-September). By the onset of the Southwest Monsoon (June), drastic hydrographical transformations took place in the study domain due to the Coastal upwelling, reflected as the surfacing of significantly cool, high nutrient and hypoxic waters. Concurrently, mud bank formed at location M2 due to the presence of relatively high-suspended sediments in the region, creating a localised calm environment conducive for fishing activities. In response to the hydrographical transformations in the entire study area during the Southwest Monsoon, the autotrophic plankton biomass and size structure experienced significant change. The micro-autotrophs biomass that was low during the Pre-Southwest Monsoon (av. 0.33 ± 0.2 mgC L- 1 at surface and av. 0.07 ± 0.04 mgC L- 1 at subsurface) noticeably increased during the Southwest Monsoon (av. 1.6 ± 0.4 mgC L- 1 at

Role of physical forcings and nutrient availability on the control of satellite-based chlorophyll a concentration in the coastal upwelling area of the Sicilian Channel

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Bernardo Patti

2010-08-01

Full Text Available The northern sector of the Sicilian Channel is an area of favourable upwelling winds, which ought to support primary production. However, the values for primary production are low when compared with other Mediterranean areas and very low compared with the most biologically productive regions of the world’s oceans: California, the Canary Islands, Humboldt and Benguela. The aim of this study was to identify the main factors that limit phytoplankton biomass in the Sicilian Channel and modulate its monthly changes. We compared satellite-based estimates of chlorophyll a concentration in the Strait of Sicily with those observed in the four Eastern Boundary Upwelling Systems mentioned above and in other Mediterranean wind-induced coastal upwelling systems (the Alboran Sea, the Gulf of Lions and the Aegean Sea. Our results show that this low level of chlorophyll is mainly due to the low nutrient level in surface and sub-surface waters, independently of wind-induced upwelling intensity. Further, monthly changes in chlorophyll are mainly driven by the mixing of water column and wind-induced and/or circulation-related upwelling processes. Finally, primary production limitation due to the enhanced stratification processes resulting from the general warming trend of Mediterranean waters is not active over most of the coastal upwelling area off the southern Sicilian coast.

Role of nutrient recycling in upwelling ecosystems

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Whitledge, T E

1979-01-01

The regeneration of nitrogen is an important process that increases the efficiency of the upwelling ecosystem by enlarging their spatial scales. Ammonium regeneration was considered to contribute 42 to 72 percent of phytoplankton nitrogen requirements in the northwest Africa, Peru, and Baja California upwelling systems. Zooplankton are responsible for the largest portion of regenerated nitrogen; however, fish and benthic sediments may be nearly as large. Comparisons of the importance of ammonium regeneration in upwelling areas with coastal and open ocean regions indicate that the percentage contributions are similar. Future nutrient regeneration studies are needed to assess the recycling of benthic sediments, microzooplankton, gelatinous zooplankton, demersal fish, bacterioplankton, and mollusks.

Pliocene Warm Period Upwelling in the Southern Benguela Region

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Petrick, B. F.; McClymont, E.; Felder, S.; Leng, M. J.; Rosell Mele, A.; Rueda, G.

2014-12-01

The mid-Pliocene has been proposed as a possible analogue for understanding future climate change and testing climate models. Previous work has shown that during the Pliocene the major upwelling systems were relatively warm, and thus either inactive, contracted, or upwelling warmer waters than present. Here we examine evidence from a core site located on the margins of the modern Benguela upwelling system, to test whether the upwelling cells had migrated or contracted relative to present during the Pliocene. We applied several organic geochemistry proxies and foraminiferal analyses to reconstruct the Pliocene history of ODP site 1087 (31º28'S, 15º19'E, 1374m water depth), including the UK37' index and TEX86 index (for reconstructing sea surface temperatures), chlorins (for estimating primary productivity) and planktonic foraminifera assemblages (for inferring water mass changes). These proxies show that between 3.5 and 3.0 Ma the southern Benguela region was significantly cooler than the northern Benguela region, the latter where the main upwelling cells are found today. Coupled with higher primary production, a shift in planktonic foraminifera assemblage, and an offset between the UK37' index and TEX86 index, we infer that more extensive upwelling was present in the southern Benguela region during the Pliocene. We infer that the main Benguela upwelling cells had shifted southward relative to today, as a result of changes in the local wind field. We find evidence for pronounced cooling and a shift in the planktonic foraminifera assemblage during the M2 and KM2 glacial stages, showing a sensitivity of Benguela upwelling to these short-lived climate events.

Under pressure: Climate change, upwelling and eastern boundary upwelling ecosystems

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Marisol eGarcía-Reyes

2015-12-01

Full Text Available The IPCC AR5 provided an overview of the likely effects of climate change on Eastern Boundary Upwelling Systems (EBUS, stimulating increased interest in research examining the issue. We use these recent studies to develop a new synthesis describing climate change impacts on EBUS. We find that model and observational data suggest coastal upwelling-favorable winds in poleward portions of EBUS have intensified and will continue to do so in the future. Although evidence is weak in data that are presently available, future projections show that this pattern might be driven by changes in the positioning of the oceanic high-pressure systems rather than by deepening of the continental low-pressure systems, as previously proposed. There is low confidence regarding the future effects of climate change on coastal temperatures and biogeochemistry due to uncertainty in the countervailing responses to increasing upwelling and coastal warming, the latter of which could increase thermal stratification and render upwelling less effective in lifting nutrient-rich deep waters into the photic zone. Although predictions of ecosystem responses are uncertain, EBUS experience considerable natural variability and may be inherently resilient. However, multi-trophic level, end-to-end (i.e., winds to whales studies are needed to resolve the resilience of EBUS to climate change, especially their response to long-term trends or extremes that exceed pre-industrial ranges.

Discriminating the biophysical impacts of coastal upwelling and mud banks along the southwest coast of India

Digital Repository Service at National Institute of Oceanography (India)

Karnan, C.; Jyothibabu, R.; Arunpandi, N.; Jagadeesan, L.; Muraleedharan, K.R.; Pratihary, A.K.; Balachandran, K.K.; Naqvi, S.W.A.

Coastal upwelling and mud banks are two oceanographic processes concurrently operating along certain stretches of the southwest (Kerala) coast of India during the Southwest Monsoon period (June-September), facilitating significant enhancement...

Influences of riverine and upwelling waters on the coastal carbonate system off Central Chile and their ocean acidification implications

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Vargas, Cristian A.; Contreras, Paulina Y.; Pérez, Claudia A.; Sobarzo, Marcus; Saldías, Gonzalo S.; Salisbury, Joe

2016-06-01

A combined data set, combining data from field campaigns and oceanographic cruises, was used to ascertain the influence of both river discharges and upwelling processes, covering spatial and temporal variation in dissolved inorganic carbon (DIC) and aragonite saturation state. This work was conducted in one of the most productive river-influenced upwelling areas in the South Pacific coasts (36°S). Additionally, further work was also conducted to ascertain the contribution of different DIC sources, influencing the dynamics of DIC along the land-ocean range. Six sampling campaigns were conducted across seven stations at the Biobío River basin, covering approximately 200 km. Three research cruises were undertaken simultaneously, covering the adjacent continental shelf, including 12 sampling stations for hydrographic measurements. Additionally, six stations were also sampled for chemical analyses, covering summer, winter, and spring conditions over 2010 and 2011. Our results evidenced that seaward extent of the river plume was more evident during the winter field campaign, when highest riverine DIC fluxes were observed. The carbonate system along the river-ocean continuum was very heterogeneous varying over spatial and temporal scales. High DIC and pCO2 were observed in river areas with larger anthropogenic effects. CO2 supersaturation at the river plume was observed during all campaigns due to the influence of low pH river waters in winter/spring and high-pCO2 upwelling waters in summer. δ13CDIC evidenced that main DIC sources along the river and river plume corresponded to the respiration of terrestrial organic matter. We have linked this natural process to the carbonate saturation on the adjacent river-influenced coastal area, suggesting that Ωaragonite undersaturation in surface/subsurface waters is largely modulated by the influence of both river discharge and coastal upwelling events in this productive coastal area. Conditions of low Ωaragonite might impact

Seasonal climatology of hydrographic conditions in the upwelling region off northern Chile

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Blanco, J. L.; Thomas, A. C.; Carr, M.-E.; Strub, P. T.

2001-06-01

Over 30 years of hydrographic data from the northern Chile (18°S-24°S) upwelling region are used to calculate the surface and subsurface seasonal climatology extending 400 km offshore. The data are interpolated to a grid with sufficient spatial resolution to preserve cross-shelf gradients and then presented as means within four seasons: austral winter (July-September), spring (October-December), summer (January-March), and fall (April-June). Climatological monthly wind forcing, surface temperature, and sea level from three coastal stations indicate equatorward (upwelling favorable) winds throughout the year, weakest in the north. Seasonal maximum alongshore wind stress is in late spring and summer (December-March). Major water masses of the region are identified in climatological T-S plots and their sources and implied circulation discussed. Surface fields and vertical transects of temperature and salinity confirm that upwelling occurs year-round, strongest in summer and weakest in winter, bringing relatively fresh water to the surface nearshore. Surface geostrophic flow nearshore is equatorward throughout the year. During summer, an anticyclonic circulation feature in the north which extends to at least 200 m depth is evident in geopotential anomaly and in both temperature and geopotential variance fields. Subsurface fields indicate generally poleward flow throughout the year, strongest in an undercurrent near the coast. This undercurrent is strongest in summer and most persistent and organized in the south (south of 21°S). A subsurface oxygen minimum, centered at ˜250 m, is strongest at lower latitudes. Low-salinity subsurface water intrudes into the study area near 100 m, predominantly in offshore regions, strongest during summer and fall and in the southernmost portion of the region. The climatological fields are compared to features off Baja within the somewhat analogous California Current and to measurements from higher latitudes within the Chile

Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

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J. Etourneau

2012-09-01

Full Text Available The global Late Pliocene/Early Pleistocene cooling (~3.0–2.0 million years ago – Ma concurred with extremely high diatom and biogenic opal production in most of the major coastal upwelling regions. This phenomenon was particularly pronounced in the Benguela upwelling system (BUS, off Namibia, where it is known as the Matuyama Diatom Maximum (MDM. Our study focuses on a new diatom silicon isotope (δ³⁰Si record covering the MDM in the BUS. Unexpectedly, the variations in δ³⁰Si signal follow biogenic opal content, whereby the highest δ³⁰Si values correspond to the highest biogenic opal content. We interpret the higher δ³⁰Si values during the MDM as a result of a stronger degree of silicate utilisation in the surface waters caused by high productivity of mat-forming diatom species. This was most likely promoted by weak upwelling intensity dominating the BUS during the Late Pliocene/Early Pleistocene cooling combined with a large silicate supply derived from a strong Southern Ocean nutrient leakage responding to the expansion of Antarctic ice cover and the resulting stratification of the polar ocean 3.0–2.7 Ma ago. A similar scenario is hypothesized for other major coastal upwelling systems (e.g. off California during this time interval, suggesting that the efficiency of the biological carbon pump was probably sufficiently enhanced in these regions during the MDM to have significantly increased the transport of atmospheric CO₂ to the deep ocean. In addition, the coeval extension of the area of surface water stratification in both the Southern Ocean and the North Pacific, which decreased CO₂ release to the atmosphere, led to further enhanced atmospheric CO₂ drawn-down and thus contributed significantly to Late Pliocene/Early Pleistocene cooling.

Regulation of bacterial sulfate reduction and hydrogen sulfide fluxes in the central Namibian coastal upwelling zone

DEFF Research Database (Denmark)

Bruchert, V.; Jørgensen, BB; Neumann, K.

2003-01-01

The coastal upwelling system off central Namibia is one of the most productive regions of the oceans and is characterized by frequently occurring shelf anoxia with severe effects for the benthic life and fisheries. We present data on water column dissolved oxygen, sulfide, nitrate and nitrite, pore......-depleted bottom waters, the oxygen minimum zone on the continental slope, and the lower continental slope below the oxygen minimum zone. High concentrations of dissolved sulfide, up to 22 mM, in the near-surface sediments of the inner shelf result from extremely high rates of bacterial sulfate reduction...

Response of Mytilus edulis to enhanced phytoplankton availibility by controlled upwelling in an oligographic fjord

NARCIS (Netherlands)

Strohmeier, T.; Strand, Ø.; Alunno-Bruscia, M.; Duinker, A.; Rosland, R.; Jansen, H.M.

2015-01-01

The controlled upwelling of nutrient-rich deep water in oligotrophic coastal regions has been proposed as a means of increasing phytoplankton and, subsequently, bivalve aquaculture production. This was tested as part of a large-scale upwelling experiment in an oligotrophic environment (Lysefjord,

Linking the Modern and Recent Record of Cabo Frio Upwelling with Local Climate and Biogeochemical Processes in Hypersaline Coastal Lagoons, Região dos Lagos, Rio de Janeiro, Brazil

Science.gov (United States)

McKenzie, J. A.; Nascimento, G. S.; Albuquerque, A. L.; Belem, A. L.; Carreira, R.; Eglinton, T. I.; Vasconcelos, C.

2015-12-01

A unique marine and lagoonal system along the coast east of Rio de Janeiro is being investigated to understand the impact of climatic variability on the South Atlantic carbon cycle and biomineralisation processes involved in carbonate precipitation in the hypersaline coastal lagoons. The region is dominated by a semi-arid microclimate attributed to the local coastal upwelling phenomenon near Cabo Frio. The intensity of the upwelling affects the hydrology of the annual water and biogeochemical cycles in the lagoons, as well as biogeochemical signals of environmental change recorded in both onshore and offshore sediments. Preliminary results of δ18O and δD values of water samples collected monthly in Lagoa Vermelha and Brejo do Espinho from 2011 to 2014 show lower values for waters corresponding to the wet season, reflecting increased input of meteoric water. The higher values for waters collected during the dry season reflect the greater amount of evaporation with increased seasonal aridity. Radiocarbon dating of Holocene marine and lagoonal cores indicates that Mg-carbonate precipitation in the lagoons is associated with high evaporation. Modern field observations for the last 3 years suggest that the amount of carbonate precipitation is correlated with evaporitic conditions associated with the upwelling phenomenon. A calibration study of hydrogen isotopic fractionation in the modern lagoons is underway to define a relationship between δDlipid of suspended particles and δDwater of associated water. This isotopic relationship will be applied to material obtained in cores from the lagoons. Offshore cores will be studied using well-tested paleotemperature proxies to evaluate the intensity of the upwelling during the Holocene. In summary, linking the coastal upwelling with the lagoonal hydrology has the potential to furnish important insights about the relationship between the local climate and paleoceanographic circulation associated with the regional carbon cycle.

Variability of coastal water hydrodynamics in the southern Baltic - hindcast modelling of an upwelling event along the Polish coast

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Andrzej Jankowski

2002-12-01

Full Text Available This paper presents the results of an attempt to reproduce, with theaid of a numerical circulation model, the hydrological conditions observedin the coastal area of the southern Baltic in September 1989.A large fall in surface layer seawater temperature was recordedin September 1989 at two coastal stations in the vicinity ofKolobrzeg and Wladyslawowo. This upwelling-like phenomenon was assumed tobe related to the specific anemobaric situation in September 1989,however typical of this phenomenon to occur along the Polish Baltic coast(Malicki & Mietus 1994. A three-dimensional (3-D sigma-coordinatebaroclinic model of the Baltic Sea, with a horizontal resolution of~5 km and 24 sigma-levels in the vertical, was applied to investigatewater circulation and thermohaline variability. Hindcastnumerical simulation showed that the model provided a good reproductionof the temporal history of the surface seawater temperature and theduration of the upwelling-like fall, but that the model results wereunderestimated. The maxima of this large fall in the surface layertemperature at both coastal stations are closely related to the phase ofchange of the upwelling-favourable wind direction to the opposite one.The results of simulation runs showed details of upwelling developmentdue to wind field fluctuations in time and differences in shaping thetemperature and current patterns in conjunction with the variations intopography and coastline features in some areas along the Polish coast.Two different hydrodynamic regimes of water movements along the coastresulting from topographical features (the Slupsk Bank can be distinguished.From the model simulation the specific conditions for the occurrence anddevelopment of upwelling at the eastern end of the Polish coast(in the vicinity of Wladyslawowo can be deduced.

Transport of terrigenous polycyclic aromatic hydrocarbons affected by the coastal upwelling in the northwestern coast of South China Sea.

Science.gov (United States)

Ya, Miaolei; Wu, Yuling; Li, Yongyu; Wang, Xinhong

2017-10-01

Coastal upwelling prevails in the coast of Hainan Island, the northern South China Sea (SCS) during summer. We studied the influences of the upwelling on the horizontal and vertical transport of terrigenous polycyclic aromatic hydrocarbons (PAHs). PAHs in dissolved and suspended particulate phase of water samples were determined in the upper (depth  10 m). PAH levels decreased sharply from inshore to offshore to open sea. The results showed that terrestrial input was the main source of coastal PAHs. Perylene, an important indicator of land plant-derived PAH, showed the significant correlation with PAHs (p sea. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biological response to coastal upwelling and dust deposition in the area off Northwest Africa

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Ohde, T.; Siegel, H.

2010-05-01

Nutrient supply in the area off Northwest Africa is mainly regulated by two processes, coastal upwelling and deposition of Saharan dust. In the present study, both processes were analyzed and evaluated by different methods, including cross-correlation, multiple correlation, and event statistics, using remotely sensed proxies of the period from 2000 to 2008 to investigate their influence on the marine environment. The remotely sensed chlorophyll- a concentration was used as a proxy for the phytoplankton biomass stimulated by nutrient supply into the euphotic zone from deeper water layers and from the atmosphere. Satellite-derived alongshore wind stress and sea-surface temperature were applied as proxies for the strength and reflection of coastal upwelling processes. The westward wind and the dust component of the aerosol optical depth describe the transport direction of atmospheric dust and the atmospheric dust column load. Alongshore wind stress and induced upwelling processes were most significantly responsible for the surface chlorophyll- a variability, accounting for about 24% of the total variance, mainly in the winter and spring due to the strong north-easterly trade winds. The remotely sensed proxies allowed determination of time lags between biological response and its forcing processes. A delay of up to 16 days in the surface chlorophyll- a concentration due to the alongshore wind stress was determined in the northern winter and spring. Although input of atmospheric iron by dust storms can stimulate new phytoplankton production in the study area, only 5% of the surface chlorophyll- a variability could be ascribed to the dust component in the aerosol optical depth. All strong desert storms were identified by an event statistics in the time period from 2000 to 2008. The 57 strong storms were studied in relation to their biological response. Six events were clearly detected in which an increase of chlorophyll- a was caused by Saharan dust input and not by

Variability of Iberian upwelling implied by ERA-40 and ERA-Interim reanalyses

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José M. R. Alves

2013-05-01

Full Text Available The Regional Ocean Modeling System ocean model is used to simulate the decadal evolution of the regional waters in offshore Iberia in response to atmospheric fields given by ECMWF ERA-40 (1961–2001 and ERA-Interim (1989–2008 reanalyses. The simulated sea surface temperature (SST fields are verified against satellite AVHRR SST, and they are analysed to characterise the variability and trends of coastal upwelling in the region. Opposing trends in upwelling frequency are found at the northern limit, where upwelling has been decreasing in recent decades, and at its southern edge, where there is some evidence of increased upwelling. These results confirm previous observational studies and, more importantly, indicate that observed SST trends are not only due to changes in radiative or atmospheric heat fluxes alone but also due to changes in upwelling dynamics, suggesting that such a process may be relevant in climate change scenarios.

Upwelling events, coastal offshore exchange, links to biogeochemical processes - Highlights from the Baltic Sea Science Congress

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Bogdan Ołdakowski

2008-03-01

Full Text Available The Baltic Sea Science Congress was held at Rostock University, Germany, from 19 to 22 March 2007. In the session entitled"Upwelling events, coastal offshore exchange, links to biogeochemical processes" 20 presentations were given,including 7 talks and 13 posters related to the theme of the session.This paper summarises new findings of the upwelling-related studies reported in the session. It deals with investigationsbased on the use of in situ and remote sensing measurements as well as numerical modelling tools. The biogeochemicalimplications of upwelling are also discussed.Our knowledge of the fine structure and dynamic considerations of upwelling has increased in recent decades with the advent ofhigh-resolution modern measurement techniques and modelling studies. The forcing and the overall structure, duration and intensity ofupwelling events are understood quite well. However, the quantification of related transports and the contribution to the overall mixingof upwelling requires further research. Furthermore, our knowledge of the links between upwelling and biogeochemical processes is stillincomplete. Numerical modelling has advanced to the extent that horizontal resolutions of c. 0.5 nautical miles can now be applied,which allows the complete spectrum of meso-scale features to be described. Even the development of filaments can be describedrealistically in comparison with high-resolution satellite data.But the effect of upwelling at a basin scale and possible changes under changing climatic conditions remain open questions.

Patterns of copepod diversity in the Chilean coastal upwelling system

Science.gov (United States)

Hidalgo, Pamela; Escribano, Ruben; Vergara, Odette; Jorquera, Erika; Donoso, Katty; Mendoza, Paula

2010-12-01

The copepod community structure from the Northern and Central/southern upwelling regions off Chile was studied and compared. The derived community descriptors were species abundance (N), species richness (R) and the Shannon-Wiener diversity index (H'). These descriptors were related to distinct habitats and conditions, sea surface temperature (SST) and depth of the upper boundary of the oxygen minimum zone (OMZ). From 159 samples, obtained between 2002 and 2008, a total number of 118 species were found of which the calanoids Paracalanus indicus, Acartia tonsa and Eucalanus inermis, along with the cyclopoid Oithona similis, and the poecilostomatoids Triconia conifera and Oncaea media were the dominant species. H' was higher in the northern region, but no differences in N and R were detected between regions. N was higher in the epipelagic vs the deep habitat, but R and H' did not differ. N, R and H' correlated positively to SST and negatively to OMZ depth. The ascent of the OMZ to the upper layer forced by upwelling was proposed as a mechanism that aggregates and increases copepod diversity in the food-rich photic zone. All these findings suggest a fundamental role of upwelling variation for modulating copepod dynamics and community structure in this highly productive but strongly variable marine ecosystem.

Seasonal and annual variability of coastal sulphur plumes in the northern Benguela upwelling system.

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Thomas Ohde

Full Text Available We investigated the seasonal and annual variability of surface sulphur plumes in the northern Benguela upwelling system off Namibia because of their significant impacts on the marine ecosystem, fishing industry, aquaculture farming and tourism due to their toxic properties. We identified the sulphur plumes in ocean colour satellite data of the medium resolution imaging spectrometer (MERIS for the 2002-2012 time period using the differences in the spectral properties of Namibian Benguela optical water types. The sulphur events have a strong seasonal cycle with pronounced main and off-seasons forced by local and remote-driven processes. The main peak season is in late austral summer and early austral autumn at the beginning of the annual upwelling cycle caused by increasing equatorwards alongshore winds. The sulphur plume activity is high between February and April during the seasonal oxygen minimum associated with the seasonal reduction of cross-shore ventilation of the bottom waters, the seasonal southernmost position of the Angola Benguela Frontal Zone, the seasonal maximum of water mass fractions of South Atlantic and Angola Gyre Central Waters as well as the seasonal arrival of the downwelling coastal trapped waves. The off-season is in austral spring and early austral summer during increased upwelling intensity and enhanced oxygen supply. The annual variability of sulphur events is characterized by very high activities in years 2004, 2005 and 2010 interrupted by periods of lower activity in years 2002 to 2003, 2006 to 2009 and 2011 to 2012. This result can be explained by the relative contributions or adding effects of local and remote-driven forces (from the equatorial area. The probability for the occurrence of sulphur plumes is enhanced in years with a lower annual mean of upwelling intensity, decreased oxygen supply associated with decreased lateral ventilation of bottom waters, more southern position of the Angola Benguela Frontal Zone

Seasonal and annual variability of coastal sulphur plumes in the northern Benguela upwelling system.

Science.gov (United States)

Ohde, Thomas; Dadou, Isabelle

2018-01-01

We investigated the seasonal and annual variability of surface sulphur plumes in the northern Benguela upwelling system off Namibia because of their significant impacts on the marine ecosystem, fishing industry, aquaculture farming and tourism due to their toxic properties. We identified the sulphur plumes in ocean colour satellite data of the medium resolution imaging spectrometer (MERIS) for the 2002-2012 time period using the differences in the spectral properties of Namibian Benguela optical water types. The sulphur events have a strong seasonal cycle with pronounced main and off-seasons forced by local and remote-driven processes. The main peak season is in late austral summer and early austral autumn at the beginning of the annual upwelling cycle caused by increasing equatorwards alongshore winds. The sulphur plume activity is high between February and April during the seasonal oxygen minimum associated with the seasonal reduction of cross-shore ventilation of the bottom waters, the seasonal southernmost position of the Angola Benguela Frontal Zone, the seasonal maximum of water mass fractions of South Atlantic and Angola Gyre Central Waters as well as the seasonal arrival of the downwelling coastal trapped waves. The off-season is in austral spring and early austral summer during increased upwelling intensity and enhanced oxygen supply. The annual variability of sulphur events is characterized by very high activities in years 2004, 2005 and 2010 interrupted by periods of lower activity in years 2002 to 2003, 2006 to 2009 and 2011 to 2012. This result can be explained by the relative contributions or adding effects of local and remote-driven forces (from the equatorial area). The probability for the occurrence of sulphur plumes is enhanced in years with a lower annual mean of upwelling intensity, decreased oxygen supply associated with decreased lateral ventilation of bottom waters, more southern position of the Angola Benguela Frontal Zone, increased mass

A numerical investigation of the atmosphere-ocean thermal contrast over the coastal upwelling region of Cabo Frio, Brazil

Energy Technology Data Exchange (ETDEWEB)

Dourado, M. [Departamento de Meteorologia, Universidade Federal de Pelotas, Pelotas RS (Brazil)]. E-mail: marcelo_dourado@ufpel.edu.br; Pereira de Oliveira, A. [Departamento de Ciencias Atmosfericas, Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, (Brazil)

2008-01-15

An one-dimensional atmospheric second order closure model, coupled to an oceanic mixed layer model, is used to investigate the short term variation of the atmospheric and oceanic boundary layers in the coastal upwelling area of Cabo Frio, Brazil (23 degrees Celsius S, 42 degrees Celsius 08' W). The numerical simulations were carried out to evaluate the impact caused by the thermal contrast between atmosphere and ocean on the vertical extent and other properties of both atmospheric and oceanic boundary layers. The numerical simulations were designed taking as reference the observations carried out during the passage of a cold front that disrupted the upwelling regime in Cabo Frio in July of 1992. The simulations indicated that in 10 hours the mechanical mixing, sustained by a constant background flow of 10 m s-1, increases the atmospheric boundary layer in 214 m when the atmosphere is initially 2 K warmer than the ocean (positive thermal contrast observed during upwelling regime). For an atmosphere initially -2 K colder than the ocean (negative thermal contrast observed during passage of the cold front), the incipient thermal convection intensifies the mechanical mixing increasing the vertical extent of the atmospheric boundary layer in 360 m. The vertical evolution of the atmospheric boundary layer is consistent with the observations carried out in Cabo Frio during upwelling condition. When the upwelling is disrupted, the discrepancy between the simulated and observed atmospheric boundary layer heights in Cabo Frio during July of 1992 increases considerably. During the period of 10 hours, the simulated oceanic mixed layer deepens 2 m and 5.4 m for positive and negative thermal contrasts of 2 K and -2 K, respectively. In the latter case, the larger vertical extent of the oceanic mixed layer is due to the presence of thermal convection in the atmospheric boundary layer, which in turn is associated to the absence of upwelling caused by the passage of cold fronts

Population parameters and the relationships between environmental factors and abundance of the Acetes americanus shrimp (Dendrobranchiata: Sergestidae near a coastal upwelling region of Brazil

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Ana Paula Freitas dos Santos

2015-09-01

Full Text Available AbstractThe population dynamics of Acetes americanus was investigated, focusing on the sex ratio, individual growth, longevity, recruitment and relationship between abundance and environmental factors in the region of Macaé, strongly influenced by coastal upwelling. Otter trawl net samplings were performed from July 2010 to June 2011 at two points (5 m and 15 m. Nearly 19,500 specimens, predominantly females (77.15%, were captured. Their sizes, larger than that of males, indicated sexual dimorphism. Shrimps at lower latitudes present larger sizes and longer longevity than those from higher latitudes. This difference is probably due to low temperatures and high primary productivity. Though no statistical correlation was found between abundance and environmental factors, the species was more abundant in temperatures closer to 20.0º C and in months with high chlorophyll-a levels. Due to the peculiar characteristics of this region, A. americanusshowed greater differences in size and longevity than individuals sampled in other studies undertaken in the continental shelf of Southeast Brazil.

Bacterial and Archaeal Communities Variability Associated with Upwelling and Anthropogenic Pressures in the Protection Area of Arraial do Cabo (Cabo Frio region - RJ).

Science.gov (United States)

Coelho-Souza, Sergio A; Araújo, Fábio V; Cury, Juliano C; Jesus, Hugo E; Pereira, Gilberto C; Guimarães, Jean R D; Peixoto, Raquel S; Dávila, Alberto M R; Rosado, Alexandre S

2015-09-01

Upwelling systems contain a high diversity of pelagic microorganisms and their composition and activity are defined by factors like temperature and nutrient concentration. Denaturing gradient gel electrophoresis (DGGE) technique was used to verify the spatial and temporal genetic variability of Bacteria and Archaea in two stations of the Arraial do Cabo coastal region, one under upwelling pressure and another under anthropogenic pressure. In addition, biotic and abiotic variables were measured in surface and deep waters from three other stations between these stations. Six samplings were done during a year and adequately represented the degrees of upwelling and anthropogenic pressures to the system. Principal Component Analysis (PCA) showed negative correlations between the concentrations of ammonia and phosphorous with prokaryotic secondary production and the total heterotrophic bacteria. PCA also showed negative correlation between temperature and the abundance of prokaryotic cells. Bacterial and archaeal compositions were changeable as were the oceanographic conditions, and upwelling had a regional pressure while anthropogenic pressure was punctual. We suggest that the measurement of prokaryotic secondary production was associated with both Bacteria and Archaea activities, and that substrate availability and temperature determine nutrients cycling.

Alkaline phosphatase activity at the southwest coast of India: A comparison of locations differently affected by upwelling

Science.gov (United States)

Mamatha, S. S.; Malik, Ashish; Varik, Sandesh; Parvathi, V.; Jineesh, V. K.; Gauns, Mangesh U.; LokaBharathi, P. A.

2015-01-01

The realization of the potential importance of phosphorus (P) as a limiting nutrient in marine ecosystem is increasing globally. Hence, the contribution of biotic variables in mobilizing this nutrient would be relevant especially in productive coastal waters. As alkaline phosphatase activity (APA) indicates the status of P for primary production in aquatic environments, we asked the following question: is the level of APA indicative of P sufficiency or deficiency in coastal waters, especially, where upwelling is a regular phenomenon? Therefore, we have examined the total APA, chlorophyll a along with phosphatase producing bacteria (PPB) and related environmental parameters from nearshore to offshore in coastal waters off Trivandrum and Kochi regions differently affected by upwelling during the onset of monsoon. Off Trivandrum, APA in the offshore waters of 5-m layer at 2.23 μM P h- 1 was > 4 times higher than nearshore. Thus, low APA could be indicative of P sufficiency in coastal waters and higher activity suggestive of deficiency in offshore waters off Trivandrum. In contrast, there was less difference in APA between near and offshore surface waters off Kochi. Our results show that the regions differently affected by upwelling respond differently according to ambient P concentration, distance from shore or depth of water. These observations could apparently be applicable to other coastal systems as well, where gradients in upwelling and phosphate runoff have been noticed. Further studies on other transects would throw more light on the extent and direction of the relationship between APA and ambient P concentration. Such studies would help in understanding the level of control of this nutrient on the productivity of coastal waters.

Spatial structure of the zooplankton community in the coastal upwelling system off central-southern Chile in spring 2004 as assessed by automated image analysis

Science.gov (United States)

Manríquez, Karen; Escribano, Ruben; Riquelme-Bugueño, Ramiro

2012-01-01

Size spectra of the mesozooplankton community was studied under the influence of coastal upwelling during austral spring 2004 in the coastal upwelling zone off central-southern Chile. Size spectra were derived from the ZooImage analysis of digitalized zooplankton samples obtained from the upper 200 m during a survey carried out under active upwelling (November 2004). An upwelling filament extended up to 180 km offshore, and the upper boundary of the oxygen minimum zone (1 mL O 2 L -1) varied between 20 m (nearshore) and 300 m depth (oceanic). The community descriptors (slope of the size spectra, size class index, abundance of size classes) were derived from the size spectra. Stepwise multiple regression analysis found significant correlations between these descriptors and oceanographic variables (temperature, dissolved oxygen, chlorophyll-a, OMZ depth). These data suggest an upwelling-dependent zooplankton distribution characterized by aggregations in a mid-shelf zone, where the log-normalized size spectra become flatter due to an increased abundance of larger size classes (>3 mm). In contrast, the inshore and offshore zones were dominated by small (zone coincided with moderate levels of chlorophyll-a (ca. 1 μg L -1) and the OMZ depth near 200 m. These spatial patterns and slopes of the size spectra however, were subjected to a significant day vs. night effect mostly explained by the diel vertical migration of the euphausiid Euphausia mucronata. This migration can descend below 200 m during the daylight, causing the larger size classes to disappear from the size spectrum and resulting in a steeper slope. Time-dependent effects must, therefore, be considered when examining the spatial patterns of zooplankton in coastal upwelling zones.

Mussel farming impact on pelagic production and respiration rates in a coastal upwelling embayment (Ría de Vigo, NW Spain)

Science.gov (United States)

Froján, María; Castro, Carmen G.; Zúñiga, Diana; Arbones, Belén; Alonso-Pérez, Fernando; Figueiras, Francisco G.

2018-05-01

This paper provides the first diagnosis of the impact of mussel farming on the primary production (PP) and the metabolic balance in a coastal upwelling region (Ría de Vigo). Measurements of size-fractionated PP and microbial plankton metabolism were performed outside (reference station; ReS) and inside the farming area (raft station; RaS). At ReS, integrated PP was higher during upwelling (1.05 ± 0.45 g C m-2 d-1) with microphytoplankton dominating carbon fixation (74 ± 14%). The significance of nanophytoplankton and picophytoplankton increased during winter linked to lower PP (0.24 ± 0.03 g C m-2 d-1). Water column at ReS was always autotrophic with net community production (NCP) ranging from 186 ± 67 mmol O2 m-2 d-1 during upwelling to 43 ± 22 mmol O2 m-2 d-1 in winter. At RaS, there was a decrease in PP attributable not only to mussel consumption but also to the lower irradiance under mussel rafts. Concomitant decrease in NCP was also observed (by 56%), yet remained autotrophic, supporting the view that under current conditions food does not limit mussel growth in the Ría, thus securing the carrying capacity of the system in terms of production.

Biological consequences of environmental changes related to coastal upwelling: a simulation study

Energy Technology Data Exchange (ETDEWEB)

Howe, S.O.

1979-05-01

Two simulation models of marine ecosystem dynamics are formulated and applied to field data. The first is a time-dependent model of phytoplankton growth in nutrient-enriched batch cultures where spatial gradients of dependent variables and the effects of higher tropic level processes are not included. Rates of photosynthesis, nutrient uptake, chlorophyll synthesis and cell division for a single phytoplankton functional group are simulated as functions of photosynthetically active solar radiation, dissolved nutrient concentrations and cell quotas of carbon, nitrogen and silica. The second model combines the phytoplankton growth model with a time dependent, two-dimensional model of coastal upwelling off northwest Africa.

Spatiotemporal variation of vertical particle fluxes and modelled chlorophyll a standing stocks in the Benguela Upwelling System

Science.gov (United States)

Vorrath, Maria-Elena; Lahajnar, Niko; Fischer, Gerhard; Libuku, Viktor Miti; Schmidt, Martin; Emeis, Kay-Christian

2018-04-01

Marine particle fluxes from high productive coastal upwelling systems return upwelled CO2 and nutrients to the deep ocean and sediments and have a substantial impact on the global carbon cycle. This study examines relations between production regimes on the shelf and over the continental margin of the Benguela Upwelling System (BUS) in the SE Atlantic Ocean. Data of composition and timing of vertical particle flux come from sediment trap time series (deployed intermittently between 1988 and 2014) in the regions Walvis Ridge, Walvis Bay, Luederitz and Orange River. We compare their seasonal variability to modelled patterns of chlorophyll concentrations in a 3-D ecosystem model. Both modelled seasonal chlorophyll a standing stocks and sampled particle flux patterns are highly correspondent with a bimodal seasonal cycle offshore the BUS. The material in the particle flux in offshore traps is dominantly carbonate (40-70%), and flux peaks in offshore particle flux originate from two independent events: in austral autumn thermocline shoaling and vertical mixing are decoupled from coastal upwelling, while fluxes in spring coincide with the upwelling season, indicated by slightly elevated biogenic opal values at some locations. Coastal particle fluxes are characterized by a trimodal pattern and are dominated by biogenic opal (22-35%) and organic matter (30-60%). The distinct seasonality in observed fluxes on the shelf is caused by high variability in production, sinking behaviour, wind stress, and hydrodynamic processes. We speculate that global warming will increase ocean stratification and alter coastal upwelling, so that consequences for primary production and particle flux in the BUS are inevitable.

Near-surface temperature gradient in a coastal upwelling regime

Science.gov (United States)

Maske, H.; Ochoa, J.; Almeda-Jauregui, C. O.; Ruiz-de la Torre, M. C.; Cruz-López, R.; Villegas-Mendoza, J. R.

2014-08-01

In oceanography, a near homogeneous mixed layer extending from the surface to a seasonal thermocline is a common conceptual basis in physics, chemistry, and biology. In a coastal upwelling region 3 km off the coast in the Mexican Pacific, we measured vertical density gradients with a free-rising CTD and temperature gradients with thermographs at 1, 3, and 5 m depths logging every 5 min during more than a year. No significant salinity gradient was observed down to 10 m depth, and the CTD temperature and density gradients showed no pronounced discontinuity that would suggest a near-surface mixed layer. Thermographs generally logged decreasing temperature with depth with gradients higher than 0.2 K m-1 more than half of the time in the summer between 1 and 3 m, 3 and 5 m and in the winter between 1 and 3 m. Some negative temperature gradients were present and gradients were generally highly variable in time with high peaks lasting fractions of hours to hours. These temporal changes were too rapid to be explained by local heating or cooling. The pattern of positive and negative peaks might be explained by vertical stacks of water layers of different temperatures and different horizontal drift vectors. The observed near-surface gradient has implications for turbulent wind energy transfer, vertical exchange of dissolved and particulate water constituents, the interpretation of remotely sensed SST, and horizontal wind-induced transport.

The physical structure of an upwelling filament off the North-west ...

African Journals Online (AJOL)

... in dispersal of material originating in the region of active coastal upwelling. The location of the filament studied appears repeatable from year to year, suggestive of a strong relation with the topographically trapped eddy, which was situated downstream of a lateral ridge between the. Canary Islands and the African coast.

Does mesoscale matters in decadal changes observed in the northern Canary upwelling system?

Science.gov (United States)

Relvas, P.; Luís, J.; Santos, A. M. P.

2009-04-01

upwelling pattern is clearly reflected in the warming field. There, the coastal upwelled waters show a weak warming trend when compared with the offshore waters. If we assume that the SST contrast between coastal and offshore waters is a proxy for the upwelling intensity, then this fact suggests the enhancement of the upwelling regime off SW Iberia since 1985. Although the seasonal nature of the upwelling in the region, the strengthening must be significant since it leaves a coherent imprint in the annual warming field. An analysis done on a monthly basis reveals that the central months of the classical upwelling season (July to September) are the responsible for this coherent mesoscale structure observed in the warming field off SW Iberia. The same conclusions are not clear for the mesoscale structure further north, where no significant differences are observed between the coastal and offshore warming rates. To investigate if our results, obtained for the period with satellite coverage (1985-2007), could be extended or not until 1960, we computed an upwelling index as the SST difference between coastal and offshore ICOADS SST. The analysis revealed that the trends are different whether we consider the whole time series or only the period investigated with the satellite imagery. We can suppose a relatively unchanged upwelling regime if we consider the period 1960-2005, but a rapid increase of intensity if we consider the period from 1985 onwards, particularly in the most southern regions, in agreement with the satellite imagery analysis. Our present results point out that mesoscale activity can account for larger changes in local SST than global average trends. In Eastern Boundary Upwelling Systems, where mesoscale structures play a major role in the description of the upwelling regime, to rely on sparse spatial observations to hypothesize about the decadal behaviour of the upwelling intensity at the basin scale may be questionable.

Combined impact of ocean acidification and corrosive waters in a river-influenced coastal upwelling area off Central Chile

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Vargas, C.; De La Hoz, M.; San Martin, V.; Contreras, P.; Navarro, J. M.; Lagos, N. A.; Lardies, M.; Manríquez, P. H.; Torres, R.

2012-12-01

Elevated CO2 in the atmosphere promotes a cascade of physical and chemical changes affecting all levels of biological organization, and the evidence from local to global scales has shown that such anthropogenic climate change has triggered significant responses in the Earth's biota. The increased concentration of CO2 is likely to cause a corresponding increase in ocean acidification (OA). In addition, economically valuable shellfish species predominantly inhabit coastal regions both in natural stocks and/or in managed stocks and farming areas. Many coastal ecosystems may experience seawater pCO2 levels significantly higher than expected from equilibrium with the atmosphere, which in this case are strongly linked to biological processes and/or the impact of two important processes; river plumes and coastal upwelling events, which indeed interplay in a very dynamic way on continental shelves, resulting in both source or sink of CO2 to the atmosphere. Coastal ecosystems receive persistent acid inputs as a result of freshwater discharges from river basins into the coastal domain. In this context, since shellfish resources and shellfish aquaculture activities predominantly occur in nearshore areas, it is expected that shellfish species inhabiting river-influenced benthic ecosystems will be exposed persistently to acidic conditions that are suboptimal for its development. In a wider ecological context, little is also known about the potential impacts of acid waters on the performance of larvae and juveniles of almost all the marine species inhabiting this benthic ecosystem in Eastern Southern Pacific Ocean. We present here the main results of a research study aimed to investigate the environmental conditions to which economically valuable calcifiers shellfish species are exposed in a river-influenced continental shelf off Central Chile. By using isotopic measurements in the dissolved inorganic carbon (DIC) pool (d13C-DIC) we showed the effect of the remineralization of

Microbial and biogeochemical responses to projected future nitrate enrichment in the California upwelling system

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Katherine Rose Marie Mackey

2014-11-01

Full Text Available Coastal California is a dynamic upwelling region where nitrogen (N and iron (Fe can both limit productivity and influence biogeochemistry over different spatial and temporal scales. With global change, the flux of nitrate from upwelling is expected to increase over the next century, potentially driving additional oceanic regions toward Fe limitation. In this study we explored the effect of changes in Fe/N ratio on native phytoplankton from five currently Fe-replete sites near the major California upwelling centers at Bodega Bay and Monterey Bay using nutrient addition incubation experiments. Despite the high nitrate levels (13-30 M in the upwelled water, phytoplankton at three of the five sites showed increased growth when 10 M nitrate was added. None of the sites showed enhanced growth following addition of 10 nM Fe. Nitrate additions favored slow sinking single-celled diatoms over faster sinking chain-forming diatoms, suggesting that future increases in nitrate flux could affect carbon and silicate export and alter grazer populations. In particular, solitary cells of Cylindrotheca were more abundant than the toxin-producing genus Pseudonitzschia following nitrate addition. These responses suggest the biogeochemistry of coastal California could change in response to future increases in nitrate, and multiple stressors like ocean acidification and hypoxia may further result in ecosystem shifts.

A Lagrangian study tracing water parcel origins in the Canary Upwelling System

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Evan Mason

2012-08-01

Full Text Available The regional ocean circulation within the Canary Upwelling System between 31°N and 35°N is studied using numerical tools. Seasonal mean and near-instantaneous velocity fields from a previously-generated climatological Regional Ocean Modelling System (ROMS solution of the Canary Basin are used to force a series of offline Lagrangian particle-tracking experiments. The primary objective is to identify the pathways through which water parcels arrive at the upwelling region north of Cape Ghir. Examining year-long pathways, the Azores Current contributes over 80% of particles annually, of which a large proportion arrive directly from offshore (from the northwest, while others travel along the shelf and slope from the Gulf of Cadiz. The remaining ~20% originate within the Gulf of Cadiz or come from the south, although the southern contribution is only significant in autumn and winter. When season-long pathways are considered, the alongshore contributions become increasingly important: northern contributions reach 40% in spring and summer, while southern values exceed 35% in winter. This study also shows that coastal upwelling changes both spatially and temporally. Upwelling becomes intensified near Cape Beddouza, with most upwelling occurring within ~40 km from shore although significant values may reach as far as 120 km offshore north of Cape Beddouza; at these locations the offshore integrated upwelling reaches as much as 4 times the offshore Ekman transport. In the Cape Beddouza area (32°N to 33°N, upwelling is negligible in February but intensifies in autumn, reaching as much as 3 times the offshore Ekman transport.

Spatio-temporal variability of upwelling along the southwest coast of India based on satellite observations

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Jayaram, Chiranjivi; Kumar, P. K. Dinesh

2018-03-01

Upwelling phenomenon along the eastern boundaries of global ocean has received greater attention in the recent times due to its environmental and economic significance in the global warming and the scenario of changing climate as opined by IPCC AR5. In this context, the availabile satellite data on sea surface winds, sea surface temperature (SST), sea level anomaly (SLA) and chlorophyll-a concentration (Chl-a), for the period 1981-2016 were analyzed to identify the coastal upwelling pattern in the Southeastern Arabian Sea (SEAS). Synergistic approach, using winds, SST, SLA and Chl-a revealed that strong upwelling was prevailing between 8°N and 12°N. During the study period, geographical differences existed in the peak values of upwelling favorable conditions considered for study. Analysis of the alongshore winds which are conducive for upwelling were observed to be curtailed towards the northern part of the study region between 2005 and 2010. Also, the strength of upwelling reduced during the strong ENSO years of 1997 and 2015. Linear regression based trend analysis of upwelling indices like Ekman transport, SST and chlorophyll along the coast, during the upwelling period, revealed slight increase in the strength towards the southern region while it decreased to the north during the study period.

Temporal variability and phylogenetic characterization of planktonic anammox bacteria in the coastal upwelling ecosystem off central Chile

Science.gov (United States)

Galán, Alexander; Molina, Verónica; Belmar, Lucy; Ulloa, Osvaldo

2012-01-01

The phylogenetic affiliation and temporal variability in the abundance of planktonic anammox bacteria were studied at a time-series station above the continental shelf off central Chile (∼36°S; bottom depth 93 m), a wind-driven, seasonal upwelling area, between August 2006 and April 2008. The study was carried out by cloning and sequencing the 16S rRNA gene and by using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Our results showed the presence of a single anammox bacteria-like ribotype during both upwelling and non-upwelling seasons, which was phylogenetically associated with a recently described oxygen-minimum-zone subcluster within the Candidatus Scalindua clade. Moreover, clear differences were observed in the temporal and vertical distribution of anammox cells. During the upwelling season (austral spring-summer), relatively high abundances (∼5500 cells mL -1) and large cells (0.8 μm 3-75.7 fg C cell -1) were found below 20 m depth. In contrast, during the non-upwelling season (austral fall-winter), lower abundances (∼600 cells mL -1) and smaller cells (0.1 μm 3-22.8 fg C cell -1) were found, predominantly associated with the bottom layer. Overall, our results indicate that the abundance and vertical distribution of anammox planktonic assemblages are related to the occurrence of seasonal, wind-driven, coastal upwelling, which in turn appears to offer favorable conditions for the development of these microorganisms. The dominance of a unique anammox bacteria-like ribotype could be related to the high environmental variability observed in the system, which prevents the establishment of other anammox lineages.

Insights into the Microbial and Viral Dynamics of a Coastal Downwelling-Upwelling Transition.

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Gustavo Bueno Gregoracci

Full Text Available Although previous studies have described opposing states in upwelling regions, i.e., the rise of cold nutrient-rich waters and prevalence of surface warm nutrient-poor waters, few have addressed the transition from one state to the other. This study aimed to describe the microbial and viral structure during this transition and was able to obtain the taxonomic and metabolic compositions as well as physical-chemical data. This integrated approach allowed for a better understanding of the dynamics of the downwelling upwelling transition, suggesting that a wealth of metabolic processes and ecological interactions are occurring in the minute fractions of the plankton (femto, pico, nano. These processes and interactions included evidence of microbial predominance during downwelling (with nitrogen recycling and aerobic anoxygenic photosynthesis, different viral predation pressures over primary production in different states (cyanobacteria vs eukaryotes, and a predominance of diatoms and selected bacterial and archaeal groups during upwelling (with the occurrence of a wealth of nitrogen metabolism involving ammonia. Thus, the results provided insights into which microbes, viruses and microbial-mediated processes are probably important in the functioning of upwelling systems.

Dynamics of a "low-enrichment high-retention" upwelling center over the southern Senegal shelf

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Ndoye, Siny; Capet, Xavier; Estrade, Philippe; Sow, Bamol; Machu, Eric; Brochier, Timothée.; Döring, Julian; Brehmer, Patrice

2017-05-01

Senegal is the southern tip of the Canary upwelling system. Its coastal ocean hosts an upwelling center which shapes sea surface temperatures between latitudes 12° and 15°N. Near this latter latitude, the Cape Verde headland and a sudden change in shelf cross-shore profile are major sources of heterogeneity in the southern Senegal upwelling sector (SSUS). SSUS dynamics is investigated by means of Regional Ocean Modeling System simulations. Configuration realism and resolution (Δx≈ 2 km) are sufficient to reproduce the SSUS frontal system. Our main focus is on the 3-D upwelling circulation which turns out to be profoundly different from 2-D theory: cold water injection onto the shelf and upwelling are strongly concentrated within a few tens of kilometers south of Cape Verde and largely arise from flow divergence in the alongshore direction; a significant fraction of the upwelled waters are retained nearshore over long distances while travelling southward under the influence of northerly winds. Another source of complexity, regional-scale alongshore pressure gradients, also contributes to the overall retention of upwelled waters over the shelf. Varying the degree of realism of atmospheric and oceanic forcings does not appreciably change these conclusions. This study sheds light on the dynamics and circulation underlying the recurrent sea surface temperature pattern observed during the upwelling season and offers new perspectives on the connections between the SSUS physical environment and its ecosystems. It also casts doubt on the validity of upwelling intensity estimations based on simple Ekman upwelling indices at such local scales.

Spatial and temporal variability in coccolithophore abundance and distribution in the NW Iberian coastal upwelling system

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B. Ausín

2018-01-01

Full Text Available A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42° N. Total coccosphere abundance was higher at the outer-shelf station, where warmer, nutrient-depleted waters favoured coccolithophore rather than phytoplanktonic diatom blooms, which are known to dominate the inner-shelf location. In seasonal terms, higher coccosphere and coccolith abundances were registered at both stations during upwelling seasons, coinciding with high irradiance levels. This was typically in conjunction with stratified, nutrient-poor conditions (i.e. relaxing upwelling conditions. However, it also occurred during some upwelling events of colder, nutrient-rich subsurface waters onto the continental shelf. Minimum abundances were generally found during downwelling periods, with unexpectedly high coccolith abundance registered in subsurface waters at the inner-shelf station. This finding can only be explained if strong storms during these downwelling periods favoured resuspension processes, thus remobilizing deposited coccoliths from surface sediments, and hence hampering the identification of autochthonous coccolithophore community structure. At both locations, the major coccolithophore assemblages were dominated by Emiliania huxleyi, small Gephyrocapsa group, Gephyrocapsa oceanica, Florisphaera profunda, Syracosphaera spp., Coronosphaera mediterranea, and Calcidiscus leptoporus. Ecological preferences of the different taxa were assessed by exploring the relationships between environmental conditions and temporal and vertical variability in coccosphere abundance. These findings provide relevant information for the use of fossil coccolith assemblages in marine sediment records, in order to infer past

Spatial and temporal variability in coccolithophore abundance and distribution in the NW Iberian coastal upwelling system

Science.gov (United States)

Ausín, Blanca; Zúñiga, Diana; Flores, Jose A.; Cavaleiro, Catarina; Froján, María; Villacieros-Robineau, Nicolás; Alonso-Pérez, Fernando; Arbones, Belén; Santos, Celia; de la Granda, Francisco; Castro, Carmen G.; Abrantes, Fátima; Eglinton, Timothy I.; Salgueiro, Emilia

2018-01-01

A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42° N. Total coccosphere abundance was higher at the outer-shelf station, where warmer, nutrient-depleted waters favoured coccolithophore rather than phytoplanktonic diatom blooms, which are known to dominate the inner-shelf location. In seasonal terms, higher coccosphere and coccolith abundances were registered at both stations during upwelling seasons, coinciding with high irradiance levels. This was typically in conjunction with stratified, nutrient-poor conditions (i.e. relaxing upwelling conditions). However, it also occurred during some upwelling events of colder, nutrient-rich subsurface waters onto the continental shelf. Minimum abundances were generally found during downwelling periods, with unexpectedly high coccolith abundance registered in subsurface waters at the inner-shelf station. This finding can only be explained if strong storms during these downwelling periods favoured resuspension processes, thus remobilizing deposited coccoliths from surface sediments, and hence hampering the identification of autochthonous coccolithophore community structure. At both locations, the major coccolithophore assemblages were dominated by Emiliania huxleyi, small Gephyrocapsa group, Gephyrocapsa oceanica, Florisphaera profunda, Syracosphaera spp., Coronosphaera mediterranea, and Calcidiscus leptoporus. Ecological preferences of the different taxa were assessed by exploring the relationships between environmental conditions and temporal and vertical variability in coccosphere abundance. These findings provide relevant information for the use of fossil coccolith assemblages in marine sediment records, in order to infer past environmental conditions, of

Improving the Remote Sensing Retrieval of Phytoplankton Functional Types (PFT Using Empirical Orthogonal Functions: A Case Study in a Coastal Upwelling Region

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Marco Correa-Ramirez

2018-03-01

Full Text Available An approach that improves the spectral-based PHYSAT method for identifying phytoplankton functional types (PFT in satellite ocean-color imagery is developed and applied to one study case. This new approach, called PHYSTWO, relies on the assumption that the dominant effect of chlorophyll-a (Chl-a in the normalized water-leaving radiance (nLw spectrum can be effectively isolated from the signal of accessory pigment biomarkers of different PFT by using Empirical Orthogonal Function (EOF decomposition. PHYSTWO operates in the dimensionless plane composed by the first two EOF modes generated through the decomposition of a space–nLw matrix at seven wavelengths (412, 443, 469, 488, 531, 547, and 555 nm. PFT determination is performed using orthogonal models derived from the acceptable ranges of anomalies proposed by PHYSAT but adjusted with the available regional and global data. In applying PHYSTWO to study phytoplankton community structures in the coastal upwelling system off central Chile, we find that this method increases the accuracy of PFT identification, extends the application of this tool to waters with high Chl-a concentration, and significantly decreases (~60% the undetermined retrievals when compared with PHYSAT. The improved accuracy of PHYSTWO and its applicability for the identification of new PFT are discussed.

Impact of Equatorial Waves on the Variability of Upwelling Process Along West Coast of India

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Prakash, K. R.; Nigam, T.; Pant, V.

