A Bayesian-Based System to Assess Wave-Driven Flooding Hazards on Coral Reef-Lined Coasts

Science.gov (United States)

Pearson, S. G.; Storlazzi, C. D.; van Dongeren, A. R.; Tissier, M. F. S.; Reniers, A. J. H. M.

2017-12-01

Many low-elevation, coral reef-lined, tropical coasts are vulnerable to the effects of climate change, sea level rise, and wave-induced flooding. The considerable morphological diversity of these coasts and the variability of the hydrodynamic forcing that they are exposed to make predicting wave-induced flooding a challenge. A process-based wave-resolving hydrodynamic model (XBeach Non-Hydrostatic, "XBNH") was used to create a large synthetic database for use in a "Bayesian Estimator for Wave Attack in Reef Environments" (BEWARE), relating incident hydrodynamics and coral reef geomorphology to coastal flooding hazards on reef-lined coasts. Building on previous work, BEWARE improves system understanding of reef hydrodynamics by examining the intrinsic reef and extrinsic forcing factors controlling runup and flooding on reef-lined coasts. The Bayesian estimator has high predictive skill for the XBNH model outputs that are flooding indicators, and was validated for a number of available field cases. It was found that, in order to accurately predict flooding hazards, water depth over the reef flat, incident wave conditions, and reef flat width are the most essential factors, whereas other factors such as beach slope and bed friction due to the presence or absence of corals are less important. BEWARE is a potentially powerful tool for use in early warning systems or risk assessment studies, and can be used to make projections about how wave-induced flooding on coral reef-lined coasts may change due to climate change.Plain Language SummaryLow-lying tropical coasts fronted by coral reefs are threatened by the effects of climate change, sea level rise, and flooding caused by waves. However, the reefs on these coasts differ widely in their shape, size, and physical characteristics; the wave and water level conditions affecting these coastlines also vary in space and time. These factors make it difficult to predict flooding caused by waves along coral reef-lined coasts. We

Coupling Biophysical and Socioeconomic Models for Coral Reef Systems in Quintana Roo, Mexican Caribbean

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Jessica Melbourne-Thomas

2011-09-01

Full Text Available Transdisciplinary approaches that consider both socioeconomic and biophysical processes are central to understanding and managing rapid change in coral reef systems worldwide. To date, there have been limited attempts to couple the two sets of processes in dynamic models for coral reefs, and these attempts are confined to reef systems in developed countries. We present an approach to coupling existing biophysical and socioeconomic models for coral reef systems in the Mexican state of Quintana Roo. The biophysical model is multiscale, using dynamic equations to capture local-scale ecological processes on individual reefs, with reefs connected at regional scales by the ocean transport of larval propagules. The agent-based socioeconomic model simulates changes in tourism, fisheries, and urbanization in the Quintana Roo region. Despite differences in the formulation and currencies of the two models, we were able to successfully modify and integrate them to synchronize and define information flows and feedbacks between them. A preliminary evaluation of the coupled model system indicates that the model gives reasonable predictions for fisheries and ecological variables and can be used to examine scenarios for future social-ecological change in Quintana Roo. We provide recommendations for where efforts might usefully be focused in future attempts to integrate models of biophysical and socioeconomic processes, based on the limitations of our coupled system.

A diverse assemblage of reef corals thriving in a dynamic intertidal reef setting (Bonaparte Archipelago, Kimberley, Australia.

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Zoe T Richards

Full Text Available The susceptibility of reef-building corals to climatic anomalies is well documented and a cause of great concern for the future of coral reefs. Reef corals are normally considered to tolerate only a narrow range of climatic conditions with only a small number of species considered heat-tolerant. Occasionally however, corals can be seen thriving in unusually harsh reef settings and these are cause for some optimism about the future of coral reefs. Here we document for the first time a diverse assemblage of 225 species of hard corals occurring in the intertidal zone of the Bonaparte Archipelago, north western Australia. We compare the environmental conditions at our study site (tidal regime, SST and level of turbidity with those experienced at four other more typical tropical reef locations with similar levels of diversity. Physical extremes in the Bonaparte Archipelago include tidal oscillations of up to 8 m, long subaerial exposure times (>3.5 hrs, prolonged exposure to high SST and fluctuating turbidity levels. We conclude the timing of low tide in the coolest parts of the day ameliorates the severity of subaerial exposure, and the combination of strong currents and a naturally high sediment regime helps to offset light and heat stress. The low level of anthropogenic impact and proximity to the Indo-west Pacific centre of diversity are likely to further promote resistance and resilience in this community. This assemblage provides an indication of what corals may have existed in other nearshore locations in the past prior to widespread coastal development, eutrophication, coral predator and disease outbreaks and coral bleaching events. Our results call for a re-evaluation of what conditions are optimal for coral survival, and the Bonaparte intertidal community presents an ideal model system for exploring how species resilience is conferred in the absence of confounding factors such as pollution.

Coral reefs of the turbid inner-shelf of the Great Barrier Reef, Australia: An environmental and geomorphic perspective on their occurrence, composition and growth

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Browne, N. K.; Smithers, S. G.; Perry, C. T.

2012-10-01

Investigations of the geomorphic and sedimentary context in which turbid zone reefs exist, both in the modern and fossil reef record, can inform key ecological debates regarding species tolerances and adaptability to elevated turbidity and sedimentation. Furthermore, these investigations can address critical geological and palaeoecological questions surrounding longer-term coral-sediment interactions and reef growth histories. Here we review current knowledge about turbid zone reefs from the inner-shelf regions of the Great Barrier Reef (GBR) in Australia to consider these issues and to evaluate reef growth in the period prior to and post European settlement. We also consider the future prospects of these reefs under reported changing water quality regimes. Turbid zone reefs on the GBR are relatively well known compared to those in other reef regions. They occur within 20 km of the mainland coast where reef development may be influenced by continual or episodic terrigenous sediment inputs, fluctuating salinities (24-36 ppt), and reduced water quality through increased nutrient and pollutant delivery from urban and agricultural runoff. Individually, and in synergy, these environmental conditions are widely viewed as unfavourable for sustained and vigorous coral reef growth, and thus these reefs are widely perceived as marginal compared to clear water reef systems. However, recent research has revealed that this view is misleading, and that in fact many turbid zone reefs in this region are resilient, exhibit relatively high live coral cover (> 30%) and have distinctive community assemblages dominated by fast growing (Acropora, Montipora) and/or sediment tolerant species (Turbinaria, Goniopora, Galaxea, Porites). Palaeoecological reconstructions based on the analysis of reef cores show that community assemblages are relatively stable at millennial timescales, and that many reefs are actively accreting (average 2-7 mm/year) where accommodation space is available

Submerged reef systems on the central western continental shelf of India

Digital Repository Service at National Institute of Oceanography (India)

Vora, K.H.; Almeida, F.

-262 255 Elsevier Science Publishers B.V., Amsterdam -- Printed in the Netherlands Letter Section Submerged Reef Systems on the Central Western Continental Shelf of India K.H. VORA and F. ALMEIDA National Institute of Oceanography, Dona Paula, Goa 403... 004 (India) (Revision accepted October 26, 1989) Abstract Vora, K.H. and Almeida, F., 1990. Submerged reef systems on the central western continental shelf of India. Mar. Geol., 91: 255-262. Echosounding and sidescan sonar data from the western...

ReefLink Database: A decision support tool for Linking Coral Reefs and Society Through Systems Thinking

Science.gov (United States)

Coral reefs provide the ecological foundation for productive and diverse fish and invertebrate communities that support multibillion dollar reef fishing and tourism industries. Yet reefs are threatened by growing coastal development, climate change, and over-exploitation. A key i...

Carbonate system parameters of an algal-dominated reef along West Maui

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Prouty, Nancy G.; Yates, Kimberly K.; Smiley, Nathan; Gallagher, Chris; Cheriton, Olivia; Storlazzi, Curt D.

2018-04-01

Constraining coral reef metabolism and carbon chemistry dynamics are fundamental for understanding and predicting reef vulnerability to rising coastal CO2 concentrations and decreasing seawater pH. However, few studies exist along reefs occupying densely inhabited shorelines with known input from land-based sources of pollution. The shallow coral reefs off Kahekili, West Maui, are exposed to nutrient-enriched, low-pH submarine groundwater discharge (SGD) and are particularly vulnerable to the compounding stressors from land-based sources of pollution and lower seawater pH. To constrain the carbonate chemistry system, nutrients and carbonate chemistry were measured along the Kahekili reef flat every 4 h over a 6-day sampling period in March 2016. Abiotic process - primarily SGD fluxes - controlled the carbonate chemistry adjacent to the primary SGD vent site, with nutrient-laden freshwater decreasing pH levels and favoring undersaturated aragonite saturation (Ωarag) conditions. In contrast, diurnal variability in the carbonate chemistry at other sites along the reef flat was driven by reef community metabolism. Superimposed on the diurnal signal was a transition during the second sampling period to a surplus of total alkalinity (TA) and dissolved inorganic carbon (DIC) compared to ocean endmember TA and DIC measurements. A shift from positive net community production and positive net community calcification to negative net community production and negative net community calcification was identified. This transition occurred during a period of increased SGD-driven nutrient loading, lower wave height, and reduced current speeds. This detailed study of carbon chemistry dynamics highlights the need to incorporate local effects of nearshore oceanographic processes into predictions of coral reef vulnerability and resilience.

Carbonate system parameters of an algal-dominated reef along west Maui

Science.gov (United States)

Prouty, Nancy G.; Yates, Kimberly K.; Smiley, Nathan A.; Gallagher, Christopher; Cheriton, Olivia; Storlazzi, Curt

2018-01-01

Constraining coral reef metabolism and carbon chemistry dynamics are fundamental for understanding and predicting reef vulnerability to rising coastal CO2 concentrations and decreasing seawater pH. However, few studies exist along reefs occupying densely inhabited shorelines with known input from land-based sources of pollution. The shallow coral reefs off Kahekili, West Maui, are exposed to nutrient-enriched, low-pH submarine groundwater discharge (SGD) and are particularly vulnerable to the compounding stressors from land-based sources of pollution and lower seawater pH. To constrain the carbonate chemistry system, nutrients and carbonate chemistry were measured along the Kahekili reef flat every 4 h over a 6-d sampling period in March 2016. Abiotic process – primarily SGD fluxes – controlled the carbonate chemistry adjacent to the primary SGD vent site, with nutrient-laden freshwater decreasing pH levels and favoring undersaturated aragonite saturation (Ωarag) conditions. In contrast, diurnal variability in the carbonate chemistry at other sites along the reef flat was driven by reef community metabolism. Superimposed on the diurnal signal was a transition during the second sampling period to a surplus of total alkalinity (TA) and dissolved inorganic carbon (DIC) compared to ocean end-member TA and DIC measurements. A shift from net community production and calcification to net respiration and carbonate dissolution was identified. This transition occurred during a period of increased SGD-driven nutrient loading, lower wave height, and reduced current speeds. This detailed study of carbon chemistry dynamics highlights the need to incorporate local effects of nearshore oceanographic processes into predictions of coral reef vulnerability and resilience.

Impacts of Artificial Reefs on Surrounding Ecosystems

Science.gov (United States)

Manoukian, Sarine

Artificial reefs are becoming a popular biological and management component in shallow water environments characterized by soft seabed, representing both important marine habitats and tools to manage coastal fisheries and resources. An artificial reef in the marine environment acts as an open system with exchange of material and energy, altering the physical and biological characteristics of the surrounding area. Reef stability will depend on the balance of scour, settlement, and burial resulting from ocean conditions over time. Because of the unstable nature of sediments, they require a detailed and systematic investigation. Acoustic systems like high-frequency multibeam sonar are efficient tools in monitoring the environmental evolution around artificial reefs, whereas water turbidity can limit visual dive and ROV inspections. A high-frequency multibeam echo sounder offers the potential of detecting fine-scale distribution of reef units, providing an unprecedented level of resolution, coverage, and spatial definition. How do artificial reefs change over time in relation to the coastal processes? How accurately does multibeam technology map different typologies of artificial modules of known size and shape? How do artificial reefs affect fish school behavior? What are the limitations of multibeam technology for investigating fish school distribution as well as spatial and temporal changes? This study addresses the above questions and presents results of a new approach for artificial reef seafloor mapping over time, based upon an integrated analysis of multibeam swath bathymetry data and geoscientific information (backscatter data analysis, SCUBA observations, physical oceanographic data, and previous findings on the geology and sedimentation processes, integrated with unpublished data) from Senigallia artificial reef, northwestern Adriatic Sea (Italy) and St. Petersburg Beach Reef, west-central Florida continental shelf. A new approach for observation of fish

Geomorphology and sediment transport on a submerged back-reef sand apron: One Tree Reef, Great Barrier Reef

Science.gov (United States)

Harris, Daniel L.; Vila-Concejo, Ana; Webster, Jody M.

2014-10-01

Back-reef sand aprons are conspicuous and dynamic sedimentary features in coral reef systems. The development of these features influences the evolution and defines the maturity of coral reefs. However, the hydrodynamic processes that drive changes on sand aprons are poorly understood with only a few studies directly assessing sediment entrainment and transport. Current and wave conditions on a back-reef sand apron were measured during this study and a digital elevation model was developed through topographic and bathymetric surveying of the sand apron, reef flats and lagoon. The current and wave processes that may entrain and transport sediment were assessed using second order small amplitude (Stokes) wave theory and Shields equations. The morphodynamic interactions between current flow and geomorphology were also examined. The results showed that sediment transport occurs under modal hydrodynamic conditions with waves the main force entraining sediment rather than average currents. A morphodynamic relationship between current flow and geomorphology was also observed with current flow primarily towards the lagoon in shallow areas of the sand apron and deeper channel-like areas directing current off the sand apron towards the lagoon or the reef crest. These results show that the short-term mutual interaction of hydrodynamics and geomorphology in coral reefs can result in morphodynamic equilibrium.

Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

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Gurney, Georgina G; Melbourne-Thomas, Jessica; Geronimo, Rollan C; Aliño, Perry M; Johnson, Craig R

2013-01-01

Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

Modelling Coral Reef Futures to Inform Management: Can Reducing Local-Scale Stressors Conserve Reefs under Climate Change?

Science.gov (United States)

Gurney, Georgina G.; Melbourne-Thomas, Jessica; Geronimo, Rollan C.; Aliño, Perry M.; Johnson, Craig R.

2013-01-01

Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

Directory of Open Access Journals (Sweden)

Georgina G Gurney

Full Text Available Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general

Coral biodiversity and bioconstruction in the northern sector of the Mesoamerican Reef system

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Fabian Alejandro Rodriguez-Zaragoza

2015-03-01

Full Text Available As the impact of anthropogenic activity and climate change continue to accelerate rates of degradation on Caribbean coral reefs, conservation and restoration faces greater challenges. At at this stage, of particular importance in coral reefs, is to recognize and to understand the structural spatial patterns of benthic assemblages. We developed a field-based framework of a Caribbean reefscape benthic structure by using hermatypic corals as an indicator group of global biodiversity and bio-construction patterns in eleven reefs of the northern sector of the Mesoamerican Barrier Reef System (nsMBRS. Four hundred and seventy four video-transects (50 m long by 0.4 m wide were performed throughout a gradient of reef complexity from north to south (∼400 km to identify coral species, families and ensembles of corals. Composition and abundance of species, families and ensembles showed differences among reefs. In the northern zone, the reefs had shallow, partial reef developments with low diversities, dominated by Acropora palmata, Siderastrea spp., Pseudodiploria strigosa and Agaricia tenuifolia. In the central and southern zones, reefs presented extensive developments, high habitat heterogeneity, and the greatest diversity and dominance of Orbicella annularis and Orbicella faveolata. These two species determined the structure and diversity of corals in the central and southern zones of the nsMBRS and their bio-construction in these zones is unique in the Caribbean. Their abundance and distribution depended on the reef habitat area, topographic complexity and species richness. Orbicella species complex were crucial for maintaining the biodiversity and bio-construction of the central and southern zones while A. palmata in the northern zones of the nsMBRS.

Linking social and ecological systems to sustain coral reef fisheries.

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Cinner, Joshua E; McClanahan, Timothy R; Daw, Tim M; Graham, Nicholas A J; Maina, Joseph; Wilson, Shaun K; Hughes, Terence P

2009-02-10

The ecosystem goods and services provided by coral reefs are critical to the social and economic welfare of hundreds of millions of people, overwhelmingly in developing countries [1]. Widespread reef degradation is severely eroding these goods and services, but the socioeconomic factors shaping the ways that societies use coral reefs are poorly understood [2]. We examine relationships between human population density, a multidimensional index of socioeconomic development, reef complexity, and the condition of coral reef fish populations in five countries across the Indian Ocean. In fished sites, fish biomass was negatively related to human population density, but it was best explained by reef complexity and a U-shaped relationship with socioeconomic development. The biomass of reef fishes was four times lower at locations with intermediate levels of economic development than at locations with both low and high development. In contrast, average biomass inside fishery closures was three times higher than in fished sites and was not associated with socioeconomic development. Sustaining coral reef fisheries requires an integrated approach that uses tools such as protected areas to quickly build reef resources while also building capacities and capital in societies over longer time frames to address the complex underlying causes of reef degradation.

Possible recovery of Acropora palmata (Scleractinia:Acroporidae within the Veracruz Reef System, Gulf of Mexico: a survey of 24 reefs to assess the benthic communities

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Elizabeth A. Larson

2014-09-01

Full Text Available Recent evidence shows that Acropora palmata within the Veracruz Reef System, located in the southwestern Gulf of Mexico, may be recovering after the die off from the flooding of the Jamapa River and a dramatic cold water event in the 1970s. Since this decline, few surveys have documented the status of A. palmata. The 28 named reefs in the system are divided into 13 northern and 15 southern groups by the River. Between 2007 and 2013, we surveyed 24 reefs to assess the benthic communities. Seven of the 11 reefs surveyed in the northern group and all in the southern group had A. palmata. Colonies were typically found on the windward side of the reefs in shallow waters along the reef edges or crest. We also recorded colony diameter and condition along belt transects at two reefs in the north (Anegada de Adentro and Verde and two in the south (Periferico and Sargazo, between 2011 and 2013. In addition, eight permanent transects were surveyed at Rizo (south. A total of 1 804 colonies were assessed; densities ranged from 0.02 to 0.28 colonies/m² (mean (±SD, colony diameter of 58 ± 73cm, and 89 ± 18% live tissue per colony. Total prevalence of predation by damselfish was 5%, by snails 2%, and <1% by fireworms, disease prevalence was <3%. Size frequency distributions indicated that all of the sites had a moderate to high spawning potential, 15-68% of the colonies at each site were mature, measuring over 1 600cm². The presence of these healthy and potentially reproductive colonies is important for species recovery, particularly because much of the greater Caribbean still shows little to no signs of recovery. Conservation and management efforts of these reefs are vital.

Mapping Health of Bonaire Coral Reefs Using a Lightweight Hyperspectral Mapping System - First Results

Science.gov (United States)

Suomalainen, Juha; Mucher, Sander; Kooistra, Lammert; Meesters, Erik

2014-05-01

The Dutch Caribbean island of Bonaire is one of the world's top diving holiday destinations much due to its clear waters and healthy coral reefs. The coral reefs surround the western side of the island as an approximately 50-150m wide band. However, the general consensus is that the extent and biodiversity of the Bonarian coral reef is constantly decreasing due to anthropogenic pressures. The last extensive study of the health of the reef ecosystem was performed in 1985 by Van Duyl creating an underwater atlas. In order to update this atlas of Bonaire's coral reefs, in October 2013, a hyperspectral mapping campaign was performed using the WUR Hyperspectral Mapping System (HYMSY). A dive validation campaign has been planned for early 2014. The HYMSY consists of a custom pushbroom spectrometer (range 450-950nm, FWHM 9nm, ~20 lines/s, 328 pixels/line), a consumer camera (collecting 16MPix raw image every 2 seconds), a GPS-Inertia Navigation System (GPS-INS), and synchronization and data storage units. The weight of the system at take-off is 2.0kg allowing it to be mounted on varying platforms. In Bonaire the system was flown on two platforms. (1) on a Cessna airplane to provide a coverage for whole west side of the island with a hyperspectral map in 2-4m resolution and a RGB orthomosaic in 15cm resolution, and (2) on a kite pulled by boat and car to provide a subset coverage in higher resolution. In this presentation we will present our mapping technique and first results including a preliminary underwater atlas and conclusions on reef development.

Prey Density Threshold and Tidal Influence on Reef Manta Ray Foraging at an Aggregation Site on the Great Barrier Reef.

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Asia O Armstrong

Full Text Available Large tropical and sub-tropical marine animals must meet their energetic requirements in a largely oligotrophic environment. Many planktivorous elasmobranchs, whose thermal ecologies prevent foraging in nutrient-rich polar waters, aggregate seasonally at predictable locations throughout tropical oceans where they are observed feeding. Here we investigate the foraging and oceanographic environment around Lady Elliot Island, a known aggregation site for reef manta rays Manta alfredi in the southern Great Barrier Reef. The foraging behaviour of reef manta rays was analysed in relation to zooplankton populations and local oceanography, and compared to long-term sighting records of reef manta rays from the dive operator on the island. Reef manta rays fed at Lady Elliot Island when zooplankton biomass and abundance were significantly higher than other times. The critical prey density threshold that triggered feeding was 11.2 mg m-3 while zooplankton size had no significant effect on feeding. The community composition and size structure of the zooplankton was similar when reef manta rays were feeding or not, with only the density of zooplankton changing. Higher zooplankton biomass was observed prior to low tide, and long-term (~5 years sighting data confirmed that more reef manta rays are also observed feeding during this tidal phase than other times. This is the first study to examine prey availability at an aggregation site for reef manta rays and it indicates that they feed in locations and at times of higher zooplankton biomass.

Understanding coral reefs as complex systems: degradation and prospects for recovery

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Raymond T. Dizon

2006-06-01

Full Text Available The present century is witness to unprecedented levels of coral reef degradation worldwide. Current understanding based on traditional ideas is unlikely to capture adequately the dynamics of phenomena accompanying this trend. In this regard, the ideas of complexity are reviewed. Some applications to coral reefs as complex systems have already been discussed in the literature although further progress is warranted as the search for new and more effective management tools continues, and the direction towards more holistic, integrative and large scale approaches gains wider acceptance. We distinguish between the concepts of robustness and resilience in the face of disturbance, highlight the various mechanisms that foster these stability properties and provide some coral reef examples. We identify some of the driving forces behind succession that are critical for community assembly and possible reef recovery. Finally, we consider how self-organization arises out of apparently random and chaotic processes and interactions to exhibit certain regularities and patterns especially when moving up on the scale of space and/or time.

Factors Affecting Detection Probability of Acoustic Tags in Coral Reefs

KAUST Repository

Bermudez, Edgar F.

2012-05-01

Acoustic telemetry is an important tool for studying the movement patterns, behaviour, and site fidelity of marine organisms; however, its application is challenged in coral reef environments where complex topography and intense environmental noise interferes with acoustic signals, and there has been less study. Therefore, it is particularly critical in coral reef telemetry studies to first conduct a long-term range test, a tool that provides informa- tion on the variability and periodicity of the transmitter detection range and the detection probability. A one-month range test of a coded telemetric system was conducted prior to a large-scale tagging project investigating the movement of approximately 400 fishes from 30 species on offshore coral reefs in the central Red Sea. During this range test we determined the effect of the following factors on transmitter detection efficiency: distance from receiver, time of day, depth, wind, current, moon-phase and temperature. The experiment showed that biological noise is likely to be responsible for a diel pattern of -on average- twice as many detections during the day as during the night. Biological noise appears to be the most important noise source in coral reefs overwhelming the effect of wind-driven noise, which is important in other studies. Detection probability is also heavily influenced by the location of the acoustic sensor within the reef structure. Understanding the effect of environmental factors on transmitter detection probability allowed us to design a more effective receiver array for the large-scale tagging study.

Reef odor: a wake up call for navigation in reef fish larvae.

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Claire B Paris

Full Text Available The behavior of reef fish larvae, equipped with a complex toolbox of sensory apparatus, has become a central issue in understanding their transport in the ocean. In this study pelagic reef fish larvae were monitored using an unmanned open-ocean tracking device, the drifting in-situ chamber (DISC, deployed sequentially in oceanic waters and in reef-born odor plumes propagating offshore with the ebb flow. A total of 83 larvae of two taxonomic groups of the families Pomacentridae and Apogonidae were observed in the two water masses around One Tree Island, southern Great Barrier Reef. The study provides the first in-situ evidence that pelagic reef fish larvae discriminate reef odor and respond by changing their swimming speed and direction. It concludes that reef fish larvae smell the presence of coral reefs from several kilometers offshore and this odor is a primary component of their navigational system and activates other directional sensory cues. The two families expressed differences in their response that could be adapted to maintain a position close to the reef. In particular, damselfish larvae embedded in the odor plume detected the location of the reef crest and swam westward and parallel to shore on both sides of the island. This study underlines the critical importance of in situ Lagrangian observations to provide unique information on larval fish behavioral decisions. From an ecological perspective the central role of olfactory signals in marine population connectivity raises concerns about the effects of pollution and acidification of oceans, which can alter chemical cues and olfactory responses.

Integrating observational and modelling systems for the management of the Great Barrier Reef

Science.gov (United States)

Baird, M. E.; Jones, E. M.; Margvelashvili, N.; Mongin, M.; Rizwi, F.; Robson, B.; Schroeder, T.; Skerratt, J.; Steven, A. D.; Wild-Allen, K.

2016-02-01

Observational and modelling systems provide two sources of knowledge that must be combined to provide a more complete view than either observations or models alone can provide. Here we describe the eReefs coupled hydrodynamic, sediment and biogeochemical model that has been developed for the Great Barrier Reef; and the multiple observations that are used to constrain the model. Two contrasting examples of model - observational integration are highlighted. First we explore the carbon chemistry of the waters above the reef, for which observations are accurate, but expensive and therefore sparse, while model behaviour is highly skilful. For carbon chemistry, observations are used to constrain model parameterisation and quantify model error, with the model output itself providing the most useable knowledge for management purposes. In contrast, ocean colour provides inaccurate, but cheap and spatially and temporally extensive observations. Thus observations are best combined with the model in a data assimilating framework, where a custom-designed optical model has been developed for the purposes of incorporating ocean colour observations. The future management of Great Barrier Reef water quality will be based on an integration of observing and modelling systems, providing the most robust information available.

Risks to coral reefs from ocean carbonate chemistry changes in recent earth system model projections

International Nuclear Information System (INIS)

Ricke, K L; Caldeira, K; Orr, J C; Schneider, K

2013-01-01

Coral reefs are among the most biodiverse ecosystems in the world. Today they are threatened by numerous stressors, including warming ocean waters and coastal pollution. Here we focus on the implications of ocean acidification for the open ocean chemistry surrounding coral reefs, as estimated from earth system models participating in the Coupled Model Intercomparison Project, Phase 5 (CMIP5). We project risks to reefs in the context of three potential aragonite saturation (Ωa) thresholds. We find that in preindustrial times, 99.9% of reefs adjacent to open ocean in the CMIP5 ensemble were located in regions with Ωa > 3.5. Under a business-as-usual scenario (RCP 8.5), every coral reef considered will be surrounded by water with Ωa 2 emissions abatement, the Ωa threshold for reefs is critical to projecting their fate. Our results indicate that to maintain a majority of reefs surrounded by waters with Ωa > 3.5 to the end of the century, very aggressive reductions in emissions are required. The spread of Ωa projections across models in the CMIP5 ensemble is narrow, justifying a high level of confidence in these results. (letter)

Social interactions among grazing reef fish drive material flux in a coral reef ecosystem.

Science.gov (United States)

Gil, Michael A; Hein, Andrew M

2017-05-02

In human financial and social systems, exchanges of information among individuals cause speculative bubbles, behavioral cascades, and other correlated actions that profoundly influence system-level function. Exchanges of information are also widespread in ecological systems, but their effects on ecosystem-level processes are largely unknown. Herbivory is a critical ecological process in coral reefs, where diverse assemblages of fish maintain reef health by controlling the abundance of algae. Here, we show that social interactions have a major effect on fish grazing rates in a reef ecosystem. We combined a system for observing and manipulating large foraging areas in a coral reef with a class of dynamical decision-making models to reveal that reef fish use information about the density and actions of nearby fish to decide when to feed on algae and when to flee foraging areas. This "behavioral coupling" causes bursts of feeding activity that account for up to 68% of the fish community's consumption of algae. Moreover, correlations in fish behavior induce a feedback, whereby each fish spends less time feeding when fewer fish are present, suggesting that reducing fish stocks may not only reduce total algal consumption but could decrease the amount of algae each remaining fish consumes. Our results demonstrate that social interactions among consumers can have a dominant effect on the flux of energy and materials through ecosystems, and our methodology paves the way for rigorous in situ measurements of the behavioral rules that underlie ecological rates in other natural systems.

Biomimetric sentinel reef structures for optical sensing and communications

Science.gov (United States)

Fries, David; Hutcheson, Tim; Josef, Noam; Millie, David; Tate, Connor

2017-05-01

Traditional artificial reef structures are designed with uniform cellular architectures and topologies and do not mimic natural reef forms. Strings and ropes are a proven, common fisheries and mariculture construction element throughout the world and using them as artificial reef scaffolding can enable a diversity of ocean sensing, communications systems including the goal of sentinel reefs. The architecture and packaging of electronics is key to enabling such structures and systems. The distributed sensor reef concept leads toward a demonstrable science-engineering-informed framework for 3D smart habitat designs critical to stock fish development and coastal monitoring and protection. These `nature-inspired' reef infrastructures, can enable novel instrumented `reef observatories' capable of collecting real-time ecosystem data. Embedding lighting and electronic elements into artificial reef systems are the first systems conceptualized. This approach of bringing spatial light to the underwater world for optical sensing, communication and even a new breed of underwater robotic vehicle is an interdisciplinary research activity which integrates principles of electronic packaging, and ocean technology with art/design.

Coral reef connectivity within the Western Gulf of Mexico

Science.gov (United States)

Salas-Monreal, David; Marin-Hernandez, Mark; Salas-Perez, Jose de Jesus; Salas-de-Leon, David Alberto; Monreal-Gomez, Maria Adela; Perez-España, Horacio

2018-03-01

The yearlong monthly mean satellite data of the geostrophic velocities, the sea surface temperature and the chlorophyll-a values were used to elucidate any possible pathway among the different coral reef systems of the Western Gulf of Mexico (WGM). The geostrophic current velocities suggested different pathways connecting the coral reef areas. The typical coastal alongshore pathway constricted to the continental shelf, and two open ocean pathway, the first connecting the Campeche Reef System (CRS) with the Veracruz (VRS) and Tuxpan-Lobos Reef Systems (TLRS), and the second pathway connecting the Tuxpan-Lobos Reef System with the Flower Garden Reef System (FGRS). According to the pathways there should be more larvae transport from the southern Gulf of Mexico reef systems toward the FGRS than the other way. The connection from the southern Gulf of Mexico toward the FGRS took place during January, May, July, August and September (2015), while the connection from the FGRS toward the southern Gulf of Mexico reef system took place during January and February (2015), this was also suggested via model outputs. The density radio (R) was used as a first approximation to elucidate the influence of the freshwater continental discharges within the continental shelf. All coral reef areas were located where the Chlorophyll-a monthly mean values had values bellow 1 mg m- 2 with a density radio between 0 and 1, i.e. under the influence of continental discharges.

Caribbean Reef Response to Plio-Pleistocene Climate Change: Results of the Dominican Republic Drilling Project (DRDP)

Science.gov (United States)

Klaus, J.; McNeill, D. F.; Diaz, V.; Swart, P. K.; Pourmand, A.

2014-12-01

Caribbean reefs changed profoundly in taxonomic composition, diversity, and dominance structure during late Pliocene and Pleistocene climatic change. These changes coincide with protracted climatic deterioration and cooling between 2.0 to 0.8 Ma, and the onset of high amplitude sea-level fluctuations ~400 ka. The Dominican Republic Drilling Project (DRDP) was initiated to determine how climate change and global high-amplitude sea level changes influenced depositional patterns in Pliocene to Recent reef systems of the Caribbean. A transect of 7 core borings (~700 m total depth) were collected along the southern coast of the DR. New age constraints based on U/Th geochronometry and radiogenic Sr isotopes, combined with depositional lithofacies, faunal indicators, and stable isotope profiles have allowed us to correlate between wells and define the internal anatomy and stratal geometry of the individual reef sigmoids and sigmoid sets. Faunal records suggest most extinction occurred prior to ~1 Ma. Following this extinction, fringing reef margins of the Caribbean display a characteristic zonation in which Acropora palmata dominates shallow high-energy reef crests and Acropora cervicornis calmer fore-reef slopes and backreef lagoons. The dominance of acroporids across this zonation has been attributed to growth rates 5-100 times faster than other corals.

Artificial reefs and reef restoration in the Laurentian Great Lakes

Science.gov (United States)

McLean, Matthew W.; Roseman, Edward; Pritt, Jeremy J.; Kennedy, Gregory W.; Manny, Bruce A.

2015-01-01

We reviewed the published literature to provide an inventory of Laurentian Great Lakes artificial reef projects and their purposes. We also sought to characterize physical and biological monitoring for artificial reef projects in the Great Lakes and determine the success of artificial reefs in meeting project objectives. We found records of 6 artificial reefs in Lake Erie, 8 in Lake Michigan, 3 in Lakes Huron and Ontario, and 2 in Lake Superior. We found 9 reefs in Great Lakes connecting channels and 6 reefs in Great Lakes tributaries. Objectives of artificial reef creation have included reducing impacts of currents and waves, providing safe harbors, improving sport-fishing opportunities, and enhancing/restoring fish spawning habitats. Most reefs in the lakes themselves were incidental (not created purposely for fish habitat) or built to improve local sport fishing, whereas reefs in tributaries and connecting channels were more frequently built to benefit fish spawning. Levels of assessment of reef performance varied; but long-term monitoring was uncommon as was assessment of physical attributes. Artificial reefs were often successful at attracting recreational species and spawning fish; however, population-level benefits of artificial reefs are unclear. Stressors such as sedimentation and bio-fouling can limit the effectiveness of artificial reefs as spawning enhancement tools. Our investigation underscores the need to develop standard protocols for monitoring the biological and physical attributes of artificial structures. Further, long-term monitoring is needed to assess the benefits of artificial reefs to fish populations and inform future artificial reef projects.

Digital reef rugosity estimates coral reef habitat complexity.

Science.gov (United States)

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-01-01

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity.

Coral settlement on a highly disturbed equatorial reef system.

Science.gov (United States)

Bauman, Andrew G; Guest, James R; Dunshea, Glenn; Low, Jeffery; Todd, Peter A; Steinberg, Peter D

2015-01-01

Processes occurring early in the life stages of corals can greatly influence the demography of coral populations, and successful settlement of coral larvae that leads to recruitment is a critical life history stage for coral reef ecosystems. Although corals in Singapore persist in one the world's most anthropogenically impacted reef systems, our understanding of the role of coral settlement in the persistence of coral communities in Singapore remains limited. Spatial and temporal patterns of coral settlement were examined at 7 sites in the southern islands of Singapore, using settlement tiles deployed and collected every 3 months from 2011 to 2013. Settlement occurred year round, but varied significantly across time and space. Annual coral settlement was low (~54.72 spat m(-2) yr(-1)) relative to other equatorial regions, but there was evidence of temporal variation in settlement rates. Peak settlement occurred between March-May and September-November, coinciding with annual coral spawning periods (March-April and October), while the lowest settlement occurred from December-February during the northeast monsoon. A period of high settlement was also observed between June and August in the first year (2011/12), possibly due to some species spawning outside predicted spawning periods, larvae settling from other locations or extended larval settlement competency periods. Settlement rates varied significantly among sites, but spatial variation was relatively consistent between years, suggesting the strong effects of local coral assemblages or environmental conditions. Pocilloporidae were the most abundant coral spat (83.6%), while Poritidae comprised only 6% of the spat, and Acroporidae coral spat. These results indicate that current settlement patterns are reinforcing the local adult assemblage structure ('others'; i.e. sediment-tolerant coral taxa) in Singapore, but that the replenishment capacity of Singapore's reefs appears relatively constrained, which could lead

Historical baselines of coral cover on tropical reefs as estimated by expert opinion

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Tyler D. Eddy

2018-01-01

Full Text Available Coral reefs are important habitats that represent global marine biodiversity hotspots and provide important benefits to people in many tropical regions. However, coral reefs are becoming increasingly threatened by climate change, overfishing, habitat destruction, and pollution. Historical baselines of coral cover are important to understand how much coral cover has been lost, e.g., to avoid the ‘shifting baseline syndrome’. There are few quantitative observations of coral reef cover prior to the industrial revolution, and therefore baselines of coral reef cover are difficult to estimate. Here, we use expert and ocean-user opinion surveys to estimate baselines of global coral reef cover. The overall mean estimated baseline coral cover was 59% (±19% standard deviation, compared to an average of 58% (±18% standard deviation estimated by professional scientists. We did not find evidence of the shifting baseline syndrome, whereby respondents who first observed coral reefs more recently report lower estimates of baseline coral cover. These estimates of historical coral reef baseline cover are important for scientists, policy makers, and managers to understand the extent to which coral reefs have become depleted and to set appropriate recovery targets.

Historical baselines of coral cover on tropical reefs as estimated by expert opinion.

Science.gov (United States)

Eddy, Tyler D; Cheung, William W L; Bruno, John F

2018-01-01

Coral reefs are important habitats that represent global marine biodiversity hotspots and provide important benefits to people in many tropical regions. However, coral reefs are becoming increasingly threatened by climate change, overfishing, habitat destruction, and pollution. Historical baselines of coral cover are important to understand how much coral cover has been lost, e.g., to avoid the 'shifting baseline syndrome'. There are few quantitative observations of coral reef cover prior to the industrial revolution, and therefore baselines of coral reef cover are difficult to estimate. Here, we use expert and ocean-user opinion surveys to estimate baselines of global coral reef cover. The overall mean estimated baseline coral cover was 59% (±19% standard deviation), compared to an average of 58% (±18% standard deviation) estimated by professional scientists. We did not find evidence of the shifting baseline syndrome, whereby respondents who first observed coral reefs more recently report lower estimates of baseline coral cover. These estimates of historical coral reef baseline cover are important for scientists, policy makers, and managers to understand the extent to which coral reefs have become depleted and to set appropriate recovery targets.

Rapid survey protocol that provides dynamic information on reef condition to managers of the Great Barrier Reef.

Science.gov (United States)

Beeden, R J; Turner, M A; Dryden, J; Merida, F; Goudkamp, K; Malone, C; Marshall, P A; Birtles, A; Maynard, J A

2014-12-01

Managing to support coral reef resilience as the climate changes requires strategic and responsive actions that reduce anthropogenic stress. Managers can only target and tailor these actions if they regularly receive information on system condition and impact severity. In large coral reef areas like the Great Barrier Reef Marine Park (GBRMP), acquiring condition and impact data with good spatial and temporal coverage requires using a large network of observers. Here, we describe the result of ~10 years of evolving and refining participatory monitoring programs used in the GBR that have rangers, tourism operators and members of the public as observers. Participants complete Reef Health and Impact Surveys (RHIS) using a protocol that meets coral reef managers' needs for up-to-date information on the following: benthic community composition, reef condition and impacts including coral diseases, damage, predation and the presence of rubbish. Training programs ensure that the information gathered is sufficiently precise to inform management decisions. Participants regularly report because the demands of the survey methodology have been matched to their time availability. Undertaking the RHIS protocol we describe involves three ~20 min surveys at each site. Participants enter data into an online data management system that can create reports for managers and participants within minutes of data being submitted. Since 2009, 211 participants have completed a total of more than 10,415 surveys at more than 625 different reefs. The two-way exchange of information between managers and participants increases the capacity to manage reefs adaptively, meets education and outreach objectives and can increase stewardship. The general approach used and the survey methodology are both sufficiently adaptable to be used in all reef regions.

Macroalgal herbivory on recovering versus degrading coral reefs

Science.gov (United States)

Chong-Seng, K. M.; Nash, K. L.; Bellwood, D. R.; Graham, N. A. J.

2014-06-01

Macroalgal-feeding fishes are considered to be a key functional group on coral reefs due to their role in preventing phase shifts from coral to macroalgal dominance, and potentially reversing the shift should it occur. However, assessments of macroalgal herbivory using bioassay experiments are primarily from systems with relatively high coral cover. This raises the question of whether continued functionality can be ensured in degraded systems. It is clearly important to determine whether the species that remove macroalgae on coral-dominated reefs will still be present and performing significant algal removal on macroalgal-dominated reefs. We compared the identity and effectiveness of macroalgal-feeding fishes on reefs in two conditions post-disturbance—those regenerating with high live coral cover (20-46 %) and those degrading with high macroalgal cover (57-82 %). Using filmed Sargassum bioassays, we found significantly different Sargassum biomass loss between the two conditions; mean assay weight loss due to herbivory was 27.9 ± 4.9 % on coral-dominated reefs and 2.2 ± 1.1 % on reefs with high macroalgal cover. However, once standardised for the availability of macroalgae on the reefs, the rates of removal were similar between the two reef conditions (4.8 ± 4.1 g m-2 h-1 on coral-dominated and 5.3 ± 2.1 g m-2 h-1 on macroalgal-dominated reefs). Interestingly, the Sargassum-assay consumer assemblages differed between reef conditions; nominally grazing herbivores, Siganus puelloides and Chlorurus sordidus, and the browser , Siganus sutor, dominated feeding on high coral cover reefs, whereas browsing herbivores, Naso elegans, Naso unicornis, and Leptoscarus vaigiensis, prevailed on macroalgal-dominated reefs. It appeared that macroalgal density in the surrounding habitat had a strong influence on the species driving the process of macroalgal removal. This suggests that although the function of macroalgal removal may continue, the species responsible may change

Pacific ciguatoxins in food web components of coral reef systems in the Republic of Kiribati.

Science.gov (United States)

Mak, Yim Ling; Wai, Tak-Cheung; Murphy, Margaret B; Chan, Wing Hei; Wu, Jia Jun; Lam, James C W; Chan, Leo L; Lam, Paul K S

2013-12-17

Ciguatera fish poisoning (CFP) is a foodborne illness caused by consumption of coral reef fishes contaminated by ciguatoxins (CTXs); of the known CTX congeners, the Pacific ciguatoxins (P-CTXs) are the most toxic. Little is known about the trophodynamics of P-CTXs in coral reef systems. The present study explores the distribution, transfer, and trophic magnification of P-CTX-1, -2, and -3 in coral reef systems with high (ciguatoxic) and low (reference) ciguatoxicity in a CFP-endemic nation by use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). In ciguatoxic coral reef systems, P-CTXs were detected in 54% of herbivorous fishes [total P-CTXs weight (ww)], 72% of omnivorous fishes (<0.500-1810 pg/g ww), and 76% of carnivorous fishes (<0.500-69 500 pg/g ww), as well as a lobster ( Panulirus penicillatus ; 2.36 pg/g ww) and an octopus (Octopodidae; 2.56 pg/g ww). The dominant P-CTXs in grazers and piscivorous fishes were P-CTX-2 and -1, respectively. No significant correlation between P-CTX levels and lipid content in three target predatory fishes indicated that accumulation of P-CTXs does not depend on fat content. A weak but significant positive relationship was observed between δ(15)N and P-CTX-1 levels, but further investigation is required to confirm its biomagnification potential.

Black reefs: iron-induced phase shifts on coral reefs.

Science.gov (United States)

Kelly, Linda Wegley; Barott, Katie L; Dinsdale, Elizabeth; Friedlander, Alan M; Nosrat, Bahador; Obura, David; Sala, Enric; Sandin, Stuart A; Smith, Jennifer E; Vermeij, Mark J A; Williams, Gareth J; Willner, Dana; Rohwer, Forest

2012-03-01

The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to reefs on Millennium, Tabuaeran and Kingman. These three sites are relatively large (>0.75 km(2)). The phase shift occurs rapidly; the Kingman black reef formed within 3 years of the ship grounding. Iron concentrations in algae tissue from the Millennium black reef site were six times higher than in algae collected from reference sites. Metagenomic sequencing of the Millennium Atoll black reef-associated microbial community was enriched in iron-associated virulence genes and known pathogens. Microcosm experiments showed that corals were killed by black reef rubble through microbial activity. Together these results demonstrate that shipwrecks and their associated iron pose significant threats to coral reefs in iron-limited regions.

Whole gut microbiome composition of damselfish and cardinalfish before and after reef settlement

OpenAIRE

Parris, Darren J.; Brooker, Rohan M.; Morgan, Michael A.; Dixson, Danielle L.; Stewart, Frank J.

2016-01-01

The Pomacentridae (damselfish) and Apogonidae (cardinalfish) are among the most common fish families on coral reefs and in the aquarium trade. Members of both families undergo a pelagic larvae phase prior to settlement on the reef, where adults play key roles in benthic habitat structuring and trophic interactions. Fish-associated microbial communities (microbiomes) significantly influence fish health and ecology, yet little is known of how microbiomes change with life stage. We quantified th...