2017-12-01

Coastal upwelling is a seasonal phenomenon along the south eastern Arabian Sea (SEAS) due to favourable wind setup during Indian Summer Monsoon Season (June-September). This upwelling brings subsurface cold and nutrient rich water to the surface layers. The cold water transported northward by the altered along shore current of west coast of India in the post-monsoon season. The different climatological forcing of positive Indian Ocean Dipole (IOD) and normal years were utilised to simulate the upwelling off the west coast of India using a three dimensional Regional Ocean Modelling System (ROMS). Strength of upwelling and the northward transport were found to be weaken for positive IOD simulations as compared to normal years. Analysis suggests that the meridional wind stress weakening resulted into a decrease in strength of West India Coastal Current (WICC) and, therefore, reduced magnitude of offshore Ekman transport. The mixed layer heat budget calculation also supports the findings by showing dominated vertical process in comparison to net heat flux effect. The post-monsoon northward transport of cold water was found to be correlated with the coastally trapped downwelling Kelvin waves. These waves are the only remote forcing from the Bay of Bengal that reaches to the south-eastern Arabian Sea during the months of October-December. The composite of sea surface height anomalies for the positive IOD and normal years shows that the downwelling Kelwin wave was absent during October-December.

Upwelling characteristics in the Gulf of Finland (Baltic Sea) as revealed by Ferrybox measurements in 2007-2013

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Kikas, Villu; Lips, Urmas

2016-07-01

Ferrybox measurements have been carried out between Tallinn and Helsinki in the Gulf of Finland (Baltic Sea) on a regular basis since 1997. The system measures autonomously water temperature, salinity, chlorophyll a fluorescence and turbidity and takes water samples for further analyses at a predefined time interval. We aimed to show how the Ferrybox technology could be used to study the coastal upwelling events in the Gulf of Finland. Based on the introduced upwelling index and related criteria, 33 coastal upwelling events were identified in May-September 2007-2013. The number of events, as well as the frequency of their occurrence and intensity expressed as a sum of daily average temperature deviations in the 20 km wide coastal area, were almost equal near the northern and southern coasts. Nevertheless, the wind impulse, which was needed to generate upwelling events of similar intensity, differed between the northern and southern coastal areas. It is suggested that the general thermohaline structure adapted to the prevailing forcing and the estuarine character of the basin weaken the upwelling created by the westerly to southwesterly (up-estuary) winds and strengthen the upwelling created by the easterly to northeasterly (down-estuary) winds. Two types of upwelling events were identified - one characterized by a strong temperature front and the other revealing gradual decrease in temperature from the open sea to the coastal area, with maximum temperature deviation close to the shore.

Surface circulation and upwelling patterns around Sri Lanka

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de Vos, A.; Pattiaratchi, C. B.; Wijeratne, E. M. S.

2013-09-01

Sri Lanka occupies a unique location within the equatorial belt in the northern Indian Ocean with the Arabian Sea on its western side and the Bay of Bengal on its eastern side. The region is characterised by bi-annually reversing monsoon winds resulting from seasonal differential heating and cooling of the continental land mass and the ocean. This study explored elements of the dynamics of the surface circulation and coastal upwelling in the waters around Sri Lanka using satellite imagery and the Regional Ocean Modelling System (ROMS) configured to the study region and forced with ECMWF interim data. The model was run for 2 yr to examine the seasonal and shorter term (∼10 days) variability. The results confirmed the presence of the reversing current system in response to the changing wind field: the eastward flowing Southwest Monsoon Current (SMC) during the Southwest (SW) monsoon transporting 11.5 Sv and the westward flowing Northeast Monsoon Current (NMC) transporting 9.5 Sv during the Northeast (NE) monsoon, respectively. A recirculation feature located to the east of Sri Lanka during the SW monsoon, the Sri Lanka Dome, is shown to result from the interaction between the SMC and the Island of Sri Lanka. Along the eastern and western coasts, during both monsoon periods, flow is southward converging along the south coast. During the SW monsoon the Island deflects the eastward flowing SMC southward whilst along the east coast the southward flow results from the Sri Lanka Dome recirculation. The major upwelling region, during both monsoon periods, is located along the south coast and is shown to be due to flow convergence and divergence associated with offshore transport of water. Higher surface chlorophyll concentrations were observed during the SW monsoon. The location of the flow convergence and hence the upwelling centre was dependent on the relative strengths of wind driven flow along the east and west coasts: during the SW (NE) monsoon the flow along the

Shift in the species composition of the diatom community in the eutrophic Mauritanian coastal upwelling: Results from a multi-year sediment trap experiment (2003-2010)

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Romero, Oscar E.; Fischer, Gerhard

2017-12-01

A multiannual, continuous sediment trap experiment was conducted at the mooring site CBeu (Cape Blanc eutrophic, ca. 20 °N, ca. 18 °W; trap depth = 1256-1296 m) in the high-productive Mauritanian coastal upwelling. Here we present fluxes and the species-specific composition of the diatom assemblage, and fluxes of biogenic silica (BSi, opal) and total organic carbon (TOC) for the time interval June 2003-Feb 2010. Flux ranges of studied parameters are (i) total diatoms = 1.2 ∗ 108-4.7 ∗ 104 valves m-2 d-1 (average = 5.9 × 106 valves ± 1.4 × 107); (ii) BSi = 296-0.5 mg m-2 d-1 (average = 41.1 ± 53.5 mg m-2 d-1), and (iii) TOC = 97-1 mg m-2 d-1 (average = 20.5 ± 17.8 mg m-2 d-1). Throughout the experiment, the overall good match of total diatom, BSi and TOC fluxes is reasonably consistent and reflects well the temporal occurrence of the main Mauritanian upwelling season. Spring and summer are the most favorable seasons for diatom production and sedimentation: out of the recorded 14 diatom maxima of different magnitude, six occurred in spring and four in summer. The diverse diatom community at site CBeu is composed of four main assemblages: benthic, coastal upwelling, coastal planktonic and open-ocean diatoms, reflecting different productivity conditions and water masses. A striking feature of the temporal variability of the diatom populations is the persistent pattern of seasonal groups' contribution: benthic and coastal upwelling taxa dominated during the main upwelling season in spring, while open-ocean diatoms were more abundant in fall and winter, when the upper water column becomes stratified, upwelling relaxes and productivity decreases. The relative abundance of benthic diatoms strongly increased after 2006, yet their spring-summer contribution remained high until the end of the trap experiment. The occurrence of large populations of benthic diatoms at the hemipelagic CBeu site is interpreted to indicate transport from shallow waters via nepheloid

Using CAM3 and the Alkenone Method to Understand how Pliocene SST's Affect California and Other Climates Adjacent to Upwelling Regions

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Searles, Z. A.; Otto-Bliesner, B. L.; Rosenbloom, N. A.; Dekens, P. S.

2008-12-01

The Intergovernmental Panel on Climate Change fourth assessment report established with 90% confidence that anthropogenic climate change will result in a warmer world. In order to more fully understand possible future climate, past analogues of warm periods should be analyzed. The early Pliocene is an appropriate analogue because the continental configuration was similar to today and CO2 levels were comparable to present (~100ppm higher than pre-anthropogenic levels). This project has two objectives: 1.To test the atmospheric sensitivity to USGS PRISM2 dataset revised to better approximate proxy data indicating warmer SST's in upwelling regions and 2. To provide early-Pliocene (2.7- 3.5 Ma) SST estimates for ODP site 1018 on the California Margin (36°59.4'N, 123°16.5'W) using the UK'37 SST proxy. Recent UK'37 proxy data reveals that PRISM2 underestimates SST's in Pacific and Atlantic coastal upwelling regions. The sensitivity of the atmosphere to significantly warmer SST's in upwelling regions was tested using the National Center for Atmospheric Research (NCAR) Community Atmospheric Model, version 3 (CAM3). Initial conditions were supplied by the USGS PRISM2 project and include Pliocene SST's, vegetation cover, sea level height, topography, marine and continental ice extent. Pliocene SST's along the Californian, Peruvian, North African and South African margin were modified to reflect proxy observations from 4 sites. The lack of observational coverage (1 data point per region) required interpolation of the areal extent of the SST warming anomaly indicated by the proxies. Experiment results show increased cumulative precipitation and humidity in regions where the original PRISM2 predicted drying. The predicted North American increase in precipitation is in better agreement with geologic proxies indicating wetter conditions. Warmer SST's also causes weaker wind velocities along the North American, Peruvian, and North African margins, and stronger winds along the

Meteorological constraints on oceanic halocarbons above the Peruvian upwelling

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S. Fuhlbrügge

2016-09-01

Full Text Available During a cruise of R/V METEOR in December 2012 the oceanic sources and emissions of various halogenated trace gases and their mixing ratios in the marine atmospheric boundary layer (MABL were investigated above the Peruvian upwelling. This study presents novel observations of the three very short lived substances (VSLSs – bromoform, dibromomethane and methyl iodide – together with high-resolution meteorological measurements, Lagrangian transport and source–loss calculations. Oceanic emissions of bromoform and dibromomethane were relatively low compared to other upwelling regions, while those for methyl iodide were very high. Radiosonde launches during the cruise revealed a low, stable MABL and a distinct trade inversion above acting as strong barriers for convection and vertical transport of trace gases in this region. Observed atmospheric VSLS abundances, sea surface temperature, relative humidity and MABL height correlated well during the cruise. We used a simple source–loss estimate to quantify the contribution of oceanic emissions along the cruise track to the observed atmospheric concentrations. This analysis showed that averaged, instantaneous emissions could not support the observed atmospheric mixing ratios of VSLSs and that the marine background abundances below the trade inversion were significantly influenced by advection of regional sources. Adding to this background, the observed maximum emissions of halocarbons in the coastal upwelling could explain the high atmospheric VSLS concentrations in combination with their accumulation under the distinct MABL and trade inversions. Stronger emissions along the nearshore coastline likely added to the elevated abundances under the steady atmospheric conditions. This study underscores the importance of oceanic upwelling and trade wind systems on the atmospheric distribution of marine VSLS emissions.

Meteorological constraints on oceanic halocarbons above the Peruvian upwelling

Science.gov (United States)

Fuhlbrügge, Steffen; Quack, Birgit; Atlas, Elliot; Fiehn, Alina; Hepach, Helmke; Krüger, Kirstin

2016-09-01

During a cruise of R/V METEOR in December 2012 the oceanic sources and emissions of various halogenated trace gases and their mixing ratios in the marine atmospheric boundary layer (MABL) were investigated above the Peruvian upwelling. This study presents novel observations of the three very short lived substances (VSLSs) - bromoform, dibromomethane and methyl iodide - together with high-resolution meteorological measurements, Lagrangian transport and source-loss calculations. Oceanic emissions of bromoform and dibromomethane were relatively low compared to other upwelling regions, while those for methyl iodide were very high. Radiosonde launches during the cruise revealed a low, stable MABL and a distinct trade inversion above acting as strong barriers for convection and vertical transport of trace gases in this region. Observed atmospheric VSLS abundances, sea surface temperature, relative humidity and MABL height correlated well during the cruise. We used a simple source-loss estimate to quantify the contribution of oceanic emissions along the cruise track to the observed atmospheric concentrations. This analysis showed that averaged, instantaneous emissions could not support the observed atmospheric mixing ratios of VSLSs and that the marine background abundances below the trade inversion were significantly influenced by advection of regional sources. Adding to this background, the observed maximum emissions of halocarbons in the coastal upwelling could explain the high atmospheric VSLS concentrations in combination with their accumulation under the distinct MABL and trade inversions. Stronger emissions along the nearshore coastline likely added to the elevated abundances under the steady atmospheric conditions. This study underscores the importance of oceanic upwelling and trade wind systems on the atmospheric distribution of marine VSLS emissions.

Diversity and Transcriptional Levels of RuBisCO Form II of Sulfur-Oxidizing γ-Proteobacteria in Coastal-Upwelling Waters with Seasonal Anoxia

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Bárbara Léniz

2017-07-01

Full Text Available Seasonal wind-driven upwelling, high primary production in surface waters, and oxygen deficiency in subsurface waters characterize the coastal ecosystem of the subtropical eastern South Pacific (ESP, and shape the nature and dynamics of the microbial community structure and function. We investigated the diversity, abundance, and transcriptional levels of the gene encoding the large subunit form II of the RuBisCO enzyme (cbbM in the pelagic microbial community at a continental-shelf site off central Chile over 2 years. We focused on cbbM genes affiliated with the sulfur-oxidizing γ-proteobacteria cluster, whose members are known to dominate in oxygen-deficient marine environments and are highly abundant in the study area. Phylogenetic analysis of cbbM sequences suggests the presence of a novel group of chemolithoautotrophs, closely related to the SUP05/ARCTIC96BD-19 clade. Through (RT-qPCR, we studied the cbbM gene abundance and transcript dynamics over an annual cycle, finding a significantly higher number of cbbM copies per unit volume in months of active upwelling and at depths in which oxygen was scarce or absent. The same temporal pattern was observed at the transcriptional level. We also analyzed the relative expression of key genes for carbon, nitrogen and sulfur cycling in six metatranscriptomic datasets, for two characteristic periods within the annual cycle: the anoxic upwelling and the suboxic downwelling. Our results indicate that coastal waters of the subtropical ESP contain transcriptionally active populations of carbon fixing pelagic bacteria, whose dynamics is controlled, in large part, by fluctuations in oxygen levels. They also suggest that chemolithoautotrophic processes coupled to the sulfur and nitrogen cycles become increasingly important for the carbon economy of marine coastal waters as oxygen concentrations decline.

Warm water upwelling in the Cenozoic Era

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Zhang, Y.

2017-12-01

Modern observations show that the occurrence of wind-driven upwelling is often tied to cold sea surface temperatures (SSTs). However, SST reconstructions indicate that globally, the upwelling regions were much warmer in the Miocene and Pliocene. This questions the overall strength of deep-water upwelling in the geological past, with important implications for the associated atmospheric, climatic and biogeochemical processes, and the fate of upwelling regions in a high-CO2 world. We recently showed that the eastern equatorial Pacific (EEP) was characterized by strong air-sea disequilibrium of CO2 during the late Miocene - Pliocene. Combined with export productivity proxies, we interpreted these as signs of vigorous upwelling. The upwelled waters were nutrient- and CO2-rich, but warm. The cause of the "excess" warming in the upwelling regions is linked to the source waters which originated from the higher latitudes. In other words, the reduced east (upwelling) to west (non-upwelling) temperature gradients along the equator in major ocean basins are rooted in the reduced meridional temperature gradients. To further test this hypothesis, we examine the history of the EEP and temperature gradients during the even-warmer Eocene - middle Miocene.

Variabilidad mensual de la velocidad de surgencia y clorofila a en la región del Panama Bight (Monthly rate variation upwelling and chlorophyll a in the region of Panama Bight

Directory of Open Access Journals (Sweden)

Nancy Villegas

2016-09-01

�� N, the third between 82-83° W and 2° 30’-3° 30’ N. Upwelling coastal zone was located on 6° 30’ and 2° N. This work showed that while the ITCZ is far from the CPO, the upwelling is favored. It was determined that, when the ITCZ is on the region, the upwelling is attenuated due to weak winds. It was corroborated that chlorophyll a concentration is high in every month throughout coastal upwelling and around three upwelling focuses.

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

KAUST Repository

Howard, Meredith D. A.; Sutula, Martha; Caron, David A.; Chao, Yi; Farrara, John D.; Frenzel, Hartmut; Jones, Burton; Robertson, George; McLaughlin, Karen; Sengupta, Ashmita

2014-01-01

Anthropogenic nutrients have been shown to provide significant sources of nitrogen (N) that have been linked to increased primary production and harmful algal blooms worldwide. There is a general perception that in upwelling regions, the flux of anthropogenic nutrient inputs is small relative to upwelling flux, and therefore anthropogenic inputs have relatively little effect on the productivity of coastal waters. To test the hypothesis that natural sources (e.g., upwelling) greatly exceed anthropogenic nutrient sources to the Southern California Bight (SCB), this study compared the source contributions of N from four major nutrient sources: (1) upwelling, (2) treated wastewater effluent discharged to ocean outfalls, (3) riverine runoff, and (4) atmospheric deposition. This comparison was made using large regional data sets combined with modeling on both regional and local scales. At the regional bight-wide spatial scale, upwelling was the largest source of N by an order of magnitude to effluent and two orders of magnitude to riverine runoff. However, at smaller spatial scales, more relevant to algal bloom development, natural and anthropogenic contributions were equivalent. In particular, wastewater effluent and upwelling contributed the same quantity of N in several subregions of the SCB. These findings contradict the currently held perception that in upwelling-dominated regions anthropogenic nutrient inputs are negligible, and suggest that anthropogenic nutrients, mainly wastewater effluent, can provide a significant source of nitrogen for nearshore productivity in Southern California coastal waters.

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

KAUST Repository

Howard, Meredith D. A.

2014-01-26

Anthropogenic nutrients have been shown to provide significant sources of nitrogen (N) that have been linked to increased primary production and harmful algal blooms worldwide. There is a general perception that in upwelling regions, the flux of anthropogenic nutrient inputs is small relative to upwelling flux, and therefore anthropogenic inputs have relatively little effect on the productivity of coastal waters. To test the hypothesis that natural sources (e.g., upwelling) greatly exceed anthropogenic nutrient sources to the Southern California Bight (SCB), this study compared the source contributions of N from four major nutrient sources: (1) upwelling, (2) treated wastewater effluent discharged to ocean outfalls, (3) riverine runoff, and (4) atmospheric deposition. This comparison was made using large regional data sets combined with modeling on both regional and local scales. At the regional bight-wide spatial scale, upwelling was the largest source of N by an order of magnitude to effluent and two orders of magnitude to riverine runoff. However, at smaller spatial scales, more relevant to algal bloom development, natural and anthropogenic contributions were equivalent. In particular, wastewater effluent and upwelling contributed the same quantity of N in several subregions of the SCB. These findings contradict the currently held perception that in upwelling-dominated regions anthropogenic nutrient inputs are negligible, and suggest that anthropogenic nutrients, mainly wastewater effluent, can provide a significant source of nitrogen for nearshore productivity in Southern California coastal waters.

On an upwelling front, propagation of upwelling and vertical velocity in the eastern Arabian sea during monsoon, 1987

Digital Repository Service at National Institute of Oceanography (India)

Antony, M.K.; Unnikrishnan, A.S.

A coastal upwelling front parallel to the coast and identifiable upto a depth of 75 m was observed between 12.5 and 16 degrees N along the eastern Arabian Sea in September, 1987 from closely spaced digital BT data. With a north-south slope...

Ocean Drilling Program Leg 112, Peru continental margin: Part 2, Sedimentary history and diagenesis in a coastal upwelling environment

Science.gov (United States)

Suess, E.; von Huene, R.

1988-10-01

On the shelf and upper slope off Peru the signal of coastal upwelling productivity and bottom-water oxygen is well preserved in alternately laminated and bioturbated diatomaceous Quaternary sediments. Global sea-level fluctuations are the ultimate cause for these cyclic facies changes. During late Miocene time, coastal upwelling was about 100 km west of the present centers, along the edge of an emergent structure that subsequently subsided to form the modern slope. The sediments are rich in organic carbon, and intense microbially mediated decomposition of organic matter is evident in sulfate reduction and methanogenesis. These processes are accompanied by the formation of diagenetic carbonates, mostly Ca-rich dolomites and Mg-calcites. The downhole isotopic signatures of these carbonate cements display distinct successions that reflect the vertical evolution of the pore fluid environment. From the association of methane gas hydrates, burial depth, and low-chloride interstitial fluids, we suggest an additional process that could contribute to the characteristic chloride depletion in pore fluids of active margins: release of interlayer water from clays without a mineral phase change. The shelf sediments also contain a subsurface brine that stretches for more than 500 km from north to south over the area drilled. The source of the brine remains uncertain, although the composition of the oxygen isotopes suggests dissolution of evaporites by seawater.

Coastal upwelling by wind-driven forcing in Jervis Bay, New South Wales: A numerical study for 2011

Science.gov (United States)

Sun, Youn-Jong; Jalón-Rojas, Isabel; Wang, Xiao Hua; Jiang, Donghui

2018-06-01

The Princeton Ocean Model (POM) was used to investigate an upwelling event in Jervis Bay, New South Wales (SE Australia), with varying wind directions and strengths. The POM was adopted with a downscaling approach for the regional ocean model one-way nested to a global ocean model. The upwelling event was detected from the observed wind data and satellite sea surface temperature images. The validated model reproduced the upwelling event showing the input of bottom cold water driven by wind to the bay, its subsequent deflection to the south, and its outcropping to the surface along the west and south coasts. Nevertheless, the behavior of the bottom water that intruded into the bay varied with different wind directions and strengths. Upwelling-favorable wind directions for flushing efficiency within the bay were ranked in the following order: N (0°; northerly) > NNE (30°; northeasterly) > NW (315°; northwesterly) > NE (45°; northeasterly) > ENE (60°; northeasterly). Increasing wind strengths also enhance cold water penetration and water exchange. It was determined that wind-driven downwelling within the bay, which occurred with NNE, NE and ENE winds, played a key role in blocking the intrusion of the cold water upwelled through the bay entrance. A northerly wind stress higher than 0.3 N m-2 was required for the cold water to reach the northern innermost bay.

A statistical approach to coastal upwelling in the Baltic Sea based on the analysis of satellite data for 1990-2009

Directory of Open Access Journals (Sweden)

Andreas Lehmann

2012-06-01

Full Text Available A statistical analysis of Baltic Sea upwelling has been carried out to cover, for the first time, the entire sea area for the period 1990-2009. Weekly composite SST maps based on NOAA/AVHRR satellite data were used to evaluate the location and frequency of upwelling. The results obtained were analysed and compared with earlier studies with excellent agreement. Our study enables the most intense upwelling areas in the entire Baltic Sea to be evaluated. According to the analysis of 443 SST maps, the most common upwelling regions are found off the Swedish south and east coasts (frequency 10-25%, the Swedish coast of the Bothnian Bay (16%, the southern tip of Gotland (up to 15%, and the Finnish coast of the Gulf of Finland (up to 15%. Pronounced upwelling also occurs off the Estonian coast and the Baltic east coast (up to 15%, the Polish coast and the west coast of Rügen (10-15%; otherwise the upwelling frequency was between 5 and 10%. Additionally, simulated SST distributions derived from a Baltic Sea numerical model were analysed for the same period. Furthermore, at specific positions close to the coastline, surface winds based on the SMHI meteorological data base were analysed for the same 20-year period. Wind components parallel to the coast were discriminated into favourable and unfavourable winds forcing upwelling. The obtained frequencies of upwelling-favourable winds fit very well the observed upwelling frequencies derived from satellite SST maps. A positive trend of upwelling frequencies along the Swedish east coast and the Finnish coast of the Gulf of Finland was calculated for the period 1990-2009.

Phytoplankton biomass and microbial abundances during the spring upwelling season in the coastal area off Concepción, central-southern Chile: Variability around a time series station

Science.gov (United States)

Morales, Carmen E.; Anabalón, Valeria

2012-01-01

In the coastal system off Concepción, time series observations at a fixed station (St. 18) have shown strong seasonal changes in the oceanographic environment of the upper layer (blooms, dominated by microplanktonic diatoms, have usually overshadowed the relevance of the smaller microbial components during upwelling. This study focuses on the variability of oceanographic conditions and their association with the structure of the planktonic community (size fractionated chlorophyll-a and microbial abundances) in the upper layer during the upwelling season, examining the extent to which St. 18 is representative of the coastal system off Concepción during springtime. For this purpose, data from three consecutive springs (2004, 2005, 2006) were compared, which included cruises for all years (8 stations around St. 18) as well as monthly sampling at St. 18. Most of the spatial (submesoscale) variability in chlorophyll-a and the microbial components was not significant, but data dispersion around mean values was high. Water column structure (temperature and salinity) in the upper layer explained a significant fraction (25-65%) of the spatial variability in most of the planktonic components; their responses to oceanographic variability were linear in some cases and non-linear in others. For the most part, St. 18 appears to adequately represent mean oceanographic conditions and the structure of planktonic communities in the coastal waters off Concepción during springtime, however spatial variability needs to be taken into account in the interpretations of temporal changes at this fixed station as well as in assessments of carbon flow within, and exportation processes from, this upwelling system.

Joint effect of freshwater plume and coastal upwelling on phytoplankton growth off the Changjiang River

Science.gov (United States)

Tseng, Y.-F.; Lin, J.; Dai, M.; Kao, S.-J.

2014-01-01

The Changjiang (Yangtze) River discharges vast amount of unbalanced nutrients (dissolved inorganic nitrogen and phosphorus with N / P ratio > 80 in general) into the East China Sea in summer. To study nutrient dynamics and P-stress potential for phytoplankton, a cruise was conducted in the Changjiang plume during summer 2011. With 3-D observations of nutrients, chlorophyll a (Chl a), and bulk alkaline phosphatase activity (APA), we concluded that the Changjiang Diluted Water and coastal upwelling significantly influenced the horizontal and vertical heterogeneities of phytoplankton P deficiency in the Changjiang plume. Allochthonous APA was detected at nutrient-enriched freshwater end. Excessive N (~ 10 to 112 μM) was observed throughout the entire plume surface. In the plume fringe featuring stratification and excess N, diapycnal phosphate supply was blocked and phytoplankton APA was stimulated for growth. We observed an upwelling just attaching to the turbidity front at seaward side where Chl a peaked yet much less APA was detected. An external phosphate supply from subsurface, which promoted phytoplankton growth but inhibited APA, was suggested to be sourced from the Nearshore Kuroshio Branch Current. In the so hydrographically complicated Changjiang plume, phosphate supply instead of its concentration may be more important in determining the expression of APA. Meanwhile, allochthonous APA may also alter the usefulness of APA as a P-stress indicator.

Upwelling filaments are cold, typically narrow features in surface ...

African Journals Online (AJOL)

spamer

They are defined by strong ... transporting coastally upwelled water to the deep ... surface temperature anomaly up to 2°C. The cool temperature signal was restricted to a shallow surface ... towards the important process of exchanges between.

Hydrodynamic control of microphytoplankton bloom in a coastal sea

Indian Academy of Sciences (India)

K Narasimha Murty

2017-08-31

Aug 31, 2017 ... surface water to depths in regions where there is no barrier layer at the ... ent availability (and light) alone does not give place to blooms in the ...... ics in a coastal upwelling system off southwestern Africa;. Deep Sea Res.

Upwelling and Other Environmental Influences on Growth of a Nearshore Benthic Fish

Science.gov (United States)

von Biela, V. R.; Zimmerman, C. E.; Kruse, G. H.; Mueter, F. J.; Black, B.; Douglas, D. C.; Bodkin, J. L.

2016-02-01

The role of upwelling in nearshore benthic systems is more uncertain compared to the relatively strong positive associations with pelagic production. To understand how upwelling and other environmental conditions influence nearshore benthic production, we developed an annual index of production from growth increments recorded in otoliths of kelp greenling (Hexagrammos decagrammus) at nine sites in the seasonally-upwelling California Current and downwelling Alaska Coastal currents. Kelp greenling are a benthic-feeding fish common in kelp forests with food webs sustained by both kelp and phytoplankton primary production. We explored the influence of basin- and local-scale conditions, including upwelling, across all seasons at lags up to two years taken to represent changes in the quantity and quality of prey. Upwelling strength was positively related to fish growth in both current systems, although relationships in the Alaska Coastal Current were indicative of faster growth with relaxed downwelling, rather than upwelling. Looking across a suite of basin- and local-scale environmental indicators, complex relationships emerged in the California Current, with faster growth related to within-year warm conditions and lagged-year cool conditions. In contrast, fish in the downwelling system grew faster both during and subsequent to warm conditions. The complex lag-dependent dynamics in the upwelling system may reflect differences in conditions that promote quantity versus quality of benthic invertebrate prey. Thus, we hypothesize that benthic production is maximized when cool and warm years alternate during periods of high frequency climate variability in the California Current. Such a pattern is consistent with previous findings suggesting that benthic invertebrate abundance (e.g., recruitment) is food-limited during warm years with reduced upwelling, while quality (e.g., energy content) is temperature-limited during cool years.

The development and decline of phytoplankton blooms in the southern Benguela upwelling region

International Nuclear Information System (INIS)

Brown, P.C.

1986-10-01

Productivity/chlorophyll a relationship are investigated with a view to estimating phytoplankton productivity from extensive chlorophyll a measurements in the southern Benguela region. Phytoplankton bloom dynamics in newly upwelled water off the Cape Peninsula are investigated on five different occasions during the upwelling season. A drogue was used to tag a 'parcel' of upwelled water which was monitored for between 4 and 8 days. In upwelling source water, mean chlorophyll a concentrations were typically low (0.7 mg.m -3 ) and nutrient concentrations were high (nitrates, silicates and phosphates were 20.8, 16.6 and 1.88 mmol.m -3 respectively). Along the drogue tracks nutrients decreased rapidly in the euphotic zone as chlorophyll increased to peak at concentrations of up to 26 mg.m -3 . Elemental changes in nitrates, silicates, phosphates and oxygen were used to estimate primary productivity. These 'Redfield productivity estimates' were similar to 14 C-uptake productivity but lower than estimates obtained from changes in particle volume. Daily rates of 14 C-uptake water column productivity ranged between 0.94 and 14.01 g C.m -2 .d -1 (mean 3.80 g C.m -2 .d -1 ) and were similar to or higher than productivity estimates reported for other upwelling areas. Phytoplankton biomass in the upper 50 metres ranged between 8 and 506 mg chll a. m -2 (mean 208 mg chll a.m -2 ). The temporal scale of phytoplankton bloom development was investigated in terms of changes in chlorophyll a concentrations in the euphotic zone. The build up and decline of the primary phytoplankton (diatom) bloom in newly upwelled water occurred within 6-8 days. The initiation of blooming was controlled by the stability of the water body. The decline of the bloom was associated with reduced nutrient levels and is considered to result mainly from phytoplankton cells sinking out of the surface layers

Response of the Benguela upwelling systems to spatial variations in the wind stress

Science.gov (United States)

Fennel, Wolfgang; Junker, Tim; Schmidt, Martin; Mohrholz, Volker

2012-08-01

In this paper we combine field observations, numerical modeling and an idealized analytical theory to study some features of the Benguela upwelling system. The current system can be established through a combination of observations and realistic simulations with an advanced numerical model. The poleward undercurrent below the equator-ward coastal jet is often found as a countercurrent that reaches the sea surface seaward of the coastal jet. The coastal band of cold upwelled water appears to broaden from south to north and at the northern edge of the wind band an offshore flow is often detected, which deflects the coastal Angola current to the west. These features can be explained and understood with an idealized analytical model forced by a spatially variable wind. A crucial role is played by the wind stress curl, which shapes the oceanic response through Ekman-pumping. The interplay of the curl driven effects and the coastal Ekman upwelling together with the coastal jet, Kelvin waves, and the undercurrent is the key to understand the formation of the three-dimensional circulation patterns in the Benguela system. While the numerical model is based on the full set of primitive equations, realistic topography and forcing, the analytic model uses a linear, flat-bottomed f-plane ocean, where the coast is a straight wall and the forcing is represented by an alongshore band of dome-shaped wind stress. Although the analytical model is highly idealized it is very useful to grasp the basic mechanisms leading to the response patterns.

Seasonal and inter-annual variation of mesozooplankton in the coastal upwelling zone off central-southern Chile

Science.gov (United States)

Escribano, Ruben; Hidalgo, Pamela; González, Humberto; Giesecke, Ricardo; Riquelme-Bugueño, Ramiro; Manríquez, Karen

2007-11-01

Zooplankton sampling at Station 18 off Concepción (36°30‧S and 73°07‧W), on an average frequency of 30 days (August 2002 to December 2005), allowed the assessment of seasonal and inter-annual variation in zooplankton biomass, its C and N content, and the community structure in relation to upwelling variability. Copepods contributed 79% of the total zooplankton community and were mostly represented by Paracalanus parvus, Oithona similis, Oithona nana, Calanus chilensis, and Rhincalanus nasutus. Other copepod species, euphausiids (mainly Euphausia mucronata), gelatinous zooplankton, and crustacean larvae comprised the rest of the community. Changes in the depth of the upper boundary of the oxygen minimum zone indicated the strongly seasonal upwelling pattern. The bulk of zooplankton biomass and total copepod abundance were both strongly and positively associated with a shallow (oxygen minimum zone; these values increased in spring/summer, when upwelling prevailed. Gelatinous zooplankton showed positive abundance anomalies in the spring and winter, whereas euphausiids had no seasonal pattern and a positive anomaly in the fall. The C content and the C/N ratio of zooplankton biomass significantly increased during the spring when chlorophyll- a was high (>5 mg m -3). No major changes in zooplankton biomass and species were found from one year to the next. We concluded that upwelling is the key process modulating variability in zooplankton biomass and its community structure in this zone. The spring/summer increase in zooplankton may be largely the result of the aggregation of dominant copepods within the upwelling region; these may reproduce throughout the year, increasing their C content and C/N ratios given high diatom concentrations.

Lipid biomarker patterns of phosphogenic sediments from upwelling regions

DEFF Research Database (Denmark)

Arning, Esther T.; Birgel, Daniel; Schultz-Vogt, Heide N.

2008-01-01

Sediments of upwelling regions off Namibia, Peru, and Chile contain dense populations of large nitrate-storing sulfide-oxidizing bacteria, Thiomargarita, Beggiatoa, and Thioploca. Increased contents of monounsaturated C16 and C18 fatty acids have been found at all stations studied, especially when...... these bacteria. As a consequence, the distributions of sulfate reducers in sediments of Namibia, Peru, and Chile are closely related to differences in the motility of the various sulfide oxidizers at the three study sites. Depth profiles of mono-O-alkyl glycerol ethers have been found to correlate best...

The ichthyoplankton assemblage of the Canaries-African Coastal Transition Zone: A review

Science.gov (United States)

Rodriguez, J. M.; Moyano, M.; Hernandez-Leon, S.

2009-12-01

In this paper we review information on the ichthyoplankton assemblage of the Canaries-African Coastal Transition Zone (C-ACTZ). This CTZ shows the singularity that the Canary Archipelago interrupts the main flow of the Canary Current and Trade Winds, introducing large mesoscale variability, in the form of island warm wakes and cyclonic and anticyclonic eddies downstream of the islands. Besides, upwelling filaments stretch towards the archipelago from the African coastal upwelling, transporting phytoplankton, zooplankton and fish larvae. They also interact with eddies shed from the islands to exchange water properties and biogenic material. All these mesoscale features influence the composition, structure, abundance and distribution of the larval fish community (LFC) of the region. The Canary Current (CC) and eddies shed from the islands drag larvae of island neritic fish species into the oceanic region and contribute, along warm wakes, to the horizontal distribution of fish larvae. Upwelling and upwelling filaments transport larvae of African neritic species into the oceanic region. These larvae dominate the LFC and account for the relatively high average larval fish abundance found in the C-ACTZ during the summer upwelling season. Filaments originated in the region of Cape Juby-Cape Bojador are entrained around a quasi-permanent cyclonic eddy, trapped between Gran Canaria Island and the African coast, forming a system through which most of the African neritic larvae may return to the African shelf. However, some larvae reach the eastern islands of the Canary archipelago and they may be spread all over the neritic region of the archipelago by eddies shed from the islands. Also in summer, the distribution of the LFC of the C-ACTZ is vertically stratified and fish larvae seem to carry out little or not diel vertical migration. Overall, this study highlights the strong relationship between mesoscale oceanographic processes and the LFC in the C-ACTZ.

Differences in coastal and oceanic SST trends north of Yucatan Peninsula

Science.gov (United States)

Varela, R.; Costoya, X.; Enriquez, C.; Santos, F.; Gómez-Gesteira, M.

2018-06-01

The coastal area north of Yucatan has experienced a cooling SST trend from 1982 to 2015 during the upwelling season (May-September) that contrasts with the warming observed at the adjacent ocean area. Different drivers were analyzed to identify the possible causes of that unusual coastal cooling. Changes in coastal upwelling and in sea-atmosphere heat fluxes are not consistent with the observed coastal cooling. The eastward shift of the Yucatan Current observed over the last decades is hypothesized as the most probable cause of coastal cooling. This shift enhances the vertical transport of cold deeper water to the continental shelf from where it is pumped to the surface by upwelling favorable westerly winds.

Zooplankton associated with the oxygen minimum zone system in the northern upwelling region of Chile during March 2000

Science.gov (United States)

Escribano, Ruben; Hidalgo, Pamela; Krautz, Cristina

2009-07-01

Zooplankton in the coastal upwelling region off northern Chile may play a significant biogeochemical role by promoting carbon flux into the subsurface OMZ (oxygen minimum zone). This work identifies the dominant zooplankton species inhabiting the area influenced by the OMZ in March 2000 off Iquique (20°S, northern Chile). Abundance and vertical distribution studies revealed 17 copepod and 9 euphausiid species distributed between the surface and 600 m at four stations sampled both by day and by night. Some abundant species remained in the well-oxygenated upper layer (30 m), with no evidence of diel vertical migration, apparently restricted by a shallow (40-60 m) oxycline. Other species, however, were found closely associated with the OMZ. The large-sized copepod Eucalanus inermis was found below the oxycline and performed diel vertical migrations into the OMZ, whereas the very abundant Euphausia mucronata performed extensive diel vertical migrations between the surface waters and the core of the OMZ (200 m), even crossing it. A complete assessment of copepods and euphausiids revealed that the whole sampled water column (0-600 m) is occupied by distinct species having well-defined habitats, some of them within the OMZ. Ontogenetic migrations were evident in Eucalanidae and E. mucronata. Estimates of species biomass showed a substantial (>75% of total zooplankton biomass) daily exchange of C between the photic layer and the OMZ. Both E. inermis and E. mucronata can actively exchange about 37.8 g C m -2 d -1 between the upper well-oxygenated (0-60 m) layer and the deeper (60-600 m) OMZ layer. This migrant biomass may contribute about 7.2 g C m -2 d -1 to the OMZ system through respiration, mortality, and production of fecal pellets within the OMZ. This movement of zooplankton in and out of the OMZ, mainly as a result of the migratory behavior of E. mucronata, suggests a very efficient mechanism for introducing large amounts of freshly produced carbon into the OMZ

Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

Energy Technology Data Exchange (ETDEWEB)

Auger, P.A., E-mail: pierreamael.auger@gmail.com [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Machu, E.; Gorgues, T.; Grima, N. [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Waeles, M. [Université de Bretagne Occidentale (UBO), Laboratoire de l' Environnement Marin (LEMAR), UMR-CNRS 6539/IRD/UBO, place N. Copernic, 29280 Plouzané (France)

2015-02-01

A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes.

Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

International Nuclear Information System (INIS)

Auger, P.A.; Machu, E.; Gorgues, T.; Grima, N.; Waeles, M.

2015-01-01

A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes

Quantifying the impact of an upwelling filament on the physical-chemical-biological interactions off SW Iberia

Science.gov (United States)

Cravo, A.; Sanchez, R.; Monteiro, C.; Cardeira, S.; Madureira, M.; Rita, F.; Relvas, P.

2017-12-01

Upwelling filaments are mesoscale structures of cold water that stretch seaward in a tongue-like shape with origin in the coastal upwelling zone. Filaments off the Iberian Peninsula are recurrent, showing similarities with those in the Californian coast. The Cape São Vicente, the SW tip of the Iberian Peninsula, is the root of recurrent filaments observed in the satellite imagery during the upwelling season. However, the understanding of its physical and chemical impact on the biological productivity is rather limited. There, a relatively small filament ( 80 km long) was investigated through remote sensing and in situ multidisciplinary observations during an upwelling favourable wind relaxation event, but just after an intense upwelling period. A total of 42 CTD+Rosette casts up to 400 m depth were distributed on an almost regular grid of 15 km mean spacing guided by guided by satellite SST imagery transmitted to the ship in near-real time. The parameters sampled during the sea campaign included: velocity field sampled along the ship track through a hull-mounted 38 kHz RDI ADCP, meteorological variables, temperature, salinity, chlorophyll a, dissolved oxygen, nitrate, phosphate, silicate, cadmium, lead and zinc. The extent of the impact of the filament was evaluated by quantifying the cross-shelf transports of several properties. The amounts conveyed by the filament were much stronger than those expected by the wind-driven Ekman mechanism, showing that it represents an efficient feature for the exchange of water, dissolved and particulate matter from the productive shelf towards the oligotrophic offshore region. Considering the periods of strong upwelling events and the extent of their duration along the year, the amounts of exported matter will certainly enhance the biological productivity of these waters, including its fisheries. These filament data contribute to better understand the physical-chemical-biological interactions of this regional ecosystem.

A Holocene record of ocean productivity and upwelling from the northern California continental slope

Science.gov (United States)

Addison, Jason A.; Barron, John A.; Finney, Bruce P.; Kusler, Jennifer E.; Bukry, David; Heusser, Linda E.; Alexander, Clark R.

2018-01-01

The Holocene upwelling history of the northern California continental slope is examined using the high-resolution record of TN062-O550 (40.9°N, 124.6°W, 550 m water depth). This 7-m-long marine sediment core spans the last ∼7500 years, and we use it to test the hypothesis that marine productivity in the California Current System (CCS) driven by coastal upwelling has co-varied with Holocene millennial-scale warm intervals. A combination of biogenic sediment concentrations (opal, total organic C, and total N), stable isotopes (organic matter δ13C and bulk sedimentary δ15N), and key microfossil indicators of upwelling were used to test this hypothesis. The record of biogenic accumulation in TN062-O550 shows considerable Holocene variability despite being located within 50 km of the mouth of the Eel River, which is one of the largest sources of terrigenous sediment to the Northeast Pacific Ocean margin. A key time interval beginning at ∼2900 calibrated years before present (cal yr BP) indicates the onset of modern upwelling in the CCS, and this period also corresponds to the most intense period of upwelling in the last 7500 years. When these results are placed into a regional CCS context during the Holocene, it was found that the timing of upwelling intensification at TN062-O550 corresponds closely to that seen at nearby ODP Site 1019, as well as in the Santa Barbara Basin of southern California. Other CCS records with less refined age control show similar results, which suggest late Holocene upwelling intensification may be synchronous throughout the CCS. Based on the strong correspondence between the alkenone sea surface temperature record at ODP Site 1019 and the onset of late Holocene upwelling in northern California, we suggest that CCS warming may be conducive to upwelling intensification, though future changes are unclear as the mechanisms forcing SST variability may differ.

Hot-spots of primary productivity: An Alternative interpretation to Conventional upwelling models

Science.gov (United States)

van Ruth, Paul D.; Ganf, George G.; Ward, Tim M.

2010-12-01

The eastern Great Australian Bight (EGAB) forms part of the Southern and Indian Oceans and is an area of high ecological and economic importance. Although it supports a commercial fishery, quantitative estimates of the primary productivity underlying this industry are open to debate. Estimates range from 500 mg C m -2 day -1. Part of this variation may be due to the unique upwelling circulation of shelf waters in summer/autumn (November-April), which shares some similarities with highly productive eastern boundary current upwelling systems, but differs due to the influence of a northern boundary current, the Flinders current, and a wide continental shelf. This study examines spatial variations in primary productivity in the EGAB during the upwelling seasons of 2005 and 2006. Daily integral productivity calculated using the vertically generalised production model (VGPM) showed a high degree of spatial variation. Productivity was low (modelled with the VGPM, which uses surface measures of phytoplankton biomass to calculate productivity. Macro-nutrient concentrations could not be used to explain the difference in the low and high productivities (silica > 1 μmol L -1, nitrate/nitrite > 0.4 μmol L -1, phosphate > 0.1 μmol L -1). Mixing patterns or micro-nutrient concentrations are possible explanations for spatial variations in primary productivity in the EGAB. On a global scale, daily rates of primary productivity of the EGAB lie between the highly productive eastern boundary current upwelling systems, and less productive coastal regions of western and south eastern Australia, and the oligotrophic ocean. However, daily productivity rates in the upwelling hotspots of the EGAB rival productivities in Benguela and Humboldt currents.

Coastal upwelling ecosystems are often identified as regions ...

African Journals Online (AJOL)

spamer

... are often identified as regions susceptible to seasonal blooms of harmful ... that the bay acts as a net importer of bottom water and net exporter of surface waters over a synoptic cycle. This ... waves or wind stress on the surface friction layer.

Spatial distribution of upwelling off the central east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Rao, T.V.N.

of the data collected along the five sections. At all the sections, a decrease in water temperature and an increase in salinity from the offshore stations to the stations closest to the shore indicated coastal upwelling. The Rossby radii of deformation...

Egyptian coastal regions development through economic diversity for its coastal cities

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Tarek AbdeL-Latif

2012-12-01

This study examines the structure of the coastal cities industry, the main types, the impacts (economic, environmental, and social of coastal cities, and the local trends in development in the Egyptian coastal cities and its regions. It will also analyze coastal and marine tourism in several key regions identified because of the diversity of life they support, and the potential destruction they could face. This paper confirms that economic diversification in coastal cities is more effective than developments in only one economic sector, even if this sector is prominent and important.

Riverine influence on nitrogen fixation in the upwelling region off Vietnam, South China Sea

DEFF Research Database (Denmark)

Voss, Maren; Bombar, Deniz; Loick, Natalie

2006-01-01

with the intermonsoon season and find that nitrogen fixation rates are app. 10 times higher during the monsoon season. However, this was not the case in the actual upwelling region - a 40-50 km wide strip along the coast - but further offshore, where the Mekong plume was noticeable. Therefore, we hypothesize...

Climate change and ocean deoxygenation within intensified surface-driven upwelling circulations.

Science.gov (United States)

Bakun, Andrew

2017-09-13

Ocean deoxygenation often takes place in proximity to zones of intense upwelling. Associated concerns about amplified ocean deoxygenation arise from an arguable likelihood that coastal upwelling systems in the world's oceans may further intensify as anthropogenic climate change proceeds. Comparative examples discussed include the uniquely intense seasonal Somali Current upwelling, the massive upwelling that occurs quasi-continuously off Namibia and the recently appearing and now annually recurring 'dead zone' off the US State of Oregon. The evident 'transience' in causal dynamics off Oregon is somewhat mirrored in an interannual-scale intermittence in eruptions of anaerobically formed noxious gases off Namibia. A mechanistic scheme draws the three examples towards a common context in which, in addition to the obvious but politically problematic remedy of actually reducing 'greenhouse' gas emissions, the potentially manageable abundance of strongly swimming, finely gill raker-meshed small pelagic fish emerges as a plausible regulating factor.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

Environmental changes associated with monsoon induced upwelling, off central west coast of India

Digital Repository Service at National Institute of Oceanography (India)

DeSousa, S.N.; Sawkar, K.; Rao, P.V.S.S.D.P.

in response to prevailing equatorward winds. High salinity ocean waters of rich nutrient contents were observed at the coast in some locations. However, the effect of upwelling on the surface distribution of properties was reduced to some extent due to coastal...

Regeneration of nitrogen by zooplankton and fish in the Northwest Africa and Peru upwelling ecosystems

Energy Technology Data Exchange (ETDEWEB)

Whitledge, T E

1976-01-01

The availability of nutrients and light are the dominant controlling factors of the levels of primary production in the ocean. In the lower latitudes where most coastal upwelling areas are located, the amount of light is seldom below the critical level to inhibit productivity so nutrients are often the limiting factor in phytoplankton growth. Nutrients utilized in primary productivity are derived from two sources in upwelling areas. Nutrients are introduced to the euphotic zone from depth by the physical processes that create upwelling and nutrients are recycled by biological organisms that inhabit the area. Nitrate introduced into the euphotic zone by upwelling supports new productivity while ammonium and other excretory products regenerated by zooplankton and nekton supports regenerated productivity. Results are reported from studies off the coast of Northwest Africa and Peru using /sup 15/N as a tracer that showed that recycled ammonium may fulfill nearly half of the daily nitrogen requirement of phytoplankton and upwelled nitrate may provide the other half.

Zooplankton Responses to Low-Oxygen Condition upon a Shallow Oxygen Minimum Zone in the Upwelling Region off Chile

Science.gov (United States)

Hidalgo, P.; Escribano, R.

2015-12-01

A shallow oxygen minimum zone (OMZ) is a critical component in the coastal upwelling ecosystem off Chile. This OMZ causes oxygen-deficient water entering the photic layer and affecting plankton communities having low tolerance to hypoxia. Variable, and usually species-dependent, responses of zooplankton to hypoxia condition can be found. Most dominant species avoid hypoxia by restricting their vertical distribution, while others can temporarily enter and even spent part of their life cycle within the OMZ. Whatever the case, low-oxygen conditions appear to affect virtually all vital rates of zooplankton, such as mortality, fecundity, development and growth and metabolism, and early developmental stages seem more sensitive, with significant consequences for population and community dynamics. For most study cases, these effects are negative at individual and population levels. Observations and predictions upon increasing upwelling intensity over the last 20-30 years indicate a gradual shoaling of the OMZ, and so that an expected enhancement of these negative effects of hypoxia on the zooplankton community. Unknown processes of adaptation and community-structure adjustments are expected to take place with uncertain consequences for the food web of this highly productive eastern boundary current ecosystem.

The use of circulation weather types to predict upwelling activity along the Western Iberian Peninsula coast

Science.gov (United States)

Ramos, Alexandre M.; Cordeiro Pires, Ana; Sousa, Pedro M.; Trigo, Ricardo M.

2013-04-01

Coastal upwelling is a phenomenon that occurs in most western oceanic coasts due to the presence of mid-latitude high-pressure systems that generate equatorward winds along the coast and consequent offshore displacement of surface waters that in turn cause deeper, colder, nutrient-rich waters to arise. In western Iberian Peninsula (IP) the high-pressure system associated to northerly winds occurs mainly during spring and summer. Upwelling systems are economically relevant, being the most productive regions of the world ocean and crucial for fisheries. In this work, we evaluate the intra- and inter-annual variability of the Upwelling Index (UI) off the western coast of the IP considering four locations at various latitudes: Rias Baixas, Aveiro, Figueira da Foz and Cabo da Roca. In addition, the relationship between the variability of the occurrence of several circulation weather types (Ramos et al., 2011) and the UI variability along this coast was assessed in detail, allowing to discriminate which types are frequently associated with strong and weak upwelling activity. It is shown that upwelling activity is mostly driven by wind flow from the northern quadrant, for which the obtained correlation coefficients (for the N and NE types) are higher than 0.5 for the four considered test locations. Taking into account these significant relationships, we then developed statistical multi-linear regression models to hindcast upwelling series (April to September) at the four referred locations, using monthly frequencies of circulation weather types as predictors. Modelled monthly series reproduce quite accurately observational data, with correlation coefficients above 0.7 for all locations, and relatively small absolute errors. Ramos AM, Ramos R, Sousa P, Trigo RM, Janeira M, Prior V (2011) Cloud to ground lightning activity over Portugal and its association with Circulation Weather Types. Atmospheric Research 101:84-101. doi: 10.1016/j.atmosres.2011.01

Initial observation of upwelling along east coast of Peninsular Malaysia musica-gratis.softonic.it/ >musica gratis

Science.gov (United States)

Akhir, M.; Tanggang, F.

2013-12-01

There is no published evidence of upwelling in coastal area along the east coast of Peninsular Malaysia. However numbers of recent cruise data collected during the southwest monsoon found features of thermocline lifting and isolated cooler temperature water along the coast, These sign was observed along the 104°E from numbers of parallel transects. To confirm the presence of upwelling, satellite remote sensing data was used, and numerical model experiments were conducted. Cooler sea-surface temperature along the coast was observed from both in-situ and satellite data, while upward movement in the vertical profiles agreed with the location of upwelling from both in-situ and satellite data. Moreover, these data also show that the upwelled water band along the 104°E longitude stretch approximately 650 km long. Initially, southwesterly wind during this season is believed to be the important mechanism that contributed to this wind-induced Ekman upwelling. musica-gratis.softonic.it/ >musica gratis

Nutrient fluxes and net metabolism in a coastal lagoon SW peninsula of Baja California, Mexico

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Cervantes Duarte, R.

2016-09-01

Full Text Available Fluxes of nutrients and net metabolism were estimated in coastal lagoon Magdalena Bay using LOICZ biogeochemical model. In situ data were obtained from 14 sites in the lagoon and also from a fixed site in the adjacent ocean area. Intense upwelling (February to July and faint upwelling (August to January were analyzed from monthly time series. The Temperature, nitrite + nitrate, ammonium and phosphate within the lagoon showed significant differences (p<0.05 between the two periods. Salinity (p=0.408 was more homogeneous (no significantly different due to mixing processes. During the intense upwelling period, nutrients increased in and out of the lagoon due to the influence of Transitional Water and Subartic Water transported by the California Current. However, during the faint upwelling, from August to January, the Transition Water and Subtropical Surface Water were predominant. Magdalena Bay showed denitrification processes of throughout the year as it occurred in other semi-arid coastal lagoons. It also showed a net autotrophic metabolism during intense upwelling and heterotrophic metabolism during faint upwelling. Understanding nutrient flows and net metabolism through simple biogeochemical models can provide tools for better management of the coastal zone.

Bloom dynamics and life cycle strategies of two toxic dinoflagellates in a coastal upwelling system (NW Iberian Peninsula)

Science.gov (United States)

Bravo, Isabel; Fraga, Santiago; Isabel Figueroa, Rosa; Pazos, Yolanda; Massanet, Ana; Ramilo, Isabel

2010-02-01

A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conducted from 2005 to 2007 in order to increase knowledge of the mechanisms governing recurrent blooms of these species. Considerable differences in their bloom dynamics were observed. G. catenatum blooms occurred in autumn and winter, following the pattern previously reported in the literature: they began off-shore and were advected to the Galician rias when a relaxation of the coastal upwelling occurred. On the other hand, A. minutum blooms developed inside embayments in spring and summer during the upwelling season and were associated with water stability and stratification. Both the vegetative population and the cyst distribution of A. minutum were related to less saline water from freshwater river outputs, which support a saline-gradient relationship postulated herein for this species. Dinoflagellates may produce both long-term double-walled cysts (resting) and short-term pellicle cysts. Resting cyst deposition and distribution in sediments showed that seeding occurred during the blooms of both species. However, the relationship between the cyst distribution in the sediments in Baiona Bay and the intensity and occurrence of G. catenatum blooms, suggests that the latter are not directly related to resting cyst germination. Moreover, the results presented in the present study point to other difference between the two species, such as the detection of pellicle cysts only for A. minutum. Finally, we discuss how the life cycle strategies of these two species may help to explain the different mechanisms of bloom formation reported herein.

How marine upwelling influences the distribution of Artemesia longinaris (Decapoda: Penaeoidea?

Directory of Open Access Journals (Sweden)

Gustavo S Sancinetti

2014-05-01

Full Text Available Upwelling events can occur in most of the oceans altering the water physical, chemical and sediment conditions and consequently the species communities dwelling the areas. For better understanding the behavior of populations inhabiting upwelling regions, the spatial and temporal distribution of a Penaeoidea shrimp was studied correlating it with the abiotic factors that vary during upwelling and non-upwelling periods in an area under influence of Cabo Frio upwelling. Bottom salinity and temperature, organic matter and sediment type from each station were sampled from March 2008 to February 2010, in six stations located between 5 and 45 m depth. The lowest temperatures were recorded during spring and summer for both years with temperature values lower than 19ºC. A total of 26,466 Artemesia longinaris shrimps were captured mainly in 10-35 m depth. Upwelling periods showed significant differences in abundance in relation to non-upwelling periods. The spatial distribution among stations varied according to the temperature with higher abundance in stations with values between 19 and 21ºC. The highest abundance of A. longinaris was recorded in spring and summer when intrusions of the cold waters of South Atlantic Central Waters (SACW were frequent. Thus, the effect of cold water of SACW boosted by the upwelling was a determinant factor in the spatial and temporal distribution of A. longinaris in the studied region.