State of the coralline reefs

International Nuclear Information System (INIS)

Garzon Ferreira, Jaime; Rodriguez Ramirez, Alberto; Bejarano Chavarro, Sonia; Navas Camacho, Raul; Reyes Nivia, Catalina

2002-01-01

A diagnosis is made based primarily on the data obtained inside the national system of monitoring of coralline reefs in Colombia, under the coordination of the INVEMAR and with the support of several institutions. The paper does a diagnostic of the covering of the reef substrate, bleaching and coralline illnesses, wealth and abundance of fishes among other topics

Hierarchical drivers of reef-fish metacommunity structure.

Science.gov (United States)

MacNeil, M Aaron; Graham, Nicholas A J; Polunin, Nicholas V C; Kulbicki, Michel; Galzin, René; Harmelin-Vivien, Mireille; Rushton, Steven P

2009-01-01

Coral reefs are highly complex ecological systems, where multiple processes interact across scales in space and time to create assemblages of exceptionally high biodiversity. Despite the increasing frequency of hierarchically structured sampling programs used in coral-reef science, little progress has been made in quantifying the relative importance of processes operating across multiple scales. The vast majority of reef studies are conducted, or at least analyzed, at a single spatial scale, ignoring the implicitly hierarchical structure of the overall system in favor of small-scale experiments or large-scale observations. Here we demonstrate how alpha (mean local number of species), beta diversity (degree of species dissimilarity among local sites), and gamma diversity (overall species richness) vary with spatial scale, and using a hierarchical, information-theoretic approach, we evaluate the relative importance of site-, reef-, and atoll-level processes driving the fish metacommunity structure among 10 atolls in French Polynesia. Process-based models, representing well-established hypotheses about drivers of reef-fish community structure, were assembled into a candidate set of 12 hierarchical linear models. Variation in fish abundance, biomass, and species richness were unevenly distributed among transect, reef, and atoll levels, establishing the relative contribution of variation at these spatial scales to the structure of the metacommunity. Reef-fish biomass, species richness, and the abundance of most functional-groups corresponded primarily with transect-level habitat diversity and atoll-lagoon size, whereas detritivore and grazer abundances were largely correlated with potential covariates of larval dispersal. Our findings show that (1) within-transect and among-atoll factors primarily drive the relationship between alpha and gamma diversity in this reef-fish metacommunity; (2) habitat is the primary correlate with reef-fish metacommunity structure at

[Influence of sediments and tungsten traces on the skeletal structure of Pseudodiploria: a reef building scleractinian coral from the Veracruz Reef System National Park, Mexico].

Science.gov (United States)

Colín-García, Norberto A; Campos, Jorge E; Tello-Musi, Jose Luis; Arias-González, Jesús E

2016-09-01

Coral reefs are under intense conditions of stress caused by the anthropogenic activities in coastal areas and the increase of human population. Water effluents from urban and industrial areas carry large amounts of sediments and pollutants affecting corals populations, inducing bioerosion, increasing diseases and promoting the development of algae that compete for space with corals. In the Veracruz Reef System National Park (VRSNP) coral reefs are strongly affected by human activities carried out in the area. Gallega and Galleguilla reefs are among the most affected by wastewater discharges from the industrial (petrochemical and metallurgical) and urban areas in their vicinity. To assess the potential impact of this contamination on corals in the VRSNP, a chemical composition and morphology study of 76 Pseudodiploria colonies collected in reefs Gallega, Galleguilla, Isla Verde and Isla de Enmedio, was performed. Fragments of ~10 cm2 were collected and boric acid at 0.5 % was used to remove tissue from the skeleton; once clean, the morphology of each sample was determined with a scanning electron microscope (SEM). Subsequently, to test the chemical composition, an energy dispersion spectroscopy of X-ray chemical microanalysis (EDSX) was performed in the SEM. We found that corals from Gallega and Galleguilla reefs, located closer to human populations, presented high levels of tungsten and the skeleton exhibited multiple perforations. In contrast, corals from the farthest offshore reefs (Isla Verde and Isla de Enmedio) exhibited lower levels of tungsten and fewer perforations in their skeleton. These results demonstrated that anthropogenic activities in the NPVRS are affecting corals skeleton, highly damaging and promoting their bioerosion. The presence of traces of tungsten in the skeleton of corals is an evidence of the damage that waste discharges are causing to coral reefs. Discharges of large amounts of contaminants promoted the growth of harmful species that

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Science.gov (United States)

Wang, Guizhi; Wang, Shuling; Wang, Zhangyong; Jing, Wenping; Xu, Yi; Zhang, Zhouling; Tan, Ehui; Dai, Minhan

2018-02-01

To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L-1, appeared at low tide and the minimum, 14.0 dpm 100 L-1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2 ≥ 0.9 and P reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

Unraveling the structure and composition of Varadero Reef, an improbable and imperiled coral reef in the Colombian Caribbean

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Valeria Pizarro

2017-12-01

Full Text Available Coral reefs are commonly associated with oligotrophic, well-illuminated waters. In 2013, a healthy coral reef was discovered in one of the least expected places within the Colombian Caribbean: at the entrance of Cartagena Bay, a highly-polluted system that receives industrial and sewage waste, as well as high sediment and freshwater loads from an outlet of the Magdalena River (the longest and most populated river basin in Colombia. Here we provide the first characterization of Varadero Reef’s geomorphology and biological diversity. We also compare these characteristics with those of a nearby reference reef, Barú Reef, located in an area much less influenced by the described polluted system. Below the murky waters, we found high coral cover of 45.1% (±3.9; up to 80% in some sectors, high species diversity, including 42 species of scleractinian coral, 38 of sponge, three of lobster, and eight of sea urchin; a fish community composed of 61 species belonging to 24 families, and the typical zonation of a Caribbean fringing reef. All attributes found correspond to a reef that, according to current standards should be considered in “good condition”. Current plans to dredge part of Varadero threaten the survival of this reef. There is, therefore, an urgent need to describe the location and characteristics of Varadero as a first step towards gaining acknowledgement of its existence and garnering inherent legal and environmental protections.

Local-scale projections of coral reef futures and implications of the Paris Agreement.

Science.gov (United States)

van Hooidonk, Ruben; Maynard, Jeffrey; Tamelander, Jerker; Gove, Jamison; Ahmadia, Gabby; Raymundo, Laurie; Williams, Gareth; Heron, Scott F; Planes, Serge

2016-12-21

Increasingly frequent severe coral bleaching is among the greatest threats to coral reefs posed by climate change. Global climate models (GCMs) project great spatial variation in the timing of annual severe bleaching (ASB) conditions; a point at which reefs are certain to change and recovery will be limited. However, previous model-resolution projections (~1 × 1°) are too coarse to inform conservation planning. To meet the need for higher-resolution projections, we generated statistically downscaled projections (4-km resolution) for all coral reefs; these projections reveal high local-scale variation in ASB. Timing of ASB varies >10 years in 71 of the 87 countries and territories with >500 km 2 of reef area. Emissions scenario RCP4.5 represents lower emissions mid-century than will eventuate if pledges made following the 2015 Paris Climate Change Conference (COP21) become reality. These pledges do little to provide reefs with more time to adapt and acclimate prior to severe bleaching conditions occurring annually. RCP4.5 adds 11 years to the global average ASB timing when compared to RCP8.5; however, >75% of reefs still experience ASB before 2070 under RCP4.5. Coral reef futures clearly vary greatly among and within countries, indicating the projections warrant consideration in most reef areas during conservation and management planning.

Development of Miocene-Pliocene reef trend, St. Croix, U. S. Virgin Islands

Energy Technology Data Exchange (ETDEWEB)

Gill, I.; Eby, D.E.; Hubbard, D.K.; Frost, S.H.

1988-01-01

The Miocene-Pliocene reef trend on St. Croix, U.S. Virgin Islands, rims the present southern western coasts of the island and includes accompanying lagoonal and forereef facies. The reef trend was established on a foram-algal bank facies that represents basinal shallowing from the deep-water pelagic and hemipelagic facies of the Miocene Kingshill Limestone. Information on facies distribution and thickness is derived from rock exposures and 22 test wells drilled to a maximum depth of 91 m. The greatest thickness of the reef facies exists in a subsidiary graben on the south coast of St. Croix. The thickness of the reef section in this locality is due to preservation of the section in a downdropped block. Reef faunas include extant corals, as well as several extinct genera. Extant corals (e.g. Montastrea annularis, Diploria sp., and Porites porites) and extinct corals (e.g., Stylophora affinis, Antillea bilobata, and Thysanus sp.) are the main reef frame-builders. Coralline algea and large benthic foraminifera are significant contributors to the sediments both prior to and during scleractinian reef growth. Dolomitization and calcite cementation occur prominantly in an area corresponding to a Holocene lagoon. The spatial distribution of the dolomite suggests that the lagoon is a Tertiary feature directly related to the dolomitization process. Stable isotopic values suggest dolomitization of fluids of elevated salinity.

Sexual systems in scleractinian corals: an unusual pattern in the reef-building species Diploastrea heliopora

Science.gov (United States)

Guest, J. R.; Baird, A. H.; Goh, B. P. L.; Chou, L. M.

2012-09-01

The sexual system in corals refers to the spatial and temporal pattern of sexual function within an individual coral polyp, colony or population. Although information on sexual systems now exists for over 400 scleractinian species, data are still lacking for some important reef-building taxa. The vast majority of scleractinians are either simultaneous hermaphrodites or gonochoric with other sexual systems rarely occurring. Diploastrea heliopora is one of the most ubiquitous and easily recognised reef-building species in the Indo-West Pacific; however, surprisingly little is known about its reproductive biology. The aim of the present study was to examine the reproductive biology of D. heliopora colonies on chronically impacted, equatorial reefs south of Singapore. Here we show that in Singapore, D. heliopora is a broadcast spawner with predominantly gonochoric polyps. Colonies, however, contained male, female and a low proportion of cosexual polyps during the 14-month sampling period. The most plausible explanation for this is that polyps switch sexes with oogenic and spermatogenic cycles occasionally overlapping. This leads to colony level alternation of sex function within and between breeding seasons. While this sexual system is atypical for scleractinians, it supports molecular evidence that D. heliopora is phylogenetically distinct from species formerly in the family Faviidae.

Coral reefs and the World Bank.

Science.gov (United States)

Hatziolos, M

1997-01-01

The World Bank¿s involvement in coral reef conservation is part of a larger effort to promote the sound management of coastal and marine resources. This involves three major thrusts: partnerships, investments, networks and knowledge. As an initial partner and early supporter of the International Coral Reef Initiative (ICRI), the Bank serves as the executive planning committee of ICRI. In partnership with the World Conservation Union and the Great Barrier Reef Marine Park Authority, the Bank promotes the efforts towards the establishment and maintenance of a globally representative system of marine protected areas. In addition, the Bank invested over $120 million in coral reef rehabilitation and protection programs in several countries. Furthermore, the Bank developed a ¿Knowledge Bank¿ that would market ideas and knowledge to its clients along with investment projects. This aimed to put the best global knowledge on environmentally sustainable development in the hands of its staff and clients. During the celebration of 1997, as the International Year of the Reef, the Bank planned to cosponsor an associated event that would highlight the significance of coral reefs and encourage immediate action to halt their degradation to conserve this unique ecosystem.

Project O.R.B (Operation Reef Ball): Creating Artificial Reefs, Educating the Community

Science.gov (United States)

Phipps, A.

2012-04-01

The Project O.R.B. (Operation Reef Ball) team at South Plantation High School's Everglades Restoration & Environmental Science Magnet Program is trying to help our ailing south Florida coral reefs by constructing, deploying, and monitoring designed artificial reefs. Students partnered with the Reef Ball Foundation, local concrete companies, state parks, Girl Scouts, Sea Scouts, local universities and environmental agencies to construct concrete reef balls, each weighing approximately 500 lbs (227 kg). Students then deployed two artificial reefs consisting of over 30 concrete reef balls in two sites previously permitted for artificial reef deployment. One artificial reef was placed approximately 1.5 miles (2.4 km) offshore of Golden Beach in Miami-Dade County with the assistance of Florida Atlantic University and their research vessel. A twin reef was deployed at the mouth of the river in Oleta River State Park in Miami. Monitoring and maintenance of the sites is ongoing with semi-annual reports due to the Reef Ball Foundation and DERM (Department of Environmental Resource Management) of Miami-Dade County. A second goal of Project O.R.B. is aligned with the Florida Local Action Strategy, the Southeast Florida Coral Reef Initiative, and the U.S. Coral Reef Task Force, all of which point out the importance of awareness and education as key components to the health of our coral reefs. Project O.R.B. team members developed and published an activity book targeting elementary school students. Outreach events incorporate cascade learning where high school students teach elementary and middle school students about various aspects of coral reefs through interactive "edu-tainment" modules. Attendees learn about water sampling, salinity, beach erosion, surface runoff, water cycle, ocean zones, anatomy of coral, human impact on corals, and characteristics of a well-designed artificial reef. Middle school students snorkel on the artificial reef to witness first-hand the success

Residency and spatial use by reef sharks of an isolated seamount and its implications for conservation.

Science.gov (United States)

Barnett, Adam; Abrantes, Kátya G; Seymour, Jamie; Fitzpatrick, Richard

2012-01-01

Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (~14 km away) and one grey reef shark completed a round trip of ~250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef.

Residency and spatial use by reef sharks of an isolated seamount and its implications for conservation.

Directory of Open Access Journals (Sweden)

Adam Barnett

Full Text Available Although marine protected areas (MPAs are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (~14 km away and one grey reef shark completed a round trip of ~250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef.

Residency and Spatial Use by Reef Sharks of an Isolated Seamount and Its Implications for Conservation

Science.gov (United States)

Barnett, Adam; Abrantes, Kátya G.; Seymour, Jamie; Fitzpatrick, Richard

2012-01-01

Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (∼14 km away) and one grey reef shark completed a round trip of ∼250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef. PMID:22615782

A Time Series Study of Lophelia pertusa and Reef Megafauna Responses to Drill Cuttings Exposure on the Norwegian Margin.

Directory of Open Access Journals (Sweden)

Autun Purser

Full Text Available As hotspots of local biodiversity in the deep sea, preservation of cold-water coral reef communities is of great importance. In European waters the most extensive reefs are found at depths of 300 - 500 m on the continental margin. In Norwegian waters many of these reefs are located in areas of interest for oil and gas exploration and production. In this study drilling was carried out in the Morvin drill field in proximity to a number of small Lophelia pertusa coral reefs (closest reefs 100 m upstream and 350 m downstream of point of waste drill material release. In a novel monitoring study, ROV video surveys of 9 reefs were conducted prior, during, immediately after and >1 year after drilling operations. Behavior of coral polyps inhabiting reefs exposed to differing concentrations of drill cuttings and drilling fluids (waste drilling material were compared. Levels of expected exposure to these waste materials were determined for each reef by modelling drill cutting transport following release, using accurate in-situ hydrodynamic data collected during the drilling period and drill cutting discharge data as parameters of a dispersal model. The presence / absence of associate reef species (Acesta excavata, Paragorgia arborea and Primnoa resedaeformis were also determined from each survey video. There were no significant differences in Lophelia pertusa polyp behavior in corals modelled to have been exposed to pulses of >25 ppm drill cutting material and those modelled to be exposed to negligible concentrations of material. From the video data collected, there were no observed degradations of reef structure over time, nor reductions of associate fauna abundance, regardless of modelled exposure concentration at any of the surveyed reefs. This study focused exclusively on adult fauna, and did not assess the potential hazard posed by waste drilling material to coral or other larvae. Video data was collected by various ROV's, using different camera and

The Status of Coral Reefs in the Remote Region of Andavadoaka ...

African Journals Online (AJOL)

compared to fringing reefs (~90 per 100 m2). These reefs are not directly threatened by terrigenous sedimentation, which is considered to be one of the principle causes of reef degradation elsewhere in southwest Madagascar's extensive reef system; instead, it is over-fishing that appears to be the main threat to their ...

Topographical features of physiographic unit borders on reef flat in fringing reefs

OpenAIRE

Nakai, Tatsuo

2007-01-01

In coral reef ecosystem spatial structure of 10^1-10^3m scale provide very important aspect in coral reef conservation. Nakai (2007) showed that physiographic unit (PGU) could be set as well as zonation on reef flat of fringing reef. The borders of PGUs delimiting it from the open sea or an adjacent PGU are constituted by landforms such as reef crest or channels. In this article the landforms becoming the borders of PGUs were discussed and the PGU property was clarified.

Say what? Coral reef sounds as indicators of community assemblages and reef conditions

Science.gov (United States)

Mooney, T. A.; Kaplan, M. B.

2016-02-01

Coral reefs host some of the highest diversity of life on the planet. Unfortunately, reef health and biodiversity is declining or is threatened as a result of climate change and human influences. Tracking these changes is necessary for effective resource management, yet estimating marine biodiversity and tracking trends in ecosystem health is a challenging and expensive task, especially in many pristine reefs which are remote and difficult to access. Many fishes, mammals and invertebrates make sound. These sounds are reflective of a number of vital biological processes and are a cue for settling reef larvae. Biological sounds may be a means to quantify ecosystem health and biodiversity, however the relationship between coral reef soundscapes and the actual taxa present remains largely unknown. This study presents a comparative evaluation of the soundscape of multiple reefs, naturally differing in benthic cover and fish diversity, in the U.S. Virgin Islands National Park. Using multiple recorders per reef we characterized spacio-temporal variation in biological sound production within and among reefs. Analyses of sounds recorded over 4 summer months indicated diel trends in both fish and snapping shrimp acoustic frequency bands with crepuscular peaks at all reefs. There were small but statistically significant acoustic differences among sites on a given reef raising the possibility of potentially localized acoustic habitats. The strength of diel trends in lower, fish-frequency bands were correlated with coral cover and fish density, yet no such relationship was found with shrimp sounds suggesting that fish sounds may be of higher relevance to tracking certain coral reef conditions. These findings indicate that, in spite of considerable variability within reef soundscapes, diel trends in low-frequency sound production reflect reef community assemblages. Further, monitoring soundscapes may be an efficient means of establishing and monitoring reef conditions.

Deposition of organic material in a coral reef lagoon, One Tree Island, Great Barrier Reef

Science.gov (United States)

Koop, K.; Larkum, A. W. D.

1987-07-01

Deposition of organic material was measured at four sites on One Tree Island coral reef using fixed sediment traps. Although no reliable data were obtained for the reef crest area because of problems of resuspension, mean deposition in the backreef area amounted to some 4 g organic C m -2 day -1 whereas in the lagoon it was about 1·5 g C m -2 day -1. This amounted to mean nitrogen deposition rates of 160 and 95 mg N m -2 day -1, respectively. As primary production by turf algae, the principal producers at One Tree Island, has been estimated at about 2·3 g C m -2 day -1 for the whole reef system and the weighted mean carbon deposition is estimated at 2·2 g C m -2 day -1, it is clear that the carbon produced by plants is largely retained in the system. Nitrogen deposition, on the other hand, amounted to only about 60% of that produced by turf algae and it must be assumed that much of this leached into the water during sedimentation. Losses of nitrogen may be minimized by incorporation of dissolved nitrogen by pelagic microheterotrophs which may in turn be consumed by filter feeders before they leave the reef.

High Latitude Reefs: A Potential Refuge for Reef Builders

Science.gov (United States)

Amat, A.; Bates, N.

2003-04-01

Coral reefs globally show variable signs of deterioration or community structure changes due to a host of anthropogenic and natural factors. In these global scenarios, rates of calcification by reef builders such as Scleractinian corals are predicted to significantly decline in the future due to the increase in atmospheric CO_2. When considering the response of reefs to the present climate change, temperature effects should also be taken into account. Here, we investigate the simultaneous impact of temperature and CO_2 on the high-latitude Bermuda coral reef system (32^oN, 64^oE)through a series of in vitro experiments at different CO_2 levels and seasonally different summer (27^oC) and winter (20^oC) temperature conditions. Four species of Scleractinian corals (Porites astreoides, Diploria labyrinthiformis, Madracis mirabilis and decactis) were acclimated for three months at: 20^oC and 27^oC (both with CO_2 levels at 400 ppm (control) and 700 ppm). Growth was assessed by buoyant weight techniques during the acclimation period. Photosynthesis, respiration and calcification were measured at the end of this period using respirometric chambers. A reproduction experiment was also undertaken under 27^oC. Photosynthesis mainly remains constant or increases under high CO_2 conditions. The results of the integrated calcification measurements confirm the hypothesis that an increase in CO_2 induces a decrease in calcification. However an increase in photosynthesis can be observed when CO_2 is unfavorable for calcification suggesting that a biological control of calcification through photosynthesis could prevent a drop in the calcification potential. Buoyant weight results indicate that the CO_2 impact could be less detrimental under lower temperature. This result will be compared with the instantaneous calcification measurements in the chambers and some in situ coral growth assessments in winter and summer conditions. The consequences for the response of marginal reefs

Virus-host interactions and their roles in coral reef health and disease.

Science.gov (United States)

Thurber, Rebecca Vega; Payet, Jérôme P; Thurber, Andrew R; Correa, Adrienne M S

2017-04-01

Coral reefs occur in nutrient-poor shallow waters, constitute biodiversity and productivity hotspots, and are threatened by anthropogenic disturbance. This Review provides an introduction to coral reef virology and emphasizes the links between viruses, coral mortality and reef ecosystem decline. We describe the distinctive benthic-associated and water-column- associated viromes that are unique to coral reefs, which have received less attention than viruses in open-ocean systems. We hypothesize that viruses of bacteria and eukaryotes dynamically interact with their hosts in the water column and with scleractinian (stony) corals to influence microbial community dynamics, coral bleaching and disease, and reef biogeochemical cycling. Last, we outline how marine viruses are an integral part of the reef system and suggest that the influence of viruses on reef function is an essential component of these globally important environments.

Eco-geomorphological zonation of the Bangaram reef, Lakshadweep

Digital Repository Service at National Institute of Oceanography (India)

Deshmukh, B.; Bahuguna, A.; Nayak, S.; Dhargalkar, V.K.; Jagtap, T.G.

-morphological and ecological zones of the Bangaram reef (of atoll type), Lakshadweep islands, using remotely sensed data and adequately supported by field data. Classification system has been evolved to zone the reefs. Comparative studies have also been carried out using image...

Physical connectivity between Pulley Ridge and Dry Tortugas coral reefs under the influence of the Loop Current/Florida Current system

Science.gov (United States)

Kourafalou, V. H.; Androulidakis, Y. S.; Kang, H.; Smith, R. H.; Valle-Levinson, A.

2018-07-01

The Pulley Ridge and Dry Tortugas coral reefs are among the most pristine, but also fragile, marine ecosystems of the continental United States. Understanding connectivity processes between them and with surrounding shelf and deep areas is fundamental for their management. This study focuses on the physical processes related to the connectivity of these reefs. Unprecedented in situ time series were used at these specific reef locations, together with satellite observations and numerical simulations, to investigate the dynamics controlling local circulation on the Southwestern Florida Shelf (SWFS) under oceanic influence. The approach of the Loop Current and Florida Current (LC/FC) system to the SWFS slope can induce 0.5 to 1 m/s offshore flows impacting the Pulley Ridge and Dry Tortugas reefs. On the other hand, when the LC/FC system retreats from the slope, onshore flows can carry open-sea waters over the coral reefs. Local formation of cyclonic eddies is possible near the Dry Tortugas reefs in the LC approach case and passage of upstream LC Frontal Eddies is possible in the LC retreat case. Offshore currents ∼1 m/s over the SWFS slope were also found during periods of anticyclonic LC Eddy separation. A novel finding is the shedding and northward propagation of mesoscale anticyclonic eddies from the core of the LC along the West Florida Shelf. Eddy shedding may have a broader effect on the dynamics of the shelf around the study reef areas. Long periods of LC/FC domination over these coral reefs (reaching several weeks to months) are characterized by strong (∼1 m/s) along-shelf currents and continuous upwelling processes, which may weaken the slope stratification and bring colder, deeper waters over the shelf-break and toward the shallower shelf region.

Use of riverine through reef habitat systems by dog snapper ( Lutjanus jocu ) in eastern Brazil

Science.gov (United States)

Moura, Rodrigo L.; Francini-Filho, Ronaldo B.; Chaves, Eduardo M.; Minte-Vera, Carolina V.; Lindeman, Kenyon C.

2011-11-01

The early life history of Western Atlantic snappers from the Southern hemisphere is largely unknown. Habitat use of different life stages (i.e. size categories) of the dog snapper ( Lutjanus jocu) was examined across the largest South Atlantic reef-estuarine complex (Abrolhos Shelf, Brazil, 16-19° S). Visual surveys were conducted in different habitats across the shelf (estuary, inner-shelf reefs and mid-shelf reefs). Lutjanus jocu showed higher densities on inner-shelf habitats, with a clear increase in fish size across the shelf. Individuals mangrove and rocky habitats) and inner-shelf reefs (particularly shallow fore-reefs and tide pools). Individuals ranging 10-30 cm were broadly distributed, but consistently more abundant on inner-shelf reefs. Individuals between 30 and 40 cm were more common on mid-shelf reefs, while individuals >40 cm were recorded only on mid-shelf reefs. Literature data indicate that individuals ranging 70-80 cm are common on deep offshore reefs. This pattern suggests that the dog snapper performs ontogenetic cross-shelf migrations. Protecting portions of the different habitats used by the dog snapper during its post-settlement life cycle is highlighted as an important conservation and management measure.

Reef Development on Artificial Patch Reefs in Shallow Water of Panjang Island, Central Java

Science.gov (United States)

Munasik; Sugiyanto; Sugianto, Denny N.; Sabdono, Agus

2018-02-01

Reef restoration methods are generally developed by propagation of coral fragments, coral recruits and provide substrate for coral attachment using artificial reefs (ARs). ARs have been widely applied as a tool for reef restoration in degraded natural reefs. Successful of coral restoration is determined by reef development such as increasing coral biomass, natural of coral recruits and fauna associated. Artificial Patch Reefs (APRs) is designed by combined of artificial reefs and coral transplantation and constructed by modular circular structures in shape, were deployed from small boats by scuba divers, and are suitable near natural reefs for shallow water with low visibility of Panjang Island, Central Java. Branching corals of Acropora aspera, Montipora digitata and Porites cylindrica fragments were transplanted on to each module of two units of artificial patch reefs in different periods. Coral fragments of Acropora evolved high survival and high growth, Porites fragments have moderate survival and low growth, while fragment of Montipora show in low survival and moderate growth. Within 19 to 22 months of APRs deployment, scleractinian corals were recruited on the surface of artificial patch reef substrates. The most recruits abundant was Montastrea, followed by Poritids, Pocilloporids, and Acroporids. We conclude that artificial patch reefs with developed by coral fragments and natural coral recruitment is one of an alternative rehabilitation method in shallow reef with low visibility.

New directions in coral reef microbial ecology.

Science.gov (United States)

Garren, Melissa; Azam, Farooq

2012-04-01

Microbial processes largely control the health and resilience of coral reef ecosystems, and new technologies have led to an exciting wave of discovery regarding the mechanisms by which microbial communities support the functioning of these incredibly diverse and valuable systems. There are three questions at the forefront of discovery: What mechanisms underlie coral reef health and resilience? How do environmental and anthropogenic pressures affect ecosystem function? What is the ecology of microbial diseases of corals? The goal is to understand the functioning of coral reefs as integrated systems from microbes and molecules to regional and ocean-basin scale ecosystems to enable accurate predictions of resilience and responses to perturbations such as climate change and eutrophication. This review outlines recent discoveries regarding the microbial ecology of different microenvironments within coral ecosystems, and highlights research directions that take advantage of new technologies to build a quantitative and mechanistic understanding of how coral health is connected through microbial processes to its surrounding environment. The time is ripe for natural resource managers and microbial ecologists to work together to create an integrated understanding of coral reef functioning. In the context of long-term survival and conservation of reefs, the need for this work is immediate. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Coral reef soundscapes may not be detectable far from the reef

Science.gov (United States)

Kaplan, Maxwell B.; Mooney, T. Aran

2016-08-01

Biological sounds produced on coral reefs may provide settlement cues to marine larvae. Sound fields are composed of pressure and particle motion, which is the back and forth movement of acoustic particles. Particle motion (i.e., not pressure) is the relevant acoustic stimulus for many, if not most, marine animals. However, there have been no field measurements of reef particle motion. To address this deficiency, both pressure and particle motion were recorded at a range of distances from one Hawaiian coral reef at dawn and mid-morning on three separate days. Sound pressure attenuated with distance from the reef at dawn. Similar trends were apparent for particle velocity but with considerable variability. In general, average sound levels were low and perhaps too faint to be used as an orientation cue except very close to the reef. However, individual transient sounds that exceeded the mean values, sometimes by up to an order of magnitude, might be detectable far from the reef, depending on the hearing abilities of the larva. If sound is not being used as a long-range cue, it might still be useful for habitat selection or other biological activities within a reef.

Zooplankton From a Reef System Under the Influence of the Amazon River Plume

Directory of Open Access Journals (Sweden)

Sigrid Neumann-Leitão

2018-03-01

Full Text Available At the mouth of the Amazon River, a widespread carbonate ecosystem exists below the river plume, generating a hard-bottom reef (∼9500 km2 that includes mainly large sponges but also rhodolith beds. The mesozooplankton associated with the pelagic realm over the reef formation was characterized, considering the estuarine plume and oceanic influence. Vertical hauls were carried out using a standard plankton net with 200 μm mesh size during September 2014. An indicator index was applied to express species importance as ecological indicators in community. Information on functional traits was gathered for the most abundant copepod species. Overall, 179 zooplankton taxa were recorded. Copepods were the richest (92 species, most diverse and most abundant group, whereas meroplankton were rare and less abundant. Species diversity (>3.0 bits.ind-1 and evenness (>0.6 were high, indicating a complex community. Small holoplanktonic species dominated the zooplankton, and the total density varied from 107.98 ind. m-3 over the reef area to 2,609.24 ind. m-3 in the estuarine plume, with a significant difference between coastal and oceanic areas. The most abundant copepods were the coastal species ithona plumifera and Clausocalanus furcatus and early stages copepodites of Paracalanidae. The holoplanktonic Oikopleura, an important producer of mucous houses, was very abundant on the reefs. The indicator species index revealed three groups: (1 indicative of coastal waters under the influence of the estuarine plume [Euterpina acutifrons, Parvocalanus crassirostris, Oikopleura (Vexillaria dioica and Hydromedusae]; (2 characterized coastal and oceanic conditions (Clausocalanus; (3 characterized the reef system (O. plumifera. Two major copepods functional groups were identified and sorted according to their trophic strategy and coastal-oceanic distribution. The species that dominated the coastal area and the area over the rhodolith beds are indicators of the estuarine

Ecological Processes and Contemporary Coral Reef Management

Directory of Open Access Journals (Sweden)

Angela Dikou

2010-05-01

Full Text Available Top-down controls of complex foodwebs maintain the balance among the critical groups of corals, algae, and herbivores, thus allowing the persistence of corals reefs as three-dimensional, biogenic structures with high biodiversity, heterogeneity, resistance, resilience and connectivity, and the delivery of essential goods and services to societies. On contemporary reefs world-wide, however, top-down controls have been weakened due to reduction in herbivory levels (overfishing or disease outbreak while bottom-up controls have increased due to water quality degradation (increase in sediment and nutrient load and climate forcing (seawater warming and acidification leading to algal-dominated alternate benthic states of coral reefs, which are indicative of a trajectory towards ecological extinction. Management to reverse common trajectories of degradation for coral reefs necessitates a shift from optimization in marine resource use and conservation towards building socio-economic resilience into coral reef systems while attending to the most manageable human impacts (fishing and water quality and the global-scale causes (climate change.

NOAA Coral Reef Watch Larval Connectivity, Florida Reef Tract

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Climate change threatens even the best-protected and most remote reefs. Reef recovery following catastrophic disturbance usually requires disturbed sites be reseeded...

Role of coral reefs in global ocean production

Energy Technology Data Exchange (ETDEWEB)

Crossland, C J; Hatcher, B G; Smith, S V [CSIRO Institute of Natural Resources and Environment, Dickson, ACT (Australia)

1991-01-01

Coral reefs cover some 600 thousand square kilometres of the earth's surface (0.17% of the ocean surface). First order estimates show coral reefs to contribute about 0.05% of the estimated net CO{sub 2} fixation rate of the global oceans. Gross CO{sub 2} fixation is relatively high (of the order 700 x 10{sup 12}g C year{sup -1}), but most of this material is recycled within the reefs. Excess (net) production of organic material (E) is much smaller, of the order 20 x 10{sup 12}g C year{sup -1}. 75% of E is available for export from coral reefs to adjacent areas. Comparison of estimates for net production by reefs and their surrounding oceans indicates that the excess production by coral reefs is similar to new production in the photic zone of oligotrophic oceans. Consequently, estimates for global ocean production should as a first approximation include reefal areas with the surrounding ocean when assigning average net production rates. It can be concluded that organic production by reefs plays a relatively minor role in the global scale of fluxes and storage of elements. In comparison, the companion process of biologically-mediated inorganic carbon precipitation represents a major role for reefs. While reef production does respond on local scales to variation in ocean climate, neither the absolute rates nor the amount accumulated into organic pools appear to be either sensitive indicators or accurate recorders of climatic change in most reef systems. Similarly, the productivity of most reefs should be little affected by currently predicted environmental changes resulting from the greenhouse effect. 86 refs., 2 figs., 1 tab.

The Açu Reef morphology, distribution, and inter reef sedimentation on the outer shelf of the NE Brazil equatorial margin

Science.gov (United States)

do Nascimento Silva, Luzia Liniane; Gomes, Moab Praxedes; Vital, Helenice

2018-05-01

have trapped relict siliciclastic sediments within the three sets of reefs, west of the Açu Incised Valley and adjacent coasts. Lines evidence of easterly nearshore currents carried sediments from the old Açu Incised Valley and adjacent coasts. These incipiently drowned reefs influence the water circulation patterns of the modern shelf system, its carbonate sedimentation, and sediment transport. This study provides a new example of reef occurrence which might be more commonly observed on similar equatorial continental shelves.

Advances in monitoring the human dimension of natural resource systems: an example from the Great Barrier Reef

Science.gov (United States)

Marshall, N. A.; Bohensky, E.; Curnock, M.; Goldberg, J.; Gooch, M.; Nicotra, B.; Pert, P.; Scherl, L. M.; Stone-Jovicich, S.; Tobin, R. C.

2016-11-01

The aim of this paper is to demonstrate the feasibility and potential utility of decision-centric social-economic monitoring using data collected from Great Barrier Reef (Reef) region. The social and economic long term monitoring program (SELTMP) for the Reef is a novel attempt to monitor the social and economic dimensions of social-ecological change in a globally and nationally important region. It represents the current status and condition of the major user groups of the Reef with the potential to simultaneously consider trends, interconnections, conflicts, dependencies and vulnerabilities. Our approach was to combine a well-established conceptual framework with a strong governance structure and partnership arrangement that enabled the co-production of knowledge. The framework is a modification of the Millennium Ecosystem Assessment and it was used to guide indicator choice. Indicators were categorised as; (i) resource use and dependency, (ii) ecosystem benefits and well-being, and (iii) drivers of change. Data were collected through secondary datasets where existing and new datasets were created where not, using standard survey techniques. Here we present an overview of baseline results of new survey data from commercial-fishers (n = 210), marine-based tourism operators (n = 119), tourists (n = 2877), local residents (n = 3181), and other Australians (n = 2002). The indicators chosen describe both social and economic components of the Reef system and represent an unprecedented insight into the ways in which people currently use and depend on the Reef, the benefits that they derive, and how they perceive, value and relate to the Reef and each other. However, the success of a program such as the SELTMP can only occur with well-translated cutting-edge data and knowledge that are collaboratively produced, adaptive, and directly feeds into current management processes. We discuss how data from the SELTMP have already been incorporated into Reef management decision

The evolution of the Great Barrier Reef during the Last Interglacial Period

Science.gov (United States)

Dechnik, Belinda; Webster, Jody M.; Webb, Gregory E.; Nothdurft, Luke; Dutton, Andrea; Braga, Juan-Carlos; Zhao, Jian-xin; Duce, Stephanie; Sadler, James

2017-02-01

Reef response to Last Interglacial (LIG) sea level and palaeoenvironmental change has been well documented at a limited number of far-field sites remote from former ice sheets. However, the age and development of LIG reefs in the Great Barrier Reef (GBR) remain poorly understood due to their location beneath modern living reefs. Here we report thirty-nine new mass spectrometry U-Th ages from seven LIG platform reefs across the northern, central and southern GBR. Two distinct geochemical populations of corals were observed, displaying activity ratios consistent with either closed or open system evolution. Our closed-system ages ( 129-126 ka) provide the first reliable LIG ages for the entire GBR. Combined with our open-system model ages, we are able to constrain the interval of significant LIG reef growth in the southern GBR to between 129-121 ka. Using age-elevation data in conjunction with newly defined coralgal assemblages and sedimentary facies analysis we have defined three distinct phases of LIG reef development in response to major sea level and oceanographic changes. These phases include: Phase 1 (> 129 ka), a shallow-water coralgal colonisation phase following initial flooding of the older, likely Marine Isotope Stage 7 (MIS7) antecedent platform; Phase 2 ( 129 ka), a near drowning event in response to rapid sea level rise and greater nutrient-rich upwelling and; Phase 3 ( 128-121 ka), establishment of significant reef framework through catch-up reef growth, initially characterised by deeper, more turbid coralgal assemblages (Phase 3a) that transition to shallow-water assemblages following sea level stabilisation (Phase 3b). Coralgal assemblage analysis indicates that the palaeoenvironments during initial reef growth phases (1 and 2) of the LIG were significantly different than the initial reef growth phases in the Holocene. However, the similar composition of ultimate shallow-water coralgal assemblages and slow reef accretion rates following stabilisation

Coral Reefs Under Rapid Climate Change and Ocean Acidification

Science.gov (United States)

Hoegh-Guldberg, O.; Mumby, P. J.; Hooten, A. J.; Steneck, R. S.; Greenfield, P.; Gomez, E.; Harvell, C. D.; Sale, P. F.; Edwards, A. J.; Caldeira, K.; Knowlton, N.; Eakin, C. M.; Iglesias-Prieto, R.; Muthiga, N.; Bradbury, R. H.; Dubi, A.; Hatziolos, M. E.

2007-12-01

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

No Reef Is an Island: Integrating Coral Reef Connectivity Data into the Design of Regional-Scale Marine Protected Area Networks.

Science.gov (United States)

Schill, Steven R; Raber, George T; Roberts, Jason J; Treml, Eric A; Brenner, Jorge; Halpin, Patrick N

2015-01-01

We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA) network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008-2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, a conservation planning software tool, to identify a regional coral reef MPA network design that meets conservation goals, minimizes underlying threats, and maintains coral reef connectivity. Our results suggest that approximately 77% of coral reefs identified as having a high regional connectivity value are not included in the existing MPA network. This research is unique because we quantify and report coral larval connectivity data by marine ecoregions and Exclusive Economic Zones (EZZ) and use this information to identify gaps in the current Caribbean-wide MPA network by integrating asymmetric connectivity information in Marxan to design a regional MPA network that includes important reef network connections. The identification of important reef connectivity metrics guides the selection of priority conservation areas and supports resilience at the whole system level into the future.

No Reef Is an Island: Integrating Coral Reef Connectivity Data into the Design of Regional-Scale Marine Protected Area Networks.

Directory of Open Access Journals (Sweden)

Steven R Schill

Full Text Available We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008-2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, a conservation planning software tool, to identify a regional coral reef MPA network design that meets conservation goals, minimizes underlying threats, and maintains coral reef connectivity. Our results suggest that approximately 77% of coral reefs identified as having a high regional connectivity value are not included in the existing MPA network. This research is unique because we quantify and report coral larval connectivity data by marine ecoregions and Exclusive Economic Zones (EZZ and use this information to identify gaps in the current Caribbean-wide MPA network by integrating asymmetric connectivity information in Marxan to design a regional MPA network that includes important reef network connections. The identification of important reef connectivity metrics guides the selection of priority conservation areas and supports resilience at the whole system level into the future.

Reefs for the future: Resilience of coral reefs in the main Hawaiian Islands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Declining health of coral reef ecosystems led scientists to search for factors that support reef resilience: the ability of reefs to resist and recover from...

Potential effects of invasive Pterois volitans in coral reefs

Directory of Open Access Journals (Sweden)

Banamali Maji

2016-01-01

Full Text Available The invasion of predatory lionfish (Pterois volitans represents a major threat to the western Atlantic coral reef ecosystems. The proliferation of venomous, fast reproducing and aggressive P. volitans in coral reefs causes severe declines in the abundance and diversity of reef herbivores. There is also widespread cannibalism amongst P. volitans populations. A mathematical model is proposed to study the effects of predation on the biomass of herbivorous reef fishes by considering two life stages and intraguild predation of P. volitans population with harvesting of adult P. volitans. The system undergoes a supercritical Hopf bifurcation when the invasiveness of P. volitans crosses a certain critical value. It is observed that cannibalism of P. volitans induces stability in the system even with high invasiveness of adult P. volitans. The dynamic instability of the system due to higher invasiveness of P. volitans can be controlled by increasing the rate of harvesting of P. volitans. It is also proven that P. volitans goes extinct when the harvest rate is greater than some critical threshold value. These results indicate that the dynamical behaviour of the model is very sensitive to the harvesting of P. volitans, which in turn is useful in the conservation of reef herbivores.

Coral Reef Color: Remote and In-Situ Imaging Spectroscopy of Reef Structure and Function

Science.gov (United States)

Hochberg, E. J.

2016-02-01

Coral reefs are threatened at local to global scales by a litany of anthropogenic impacts, including overfishing, coastal development, marine and watershed pollution, rising ocean temperatures, and ocean acidification. However, available data for the primary indicator of coral reef condition — proportional cover of living coral — are surprisingly sparse and show patterns that contradict the prevailing understanding of how environment impacts reef condition. Remote sensing is the only available tool for acquiring synoptic, uniform data on reef condition at regional to global scales. Discrimination between coral and other reef benthos relies on narrow wavebands afforded by imaging spectroscopy. The same spectral information allows non-invasive quantification of photosynthetic pigment composition, which shows unexpected phenological trends. There is also potential to link biodiversity with optical diversity, though there has been no effort in that direction. Imaging spectroscopy underlies the light-use efficiency model for reef primary production by quantifying light capture, which in turn indicates biochemical capacity for CO2 assimilation. Reef calcification is strongly correlated with primary production, suggesting the possibility for an optics-based model of that aspect of reef function, as well. By scaling these spectral models for use with remote sensing, we can vastly improve our understanding of reef structure, function, and overall condition across regional to global scales. By analyzing those remote sensing products against ancillary environmental data, we can construct secondary models to predict reef futures in the era of global change. This final point is the objective of CORAL (COral Reef Airborne Laboratory), a three-year project funded under NASA's Earth Venture Suborbital-2 program to investigate the relationship between coral reef condition at the ecosystem scale and various nominal biogeophysical forcing parameters.

Molluscan subfossil assemblages reveal the long-term deterioration of coral reef environments in Caribbean Panama.

Science.gov (United States)

Cramer, Katie L; Leonard-Pingel, Jill S; Rodríguez, Félix; Jackson, Jeremy B C

2015-07-15

Caribbean reef corals have declined sharply since the 1980s, but the lack of prior baseline data has hindered identification of drivers of change. To assess anthropogenic change in reef environments over the past century, we tracked the composition of subfossil assemblages of bivalve and gastropod mollusks excavated from pits below lagoonal and offshore reefs in Bocas del Toro, Panama. The higher prevalence of (a) infaunal suspension-feeding bivalves and herbivorous and omnivorous gastropods in lagoons and (b) epifaunal and suspension-feeding bivalves and carnivorous and suspension-feeding gastropods offshore reflected the greater influence of land-based nutrients/sediments within lagoons. Temporal changes indicated deteriorating environmental conditions pre-1960 in lagoons and post-1960 offshore, with offshore communities becoming more similar to lagoonal ones since 1960. Relative abundances of dominant bivalve species tracked those of their coral hosts, revealing broader ecosystem effects of coral community change. The nature and timing of changes implicate land-based runoff in reef deterioration. Copyright © 2015. Published by Elsevier Ltd.

Coral reefs in the Anthropocene.

Science.gov (United States)

Hughes, Terry P; Barnes, Michele L; Bellwood, David R; Cinner, Joshua E; Cumming, Graeme S; Jackson, Jeremy B C; Kleypas, Joanie; van de Leemput, Ingrid A; Lough, Janice M; Morrison, Tiffany H; Palumbi, Stephen R; van Nes, Egbert H; Scheffer, Marten

2017-05-31

Coral reefs support immense biodiversity and provide important ecosystem services to many millions of people. Yet reefs are degrading rapidly in response to numerous anthropogenic drivers. In the coming centuries, reefs will run the gauntlet of climate change, and rising temperatures will transform them into new configurations, unlike anything observed previously by humans. Returning reefs to past configurations is no longer an option. Instead, the global challenge is to steer reefs through the Anthropocene era in a way that maintains their biological functions. Successful navigation of this transition will require radical changes in the science, management and governance of coral reefs.