Mercury speciation in fish of the Cabo Frio upwelling region, SE-Brazil

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Carlos Alberto da Silva

2011-09-01

Full Text Available Mercury distribution in the oceans is controlled by complex biogeochemical cycles, resulting in retention of trace amounts of this metal in marine biota. The impact of upwelling processes in this metal behavior has been overlooked. Data from literature are insufficient to evaluate the risks associated with the presence of mercury in the fish collected in upwelling areas and its consumers. Therefore, the aim of the present work was to perform a study of mercury speciation in four fish species belonging to different trophic levels from Cabo Frio-Brazil upwelling region. The total mercury content vary of 53 ng g-1 (Sardinella brasiliensis -sardine to 1215 ng g-1 (Cynoscion striatus -striped weakfish and, with exception of the planktivorous fish, methylmercury levels reaches circa 90% of total mercury concentration.A distribuição de Mercúrio nos oceanos é controlada por um complexo ciclo biogeoquímico, resultando na retenção de pequenas quantidades na biota marinha. O impacto dos processos de ressurgência costeira no comportamento desse metal tem sido negligenciado. Dados da literatura são insuficientes para elucidar o risco associado com a presença de mercúrio em peixes capturados em áreas de ressurgência e seus consumidores. Portanto o objetivo do presente trabalho foi realizar um estudo de especiação de mercúrio em quatro espécies de peixes pertencentes a diferentes níveis tróficos da região de ressurgência de Cabo Frio-Brasil. O conteúdo total de mercúrio variou de 53 ng g-1 (Sardinella brasiliensis -sardinha to 1215 ng g-1 (Cynoscion striatus -pescada e, com exceção da espécie planctivora, os níveis de metilmercúrio atingem cerca de 90% da concentração total de mercúrio.

Modelling shelf-ocean exchange and its biogeochemical consequences in coastal upwelling systems

DEFF Research Database (Denmark)

Muchamad, Al Azhar

margin bathymetry, and 3) what processes determine the observed variability of total organic carbon (TOC) content in shelf sediments underlying the upwelling system, with implications for the formation of petroleum source rocks. Here, a numerical ocean modeling approach is used in this thesis to explore...... processes and the development of anoxia/euxinia under the present day or past geological conditions. Thirdly and last, processes controlling distribution of total organic carbon (TOC) content in sediments across the continental margin is evaluated by application of the model to the Benguela upwelling system....... In the model, biological primary production and shelf bottom-water anoxia result in enhanced sedimentary TOC concentrations on the mid shelf and upper slope. The simulated TOCs implicate that bottom lateral transport only has a significant effect on increasing the deposition of the organic carbon on the mid...

Nutrients, Recycling, and Biological Populations in Upwelling Ecosystems

Energy Technology Data Exchange (ETDEWEB)

Whitledge, T. E.

1980-01-01

Nutrient recycling has been studied in the upwelling areas of Baja California, Northwest Africa, and Peru. Regeneration by biological populations in these areas contributes significant quantities of recycled nitrogen which is utilized in productivity processes. Each area has a different combination of organisms which leads to differences in the relative contributions of zooplankton, nekton, or benthos to the nutrient cycles. Comparisons of ammonium regeneration rates of zooplankton and nekton-micronekton populations in the three upwelling areas show that zooplankton recycle relatively less nitrogen in the Baja California and Peru systems than nekton. In the Northwest Africa upwelling region, however, zooplankton, fish, and benthic inputs are all substantial. In recent years the Peruvian upwelling system has been altered with the decline of the anchoveta population and an increase in the importance of zooplankton in nutrient recycling. The distribution of recycled nitrogen (ammonium and urea) in transects across the shelf at 10°S and 15°S indicates that regeneration is relatively more important at 10°S in the region of the wide shelf. In both areas the distribution of ammonium and urea are not entirely coincident thereby indicating differences in their production and/or utilization.

Geochemistry of surficial sediments along the central southwest coast of India - Seasonal changes in regional distribution

Digital Repository Service at National Institute of Oceanography (India)

Balachandran, K.K.; Joseph, T.; Nair, M.; Sankaranarayanan, V.N.; Das, V.K.; Sheeba, P.

was extended to about 2000 km 2 , also covering the nearest mud bank region. The samples were kept frozen prior to drying, grinding and analysis. Tex tural characteristics were determined foJlowing pipette anal ysis (KRUMBEIN and PETTIJOHN", 1938) and organic... of the trace metals (Fe, Ni, Cu and Zn) in high concen tration. Sediments of the upwelling coastal regions are reported to accumulate substantial amount ofmetals through organic in put, possibly from the upwelled waters (CALvlmT and PH/CEo 1983; DAESSLE et ai...

Changes in the coastal and marine environments

Digital Repository Service at National Institute of Oceanography (India)

DeSousa, S.N.; Ahmed, A.U.; DileepKumar, M.; Jagtap, T.G.; Sardessai, S.; Hassan, A.

to the euphotic layer. These factors make the Arabian Sea a potentially fertile area, since any vertical disturbance that can disrupt or shift the thermocline banier can lead to injection of nutrients into the euphotic layer and fuel increased biological...) injecting nutrients from the thermocline region into the surface layer, as observed by de Sousa et a!. (1996b). 1.1.3 Biological Response It was seen in sections 1.1.1-1.1.2 that processes of upwelling (both coastal and open ocean) during summer monsoon...

Oceanic upwelling and productivity in the eastern tropical Pacific

International Nuclear Information System (INIS)

Fiedler, P.C.; Philbrick, V.; Chavez, F.P.

1991-01-01

An oceanographic survey of the eastern tropical Pacific Ocean in August-November 1990 found a productive, nutrient-rich, moderately high-chlorophyll surface layer in two oceanic upwelling regions: the equatorial divergence, especially east of the Galapagos, and the countercurrent divergence out to 105 degree W, > 1,000 km west of the Costa Rica Dome. Although NO 3 is not depleted in upwelling regions, relationships among nutrient concentrations and temperature in 1986-1988 data from the same area show that NO 3 is the first macronutrient to be depleted in adjacent, less-productive regions. A three-dimensional, two-layer box model of NO 3 flux within and into the euphotic zone gives estimated rates of new production that are ∼29% of measured rates of 14 C phytoplankton production. Persistence of excess NO 3 in the euphotic zone exceeds 1 yr under high-nutrient, low-chlorophyll conditions off the equator where weak upwelling, or downwelling, occurs. These results indicate substantial control or limitation of NO 3 utilization and productivity in nutrient-rich oceanic regions of the eastern tropical Pacific

On an upwelling front along the west coast of India during later part of southwest monsoon

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.; Antony, M.K.

A coastal front, associated with upwelling, is identified from the observed thermal field along the west coast of India during September, 1987. The front, which is seen very clearly upto a depth of about 75 m, has a horizontal gradient...

Mantle Upwellings Below the Ibero-Maghrebian Region with a Common Deep Source from P Travel-time Tomography

Science.gov (United States)

Civiero, C.; Custodio, S.; Silveira, G. M.; Rawlinson, N.; Arroucau, P.

2017-12-01

The processes responsible for the geodynamical evolution of the Ibero-Maghrebian domain are still enigmatic. Several geophysical studies have improved our understanding of the region, but no single model has been accepted yet. This study takes advantage of the dense station networks deployed from France in the north to Canary Islands and Morocco in the south to provide a new high-resolution P-wave velocity model of the structure of the upper-mantle and top of the lower mantle. These images show subvertical small-scale upwellings below Atlas Range, Canary Islands and Central Iberia that seem to cross the transition zone. The results, together with geochemical evidence and a comparison with previous global tomographic models, reveal the ponding or flow of deep-plume material beneath the transition zone, which seems to feed upper-mantle "secondary" pulses. In the upper mantle the plumes, in conjunction with the subduction-related upwellings, allow the hot mantle to rise in the surrounding zones. During its rising, the mantle interacts with horizontal SW slab-driven flow which skirts the Alboran slab and connects with the mantle upwelling below Massif Central through the Valencia Trough rift.

Distribution and air–sea exchange of nitrous oxide in the coastal Bay of Bengal during peak discharge period (southwest monsoon)

Digital Repository Service at National Institute of Oceanography (India)

Rao, G.D.; Rao, V.D.; Sarma, V.V.S.S.

from monsoonal rivers containing high N sub(2)O concentrations, high nitrification rates and mild coastal upwelling. The sea-to-air fluxes of N sub(2)O suggest that NW region is a sink for atmospheric N sub(2)O due to discharge of under saturated water...

Influence of upwelling induced near shore hypoxia on the Alappuzha mud banks, South West Coast of India

Digital Repository Service at National Institute of Oceanography (India)

GireeshKumar, T.R.; Mathew, D.; Pratihary, A.K.; Naik, H.; Narvekar, K.U.; Araujo, J.; Balachandran, K.K.; Muraleedharan, K.R.; Thorat, B.R.; Nair, M.; Naqvi, S.W.A.

The results of the first time-series measurements spanning 18-weeks (22 April to 20 September 2014) from a coastal environment (Alappuzha, southwest India), where two process of upwelling and mud banks are concurrent during summer monsoon...

High resolution projections for the western Iberian coastal low level jet in a changing climate

Science.gov (United States)

Soares, Pedro M. M.; Lima, Daniela C. A.; Cardoso, Rita M.; Semedo, Alvaro

2017-09-01

The Iberian coastal low-level jet (CLLJ) is one of the less studied boundary layer wind jet features in the Eastern Boundary Currents Systems (EBCS). These regions are amongst the most productive ocean ecosystems, where the atmosphere-land-ocean feedbacks, which include marine boundary layer clouds, coastal jets, upwelling and inland soil temperature and moisture, play an important role in defining the regional climate along the sub-tropical mid-latitude western coastal areas. Recently, the present climate western Iberian CLLJ properties were extensively described using a high resolution regional climate hindcast simulation. A summer maximum frequency of occurrence above 30 % was found, with mean maximum wind speeds around 15 ms-1, between 300 and 400 m heights (at the jet core). Since the 1990s the climate change impact on the EBCS is being studied, nevertheless some lack of consensus still persists regarding the evolution of upwelling and other components of the climate system in these areas. However, recently some authors have shown that changes are to be expected concerning the timing, intensity and spatial homogeneity of coastal upwelling, in response to future warming, especially at higher latitudes, namely in Iberia and Canaries. In this study, the first climate change assessment study regarding the Western Iberian CLLJ, using a high resolution (9 km) regional climate simulation, is presented. The properties of this CLLJ are studied and compared using two 30 years simulations: one historical simulation for the 1971-2000 period, and another simulation for future climate, in agreement with the RCP8.5 scenario, for the 2071-2100 period. Robust and consistent changes are found: (1) the hourly frequency of occurrence of the CLLJ is expected to increase in summer along the western Iberian coast, from mean maximum values of around 35 % to approximately 50 %; (2) the relative increase of the CLLJ frequency of occurrence is higher in the north off western Iberia; (3

Changes in upwelling and surface productivity in the Eastern Pacific during Terminations I and II

Science.gov (United States)

Erdem, Z.; De Bar, M.; Stolwijk, D.; Schneider, R. R.; S Sinninghe Damsté, J.; Schouten, S.

2017-12-01

The Eastern Pacific coastal system is characterized by intense upwelling and consequently by an enhanced surface primary productivity. Combination of this high organic matter flux with sluggish bottom water ventilation results in one of the most pronounced oxygen minimum zones reaching from offshore California in the North to offshore Chile in the South. As a result of this process, the region is particularly interesting in view of nutrient and carbon cycling as well as ecosystem dynamics. The dynamics of the upwelling and oxygen concentrations are closely related to climatic conditions. Therefore, paleo-reconstructions of different settings are crucial in order to improve our understanding of the response of these nutrient-rich, oxygen-deficient, environments in relation to the recent global ocean warming, acidification and deoxygenation. In this study, we present downcore results from three different sites in the Eastern Pacific: offshore California (IODP site 1012), Peru (M77/2-52-2) and Chile (IODP site 1234). We applied different biomarkers as proxies to decipher changes in phytoplankton community composition, including the upwelling index based on long chain diols, and other common productivity indicators such as bulk organic carbon, carbonate and biogenic opal. In addition, application of carbon and nitrogen isotope ratios of total organic carbon and benthic foraminifera complement our multiproxy approach. Herewith we aim to compare at least two glacial-interglacial transitions with different magnitudes of deglacial warming along the Eastern Pacific upwelling systems at different latitudes. The data presented will cover the last 160 ka BP offshore California and Chile, and 30 ka BP offshore Peru enabling comparison between glacial Terminations I and II.

Wind-driven coastal upwelling along the western boundary of the Bay of Bengal during the southwest monsoon

Digital Repository Service at National Institute of Oceanography (India)

Shetye, S.R.; Shenoi, S.S.C.; Gouveia, A.D.; Michael, G.S.; Sundar, D.; Nampoothiri, G.

The western boundary regions of the world's oceans generally show the influence of remote forcing by the presence of a western boundary current. On the continental shelf off Florida, U.S.A., influence of the Gulf Stream is felt at locations as shallow as 75... upwelling on the Bay of Bengal 1403 ee" ~t 32 i i* Fig. 6. bo" , e.5, , , to" Salinity (ppt) at the surface. Dots indicate station locations. using available climatologies. The charts for 10-day mean ship-drift averaged over 1 ° x 1 ° given...

Distribution and burial of organic carbon in sediments from the Indian Ocean upwelling region off Java and Sumatra, Indonesia

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Baumgart, Anne; Jennerjahn, Tim; Mohtadi, Mahyar; Hebbeln, Dierk

2010-03-01

Sediments were sampled and oxygen profiles of the water column were determined in the Indian Ocean off west and south Indonesia in order to obtain information on the production, transformation, and accumulation of organic matter (OM). The stable carbon isotope composition (δ 13C org) in combination with C/N ratios depicts the almost exclusively marine origin of sedimentary organic matter in the entire study area. Maximum concentrations of organic carbon (C org) and nitrogen (N) of 3.0% and 0.31%, respectively, were observed in the northern Mentawai Basin and in the Savu and Lombok basins. Minimum δ 15N values of 3.7‰ were measured in the northern Mentawai Basin, whereas they varied around 5.4‰ at stations outside this region. Minimum bottom water oxygen concentrations of 1.1 mL L -1, corresponding to an oxygen saturation of 16.1%, indicate reduced ventilation of bottom water in the northern Mentawai Basin. This low bottom water oxygen reduces organic matter decomposition, which is demonstrated by the almost unaltered isotopic composition of nitrogen during early diagenesis. Maximum C org accumulation rates (CARs) were measured in the Lombok (10.4 g C m -2 yr -1) and northern Mentawai basins (5.2 g C m -2 yr -1). Upwelling-induced high productivity is responsible for the high CAR off East Java, Lombok, and Savu Basins, while a better OM preservation caused by reduced ventilation contributes to the high CAR observed in the northern Mentawai Basin. The interplay between primary production, remineralisation, and organic carbon burial determines the regional heterogeneity. CAR in the Indian Ocean upwelling region off Indonesia is lower than in the Peru and Chile upwellings, but in the same order of magnitude as in the Arabian Sea, the Benguela, and Gulf of California upwellings, and corresponds to 0.1-7.1% of the global ocean carbon burial. This demonstrates the relevance of the Indian Ocean margin off Indonesia for the global OM burial.

Distribution and evolution of sterols and aliphatic hydrocarbons in dated marine sediment cores from the Cabo Frio upwelling region, SW Atlantic, Brazil.

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Lourenço, Rafael André; Martins, César C; Taniguchi, Satie; Mahiques, Michel Michaelovitch; Montone, Rosalinda Carmela; Magalhães, Caio Augusto; Bícego, Márcia Caruso

2017-08-01

We report the distribution of selected lipid biomarkers specifically sterols and aliphatic hydrocarbons in sediment cores from Cabo Frio, SW Atlantic continental shelf, Brazil, corresponding approximately to the last 700 years. In the Cabo Frio region, a costal upwelling occurs as a quasi-seasonal phenomenon characterized by nutrient-rich bottom waters that intrude on the continental shelf and promote relatively high biological productivity compared to other Brazilian continental shelf areas. The results for sterols indicate the predominance of organic matter (OM) inputs related to marine organisms, mainly plankton, in all of the cores along the time scale studied. Principal component analyses show three different groups of variables, which may be associated with (i) the more effective intrusion of the nutrient-rich South Atlantic Central Water, resulting in the increase of marine lipid biomarkers such as sterols and short-chain n-alkanes; (ii) the influence of the Coastal Water with higher surface water temperature and subsequently lower primary productivity; and (iii) OM characterized by high total organic carbon and long-chain n-alkanes related to an allochthonous source. Relatively high concentrations of sterols and n-alkanes between 1450 and 1700 AD, chronologically associated with the Little Ice Age, suggest a period associated with changes in the local input of specific sources of these compounds. The concentrations of lipid biomarkers vary over core depth, but this does not suggest a notably high or low intensity of upwelling processes. It is possible that the climatic and sea surface temperature changes reported in previous studies did not affect the input of the sedimentary lipid biomarkers analyzed here.

Biogenic halocarbons from the Peruvian upwelling region as tropospheric halogen source

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H. Hepach

2016-09-01

Full Text Available Halocarbons are produced naturally in the oceans by biological and chemical processes. They are emitted from surface seawater into the atmosphere, where they take part in numerous chemical processes such as ozone destruction and the oxidation of mercury and dimethyl sulfide. Here we present oceanic and atmospheric halocarbon data for the Peruvian upwelling zone obtained during the M91 cruise onboard the research vessel METEOR in December 2012. Surface waters during the cruise were characterized by moderate concentrations of bromoform (CHBr3 and dibromomethane (CH2Br2 correlating with diatom biomass derived from marker pigment concentrations, which suggests this phytoplankton group is a likely source. Concentrations measured for the iodinated compounds methyl iodide (CH3I of up to 35.4 pmol L−1, chloroiodomethane (CH2ClI of up to 58.1 pmol L−1 and diiodomethane (CH2I2 of up to 32.4 pmol L−1 in water samples were much higher than previously reported for the tropical Atlantic upwelling systems. Iodocarbons also correlated with the diatom biomass and even more significantly with dissolved organic matter (DOM components measured in the surface water. Our results suggest a biological source of these compounds as a significant driving factor for the observed large iodocarbon concentrations. Elevated atmospheric mixing ratios of CH3I (up to 3.2 ppt, CH2ClI (up to 2.5 ppt and CH2I2 (3.3 ppt above the upwelling were correlated with seawater concentrations and high sea-to-air fluxes. During the first part of the cruise, the enhanced iodocarbon production in the Peruvian upwelling contributed significantly to tropospheric iodine levels, while this contribution was considerably smaller during the second part.

Application of the Hyperspectral Imager for the Coastal Ocean to Phytoplankton Ecology Studies in Monterey Bay, CA, USA

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John P. Ryan

2014-01-01

Full Text Available As a demonstrator for technologies for the next generation of ocean color sensors, the Hyperspectral Imager for the Coastal Ocean (HICO provides enhanced spatial and spectral resolution that is required to understand optically complex aquatic environments. In this study we apply HICO, along with satellite remote sensing and in situ observations, to studies of phytoplankton ecology in a dynamic coastal upwelling environment—Monterey Bay, CA, USA. From a spring 2011 study, we examine HICO-detected spatial patterns in phytoplankton optical properties along an environmental gradient defined by upwelling flow patterns and along a temporal gradient of upwelling intensification. From a fall 2011 study, we use HICO’s enhanced spatial and spectral resolution to distinguish a small-scale “red tide” bloom, and we examine bloom expansion and its supporting processes using other remote sensing and in situ data. From a spectacular HICO image of the Monterey Bay region acquired during fall of 2012, we present a suite of algorithm results for characterization of phytoplankton, and we examine the strengths, limitations, and distinctions of each algorithm in the context of the enhanced spatial and spectral resolution.

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

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Saliou eFaye

2015-09-01

Full Text Available The climatological seasonal cycle of the sea surface temperature (SST in the north-eastern tropical Atlantic (7-25°N, 26-12°W is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ. The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N, and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm the surface north (south of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.Keywords: SST, upwelling, circulation, heat budget, observations, modeling

Wind influence on a coastal buoyant outflow

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Whitney, Michael M.; Garvine, Richard W.

2005-03-01

This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ Wind events, however, overwhelm the buoyancy-driven flow (∣Ws∣ > 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

Yearly variation of bacterial production in the Arraial do Cabo protection area (Cabo Frio upwelling region): an evidence of anthropogenic pressure.

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Coelho-Souza, Sérgio A; Pereira, Gilberto C; Coutinho, Ricardo; Guimarães, Jean R D

2013-12-01

Arraial do Cabo is where upwelling occurs more intensively on the Brazilian coast. Although it is a protection area it suffers anthropogenic pressure such as harbor activities and sporadic sewage emissions. Short-time studies showed a high variability of bacterial production (BP) in this region but none of them evaluated BP during long periods in a large spatial scale including stations under different natural (upwelling and cold fronts) and anthropogenic pressures. During 2006, we sampled surface waters 10 times (5 in upwelling and 5 in subsidence periods) in 8 stations and we measured BP, temperature as well as the concentrations of inorganic nutrients, pigments and particulate organic matter (POM). BP was up to 400 times higher when sewage emissions were observed visually and it had a positive correlation with ammonia concentrations. Therefore, in 2007, we did two samples (each during upwelling and subsidence periods) during sewage emissions in five stations under different anthropogenic pressure and we also measured particles abundance by flow cytometry. The 12 samples in the most impacted area confirmed that BP was highest when ammonia was higher than 2 μM, also reporting the highest concentrations of chlorophyll a and suspended particles. However, considering all measured variables, upwelling was the main disturbing factor but the pressure of fronts should not be neglected since it had consequences in the auto-heterotrophic coupling, increasing the concentrations of non fluorescent particles and POM. Stations clustered in function of natural and anthropogenic pressures degrees and both determined the temporal-spatial variability.

The Effect of Barotropic and Baroclinic Tides on Coastal Stratification and Mixing

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Suanda, S. H.; Feddersen, F.; Kumar, N.

2017-12-01

The effects of barotropic and baroclinic tides on subtidal stratification and vertical mixing are examined with high-resolution, three-dimensional numerical simulations of the Central Californian coastal upwelling region. A base simulation with realistic atmospheric and regional-scale boundary forcing but no tides (NT) is compared to two simulations with the addition of predominantly barotropic local tides (LT) and with combined barotropic and remotely generated, baroclinic tides (WT) with ≈ 100 W m-1 onshore baroclinic energy flux. During a 10 day period of coastal upwelling when the domain volume-averaged temperature is similar in all three simulations, LT has little difference in subtidal temperature and stratification compared to NT. In contrast, the addition of remote baroclinic tides (WT) reduces the subtidal continental shelf stratification up to 50% relative to NT. Idealized simulations to isolate barotropic and baroclinic effects demonstrate that within a parameter space of typical U.S. West Coast continental shelf slopes, barotropic tidal currents, incident energy flux, and subtidal stratification, the dissipating baroclinic tide destroys stratification an order of magnitude faster than barotropic tides. In WT, the modeled vertical temperature diffusivity at the top (base) of the bottom (surface) boundary layer is increased up to 20 times relative to NT. Therefore, the width of the inner-shelf (region of surface and bottom boundary layer overlap) is increased approximately 4 times relative to NT. The change in stratification due to dissipating baroclinic tides is comparable to the magnitude of the observed seasonal cycle of stratification.

Currents and upwelling along the Latium coasts in the Central Tyrrhenian Sea (western Mediterranean

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V. Rossi

1995-04-01

Full Text Available In this study, springtime coastal currents along the Latium coast and their relation to external forcings, mainly wind stress curl and atmospheric pressure, are analysed. As a main result, we find that hydrographical measurements reveal currents parallel to the bottom isobaths, but with isopycnal sloping upwards towards the coast, suggesting the importance of upwellings in determining the coastal currents. This is confirmed by thermal satellite data showing the presence of a ~10-km-wide patch of cold water east of Mount Argentario, i.e. a cyclonic vortex. The current meter data give rather small values of the time-averaged alongshore velocities (~2 cm s–1 for most current meters and ~3 cm s–1 for the current meter placed immediately off the Argentario and also smaller values for the offshore velocities. The correlation between these two types of currents is rather poor; this is also due to the variability characteristic of a wind-induced upwelling. Finally, we obtain a value of 0.74 for the correlation between the alongshore current (first mode of Empirical Orthogonal Functions decomposition and the wind stress if a 23-h time lag is assumed.

Uncovering a New Current: The Southwest MAdagascar Coastal Current

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Ramanantsoa, Juliano D.; Penven, P.; Krug, M.; Gula, J.; Rouault, M.

2018-02-01

Cruise data sets, satellite remote sensing observations, and model data analyses are combined to highlight the existence of a coastal surface poleward flow in the southwest of Madagascar: the Southwest MAdagascar Coastal Current (SMACC). The SMACC is a relatively shallow (water surface signature of the SMACC extends from 22°S (upstream) to 26.4°S (downstream). The SMACC exhibits a seasonal variability: more intense in summer and reduced in winter. The average volume transport of its core is about 1.3 Sv with a mean summer maximum of 2.1 Sv. It is forced by a strong cyclonic wind stress curl associated with the bending of the trade winds along the southern tip of Madagascar. The SMACC directly influences the coastal upwelling regions south of Madagascar. Its existence is likely to influence local fisheries and larval transport patterns, as well as the connectivity with the Agulhas Current, affecting the returning branch of the global overturning circulation.

Transcriptomics reveal transgenerational effects in purple sea urchin embryos: Adult acclimation to upwelling conditions alters the response of their progeny to differential pCO2 levels.

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Wong, Juliet M; Johnson, Kevin M; Kelly, Morgan W; Hofmann, Gretchen E

2018-03-01

Understanding the mechanisms with which organisms can respond to a rapidly changing ocean is an important research priority in marine sciences, especially in the light of recent predictions regarding the pace of ocean change in the coming decades. Transgenerational effects, in which the experience of the parental generation can shape the phenotype of their offspring, may serve as such a mechanism. In this study, adult purple sea urchins, Strongylocentrotus purpuratus, were conditioned to regionally and ecologically relevant pCO 2 levels and temperatures representative of upwelling (colder temperature and high pCO 2 ) and nonupwelling (average temperature and low pCO 2 ) conditions typical of coastal upwelling regions in the California Current System. Following 4.5 months of conditioning, adults were spawned and offspring were raised under either high or low pCO 2 levels, to examine the role of maternal effects. Using RNA-seq and comparative transcriptomics, our results indicate that differential conditioning of the adults had an effect on the gene expression patterns of the progeny during the gastrula stage of early development. For example, maternal conditioning under upwelling conditions intensified the transcriptomic response of the progeny when they were raised under high versus low pCO 2 conditions. Additionally, mothers that experienced upwelling conditions produced larger progeny. The overall findings of this study are complex, but do suggest that transgenerational plasticity in situ could act as an important mechanism by which populations might keep pace with rapid environmental change. © 2018 John Wiley & Sons Ltd.

Global Climatology of the Coastal Low-Level Wind Jets using different Reanalysis

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Lima, Daniela C. A.; Soares, Pedro M. M.; Semedo, Alvaro; Cardoso, Rita M.

2016-04-01

Coastal Low-Level Jets (henceforth referred to as "coastal jets" or simply as CLLJ) are low-tropospheric mesoscale wind features, with wind speed maxima confined to the marine atmospheric boundary layer (MABL), typically bellow 1km. Coastal jets occur in the eastern flank of the semi-permanent subtropical mid-latitude high pressure systems, along equatorward eastern boundary currents, due to a large-scale synoptic forcing. The large-scale synoptic forcing behind CLLJ occurrences is a high pressure system over the ocean and a thermal low inland. This results in coastal parallel winds that are the consequence of the geostrophic adjustment. CLLJ are found along the California (California-Oregon) and the Canary (Iberia and Northeastern Africa) currents in the Northern Hemisphere, and along the Peru-Humboldt (Peru-Chile), Benguela (Namibia) and Western Australia (West Australia) currents in the Southern Hemisphere. In the Arabian Sea (Oman CLLJ), the interaction between the high pressure over the Indian Ocean in summer (Summer Indian Monsoon) and the Somali (also known as Findlater) Jet forces a coastal jet wind feature off the southeast coast of Oman. Coastal jets play an important role in the regional climates of the mid-latitude western continental regions. The decrease of the sea surface temperatures (SST) along the coast due to upwelling lowers the evaporation over the ocean and the coast parallel winds prevents the advection of marine air inshore. The feedback processes between the CLLJ and upwelling play a crucial role in the regional climate, namely, promoting aridity since the parallel flow prevents the intrusion of moisture inland, and increasing fish stocks through the transport of rich nutrient cold water from the bottom. In this study, the global coastal low-level wind jets are identified and characterized using an ensemble of three reanalysis, the ECMWF Interim Reanalysis (ERA-Interim), the Japanese 55-year Reanalysis (JRA-55) and the NCEP Climate Forecast

International cooperation for integrated management of coastal regions

International Nuclear Information System (INIS)

Bosc, E.; Houlbreque, F.; Boisson, F.; Scholten, J.; Betti, M.

2010-01-01

Coastal zones which comprise < 20% of the earth surface are one of the most dynamic areas of the world. Housing more than 50% of the earth's population, the coastal zones are affected by natural and anthropogenic induced pressures which challenge the sustainability of the coastal environment and its resources. Most of the environmental pressures originate from outside the coastal zones thus requiring an inter-regional approach for coastal environmental assessments. It is one of the missions of the Marine Environment Laboratories (MEL) of the International Atomic Energy Agency to assist Member States in coastal zone management by applying nuclear and isotopic techniques. These techniques are used in many ways at MEL to enhance the understanding of marine ecosystems and to improve their management and protection. The article gives an overview of MEL's current marine coastal projects and research activities. (author)

Case Study of the California Low Level Coastal Jet Comparisons Between Observed and Model-Estimated Winds and Temperatures using WRF and COAMPS

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Tomé, Ricardo; Semedo, Alvaro; Ranjha, Raza; Tjernström, Michael; Svensson, Gunilla

2010-05-01

A low level coastal jet (LLCJ) is a low-troposphereic wind feature driven by the pressure gradient produced by a sharp contrast between high temperatures over land and lower temperatures over sea. This feature has been identified and studied in several areas of the world, where such a land-sea temperature contrast exist: off the coast of Somalia, near Lima, Peru, off the Mediterranean coast of Spain, in the Southwest coast of Africa, or in the South China Sea coast. Nevertheless, the California LLCJ is probably the most studied coastal jet in the world, with several studies available in the literature. Coastal jets have a notorious impact on coastal areas. Climatologically they are associated with coastal upwelling processes. The major coastal fishing grounds in the world are usually in areas of upwelling, and the abundance of fish at the surface is supported by the upwelled nutrient-rich waters from deeper levels. The effect of this upwelled water to the fishing industry and to the habitat of an enormous diversity of marine life is of paramount importance, and has led to numerous studies in this field. Littoral areas are usually densely populated, and often airports are built in areas where a LLCJ may occur. Thus, aviation operations are deeply influenced by this weather feature, which has a significant impact on the takeoff and landing of airplanes. Therefore the forecasting of LLCJ features is very important for several reasons.The forecasting skills of mesoscale models, while challenging in any region, become particularly complex near coastlines, where processes associated with the coastal boundary add additional complexity: interaction of the flow with the coastal orography, sharp sea-land temperature gradients, highly baroclinic environment, complex air-sea exchanging processes, etc. The purpose of this study is to assess the forecasting skills of the limited-area models WRF (Weather Research and Forecasting) and COAMPS® (Coupled Ocean-Atmosphere Mesoscale

Modelling an alkenone-like proxy record in the NW African upwelling

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X. Giraud

2006-01-01

Full Text Available A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy, alkenones, are produced at the sea surface and recorded in the slope sediments. The biogeochemical model has two phytoplankton groups: an alkenone producer group, considered to be coccolithophores, and a group comprising other phytoplankton. The Regional Ocean Modelling System (ROMS is used to simulate the ocean circulation and takes advantage of the Adaptive Grid Refinement in Fortran (AGRIF package to set up an embedded griding system. In the simulations the alkenone temperature records in the sediments are between 1.1 and 2.3°C colder than the annual mean SSTs. Despite the seasonality of the coccolithophore production, this temperature difference is not mainly due to a seasonal bias, nor to the lateral advection of phytoplankton and phytodetritus seaward from the cold near-shore waters, but to the production depth of the coccolithophores. If coretop alkenone temperatures are effectively recording the annual mean SSTs, the amount of alkenone produced must vary among the coccolithophores in the water column and depend on physiological factors (e.g. growth rate, nutrient stress.

NOAA's Coastal Change Analysis Program (C-CAP) 2001 Regional Land Cover Data - Coastal United States

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National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2016 Regional Land Cover Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2006 Regional Land Cover Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1985 Regional Land Cover Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1996 Regional Land Cover Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1992 Regional Land Cover Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

Intensification of Chile-Peru upwelling under climate change: diagnosing the impact of natural and anthropogenic forcing from the IPSL-CM5 model.

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Jebri, B.; Khodri, M.; Gastineau, G.; Echevin, V.; Thiria, S.

2017-12-01

Upwelling is critical to the biological production, acidification, and deoxygenation of the ocean's major eastern boundary current ecosystems. A conceptual hypothesis suggests that the winds that favour coastal upwelling intensify with anthropogenic global warming due to increased land-sea temperature contrast. We examine this hypothesis for the dynamics of the Peru-Chile upwelling using a set of four large ensembles of coupled, ocean-atmosphere model simulations with the IPSL model covering the 1940-2014 period. In one large ensemble we prescribe the standard CMIP5 greenhouse gas (GHG) concentrations, anthropogenic aerosol, ozone and volcanic forcings, following the historical experiments through 2005 and RCP8.5 from 2006-2014, while the other ensembles consider separately the GHG, ozone and volcanic forcings. We find evidence for intensification of upwelling-favourable winds with however little evidence of atmospheric pressure gradients in response to increasing land-sea temperature differences. Our analyses reveal poleward migration and intensification of the South Pacific Anticyclone near poleward boundaries of climatological Peruvian and Chilean upwelling zones. This contribution further investigates the physical mechanisms for the Peru-Chile upwelling intensification and the relative role of natural and anthropogenic forcings.

Effects of natural and human-induced hypoxia on coastal benthos

OpenAIRE

Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, S. W. A.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-01-01

Coastal hypoxia (<1.42 ml L⁻¹; 62.5 μM; 2 mg L⁻¹, approx. 30% oxygen saturation) occurs seasonally in many estuaries, fjords, and along open coasts subject to upwelling or excessive riverine nutrient input, and permanently in some isolated seas and marine basins. Underlying causes of hypoxia include enhanced nutrient input from natural causes (upwelling) or anthropogenic origin (eutrophication) and reduction of mixing by...

Radiolarian Indices of Paleoproductivity Variation in the late Pleistocene Benguela Upwelling System, ODP Site 1084

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Bittniok, B. B.; Lazarus, D. B.; Diester-Haass, L.; Billups, K.; Meyers, P.

2006-12-01

Changes in export productivity play a significant role in ocean carbon budgets and global climate change. Proxies for export productivity can be difficult to interpret: benthic foraminifera accumulation rates (BFAR) can be affected by carbonate dissolution in organic-carbon rich sediments; bulk opal can be affected by silica limitation of source waters. Recent work (Lazarus et al. 2006; Mar. Micropal.) has shown that a new index based on radiolarian faunal changes (WADE ratio) correlates well to total organic carbon (TOC) values from the same samples over the long term (latest Miocene-Recent) history of productivity in the Benguela Upwelling System (BUS). We present new data on variation in export productivity proxies (WADE, TOC, carbonate, radiolarian opal, BFAR) for the last glacial-interglacial cycle from ODP Site 1084, located just offshore from the main coastal upwelling cells of the BUS. Our age model, from mean Quaternary sedimentation rates (Leg 175 Scientific Results), is in accordance with cyclic variation in other climate sensitive parameters (carbonate and color reflectance). Although opal content and radiolarian preservation is only moderate in our samples, WADE values vary significantly and suggest higher productivity during the last glacial, in accordance with current interpretations of BUS history. Radiolarian opal accumulation is also higher during the last glacial, suggesting that silica limitation (opal paradox) conditions did not dominate over this time period. Similar results for bulk opal have been reported from late Quaternary piston cores from the more northerly Congo upwelling region (Schneider et al, 1997; Paleoc.). We conclude that WADE ratios are a useful proxy for late Pleistocene productivity in the BUS at glacial- interglacial time scales.

Large Topographic Rises on Venus: Implications for Mantle Upwelling

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Stofan, Ellen R.; Smrekar, Suzanne E.; Bindschandler, Duane L.; Senske, David A.

1995-01-01

Topographic rises on Venus have been identified that are interpreted to be the surface manifestation of mantle upwellings. These features are classified into groups based on their dominant morphology. Atla and Beta Regiones are classified as rift-dominated, Dione, western Eistla, Bell, and Imdr Regiones as volcano-dominated, and Themis, eastern Eistla, and central Eistla Regiones as corona-dominated. At several topographic rises, geologic indicators were identified that may provide evidence of uplifted topography (e.g., volcanic flow features trending upslope). We assessed the minimum contribution of volcanic construction to the topography of each rise, which in general represents less than 5% of the volume of the rise, similar to the volumes of edifices at terrestrial hotspot swells. The total melt volume at each rise is approximated to be 10(exp 4) - 10(exp 6) cu km. The variations in morphology, topography, and gravity signatures at topographic rises are not interpreted to indicate variations in stage of evolution of a mantle upwelling. Instead, the morphologic variations between the three classes of topographic rises are interpreted to indicate the varying influences of lithospheric structure, plume characteristics, and regional tectonic environment. Within each class, variations in topography, gravity, and amount of volcanism may be indicative of differing stages of evolution. The similarity between swell and volcanic volumes for terrestrial and Venusian hotspots implies comparable time-integrated plume strengths for individual upwellings on the two planets.

Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystem

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Galán, Alexander; Thamdrup, Bo; Saldías, Gonzalo S.; Farías, Laura

2017-10-01

The upwelling system off central Chile (36.5° S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30-50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N2 and/or N2O, were studied using 15N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. Incubations were developed using water retrieved from the oxycline (25 m depth) and bottom waters (85 m depth) over the continental shelf off Concepción, Chile. Results of 15N-labelled incubations revealed higher N removal activity during the austral summer, with denitrification as the dominant N2-producing pathway, which occurred together with anammox at all times. Interestingly, in both spring and summer maximum potential N removal rates were observed in the oxycline, where a greater availability of oxygen was observed (maximum O2 fluctuation between 270 and 40 µmol L-1) relative to the hypoxic bottom waters ( multiple N-cycling processes are modulating the isotopic nitrate composition over the shelf off central Chile during spring and summer. N removal processes in this coastal system appear to be related to the availability and distribution of oxygen and particles, which are a source of organic matter and the fuel for the production of other electron donors (i.e. ammonium) and acceptors (i.e. nitrate and nitrite) after its remineralization. These results highlight the links between several pathways involved in N loss. They also establish that different mechanisms supported by alternative N substrates are responsible for substantial accumulation of N2O, which are frequently observed as hotspots in the

Geomorphic Regionalization of Coastal Zone Using Geospatial Technology

Directory of Open Access Journals (Sweden)

Manoranjan Mishra

2016-08-01

Full Text Available The world coastal environment is made of diversified landforms and are also potentially vulnerable to climate variability, delta sinking, extreme events and anthropogenic interferences. Sustainable management of coastal resources and transforming quality ecosystem services to future generation are the goals of Integrated Coastal Zone Management (ICZM. Geographical homogenous unit are the basic implementation locus and back bone of these kinds of integrated management strategy and activities. However, coastal zone management projects in developing world using use arbitrary land-ward and sea-ward boundaries from physical reference as unit of management. The oversimplified fixed distance approaches are not able to map the spatial and temporal changes in coastal systems. The spatio-temporal variations of coastal systems are configured in geomorphic landforms and further that work on interaction between natural forces and anthropogenic inputs. The present research work is an attempt to present a simplified method of regionalization geomorphic landforms using geospatial platforms for delineating Orissa coast into smaller homogenous geographic unit as reference point for future management. Geomorphic landforms are reconstructed using Enhanced Thematic Mapper Plus (ETM+ imagery, Survey of India topomaps, field survey and Digital Elevation Model data at geographic information system (GIS plat form. Seventy geomorphic features covering an area of 5033.64 km2 were identified and further, regionalized into five homogenous geographic units. The need of time is to recognize unsustainable coastal systems in these homogenous geographic units by fine tuning development parameters and also same time allowing coastal systems to adapt naturally to any kind of variability. Although, the methodology applied to Orissa for delineation homogenous geographic area but it can be replicated to any coast in world.

Human-mediated drivers of change — impacts on coastal ...

African Journals Online (AJOL)

Human-mediated drivers of change — impacts on coastal ecosystems and marine ... of global change because they are located at the land–ocean interface and ... upwelling regimes are all being affected by human-mediated climate change.

Oceanographic features of the upwelling in front of Gaira's intent Magdalena Department, minor dry season of 2006

International Nuclear Information System (INIS)

Arevalo Martinez, Damian Leonardo; Franco Herrera, Andres

2008-01-01

In order to determine the influence of the ocean and atmospheric coupling dynamics on upwelling events, caused by Ekman's transport and by continental winds, as well as the possible fertilization effect produced by the increasing of the concentration of inorganic nutrients in coastal waters of Gaira's inlet, Magdalena department, during the minor dry season of 2006, atmospheric, oceanographic, and biological variables were measured by the implementation of the Eurelian method. A total of four samplings were carried out, among which two presented atmospheric and oceanic conditions that evidence the occurrence of upwelling events 48 hours before in response to strong winds coming from northeast (trade winds) and from the continent, whereas the other two samplings presented similar characteristics to those typical of rainy seasons. During this study, wind velocity and direction presented expected values during upwelling events caused by Ekman's transport and by continental winds (≥ 4.5 m/s, 26 Celsius degrade and 120 Celsius degrade, respectively), generating enough stress levels in the sea surface layer that could move it offshore (1.2 dynes/cm 2 ). During the days following the upwelling events, anomalies in water physical and chemical characteristics were observed, presenting low temperatures (26.1 +- 1.1 Celsius degrade), high salinity (36.0 +- 0.5) and, as a consequence, high densities (δ 26.31 +- 0.50), as well as low dissolved oxygen levels (4.04 +- 0.29 mL/L) and predominant subsaturation (84.3 +- 6.1 %) Inorganic nutrient concentration showed a relatively homogeneous behavior, keeping low nitrite (0.35 +- 0.02 μM) and phosphate (0.30 +- 0.01 μM) levels during all samplings, whereas the mean ammonium concentration was relatively high (1.08 +- 0.11 μM). In contrast, nitrate levels were high during all samplings, with higher values corresponding to upwelling events (9.48 +- 0.49 μM), although variation was not statistically significative. Phytoplanktonic

Factors structuring the phytoplankton community in the upwelling site off El Loa River in northern Chile

Science.gov (United States)

Herrera, Liliana; Escribano, Ruben

2006-06-01

Understanding processes affecting the structure of the autotrophic community in marine ecosystems is relevant because species-dependent characters may affect productivity and carbon fluxes of the ocean. In this work, we studied the influence of oceanographic variability on phytoplankton species composition at a coastal upwelling site off northern Chile. Four seasonal cruises carried out during 2003 off El Loa River (21°S) showed that upwelling occurs year-round supporting a large number of diatoms, dinoflagellates, naked nanoflagellates, and silicoflagellates. The analysis of species composition showed that changes in the structure of the autotrophic community are expressed both in abundance and in differences in species assemblages. These changes occurred not only over the seasonal scale but also over the spatial pattern of distribution, and they correlated well to temporal variability of upwelling and spatial variation of upwelling conditions over the cross-shelf axis. A K-means clustering and principal component analyses showed that species assemblages can be represented by few dominant species strongly coupled to alternate upwelling vs. non-upwelling conditions. Both conditions are well defined, and mostly explained by changes in depth of the upper boundary of the oxygen minimum zone (OMZ) (a prominent feature in northern Chile), surface temperature and water column stratification. Abundance of dominant phytoplankton species were strongly correlated to both OMZ depth and water column stratification. Processes through which OMZ depth might influence species abundance and composition are unknown, although they may relate to changes in redox conditions which affect the nutrient field. Another explanation may relate to changes in grazing pressure derived from the effect of low oxygen water on zooplankton vertical distribution.

The Benguela upwelling system lying off southern Africa's west ...

African Journals Online (AJOL)

spamer

Africa's west coast is one of the world's four main upwelling ..... Regions of current shear, convergence and divergence, as well ..... between Cape Point and Danger Point in 1975. .... processes in relation to eastern boundary current pelagic.

A long history of equatorial deep-water upwelling in the Pacific Ocean

Science.gov (United States)

Zhang, Yi Ge; Pagani, Mark; Henderiks, Jorijntje; Ren, Haojia

2017-06-01

Cold, nutrient- and CO2-rich waters upwelling in the eastern equatorial Pacific (EEP) give rise to the Pacific cold tongue. Quasi-periodic subsidence of the thermocline and attenuation in wind strength expressed by El Niño conditions decrease upwelling rates, increase surface-water temperatures in the EEP, and lead to changes in regional climates both near and far from the equatorial Pacific. EEP surface waters have elevated CO2 concentrations during neutral (upwelling) or La Niña (strong upwelling) conditions. In contrast, approximate air-sea CO2 equilibrium characterizes El Niño events. One hypothesis proposes that changes in physical oceanography led to the establishment of a deep tropical thermocline and expanded mixed-layer prior to 3 million years ago. These effects are argued to have substantially reduced deep-water upwelling rates in the EEP and promoted a "permanent El Niño-like" climate state. For this study, we test this supposition by reconstructing EEP "excess CO2" and upwelling history for the past 6.5 million years using the alkenone-pCO2 methodology. Contrary to previous assertions, our results indicate that average temporal conditions in the EEP over the past ∼6.5 million years were characterized by substantial CO2 disequilibrium and high nutrient delivery to surface waters - characteristics that imply strong upwelling of deep waters. Upwelling appears most vigorous between ∼6.5 to 4.5 million years ago coinciding with high accumulation rates of biogenic material during the late Miocene - early Pliocene "biogenic bloom".

Long-time observation of annual variation of Taiwan Strait upwelling in summer season

Science.gov (United States)

Tang, D. L.; Kawamura, H.; Guan, L.

The Taiwan Strait is between Taiwan Island and Mainland China, where several upwelling zones are well known for good fishing grounds. Earlier studies in the strait have been conducted on detecting upwelling by ship measurements with short-term cruises, but long-term variations of upwelling in this region are not understood. The present paper examines satellite images for a long-time observation of two major upwelling zones in the Taiwan Strait: Taiwan Bank Upwelling (TBU) and Dongshan Upwelling (DSU). Sea surface temperature (SST) and chlorophyll a (Chl-a) images have been analyzed for summer months (June, July, and August) from 1980 to 2002. Results reveal annual variation of two upwelling zones. These two upwelling zones occur every year characterized with distinct low water temperature and high Chl-a concentrations. During the period from 1989 to 1998, SST is found to be 1.15 °C lower in TBU, and 1.42 °C lower in the DSU than the Taiwan Strait. The size of DSU has been found to be larger during summer of 1989, 1990, 1993 and 1995; TBU has been found to be weak during summer of 1994 and 1997. Ocean color images obtained from CZCS, OCI, and SeaWiFS also show high Chl-a concentrations (0.8-2.5 mg m-3) in two upwelling zones, which coincide with low SST in terms of location, shape, and time. These high Chl-a concentrations in TBU and DSU may be related to upwelling waters that bring nutrients from bottom to surface. The present results also show the potential of using satellite data for monitoring of ocean environment for long time period.

Defining seascapes for marine unconsolidated shelf sediments in an eastern boundary upwelling region: The southern Benguela as a case study

Science.gov (United States)

Karenyi, Natasha; Sink, Kerry; Nel, Ronel

2016-02-01

Marine unconsolidated sediment habitats, the largest benthic ecosystem, are considered physically controlled ecosystems driven by a number of local physical processes. Depth and sediment type are recognised key drivers of these ecosystems. Seascape (i.e., marine landscape) habitat classifications are based solely on consistent geophysical features and provide an opportunity to define unconsolidated sediment habitats based on processes which may vary in distribution through space and time. This paper aimed to classify unconsolidated sediment seascapes and explore their diversity in an eastern boundary upwelling region at the macro-scale, using the South African west coast as a case study. Physical variables such as sediment grain size, depth and upwelling-related variables (i.e., maximum chlorophyll concentration, austral summer bottom oxygen concentration and sediment organic carbon content) were included in the analyses. These variables were directly measured through sampling, or collated from existing databases and the literature. These data were analysed using multivariate Cluster, Principal Components Ordination and SIMPER analyses (in PRIMER 6 + with PERMANOVA add-in package). There were four main findings; (i) eight seascapes were identified for the South African west coast based on depth, slope, sediment grain size and upwelling-related variables, (ii) three depth zones were distinguished (inner, middle and outer shelf), (iii) seascape diversity in the inner and middle shelves was greater than the outer shelf, and (iv) upwelling-related variables were responsible for the habitat diversity in both inner and middle shelves. This research demonstrates that the inclusion of productivity and its related variables, such as hypoxia and sedimentary organic carbon, in seascape classifications will enhance the ability to distinguish seascapes on continental shelves, where productivity is most variable.

Phytoplankton stimulation in frontal regions of Benguela upwelling filaments by internal factors

Directory of Open Access Journals (Sweden)

Norbert Wasmund

2016-11-01

Full Text Available Filaments are intrusions of upwelling water into the sea, separated from the surrounding water by fronts. Current knowledge explains the enhanced primary production and phytoplankton growth found in frontal areas by external factors like nutrient input. The question is whether this enhancement is also caused by intrinsic factors, i.e. simple mixing without external forcing. In order to study the direct effect of frontal mixing on organisms, disturbing external influx has to be excluded. Therefore mixing was simulated by joining waters originating from inside and outside the filament in mesocosms (tanks. These experiments were conducted during two cruises in the northern Benguela upwelling system in September 2013 and January 2014. The mixed waters reached a much higher net primary production and chlorophyll a (chla concentration than the original waters already 2-3 days after their merging. The peak in phytoplankton biomass stays longer than the chla peak. After their maxima, primary production rates decreased quickly due to depletion of the nutrients. The increase in colored dissolved organic matter (CDOM may indicate excretion and degradation. Zooplankton is not quickly reacting on the changed conditions. We conclude that already simple mixing of two water bodies, which occurs generally at fronts between upwelled and ambient water, leads to a short-term stimulation of the phytoplankton growth. However, after the exhaustion of the nutrient stock, external nutrient supply is necessary to maintain the enhanced phytoplankton growth in the frontal area. Based on these data, some generally important ecological factors are discussed as for example nutrient ratios and limitations, silicate requirements and growth rates.

Regional Climate Modelling of the Western Iberian Low-Level Wind Jet

Science.gov (United States)

Soares, Pedro M. M.; Lima, Daniela C. A.; Cardoso, Rita M.; Semedo, Álvaro

2016-04-01

The Iberian coastal low-level jet (CLLJ) is one the less studied boundary layer wind jet features in the Eastern Boundary Currents Systems (EBCS). These regions are amongst the most productive ocean ecosystems, where the atmosphere-land-ocean feedbacks, which include marine boundary layer clouds, coastal jets, upwelling and inland soil temperature and moisture, play an important role in defining the regional climate along the sub-tropical mid-latitude western coastal areas. Recently, the present climate western Iberian CLLJ properties were extensively described using a high resolution regional climate hindcast simulation. A summer maximum frequency of occurrence above 30% was found, with mean maximum wind speeds around 15 ms-1, between 300 and 400m heights (at the jet core). Since the 1990s the climate change impact on the EBCS is being studied, nevertheless some lack of consensus still persists regarding the evolution of upwelling and other components of the climate system in these areas. However, recently some authors have shown that changes are to be expected concerning the timing, intensity and spatial homogeneity of coastal upwelling and of CLLJs, in response to future warming, especially at higher latitudes, namely in Iberia and Canaries. In this study, the first climate change assessment study regarding the Western Iberian CLLJ, using a high resolution (9km) regional climate simulation, is presented. The properties of this CLLJ are studied and compared using two 30 years simulations: one historical simulation for the 1971-2000 period, and another simulation for future climate, in agreement with the RCP8.5 scenario, for the 2071-2100 period. Robust and consistent changes are found: 1) the hourly frequency of occurrence of the CLLJ is expected to increase in summer along the western Iberian coast, from mean maximum values of around 35% to approximately 50%; 2) the relative increase of the CLLJ frequency of occurrence is higher in the north off western Iberia

Convergent tectonics and coastal upwelling: a history of the Peru continental margin ( Pacific).

Science.gov (United States)

von Huene, Roland E.; Suess, E.; Emeis, K.C.

1987-01-01

Late in 1986, scientists on the ODP drillship JOIDES Resolution confirmed that the upper slope of the Peruvian margin consists of continental crust whereas the lower slope comprises an accretionary complex. An intricate history of horizontal and vertical movements can be detected, and the locations of ancient centers of upwelling appear to have varied, partly due to tectonic movements of the margin. In this review of Leg 112, the 3 scientific leaders on this cruise discuss their results. -from Journal Editor

Average Potential Temperature of the Upper Mantle and Excess Temperatures Beneath Regions of Active Upwelling

Science.gov (United States)

Putirka, K. D.

2006-05-01

The question as to whether any particular oceanic island is the result of a thermal mantle plume, is a question of whether volcanism is the result of passive upwelling, as at mid-ocean ridges, or active upwelling, driven by thermally buoyant material. When upwelling is passive, mantle temperatures reflect average or ambient upper mantle values. In contrast, sites of thermally driven active upwellings will have elevated (or excess) mantle temperatures, driven by some source of excess heat. Skeptics of the plume hypothesis suggest that the maximum temperatures at ocean islands are similar to maximum temperatures at mid-ocean ridges (Anderson, 2000; Green et al., 2001). Olivine-liquid thermometry, when applied to Hawaii, Iceland, and global MORB, belie this hypothesis. Olivine-liquid equilibria provide the most accurate means of estimating mantle temperatures, which are highly sensitive to the forsterite (Fo) contents of olivines, and the FeO content of coexisting liquids. Their application shows that mantle temperatures in the MORB source region are less than temperatures at both Hawaii and Iceland. The Siqueiros Transform may provide the most precise estimate of TpMORB because high MgO glass compositions there have been affected only by olivine fractionation, so primitive FeOliq is known; olivine thermometry yields TpSiqueiros = 1430 ±59°C. A global database of 22,000 MORB show that most MORB have slightly higher FeOliq than at Siqueiros, which translates to higher calculated mantle potential temperatures. If the values for Fomax (= 91.5) and KD (Fe-Mg)ol-liq (= 0.29) at Siqueiros apply globally, then upper mantle Tp is closer to 1485 ± 59°C. Averaging this global estimate with that recovered at Siqueiros yields TpMORB = 1458 ± 78°C, which is used to calculate plume excess temperatures, Te. The estimate for TpMORB defines the convective mantle geotherm, and is consistent with estimates from sea floor bathymetry and heat flow (Stein and Stein, 1992), and

Changes in optical characteristics of surface microlayers in the Peruvian upwelling region hint to photochemically and microbially-mediated DOM turnover

Science.gov (United States)

Engel, A.; Galgani, L.

2016-02-01

The coastal upwelling system off Peru is characterized by high biological activity and associated subsurface oxygen minimum zone, leading to an enhanced emission of atmospheric trace gases. High biological productivity in the water column may promote the establishment of enriched organic surface films, key environments for processes regulating gas fluxes across the water-air interface. During M91 cruise to the Peruvian upwelling, we focused our attention on the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples in 38 stations determining DOC concentrations, amino acids composition, marine gels, CDOM and bacterial abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slopes (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources. Profound changes in spectral slope properties were observed suggesting smaller MW CDOM in the SML compared to underlying water. Microbial and photochemical degradation are likely the main drivers for organic matter cycling in the top layer of the ocean. Consequences on the formation of inorganic and organic species highly relevant for air-sea gas exchange and for climate dynamics will be discussed.