Does reef architectural complexity influence resource availability for a large reef-dwelling invertebrate?

Science.gov (United States)

Lozano-Álvarez, Enrique; Luviano-Aparicio, Nelia; Negrete-Soto, Fernando; Barradas-Ortiz, Cecilia; Aguíñiga-García, Sergio; Morillo-Velarde, Piedad S.; Álvarez-Filip, Lorenzo; Briones-Fourzán, Patricia

2017-10-01

In coral reefs, loss of architectural complexity and its associated habitat degradation is expected to affect reef specialists in particular due to changes in resource availability. We explored whether these features could potentially affect populations of a large invertebrate, the spotted spiny lobster Panulirus guttatus, which is an obligate Caribbean coral reef-dweller with a limited home range. We selected two separate large coral reef patches in Puerto Morelos (Mexico) that differed significantly in structural complexity and level of degradation, as assessed via the rugosity index, habitat assessment score, and percent cover of various benthic components. On each reef, we estimated density of P. guttatus and sampled lobsters to analyze their stomach contents, three different condition indices, and stable isotopes (δ15N and δ13C) in muscle. Lobster density did not vary with reef, suggesting that available crevices in the less complex patch still provided adequate refuge to these lobsters. Lobsters consumed many food types, dominated by mollusks and crustaceans, but proportionally more crustaceans (herbivore crabs) in the less complex patch, which had more calcareous macroalgae and algal turf. Lobsters from both reefs had a similar condition (all three indices) and mean δ15N, suggesting a similar quality of diet between reefs related to their opportunistic feeding, but differed in mean δ13C values, reflecting the different carbon sources between reefs and providing indirect evidence of individuals of P. guttatus foraging exclusively over their home reef. Overall, we found no apparent effects of architectural complexity, at least to the degree observed in our less complex patch, on density, condition, or trophic level of P. guttatus.

Allelopathy in the tropical alga Lobophora variegata (Phaeophyceae): mechanistic basis for a phase shift on mesophotic coral reefs?

Science.gov (United States)

Slattery, Marc; Lesser, Michael P

2014-06-01

Macroalgal phase shifts on Caribbean reefs have been reported with increasing frequency, and recent reports of these changes on mesophotic coral reefs have raised questions regarding the mechanistic processes behind algal population expansions to deeper depths. The brown alga Lobophora variegata is a dominant species on many shallow and deep coral reefs of the Caribbean and Pacific, and it increased in percent cover (>50%) up to 61 m on Bahamian reefs following the invasion of the lionfish Pterois volitans. We examined the physiological and ecological constraints contributing to the spread of Lobophora on Bahamian reefs across a mesophotic depth gradient from 30 to 61 m, pre- and post-lionfish invasion. Results indicate that there were no physiological limitations to the depth distribution of Lobophora within this range prior to the lionfish invasion. Herbivory by acanthurids and scarids in algal recruitment plots at mesophotic depths was higher prior to the lionfish invasion, and Lobophora chemical defenses were ineffective against an omnivorous fish species. In contrast, Lobophora exhibited significant allelopathic activity against the coral Montastraea cavernosa and the sponge Agelas clathrodes in laboratory assays. These data indicate that when lionfish predation on herbivorous fish released Lobophora from grazing pressure at depth, Lobophora expanded its benthic cover to a depth of 61 m, where it replaced the dominant coral and sponge species. Our results suggest that this chemically defended alga may out-compete these species in situ, and that mesophotic reefs may be further impacted in the near future as Lobophora continues to expand to its compensation point. © 2013 Phycological Society of America.

Uranium mineralization of the Witwatersrand and Dominion Reef systems

International Nuclear Information System (INIS)

Simpson, P.R.; Bowles, J.F.W.

1977-01-01

Uranium-bearing minerals in the Witwatersrand and Dominion Reef sediments have been studied by ore microscopic, electron microprobe, fission track and neutron activation analytical methods to determine the controls of uranium mineralization. In the Dominion Reef, which represents a high-energy banket type of depositional environment, allogenic thorian uraninite occurs in hydraulic equivalence with allogenic pyrite, quartz and possibly also gold in the sediments which have uranium-thorium ratios between 3.1 and 5.6 indicating substantial amounts of thorium-rich resistate minerals. The Witwatersrand sediments have uranium-thorium ratios ranging between 7.1 and 19.6 indicating lesser amounts of resistates which is consistent with the lower-energy depositional environment. The proximal or nearshore deposits are of banket type but are distinguished from the Dominion Reef by the abundance of concretionary pyrite formed within the Basin and the presence of carbonaceous matter. The distal deposits formed at greater distance from the shoreline contain decaying organic material which has precipitated both uranium and gold from solution. Subsequent metamorphism has resulted in the formation of carbonaceous material bearing finely disseminated low-thorium pitchblende and a fine dissemination of gold associated with sulphides and arsenides. (author)

Modeling Reef Island Morphodynamics in Profile and Plan View

Science.gov (United States)

Ashton, A. D.; Ortiz, A. C.; Lorenzo-Trueba, J.

2016-12-01

Reef islands are carbonate detrital landforms perched atop shallow reef flats of atolls and barrier reef systems. Often comprising the only subaerial, inhabitable land of many island chains and island nations, these low-lying, geomorphically active landforms face considerable hazards from climate change. While there hazards include wave overtopping and groundwater salinization, sea-level rise and wave climate change will affect sediment transport and shoreline dynamics, including the possibility for wholesale reorganization of the islands themselves. Here we present a simplified morphodynamic model that can spatially quantify the potential impacts of climate change on reef islands. Using parameterizations of sediment transport pathways and feedbacks from previously presented XBeach modeling results, we investigate how sea-level rise, change in storminess, and different carbonate production rates can affect the profile evolution of reef islands, including feedbacks with the shallow reef flat that bounds the islands offshore (and lagoonward). Model results demonstrate that during rising sea levels, the reef flat can serve as a sediment trap, starving reef islands of detrital sediment that could otherwise fortify the shore against sea-level-rise-driven erosion. On the other hand, if reef flats are currently shallow (likely due to geologic inheritance or biologic cementation processes) such that sea-level rise does not result in sediment accumulation on the flat, reef island shorelines may be more resilient to rising seas. We extend the model in plan view to examine how long-term (decadal) changes in wave approach direction could affect reef island shoreline orientation. We compare model results to historical and geologic change for different case studies on the Marshall Islands. This simplified modeling approach, focusing on boundary dynamics and mass fluxes, provides a quantitative tool to predict the response of reef island environments to climate change.

Timing and locations of reef fish spawning off the southeastern United States.

Directory of Open Access Journals (Sweden)

Nicholas A Farmer

Full Text Available Managed reef fish in the Atlantic Ocean of the southeastern United States (SEUS support a multi-billion dollar industry. There is a broad interest in locating and protecting spawning fish from harvest, to enhance productivity and reduce the potential for overfishing. We assessed spatiotemporal cues for spawning for six species from four reef fish families, using data on individual spawning condition collected by over three decades of regional fishery-independent reef fish surveys, combined with a series of predictors derived from bathymetric features. We quantified the size of spawning areas used by reef fish across many years and identified several multispecies spawning locations. We quantitatively identified cues for peak spawning and generated predictive maps for Gray Triggerfish (Balistes capriscus, White Grunt (Haemulon plumierii, Red Snapper (Lutjanus campechanus, Vermilion Snapper (Rhomboplites aurorubens, Black Sea Bass (Centropristis striata, and Scamp (Mycteroperca phenax. For example, Red Snapper peak spawning was predicted in 24.7-29.0°C water prior to the new moon at locations with high curvature in the 24-30 m depth range off northeast Florida during June and July. External validation using scientific and fishery-dependent data collections strongly supported the predictive utility of our models. We identified locations where reconfiguration or expansion of existing marine protected areas would protect spawning reef fish. We recommend increased sampling off southern Florida (south of 27° N, during winter months, and in high-relief, high current habitats to improve our understanding of timing and location of reef fish spawning off the southeastern United States.

Local Stressors, Resilience, and Shifting Baselines on Coral Reefs.

Science.gov (United States)

McLean, Matthew; Cuetos-Bueno, Javier; Nedlic, Osamu; Luckymiss, Marston; Houk, Peter

2016-01-01

Understanding how and why coral reefs have changed over the last twenty to thirty years is crucial for sustaining coral-reef resilience. We used a historical baseline from Kosrae, a typical small island in Micronesia, to examine changes in fish and coral assemblages since 1986. We found that natural gradients in the spatial distribution of fish and coral assemblages have become amplified, as island geography is now a stronger determinant of species abundance patterns, and habitat forming Acropora corals and large-bodied fishes that were once common on the leeward side of the island have become scarce. A proxy for fishing access best predicted the relative change in fish assemblage condition over time, and in turn, declining fish condition was the only factor correlated with declining coral condition, suggesting overfishing may have reduced ecosystem resilience. Additionally, a proxy for watershed pollution predicted modern coral assemblage condition, suggesting pollution is also reducing resilience in densely populated areas. Altogether, it appears that unsustainable fishing reduced ecosystem resilience, as fish composition has shifted to smaller species in lower trophic levels, driven by losses of large predators and herbivores. While prior literature and anecdotal reports indicate that major disturbance events have been rare in Kosrae, small localized disturbances coupled with reduced resilience may have slowly degraded reef condition through time. Improving coral-reef resilience in the face of climate change will therefore require improved understanding and management of growing artisanal fishing pressure and watershed pollution.

Local Stressors, Resilience, and Shifting Baselines on Coral Reefs.

Directory of Open Access Journals (Sweden)

Matthew McLean

Full Text Available Understanding how and why coral reefs have changed over the last twenty to thirty years is crucial for sustaining coral-reef resilience. We used a historical baseline from Kosrae, a typical small island in Micronesia, to examine changes in fish and coral assemblages since 1986. We found that natural gradients in the spatial distribution of fish and coral assemblages have become amplified, as island geography is now a stronger determinant of species abundance patterns, and habitat forming Acropora corals and large-bodied fishes that were once common on the leeward side of the island have become scarce. A proxy for fishing access best predicted the relative change in fish assemblage condition over time, and in turn, declining fish condition was the only factor correlated with declining coral condition, suggesting overfishing may have reduced ecosystem resilience. Additionally, a proxy for watershed pollution predicted modern coral assemblage condition, suggesting pollution is also reducing resilience in densely populated areas. Altogether, it appears that unsustainable fishing reduced ecosystem resilience, as fish composition has shifted to smaller species in lower trophic levels, driven by losses of large predators and herbivores. While prior literature and anecdotal reports indicate that major disturbance events have been rare in Kosrae, small localized disturbances coupled with reduced resilience may have slowly degraded reef condition through time. Improving coral-reef resilience in the face of climate change will therefore require improved understanding and management of growing artisanal fishing pressure and watershed pollution.

Effects of Great Barrier Reef degradation on recreational reef-trip demand: a contingent behaviour approach

NARCIS (Netherlands)

Kragt, M.E.; Roebeling, P.C.; Ruijs, A.J.W.

2009-01-01

There is a growing concern that increased nutrient and sediment runoff from river catchments are a potential source of coral reef degradation. Degradation of reefs may affect the number of tourists visiting the reef and, consequently, the economic sectors that rely on healthy reefs for their income

Zooplankton diversity across three Red Sea reefs using pyrosequencing

KAUST Repository

Pearman, John K.

2014-07-30

Coral reefs are considered among the most diverse ecosystems on Earth, yet little is known about the diversity of plankton in the surrounding water column. Moreover, few studies have utilized genomic methods to investigate zooplankton diversity in any habitat. This study investigated the diversity of taxa by sampling 45 stations around three reef systems in the central/southern Red Sea. The diversity of metazoan plankton was investigated by targeting the 18S rRNA gene and clustering OTUs at 97% sequence similarity. A total of 754 and 854 metazoan OTUs were observed in the data set for the 1380F and 1389F primer sets respectively. The phylum Arthropoda dominated both primer sets accounting for ~60% of reads followed by Cnidaria (~20%). Only about 20% of OTUs were shared between all three reef systems and the relation between geographic distance and Jaccard Similarity measures was not significant. Cluster analysis showed that there was no distinct split between reefs and stations from different reefs clustered together both for metazoans as a whole and for the phyla Arthropoda, Cnidaria and Chordata separately. This suggests that distance may not be a determining factor in the taxonomic composition of stations.

The importance of spatial fishing behavior for coral reef resilience

Science.gov (United States)

Rassweiler, A.; Lauer, M.; Holbrook, S. J.

2016-02-01

Coral reefs are dynamic systems in which disturbances periodically reduce coral cover but are normally followed by recovery of the coral community. However, human activity may have reduced this resilience to disturbance in many coral reef systems, as an increasing number of reefs have undergone persistent transitions from coral-dominated to macroalgal-dominated community states. Fishing on herbivores may be one cause of reduced reef resilience, as lower herbivory can make it easier for macroalgae to become established after a disturbance. Despite the acknowledged importance of fishing, relatively little attention has been paid to the potential for feedbacks between ecosystem state and fisher behavior. Here we couple methods from environmental anthropology and ecology to explore these feedbacks between small-scale fisheries and coral reefs in Moorea, French Polynesia. We document how aspects of ecological state such as the abundance of macroalgae affect people's preference for fishing in particular lagoon habitats. We then incorporate biases towards fishing in certain ecological states into a spatially explicit bio-economic model of ecological dynamics and fishing in Moorea's lagoons. We find that feedbacks between spatial fishing behavior and ecological state can have critical effects on coral reefs. Presence of these spatial behaviors consistently leads to more coherence across the reef-scape. However, whether this coherence manifests as increased resilience or increased fragility depends on the spatial scales of fisher movement and the magnitudes of disturbance. These results emphasize the potential importance of spatially-explicit fishing behavior for reef resilience, but also the complexity of the feedbacks involved.

Octocoral Species Assembly and Coexistence in Caribbean Coral Reefs.

Science.gov (United States)

Velásquez, Johanna; Sánchez, Juan A

2015-01-01

What are the determinant factors of community assemblies in the most diverse ecosystem in the ocean? Coral reefs can be divided in continental (i.e., reefs that develop on the continental shelf, including siliciclastic reefs) and oceanic (i.e., far off the continental shelf, usually on volcanic substratum); whether or not these habitat differences impose community-wide ecological divergence or species exclusion/coexistence with evolutionary consequences, is unknown. Studying Caribbean octocorals as model system, we determined the phylogenetic community structure in a coral reef community, making emphasis on species coexistence evidenced on trait evolution and environmental feedbacks. Forty-nine species represented in five families constituted the species pool from which a phylogenetic tree was reconstructed using mtDNA. We included data from 11 localities in the Western Caribbean (Colombia) including most reef types. To test diversity-environment and phenotype-environment relationships, phylogenetic community structure and trait evolution we carried out comparative analyses implementing ecological and evolutionary approaches. Phylogenetic inferences suggest clustering of oceanic reefs (e.g., atolls) contrasting with phylogenetic overdispersion of continental reefs (e.g., reefs banks). Additionally, atolls and barrier reefs had the highest species diversity (Shannon index) whereas phylogenetic diversity was higher in reef banks. The discriminant component analysis supported this differentiation between oceanic and continental reefs, where continental octocoral species tend to have greater calyx apertures, thicker branches, prominent calyces and azooxanthellate species. This analysis also indicated a clear separation between the slope and the remaining habitats, caused by the presence or absence of Symbiodinium. K statistic analysis showed that this trait is conserved as well as the branch shape. There was strong octocoral community structure with opposite diversity

Octocoral Species Assembly and Coexistence in Caribbean Coral Reefs.

Directory of Open Access Journals (Sweden)

Johanna Velásquez

Full Text Available What are the determinant factors of community assemblies in the most diverse ecosystem in the ocean? Coral reefs can be divided in continental (i.e., reefs that develop on the continental shelf, including siliciclastic reefs and oceanic (i.e., far off the continental shelf, usually on volcanic substratum; whether or not these habitat differences impose community-wide ecological divergence or species exclusion/coexistence with evolutionary consequences, is unknown.Studying Caribbean octocorals as model system, we determined the phylogenetic community structure in a coral reef community, making emphasis on species coexistence evidenced on trait evolution and environmental feedbacks. Forty-nine species represented in five families constituted the species pool from which a phylogenetic tree was reconstructed using mtDNA. We included data from 11 localities in the Western Caribbean (Colombia including most reef types. To test diversity-environment and phenotype-environment relationships, phylogenetic community structure and trait evolution we carried out comparative analyses implementing ecological and evolutionary approaches.Phylogenetic inferences suggest clustering of oceanic reefs (e.g., atolls contrasting with phylogenetic overdispersion of continental reefs (e.g., reefs banks. Additionally, atolls and barrier reefs had the highest species diversity (Shannon index whereas phylogenetic diversity was higher in reef banks. The discriminant component analysis supported this differentiation between oceanic and continental reefs, where continental octocoral species tend to have greater calyx apertures, thicker branches, prominent calyces and azooxanthellate species. This analysis also indicated a clear separation between the slope and the remaining habitats, caused by the presence or absence of Symbiodinium. K statistic analysis showed that this trait is conserved as well as the branch shape.There was strong octocoral community structure with opposite

Whole gut microbiome composition of damselfish and cardinalfish before and after reef settlement.

Science.gov (United States)

Parris, Darren J; Brooker, Rohan M; Morgan, Michael A; Dixson, Danielle L; Stewart, Frank J

2016-01-01

The Pomacentridae (damselfish) and Apogonidae (cardinalfish) are among the most common fish families on coral reefs and in the aquarium trade. Members of both families undergo a pelagic larvae phase prior to settlement on the reef, where adults play key roles in benthic habitat structuring and trophic interactions. Fish-associated microbial communities (microbiomes) significantly influence fish health and ecology, yet little is known of how microbiomes change with life stage. We quantified the taxonomic (16S rRNA gene) composition of whole gut microbiomes from ten species of damselfish and two species of cardinalfish from Lizard Island, Australia, focusing specifically on comparisons between pelagic larvae prior to settlement on the reef versus post-settlement juvenile and adult individuals. On average, microbiome phylogenetic diversity increased from pre- to post-settlement, and was unrelated to the microbial composition in the surrounding water column. However, this trend varied among species, suggesting stochasticity in fish microbiome assembly. Pre-settlement fish were enriched with bacteria of the Endozoicomonaceae, Shewanellaceae, and Fusobacteriaceae, whereas settled fish harbored higher abundances of Vibrionaceae and Pasteurellaceae. Several individual operational taxonomic units, including ones related to Vibrio harveyi, Shewanella sp., and uncultured Endozoicomonas bacteria, were shared between both pre and post-settlement stages and may be of central importance in the intestinal niche across development. Richness of the core microbiome shared among pre-settlement fish was comparable to that of settled individuals, suggesting that changes in diversity with adulthood are due to the acquisition or loss of host-specific microbes. These results identify a key transition in microbiome structure across host life stage, suggesting changes in the functional contribution of microbiomes over development in two ecologically dominant reef fish families.

Black reefs: iron-induced phase shifts on coral reefs

NARCIS (Netherlands)

Wegley Kelly, L.; Barott, K.L.; Dinsdale, E.; Friedlander, A.M.; Nosrat, B.; Obura, D.; Sala, E.; Sandin, S.A.; Smith, J.E.; Vermeij, M.J.A.; Williams, G.J.; Willner, D.; Rohwer, F.

2012-01-01

The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the

Human activities threaten coral reefs

International Nuclear Information System (INIS)

Tveitdal, Svein; Bjoerke, Aake

2002-01-01

Research indicates that 58 per cent of the coral reefs of the world are threatened by human activities. Pollution and global heating represent some of the threats. Coral reefs just beneath the surface of the sea are very sensitive to temperature changes. Since 1979, mass death of coral reefs has been reported increasingly often. More than 1000 marine species live in the coral reefs, among these are one fourth of all marine species of fish. It is imperative that the coral reefs be preserved, as coastal communities all over the world depend on them as sources of food and as they are the raw materials for important medicines. The article discusses the threats to the coral reefs in general and does not single out any particular energy-related activity as the principal threat. For instance, the El-Nino phenomenon of the Pacific Ocean is probably involved in mass death of coral reefs and in the North Sea large parts of deep-water reefs have been crushed by heavy beam trawlers fishing for bottom fish

Coralline reefs classification in Banco Chinchorro, Mexico

Science.gov (United States)

Contreras-Silva, Ameris I.; López-Caloca, Alejandra A.

2009-09-01

The coralline reefs in Banco Chinchorro, Mexico, are part of the great reef belt of the western Atlantic. This reef complex is formed by an extensive coralline structure with great biological richness and diversity of species. These colonies are considered highly valuable ecologically, economically, socially and culturally, and they also inherently provide biological services. Fishing and scuba diving have been the main economic activities in this area for decades. However, in recent years, there has been a bleaching process and a decrease of the coral colonies in Quintana Roo, Mexico. This drop is caused mainly by the production activities performed in the oil platforms and the presence of hurricanes among other climatic events. The deterioration of the reef system can be analyzed synoptically using remote sensing. Thanks to this type of analysis, it is possible to have updated information of the reef conditions. In this paper, satellite imagery in Landsat TM and SPOT 5 is applied in the coralline reefs classification in the 1980- 2006 time period. Thus, an integral analysis of the optical components of the water surrounding the coralline reefs, such as on phytoplankton, sediments, yellow substance and even on the same water adjacent to the coral colonies, is performed. The use of a texture algorithm (Markov Random Field) was a key tool for their identification. This algorithm, does not limit itself to image segmentation, but also works on edge detection. In future work the multitemporal analysis of the results will determine the deterioration degree of these habitats and the conservation status of the coralline areas.

Learning priors for Bayesian computations in the nervous system.

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Max Berniker

Full Text Available Our nervous system continuously combines new information from our senses with information it has acquired throughout life. Numerous studies have found that human subjects manage this by integrating their observations with their previous experience (priors in a way that is close to the statistical optimum. However, little is known about the way the nervous system acquires or learns priors. Here we present results from experiments where the underlying distribution of target locations in an estimation task was switched, manipulating the prior subjects should use. Our experimental design allowed us to measure a subject's evolving prior while they learned. We confirm that through extensive practice subjects learn the correct prior for the task. We found that subjects can rapidly learn the mean of a new prior while the variance is learned more slowly and with a variable learning rate. In addition, we found that a Bayesian inference model could predict the time course of the observed learning while offering an intuitive explanation for the findings. The evidence suggests the nervous system continuously updates its priors to enable efficient behavior.

Socio-ecological dynamics of Caribbean coral reef ecosystems and conservation opinion propagation.

Science.gov (United States)

Thampi, Vivek A; Anand, Madhur; Bauch, Chris T

2018-02-07

The Caribbean coral reef ecosystem has experienced a long history of deterioration due to various stressors. For instance, over-fishing of parrotfish - an important grazer of macroalgae that can prevent destructive overgrowth of macroalgae - has threatened reef ecosystems in recent decades and stimulated conservation efforts such as the formation of marine protected areas. Here we develop a mathematical model of coupled socio-ecological interactions between reef dynamics and conservation opinion dynamics to better understand how natural and human factors interact individually and in combination to determine coral reef cover. We find that the coupling opinion and reef systems generates complex dynamics that are difficult to anticipate without use of a model. For instance, instead of converging to a stable state of constant coral cover and conservationist opinion, the system can oscillate between low and high live coral cover as human opinion oscillates in a boom-bust cycle between complacency and concern. Out of various possible parameter manipulations, we also find that raising awareness of coral reef endangerment best avoids counter-productive nonlinear feedbacks and always increases and stabilizes live coral reef cover. In conclusion, an improved understanding of coupled opinion-reef dynamics under anthrogenic stressors is possible using coupled socio-ecological models, and such models should be further researched.

Benthic foraminifera baseline assemblages from a coastal nearshore reef complex on the central Great Barrier Reef

Science.gov (United States)

Johnson, Jamie; Perry, Chris; Smithers, Scott; Morgan, Kyle

2016-04-01

Declining water quality due to river catchment modification since European settlement (c. 1850 A.D.) represents a major threat to the health of coral reefs on Australia's Great Barrier Reef (GBR), particularly for those located in the coastal waters of the GBR's inner-shelf. These nearshore reefs are widely perceived to be most susceptible to declining water quality owing to their close proximity to river point sources. Despite this, nearshore reefs have been relatively poorly studied with the impacts and magnitudes of environmental degradation still remaining unclear. This is largely due to ongoing debates concerning the significance of increased sediment yields against naturally high background sedimentary regimes. Benthic foraminifera are increasingly used as tools for monitoring environmental and ecological change on coral reefs. On the GBR, the majority of studies have focussed on the spatial distributions of contemporary benthic foraminiferal assemblages. While baseline assemblages from other environments (e.g. inshore reefs and mangroves) have been described, very few records exist for nearshore reefs. Here, we present preliminary results from the first palaeoecological study of foraminiferal assemblages of nearshore reefs on the central GBR. Cores were recovered from the nearshore reef complex at Paluma Shoals using percussion techniques. Recovery was 100%, capturing the entire Holocene reef sequence of the selected reef structures. Radiocarbon dating and subsequent age-depth modelling techniques were used to identify reef sequences pre-dating European settlement. Benthic foraminifera assemblages were reconstructed from the identified sequences to establish pre-European ecological baselines with the aim of providing a record of foraminiferal distribution during vertical reef accretion and against which contemporary ecological change may be assessed.

Trophodynamics as a Tool for Understanding Coral Reef Ecosystems

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Stacy L. Bierwagen

2018-02-01

Full Text Available The increased frequency of publications concerning trophic ecology of coral reefs suggests a degree of interest in the role species and functional groups play in energy flow within these systems. Coral reef ecosystems are particularly complex, however, and assignment of trophic positions requires precise knowledge of mechanisms driving food webs and population dynamics. Competent analytical tools and empirical analysis are integral to defining ecosystem processes and avoiding misinterpretation of results. Here we examine the contribution of trophodynamics to informing ecological roles and understanding of coral reef ecology. Applied trophic studies of coral reefs were used to identify recent trends in methodology and analysis. Although research is increasing, clear definitions and scaling of studies is lacking. Trophodynamic studies will require more precise spatial and temporal data collection and analysis using multiple methods to fully explore the complex interactions within coral reef ecosystems.

Soundscapes from a Tropical Eastern Pacific reef and a Caribbean Sea reef

Science.gov (United States)

Staaterman, E.; Rice, A. N.; Mann, D. A.; Paris, C. B.

2013-06-01

Underwater soundscapes vary due to the abiotic and biological components of the habitat. We quantitatively characterized the acoustic environments of two coral reef habitats, one in the Tropical Eastern Pacific (Panama) and one in the Caribbean (Florida Keys), over 2-day recording durations in July 2011. We examined the frequency distribution, temporal variability, and biological patterns of sound production and found clear differences. The Pacific reef exhibited clear biological patterns and high temporal variability, such as the onset of snapping shrimp noise at night, as well as a 400-Hz daytime band likely produced by damselfish. In contrast, the Caribbean reef had high sound levels in the lowest frequencies, but lacked clear temporal patterns. We suggest that acoustic measures are an important element to include in reef monitoring programs, as the acoustic environment plays an important role in the ecology of reef organisms at multiple life-history stages.

Coral Reef Resilience, Tipping Points and the Strength of Herbivory.

Science.gov (United States)

Holbrook, Sally J; Schmitt, Russell J; Adam, Thomas C; Brooks, Andrew J

2016-11-02

Coral reefs increasingly are undergoing transitions from coral to macroalgal dominance. Although the functional roles of reef herbivores in controlling algae are becoming better understood, identifying possible tipping points in the herbivory-macroalgae relationships has remained a challenge. Assessment of where any coral reef ecosystem lies in relation to the coral-to-macroalgae tipping point is fundamental to understanding resilience properties, forecasting state shifts, and developing effective management practices. We conducted a multi-year field experiment in Moorea, French Polynesia to estimate these properties. While we found a sharp herbivory threshold where macroalgae escape control, ambient levels of herbivory by reef fishes were well above that needed to prevent proliferation of macroalgae. These findings are consistent with previously observed high resilience of the fore reef in Moorea. Our approach can identify vulnerable coral reef systems in urgent need of management action to both forestall shifts to macroalgae and preserve properties essential for resilience.

Wave-driven Hydrodynamics for Different Reef Geometries and Roughness Scenarios

Science.gov (United States)

Franklin, G. L.; Marino-Tapia, I.; Torres-Freyermuth, A.

2013-05-01

In fringing reef systems where a shallow lagoon is present behind the reef crest, wave breaking appears to dominate circulation, controlling numerous key processes such as the transport and dispersion of larvae, nutrients and sediments. Despite their importance, there is a need for more detailed knowledge on the hydrodynamic processes that take place within the surf zone of these systems and the effects different combinations of geometries and roughness have on them. The present study focuses on the use of two-dimensional (2DV) numerical model simulations and data obtained during a field campaign in Puerto Morelos, Quintana Roo, Mexico to better understand the detailed surf zone processes that occur over a fringing reef. The model used is Cornell Breaking Wave and Structures (COBRAS), which solves Reynolds-Averaged Navier-Stokes (RANS) equations. Reef geometries implemented in the model include a reef flat and two different reef crests. The effect of roughness on wave setup, radiation stress, mean flows, and cross-shore spectral evolution for the model results was studied using different roughness coefficients (Nikuradse) and a bathymetric profile obtained in the field using the bottom track option of an Acoustic Doppler Current Profiler. Field data were also analysed for the configuration and roughness of Puerto Morelos. Model results reveal that for all profiles wave setup increased significantly (~22%) with increasing bed roughness, in agreement with previous findings for sandy beaches.For all wave heights and periods studied, increasing roughness also affected spectral wave evolution across the reef, with a significant reduction in energy, particularly at infragravity frequencies. The presence of a reef crest in the profile resulted in differences in behaviour at infragravity frequencies. For example, preliminary results suggest that there is a shift towards higher frequencies as waves progress into the lagoon when a crest is present, something that does not

Using virtual reality to estimate aesthetic values of coral reefs

Science.gov (United States)

Clifford, Sam; Caley, M. Julian; Pearse, Alan R.; Brown, Ross; James, Allan; Christensen, Bryce; Bednarz, Tomasz; Anthony, Ken; González-Rivero, Manuel; Mengersen, Kerrie; Peterson, Erin E.

2018-01-01

Aesthetic value, or beauty, is important to the relationship between humans and natural environments and is, therefore, a fundamental socio-economic attribute of conservation alongside other ecosystem services. However, beauty is difficult to quantify and is not estimated well using traditional approaches to monitoring coral-reef aesthetics. To improve the estimation of ecosystem aesthetic values, we developed and implemented a novel framework used to quantify features of coral-reef aesthetics based on people's perceptions of beauty. Three observer groups with different experience to reef environments (Marine Scientist, Experienced Diver and Citizen) were virtually immersed in Australian's Great Barrier Reef (GBR) using 360° images. Perceptions of beauty and observations were used to assess the importance of eight potential attributes of reef-aesthetic value. Among these, heterogeneity, defined by structural complexity and colour diversity, was positively associated with coral-reef-aesthetic values. There were no group-level differences in the way the observer groups perceived reef aesthetics suggesting that past experiences with coral reefs do not necessarily influence the perception of beauty by the observer. The framework developed here provides a generic tool to help identify indicators of aesthetic value applicable to a wide variety of natural systems. The ability to estimate aesthetic values robustly adds an important dimension to the holistic conservation of the GBR, coral reefs worldwide and other natural ecosystems. PMID:29765676

Coral Reef Remote Sensing: Helping Managers Protect Reefs in a Changing Climate

Science.gov (United States)

Eakin, C.; Liu, G.; Li, J.; Muller-Karger, F. E.; Heron, S. F.; Gledhill, D. K.; Christensen, T.; Rauenzahn, J.; Morgan, J.; Parker, B. A.; Skirving, W. J.; Nim, C.; Burgess, T.; Strong, A. E.

2010-12-01

Climate change and ocean acidification are already having severe impacts on coral reef ecosystems. Warming oceans have caused corals to bleach, or expel their symbiotic algae (zooxanthellae) with alarming frequency and severity and have contributed to a rise in coral infectious diseases. Ocean acidification is reducing the availability of carbonate ions needed by corals and many other marine organisms to build structural components like skeletons and shells and may already be slowing the coral growth. These two impacts are already killing corals and slowing reef growth, reducing biodiversity and the structure needed to provide crucial ecosystem services. NOAA’s Coral Reef Watch (CRW) uses a combination of satellite data, in situ observations, and models to provide coral reef managers, scientists, and others with information needed to monitor threats to coral reefs. The advance notice provided by remote sensing and models allows resource managers to protect corals, coral reefs, and the services they provide, although managers often encounter barriers to implementation of adaptation strategies. This talk will focus on application of NOAA’s satellite and model-based tools that monitor the risk of mass coral bleaching on a global scale, ocean acidification in the Caribbean, and coral disease outbreaks in selected regions, as well as CRW work to train managers in their use, and barriers to taking action to adapt to climate change. As both anthropogenic CO2 and temperatures will continue to rise, local actions to protect reefs are becoming even more important.

The Impact of Marine Protected Areas on Reef-Wide Population Structure and Fishing-Induced Phenotypes in Coral-Reef Fishes

Science.gov (United States)

Fidler, Robert Young, III

Overfishing and destructive fishing practices threaten the sustainability of fisheries worldwide. In addition to reducing population sizes, anthropogenic fishing effort is highly size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-selective mortality induces widespread phenotypic shifts toward the predominance of smaller and earlier-maturing individuals. Fish that reach sexual maturity at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of exploited populations. These directional phenotypic alterations, collectively known as "fisheries-induced evolution" (FIE) are among the primary causes of the loss of harvestable fish biomass. Marine protected areas (MPAs) are one of the most widely utilized components of fisheries management programs around the world, and have been proposed as a potential mechanism by which the impacts of FIE may be mitigated. The ability of MPAs to buffer exploited populations against fishing pressure, however, remains debated due to inconsistent results across studies. Additionally, empirical evidence of phenotypic shifts in fishes within MPAs is lacking. This investigation addresses both of these issues by: (1) using a categorical meta-analysis of MPAs to standardize and quantify the magnitude of MPA impacts across studies; and (2) conducting a direct comparison of life-history phenotypes known to be influenced by FIE in six reef-fish species inside and outside of MPAs. The Philippines was used as a model system for analyses due to the country's significance in global marine biodiversity and reliance on MPAs as a fishery management tool. The quantitative impact of Philippine MPAs was assessed using a "reef-wide" meta-analysis. This analysis used pooled visual census data from 39 matched pairs of MPAs and fished reefs surveyed twice over a mean period of 3 years. In 17 of these MPAs, two additional surveys were conducted

Spatial distribution of epibenthic molluscs on a sandstone reef in the Northeast of Brazil

Directory of Open Access Journals (Sweden)

AS. Martinez

Full Text Available The present study investigated the distribution and abundance of epibenthic molluscs and their feeding habits associated to substrate features (coverage and rugosity in a sandstone reef system in the Northeast of Brazil. Rugosity, low coral cover and high coverage of zoanthids and fleshy alga were the variables that influenced a low richness and high abundance of a few molluscan species in the reef habitat. The most abundant species were generalist carnivores, probably associated to a lesser offer and variability of resources in this type of reef system, when compared to the coral reefs. The results found in this study could reflect a normal characteristic of the molluscan community distribution in sandstone reefs, with low coral cover, or could indicate a degradation state of this habitat if it is compared to coral reefs, once that the significantly high coverage of fleshy alga has been recognized as a negative indicator of reef ecosystems health.

Spatial distribution of epibenthic molluscs on a sandstone reef in the Northeast of Brazil.

Science.gov (United States)

Martinez, A S; Mendes, L F; Leite, T S

2012-05-01

The present study investigated the distribution and abundance of epibenthic molluscs and their feeding habits associated to substrate features (coverage and rugosity) in a sandstone reef system in the Northeast of Brazil. Rugosity, low coral cover and high coverage of zoanthids and fleshy alga were the variables that influenced a low richness and high abundance of a few molluscan species in the reef habitat. The most abundant species were generalist carnivores, probably associated to a lesser offer and variability of resources in this type of reef system, when compared to the coral reefs. The results found in this study could reflect a normal characteristic of the molluscan community distribution in sandstone reefs, with low coral cover, or could indicate a degradation state of this habitat if it is compared to coral reefs, once that the significantly high coverage of fleshy alga has been recognized as a negative indicator of reef ecosystems health.

Holocene coral patch reef ecology and sedimentary architecture, Northern Belize, Central America

Energy Technology Data Exchange (ETDEWEB)

Mazzullo, S.J.; Anderson-Underwood, K.E.; Burke, C.D.; Bischoff, W.D. (Wichita State Univ., KS (United States))

1992-12-01

Coral patch reefs are major components of Holocene platform carbonate facies systems in tropical and subtropical areas. The biotic composition, growth and relationship to sea level history, and diagenetic attributes of a representative Holocene patch reef ([open quotes]Elmer Reef[close quotes]) in the Mexico Rocks complex in northern Belize are described and compared to those of Holocene patch reefs in southern Belize. Elmer Reef has accumulated in shallow (2.5 m) water over the last 420 yr, under static sea level conditions. Rate of vertical construction is 0.3-0.5 m/100 yr, comparable to that of patch reefs in southern Belize. A pronounced coral zonation exists across Elmer Reef, with Monastrea annularis dominating on its crest and Acropora cervicornis occurring on its windward and leeward flanks. The dominance of Montastrea on Elmer Reef is unlike that of patch reefs in southern Belize, in which this coral assumes only a subordinate role in reef growth relative to that of Acropora palmata. Elmer Reef locally is extensively biodegraded and marine, fibrous aragonite and some bladed high-magnesium calcite cements occur throughout the reef section, partially occluding corallites and interparticle pores in associated sands. Patch reefs in southern Belize have developed as catch-up and keep-up reefs in a transgressive setting. In contrast, the dominant mode of growth of Elmer Reef, and perhaps other patch reefs in Mexico Rocks, appears to be one of lateral rather than vertical accretion. This style of growth occurs in a static sea level setting where there is only limited accommodation space because of the shallowness of the water, and such reefs are referred to as [open quotes]expansion reefs[close quotes]. 39 refs., 8 figs., 2 tabs.

Geochemical partitioning of lead in biogenic carbonate sediments in a coral reef depositional environment

International Nuclear Information System (INIS)

Horta-Puga, Guillermo

2017-01-01

The fate of trace elements in reef depositional environments has not been extensively investigated. The aim of this study was to determine the partitioning of Pb in sediments of the Veracruz Reef System, and its relation to local environmental sources. Lead was determined in four geochemical fractions: exchangeable (3.8 ± 0.4 μg g −1 ), carbonate (57.0 ± 13.6 μg g −1 ), organic matter (2.0 ± 0.9 μg g −1 ), and mineral (17.5 ± 5.4 μg g −1 ). For the mineral fraction, lead concentrations were higher in those reefs influenced by river discharge or by long-distance transport of terrigenous sediments. The bioavailable concentration of lead (range: 21.9–85.6 μg g −1 ) indicates that the Veracruz Reef System is a moderately polluted area. As expected, the carbonate fraction contained the highest proportion of Pb (70%), and because the reef framework is largely made up of by biogenic carbonate sediments, hence, it is therefore the most important repository of Pb in coral reef depositional environments. - Highlights: • Lead concentrations were determined in four geochemical fractions of reef sediments. • The carbonate fraction accounted for > 70% of the content of Pb in reef sediments. • Terrigenous sediments are the main source of Pb associated to the mineral fraction. • The Veracruz Reef System is considered a moderately polluted area. • Sediments are the main repositories of lead in coral reef depositional environments.

Understanding Reef Flat Sediment Regimes and Hydrodynamics can Inform Erosion Mitigation on Land

Directory of Open Access Journals (Sweden)

Lida Tenkova Teneva

2016-01-01

Full Text Available Coral reefs worldwide are affected by excessive sediment and nutrient delivery from adjacent watersheds. Land cover and land use changes contribute to reef ecosystem degradation, which in turn, diminish many ecosystem services, including coastal protection, recreation, and food provisioning. The objectives of this work were to understand the role of coastal oceanic and biophysical processes in mediating the effects of sedimentation in shallow reef environments, and to assess the efficacy of land-based sediment remediation in the coastal areas near Maunalei reef, Lāna’i Island, Hawai’i. To the best of our knowledge, this was the first study of sediment dynamics on an east-facing (i.e., facing the trade winds reef in the Hawaiian Islands. We developed ridge-to-reef monitoring systems at two paired stream bed-to-reef sites, where one of the reef sites was adjacent to a community stream sediment remediation project. We found that the two reef sites were characterized by different processes that affected the sediment removal rates; the two sites were also exposed to different amounts of sediment runoff. The community stream sediment remediation project appeared to keep at least 77 tonnes of sediment off the reef flat in one wet season. We found that resuspension of sediments on this reef was similar to that on north-facing and south-facing reefs that also are exposed to the trade winds. We posit that sites with slower sediment removal rates due to slower current velocities or high resuspension rates will require more-robust sediment capture systems on land to reduce sediment input rates and maximize potential for reef health recovery. This suggests that interventions such as local sediment remediation and watershed restoration may mitigate sediment delivery to coral reefs, but these interventions are more likely to be effective if they account for how adjacent coastal oceanographic processes distribute, accumulate, or advect sediment away from

In situ coral reef oxygen metabolism: an eddy correlation study.

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Matthew H Long

Full Text Available Quantitative studies of coral reefs are challenged by the three-dimensional hard structure of reefs and the high spatial variability and temporal dynamics of their metabolism. We used the non-invasive eddy correlation technique to examine respiration and photosynthesis rates, through O2 fluxes, from reef crests and reef slopes in the Florida Keys, USA. We assessed how the photosynthesis and respiration of different reef habitats is controlled by light and hydrodynamics. Numerous fluxes (over a 0.25 h period were as high as 4500 mmol O2 m(-2 d(-1, which can only be explained by efficient light utilization by the phototrophic community and the complex canopy structure of the reef, having a many-fold larger surface area than its horizontal projection. Over diel cycles, the reef crest was net autotrophic, whereas on the reef slope oxygen production and respiration were balanced. The autotrophic nature of the shallow reef crests implies that the export of organics is an important source of primary production for the larger area. Net oxygen production on the reef crest was proportional to the light intensity, up to 1750 µmol photons m(-2 s(-1 and decreased thereafter as respiration was stimulated by high current velocities coincident with peak light levels. Nighttime respiration rates were also stimulated by the current velocity, through enhanced ventilation of the porous framework of the reef. Respiration rates were the highest directly after sunset, and then decreased during the night suggesting that highly labile photosynthates produced during the day fueled early-night respiration. The reef framework was also important to the acquisition of nutrients as the ambient nitrogen stock in the water had sufficient capacity to support these high production rates across the entire reef width. These direct measurements of complex reefs systems yielded high metabolic rates and dynamics that can only be determined through in situ, high temporal resolution

Quantifying climatological ranges and anomalies for Pacific coral reef ecosystems.

Science.gov (United States)

Gove, Jamison M; Williams, Gareth J; McManus, Margaret A; Heron, Scott F; Sandin, Stuart A; Vetter, Oliver J; Foley, David G

2013-01-01

identify reef ecosystems most exposed to environmental stress as well as systems that may be more resistant or resilient to future climate change.

Quantifying Climatological Ranges and Anomalies for Pacific Coral Reef Ecosystems

Science.gov (United States)

Gove, Jamison M.; Williams, Gareth J.; McManus, Margaret A.; Heron, Scott F.; Sandin, Stuart A.; Vetter, Oliver J.; Foley, David G.

2013-01-01

help identify reef ecosystems most exposed to environmental stress as well as systems that may be more resistant or resilient to future climate change. PMID:23637939

Quantifying climatological ranges and anomalies for Pacific coral reef ecosystems.

Directory of Open Access Journals (Sweden)

Jamison M Gove

. These metrics will help identify reef ecosystems most exposed to environmental stress as well as systems that may be more resistant or resilient to future climate change.

Coal ash artificial reef demonstration

International Nuclear Information System (INIS)

Livingston, R.J.; Brendel, G.F.; Bruzek, D.A.