Pathways of upwelling deep waters to the surface of the Southern Ocean

Science.gov (United States)

Tamsitt, Veronica; Drake, Henri; Morrison, Adele; Talley, Lynne; Dufour, Carolina; Gray, Alison; Griffies, Stephen; Mazloff, Matthew; Sarmiento, Jorge; Wang, Jinbo; Weijer, Wilbert

2017-04-01

Upwelling of Atlantic, Indian and Pacific deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of anthropogenic carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. Here we go beyond the two-dimensional view of Southern Ocean upwelling, to show detailed Southern Ocean upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution ocean and climate models. The northern deep waters enter the Antarctic Circumpolar Current (ACC) via narrow southward currents along the boundaries of the three ocean basins, before spiraling southeastward and upward through the ACC. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the southern ACC boundary, with a spatially nonuniform distribution, regionalizing warm water supply to Antarctic ice shelves and the delivery of nutrient and carbon-rich water to the sea surface. The timescale for half of the deep water to upwell from 30°S to the mixed layer is on the order of 60-90 years, which has important implications for the timescale for signals to propagate through the deep ocean. In addition, we quantify the diabatic transformation along particle trajectories, to identify where diabatic processes are important along the upwelling pathways.

The physical structure of a cold filament in a Chilean upwelling zone (Península de Mejillones, Chile, 23°S)

Science.gov (United States)

Sobarzo, Marcus; Figueroa, Dante

2001-12-01

Cold filaments associated with Eastern Boundary Currents are typically narrower than 100 km but can be several hundred kilometers long, extending from the coast to the open ocean in upwelling areas. One such structure, observed off Península de Mejillones (23°S, Chile), was studied with both satellite images and two 5-days hydrographic cruises carried out during January 1997. The study used a coastal grid of 31 stations in an area of 165 ×155 km 2, approximately. The spatial distribution of the filament and its change between cruises are described from the horizontal distributions of dynamic height, temperature, salinity and dissolved oxygen. The filament was a shallow feature (thickness zone show the ascent of the shallow salinity minimum (SSM), and its extension toward the ocean, bound to the filament. It is concluded that Subantarctic Water ((SAAW) distinguish by low salinity, high dissolved oxygen) and Equatorial Subsurface Water ((ESSW) high salinity, low dissolved oxygen, high nutrient content) form this filament, and that their relative proportions depend on the strength of the coastal upwelling. Thus, the knowledge of the dynamics of these structures is fundamental to better understanding of the spatial distribution of important biological variables, such as nutrients and chlorophyll, in the coastal ecosystem.

Developments in Coastal Ocean Modeling

Science.gov (United States)

Allen, J. S.

2001-12-01

Capabilities in modeling continental shelf flow fields have improved markedly in the last several years. Progress is being made toward the long term scientific goal of utilizing numerical circulation models to interpolate, or extrapolate, necessarily limited field measurements to provide additional full-field information describing the behavior of, and providing dynamical rationalizations for, complex observed coastal flow. The improvement in modeling capabilities has been due to several factors including an increase in computer power and, importantly, an increase in experience of modelers in formulating relevant numerical experiments and in analyzing model results. We demonstrate present modeling capabilities and limitations by discussion of results from recent studies of shelf circulation off Oregon and northern California (joint work with Newberger, Gan, Oke, Pullen, and Wijesekera). Strong interactions between wind-forced coastal currents and continental shelf topography characterize the flow regimes in these cases. Favorable comparisons of model and measured alongshore currents and other variables provide confidence in the model-produced fields. The dependence of the mesoscale circulation, including upwelling and downwelling fronts and flow instabilities, on the submodel used to parameterize the effects of small scale turbulence, is discussed. Analyses of model results to provide explanations for the observed, but previously unexplained, alongshore variability in the intensity of coastal upwelling, which typically results in colder surface water south of capes, and the observed development in some locations of northward currents near the coast in response to the relaxation of southward winds, are presented.

Summertime sea surface temperature fronts associated with upwelling around the Taiwan Bank

Science.gov (United States)

Lan, Kuo-Wei; Kawamura, Hiroshi; Lee, Ming-An; Chang, Yi; Chan, Jui-Wen; Liao, Cheng-Hsin

2009-04-01

It is well known that upwelling of subsurface water is dominant around the Taiwan Bank (TB) and the Penghu (PH) Islands in the southern Taiwan Strait in summertime. Sea surface temperature (SST) frontal features and related phenomena around the TB upwelling and the PH upwelling were investigated using long-term AVHRR (1996-2005) and SeaWiFS (1998-2005) data received at the station of National Taiwan Ocean University. SST and chlorophyll-a (Chl-a) images with a spatial resolution of 0.01° were generated and used for the monthly SST and Chl-a maps. SST fronts were extracted from each SST images and gradient magnitudes (GMs); the orientations were derived for the SST fronts. Monthly maps of cold fronts where the cooler SSTs were over a shallower bottom were produced from the orientation. Areas with high GMs (0.1-0.2 °C/km) with characteristic shapes appeared at geographically fixed positions around the TB/PH upwelling region where SSTs were lower than the surrounding waters. The well-shaped high GMs corresponded to cold fronts. Two areas with high Chl-a were found around the TB and PH Islands. The southern border of the high-Chl-a area in the TB upwelling area was outlined by the high-GM area. Shipboard measurements of snapshot vertical sections of temperature (T) and salinity (S) along the PH Channel showed a dome structure east of PH Islands, over which low SST and high GM in the maps of the corresponding month were present. Clear evidence of upwelling (vertically uniform distributions of T and S) was indicated at the TB edge in the T and S sections close to TB upwelling. This case of upwelling may be caused by bottom currents ascending the TB slope as pointed out by previous studies. The position of low SSTs in the monthly maps matched the upwelling area, and the high GMs corresponded to the area of eastern surface fronts in the T/S sections.

Estimating total alkalinity for coastal ocean acidification monitoring at regional to continental scales in Australian coastal waters

KAUST Repository

Baldry, Kimberlee; Hardman-Mountford, Nick; Greenwood, Jim

2017-01-01

Owing to a lack of resources, tools, and knowledge, the natural variability and distribution of Total Alkalinity (TA) has been poorly characterised in coastal waters globally, yet variability is known to be high in coastal regions due to the complex interactions of oceanographic, biotic, and terrestrially-influenced processes. This is a particularly challenging task for the vast Australian coastline, however, it is also this vastness that demands attention in the face of ocean acidification (OA). Australian coastal waters have high biodiversity and endemism, and are home to large areas of coral reef, including the Great Barrier Reef, the largest coral reef system in the world. Ocean acidification threatens calcifying marine organisms by hindering calcification rates, threatening the structural integrity of coral reefs and other ecosystems. Tracking the progression of OA in different coastal regions requires accurate knowledge of the variability in TA. Thus, estimation methods that can capture this variability at synoptic scales are needed. Multiple linear regression is a promising approach in this regard. Here, we compare a range of both simple and multiple linear regression models to the estimation of coastal TA from a range of variables, including salinity, temperature, chlorophyll-a concentration and nitrate concentration. We find that regionally parameterised models capture local variability better than more general coastal or open ocean parameterised models. The strongest contribution to model improvement came through incorporating temperature as an input variable as well as salinity. Further improvements were achieved through the incorporation of either nitrate or chlorophyll-a, with the combination of temperature, salinity, and nitrate constituting the minimum model in most cases. These results provide an approach that can be applied to satellite Earth observation and autonomous in situ platforms to improve synoptic scale estimation of TA in coastal waters.

Estimating total alkalinity for coastal ocean acidification monitoring at regional to continental scales in Australian coastal waters

KAUST Repository

Baldry, Kimberlee

2017-06-01

Owing to a lack of resources, tools, and knowledge, the natural variability and distribution of Total Alkalinity (TA) has been poorly characterised in coastal waters globally, yet variability is known to be high in coastal regions due to the complex interactions of oceanographic, biotic, and terrestrially-influenced processes. This is a particularly challenging task for the vast Australian coastline, however, it is also this vastness that demands attention in the face of ocean acidification (OA). Australian coastal waters have high biodiversity and endemism, and are home to large areas of coral reef, including the Great Barrier Reef, the largest coral reef system in the world. Ocean acidification threatens calcifying marine organisms by hindering calcification rates, threatening the structural integrity of coral reefs and other ecosystems. Tracking the progression of OA in different coastal regions requires accurate knowledge of the variability in TA. Thus, estimation methods that can capture this variability at synoptic scales are needed. Multiple linear regression is a promising approach in this regard. Here, we compare a range of both simple and multiple linear regression models to the estimation of coastal TA from a range of variables, including salinity, temperature, chlorophyll-a concentration and nitrate concentration. We find that regionally parameterised models capture local variability better than more general coastal or open ocean parameterised models. The strongest contribution to model improvement came through incorporating temperature as an input variable as well as salinity. Further improvements were achieved through the incorporation of either nitrate or chlorophyll-a, with the combination of temperature, salinity, and nitrate constituting the minimum model in most cases. These results provide an approach that can be applied to satellite Earth observation and autonomous in situ platforms to improve synoptic scale estimation of TA in coastal waters.

NOAA's Coastal Change Analysis Program (C-CAP) 1996 to 2010 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2006 to 2016 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2001 to 2016 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1985 to 2006 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1996 to 2001 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1992 to 2006 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2001 to 2006 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2006 to 2010 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1992 to 2001 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1975 to 2010 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1996 to 2016 Regional Land Cover Change Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

Wind-driven upwelling effects on cephalopod paralarvae: Octopus vulgaris and Loliginidae off the Galician coast (NE Atlantic)

Science.gov (United States)

Otero, Jaime; Álvarez-Salgado, X. Antón; González, Ángel F.; Souto, Carlos; Gilcoto, Miguel; Guerra, Ángel

2016-02-01

Circulation patterns of coastal upwelling areas may have central consequences for the abundance and cross-shelf transport of the larval stages of many species. Previous studies have provided evidences that larvae distribution results from a combination of subtidal circulation, species-specific behaviour and larval sources. However, most of these works were conducted on organisms characterised by small-sized and abundant early life phases. Here, we studied the influence of the hydrography and circulation of the Ría de Vigo and adjacent shelf (NW Iberian upwelling system) on the paralarval abundance of two contrasting cephalopods, the benthic common octopus (Octopus vulgaris) and the pelagic squids (Loliginidae). We sampled repeatedly a cross-shore transect during the years 2003-2005 and used zero inflated models to accommodate the scarcity and patchy distribution of cephalopod paralarvae. The probability of catching early stages of both cephalopods was higher at night. Octopus paralarvae were more abundant in the surface layer at night whereas loliginids preferred the bottom layer regardless of the sampling time. Abundance of both cephalopods increased when shelf currents flowed polewards, water temperature was high and water column stability was low. The probability of observing an excess of zero catches decreased during the year for octopus and at high current speed for loliginids. In addition, the circulation pattern conditioned the body size distribution of both paralarvae; while the average size of the captured octopuses increased (decreased) with poleward currents at daylight (nighttime), squids were smaller with poleward currents regardless of the sampling time. These results contribute to the understanding of the effects that the hydrography and subtidal circulation of a coastal upwelling have on the fate of cephalopod early life stages.

Stable nitrogen isotopes in coastal macroalgae: Geographic and anthropogenic variability

International Nuclear Information System (INIS)

Viana, Inés G.; Bode, Antonio

2013-01-01

Growing human population adds to the natural nitrogen loads to coastal waters. Both anthropogenic and natural nitrogen is readily incorporated in new biomass, and these different nitrogen sources may be traced by the measurement of the ratio of stable nitrogen isotopes (δ 15 N). In this study δ 15 N was determined in two species of macroalgae (Ascophyllum nodosum and Fucus vesiculosus), and in nitrate and ammonium to determine the relative importance of anthropogenic versus natural sources of nitrogen along the coast of NW Spain. Both algal species and nitrogen sources showed similar isotopic enrichment for a given site, but algal δ 15 N was not related to either inorganic nitrogen concentrations or δ 15 N in the water samples. The latter suggests that inorganic nitrogen inputs are variable and do not always leave an isotopic trace in macroalgae. However, a significant linear decrease in macroalgal δ 15 N along the coast is consistent with the differential effect of upwelling. Besides this geographic variability, the influence of anthropogenic nitrogen sources is evidenced by higher δ 15 N in macroalgae from rias and estuaries compared to those from open coastal areas and in areas with more than 15 × 10 3 inhabitants in the watershed. These results indicate that, in contrast with other studies, macroalgal δ 15 N is not simply related to either inorganic nitrogen concentrations or human population size but depends on other factors as the upwelling or the efficiency of local waste treatment systems. - Highlights: ► Anthropogenic versus upwelling nitrogen effect on macroalgal δ 15 N was studied. ► The influence of populations and upwelling has not been made before on macroalgal δ 15 N. ► Natural variability has not been taken into account in most biomonitoring studies. ► Upwelling explains most of the variability in δ 15 N in macroalgae

Spatio-Temporal Variation in Effects of Upwelling on the Fatty Acid Composition of Benthic Filter Feeders in the Southern Benguela Ecosystem: Not All Upwelling Is Equal.

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Eleonora Puccinelli

Full Text Available Variability in mesoscale nearshore oceanographic conditions plays an important role in the distribution of primary production and food availability for intertidal consumers. Advection of nutrient rich waters by upwelling usually allows the proliferation of diatoms, later replaced by dinoflagellates. We examined upwelling effects on the fatty acid (FA signature of a benthic intertidal filter feeder to identify its response to pulsed variability in food availability. The study took place in two contrasting seasons and at two upwelling and two non-upwelling sites interspersed within the southern Benguela upwelling system of South Africa. We investigated the FA composition of the adductor muscles and gonads of the mussel Mytilus galloprovincialis to assess how FA are apportioned to the different tissues and whether this changes between upwelling and non-upwelling conditions. In situ temperature loggers used to identify upwelling conditions at the four sites indicated that such events occurred only at the upwelling centres and only in summer. Tissues differed strongly, with gonads presenting a higher proportion of essential FAs. This could reflect the faster turnover rate of gonad tissue or preferential retention of specific FA for reproductive purposes. FA composition did not vary as a direct function of upwelling, but there were strong dissimilarities among sites. Upwelling influenced mussel diets at one upwelling site while at the other, the expected signature of upwelling was displaced downstream of the core of upwelling. Condition Index (CI and Gonad Index (GI differed among sites and were not influenced by upwelling, with GI being comparable among sites. In addition, FA proportions were consistent among sites, indicating similar food quality and quantity over time and under upwelling and non-upwelling conditions. This suggests that the influence of upwelling on the west coast of South Africa is pervasive and diffuse, rather than discrete; while

Statistical downscaling of sea-surface wind over the Peru-Chile upwelling region: diagnosing the impact of climate change from the IPSL-CM4 model

Energy Technology Data Exchange (ETDEWEB)

Goubanova, K. [CNES/CNRS/IRD/UPS, Laboratoire d' Etudes en Geophysique et Oceanographie Spatiale, Toulouse (France); Instituto del Mar del Peru, Callao (Peru); Echevin, V.; Terray, P. [IPSL/UPMC/IRD, Laboratoire d' Oceanographie et de Climatologie, Experimentation et Approches Numeriques, Paris (France); Dewitte, B. [CNES/CNRS/IRD/UPS, Laboratoire d' Etudes en Geophysique et Oceanographie Spatiale, Toulouse (France); Instituto del Mar del Peru, Callao (Peru); Instituto Geofisico del Peru, Lima (Peru); Codron, F. [UPMC/CNRS, Laboratoire de Meteorologie Dynamique, Paris (France); Takahashi, K. [Instituto Geofisico del Peru, Lima (Peru); Vrac, M. [IPSL/CNRS/CEA/UVSQ, Laboratoire des Sciences du Climat et de l' Environnement, Gif-sur-Yvette (France)

2011-04-15

The key aspect of the ocean circulation off Peru-Chile is the wind-driven upwelling of deep, cold, nutrient-rich waters that promote a rich marine ecosystem. It has been suggested that global warming may be associated with an intensification of upwelling-favorable winds. However, the lack of high-resolution long-term observations has been a limitation for a quantitative analysis of this process. In this study, we use a statistical downscaling method to assess the regional impact of climate change on the sea-surface wind over the Peru-Chile upwelling region as simulated by the global coupled general circulation model IPSL-CM4. Taking advantage of the high-resolution QuikSCAT wind product and of the NCEP reanalysis data, a statistical model based on multiple linear regressions is built for the daily mean meridional and zonal wind at 10 m for the period 2000-2008. The large-scale 10 m wind components and sea level pressure are used as regional circulation predictors. The skill of the downscaling method is assessed by comparing with the surface wind derived from the ERS satellite measurements, with in situ wind observations collected by ICOADS and through cross-validation. It is then applied to the outputs of the IPSL-CM4 model over stabilized periods of the pre-industrial, 2 x CO{sub 2} and 4 x CO{sub 2} IPCC climate scenarios. The results indicate that surface along-shore winds off central Chile (off central Peru) experience a significant intensification (weakening) during Austral winter (summer) in warmer climates. This is associated with a general decrease in intra-seasonal variability. (orig.)

Saint Petersburg as a Global Coastal City: Positioning in the Baltic Region

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Lachininskii Stanislav

2015-09-01

Full Text Available The Baltic region consists of coastal areas of nine countries — Russia, Estonia, Latvia, Lithuania, Poland, Germany, Denmark, Sweden, and Finland. The region’s hubs are the port cities located along the Baltic Sea coast. However, Peter Taylor and Saskia Sassen’s classification identifies higher status cities and ‘global cities’, which are to be considered in the global context. Seven coastal regions are distinguished within this region, whose organising centers are the global coastal cities of Stockholm, Copenhagen, Helsinki, Riga, Tallinn, St. Petersburg, and Malmö. The concept of a “global city-region” (Sassen can be used as a methodological framework for analyzing this connection. Within this hierarchy, the dominant alpha group global city is Stockholm. The authors argue that, as a global coastal city, St. Petersburg forms the St. Petersburg coastal region, which can be defined as a typical "global city region". The index method shows that the position of St. Petersburg in the system of global coastal cities of the Baltic region is relatively favorable in view of its transport, logistics, and demographic potential and the advantageous geo-economic situation. St. Petersburg has certain competitive advantages in the region brought about by its demographic potential, port freight capacity, and the favorable geo-economic position of the "sea gate" of Russia. However, the level of high-tech services and ‘new economy’ development is not sufficient for the port to become a match for the top three cities (Stockholm, Helsinki, and Copenhagen. This is increasingly important because transboundary global city networks demonstrate that global cities are functions of global networks. Saint Petersburg is just starting to integrate into these networks through the Pulkovo airline hub and seaports of Ust-Luga, Primorsk, and Saint Petersburg.

Saint Petersburg as a Global Coastal City: Positioning in the Baltic Region

Directory of Open Access Journals (Sweden)

Lachninsky S.

2015-08-01

Full Text Available The Baltic region consists of coastal areas of nine countries — Russia, Estonia, Latvia, Lithuania, Poland, Germany, Denmark, Sweden, and Finland. The region’s hubs are the port cities located along the Baltic Sea coast. However, Peter Taylor and Saskia Sassen’s classification identifies higher status cities and ‘global cities’, which are to be considered in the global context. Seven coastal regions are distinguished within this region, whose organising centers are the global coastal cities of Stockholm, Copenhagen, Helsinki, Riga, Tallinn, St. Petersburg, and Malmö. The concept of a “global city-region” (Sassen can be used as a methodological framework for analyzing this connection. Within this hierarchy, the dominant alpha group global city is Stockholm. The authors argue that, as a global coastal city, St. Petersburg forms the St. Petersburg coastal region, which can be defined as a typical "global city region". The index method shows that the position of St. Petersburg in the system of global coastal cities of the Baltic region is relatively favorable in view of its transport, logistics, and demographic potential and the advantageous geo-economic situation. St. Petersburg has certain competitive advantages in the region brought about by its demographic potential, port freight capacity, and the favorable geo-economic position of the "sea gate" of Russia. However, the level of high-tech services and ‘new economy’ development is not sufficient for the port to become a match for the top three cities (Stockholm, Helsinki, and Copenhagen. This is increasingly important because transboundary global city networks demonstrate that global cities are functions of global networks. Saint Petersburg is just starting to integrate into these networks through the Pulkovo airline hub and seaports of Ust-Luga, Primorsk, and Saint Petersburg.

Ocean circulation off the north-west coast of the United States is ...

African Journals Online (AJOL)

spamer

The coastal upwelling region near Cape Blanco (43°N), Oregon, off the west coast of the ... other eastern boundary current regions of the world. ..... behaviour in August, when the upwelling circulation ... This work was funded by the United.

Development of Phaeocystis globosa blooms in the upwelling waters of the South Central coast of Viet Nam

Science.gov (United States)

Hai, Doan-Nhu; Lam, Nguyen-Ngoc; Dippner, Joachim W.

2010-11-01

Blooms of haptophyte algae in the south central coastal waters of Viet Nam often occur in association with upwelling phenomenon during the southwest (SW) monsoon. Depending on the magnitude of the blooms, damage to aquaculture farms may occur. Based on two years of data on biology, oceanography, and marine chemistry, the present study suggests a conceptual model of the growth of the haptophyte Phaeocystis globosa. At the beginning of the bloom, low temperature and abundant nutrient supply, especially nitrate from rain and upwelling, favour bloom development. Diatoms utilize available nitrate and phosphate; subsequently, higher ammonium concentration allows P. globosa to grow faster than the diatoms. At the end of the Phaeocystis bloom, free cells may become available as food for a heterotrophic dinoflagellate species, Noctiluca scintillans. During and after the phytoplankton bloom, remineralization by bacteria reduces dissolved oxygen to a very low concentration at depth, and favors growth of nitrate-reducing bacteria.A Lagrangian Harmful Algal Bloom (HAB) model, driven by a circulation model of the area, realistically simulates the transport of microalgae in surface waters during strong and weak SW monsoon periods, suggesting that it may be a good tool for early warning of HABs in Vietnamese coastal waters.

Estimates of upwelling rates in the Arabian Sea and the equatorial Indian Ocean based on bomb radiocarbon.

Science.gov (United States)

Bhushan, R; Dutta, K; Somayajulu, B L K

2008-10-01

Radiocarbon measurements were made in the water column of the Arabian Sea and the equatorial Indian Ocean during 1994, 1995 and 1997 to assess the temporal variations in bomb 14C distribution and its inventory in the region with respect to GEOSECS measurements made during 1977-1978. Four GEOSECS stations were reoccupied (three in the Arabian Sea and one in the equatorial Indian Ocean) during this study, with all of them showing increased penetration of bomb 14C along with decrease in its surface water activity. The upwelling rates derived by model simulation of bomb 14C depth profile using the calculated exchange rates ranged from 3 to 9 m a(-1). The western region of the Arabian Sea experiencing high wind-induced upwelling has higher estimated upwelling rates. However, lower upwelling rates obtained for the stations occupied during this study could be due to reduced 14C gradient compared to that during GEOSECS.

Spawning of the chilean hake (Merluccius gayi in the upwelling system off Talcahuano in relation to oceanographic features

Directory of Open Access Journals (Sweden)

Cristian A. Vargas

2001-06-01

Full Text Available Previous studies have shown that the upwelling area off Talcahuano, in central-south Chile, is an important spawning zone for the hake Merluccius gayi. We document the results of a study designed to assess the importance of oceanographic features on the horizontal and vertical distribution of hake eggs and larvae. Ichthyoplankton samples and oceanographic data (CTDO casts, and wind speed and direction were collected during a cruise carried out off Talcahuano (36º22´S-37º10´S in early spring (October 1996, which included a grid of 61 stations up to 60 nm offshore. The oceanographic information obtained revealed the presence of an upwelling plume at Lavapie Point (southern zone extending northward over the shelf, and the presence of a warmer water parcel close to shore in the northern area. Peak egg densities occurred in this northern area over the shelf, in a nucleus located at the shoreward moving deeper layer (40-100 m deep and associated with the upwelling front about 20-30 nm from shore. The highest larval abundance also occurred in the northern area over the shelf and in the deeper layer but closer to shore than the egg nucleus. Because the timing (early spring and location of spawning (at depth, over the shelf and in association with frontal structures are also shared by other hake species in upwelling areas, we propose that they may be part of a more commonly developed strategy to enhance offspring survival in coastal upwelling areas of eastern boundary currents.

Physical and chemical aspects of transient stages of the upwelling at southwest of Cabo Frio (Lat. 23ºS - Long, 42ºW

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Argeo Magliocca

1979-01-01

Full Text Available An upwelling event was observed during February 1971 in the coastal region between Cabo Frio and Saquarema Point. Isolated upwelled water observed on a first survey, with a temperature of 17ºC, oxygen concentration of 4.2 ml/liter and inorganic phosphate concentration of 0.6 µg-at/liter, cleanly indicating its subsurface origin, was replaced, after a period of four to seven days, by coastal water with a temperature of 22ºC, oxygen concentration of 5.0 ml/liter and inorganic phosphate concentration of less than 0.3 µg-at,/liter. The evidence indicates that this replacement took place due to an eastward coastal current with a maximum velocity of nearly 5.0 nautical miles per day. The subsurface distribution of the chemical and physical properties indicates that the upwelling occurred mostly in the narrowest portion of the continental shelf.As observações oceanográficas realizadas em fevereiro de 1971, na plataforma continental entre Cabo Frio e a Ponta de Guaratiba, mostraram a presença e a atenuação de efeitos do fenomeno de ressurgência observados na superfície. A análise detalhada da distribuição térmica na camada superficial evidencia que o processo físico responsável pela atenuação desse fenomeno foi a advecção de uma corrente costeira de aguas quentes, fluindo para leste. A componente zonal dessa corrente costeira atingiu nas proximidades da costa o valor máximo de 5 mn. dia 1 e a sua intensidade decresceu com o aumento da distancia á costa, anulando-se aproximadamente sobre a isobata de 100 m. Os efeitos do fenomeno de ressurgência na superficíe, observados ao largo da Ponta de Saquarema, eram claramente indicados pelos mínimos de temperatura (17ºC e da concentração de oxigênio dissolvido (4,2 ml/l bem como pelo máximo na concentração de fosfato (0,6 µg-at/l, que sao característicos de aguas mais profundas. No intervalo de tempo (4-7 dias decorrido entre as observações, verificou-se não somente

Savannah River Region: Transition between the Gulf and Atlantic Coastal Plains. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Zullo, V.A.; Harris, W.B.; Price, V. [eds.

1990-12-31

The focus of the this conference of Coastal Plains geologists was on the Savannah River region of Georgia and South Carolina, and particularly on the geology of the US Department of Energy`s 300 square mile Savannah River Site (SRS) in western South Carolina. Current geological studies indicate that the Mesozoic-Cenozoic section in the Savannah River region is transitional between that of the Gulf Coastal Plain to the southwest and that of the Atlantic Coastal Plain to the northeast. With the transitional aspect of the region as its theme, the first session was devoted to overviews of Cretaceous and Paleogene geology in the Gulf and Atlantic Coastal Plains. Succeeding presentations and resulting discussions dealt with more specific problems in structural, lithostratigraphic, hydrological, biostratigraphic, and cyclostratigraphic analysis, and of correlation to standard stratigraphic frameworks. For these conference proceedings, individual papers have been processed separately for the Energy Data Base.

The circulation dynamics associated with a northern Benguela upwelling filament during October 2010

Science.gov (United States)

Muller, Annethea A.; Mohrholz, Volker; Schmidt, Martin

2013-07-01

Upwelling filaments, a common feature in all the major upwelling systems, are also regularly observed in the Benguela upwelling system and are thought to provide an effective mechanism for the exchange of matter between the shelf and the open ocean. The mesoscale dynamics of a northern Benguela upwelling filament located at approximately 18.5°S were examined and the associated transport was quantified. The development of the filament was tracked using optimal interpolated SST satellite data and two transects were consequently sampled across the feature using a towed undulating CTD (ScanFish). Additional hydrographic, nutrient and biological parameters were investigated at several stations along each transect. Following 7 days of strong upwelling favorable winds, sampling coincided with a period of relative wind relaxation and the filament was presumably in a decaying state. The basic mesoscale structure of the investigated filament corresponded well to what had previously been described for filaments from other eastern boundary current systems. The cross-shore transport associated with the filament was found to be significantly greater than the integrated Ekman transport in the region. With the combination of the high resolution dataset and a MOM-4 ecosystem model the complex mesoscale flow field associated with the feature could be observed and the counterbalancing onshore transport, associated with subsurface dipole eddies, was revealed within the filament. The results further suggest that an interaction between the offshore bending of flow at the Angola-Benguela Front (ABF), the detachment of the strong poleward flow from the coast as the thermal front meanders and the observed dipole eddies may be driving filament occurrence in the region off Cape Frio.

Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upwelling region

International Nuclear Information System (INIS)

Blasco, D.; MacIsaac, J.J.; Packard, T.T.; Dugdale, R.C.

1984-01-01

Nitrate reductase (NR) activity and 15 NO 3 - uptake in phytoplankton were compared under different environmental conditions on two cruises in the upwelling region off Peru. The NR activity and NO 3 - uptake rates responded differently to light and nutrients and the differences led to variations in the uptake: reductase ratio. Analysis of these variations suggests that the re-equilibration time of the two processes in response to environmental perturbation is an important source of variability. The nitrate uptake system responds faster than the nitrate reductase system. Considering these differences in response time the basic differences in the two processes, and the differences in their measurement, the authors conclude that the Nr activity measures the current nitrate-reducing potential, which reflects NO 3 - assimilation before the sampling time, while 15 NO 3 - uptake measures NO 3 - assimilation in the 6-h period following sampling

Iberian and California-Oregon Upwelling Systems: trends and status of two upwelling systems at the same latitude over the last four decades.

Science.gov (United States)

Barreiro, B.; Barton, E. D.

2012-04-01

The study of Eastern Boundary Upwelling Systems is of vital importance, given the interest in rational management of the fisheries resources. The high level of biogeochemical activity associated with the physical process of upwelling increases primary production and enriches the living resources of these areas. This presentation focuses on the variability of these physical processes on daily to interdecadal scales, in an investigation of the effects of climate change in the Iberian and California-Oregon Upwelling Systems. The Upwelling Index (UI) was analysed for the period 1967-2010 at 35.5-44.5°N in both areas. The two systems differ in that the magnitudes of upwelling intensity off California-Oregon are 3.3 higher than off Iberia but they show a similar latitudinal behaviour. The annual/interannual scale variability of upwelling can be represented by the recently introduced Cumulative Upwelling Index (CUI) based on summing the mean daily UI. The seasonal cycle results show the length of upwelling season increases southwards from 180 to 300 days and a net upwelling occurs only for latitudes lower than 43°N. On the interannual scales, the CUI showed a roughly linear change at high and low latitudes (R>0.9), with slopes between 250 and -130 m3 s-1 km-1 day-1 in Iberian and 620 and -290 m3 s-1 km-1 day-1 in California-Oregon. The central areas (40.5-42.5°N) are less stable and shifted between net upwelling and downwelling over extended periods. This information helps us contextualize the present state of the study area and interpreted ongoing intensive process-oriented studies within the longer term variability.

77 FR 35357 - Atlantic Highly Migratory Species; Commercial Atlantic Region Non-Sandbar Large Coastal Shark...

Science.gov (United States)

2012-06-13

... Highly Migratory Species; Commercial Atlantic Region Non-Sandbar Large Coastal Shark Fishery Opening Date... commercial Atlantic region non-sandbar large coastal shark fishery. This action is necessary to inform... large coastal shark fishery will open on July 15, 2012. FOR FURTHER INFORMATION CONTACT: Karyl Brewster...

Changes in optical characteristics of surface microlayers hint to photochemically and microbially-mediated DOM turnover in the upwelling region off Peru

Science.gov (United States)

Galgani, L.; Engel, A.

2015-12-01

The coastal upwelling system off Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. During the Meteor (M91) cruise to the Peruvian upwelling system in 2012, we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples at 38 stations determining DOC concentration, amino acid composition, marine gels, CDOM and bacterial and phytoplankton abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. We identified five fluorescent components of the CDOM pool, of which two had excitation/emission characteristics of protein-like fluorophores and were highly enriched in the SML. CDOM composition and changes in spectral slope properties suggested a local microbial release of HMW DOM directly in the SML as a response to light exposure in this extreme environment. Our results suggest that microbial and photochemical processes play an important role for the production, alteration and loss of optically active substances in the SML.

Causes and consequences of ecosystem service regionalization in a coastal suburban watershed

Science.gov (United States)

Wollheim, Wilfred M.; Mark B. Green,; Pellerin, Brian A.; Morse, Nathaniel B.; Hopkinson, Charles S.

2015-01-01

The demand for ecosystem services and the ability of natural ecosystems to provide those services evolve over time as population, land use, and management practices change. Regionalization of ecosystem service activity, or the expansion of the area providing ecosystem services to a population, is a common response in densely populated coastal regions, with important consequences for watershed water and nitrogen (N) fluxes to the coastal zone. We link biophysical and historical information to explore the causes and consequences of change in ecosystem service activity—focusing on water provisioning and N regulation—from 1850 to 2010 in a coastal suburban watershed, the Ipswich River watershed in northeastern Massachusetts, USA. Net interbasin water transfers started in the late 1800s due to regionalization of water supply for use by larger populations living outside the Ipswich watershed boundaries, reaching a peak in the mid-1980s. Over much of the twentieth century, about 20 % of river runoff was diverted from reaching the estuary, with greater proportions during drought years. Ongoing regionalization of water supply has contributed to recent declines in diversions, influenced by socioecological feedbacks resulting from the river drying and fish kills. Similarly, the N budget has been greatly perturbed since the suburban era began in the 1950s due to food and lawn fertilizer imports and human waste release. However, natural ecosystems are able to remove most of this anthropogenic N, mitigating impacts on the coastal zone. We propose a conceptual model whereby the amount and type of ecosystem services provided by coastal watersheds in urban regions expand and contract over time as regional population expands and ecosystem services are regionalized. We hypothesize that suburban watersheds can be hotspots of ecosystem service sources because they retain sufficient ecosystem function to still produce services that meet increasing demand from the local population

Climate warming and estuarine and marine coastal ecosystems

International Nuclear Information System (INIS)

Kennedy, V.S.

1994-01-01

Estuaries are physically controlled, resilient coastal ecosystems harboring environmentally tolerant species in diluted seawater. Marine coastal systems are less stressed physically and contain some environmentally less tolerant species. Both systems are biologically productive and economically significant. Because of their complex structure and function, it is difficult to predict accurately the effects of climate change, but some broad generalizations can be made. If climate warming occurs, it will raise sea-level, heat shallow waters, and modify precipitation, wind, and water circulation patterns. Rapid sea-level rise could cause the loss of salt marshes, mangrove swamps, and coral reefs, thus diminishing the ecological roles of these highly productive systems. Warmer waters could eliminate heat-sensitive species from part of their geographical range while allowing heat-tolerant species to expand their range, depending on their ability to disperse. Most thermally influenced losses of species will probably only be local, but changed distributions may lead to changed community function. It is more difficult to predict the effects of modified precipitation, wind, and water circulation patterns, but changes could affect organisms dependent on such patterns for food production (e.g., in upwelling regions) or for retention in estuaries. Aquacultural and fishery-related enterprises would be affected negatively in some regions and positively in others. 73 refs

Recent crustal movements and seismicity in the western coastal region of peninsular India

Science.gov (United States)

Kailasam, L. N.

1983-09-01

Recent crustal movements, tectonics and seismicity of the western coastal region of peninsular India have been studied in detail in the very recent past. Prominent geomorphic features and large-scale manifestation of Holocene deformation and crustal movements have been noticed and studied over this coastal region from the Gulf of Cambay to the southernmost parts of Kerala, evidence for which is afforded in the form of Recent and sub-Recent raised beaches, sandbars, raised old terraces, pebble beds, etc. The sedimentary formations in this narrow coastal belt include Neogene and Quaternary sediments. The Bouguer gravity map of the western coastal tract shows some prominent gravity features extending into the offshore regions, suggestive of some significant tectonic and structural features. The seismic data in the offshore regions bring out some prominent roughly northwest-southeast as well as east-west faults and shears, in addition to prominent structural "highs" off the Bombay and Ratnagiri coast which have proved oil. The seismicity in this coastal tract as well as the faulted western margin of the western continental shelf in the Arabian Sea is generally of magnitude 3-6.

Regional gradients in surface sediment nitrogen isotopes as a reflection of nutrient cycling and oxygen deficiency in upwelling areas off Peru and Namibia (Invited)

Science.gov (United States)

Schneider, R. R.; Mollier-Vogel, E.; Martinez, P.

2010-12-01

The sedimentary d15N signal is commonly considered as a reflection of the marine nutrient cycling and related biochemical processes in the overlying water masses. In the modern ocean all processes together result in a mean d15N value of about 5 to 6 per mill for dissolved nitrate. Deviations from this value are considered as a product mainly of nitrogen fixation and nitrate supply causing lower values, while nitrate utilization and denitrification, as well as organic matter degradation tend to shift the signal to higher values. As denitrification is only occurring under conditions of strong oxygen limitation in the water column outstandingly high d15N values in sediment records are commonly taken as indirect evidence for strong oxygen minimum conditions in the past. By comparing surface sediment values from coastal upwelling areas off Namibia and Peru, we test whether such an approach is applicable. Only the Peruvian system is characterized by a pronounced oxygen minimum zone (OMZ) that extends across the shelf and slope far into the Eastern Equatorial Pacific. For comparison we present new results for the Peruvian margin between 2°N and 20°S within and below the Peruvian OMZ in combination with a similar data set from the Namibian margin with an OMZ restricted to the inner shelf. The Peruvian sediment data is furthermore compared to d15N of dissolved nitrate in the overlying water column to better understand how regional oceanography effects the water column d15N and thus the sediment surface signal. Productivity and nitrate uptake is maximal at the position of local and perennial upwelling cells in both systems. However, due to continuous nutrient supply into the upwelling systems sedimentary d15N values on the outer shelves and slopes reveal an increase of only about 2 to 3 per mill over the mean ocean value. Only where extreme oxygen deficiency occurs, as off Peru between 10 and 20 S, the sedimentary d15N signal reaches very high values above 10 per mill

Assessment of MODIS-Aqua chlorophyll-a algorithms in coastal and shelf waters of the eastern Arabian Sea

Science.gov (United States)

Tilstone, Gavin H.; Lotliker, Aneesh A.; Miller, Peter I.; Ashraf, P. Muhamed; Kumar, T. Srinivasa; Suresh, T.; Ragavan, B. R.; Menon, Harilal B.

2013-08-01

The use of ocean colour remote sensing to facilitate the monitoring of phytoplankton biomass in coastal waters is hampered by the high variability in absorption and scattering from substances other than phytoplankton. The eastern Arabian Sea coastal shelf is influenced by river run-off, winter convection and monsoon upwelling. Bio-optical parameters were measured along this coast from March 2009 to June 2011, to characterise the optical water type and validate three Chlorophyll-a (Chla) algorithms applied to Moderate Resolution Imaging Spectroradiometer on Aqua (MODIS-Aqua) data against in situ measurements. Ocean Colour 3 band ratio (OC3M), Garver-Siegel-Maritorena Model (GSM) and Generalized Inherent Optical Property (GIOP) Chla algorithms were evaluated. OC3M performed better than GSM and GIOP in all regions and overall, was within 11% of in situ Chla. GSM was within 24% of in situ Chla and GIOP on average was 55% lower. OC3M was less affected by errors in remote sensing reflectance Rrs(λ) and by spectral variations in absorption coefficient (aCDOM(λ)) of coloured dissolved organic material (CDOM) and total suspended matter (TSM) compared to the other algorithms. A nine year Chla time series from 2002 to 2011 was generated to assess regional differences between OC3M and GSM. This showed that in the north eastern shelf, maximum Chla occurred during the winter monsoon from December to February, where GSM consistently gave higher Chla compared to OC3M. In the south eastern shelf, maximum Chla occurred in June to July during the summer monsoon upwelling, and OC3M yielded higher Chla compared to GSM. OC3M currently provides the most accurate Chla estimates for the eastern Arabian Sea coastal waters.

Sources of new nitrogen in the Vietnamese upwelling region of the South China Sea

DEFF Research Database (Denmark)

Bombar, Deniz; Dippner, Joachim W.; Doan, Hai Nhu

2010-01-01

In the South China Sea, the southwest monsoon between June and September induces upwelling off the southern central Vietnamese coast. During field campaigns in July 2003 and 2004 we evaluated the importance of nitrate and nitrogen fixation as sources of new nitrogen for phytoplankton primary...

Isotopic and enzymatic analyses of planktonic nitrogen utilisation in the vicinity of Cape Sines (Portugal) during weak upwelling activity

Science.gov (United States)

Slawyk, Gerd; Coste, Bernard; Collos, Yves; Rodier, Martine

1997-01-01

Using measurements of 15N uptake and activities of nitrate reductase and glutamine synthetase, the utilization of nitrogenous nutrients by microplankton in the Portuguese upwelling area was investigated. During this cruise the euphotic zone of coastal waters was in most cases bisected by a nitracline forming two layers. Total inorganic nitrogen uptake rates (NH 4+ + NO 3-) in the upper mixed and nitrate-impoverished layer ranged from 0.1 to 0.8 nM h -1 and were primarily supported by regenerated (ammonium) nitrogen (62-97%), whereas they varied between 0.9 and 10.4 nM h -1 in the deep nitrate-rich layer and were mainly driven by new (nitrate) nitrogen (52-82%). Depth profiles of Chl a-specific uptake rates for ammonium and nitrate paralleled those of absolute uptake rates, i.e. values of VNH 4+Chl were highest (up to 16.1 nmol μg -1 h -1) in nitrate-poor surface waters while values of VNO 3-Chl were maximum (up to 8.4 nmol μg -1 h -1)within the nitracline. This latter vertical ordering of planktonic nitrogen nutrition was consistent with an aged upwelling situation. However, applying several indices of cell metabolism and nutritional status, such as 15N uptake/enzyme activity, surge uptake internally controlled uptake, and V maxChl/K t ratios, we were able to demonstrate that the phytoplankton assemblages inhabiting the nutrient-impoverished upper layer still bore the signature of physically mediated nitrogen (nitrate) supply generated by active upwelling that had occurred during the week before our visit to the area. This signature was the most evident in samples from the station furthest inshore and faded with distance from shore as a result of the deepening of the nitrate isopleths (weakening of upwelling activity), which showed the same offshore trend. The appearance of nitrate-rich waters at the surface, after a strong pulse of upwelling favourable winds just before the end of the cruise, led to a five-fold increase in average (over the euphotic zone

Stable nitrogen isotopes in coastal macroalgae: Geographic and anthropogenic variability

Energy Technology Data Exchange (ETDEWEB)

Viana, Inés G., E-mail: ines.gonzalez@co.ieo.es; Bode, Antonio

2013-01-15

Growing human population adds to the natural nitrogen loads to coastal waters. Both anthropogenic and natural nitrogen is readily incorporated in new biomass, and these different nitrogen sources may be traced by the measurement of the ratio of stable nitrogen isotopes (δ{sup 15}N). In this study δ{sup 15}N was determined in two species of macroalgae (Ascophyllum nodosum and Fucus vesiculosus), and in nitrate and ammonium to determine the relative importance of anthropogenic versus natural sources of nitrogen along the coast of NW Spain. Both algal species and nitrogen sources showed similar isotopic enrichment for a given site, but algal δ{sup 15}N was not related to either inorganic nitrogen concentrations or δ{sup 15}N in the water samples. The latter suggests that inorganic nitrogen inputs are variable and do not always leave an isotopic trace in macroalgae. However, a significant linear decrease in macroalgal δ{sup 15}N along the coast is consistent with the differential effect of upwelling. Besides this geographic variability, the influence of anthropogenic nitrogen sources is evidenced by higher δ{sup 15}N in macroalgae from rias and estuaries compared to those from open coastal areas and in areas with more than 15 × 10{sup 3} inhabitants in the watershed. These results indicate that, in contrast with other studies, macroalgal δ{sup 15}N is not simply related to either inorganic nitrogen concentrations or human population size but depends on other factors as the upwelling or the efficiency of local waste treatment systems. - Highlights: ► Anthropogenic versus upwelling nitrogen effect on macroalgal δ{sup 15}N was studied. ► The influence of populations and upwelling has not been made before on macroalgal δ{sup 15}N. ► Natural variability has not been taken into account in most biomonitoring studies. ► Upwelling explains most of the variability in δ{sup 15}N in macroalgae.

Diurnal Variability of the inner-shelf circulation in the lee of a cape under upwelling conditions

Science.gov (United States)

Lamas, Luisa; Peliz, Álvaro; Marchesiello, Patrick

2013-04-01

The circulation over the inner-shelf is a key component of shelf dynamics and an important mechanism for cross-shore exchange on most shelves. Yet our understanding of the cross-shore circulation and how it depends on different forcing conditions, bathymetry and stratification remains poor due in part to sparse observations and the difficulty of resolving spatial and temporal scales within the inner-shelf. Most studies of cross-shore transport on the inner-shelf consider only a 2D circulation, due to coastal upwelling or downwelling and assume along-shore uniformity. However, divergence in the along-shore and cross-shore flows may occur with the presence of complex coastline topography or subtle bathymetric features, and can drive substantial horizontal cross-shore exchange, with same order of magnitude as coastal upwelling and downwelling. A recent study using observational data collected near cape Sines, Portugal, showed that not only wind, waves and tides are important forcing mechanisms of the inner-shelf circulation, but also that the along-shore pressure gradient plays a major role on driving cross-shore exchange. A modeling study was conducted in order to study the complexity of the inner-shelf dynamics, in the presence of a cape. A simplified configuration was used in order to isolate the effects of individual processes: wind, heat fluxes, tides and waves. The preliminary results of the effects of these processes on the inner-shelf circulation will be presented.

Changes in optical characteristics of surface microlayers hint to photochemically and microbially mediated DOM turnover in the upwelling region off the coast of Peru

Science.gov (United States)

Galgani, Luisa; Engel, Anja

2016-04-01

The coastal upwelling system off the coast of Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. From 3 to 23 December 2012, R/V Meteor (M91) cruise took place in the Peruvian upwelling system between 4.59 and 15.4° S, and 82.0 to 77.5° W. During M91 we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like chromophoric dissolved organic matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. We analyzed SML and underlying water (ULW) samples at 38 stations focusing on CDOM spectral characteristics as indicator of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and excitation-emission matrix fluorescence (EEMs), which allow us to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. Spectral slope S varied between 0.012 to 0.043 nm-1 and was quite similar between SML and ULW, with no significant differences between the two compartments. Higher S values were observed in the ULW of the southern stations below 15° S. By EEMs, we identified five fluorescent components (F1-5) of the CDOM pool, of which two had excitation/emission characteristics of amino-acid-like fluorophores (F1, F4) and were highly enriched in the SML, with a median ratio SML : ULW of 1.5 for both fluorophores. In the study region, values for CDOM absorption ranged from 0.07 to 1.47 m-1. CDOM was generally highly concentrated in the SML, with a median enrichment with respect to the ULW of 1.2. CDOM composition and changes in spectral slope properties suggested a local

NOAA's Coastal Change Analysis Program (C-CAP) 1985 to 2010 Regional Land Cover Change Data - Coastal United States (NODC Accession 0121254)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

Particle Fluxes and Bulk Geochemical Characterization of the Cabo Frio Upwelling System in Southeastern Brazil: Sediment Trap Experiments between Spring 2010 and Summer 2012

Directory of Open Access Journals (Sweden)

ANA LUIZA S. ALBUQUERQUE

2014-06-01

Full Text Available Physical and biogeochemical processes in continental shelves act synergistically in both transporting and transforming suspended material, and ocean dynamics control the dispersion of particles by the coastal zone and their subsequent mixing and dilution within the shelf area constrained by oceanic boundary currents, followed by their gradual settling in a complex sedimentary scenario. One of these regions is the Cabo Frio Upwelling System located in a significantly productive area of Southeastern Brazil, under the control of the nutrient-poor western boundary Brazil Current but also with a wind-driven coastal upwelling zone, inducing cold-water intrusions of South Atlantic Central Water on the shelf. To understand these synergic interactions among physical and biogeochemical processes in the Cabo Frio shelf, a series of four experiments with a total of 98 discrete samples using sediment traps was performed from November 2010 to March 2012, located on the 145 m isobath on the edge of the continental shelf. The results showed that lateral transport might be relevant in some cases, especially in deep layers, although no clear seasonal cycle was detected. Two main physical-geochemical coupling scenarios were identified: singular downwelling events that can enhance particles fluxes and are potentially related to the Brazil Current oscillations; and events of significant fluxes related to the intrusion of the 18°C isotherm in the euphotic zone. The particulate matter settling in the Cabo Frio shelf area seems to belong to multiple marine and terrestrial sources, in which both Paraiba do Sul River and Guanabara Bay could be potential land-sources, although the particulate material might subject intense transformation (diagenesis during its trajectory to the shelf edge.

Particle Fluxes and Bulk Geochemical Characterization of the Cabo Frio Upwelling System in Southeastern Brazil: Sediment Trap Experiments between Spring 2010 and Summer 2012.

Science.gov (United States)

Albuquerque, Ana Luiza S; Belém, André L; Zuluaga, Francisco J B; Cordeiro, Livia G M; Mendoza, Ursula; Knoppers, Bastiaan A; Gurgel, Marcio H C; Meyers, Philip A; Capilla, Ramsés

2014-05-14

Physical and biogeochemical processes in continental shelves act synergistically in both transporting and transforming suspended material, and ocean dynamics control the dispersion of particles by the coastal zone and their subsequent mixing and dilution within the shelf area constrained by oceanic boundary currents, followed by their gradual settling in a complex sedimentary scenario. One of these regions is the Cabo Frio Upwelling System located in a significantly productive area of Southeastern Brazil, under the control of the nutrient-poor western boundary Brazil Current but also with a wind-driven coastal upwelling zone, inducing cold-water intrusions of South Atlantic Central Water on the shelf. To understand these synergic interactions among physical and biogeochemical processes in the Cabo Frio shelf, a series of four experiments with a total of 98 discrete samples using sediment traps was performed from November 2010 to March 2012, located on the 145 m isobath on the edge of the continental shelf. The results showed that lateral transport might be relevant in some cases, especially in deep layers, although no clear seasonal cycle was detected. Two main physical-geochemical coupling scenarios were identified: singular downwelling events that can enhance particles fluxes and are potentially related to the Brazil Current oscillations; and events of significant fluxes related to the intrusion of the 18°C isotherm in the euphotic zone. The particulate matter settling in the Cabo Frio shelf area seems to belong to multiple marine and terrestrial sources, in which both Paraiba do Sul River and Guanabara Bay could be potential land-sources, although the particulate material might subject intense transformation (diagenesis) during its trajectory to the shelf edge.

An AHP-derived method for mapping the physical vulnerability of coastal areas at regional scales

Directory of Open Access Journals (Sweden)

G. Le Cozannet

2013-05-01

Full Text Available Assessing coastal vulnerability to climate change at regional scales is now mandatory in France since the adoption of recent laws to support adaptation to climate change. However, there is presently no commonly recognised method to assess accurately how sea level rise will modify coastal processes in the coming decades. Therefore, many assessments of the physical component of coastal vulnerability are presently based on a combined use of data (e.g. digital elevation models, historical shoreline and coastal geomorphology datasets, simple models and expert opinion. In this study, we assess the applicability and usefulness of a multi-criteria decision-mapping method (the analytical hierarchy process, AHP to map physical coastal vulnerability to erosion and flooding in a structured way. We apply the method in two regions of France: the coastal zones of Languedoc-Roussillon (north-western Mediterranean, France and the island of La Réunion (south-western Indian Ocean, notably using the regional geological maps. As expected, the results show not only the greater vulnerability of sand spits, estuaries and low-lying areas near to coastal lagoons in both regions, but also that of a thin strip of erodible cliffs exposed to waves in La Réunion. Despite gaps in knowledge and data, the method is found to provide a flexible and transportable framework to represent and aggregate existing knowledge and to support long-term coastal zone planning through the integration of such studies into existing adaptation schemes.

Surface distribution of brachyuran megalopae and ichthyoplankton in the Columbia River plume during transition from downwelling to upwelling conditions

Science.gov (United States)

Roegner, G. Curtis; Daly, Elizabeth A.; Brodeur, Richard D.

2013-06-01

In the California Current coastal boundary zone, the spring transition between downwelling and upwelling conditions, along with the fluctuating structure of the Columbia River plume, creates highly dynamic interactions. In this study, we investigated whether the surface distribution of brachyuran larvae and ichthyoplankton would track the dynamics of the Columbia River plume. By happenstance, the cruise period coincided with the spring transition from downwelling to sustained upwelling conditions in 2010, a year when the transition was delayed and Columbia River flow was substantially higher than average. We used time series of wind and freshwater input to evaluate the influence of physical forcing on oceanographic patterns, and sampled hydrography and surface plankton concentrations within a 182 km2 grid off Willapa Bay, WA. Additionally, two longer transects, one cross-shelf and the other along-shore, were made to discern the extent of plume influence on larval crab and fish abundance. We found that plume waters that were trapped in a northward-flowing coastal-boundary current during downwelling conditions were advected offshore after several days of upwelling-favorable winds. Neustonic collections of brachyuran larvae and ichthyoplankton varied in response to this large seaward advective event. Megalopae of cancrid crabs exhibited patterns of both offshore transport (Cancer oregonensis/productus) and nearshore retention (C. magister). Additionally, abundant numbers of large juvenile widow (Sebastes entomelas) and yellowtail (S. flavidus) rockfish of a size appropriate for settlement were sampled during a period when ocean conditions favored high recruitment success. These results demonstrated that the response of planktonic crab larvae and ichthyoplankton to large-scale advection varied by species, with larger and more vagile fish exhibiting less evidence of passive transport than smaller crab larvae. Importantly, portions of the planktonic fish and crab

Associations between accelerated glacier mass wastage and increased summer temperature in coastal regions

Science.gov (United States)

Dyurgerov, M.; McCabe, G.J.

2006-01-01

Low-elevation glaciers in coastal regions of Alaska, the Canadian Arctic, individual ice caps around the Greenland ice sheet, and the Patagonia Ice Fields have an aggregate glacier area of about 332 ?? 103 km 2 and account for approximately 42% of all the glacier area outside the Greenland and Antarctic ice sheets. They have shown volume loss, especially since the end of the 1980s, increasing from about 45% in the 1960s to nearly 67% in 2003 of the total wastage from all glaciers on Earth outside those two largest ice sheets. Thus, a disproportionally large contribution of coastal glacier ablation to sea level rise is evident. We examine cumulative standardized departures (1961-2000 reference period) of glacier mass balances and air temperature data in these four coastal regions. Analyses indicate a strong association between increases in glacier volume losses and summer air temperature at regional and global scales. Increases in glacier volume losses in the coastal regions also coincide with an accelerated rate of ice discharge from outlet glaciers draining the Greenland and West Antarctic ice sheets. These processes imply further increases in sea level rise. ?? 2006 Regents of the University of Colorado.

Subsurface ammonium maxima in northern Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Satyanarayana, D.; Sahu, S.D.; Panigrahy, P.K.; Sarma, V.V.; Suguna, C.

environments: The eastern tropical North Pacific Ocean and the Cariaco Trench. PhD Thesis, University of California at Los Angeles, 270 pp. Codispoti, L. A. (1981). Temporal nutrient variability in three different upwelling regions. In Coastal Upwelling, ed...

Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

Directory of Open Access Journals (Sweden)

A. Randelhoff

2018-04-01

Full Text Available The future of Arctic marine ecosystems has received increasing attention in recent years as the extent of the sea ice cover is dwindling. Although the Pacific and Atlantic inflows both import huge quantities of nutrients and plankton, they feed into the Arctic Ocean in quite diverse regions. The strongly stratified Pacific sector has a historically heavy ice cover, a shallow shelf and dominant upwelling-favourable winds, while the Atlantic sector is weakly stratified, with a dynamic ice edge and a complex bathymetry. We argue that shelf break upwelling is likely not a universal but rather a regional, albeit recurring, feature of the new Arctic. It is the regional oceanography that decides its importance through a range of diverse factors such as stratification, bathymetry and wind forcing. Teasing apart their individual contributions in different regions can only be achieved by spatially resolved time series and dedicated modelling efforts. The Northern Barents Sea shelf is an example of a region where shelf break upwelling likely does not play a dominant role, in contrast to the shallower shelves north of Alaska where ample evidence for its importance has already accumulated. Still, other factors can contribute to marked future increases in biological productivity along the Arctic shelf break. A warming inflow of nutrient-rich Atlantic Water feeds plankton at the same time as it melts the sea ice, permitting increased photosynthesis. Concurrent changes in sea ice cover and zooplankton communities advected with the boundary currents make for a complex mosaic of regulating factors that do not allow for Arctic-wide generalizations.

Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

Science.gov (United States)

Randelhoff, Achim; Sundfjord, Arild

2018-04-01

The future of Arctic marine ecosystems has received increasing attention in recent years as the extent of the sea ice cover is dwindling. Although the Pacific and Atlantic inflows both import huge quantities of nutrients and plankton, they feed into the Arctic Ocean in quite diverse regions. The strongly stratified Pacific sector has a historically heavy ice cover, a shallow shelf and dominant upwelling-favourable winds, while the Atlantic sector is weakly stratified, with a dynamic ice edge and a complex bathymetry. We argue that shelf break upwelling is likely not a universal but rather a regional, albeit recurring, feature of the new Arctic. It is the regional oceanography that decides its importance through a range of diverse factors such as stratification, bathymetry and wind forcing. Teasing apart their individual contributions in different regions can only be achieved by spatially resolved time series and dedicated modelling efforts. The Northern Barents Sea shelf is an example of a region where shelf break upwelling likely does not play a dominant role, in contrast to the shallower shelves north of Alaska where ample evidence for its importance has already accumulated. Still, other factors can contribute to marked future increases in biological productivity along the Arctic shelf break. A warming inflow of nutrient-rich Atlantic Water feeds plankton at the same time as it melts the sea ice, permitting increased photosynthesis. Concurrent changes in sea ice cover and zooplankton communities advected with the boundary currents make for a complex mosaic of regulating factors that do not allow for Arctic-wide generalizations.

Coastal Change Analysis Program (C-CAP) Regional Land Cover Data and Change Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

Challenges of Tsunami Disaster and Extreme climate Events Along Coastal Region in Asia-Pacific

Science.gov (United States)

Chaudhari, S.

2017-12-01

South Asia is more vulnerable to Geo disasters and impacts of climate changes in recent years. On 26 December 2004 massive waves triggered by an earthquake surged into coastal communities in Asia and East Africa with devastating force. Hitting Indonesia, Sri Lanka , Thailand and India hardest, the deadly waves swept more than 200 000 people to their deaths. Also in an another extreme climate change phenomenon during 2005 - 2006,causing heavy rains and flooding situation in the South Asia - Europe and Pacific region ,more than 100 million population in these regions are witnessing the social- economical and ecological risks and impacts due to climate changes and Geohazards. For mitigating geo-disasters, marine hazards and rehabilitation during post tsunami period, scientific knowledge is needed, requiring experienced research communities who can train the local population during tsunami rehabilitation. Several civil society institutions jointly started the initiatives on the problem identifications in management of risks in geo-disasters, tsunami rehabilitation ,Vulnerability and risk assessments for Geohazards etc., to investigate problems related to social-economic and ecological risks and management issues resulting from the December tsunami and Geo- disaster, to aid mitigation planning in affected areas and to educate scientists and local populations to form a basis for sustainable and economic solutions. The poster aims to assess the potential risk and hazard , technical issues, problems and damage arising from Tsunami in the Asia-pacific region in coastal geology, coastal ecosystems and coastal environmental systems . This poster deals with the status and issues of interactions between Human and Ocean Systems, Geo-risks, marine risks along coastal region of Asia- Pacific and also human influence on the earth system . The poster presentation focuses on capacity building of the local population, scientists and researchers for integration of human and ocean

Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upwelling region

International Nuclear Information System (INIS)

Blasco, D.; MacIsaac, J.J.; Packard, T.T.; Dugdale, R.C.

1984-01-01

Nitrate reductase (NR) activity and 15 NO 3 - uptake in phytoplankton were compared under different environmental conditions on two cruises in the upwelling region off Peru. The NR activity and NO 3 - uptake rates responded differently to light and nutrients and the differences led to variations in the uptake:reductase ratio. Analysis of these variations suggests that the re-equilibration time of the two processes in response to environmental perturbation is an important source of variability. The nitrate uptake system responds faster than the nitrate reductase system. Considering these differences in response time, the basic differences in the two processes, and the differences in their measurement, the authors conclude that the NR activity measures the current nitrate-reducing potential, which relfects NO 3 - assimilation before the sampling time, while 15 NO 3 - uptake measures NO 3 - assimilation in the 6-h period following sampling. Thus, considering the sampling time as a point of reference, the former is a measure of the past and the latter is a measure of the future

A meta-analysis of plant facilitation in coastal dune systems: responses, regions, and research gaps.

Science.gov (United States)

Castanho, Camila de Toledo; Lortie, Christopher J; Zaitchik, Benjamin; Prado, Paulo Inácio

2015-01-01

Empirical studies in salt marshes, arid, and alpine systems support the hypothesis that facilitation between plants is an important ecological process in severe or 'stressful' environments. Coastal dunes are both abiotically stressful and frequently disturbed systems. Facilitation has been documented, but the evidence to date has not been synthesized. We did a systematic review with meta-analysis to highlight general research gaps in the study of plant interactions in coastal dunes and examine if regional and local factors influence the magnitude of facilitation in these systems. The 32 studies included in the systematic review were done in coastal dunes located in 13 countries around the world but the majority was in the temperate zone (63%). Most of the studies adopt only an observational approach to make inferences about facilitative interactions, whereas only 28% of the studies used both observational and experimental approaches. Among the factors we tested, only geographic region mediates the occurrence of facilitation more broadly in coastal dune systems. The presence of a neighbor positively influenced growth and survival in the tropics, whereas in temperate and subartic regions the effect was neutral for both response variables. We found no evidence that climatic and local factors, such as life-form and life stage of interacting plants, affect the magnitude of facilitation in coastal dunes. Overall, conclusions about plant facilitation in coastal dunes depend on the response variable measured and, more broadly, on the geographic region examined. However, the high variability and the limited number of studies, especially in tropical region, indicate we need to be cautious in the generalization of the conclusions. Anyway, coastal dunes provide an important means to explore topical issues in facilitation research including context dependency, local versus regional drivers of community structure, and the importance of gradients in shaping the outcome of net

A meta-analysis of plant facilitation in coastal dune systems: responses, regions, and research gaps

Directory of Open Access Journals (Sweden)

Camila de Toledo Castanho

2015-02-01

Full Text Available Empirical studies in salt marshes, arid, and alpine systems support the hypothesis that facilitation between plants is an important ecological process in severe or ‘stressful’ environments. Coastal dunes are both abiotically stressful and frequently disturbed systems. Facilitation has been documented, but the evidence to date has not been synthesized. We did a systematic review with meta-analysis to highlight general research gaps in the study of plant interactions in coastal dunes and examine if regional and local factors influence the magnitude of facilitation in these systems. The 32 studies included in the systematic review were done in coastal dunes located in 13 countries around the world but the majority was in the temperate zone (63%. Most of the studies adopt only an observational approach to make inferences about facilitative interactions, whereas only 28% of the studies used both observational and experimental approaches. Among the factors we tested, only geographic region mediates the occurrence of facilitation more broadly in coastal dune systems. The presence of a neighbor positively influenced growth and survival in the tropics, whereas in temperate and subartic regions the effect was neutral for both response variables. We found no evidence that climatic and local factors, such as life-form and life stage of interacting plants, affect the magnitude of facilitation in coastal dunes. Overall, conclusions about plant facilitation in coastal dunes depend on the response variable measured and, more broadly, on the geographic region examined. However, the high variability and the limited number of studies, especially in tropical region, indicate we need to be cautious in the generalization of the conclusions. Anyway, coastal dunes provide an important means to explore topical issues in facilitation research including context dependency, local versus regional drivers of community structure, and the importance of gradients in shaping

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bamberger, Judith A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-02-28

This report evaluates the physics of the upwell flow in pulse jet mixed systems in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Although the initial downward flow and radial flow from jets characteristic of pulse jet mixers (PJMs) has been analyzed, the upwells have received considerably less attention despite having significant implications for vessel mixing. Do the upwells behave like jets? How do the upwells scale? When will the central upwell break through? What proportion of the vessel is blended by the upwells themselves? Indeed, how the physics of the central upwell is affected by multiple PJMs (e.g., six in the proposed mixing vessels), non-Newtonian rheology, and significant multicomponent solids loadings remain unexplored.

Meteorological constraints on oceanic halocarbons above the Peruvian Upwelling

OpenAIRE

S. Fuhlbrügge; B. Quack; E. Atlas; A. Fiehn; H. Hepach; K. Krüger

2015-01-01

Halogenated very short lived substances (VSLS) are naturally produced in the ocean and emitted to the atmosphere. Recently, oceanic upwelling regions in the tropical East Atlantic were identified as strong sources of brominated halocarbons to the atmosphere. During a cruise of R/V METEOR in December 2012 the oceanic sources and emissions of various halogenated trace gases and their mixing ratios in the marine atmospheric boundary layer (M...

Properties of Red Sea coastal currents

KAUST Repository

Churchill, J.H.

2014-02-14

Properties of coastal flows of the central Red Sea are examined using 2 years of velocity data acquired off the coast of Saudi Arabia near 22 °N. The tidal flow is found to be very weak. The strongest tidal constituent, the M2 tide, has a magnitude of order 4 cm s−1. Energetic near-inertial and diurnal period motions are observed. These are surface-intensified currents, reaching magnitudes of >10 cm s−1. Although the diurnal currents appear to be principally wind-driven, their relationship with the surface wind stress record is complex. Less than 50% of the diurnal current variance is related to the diurnal wind stress through linear correlation. Correlation analysis reveals a classical upwelling/downwelling response to the alongshore wind stress. However, less than 30% of the overall sub-inertial variance can be accounted for by this response. The action of basin-scale eddies, impinging on the coastal zone, is implicated as a primary mechanism for driving coastal flows.

Climate Outreach Using Regional Coastal Ocean Observing System Portals

Science.gov (United States)

Anderson, D. M.; Hernandez, D. L.; Wakely, A.; Bochenek, R. J.; Bickel, A.

2015-12-01

Coastal oceans are dynamic, changing environments affected by processes ranging from seconds to millennia. On the east and west coast of the U.S., regional observing systems have deployed and sustained a remarkable diverse array of observing tools and sensors. Data portals visualize and provide access to real-time sensor networks. Portals have emerged as an interactive tool for educators to help students explore and understand climate. Bringing data portals to outreach events, into classrooms, and onto tablets and smartphones enables educators to address topics and phenomena happening right now. For example at the 2015 Charleston Science Technology Engineering and Math (STEM) Festival, visitors navigated the SECOORA (Southeast Coastal Ocean Observing regional Association) data portal to view the real-time marine meteorological conditions off South Carolina. Map-based entry points provide an intuitive interface for most students, an array of time series and other visualizations depict many of the essential principles of climate science manifest in the coastal zone, and data down-load/ extract options provide access to the data and documentation for further inquiry by advanced users. Beyond the exposition of climate principles, the portal experience reveals remarkable technologies in action and shows how the observing system is enabled by the activity of many different partners.

Factors regulating early life history dispersal of Atlantic cod (Gadus morhua) from coastal Newfoundland.

Science.gov (United States)

Stanley, Ryan R E; deYoung, Brad; Snelgrove, Paul V R; Gregory, Robert S

2013-01-01

To understand coastal dispersal dynamics of Atlantic cod (Gadus morhua), we examined spatiotemporal egg and larval abundance patterns in coastal Newfoundland. In recent decades, Smith Sound, Trinity Bay has supported the largest known overwintering spawning aggregation of Atlantic cod in the region. We estimated spawning and dispersal characteristics for the Smith Sound-Trinity Bay system by fitting ichthyoplankton abundance data to environmentally-driven, simplified box models. Results show protracted spawning, with sharply increased egg production in early July, and limited dispersal from the Sound. The model for the entire spawning season indicates egg export from Smith Sound is 13%•day(-1) with a net mortality of 27%•day(-1). Eggs and larvae are consistently found in western Trinity Bay with little advection from the system. These patterns mirror particle tracking models that suggest residence times of 10-20 days, and circulation models indicating local gyres in Trinity Bay that act in concert with upwelling dynamics to retain eggs and larvae. Our results are among the first quantitative dispersal estimates from Smith Sound, linking this spawning stock to the adjacent coastal waters. These results illustrate the biophysical interplay regulating dispersal and connectivity originating from inshore spawning of coastal northwest Atlantic.

Factors regulating early life history dispersal of Atlantic cod (Gadus morhua from coastal Newfoundland.

Directory of Open Access Journals (Sweden)

Ryan R E Stanley

Full Text Available To understand coastal dispersal dynamics of Atlantic cod (Gadus morhua, we examined spatiotemporal egg and larval abundance patterns in coastal Newfoundland. In recent decades, Smith Sound, Trinity Bay has supported the largest known overwintering spawning aggregation of Atlantic cod in the region. We estimated spawning and dispersal characteristics for the Smith Sound-Trinity Bay system by fitting ichthyoplankton abundance data to environmentally-driven, simplified box models. Results show protracted spawning, with sharply increased egg production in early July, and limited dispersal from the Sound. The model for the entire spawning season indicates egg export from Smith Sound is 13%•day(-1 with a net mortality of 27%•day(-1. Eggs and larvae are consistently found in western Trinity Bay with little advection from the system. These patterns mirror particle tracking models that suggest residence times of 10-20 days, and circulation models indicating local gyres in Trinity Bay that act in concert with upwelling dynamics to retain eggs and larvae. Our results are among the first quantitative dispersal estimates from Smith Sound, linking this spawning stock to the adjacent coastal waters. These results illustrate the biophysical interplay regulating dispersal and connectivity originating from inshore spawning of coastal northwest Atlantic.

Strengthening Coastal Pollution Management in the Wider Caribbean Region

NARCIS (Netherlands)

Lavieren, van H.; Metcalfe, C.D.; Drouillard, K.; Sale, P.; Gold-Bouchot, G.; Reid, R.; Vermeulen, L.C.

2011-01-01

Control of aquatic pollution is critical for improving coastal zone management and for the conservation of fisheries resources. Countries in the Wider Caribbean Region (WCR) generally lack monitoring capacity and do not have reliable information on the levels and distribution of pollutants,

Mass-specific respiration of mesozooplankton and its role in the maintenance of an oxygen-deficient ecological barrier (BEDOX) in the upwelling zone off Chile upon presence of a shallow oxygen minimum zone

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Donoso, Katty; Escribano, Ruben

2014-01-01

A shallow oxygen minimum zone (OMZ) in the coastal upwelling zone off Chile may vertically confine most zooplankton to a narrow (oxygen consumption of the mesozooplankton community obtained in Bay of Mejillones, northern Chile (23°S) in May 2010, December 2010 and August 2011. Mass-specific respiration rates were in the range of 8.2-24.5 μmol O2 mg dry mass- 1 day- 1, at an average temperature of 12 °C. Estimates of the mesozooplankton biomass in the water column indicated that its aerobic respiration may remove daily a maximum of about 20% of oxygen available at the base of the oxycline. Since previous work indicates that zooplankton aggregate near the base of the oxycline, the impact of aerobic respiration on oxygen content might be even stronger at this depth. Mesozooplankton respiration, along with community respiration by microorganisms near the base of the oxycline and a strongly stratified condition (limiting vertical flux of O2), are suggested as being critical factors causing and maintaining a persistent subsurface oxygen-deficient ecological barrier (BEDOX) in the upwelling zone. This BEDOX layer can have a major role in affecting and regulating zooplankton distribution and their dynamics in the highly productive coastal upwelling zone of the Humboldt Current System.

Dinoflagellate blooms in upwelling systems: Seeding, variability, and contrasts with diatom bloom behaviour

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Smayda, T. J.; Trainer, V. L.

2010-04-01

The influence of diatom bloom behaviour, dinoflagellate life cycles, propagule type and upwelling bloom cycles on the seeding of dinoflagellate blooms in eastern boundary current upwelling systems is evaluated. Winter-spring diatom bloom behaviour is contrasted with upwelling bloom behaviour because their phenology impacts dinoflagellate blooms. The winter-spring diatom bloom is usually sustained, whereas the classical upwelling diatom bloom occurs as a series of separate, recurrent mini-blooms intercalated by upwelling-relaxation periods, during which dinoflagellates often bloom. Four sequential wind-regulated phases characterize upwelling cycles, with each phase having different effects on diatom and dinoflagellate bloom behaviour: bloom “spin up”, bloom maximum, bloom “spin down”, and upwelling relaxation. The spin up - bloom maximum is the period of heightened diatom growth; the spin down - upwelling-relaxation phases are the periods when dinoflagellates often bloom. The duration, intensity and ratio of the upwelling and relaxation periods making up upwelling cycles determine the potential for dinoflagellate blooms to develop within a given upwelling cycle and prior to the subsequent “spin up” of upwelling that favours diatom blooms. Upwelling diatoms and meroplanktonic dinoflagellates have three types of propagules available to seed blooms: vegetative cells, resting cells and resting cysts. However, most upwelling dinoflagellates are holoplanktonic, which indicates that the capacity to form resting cysts is not an absolute requirement for growth and survival in upwelling systems. The long-term (decadal) gaps in bloom behaviour of Gymnodinium catenatum and Lingulodinium polyedrum, and the unpredictable bloom behaviour of dinoflagellates generally, are examined from the perspective of seeding strategies. Mismatches between observed and expected in situ bloom behaviour and resting cyst dynamics are common among upwelling dinoflagellates. This

Towards a regional coastal ocean observing system: An initial design for the Southeast Coastal Ocean Observing Regional Association

Science.gov (United States)

Seim, H. E.; Fletcher, M.; Mooers, C. N. K.; Nelson, J. R.; Weisberg, R. H.

2009-05-01

A conceptual design for a southeast United States regional coastal ocean observing system (RCOOS) is built upon a partnership between institutions of the region and among elements of the academic, government and private sectors. This design envisions support of a broad range of applications (e.g., marine operations, natural hazards, and ecosystem-based management) through the routine operation of predictive models that utilize the system observations to ensure their validity. A distributed information management system enables information flow, and a centralized information hub serves to aggregate information regionally and distribute it as needed. A variety of observing assets are needed to satisfy model requirements. An initial distribution of assets is proposed that recognizes the physical structure and forcing in the southeast U.S. coastal ocean. In-situ data collection includes moorings, profilers and gliders to provide 3D, time-dependent sampling, HF radar and surface drifters for synoptic sampling of surface currents, and satellite remote sensing of surface ocean properties. Nested model systems are required to properly represent ocean conditions from the outer edge of the EEZ to the watersheds. An effective RCOOS will depend upon a vital "National Backbone" (federally supported) system of in situ and satellite observations, model products, and data management. This dependence highlights the needs for a clear definition of the National Backbone components and a Concept of Operations (CONOPS) that defines the roles, functions and interactions of regional and federal components of the integrated system. A preliminary CONOPS is offered for the Southeast (SE) RCOOS. Thorough system testing is advocated using a combination of application-specific and process-oriented experiments. Estimates of costs and personnel required as initial components of the SE RCOOS are included. Initial thoughts on the Research and Development program required to support the RCOOS are

Compound-specific δ15N amino acid measurements in littoral mussels in the California upwelling ecosystem: a new approach to generating baseline δ15N Isoscapes for coastal ecosystems.

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Natasha L Vokhshoori

Full Text Available We explored δ(15N compound-specific amino acid isotope data (CSI-AA in filter-feeding intertidal mussels (Mytilus californianus as a new approach to construct integrated isoscapes of coastal primary production. We examined spatial δ(15N gradients in the California Upwelling Ecosystem (CUE, determining bulk δ(15N values of mussel tissue from 28 sites between Port Orford, Oregon and La Jolla, California, and applying CSI-AA at selected sites to decouple trophic effects from isotopic values at the base of the food web. Bulk δ(15N values showed a strong linear trend with latitude, increasing from North to South (from ∼ 7‰ to ∼ 12‰, R(2 = 0.759. In contrast, CSI-AA trophic position estimates showed no correlation with latitude. The δ(15N trend is therefore most consistent with a baseline δ(15N gradient, likely due to the mixing of two source waters: low δ(15N nitrate from the southward flowing surface California Current, and the northward transport of the California Undercurrent (CUC, with (15N-enriched nitrate. This interpretation is strongly supported by a similar linear gradient in δ(15N values of phenylalanine (δ(15NPhe, the best AA proxy for baseline δ(15N values. We hypothesize δ(15N(Phe values in intertidal mussels can approximate annual integrated δ(15N values of coastal phytoplankton primary production. We therefore used δ(15N(Phe values to generate the first compound-specific nitrogen isoscape for the coastal Northeast Pacific, which indicates a remarkably linear gradient in coastal primary production δ(15N values. We propose that δ(15N(Phe isoscapes derived from filter feeders can directly characterize baseline δ(15N values across major biochemical provinces, with potential applications for understanding migratory and feeding patterns of top predators, monitoring effects of climate change, and study of paleo- archives.

Macro-Scale Patterns in Upwelling/Downwelling Activity at North American West Coast.

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Romeo Saldívar-Lucio

Full Text Available The seasonal and interannual variability of vertical transport (upwelling/downwelling has been relatively well studied, mainly for the California Current System, including low-frequency changes and latitudinal heterogeneity. The aim of this work was to identify potentially predictable patterns in upwelling/downwelling activity along the North American west coast and discuss their plausible mechanisms. To this purpose we applied the min/max Autocorrelation Factor technique and time series analysis. We found that spatial co-variation of seawater vertical movements present three dominant low-frequency signals in the range of 33, 19 and 11 years, resembling periodicities of: atmospheric circulation, nodal moon tides and solar activity. Those periodicities might be related to the variability of vertical transport through their influence on dominant wind patterns, the position/intensity of pressure centers and the strength of atmospheric circulation cells (wind stress. The low-frequency signals identified in upwelling/downwelling are coherent with temporal patterns previously reported at the study region: sea surface temperature along the Pacific coast of North America, catch fluctuations of anchovy Engraulis mordax and sardine Sardinops sagax, the Pacific Decadal Oscillation, changes in abundance and distribution of salmon populations, and variations in the position and intensity of the Aleutian low. Since the vertical transport is an oceanographic process with strong biological relevance, the recognition of their spatio-temporal patterns might allow for some reasonable forecasting capacity, potentially useful for marine resources management of the region.

Investigation of different coastal processes in Indonesian waters using SeaWiFS data

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Hendiarti, Nani; Siegel, Herbert; Ohde, Thomas

2004-01-01

SeaWiFS data were applied to investigate coastal processes in Indonesian waters around the most populated island of Java. Coastal processes due to wind forcing were studied the first time using SeaWiFS-derived chlorophyll and TSM concentrations in combination with AVHRR-derived SST in the period from September 1997 to December 2001. Upwelling events were studied along the southern coast of Java during the southeast monsoon (June to September). Satellite-derived chlorophyll concentrations higher than 0.8 mg/ m3 and sea-surface temperatures lower than 28°C are indications of upwelling. Upwelling events influence the distribution and growth of phytoplankton and provide by that good feeding condition for zooplankton, larvae, juvenile and adult of pelagic fish. Coastal discharge into the western Java Sea contains organic and inorganic materials originating from different sources. Diffuse impacts, particularly from fish farms and aquaculture, as well as coastal erosion influence large coastal areas during the rainy season (December to March), and to a lesser extent during the dry season. Strong Citarum river discharge was observed during the transition phase from the rainy to the dry season (March and April), when the maximum amount of transported material reaches the sea. The river plume is evident from chlorophyll concentrations higher than 2.5 mg/ m3, and suspended particulate matter concentrations of more than 8 mg/dm3. The Sunda Strait is seasonally influenced by water transport from the Java Sea and from the Indian Ocean. The satellite data show that water transport from the Java Sea occurs during the pre-dominantly easterly winds period (June to September). This is characterized by warm water (SST higher than 29.5°C) and chlorophyll concentrations higher than 0.5 mg/ m3. This water transport influences the fish abundance in the Sunda Strait. High fish catches coincide with the presence of Java Sea water, while the surface currents lead to the migration of

The influence of atmospheric cold fronts on larval supply and settlement of intertidal invertebrates: Case studies in the Cabo Frio coastal upwelling system (SE Brazil)

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de Azevedo Mazzuco, Ana Carolina; Christofoletti, Ronaldo Adriano; Coutinho, Ricardo; Ciotti, Áurea Maria

2018-07-01

Atmospheric fronts such as cold fronts are dynamic mesoscale systems with potential effects on the ecology of marine communities. In this study, larval dynamics in subtropical rocky shore communities were evaluated under the influence of atmospheric frontal systems. The hypothesis is that these systems may promote favorable conditions for larval supply and settlement regardless of taxa or site, and that supply and settlement vary in association with fluctuations of meteorological and oceanographic conditions driven by the fronts. This study was carried out in the Southeastern Brazil littoral region under the influence of coastal upwelling events (Cabo Frio) and subject to weekly atmospheric frontal systems, cold polar fronts. The spatial and temporal variability of larvae and settlers of barnacles and mussels were assessed by collecting daily samples at three sites before, during and after atmospheric cold fronts, and the atmospheric and pelagic conditions were monitored. Contrasts among rates, events and sites were tested using discriminant function analysis, analyses of variance and correlation analysis. Atmospheric frontal systems were considered to influence the sites when wind direction changed to SW-S-SE and persisted for at least a day, and waves from SW-SW-SE increased in height. The results corroborate the hypothesis that cold fronts are important regulators of larval dynamics and intertidal communities on rocky shores of the studied area. Both larval supply and settlement were highly correlated with fluctuations in wind speed and direction. Higher settlement rates of barnacles occurred one-day prior, or on the onset of cold fronts. Mussels species tended to settle during all conditions, but on average, settlement rates were higher during the cold fronts. Some temporal trends were site specific and variability was detected among taxa and larval stages. Our findings suggest that mesoscale oceanographic/atmospheric systems are particularly relevant on the

Reverse trends of TEX86 temperature in coastal areas of the East China Sea over the last 100 years: implication for global warming and regional circulation

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Cao, Y.; Xing, L.; Zhang, T.

2017-12-01

To reconstruct and compare the SST changes in different regions of the ECS over the last 100 years, in this study, we analyzed iGDGTs compounds and TEX86 index in two sediment cores (DH5-1 and DH6-2) from the inner shelf of the East China Sea (ECS). GDGT-0 and GDGT-5 in the two cores account for 80% of iGDGTs, significantly more abundant than the other iGDGTs compounds. It is also found that iGDGTs are mainly derived from marine Thaumarchaeota. TEXH86 temperatures varied from 17 °C to 22 °C (average 19.4 °C), showing a gradual increase in Core DH5-1 near the Changjiang River Estuary, corresponding to global warming and temperature rise in the ECS over the last 100 years. However, in Core DH6-2 further away from the Changjiang River Estuary, TEXH86 temperatures gradually decreased over the last 80 years with a range of 15.3 °C-18.3 °C, which is attributed to the strengthened near-shore Kuroshio Branch Current transporting more subsurface cold water to the ECS coastal area. In future, more sites should be investigated to confirm the range of the coastal area where the decrease in SST is caused by upwelling subsurface water.

U.S. Geological Survey (USGS) Western Region: Coastal and Ocean Science

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Kinsinger, Anne E.

2009-01-01

USGS Western Region Coastal and Ocean Science is interdisciplinary, collaborative, and integrates expertise from all USGS Disciplines, and ten of its major Science Centers, in Alaska, Hawai'i, California, Washington, and Oregon. The scientific talent, laboratories, and research vessels in the Western Region and across the Nation, strategically position the USGS to address broad geographic and oceanographic research topics. USGS information products inform resource managers and policy makers who must balance conservation mandates with increasing demands for resources that sustain the Nation's economy. This fact sheet describes but a few examples of the breadth of USGS science conducted in coastal, nearshore, and ocean environments along our Nation's West Coast and Pacific Islands.

A numerical analysis of shipboard and coastal zone color scanner time series of new production within Gulf Stream cyclonic eddies in the South Atlantic Bight

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Pribble, J. Raymond; Walsh, John J.; Dieterle, Dwight A.; Mueller-Karger, Frank E.

1994-01-01

Eddy-induced upwelling occurs along the western edge of the Gulf Stream between Cape Canaveral, Florida, and Cape Hatteras, North Carolina, in the South Atlantic Bight (SAB). Coastal zone color scanner images of 1-km resolution spanning the period April 13-21, 1979, were processed to examine these eddy features in relation to concurrent shipboard and current/temperature measurements at moored arrays. A quasi-one-dimensional (z), time dependent biological model, using only nitrate as a nutrient source, has been combined with a three-dimensional physical model in an attempt to replicate the observed phytoplankton field at the northward edge of an eddy. The model is applicable only to the SAB south of the Charleston Bump, at approximately 31.5 deg N, since no feature analogous to the bump exists in the model bathymetry. The modeled chlorophyll, nitrate, and primary production fields of the euphotic zone are very similar to those obtained from the satellite and shipboard data at the leading edges of the observed eddies south of the Charleston Bump. The horizontal and vertical simulated fluxes of nitrate and chlorophyll show that only approximately 10% of the upwelled nitrate is utilized by the phytoplankton of the modeled grid box on the northern edge of the cyclone, while approximately 75% is lost horizontally, with the remainder still in the euphotic zone after the 10-day period of the model. Loss of chlorophyll due to sinking is very small in this strong upwelling region of the cyclone. The model is relatively insensitive to variations in the sinking parameterization and the external nitrate and chlorophyll fields but is very sensitive to a reduction of the maximum potential growth rate to half that measured. Given the success of this model in simulating the new production of the selcted upwelling region, other upwelling regions for which measurements or successful models of physical and biological quantities and rates exist could be modeled similarly.

Regional biomass stores and dynamics in forests of coastal Alaska

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Mikhaill A. Yatskov; Mark E. Harmon; Olga N. Krankina; Tara M. Barrett; Kevin R. Dobelbower; Andrew N. Gray; Becky Fasth; Lori Trummer; Toni L. Hoyman; Chana M. Dudoit

2015-01-01

Coastal Alaska is a vast forested region (6.2 million ha) with the potential to store large amounts of carbon in live and dead biomass thus influencing continental and global carbon dynamics. The main objectives of this study were to assess regional biomass stores, examine the biomass partitioning between live and dead pools, and evaluate the effect of disturbance on...

Time scales of pattern evolution from cross-spectrum analysis of advanced very high resolution radiometer and coastal zone color scanner imagery

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Denman, Kenneth L.; Abbott, Mark R.

1994-01-01

We have selected square subareas (110 km on a side) from coastal zone color scanner (CZCS) and advanced very high resolution radiometer (AVHRR) images for 1981 in the California Current region off northern California for which we could identify sequences of cloud-free data over periods of days to weeks. We applied a two-dimensional fast Fourier transformation to images after median filtering, (x, y) plane removal, and cosine tapering. We formed autospectra and coherence spectra as functions of a scalar wavenumber. Coherence estimates between pairs of images were plotted against time separation between images for several wide wavenumber bands to provide a temporal lagged coherence function. The temporal rate of loss of correlation (decorrelation time scale) in surface patterns provides a measure of the rate of pattern change or evolution as a function of spatial dimension. We found that patterns evolved (or lost correlation) approximately twice as rapidly in upwelling jets as in the 'quieter' regions between jets. The rapid evolution of pigment patterns (lifetime of about 1 week or less for scales of 50-100 km) ought to hinder biomass transfer to zooplankton predators compared with phytoplankton patches that persist for longer times. We found no significant differences between the statistics of CZCS and AVHRR images (spectral shape or rate of decorrelation). In addition, in two of the three areas studied, the peak correlation between AVHRR and CZCS images from the same area occurred at zero lag, indicating that the patterns evolved simutaneously. In the third area, maximum coherence between thermal and pigment patterns occurred when pigment images lagged thermal images by 1-2 days, mirroring the expected lag of high pigment behind low temperatures (and high nutrients) in recently upwelled water. We conclude that in dynamic areas such as coastal upwelling systems, the phytoplankton cells (identified by pigment color patterns) behave largely as passive scalars at the

The Triassic upwelling system of Arctic Alaska

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Yurchenko, I.; Graham, S. A.

2017-12-01

The Middle to Upper Triassic Shublik Formation of Arctic Alaska is a laterally and vertically heterogeneous rock unit that has been analyzed both in outcrop and in the subsurface. The Shublik Formation sediments are distinguished by a characteristic set of lithologies that include glauconitic, phosphatic, organic-rich, and cherty facies consistent with a coastal upwelling zone deposition interpretation. It is often recognized by abundance of impressions and shells of distinctive Triassic bivalves. To understand main controls on lithofacies distributions, this study reviews and refines lithologic and paleoenvironmental interpretations of the Shublik Formation, and incorporates the newly acquired detailed geochemical analyses of two complete Shublik cores. This work focuses on organic geochemistry (analyses of biomarkers and diamondoids), chemostratigraphy (hand-held XRF), and iron speciation analysis to reconstruct paleoproductivity and redox conditions. Based on the available evidence, during Shublik deposition, an upwelling-influenced open shelf resulted in high nutrient supply that stimulated algal blooms leading to high net organic productivity, reduced water transparency, oxygen deficiency, and water column stratification. Evidence of such eutrophic conditions is indicated by the lack of photic benthic organisms, bioturbation and trace fossils, and dominance of the monospecific light-independent epibenthic bivalves. The flat, subcircular, thin shells of these carbonate-secreting organisms allowed them to adapt to dysoxic conditions, and float on soft, soupy, muddy substrate. The distinctive clay- and organic-rich facies with abundant bivalves occurred on the mid to outer stable broad shelf, and were deposited when organic productivity at times overlapped with periods of increased siliciclastic input controlled by sea level and changes in local sediment dispersal systems, and therefore are more spatially and temporally localized than the widespread clay

Time-Series Analysis of Remotely-Sensed SeaWiFS Chlorophyll in River-Influenced Coastal Regions

Science.gov (United States)

Acker, James G.; McMahon, Erin; Shen, Suhung; Hearty, Thomas; Casey, Nancy

2009-01-01

The availability of a nearly-continuous record of remotely-sensed chlorophyll a data (chl a) from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission, now longer than ten years, enables examination of time-series trends for multiple global locations. Innovative data analysis technology available on the World Wide Web facilitates such analyses. In coastal regions influenced by river outflows, chl a is not always indicative of actual trends in phytoplankton chlorophyll due to the interference of colored dissolved organic matter and suspended sediments; significant chl a timeseries trends for coastal regions influenced by river outflows may nonetheless be indicative of important alterations of the hydrologic and coastal environment. Chl a time-series analysis of nine marine regions influenced by river outflows demonstrates the simplicity and usefulness of this technique. The analyses indicate that coastal time-series are significantly influenced by unusual flood events. Major river systems in regions with relatively low human impact did not exhibit significant trends. Most river systems with demonstrated human impact exhibited significant negative trends, with the noteworthy exception of the Pearl River in China, which has a positive trend.

Spatial distribution of common Minke whale (Balaenoptera acutorostrata) as an indication of a biological hotspot in the East Sea

Science.gov (United States)

Lee, Dasom; An, Yong Rock; Park, Kyum Joon; Kim, Hyun Woo; Lee, Dabin; Joo, Hui Tae; Oh, Young Geun; Kim, Su Min; Kang, Chang Keun; Lee, Sang Heon

2017-09-01

The minke whale (Balaenoptera acutorostrata) is the most common baleen whale among several marine mammal species observed in Korea. Since a high concentrated condition of prey to whales can be obtained by physical structures, the foraging whale distribution can be an indicator of biological hotspot. Our main objective is verifying the coastal upwelling-southwestern East Sea as a productive biological hotspot based on the geographical distribution of minke whales. Among the cetacean research surveys of the National Institute of Fisheries Science since 1999, 9 years data for the minke whales available in the East Sea were used for this study. The regional primary productivity derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) was used for a proxy of biological productivity. Minke whales observed during the sighting surveys were mostly concentrated in May and found mostly (approximately 70%) in the southwestern coastal areas (whales was found in recent years, which indicate that the major habitats of mink whales have been shifted into the north of the common coastal upwelling regions. This is consistent with the recently reported unprecedented coastal upwelling in the mid-eastern coast of Korea. Based on high phytoplankton productivity and high distribution of minke whales, the southwestern coastal regions can be considered as one of biological hotspots in the East Sea. These regions are important for ecosystem dynamics and the population biology of top marine predators, especially migratory whales and needed to be carefully managed from a resource management perspective.

Bangladesh’s dynamic coastal regions and sea-level rise

Directory of Open Access Journals (Sweden)

Hugh Brammer

2014-01-01

Full Text Available The physical geography of Bangladesh’s coastal area is more diverse and dynamic than is generally recognised. Failure to recognise this has led to serious misconceptions about the potential impacts of a rising sea-level on Bangladesh with global warming. This situation has been aggravated by accounts giving incorrect information on current rates of coastal erosion and land subsidence. This paper describes physical conditions within individual physiographic regions in Bangladesh’s coastal area based on ground-surveyed information, and it reviews possible area-specific mitigation measures to counter predicted rates of sea-level rise in the 21st century. Two important conclusions are drawn: the adoption of appropriate measures based on knowledge of the physical geography of potentially-affected areas could significantly reduce the currently-predicted displacement of many millions of people; and the impacts of a slowly-rising sea-level are currently much less than those generated by rapidly increasing population pressure on Bangladesh’s available land and water resources and by exposure to existing environmental hazards, and the latter problems need priority attention.

Winter-summer nutrient composition linkage to algae-produced toxins in shellfish at a eutrophic coastal lagoon (Óbidos lagoon, Portugal)

Science.gov (United States)

Pereira, Patrícia; Botelho, Maria João; Cabrita, Maria Teresa; Vale, Carlos; Moita, Maria Teresa; Gonçalves, Célia

2012-10-01

The current work examines the linkage of pronounced winter-summer fluctuations on the nutrient composition with phytoplankton assemblages and mussel toxicity produced by the presence of toxic dinoflagellates. The work was performed at the Óbidos lagoon, a coastal eutrophic ecosystem that is permanently connected to an area characterized by frequent upwelling episodes. The lagoon and adjoining coastal area exhibit recurrent incidents of diarrhetic and paralytic shellfish poisoning. The conclusions are based on: (1) inorganic and organic nutrients at five sites of the lower, middle and upper Óbidos lagoon, and inorganic nutrients at two sites of the adjacent coastal area; biannual campaigns were performed in winter and summer between 2006 and 2010; (2) phytoplankton assemblages at three sites of the lagoon (located at lower and upper areas) in winter and summer of 2009; (3) algae-derived toxicity of wild mussels from the lower lagoon and coastal area, on a 1-2 week time scale, over 2006 and 2009. Nutrient molar ratios in Óbidos lagoon contrast between winter and summer. The lower median ratios DIN:P (31 and 0.8) and Si:P (11 and 3.3) in summer reflect the excess of phosphate. Excess was mainly attributed to phosphorus regeneration in sediments of the upper lagoon with accentuated symptoms of eutrophication. Dissolved organic nitrogen and dissolved organic phosphorus were also higher in summer, particularly in this area. No significant winter-summer differences were recorded for nutrient ratios in the adjacent coastal area. Phytoplankton assemblages pointed to a winter-summer contrast characterized by a shift of non-siliceous-based phytoplankton to diatoms. The toxic dinoflagellate species (Gymnodinium catenatum, Dinophysis cf. acuminata and Dinophysis acuta), presumably imported from the adjacent coast following upwelling episodes in summer, were observed in the lower lagoon. In summer of the two surveyed years, toxins produced by dinoflagellates occurred in

Satellite observation of bio-optical indicators related to North-Western Black Sea coastal zone changes

Science.gov (United States)

Zoran, Maria

Satellite remote sensing provides a means for locating, identifying and mapping certain coastal zone features and assessing of spatio-temporal changes.The Romanian coastal zone of the Black Sea is a mosaic of complex, interacting ecosystems, exposed to dramatic changes due to natural and anthropogenic causes (increase in the nutrient and pollutant load of rivers input, industrial and municipal wastewater pollution along the coast, and dumping on the open sea). This study focuses on the assessment of coastal zone land cover changes based on the fusion of satellite remote sensing data.The evaluation of coastal zone landscapes is based upon different sub-functions which refer to landscape features such as water, soil, land-use, buildings, groundwater, biotope types. Mixed pixels result when the sensor's instantaneous field-of-view includes more than one land cover class on the ground. Based on different satellite data (Landsat TM, ETM, SAR ERS, IKONOS, Quickbird, and MODIS) was performed object recognition for North-Western Black Sea coastal zone. Preliminary results show significant coastline position changes of North Western Black Sea during the period of 1987-2007 and urban growth of Constantza town. Also the change in the position of the coastline is examined and linked to the urban expansion in order to determine if the changes are natural or anthropogenic. A distinction is made between landfill/sedimentation processes on the one hand and dredging/erosion processes on the other. Waves play an important role for shoreline configuration. Wave pattern could induce erosion and sedimentation. A quasi-linear model was used to model the rate of shoreline change. The vectors of shoreline were used to compare with wave spectra model in order to examine the accuracy of the coastal erosion model. The shoreline rate modeled from vectors data of SAR ERS-1 has a good correlation with a quasi-linear model. Wave refraction patterns are a good index for shoreline erosion. A coast

Critical review of studies on atmospheric dispersion in coastal regions

International Nuclear Information System (INIS)

Shearer, D.L.; Kaleel, R.J.

1982-09-01

This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models

Physical structure and algae community of summer upwelling off eastern Hainan

Science.gov (United States)

Xu, H.; Liu, S.; Xie, Q.; Hong, B.; Long, T.

2017-12-01

The upwelling system is the most productive ecosystem along the continental shelf of the northern South China Sea Shelf. It brings nutrient from bottom to surface and blooms biotic community driven by summer monsoon. In this study, we present observed results of physical and biotic community structures during August, 2015 in the upwelling system along Hainan eastern coast, which is one the strongest upwelling systems in the northern South China Sea. By using hydrological data collected by CTD, we found a significant cold water tongue with high salinity which extended from offshore to 100 m isobaths. However, dissolved oxygen (DO) showed a sandwich structure in which high core of DO concentration appeared at the layer from 5 m to 30 m. It possibly was caused by the advection transport of high DO from adjacent area. Basically, this upwelling system was constrained at northern area of 18.8ºN in horizontal due to the weakening summer monsoon in August. In addition, we collected water sample at the upwelling area and measured algae categories and concentration by high performance liquid chromatography (HPLC). Results show the biotic community was dominated by five types of algae mainly, they were diatoms, dinoflagellates, green algae, prokaryotes and prochlorococcus. And different patterns of different algae were demonstrated. In the upwelling area, diatoms and prokaryotes show opposite structures, and more complex pattern for the rest three algae indicating an active biotic community in the upwelling system.

Kinetics of N-Utilization By Natural Phytoplankton Assemblages During Upwelling Events At The NW Iberian Shelf

Science.gov (United States)

Brion, N.; Elskens, M.; Dehairs, F.; Baeyens, W.

2003-04-01

, nitrate uptake rate was dominant resulting in f-ratio values greater than 0.5, a characteristic of a new production regime. The new production rate is only marginally sensitive to increases of the ambient nitrate, but is drastically inhibited by small increases of the ambient ammonium. The situation of September 1999 was very close to that observed in July 1998, with higher nitrate concentrations in the coastal northern part of the sampling area dominated by upwelling.

Octopus vulgaris paralarvae vertical distribution in a fluctuating upwelling-downwelling system

Directory of Open Access Journals (Sweden)

Lorena Olmos Pérez

2014-06-01

- Upwelling situation: superficial waters (0-20m enter through the northern mouth of the Ría and are washed through the southern mouth. This water movement promotes the entrance of cold, bottom upwelled water through the southern mouth of the Ría. Under this scenario, Octopus paralarvae are concentrated at the surface (10-0m, thus leaving the Ría. This difference is bigger after strong upwelling during the previous days. Abundances inside the Ría are the highest, maybe because it acts as a temporal retention area, or because cold upwelled waters might stimulate hatching inside the Ría. Day/night changes under strong upwelling conditions: paralarvae abundance in both mouths was quite similar, except that during the day they were in sub-surficial waters (10-5 m, while at night paralarvae were mainly found close to the surface (0-5 m. This vertical distribution during the day is remarkable because paralarvae may select offward surface waters.

Occurrence and transport of 17 perfluoroalkyl acids in 12 coastal rivers in south Bohai coastal region of China with concentrated fluoropolymer facilities

International Nuclear Information System (INIS)

Wang, Pei; Lu, Yonglong; Wang, Tieyu; Fu, Yaning; Zhu, Zhaoyun; Liu, Shijie; Xie, Shuangwei; Xiao, Yang; Giesy, John P.

2014-01-01

Perfluoroalkyl acids (PFAAs) are emerging contaminants that have raised great concern in recent years. While PFAAs manufacturing becomes regulated in developed countries, production has been partly shifted to China. Eight fluoropolymer manufacturing facilities located in the South Bohai coastal region, one of the most populated areas of China, have been used to manufacture PFAA-related substances since 2001. The environmental consequence of the intensive production of PFAAs in this region remains largely unknown. We analyzed 17 PFAAs in twelve coastal rivers of this region, and found staggeringly high concentrations of perfluorooctanoic acid (PFOA) ranging from 0.96 to 4534.41 ng/L. The highest concentration was observed in the Xiaoqing River which received effluents from certain fluoropolymer facilities. Principal component analysis indicated similar sources of several perfluoroalkyl carboxylic acids (PFCAs) in all rivers, which indicated that atmospheric transport, wastewater treatment and surface runoff also acted as important supplements to direct discharge to surface water. - Highlights: • PFAAs were detected in rapidly urbanized regions. • PFOA was found predominant followed by short chain PFCAs. • Fluoropolymer facilities were associated with PFAAs contamination. • Higher PFAAs levels were found near the PTFE production facilities. • Diffusion of PFAAs from rivers to the sea was influenced by tide and current. - High level of PFOA was detected in the river water due to the fluoropolymer industries in South Bohai coastal region

Abyssal Upwelling and Downwelling and the role of boundary layers

Science.gov (United States)

McDougall, T. J.; Ferrari, R. M.

2016-02-01

The bottom-intensified mixing activity arising from the interaction of internal tides with bottom topography implies that the dianeutral advection in the ocean interior is downwards, rather than upwards as is required by continuity. The upwelling of Bottom Water through density surfaces in the deep ocean is however possible because of the sloping nature of the sea floor. A budget study of the abyss (deeper than 2000m) will be described that shows that while the upwelling of Bottom Water might be 25 Sv, this is achieved by very strong upwelling in the bottom turbulent boundary layer (of thickness 50m) of 100 Sv and strong downwelling in the ocean interior of 75 Sv. This downwelling occurs within 10 degrees of longitude of the continental boundaries. This near-boundary confined strong upwelling and downwelling clearly has implications for the Stommel-Arons circulation.

Triassic volcanic units in coastal region of Antofagasta, northern Chile

International Nuclear Information System (INIS)

Basso, M.; Cortes, J.A.; Marinovic, N

2001-01-01

U-Pb geochronological evidence of a Middle to Late Triassic volcanic event was found in the coastal region of Antofagasta, northern Chile (23 o -23 o 30 ). Two new ages were obtained from rhyolitic tuffs and an associated dome, which have classically been attributed to the Jurassic La Negra Formation (au)

An Altimetry-Derived Index of the Offshore Forcing on the "Pressure Point" of the West Florida Shelf: Anomalous Upwelling and Its Influence on Harmful Algal Blooms

Science.gov (United States)

Liu, Y.; Weisberg, R. H.; Lenes, J. M.; Zheng, L.; Hubbard, K.; Walsh, J. J.

2017-12-01

Gulf of Mexico Loop Current (LC) interactions with the West Florida Shelf (WFS) slope play an important role in shelf ecology through the upwelling of new inorganic nutrients across the shelf break. This is particularly the case when the LC impinges upon the shelf slope in the southwest portion of the WFS near the Dry Tortugas. By contacting shallow water isobaths at this "pressure point" the LC forcing sets the entire shelf into motion. Characteristic patterns of LC interactions with the WFS and their occurrences are identified from altimetry data using unsupervised neural network, self-organizing map. The duration of the occurrences of such LC patterns is used as an indicator of offshore forcing of anomalous upwelling. Consistency is found between the altimetry-derived offshore forcing and the occurrence and severity of WFS coastal blooms of the toxic dinoflagellate, Karenia brevis: years without major blooms tend to have prolonged LC contact at the "pressure point," whereas years with major blooms tend not to have prolonged offshore forcing. Resetting the nutrient state of the shelf by the coastal ocean circulation in response to deep-ocean forcing demonstrates the importance of physical oceanography in shelf ecology. A satellite altimetry-derived seasonal predictor for major K. brevis blooms is also proposed.

Ekman estimates of upwelling at cape columbine based on ...

African Journals Online (AJOL)

Ekman estimates of upwelling at cape columbine based on measurements of longshore wind from a 35-year time-series. AS Johnson, G Nelson. Abstract. Cape Columbine is a prominent headland on the south-west coast of Africa at approximately 32°50´S, where there is a substantial upwelling tongue, enhancing the ...

Are large macroalgal blooms necessarily bad? Nutrient impacts on seagrass in upwelling-influenced estuaries.

Science.gov (United States)

Hessing-Lewis, Margot L; Hacker, Sally D; Menge, Bruce A; McConville, Sea-oh; Henderson, Jeremy

2015-07-01

Knowledge of nutrient pathways and their resulting ecological interactions can alleviate numerous environmental problems associated with nutrient increases in both natural and managed systems. Although not unique, coastal systems are particularly prone to complex ecological interactions resulting from nutrient inputs from both the land and sea. Nutrient inputs to coastal systems often spur ulvoid macroalgal blooms, with negative consequences for seagrasses, primarily through shading, as well as through changes in local biogeochemistry. We conducted complementary field and mesocosm experiments in an upwelling-influenced estuary, where marine-derived nutrients dominate, to understand the direct and indirect effects of nutrients on the macroalgal-eelgrass (Zostera marina L.) interaction. In the field experiment, we found weak evidence that nutrients and/or macroalgal treatments had a negative effect on eelgrass. However, in the mesocosm experiment, we found that a combination of nutrient and macroalgal treatments led to strongly negative eelgrass responses, primarily via indirect effects associated with macroalgal additions. Together, increased total light attenuation and decreased sediment oxygen levels were associated with larger effects on eelgrass than shading alone, which was evaluated using mimic algae treatments that did not alter sediment redox potential. Nutrient addition in the mesocosms directly affected seagrass density; biomass, and morphology, but not as strongly as macroalgae. We hypothesize that the contrary results from these parallel experiments are a consequence of differences in the hydrodynamics between field and mesocosm settings. We suggest that the high rates of water movement and tidal submersion of our intertidal field experiments alleviated the light reduction and negative biogeochemical changes in the sediment associated with macroalgal canopies, as well as the nutrient effects observed in the mesocosm experiments. Furthermore, adaptation

NOAA's Coastal Change Analysis Program (C-CAP) 1992 to 2001 Regional Land Cover Change Data - Hawaii

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2001 to 2005 Regional Land Cover Change Data - Hawaii

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

The Benguela upwelling ecosystem lies adjacent to the south ...

African Journals Online (AJOL)

denise

The Benguela upwelling ecosystem lies adjacent to the south-western coast of Africa, from southern Angola. (15°S) to Cape Agulhas (35°S; Fig. 1). Ecologically, it is split into separate northern and southern sub- systems by a zone of intense perennial upwelling near. Lüderitz (26–27.5°S; Shannon 1985). As is charac-.

Upwelling features near Sri Lanka in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

ShreeRam, P.; Rao, L.V.G.

, the southwest monsoon in summer and the northeast monsoon in winter. The wind stress associated with these winds cause mass drift of oceanic waters leading to upwelling and downwelling. The upwelling features in the Bay of Bengal with a special mention about...

Historical bathymetry and bathymetric change in the Mississippi-Alabama coastal region, 1847-2009

Science.gov (United States)

Buster, Noreen A.; Morton, Robert A.

2011-01-01

Land loss and seafloor change around the Mississippi and Alabama (MS-AL) barrier islands are of great concern to the public and to local, state, and federal agencies. The islands provide wildlife protected areas and recreational land, and they serve as a natural first line of defense for the mainland against storm activity (index map on poster). Principal physical conditions that drive morphological seafloor and coastal change in this area include decreased sediment supply, sea-level rise, storms, and human activities (Otvos, 1970; Byrnes and others, 1991; Morton and others, 2004; Morton, 2008). Seafloor responses to the same processes can also affect the entire coastal zone. Sediment eroded from the barrier islands is entrained in the littoral system, where it is redistributed by alongshore currents. Wave and current activity is partially controlled by the profile of the seafloor, and this interdependency along with natural and anthropogenic influences has significant effects on nearshore environments. When a coastal system is altered by human activity such as dredging, as is the case of the MS-AL coastal region, the natural state and processes are altered, and alongshore sediment transport can be disrupted. As a result of deeply dredged channels, adjacent island migration is blocked, nearshore environments downdrift in the littoral system become sediment starved, and sedimentation around the channels is modified. Sediment deposition and erosion are reflected through seafloor evolution. In a rapidly changing coastal environment, understanding historically where and why changes are occurring is essential. To better assess the comprehensive dynamics of the MS-AL coastal zone, a 160-year evaluation of the bathymetry and bathymetric change of the region was conducted.

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bamberger, Judith A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-08-01

This report evaluates the physics of the upwell flow in pulse jet mixed systems in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Although the initial downward flow and radial flow from pulse jet mixers (PJMs) has been analyzed in some detail, the upwells have received considerably less attention despite having significant implications for vessel mixing. Do the upwells behave like jets? How do the upwells scale? When will the central upwell breakthrough? What proportion of the vessel is blended by the upwells themselves? Indeed, how the physics of the central upwell is affected by multiple PJMs (e.g., six in the proposed mixing vessels), non-Newtonian rheology, and significant multicomponent solids loadings remain unexplored. The central upwell must satisfy several criteria to be considered a free jet. First, it must travel for several diameters in a nearly constant direction. Second, its velocity must decay with the inverse of elevation. Third, it should have an approximately Gaussian profile. Fourth, the influence of surface or body forces must be negligible. A combination of historical data in a 12.75 ft test vessel, newly analyzed data from the 8 ft test vessel, and conservation of momentum arguments derived specifically for PJM operating conditions demonstrate that the central upwell satisfies these criteria where vigorous breakthrough is achieved. An essential feature of scaling from one vessel to the next is the requirement that the underlying physics does not change adversely. One may have confidence in scaling if (1) correlations and formulas capture the relevant physics; (2) the underlying physics does not change from the conditions under which it was developed to the conditions of interest; (3) all factors relevant to scaling have been incorporated, including flow, material, and geometric considerations; and (4) the uncertainty in the relationships is sufficiently narrow to meet required specifications. Although the central upwell

Effects of the Relaxation of Upwelling-Favorable Winds on the Diurnal and Semidiurnal Water Temperature Fluctuations in the Santa Barbara Channel, California

Science.gov (United States)

Aristizábal, María. F.; Fewings, Melanie R.; Washburn, Libe

2017-10-01

In the Santa Barbara Channel, California, and around the Northern Channel Islands, water temperature fluctuations in the diurnal and semidiurnal frequency bands are intermittent, with amplitudes that vary on time scales of days to weeks. The cause of this intermittency is not well understood. We studied the effects of the barotropic tide, vertical stratification, propagation of coastal-trapped waves, regional wind relaxations, and diurnal-band winds on the intermittency of the temperature fluctuations during 1992-2015. We used temperature data from 43 moorings in 10-200 m water depth and wind data from two buoys and one land station. Subtidal-frequency changes in vertical stratification explain 20-40% of the intermittency in diurnal and semidiurnal temperature fluctuations at time scales of days to weeks. Along the mainland north of Point Conception and at the Northern Channel Islands, the relaxation of upwelling-favorable winds substantially increases vertical stratification, accounting for up to 55% of the subtidal-frequency variability in stratification. As a result of the enhanced stratification, wind relaxations enhance the diurnal and semidiurnal temperature fluctuations at those sites, even though the diurnal-band wind forcing decreases during wind relaxation. A linear model where the background stratification is advected vertically explains a substantial fraction of the temperature fluctuations at most sites. The increase of vertical stratification and subsequent increase in diurnal and semidiurnal temperature fluctuations during wind relaxation is a mechanism that can supply nutrients to the euphotic zone and kelp forests in the Channel in summer when upwelling is weak.

Upwelling Dynamic Based on Satellite and INDESO Data in the Flores Sea

Science.gov (United States)

Kurniawan, Reski; Suriamihardja, D. A.; Hamzah Assegaf, Alimuddin

2018-03-01

Upwelling phenomenon is crucial to be forecasted, mainly concerning the information of potential fishery areas. Utilization of calibrated model for recorded upwelling such as INDESO gives benefit for historical result up to the present time. The aim of this study is to estimate areas and seasons of upwelling occurrences in the Flores Sea using data assimilation of satellite and modeling result. This study uses sea surface temperature, chlorophyll-a data from level 3 of MODIS image and sea surface height from satellite Jason-2 monthly for three years (2014-2016) and INDESO model data for sea surface temperature, sea surface height, and chlorophyll-a daily for three years (2014-2016). The upwelling is indicated by declining of sea surface temperature, sea surface height and increasing of chlorophyll-a. Verification is conducted by comparing the model result with recorded MODIS satellite image. The result shows that the area of southern Makassar Strait having occurrences of upwelling phenomenon every year starting in June, extended to July and August. The strongest upwelling occurred in 2015 covering more or less the area of 23,000 km2. The relation of monthly data of satellite has significantly correlated with daily data of INDESO model

Fish Biodiversity Patterns in Reef Communities of the Southeastern Coast of Brazil

Directory of Open Access Journals (Sweden)

Ralf Riedel

2015-10-01

Full Text Available Marine Protected Areas are increasingly becoming a tool of choice for conservation and management of marine resources and ecosystems. Data on biodiversity are necessary to assist in establishing protected areas for conservation objectives to be met. Toward that effect, we investigated reef biodiversity patterns in three large-scale coastal regions of Brazil. The study areas comprised of an upwelling region, an adjacent high impacted region, and a more distant marine park. We surveyed four reef sites in each study region. Fish species and abundance, substrate relief, and water temperature were recorded during the surveys. Biodiversity was estimated using Simpson’s and Shannon’s indices on species richness and abundance. Fish diversity was highest at the upwelling area. No difference in diversity was observed between the high impacted region and the marine park. No substrate relief patterns were found. Temperature readings showed higher frequency of low temperature episodic events at the upwelling region. Our results favor the upwelling region for establishment of a Marine Protected Area. Moreover, the similar diversity between the high impacted region and the marine park showed evidence of spillover effects from the upwelling into the high impacted region, further demonstrating the importance of the upwelling region for conservation.

Why is Coastal Community Resilience Important in the Gulf of Mexico Region?

Science.gov (United States)

The Gulf of Mexico Program supports the regional collaborative approach and efforts of the Coastal Community Resilience Priority Issue Team of the Gulf of Mexico Governors’ Alliance and its broad spectrum of partners and stakeholders.

Bleaching Susceptibility and Recovery of Colombian Caribbean Corals in Response to Water Current Exposure and Seasonal Upwelling

Science.gov (United States)

Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

2013-01-01

Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs. PMID:24282551

Counterintuitive effects of global warming-induced wind patterns on primary production in the Northern Humboldt Current System.

Science.gov (United States)

Mogollón, Rodrigo; R Calil, Paulo H

2018-04-14

It has been hypothesized that global warming will strengthen upwelling-favorable winds in the Northern Humboldt Current System (NHCS) as a consequence of the increase of the land-sea thermal gradient along the Peruvian coast. The effect of strengthened winds in this region is assessed with the use of a coupled physical-biogeochemical model forced with projected and climatological winds. Strengthened winds induce an increase in primary production of 2% per latitudinal degree from 9.5°S to 5°S. In some important coastal upwelling sites primary production is reduced. This is due to a complex balance between nutrient availability, nutrient use efficiency, as well as eddy- and wind-driven factors. Mesoscale activity induces a net offshore transport of inorganic nutrients, thus reducing primary production in the coastal upwelling region. Wind mixing, in general disadvantageous for primary producers, leads to shorter residence times in the southern and central coastal zones. Overall, instead of a proportional enhancement in primary production due to increased winds, the NHCS becomes only 5% more productive (+5 mol C m -2 year -1 ), 10% less limited by nutrients and 15% less efficient due to eddy-driven effects. It is found that regions with a initial strong nutrient limitation are more efficient in terms of nutrient assimilation which makes them more resilient in face of the acceleration of the upwelling circulation. © 2018 John Wiley & Sons Ltd.

Characteristics and environmental carrying capacities of coastal area in Yogyakarta Special Region for aquaculture

Science.gov (United States)

Triyatmo, B.; Rustadi; Priyono, S. B.

2018-03-01

The purpose of this study were to determine characteristics and environmental carrying capacities of coastal area in Yogyakarta Special Region for aquaculture. This study was conducted in 2015 by characterizing land and water dynamics, land use, and the suitability of coastal environments for aquaculture. Evaluation on the coastal environments suitability for aquaculture ponds was based on the landforms, soil properties, water quality and land. Selection of coastal locations for aquaculture development was based on the level of suitability of coastal environment. The results showed that the coastal in Kulon Progo and Bantul Regencies were characterized by sand dune and beach ridge with sandy soil texture, while in Gunungkidul Regency was characterized by limestone hill with rocky texture. Water sources of the coastal area were the sea, river, and ground water with the salinity of 31–37, 7–11, 7–31 ppt and pH of 7.4–8.4 7.0–8.2 and 7.4–9.9, respectively. The coastal lands were used for seasonal/annual planting, ponds, fish landing sites, tourism areas and conservation areas. The coastal carrying capacity was rather suitable for aquaculture, especially in the sandy soil area. Aquaculture in that area can be done intensively for shrimp (Litopenaeus vannamei), using biocrete (biological material) or plastic sheet.

Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem.

Science.gov (United States)

Santora, Jarrod A; Sydeman, William J; Schroeder, Isaac D; Field, John C; Miller, Rebecca R; Wells, Brian K

2017-03-01

Human impacts (e.g., fishing, pollution, and shipping) on pelagic ecosystems are increasing, causing concerns about stresses on marine food webs. Maintaining predator-prey relationships through protection of pelagic hotspots is crucial for conservation and management of living marine resources. Biotic components of pelagic, plankton-based, ecosystems exhibit high variability in abundance in time and space (i.e., extreme patchiness), requiring investigation of persistence of abundance across trophic levels to resolve trophic hotspots. Using a 26-yr record of indicators for primary production, secondary (zooplankton and larval fish), and tertiary (seabirds) consumers, we show distributions of trophic hotspots in the southern California Current Ecosystem result from interactions between a strong upwelling center and a productive retention zone with enhanced nutrients, which concentrate prey and predators across multiple trophic levels. Trophic hotspots also overlap with human impacts, including fisheries extraction of coastal pelagic and groundfish species, as well as intense commercial shipping traffic. Spatial overlap of trophic hotspots with fisheries and shipping increases vulnerability of the ecosystem to localized depletion of forage fish, ship strikes on marine mammals, and pollution. This study represents a critical step toward resolving pelagic areas of high conservation interest for planktonic ecosystems and may serve as a model for other ocean regions where ecosystem-based management and marine spatial planning of pelagic ecosystems is warranted. © 2016 by the Ecological Society of America.

Submesoscale CO2 variability across an upwelling front off Peru

Science.gov (United States)

Köhn, Eike E.; Thomsen, Sören; Arévalo-Martínez, Damian L.; Kanzow, Torsten

2017-12-01

As a major source for atmospheric CO2, the Peruvian upwelling region exhibits strong variability in surface fCO2 on short spatial and temporal scales. Understanding the physical processes driving the strong variability is of fundamental importance for constraining the effect of marine emissions from upwelling regions on the global CO2 budget. In this study, a frontal decay on length scales of 𝒪(10 km) was observed off the Peruvian coast following a pronounced decrease in down-frontal (equatorward) wind speed with a time lag of 9 h. Simultaneously, the sea-to-air flux of CO2 on the inshore (cold) side of the front dropped from up to 80 to 10 mmol m-2 day-1, while the offshore (warm) side of the front was constantly outgassing at a rate of 10-20 mmol m-2 day-1. Based on repeated ship transects the decay of the front was observed to occur in two phases. The first phase was characterized by a development of coherent surface temperature anomalies which gained in amplitude over 6-9 h. The second phase was characterized by a disappearance of the surface temperature front within 6 h. Submesoscale mixed-layer instabilities were present but seem too slow to completely remove the temperature gradient in this short time period. Dynamics such as a pressure-driven gravity current appear to be a likely mechanism behind the evolution of the front.

Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

Directory of Open Access Journals (Sweden)

Elisa Bayraktarov

Full Text Available Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34% compared to the exposed site (8%. Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

Science.gov (United States)

Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

2013-01-01

Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

Total and mesoscale long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic

Science.gov (United States)

Lovecchio, Elisa; Gruber, Nicolas; Münnich, Matthias; Byrne, David; Lachkar, Zouhair

2017-04-01

The ocean's biological pump is often simplified to a purely vertical process. Nevertheless, the horizontal transport of organic carbon can be substantial, especially in coastal regions such as the Canary Upwelling System (CanUS), one of the four major Eastern Boundary Upwelling Systems, characterized by high shelf productivity and an intense lateral exchange of mass and tracers with the adjacent oligotrophic waters. Despite its importance, the magnitude of this lateral flux has not yet been constrained. Here, we quantify the lateral export of organic carbon from the CanUS to the open North Atlantic using the Regional Ocean Modeling System (ROMS) coupled to a biogeochemical ecosystem module. The model is run on an Atlantic telescopic grid with a strong refinement towards the north-western African shelf, to combine an eddy-resolving resolution in the region of study with a full Atlantic basin perspective. Our results reveal that over the whole CanUS more than a third of the Net Community Production (NCP) in the nearshore 100 km is transported offshore, amounting to about 19 Tg C yr-1. The offshore transport dominates the lateral fluxes up to 1500 km into the subtropical North Atlantic, along the way adding organic carbon to the upper 100 m at rates of between 8% and 34% of the alongshore average NCP. The remineralization at depth of this extra organic carbon leads to strongly negative vertically-integrated NCP throughout the whole offshore region of the CanUS, i.e. it makes the offshore region net heterotrophic. Substantial subregional variability shapes the spatial pattern of the fluxes in the CanUS. In particular, the central subregion surrounding Cape Blanc is the most efficient in terms of collecting and laterally exporting the organic carbon, resulting in a sharp peak of watercolumn heterotrophy. A decomposition of the organic carbon fluxes into a time-mean component and a time-variable, i.e., mesoscale component reveals a large contribution of the mesoscale

High-resolution climate of the past ∼7300 years of coastal northernmost California: Results from diatoms, silicoflagellates, and pollen

Science.gov (United States)

Barron, John A.; Bukry, David; Heusser, Linda E.; Addison, Jason A.; Alexander, Clark R.

2018-01-01

Piston core TN062-O550, collected about 33 km offshore of Eureka, California, contains a high-resolution record of the climate and oceanography of coastal northernmost California during the past ∼7.34 kyr. Chronology established by nine AMS ages on a combination of planktic foraminifers, bivalve shell fragments, and wood yields a mean sedimentation rate of 103 cm kyr−1. Marine proxies (diatoms and silicoflagellates) and pollen transported by the nearby Eel River reveal a stepwise development of both modern offshore surface water oceanography and coastal arboreal ecosystems. Beginning at ∼5.4 cal ka the relative abundance of coastal redwood pollen, a proxy for coastal fog, displays a two fold increase suggesting enhanced coastal upwelling. A decline in the relative contribution of subtropical diatoms at ∼5.0 cal ka implies cooling of sea surface temperatures (SSTs). At ∼3.6 cal ka an increase in the relative abundance of alder and oak at the expense of coastal redwood likely signals intensified riverine transport of pollen from inland environments. Cooler offshore SSTs and increased precipitation characterize the interval between ∼3.6 and 2.8 cal ka. A rapid, stepwise change in coastal climatology and oceanography occurs between ∼2.8 and 2.6 cal ka that suggests an enhanced expression of modern Pacific Decadal Oscillation-like (PDO) cycles. A three-fold increase in the relative abundance of the subtropical diatom Fragilariopsis doliolus at 2.8 cal ka appears to mark an abrupt warming of winter SSTs. Soon afterwards at 2.6 cal ka, a two fold increase in the relative abundance of coastal redwood pollen is suggestive of an abrupt intensification of spring upwelling. After ∼2.8 cal ka a sequence of cool-warm, PDO-like cycles occurs wherein cool cycles are characterized by relative abundance increases in coastal redwood pollen and decreased contributions of subtropical diatoms, whereas opposite proxy trends distinguish warm cycles.

Near-coastal ocean variability off southern Tamaulipas - northern Veracruz, western Gulf of Mexico, during spring-summer 2013

Science.gov (United States)

Rivas, David

2016-04-01

Six months of observations from a near-coastal mooring deployed off southern Tamaulipas-northern Veracruz coast (western Gulf of Mexico) during spring-summer 2013 provides velocity, temperature, salinity, sea level, and dissolved oxygen series in a region which ocean dynamics is still poorly understood. As shown in a preceding analysis of this region's winter circulation for winter 2012-2013, coastal trapped motions associated with the regional invasion of synoptic cold fronts modulate the local variability; this pattern remains in the spring 2013, when even more intense events of alongshore flow (>50 cm/s) are observed. This intensified flow is associated with a significant decrease in the dissolved oxygen, most probably related to an influence of hypoxic waters coming from the northern Gulf. In late spring-mid summer, the wind pattern corresponds to persistent southeasterly winds that favor the occurrence of a local upwelling, which maintains a local thermal reduction (>3 degrees Celsius) and is associated with a persistent northward flow (>30 cm/s). The late summer was characterized by a significant tropical-cyclone activity, when a depression, a storm, and a hurricane affected the western Gulf. These tropical systems caused an intense precipitation and hence an important intensification of the local riverine discharge, and the winds enhanced the mixing of such riverine waters, via mostly kinetic stirring and Ekman pumping.

An upwelling-induced retention area off Senegal: A mechanism to ...

African Journals Online (AJOL)

Chlorophyll distribution peaks nearshore. This unique surface structure is interpreted as the result of a “double cell” structure in the upwelling vertical circulation: a first cell located at the shelf break, the main upwelling cell that brings cold and nutrient-rich subsurface water to the surface, and a second cell located inshore of ...

Mesozooplankton respiration and community structure in a seamount region of the eastern South Pacific

Science.gov (United States)

Frederick, Leissing; Escribano, Ruben; Morales, Carmen E.; Hormazabal, Samuel; Medellín-Mora, Johanna

2018-05-01

Seamounts in the Juan Fernandez Ridge, as well as in other seamount regions in the eastern South Pacific and in the world oceans, remain poorly studied ecosystems in terms of structure and functioning. Here, community respiration by epipelagic mesozooplankton in three seamounts of the Juan Fernandez Ridge, including the O`Higgins Seamount close to the coastal upwelling zone and two oceanic seamounts near the Juan Fernandez Archipelago ( 33°S-78°W), was assessed. Oxygen consumption by mixed assemblages was estimated using continuous measurements of dissolved oxygen concentration under controlled temperature during onboard, short-term incubations (2-4 h). Mesozooplankton composition was analyzed with a ZooScan device and expressed in terms of community normalized size spectra, and taxa and size diversity (Shannon-Wiener index). Carbon-specific community respiration rates in the upper 100 m layer were in the range of 0.3-1.9 mg O2 m-2 d-1, indicating that up to 3.1% of the mesozooplankton biomass can be respired on a daily basis. The mesozooplankton community was dominated by small-size copepods but the proportions of small copepods, large copepods, and gelatinous zooplankton (mostly salps) changed between the seamounts, in association with modifications in taxa composition, size diversity, and the slope of the size spectrum. Community respiration was significantly correlated to these community descriptors, suggesting the composition of the pelagic community has a direct impact on the total amount of respired-C. Connectivity between the coastal upwelling zone and the Juan Fernandez Ridge region mediated by mesoscale activity, interacting with the seamounts, is suggested as a most important process in controlling zooplankton community structure and in turn community metabolism.

Development of a Florida Coastal Mapping Program Through Local and Regional Coordination

Science.gov (United States)

Hapke, C. J.; Kramer, P. A.; Fetherston-Resch, E.; Baumstark, R.

2017-12-01

The State of Florida has the longest coastline in the contiguous United States (2,170 km). The coastal zone is heavily populated and contains 1,900 km of sandy beaches that support economically important recreation and tourism. Florida's waters also host important marine mineral resources, unique ecosystems, and the largest number of recreational boats and saltwater fishermen in the country. There is increasing need and demand for high resolution data of the coast and adjacent seafloor for resource and habitat mapping, understanding coastal vulnerability, evaluating performance of restoration projects, and many other coastal and marine spatial planning efforts. The Florida Coastal Mapping Program (FCMP), initiated in 2017 as a regional collaboration between four federal and three state agencies, has goals of establishing the priorities for high resolution seafloor mapping of Florida's coastal environment, and developing a strategy for leveraging funds to support mapping priorities set by stakeholders. We began by creating a comprehensive digital inventory of existing data (collected by government, the private sector, and academia) from 1 kilometer inland to the 200 meter isobath for a statewide geospatial database and gap analysis. Data types include coastal topography, bathymetry, and acoustic data such as sidescan sonar and subbottom profiles. Next, we will develop appropriate proposals and legislative budget requests in response to opportunities to collect priority data in high priority areas. Data collection will be undertaken by a combination of state and federal agencies. The FCMP effort will provide the critical baseline information that is required for characterizing changes to fragile ecosystems, assessing marine resources, and forecasting the impacts on coastal infrastructure and recreational beaches from future storms and sea-level rise.

Environmental proteomics of microbial plankton in a highly productive coastal upwelling system

Energy Technology Data Exchange (ETDEWEB)

Sowell, Sarah [Oregon State University, Corvallis; Abraham, Paul E [ORNL; Shah, Manesh B [ORNL; Verberkmoes, Nathan C [ORNL; Smith, Daniel [Oregon State University, Corvallis; Barofsky, Douglas [Oregon State University, Corvallis; Giovannoni, Stephen [Oregon State University, Corvallis

2011-01-01

Metaproteomics is one of a suite of new approaches providing insights into the activities of microorganisms in natural environments. Proteins, the final products of gene expression, indicate cellular priorities, taking into account both transcriptional and posttranscriptional control mechanisms that control adaptive responses. Here, we report the proteomic composition of the o 1.2 lm fraction of a microbial community from Oregon coast summer surface waters, detected with two-dimensional liquid chromatography coupled with electrospray tandem mass spectrometry. Spectra corresponding to proteins involved in protein folding and biosynthesis, transport, and viral capsid structure were the most frequently detected. A total of 36% of all the detected proteins were best matches to the SAR11 clade, and other abundant coastal microbial clades were also well represented, including the Roseobacter clade (17%), oligotrophic marine gammaproteobacteria group (6%), OM43 clade (1%). Viral origins were attributed to 2.5% of proteins. In contrast to oligotrophic waters, phosphate transporters were not highly detected in this nutrient-rich system. However, transporters for amino acids, taurine, polyamines and glutamine synthetase were among the most highly detected proteins, supporting predictions that carbon and nitrogen are more limiting than phosphate in this environment. Intriguingly, one of the highly detected proteins was methanol dehydrogenase originating from the OM43 clade, providing further support for recent reports that the metabolism of one-carbon compounds by these streamlined methylotrophs might be an important feature of coastal ocean biogeochemistry.

Trends of coastal and oceanic ST along the Western Iberian Peninsula over the period 1975- 2006.

Science.gov (United States)

Santos, F.; Gómez-Gesteira, M.; deCastro, M.; Álvarez, I.; Sousa, M. C.

2012-04-01

Temperature is observed to have different trends at coastal and oceanic locations along the western Iberian Peninsula (from 43.25oN to 37.25oN and from 9.75°W to 14.75°W) from 1975 to 2006. This period corresponds with the last warming period in the area under study. The analysis was carried out by means of the Simple Ocean Data Assimilation (SODA) package. Reanalysis of ocean climate variability are available at monthly scale with a horizontal resolution of 0.5o- 0.5o and a vertical resolution of 40 levels which allows us to obtain information beneath the sea surface levels (http://www.atmos.umd.edu/~ocean/). Only the first 21 vertical levels (from 5.0 m to 729.35 m) were considered since the most important changes in the heat content observed in the world ocean during the last decades, correspond to the upper 700m (Levitus et al., 2009). Warming was observed to be considerably higher at ocean locations than at coastal ones at the same latitude. This behavior is observed throughout the water column. Ocean warming ranged from values on the order of 0.3 °C dec-1 near surface to 0.1 °C dec-1 at 500 m depth. On the contrary, the coastal warming is much smaller, reaching values close to 0.2 °C dec-1 near surface and decreasing rapidly at values below 0.1 °C dec-1 for depths on the order of 50 m. Actually, coastal warming is practically negligible under 50 m. The different warming rates near coast and at ocean locations have been previously described for SST by the authors (Santos et al, 2011, 2012). The weaker coastal warming compared with the ocean warming at the same latitude was related to the presence of coastal upwelling. Coastal upwelling is the most importing forcing mechanism in the western coast of the Iberian Peninsula pumping cold water from below to near surface layers. In this sense, the heat diffusion from the atmosphere is constrained to near surface area by advection, which mixes deeper colder water with warmer surface water. The heat content

Abrupt environmental shift associated with changes in the ...

African Journals Online (AJOL)

In addition, signals, coherent with the 1996 shift recorded in sea surface temperatures, were also found in atmospheric surface pressure and zonal wind data for that region; interannual coastal SST variability is also shown to be correlated with zonal wind-stress forcing. As a result, increased wind-induced coastal upwelling ...

Evaluation of Tsunami Run-Up on Coastal Areas at Regional Scale

Science.gov (United States)

González, M.; Aniel-Quiroga, Í.; Gutiérrez, O.

2017-12-01

Tsunami hazard assessment is tackled by means of numerical simulations, giving as a result, the areas flooded by tsunami wave inland. To get this, some input data is required, i.e., the high resolution topobathymetry of the study area, the earthquake focal mechanism parameters, etc. The computational cost of these kinds of simulations are still excessive. An important restriction for the elaboration of large scale maps at National or regional scale is the reconstruction of high resolution topobathymetry on the coastal zone. An alternative and traditional method consists of the application of empirical-analytical formulations to calculate run-up at several coastal profiles (i.e. Synolakis, 1987), combined with numerical simulations offshore without including coastal inundation. In this case, the numerical simulations are faster but some limitations are added as the coastal bathymetric profiles are very simply idealized. In this work, we present a complementary methodology based on a hybrid numerical model, formed by 2 models that were coupled ad hoc for this work: a non-linear shallow water equations model (NLSWE) for the offshore part of the propagation and a Volume of Fluid model (VOF) for the areas near the coast and inland, applying each numerical scheme where they better reproduce the tsunami wave. The run-up of a tsunami scenario is obtained by applying the coupled model to an ad-hoc numerical flume. To design this methodology, hundreds of worldwide topobathymetric profiles have been parameterized, using 5 parameters (2 depths and 3 slopes). In addition, tsunami waves have been also parameterized by their height and period. As an application of the numerical flume methodology, the coastal parameterized profiles and tsunami waves have been combined to build a populated database of run-up calculations. The combination was tackled by means of numerical simulations in the numerical flume The result is a tsunami run-up database that considers real profiles shape

Phytoplankton dynamics in relation to seasonal variability and upwelling and relaxation patterns at the mouth of Ria de Aveiro (West Iberian Margin over a four-year period.

Directory of Open Access Journals (Sweden)

Tânia Vidal

Full Text Available From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin. We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceanographic regime, namely changes in frequency and intensity of upwelling events, over the dynamics of the phytoplankton assemblage. The samples were consistently handled and a final subset of 136 OTUs (taxa with relative abundance > 0.01% was subsequently submitted to various multivariate analyses. The phytoplankton assemblage showed significant changes at all temporal scales but with an overriding importance of seasonality over longer- (inter-annual or shorter-term fluctuations (upwelling-related. Sea-surface temperature, salinity and maximum upwelling index were retrieved as the main driver of seasonal change. Seasonal signal was most evident in the fluctuations of chlorophyll a concentration and in the high turnover from the winter to spring phytoplankton assemblage. The seasonal cycle of production and succession was disturbed by upwelling events known to disrupt thermal stratification and induce changes in the phytoplankton assemblage. Our results indicate that both the frequency and intensity of physical forcing were important drivers of such variability, but the outcome in terms of species composition was highly dependent on the available local pool of species and the timing of those events in relation to the seasonal cycle. We conclude that duration, frequency and intensity of upwelling events, which vary seasonally and inter-annually, are paramount for maintaining long-term phytoplankton diversity likely by allowing unstable coexistence and incorporating species turnover at different scales. Our results contribute to the understanding of the complex mechanisms of coastal phytoplankton dynamics in

Sr/Ca and Mg/Ca in Glycymeris glycymeris (Bivalvia) shells from the Iberian upwelling system: Ontogeny and environmental control

Science.gov (United States)

Freitas, Pedro; Richardson, Christopher; Chenery, Simon; Monteiro, Carlos; Butler, Paul; Reynolds, David; Scourse, James; Gaspar, Miguel

2017-04-01

Bivalve shells have a great potential as high-resolution geochemical proxy archives of marine environmental conditions. In addition, sclerochronology of long-lived bivalve species (e.g. Arctica islandica) provides a timeline of absolutely dated shell material for geochemical analysis that can extend into the past beyond the lifetime of single individuals through the use of replicated crossmatched centennial to millennial chronologies. However, the interpretation of such records remains extremely challenging and complex, with multiple environmental and biological processes affecting element incorporation in the shell (e.g. crystal fabrics, organic matrix, biomineralization mechanisms and physiological processes). As a result, the effective use of bivalve shell elemental/Ca ratios as palaeoenvironmental proxies has been limited, often to species-specific applications or applications restricted to particular environmental settings. The dog-cockle, Glycymeris glycymeris, is a relatively long-lived bivalve (up to 200 years) that occurs in coarse-grained subtidal sediments of coastal shelf seas of Europe and North West Africa. Glycymeris glycymeris shells provide a valuable, albeit not fully explored, archive to reconstruct past environmental variability in an area lacking sclerochronological studies due to the rarity of long-lived bivalves and lack of coral reefs. In this study, we evaluate the potential of Sr/Ca and Mg/Ca ratios in G. glycymeris shells as geochemical proxies of upwelling conditions in the Iberian Upwelling System, the northern section of the Canary Current Eastern Boundary Upwelling System. Sr/Ca and Mg/Ca generally co-varied significantly and a clear ontogenetic, non-environmental related change in Sr/Ca and Ba/Ca variability was observed. High Sr/Ca and Mg/Ca ratios in older shells (> 10 years old) were found to be associated with the occurrence of growth lines deposited during the winter reduction in shell growth. Nevertheless, Sr/Ca and Mg

Preliminary survey of the coastal region between Peruibe and Iguape: plankton and hydrography

International Nuclear Information System (INIS)

Pereira, D.N.; Tommasi, L.R.; Sao Paulo Univ.

1984-01-01

In October 1980 a preliminary survey of the coastal region, between Peruibe and Iguape (Sao Paulo State, Brazil) was carried out in order to gather basic oceanographic data on the region where nuclear power plants are going to be built. Data on temperature, salinity, currents, dissolved oxygen, nitrogen, phosphorus, phytoplankton, chlorophyll-a and zooplankton are presented and discussed. (Author) [pt

Basic concepts in oceanography

International Nuclear Information System (INIS)

Small, L.F.

1997-01-01

Basic concepts in oceanography include major wind patterns that drive ocean currents, and the effects that the earth's rotation, positions of land masses, and temperature and salinity have on oceanic circulation and hence global distribution of radioactivity. Special attention is given to coastal and near-coastal processes such as upwelling, tidal effects, and small-scale processes, as radionuclide distributions are currently most associated with coastal regions. (author)

Geochemistry and magnetic sediment distribution at the western boundary upwelling system of southwest Atlantic

Science.gov (United States)

Cruz, Anna P. S.; Barbosa, Catia F.; Ayres-Neto, Arthur; Munayco, Pablo; Scorzelli, Rosa B.; Amorim, Nívea Santos; Albuquerque, Ana L. S.; Seoane, José C. S.

2018-02-01

In order to investigate the chemical and magnetic characteristics of sediments of the western boundary upwelling system of Southwest Atlantic we analyzed magnetic susceptibility, grain size distribution, total organic carbon, heavy mineral abundance, Fe associated with Mössbauer spectra, and Fe and Mn of pore water to evaluate the deposition patterns of sediments. Four box-cores were collected along a cross-shelf transect. Brazil Current and coastal plume exert a primary control at the inner and outer shelf cores, which exhibited similar depositional patterns characterized by a high abundance of heavy minerals (mean 0.21% and 0.08%, respectively) and very fine sand, whereas middle shelf cores presented low abundances of heavy minerals (mean 0.03%) and medium silt. The inner shelf was dominated by sub-angular grains, while in middle and outer shelf cores well-rounded grains were found. The increasing Fe3+:Fe2+ ratio from the inner to the outer shelf reflects farther distance to the sediment source. The outer shelf presented well-rounded minerals, indicating abrasive processes as a result of transport by the Brazil Current from the source areas. In the middle shelf, cold-water intrusion of the South Atlantic Central Water contributes to the primary productivity, resulting in higher deposition of fine sediment and organic carbon accumulation. The high input of organic carbon and the decreased grain size are indicative of changes in the hydrodynamics and primary productivity fueled by the western boundary upwelling system, which promotes loss of magnetization due to the induction of diagenesis of iron oxide minerals.

Benefits of coastal recreation in Europe: identifying trade-offs and priority regions for sustainable management.

Science.gov (United States)

Ghermandi, Andrea

2015-04-01

This paper examines the welfare dimension of the recreational services of coastal ecosystems through the application of a meta-analytical value transfer framework, which integrates Geographic Information Systems (GIS) for the characterization of climate, biodiversity, accessibility, and anthropogenic pressure in each of 368 regions of the European coastal zone. The relative contribution of international, domestic, and local recreationists to aggregated regional values is examined. The implications of the analysis for prioritization of conservation areas and identification of good management practices are highlighted through the comparative assessment of estimated recreation values, current environmental pressures, and existing network of protected sites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Episodic Upwelling of Zooplankton within a Bowhead Whale Feeding Area Near Barrow, AK

Science.gov (United States)

2013-09-30

recorders. 4. Determine the correlations between exchange events and wind speed and direction , wind duration, ice cover, shelf water column...sample over longer time periods in that region in order to better describe the impact of the strength and magnitude of the wind on upwelling along the...oceanography of the shelf is complex, dynamic, and highly variable and that advection is closely coupled to the direction and magnitude of the winds . In

Ecosystem services provided by a complex coastal region: challenges of classification and mapping

Science.gov (United States)

Sousa, Lisa P.; Sousa, Ana I.; Alves, Fátima L.; Lillebø, Ana I.

2016-03-01

A variety of ecosystem services classification systems and mapping approaches are available in the scientific and technical literature, which needs to be selected and adapted when applied to complex territories (e.g. in the interface between water and land, estuary and sea). This paper provides a framework for addressing ecosystem services in complex coastal regions. The roadmap comprises the definition of the exact geographic boundaries of the study area; the use of CICES (Common International Classification of Ecosystem Services) for ecosystem services identification and classification; and the definition of qualitative indicators that will serve as basis to map the ecosystem services. Due to its complexity, the Ria de Aveiro coastal region was selected as case study, presenting an opportunity to explore the application of such approaches at a regional scale. The main challenges of implementing the proposed roadmap, together with its advantages are discussed in this research. The results highlight the importance of considering both the connectivity of natural systems and the complexity of the governance framework; the flexibility and robustness, but also the challenges when applying CICES at regional scale; and the challenges regarding ecosystem services mapping.

Ecosystem services provided by a complex coastal region: challenges of classification and mapping.

Science.gov (United States)

Sousa, Lisa P; Sousa, Ana I; Alves, Fátima L; Lillebø, Ana I

2016-03-11

A variety of ecosystem services classification systems and mapping approaches are available in the scientific and technical literature, which needs to be selected and adapted when applied to complex territories (e.g. in the interface between water and land, estuary and sea). This paper provides a framework for addressing ecosystem services in complex coastal regions. The roadmap comprises the definition of the exact geographic boundaries of the study area; the use of CICES (Common International Classification of Ecosystem Services) for ecosystem services identification and classification; and the definition of qualitative indicators that will serve as basis to map the ecosystem services. Due to its complexity, the Ria de Aveiro coastal region was selected as case study, presenting an opportunity to explore the application of such approaches at a regional scale. The main challenges of implementing the proposed roadmap, together with its advantages are discussed in this research. The results highlight the importance of considering both the connectivity of natural systems and the complexity of the governance framework; the flexibility and robustness, but also the challenges when applying CICES at regional scale; and the challenges regarding ecosystem services mapping.

Coastal currents and mass transport of surface sediments over the shelf regions of Monterey Bay, California

Science.gov (United States)

Wolf, S.C.

1970-01-01

In Monterey Bay, the highest concentrations of medium and fine sands occur nearshore between ten and thirty fathoms. Silt and clay accumulate in greater depths. Contours of median diameter roughly parallel the isobaths. Fine-grained materials are supplied to the bay region from erosion of cliffs which partly surround Monterey Bay, from sediment laden river discharge, and from continual reworking of widespread Pleistocene and Recent sea floor sediments. These sediments in turn are picked up by coastal currents and distributed over the shelf regions by present day current regimes. Studies of bottom currents over the shelf regions and in Monterey Canyon have revealed patterns which vary with seasonal changes. Current patterns during August and September exhibit remarkable symmetry about the axis of Monterey Submarine Canyon. Central Shelf currents north and south of Monterey Canyon flowed northwest at an average rate of 0.2 knots and south at 0.3 knots respectively. On the North Shelf between January and March currents flowed east to southeast at 0.3-0.5 knots with mirror image patterns above the South Shelf during the same period. Irregular current flow in the canyon indicates a complex current structure with frequent shifts in counterclockwise and clockwise direction over very short periods of time. Bottom topography of the canyon complex often causes localization of canyon currents. One particular observation at a depth of 51 fathoms indicated up-canyon flow at a rate of 0.2 knots. Most of the observed currents are related to seasonal variations, upwelling, ocean swell patterns, and to changes in the California and Davidson currents. Changes in current regimes are reflected in the patterns of sediment distribution and transport. Sediment transport is chiefly parallel to the isobaths, particularly on the North and South Shelf regions. Complex dispersal patterns are observed near Monterey Canyon and Moss Landing Harbor jetties. Longshore currents move sediments

Osmotically driven membrane process for the management of urban runoff in coastal regions

KAUST Repository

Li, Zhenyu; Valladares Linares, Rodrigo; Abu-Ghdaib, Muhannad; Zhan, Tong; Yangali-Quintanilla, Victor; Amy, Gary L.

2014-01-01

An osmotic detention pond was proposed for the management of urban runoff in coastal regions. Forward osmosis was employed as a bridge to utilize natural osmotic energy from seawater for concentrating and reusing urban runoff water, and as a barrier

Surface mixing and biological activity in the four Eastern Boundary Upwelling Systems

Directory of Open Access Journals (Sweden)

V. Rossi

2009-08-01

Full Text Available Eastern Boundary Upwelling Systems (EBUS are characterized by a high productivity of plankton associated with large commercial fisheries, thus playing key biological and socio-economical roles. Since they are populated by several physical oceanic structures such as filaments and eddies, which interact with the biological processes, it is a major challenge to study this sub- and mesoscale activity in connection with the chlorophyll distribution. The aim of this work is to make a comparative study of these four upwelling systems focussing on their surface stirring, using the Finite Size Lyapunov Exponents (FSLEs, and their biological activity, based on satellite data. First, the spatial distribution of horizontal mixing is analysed from time averages and from probability density functions of FSLEs, which allow us to divide each areas in two different subsystems. Then we studied the temporal variability of surface stirring focussing on the annual and seasonal cycle. We also proposed a ranking of the four EBUS based on the averaged mixing intensity. When investigating the links with chlorophyll concentration, the previous subsystems reveal distinct biological signatures. There is a global negative correlation between surface horizontal mixing and chlorophyll standing stocks over the four areas. To try to better understand this inverse relationship, we consider the vertical dimension by looking at the Ekman-transport and vertical velocities. We suggest the possibility of a changing response of the phytoplankton to sub/mesoscale turbulence, from a negative effect in the very productive coastal areas to a positive one in the open ocean. This study provides new insights for the understanding of the variable biological productivity in the ocean, which results from both dynamics of the marine ecosystem and of the 3-D turbulent medium.

Influence of monsoon upwelling on the planktonic foraminifera off Oman during Late Quaternary

Digital Repository Service at National Institute of Oceanography (India)

Naidu, P.D.

Planktonic foraminifer abundances, fluxes, test sizes, and coiling properties are influenced in various ways by the southwest monsoon winds and associated upwelling in the western Arabian Sea. The influence of monsoon driven upwelling...

Intensive aggregate formation with low vertical flux during an upwelling-induced diatom bloom

DEFF Research Database (Denmark)

Kiørboe, Thomas; Tiselius, P.; Mitchell-Innes, B.

1998-01-01

of turbulent shear in the ocean such stickiness coefficients predict very high specific coagulation rates (0.3 d(-1)). In situ video observation demonstrated the occurrence of abundant diatom aggregates with surface water concentrations between 1,000 and 3,000 ppm. Despite the very high concentration......The surfaces of most pelagic diatoms are sticky at times and may therefore form rapidly settling aggregates by physical coagulation. Stickiness and aggregate formation may be particularly adaptive in upwelling systems by allowing the retention of diatom populations in the vicinity of the upwelling...... center. We therefore hypothesized that upwelling diatom blooms are terminated by aggregate formation and rapid sedimentation. We monitored the development of a maturing diatom (mainly Chaetoceros spp.) bloom in the Benguela upwelling current during 7 d in February. Chlorophyll concentrations remained...

Characteristics of the Norwegian Coastal Current during Years with High Recruitment of Norwegian Spring Spawning Herring (Clupea harengus L..

Directory of Open Access Journals (Sweden)

Øystein Skagseth

Full Text Available Norwegian Spring Spawning herring (NSSH Clupea harengus L. spawn on coastal banks along the west coast of Norway. The larvae are generally transported northward in the Norwegian Coastal Current (NCC with many individuals utilizing nursery grounds in the Barents Sea. The recruitment to this stock is highly variable with a few years having exceptionally good recruitment. The principal causes of recruitment variability of this herring population have been elusive. Here we undertake an event analysis using data between 1948 and 2010 to gain insight into the physical conditions in the NCC that coincide with years of high recruitment. In contrast to a typical year when northerly upwelling winds are prominent during spring, the years with high recruitment coincide with predominantly southwesterly winds and weak upwelling in spring and summer, which lead to an enhanced northward coastal current during the larval drift period. Also in most peak recruitment years, low-salinity anomalies are observed to propagate northward during the spring and summer. It is suggested that consistent southwesterly (downwelling winds and propagating low-salinity anomalies, both leading to an enhanced northward transport of larvae, are important factors for elevated recruitment. At the same time, these conditions stabilize the coastal waters, possibly leading to enhanced production and improved feeding potential along the drift route to Barents Sea. Further studies on the drivers of early life history mortality can now be undertaken with a better understanding of the physical conditions that prevail during years when elevated recruitment occurs in this herring stock.

Radon as an indicator of submarine groundwater discharge in coastal regions

International Nuclear Information System (INIS)

Jacob, Noble; Shivanna, K.; Suresh Babu, D.S.

2009-01-01

This article reviews the various available methodologies to estimate submarine groundwater discharge (SGD) and demonstrates the utility of radon with a case study. An attempt has been made to identify the existence of submarine groundwater discharge (SGD) and semi-quantitatively estimate its rate in the coastal area of Vizhinjam, Thiruvananthapuram, Kerala. Natural 222 Rn (half-life = 3.8 days) was used as a tracer of SGD because of its conservative nature, short half-life, easiness in measurement and high abundance in groundwater. As in situ radon ( 222 Rn) monitoring study conducted in this region indicated comparatively higher 222 Rn activities (average 14.1±1.7 Bq/m 3 ) in the coastal waters revealing significant submarine groundwater discharge. The SGD may be a combination of fresh groundwater and recirculated seawater that is controlled by the hydraulic gradient in the adjacent aquifer and varying tidal conditions in the coastal waters. Using a transient 222 Rn mass balance model for the coastal waters, SGD rates were computed and the average value was found to be 10.9±6.1 cm/day. These estimates are comparable with those reported in the literature. In general, identification and estimation of submarine groundwater discharge is important in the Indian context because of the possibility of large amounts of groundwater loss through its long coastline, that can be judiciously exploited to cater to the present water requirements for drinking and irrigation purposes. (author)

Ocean Acidification of the coastal waters of the Pacific Northwest: A modeling study

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Siedlecki, S. A.; Hermann, A. J.; Bond, N. A.; Alin, S. R.; Feely, R. A.; Hales, B. R.; Newton, J.; Migliaccio, L.

2013-12-01

A regional oxygen model of the Washington and Oregon shelves (Siedlecki, S.A., Banas, N., Davis, K.A., Giddings, S., P. MacCready, Connolly, T., & B. Hickey. Seasonal Oxygen variability on the continental shelves of Washington and Oregon, in prep) is combined with the empirical relationships between the carbonate system, oxygen and temperature (Alin et al, in prep) to simulate the carbonate chemistry in this region. A model hindcast for 2009 is compared to local observations of oxygen, and aragonite saturation. The model is able to reproduce the seasonal change in oxygen observed on the Oregon shelf. Challenges of this approach are discussed. The volume of hypoxic and undersaturated water increases over the upwelling season, occupying more of the water column later in the upwelling season. This results in increasingly stressful conditions over most of the water column for biota on the shelf as the upwelling season progresses. How the rate of ascension and presence of this undersaturated water varies regionally will be discussed.

Assessing the Feasibility and Risks of Using Wave-Driven Upwelling Pumps to Enhance the Biological Sequestration of Carbon in Open Oceans

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White, A.; Bjorkman, K.; Grabowski, E.; Letelier, R. M.; Poulos, S.; Watkins, B.; Karl, D. M.

2008-12-01

In 1976, John D. Isaacs proposed to use wave energy to pump cold and nutrient-rich deep water into the sunlit surface layers. The motivation for this endeavor has taken many forms over the years, from energy production to fueling aquaculture to the more recent suggestion that artificial upwelling could be used to stimulate primary productivity and anthropogenic carbon sequestration in oligotrophic regions of the ocean. However, the potential for biological carbon sequestration in response to upwelling will depend on the concentration of nutrients relative to that of dissolved inorganic carbon in the water being upwelled and on the response of the marine microbial assemblage to this nutrient enrichment. In June 2008, we tested a commercially available wave pump in the vicinity of Station ALOHA, north of Oahu, Hawaii in order to assess the logistics of at-sea deployment and the survivability of the equipment in the open ocean. Our engineering test was also designed to evaluate a recently published hypothesis (Karl and Letelier, 2008, Marine Ecology Progress Series) that upwelling of water containing excess phosphate relative to nitrogen compared to the canonical "Redfield" molar ratio of 16N:1P, would generate a two-phased phytoplankton bloom and enhance carbon sequestration. In this presentation, we analyze the results of this field test within the context of pelagic biogeochemical cycles. Furthermore, we discuss the deployment of a 300m wave pump, efforts to sample a biochemical response, the engineering challenges faced and the practical and ethical implications of these results for future experiments aimed at stimulating the growth of phytoplankton in oligotrophic regions.

Nitrospina-like bacteria are the main drivers of nitrite oxidation in the seasonal upwelling area of the Eastern South Pacific (Central Chile ∼36°S).

Science.gov (United States)

Levipan, Héctor A; Molina, Verónica; Fernandez, Camila

2014-12-01

Aerobic nitrite oxidation in marine environments plays a key role in the nitrification process. Marine bacteria involved in this nitrate-producing process have however been seldom studied compared with the ammonia-oxidizing community. Here, we report for the first time the community structure of aerobic nitrite-oxidizing bacteria (NOB) in the seasonal upwelling and oxygen-deficient area off Central Chile. Analysis of 16S rRNA by tag pyrosequencing was combined with specific quantitative polymerase chain reaction (qPCR) and reverse transcription qPCR in summer and wintertime. Nitrospina-like bacteria were the only known NOB detected by means of pyrosequencing between 30 and 80 m depth, accounting for up to 5% of total bacteria. This guild was represented by 11 and 7 operational taxonomic units (97% cut-off) in winter and summertime respectively. Nitrospina-like bacteria were phylogenetically related to sequences retrieved from coastal upwelling, oxygen minimum zones and deep-sea environments. This group was also detected by qPCR with abundances that increased with depth throughout the water column. Importantly, Nitrospina from surface layers showed low abundances but high 16S rRNA : rDNA ratios and mainly in summertime. Overall, our results highlight the seasonal variability between the structure and physiological state of this community and suggest a significant role of Nitrospina in the nitrogen cycle of seasonal upwelling areas.

Environmental hazards for pipelines in coastal regions/shore approaches

International Nuclear Information System (INIS)

Jinsi, B.K.

1995-01-01

Often oil/gas and other hydrocarbons discovered and produced offshore are transported to onshore facilities via submarine pipelines. The route of such pipelines traverses through coastal/shore approach regions. For a rational/economic design, safe installation and subsequent operation it is of utmost importance to review, evaluate and finalize various environmental hazard such as winds, waves, currents, seabed topography, seabed and sub-bottom soils, seabed erosion and soil accretion. This paper addresses the above described environmental hazards, their assessment and techniques to prepare design parameters which must be used for stability analysis, installation methods, long term operation and maintenance for the shore approaches. Additionally, various proven pipeline installation and stabilization techniques for the shore approach region are detailed. As case histories, three approaches installed in the Dutch North Sea are described

Physical trajectory profile data from glider ru22 deployed by Rutgers, the State University of New Jersey in the Coastal Waters of California from 2014-08-04 to 2014-08-22 (NCEI Accession 0138014)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The project is a comprehensive observational and analytical program to examine the dynamics and source waters of the relaxation flows in a coastal upwelling system...

Physical trajectory profile data from glider ru22 deployed by Rutgers, the State University of New Jersey in the Coastal Waters of California from 2014-08-25 to 2014-09-23 (NCEI Accession 0138015)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The project is a comprehensive observational and analytical program to examine the dynamics and source waters of the relaxation flows in a coastal upwelling system...

Development of upwelling on pathway and freshwater transport of Pearl River plume in northeastern South China Sea

Science.gov (United States)

Chen, Zhaoyun; Jiang, Yuwu; Liu, James T.; Gong, Wenping

2017-08-01

In situ observations, satellite images, and numerical modeling results have shown that the Pearl River plume axis extends alongshore and passes through two separate upwelling regions—one off the Guangdong and Fujian coasts (the Yuedong upwelling) and the other in the Taiwan Bank during the initial and medium stages of the Yuedong upwelling, while it is directed offshore when the Yuedong upwelling is strong. Model experiments are conducted to examine the effects of wind strength and baroclinicity on the upwelling and the corresponding pathway and freshwater transport of the Pearl River plume. The baroclinic effect is important to intensifying the horizontal velocity at the upwelling front and freshwater transport in the northeastern South China Sea. The freshwater transport flux is further decomposed into advection, vertical shear, and tidal pumping components, and advection is the dominant contributor. As the Yuedong upwelling develops, the zone with a relatively high-pressure gradient moves offshore due to offshore Ekman transport and the shift in the upwelling front, which is responsible for the offshore transport of the river plume. When the river plume is transported to the outer-shelf, sometimes it can be further entrained into eddies, allowing its export to the open sea.

Water masses and mesoscale control on latitudinal and cross-shelf variations in larval fish assemblages off NW Africa

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Olivar, M. Pilar; Sabatés, Ana; Pastor, Maria V.; Pelegrí, Josep L.

2016-11-01

We explore the associations between larval fish assemblages and oceanographic conditions in the upper ocean (top 200 m) along the African slope, from tropical (15°N) to subtropical (35°N) latitudes, during a period of intense upwelling. In this extensive region, the northward Mauritanian Current and Poleward Undercurrent carry South Atlantic Central Waters (SACW) while the southward Canary Upwelling Current transports North Atlantic Central Waters (NACW). South of Cape Blanc we only find SACW, and north of Cape Blanc there is NACW far offshore and a combination of NACW and SACW nearshore, separated by the Canary Upwelling Front (CUF). The larvae of different myctophid species serve as indicators of the water masses, e.g. S. veranyi and M. punctatum were found in some coastal stations that were dominated by NACW, while the tropical mesopelagic B. argyrogaster, H. macrochir, M. affine and S. kreffti were associated to the SACW. The along-slope offshore convergence of NACW and SACW takes place at the Cape Verde Frontal Zone (CVFZ), representing a region of extensive offshore export for larvae of coastal species, S. pilchardus and E. encrasicolus, far from their nearshore spawning area. The large-scale frontal systems (CVFZ and CUF) and mesoscale eddies contribute to retain larvae within productive waters, influencing both coastal and oceanic species.

Response of zooplankton to physical changes in the environment: coastal upwelling along central west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Madhupratap, M.; Nair, S.R.S.; Haridas, P.; Padmavati, G.

.U. Haq and J.D. Milliman, (Eds.), Marine Geology and Oceanography ofArabian Sea and Coastal Pakistan. New York: Reinhold, pp. 339-350. PAFFENHOFER, G-A.; WESTER, B.T. and NICHO· LAS, W.O., 1984. Zooplankton abundance in rela- Journal of Coastal Research... Ocean. Proceedings of the Indian Academy of Sciences, 94, 129-137. SMITH, S.L., 1982. The northwest Indian Ocean dur ing the monsoons of 1979: distribution, abundance and feeding of zooplankton. Deep-Sea Research, 29, 1331-1353. SMITH, S.L.; BOYQ, C...

Ocean Acidification of the Pacific Northwest Coastal Waters: A Modeling Study

Science.gov (United States)

Siedlecki, S. A.; MacCready, P.; McCabe, R. M.; Feely, R. A.; Alin, S. R.; Newton, J.; Barth, J. A.; Durski, S. M.

2016-02-01

Total inorganic carbon and alkalinity is incorporated into a regional bio-physical model to examine inorganic carbon variability along the Washington and Oregon continental margin. Results are compared to output from an existing oxygen model (Siedlecki et al., 2015) combined with observationally-based empirical relationships between carbon system parameters, oxygen, and temperature (Alin et al., in prep). Model hindcasts for 2007 and 2013 are also validated against local observations of dissolved oxygen, pH, and the saturation state of aragonite. Challenges and benefits of each approach are discussed. The model suggests that the volume of hypoxic and undersaturated water present over the continental shelf increases over the upwelling season, occupying more of the water column later in the upwelling season. This would result in increasingly stressful conditions for biota over most of the water column as the upwelling season progresses. Spatial variability in the volume of undersaturated water in the region will also be discussed.

Climate Change and Coastal Zones. An Overview of the State-of-the-Art on Regional and Local Vulnerability Assessment

International Nuclear Information System (INIS)

Sterr, H.; Klein, R.J.T.; Reese, S.

2000-06-01

This paper provides an overview of the latest developments in methodologies for assessing the vulnerability of coastal zones to climate change at regional and local scales. The focus of vulnerability assessment in coastal zones used to be on erosion and land loss due to sea-level rise. Methodologies now increasingly consider the wide range of climate and impact variables that play a part in determining coastal vulnerability, as well as non-climatic developments. The paper presents a conceptual framework for vulnerability assessment that identifies a number of system components that can be considered determinants of vulnerability. It then goes on to outline a number of steps that are required for the actual assessment of coastal vulnerability, such as scenario development, data collection and impact assessment. The approach is illustrated using a regional and local case study in Germany

Modelization of highly nonlinear waves in coastal regions

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Gouin, Maïté; Ducrozet, Guillaume; Ferrant, Pierre

2015-04-01

The proposed work deals with the development of a highly non-linear model for water wave propagation in coastal regions. The accurate modelization of surface gravity waves is of major interest in ocean engineering, especially in the field of marine renewable energy. These marine structures are intended to be settled in coastal regions where the effect of variable bathymetry may be significant on local wave conditions. This study presents a numerical model for the wave propagation with complex bathymetry. It is based on High-Order Spectral (HOS) method, initially limited to the propagation of non-linear wave fields over flat bottom. Such a model has been developed and validated at the LHEEA Lab. (Ecole Centrale Nantes) over the past few years and the current developments will enlarge its application range. This new numerical model will keep the interesting numerical properties of the original pseudo-spectral approach (convergence, efficiency with the use of FFTs, …) and enable the possibility to propagate highly non-linear wave fields over long time and large distance. Different validations will be provided in addition to the presentation of the method. At first, Bragg reflection will be studied with the proposed approach. If the Bragg condition is satisfied, the reflected wave generated by a sinusoidal bottom patch should be amplified as a result of resonant quadratic interactions between incident wave and bottom. Comparisons will be provided with experiments and reference solutions. Then, the method will be used to consider the transformation of a non-linear monochromatic wave as it propagates up and over a submerged bar. As the waves travel up the front slope of the bar, it steepens and high harmonics are generated due to non-linear interactions. Comparisons with experimental data will be provided. The different test cases will assess the accuracy and efficiency of the method proposed.

Coastal counter-currents setup patterns in the Gulf of Cadiz

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Relvas, P.; Juniór, L.; Garel, E.; Drago, T.