1991-01-01

This experimental project evaluated the use of coal ash to construct artificial reefs. An artificial reef consisting of approximately 33 tons of cement-stabilized coal ash blocks was constructed in approximately 20 feet of water in the Gulf of Mexico approximately 9.3 miles west of Cedar Key, Florida. The project objectives were: (1) demonstrate that a durable coal ash/cement block can be manufactured by commercial block-making machines for use in artificial reefs, and (2) evaluate the possibility that a physically stable and environmentally acceptable coal ash/cement block reef can be constructed as a means of expanding recreational and commercial fisheries. The reef was constructed in February 1988 and biological surveys were made at monthly intervals from May 1988 to April 1989. The project provided information regarding: Development of an optimum design mix, block production and reef construction, chemical composition of block leachate, biological colonization of the reef, potential concentration of metals in the food web associated with the reef, acute bioassays (96-hour LC 50 ). The Cedar Key reef was found to be a habitat that was associated with a relatively rich assemblage of plants and animals. The reef did not appear to be a major source of heavy metals to species at various levels of biological organization. GAI Consultants, Inc (GAI) of Monroeville, Pennsylvania was the prime consultant for the project. The biological monitoring surveys and evaluations were performed by Environmental Planning and Analysis, Inc. of Tallahassee, Florida. The chemical analyses of biological organisms and bioassay elutriates were performed by Savannah Laboratories of Tallahassee, Florida. Florida Power Corporation of St. Petersburg, Florida sponsored the project and supplied ash from their Crystal River Energy Complex

Whole gut microbiome composition of damselfish and cardinalfish before and after reef settlement

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Darren J. Parris

2016-08-01

Full Text Available The Pomacentridae (damselfish and Apogonidae (cardinalfish are among the most common fish families on coral reefs and in the aquarium trade. Members of both families undergo a pelagic larvae phase prior to settlement on the reef, where adults play key roles in benthic habitat structuring and trophic interactions. Fish-associated microbial communities (microbiomes significantly influence fish health and ecology, yet little is known of how microbiomes change with life stage. We quantified the taxonomic (16S rRNA gene composition of whole gut microbiomes from ten species of damselfish and two species of cardinalfish from Lizard Island, Australia, focusing specifically on comparisons between pelagic larvae prior to settlement on the reef versus post-settlement juvenile and adult individuals. On average, microbiome phylogenetic diversity increased from pre- to post-settlement, and was unrelated to the microbial composition in the surrounding water column. However, this trend varied among species, suggesting stochasticity in fish microbiome assembly. Pre-settlement fish were enriched with bacteria of the Endozoicomonaceae, Shewanellaceae, and Fusobacteriaceae, whereas settled fish harbored higher abundances of Vibrionaceae and Pasteurellaceae. Several individual operational taxonomic units, including ones related to Vibrio harveyi, Shewanella sp., and uncultured Endozoicomonas bacteria, were shared between both pre and post-settlement stages and may be of central importance in the intestinal niche across development. Richness of the core microbiome shared among pre-settlement fish was comparable to that of settled individuals, suggesting that changes in diversity with adulthood are due to the acquisition or loss of host-specific microbes. These results identify a key transition in microbiome structure across host life stage, suggesting changes in the functional contribution of microbiomes over development in two ecologically dominant reef fish

Mesopredator trophodynamics on thermally stressed coral reefs

Science.gov (United States)

Hempson, Tessa N.; Graham, Nicholas A. J.; MacNeil, M. Aaron; Hoey, Andrew S.; Almany, Glenn R.

2018-03-01

Ecosystems are becoming vastly modified through disturbance. In coral reef ecosystems, the differential susceptibility of coral taxa to climate-driven bleaching is predicted to shift coral assemblages towards reefs with an increased relative abundance of taxa with high thermal tolerance. Many thermally tolerant coral species are characterised by low structural complexity, with reduced habitat niche space for the small-bodied coral reef fishes on which piscivorous mesopredators feed. This study used a patch reef array to investigate the potential impacts of climate-driven shifts in coral assemblages on the trophodynamics of reef mesopredators and their prey communities. The `tolerant' reef treatment consisted only of coral taxa of low susceptibility to bleaching, while `vulnerable' reefs included species of moderate to high thermal vulnerability. `Vulnerable' reefs had higher structural complexity, and the fish assemblages that established on these reefs over 18 months had higher species diversity, abundance and biomass than those on `tolerant' reefs. Fish assemblages on `tolerant' reefs were also more strongly influenced by the introduction of a mesopredator ( Cephalopholis boenak). Mesopredators on `tolerant' reefs had lower lipid content in their muscle tissue by the end of the 6-week experiment. Such sublethal energetic costs can compromise growth, fecundity, and survivorship, resulting in unexpected population declines in long-lived mesopredators. This study provides valuable insight into the altered trophodynamics of future coral reef ecosystems, highlighting the potentially increased vulnerability of reef fish assemblages to predation as reef structure declines, and the cost of changing prey availability on mesopredator condition.

Predicting Heat Stress to Inform Reef Management: NOAA Coral Reef Watch's 4-Month Coral Bleaching Outlook

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Gang Liu

2018-03-01

Full Text Available The U.S. National Oceanic and Atmospheric Administration's (NOAA Coral Reef Watch (CRW operates a global 4-Month Coral Bleaching Outlook system for shallow-water coral reefs in collaboration with NOAA's National Centers for Environmental Prediction (NCEP. The Outlooks are generated by applying the algorithm used in CRW's operational satellite coral bleaching heat stress monitoring, with slight modifications, to the sea surface temperature (SST predictions from NCEP's operational Climate Forecast System Version 2 (CFSv2. Once a week, the probability of heat stress capable of causing mass coral bleaching is predicted for 4-months in advance. Each day, CFSv2 generates an ensemble of 16 forecasts, with nine runs out to 45-days, three runs out to 3-months, and four runs out to 9-months. This results in 28–112 ensemble members produced each week. A composite for each predicted week is derived from daily predictions within each ensemble member. The probability of each of four heat stress ranges (Watch and higher, Warning and higher, Alert Level 1 and higher, and Alert Level 2 is determined from all the available ensemble members for the week to form the weekly probabilistic Outlook. The probabilistic 4-Month Outlook is the highest weekly probability predicted among all the weekly Outlooks during a 4-month period for each of the stress ranges. An initial qualitative skill analysis of the Outlooks for 2011–2015, compared with CRW's satellite-based coral bleaching heat stress products, indicated the Outlook has performed well with high hit rates and low miss rates for most coral reef areas. Regions identified with high false alarm rates will guide future improvements. This Outlook system, as the first and only freely available global coral bleaching prediction system, has been providing critical early warning to marine resource managers, scientists, and decision makers around the world to guide management, protection, and monitoring of coral reefs

Notes on common macrobenthic reef invertebrates of Tubbataha Reefs Natural Park, Philippines

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Jean Beth S. Jontila

2012-12-01

Full Text Available Macrobenthic reef invertebrates are important reef health indicators and fishery resources but are not very well documented in Tubbataha Reefs Natural Park. To provide notes on the species composition and the abundance and size of commonly encountered macrobenthic reef invertebrates, belt transects survey in intertidal, shallow, and deep subtidal reef habitats were conducted. In total, 18 species were recorded, six of which were echinoderms and 12 were mollusks, which include the rare giant clam Hippopusporcellanus. Only the giant clam Tridacna crocea and the top shell Trochus niloticus occurred in all seven permanent monitoring sites but the two species varied in densities across depths. There was also an outbreak of crown-of-thorns (COTs sea stars in some sites. The large variation in the density of each species across sites and depths suggests niche differences, overharvesting, or their recovery fromhaving been overly exploited. Separate monitoring areas for each commercially important species are suggested to determine how their populations respond to poaching and their implications on the park’s long term management.

Diel coral reef acidification driven by porewater advection in permeable sands, Heron Island, Great Barrier Reef

DEFF Research Database (Denmark)

Santos, Isaac R.; Glud, Ronnie N.; Maher, Damien

2011-01-01

Little is known about how biogeochemical processes in permeable sediments affect the pH of coastal waters. We demonstrate that seawater recirculation in permeable sands can play a major role in proton (H+) cycling in a coral reef lagoon. The diel pH range (up to 0.75 units) in the Heron Island...... lagoon was the broadest ever reported for reef waters, and the night‐time pH (7.69) was comparable to worst‐case scenario predictions for seawater pH in 2100. The net contribution of coarse carbonate sands to the whole system H+ fluxes was only 9% during the day, but approached 100% at night when small...... scale (i.e., flow and topography‐induced pressure gradients) and large scale (i.e., tidal pumping as traced by radon) seawater recirculation processes were synergistic. Reef lagoon sands were a net sink for H+, and the sink strength was a function of porewater flushing rate. Our observations suggest...

Reef Sharks Exhibit Site-Fidelity and Higher Relative Abundance in Marine Reserves on the Mesoamerican Barrier Reef

Science.gov (United States)

Bond, Mark E.; Babcock, Elizabeth A.; Pikitch, Ellen K.; Abercrombie, Debra L.; Lamb, Norlan F.; Chapman, Demian D.

2012-01-01

Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ecosystems and have declined in many regions due to intense fishing pressure. There is some support for the hypothesis that carcharhinid species that complete their life-cycle within coral reef ecosystems, hereafter referred to as “reef sharks”, are more abundant inside no-take marine reserves due to a reduction in fishing pressure (i.e., they benefit from marine reserves). Key predictions of this hypothesis are that (a) individual reef sharks exhibit high site-fidelity to these protected areas and (b) their relative abundance will generally be higher in these areas compared to fished reefs. To test this hypothesis for the first time in Caribbean coral reef ecosystems we combined acoustic monitoring and baited remote underwater video (BRUV) surveys to measure reef shark site-fidelity and relative abundance, respectively. We focused on the Caribbean reef shark (Carcharhinus perezi), the most common reef shark in the Western Atlantic, at Glover's Reef Marine Reserve (GRMR), Belize. Acoustically tagged sharks (N = 34) were detected throughout the year at this location and exhibited strong site-fidelity. Shark presence or absence on 200 BRUVs deployed at GRMR and three other sites (another reserve site and two fished reefs) showed that the factor “marine reserve” had a significant positive effect on reef shark presence. We rejected environmental factors or site-environment interactions as predominant drivers of this pattern. These results are consistent with the hypothesis that marine reserves can benefit reef shark populations and we suggest new hypotheses to determine the underlying mechanism(s) involved: reduced fishing mortality or enhanced prey availability. PMID:22412965

Diving down the reefs? Intensive diving tourism threatens the reefs of the northern Red Sea

DEFF Research Database (Denmark)

Hasler-Sheetal, Harald; Ott, Jörg A.

2008-01-01

Intensive recreational SCUBA diving threatens coral reef ecosystems. The reefs at Dahab, South Sinai, Egypt, are among the world’s most dived (>30,000dives y−1). We compared frequently dived sites to sites with no or little diving. Benthic communities and condition of corals were examined...... to intensive SCUBA diving showed a significantly higher number of broken and damaged corals and significantly lower coral cover. Reef crest coral communities were significantly more affected than those of the reef slope: 95% of the broken colonies were branching ones. No effect of diving on the abundance...... by the point intercept sampling method in the reef crest zone (3 m) and reef slope zone (12 m). Additionally, the abundance of corallivorous and herbivorous fish was estimated based on the visual census method. Sediments traps recorded the sedimentation rates caused by SCUBA divers. Zones subject...

Artificial Reefs in Motion: Legacy of changes and degradation at the Redbird Reef Site

Science.gov (United States)

Trembanis, A. C.; DuVal, C.; Peter, B.

2016-12-01

Artificial reefs are used for a variety of purposes at sites throughout the U.S. and around the globe, yet little, if any, long-term monitoring has been conducted with the goal of understanding inter-annual changes to the emplaced structures. Throughout the U.S. Mid-Atlantic region, several programs utilized retired subway cars as disposal structures to form artificial reefs. One such site, known as site 11, or "Redbird Reef", is located off the coast of Delaware and was at one time home to 997 former NYC subway cars. Opportunistic sonar surveys at the site have been conducted between 2008 and 2016 providing one of the most extensive and repeated mapping studies for this type of reef. Previous studies conducted by our group at the site have focused on understanding wave orbital ripple dynamics and scour patterns. In this present study, we analyze the changes apparent at the site itself, focused on the storm-response dynamics of the subway cars. Results have shown that Superstorm Sandy in 2012 produced dramatic changes to the reef structures resulting in the total or partial destruction of eight subway cars within a small (.45 x .2km) portion of the reef site. Winter Storm Jonas in 2016 resulted in the destruction of fewer cars, but rotated a previously static 47m long Navy barge nearly 60 degrees. Once destroyed or collapsed by waves the subway cars go from providing positive structural relief and thus beneficial habitat above the surrounding seabed to being reduced to scattered low relief marine debris. A once popular consideration for reef material, the event and inter-annual decay of subway cars as observed at the Redbird reef provides both a stark indication of the power of storm dynamics on the inner-shelf and a cautionary tale with regards to the selection of seabed reef material.

DIVERSITY OF REEF FISH FUNGSIONAL GROUPS IN TERMS OF CORAL REEF RESILIENCES

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Isa Nagib edrus

2017-01-01

Full Text Available Infrastructure development in the particular sites of  Seribu Islands as well as those in main land of Jakarta City increased with coastal population this phenomenon is likely to increase the effects to the adjacent coral waters of Seribu Islands.  Chemical pollutants, sedimentation, and domestic wastes are the common impact and threatening, the survival of coral reef ecosystem. Coral reef resiliences naturaly remained on their processes under many influences of supporting factors. One of the major factor is the role of reef fish functional groups on controling algae growth to recolonize coral juveniles. The  aim of this study to obtain data of a herbivory and other fish functional groups of reef fishes in the Pari Islands that are resilience indicators, or that may indicate the effectiveness of management actions. A conventional scientific approach on fish diversity and abundance data gathering was conducted by the underwater visual cencus. Diversity values of the reef fish functional groups, such as the abundance of individual fish including species, were collected and tabulated by classes and weighted as a baseline to understand the resilience of coral reed based on Obura and Grimsditch (2009 techniques. The results succesfully identified several fish functional groups such as harbivores (21 species, carnivores (13 species and fish indicator (5 species occurred in the area. Regarding the aspects of fish density and its diversity, especially herbivorous fish functional group, were presumably in the state of rarely available to support the coral reef resiliences. Resilience indices ranged from 1 (low level to 3 (moderate level and averages of the quality levels ranged from 227 to 674. These levels were inadequate to support coral reef recolonization.

Climatic and tectonic controls on late Quaternary reef growth in New Caledonia

International Nuclear Information System (INIS)

Cabioch, G.; Recy, J.; Jouannic, CH.; Turpin, L.

1996-01-01

Sedimentological and stratigraphic analysis of about 40 sub-surface cores drilled through the reefs of New Caledonia provides valuable data on the processes of reef recolonization following the past post glacial sea-level rise, and on the vertical tectonic behaviour of the island over the past 125,000 years. Holocene reefs in New Caledonia are not older than 8.5 ky. The fringing reef which developed during the last interglacial high sea-level 125 ky ago, is today uplifted and lies along some 30 km of coast in the area of 10 m, while the present-day barrier reef is deeply submerged (around - 15 to - 20 m). Near Hienghene (east coast), a double system of two notches is markedly deformed by a bulge, but is much more localized (3 km long) than in the Yate area, with a maximum uplift of 13 m of the upper double notch system (interpreted as having formed during the last interglacial event). Relics of the 125 ky fringing reef are emergent at various locations in the Bourail region (west coast). However, their altitudes are lower than that generally admitted (+ 6 m) for their construction at 125 ky, thus most probably reflecting a slight subsidence of the area. Elsewhere, the 125 ky fringing reef underlies the Holocene reef: in the SW of the island, in particular, the Holocene - Pleistocene unconformity is observed at - 6 m. In areas of higher subsidence rates, such as the NW or NE of the island, the 125 ky fringing reef may be more deeply buried. In that case, the Holocene reef rests directly on a metamorphic or sedimentary substratum. Within the barrier reef build-up itself, the 125 ky reef flat is overlain by a Holocene sequence, whose thickness depends on local subsidence rates. The observation of notches, raised becah-rocks or coral reefs (dated ar around 5,500 yr) uplifted up to 1 to 1,5 m above MLWS reflects the existence of a hydro-isostatic rebound. Traces of this rebound disappear in areas of high subsidence rate, illustrating the action of local tectonics

Oceanic forcing of coral reefs.

Science.gov (United States)

Lowe, Ryan J; Falter, James L

2015-01-01

Although the oceans play a fundamental role in shaping the distribution and function of coral reefs worldwide, a modern understanding of the complex interactions between ocean and reef processes is still only emerging. These dynamics are especially challenging owing to both the broad range of spatial scales (less than a meter to hundreds of kilometers) and the complex physical and biological feedbacks involved. Here, we review recent advances in our understanding of these processes, ranging from the small-scale mechanics of flow around coral communities and their influence on nutrient exchange to larger, reef-scale patterns of wave- and tide-driven circulation and their effects on reef water quality and perceived rates of metabolism. We also examine regional-scale drivers of reefs such as coastal upwelling, internal waves, and extreme disturbances such as cyclones. Our goal is to show how a wide range of ocean-driven processes ultimately shape the growth and metabolism of coral reefs.

40 CFR 230.44 - Coral reefs.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Coral reefs. 230.44 Section 230.44... Aquatic Sites § 230.44 Coral reefs. (a) Coral reefs consist of the skeletal deposit, usually of calcareous... organisms present in growing portions of the reef. (b) Possible loss of values: The discharge of dredged or...

Cumulative Human Impacts on Coral Reefs: Assessing Risk and Management Implications for Brazilian Coral Reefs

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Rafael A. Magris

2018-04-01

Full Text Available Effective management of coral reefs requires strategies tailored to cope with cumulative disturbances from human activities. In Brazil, where coral reefs are a priority for conservation, intensifying threats from local and global stressors are of paramount concern to management agencies. Using a cumulative impact assessment approach, our goal was to inform management actions for coral reefs in Brazil by assessing their exposure to multiple stressors (fishing, land-based activities, coastal development, mining, aquaculture, shipping, and global warming. We calculated an index of the risk to cumulative impacts: (i assuming uniform sensitivity of coral reefs to stressors; and (ii using impact weights to reflect varying tolerance levels of coral reefs to each stressor. We also predicted the index in both the presence and absence of global warming. We found that 16% and 37% of coral reefs had high to very high risk of cumulative impacts, without and with information on sensitivity respectively, and 42% of reefs had low risk to cumulative impacts from both local and global stressors. Our outputs are the first comprehensive spatial dataset of cumulative impact on coral reefs in Brazil, and show that areas requiring attention mostly corresponded to those closer to population centres. We demonstrate how the relationships between risks from local and global stressors can be used to derive strategic management actions.

Conservation and management applications of the REEF volunteer fish monitoring program.

Science.gov (United States)

Pattengill-Semmens, Christy V; Semmens, Brice X

2003-01-01

The REEF Fish Survey Project is a volunteer fish monitoring program developed by the Reef Environmental Education Foundation (REEF). REEF volunteers collect fish distribution and abundance data using a standardized visual method during regular diving and snorkeling activities. Survey data are recorded on preprinted data sheets that are returned to REEF and optically digitized. Data are housed in a publicly accessible database on REEF's Web site (http://www.reef.org). Since the project's inception in 1993, over 40,000 surveys have been conducted in the coastal waters of North America, tropical western Atlantic, Gulf of California and Hawaii. The Fish Survey Project has been incorporated into existing monitoring programs through partnerships with government agencies, scientists, conservation organizations, and private institutions. REEF's partners benefit from the educational value and increased stewardship resulting from volunteer data collection. Applications of the data include an evaluation of fish/habitat interactions in the Florida Keys National Marine Sanctuary, the development of a multi-species trend analysis method to identify sites of management concern, assessment of the current distribution of species, status reports on fish assemblages of marine parks, and the evaluation of no-take zones in the Florida Keys. REEF's collaboration with a variety of partners, combined with the Fish Survey Project's standardized census method and database management system, has resulted in a successful citizen science monitoring program.

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

Science.gov (United States)

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.

Correlation Between Existence of Reef Sharks with Abundance of Reef Fishes in South Waters of Morotai Island (North Moluccas)

Science.gov (United States)

Mukharror, Darmawan Ahmad; Tiara Baiti, Isnaini; Ichsan, Muhammad; Pridina, Niomi; Triutami, Sanny

2017-10-01

Despite increasing academic research citation on biology, abundance, and the behavior of the blacktip reef sharks, the influence of reef fish population on the density of reef sharks: Carcharhinus melanopterus and Triaenodon obesus population in its habitat were largely unassessed. This present study examined the correlation between abundance of reef fishes family/species with the population of reef sharks in Southern Waters of Morotai Island. The existence of reef sharks was measured with the Audible Stationary Count (ASC) methods and the abundance of reef fishes was surveyed using Underwater Visual Census (UVC) combined with Diver Operated Video (DOV) census. The coefficient of Determination (R2) was used to investigate the degree of relationships between sharks and the specific reef fishes species. The research from 8th April to 4th June 2015 showed the strong positive correlations between the existence of reef sharks with abundance of reef fishes. The correlation values between Carcharhinus melanopterus/Triaenodon obesus with Chaetodon auriga was 0.9405, blacktip/whitetip reef sharks versus Ctenochaetus striatus was 0.9146, and Carcharhinus melanopterus/Triaenodon obesus to Chaetodon kleinii was 0.8440. As the shark can be worth more alive for shark diving tourism than dead in a fish market, the abundance of these reef fishes was important as an early indication parameter of shark existence in South Water of Morotai Island. In the long term, this highlights the importance of reef fishes abundance management in Morotai Island’s Waters to enable the establishment of appropriate and effective reef sharks conservation.

Assessing coral reefs on a Pacific-wide scale using the microbialization score.

Directory of Open Access Journals (Sweden)

Tracey McDole

Full Text Available The majority of the world's coral reefs are in various stages of decline. While a suite of disturbances (overfishing, eutrophication, and global climate change have been identified, the mechanism(s of reef system decline remain elusive. Increased microbial and viral loading with higher percentages of opportunistic and specific microbial pathogens have been identified as potentially unifying features of coral reefs in decline. Due to their relative size and high per cell activity, a small change in microbial biomass may signal a large reallocation of available energy in an ecosystem; that is the microbialization of the coral reef. Our hypothesis was that human activities alter the energy budget of the reef system, specifically by altering the allocation of metabolic energy between microbes and macrobes. To determine if this is occurring on a regional scale, we calculated the basal metabolic rates for the fish and microbial communities at 99 sites on twenty-nine coral islands throughout the Pacific Ocean using previously established scaling relationships. From these metabolic rate predictions, we derived a new metric for assessing and comparing reef health called the microbialization score. The microbialization score represents the percentage of the combined fish and microbial predicted metabolic rate that is microbial. Our results demonstrate a strong positive correlation between reef microbialization scores and human impact. In contrast, microbialization scores did not significantly correlate with ocean net primary production, local chla concentrations, or the combined metabolic rate of the fish and microbial communities. These findings support the hypothesis that human activities are shifting energy to the microbes, at the expense of the macrobes. Regardless of oceanographic context, the microbialization score is a powerful metric for assessing the level of human impact a reef system is experiencing.

Assessing coral reefs on a Pacific-wide scale using the microbialization score.

Science.gov (United States)

McDole, Tracey; Nulton, James; Barott, Katie L; Felts, Ben; Hand, Carol; Hatay, Mark; Lee, Hochul; Nadon, Marc O; Nosrat, Bahador; Salamon, Peter; Bailey, Barbara; Sandin, Stuart A; Vargas-Angel, Bernardo; Youle, Merry; Zgliczynski, Brian J; Brainard, Russell E; Rohwer, Forest

2012-01-01

The majority of the world's coral reefs are in various stages of decline. While a suite of disturbances (overfishing, eutrophication, and global climate change) have been identified, the mechanism(s) of reef system decline remain elusive. Increased microbial and viral loading with higher percentages of opportunistic and specific microbial pathogens have been identified as potentially unifying features of coral reefs in decline. Due to their relative size and high per cell activity, a small change in microbial biomass may signal a large reallocation of available energy in an ecosystem; that is the microbialization of the coral reef. Our hypothesis was that human activities alter the energy budget of the reef system, specifically by altering the allocation of metabolic energy between microbes and macrobes. To determine if this is occurring on a regional scale, we calculated the basal metabolic rates for the fish and microbial communities at 99 sites on twenty-nine coral islands throughout the Pacific Ocean using previously established scaling relationships. From these metabolic rate predictions, we derived a new metric for assessing and comparing reef health called the microbialization score. The microbialization score represents the percentage of the combined fish and microbial predicted metabolic rate that is microbial. Our results demonstrate a strong positive correlation between reef microbialization scores and human impact. In contrast, microbialization scores did not significantly correlate with ocean net primary production, local chla concentrations, or the combined metabolic rate of the fish and microbial communities. These findings support the hypothesis that human activities are shifting energy to the microbes, at the expense of the macrobes. Regardless of oceanographic context, the microbialization score is a powerful metric for assessing the level of human impact a reef system is experiencing.

Coral reefs - sources or sinks of atmospheric CO[sub 2

Energy Technology Data Exchange (ETDEWEB)

Ware, J R; Smith, S V; Reakakudla, M L [Hawaii University, Honolulu, HI (USA). Dept. of Oceanography

1992-09-01

Because the precipitation of calcium carbonate results in the sequestering of carbon, it frequently has been thought that coral reefs function as sinks of global atmospheric CO[sub 2]. However, the precipitation of calcium carbonate is accompanied by a shift of pH that results in the release of CO[sub 2]. This release of CO[sub 2] is less in buffered sea water than fresh water systems; nevertheless, coral reefs are sources, not sinks, of atmospheric carbon. Using estimated rates of coral reef carbonate production, we compute that coral reefs release 0.02 to 0.08 Gt C as CO[sub 2] annually. This is approximately 0.4% to 1.4% of the current anthropogenic CO[sub 2] production due to fossil fuel combustion.

Is proximity to land-based sources of coral stressors an appropriate measure of risk to coral reefs? An example from the Florida Reef Tract.

Science.gov (United States)

Lirman, Diego; Fong, Peggy

2007-06-01

Localized declines in coral condition are commonly linked to land-based sources of stressors that influence gradients of water quality, and the distance to sources of stressors is commonly used as a proxy for predicting the vulnerability and future status of reef resources. In this study, we evaluated explicitly whether proximity to shore and connections to coastal bays, two measures of potential land-based sources of disturbance, influence coral community and population structure, and the abundance, distribution, and condition of corals within patch reefs of the Florida Reef Tract. In the Florida Keys, long-term monitoring has documented significant differences in water quality along a cross-shelf gradient. Inshore habitats exhibit higher levels of nutrients (DIN and TP), TOC, turbidity, and light attenuation, and these levels decrease with increasing distance from shore and connections to tidal bays. In clear contrast to these patterns of water quality, corals on inshore patch reefs exhibited significantly higher coral cover, higher growth rates, and lower partial mortality rates than those documented in similar offshore habitats. Coral recruitment rates did not differ between inshore and offshore habitats. Corals on patch reefs closest to shore had well-spread population structures numerically dominated by intermediate to large colonies, while offshore populations showed narrower size-distributions that become increasingly positively skewed. Differences in size-structure of coral populations were attributed to faster growth and lower rates of partial mortality at inshore habitats. While the underlying causes for the favorable condition of inshore coral communities are not yet known, we hypothesize that the ability of corals to shift their trophic mode under adverse environmental conditions may be partly responsible for the observed patterns, as shown in other reef systems. This study, based on data collected from a uniform reef habitat type and coral species

Global warming transforms coral reef assemblages.

Science.gov (United States)

Hughes, Terry P; Kerry, James T; Baird, Andrew H; Connolly, Sean R; Dietzel, Andreas; Eakin, C Mark; Heron, Scott F; Hoey, Andrew S; Hoogenboom, Mia O; Liu, Gang; McWilliam, Michael J; Pears, Rachel J; Pratchett, Morgan S; Skirving, William J; Stella, Jessica S; Torda, Gergely

2018-04-01

Global warming is rapidly emerging as a universal threat to ecological integrity and function, highlighting the urgent need for a better understanding of the impact of heat exposure on the resilience of ecosystems and the people who depend on them 1 . Here we show that in the aftermath of the record-breaking marine heatwave on the Great Barrier Reef in 2016 2 , corals began to die immediately on reefs where the accumulated heat exposure exceeded a critical threshold of degree heating weeks, which was 3-4 °C-weeks. After eight months, an exposure of 6 °C-weeks or more drove an unprecedented, regional-scale shift in the composition of coral assemblages, reflecting markedly divergent responses to heat stress by different taxa. Fast-growing staghorn and tabular corals suffered a catastrophic die-off, transforming the three-dimensionality and ecological functioning of 29% of the 3,863 reefs comprising the world's largest coral reef system. Our study bridges the gap between the theory and practice of assessing the risk of ecosystem collapse, under the emerging framework for the International Union for Conservation of Nature (IUCN) Red List of Ecosystems 3 , by rigorously defining both the initial and collapsed states, identifying the major driver of change, and establishing quantitative collapse thresholds. The increasing prevalence of post-bleaching mass mortality of corals represents a radical shift in the disturbance regimes of tropical reefs, both adding to and far exceeding the influence of recurrent cyclones and other local pulse events, presenting a fundamental challenge to the long-term future of these iconic ecosystems.

Global microbialization of coral reefs.

Science.gov (United States)

Haas, Andreas F; Fairoz, Mohamed F M; Kelly, Linda W; Nelson, Craig E; Dinsdale, Elizabeth A; Edwards, Robert A; Giles, Steve; Hatay, Mark; Hisakawa, Nao; Knowles, Ben; Lim, Yan Wei; Maughan, Heather; Pantos, Olga; Roach, Ty N F; Sanchez, Savannah E; Silveira, Cynthia B; Sandin, Stuart; Smith, Jennifer E; Rohwer, Forest

2016-04-25

Microbialization refers to the observed shift in ecosystem trophic structure towards higher microbial biomass and energy use. On coral reefs, the proximal causes of microbialization are overfishing and eutrophication, both of which facilitate enhanced growth of fleshy algae, conferring a competitive advantage over calcifying corals and coralline algae. The proposed mechanism for this competitive advantage is the DDAM positive feedback loop (dissolved organic carbon (DOC), disease, algae, microorganism), where DOC released by ungrazed fleshy algae supports copiotrophic, potentially pathogenic bacterial communities, ultimately harming corals and maintaining algal competitive dominance. Using an unprecedented data set of >400 samples from 60 coral reef sites, we show that the central DDAM predictions are consistent across three ocean basins. Reef algal cover is positively correlated with lower concentrations of DOC and higher microbial abundances. On turf and fleshy macroalgal-rich reefs, higher relative abundances of copiotrophic microbial taxa were identified. These microbial communities shift their metabolic potential for carbohydrate degradation from the more energy efficient Embden-Meyerhof-Parnas pathway on coral-dominated reefs to the less efficient Entner-Doudoroff and pentose phosphate pathways on algal-dominated reefs. This 'yield-to-power' switch by microorganism directly threatens reefs via increased hypoxia and greater CO2 release from the microbial respiration of DOC.

Novel tradable instruments in the conservation of coral reefs, based on the coral gardening concept for reef restoration.

Science.gov (United States)

Rinkevich, Baruch

2015-10-01

Nearly all coral reefs bordering nations have experienced net losses in reef biodiversity, goods and services, even without considering the ever-developing global change impacts. In response, this overview wishes to reveal through prospects of active reef-restoration, the currently non-marketed or poorly marketed reef services, focusing on a single coral species (Stylophora pistillata). It is implied that the integration of equity capitals and other commodification with reef-restoration practices will improve total reef services. Two tiers of market-related activities are defined, the traditional first-tier instruments (valuating costs/gains for extracting tradable goods and services) and novel second-tier instruments (new/expanded monetary tools developed as by-products of reef restoration measures). The emerging new suite of economic mechanisms based on restoration methodologies could be served as an incentive for ecosystem conservation, enhancing the sum values of all services generated by coral reefs, where the same stocks of farmed/transplanted coral colonies will be used as market instruments. I found that active restoration measures disclose 12 classes of second-tier goods and services, which may partly/wholly finance restoration acts, bringing to light reef capitalizations that allow the expansion of markets with products that have not been considered before. The degree to which the second tier of market-related services could buffer coral-reef degradation is still unclear and would vary with different reef types and in various reef restoration scenarios; however, reducing the uncertainty associated with restoration. It is expected that the expansion of markets with the new products and the enhancement of those already existing will be materialized even if reef ecosystems will recover into different statuses. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatial variability of sediment transport processes over intra‐ and subtidal timescales within a fringing coral reef system

Science.gov (United States)

Pomeroy, Andrew; Lowe, Ryan J.; Ghisalberti, Marco; Winter, Gundula; Storlazzi, Curt D.; Cuttler, Michael V. W.

2018-01-01

Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of incident waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that incident waves are the key driver of the SSC variability spatially (reef flat, lagoon, and channels) but cannot not fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intra‐tidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) time scales, which is related to the arrival of large incident waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross‐reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave‐driven flows, but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intra‐tidal) current variability also occur due to both tidal flows, as well as variations in the water depth that influence wave transmission across the reef and wave‐driven currents.

Macroalgae in the coral reefs of Eilat (Gulf of Aqaba, Red Sea) as a possible indicator of reef degradation

International Nuclear Information System (INIS)

Bahartan, Karnit; Zibdah, Mohammad; Ahmed, Yousef; Israel, Alvaro; Brickner, Itzchak; Abelson, Avigdor

2010-01-01

The current state of health of the coral reefs in the northern Gulf of Aqaba (Red Sea), notably the Eilat reefs, is under debate regarding both their exact condition and the causes of degradation. A dearth of earlier data and unequivocal reliable indices are the major problems hinder a clear understanding of the reef state. Our research objective was to examine coral-algal dynamics as a potential cause and an indication of reef degradation. The community structure of stony corals and algae along the northern Gulf of Aqaba reveal non-seasonal turf algae dominancy in the shallow Eilat reefs (up to 72%), while the proximate Aqaba reefs present negligible turf cover (<6%). We believe that turf dominancy can indicate degradation in these reefs, based on the reduction in essential reef components followed by proliferation of perennial turf algae. Our findings provide further evidence for the severe state of the Eilat coral reefs.

A method for risk analysis across governance systems: a Great Barrier Reef case study

International Nuclear Information System (INIS)

Dale, Allan; Vella, Karen; Potts, Ruth; Pressey, Robert L; Brodie, Jon; Yorkston, Hugh

2013-01-01

Healthy governance systems are key to delivering sound environmental management outcomes from global to local scales. There are, however, surprisingly few risk assessment methods that can pinpoint those domains and sub-domains within governance systems that are most likely to influence good environmental outcomes at any particular scale, or those if absent or dysfunctional, most likely to prevent effective environmental management. This paper proposes a new risk assessment method for analysing governance systems. This method is then tested through its preliminary application to a significant real-world context: governance as it relates to the health of Australia’s Great Barrier Reef (GBR). The GBR exists at a supra-regional scale along most of the north eastern coast of Australia. Brodie et al (2012 Mar. Pollut. Bull. 65 81–100) have recently reviewed the state and trend of the health of the GBR, finding that overall trends remain of significant concern. At the same time, official international concern over the governance of the reef has recently been signalled globally by the International Union for the Conservation of Nature (IUCN). These environmental and political contexts make the GBR an ideal candidate for use in testing and reviewing the application of improved tools for governance risk assessment. (letter)

Synergistic impacts of global warming on the resilience of coral reefs

Science.gov (United States)

Bozec, Yves-Marie; Mumby, Peter J.

2015-01-01

Recent epizootics have removed important functional species from Caribbean coral reefs and left communities vulnerable to alternative attractors. Global warming will impact reefs further through two mechanisms. A chronic mechanism reduces coral calcification, which can result in depressed somatic growth. An acute mechanism, coral bleaching, causes extreme mortality when sea temperatures become anomalously high. We ask how these two mechanisms interact in driving future reef state (coral cover) and resilience (the probability of a reef remaining within a coral attractor). We find that acute mechanisms have the greatest impact overall, but the nature of the interaction with chronic stress depends on the metric considered. Chronic and acute stress act additively on reef state but form a strong synergy when influencing resilience by intensifying a regime shift. Chronic stress increases the size of the algal basin of attraction (at the expense of the coral basin), whereas coral bleaching pushes the system closer to the algal attractor. Resilience can change faster—and earlier—than a change in reef state. Therefore, we caution against basing management solely on measures of reef state because a loss of resilience can go unnoticed for many years and then become disproportionately more difficult to restore.

Umbrella species in marine systems: using the endangered humphead wrasse to conserve coral reefs

DEFF Research Database (Denmark)

Weng, Kevin C.; Pedersen, Martin Wæver; Del Raye, Gen A.

2015-01-01

of the humphead wrasse as an umbrella species for coral reef conservation, we conducted a multi-year study of humphead wrasse home range at Palmyra Atoll, Central Tropical Pacific, tagging juvenile, female, and male individuals with acoustic transmitters. We quantified home range using 2 metrics, length and area.......4 to 14 km and changed with ontogeny. Females had larger home ranges than other reef fishes studied to date (n = 68), indicating value as an umbrella species for coral reefs. We compared the home range of the species to the size distribution of tropical marine protected areas (MPAs), and used a model...

Habitat use patterns of the invasive red lionfish Pterois volitans: a comparison between mangrove and reef systems in San Salvador, Bahamas

Science.gov (United States)

Pimiento, Catalina; Nifong, James C.; Hunter, Margaret E.; Monaco, Eric; Silliman, Brian R.

2015-01-01

The Indo-Pacific red lionfish Pterois volitans is widespread both in its native and its non-native habitats. The rapid invasion of this top predator has had a marked negative effect on fish populations in the Western Atlantic and the Caribbean. It is now well documented that lionfish are invading many tropical and sub-tropical habitats. However, there are fewer data available on the change in lionfish abundance over time and the variation of body size and diet across habitats. A recent study in San Salvador, Bahamas, found body size differences between individuals from mangrove and reef systems. That study further suggested that ontogenetic investigation of habitat use patterns could help clarify whether lionfish are using the mangrove areas of San Salvador as nurseries. The aim of the present study is to determine temporal trends in lionfish relative abundance in mangrove and reef systems in San Salvador, and to further assess whether there is evidence suggesting an ontogenetic shift from mangroves to reef areas. Accordingly, we collected lionfish from mangrove and reef habitats and calculated catch per unit effort (a proxy for relative abundance), compared body size distributions across these two systems, and employed a combination of stable isotope, stomach content, and genetic analyses of prey, to evaluate differences in lionfish trophic interactions and habitat use patterns. Our results show that populations may have increased in San Salvador during the last 4 years, and that there is a strong similarity in body size between habitats, stark differences in prey items, and no apparent overlap in the use of habitat and/or food resources. These results suggest that there is not evidence an for ontogenetic shift from mangroves to reefs, and support other studies that propose lionfish are opportunistic forages with little movement across habitats.

NMFS Reef Survey Forms

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Reef Environmental Survey Project (REEF) mission to educate and enlist divers in the conservation of marine habitats is accomplished primarily through its Fish...

Linking Wave Forcing to Coral Cover and Structural Complexity Across Coral Reef Flats

Science.gov (United States)

Harris, D. L.; Rovere, A.; Parravicini, V.; Casella, E.

2015-12-01

The hydrodynamic regime is a significant component in the geomorphic and ecological development of coral reefs. The energy gradients and flow conditions generated by the breaking and transformation of waves across coral reef crests and flats drive changes in geomorphic structure, and coral growth form and distribution. One of the key aspects in regulating the wave energy propagating across reef flats is the rugosity or roughness of the benthic substrate. Rugosity and structural complexity of coral reefs is also a key indicator of species diversity, ecological functioning, and reef health. However, the links between reef rugosity, coral species distribution and abundance, and hydrodynamic forcing are poorly understood. In this study we examine this relationship by using high resolution measurement of waves in the surf zone and coral reef benthic structure.Pressure transducers (logging at 4 Hz) were deployed in cross reef transects at two sites (Tiahura and Ha'apiti reef systems) in Moorea, French Polynesia with wave characteristics determined on a wave by wave basis. A one dimensional hydrodynamic model (XBeach) was calibrated from this data to determine wave processes on the reef flats under average conditions. Transects of the reef benthic structure were conducted using photographic analysis and the three dimensional reef surface was constructed using structure from motion procedures. From this analysis reef rugosity, changes in coral genus and growth form, and across reef shifts in benthic community were determined. The results show clear changes in benthic assemblages along wave energy gradients with some indication of threshold values of wave induced bed shear stress above which live coral cover was reduced. Reef rugosity was shown to be significantly along the cross-reef transect which has important implications for accurate assessment of wave dissipation across coral reef flats. Links between reef rugosity and coral genus were also observed and may indicate

Coral reefs - Specialized ecosystems

Digital Repository Service at National Institute of Oceanography (India)

Wafar, M.V.M.

This paper discusses briefly some aspects that characterize and differentiate coral reef ecosystems from other tropical marine ecosystems. A brief account on the resources that are extractable from coral reefs, their susceptibility to natural...

Chitons (Mollusca, Polyplacophora from Alacranes Reef, Yucatan, Mexico

Directory of Open Access Journals (Sweden)

Adriana Reyes-Gómez

2017-04-01

Full Text Available This study represents the first comprehensive chiton study from Alacranes Reef, the largest reef system in the Gulf of Mexico. Nine chiton species were found in seven localities within the area, in the intertidal and subtidal to 12 m depth. SEM examination of C. janeirensis, A. hemphilli, T. schrammi and C. floridanus, showed variations in the sculpture and radular teeth morphology when compared to specimens of the same species from Florida Keys, Bahamas and Puerto Rico. The distribution ranges of T. schrammi, L. liozonis and S. floridana are extended into the south-western area of the Gulf of Mexico. Altogether, combining previous literature and the present survey, reports eleven chiton species which have now been recorded within the Alacranes reef area.

Chitons (Mollusca, Polyplacophora) from Alacranes Reef, Yucatan, Mexico

Science.gov (United States)

Reyes-Gómez, Adriana; Ortigosa, Deneb; Simões, Nuno

2017-01-01

Abstract This study represents the first comprehensive chiton study from Alacranes Reef, the largest reef system in the Gulf of Mexico. Nine chiton species were found in seven localities within the area, in the intertidal and subtidal to 12 m depth. SEM examination of C. janeirensis, A. hemphilli, T. schrammi and C. floridanus, showed variations in the sculpture and radular teeth morphology when compared to specimens of the same species from Florida Keys, Bahamas and Puerto Rico. The distribution ranges of T. schrammi, L. liozonis and S. floridana are extended into the south-western area of the Gulf of Mexico. Altogether, combining previous literature and the present survey, reports eleven chiton species which have now been recorded within the Alacranes reef area. PMID:28769624

The influence of coral reef benthic condition on associated fish assemblages.

Directory of Open Access Journals (Sweden)

Karen M Chong-Seng

Full Text Available Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58% and high structural complexity to high macroalgae cover (up to 95% and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

Understanding Resilience in a Vulnerable Industry: the Case of Reef Tourism in Australia

Directory of Open Access Journals (Sweden)

Duan Biggs

2011-03-01

Full Text Available Understanding the resilience of vulnerable sectors of social-ecological systems is critical in an era of escalating global change. The coral reef tourism sector is highly vulnerable not only to ecological effects of climate change and other anthropogenic disturbances on reefs, but also to shocks such as economic recession and energy price escalation. Commercial tourism enterprises are key players in reef tourism in Australia and elsewhere. However, the factors that confer resilience to reef-based tourism enterprises, or the reef tourism sector more broadly, in the face of large disturbances have not been investigated to date. This paper empirically examines the perceived resilience of reef tourism enterprises on Australia's Great Barrier Reef to large disturbances or shocks. Binary logistic regression analysis of two measures of enterprise resilience demonstrates the importance of human capital in strengthening enterprise resilience. Lifestyle identity, measured as the extent to which owners and senior managers are active in reef tourism as a lifestyle choice, is positively related to enterprise resilience. Finally, reef tourism enterprises indicate that financial and marketing support are the most important actions that government can take to support enterprises in the face of a large shock.

Coastal nutrification and coral health at Porto Seguro reefs, Brazil

Science.gov (United States)

Costa, O.; Attrill, M.; Nimmo, M.

2003-04-01

Human activities have substantially increased the natural flux of nutrients to coastal systems worldwide. In Brazilian reefs, all major stresses (sedimentation, overfishing, tourism-related activities and nutrification) are human induced. To assess nutrification levels in Brazilian coastal reefs, measurements of the distribution patterns of nutrients and chlorophyll concentrations were conducted in three nearshore and offshore reefs with distinct nutrient inputs along the south coast of Bahia State. Seawater and porewater samples were analysed for soluble reactive phosphorus, total oxidised nitrogen and reactive silica. Benthic surveys were performed at all sites to investigate the relationships between benthic community composition and nutrient and chlorophyll concentrations. Sampling was undertaken in dry and rainy seasons. Results of both seawater and porewater nutrient measurements revealed the occurrence of consistent spatial and temporal patterns. An inshore-offshore gradient reflects the occurrence of land-based point sources, with significant amount of nutrients being delivered by human activities on the coast (untreated sewage and groundwater seepage). Another spatial gradient is related to distance from a localized source of pollution (an urban settlement without sewerage treatment) with two nearshore reefs presenting distinct nutrient and chlorophyll concentrations. Seasonal variations suggest that submarine groundwater discharge (SGD) is the primary source of nutrients for the coastal reefs during rainy season. The data also suggests that the SGD effect is not restricted to nearshore reefs, and may be an important factor controlling the differences between landward and seaward sides on the offshore reef. Benthic community assessment revealed that turf alga is the dominant group in all studied reefs and that zoanthids are the organisms most adapted to take advantage of nutrient increase in coastal areas. At nearshore reefs, there was a negative

Coral reefs and eutrophication

International Nuclear Information System (INIS)

Stambler, N.