2017-12-01

Alongshore coastal counter-currents (CCC) are frequent features of Eastern Boundary Upwelling Systems, where they temporally alternate with upwelling driven jets of opposite direction. Along the northern margin of the Gulf of Cadiz inner shelf, these CCCs are oriented poleward (eastward) and responsible for sharp temperature increases during the upwelling season, along with potential decline in water quality at the coast. This research is based on a multi-year ADCP velocity time-series (2008-2017), recorded at a single location (23 m water depth) over 13 deployments up to 3 months-long. The analysis focuses on the water column alongshore velocities during current inversions (i.e., the transition from equatorward upwelling jets to poleward CCCs). A set of parameters were derived from the flow structure to identify distinct types of inversions and to hypothesize about their driving mechanisms. Results show that 77% of the inversions start near the bed, propagating then to the upper layers. The bottom layer also changes direction before the surface layer for most events (71%). The vertical shear in this case is one order of magnitude greater than in the (less frequent) opposite situation. No seasonal variability is observed in the CCC occurrences. However, the parameters analysed in this study suggest different types of inversion between winter and summer. In winter, inversions are well defined (low variability), with similar patterns near the surface and bed layers as a result of a strong barotropic component. In summer the inversion patterns are more variable. In particular, the upper and bed layers are often importantly decoupled during inversions, indicating the strengthening of baroclinicity. A categorization of inversions events is proposed based on cross-correlation and multi-variable analyses of the developed parameters. Various types of inversion are obtained, suggesting that CCCs are driven by different forcings that may act separately or jointly.

Scales and sources of pH and dissolved oxygen variability in a shallow, upwelling-driven ecosystem

Science.gov (United States)

Tanner, C. A.; Martz, T.; Levin, L. A.

2011-12-01

In the coastal zone extreme variability in carbonate chemistry and oxygen is driven by fluctuations in temperature, salinity, air-sea gas exchange, mixing processes, and biology. This variability appears to be magnified in upwelling-driven ecosystems where low oxygen and low pH waters intrude into shallow depths. The oxygen and carbon chemistry signal can be further confounded by highly productive ecosystems such as kelp beds where photosynthesis and respiration consume and release significant amounts of dissolved inorganic carbon and oxygen. This variability poses a challenge for scientists assessing the impacts of climate change on nearshore ecosystems. We deployed physical & biogeochemical sensors in order to observe these processes in situ. The "SeapHOx" instruments used in this study consist of a modified Honeywell Durafet° ISFET pH sensor, an Aanderra Optode Oxygen sensor, and a SBE-37 conductivity, temperature, pressure sensor. The instruments were deployed on and around the La Jolla Kelp Forest at a variety of depths. Our goals were to (a) characterize the link between pH and oxygen and identify the magnitude of pH and oxygen variability over a range of intra-annual time scales and (b) investigate spatial patterns of pH and oxygen variability associated with depth, proximity to shore, and presence of kelp. Results thus far reveal a strong relationship between oxygen and pH. Temporal variability is greatest at the semidiurnal frequency where pH (at 7 m) can range up to 0.3 units and oxygen can change 50% over 6 h. Diurnal variability is a combination of the diurnal tidal component and diel cycles of production and respiration. Event-scale dynamics associated with upwelling can maintain pH and oxygen below 7.8 units and 200 μmol kg-1, respectively, for multiple days. Frequent current reversals drive changes in the observed oxygen and pH variability. When alongshore currents are flowing southward, driven by upwelling-favorable winds, the magnitude of

Stable nitrogen isotopes in coastal macroalgae: geographic and anthropogenic variability.

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Viana, Inés G; Bode, Antonio

2013-01-15

Growing human population adds to the natural nitrogen loads to coastal waters. Both anthropogenic and natural nitrogen is readily incorporated in new biomass, and these different nitrogen sources may be traced by the measurement of the ratio of stable nitrogen isotopes (δ(15)N). In this study δ(15)N was determined in two species of macroalgae (Ascophyllum nodosum and Fucus vesiculosus), and in nitrate and ammonium to determine the relative importance of anthropogenic versus natural sources of nitrogen along the coast of NW Spain. Both algal species and nitrogen sources showed similar isotopic enrichment for a given site, but algal δ(15)N was not related to either inorganic nitrogen concentrations or δ(15)N in the water samples. The latter suggests that inorganic nitrogen inputs are variable and do not always leave an isotopic trace in macroalgae. However, a significant linear decrease in macroalgal δ(15)N along the coast is consistent with the differential effect of upwelling. Besides this geographic variability, the influence of anthropogenic nitrogen sources is evidenced by higher δ(15)N in macroalgae from rias and estuaries compared to those from open coastal areas and in areas with more than 15×10(3) inhabitants in the watershed. These results indicate that, in contrast with other studies, macroalgal δ(15)N is not simply related to either inorganic nitrogen concentrations or human population size but depends on other factors as the upwelling or the efficiency of local waste treatment systems. Copyright © 2012 Elsevier B.V. All rights reserved.

Primary productivity

Digital Repository Service at National Institute of Oceanography (India)

Verlecar, X.N.; Parulekar, A.H.

Photosynthetic production in the oceans in relation to light, nutrients and mixing processes is discussed. Primary productivity in the estuarine region is reported to be high in comparison to coastal and oceanic waters. Upwelling phenomenon...

Analysis of systematic fracturing in Eocene flsch of the Slovenian coastal region

Directory of Open Access Journals (Sweden)

Marko Vrabec

2017-12-01

Full Text Available We analyse systematic fractures occurring in sandstone beds in Eocene flsch of the Slovenian coastal area. Two nearly perpendicular fracture sets were identifid: fractures F1 are generally NW-SE oriented, wellexpressed and predominately planar, whereas fractures F2 are NE-SW-striking, shorter, more irregular in shape, and terminate against the F1 set. The average orientation of both sets does not change signifiantly in a coastal transect crossing all principal structural domains of the area. We analysed fracture spacing with respect to layer thickness and determined fracture spacing index for both fracture sets. We interpret both fracture sets as tensional (Mode I joints originating in two distinct extensional episodes. Set F1 is older and formed in NE-SW directed tension which we correlate with the well-documented regional post-Dinaric orogen-perpendicular extension of presumably mid-Miocene age. Set F2 formed in NW-SE oriented tension, which is compatible with previously documented NE-SW-striking normal faults occurring in the area, but was so far not documented elsewhere. We interpret that F1 fractures predate folding and thrusting in the coastal belt. Earlier, Eocene-Oligocene Dinaric thrusting therefore did not signifiantly affect the coastal area, whereas post-F1 shortening, associated with northward indentation and underthrusting of the Adria microplate, did not commence before late Miocene.

Upwelling along the east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Murty, C.S.; Varadachari, V.V.R.

the premonsoon and monsoon periods. Waters from deeper layers of the shelf appear to reach the surface causing considerable fall of surface temperature near the coast. The probable causes for these differences in upwelling along the coast are discussed...

Nutrient dynamics and oceanographic features in the central Namibian upwelling region as reflected in δ15N-signals of suspended matter and surface sediments

Directory of Open Access Journals (Sweden)

S. Meisel

2011-08-01

Full Text Available The study deals with the modern situation of the northern Benguela Upwelling, directing particular attention to the shelf region off central Namibia (21 to 24° S. At the centre of the investigation is the comparison of δ15N-records in surface sediments (δ15Nsediment with suspended particulate matter (δ15NSPM from the surface ocean. In addition to that, water column profiles (including hydrographic data provide an insight into changes of δ15NSPM with depth and elucidate potential offsets between δ15NSPM and δ15Nsediment. The parallel spatial trend of δ15Nsediment and surface ocean δ15NSPM shows that secondary processes are not so pronounced as to obliterate the signal generated in the surface waters. Highest δ15N-signatures are found right off the coast where water temperatures are lowest. Concomitantly high productivity rates and low bottom oxygen suggest the upwelling of denitrified source waters. With increasing distance offshore, δ15N declines unexpectedly, reaching a minimum above the shelf break. Beyond that, the trend reverses to "normal" with δ15N-signals continuously increasing towards the mesopelagic ocean. The decrease in δ15Nsediment and surface ocean δ15NSPM with increasing distance to the coast disagrees with the concept of Rayleigh fractionation kinetics, viz. the progressive 15N-enrichment of the nitrate pool as it is gradually used up by phytoplankton growth. On the basis of the available evidence, the downward trend of δ15N results from decreased relative nitrate consumption, resting on a combination of reduced primary production and the existence of an ulterior source of nutrients. Nutrient replenishment seems to occur via an additional upwelling front at the edge of the shelf as well as tapping of subsurface nitrate through sufficiently deep penetration of wind- and wave-induced mixing over large areas of the shelf. Both mechanisms are considered capable of working against the expected nutrient drawdown (i.e. 15

DEFORMATION EFFECTS OF DAMS ON COASTAL REGIONS USING SENTINEL-1 IW TOPS TIME SERIES: THE WEST LESVOS, GREECE CASE

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K. Karamvasis

2017-11-01

Full Text Available Coastal zones are vulnerable to erosion and loss by level sea rise. Subsidence caused by the reduction of fluvial sediments in coastal zones found close to dams, is another important deformation factor. Quantification of the deformation rate of coastal region is essential for natural and anthropogenic activities. The study utilizes Interferometric SAR (Synthetic Aperture Radar techniques and exploits the archive of Sentinel-1 TOPS data for the period 2014–2016. The freely available, wide ground coverage (250 × 170 km and small temporal resolution Sentinel-1 TOPS datasets are promising for coastal applications. Persistent Scatterer Interferometry (PSI methodologies are considered state-of-the-art remote sensing approaches for land deformation monitoring. The selected PSI method is the Small Baseline Subset (SBAS multitemporal InSAR technique. The study area of this study is the coastal zone of west region of Lesvos Island, Greece. The main characteristic of the area is the reduction of the fluvial sediment supply from the coastal drainage basins due to construction of dams and the abstraction of riverine sediments. The study demonstrates the potentials of the SBAS method for measuring and mapping the dynamic changes in coastal topography in terms of subsidence rates and discusses its advantages and limitations. The results show that natural and rural environments appear to have diverse ground deformation patterns.

Natural ocean acidification at Papagayo upwelling system (north Pacific Costa Rica): implications for reef development

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Sánchez-Noguera, Celeste; Stuhldreier, Ines; Cortés, Jorge; Jiménez, Carlos; Morales, Álvaro; Wild, Christian; Rixen, Tim

2018-04-01

Numerous experiments have shown that ocean acidification impedes coral calcification, but knowledge about in situ reef ecosystem response to ocean acidification is still scarce. Bahía Culebra, situated at the northern Pacific coast of Costa Rica, is a location naturally exposed to acidic conditions due to the Papagayo seasonal upwelling. We measured pH and pCO2 in situ during two non-upwelling seasons (June 2012, May-June 2013), with a high temporal resolution of every 15 and 30 min, respectively, using two Submersible Autonomous Moored Instruments (SAMI-pH, SAMI-CO2). These results were compared with published data from the 2009 upwelling season. Findings revealed that the carbonate system in Bahía Culebra shows a high temporal variability. Incoming offshore waters drive intra- and interseasonal changes. Lowest pH (7.8) and highest pCO2 (658.3 µatm) values measured during a cold-water intrusion event in the non-upwelling season were similar to those minimum values reported from upwelling season (pH = 7.8, pCO2 = 643.5 µatm), unveiling that natural acidification also occurs sporadically in the non-upwelling season. This affects the interaction of photosynthesis, respiration, calcification and carbonate dissolution and the resulting diel cycle of pH and pCO2 in the reefs of Bahía Culebra. During the non-upwelling season, the aragonite saturation state (Ωa) rises to values of > 3.3 and during the upwelling season falls below 2.5. The Ωa threshold values for coral growth were derived from the correlation between measured Ωa and coral linear extension rates which were obtained from the literature and suggest that future ocean acidification will threaten the continued growth of reefs in Bahía Culebra. These data contribute to building a better understanding of the carbonate system dynamics and coral reefs' key response (e.g., coral growth) to natural low-pH conditions, in upwelling areas in the eastern tropical Pacific and beyond.

Energy and resource basis of an Italian coastal resort region integrated using emergy synthesis.

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Vassallo, Paolo; Paoli, Chiara; Tilley, David R; Fabiano, Mauro

2009-10-01

Sustainable development of coastal zones must balance economic development that encourages human visitation from a larger population with desires that differ from the local residents with the need to maintain opportunities for the local resident society and conserve ecological capital, which may serve as the basis for residents. We present a case study in which the sustainability level of a coastal zone (Riviera del Beigua), located along the Ligurian coast of north-western Italy, was assessed through the lens of systems ecology using emergy synthesis to integrate across economic, social and environmental sub-systems. Our purposes were (1) to quantify the environmental sustainability level of this coastal zone, (2) to evaluate the role of tourism in affecting the economy, society and environment, and (3) to compare emergy synthesis to Butler's Tourism Area Life Cycle model (TALC). Results showed that 81% of the total emergy consumption in the coastal zone was derived from external sources, indicating that this tourist-heavy community was not sustainable. Tourism, as the dominant economic sub-system, consumed 42% of the total emergy budget, while local residents used the remaining 58%. The progressive stages of the TALC model were found to parallel the dynamic changes in the ratio of external emergy inputs to local emergy inputs, suggesting that emergy synthesis could be a useful tool for detecting a tourist region's TALC stage. Use of such a quantitative tool could expedite sustainability assessment to allow administrative managers to understand the complex relationship between a region's economy, environment and resident society so sound policies can be developed to improve overall sustainability.

Nearshore currents on the southern Namaqua shelf of the Benguela upwelling system

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Fawcett, A. L.; Pitcher, G. C.; Shillington, F. A.

2008-05-01

Nearshore currents of the southern Namaqua shelf were investigated using data from a mooring situated three and a half kilometres offshore of Lambert's Bay, downstream of the Cape Columbine upwelling cell, on the west coast of South Africa. This area is susceptible to harmful algal blooms (HABs) and wind-forced variations in currents and water column structure are critical in determining the development, transport and dissipation of blooms. Time series of local wind data, and current and temperature profile data are described for three periods, considered to be representative of the latter part of the upwelling season (27 January-22 February), winter conditions (5-29 May) and the early part of the upwelling season (10 November-12 December) in 2005. Differences observed in mean wind strength and direction between data sets are indicative of seasonal changes in synoptic meteorological conditions. These quasi-seasonal variations in wind forcing affect nearshore current flow, leading to mean northward flow in surface waters early in the upwelling season when equatorward, upwelling-favourable winds are persistent. Mean near-surface currents are southward during the latter part of the upwelling season, consistent with more prolonged periods of relaxation from equatorward winds, and under winter conditions when winds were predominantly poleward. Within these seasonal variations in mean near-surface current direction, two scales of current variability were evident within all data sets: strong inertial oscillations were driven by diurnal winds and introduced vertical shear into the water column enhancing mixing across the thermocline, while sub-inertial current variability was driven by north-south wind reversals at periods of 2-5 days. Sub-inertial currents were found to lag wind reversals by approximately 12 h, with a tendency for near-surface currents to flow poleward in the absence of wind forcing. Consistent with similar sites along the Californian and Iberian coasts

Crustal structure of the coastal and marine San Francisco Bay region, California

Science.gov (United States)

Parsons, Tom

2002-01-01

As of the time of this writing, the San Francisco Bay region is home to about 6.8 million people, ranking fifth among population centers in the United States. Most of these people live on the coastal lands along San Francisco Bay, the Sacramento River delta, and the Pacific coast. The region straddles the tectonic boundary between the Pacific and North American Plates and is crossed by several strands of the San Andreas Fault system. These faults, which are stressed by about 4 cm of relative plate motion each year, pose an obvious seismic hazard.

Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea

Science.gov (United States)

George, John C.; Druckenmiller, Matthew L.; Laidre, Kristin L.; Suydam, Robert; Person, Brian

2015-08-01

We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering-Chukchi-Beaufort Seas (BCB) stock to estimate various body condition indices (BCI's) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989-2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI's was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the

Metallogenic events in the Coastal Cordillera of Copiapo region, northern Chile (26-28o S)

International Nuclear Information System (INIS)

Diaz, A.; Vivallo, W

2001-01-01

The metallogenic province of the Coastal Cordillera in the Copiapo region is characterized by Cu, Cu-Au,Cu-Fe-Au, Fe, Ag and Au deposits. The ore deposits are ranging in ages between Middle to Late Jurassic (1) and Early Cretaceous (2). Results of a geochronology program for ore deposits in this metallogenic province, in addition to existing geochronological control of the ore deposits host rocks (mainly intrusive) allowed to define four different Metallogenic Epochs which could be extended to other zones in the Coastal Cordillera (au)

The effect of evaporation and nutrient enrichment on the erodability of mudflats in a mesotidal estuary

Science.gov (United States)

Fagherazzi, S.; Viggato, T.; Vieillard, A. M.; Fulweiler, R. W.

2014-12-01

The continental shelf region off the Washington-Oregon-California coast is seasonally exposed to water with a low aragonite saturation state by coastal upwelling of CO2-rich waters. To date, the spatial and temporal distribution of anthropogenic CO2 (Canth) contribution to the CO2-rich waters is largely unknown. Here we use an adaptation of the linear regression approach described in Feely et al. (2008) to utilize the GO-SHIP Repeat Hydrography data set from the northeast Pacific to establish an annually updated relationship between Canth and potential density. This relationship was then used with the NOAA Ocean Acidification Program West Coast cruise data sets from 2007, 2011, 2012 and 2013 to determine the spatial variations of Canth in the upwelled water. Our results show large spatial differences in Canth in surface waters along the coast with the lowest values (40-45 μmol kg-1) in strong upwelling regions of off northern California and southern Oregon and higher values (50-70 μmol kg-1) to the north and south of this region. Canth contributes an average of about 70 % of the increased amount of dissolved inorganic carbon in the upwelled waters at the surface relative to what would be expected from physical circulation and exchange with a preindustrial atmosphere alone. In contrast, Canth contributes an average of about 31%, and 16% of the increased amount of dissolved inorganic carbon at 50 m depth, and at 100 m depth respectively. The remaining contributions are either due to respiration processes in the water that was upwelled and transported to coastal regions or respiration processes that occurs locally during the course of the upwelling season. The uptake of Canth has caused the aragonite saturation horizon to shoal by approximately 30-50 m since preindustrial period so that the undersaturated waters are well within the regions of the continental shelf that affect the biological communities.

Evidence of bottom-up limitations in nearshore marine systems based on otolith proxies of fish growth

Science.gov (United States)

von Biela, Vanessa R.; Kruse, Gordon H.; Mueter, Franz J.; Black, Bryan A.; Douglas, David C.; Helser, Thomas E.; Zimmerman, Christian E.

2015-01-01

Fish otolith growth increments were used as indices of annual production at nine nearshore sites within the Alaska Coastal Current (downwelling region) and California Current (upwelling region) systems (~36–60°N). Black rockfish (Sebastes melanops) and kelp greenling (Hexagrammos decagrammus) were identified as useful indicators in pelagic and benthic nearshore food webs, respectively. To examine the support for bottom-up limitations, common oceanographic indices of production [sea surface temperature (SST), upwelling, and chlorophyll-a concentration] during summer (April–September) were compared to spatial and temporal differences in fish growth using linear mixed models. The relationship between pelagic black rockfish growth and SST was positive in the cooler Alaska Coastal Current and negative in the warmer California Current. These contrasting growth responses to SST among current systems are consistent with the optimal stability window hypothesis in which pelagic production is maximized at intermediate levels of water column stability. Increased growth rates of black rockfish were associated with higher chlorophyll concentrations in the California Current only, but black rockfish growth was unrelated to the upwelling index in either current system. Benthic kelp greenling growth rates were positively associated with warmer temperatures and relaxation of downwelling (upwelling index near zero) in the Alaska Coastal Current, while none of the oceanographic indices were related to their growth in the California Current. Overall, our results are consistent with bottom-up forcing of nearshore marine ecosystems—light and nutrients constrain primary production in pelagic food webs, and temperature constrains benthic food webs.

Hot upwelling conduit beneath the Atlas Mountains, Morocco

Science.gov (United States)

Sun, Daoyuan; Miller, Meghan S.; Holt, Adam F.; Becker, Thorsten W.

2014-11-01

The Atlas Mountains of Morocco display high topography, no deep crustal root, and regions of localized Cenozoic alkaline volcanism. Previous seismic imaging and geophysical studies have implied a hot mantle upwelling as the source of the volcanism and high elevation. However, the existence, shape, and physical properties of an associated mantle anomaly are debated. Here we use seismic waveform analysis from a broadband deployment and geodynamic modeling to define the physical properties and morphology of the anomaly. The imaged low-velocity structure extends to ~200 km beneath the Atlas and appears ~350 K hotter than the ambient mantle with possible partial melting. It includes a lateral conduit, which suggests that the Quaternary volcanism arises from the upper mantle. Moreover, the shape and temperature of the imaged anomaly indicate that the unusually high topography of the Atlas Mountains is due to active mantle support.

Characteristic ichthyoplankton taxa in the separation zone of the East Australian Current: Larval assemblages as tracers of coastal mixing

Science.gov (United States)

Syahailatua, Augy; Roughan, Moninya; Suthers, Iain M.

2011-03-01

Ichthyoplankton assemblages were compared between regions dominated by the oligotrophic East Australian Current (EAC) and the inner-shelf waters off southeastern Australia, to determine if the early life history of fish was related to the separation of the EAC from the coast, producing different water masses as well as characteristic taxa. Samples were collected at the surface and in sub-surface waters, at 50 and 100 m isobath stations, during two summer research voyages in November 1998 and January 1999. On both voyages the study region was characterized by coastal and EAC waters in the north (˜31°S), and in the south by topographically induced upwelling (˜31°S), associated with narrowing of the continental shelf and separation of the EAC from the coast. Among the 111 families of larval fish, we observed distinctive assemblages of ichthyoplankton associated with the two different water masses. A greater abundance of the Carangidae, Labridae, Lutjanidae, Microcanthidae, Myctophidae and Scombridae was associated with the nutrient poor EAC water mass, while the Callionymidae, Clupeidae, Platycephalidae and Sillaginidae were mostly found in the cooler and/or fresher inner-shelf water mass. We assessed these patterns with opportunistic samples from an unusual, wind-driven upwelling event in the north (˜31°S) earlier in the November voyage. The relative abundance of these 10 characteristic families distinguished this wind-driven upwelling event from the subsequent relaxation and predominance of the EAC assemblage at this location just 6 d later. Distinctive and abundant families such as larval clupeids, relative to larval carangids, could be a useful marker of inner-shelf, EAC and mixed water masses in the absence of robust hydrographic data. This and related studies indicate contrast in early life histories of Sardinops sagax and Trachurus spp., which appear to spawn respectively in the inner-shelf and outer-shelf waters. The post-flexion stages of S. sagax

Inferring coastal processes from regional-scale mapping of 222Radon and salinity: examples from the Great Barrier Reef, Australia

International Nuclear Information System (INIS)

Stieglitz, Thomas C.; Cook, Peter G.; Burnett, William C.

2010-01-01

The radon isotope 222 Rn and salinity in coastal surface water were mapped on regional scales, to improve the understanding of coastal processes and their spatial variability. Radon was measured with a surface-towed, continuously recording multi-detector setup on a moving vessel. Numerous processes and locations of land-ocean interaction along the Central Great Barrier Reef coastline were identified and interpreted based on the data collected. These included riverine fluxes, terrestrially-derived fresh submarine groundwater discharge (SGD) and the tidal pumping of seawater through mangrove forests. Based on variations in the relationship of the tracers radon and salinity, some aspects of regional freshwater inputs to the coastal zone and to estuaries could be assessed. Concurrent mapping of radon and salinity allowed an efficient qualitative assessment of land-ocean interaction on various spatial and temporal scales, indicating that such surveys on coastal scales can be a useful tool to obtain an overview of SGD locations and processes.

Cooperative Monitoring Center Occasional Paper/11: Cooperative Environmental Monitoring in the Coastal Regions of India and Pakistan

Energy Technology Data Exchange (ETDEWEB)

Rajen, Gauray

1999-06-01

The cessation of hostilities between India and Pakistan is an immediate need and of global concern, as these countries have tested nuclear devices, and have the capability to deploy nuclear weapons and long-range ballistic missiles. Cooperative monitoring projects among neighboring countries in South Asia could build regional confidence, and, through gradual improvements in relations, reduce the threat of war and the proliferation of weapons of mass destruction. This paper discusses monitoring the trans-border movement of flow and sediment in the Indian and Pakistani coastal areas. Through such a project, India and Pakistan could initiate greater cooperation, and engender movement towards the resolution of the Sir Creek territorial dispute in their coastal region. The Joint Working Groups dialogue being conducted by India and Pakistan provides a mechanism for promoting such a project. The proposed project also falls within a regional framework of cooperation agreed to by several South Asian countries. This framework has been codified in the South Asian Seas Action Plan, developed by Bangladesh, India, Maldives, Pakistan and Sri Lanka. This framework provides a useful starting point for Indian and Pakistani cooperative monitoring in their trans-border coastal area. The project discussed in this paper involves computer modeling, the placement of in situ sensors for remote data acquisition, and the development of joint reports. Preliminary computer modeling studies are presented in the paper. These results illustrate the cross-flow connections between Indian and Pakistani coastal regions and strengthen the argument for cooperation. Technologies and actions similar to those suggested for the coastal project are likely to be applied in future arms control and treaty verification agreements. The project, therefore, serves as a demonstration of cooperative monitoring technologies. The project will also increase people-to-people contacts among Indian and Pakistani policy

Multiscale upwelling forcing cycles and biological response off north-central Chile Ciclos multiescala en el forzamiento de la surgencia y respuesta biológica en el centro-norte de Chile

Directory of Open Access Journals (Sweden)

JOSÉ RUTLLANT

2002-03-01

Full Text Available The physical forcing of the upwelling along the subtropical west coasts of the continents encompasses a broad range of time scales which shape both phytoplankton biomass (Chl-a and primary productivity (carbon fixation changes over any given time interval. The narrow continental shelf and the steep alongshore orography off north-central Chile provide for a unique combination of year-round, upwelling-favorable winds with quasi-weekly upwelling pulses associated with atmospheric coastal-trapped disturbances (coastal lows. This variability is modulated by intraseasonal oscillations in the depth of the thermo/nutricline, produced by coastal-trapped waves in the ocean, upon which annual (seasons and interannual (ENSO cycles are superimposed. During coastal field experiments off Cruz Grande bay (29º S, carried on in November 1987 and 1988 (opposite extremes of the ENSO cycle, mean changes of the phytoplankton-integrated Chl-a (B and carbon fixation rate (PP from the active to the relaxed phases of the local upwelling forcing cycle (phyto-pattern were characterized. Those data were contrasted against similar ones reported off Punta Lengua de Vaca (Coquimbo, 30º S and off Mejillones peninsula (Antofagasta, 23º S, encompassing different seasons and phases of intraseasonal and interannual (ENSO cycles from 1992 to 1997. A "warm" phyto-pattern was schematically characterized by a significant increase in B and a quasi-steady evolution of PP from the active to the relaxed phases of one complete upwelling event. Conversely, relative small changes in B and a significant increase in PP characterized a "cold" phyto-pattern. It is proposed here that the ENSO "cold/warm" signal may be offset by more than one opposite "thermal" condition (seasonal and/or intraseasonal in defining a "warm" or "cold" phyto-pattern associated with a particular cycle of the local upwelling forcingEl forzamiento físico de la surgencia a lo largo de las costas occidentales de los

Development of three dimensional ocean current model for coastal region

International Nuclear Information System (INIS)

Kobayashi, Takuya

1999-12-01

In order to study the migration behavior of radionuclides released into a coastal region around Japan, Princeton Ocean Model (POM) was introduced. This three-dimensional ocean current model was modified to be applied for oceanic simulations around Japan. This report describes the governing equations, numerical methods and model improvements. In addition, database system which is utilized for calculations and visualization system for graphical outputs are also described. Model simulation was carried out at off the area of Shimokita. Aomori-ken, Japan to investigate the effects of the boundary conditions on simulated results. (author)

The Effect of Alongcoast Advection on Pacific Northwest Shelf and Slope Water Properties in Relation to Upwelling Variability

Science.gov (United States)

Stone, Hally B.; Banas, Neil S.; MacCready, Parker

2018-01-01

The Northern California Current System experiences highly variable seasonal upwelling in addition to larger basin-scale variability, both of which can significantly affect its water chemistry. Salinity and temperature fields from a 7 year ROMS hindcast model of this region (43°N-50°N), along with extensive particle tracking, were used to study interannual variability in water properties over both the upper slope and the midshelf bottom. Variation in slope water properties was an order of magnitude smaller than on the shelf. Furthermore, the primary relationship between temperature and salinity anomalies in midshelf bottom water consisted of variation in density (cold/salty versus warm/fresh), nearly orthogonal to the anomalies along density levels (cold/fresh versus warm/salty) observed on the upper slope. These midshelf anomalies were well-explained (R2 = 0.6) by the combination of interannual variability in local and remote alongshore wind stress, and depth of the California Undercurrent (CUC) core. Lagrangian analysis of upper slope and midshelf bottom water shows that both are affected simultaneously by large-scale alongcoast advection of water through the northern and southern boundaries. The amplitude of anomalies in bottom oxygen and dissolved inorganic carbon (DIC) on the shelf associated with upwelling variability are larger than those associated with typical variation in alongcoast advection, and are comparable to observed anomalies in this region. However, a large northern intrusion event in 2004 illustrates that particular, large-scale alongcoast advection anomalies can be just as effective as upwelling variability in changing shelf water properties on the interannual scale.

Natural ocean acidification at Papagayo upwelling system (north Pacific Costa Rica: implications for reef development

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C. Sánchez-Noguera

2018-04-01

Full Text Available Numerous experiments have shown that ocean acidification impedes coral calcification, but knowledge about in situ reef ecosystem response to ocean acidification is still scarce. Bahía Culebra, situated at the northern Pacific coast of Costa Rica, is a location naturally exposed to acidic conditions due to the Papagayo seasonal upwelling. We measured pH and pCO2 in situ during two non-upwelling seasons (June 2012, May–June 2013, with a high temporal resolution of every 15 and 30 min, respectively, using two Submersible Autonomous Moored Instruments (SAMI-pH, SAMI-CO2. These results were compared with published data from the 2009 upwelling season. Findings revealed that the carbonate system in Bahía Culebra shows a high temporal variability. Incoming offshore waters drive intra- and interseasonal changes. Lowest pH (7.8 and highest pCO2 (658.3 µatm values measured during a cold-water intrusion event in the non-upwelling season were similar to those minimum values reported from upwelling season (pH  =  7.8, pCO2  =  643.5 µatm, unveiling that natural acidification also occurs sporadically in the non-upwelling season. This affects the interaction of photosynthesis, respiration, calcification and carbonate dissolution and the resulting diel cycle of pH and pCO2 in the reefs of Bahía Culebra. During the non-upwelling season, the aragonite saturation state (Ωa rises to values of  >  3.3 and during the upwelling season falls below 2.5. The Ωa threshold values for coral growth were derived from the correlation between measured Ωa and coral linear extension rates which were obtained from the literature and suggest that future ocean acidification will threaten the continued growth of reefs in Bahía Culebra. These data contribute to building a better understanding of the carbonate system dynamics and coral reefs' key response (e.g., coral growth to natural low-pH conditions, in upwelling areas in the eastern tropical

Impact of climate change on food security in southwest coastal region of bangladesh

International Nuclear Information System (INIS)

Islam, S.; Rahman, A.

2014-01-01

This paper examines the impact of climate change on food security of the population residing in the coastal area of Bangladesh. Based on multistage random sampling technique, a survey was conducted to collect socioeconomic and food datasets of the people affected by extreme climate events in the country. The study found that climate change caused food insecurity in the region; it led to greater dependence on pond and rain water for cooking food and water intake. Catastrophe due to extreme weather events adversely affected the livelihoods and level of income. The severe cyclonic storms, Sidr (November 2007) and Alia (May 2009) severely affected the vulnerable people of this region, especially the extremely poor. The study came out with several coping strategies to address adverse effects of climate change, including rehabilitation with income and employment generating activities and development training; alternative livelihood adaptation practices; access to subsidized inputs and credits; introduction of crop calendar; conservation of arable and fellow land; and innovation of saline-tolerant, heat-resistant, moderate water consuming and short-rotation crops for the coastal people. (author)

Coastal Zone Color Scanner

Science.gov (United States)

Johnson, B.

1988-01-01

The Coastal Zone Color Scanner (CZCS) spacecraft ocean color instrument is capable of measuring and mapping global ocean surface chlorophyll concentration. It is a scanning radiometer with multiband capability. With new electronics and some mechanical, and optical re-work, it probably can be made flight worthy. Some additional components of a second flight model are also available. An engineering study and further tests are necessary to determine exactly what effort is required to properly prepare the instrument for spaceflight and the nature of interfaces to prospective spacecraft. The CZCS provides operational instrument capability for monitoring of ocean productivity and currents. It could be a simple, low cost alternative to developing new instruments for ocean color imaging. Researchers have determined that with global ocean color data they can: specify quantitatively the role of oceans in the global carbon cycle and other major biogeochemical cycles; determine the magnitude and variability of annual primary production by marine phytoplankton on a global scale; understand the fate of fluvial nutrients and their possible affect on carbon budgets; elucidate the coupling mechanism between upwelling and large scale patterns in ocean basins; answer questions concerning the large scale distribution and timing of spring blooms in the global ocean; acquire a better understanding of the processes associated with mixing along the edge of eddies, coastal currents, western boundary currents, etc., and acquire global data on marine optical properties.

Modelling Ecosystem Dynamics of the Oxygen Minimum Zones in the Angola Gyre and the Northern Benguela Upwelling System.

Science.gov (United States)

Schmidt, M.; Eggert, A.

2016-02-01

The Angola Gyre and the Northern Benguela Upwelling System are two major oxygen minimum zones (OMZ) of different kind connected by the system of African Eastern Boundary Currents. We discuss results from a 3-dimensional coupled biogeochemical model covering both oxygen-deficient systems. The biogeochemical model component comprises trophic levels up to zooplankton. Physiological properties of organisms are parameterized from field data gained mainly in the course of the project "Geochemistry and Ecology of the Namibian Upwelling System" (GENUS). The challenge of the modelling effort is the different nature of both systems. The Angola Gyre, located in a "shadow zone" of the tropical Atlantic, has a low productivity and little ventilation, hence a long residence time of water masses. In the northern Benguela Upwelling System, trade winds drive an intermittent, but permanent nutrient supply into the euphotic zone which fuels a high coastal productivity, large particle export and high oxygen consumption from dissimilatory processes. In addition to the local processes, oxygen-deficient water formed in the Angola Gyre is one of the source water masses of the poleward undercurrent, which feeds oxygen depleted water into the Benguela system. In order to simulate the oxygen distribution in the Benguela system, both physical transport as well as local biological processes need to be carefully adjusted in the model. The focus of the analysis is on the time scale and the relative contribution of the different oxygen related processes to the oxygen budgets in both the oxygen minimum zones. Although these are very different in both the OMZ, the model is found as suitable to produce oxygen minimum zones comparable with observations in the Benguela and the Angola Gyre as well. Variability of the oxygen concentration in the Angola Gyre depends strongly on organismic oxygen consumption, whereas the variability of the oxygen concentration on the Namibian shelf is governed mostly by

Global distribution and seasonal variability of coastal low-level jets derived from ERA-Interim reanalysis

Directory of Open Access Journals (Sweden)

Raza Ranjha

2013-08-01

Full Text Available A low-level wind maximum is often found over the oceans near many coasts around the world. These Coastal Low-Level Jets (CLLJs play an important role in the coastal weather and have significant impacts on regional climate and ecology as well as on a number of human activities. The presence of CLLJs is related to various local circumstances such as land-sea temperature contrasts, upwelling, coastal terrain, orientation of the coast, and so on, but also to the large-scale atmospheric dynamics. This makes studies of CLLJs not only interesting but also challenging. In this study, based on ERA-Interim reanalysis data, the global distribution, spatio-temporal structure and the seasonal variability of CLLJs are documented. Seasonal data from 1980 to 2011 are used to identify areas where CLLJs are frequently found in the lowest 2 km, following criteria based on the vertical profiles of wind speed and temperature. The results are analysed to highlight the fundamental aspects and distinctive features of the CLLJs across the globe, including their occurrence rate, jet height, maximum wind speed and horizontal extent. Global maps of CLLJs are constructed for the summer and winter seasons. The west coasts of North America, the Iberian Peninsula, north-western Africa and the south-eastern coast of the Arabian Peninsula make up the Northern Hemispheric CLLJ regions, while the west coasts of South America, Australia, and southern Africa comprise the South Hemispheric equivalents. The existence and characteristics of CLLJs along the southern coast of Oman and the western coast of the Iberian Peninsula regions are also discussed, not fully envisaged before in the context of CLLJs. The highest occurrence of CLLJs is found during the summer in both hemispheres, and the coast of Oman has the globally highest CLLJ frequency, with also the highest maximum wind speeds. The most commonly found CLLJ has a maximum wind speed between 9 and 15 m s−1, and occurs at

Assessment of groundwater vulnerability in the coastal region of Oman using DRASTIC index method in GIS environment.

Science.gov (United States)

Jamrah, Ahmad; Al-Futaisi, Ahmed; Rajmohan, Natarajan; Al-Yaroubi, Saif

2008-12-01

A study was carried out to develop a vulnerability map for Barka region in the North Batina of Oman using DRASTIC vulnerability index method in GIS environment. DRASTIC layers were created using data from published reports and the seven DRASTIC layers were processed by the ArcGIS geographic information system. Finally, DRASTIC maps were created for 1995 and 2004 to understand the long-term changes in the vulnerability index. DRASTIC vulnerability maps were evaluated using groundwater quality data such as chemical and biological parameters. DRASTIC vulnerability maps of 1995 and 2004 indicate that the northern part of Barka is more vulnerable to pollution than southern part and the central part of Barka also shows high relative vulnerability which is mostly related to the high conductivity values. Moreover, the changes in water level due to high abstraction rate of groundwater reflect in the vulnerability maps and low vulnerability area is increased in the southern part during 2004 compared to 1995. Moreover, regional distribution maps of nitrate, chloride and total and fecal coliforms are well correlated with DRASTIC vulnerability maps. In contrast to this, even though DRASTIC method predicted the central part of the study region is highly vulnerable, both chemical and biological parameters show lower concentrations in this region compared to coastal belt, which is mainly due to agricultural and urban development. In Barka, urban development and agricultural activities are very high in coastal region compared to southern and central part of the study area. Hence, this study concluded that DRASTIC method is also applicable in coastal region having ubiquitous contamination sources.

Upwelling systems in eastern boundary currents have been ...

African Journals Online (AJOL)

spamer

Differences are found in the location of return, onshore flow. .... eastern boundary currents, downstream of the west wind drift ... show maximum upwelling conditions (equatorward winds) in ..... The work of PTS and CJ was supported by Grant.

Process for evaluating overweight truck corridors serving coastal port regions and border ports of entry

Science.gov (United States)

2017-08-01

Coastal and inland ports, regional mobility authorities, cities, and counties located near or along the Texas Gulf Coast, and along the border with Mexico, have been granted authority by the state legislature to establish permitted overweight truck c...

A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation

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R. P. M. Topper

2011-03-01

Full Text Available High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary has been developed. A first order check of the results has been performed by comparison with the results of a recent global Cenomanian CCSM3 run, from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of the basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may have been behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling could have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario could have inhibited large scale black shale formation, as could have the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.

Heterotrophic bacterial production, respiration, and growth efficiency associated with upwelling intensity in the Ulleung Basin, East Sea

Science.gov (United States)

Kim, Bomina; Kim, Sung-Han; Kwak, Jung Hyun; Kang, Chang-Keun; Lee, Sang Heon; Hyun, Jung-Ho

2017-09-01

We investigated bacterial production (BP) and respiration (BR), as well as the physico-chemical properties of the water column, to elucidate the effect of upwelling on heterotrophic bacterial metabolic activities and growth efficiency (BGE) in July 2012 and May 2013 in the Ulleung Basin (UB), East/Japan Sea. The upwelled conditions were characterized by higher chlorophyll-a (Chl-a) concentrations resulting from the upward shift of the nitracline compared to that of the non-upwelled condition. Analyses of the size fractions of Chl-a and pigment composition revealed that large size phytoplankton (> 20 μm), mainly consisting of diatoms, appeared to be the major phytoplankton component. BP and BR were significantly correlated with Chl-a (P 0.05). These results suggest that bacterial metabolic activities are stimulated by the availability of organic resources enhanced by upwelling in the UB. Further statistical analysis showed that the difference in BP and BGE with variations in upwelling intensity were significant (P = 0.018 for BP, P = 0.035 for BGE), but the difference in BR was not significant (P = 0.321). These results suggest that metabolic energy is partitioned more for BP under a strong upwelling condition, i.e. high nutrient and Chl-a conditions. In contrast, the energy generated via respiration was partitioned more for maintaining metabolism rather than for biomass production under weakly or non-upwelled conditions, i.e. stratified and low Chl-a conditions. Overall, our results suggest that any changes in upwelling intensity would significantly affect the carbon cycle associated with the fate of primary production, and the role of the microbial loop in the UB where changes in the intensity and frequency of upwelling associated with climatic changes are in progress.

Equatorial Pacific peak in biological production regulated by nutrient and upwelling during the late Pliocene/early Pleistocene cooling

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J. Etourneau

2013-08-01

Full Text Available The largest increase in export production in the eastern Pacific of the last 5.3 Myr (million years occurred between 2.2 and 1.6 Myr, a time of major climatic and oceanographic reorganization in the region. Here, we investigate the causes of this event using reconstructions of export production, nutrient supply and oceanic conditions across the Pliocene–Pleistocene in the eastern equatorial Pacific (EEP for the last 3.2 Myr. Our results indicate that the export production peak corresponds to a cold interval marked by high nutrient supply relative to consumption, as revealed by the low bulk sedimentary 15N/14N (δ15N and alkenone-derived sea surface temperature (SST values. This ∼0.6 million year long episode of enhanced delivery of nutrients to the surface of the EEP was predominantly initiated through the upwelling of nutrient-enriched water sourced in high latitudes. In addition, this phenomenon was likely promoted by the regional intensification of upwelling in response to the development of intense Walker and Hadley atmospheric circulations. Increased nutrient consumption in the polar oceans and enhanced denitrification in the equatorial regions restrained nutrient supply and availability and terminated the high export production event.

Regional evaluation of particulate matter composition in an Atlantic coastal area (Cantabria region, northern Spain): Spatial variations in different urban and rural environments

Science.gov (United States)

Arruti, A.; Fernández-Olmo, I.; Irabien, A.

2011-07-01

The aim of this study was to determine the major components (Na, Ca, K, Mg, Fe, Al, NH 4+, SO 42-, NO 3-, Cl - and TC) and trace-metal levels (As, Ni, Cd, Pb, Ti, V, Cr, Mn, Cu, Mo, Rh and Hg) in PM 10 and PM 2.5 at an Atlantic coastal city (Santander, Cantabria region, Northern Spain). Additional samples were collected in other urban sites of the Cantabria region to assess the metal content found in different urban environments within the region. To control for the mass attributed to inland regional background particulate matter, samples were also collected in Los Tojos village. The spatial variability of the major PM components shows that PM origins are different at inland and coastal sites. In the coastal city of Santander, the most important contributors are (i) the marine aerosol and (ii) the secondary inorganic aerosol (SIA) and the total carbon (TC) in PM 10 and PM 2.5, respectively. Additionally, the influence of the coastal location on the ionic balance of PM is also studied. The trace metal spatial variability is studied using the coefficient of divergence (COD), which shows that the levels of trace metals at the three studied urban sites are mainly influenced by local emission sources. The main local tracers are identified as follows: Mn in the Santander area; Mo, Cr and Pb at Reinosa; and Ni and V at Castro Urdiales. A more detailed source apportionment study of the local trace metals at Santander is conducted by Principal Component Analysis (PCA) and Positive Matrix Factorisation (PMF); these two receptor models report complementary information. From these statistical analyses, the identified sources of trace metals in PM 10 are urban background sources, industrial sources and traffic. The industrial factor was dominated by Mn, Cu and Pb, which are trace metals used in steel production and manganese-ferroalloy production plant. With respect to PM 2.5, the identified emission sources of trace metals are combustion processes as well as traffic and

NODC Standard Product: C-CAP Coastal Change Analysis Project - St. Croix estuary region (1985 - 1992) (NODC Accession 0090142)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Coastal Change Analysis Project St. Croix Estuary Region CD-ROM data set uses Landsat Thematic Mapper (TM) imagery from 1985 to 1992 to provide a regional change...

Far-reaching transport of Pearl River plume water by upwelling jet in the northeastern South China Sea

Science.gov (United States)

Chen, Zhaoyun; Pan, Jiayi; Jiang, Yuwu; Lin, Hui

2017-09-01

Satellite images from the Moderate Resolution Imaging Spectroradiometer (MODIS) show that there was a belt of turbid water appearing along an upwelling front near the Chinese coast of Guangdong, and indicate that the turbid water of the Pearl River plume water could be transported to a far-reaching area east of the Taiwan Bank. Numerical modeling results are consistent with the satellite observations, and reveal that a strong jet exists at the upwelling front with a speed as high as 0.8 m s- 1, which acts as a pathway for transporting the high-turbidity plume water. The dynamical analysis suggests that geostrophic equilibrium dominates in the upwelling front and plume areas, and the baroclinicity of the upwelling front resulting from the horizontal density gradient is responsible for the generation of the strong jet, which enhances the far-reaching transport of the terrigenous nutrient-rich water of the Pearl River plume. Model sensitivity analyses also confirm that this jet persists as long as the upwelling front exists, even when the wind subsides and becomes insignificant. Further idealized numerical model experiments indicate that the formation and persistence of the upwelling front jet depend on the forcing strength of the upwelling-favorable wind. The formation time of the jet varies from 15 to 158 h as the stress of the upwelling-favorable wind changes from 0.2 to 0.01 N m- 2. With the persistent transport of the nutrient-rich plume water, biophysical activities can be promoted significantly in the far-reaching destination area of the oligotrophic water.

Inferring coastal processes from regional-scale mapping of {sup 222}Radon and salinity: examples from the Great Barrier Reef, Australia

Energy Technology Data Exchange (ETDEWEB)

Stieglitz, Thomas C., E-mail: thomas.stieglitz@jcu.edu.a [AIMS-JCU, Townsville (Australia); Australian Institute of Marine Science, PMB NO 3, Townsville QLD 4810 (Australia); School of Engineering and Physical Sciences, James Cook University, Townsville QLD 4811 (Australia); Cook, Peter G., E-mail: peter.g.cook@csiro.a [CSIRO Land and Water, Private Bag 2, Glen Osmond SA 5064 (Australia); Burnett, William C., E-mail: wburnett@mailer.fsu.ed [Department of Oceanography, Florida State University, Tallahassee, FL 32306 (United States)

2010-07-15

The radon isotope {sup 222}Rn and salinity in coastal surface water were mapped on regional scales, to improve the understanding of coastal processes and their spatial variability. Radon was measured with a surface-towed, continuously recording multi-detector setup on a moving vessel. Numerous processes and locations of land-ocean interaction along the Central Great Barrier Reef coastline were identified and interpreted based on the data collected. These included riverine fluxes, terrestrially-derived fresh submarine groundwater discharge (SGD) and the tidal pumping of seawater through mangrove forests. Based on variations in the relationship of the tracers radon and salinity, some aspects of regional freshwater inputs to the coastal zone and to estuaries could be assessed. Concurrent mapping of radon and salinity allowed an efficient qualitative assessment of land-ocean interaction on various spatial and temporal scales, indicating that such surveys on coastal scales can be a useful tool to obtain an overview of SGD locations and processes.

Tracers vs. trajectories in a coastal region

Science.gov (United States)

Engqvist, A.; Döös, K.

2008-12-01

Two different methods of estimating the water exchange through a Baltic coastal region have been used, consisting of particle trajectories and passive tracers. Water is traced from and to a small discharge region near the coast. The discharge material in this region is treated as zero dimensional particles or tracers with neutral buoyancy. The real discharge material could be a leakage of radio-nuclides through the sea floor from an underground repository of nuclear waste. Water exchange rates between the discharge region and the model domain are estimated using both forward and backward trajectories as well as passive tracers. The Lagrangian trajectories can account for the time evolution of the water exchange while the tracers give one average age per model grid box. Water exchange times such as residence time, age and transient times have been calculated with trajectories but only the average age (AvA) for tracers. The trajectory calculations provide a more detailed time evolution than the tracers. On the other hand the tracers are integrated "on-line" simultaneously in the sea circulation model with the same time step while the Lagrangian trajectories are integrated "off-line" from the stored model velocities with its inherent temporal resolution, presently one hour. The sub-grid turbulence is parameterised as a Laplacian diffusion for the passive tracers and with an extra stochastic velocity for trajectories. The importance of the parameterised sub-grid turbulence for the trajectories is estimated to give an extra diffusion of the same order as the Laplacian diffusion by comparing the Lagrangian dispersions with and without parameterisation. The results of the different methods are similar but depend on the chosen diffusivity coefficient with a slightly higher correlation between trajectories and tracers when integrated with a lower diffusivity coefficient.

Upwelling Index, 51N 131W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Nitrate reducing activity pervades surface waters during upwelling.

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, S.O.; Halarnekar, R.; Malik, A.; Vijayan, V.; Varik, S.; RituKumari; Jineesh V.K.; Gauns, M.U.; Nair, S.; LokaBharathi, P.A.

.A., Roson, G., Perez, F.F., Figueiras, F.G., Pazos, Y., 1996. Nitrogen cycling in an estuarine upwelling system, the Ria de Arousa (NW Spain). Short-time-scale patterns of hydrodynamic and biogeochemical circulation. Mar. Ecol. Prog. Ser. 135, 259...

Upwelling Index, 33N 119W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 30N 119W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 42N 125W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 54N 134W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 60N 149W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 39N 125W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 36N 122W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 24N 113W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 21N 107W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 48N 125W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 45N 125W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 27N 116W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 57N 137W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Upwelling Index, 60N 146W, 6-hourly

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Upwelling index computed from 1-degree FNMOC sea level pressure for 15 locations off the North American West Coast at each 3 degrees of latitude from 21N to 60N. The...

Groundwater Modeling in Coastal Arid Regions Under the Influence of Marine Saltwater Intrusion

Science.gov (United States)

Walther, Marc; Kolditz, Olaf; Grundmann, Jens; Liedl, Rudolf

2010-05-01

The optimization of an aquifer's "safe yield", especially within agriculturally used regions, is one of the fundamental tasks for nowaday's groundwater management. Due to the limited water ressources in arid regions, conflict of interests arise that need to be evaluated using scenario analysis and multicriterial optimization approaches. In the context of the government-financed research project "International Water Research Alliance Saxony" (IWAS), the groundwater quality for near-coastal, agriculturally used areas is investigated under the influence of marine saltwater intrusion. Within the near-coastal areas of the study region, i.e. the Batinah plains of Northern Oman, an increasing agricultural development could be observed during the recent decades. Simultaneously, a constant lowering of the groundwater table was registered, which is primarily due to the uncontrolled and unsupervised mining of the aquifers for the local agricultural irrigation. Intensively decreased groundwater levels, however, cause an inversion of the hydraulic gradient which is naturally aligned towards the coast. This, in turn,leads to an intrusion of marine saltwater flowing inland, endangering the productivity of farms near the coast. Utilizing the modeling software package OpenGeoSys, which has been developed and constantly enhanced by the Department of Environmental Informatics at the Helmholtz Centre for Environmental Research Leipzig (UFZ; Kolditz et al., 2008), a three-dimensional, density-dependent model including groundwater flow and mass transport is currently being built up. The model, comprehending three selected coastal wadis of interest, shall be used to investigate different management scenarios. The main focus of the groundwater modelling are the optimization of well positions and pumping schemes as well as the coupling with a surface runoff model, which is also used for the determination of the groundwater recharge due to wadi runoff downstream of retention dams. Based on

Natural and human-induced hypoxia and consequences for coastal areas: synthesis and future development

CSIR Research Space (South Africa)

Zhang, J

2010-01-01

Full Text Available and organic vs inorganic phosphorus (i.e. DOP vs DIP)] has been used to disentangle the effect of nutrients related to coastal eutrophication versus physical effects. The levels of NO?3 / NH + 4 and DIP/DOP over the broad shelf of East China Sea indicate... the replenishment of nutrients upwelled through the incursion of Kurosio Current across shelf-break, whereas in the eutrophic waters closer to the coast, ratios between oxidized and reduced forms as well as inorganic to organic forms of nitrogen and phosphorus...

Distribution of dissolved manganese in the Peruvian Upwelling and Oxygen Minimum Zone

Science.gov (United States)

Vedamati, Jagruti; Chan, Catherine; Moffett, James W.

2015-05-01

The geochemistry of manganese (Mn) in seawater is dominated by its redox chemistry, as Mn(II) is soluble and Mn(IV) forms insoluble oxides, and redox transformations are mediated by a variety of processes in the oceans. Dissolved Mn (DMn) accumulates under reducing conditions and is depleted under oxidizing conditions. Thus the Peruvian upwelling region, characterized by highly reducing conditions over a broad continental shelf and a major oxygen minimum zone extending far offshore, is potentially a large source of Mn to the eastern Tropical South Pacific. In this study, DMn was determined on cruises in October 2005 and February 2010 in the Peruvian Upwelling and Oxygen Minimum Zone, to evaluate the relationship between Mn, oxygen and nitrogen cycle processes. DMn concentrations were determined using simple dilution and matrix-matched external standardization inductively coupled mass spectrometry. Surprisingly, DMn was depleted under the most reducing conditions along the Peruvian shelf. Concentrations of dissolved Mn in surface waters increased offshore, indicating that advection of Mn offshore from the Peruvian shelf is a minor source. Subsurface Mn maxima were observed within the oxycline rather than within the oxygen minimum zone (OMZ), indicating they arise from remineralization of organic matter rather than reduction of Mn oxides. The distribution of DMn appears to be dominated by non-redox processes and inputs from the atmosphere and from other regions associated with specific water masses. Lower than expected DMn concentrations on the shelf probably reflect limited fluvial inputs from the continent and efficient offshore transport. This behavior is in stark contrast to Fe, reported in a companion study which is very high on the shelf and undergoes dynamic redox cycling.

Lagrangian Timescales of Southern Ocean Upwelling in a Hierarchy of Model Resolutions

Science.gov (United States)

Drake, Henri F.; Morrison, Adele K.; Griffies, Stephen M.; Sarmiento, Jorge L.; Weijer, Wilbert; Gray, Alison R.

2018-01-01

In this paper we study upwelling pathways and timescales of Circumpolar Deep Water (CDW) in a hierarchy of models using a Lagrangian particle tracking method. Lagrangian timescales of CDW upwelling decrease from 87 years to 31 years to 17 years as the ocean resolution is refined from 1° to 0.25° to 0.1°. We attribute some of the differences in timescale to the strength of the eddy fields, as demonstrated by temporally degrading high-resolution model velocity fields. Consistent with the timescale dependence, we find that an average Lagrangian particle completes 3.2 circumpolar loops in the 1° model in comparison to 0.9 loops in the 0.1° model. These differences suggest that advective timescales and thus interbasin merging of upwelling CDW may be overestimated by coarse-resolution models, potentially affecting the skill of centennial scale climate change projections.

Recent warming trend in the coastal region of Qatar

Science.gov (United States)

Cheng, Way Lee; Saleem, Ayman; Sadr, Reza

2017-04-01

The objective of this study was to analyze long-term temperature-related phenomena in the eastern portion of the Middle East, focusing on the coastal region of Qatar. Extreme temperature indices were examined, which were defined by the Expert Team on Climate Change Detection and Indices, for Doha, Qatar; these indices were then compared with those from neighboring countries. The trends were calculated for a 30-year period (1983-2012), using hourly data obtained from the National Climatic Data Center. The results showed spatially consistent warming trends throughout the region. For Doha, 11 of the 12 indices studied showed significant warming trends. In particular, the warming trends were represented by an increase in the number of warm days and nights and a decrease in the number of cool nights and days. The high-temperature extremes during the night have risen at more than twice the rate of their corresponding daytime extremes. The intensity and frequency of hot days have increased, and the minimum temperature indices exhibited a higher rate of warming. The climatic changes in Doha are consistent with the region-wide heat-up in recent decades across the Middle East. However, the rapid economic expansion, increase of population since the 1990s, and urban effects in the region are thought to have intensified the rapidly warming climate pattern observed in Doha since the turn of the century.

Impact of Biomass Burning Aerosols on Cloud Formation in Coastal Regions

Science.gov (United States)

Nair, U. S.; Wu, Y.; Reid, J. S.

2017-12-01

In the tropics, shallow and deep convective cloud structures organize in hierarchy of spatial scales ranging from meso-gamma (2-20 km) to planetary scales (40,000km). At the lower end of the spectrum is shallow convection over the open ocean, whose upscale growth is dependent upon mesoscale convergence triggers. In this context, cloud systems associated with land breezes that propagate long distances into open ocean areas are important. We utilized numerical model simulations to examine the impact of biomass burning on such cloud systems in the maritime continent, specifically along the coastal regions of Sarawak. Numerical model simulations conducted using the Weather Research and Forecasting Chemistry (WRF-Chem) model show spatial patterns of smoke that show good agreement to satellite observations. Analysis of model simulations show that, during daytime the horizontal convective rolls (HCRs) that form over land play an important role in organizing transport of smoke in the coastal regions. Alternating patterns of low and high smoke concentrations that are well correlated to the wavelengths of HCRs are found in both the simulations and satellite observations. During night time, smoke transport is modulated by the land breeze circulation and a band of enhanced smoke concentration is found along the land breeze front. Biomass burning aerosols are ingested by the convective clouds that form along the land breeze and leads to changes in total water path, cloud structure and precipitation formation.

Application of Landsat Thematic Mapper data for coastal thermal plume analysis at Diablo Canyon

Science.gov (United States)

Gibbons, D. E.; Wukelic, G. E.; Leighton, J. P.; Doyle, M. J.

1989-01-01

The possibility of using Landsat Thematic Mapper (TM) thermal data to derive absolute temperature distributions in coastal waters that receive cooling effluent from a power plant is demonstrated. Landsat TM band 6 (thermal) data acquired on June 18, 1986, for the Diablo Canyon power plant in California were compared to ground truth temperatures measured at the same time. Higher-resolution band 5 (reflectance) data were used to locate power plant discharge and intake positions and identify locations of thermal pixels containing only water, no land. Local radiosonde measurements, used in LOWTRAN 6 adjustments for atmospheric effects, produced corrected ocean surface radiances that, when converted to temperatures, gave values within approximately 0.6 C of ground truth. A contour plot was produced that compared power plant plume temperatures with those of the ocean and coastal environment. It is concluded that Landsat can provide good estimates of absolute temperatures of the coastal power plant thermal plume. Moreover, quantitative information on ambient ocean surface temperature conditions (e.g., upwelling) may enhance interpretation of numerical model prediction.

Desulfofrigus sp. prevails in sulfate-reducing dilution cultures from sediments of the Benguela upwelling area.

Science.gov (United States)

Kraft, Beate; Engelen, Bert; Goldhammer, Tobias; Lin, Yu-Shih; Cypionka, Heribert; Könneke, Martin

2013-04-01

Sediments of coastal upwelling areas are generally characterized by a high content of organic carbon that is mainly degraded via anaerobic microbial processes including sulfate reduction as a major terminal oxidation step. Despite the high importance of sulfate reduction in these sediments, the identity of sulfate-reducing bacteria (SRB) has remained almost unknown. Here, we applied a cultivation-based approach using selective enrichment conditions to study the diversity and distribution of active SRB in sediments along a transect perpendicular to the continental slope off the coast of Namibia (Meteor-cruise M76/1). To promote growth of the most abundant SRB, dilution series were prepared and amended with hydrogen, acetate, or a mixture of monomers representing typical substrates for SRB. Growth of SRB could be detected in the presence of all electron donors and from sediment down to 4 m depth. 16S rRNA gene-based DGGE analysis and sequencing revealed the predominance of SRB related to psychrophiles in particular to the genus Desulfofrigus, which made up 1 % of the total microbial community, accounting for an absolute abundance of up to 4.8 × 10(7)  cells mL(-1) . In general, the abundance of cultured SRB changed with depth and between the different sampling sites and correlated with the content of organic carbon as previously reported. Growth of chemolithotrophic SRB in relatively high dilution steps and the enrichment of methanogens as well as acetogens from deeper sediment point to a competition between hydrogen-utilizing microbial processes and their biogeochemical significance in deep sediment layers of the Benguela upwelling area. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Understanding Urban Communication in Information Era: Analyzing Development Progress of Coastal Territories in the Context of West Java’s Metropolitan Regions

Science.gov (United States)

Sutriadi, Ridwan; Indriyani Kurniasari, Meta

2017-07-01

This paper explores a consequence of metropolitan and development centers policy to the development progress of coastal territories by analyzing municipal website base on urban communication functions of communicative city concept. In terms of coastal territories as a part of development center, efforts have to be made in enhancing the role and function of municipal website to show their development progress. Perceptual analysis is taken as a method to measure their position, especially kabupaten/kota as coastal territories in regional context (West Java Province). The results indicate that the availability of public information in coastal territories cities lower than other cities in metropolitan area. Innovation in specifying coastal features has to be promoted in illustrating development progress of coastal territories as a part of development centers in West Java Province.

SCOR Working Group 137: "Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems": An introduction to the special issue of Estuarine, Coastal and Shelf Science

Science.gov (United States)

Paerl, Hans W.; Yin, Kedong; O'Brien, Todd D.

2015-09-01

Phytoplankton form the base of most aquatic food webs and play a central role in assimilation and processing of carbon and nutrients, including nitrogen, phosphorus, silicon, iron and a wide range of trace elements (Reynolds, 2006). In the marine environment, estuarine and coastal ecosystems (jointly termed coastal here) are among the most productive, resourceful and dynamic habitats on Earth (Malone et al., 1999; Day et al., 2012). These ecosystems constitute only ∼10% of the global oceans' surface, but account for over 30% of its primary production (Day et al., 2012). They process vast amounts of nutrients, sediments, carbonaceous, and xenobiotic compounds generated in coastal watersheds, in which approximately 70% of the world's human population resides (Nixon, 1995; Vitousek et al., 1997; NOAA, 2013). Estuarine and coastal ecosystems are also strongly influenced by localized nutrient enrichment from coastal upwelling, with major impacts on the structure and function of phytoplankton communities and the food webs they support (Legendre and Rassoulzadegan, 2012; Paerl and Justić, 2012). In addition, introductions and invasions of exotic plant and animal species have led to significant "top down" mediated changes in phytoplankton community structure and function (Carlton, 1999; Thompson, 2005). Lastly, the coastal zone is the "front line" of climatically-induced environmental change, including warming, altered rainfall patterns, intensities and magnitudes (Trenberth, 2005; IPCC, 2012), which jointly impact phytoplankton community structure and function (Cloern and Jassby, 2012; Hall et al., 2013). The combined effects of these pressures translate into a myriad of changes in phytoplankton production and community structure along geomorphological and geographic gradients (Fig. 1), with cascading quantitative and qualitative impacts on biogeochemical cycling, food web structure and function, water quality and overall resourcefulness and sustainability of these

Monitoring habitat restoration projects: U.S. Fish and Wildlife Service Pacific Region Partners for Fish and Wildlife Program and Coastal Program Protocol

Science.gov (United States)

Woodward, Andrea; Hollar, Kathy

2011-01-01

The U.S. Fish and Wildlife Service's (FWS) Pacific Region (Region 1) includes more than 158 million acres (almost 247,000 square miles) of land base in Idaho, Oregon, Washington, Hawai`i, the Commonwealth of the Northern Mariana Islands, American Samoa, Guam, the Republic of Palau, the Federated States of Micronesia, and the Republic of the Marshall Islands. Region 1 is ecologically diverse with landscapes that range from coral reefs, broadleaf tropical forests, and tropical savannahs in the Pacific Islands, to glacial streams and lakes, lush old-growth rainforests, inland fjords, and coastal shoreline in the Pacific Northwest, to the forested mountains, shrub-steppe desert, and native grasslands in the Inland Northwest. Similarly, the people of the different landscapes perceive, value, and manage their natural resources in ways unique to their respective regions and cultures. The Partners for Fish and Wildlife Program (Partners Program) and Coastal Program work with a variety of partners in Region 1 including individual landowners, watershed councils, land trusts, Soil and Water Conservation Districts, non-governmental organizations, Tribal governments, Native Hawaiian organizations, and local, State, and Federal agencies. The Partners Program is the FWS's vanguard for working with private landowners to voluntarily restore and conserve fish and wildlife habitat. Using non-regulatory incentives, the Partners Program engages willing partners to conserve and protect valuable fish and wildlife habitat on their property and in their communities. This is accomplished by providing the funding support and technical and planning tools needed to make on-the-ground conservation affordable, feasible, and effective. The primary goals of the Pacific Region Partners Program are to: Promote citizen and community-based stewardship efforts for fish and wildlife conservation Contribute to the recovery of at-risk species, Protect the environmental integrity of the National Wildlife

Study and mapping of natural hazards in the coastal zone of Murcia; Estudio y cartografia de los peligros naturales costeros de la region de Murcia

Energy Technology Data Exchange (ETDEWEB)

Seisdedos, J.; Mulas, J.; Gonzalez de Vallejo, L. I.; Rodriguez Franco, J. A.; Garcia, F. J.; Rio, L. del; Garrote, J.

2013-09-01

Despite the importance and implications of coastal hazards, very few studies have been focused on their analysis and mapping on a regional scale in a systematic and integrated way. This article presents a methodology based on the detailed analysis of natural hazards affecting coastal zones: floods, erosion, sea level rise, tsunamis, landslides, etc., and the study and mapping of the factors involved (coastal geomorphology, coastal processes, historical events, human activities). These factors and hazards are evaluated and integrated to prepare maps which include the assessments of each individual hazard and the overall ones. A mapping system in strips parallel to the coast is used, allowing the recognition and interpretation of the characteristics of the coast and the associated hazards. This methodology is applied to the coastal zone of Murcia, showing its usefulness for studying and mapping coastal hazards and its applicability to other regions. (Author)

Application of factor analysis and electrical resistivity to understand groundwater contributions to coastal embayments in semi-arid and hypersaline coastal settings

Energy Technology Data Exchange (ETDEWEB)

Bighash, Paniz, E-mail: Bighash.p@gmail.com; Murgulet, Dorina

2015-11-01

Groundwater contributions and sources of salinity to Oso Bay in south Texas were investigated using multivariate statistical analysis of geochemical data and multitemporal electrical resistivity tomography surveys. Both analysis of geochemical data and subsurface imaging techniques identified two commonalities for the investigated system: 1) hypersaline water occurs near the groundwater/surface water interface during wet conditions creating reverse hydraulic gradients due to density effects. The development and downward movement of these fluids as continuous plumes deflect fresher groundwater discharge downward and laterally away from the surface; and 2) more pronounced upwelling of fresher groundwater occurs during drought periods when density inversions are more defined and are expected to overcome dispersion and diffusion processes and create sufficiently large-enough unstable gradients that induce density-difference convection. Salinity mass-balance models derived from time-difference resistivity tomograph and in-situ salinity data reaffirm these findings indicating that groundwater upwelling is more prominent during dry to wet conditions in 2013 (~ 545.5 m{sup 3}/d) and is less pronounced during wet to dry conditions in 2012 (~ 262.7 m{sup 3}/d) for the 224 m{sup 2} area surveyed. Findings show that the highly saline nature of water in this area and changes in salinity regimes can be attributed to a combination of factors, namely: surface outflows, evapoconcentration, recirculation of hypersaline groundwaters, and potential trapped oil field brines. Increased drought conditions will likely exacerbate the rate at which salinity levels are increasing in bays and estuaries in semi-arid regions where both hypersaline groundwater discharge and high evaporation rates occur simultaneously. - Highlights: • Study of salinity regimes in relation to groundwater in a coastal semiarid setting • Factor analysis defined dominant factors influencing water quality

Application of factor analysis and electrical resistivity to understand groundwater contributions to coastal embayments in semi-arid and hypersaline coastal settings

International Nuclear Information System (INIS)

Bighash, Paniz; Murgulet, Dorina

2015-01-01

Groundwater contributions and sources of salinity to Oso Bay in south Texas were investigated using multivariate statistical analysis of geochemical data and multitemporal electrical resistivity tomography surveys. Both analysis of geochemical data and subsurface imaging techniques identified two commonalities for the investigated system: 1) hypersaline water occurs near the groundwater/surface water interface during wet conditions creating reverse hydraulic gradients due to density effects. The development and downward movement of these fluids as continuous plumes deflect fresher groundwater discharge downward and laterally away from the surface; and 2) more pronounced upwelling of fresher groundwater occurs during drought periods when density inversions are more defined and are expected to overcome dispersion and diffusion processes and create sufficiently large-enough unstable gradients that induce density-difference convection. Salinity mass-balance models derived from time-difference resistivity tomograph and in-situ salinity data reaffirm these findings indicating that groundwater upwelling is more prominent during dry to wet conditions in 2013 (~ 545.5 m 3 /d) and is less pronounced during wet to dry conditions in 2012 (~ 262.7 m 3 /d) for the 224 m 2 area surveyed. Findings show that the highly saline nature of water in this area and changes in salinity regimes can be attributed to a combination of factors, namely: surface outflows, evapoconcentration, recirculation of hypersaline groundwaters, and potential trapped oil field brines. Increased drought conditions will likely exacerbate the rate at which salinity levels are increasing in bays and estuaries in semi-arid regions where both hypersaline groundwater discharge and high evaporation rates occur simultaneously. - Highlights: • Study of salinity regimes in relation to groundwater in a coastal semiarid setting • Factor analysis defined dominant factors influencing water quality variations. �

Natural and human-induced hypoxia and consequences for coastal areas: synthesis and future development

Directory of Open Access Journals (Sweden)

J. Zhang

2010-05-01

Full Text Available Hypoxia has become a world-wide phenomenon in the global coastal ocean and causes a deterioration of the structure and function of ecosystems. Based on the collective contributions of members of SCOR Working Group #128, the present study provides an overview of the major aspects of coastal hypoxia in different biogeochemical provinces, including estuaries, coastal waters, upwelling areas, fjords and semi-enclosed basins, with various external forcings, ecosystem responses, feedbacks and potential impact on the sustainability of the fishery and economics. The obvious external forcings include freshwater runoff and other factors contributing to stratification, organic matter and nutrient loadings, as well as exchange between coastal and open ocean water masses. Their different interactions set up mechanisms that drive the system towards hypoxia. Coastal systems also vary in their relative susceptibility to hypoxia depending on their physical and geographic settings. It is understood that coastal hypoxia has a profound impact on the sustainability of ecosystems, which can be seen, for example, by the change in the food-web structure and system function; other influences include compression and loss of habitat, as well as changes in organism life cycles and reproduction. In most cases, the ecosystem responds to the low dissolved oxygen in non-linear ways with pronounced feedbacks to other compartments of the Earth System, including those that affect human society. Our knowledge and previous experiences illustrate that there is a need to develop new observational tools and models to support integrated research of biogeochemical dynamics and ecosystem behavior that will improve confidence in remediation management strategies for coastal hypoxia.

Natural and human-induced hypoxia and consequences for coastal areas: synthesis and future development

Science.gov (United States)

Zhang, J.; Gilbert, D.; Gooday, A. J.; Levin, L.; Naqvi, S. W. A.; Middelburg, J. J.; Scranton, M.; Ekau, W.; Peña, A.; Dewitte, B.; Oguz, T.; Monteiro, P. M. S.; Urban, E.; Rabalais, N. N.; Ittekkot, V.; Kemp, W. M.; Ulloa, O.; Elmgren, R.; Escobar-Briones, E.; van der Plas, A. K.

2010-05-01

Hypoxia has become a world-wide phenomenon in the global coastal ocean and causes a deterioration of the structure and function of ecosystems. Based on the collective contributions of members of SCOR Working Group #128, the present study provides an overview of the major aspects of coastal hypoxia in different biogeochemical provinces, including estuaries, coastal waters, upwelling areas, fjords and semi-enclosed basins, with various external forcings, ecosystem responses, feedbacks and potential impact on the sustainability of the fishery and economics. The obvious external forcings include freshwater runoff and other factors contributing to stratification, organic matter and nutrient loadings, as well as exchange between coastal and open ocean water masses. Their different interactions set up mechanisms that drive the system towards hypoxia. Coastal systems also vary in their relative susceptibility to hypoxia depending on their physical and geographic settings. It is understood that coastal hypoxia has a profound impact on the sustainability of ecosystems, which can be seen, for example, by the change in the food-web structure and system function; other influences include compression and loss of habitat, as well as changes in organism life cycles and reproduction. In most cases, the ecosystem responds to the low dissolved oxygen in non-linear ways with pronounced feedbacks to other compartments of the Earth System, including those that affect human society. Our knowledge and previous experiences illustrate that there is a need to develop new observational tools and models to support integrated research of biogeochemical dynamics and ecosystem behavior that will improve confidence in remediation management strategies for coastal hypoxia.

Coastal Economic Trends for Coastal Geographies

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These market data provide a comprehensive set of measures of changes in economic activity throughout the coastal regions of the United States. In regard to the...

Artificial upwelling using offshore wind energy for mariculture applications

Directory of Open Access Journals (Sweden)

Álvaro Viúdez

2016-09-01

Full Text Available Offshore wind is proposed as an energy source to upwell nutrient-rich deep water to the ocean photic layers. A spar-buoy wind turbine with a rigid tube about 300 m long is proposed as a pipe to drive deep water up to the surface. The minimum energy required to uplift the water is the potential energy difference between surface waters inside and outside the pipe, which depends on the background density profile. The corresponding surface jump or hydraulic head, h, calculated for several analytical and experimental density profiles, is of the order of 10 cm. If the complete turbine power (of the order of several MW is used for raising the water (assuming a 100% pump efficiency, in a frictionless flow, very large water volumes, of the order of thousands of m3 s-1, will be transported to the photic layers. In a more realistic case, taking into account pipe friction in wide pipes, of the order of 10 m radius, and a power delivered to the fluid of 1 MW, the volume transport is still very large, about 500 m3 s-1. However, such a large amount of dense water could sink fast to aphotic layers due to vertical static instability (the fountain effect, ruining the enhancement of primary production. Hence, some ways to increase the turbulent entrainment and avoid the fountain effect are proposed. From the energetic viewpoint, artificial upwelling using offshore wind energy is a promising way to fertilize large open sea regions. This mariculture application is, however, severely subjected to atmosphere and ocean climatology, as well as to ecological dynamics. The general problem is multidisciplinary, and some important physical, engineering and ecological questions need to be seriously addressed to improve our confidence in the approach presented here.

Diurnal variability of inner-shelf circulation in the lee of a cape under upwelling conditions

Science.gov (United States)

Lamas, L.; Peliz, A.; Dias, J.; Oliveira, P. B.; Angélico, M. M.; Castro, J. J.; Fernandes, J. N.; Trindade, A.; Cruz, T.

2017-07-01

The nearshore circulation in the lee of a cape under upwelling conditions was studied using in-situ data from 3 consecutive summers (2006-2008). Focus was given to a period between 20 July and 04 August 2006 to study the diurnal variability of the cross-shelf circulation. This period was chosen because it had a steady upwelling-favourable wind condition modulated by a diurnal cycle much similar to sea breeze. The daily variability of the observed cross-shelf circulation consisted of three distinct periods: a morning period with a 3-layer vertical structure with onshore velocities at mid-depth, a mid-day period where the flow is reversed and has a 2-layer structure with onshore velocities at the surface and offshore flow below, and, lastly, in the evening, a 2-layer period with intensified offshore velocities at the surface and onshore flow at the bottom. The observed cross-shelf circulation showed a peculiar vertical shape and diurnal variability different from several other systems described in literature. We hypothesize that the flow reversal of the cross-shelf circulation results as a response to the rapid change of the wind magnitude and direction at mid-day with the presence of the cape north of the mooring site influencing this response. A numerical modelling experiment exclusively forced by winds simulated successfully most of the circulation at the ADCP site, especially the mid-day reversal and the evening's upwelling-type structure. This supports the hypothesis that the cross-shelf circulation at diurnal timescales is mostly wind-driven. By analysing the 3D circulation in the vicinity of Cape Sines we came to the conclusion that the diurnal variability of the wind and the flow interaction with topography are responsible for the circulation variability at the ADCP site, though only a small region in the south of the cape showed a similar diurnal variability. The fact that the wind diurnally undergoes relaxation and intensification strongly affects the

Coastal ecosystems, productivity and ecosystem protection: Coastal ecosystem management

International Nuclear Information System (INIS)

Ngoile, M.A.K.; Horrill, C.J.

1993-01-01

The coastal zone is a complex ecosystem under the influence of physical, chemical and biological processes. Under natural conditions these processes interact and maintain an equilibrium in the coastal ecosystem. Man makes a variety of important uses of coastal resources, ranging from harvesting of living resources, extraction of nonliving resources, and recreation, to the disposal of wastes. Man's extensive use of the oceans introduces factors which bring about an imbalance in the natural processes, and may result in harmful and hazardous effects to life hindering further use. Man's pressure on the resources of the coastal zone is already manifest and will increase manifold. This calls for an immediate solution to the protection and sustainable use of coastal resources. The current sectorized approach to the management of human activities will not solve the problem because the different resources of the coastal zone interact in such a manner that disturbances in one cause imbalance in the others. This is further complicated by the sectorized approach to research and limited communication between policy makers, managers, and scientists. This paper discusses strategies for managing coastal-resources use through an integrated approach. The coastal zone is presented as a unified ecosystem in equilibrium and shows that man's extensive use of the coastal resources destabilizes this equilibrium. Examples from the East Africa Region are presented. 15 refs, 2 figs, 3 tabs

SCREENING OF BIOSURFACTANT PRODUCTION BY BACILLUS SP ISOLATED FROM COASTAL REGION IN CUDDALORE TAMILNADU

OpenAIRE

Bhuvaneswari. M*and P. Sivagurunathan

2016-01-01

Marine microorganisms produce extracellular or membrane associated surface-active compounds (bio surfactants). Biosurfactant are organic compounds belonging to various classes including glycolipids, lipopeptides, fatty acids, phospholipids that reduce the interfacial tension between immiscible liquids.This study deals with production and characterization of biosurfactant from Bacillus sp. The efficiency of Bacillus spstrain isolated from a marine sediments soil sample from coastal region -Cud...

Preparing to predict: The Second Autonomous Ocean Sampling Network (AOSN-II) experiment in the Monterey Bay

Science.gov (United States)

Ramp, S. R.; Davis, R. E.; Leonard, N. E.; Shulman, I.; Chao, Y.; Robinson, A. R.; Marsden, J.; Lermusiaux, P. F. J.; Fratantoni, D. M.; Paduan, J. D.; Chavez, F. P.; Bahr, F. L.; Liang, S.; Leslie, W.; Li, Z.

2009-02-01

The Autonomous Ocean Sampling Network Phase Two (AOSN-II) experiment was conducted in and offshore from the Monterey Bay on the central California coast during July 23-September 6, 2003. The objective of the experiment was to learn how to apply new tools, technologies, and analysis techniques to adaptively sample the coastal ocean in a manner demonstrably superior to traditional methodologies, and to use the information gathered to improve predictive skill for quantities of interest to end-users. The scientific goal was to study the upwelling/relaxation cycle near an open coastal bay in an eastern boundary current region, particularly as it developed and spread from a coastal headland. The suite of observational tools used included a low-flying aircraft, a fleet of underwater gliders, including several under adaptive autonomous control, and propeller-driven AUVs in addition to moorings, ships, and other more traditional hardware. The data were delivered in real time and assimilated into the Harvard Ocean Prediction System (HOPS), the Navy Coastal Ocean Model (NCOM), and the Jet Propulsion Laboratory implementation of the Regional Ocean Modeling System (JPL/ROMS). Two upwelling events and one relaxation event were sampled during the experiment. The upwelling in both cases began when a pool of cold water less than 13 °C appeared near Cape Año Nuevo and subsequently spread offshore and southward across the bay as the equatorward wind stress continued. The primary difference between the events was that the first event spread offshore and southward, while the second event spread only southward and not offshore. The difference is attributed to the position and strength of meanders and eddies of the California Current System offshore, which blocked or steered the cold upwelled water. The space and time scales of the mesoscale variability were much shorter than have been previously observed in deep-water eddies offshore. Additional process studies are needed to elucidate

Dynamics of oxygen depletion in the nearshore of a coastal embayment of the southern Benguela upwelling system

CSIR Research Space (South Africa)

Pitcher, GC

2014-04-01

Full Text Available is characterized by seasonally recurrent hypoxia (<1.42 ml l(sup-1)) associated with a deep pool of oxygen-depleted water and episodic anoxia (<0.02 ml l(sup-1)) driven by the nearshore (<20 m isobath) decay of red tide. Coastal wind forcing influences DO...

Proceedings of a workshop on coastal impacts and adaptation related to climate change : the C-CIARN Coastal Node

International Nuclear Information System (INIS)

2001-03-01

Coastal zones are sensitive to increases in air, sea and ground temperatures as well as to variations in sea level, precipitation, ice thickness, and storm intensity. In order to address concerns regarding climate change in coastal areas, the government of Canada established a Coastal Node as part of the Canadian Climate Impact and Adaptation Research Network (C-CIARN). The role of C-CIARN Coastal Node was recently outlined in a workshop aimed at providing guidelines and research priorities for stakeholders from all coastal regions of Canada. The workshop considered the integration of the node function with one or more of the regional nodes or with the fisheries node. Topics of discussion included both direct impacts on coastal infrastructure or human-use activities as well as indirect impacts resulting from changes in the ecosystem. refs., tabs

Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context – a multi-proxy approach

Directory of Open Access Journals (Sweden)

S. Meisel

2011-08-01

Full Text Available The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (δ15N, δ13C and productivity proxies (accumulation rates of total organic carbon; ARTOC. Reconstructed sea surface temperatures (alkenone-derived SST and temperatures at subsurface depths (Tδ18O; based on tests of planktonic foraminifers reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1 over centennial (core 178 to millennial scale (core 226620. The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and Tδ18O proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. Tδ18O records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or

Southern Alaska Coastal Relief Model

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building coastal-relief models (CRM) for select U.S. coastal regions. Bathymetric, topographic, and shoreline data...

NOAA's Coastal Change Analysis Program (C-CAP) 2010 Forest Fragmentation Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 2006 Forest Fragmentation Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1985 Forest Fragmentation Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

NOAA's Coastal Change Analysis Program (C-CAP) 1996 Forest Fragmentation Data - Coastal United States

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Change Analysis Program (C-CAP) produces national standardized land cover and change products for the coastal regions of the U.S. C-CAP products...

Tsunami induced transportation of the coastal marine sediments to distant onshore regions: Some indications from foraminiferal and microbenthic studies of new Wandoor region (Andaman & Nicobar)

Digital Repository Service at National Institute of Oceanography (India)

Khare, N.; Chaturvedi, S.K.; Ingole, B.S.

regions near New Wandoor (Andaman and Nicobar) suggested the areal extent of marine transgression due to tsunami waves on December 26, 2004. There is a need to investigate coastal marine sediments with multi-disciplinary approach to understnd impact...

Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

Directory of Open Access Journals (Sweden)

Barbara Neumann

Full Text Available Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential

Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

Science.gov (United States)

Neumann, Barbara; Vafeidis, Athanasios T; Zimmermann, Juliane; Nicholls, Robert J

2015-01-01

Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we

Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding - A Global Assessment

Science.gov (United States)

Neumann, Barbara; Vafeidis, Athanasios T.; Zimmermann, Juliane; Nicholls, Robert J.

2015-01-01

Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we

Climatic variability and trends in the surface waters of coastal British Columbia

Science.gov (United States)

Cummins, Patrick F.; Masson, Diane

2014-01-01

Multi-decadal records of monthly sea surface temperature (SST) and sea surface salinity (SSS) collected at a set of lighthouse stations are used to examine climatic variability and trends in the coastal waters of British Columbia. Particular attention is given to relations between the water property anomalies and variability in coastal freshwater discharge and alongshore wind stress. Within the Strait of Georgia, SSS anomalies are closely related to Fraser River discharge anomalies. Along the Pacific coast, anomalies in alongshore wind stress and freshwater runoff have the characteristics of white noise processes. A cross-correlation analysis demonstrates that SST and SSS variability along the open west coast is consistent with the response of a first-order autoregressive process driven by anomalous alongshore wind stress and coastal freshwater discharge, respectively. Thus climatic variability of SST and SSS along the Pacific coast of British Columbia occurs, in part, through the integration of noisy atmospheric forcing and coastal precipitation. Seasonal correlations show that SST is strongly related to wind stress during winter and fall. Conversely, SSS is relatively weakly related to the alongshore wind during spring, suggesting that variability in upwelling makes only a modest contribution to variability of SSS in the nearshore environment. Consistent with previous studies, secular trends indicate long-term warming and freshening of the coastal ocean at most stations. It is shown that long-term SST trends can be obscured by the pronounced climatic variability of these waters, requiring that time series extend for several decades to be reliably detected.

Twitter Analytics: Are the U.S. Coastal Regions Prepared for Climate Change in 2017?

Science.gov (United States)

Singleton, S. L.; Kumar, S.

2017-12-01

According to the U.S. National Climate Assessment, the Southeast Coast and Gulf Coast of the United States are particularly susceptible to sea level rise, heat waves, hurricanes and less accessibility to clean water due to climate change. This is because of the extreme variation of topography in these two regions. Preparation for climate change consequences can only occur with conversation, which is a method of bringing awareness to the issue. Over the past decade, social media has taken over the spectrum of information exchange in the United States. Social Network Analysis (SNA) is a field that is emerging with the growth in popularity of social media. SNA is the practice of analyzing trends in volume and opinion of a population of social media users. Twitter, one popular social media platform, is one of the largest microblogging sites in the world, and it provides an abundance of data related to the trending topics such as climate change. Twitter analytics is a type of SNA performed on data from the tweets of Twitter users. In this work, Twitter analytics is performed on the data generated from the Twitter users in the United States, who were talking about climate change, global warming and/or CO2, over the course of one year (July 2016 - June 2017). Specifically, a regional comparative analysis on the coastal U.S. regions was conducted to recognize which region(s) is/are falling behind on the conversation about climate change. Sentiment analysis was also performed to understand the trends in opinion about climate change that vary over time. Experimental results determined that the southeast coast of the United States is deficient in their discussion about climate change compared to the other coastal regions. Igniting the conversation about this issue in these regions will mitigate the disasters due to climate change by increasing awareness in the people of these regions so they can properly prepare.

Activity and phylogenetic diversity of bacterial cells with high and low nucleic acid content and electron transport system activity in an upwelling ecosystem.

Science.gov (United States)

Longnecker, K; Sherr, B F; Sherr, E B

2005-12-01

We evaluated whether bacteria with higher cell-specific nucleic acid content (HNA) or an active electron transport system, i.e., positive for reduction of 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), were responsible for the bulk of bacterioplankton metabolic activity. We also examined whether the phylogenetic diversity of HNA and CTC-positive cells differed from the diversity of Bacteria with low nucleic acid content (LNA). Bacterial assemblages were sampled both in eutrophic shelf waters and in mesotrophic offshore waters in the Oregon coastal upwelling region. Cytometrically sorted HNA, LNA, and CTC-positive cells were assayed for their cell-specific [3H]leucine incorporation rates. Phylogenetic diversity in sorted non-radioactively labeled samples was assayed using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes. Cell-specific rates of leucine incorporation of HNA and CTC-positive cells were on average only slightly greater than the cell-specific rates of LNA cells. HNA cells accounted for most bacterioplankton substrate incorporation due to high abundances, while the low abundances of CTC-positive cells resulted in only a small contribution by these cells to total bacterial activity. The proportion of the total bacterial leucine incorporation attributable to LNA cells was higher in offshore regions than in shelf waters. Sequence data obtained from DGGE bands showed broadly similar phylogenetic diversity across HNA, LNA, and CTC-positive cells, with between-sample and between-region variability in the distribution of phylotypes. Our results suggest that LNA bacteria are not substantially different from HNA bacteria in either cell-specific rates of substrate incorporation or phylogenetic composition and that they can be significant contributors to bacterial metabolism in the sea.

Author Details

African Journals Online (AJOL)

Preliminary annual estimates of regional nitrate supply in the southern Benguela using coastal sea level fluctuations as a proxy for upwelling. Abstract PDF · Vol 18 (1997) - Articles Anchovy biomass is linked to annual potential new production in the southern Benguela: support for the “Optimal environmental window” ...

Nutrient pumping by submesoscale circulations in the mauritanian upwelling system

Science.gov (United States)

Hosegood, P. J.; Nightingale, P. D.; Rees, A. P.; Widdicombe, C. E.; Woodward, E. M. S.; Clark, D. R.; Torres, R. J.

2017-12-01

Observations made within a cold filament in the Mauritanian upwelling system demonstrate that intense submesoscale circulations at the peripheral edges of the filament are likely responsible for anomalously high levels of observed primary productivity by resupplying nutrients to the euphotic zone. Measurements made on the shelf within the recently upwelled water reveal that primary production (PP) of 8.2 gC/m-2 day-1 was supported by nitrate concentrations (NC) of 8 mmol m-3. Towards the front that defined the edge of the filament containing the upwelled water as it was transported offshore, PP dropped to 1.6 gC m-2 day-1 whilst NC dropped to 5.5 mmol m-3. Thus, whilst the observed nutrients on the shelf accounted for 90% of new production, this value dropped to ∼60% near the filament's front after accounting for vertical turbulent fluxes and Ekman pumping. We demonstrate that the N15 was likely to have been supplied at the front by submesoscale circulations that were directly measured as intense vertical velocities ⩾100 m day-1 by a drifting acoustic Doppler current profiler that crossed a submesoscale surface temperature front. At the same time, a recently released tracer was subducted out of the mixed layer within 24 h of release, providing direct evidence that the frontal circulations were capable of accessing the reservoir of nutrients beneath the pycnocline. The susceptibility of the filament edge to submesoscale instabilities was demonstrated by O(1) Rossby numbers at horizontal scales of 1-10 km. The frontal circulations are consistent with instabilities arising from a wind-driven nonlinear Ekman buoyancy flux generated by the persistent northerly wind stress that has a down-front component at the northern edge of the inshore section of the filament. The prevalence of submesoscale instabilities and their associated vertical circulations are proposed to be a key mechanism operating at sub-grid scales and sustaining new production throughout the upwelling

Picoplankton Bloom in Global South? A High Fraction of Aerobic Anoxygenic Phototrophic Bacteria in Metagenomes from a Coastal Bay (Arraial do Cabo--Brazil).

Science.gov (United States)

Cuadrat, Rafael R C; Ferrera, Isabel; Grossart, Hans-Peter; Dávila, Alberto M R

2016-02-01

Marine habitats harbor a great diversity of microorganism from the three domains of life, only a small fraction of which can be cultivated. Metagenomic approaches are increasingly popular for addressing microbial diversity without culture, serving as sensitive and relatively unbiased methods for identifying and cataloging the diversity of nucleic acid sequences derived from organisms in environmental samples. Aerobic anoxygenic phototrophic bacteria (AAP) play important roles in carbon and energy cycling in aquatic systems. In oceans, those bacteria are widely distributed; however, their abundance and importance are still poorly understood. The aim of this study was to estimate abundance and diversity of AAPs in metagenomes from an upwelling affected coastal bay in Arraial do Cabo, Brazil, using in silico screening for the anoxygenic photosynthesis core genes. Metagenomes from the Global Ocean Sample Expedition (GOS) were screened for comparative purposes. AAPs were highly abundant in the free-living bacterial fraction from Arraial do Cabo: 23.88% of total bacterial cells, compared with 15% in the GOS dataset. Of the ten most AAP abundant samples from GOS, eight were collected close to the Equator where solar irradiation is high year-round. We were able to assign most retrieved sequences to phylo-groups, with a particularly high abundance of Roseobacter in Arraial do Cabo samples. The high abundance of AAP in this tropical bay may be related to the upwelling phenomenon and subsequent picoplankton bloom. These results suggest a link between upwelling and light abundance and demonstrate AAP even in oligotrophic tropical and subtropical environments. Longitudinal studies in the Arraial do Cabo region are warranted to understand the dynamics of AAP at different locations and seasons, and the ecological role of these unique bacteria for biogeochemical and energy cycling in the ocean.

Managing saltwater intrusion in coastal arid regions and its societal implications for agriculture

Directory of Open Access Journals (Sweden)

J. Grundmann

2016-05-01

Full Text Available Coastal aquifers in arid and semiarid regions are particularly at risk due to intrusion of salty marine water. Since groundwater is predominantly used in irrigated agriculture, its excessive pumping – above the natural rate of replenishment – strengthen the intrusion process. Using this increasingly saline water for irrigation, leads to a destruction of valuable agricultural resources and the economic basis of farmers and their communities. The limitation of resources (water and soil in these regions requires a societal adaptation and change in behaviour as well as the development of appropriate management strategies for a transition towards stable and sustainable future hydrosystem states. Besides a description of the system dynamics and the spatial consequences of adaptation on the resources availability, the contribution combines results of an empirical survey with stakeholders and physically based modelling of the groundwater-agriculture hydrosystem interactions. This includes an analysis of stakeholders' (farmers and decision makers behaviour and opinions regarding several management interventions aiming on water demand and water resources management as well as the thinking of decision makers how farmers will behave. In this context, the technical counter measures to manage the saltwater intrusion by simulating different groundwater pumping strategies and scenarios are evaluated from the economic and social point of view and if the spatial variability of the aquifer's hydrogeology is taken into consideration. The study is exemplarily investigated for the south Batinah region in the Sultanate of Oman, which is affected by saltwater intrusion into a coastal aquifer system due to excessive groundwater withdrawal for irrigated agriculture.

Regional Interdependence in Adaptation to Sea Level Rise and Coastal Flooding

Science.gov (United States)

Stacey, M. T.; Lubell, M.; Hummel, M.; Wang, R. Q.; Barnard, P.; Erikson, L. H.; Herdman, L.; Pozdnukhov, A.; Sheehan, M.

2017-12-01

Projections of sea level rise may differ in the pace of change, but there is clear consensus that coastal communities will be facing more frequent and severe flooding events in the coming century. As communities adapt to future conditions, infrastructure systems will be developed, modified and abandoned, with important consequences for services and resilience. Whether action or inaction is pursued, the decisions made by an individual community regarding a single infrastructure system have implications that extend spatially and temporally due to geographic and infrastructure system interactions. At the same time, there are a number of barriers to collective or coordinated action that inhibit regional solutions. This interplay between local actions and regional responses is one of the great challenges facing decision-makers grappling with both local and regional climate-change adaptation. In this talk, I present case studies of the San Francisco Bay Area that examine how shoreline infrastructure, transporation sytems and decision-making networks interact to define the regional response to local actions and the local response to regional actions. I will characterize the barriers that exist to regional solutions, and characterize three types of interdependence that may motivate decision-makers to overcome those barriers. Using these examples, I will discuss the importance of interdisciplinary analyses that integrate the natural sciences, engineering and the social science to climate change adaptation more generally.

Intraseasonal patterns in coastal plankton biomass off central Chile derived from satellite observations and a biochemical model

Science.gov (United States)

Gomez, Fabian A.; Spitz, Yvette H.; Batchelder, Harold P.; Correa-Ramirez, Marco A.

2017-10-01

Subseasonal (5-130 days) environmental variability can strongly affect plankton dynamics, but is often overlooked in marine ecology studies. We documented the main subseasonal patterns of plankton biomass in the coastal upwelling system off central Chile, the southern part of the Humboldt System. Subseasonal variability was extracted from temporal patterns in satellite data of wind stress, sea surface temperature, and chlorophyll from the period 2003-2011, and from a realistically forced eddy-resolving physical-biochemical model from 2003 to 2008. Although most of the wind variability occurs at submonthly frequencies (< 30 days), we found that the dominant subseasonal pattern of phytoplankton biomass is within the intraseasonal band (30-90 days). The strongest intraseasonal coupling between wind and plankton is in spring-summer, when increased solar radiation enhances the phytoplankton response to upwelling. Biochemical model outputs show intraseasonal shifts in plankton community structure, mainly associated with the large fluctuations in diatom biomass. Diatom biomass peaks near surface during strong upwelling, whereas small phytoplankton biomass peaks at subsurface depths during relaxation or downwelling periods. Strong intraseasonally forced changes in biomass and species composition could strongly impact trophodynamics connections in the ecosystem, including the recruitment of commercially important fish species such as common sardine and anchovy. The wind-driven variability of chlorophyll concentration was connected to mid- and high-latitude atmospheric anomalies, which resemble disturbances with frequencies similar to the tropical Madden-Julian Oscillation.

Monitoring and Management of Karstic Coastal Groundwater in a Changing Environment (Southern Italy: A Review of a Regional Experience

Directory of Open Access Journals (Sweden)

Maurizio Polemio

2016-04-01

Full Text Available The population concentration in coastal areas and the increase of groundwater discharge in combination with the peculiarities of karstic coastal aquifers constitute a huge worldwide problem, which is particularly relevant for coastal aquifers of the Mediterranean basin. This paper offers a review of scientific activities realized to pursue the optimal utilization of Apulian coastal groundwater. Apulia, with a coastline extending for over 800 km, is the Italian region with the largest coastal karst aquifers. Apulian aquifers have suffered both in terms of water quality and quantity. Some regional regulations were implemented from the 1970s with the purpose of controlling the number of wells, well locations, and well discharge. The practical effects of these management criteria, the temporal and spatial trend of recharge, groundwater quality, and seawater intrusion effects are discussed based on long-term monitoring. The efficacy of existing management tools and the development of predictive scenarios to identify the best way to reconcile irrigation and demands for high-quality drinking water have been pursued in a selected area. The Salento peninsula was selected as the Apulian aquifer portion exposed to the highest risk of quality degradation due to seawater intrusion. The capability of large-scale numerical models in groundwater management was tested, particularly for achieving forecast scenarios to evaluate the impacts of climate change on groundwater resources. The results show qualitative and quantitative groundwater trends from 1930 to 2060 and emphasize the substantial decrease of the piezometric level and a serious worsening of groundwater salinization due to seawater intrusion.

Four large coastal upwelling areas are created by eastern boundary ...

African Journals Online (AJOL)

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large deep-water hake Merluccius paradoxus, 2.7% small M. paradoxus, 1.3% ... hake in the Benguela region, the shallow-water species. Merluccius capensis .... sharks are not included in the estimate, and neither is the proportion of sharks ...

Perceptions of Village Dogs by Villagers and Tourists in the Coastal Region of Rural Oaxaca, Mexico

NARCIS (Netherlands)

Ruiz Izaguirre, E.; Eilers, C.H.A.M.

2012-01-01

The objective of this study was to gain an understanding of the village dog-keeping system, and of perceptions of dog-related problems by villagers and tourists, in the coastal region of Oaxaca, Mexico. We conducted a survey of the inhabitants of three villages (Mazunte, Puerto Angel, and Río Seco),

Internal structure of the upwelling events at Punta Gallinas (Colombian Caribbean) from modis-sst imagery

Science.gov (United States)

Alonso, J.; Blázquez, E.; Isaza-Toro, E.; Vidal, J.

2015-10-01

The upwelling at Punta Gallinas in the Guajira Peninsula (Colombian Caribbean) was studied from the point of view of the Mathematical Morphology using 10 years of monthly composite MODIS-SST imagery. Among all the morphological operators, the skeleton is widely used to compute the axis of the of the SST fields for the observed upwelling events. The skeleton is characterized by means of the Geometrical Theory of Measurement using the fractal dimension. The upwelling in the area is driven by the dynamic of the ITCZ (InterTropical Convergence Zone) and the relationship between the area and the East-West component of the trade winds has a lag of about 4 months. It has been found that the fractal dimension of the skeleton and the area of the upwelling are related. Some relationship was found between the fractal dimension of the skeleton (its complexity) and the Southern Oscillation Index by means of linear regression and cross-spectral analysis finding coherent energy at 1 year, 6 months and in the low frequency band. Finally, a sensitivity analysis between fractal dimension and threshold SST points out to take an extreme care at the time of fixing the last one.

Living with the Risks of Cyclone Disasters in the South-Western Coastal Region of Bangladesh

Directory of Open Access Journals (Sweden)

Bishawjit Mallick

2017-02-01

Full Text Available Bangladesh is one of the most disaster prone countries in the world. Cyclone disasters that affect millions of people, destroy homesteads and livelihoods, and trigger migration are common in the coastal region of Bangladesh. The aim of this article is to understand how the coastal communities in Bangladesh deal with the continuous threats of cyclones. As a case study, this study investigates communities that were affected by the Cyclone Sidr in 2007 and Cyclone Aila in 2009, covering 1555 households from 45 coastal villages in the southwestern region of Bangladesh. The survey method incorporated household based questionnaire techniques and community based focus group discussions. The pre-event situation highlights that the affected communities were physically vulnerable due to the strategic locations of the cyclone shelters nearer to those with social supreme status and the location of their houses in relatively low-lying lands. The victims were also socio-economically vulnerable considering the high rate of illiteracy, larger family size, no ownership of land, and extreme poverty. They were mostly day labourers, farmers, and fishermen. Post-event situation reveals that the victims’ houses and livelihoods were severely damaged or destroyed. Most victims were forced to shift their occupations (e.g., from farmers to fishermen, and many became unemployed. They also became heavily dependent on micro-credits and other forms of loans. A significant number of people were displaced and migrated to large urban agglomerations in search of livelihoods to maintain their families back in the affected villages. Migration was primarily undertaken as an adaptation strategy.

Distribution and abundance of diatom species from coastal waters of Karachi, Pakistan

International Nuclear Information System (INIS)

Khokhar, F. N.; Burhan, Z.; Iqbal, P.; Abbasi, J.; Siddiqui, P.

2016-01-01

This is the first comprehensive study on the distribution and abundance of diatom species from the coastal and nearshore waters of Karachi, Pakistan, bordering northern Arabian Sea. A total of 20 genera are recorded in high abundance (Cerataulina, Chaetoceros, Coscinodiscus, Cylindrotheca, Eucampia, Guinardia, Haslea, Hemiaulus, Lauderia, Lennoxia, Leptocylindrus, Navicula, Nitzschia, Trieres, Planktoniella, Pleurosigma, Pseudo-nitzschia, Rhizosolenia, Thalassionema and Thalassiosira). The most abundant genera were observed Guinardia, Chaetoceros, Leptocylindrus, Nitzschia and Lennoxia at all stations. Manora coastal station (MI-1) had high abundance corresponding with high Chlorophyll a (130 meu gL- l) values. Minimum abundance and low chlorophyll a value (0.05μgL-l) were observed at Mubarak Village coastal station (MV-1). Diatom abundance showed significant correlation with Chlorophyll a. In present study 12 centric and 8 pennate forms were recorded and similarly high diversity of centric taxa was observed compared to pennate forms. A total of 134 species are recorded of which 40 species were observed at four stations, 31species at three stations, 23 at two stations and 40 species only at one station. The total phytoplankton and diatom peak abundance was observed during NE monsoon (winter season) associated with nutrient loading through up-sloping of nutrient rich water upwelled off of Oman during South West monsoon. Overall higher diversity was observed at Manora coastal and nearshore stations (MI-1, MI-2) indicating the influence of organic pollution loading from Layari and Malir rivers. (author)

Mechanisms of the intensification of the upwelling-favorable winds during El Niño 1997-1998 in the Peruvian upwelling system

Science.gov (United States)

Chamorro, Adolfo; Echevin, Vincent; Colas, François; Oerder, Vera; Tam, Jorge; Quispe-Ccalluari, Carlos

2018-01-01

The physical processes driving the wind intensification in a coastal band of 100 km off Peru during the intense 1997-1998 El Niño (EN) event were studied using a regional atmospheric model. A simulation performed for the period 1994-2000 reproduced the coastal wind response to local sea surface temperature (SST) forcing and large scale atmospheric conditions. The model, evaluated with satellite data, represented well the intensity, seasonal and interannual variability of alongshore (i.e. NW-SE) winds. An alongshore momentum budget showed that the pressure gradient was the dominant force driving the surface wind acceleration. The pressure gradient tended to accelerate the coastal wind, while turbulent vertical mixing decelerated it. A quasi-linear relation between surface wind and pressure gradient anomalies was found. Alongshore pressure gradient anomalies were caused by a greater increase in near-surface air temperature off the northern coast than off the southern coast, associated with the inhomogeneous SST warming. Vertical profiles of wind, mixing coefficient, and momentum trends showed that the surface wind intensification was not caused by the increase of turbulence in the planetary boundary layer. Moreover, the temperature inversion in the vertical mitigated the development of pressure gradient due to air convection during part of the event. Sensitivity experiments allowed to isolate the respective impacts of the local SST forcing and large scale condition on the coastal wind intensification. It was primarily driven by the local SST forcing whereas large scale variability associated with the South Pacific Anticyclone modulated its effects. Examination of other EN events using reanalysis data confirmed that intensifications of alongshore wind off Peru were associated with SST alongshore gradient anomalies, as during the 1997-1998 event.

Although most of the phytoplankton of the Benguela upwelling ...

African Journals Online (AJOL)

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The Benguela upwelling system is subjected to blooms of harmful and toxic algae, the incidence and consequences of which are ... the coupling between this physical environment and ... Gordons Bay) and the 24 stations at which Fisheries Control Officers are located ... Oil Pollution vessels and aircraft, the Air Force.

The role of Southern Ocean mixing and upwelling in glacial-interglacial atmospheric CO2 change

International Nuclear Information System (INIS)

Watson, Andrew J.; Naveira Garabato, Alberto C.

2006-01-01

Decreased ventilation of the Southern Ocean in glacial time is implicated in most explanations of lower glacial atmospheric CO 2 . Today, the deep (>2000 m) ocean south of the Polar Front is rapidly ventilated from below, with the interaction of deep currents with topography driving high mixing rates well up into the water column. We show from a buoyancy budget that mixing rates are high in all the deep waters of the Southern Ocean. Between the surface and 2000 m depth, water is upwelled by a residual meridional overturning that is directly linked to buoyancy fluxes through the ocean surface. Combined with the rapid deep mixing, this upwelling serves to return deep water to the surface on a short time scale. We propose two new mechanisms by which, in glacial time, the deep Southern Ocean may have been more isolated from the surface. Firstly, the deep ocean appears to have been more stratified because of denser bottom water resulting from intense sea ice formation near Antarctica. The greater stratification would have slowed the deep mixing. Secondly, subzero atmospheric temperatures may have meant that the present-day buoyancy flux from the atmosphere to the ocean surface was reduced or reversed. This in turn would have reduced or eliminated the upwelling (contrary to a common assumption, upwelling is not solely a function of the wind stress but is coupled to the air/sea buoyancy flux too). The observed very close link between Antarctic temperatures and atmospheric CO 2 could then be explained as a natural consequence of the connection between the air/sea buoyancy flux and upwelling in the Southern Ocean, if slower ventilation of the Southern Ocean led to lower atmospheric CO 2 . Here we use a box model, similar to those of previous authors, to show that weaker mixing and reduced upwelling in the Southern Ocean can explain the low glacial atmospheric CO 2 in such a formulation

A study on biological activity of marine fungi from different habitats in coastal regions.

Science.gov (United States)

Zhou, Songlin; Wang, Min; Feng, Qi; Lin, Yingying; Zhao, Huange

2016-01-01

In recent years, marine fungi have become an important source of active marine natural products. Former researches are limited in habitats selection of fungi with bioactive compounds. In this paper were to measure antibacterial and antitumor cell activity for secondary metabolites of marine fungi, which were isolated from different habitats in coastal regions. 195 strains of marine fungi were isolated and purified from three different habitats. They biologically active experiment results showed that fungi isolation from the mangrove habitats had stronger antibacterial activity than others, and the stains isolated from the estuarial habitats had the least antibacterial activity. However, the strains separated from beach habitats strongly inhibited tumor cell proliferation in vitro, and fungi of mangrove forest habitats had the weakest activity of inhibiting tumor. Meanwhile, 195 fungal strains belonged to 46 families, 84 genera, 142 species and also showed 137 different types of activity combinations by analyzing the inhibitory activity of the metabolites fungi for 4 strains of pathogenic bacteria and B-16 cells. The study investigated the biological activity of marine fungi isolated from different habitats in Haikou coastal regions. The results help us to understand bioactive metabolites of marine fungi from different habitats, and how to selected biological activity fungi from various marine habitats effectively.

Oceanographic, Air-sea Interaction, and Environmental Aspects of Artificial Upwelling Produced by Wave-Inertia Pumps for Potential Hurricane Intensity Mitigation

Science.gov (United States)

Soloviev, A.; Dean, C.

2017-12-01

The artificial upwelling system consisting of the wave-inertia pumps driven by surface waves can produce flow of cold deep water to the surface. One of the recently proposed potential applications of the artificial upwelling system is the hurricane intensity mitigation. Even relatively small reduction of intensity may provide significant benefits. The ocean heat content (OHC) is the "fuel" for hurricanes. The OHC can be reduced by mixing of the surface layer with the cold water produced by wave-inertia pumps. Implementation of this system for hurricane mitigation has several oceanographic and air-sea interaction aspects. The cold water brought to the surface from a deeper layer has higher density than the surface water and, therefore, tends to sink back down. The mixing of the cold water produced by artificial upwelling depends on environmental conditions such as stratification, regional ocean circulation, and vertical shear. Another aspect is that as the sea surface temperature drops below the air temperature, the stable stratification develops in the atmospheric boundary layer. The stable atmospheric stratification suppresses sensible and latent heat air-sea fluxes and reduces the net longwave irradiance from the sea surface. As a result, the artificial upwelling may start increasing the OHC (though still reducing the sea surface temperature). In this work, the fate of the cold water in the stratified environment with vertical shear has been studied using computational fluid dynamics (CFD) tools. A 3D large eddy simulation model is initialized with observational temperature, salinity, and current velocity data from a sample location in the Straits of Florida. A periodic boundary condition is set along the direction of the current, which allows us to simulate infinite fetch. The model results indicate that the cold water brought to the sea surface by a wave-inertia pump forms a convective jet. This jet plunges into the upper ocean mixed layer and penetrates the

Metals content in surface waters of an upwelling system of the northern Humboldt Current (Mejillones Bay, Chile)

Science.gov (United States)

Valdés, Jorge; Román, Domingo; Alvarez, Gabriel; Ortlieb, Luc; Guiñez, Marcos

Physical-chemical parameters (temperature, salinity, dissolved oxygen, nutrients, and chlorophyll concentration) of surface waters were used to evaluate the influence of biological and physical processes over the metal concentrations (Cd, Ni, V, Mo, Mn, and Fe) in different periods of a normal annual cycle (June 2002 and April 2003), in Mejillones Bay (23° S), one of northern Chile's strongest upwelling cells. Two points were sampled every 2 months, but statistical analysis of these parameters did not show any spatial differences in surface water composition (annual average) in this bay. The order of total and dissolved metals by abundance (annual mean) in the Mejillones Bay surface waters during the sampling period was Cd Oxygen Minimum Zone which characterizes the Mejillones bay should have an important influence on surface distribution of trace metals and can explain the high temporal variability observed in most of the metals analyzed in this work. A two-box conceptual model is proposed to suggest possible influences on metals in surface waters of this coastal ecosystem.

Upwelling to Outflowing Oxygen Ions at Auroral Latitudes during Quiet Times: Exploiting a New Satellite Database

Science.gov (United States)

Redmon, Robert J.