1999-01-01

Coral reefs are found in oligotrophic waters, which are poor in nutrients such as nitrogen, phosphate, and possibly iron. In spite of this, coral reefs exhibit high gross primary productivity rates. They thrive in oligotrophic conditions because of the symbiotic relationship between corals and dinoflagellate algae (zooxanthellae) embedded in the coral tissue. In their mutualistic symbiosis, the zooxanthellae contribute their photosynthetic capability as the basis for the metabolic energy of the whole association, and eventually of a great part of the entire reef ecosystem

Rapidly increasing macroalgal cover not related to herbivorous fishes on Mesoamerican reefs

Directory of Open Access Journals (Sweden)

Adam Suchley

2016-05-01

Full Text Available Long-term phase shifts from coral to macroalgal dominated reef systems are well documented in the Caribbean. Although the impact of coral diseases, climate change and other factors is acknowledged, major herbivore loss through disease and overfishing is often assigned a primary role. However, direct evidence for the link between herbivore abundance, macroalgal and coral cover is sparse, particularly over broad spatial scales. In this study we use a database of coral reef surveys performed at 85 sites along the Mesoamerican Reef of Mexico, Belize, Guatemala and Honduras, to examine potential ecological links by tracking site trajectories over the period 2005–2014. Despite the long-term reduction of herbivory capacity reported across the Caribbean, the Mesoamerican Reef region displayed relatively low macroalgal cover at the onset of the study. Subsequently, increasing fleshy macroalgal cover was pervasive. Herbivorous fish populations were not responsible for this trend as fleshy macroalgal cover change was not correlated with initial herbivorous fish biomass or change, and the majority of sites experienced increases in macroalgae browser biomass. This contrasts the coral reef top-down herbivore control paradigm and suggests the role of external factors in making environmental conditions more favourable for algae. Increasing macroalgal cover typically suppresses ecosystem services and leads to degraded reef systems. Consequently, policy makers and local coral reef managers should reassess the focus on herbivorous fish protection and consider complementary measures such as watershed management in order to arrest this trend.

Operationalizing resilience for adaptive coral reef management under global environmental change.

Science.gov (United States)

Anthony, Kenneth R N; Marshall, Paul A; Abdulla, Ameer; Beeden, Roger; Bergh, Chris; Black, Ryan; Eakin, C Mark; Game, Edward T; Gooch, Margaret; Graham, Nicholas A J; Green, Alison; Heron, Scott F; van Hooidonk, Ruben; Knowland, Cheryl; Mangubhai, Sangeeta; Marshall, Nadine; Maynard, Jeffrey A; McGinnity, Peter; McLeod, Elizabeth; Mumby, Peter J; Nyström, Magnus; Obura, David; Oliver, Jamie; Possingham, Hugh P; Pressey, Robert L; Rowlands, Gwilym P; Tamelander, Jerker; Wachenfeld, David; Wear, Stephanie

2015-01-01

Cumulative pressures from global climate and ocean change combined with multiple regional and local-scale stressors pose fundamental challenges to coral reef managers worldwide. Understanding how cumulative stressors affect coral reef vulnerability is critical for successful reef conservation now and in the future. In this review, we present the case that strategically managing for increased ecological resilience (capacity for stress resistance and recovery) can reduce coral reef vulnerability (risk of net decline) up to a point. Specifically, we propose an operational framework for identifying effective management levers to enhance resilience and support management decisions that reduce reef vulnerability. Building on a system understanding of biological and ecological processes that drive resilience of coral reefs in different environmental and socio-economic settings, we present an Adaptive Resilience-Based management (ARBM) framework and suggest a set of guidelines for how and where resilience can be enhanced via management interventions. We argue that press-type stressors (pollution, sedimentation, overfishing, ocean warming and acidification) are key threats to coral reef resilience by affecting processes underpinning resistance and recovery, while pulse-type (acute) stressors (e.g. storms, bleaching events, crown-of-thorns starfish outbreaks) increase the demand for resilience. We apply the framework to a set of example problems for Caribbean and Indo-Pacific reefs. A combined strategy of active risk reduction and resilience support is needed, informed by key management objectives, knowledge of reef ecosystem processes and consideration of environmental and social drivers. As climate change and ocean acidification erode the resilience and increase the vulnerability of coral reefs globally, successful adaptive management of coral reefs will become increasingly difficult. Given limited resources, on-the-ground solutions are likely to focus increasingly on

A Synthesis and Comparison of Approaches for Quantifying Coral Reef Structure

Science.gov (United States)

Duvall, M. S.; Hench, J. L.

2016-02-01

The complex physical structures of coral reefs provide substrate for benthic organisms, surface area for material fluxes, and have been used as a predictor of reef-fish biomass and biodiversity. Coral reef topography has a first order effect on reef hydrodynamics by imposing drag forces and increasing momentum and scalar dispersion. Despite its importance, quantifying reef topography remains a challenge, as it is patchy and discontinuous while also varying over orders of magnitude in spatial scale. Previous studies have quantified reef structure using a range of 1D and 2D metrics that estimate vertical roughness, which is the departure from a flat geometric profile or surface. However, there is no general mathematical or conceptual framework by which to apply or compare these roughness metrics. While the specific calculations of different metrics vary, we propose that they can be classified into four categories based on: 1) vertical relief relative to a reference height; 2) gradients in vertical relief; 3) surface contour distance; or 4) variations in roughness with scale. We apply metrics from these four classes to idealized reef topography as well as natural reef topography data from Moorea, French Polynesia. Through the use of idealized profiles, we demonstrate the potential for reefs with different morphologies to possess the same value for some scale-dependent metrics (i.e. classes 1-3). Due to the superposition of variable-scale roughness elements in reef topography, we find that multi-scale metrics (i.e. class 4) can better characterize structural complexity by capturing surface roughness across a range of spatial scales. In particular, we provide evidence of the ability of 1D continuous wavelet transforms to detect changes in dominant roughness scales on idealized topography as well as within real reef systems.

Eddy covariance measurement of the spatial heterogeneity of surface energy exchanges over Heron Reef, Great Barrier Reef, Australia

Science.gov (United States)

MacKellar, M.; McGowan, H. A.; Phinn, S. R.

2011-12-01

Coral reefs cover 2.8 to 6.0 x 105 km2 of the Earth's surface and are warm, shallow regions that are believed to contribute enhanced sensible and latent heat to the atmosphere, relative to the surrounding ocean. To predict the impact of climate variability on coral reefs and their weather and climate including cloud, winds, rainfall patterns and cyclone genesis, accurate parameterisation of air-sea energy exchanges over coral reefs is essential. This is also important for the parameterisation and validation of regional to global scale forecast models to improve prediction of tropical and sub-tropical marine and coastal weather. Eddy covariance measurements of air-sea fluxes over coral reefs are rare due to the complexities of installing instrumentation over shallow, tidal water. Consequently, measurements of radiation and turbulent flux data for coral reefs have been captured remotely (satellite data) or via single measurement sites downwind of coral reefs (e.g. terrestrial or shipboard instrumentation). The resolution of such measurements and those that have been made at single locations on reefs may not capture the spatial heterogeneity of surface-atmosphere energy exchanges due to the different geomorphic and biological zones on coral reefs. Accordingly, the heterogeneity of coral reefs with regard to substrate, benthic communities and hydrodynamic processes are not considered in the characterization of the surface radiation energy flux transfers across the water-atmosphere interface. In this paper we present a unique dataset of concurrent in situ eddy covariance measurements made on instrumented pontoons of the surface energy balance over different geomorphic zones of a coral reef (shallow reef flat, shallow and deep lagoons). Significant differences in radiation transfers and air-sea turbulent flux exchanges over the reef were highlighted, with higher Bowen ratios over the shallow reef flat. Increasing wind speed was shown to increase flux divergence between

Coral Reef and Hardbottom from Unified Florida Reef Tract Map (NODC Accession 0123059)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a subset of the Unified Map representing Coral reef and Hardbottom areas. Version 1.1 - December 2013. The Unified Florida Reef Tract Map (Unified...

Testing the effect of habitat structure and complexity on nekton assemblages using experimental oyster reefs

Science.gov (United States)

Humphries, Austin T.; LaPeyre, Megan K.; Kimball, Matthew E.; Rozas, Lawrence P.

2011-01-01

Structurally complex habitats are often associated with more diverse and abundant species assemblages in both aquatic and terrestrial ecosystems. Biogenic reefs formed by the eastern oyster (Crassostrea virginica) are complex in nature and are recognized for their potential habitat value in estuarine systems along the US Atlantic and Gulf of Mexico coasts. Few studies, however, have examined the response of nekton to structural complexity within oyster reefs. We used a quantitative sampling technique to examine how the presence and complexity of experimental oyster reefs influence the abundance, biomass, and distribution of nekton by sampling reefs 4 months and 16 months post-construction. Experimental oyster reefs were colonized immediately by resident fishes and decapod crustaceans, and reefs supported a distinct nekton assemblage compared to mud-bottom habitat. Neither increased reef complexity, nor age of the experimental reef resulted in further changes in nekton assemblages or increases in nekton abundance or diversity. The presence of oyster reefs per se was the most important factor determining nekton usage.

Ontogenetic dietary changes of coral reef fishes in the mangrove-seagress-reef continuum: stable isotope and gut-content analysis

NARCIS (Netherlands)

Cocheret de la Morinière, E.; Pollux, B.J.A.; Nagelkerken, I.; Hemminga, M.A.; Huiskes, A.H.L.; Van der Velde, G.

2003-01-01

Juveniles of a number of reef fish species develop in shallow-water 'nursery' habitats such as mangroves and seagrass beds, and then migrate to the coral reef. This implies that some reef fish species are distributed over the mangrove-seagrass-reef continuum in subpopulations with different size

Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras.

Science.gov (United States)

Titus, Benjamin M; Daly, Marymegan; Exton, Dan A

2015-01-01

Contact between humans and the marine environment is increasing, but the capacity of communities to adapt to human presence remains largely unknown. The popularization of SCUBA diving has added a new dimension to human impacts in aquatic systems and, although individual-level impacts have been identified, cumulative effects on ecosystem function and community-wide responses are unclear. In principle, habituation may mitigate the consequences of human presence on the biology of an individual and allow the quick resumption of its ecological roles, but this has not been documented in aquatic systems. Here, we investigate the short-term impact of human presence and the long-term habituation potential of reef-fish communities to recreational SCUBA divers by studying symbiotic cleaning interactions on coral reefs with differing levels of historical contact with divers. We show that incidences of human contact result in a smaller decline in ecosystem function and more rapid resumption of baseline services on a reef in Utila, Honduras that has heavy historical levels of SCUBA diver presence, compared to an un-dived reef site in the Cayos Cochinos Marine Protected Area (CCMPA). Nonetheless, despite the generally smaller change in ecosystem function and decades of regular contact with divers, cleaning behavior is suppressed by >50% at Utila when divers are present. We hypothesize that community-wide habituation of reef fish is not fully achievable and may be biologically restricted to only partial habituation. Differential responses to human presence impacts the interpretation and execution of behavioral research where SCUBA is the predominant means of data collection, and provides an important rationale for future research investigating the interplay between human presence, ecosystem function, and community structure on coral reefs.

Coral identity underpins architectural complexity on Caribbean reefs.

Science.gov (United States)

Alvarez-Filip, Lorenzo; Dulvy, Nicholas K; Côte, Isabelle M; Watkinson, Andrew R; Gill, Jennifer A

2011-09-01

The architectural complexity of ecosystems can greatly influence their capacity to support biodiversity and deliver ecosystem services. Understanding the components underlying this complexity can aid the development of effective strategies for ecosystem conservation. Caribbean coral reefs support and protect millions of livelihoods, but recent anthropogenic change is shifting communities toward reefs dominated by stress-resistant coral species, which are often less architecturally complex. With the regionwide decline in reef fish abundance, it is becoming increasingly important to understand changes in coral reef community structure and function. We quantify the influence of coral composition, diversity, and morpho-functional traits on the architectural complexity of reefs across 91 sites at Cozumel, Mexico. Although reef architectural complexity increases with coral cover and species richness, it is highest on sites that are low in taxonomic evenness and dominated by morpho-functionally important, reef-building coral genera, particularly Montastraea. Sites with similar coral community composition also tend to occur on reefs with very similar architectural complexity, suggesting that reef structure tends to be determined by the same key species across sites. Our findings provide support for prioritizing and protecting particular reef types, especially those dominated by key reef-building corals, in order to enhance reef complexity.

Ecological States and the Resilience of Coral Reefs

Directory of Open Access Journals (Sweden)

Tim McClanahan

2002-12-01

Full Text Available We review the evidence for multiple ecological states and the factors that create ecological resilience in coral reef ecosystems. There are natural differences among benthic communities along gradients of water temperature, light, nutrients, and organic matter associated with upwelling-downwelling and onshore-offshore systems. Along gradients from oligotrophy to eutrophy, plant-animal symbioses tend to decrease, and the abundance of algae and heterotrophic suspension feeders and the ratio of organic to inorganic carbon production tend to increase. Human influences such as fishing, increased organic matter and nutrients, sediments, warm water, and transportation of xenobiotics and diseases are common causes of a large number of recently reported ecological shifts. It is often the interaction of persistent and multiple synergistic disturbances that causes permanent ecological transitions, rather than the succession of individual short-term disturbances. For example, fishing can remove top-level predators, resulting in the ecological release of prey such as sea urchins and coral-eating invertebrates. When sea urchins are not common because of unsuitable habitat, recruitment limitations, and diseases, and when overfishing removes herbivorous fish, frondose brown algae can dominate. Terrigenous sediments carried onto reefs as a result of increased soil erosion largely promote the dominance of turf or articulated green algae. Elevated nutrients and organic matter can increase internal eroders of reef substratum and a mixture of filamentous algae. Local conservation actions that attempt to reduce fishing and terrestrial influences promote the high production of inorganic carbon that is necessary for reef growth. However, global climate change threatens to undermine such actions because of increased bleaching and mortality caused by warm-water anomalies, weakened coral skeletons caused by reduced aragonite availability in reef waters, and increased

Ocean Acidification Refugia of the Florida Reef Tract

Science.gov (United States)

Manzello, Derek P.; Enochs, Ian C.; Melo, Nelson; Gledhill, Dwight K.; Johns, Elizabeth M.

2012-01-01

Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO2, alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO2 (TCO2) which increases aragonite saturation state (Ωarag) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ωarag than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error) Ωarag-values in spring = 4.69 (±0.101). Conversely, Ωarag-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO2 mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA. PMID:22848575

Ocean acidification refugia of the Florida Reef Tract.

Directory of Open Access Journals (Sweden)

Derek P Manzello

Full Text Available Ocean acidification (OA is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO(2, alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT. During periods of heightened productivity, there is a net uptake of total CO(2 (TCO(2 which increases aragonite saturation state (Ω(arag values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ω(arag than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error Ω(arag-values in spring = 4.69 (±0.101. Conversely, Ω(arag-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO(2 mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA.

Unmixing-Based Denoising as a Pre-Processing Step for Coral Reef Analysis

Science.gov (United States)

Cerra, D.; Traganos, D.; Gege, P.; Reinartz, P.

2017-05-01

Coral reefs, among the world's most biodiverse and productive submerged habitats, have faced several mass bleaching events due to climate change during the past 35 years. In the course of this century, global warming and ocean acidification are expected to cause corals to become increasingly rare on reef systems. This will result in a sharp decrease in the biodiversity of reef communities and carbonate reef structures. Coral reefs may be mapped, characterized and monitored through remote sensing. Hyperspectral images in particular excel in being used in coral monitoring, being characterized by very rich spectral information, which results in a strong discrimination power to characterize a target of interest, and separate healthy corals from bleached ones. Being submerged habitats, coral reef systems are difficult to analyse in airborne or satellite images, as relevant information is conveyed in bands in the blue range which exhibit lower signal-to-noise ratio (SNR) with respect to other spectral ranges; furthermore, water is absorbing most of the incident solar radiation, further decreasing the SNR. Derivative features, which are important in coral analysis, result greatly affected by the resulting noise present in relevant spectral bands, justifying the need of new denoising techniques able to keep local spatial and spectral features. In this paper, Unmixing-based Denoising (UBD) is used to enable analysis of a hyperspectral image acquired over a coral reef system in the Red Sea based on derivative features. UBD reconstructs pixelwise a dataset with reduced noise effects, by forcing each spectrum to a linear combination of other reference spectra, exploiting the high dimensionality of hyperspectral datasets. Results show clear enhancements with respect to traditional denoising methods based on spatial and spectral smoothing, facilitating the coral detection task.

Spatial and tidal variation in food supply to shallow cold-water coral reefs of the Mingulay Reef complex (Outer Hebrides, Scotland)

NARCIS (Netherlands)

Duineveld, G.C.A.; Jeffreys, R.M.; Lavaleye, M.S.S.; Davies, A.J.; Bergman, M.J.N.; Watmough, T.; Witbaard, R.

2012-01-01

The finding of a previously undescribed cold-water coral reef (Banana Reef) in the Scottish Mingulay reef complex, with denser coverage of living Lophelia pertusa than the principal Mingulay 1 Reef, was the incentive for a comparative study of the food supply to the 2 reefs. Suspended particulate

Cryptic Coral Reef Diversity Across the Pacific Assessed using Autonomous Reef Monitoring Structures and Multi-omic Methods

Science.gov (United States)

Ransome, E. J.; Timmers, M.; Hartmann, A.; Collins, A.; Meyer, C.

2016-02-01

Coral reefs harbor diverse and distinct eukaryotic, bacterial and viral communities, which are critically important for their success. The lack of standardized measures for comprehensively assessing reef diversity has been a major obstacle in understanding the complexity of eukaryotic and microbial associations, and the processes that drive ecosystem shifts on reefs. ARMS, which mimic the structural complexity of the reef using artificial settlement plates, were used to systematically measure reef biodiversity across the Indo-Pacific. This device allows for standardized sampling of reef microbes to metazoans, providing the opportunity to investigate the fundamental links between these groups at an ecosystem level. We integrate the use of traditional ecology methods with metagenomics and metabolomics (metabolic predictors) to quantify the taxonomic composition of one of the planet's most diverse ecosystems and to assess the fundamental links between these cryptic communities and ecosystem function along geographical and anthropogenic stress gradients.

MANGROVE-DERIVED NUTRIENTS AND CORAL REEFS

Science.gov (United States)

Understanding the consequences of the declining global cover of mangroves due to anthropogenic disturbance necessitates consideration of how mangrove-derived nutrients contribute to threatened coral reef systems. We sampled potential sources of organic matter and a suite of sessi...

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

Coral reefs as eco-energy factories. Eco-energy kichi to shite no sangosho

Energy Technology Data Exchange (ETDEWEB)

Nozaki, K [Electrochemical Laboratory, Tsukuba (Japan)

1993-05-01

This paper gives an outline of basic problems related to possibilities of CO2 fixing technologies using coral reefs, and problems in their development. The paper describes that primary production (of organic matters) per unit area of a coral reef shows a value exceeding that with tropical rain forests. However, with respect to whether an effective CO2 fixing system could be structured, there are questions to be answered to CO2 fixing mechanisms in coral reefs and to where organic matters produced in coral reefs would go. For the latter problem, the following three cases may be assumed: Accumulation in coral bottom materials; flow-out from a coral reef and transfer to deep ocean layers; and decomposition into CO2 and water as a result of actions of microorganisms. As regards development of CO2 fixing technologies, the paper indicates necessity of discussions on the following matters: Utilization of ocean thermal energy conversion in addition to promoting CO2 fixation using coral reefs; dissolution of coral reef limestone by injecting liquefied CO2; and utilization of coral reefs as energy transportation relaying stations. 3 refs., 2 figs.

Cyanobacteria in Coral Reef Ecosystems: A Review

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L. Charpy

2012-01-01

Full Text Available Cyanobacteria have dominated marine environments and have been reef builders on Earth for more than three million years (myr. Cyanobacteria still play an essential role in modern coral reef ecosystems by forming a major component of epiphytic, epilithic, and endolithic communities as well as of microbial mats. Cyanobacteria are grazed by reef organisms and also provide nitrogen to the coral reef ecosystems through nitrogen fixation. Recently, new unicellular cyanobacteria that express nitrogenase were found in the open ocean and in coral reef lagoons. Furthermore, cyanobacteria are important in calcification and decalcification. All limestone surfaces have a layer of boring algae in which cyanobacteria often play a dominant role. Cyanobacterial symbioses are abundant in coral reefs; the most common hosts are sponges and ascidians. Cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. Cyanobacteria can also form pathogenic microbial consortia in association with other microbes on living coral tissues, causing coral tissue lysis and death, and considerable declines in coral reefs. In deep lagoons, coccoid cyanobacteria are abundant and are grazed by ciliates, heteroflagellates, and the benthic coral reef community. Cyanobacteria produce metabolites that act as attractants for some species and deterrents for some grazers of the reef communities.

Pleistocene reef development in Bulukumba, South Sulawesi

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Muhammad Imran Andi

2017-01-01

Full Text Available Quaternary reefs are commonly studied right now to explain climate change during that time. They act as a good archive of climate change, because their development is influenced by climate condition. The research area is located in the southern tip of Bulukumba Regency, South Sulawesi. The objective of this research is to define the development of the reef. Methods applied in this research are field survey of 4 line transects along reef cliff. Laboratory work is mostly on petrographic and biofacies analyses in order to reconstruct the reef development. Four reef biofacies have developed in this study namely 1 Coralgal framestone - wackestone, 2 Massive coral framestone facies, 3 Platylike coral Bindstone facies, and 4 Branching Coral Bafflestone facies. Based on the facies association and organism accumulation, the reefs are interpreted to be developed within a reef complex in a shallow marine environment.

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across American Samoa from 2012 to 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

Photography of Coral Reefs from ISS

Science.gov (United States)

Robinson, Julie A.

2009-01-01

This viewgraph presentation reviews the uses of photography from the International Space Station (ISS) in studying Earth's coral reefs. The photographs include reefs in various oceans . The photographs have uses for science in assisting NASA mapping initiatives, distribution worldwide through ReefBase, and by biologist in the field.

Environmental quality and preservation; reefs, corals, and carbonate sands; guides to reef-ecosystem health and environment

Science.gov (United States)

Lidz, Barbara H.

2001-01-01

Introduction In recent years, the health of the entire coral reef ecosystem that lines the outer shelf off the Florida Keys has declined markedly. In particular, loss of those coral species that are the building blocks of solid reef framework has significant negative implications for economic vitality of the region. What are the reasons for this decline? Is it due to natural change, or are human activities (recreational diving, ship groundings, farmland runoff, nutrient influx, air-borne contaminants, groundwater pollutants) a contributing factor and if so, to what extent? At risk of loss are biologic resources of the reefs, including habitats for endangered species in shoreline mangroves, productive marine and wetland nurseries, and economic fisheries. A healthy reef ecosystem builds a protective offshore barrier to catastrophic wave action and storm surges generated by tropical storms and hurricanes. In turn, a healthy reef protects the homes, marinas, and infrastructure on the Florida Keys that have been designed to capture a lucrative tourism industry. A healthy reef ecosystem also protects inland agricultural and livestock areas of South Florida whose produce and meat feed much of the United States and other parts of the world. In cooperation with the National Oceanic and Atmospheric Administration's (NOAA) National Marine Sanctuary Program, the U.S. Geological Survey (USGS) continues longterm investigations of factors that may affect Florida's reefs. One of the first steps in distinguishing between natural change and the effects of human activities, however, is to determine how coral reefs have responded to past environmental change, before the advent of man. By so doing, accurate scientific information becomes available for Marine Sanctuary management to understand natural change and thus to assess and regulate potential human impact better. The USGS studies described here evaluate the distribution (location) and historic vitality (thickness) of Holocene

Cumulative Human Impacts on Coral Reefs: Assessing Risk and Management Implications for Brazilian Coral Reefs

OpenAIRE

Rafael A. Magris; Alana Grech; Robert L. Pressey

2018-01-01

Effective management of coral reefs requires strategies tailored to cope with cumulative disturbances from human activities. In Brazil, where coral reefs are a priority for conservation, intensifying threats from local and global stressors are of paramount concern to management agencies. Using a cumulative impact assessment approach, our goal was to inform management actions for coral reefs in Brazil by assessing their exposure to multiple stressors (fishing, land-based activities, coastal de...

Pacific Circulation and the Resilience of its Equatorial Reefs

Science.gov (United States)

Cohen, A. L.; Drenkard, E.

2012-12-01

High rates of calcification by tropical reef-building corals are paramount to the maintenance of healthy reefs. Investigations of the impact of ocean acidification in both laboratory and field studies demonstrate unequivocally the dependence of coral and coral reef calcification on the carbonate ion concentration of seawater, a dependence predicted by fundamental laws of physical chemistry. Nevertheless, results from a new generation of experiments that exploit the biology of coral calcification, suggest that effects of ocean acidification can - in some instances - be mitigated with simultaneous manipulation of multiple factors. These laboratory results imply that coral reefs in regions projected to experience changes in, for example, nutrient delivery, light and flow, in addition to pH and carbonate ion concentration, may be more resilient (or vulnerable) to the effects of ocean acidification alone. If demonstrated to be true, these observations have profound implications for the conservation and management of coral reefs in the 21st century. We quantified spatial and temporal variability in rates of calcification of a dominant Indo-Pacific reef building coral across sites where changes in ocean circulation patterns drive variability in multiple physical, chemical and biological parameters. Such changes are occurring against a background of variability and trends in carbonate system chemistry. Our field data provide support for hypotheses based on laboratory observations, and show that impacts of ocean acidification on coral calcification can be partially and in some cases, fully, offset by simultaneous changes in multiple factors. Our results imply that projected changes in oceanic and atmospheric circulation patterns, driven by global warming, must be considered when predicting coral reef resilience, or vulnerability, to 21st century ocean acidification.

Turning up the heat: increasing temperature and coral bleaching at the high latitude coral reefs of the Houtman Abrolhos Islands.

Science.gov (United States)

Abdo, David A; Bellchambers, Lynda M; Evans, Scott N

2012-01-01

Coral reefs face increasing pressures particularly when on the edge of their distributions. The Houtman Abrolhos Islands (Abrolhos) are the southernmost coral reef system in the Indian Ocean, and one of the highest latitude reefs in the world. These reefs have a unique mix of tropical and temperate marine fauna and flora and support 184 species of coral, dominated by Acropora species. A significant La Niña event during 2011 produced anomalous conditions of increased temperature along the whole Western Australian coastline, producing the first-recorded widespread bleaching of corals at the Abrolhos. We examined long term trends in the marine climate at the Abrolhos using historical sea surface temperature data (HadISST data set) from 1900-2011. In addition in situ water temperature data for the Abrolhos (from data loggers installed in 2008, across four island groups) were used to determine temperature exposure profiles. Coupled with the results of coral cover surveys conducted annually since 2007; we calculated bleaching thresholds for monitoring sites across the four Abrolhos groups. In situ temperature data revealed maximum daily water temperatures reached 29.54°C in March 2011 which is 4.2°C above mean maximum daily temperatures (2008-2010). The level of bleaching varied across sites with an average of ∼12% of corals bleached. Mortality was high, with a mean ∼50% following the 2011 bleaching event. Prior to 2011, summer temperatures reached a mean (across all monitoring sites) of 25.1°C for 2.5 days. However, in 2011 temperatures reached a mean of 28.1°C for 3.3 days. Longer term trends (1900-2011) showed mean annual sea surface temperatures increase by 0.01°C per annum. Long-term temperature data along with short-term peaks in 2011, outline the potential for corals to be exposed to more frequent bleaching risk with consequences for this high latitude coral reef system at the edge of its distribution.

Fishing down the largest coral reef fish species.

Science.gov (United States)

Fenner, Douglas

2014-07-15

Studies on remote, uninhabited, near-pristine reefs have revealed surprisingly large populations of large reef fish. Locations such as the northwestern Hawaiian Islands, northern Marianas Islands, Line Islands, U.S. remote Pacific Islands, Cocos-Keeling Atoll and Chagos archipelago have much higher reef fish biomass than islands and reefs near people. Much of the high biomass of most remote reef fish communities lies in the largest species, such as sharks, bumphead parrots, giant trevally, and humphead wrasse. Some, such as sharks and giant trevally, are apex predators, but others such as bumphead parrots and humphead wrasse, are not. At many locations, decreases in large reef fish species have been attributed to fishing. Fishing is well known to remove the largest fish first, and a quantitative measure of vulnerability to fishing indicates that large reef fish species are much more vulnerable to fishing than small fish. The removal of large reef fish by fishing parallels the extinction of terrestrial megafauna by early humans. However large reef fish have great value for various ecological roles and for reef tourism. Copyright © 2014 Elsevier Ltd. All rights reserved.

COLLABORATIVE GUIDE: A REEF MANAGER'S GUIDE TO ...

Science.gov (United States)

Innovative strategies to conserve the world's coral reefs are included in a new guide released today by NOAA, and the Australian Great Barrier Reef Marine Park Authority, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. Referred to as A Reef Manager's Guide to Coral Bleaching, the guide will provide coral reef managers with the latest scientific information on the causes of coral bleaching and new management strategies for responding to this significant threat to coral reef ecosystems. Innovative strategies to conserve the world's coral reefs are included in a new guide released today by NOAA, and the Australian Great Barrier Reef Marine Park Authority, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. Dr. Jordan West, of the National Center for Environmental Assessment, was a major contributor to the guide. Referred to as

High refuge availability on coral reefs increases the vulnerability of reef-associated predators to overexploitation.

Science.gov (United States)

Rogers, Alice; Blanchard, Julia L; Newman, Steven P; Dryden, Charlie S; Mumby, Peter J

2018-02-01

Refuge availability and fishing alter predator-prey interactions on coral reefs, but our understanding of how they interact to drive food web dynamics, community structure and vulnerability of different trophic groups is unclear. Here, we apply a size-based ecosystem model of coral reefs, parameterized with empirical measures of structural complexity, to predict fish biomass, productivity and community structure in reef ecosystems under a broad range of refuge availability and fishing regimes. In unfished ecosystems, the expected positive correlation between reef structural complexity and biomass emerges, but a non-linear effect of predation refuges is observed for the productivity of predatory fish. Reefs with intermediate complexity have the highest predator productivity, but when refuge availability is high and prey are less available, predator growth rates decrease, with significant implications for fisheries. Specifically, as fishing intensity increases, predators in habitats with high refuge availability exhibit vulnerability to over-exploitation, resulting in communities dominated by herbivores. Our study reveals mechanisms for threshold dynamics in predators living in complex habitats and elucidates how predators can be food-limited when most of their prey are able to hide. We also highlight the importance of nutrient recycling via the detrital pathway, to support high predator biomasses on coral reefs. © 2018 by the Ecological Society of America.

Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras.

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Benjamin M Titus

Full Text Available Contact between humans and the marine environment is increasing, but the capacity of communities to adapt to human presence remains largely unknown. The popularization of SCUBA diving has added a new dimension to human impacts in aquatic systems and, although individual-level impacts have been identified, cumulative effects on ecosystem function and community-wide responses are unclear. In principle, habituation may mitigate the consequences of human presence on the biology of an individual and allow the quick resumption of its ecological roles, but this has not been documented in aquatic systems. Here, we investigate the short-term impact of human presence and the long-term habituation potential of reef-fish communities to recreational SCUBA divers by studying symbiotic cleaning interactions on coral reefs with differing levels of historical contact with divers. We show that incidences of human contact result in a smaller decline in ecosystem function and more rapid resumption of baseline services on a reef in Utila, Honduras that has heavy historical levels of SCUBA diver presence, compared to an un-dived reef site in the Cayos Cochinos Marine Protected Area (CCMPA. Nonetheless, despite the generally smaller change in ecosystem function and decades of regular contact with divers, cleaning behavior is suppressed by >50% at Utila when divers are present. We hypothesize that community-wide habituation of reef fish is not fully achievable and may be biologically restricted to only partial habituation. Differential responses to human presence impacts the interpretation and execution of behavioral research where SCUBA is the predominant means of data collection, and provides an important rationale for future research investigating the interplay between human presence, ecosystem function, and community structure on coral reefs.

The status of coral reef ecology research in the Red Sea

KAUST Repository

Berumen, Michael L.

2013-06-21

The Red Sea has long been recognized as a region of high biodiversity and endemism. Despite this diversity and early history of scientific work, our understanding of the ecology of coral reefs in the Red Sea has lagged behind that of other large coral reef systems. We carried out a quantitative assessment of ISI-listed research published from the Red Sea in eight specific topics (apex predators, connectivity, coral bleaching, coral reproductive biology, herbivory, marine protected areas, non-coral invertebrates and reef-associated bacteria) and compared the amount of research conducted in the Red Sea to that from Australia\\'s Great Barrier Reef (GBR) and the Caribbean. On average, for these eight topics, the Red Sea had 1/6th the amount of research compared to the GBR and about 1/8th the amount of the Caribbean. Further, more than 50 % of the published research from the Red Sea originated from the Gulf of Aqaba, a small area (<2 % of the area of the Red Sea) in the far northern Red Sea. We summarize the general state of knowledge in these eight topics and highlight the areas of future research priorities for the Red Sea region. Notably, data that could inform science-based management approaches are badly lacking in most Red Sea countries. The Red Sea, as a geologically "young" sea located in one of the warmest regions of the world, has the potential to provide insight into pressing topics such as speciation processes as well as the capacity of reef systems and organisms to adapt to global climate change. As one of the world\\'s most biodiverse coral reef regions, the Red Sea may yet have a significant role to play in our understanding of coral reef ecology at a global scale. © 2013 Springer-Verlag Berlin Heidelberg.

Impacts of Artificial Reefs and Diving Tourism

Directory of Open Access Journals (Sweden)

Sandra Jakšić

2013-10-01

Full Text Available Coral reefs are currently endangered throughout the world. One of the main activities responsible for this is scuba-diving. Scuba-diving on coral reefs was not problematic in the begging, but due to popularization of the new sport, more and more tourists desired to participate in the activity. Mass tourism, direct contact of the tourists with the coral reefs and unprofessional behavior underwater has a negative effect on the coral reefs. The conflict between nature preservation and economy benefits related to scuba-diving tourism resulted in the creation of artificial reefs, used both to promote marine life and as tourists attractions, thereby taking the pressure off the natural coral reefs. Ships, vehicles and other large structures can be found on the coastal sea floor in North America, Australia, Japan and Europe. The concept of artificial reefs as a scuba-diving attraction was developed in Florida. The main goal was to promote aquaculture, with the popularization of scuba-diving attractions being a secondary effect. The aim of this paper is to determine the effects of artificial reefs on scuba-diving tourism, while taking into account the questionnaire carried out among 18 divers

Large-scale bleaching of corals on the Great Barrier Reef.

Science.gov (United States)

Hughes, T P; Kerry, J T; Simpson, T

2018-02-01

In 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March-April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7-8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite-derived sea surface

Reef Visual Census (RVC) data.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Provide data on frequency of occurrence , density abundance, and length frequency of reef fish throughout Florida reef tract from 1978 forward.

Physical and Biological Controls on the Carbonate Chemistry of Coral Reef Waters: Effects of Metabolism, Wave Forcing, Sea Level, and Geomorphology

Science.gov (United States)

Falter, James L.; Lowe, Ryan J.; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO2, pH, and aragonite saturation state (Ωar) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO2, pH, and Ωar are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO2 relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO2 in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO2. PMID:23326411

Physical and biological controls on the carbonate chemistry of coral reef waters: effects of metabolism, wave forcing, sea level, and geomorphology.

Science.gov (United States)

Falter, James L; Lowe, Ryan J; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO(2), pH, and aragonite saturation state (Ω(ar)) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO(2), pH, and Ω(ar) are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO(2) relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO(2) in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO(2).

Typhoon damage on a shallow mesophotic reef in Okinawa, Japan

Directory of Open Access Journals (Sweden)

Kristine N. White

2013-09-01

Full Text Available Little is known about effects of large storm systems on mesophotic reefs. This study reports on how Typhoon 17 (Jelawat affected Ryugu Reef on Okinawa-jima, Japan in September 2012. Benthic communities were surveyed before and after the typhoon using line intercept transect method. Comparison of the benthic assemblages showed highly significant differences in coral coverage at depths of 25–32 m before and after Typhoon 17. A large deep stand of Pachyseris foliosa was apparently less resistant to the storm than the shallower high diversity area of this reef. Contradictory to common perception, this research shows that large foliose corals at deeper depths are just as susceptible to typhoon damage as shallower branching corals. However, descriptive functional group analyses resulted in only minor changes after the disturbance, suggesting the high likelihood of recovery and the high resilience capacity of this mesophotic reef.

Weapon System Requirements: Detailed Systems Engineering Prior to Product Development Positions Programs for Success

Science.gov (United States)

2016-11-01

modified, replaced, or sustained by consumers or different manufacturers in addition to the manufacturer that developed the system. It also allows...WEAPON SYSTEM REQUIREMENTS Detailed Systems Engineering Prior to Product Development Positions Programs for Success...Engineering Prior to Product Development Positions Programs for Success Why GAO Did This Study Cost and schedule growth in DOD major defense

Sewage pollution in Negril, Jamaica: effects on nutrition and ecology of coral reef macroalgae

Science.gov (United States)

Lapointe, B. E.; Thacker, K.; Hanson, C.; Getten, L.

2011-07-01

Coral reefs in the Negril Marine Park (NMP), Jamaica, have been increasingly impacted by nutrient pollution and macroalgal blooms following decades of intensive development as a major tourist destination. A baseline survey of DIN and SRP concentrations, C:N:P and stable nitrogen isotope ratios (δ15N) of abundant reef macroalgae on shallow and deep reefs of the NMP in 1998 showed strong P-limitation and evidence of increasing sewage pollution. In 1999, a sewage collection and treatment project began diverting wastewater from the resort and urban areas to a pond system that discharged partially-treated effluent into the South Negril River (SNR). These sewage discharges significantly increased concentrations of NH{4/+} and SRP (N:P ˜13) in the SNR, which flows into Long Bay and around Negril's "West End". Concentrations of SRP, the primary limiting nutrient, were higher on shallow reefs of the West End in 2001 compared to 1998. Stable nitrogen isotope ratios (δ15N) of abundant reef macroalgae on both shallow and deep reefs of the West End in 2002 were significantly higher than baseline values in 1998, indicating an escalating impact of sewage nitrogen pollution over this timeframe. The increased nutrient concentrations and δ15N enrichment of reef macroalgae correlated with blooms of the chlorophyte Chaetomorpha linum in shallow waters of Long Bay and Codium isthmocladum and Caulerpa cupressoides on deep reefs of the West End. Sewage treatment systems adjacent to coral reefs must include nutrient removal to ensure that DIN and SRP concentrations, after dilution, are below the low thresholds noted for these oligotrophic ecosystems.

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Marianas Archipelago from 2011 to 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Hawaiian Archipelago from 2010 to 2016

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

An integrated ecosystem model for coral reef management where oceanography, ecology and socio-economics meet

NARCIS (Netherlands)

Weijerman, M.

2015-01-01

Summary

Widespread coral reef decline, including decline in reef fish populations upon which many coastal human populations depend, have led to phase-shifts from the coral-dominated systems, found desirable by humans, to algal-dominated systems that provide less ecosystem

An integrated ecosystem model for coral reef management where oceanography, ecology and socio-economics meet

NARCIS (Netherlands)

Weijerman, Mariska

2015-01-01

Widespread coral reef decline, including decline in reef fish populations upon which many coastal human populations depend, have led to phase-shifts from the coral-dominated systems, found desirable by humans, to algal-dominated systems that provide less ecosystem services, and the loss of

Intra-annual variation in turbidity in response to terrestrial runoff on near-shore coral reefs of the Great Barrier Reef

Science.gov (United States)

Fabricius, Katharina E.; De'ath, Glenn; Humphrey, Craig; Zagorskis, Irena; Schaffelke, Britta

2013-01-01

Seawater turbidity is a fundamental driver of the ecology of coastal marine systems, and is widely used as indicator for environmental reporting. However, the time scales and processes leading to changes in turbidity in tropical coastal waters remain poorly understood. This study investigates the main determinants of inshore turbidity in four inshore regions along ˜1000 km of the Australian Great Barrier Reef, based on ˜3 years of almost continuous in situ turbidity logger data on 14 reefs. Generalized additive mixed models were used to predict spatial and temporal variation in weekly mean turbidity based on variation in resuspension and runoff conditions. At any given wave height, wave period and tidal range, turbidity was significantly affected by river flow and rainfall. Averaged across all reefs, turbidity was 13% lower (range: 5-37%) in weeks with low compared with high rainfall and river flows. Additionally, turbidity was on average 43% lower 250 days into the dry season than at the start of the dry season on reefs with long-term mean turbidity >1.1 NTU. The data suggest the time scale of winnowing or consolidation of newly imported materials in this zone is months to years. In contrast, turbidity returned to low levels within weeks after river flows and rainfall on reefs with long-term mean turbidity of <1.1 NTU. Turbidity was also up to 10-fold higher on reefs near compared to away from river mouths, suggesting inter-annual accumulation of fine resuspendible sediments. The study suggests that a reduction in the river loads of fine sediments and nutrients through improved land management should lead to measurably improved inshore water clarity in the most turbid parts of the GBR.

The Ecological Role of Sharks on Coral Reefs.

Science.gov (United States)

Roff, George; Doropoulos, Christopher; Rogers, Alice; Bozec, Yves-Marie; Krueck, Nils C; Aurellado, Eleanor; Priest, Mark; Birrell, Chico; Mumby, Peter J

2016-05-01

Sharks are considered the apex predator of coral reefs, but the consequences of their global depletion are uncertain. Here we explore the ecological roles of sharks on coral reefs and, conversely, the importance of reefs for sharks. We find that most reef-associated shark species do not act as apex predators but instead function as mesopredators along with a diverse group of reef fish. While sharks perform important direct and indirect ecological roles, the evidence to support hypothesised shark-driven trophic cascades that benefit corals is weak and equivocal. Coral reefs provide some functional benefits to sharks, but sharks do not appear to favour healthier reef environments. Restoring populations of sharks is important and can yet deliver ecological surprise. Copyright © 2016 Elsevier Ltd. All rights reserved.

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages.

Directory of Open Access Journals (Sweden)

Zarinah Waheed

Full Text Available The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39, Agariciidae (n = 30 and Euphylliidae (n = 15. The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51% and good (38%. Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages.

Science.gov (United States)

Waheed, Zarinah; van Mil, Harald G J; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W

2015-01-01

The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

Science.gov (United States)

Waheed, Zarinah; van Mil, Harald G. J.; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W.

2015-01-01

The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park. PMID:26719987

The role of turtles as coral reef macroherbivores

KAUST Repository

Goatley, Christopher H. R.

2012-06-29

Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood. © 2012 Goatley et al.

The role of turtles as coral reef macroherbivores

KAUST Repository

Goatley, Christopher H. R.; Hoey, Andrew; Bellwood, David R.

2012-01-01

Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood. © 2012 Goatley et al.

The role of turtles as coral reef macroherbivores.

Directory of Open Access Journals (Sweden)

Christopher H R Goatley

Full Text Available Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas and hawksbill turtles (Eretmochelys imbricata showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood.

Soft coral abundance on the central Great Barrier Reef: effects of Acanthaster planci, space availability, and aspects of the physical environment

Science.gov (United States)

Fabricius, K. E.

1997-07-01

The distribution and abundance of soft coral genera on reefs of the central Great Barrier Reef was investigated in relation to reef position, recent history of disturbance, wave exposure, substratum slope and depth. Eighty-five 25 m long transects were surveyed at 10 m depth on windward sides of 14 mid- and outer-shelf reefs. A further 75 transects in different zones on one mid-shelf reef (Davies Reef) between 5 and 30 m depth were investigated. The crown-of-thorns starfish Acanthaster planci had caused large-scale mortality of scleractinians on eight of these reefs five to ten years prior to the study, and as a result, scleractinian cover was only 35-55% of that on the six unimpacted reefs. On the impacted reefs, stony corals with massive and encrusting growths form had smaller average colony diameters but similar or slightly lower numerical abundance. In contrast, mean colony size, cover and abundance of branching stony corals showed no difference between impacted and unimpacted reefs. Twenty-four genera of soft corals (in eight families) were recorded, and none showed different abundance or cover in areas of former A. planci impact, compared to unaffected sites. Similarly, no difference was detected among locations in the numbers or area cover of sponges, tunicates, zoanthids, Halimeda or other macro-algae. Mean soft coral cover was 2 to 5% at 10 m on sheltered mid-shelf reefs, and 12 to 17% on more current-exposed reefs. Highest cover and abundances generally occurred on platforms of outer-shelf reefs exposed to relatively strong currents but low wave energy. On Davies Reef, cover and colony numbers of the families Nephtheidae and Xeniidae were low within the zone of wave impact, in flow-protected bays and lagoons, on shaded steep slopes, and at depths above 10 and below 25 m. In contrast, distributions of genera of the family Alcyoniidae were not related to these physical parameters. The physical conditions of a large proportion of habitats appear "sub

A Global Estimate of the Number of Coral Reef Fishers.

Directory of Open Access Journals (Sweden)

Louise S L Teh

Full Text Available Overfishing threatens coral reefs worldwide, yet there is no reliable estimate on the number of reef fishers globally. We address this data gap by quantifying the number of reef fishers on a global scale, using two approaches - the first estimates reef fishers as a proportion of the total number of marine fishers in a country, based on the ratio of reef-related to total marine fish landed values. The second estimates reef fishers as a function of coral reef area, rural coastal population, and fishing pressure. In total, we find that there are 6 million reef fishers in 99 reef countries and territories worldwide, of which at least 25% are reef gleaners. Our estimates are an improvement over most existing fisher population statistics, which tend to omit accounting for gleaners and reef fishers. Our results suggest that slightly over a quarter of the world's small-scale fishers fish on coral reefs, and half of all coral reef fishers are in Southeast Asia. Coral reefs evidently support the socio-economic well-being of numerous coastal communities. By quantifying the number of people who are employed as reef fishers, we provide decision-makers with an important input into planning for sustainable coral reef fisheries at the appropriate scale.

A Global Estimate of the Number of Coral Reef Fishers.

Science.gov (United States)

Teh, Louise S L; Teh, Lydia C L; Sumaila, U Rashid

2013-01-01

Overfishing threatens coral reefs worldwide, yet there is no reliable estimate on the number of reef fishers globally. We address this data gap by quantifying the number of reef fishers on a global scale, using two approaches - the first estimates reef fishers as a proportion of the total number of marine fishers in a country, based on the ratio of reef-related to total marine fish landed values. The second estimates reef fishers as a function of coral reef area, rural coastal population, and fishing pressure. In total, we find that there are 6 million reef fishers in 99 reef countries and territories worldwide, of which at least 25% are reef gleaners. Our estimates are an improvement over most existing fisher population statistics, which tend to omit accounting for gleaners and reef fishers. Our results suggest that slightly over a quarter of the world's small-scale fishers fish on coral reefs, and half of all coral reef fishers are in Southeast Asia. Coral reefs evidently support the socio-economic well-being of numerous coastal communities. By quantifying the number of people who are employed as reef fishers, we provide decision-makers with an important input into planning for sustainable coral reef fisheries at the appropriate scale.

Energetic differences between bacterioplankton trophic groups and coral reef resistance.

Science.gov (United States)

McDole Somera, Tracey; Bailey, Barbara; Barott, Katie; Grasis, Juris; Hatay, Mark; Hilton, Brett J; Hisakawa, Nao; Nosrat, Bahador; Nulton, James; Silveira, Cynthia B; Sullivan, Chris; Brainard, Russell E; Rohwer, Forest

2016-04-27

Coral reefs are among the most productive and diverse marine ecosystems on the Earth. They are also particularly sensitive to changing energetic requirements by different trophic levels. Microbialization specifically refers to the increase in the energetic metabolic demands of microbes relative to macrobes and is significantly correlated with increasing human influence on coral reefs. In this study, metabolic theory of ecology is used to quantify the relative contributions of two broad bacterioplankton groups, autotrophs and heterotrophs, to energy flux on 27 Pacific coral reef ecosystems experiencing human impact to varying degrees. The effective activation energy required for photosynthesis is lower than the average energy of activation for the biochemical reactions of the Krebs cycle, and changes in the proportional abundance of these two groups can greatly affect rates of energy and materials cycling. We show that reef-water communities with a higher proportional abundance of microbial autotrophs expend more metabolic energy per gram of microbial biomass. Increased energy and materials flux through fast energy channels (i.e. water-column associated microbial autotrophs) may dampen the detrimental effects of increased heterotrophic loads (e.g. coral disease) on coral reef systems experiencing anthropogenic disturbance. © 2016 The Author(s).

The wicked problem of China's disappearing coral reefs.

Science.gov (United States)

Hughes, Terry P; Huang, Hui; Young, Matthew A L

2013-04-01

We examined the development of coral reef science and the policies, institutions, and governance frameworks for management of coral reefs in China in order to highlight the wicked problem of preserving reefs while simultaneously promoting human development and nation building. China and other sovereign states in the region are experiencing unprecedented economic expansion, rapid population growth, mass migration, widespread coastal development, and loss of habitat. We analyzed a large, fragmented literature on the condition of coral reefs in China and the disputed territories of the South China Sea. We found that coral abundance has declined by at least 80% over the past 30 years on coastal fringing reefs along the Chinese mainland and adjoining Hainan Island. On offshore atolls and archipelagos claimed by 6 countries in the South China Sea, coral cover has declined from an average of >60% to around 20% within the past 10-15 years. Climate change has affected these reefs far less than coastal development, pollution, overfishing, and destructive fishing practices. Ironically, these widespread declines in the condition of reefs are unfolding as China's research and reef-management capacity are rapidly expanding. Before the loss of corals becomes irreversible, governance of China's coastal reefs could be improved by increasing public awareness of declining ecosystem services, by providing financial support for training of reef scientists and managers, by improving monitoring of coral reef dynamics and condition to better inform policy development, and by enforcing existing regulations that could protect coral reefs. In the South China Sea, changes in policy and legal frameworks, refinement of governance structures, and cooperation among neighboring countries are urgently needed to develop cooperative management of contested offshore reefs. © 2012 Society for Conservation Biology.

Complexities and uncertainties in transitioning small-scale coral reef fisheries

Directory of Open Access Journals (Sweden)

Pierre eLeenhardt

2016-05-01

Full Text Available Coral reef fisheries support the development of local and national economies and are the basis of important cultural practices and worldviews. Transitioning economies, human development and environmental stress can harm this livelihood. Here we focus on a transitioning social-ecological system as case study (Moorea, French Polynesia. We review fishing practices and three decades of effort and landing estimates with the broader goal of informing management. Fishery activities in Moorea are quite challenging to quantify because of the diversity of gears used, the lack of centralized access points or markets, the high participation rates of the population in the fishery, and the overlapping cultural and economic motivations to catch fish. Compounding this challenging diversity, we lack a basic understanding of the complex interplay between the cultural, subsistence, and commercial use of Moorea's reefs. In Moorea, we found an order of magnitude gap between estimates of fishery yield produced by catch monitoring methods (~2 t km-2 year-1 and estimates produced using consumption or participatory socioeconomic consumer surveys (~24 t km-2 year-1. Several lines of evidence suggest reef resources may be overexploited and stakeholders have a diversity of opinions as to whether trends in the stocks are a cause for concern. The reefs, however, remain ecologically resilient. The relative health of the reef is striking given the socio-economic context. Moorea has a relatively high population density, a modern economic system linked into global flows of trade and travel, and the fishery has little remaining traditional or customary management. Other islands in the Pacific that continue to develop economically may have small-scale fisheries that increasingly resemble Moorea. Therefore, understanding Moorea's reef fisheries may provide insight into their future.

Coral reef bleaching: ecological perspectives

Science.gov (United States)

Glynn, P. W.

1993-03-01

Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt

Artificial reefs: “Attraction versus Production”

Directory of Open Access Journals (Sweden)

Eduardo Barros Fagundes Netto

2011-04-01

Full Text Available The production of fish is the most common reason for the construction and installation of an artificial reef. More recently, environmental concerns and conservation of biological resources have been instrumental to the formulation of new goals of the research. One of the issues to be resolved is the biological function of “attraction vs. production” as a result of the use of artificial reefs. The uncertainty as to the answer to the question whether the artificial reefs will or not benefit the development of fish stocks could be solved if the artificial reefs would be managed as marine protected areas.

Ecohydrodynamics of cold-water coral reefs: a case study of the Mingulay Reef Complex (western Scotland.

Directory of Open Access Journals (Sweden)

Juan Moreno Navas

Full Text Available Ecohydrodynamics investigates the hydrodynamic constraints on ecosystems across different temporal and spatial scales. Ecohydrodynamics play a pivotal role in the structure and functioning of marine ecosystems, however the lack of integrated complex flow models for deep-water ecosystems beyond the coastal zone prevents further synthesis in these settings. We present a hydrodynamic model for one of Earth's most biologically diverse deep-water ecosystems, cold-water coral reefs. The Mingulay Reef Complex (western Scotland is an inshore seascape of cold-water coral reefs formed by the scleractinian coral Lophelia pertusa. We applied single-image edge detection and composite front maps using satellite remote sensing, to detect oceanographic fronts and peaks of chlorophyll a values that likely affect food supply to corals and other suspension-feeding fauna. We also present a high resolution 3D ocean model to incorporate salient aspects of the regional and local oceanography. Model validation using in situ current speed, direction and sea elevation data confirmed the model's realistic representation of spatial and temporal aspects of circulation at the reef complex including a tidally driven current regime, eddies, and downwelling phenomena. This novel combination of 3D hydrodynamic modelling and remote sensing in deep-water ecosystems improves our understanding of the temporal and spatial scales of ecological processes occurring in marine systems. The modelled information has been integrated into a 3D GIS, providing a user interface for visualization and interrogation of results that allows wider ecological application of the model and that can provide valuable input for marine biodiversity and conservation applications.

Coral mortality in reefs: The cause and effect; A central concern for reef monitoring

Digital Repository Service at National Institute of Oceanography (India)

Raghukumar, C.

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Consequences of ecological, evolutionary and biogeochemical uncertainty for coral reef responses to climatic stress.

Science.gov (United States)

Mumby, Peter J; van Woesik, Robert

2014-05-19

Coral reefs are highly sensitive to the stress associated with greenhouse gas emissions, in particular ocean warming and acidification. While experiments show negative responses of most reef organisms to ocean warming, some autotrophs benefit from ocean acidification. Yet, we are uncertain of the response of coral reefs as systems. We begin by reviewing sources of uncertainty and complexity including the translation of physiological effects into demographic processes, indirect ecological interactions among species, the ability of coral reefs to modify their own chemistry, adaptation and trans-generational plasticity. We then incorporate these uncertainties into two simple qualitative models of a coral reef system under climate change. Some sources of uncertainty are far more problematic than others. Climate change is predicted to have an unambiguous negative effect on corals that is robust to several sources of uncertainty but sensitive to the degree of biogeochemical coupling between benthos and seawater. Macroalgal, zoanthid, and herbivorous fish populations are generally predicted to increase, but the ambiguity (confidence) of such predictions are sensitive to the source of uncertainty. For example, reversing the effect of climate-related stress on macroalgae from being positive to negative had no influence on system behaviour. By contrast, the system was highly sensitive to a change in the stress upon herbivorous fishes. Minor changes in competitive interactions had profound impacts on system behaviour, implying that the outcomes of mesocosm studies could be highly sensitive to the choice of taxa. We use our analysis to identify new hypotheses and suggest that the effects of climatic stress on coral reefs provide an exceptional opportunity to test emerging theories of ecological inheritance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Wave Dissipation on Low- to Super-Energy Coral Reefs

Science.gov (United States)

Harris, D. L.

2016-02-01

Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

Warm-water coral reefs and climate change.

Science.gov (United States)

Spalding, Mark D; Brown, Barbara E

2015-11-13

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak. Copyright © 2015, American Association for the Advancement of Science.

Temporal variation in development of ecosystem services from oyster reef restoration

Science.gov (United States)

LaPeyre, Megan K.; Humphries, Austin T.; Casas, Sandra M.; La Peyre, Jerome F.

2014-01-01

Restoration ecology relies heavily on ecosystem development theories that generally assume development of fully functioning natural systems over time, but often fail to identify the time-frame required for provision of desired functions, or acknowledge different pathways of functional development. In estuaries, a decline of overall habitat quality and functioning has led to significant efforts to restore critical ecosystem services, recently through the creation and restoration of oyster reefs. Oyster reef restoration generally occurs with goals of (1) increasing water quality via filtration through sustainable oyster recruitment, (2) stabilizing shorelines, and (3) creating and enhancing critical estuarine habitat for fish and invertebrates. We restored over 260 m2 of oyster reef habitat in coastal Louisiana and followed the development and provision of these ecosystem services from 2009 through 2012. Oysters recruited to reefs immediately, with densities of oysters greater than 75 mm exceeding 80 ind m−2 after 3 years, and provision of filtration rates of 1002 ± 187 L h−1 m−2; shoreline stabilization effects of the created reefs were minimal over the three years of monitoring, with some evidence of positive shoreline stabilization during higher wind/energy events only; increased nekton abundance of resident, but not larger transient fish was immediately measurable at the reefs, however, this failed to increase through time. Our results provide critical insights into the development trajectories of ecosystem services provided by restored oyster reefs, as well as the mechanisms mediating these changes. This is critical both ecologically to understand how and where a reef thrives, and for policy and management to guide decision-making related to oyster reef restoration and the crediting and accounting of ecosystem services.

Reduced Diversity and High Sponge Abundance on a Sedimented Indo-Pacific Reef System: Implications for Future Changes in Environmental Quality

Science.gov (United States)

Powell, Abigail; Smith, David J.; Hepburn, Leanne J.; Jones, Timothy; Berman, Jade; Jompa, Jamaluddin; Bell, James J.

2014-01-01

Although coral reef health across the globe is declining as a result of anthropogenic impacts, relatively little is known of how environmental variability influences reef organisms other than corals and fish. Sponges are an important component of coral reef fauna that perform many important functional roles and changes in their abundance and diversity as a result of environmental change has the potential to affect overall reef ecosystem functioning. In this study, we examined patterns of sponge biodiversity and abundance across a range of environments to assess the potential key drivers of differences in benthic community structure. We found that sponge assemblages were significantly different across the study sites, but were dominated by one species Lamellodysidea herbacea (42% of all sponges patches recorded) and that the differential rate of sediment deposition was the most important variable driving differences in abundance patterns. Lamellodysidea herbacea abundance was positively associated with sedimentation rates, while total sponge abundance excluding Lamellodysidea herbacea was negatively associated with rates of sedimentation. Overall variation in sponge assemblage composition was correlated with a number of variables although each variable explained only a small amount of the overall variation. Although sponge abundance remained similar across environments, diversity was negatively affected by sedimentation, with the most sedimented sites being dominated by a single sponge species. Our study shows how some sponge species are able to tolerate high levels of sediment and that any transition of coral reefs to more sedimented states may result in a shift to a low diversity sponge dominated system, which is likely to have subsequent effects on ecosystem functioning. PMID:24475041

Holocene reef accretion: southwest Molokai, Hawaii, U.S.A.

Science.gov (United States)

Engels, Mary S.; Fletcher, Charles H.; Field, Michael E.; Storlazzi, Curt D.; Grossman, Eric E.; Rooney, John J.B.; Conger, Christopher L.; Glenn, Craig

2004-01-01

Two reef systems off south Molokai, Hale O Lono and Hikauhi (separated by only 10 km), show strong and fundamental differences in modern ecosystem structure and Holocene accretion history that reflect the influence of wave-induced near-bed shear stresses on reef development in Hawaii. Both sites are exposed to similar impacts from south, Kona, and trade-wind swell. However, the Hale O Lono site is exposed to north swell and the Hikuahi site is not. As a result, the reef at Hale O Lono records no late Holocene net accretion while the reef at Hikauhi records consistent and robust accretion over late Holocene time. Analysis and dating of 24 cores from Hale O Lono and Hikauhi reveal the presence of five major lithofacies that reflect paleo-environmental conditions. In order of decreasing depositional energy they are: (1) coral-algal bindstone; (2) mixed skeletal rudstone; (3) massive coral framestone; (4) unconsolidated floatstone; and (5) branching coral framestone-bafflestone. At Hale O Lono, 10 cores document a backstepping reef ranging from ∼ 8,100 cal yr BP (offshore) to ∼ 4,800 cal yr BP (nearshore). A depauperate community of modern coral diminishes shoreward and seaward of ∼ 15 m depth due to wave energy, disrupted recruitment activities, and physical abrasion. Evidence suggests a change from conditions conducive to accretion during the early Holocene to conditions detrimental to accretion in the late Holocene. Reef structure at Hikauhi, reconstructed from 14 cores, reveals a thick, rapidly accreting and young reef (maximum age ∼ 900 cal yr BP). Living coral cover on this reef increases seaward with distance from the reef crest but terminates at a depth of ∼ 20 m where the reef ends in a large sand field. The primary limitation on vertical reef growth is accommodation space under wave base, not recruitment activities or energy conditions. Interpretations of cored lithofacies suggest that modern reef growth on the southwest corner of Molokai, and by

Processes Driving Natural Acidification of Western Pacific Coral Reef Waters

Science.gov (United States)

Shamberger, K. E.; Cohen, A. L.; Golbuu, Y.; McCorkle, D. C.; Lentz, S. J.; Barkley, H. C.

2013-12-01

Rising levels of atmospheric carbon dioxide (CO2) are acidifying the oceans, reducing seawater pH, aragonite saturation state (Ωar) and the availability of carbonate ions (CO32-) that calcifying organisms use to build coral reefs. Today's most extensive reef ecosystems are located where open ocean CO32- concentration ([CO32-]) and Ωar exceed 200 μmol kg-1 and 3.3, respectively. However, high rates of biogeochemical cycling and long residence times of water can result in carbonate chemistry conditions within coral reef systems that differ greatly from those of nearby open ocean waters. In the Palauan archipelago, water moving across the reef platform is altered by both biological and hydrographic processes that combine to produce seawater pH, Ωar, [CO32-] significantly lower than that of open ocean source water. Just inshore of the barrier reefs, average Ωar values are 0.2 to 0.3 and pH values are 0.02 to 0.03 lower than they are offshore, declining further as water moves across the back reef, lagoon and into the meandering bays and inlets that characterize the Rock Islands. In the Rock Island bays, coral communities inhabit seawater with average Ωar values of 2.7 or less, and as low as 1.9. Levels of Ωar as low as these are not predicted to occur in the western tropical Pacific open ocean until near the end of the century. Calcification by coral reef organisms is the principal biological process responsible for lowering Ωar and pH, accounting for 68 - 99 % of the difference in Ωar between offshore source water and reef water at our sites. However, in the Rock Island bays where Ωar is lowest, CO2 production by net respiration contributes between 17 - 30 % of the difference in Ωar between offshore source water and reef water. Furthermore, the residence time of seawater in the Rock Island bays is much longer than at the well flushed exposed sites, enabling calcification and respiration to drive Ωar to very low levels despite lower net ecosystem

Diet and condition of mesopredators on coral reefs in relation to shark abundance.

Directory of Open Access Journals (Sweden)

Shanta C Barley

Full Text Available Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a "natural experiment" to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other, our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.

Diet and condition of mesopredators on coral reefs in relation to shark abundance.

Science.gov (United States)

Barley, Shanta C; Meekan, Mark G; Meeuwig, Jessica J

2017-01-01

Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a "natural experiment" to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other), our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.

Quantifying uncertainty and resilience on coral reefs using a Bayesian approach

International Nuclear Information System (INIS)

Van Woesik, R

2013-01-01

Coral reefs are rapidly deteriorating globally. The contemporary management option favors managing for resilience to provide reefs with the capacity to tolerate human-induced disturbances. Yet resilience is most commonly defined as the capacity of a system to absorb disturbances without changing fundamental processes or functionality. Quantifying no change, or the uncertainty of a null hypothesis, is nonsensical using frequentist statistics, but is achievable using a Bayesian approach. This study outlines a practical Bayesian framework that quantifies the resilience of coral reefs using two inter-related models. The first model examines the functionality of coral reefs in the context of their reef-building capacity, whereas the second model examines the recovery rates of coral cover after disturbances. Quantifying intrinsic rates of increase in coral cover and habitat-specific, steady-state equilibria are useful proxies of resilience. A reduction in the intrinsic rate of increase following a disturbance, or the slowing of recovery over time, can be useful indicators of stress; a change in the steady-state equilibrium suggests a phase shift. Quantifying the uncertainty of key reef-building processes and recovery parameters, and comparing these parameters against benchmarks, facilitates the detection of loss of resilience and provides signals of imminent change. (letter)

Quantifying uncertainty and resilience on coral reefs using a Bayesian approach

Science.gov (United States)

van Woesik, R.

2013-12-01

Coral reefs are rapidly deteriorating globally. The contemporary management option favors managing for resilience to provide reefs with the capacity to tolerate human-induced disturbances. Yet resilience is most commonly defined as the capacity of a system to absorb disturbances without changing fundamental processes or functionality. Quantifying no change, or the uncertainty of a null hypothesis, is nonsensical using frequentist statistics, but is achievable using a Bayesian approach. This study outlines a practical Bayesian framework that quantifies the resilience of coral reefs using two inter-related models. The first model examines the functionality of coral reefs in the context of their reef-building capacity, whereas the second model examines the recovery rates of coral cover after disturbances. Quantifying intrinsic rates of increase in coral cover and habitat-specific, steady-state equilibria are useful proxies of resilience. A reduction in the intrinsic rate of increase following a disturbance, or the slowing of recovery over time, can be useful indicators of stress; a change in the steady-state equilibrium suggests a phase shift. Quantifying the uncertainty of key reef-building processes and recovery parameters, and comparing these parameters against benchmarks, facilitates the detection of loss of resilience and provides signals of imminent change.

Physics of coral reef systems in a shallow tidal embayment

NARCIS (Netherlands)

Hoitink, Antonius Johannes Franciscus

2003-01-01

Ongoing deforestation in the tropics involves higher river discharges and an increase of runoff, which has consequences to coastal ecosystems. The dispersal of fluvial sediment and freshwater by marine processes affects the environmental determinants of coral reefs near the coast, which include

Diverse coral communities in naturally acidified waters of a Western Pacific reef

Science.gov (United States)

Shamberger, Kathryn E. F.; Cohen, Anne L.; Golbuu, Yimnang; McCorkle, Daniel C.; Lentz, Steven J.; Barkley, Hannah C.

2014-01-01

Anthropogenic carbon dioxide emissions are acidifying the oceans, reducing the concentration of carbonate ions ([CO32-]) that calcifying organisms need to build and cement coral reefs. To date, studies of a handful of naturally acidified reef systems reveal depauperate communities, sometimes with reduced coral cover and calcification rates, consistent with results of laboratory-based studies. Here we report the existence of highly diverse, coral-dominated reef communities under chronically low pH and aragonite saturation state (Ωar). Biological and hydrographic processes change the chemistry of the seawater moving across the barrier reefs and into Palau's Rock Island bays, where levels of acidification approach those projected for the western tropical Pacific open ocean by 2100. Nevertheless, coral diversity, cover, and calcification rates are maintained across this natural acidification gradient. Identifying the combination of biological and environmental factors that enable these communities to persist could provide important insights into the future of coral reefs under anthropogenic acidification.

Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

Directory of Open Access Journals (Sweden)

Tom C L Bridge

Full Text Available High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2 plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

Science.gov (United States)

Bridge, Tom C L; Ferrari, Renata; Bryson, Mitch; Hovey, Renae; Figueira, Will F; Williams, Stefan B; Pizarro, Oscar; Harborne, Alastair R; Byrne, Maria

2014-01-01

High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2) plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies) prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

SIMAC: development and implementation of a coral reef monitoring network in Colombia.

Science.gov (United States)

Garzón-Ferreira, Jaime; Rodríguez-Ramírez, Alberto

2010-05-01

Significant coral reef decline has been observed in Colombia during the last three decades. However, due to the lack of monitoring activities, most of the information about health and changes was fragmentary or inadequate. To develop an expanded nation-wide reef-monitoring program, in 1998 INVEMAR (Instituto de Investigaciones Marinas y Costeras: "Colombian Institute of Marine and Coastal Research") designed and implemented SIMAC (Sistema Nacional de Monitorco de Arrecifes Coralinos en Colombia: "National Monitoring System of Coral Reefs in Colombia") with the participation of other institutions. By the end of 2003 the SIMAC network reached more than twice its initial size, covering ten reef areas (seven in the Caribbean and three in the Pacific), 63 reef sites and 263 permanent transects. SIMAC monitoring continued without interruption until 2008 and should persist in the long-term. The SIMAC has a large database and consists basically of water quality measurements (temperature, salinity, turbidity) and a yearly estimation of benthic reef cover, coral disease prevalence, gorgonian density, abundance of important mobile invertebrates, fish diversity and abundance of important fish species. A methods manual is available in the Internet. Data and results of SIMAC have been widely circulated through a summary report published annually since 2000 for the Colombian environmental agencies and the general public, as well as numerous national and international scientific papers and presentations at meetings. SIMAC information has contributed to support regional and global reef monitoring networks and databases (i.e. CARICOMP, GCRMN, ReefBase).

Multiscale approach reveals that Cloudina aggregates are detritus and not in situ reef constructions

Science.gov (United States)

Mehra, Akshay; Maloof, Adam

2018-03-01

The earliest metazoans capable of biomineralization appeared during the late Ediacaran Period (635–541 Ma) in strata associated with shallow water microbial reefs. It has been suggested that some Ediacaran microbial reefs were dominated (and possibly built) by an abundant and globally distributed tubular organism known as Cloudina. If true, this interpretation implies that metazoan framework reef building—a complex behavior that is responsible for some of the largest bioconstructions and most diverse environments in modern oceans—emerged much earlier than previously thought. Here, we present 3D reconstructions of Cloudina populations, produced using an automated serial grinding and imaging system coupled with a recently developed neural network image classifier. Our reconstructions show that Cloudina aggregates are composed of transported remains while detailed field observations demonstrate that the studied reef outcrops contain only detrital Cloudina buildups, suggesting that Cloudina played a minor role in Ediacaran reef systems. These techniques have wide applicability to problems that require 3D reconstructions where physical separation is impossible and a lack of density contrast precludes tomographic imaging techniques.

Mapping Oyster Reef Habitats in Mobile Bay

Science.gov (United States)

Bolte, Danielle

2011-01-01

Oyster reefs around the world are declining rapidly, and although they haven t received as much attention as coral reefs, they are just as important to their local ecosystems and economies. Oyster reefs provide habitats for many species of fish, invertebrates, and crustaceans, as well as the next generations of oysters. Oysters are also harvested from many of these reefs and are an important segment of many local economies, including that of Mobile Bay, where oysters rank in the top five commercial marine species both by landed weight and by dollar value. Although the remaining Mobile Bay oyster reefs are some of the least degraded in the world, projected climate change could have dramatic effects on the health of these important ecosystems. The viability of oyster reefs depends on water depth and temperature, appropriate pH and salinity levels, and the amount of dissolved oxygen in the water. Projected increases in sea level, changes in precipitation and runoff patterns, and changes in pH resulting from increases in the amount of carbon dioxide dissolved in the oceans could all affect the viability of oyster reefs in the future. Human activities such as dredging and unsustainable harvesting practices are also adversely impacting the oyster reefs. Fortunately, several projects are already under way to help rebuild or support existing or previously existing oyster reefs. The success of these projects will depend on the local effects of climate change on the current and potential habitats and man s ability to recognize and halt unsustainable harvesting practices. As the extent and health of the reefs changes, it will have impacts on the Mobile Bay ecosystem and economy, changing the resources available to the people who live there and to the rest of the country, since Mobile Bay is an important national source of seafood. This project identified potential climate change impacts on the oyster reefs of Mobile Bay, including the possible addition of newly viable

Not finding Nemo: limited reef-scale retention in a coral reef fish

KAUST Repository

Nanninga, Gerrit B.

2015-02-03

The spatial scale of larval dispersal is a key predictor of marine metapopulation dynamics and an important factor in the design of reserve networks. Over the past 15 yr, studies of larval dispersal in coral reef fishes have generated accumulating evidence of consistently high levels of self-recruitment and local retention at various spatial scales. These findings have, to a certain degree, created a paradigm shift toward the perception that large fractions of locally produced recruitment may be the rule rather than the exception. Here we examined the degree of localized settlement in an anemonefish, Amphiprion bicinctus, at a solitary coral reef in the central Red Sea by integrating estimates of self-recruitment obtained from genetic parentage analysis with predictions of local retention derived from a biophysical dispersal model parameterized with real-time physical forcing. Self-recruitment at the reef scale (c. 0.7 km2) was virtually absent during two consecutive January spawning events (1.4 % in 2012 and 0 % in 2013). Predicted levels of local retention at the reef scale varied temporally, but were comparatively low for both simulations (7 % in 2012 and 0 % in 2013). At the same time, the spatial scale of simulated dispersal was restricted to approximately 20 km from the source. Model predictions of reef-scale larval retention were highly dependent on biological parameters, underlining the need for further empirical validations of larval traits over a range of species. Overall, our findings present an urgent caution when assuming the potential for self-replenishment in small marine reserves.

Water-mass dynamics of an Arctic cold-water coral reef: First results from a new ocean observatory system

Science.gov (United States)

Flögel, Sascha; Karstensen, Johannes; Linke, Peter; Pfannkuche, Olaf; Ashastina, Kseniia; Dullo, Christian

2015-04-01

Cold-water coral reefs occur at various sites along the European continental margin, like in the Mediterranean Sea, on carbonate mounds West off Ireland, or at shallower depths between 100 and 350 m on the Norwegian shelf. Their occurrence is related to different physical parameters like temperature, salinity, seawater density, dissolved oxygen, and to other environmental parameters such as internal wave activity, nutrient supply, strong currents, which keep sediment input low, etc. Here, we present first results from a long-term observation in one of the nortnermost cold-water coral reefs at 70.5°N - the Stjernsund in northern Norway. The Stjernsund is a 30 km long and up to 3.5 km wide sound connecting the open North Atlantic with a fjord system. A deep-seated SW-NE oriented morainic sill with varying depths (203-236 m) splits the more than 400 m deep sound into two troughs. Living Lophelia pertusa dominated reef complexes occur on the NW slope between 235 and 305 m water depths and on the SE slope between 245 and 280 m. To investigate the dominating physical and biogeochemical boundary conditions a new modular seafloor observatory, MoLab, consisting of five sea-floor observatories and two moorings was deployed for 100 days during the summer of 2012. The various lander systems and moorimgs were equipped with sensors to measure current velocities and directions, temperature, salinity, pressure, pH, turbidity, fluorescence, oxygen concentration and saturation. Results showed that near-bottom salinities, temperature and current velocities are dominated by a semi-diurnal tidal forcing (pronounced M2 constituent), which cause vertical water mass movements of up to 100 m. These influence large parts of the living reef. Closer examination revealed overturning cells on the south-eastern slope of the sill during high tide, when Atlantic Water flows over the sill. The appearance of living cold-water corals is limited to a density envelope of sigma-theta=27.25-27.50 kg/m-3

Coral reefs: threats and conservation in an era of global change.

Science.gov (United States)

Riegl, Bernhard; Bruckner, Andy; Coles, Steve L; Renaud, Philip; Dodge, Richard E

2009-04-01

Coral reefs are iconic, threatened ecosystems that have been in existence for approximately 500 million years, yet their continued ecological persistence seems doubtful at present. Anthropogenic modification of chemical and physical atmospheric dynamics that cause coral death by bleaching and newly emergent diseases due to increased heat and irradiation, as well as decline in calcification caused by ocean acidification due to increased CO(2), are the most important large-scale threats. On more local scales, overfishing and destructive fisheries, coastal construction, nutrient enrichment, increased runoff and sedimentation, and the introduction of nonindigenous invasive species have caused phase shifts away from corals. Already approximately 20% of the world's reefs are lost and approximately 26% are under imminent threat. Conservation science of coral reefs is well advanced, but its practical application has often been lagging. Societal priorites, economic pressures, and legal/administrative systems of many countries are more prone to destroy rather than conserve coral-reef ecosystems. Nevertheless, many examples of successful conservation exist from the national level to community-enforced local action. When effectively managed, protected areas have contributed to regeneration of coral reefs and stocks of associated marine resources. Local communities often support coral-reef conservation in order to raise income potential associated with tourism and/or improved resource levels. Coral reefs create an annual income in S-Florida alone of over $4 billion. Thus, no conflict between development, societal welfare, and coral-reef conservation needs to exist. Despite growing threats, it is not too late for decisive action to protect and save these economically and ecologically high-value ecosystems. Conservation science plays a critical role in designing effective strategies.

Pacific Reef Assessment and Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structures (ARMS) Deployed at Coral Reef Sites across the U.S. Pacific from 2008 to 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — To support a long-term program for sustainable management and conservation of coral reef ecosystems, from 2008, Autonomous Reef Monitoring Structures (ARMS) have...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Pacific Remote Island Areas from 2011 to 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

Fouling assemblages associated with estuarine artificial reefs in new South Wales, Australia

Directory of Open Access Journals (Sweden)

Rob Mckenzie

2011-01-01

Full Text Available Previous studies examining the dynamics of succession on artificial reefs have predominantly focussed on fish communities and largely ignored the role of fouling assemblages in explaining the patterns of community structure associated with artificial reefs. The objective of this study was to record the development of epibiotic assemblages on three "design specific" (Reef Ball® estuarine artificial reefs systems located in Lake Macquarie, Botany Bay and St Georges Basin in New South Wales, Australia. Recruitment to the artificial reefs was relatively rapid with the majority of taxa identified over the two-year study period observed within the first year post-deployment. The artificial reefs in Lake Macquarie and St Georges Basin were characterised by low diversity with four and nine taxa recorded respectively in contrast to the sixteen taxa observed on the Botany Bay reefs. Results indicated no significant differences in percentage cover of taxa among reefs in either St Georges Basin or Lake Macquarie. In contrast, comparisons between individual Botany Bay reefs identified significant differences in the percentage cover of species between artificial reefs. Analysis of assemblage structure with reef age indicated discrete patterns among estuaries with an overall reduction in the percentage cover of filamentous turfing algae (FTA identified for all reef systems with an increase in reef age. Variations in environmental and physical conditions (turbidity, water flow, wave action and proximity to naturally occurring reef may have contributed to the observed differences in fouling assemblages between estuaries and between artificial reefs within Botany Bay.Estudos prévios que examinaram a dinâmica de sucessão em recifes artificiais foram focalizados nas comunidades de peixes, e sempre ignoraram o papel exercido pelos organismos incrustantes sobre a estruturação das comunidades associadas aos recifes artificiais. O presente estudo tem por objetivo

Transport of Calcareous Fragments by Reef Fishes.

Science.gov (United States)

Bardach, J E

1961-01-13

The weight of sand, coral scrapings, algal fragments, and other calcareous materials which pass through the intestines of reef fishes was calculated on a hectare-per-year basis. It was found that browsing omnivorous reef fishes which rely, in part, on a plant diet ingested and redeposited at least 2300 kg of such material on a 1-hectare study reef near Bermuda. Reasons are presented why this estimate, certainly in order of magnitude, should be applicable to coral reefs in general.

A trophic model of fringing coral reefs in Nanwan Bay, southern Taiwan suggests overfishing.

Science.gov (United States)

Liu, Pi-Jen; Shao, Kwang-Tsao; Jan, Rong-Quen; Fan, Tung-Yung; Wong, Saou-Lien; Hwang, Jiang-Shiou; Chen, Jen-Ping; Chen, Chung-Chi; Lin, Hsing-Juh

2009-09-01

Several coral reefs of Nanwan Bay, Taiwan have recently undergone shifts to macroalgal or sea anemone dominance. Thus, a mass-balance trophic model was constructed to analyze the structure and functioning of the food web. The fringing reef model was comprised of 18 compartments, with the highest trophic level of 3.45 for piscivorous fish. Comparative analyses with other reef models demonstrated that Nanwan Bay was similar to reefs with high fishery catches. While coral biomass was not lower, fish biomass was lower than those of reefs with high catches. Consequently, the sums of consumption and respiratory flows and total system throughput were also decreased. The Nanwan Bay model potentially suggests an overfished status in which the mean trophic level of the catch, matter cycling, and trophic transfer efficiency are extremely reduced.

National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in American Samoa from Water Samples collected since 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and...

Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape

Science.gov (United States)

Eggertsen, L.; Ferreira, C. E. L.; Fontoura, L.; Kautsky, N.; Gullström, M.; Berkström, C.

2017-09-01

Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.

Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico

OpenAIRE

Gonzalez-Gandara, C.; Perez-Diaz, E.; Santos-Rodriguez, L.; Arias-Gonzalez, J.E.

2003-01-01

Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000.

Lake sturgeon response to a spawning reef constructed in the Detroit river

Science.gov (United States)

Roseman, Edward F.; Manny, B.; Boase, J.; Child, M.; Kennedy, G.; Craig, J.; Soper, K.; Drouin, R.

2011-01-01

Prior to the First World War, the bi-national Detroit River provided vast areas of functional fish spawning and nursery habitat. However, ongoing conflicting human uses of these waters for activities such as waste disposal, water withdrawals, shoreline development, shipping, recreation, and fishing have altered many of the chemical, physical, and biological processes of the Detroit River. Of particular interest and concern to resource managers and stakeholders is the significant loss and impairment of fish spawning and nursery habitat that led to the decline in abundance of most fish species using this ecosystem. Lake sturgeon (Acipenser fulvescens) populations for example, were nearly extirpated by the middle of the 20th century, leaving only a small fraction of their former population. Fisheries managers recognized that the loss of suitable fish spawning habitat is a limiting factor in lake sturgeon population rehabilitation in the Detroit River. In efforts to remediate this beneficial water use impairment, a reef consisting of a mixture of natural rock and limestone was constructed at the upstream end of Fighting Island in 2008. This paper focuses on the response by lake sturgeon to the different replicates of suitable natural materials used to construct the fish spawning habitat at Fighting Island in the Detroit River. Pre-construction fisheries assessment during 2006–2008 showed that along with the presence of adult lake sturgeon, spawning conditions were favorable. However, no eggs were found in assessments conducted prior to reef construction. The 3300 m2 Fighting Island reef was placed at the upstream end of the island in October of 2008. The construction design included 12 spawning beds of three replicates each consisting of either round rock, small or large (shot-rock) diameter limestone or a mixture thereof. An observed response by spawning lake sturgeon occurred the following year when spawning-ready adults (ripe), viable eggs, and larvae were

How models can support ecosystem-based management of coral reefs

Science.gov (United States)

Weijerman, Mariska; Fulton, Elizabeth A.; Janssen, Annette B. G.; Kuiper, Jan J.; Leemans, Rik; Robson, Barbara J.; van de Leemput, Ingrid A.; Mooij, Wolf M.

2015-11-01

Despite the importance of coral reef ecosystems to the social and economic welfare of coastal communities, the condition of these marine ecosystems have generally degraded over the past decades. With an increased knowledge of coral reef ecosystem processes and a rise in computer power, dynamic models are useful tools in assessing the synergistic effects of local and global stressors on ecosystem functions. We review representative approaches for dynamically modeling coral reef ecosystems and categorize them as minimal, intermediate and complex models. The categorization was based on the leading principle for model development and their level of realism and process detail. This review aims to improve the knowledge of concurrent approaches in coral reef ecosystem modeling and highlights the importance of choosing an appropriate approach based on the type of question(s) to be answered. We contend that minimal and intermediate models are generally valuable tools to assess the response of key states to main stressors and, hence, contribute to understanding ecological surprises. As has been shown in freshwater resources management, insight into these conceptual relations profoundly influences how natural resource managers perceive their systems and how they manage ecosystem recovery. We argue that adaptive resource management requires integrated thinking and decision support, which demands a diversity of modeling approaches. Integration can be achieved through complimentary use of models or through integrated models that systemically combine all relevant aspects in one model. Such whole-of-system models can be useful tools for quantitatively evaluating scenarios. These models allow an assessment of the interactive effects of multiple stressors on various, potentially conflicting, management objectives. All models simplify reality and, as such, have their weaknesses. While minimal models lack multidimensionality, system models are likely difficult to interpret as they

Assessing cryptic reef diversity of colonizing marine invertebrates using Autonomous Reef Monitoring Structures (ARMS) deployed at coral reef sites in Batangas, Philippines from 2012-03-12 to 2015-05-31 (NCEI Accession 0162829)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used by the NOAA Coral Reef Ecosystem Program (CREP) to assess and monitor cryptic reef diversity across the...

The continuing decline of coral reefs in Bahrain.

Science.gov (United States)

Burt, John A; Al-Khalifa, Khalifa; Khalaf, Ebtesam; Alshuwaikh, Bassem; Abdulwahab, Ahmed

2013-07-30

Historically coral reefs of Bahrain were among the most extensive in the southern basin of the Arabian Gulf. However, Bahrain's reefs have undergone significant decline in the last four decades as a result of large-scale coastal development and elevated sea surface temperature events. Here we quantitatively surveyed six sites including most major coral reef habitats around Bahrain and a reef located 72 km offshore. Fleshy and turf algae now dominate Bahrain's reefs (mean: 72% cover), and live coral cover is low (mean: 5.1%). Formerly dominant Acropora were not observed at any site. The offshore Bulthama reef had the highest coral cover (16.3%) and species richness (22 of the 23 species observed, 13 of which were exclusive to this site). All reefs for which recent and historical data are available show continued degradation, and it is unlikely that they will recover under continuing coastal development and projected climate change impacts. Copyright © 2012 Elsevier Ltd. All rights reserved.

Status and review of health of Indian coral reefs

Digital Repository Service at National Institute of Oceanography (India)

Rajan, R.; Satyanarayan, C.; Raghunathan, C.; Koya, S.S.; Ravindran, J.; Manikandan, B.; Venkataraman, K.

Status of reef health incorporating species-wise cover of scleractinians has been reported covering 61 stations in 29 reef locations of the four major reef regions in India as of March 2011, alongside a review of available reef health data since...

SIMAC: Development and implementation of a coral reef monitoring network in Colombia

Directory of Open Access Journals (Sweden)

Jaime Garzón-Ferreira

2010-05-01

Full Text Available Significant coral reef decline has been observed in Colombia during the last three decades. However, due to the lack of monitoring activities, most of the information about health and changes was fragmentary or inadequate. To develop an expanded nation-wide reef-monitoring program, in 1998 INVEMAR (Instituto de Investigaciones Marinas y Costeras: "Colombian Institute of Marine and Coastal Research" designed and implemented SIMAC (Sistema Nacional de Monitoreo de Arrecifes Coralinos en Colombia: "National Monitoring System of Coral Reefs in Colombia" with the participation of other institutions. By the end of 2003 the SIMAC network reached more than twice its initial size, covering ten reef areas (seven in the Caribbean and three in the Pacific, 63 reef sites and 263 permanent transects. SIMAC monitoring continued without interruption until 2008 and should persist in the long-term. The SIMAC has a large database and consists basically of water quality measurements (temperature, salinity, turbidity and a yearly estimation of benthic reef cover, coral disease prevalence, gorgonian density, abundance of important mobile invertebrates, fish diversity and abundance of important fish species. A methods manual is available in the internet. Data and results of SIMAC have been widely circulated through a summary report published annually since 2000 for the Colombian environmental agencies and the general public, as well as numerous national and international scientific papers and presentations at meetings. SIMAC information has contributed to support regional and global reef monitoring networks and databases (i.e. CARICOMP, GCRMN, ReefBase. Rev. Biol. Trop. 58 (Suppl. 1: 67-80. Epub 2010 May 01.

Reduced diversity and high sponge abundance on a sedimented Indo-Pacific reef system: implications for future changes in environmental quality.

Directory of Open Access Journals (Sweden)

Abigail Powell

Full Text Available Although coral reef health across the globe is declining as a result of anthropogenic impacts, relatively little is known of how environmental variability influences reef organisms other than corals and fish. Sponges are an important component of coral reef fauna that perform many important functional roles and changes in their abundance and diversity as a result of environmental change has the potential to affect overall reef ecosystem functioning. In this study, we examined patterns of sponge biodiversity and abundance across a range of environments to assess the potential key drivers of differences in benthic community structure. We found that sponge assemblages were significantly different across the study sites, but were dominated by one species Lamellodysidea herbacea (42% of all sponges patches recorded and that the differential rate of sediment deposition was the most important variable driving differences in abundance patterns. Lamellodysidea herbacea abundance was positively associated with sedimentation rates, while total sponge abundance excluding Lamellodysidea herbacea was negatively associated with rates of sedimentation. Overall variation in sponge assemblage composition was correlated with a number of variables although each variable explained only a small amount of the overall variation. Although sponge abundance remained similar across environments, diversity was negatively affected by sedimentation, with the most sedimented sites being dominated by a single sponge species. Our study shows how some sponge species are able to tolerate high levels of sediment and that any transition of coral reefs to more sedimented states may result in a shift to a low diversity sponge dominated system, which is likely to have subsequent effects on ecosystem functioning.

Deposition of calcium carbonate into postglacial reefs: a test on a 'coral reef hypothesis'. Kohyoki no sangosho eno tansan calcium taiseki sokudo

Energy Technology Data Exchange (ETDEWEB)

Kayanne, H [Geological Survey of Japan, Tsukuba (Japan)

1993-06-15

This paper describes the following matters on changes in rates of deposition of calcium carbonate into postglacial coral reefs: Estimation was made on change in CaCO3 deposition in four coral reefs the data of which relating to all cross sections down to reef base have been acquired by drilling; the main deposition periods in the coral reefs formed in the postglacial period were five to six thousand years ago; the maximum deposition rate is estimated to be 2.7 [times] 10[sup 14] gC per one thousand years under an assumption that the total deposition amount in postglacial coral reefs is 1.2 [times] 10[sup 18] gC (converted to carbon amount); the recent deposition rate is (1/7.5) that of the former rate; from information obtained on submerged coral reefs, deposition amounts in coral reefs before 10,000 years ago are judged to have been smaller than those thereafter; and the above knowledges do not support the 'coral reef hypothesis' by Berger et al. that deposition of calcium carbonate into postglacial coral reefs has occurred from 15,000 years ago to 10,000 years ago. 30 refs., 2 figs.

Functionally diverse reef-fish communities ameliorate coral disease.

Science.gov (United States)

Raymundo, Laurie J; Halford, Andrew R; Maypa, Aileen P; Kerr, Alexander M

2009-10-06

Coral reefs, the most diverse of marine ecosystems, currently experience unprecedented levels of degradation. Diseases are now recognized as a major cause of mortality in reef-forming corals and are complicit in phase shifts of reef ecosystems to algal-dominated states worldwide. Even so, factors contributing to disease occurrence, spread, and impact remain poorly understood. Ecosystem resilience has been linked to the conservation of functional diversity, whereas overfishing reduces functional diversity through cascading, top-down effects. Hence, we tested the hypothesis that reefs with trophically diverse reef fish communities have less coral disease than overfished reefs. We surveyed reefs across the central Philippines, including well-managed marine protected areas (MPAs), and found that disease prevalence was significantly negatively correlated with fish taxonomic diversity. Further, MPAs had significantly higher fish diversity and less disease than unprotected areas. We subsequently investigated potential links between coral disease and the trophic components of fish diversity, finding that only the density of coral-feeding chaetodontid butterflyfishes, seldom targeted by fishers, was positively associated with disease prevalence. These previously uncharacterized results are supported by a second large-scale dataset from the Great Barrier Reef. We hypothesize that members of the charismatic reef-fish family Chaetodontidae are major vectors of coral disease by virtue of their trophic specialization on hard corals and their ecological release in overfished areas, particularly outside MPAs.

Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae

NARCIS (Netherlands)

Barott, K.L.; Rodriguez-Mueller, B; Youle, M.; Marhaver, K.L.; Vermeij, M.J.A.; Smith, J.E.; Rohwer, F.L.

2012-01-01

Competition between reef-building corals and benthic algae is of key importance for reef dynamics. These interactions occur on many spatial scales, ranging from chemical to regional. Using microprobes, 16S rDNA pyrosequencing and underwater surveys, we examined the interactions between the

Benthic meiofaunal community response to the cascading effects of herbivory within an algal halo system of the Great Barrier Reef.

Science.gov (United States)

Ollivier, Quinn R; Hammill, Edward; Booth, David J; Madin, Elizabeth M P; Hinchliffe, Charles; Harborne, Alastair R; Lovelock, Catherine E; Macreadie, Peter I; Atwood, Trisha B

2018-01-01

Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the 'grazing halos' of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways.

Diving down the reefs? Intensive diving tourism threatens the reefs of the northern Red Sea.

Science.gov (United States)

Hasler, Harald; Ott, Jörg A

2008-10-01

Intensive recreational SCUBA diving threatens coral reef ecosystems. The reefs at Dahab, South Sinai, Egypt, are among the world's most dived (>30,000 dives y(-1)). We compared frequently dived sites to sites with no or little diving. Benthic communities and condition of corals were examined by the point intercept sampling method in the reef crest zone (3m) and reef slope zone (12 m). Additionally, the abundance of corallivorous and herbivorous fish was estimated based on the visual census method. Sediments traps recorded the sedimentation rates caused by SCUBA divers. Zones subject to intensive SCUBA diving showed a significantly higher number of broken and damaged corals and significantly lower coral cover. Reef crest coral communities were significantly more affected than those of the reef slope: 95% of the broken colonies were branching ones. No effect of diving on the abundance of corallivorous and herbivorous fish was evident. At heavily used dive sites, diver-related sedimentation rates significantly decreased with increasing distance from the entrance, indicating poor buoyancy regulation at the initial phase of the dive. The results show a high negative impact of current SCUBA diving intensities on coral communities and coral condition. Corallivorous and herbivorous fishes are apparently not yet affected, but are endangered if coral cover decline continues. Reducing the number of dives per year, ecologically sustainable dive plans for individual sites, and reinforcing the environmental education of both dive guides and recreational divers are essential to conserve the ecological and the aesthetic qualities of these dive sites.

75 FR 48934 - Coral Reef Conservation Program Implementation Guidelines

Science.gov (United States)

2010-08-12

...-01] RIN 0648-ZC19 Coral Reef Conservation Program Implementation Guidelines AGENCY: National Oceanic... Guidelines (Guidelines) for the Coral Reef Conservation Program (CRCP or Program) under the Coral Reef... assistance for coral reef conservation projects under the Act. NOAA revised the Implementation Guidelines for...

Pattern and intensity of human impact on coral reefs depend on depth along the reef profile and on the descriptor adopted

Science.gov (United States)

Nepote, Ettore; Bianchi, Carlo Nike; Chiantore, Mariachiara; Morri, Carla; Montefalcone, Monica

2016-09-01

Coral reefs are threatened by multiple global and local disturbances. The Maldives, already heavily hit by the 1998 mass bleaching event, are currently affected also by growing tourism and coastal development that may add to global impacts. Most of the studies investigating effects of local disturbances on coral reefs assessed the response of communities along a horizontal distance from the impact source. This study investigated the status of a Maldivian coral reef around an island where an international touristic airport has been recently (2009-2011) built, at different depths along the reef profile (5-20 m depth) and considering the change in the percentage of cover of five different non-taxonomic descriptors assessed through underwater visual surveys: hard corals, soft corals, other invertebrates, macroalgae and abiotic attributes. Eight reefs in areas not affected by any coastal development were used as controls and showed a reduction of hard coral cover and an increase of abiotic attributes (i.e. sand, rock, coral rubble) at the impacted reef. However, hard coral cover, the most widely used descriptor of coral reef health, was not sufficient on its own to detect subtle indirect effects that occurred down the reef profile. Selecting an array of descriptors and considering different depths, where corals may find a refuge from climate impacts, could guide the efforts of minimising local human pressures on coral reefs.

Preliminary assessment of bioengineered fringing shoreline reefs in Grand Isle and Breton Sound, Louisiana

Science.gov (United States)

La Peyre, Megan K.; Schwarting, Lindsay; Miller, Shea

2013-01-01

data at two of the sites, and differences in reef placement between sites, however, it is difficult to draw any conclusions. Longer-term data collection and further analyses comparing reef placement; local wind, wave energy, sediment transport processes; and local bathymetry may help in parameterizing sites where fringing reefs may be most beneficial for shoreline protection. In addition to basic reef sustainability and shoreline stabilization, we measured both water quality parameters and nekton abundances around the newly created reefs and adjacent reference sites. Within the timeframe of monitoring, no effect of reefs on water quality was detected at any site. Given that water quality effects are hypothesized to result from the filtration activities of bivalves, and reefs either failed to recruit (settlement plus survival to > 50 mm) or successfully recruited but only had a couple months of growth prior to this report, it was not expected that an effect would be detectable in this timeframe. Nekton such as blue crab, gulf menhaden, and anchovies were found to be more abundant on the reefs; larger, more transient species were not found to be affected by reef presence. Future work examining smaller organisms and juveniles, including more explicit studies examining why and how these organisms preferentially use oyster reefs, would be useful in the design of other bioengineered reefs and help in understanding the role of the reefs in supporting the nekton community. It is clear from the initial work that ensuring correct site selection by better understanding what local site factors influence oyster populations is key to establishing successful living shoreline reefs. Ultimately, the success of the reefs in providing any ecosystem service relies on their ability to build a viable oyster population that is self-sustaining over the long term. As many of the ecosystem processes hypothesized to result from reefs develop over the long term (4–6 years), some level of

Coral Reef and Coastal Ecosystems Decision Support Workshop April 27-29, 2010 Caribbean Coral Reef Institute, La Parguera, Puerto Rico

Science.gov (United States)

The U.S. Environmental Protection Agency (EPA) and Caribbean Coral Reef Institute (CCRI) hosted a Coral Reef and Coastal Ecosystems Decision Support Workshop on April 27-28, 2010 at the Caribbean Coral Reef Institute in La Parguera, Puerto Rico. Forty-three participants, includin...

Re-creating missing population baselines for Pacific reef sharks.

Science.gov (United States)

Nadon, Marc O; Baum, Julia K; Williams, Ivor D; McPherson, Jana M; Zgliczynski, Brian J; Richards, Benjamin L; Schroeder, Robert E; Brainard, Russell E

2012-06-01

Sharks and other large predators are scarce on most coral reefs, but studies of their historical ecology provide qualitative evidence that predators were once numerous in these ecosystems. Quantifying density of sharks in the absence of humans (baseline) is, however, hindered by a paucity of pertinent time-series data. Recently researchers have used underwater visual surveys, primarily of limited spatial extent or nonstandard design, to infer negative associations between reef shark abundance and human populations. We analyzed data from 1607 towed-diver surveys (>1 ha transects surveyed by observers towed behind a boat) conducted at 46 reefs in the central-western Pacific Ocean, reefs that included some of the world's most pristine coral reefs. Estimates of shark density from towed-diver surveys were substantially lower (sharks observed in towed-diver surveys and human population in models that accounted for the influence of oceanic primary productivity, sea surface temperature, reef area, and reef physical complexity. We used these models to estimate the density of sharks in the absence of humans. Densities of gray reef sharks (Carcharhinus amblyrhynchos), whitetip reef sharks (Triaenodon obesus), and the group "all reef sharks" increased substantially as human population decreased and as primary productivity and minimum sea surface temperature (or reef area, which was highly correlated with temperature) increased. Simulated baseline densities of reef sharks under the absence of humans were 1.1-2.4/ha for the main Hawaiian Islands, 1.2-2.4/ha for inhabited islands of American Samoa, and 0.9-2.1/ha for inhabited islands in the Mariana Archipelago, which suggests that density of reef sharks has declined to 3-10% of baseline levels in these areas. ©2012 Society for Conservation Biology No claim to original US government works.

Coral Reef Coverage Percentage on Binor Paiton-Probolinggo Seashore

Directory of Open Access Journals (Sweden)

Dwi Budi Wiyanto

2016-01-01

Full Text Available The coral reef damage in Probolinggo region was expected to be caused by several factors. The first one comes from its society that exploits fishery by using cyanide toxin and bomb. The second one goes to the extraction of coral reef, which is used as decoration or construction materials. The other factor is likely caused by the existence of large industry on the seashore, such as Electric Steam Power Plant (PLTU Paiton and others alike. Related to the development of coral reef ecosystem, availability of an accurate data is crucially needed to support the manner of future policy, so the research of coral reef coverage percentage needs to be conducted continuously. The aim of this research is to collect biological data of coral reef and to identify coral reef coverage percentage in the effort of constructing coral reef condition basic data on Binor, Paiton, and Probolinggo regency seashore. The method used in this research is Line Intercept Transect (LIT method. LIT method is a method that used to decide benthic community on coral reef based on percentage growth, and to take note of benthic quantity along transect line. Percentage of living coral coverage in 3 meters depth on this Binor Paiton seashore that may be categorized in a good condition is 57,65%. While the rest are dead coral that is only 1,45%, other life form in 23,2%, and non-life form in 17,7%. A good condition of coral reef is caused by coral reef transplantation on the seashore, so this coral reef is dominated by Acropora Branching. On the other hand, Mortality Index (IM of coral reef resulted in 24,5%. The result from observation and calculation of coral reef is dominated by Hard Coral in Acropora Branching (ACB with coral reef coverage percentage of 39%, Coral Massive (CM with coral reef coverage percentage of 2,85%, Coral Foliose (CF with coral reef coverage percentage of 1,6%, and Coral Mushroom (CRM with coral reef coverage percentage of 8,5%. Observation in 10 meters depth

Coral Reef Coverage Percentage on Binor Paiton-Probolinggo Seashore

Directory of Open Access Journals (Sweden)

Dwi Budi Wiyanto

2016-02-01

Full Text Available The coral reef damage in Probolinggo region was expected to be caused by several factors. The first one comes from its society that exploits fishery by using cyanide toxin and bomb. The second one goes to the extraction of coral reef, which is used as decoration or construction materials. The other factor is likely caused by the existence of large industry on the seashore, such as Electric Steam Power Plant (PLTU Paiton and others alike. Related to the development of coral reef ecosystem, availability of an accurate data is crucially needed to support the manner of future policy, so the research of coral reef coverage percentage needs to be conducted continuously. The aim of this research is to collect biological data of coral reef and to identify coral reef coverage percentage in the effort of constructing coral reef condition basic data on Binor, Paiton, and Probolinggo regency seashore. The method used in this research is Line Intercept Transect (LIT method. LIT method is a method that used to decide benthic community on coral reef based on percentage growth, and to take note of benthic quantity along transect line. Percentage of living coral coverage in 3 meters depth on this Binor Paiton seashore that may be categorized in a good condition is 57,65%. While the rest are dead coral that is only 1,45%, other life form in 23,2%, and non-life form in 17,7%. A good condition of coral reef is caused by coral reef transplantation on the seashore, so this coral reef is dominated by Acropora Branching. On the other hand, Mortality Index (IM of coral reef resulted in 24,5%. The result from observation and calculation of coral reef is dominated by Hard Coral in Acropora Branching (ACB with coral reef coverage percentage of 39%, Coral Massive (CM with coral reef coverage percentage of 2,85%, Coral Foliose (CF with coral reef coverage percentage of 1,6%, and Coral Mushroom (CRM with coral reef coverage percentage of 8,5%. Observation in 10 meters depth

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Directory of Open Access Journals (Sweden)

G. Wang

2018-02-01

Full Text Available To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring–neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L−1, appeared at low tide and the minimum, 14.0 dpm 100 L−1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring–neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2  ≥  0.9 and P < 0.05 at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitrite-depleted, nitrate- and phosphate-rich less saline groundwater and nitrite-rich, nitrate- and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NOx and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NOx and phosphate were significantly correlated with regression slopes of 4.60 (R2  =  0.16 in the spring tide and 13.4 (R2  =  0.75 in the neap tide, similar to the composition of these

National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in the Hawaiian Archipelago from Water Samples collected since 2013

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and...

National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in the Mariana Archipelago from Water Samples collected in 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and...

Ocean acidification: Linking science to management solutions using the Great Barrier Reef as a case study.

Science.gov (United States)

Albright, Rebecca; Anthony, Kenneth R N; Baird, Mark; Beeden, Roger; Byrne, Maria; Collier, Catherine; Dove, Sophie; Fabricius, Katharina; Hoegh-Guldberg, Ove; Kelly, Ryan P; Lough, Janice; Mongin, Mathieu; Munday, Philip L; Pears, Rachel J; Russell, Bayden D; Tilbrook, Bronte; Abal, Eva

2016-11-01

Coral reefs are one of the most vulnerable ecosystems to ocean acidification. While our understanding of the potential impacts of ocean acidification on coral reef ecosystems is growing, gaps remain that limit our ability to translate scientific knowledge into management action. To guide solution-based research, we review the current knowledge of ocean acidification impacts on coral reefs alongside management needs and priorities. We use the world's largest continuous reef system, Australia's Great Barrier Reef (GBR), as a case study. We integrate scientific knowledge gained from a variety of approaches (e.g., laboratory studies, field observations, and ecosystem modelling) and scales (e.g., cell, organism, ecosystem) that underpin a systems-level understanding of how ocean acidification is likely to impact the GBR and associated goods and services. We then discuss local and regional management options that may be effective to help mitigate the effects of ocean acidification on the GBR, with likely application to other coral reef systems. We develop a research framework for linking solution-based ocean acidification research to practical management options. The framework assists in identifying effective and cost-efficient options for supporting ecosystem resilience. The framework enables on-the-ground OA management to be the focus, while not losing sight of CO2 mitigation as the ultimate solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reef fishes of Saba Bank, Netherlands Antilles: assemblage structure across a gradient of habitat types.

Directory of Open Access Journals (Sweden)

Wes Toller

Full Text Available Saba Bank is a 2,200 km(2 submerged carbonate platform in the northeastern Caribbean Sea off Saba Island, Netherlands Antilles. The presence of reef-like geomorphic features and significant shelf edge coral development on Saba Bank have led to the conclusion that it is an actively growing, though wholly submerged, coral reef atoll. However, little information exists on the composition of benthic communities or associated reef fish assemblages of Saba Bank. We selected a 40 km(2 area of the bank for an exploratory study. Habitat and reef fish assemblages were investigated in five shallow-water benthic habitat types that form a gradient from Saba Bank shelf edge to lagoon. Significant coral cover was restricted to fore reef habitat (average cover 11.5% and outer reef flat habitat (2.4% and declined to near zero in habitats of the central lagoon zone. Macroalgae dominated benthic cover in all habitats (average cover: 32.5--48.1% but dominant algal genera differed among habitats. A total of 97 fish species were recorded. The composition of Saba Bank fish assemblages differed among habitat types. Highest fish density and diversity occurred in the outer reef flat, fore reef and inner reef flat habitats. Biomass estimates for commercially valued species in the reef zone (fore reef and reef flat habitats ranged between 52 and 83 g/m(2. The composition of Saba Bank fish assemblages reflects the absence of important nursery habitats, as well as the effects of past fishing. The relatively high abundance of large predatory fish (i.e. groupers and sharks, which is generally considered an indicator of good ecosystem health for tropical reef systems, shows that an intact trophic network is still present on Saba Bank.

Model of a coral reef ecosystem

Science.gov (United States)

Atkinson, Marlin J.; Grigg, Richard W.

1984-08-01

The ECOPATH model for French Frigate Shoals estimates the benthic plant production (net primary production in kg wet weight) required to support the atoll food chain. In this section we estimate the benthic net primary production and net community production of the atoll based on metabolism studies of reef flat, knolls, and lagoon communities at French Frigate Shoals Hawaii. Community metabolism was measured during winter and summer. The reef communities at French Frigate Shoals exhibited patterns and rates of organic carbon production and calcification similar to other reefs in the world. The estimate of net primary production is 6.1·106 kg wet weight km-2 year-1±50%, a value remarkably close to the estimate by the ECOPATH model of 4.3·106 kg wet weight km-2 year-1. Our estimate of net community production or the amount of carbon not consumed by the benthos was high; approximately 15% of the net primary production. Model results indicate that about 5% of net primary production is passed up the food chain to mobile predators. This suggests about 10% of net primary production (˜6% of gross primary production) may be permanently lost to the system via sediment burial or export offshore.

The Changing Face of Plio-Pleistocene Reef Margins: Results of the Dominican Republic Drilling Project (DRDP)

Science.gov (United States)

Klaus, J.; McNeill, D. F.; Díaz, V.; Swart, P. K.; Pourmand, A.; Grasmueck, M.; Eberli, G. P.

2013-12-01

Fringing reef margins of the Caribbean display a characteristic zonation in which Acropora palmata dominates shallow high-energy reef crests and Acropora cervicornis calmer fore-reef slopes and backreef lagoons. The dominance of acroporids across this zonation has been attributed to growth rates 5-100 times faster than other corals. However, the dominance and high accretion potential of acroporid reefs has a relatively recent geologic origin. Caribbean reefs changed profoundly in taxonomic composition, diversity, and dominance structure during late Pliocene and Pleistocene climatic change. These changes coincide with protracted climatic deterioration and cooling between 2.0 to 0.8 Ma, and the onset of high amplitude sea-level fluctuations ~400 ka. The Dominican Republic Drilling Project (DRDP) was initiated to determine how climate change and global high-amplitude sea level changes influenced depositional patterns in Pliocene to Recent reef systems of the Caribbean. A transect of 7 core borings (~700 m total depth) were collected along a transect of the southern coast of the DR in conjunction with over 20 km of ground penetrating radar (GPR) lines. New age constraints based on U/Th geochronometry and radiogenic Sr isotopes, combined with depositional lithofacies, faunal indicators, stable isotope profiles and GPR data have allowed us to correlate between wells and define the internal anatomy and stratal geometry of the individual reef sigmoids and sigmoid sets. The stacking of these sigmoid-shaped reefs produce lateral progradation of approximately 15 km with geometries that generally follow the highstand systems tract model of Pomar and Ward (1994). Based on existing age models eccentricity (high amplitude 100 kyr) sigmoids display increased aggradation and progradation potential compared to reef cycles driven by obliquity (41 kyr).

Reef sharks: recent advances in ecological understanding to inform conservation.

Science.gov (United States)

Osgood, G J; Baum, J K

2015-12-01

Sharks are increasingly being recognized as important members of coral-reef communities, but their overall conservation status remains uncertain. Nine of the 29 reef-shark species are designated as data deficient in the IUCN Red List, and three-fourths of reef sharks had unknown population trends at the time of their assessment. Fortunately, reef-shark research is on the rise. This new body of research demonstrates reef sharks' high site restriction, fidelity and residency on coral reefs, their broad trophic roles connecting reef communities and their high population genetic structure, all information that should be useful for their management and conservation. Importantly, recent studies on the abundance and population trends of the three classic carcharhinid reef sharks (grey reef shark Carcharhinus amblyrhynchos, blacktip reef shark Carcharhinus melanopterus and whitetip reef shark Triaenodon obesus) may contribute to reassessments identifying them as more vulnerable than currently realized. Because over half of the research effort has focused on only these three reef sharks and the nurse shark Ginglymostoma cirratum in only a few locales, there remain large taxonomic and geographic gaps in reef-shark knowledge. As such, a large portion of reef-shark biodiversity remains uncharacterized despite needs for targeted research identified in their red list assessments. A research agenda for the future should integrate abundance, life history, trophic ecology, genetics, habitat use and movement studies, and expand the breadth of such research to understudied species and localities, in order to better understand the conservation requirements of these species and to motivate effective conservation solutions. © 2015 The Fisheries Society of the British Isles.

Tourism, Reef Condition and Visitor Satisfaction in Watamu Marine ...

African Journals Online (AJOL)

Abstract—Reef-based tourism is known to put environmental pressure on reefs but its consequences on the ecological and economic sustainability of Marine. Protected Areas is unknown. Previous research suggests that, if reef conditions decline, then tourism on a reef will also suffer, but is this always the case? This.

CORAL REEF BIOLOGICAL CRITERIA: USING THE CLEAN ...

Science.gov (United States)

Coral reefs are declining at unprecedented rates worldwide due to multiple interactive stressors including climate change and land-based sources of pollution. The Clean Water Act (CWA) can be a powerful legal instrument for protecting water resources, including the biological inhabitants of coral reefs. The objective of the CWA is to restore and maintain the chemical, physical and biological integrity of water resources. Coral reef protection and restoration under the Clean Water Act begins with water quality standards - provisions of state or Federal law that consist of a designated use(s) for the waters of the United States and water quality criteria sufficient to protect the uses. Aquatic life use is the designated use that is measured by biological criteria (biocriteria). Biocriteria are expectations set by a jurisdiction for the quality and quantity of living aquatic resources in a defined waterbody. Biocriteria are an important addition to existing management tools for coral reef ecosystems. The Technical Support Document “Coral Reef Biological Criteria: Using the Clean Water Act to Protect a National Treasure” will provide a framework to aid States and Territories in their development, adoption, and implementation of coral reef biocriteria in their respective water quality standards. The Technical Support Document “Coral Reef Biological Criteria: Using the Clean Water Act to Protect a National Treasure” will provide a framework for coral re

Species identity and depth predict bleaching severity in reef-building corals: shall the deep inherit the reef?

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Muir, Paul R; Marshall, Paul A; Abdulla, Ameer; Aguirre, J David

2017-10-11

Mass bleaching associated with unusually high sea temperatures represents one of the greatest threats to corals and coral reef ecosystems. Deeper reef areas are hypothesized as potential refugia, but the susceptibility of Scleractinian species over depth has not been quantified. During the most severe bleaching event on record, we found up to 83% of coral cover severely affected on Maldivian reefs at a depth of 3-5 m, but significantly reduced effects at 24-30 m. Analysis of 153 species' responses showed depth, shading and species identity had strong, significant effects on susceptibility. Overall, 73.3% of the shallow-reef assemblage had individuals at a depth of 24-30 m with reduced effects, potentially mitigating local extinction and providing a source of recruits for population recovery. Although susceptibility was phylogenetically constrained, species-level effects caused most lineages to contain some partially resistant species. Many genera showed wide variation between species, including Acropora, previously considered highly susceptible. Extinction risk estimates showed species and lineages of concern and those likely to dominate following repeated events. Our results show that deeper reef areas provide refuge for a large proportion of Scleractinian species during severe bleaching events and that the deepest occurring individuals of each population have the greatest potential to survive and drive reef recovery. © 2017 The Author(s).

Mapping Mesophotic Reefs Along the Brazilian Continental Margin

Science.gov (United States)

Bastos, A.; Moura, R.; Amado Filho, G.; Ferreira, L.; Boni, G.; Vedoato, F.; D'Agostini, D.; Lavagnino, A. C.; Leite, M. D.; Quaresma, V.

2017-12-01

Submerged or drowned reefs constitute an important geological record of sea level variations, forming the substrate for the colonization of modern benthic mesophotic communities. Although mapping mesophotic reefs has increased in the last years, their spatial distribution is poorly known and the worldwide occurrence of this reef habitat maybe underestimated. The importance in recognizing the distribution of mesophotic reefs is that they can act as a refuge for corals during unsuitable environmental conditions and a repository for shallow water corals. Here we present the result of several acoustic surveys that mapped and discovered new mesophotic reefs along the Eastern and Equatorial Brazilian Continental Margin. Seabed mapping was carried out using multibeam and side scan sonars. Ground truthing was obtained using drop camera or scuba diving. Mesophotic reefs were mapped in water depths varying from 30 to 100m and under distinct oceanographic conditions, especially in terms of river load input and shelf width. Reefs showed distinct morphologies, from low relief banks and paleovalleys to shelf edge ridges. Extensive occurrence of low relief banks were mapped along the most important coralline complex province in the South Atlantic, the Abrolhos Shelf. These 30 to 40m deep banks, have no more than 3 meters in height and may represent fringing reefs formed during sea level stabilization. Paleovalleys mapped along the eastern margin showed the occurrence of coralgal ledges along the channel margins. Paleovalleys are usually deeper than 45m and are associated with outer shelf rhodolith beds. Shelf edge ridges (80 to 120m deep) were mapped along both margins and are related to red algal encrusting irregular surfaces that have more than 3m in height, forming a rigid substrate for coral growth. Along the Equatorial Margin, off the Amazon mouth, shelf edge patch reefs and rhodolith beds forming encrusting surfaces and shelf edge ridges were mapped in water depths greater

1300 km long late Pleistocene-Holocene shelf edge barrier reef system along the western continental shelf of India: Occurrence and significance

Digital Repository Service at National Institute of Oceanography (India)

Vora, K.H.; Wagle, B.G.; Veerayya, M.; Almeida, F.; Karisiddaiah, S.M.

. It is surmised that coral/algal reef growth commenced with the advent of the Holocene trangression and favorable antecedent topography, and continued until early Holocene. Subsequently, rapid sea level rise drowned the reefs. The shelf edge reefs, therefore...

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

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Emma F. Camp

2018-02-01

Full Text Available Global climate change and localized anthropogenic stressors are driving rapid declines in coral reef health. In vitro experiments have been fundamental in providing insight into how reef organisms will potentially respond to future climates. However, such experiments are inevitably limited in their ability to reproduce the complex interactions that govern reef systems. Studies examining coral communities that already persist under naturally-occurring extreme and marginal physicochemical conditions have therefore become increasingly popular to advance ecosystem scale predictions of future reef form and function, although no single site provides a perfect analog to future reefs. Here we review the current state of knowledge that exists on the distribution of corals in marginal and extreme environments, and geographic sites at the latitudinal extremes of reef growth, as well as a variety of shallow reef systems and reef-neighboring environments (including upwelling and CO2 vent sites. We also conduct a synthesis of the abiotic data that have been collected at these systems, to provide the first collective assessment on the range of extreme conditions under which corals currently persist. We use the review and data synthesis to increase our understanding of the biological and ecological mechanisms that facilitate survival and success under sub-optimal physicochemical conditions. This comprehensive assessment can begin to: (i highlight the extent of extreme abiotic scenarios under which corals can persist, (ii explore whether there are commonalities in coral taxa able to persist in such extremes, (iii provide evidence for key mechanisms required to support survival and/or persistence under sub-optimal environmental conditions, and (iv evaluate the potential of current sub-optimal coral environments to act as potential refugia under changing environmental conditions. Such a collective approach is critical to better understand the future survival of

Developing a multi-stressor gradient for coral reefs

Science.gov (United States)

Coral reefs are often found near coastal waters where multiple anthropogenic stressors co-occur at areas of human disturbance. Developing coral reef biocriteria under the U.S. Clean Water Act requires relationships between anthropogenic stressors and coral reef condition to be es...

Spatial and seasonal reef calcification in corals and calcareous crusts in the central Red Sea

KAUST Repository

Roik, Anna Krystyna; Roder, Cornelia; Rö thig, Till; Voolstra, Christian R.

2015-01-01

The existence of coral reef ecosystems critically relies on the reef carbonate framework produced by scleractinian corals and calcareous crusts (i.e., crustose coralline algae). While the Red Sea harbors one of the longest connected reef systems in the world, detailed calcification data are only available from the northernmost part. To fill this knowledge gap, we measured in situ calcification rates of primary and secondary reef builders in the central Red Sea. We collected data on the major habitat-forming coral genera Porites, Acropora, and Pocillopora and also on calcareous crusts (CC) in a spatio-seasonal framework. The scope of the study comprised sheltered and exposed sites of three reefs along a cross-shelf gradient and over four seasons of the year. Calcification of all coral genera was consistent across the shelf and highest in spring. In addition, Pocillopora showed increased calcification at exposed reef sites. In contrast, CC calcification increased from nearshore, sheltered to offshore, exposed reef sites, but also varied over seasons. Comparing our data to other reef locations, calcification in the Red Sea was in the range of data collected from reefs in the Caribbean and Indo-Pacific; however, Acropora calcification estimates were at the lower end of worldwide rates. Our study shows that the increasing coral cover from nearshore to offshore environments aligned with CC calcification but not coral calcification, highlighting the potentially important role of CC in structuring reef cover and habitats. While coral calcification maxima have been typically observed during summer in many reef locations worldwide, calcification maxima during spring in the central Red Sea indicate that summer temperatures exceed the optima of reef calcifiers in this region. This study provides a foundation for comparative efforts and sets a baseline to quantify impact of future environmental change in the central Red Sea.

Spatial and seasonal reef calcification in corals and calcareous crusts in the central Red Sea

KAUST Repository

Roik, Anna Krystyna

2015-12-14

The existence of coral reef ecosystems critically relies on the reef carbonate framework produced by scleractinian corals and calcareous crusts (i.e., crustose coralline algae). While the Red Sea harbors one of the longest connected reef systems in the world, detailed calcification data are only available from the northernmost part. To fill this knowledge gap, we measured in situ calcification rates of primary and secondary reef builders in the central Red Sea. We collected data on the major habitat-forming coral genera Porites, Acropora, and Pocillopora and also on calcareous crusts (CC) in a spatio-seasonal framework. The scope of the study comprised sheltered and exposed sites of three reefs along a cross-shelf gradient and over four seasons of the year. Calcification of all coral genera was consistent across the shelf and highest in spring. In addition, Pocillopora showed increased calcification at exposed reef sites. In contrast, CC calcification increased from nearshore, sheltered to offshore, exposed reef sites, but also varied over seasons. Comparing our data to other reef locations, calcification in the Red Sea was in the range of data collected from reefs in the Caribbean and Indo-Pacific; however, Acropora calcification estimates were at the lower end of worldwide rates. Our study shows that the increasing coral cover from nearshore to offshore environments aligned with CC calcification but not coral calcification, highlighting the potentially important role of CC in structuring reef cover and habitats. While coral calcification maxima have been typically observed during summer in many reef locations worldwide, calcification maxima during spring in the central Red Sea indicate that summer temperatures exceed the optima of reef calcifiers in this region. This study provides a foundation for comparative efforts and sets a baseline to quantify impact of future environmental change in the central Red Sea.

78 FR 67128 - Coral Reef Conservation Program; Meeting

Science.gov (United States)

2013-11-08

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Coral Reef Conservation Program; Meeting AGENCY: Coral Reef Conservation Program, Office of Ocean and Coastal Resource Management... meeting of the U.S. Coral Reef Task Force (USCRTF). The meeting will be held in Christiansted, U.S. Virgin...

Ammonium in Witwatersrand reefs: a possible indicator of metamorphic fluid flow

International Nuclear Information System (INIS)

Meyer, F.M.

1991-01-01

Ammonium concentrations and NH 4 + /K ratios in the Kimberley Reef indicate chemical interaction with metamorphic fluids. The data, although preliminary, also suggests a gold-ammonium association in that higher gold levels are related to higher NH 4 + /K ratios. Samples from the Ventersdorp Contact Reef are also hydrothermally altered but no ammonium was detected. The low ammonium concentrations suggest that over-printing by NH 4 -bearing metamorphic fluids was negligible. From this it is concluded that chemically different fluid systems must have been operative, probably at different times, during Witwatersrand history. It appears, therefore, that ammonium geochemistry is potentially useful in the study of fluid flow and related gold (re)distribution in Witwatersrand reefs. 17 refs., 2 figs., 1 tab

Status of coral reefs of India

Digital Repository Service at National Institute of Oceanography (India)

Muley, E.V.; Venkataraman, K.; Alfred, J.R.B.; Wafar, M.V.M.

and economic significance of coral reefs and the threat perceptions, Government of India has initiated measures for their intensive conservation and management. Present paper deals with ecological status of coral reefs in the country and various national...

Biology of corals and coral reefs

Digital Repository Service at National Institute of Oceanography (India)

Rajkumar, R.; Parulekar, A.H.

on the systematic position is presented. The general structure is depicted with illustrations. Physiology part is updated to current knowledge on reproduction, nutrition and excretion of corals. The coral reefs section begins with status of world reefs...

Doom and boom on a resilient reef: climate change, algal overgrowth and coral recovery.

Directory of Open Access Journals (Sweden)

Guillermo Diaz-Pulido

Full Text Available Coral reefs around the world are experiencing large-scale degradation, largely due to global climate change, overfishing, diseases and eutrophication. Climate change models suggest increasing frequency and severity of warming-induced coral bleaching events, with consequent increases in coral mortality and algal overgrowth. Critically, the recovery of damaged reefs will depend on the reversibility of seaweed blooms, generally considered to depend on grazing of the seaweed, and replenishment of corals by larvae that successfully recruit to damaged reefs. These processes usually take years to decades to bring a reef back to coral dominance.In 2006, mass bleaching of corals on inshore reefs of the Great Barrier Reef caused high coral mortality. Here we show that this coral mortality was followed by an unprecedented bloom of a single species of unpalatable seaweed (Lobophora variegata, colonizing dead coral skeletons, but that corals on these reefs recovered dramatically, in less than a year. Unexpectedly, this rapid reversal did not involve reestablishment of corals by recruitment of coral larvae, as often assumed, but depended on several ecological mechanisms previously underestimated.These mechanisms of ecological recovery included rapid regeneration rates of remnant coral tissue, very high competitive ability of the corals allowing them to out-compete the seaweed, a natural seasonal decline in the particular species of dominant seaweed, and an effective marine protected area system. Our study provides a key example of the doom and boom of a highly resilient reef, and new insights into the variability and mechanisms of reef resilience under rapid climate change.

Contribution to origin of the reefs in northeastern

International Nuclear Information System (INIS)

Nobrega Coutinho, P. da; Farias, C.C.

1979-01-01

Several reef lines parallel to the seashore are encountered on the heaches of north east Brazil, composing one of the most characteristic morphological phenomena of the region. The textural and mineralogical composition of the reefs is very similar to the sediments met in the submarine beach. The initial comentation seems to take place beach. X-ray diffraction analyses showed that the cement of the first reef line of the intertidal zone is constituited of 60% aragonite and of 40% magnesium calcite with approximately 15-18 mol. %MgCO 3 in the calcite. The cement of the second reef line in the submarine beach is made up of solely calcite with only 3 mol. %MgCO 3 . This proportion becomes even smaller in the cement in the reefs beneath the sand bank. The cement of these reefs is a result of the dissolution and precipitation of organic fragments present in the submarine beach sediments, especial Halimeda. The composition of these fragments appeared to be identical to the reefs of the intertidal zone. The magnesium calcite is mainly a result to the alteration of the aragonite, being the marine inorganic precipitation as a secondary process. (author) [pt

How to evaluate the carbon cycle in coral-reef ecosystems. Sangosho ni okeru sanso junkan kenkyu no kadai

Energy Technology Data Exchange (ETDEWEB)

Yamamuro, M [Geological Survey of Japan, Tsukuba (Japan)

1993-05-01

This paper describes problems concerning carbon balance and nutrient salt in coral reefs. Coral reefs fix CO2 in two forms of organic matters and calcium carbonates. It is reported that 10% of organic matters fixed by photosynthesis may either be buried in deposits on coral reefs or flow out into open seas. Quantification of the carbon balance in coral reefs has a problem of handling organic matters in calcium carbonate skeletons as products, and a problem related to evaluation of organic matters flown out from ecological systems. Corals provide, through building foundations at shallow depths, living organisms carrying out photosynthesis with locations abundant in quantity of light. Coral reefs are thought to accumulate nutrients in their skeletons or in the foundations for deposits. They would hold nitrogen in them through nitrogen fixation, and maintain phosphor production at high levels by retaining nitrogen-to-phosphor ratio which is relatively lower than in other ecological systems. Coral reefs provide foundations to transparent sea water with extremely small amount of phytoplankton, and favorable environment for large-size animals and algae. 21 refs., 2 figs.

Watershed processes from ridge to reef: consequences of feral ungulates for coral reef and effects of watershed management

Science.gov (United States)

Gordon Tribble; Jonathan Stock; Jim Jacobi

2016-01-01

Molokai’s south shore has some of Hawaii’s most extensive and best-developed coral reefs. Historic terrigenous sedimentation appears to have impacted coral growth along several miles of fringing reef. The land upslope of the reef consists of small watersheds with streams that flow intermittently to the ocean. A USGS gage at the outlet of one of the most impacted...

Coral reef ecosystem

Digital Repository Service at National Institute of Oceanography (India)

Wafar, M.V.M.; Wafar, S.

), on submerged banks like Gave shani bank (13°24'N; 73°45'E) (Nair and Qasim 1978) andSidere~ko Bank (13°43.5' N; 73°42'E) (Rao 1972) and as stray individual units off Visakhapatnam (Bakus, G. personal communication) and Pondicherry (Ramesh, A. personal... communication). Fossil reefs, drowned as a result of the Holocene sea level rise, occur at 92, 85, 75 and 55 m depth along .. ~ !! ":2 0. ~ Figure 3.1 Graphical Representation of the SO-Box Model of a Caribbean Coral Reef Key: 1. Benthic producers. 2. Detritus...

Identification of Coral Reefs in Mamburit Waters, Sumenep Regency

OpenAIRE

Sawiya, Sawiya; Mahmudi, Mohammad; Guntur, Guntur

2014-01-01

This research was conducted in September to October 2013 in Mamburit Waters, Sumenep Regency. This study was aimed to assess the percentage of coral reefs and acknowkedge the type of the coral reefs. Coral reefs was observed with the Line Intercept (LIT) method laid parallel to the coastline in the depth of 3 m and 10 m in windward and leeward area. Total of 59.88% coral reefs lived in leeward area in 3 m depth includes in good category and the percentage of dead coral reefs and other fauna f...

Community metabolism in shallow coral reef and seagrass ecosystems, lower Florida Keys

Science.gov (United States)

Turk, Daniela; Yates, Kimberly K.; Vega-Rodriguez, Maria; Toro-Farmer, Gerardo; L'Esperance, Chris; Melo, Nelson; Ramsewak, Deanesch; Estrada, S. Cerdeira; Muller-Karger, Frank E.; Herwitz, Stan R.; McGillis, Wade

2016-01-01

Diurnal variation of net community production (NEP) and net community calcification (NEC) were measured in coral reef and seagrass biomes during October 2012 in the lower Florida Keys using a mesocosm enclosure and the oxygen gradient flux technique. Seagrass and coral reef sites showed diurnal variations of NEP and NEC, with positive values at near-seafloor light levels >100–300 µEinstein m-2 s-1. During daylight hours, we detected an average NEP of 12.3 and 8.6 mmol O2 m-2 h-1 at the seagrass and coral reef site, respectively. At night, NEP at the seagrass site was relatively constant, while on the coral reef, net respiration was highest immediately after dusk and decreased during the rest of the night. At the seagrass site, NEC values ranged from 0.20 g CaCO3 m-2 h-1 during daylight to -0.15 g CaCO3 m-2 h-1 at night, and from 0.17 to -0.10 g CaCO3 m-2 h-1 at the coral reef site. There were no significant differences in pH and aragonite saturation states (Ωar) between the seagrass and coral reef sites. Decrease in light levels during thunderstorms significantly decreased NEP, transforming the system from net autotrophic to net heterotrophic.

Robust Performance of Marginal Pacific Coral Reef Habitats in Future Climate Scenarios.

Science.gov (United States)

Freeman, Lauren A

2015-01-01

Coral reef ecosystems are under dual threat from climate change. Increasing sea surface temperatures and thermal stress create environmental limits at low latitudes, and decreasing aragonite saturation state creates environmental limits at high latitudes. This study examines the response of unique coral reef habitats to climate change in the remote Pacific, using the National Center for Atmospheric Research Community Earth System Model version 1 alongside the species distribution algorithm Maxent. Narrow ranges of physico-chemical variables are used to define unique coral habitats and their performance is tested in future climate scenarios. General loss of coral reef habitat is expected in future climate scenarios and has been shown in previous studies. This study found exactly that for most of the predominant physico-chemical environments. However, certain coral reef habitats considered marginal today at high latitude, along the equator and in the eastern tropical Pacific were found to be quite robust in climate change scenarios. Furthermore, an environmental coral reef refuge previously identified in the central south Pacific near French Polynesia was further reinforced. Studying the response of specific habitats showed that the prevailing conditions of this refuge during the 20th century shift to a new set of conditions, more characteristic of higher latitude coral reefs in the 20th century, in future climate scenarios projected to 2100.

Robust Performance of Marginal Pacific Coral Reef Habitats in Future Climate Scenarios.

Directory of Open Access Journals (Sweden)

Lauren A Freeman

Full Text Available Coral reef ecosystems are under dual threat from climate change. Increasing sea surface temperatures and thermal stress create environmental limits at low latitudes, and decreasing aragonite saturation state creates environmental limits at high latitudes. This study examines the response of unique coral reef habitats to climate change in the remote Pacific, using the National Center for Atmospheric Research Community Earth System Model version 1 alongside the species distribution algorithm Maxent. Narrow ranges of physico-chemical variables are used to define unique coral habitats and their performance is tested in future climate scenarios. General loss of coral reef habitat is expected in future climate scenarios and has been shown in previous studies. This study found exactly that for most of the predominant physico-chemical environments. However, certain coral reef habitats considered marginal today at high latitude, along the equator and in the eastern tropical Pacific were found to be quite robust in climate change scenarios. Furthermore, an environmental coral reef refuge previously identified in the central south Pacific near French Polynesia was further reinforced. Studying the response of specific habitats showed that the prevailing conditions of this refuge during the 20th century shift to a new set of conditions, more characteristic of higher latitude coral reefs in the 20th century, in future climate scenarios projected to 2100.

Hypoxia tolerance in coral-reef triggerfishes (Balistidae)

Science.gov (United States)

Wong, Corrie C.; Drazen, Jeffrey C.; Callan, Chatham K.; Korsmeyer, Keith E.

2018-03-01

Despite high rates of photosynthetic oxygen production during the day, the warm waters of coral reefs are susceptible to hypoxia at night due to elevated respiration rates at higher temperatures that also reduce the solubility of oxygen. Hypoxia may be a challenge for coral-reef fish that hide in the reef to avoid predators at night. Triggerfishes (Balistidae) are found in a variety of reef habitats, but they also are known to find refuge in reef crevices and holes at night, which may expose them to hypoxic conditions. The critical oxygen tension ( P crit) was determined as the point below which oxygen uptake could not be maintained to support standard metabolic rate (SMR) for five species of triggerfish. The triggerfishes exhibited similar levels of hypoxia tolerance as other coral-reef and coastal marine fishes that encounter low oxygen levels in their environment. Two species, Rhinecanthus rectangulus and R. aculeatus, had the lowest P crit ( 3.0 kPa O2), comparable to the most hypoxia-tolerant obligate coral-dwelling gobies, while Odonus niger and Sufflamen bursa were moderately tolerant to hypoxia ( P crit 4.5 kPa), and Xanthichthys auromarginatus was intermediate ( P crit 3.7 kPa). These differences in P crit were not due to differences in oxygen demand, as all the species had a similar SMR once mass differences were taken into account. The results suggest that triggerfish species are adapted for different levels of hypoxia exposure during nocturnal sheltering within the reef.

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Marianas Archipelago from 2011-04-07 to 2014-05-04 (NCEI Accession 0162461)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across Wake Island from 2011-03-23 to 2014-03-19 (NCEI Accession 0162467)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Hawaiian Archipelago from 2013-08-03 to 2016-09-24 (NCEI Accession 0162465)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Hawaiian Archipelago from 2008-10-07 to 2013-09-13 (NCEI Accession 0162470)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across American Samoa from 2012-04-03 to 2015-03-26 (NCEI Accession 0162468)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

Hysteresis in coral reefs under macroalgal toxicity and overfishing.

Science.gov (United States)

Bhattacharyya, Joydeb; Pal, Samares

2015-03-01

Macroalgae and corals compete for the available space in coral reef ecosystems.While herbivorous reef fish play a beneficial role in decreasing the growth of macroalgae, macroalgal toxicity and overfishing of herbivores leads to proliferation of macroalgae. The abundance of macroalgae changes the community structure towards a macroalgae-dominated reef ecosystem. We investigate coral-macroalgal phase shifts by means of a continuous time model in a food chain. Conditions for local asymptotic stability of steady states are derived. It is observed that in the presence of macroalgal toxicity and overfishing, the system exhibits hysteresis through saddle-node bifurcation and transcritical bifurcation. We examine the effects of time lags in the liberation of toxins by macroalgae and the recovery of algal turf in response to grazing of herbivores on macroalgae by performing equilibrium and stability analyses of delay-differential forms of the ODE model. Computer simulations have been carried out to illustrate the different analytical results.

The coral reef of South Moloka'i, Hawai'i - Portrait of a sediment-threatened fringing reef

Science.gov (United States)

Field, Michael E.; Cochran, Susan A.; Logan, Joshua; Storlazzi, Curt D.

2008-01-01

Moloka‘i, with the most extensive coral reef in the main Hawaiian Islands, is especially sacred to Hina, the Goddess of the Moon. As Hinaalo, she is the Mother of the Hawaiian people; as Hinapuku‘a, she is the Goddess of Fishermen; and in the form Hina‘opuhalako‘a, she is the Goddess who gave birth to coral, coral reefs, and all spiny marine organisms. Interdependence between the reef’s living resources, the people, and their cosmology was the basis for management of Moloka‘i’s coastal waters for over a thousand years.The ancient residents of Moloka‘i built the greatest concentration of fishponds known anywhere, but their mastery of mariculture, something needed now more than ever, was lost after near genocide from exotic Western diseases. Subsequent destruction of the native vegetation for exotic cattle, goats, pigs, sugar cane, and pineapple caused soil erosion and sedimentation on the reef flat. This masterful volume clearly documents that soil washing into the sea is the major threat to the reef today. Abandoned fishponds, choked with sediment, now act as barriers and mud traps, making damage to corals less than it would otherwise would have been.The role of mud and freshwater from land in preventing coral reef growth, clearly articulated in Charles Darwin’s first book, The Structure and Distribution of Coral Reefs, is the major theme of this book. All around the tropics, coral reefs have died from huge increases in terrestrial sedimentation that resulted from destruction of hillside forests for cash-crop agriculture and pastures in the colonial era, especially in Latin America, Asia, and the islands of the Caribbean and Indo-Pacific. It is obvious that one cannot manage the coastal zone as a unit separate from the watersheds that drain into it. Yet there has been surprisingly little comprehensive scientific study of these impacts.In this landmark volume, U.S. Geological Survey researchers and their colleagues have developed and applied a

Fluid Characteristics in the Giant Quartz Reef System of the Bundelkhand Craton, India: Constraints from Fluid Inclusion Study

Science.gov (United States)

Rout, D.; Panigrahi, M. K.; Pati, J. K.

2017-12-01

Giant quartz reefs are anomalous features indicating extensive mobilization of silica in the crust. Such reefs in the Abitibi belt, Canada and elsewhere are believed to be the result of activity of fluid of diverse sources on terrain boundaries. The Bundelkhand granitoid complex constituting a major part of the Bundelkhnad Craton in north-Central India is traversed by numerous such quartz reefs all across for a length of about 500 km. There are about 20 major reefs having dimensions of 35 to 40 km in length, 50 to 60 m in width standing out as prominent ridges in the region. Almost all are aligned parallel to each other in a sub-vertical to vertical manner following the NE-SW to NNE-SSW trend. Fluid inclusion petrography in quartz from these reefs reveal four types of inclusions viz. aqueous biphase (type-I), pure carbonic (type-II), aqueous carbonic (type-III) and polyphase (type-IV) inclusions. The type-I aqueous biphase inclusions are the dominant type in all the samples studied so far. Salinities calculated from temperature of melting of last ice (Tm) values are low to moderate, ranging from 0.18 to 18.19 wt% NaCl equivalents. Temperature of liquid-vapor homogenization (Th) values of these inclusions show a wide range from 101 ºC to 386 ºC (cluster around 150-250 ºC) essentially into liquid phase ruling out boiling during its course of evolution. Besides, aqueous Biphase inclusions, some data on pure CO2 inclusions furnish a near constant value of TmCO2 at -56.6 ºC in the Bundelkhand Craton indicating absence of CH4. Bivariate plot between Th and salinity suggest three possible water types which are controlling the overall activity of fluid in quartz reefs of Bundelkhand Craton viz. low-T low saline, high-T low saline and moderate-T and moderate saline. A low saline and CO2-bearing and higher temperature nature resembles a metamorphic fluid that may be a source for these giant quartz reefs. The low temperature low-salinity component could be a meteoric

Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

KAUST Repository

Williamson, David H.; Harrison, Hugo B.; Almany, Glenn R.; Berumen, Michael L.; Bode, Michael; Bonin, Mary C.; Choukroun, Severine; Doherty, Peter J.; Frisch, Ashley J.; Saenz-Agudelo, Pablo; Jones, Geoffrey P.

2016-01-01

Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no-take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short-distance larval dispersal within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long-distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.

Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

KAUST Repository

Williamson, David H.

2016-11-15

Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no-take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short-distance larval dispersal within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long-distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.

Early-phase dynamics in coral recovery following cyclone disturbance on the inshore Great Barrier Reef, Australia

Science.gov (United States)

Sato, Yui; Bell, Sara C.; Nichols, Cassandra; Fry, Kent; Menéndez, Patricia; Bourne, David G.

2018-06-01

Coral recovery (the restoration of abundance and composition of coral communities) after disturbance is a key process that determines the resilience of reef ecosystems. To understand the mechanisms underlying the recovery process of coral communities, colony abundance and size distribution were followed on reefs around Pelorus Island, located in the inshore central region of the Great Barrier Reef, following a severe tropical cyclone in 2011 that caused dramatic loss of coral communities. Permanent quadrats (600 m2) were monitored biannually between 2012 and 2016, and individual coral colonies were counted, sized and categorized into morphological types. The abundance of coral recruits and coral cover were also examined using permanent quadrats and random line intercept transects, respectively. The number of colonies in the smallest size class (4-10 cm) increased substantially during the study period, driving the recovery of coral populations. The total number of coral colonies 5 yr post-cyclone reached between 73 and 122% of pre-cyclone levels though coral cover remained between 16 and 31% of pre-cyclone levels, due to the dominance of small coral colonies in the recovering communities. Temporal transitions of coral demography (i.e., colony-size distributions) illustrated that the number of recently established coral populations overtook communities of surviving colonies. Coral recruits (coral recovery. A shift in morphological composition of coral communities was also observed, with the relative abundance of encrusting corals reduced post-cyclone in contrast to their dominance prior to the disturbance. This study identifies the fine-scale processes involved in the initial recovery of coral reefs, providing insights into the dynamics of coral demography that are essential for determining coral reef resilience following major disturbance.

Neogene reef coral assemblages of the Bocas del Toro region, Panama: the rise of Acropora palmata

Science.gov (United States)

Klaus, J. S.; McNeill, D. F.; Budd, A. F.; Coates, A. G.

2012-03-01

Temporal patterns are evaluated in Neogene reef coral assemblages from the Bocas del Toro Basin of Panama in order to understand how reef ecosystems respond to long-term environmental change. Analyses are based on a total of 1,702 zooxanthellate coral specimens collected from six coral-bearing units ranging in age from the earliest Late Miocene to the Early Pleistocene: (1) Valiente Formation (12-11 Ma), (2) Fish Hole Member of the Old Bank Formation (5.8-5.6 Ma), (3) La Gruta Member of the Isla Colon Formation (2.2-1.4 Ma), (4) Ground Creek Member of the Isla Colon Formation (2.2-1.4 Ma), (5) Mimitimbi Member of the Urracá Formation (1.2-0.8 Ma), and (6) Hill Point Member of the Urracá Formation (1.2-0.8 Ma). Over 100 coral species occur in the six units, with faunal assemblages ranging from less than 10% extant taxa (Valiente Formation) to over 85% extant taxa (Ground Creek Member). The collections provide new temporal constraints on the emergence of modern Caribbean reefs, with the La Gruta Member containing the earliest occurrence of large monospecific stands of the dominant Caribbean reef coral Acropora palmata, and the Urracá Formation containing the last fossil occurrences of 15 regionally extinct taxa. Canonical correspondence analysis of 41 Late Miocene to Recent reef coral assemblages from the Caribbean region suggests changes in community structure coincident with effective oceanic closure of the Central American Seaway (~3.5 Ma). These changes, including increased Acropora dominance, may have contributed to a protracted period of elevated extinction debt prior to the major peak in regional coral extinctions (~2-1 Ma).

Decline of coral reefs during late Paleocene to early Eocene global warming

OpenAIRE

Scheibner , C.; Speijer , R. P.

2007-01-01

International audience; Since the 1980s the frequency of warming events has intensified and simultaneously widespread coral bleaching, and enhanced coral mortality have been observed. Yet, it remains unpredictable how tropical coral reef communities will react to prolonged adverse conditions. Possibly, coral reef systems are sufficiently robust to withstand continued environmental pressures. But if coral mortality increases, what will platform communities of the future look like? The co-evolu...

Artificial Reefs

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block...

Bayesian nonparametric system reliability using sets of priors

NARCIS (Netherlands)

Walter, G.M.; Aslett, L.J.M.; Coolen, F.P.A.

2016-01-01

An imprecise Bayesian nonparametric approach to system reliability with multiple types of components is developed. This allows modelling partial or imperfect prior knowledge on component failure distributions in a flexible way through bounds on the functioning probability. Given component level test

Influence of landscape structure on reef fish assemblages

Science.gov (United States)

Grober-Dunsmore, R.; Frazer, T.K.; Beets, J.P.; Lindberg, W.J.; Zwick, P.; Funicelli, N.A.

2008-01-01

Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape. ?? 2007 Springer Science+Business Media B.V.

Coral reefs as drivers of cladogenesis: expanding coral reefs, cryptic extinction events, and the development of biodiversity hotspots.

Science.gov (United States)

Cowman, P F; Bellwood, D R

2011-12-01

Diversification rates within four conspicuous coral reef fish families (Labridae, Chaetodontidae, Pomacentridae and Apogonidae) were estimated using Bayesian inference. Lineage through time plots revealed a possible late Eocene/early Oligocene cryptic extinction event coinciding with the collapse of the ancestral Tethyan/Arabian hotspot. Rates of diversification analysis revealed elevated cladogenesis in all families in the Oligocene/Miocene. Throughout the Miocene, lineages with a high percentage of coral reef-associated taxa display significantly higher net diversification rates than expected. The development of a complex mosaic of reef habitats in the Indo-Australian Archipelago (IAA) during the Oligocene/Miocene appears to have been a significant driver of cladogenesis. Patterns of diversification suggest that coral reefs acted as a refuge from high extinction, as reef taxa are able to sustain diversification at high extinction rates. The IAA appears to support both cladogenesis and survival in associated lineages, laying the foundation for the recent IAA marine biodiversity hotspot. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Can mesophotic reefs replenish shallow reefs? Reduced coral reproductive performance casts a doubt.

Science.gov (United States)

Shlesinger, Tom; Grinblat, Mila; Rapuano, Hanna; Amit, Tal; Loya, Yossi

2018-02-01

Mesophotic coral ecosystems (i.e., deep coral reefs at 30-120 m depth) appear to be thriving while many shallow reefs in the world are declining. Amid efforts to understand and manage their decline, it was suggested that mesophotic reefs might serve as natural refuges and a possible source of propagules for the shallow reefs. However, our knowledge of how reproductive performance of corals alters with depth is sparse. Here, we present a comprehensive study of the reproductive phenology, fecundity, and abundance of seven reef-building conspecific corals in shallow and mesophotic habitats. Significant differences were found in the synchrony and timing of gametogenesis and spawning between shallow and mesophotic coral populations. Thus, mesophotic populations exhibited delayed or protracted spawning events, which led to spawning of the mesophotic colonies in large proportions at times where the shallow ones had long been depleted of reproductive material. All species investigated demonstrated a substantial reduction in fecundity and/or oocyte sizes at mesophotic depths (40-60 m). Two species (Seriatopora hystrix and Galaxea fascicularis) displayed a reduction in both fecundity and oocyte size at mesophotic depths. Turbinaria reniformis had only reduced fecundity and Acropora squarrosa and Acropora valida only reduced oocyte size. In Montipora verrucosa, reduced fecundity was found during one annual reproductive season while, in the following year, only reduced oocyte size was found. In contrast, reduced oocyte size in mesophotic populations of Acropora squarrosa was consistent along three studied years. One species, Acropora pharaonis, was found to be infertile at mesophotic depths along two studied years. This indicates that reproductive performance decreases with depth; and that although some species are capable of reproducing at mesophotic depths, their contribution to the replenishment of shallow reefs may be inconsequential. Reduced reproductive performance

Oyster Reef Communities in the Chesapeake Bay: A Brief Primer. VORTEX: Virginia's Oyster Reef Teaching EXperience.

Science.gov (United States)

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This document introduces Virginia's Oyster Reef Teaching EXperience (VORTEX), which is an interdisciplinary program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem. The VORTEX program uses field and laboratory experience supported by multimedia instruction. This document presents an overview on the biology of…

Determining the extent and characterizing coral reef habitats of the northern latitudes of the Florida Reef Tract (Martin County).

Science.gov (United States)

Walker, Brian K; Gilliam, David S

2013-01-01

Climate change has recently been implicated in poleward shifts of many tropical species including corals; thus attention focused on higher-latitude coral communities is warranted to investigate possible range expansions and ecosystem shifts due to global warming. As the northern extension of the Florida Reef Tract (FRT), the third-largest barrier reef ecosystem in the world, southeast Florida (25-27° N latitude) is a prime region to study such effects. Most of the shallow-water FRT benthic habitats have been mapped, however minimal data and limited knowledge exist about the coral reef communities of its northernmost reaches off Martin County. First benthic habitat mapping was conducted using newly acquired high resolution LIDAR bathymetry and aerial photography where possible to map the spatial extent of coral reef habitats. Quantitative data were collected to characterize benthic cover and stony coral demographics and a comprehensive accuracy assessment was performed. The data were then analyzed in a habitat biogeography context to determine if a new coral reef ecosystem region designation was warranted. Of the 374 km(2) seafloor mapped, 95.2% was Sand, 4.1% was Coral Reef and Colonized Pavement, and 0.7% was Other Delineations. Map accuracy assessment yielded an overall accuracy of 94.9% once adjusted for known map marginal proportions. Cluster analysis of cross-shelf habitat type and widths indicated that the benthic habitats were different than those further south and warranted designation of a new coral reef ecosystem region. Unlike the FRT further south, coral communities were dominated by cold-water tolerant species and LIDAR morphology indicated no evidence of historic reef growth during warmer climates. Present-day hydrographic conditions may be inhibiting poleward expansion of coral communities along Florida. This study provides new information on the benthic community composition of the northern FRT, serving as a baseline for future community shift and

Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers

Science.gov (United States)

Fujita, K.; Hikami, M.; Suzuki, A.; Kuroyanagi, A.; Sakai, K.; Kawahata, H.; Nojiri, Y.

2011-08-01

Ocean acidification (decreases in carbonate ion concentration and pH) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Large, algal symbiont-bearing benthic foraminifers, which are important primary and carbonate producers in coral reefs, produce high-Mg calcite shells, whose solubility can exceed that of aragonite produced by corals, making them the "first responder" in coral reefs to the decreasing carbonate saturation state of seawater. Here we report results of culture experiments performed to assess the effects of ongoing ocean acidification on the calcification of symbiont-bearing reef foraminifers using a high-precision pCO2 control system. Living clone individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured individuals were maintained for about 12 weeks in an indoor flow-through system under constant water temperature, light intensity, and photoperiod. After the experiments, the shell diameter and weight of each cultured specimen were measured. Net calcification of B. sphaerulata and C. gaudichaudii, which secrete a hyaline shell and host diatom symbionts, increased under intermediate levels of pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level (970 μatm). Net calcification of A. hemprichii, which secretes a porcelaneous shell and hosts dinoflagellate symbionts, tended to decrease at elevated pCO2. Observed different responses between hyaline and porcelaneous species are possibly caused by the relative importance of elevated pCO2, which induces CO2 fertilization effects by algal symbionts, versus associated changes in seawater carbonate chemistry, which decreases a carbonate concentration. Our findings suggest that ongoing ocean acidification might favor symbiont

International Workshop on Carbon Cycling and Coral Reef Metabolism; Sangosho no tanso junkan ni kansuru kokusai workshop hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-10-16

The paper described the International Workshop on Carbon Cycling and Coral Reef Metabolism which was held at Miyako-jima, Okinawa Pref. on October 17-24, 1995. In the workshop, researchers got together which are involved in marine chemistry, marine biology, coral ecology, and environmental science, and discussed the carbon cycling and metabolism of coral reef. Discussions were made on what the coral reef ecosystem is, and what the definition of a sink or a source for CO2 is. Also discussed were scales of how much time and space should be considered to make these issues clear. Further, it was proposed that it was necessary to investigate carbon balance of both the whole system and the components of the system and to keep track of mass transfer among neighboring components of the system. Seventeen presentations were given. The workshop obtained a definite consensus on carbon balance of the coral reef system. 123 refs., 39 figs., 9 tabs.

Scientific Frontiers in the Management of Coral Reefs

Directory of Open Access Journals (Sweden)

Shankar eAswani

2015-07-01

Full Text Available Coral reefs are subjected globally to a variety of natural and anthropogenic stressors that often act synergistically. Today, reversing ongoing and future coral reef degradation presents significant challenges and countering this negative trend will take considerable efforts and investments. Scientific knowledge can inform and guide the requisite decision-making process and offer practical solutions to the problem of protection as the effects of climate change exacerbate. However, implementation of solutions presently lags far behind the pace required to reverse global declines, and there is a need for an urgent and significant step-up in the extent and range of strategies being implemented. In this paper, we consider scientific frontiers in natural and social science research that can help build stronger support for reef management and improve the efficacy of interventions. We cover various areas including: (1 enhancing the case for reef conservation and management, (2 dealing with local stressors on reefs, (3 addressing global climate change impacts, (4 and reviewing various approaches to the governance of coral reefs. In sum, we consider scientific frontiers in natural and social science that will require further attention in coming years as managers’ work towards building stronger support for reef management and improve the efficacy of local interventions.

Coral Reefs: A Gallery Program, Grades 7-12.

Science.gov (United States)

National Aquarium in Baltimore, MD. Dept. of Education.

Gallery classes at the National Aquarium in Baltimore give the opportunity to study specific aquarium exhibits which demonstrate entire natural habitats. The coral reef gallery class features the gigantic western Atlantic coral reef (325,000 gallons) with over 1,000 fish. The exhibit simulates a typical Caribbean coral reef and nearby sandy…

Recent and relict topography of Boo Bee patch reef, Belize

Science.gov (United States)

Halley, R.B.; Shinn, E.A.; Hudson, J.H.; Lidz, B.; Taylor, D.L.

1977-01-01

Five core borings were taken on and around Boo Bee Patch Reef to better understand the origin of such shelf lagoon reefs. The cores reveal 4 stages of development: (1) subaerial exposure of a Pleistocene "high" having about 8 meters of relief, possibly a Pleistocene patch reef; (2) deposition of peat and impermeable terrigenous clay 3 meters thick around the high; (3) initiation of carbonate sediment production by corals and algae on the remaining 5 meters of hard Pleistocene topography and carbonate mud on the surrounding terrigenous clay; and (4) accelerated organic accumulation on the patch reef. Estimates of patch reef sedimentation rates (1.6 m/1000 years) are 3 to 4 times greater than off-reef sedimentation rates (0.4-0.5 m/1000 years). During periods of Pleistocene sedimentation on the Belize shelf, lagoon patch reefs may have grown above one another, stacking up to form reef accumulation of considerable thickness.

National Coral Reef Monitoring Program: Coral Reef Fish collected in Fl Keys Reef Tract (2014)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Divers conducted reef visual census (RVC) fish surveys and habitat assessments at 433 sites in the Florida Keys, 436 sites in the Dry Tortugas and 320 sites in the...

Nitrification in reef corals

Digital Repository Service at National Institute of Oceanography (India)

Wafar, M.V.M.; Wafar, S.; David, J.J.

. An estimate of the density of nitrifying bacteria on living corals can be made by comparing the nitrifying rates of bacterial cells and the rate of production of NO,-. Kaplan (1983) summarized the growth con- stants of marine nitrifying bacteria... Reef Con=. 3: 395-399. -, C. R. WILKINSON, V. p. VICENTE, J. M. MORELL, AND E. OTERO. 1988. Nitrate release by Carib- bean reef sponges. Limnol. Oceanogr. 33: 114- 120. CROSSLAND, C. J., AND D. J. BARNES. 1983. Dissolved nutrients and organic...

Coral Reef Functioning Along a Cross‐shelf Environmental Gradient: Abiotic and Biotic Drivers of Coral Reef Growth in the Red Sea

KAUST Repository

Roik, Anna

2016-06-01

Despite high temperature and salinity conditions that challenge reef growth in other oceans, the Red Sea maintains amongst the most biodiverse and productive coral reefs worldwide. It is therefore an important region for the exploration of coral reef functioning, and expected to contribute valuable insights towards the understanding of coral reefs in challenging environments. This dissertation assessed the baseline variability of in situ abiotic conditions (temperature, dissolved oxygen, pH, and total alkalinity, among others) in the central Red Sea and highlights these environmental regimes in a global context. Further, focus was directed on biotic factors (biofilm community dynamics, calcification and bioerosion), which underlie reef growth processes and are crucial for maintaining coral reef functioning and ecosystem services. Using full‐year data from an environmental cross‐shelf gradient, the dynamic interplay of abiotic and biotic factors was investigated. In situ observations demonstrate that central Red Sea coral reefs were highly variable on spatial, seasonal, and diel scales, and exhibited comparably high temperature, high salinity, and low dissolved oxygen levels, which on the one hand reflect future ocean predictions. Under these conditions epilithic bacterial and algal assemblages were mainly driven by variables (i.e., temperature, salinity, dissolved oxygen) which are predicted to change strongly in the progression of global climate change, implying an influential bottom up effect on reef‐building communities. On the other hand, measured alkalinity and other carbonate chemistry value were close to the estimates of preindustrial global ocean surface water and thus in favor of reef growth processes. Despite this beneficial carbonate chemistry, calcification and carbonate budgets in the reefs were not higher than in other coral reef regions. In this regard, seasonal calcification patterns suggest that summer temperatures may be exceeding the optima

National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in the Pacific Remote Island Areas from Water Samples collected since 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and...

Patterns of coral species richness and reef connectivity in Malaysia

NARCIS (Netherlands)

Waheed, Z.

2016-01-01

Much remains to be discovered about the biodiversity of coral reefs in Malaysia, making this area a priority for coral reef research. This thesis aims to provide insights into the patterns of reef coral species richness and the degree of reef connectivity across Malaysia. For the species richness

Relationships between structural complexity, coral traits, and reef fish assemblages

Science.gov (United States)

Darling, Emily S.; Graham, Nicholas A. J.; Januchowski-Hartley, Fraser A.; Nash, Kirsty L.; Pratchett, Morgan S.; Wilson, Shaun K.

2017-06-01

With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

Benthic N2 fixation in coral reefs and the potential effects of human-induced environmental change

Science.gov (United States)

Cardini, Ulisse; Bednarz, Vanessa N; Foster, Rachel A; Wild, Christian

2014-01-01

Tropical coral reefs are among the most productive and diverse ecosystems, despite being surrounded by ocean waters where nutrients are in short supply. Benthic dinitrogen (N2) fixation is a significant internal source of “new” nitrogen (N) in reef ecosystems, but related information appears to be sparse. Here, we review the current state (and gaps) of knowledge on N2 fixation associated with coral reef organisms and their ecosystems. By summarizing the existing literature, we show that benthic N2 fixation is an omnipresent process in tropical reef environments. Highest N2 fixation rates are detected in reef-associated cyanobacterial mats and sea grass meadows, clearly showing the significance of these functional groups, if present, to the input of new N in reef ecosystems. Nonetheless, key benthic organisms such as hard corals also importantly contribute to benthic N2 fixation in the reef. Given the usually high coral coverage of healthy reef systems, these results indicate that benthic symbiotic associations may be more important than previously thought. In fact, mutualisms between carbon (C) and N2 fixers have likely evolved that may enable reef communities to mitigate N limitation. We then explore the potential effects of the increasing human interferences on the process of benthic reef N2 fixation via changes in diazotrophic populations, enzymatic activities, or availability of benthic substrates favorable to these microorganisms. Current knowledge indicates positive effects of ocean acidification, warming, and deoxygenation and negative effects of increased ultraviolet radiation on the amount of N fixed in coral reefs. Eutrophication may either boost or suppress N2 fixation, depending on the nutrient becoming limiting. As N2 fixation appears to play a fundamental role in nutrient-limited reef ecosystems, these assumptions need to be expanded and confirmed by future research efforts addressing the knowledge gaps identified in this review. PMID:24967086

Individual-based analyses reveal limited functional overlap in a coral reef fish community.

Science.gov (United States)

Brandl, Simon J; Bellwood, David R

2014-05-01

Detailed knowledge of a species' functional niche is crucial for the study of ecological communities and processes. The extent of niche overlap, functional redundancy and functional complementarity is of particular importance if we are to understand ecosystem processes and their vulnerability to disturbances. Coral reefs are among the most threatened marine systems, and anthropogenic activity is changing the functional composition of reefs. The loss of herbivorous fishes is particularly concerning as the removal of algae is crucial for the growth and survival of corals. Yet, the foraging patterns of the various herbivorous fish species are poorly understood. Using a multidimensional framework, we present novel individual-based analyses of species' realized functional niches, which we apply to a herbivorous coral reef fish community. In calculating niche volumes for 21 species, based on their microhabitat utilization patterns during foraging, and computing functional overlaps, we provide a measurement of functional redundancy or complementarity. Complementarity is the inverse of redundancy and is defined as less than 50% overlap in niche volumes. The analyses reveal extensive complementarity with an average functional overlap of just 15.2%. Furthermore, the analyses divide herbivorous reef fishes into two broad groups. The first group (predominantly surgeonfishes and parrotfishes) comprises species feeding on exposed surfaces and predominantly open reef matrix or sandy substrata, resulting in small niche volumes and extensive complementarity. In contrast, the second group consists of species (predominantly rabbitfishes) that feed over a wider range of microhabitats, penetrating the reef matrix to exploit concealed surfaces of various substratum types. These species show high variation among individuals, leading to large niche volumes, more overlap and less complementarity. These results may have crucial consequences for our understanding of herbivorous processes on

Status and conservation of coral reefs in Costa Rica.

Science.gov (United States)

Cortés, Jorge; Jiménez, Carlos E; Fonseca, Ana C; Alvarado, Juan José

2010-05-01

Costa Rica has coral communities and reefs on the Caribbean coast and on the Pacific along the coast and off-shore islands. The Southern section of the Caribbean coast has fringing and patch reefs, carbonate banks, and an incipient algal ridge. The Pacific coast has coral communities, reefs and isolated coral colonies. Coral reefs have been seriously impacted in the last 30 years, mainly by sediments (Caribbean coast and some Pacific reefs) and by El Niño warming events (both coasts). Monitoring is being carried out at three sites on each coast. Both coasts suffered significant reductions in live coral cover in the 1980's, but coral cover is now increasing in most sites. The government of Costa Rica is aware of the importance of coral reefs and marine environments in general, and in recent years decrees have been implemented (or are in the process of approval) to protect them, but limited resources endanger their proper management and conservation, including proper outreach to reef users and the general public.

Radiography of X-ray in coral reefs

International Nuclear Information System (INIS)

Djoli Soembogo

2016-01-01

The application of X-ray radiography has been developed and it is already widely used in metal materials such as metal steel and carbon steel. This radiography using a source of radiation from X-ray machines. This research attempts to use the application of digital radiography X-ray source and use scanner Epson V700 positive films media for digitization results of conventional radiographic films on coral reefs. It has been testing radiography using Fuji film 100 to get the contrast medium, the sensitivity of the medium and image quality is good, Single Wall Single Image method , and using the media scanner films positive and X-ray sources, observation parameter are density radiographic film and the defect shape. Radiography uses Fuji film 100 to obtain a good contrast medium, good medium sensitivity and good quality image. Radiography of X-ray on coral reefs aims to find defects or discontinuities coral reefs such as porosity which would interfere with the determination of the age of the coral reefs. X-ray exposure time is 1 seconds for a thickness of 5.45 mm and 5.60 mm coral reefs by using a high voltage X-ray machine Rigaku of 130 kV. The result of the positive film scanner in the form of digital radiography that allows for the transfer of digital data or digital computerized data storage. The test results of radiographic on coral reefs with Single Wall Single Image method obtained radiographic film density parameter for Fuji film 100 on coral reefs No. 2 are 2.55; 2.53; 2.59 and on coral reefs No. 4 are 2.62; 2.65; 2.66, unsharpness geometric of radiographic results obtained 0.022 mm and 0.023 mm, sensitivity radiography are 1.648% and 1.604%. No defect found of Porosity that is significant. Status is acceptable for Fuji film 100, because the density of the film is in conformity with the standards referred to. Status of coral reefs No. 2 and No. 4 can be accepted, because it has conformed with the standards referred. (author)

Can partnerships and community-based conservation reverse the decline of coral reef social-ecological systems?

Directory of Open Access Journals (Sweden)

James Barclay Frey

2014-03-01

Full Text Available The marine aquarium trade has played an important role in shaping the ecological state of coral reefs in Indonesia and much of the Asia-Pacific. The use of cyanide by ornamental fishers in Buleleng District, Bali, in the 1980s and 1990s has resulted in a precipitous decline in the ecological health of reefs. Cyanide-free harvesting techniques were introduced after 2000, along with reef restoration measures. This paper examines social and ecological processes in the fishing village of Les, Bali, in ending the use of cyanide and the resulting ecological restoration. An emphasis on conservation-development (with livelihood objectives was important in securing interest and cooperation across stakeholder groups. Adaptive approaches to governance and knowledge co-production were also important. The strategy used at Les is now being exported to other communities across Indonesia, and provides a promising example of a marine resources-based conservation-development initiative that may be implemented at other, similar communities.

Accretion history and stratigraphy of mid-Holocene coral reefs from Southeast Florida, USA

Science.gov (United States)

Stathakopoulos, A.; Riegl, B. M.; Swart, P. K.

2013-05-01

The southeast Florida shelf is a well-studied coral reef region previously used in studies of late Quaternary sea-level, reef geomorphology, and paleoecology in the sub-tropical Atlantic. Situated on the shelf is the southeast Florida continental reef tract; a ~125 km long Holocene fringing/barrier coral reef complex, composed of three shore-parallel linear reefs ('outer', 'middle', and 'inner' reefs) of varying age. Since few detailed stratigraphic descriptions exist, drill cores were extracted to further understand the composition, character, and radiometric ages of reef material in order to reconstruct the accretion history. Sixteen reef cores from the shallow inner reef were collected along and across the reef axes and were combined with lidar bathymetric data for stratigraphic and geomorphologic analyses. Macroscopic and microscopic (petrographic thin sections) examinations of reef clasts were performed to identify coral and reef infauna species compositions, diagenetic facies, and taphonomic features for interpretation of former reef environments/zonation. The southeast Florida continental reef tract was characterized by dynamic reef terminations, backstepping, and re-initiation in response to post-glacial sea-level rise and flooding of topography suitable for reef initiation and growth. Results suggest that the outer reef accreted from ~10.6-8.0 ka cal BP, the middle reef from at least ~5.8-3.7 ka cal BP, and the inner reef from ~7.8-5.5 ka cal BP. The outer reef is the best-developed reef, followed by the inner reef, while the middle reef apparently has relatively little framework buildup. New data from this study and a lack of significant age overlaps confirm that reef backstepping from the outer to the inner reef occurred within a few hundred years after outer reef termination. This is consistent with temporal and spatial scales reported from backstepped reefs in St. Croix and Puerto Rico. The cause of the backstep is still unknown however some studies

Coral Reefs: An English Compilation of Activities for Middle School Students.

Science.gov (United States)

Walker, Sharon H.; Newton, R. Amanda; Ortiz, Alida

This activity book on coral reefs for middle school students is divided into 10 sections. Section 1 contains the introduction. Section 2 describes what coral reefs are while section 3 describes how coral reefs reproduce and grow. Section 4 discusses where coral reefs are found and section 5 describes life on a coral reef. Section 6 discusses the…

Perspectives on the Great Amazon Reef: Extension, Biodiversity, and Threats

Directory of Open Access Journals (Sweden)

Ronaldo B. Francini-Filho

2018-04-01

Full Text Available Here we provide a broad overview of the Great Amazon Reef System (GARS based on the first-ever video surveys of the region. This footage supports four major hypotheses: (1 the GARS area may be six times larger than previously suggested (up to 56,000 km2; (2 the GARS may extend deeper than previously suggested (up to 220 m; (3 the GARS is composed of a greater complexity and diversity of habitats than previously recognized (e.g., reef platforms, reef walls, rhodolith beds, and sponge bottoms; and (4 the GARS represents a useful system to test whether a deep corridor connects the Caribbean Sea to the Southwest Atlantic Ocean. We also call attention to the urgent need to adopt precautionary conservation measures to protect the region in the face of increasing threats from extractive oil and gas practices. With less than 5% of the potential area of the GARS surveyed so far, more research will be required to inform a systematic conservation planning approach and determine how best to establish a network of marine protected areas. Such planning will be required to reconcile extractive activities with effective biodiversity conservation in the GARS.

Pacific Reef Assessment and Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structures (ARMS) Deployed at Coral Reef Sites across the U.S. Pacific from 2008-02-06 to 2012-05-18 (NCEI Accession 0162469)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — To support a long-term program for sustainable management and conservation of coral reef ecosystems, from 2008, Autonomous Reef Monitoring Structures (ARMS) have...

National Coral Reef Monitoring Program: Assessing and Monitoring Cryptic Reef Diversity of Colonizing Marine Invertebrates using Autonomous Reef Monitoring Structure (ARMS) Deployed at Coral Reef Sites across the Pacific Remote Island Areas from 2012-05-03 to 2015-04-28 (NCEI Accession 0162464)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Autonomous Reef Monitoring Structures (ARMS) are used to assess and monitor cryptic reef diversity of colonizing marine invertebrates in the Hawaiian and Mariana...

The DNA of coral reef biodiversity: predicting and protecting genetic diversity of reef assemblages.

Science.gov (United States)

Selkoe, Kimberly A; Gaggiotti, Oscar E; Treml, Eric A; Wren, Johanna L K; Donovan, Mary K; Toonen, Robert J

2016-04-27

Conservation of ecological communities requires deepening our understanding of genetic diversity patterns and drivers at community-wide scales. Here, we use seascape genetic analysis of a diversity metric, allelic richness (AR), for 47 reef species sampled across 13 Hawaiian Islands to empirically demonstrate that large reefs high in coral cover harbour the greatest genetic diversity on average. We found that a species's life history (e.g. depth range and herbivory) mediates response of genetic diversity to seascape drivers in logical ways. Furthermore, a metric of combined multi-species AR showed strong coupling to species richness and habitat area, quality and stability that few species showed individually. We hypothesize that macro-ecological forces and species interactions, by mediating species turnover and occupancy (and thus a site's mean effective population size), influence the aggregate genetic diversity of a site, potentially allowing it to behave as an apparent emergent trait that is shaped by the dominant seascape drivers. The results highlight inherent feedbacks between ecology and genetics, raise concern that genetic resilience of entire reef communities is compromised by factors that reduce coral cover or available habitat, including thermal stress, and provide a foundation for new strategies for monitoring and preserving biodiversity of entire reef ecosystems. © 2016 The Authors.

Abrolhos bank reef health evaluated by means of water quality, microbial diversity, benthic cover, and fish biomass data.

Directory of Open Access Journals (Sweden)

Thiago Bruce

Full Text Available The health of the coral reefs of the Abrolhos Bank (Southwestern Atlantic was characterized with a holistic approach using measurements of four ecosystem components: (i inorganic and organic nutrient concentrations, [1] fish biomass, [1] macroalgal and coral cover and (iv microbial community composition and abundance. The possible benefits of protection from fishing were particularly evaluated by comparing sites with varying levels of protection. Two reefs within the well-enforced no-take area of the National Marine Park of Abrolhos (Parcel dos Abrolhos and California were compared with two unprotected coastal reefs (Sebastião Gomes and Pedra de Leste and one legally protected but poorly enforced coastal reef (the "paper park" of Timbebas Reef. The fish biomass was lower and the fleshy macroalgal cover was higher in the unprotected reefs compared with the protected areas. The unprotected and protected reefs had similar seawater chemistry. Lower vibrio CFU counts were observed in the fully protected area of California Reef. Metagenome analysis showed that the unprotected reefs had a higher abundance of archaeal and viral sequences and more bacterial pathogens, while the protected reefs had a higher abundance of genes related to photosynthesis. Similar to other reef systems in the world, there was evidence that reductions in the biomass of herbivorous fishes and the consequent increase in macroalgal cover in the Abrolhos Bank may be affecting microbial diversity and abundance. Through the integration of different types of ecological data, the present study showed that protection from fishing may lead to greater reef health. The data presented herein suggest that protected coral reefs have higher microbial diversity, with the most degraded reef (Sebastião Gomes showing a marked reduction in microbial species richness. It is concluded that ecological conditions in unprotected reefs may promote the growth and rapid evolution of opportunistic

Extinction vulnerability of coral reef fishes.

Science.gov (United States)

Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron Macneil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

2011-04-01

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. © 2011 Blackwell Publishing Ltd/CNRS.

Genetic assessment of connectivity in the common reef sponge, Callyspongia vaginalis (Demospongiae: Haplosclerida) reveals high population structure along the Florida reef tract

Science.gov (United States)

Debiasse, M. B.; Richards, V. P.; Shivji, M. S.

2010-03-01

The genetic population structure of the common branching vase sponge, Callyspongia vaginalis, was determined along the entire length (465 km) of the Florida reef system from Palm Beach to the Dry Tortugas based on sequences of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene. Populations of C. vaginalis were highly structured (overall ΦST = 0.33), in some cases over distances as small as tens of kilometers. However, nonsignificant pairwise ΦST values were also found between a few relatively distant sampling sites suggesting that some long distance larval dispersal may occur via ocean currents or transport in sponge fragments along continuous, shallow coastlines. Indeed, sufficient gene flow appears to occur along the Florida reef tract to obscure a signal of isolation by distance, but not to homogenize COI haplotype frequencies. The strong genetic differentiation among most of the sampling locations suggests that recruitment in this species is largely local source-driven, pointing to the importance of further elucidating general connectivity patterns along the Florida reef tract to guide the spatial scale of management efforts.

Cryptofauna of the epilithic algal matrix on an inshore coral reef, Great Barrier Reef

Science.gov (United States)

Kramer, M. J.; Bellwood, D. R.; Bellwood, O.

2012-12-01

Composed of a collection of algae, detritus, sediment and invertebrates, the epilithic algal matrix (EAM) is an abundant and ubiquitous feature of coral reefs. Despite its prevalence, there is a paucity of information regarding its associated invertebrate fauna. The cryptofaunal invertebrate community of the EAM was quantitatively investigated in Pioneer Bay on Orpheus Island, Great Barrier Reef. Using a vacuum collection method, a diversity of organisms representing 10 different phyla were identified. Crustacea dominated the samples, with harpacticoid copepods being particularly abundant (2025 ± 132 100 cm-2; mean density ± SE). The volume of coarse particulate matter in the EAM was strongly correlated with the abundance of harpacticoid copepods. The estimated biomass of harpacticoid copepods (0.48 ± 0.05 g m-2; wet weight) suggests that this group is likely to be important for reef trophodynamics and nutrient cycling.

Geohydrology of Enewetak Atoll islands and reefs

International Nuclear Information System (INIS)

Buddemeier, R.W.

1981-01-01

Extensive tidal studies in island wells and the lagoon at Enewetak Atoll have shown that island ground water dynamics are controlled by a layered aquifer system. The surface aquifer of unconsolidated Holocene material extends to a depth of approximately 15 m, and has a hydraulic conductivity K = 60 m/day. From 15 to 60 m (approximate lagoon depth) the reef structure consists of successive layers of altered Pleistocene materials, with bulk permeability substantially higher than that of the surface aquifer. Because of wave set-up over the windward reef and the limited pass area for outflow at the south end of the atoll, lagoon tides rise in phase with the ocean tides but fall later than the ocean water level. This results in a net lagoon-to-ocean head which can act as the driving force for outflow through the permeable Pleistocene aquifer. This model suggests that fresh water, nutrients or radioactive contaminants found in island ground water or reef interstitial water may be discharged primarily into the ocean rather than the lagoon. Atoll island fresh water resources are controlled by recharge, seawater dilution due to vertical tidal mixing between the surface and deeper aquifers, and by loss due to entrainment by the outflowing water in the deeper aquifers. Estimated lagoon-ot-ocean transit times through the deep aquifer are on the order of a few years, which corresponds well to the freshwater residence time estimates based on inventory and recharge. Islands in close proximity to reef channels have more fresh ground water than others, which is consistent with a locally reduced hydraulic gradient and slower flow through the Pleistocene aquifers

Coral diseases and bleaching on Colombian Caribbean coral reefs.

Science.gov (United States)

Navas-Camacho, Raúl; Gil-Agudelo, Diego Luis; Rodríguez-Ramírez, Alberto; Reyes-Nivia, María Catalina; Garzón-Ferreira, Jaime

2010-05-01

Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC) has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá). The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10 x 2m) with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters) are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2), and Urabá had high numbers with bleaching (54.4 colonies/m2). Of the seven reported coral diseases studied, Dark Spots Disease (DSD), and White Plague Disease (WPD) were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A. grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years) variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few long

Coral diseases and bleaching on Colombian Caribbean coral reefs

Directory of Open Access Journals (Sweden)

Raúl Navas-Camacho

2010-05-01

Full Text Available Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá. The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10x2m with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2, and Urabá had high numbers with bleaching (54.4 colonies/m2. Of the seven reported coral diseases studied, Dark Spots Disease (DSD, and White Plague Disease (WPD were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A.grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few

Microbial contributions to the persistence of coral reefs.

Science.gov (United States)

Webster, Nicole S; Reusch, Thorsten B H

2017-10-01

On contemplating the adaptive capacity of reef organisms to a rapidly changing environment, the microbiome offers significant and greatly unrecognised potential. Microbial symbionts contribute to the physiology, development, immunity and behaviour of their hosts, and can respond very rapidly to changing environmental conditions, providing a powerful mechanism for acclimatisation and also possibly rapid evolution of coral reef holobionts. Environmentally acquired fluctuations in the microbiome can have significant functional consequences for the holobiont phenotype upon which selection can act. Environmentally induced changes in microbial abundance may be analogous to host gene duplication, symbiont switching / shuffling as a result of environmental change can either remove or introduce raw genetic material into the holobiont; and horizontal gene transfer can facilitate rapid evolution within microbial strains. Vertical transmission of symbionts is a key feature of many reef holobionts and this would enable environmentally acquired microbial traits to be faithfully passed to future generations, ultimately facilitating microbiome-mediated transgenerational acclimatisation (MMTA) and potentially even adaptation of reef species in a rapidly changing climate. In this commentary, we highlight the capacity and mechanisms for MMTA in reef species, propose a modified Price equation as a framework for assessing MMTA and recommend future areas of research to better understand how microorganisms contribute to the transgenerational acclimatisation of reef organisms, which is essential if we are to reliably predict the consequences of global change for reef ecosystems.

Coral reefs in an urban embayment in Hawaii: a complex case history controlled by natural and anthropogenic stress

Science.gov (United States)

Grigg, R. W.

1995-11-01

The effects of natural and anthropogenic stress need to be separated before coral reef ecosystems can be effectively managed. In this paper, a 25 year case history of coral reefs in an urban embayment (Mamala Bay) off Honolulu, Hawaii is described and differences between natural and man-induced stress are distinguished. Mamala Bay is a 30 km long shallow coastal bay bordering the southern (leeward) shore of Oahu and the city of Honolulu in the Hawaiian Islands. During the last 25 years, this area has been hit by two magnitude 5 hurricane events (winds > 240 km/h) generating waves in excess of 7.5 m. Also during this period, two large sewer outfalls have discharged up to 90 million gallons per day (mgd) or (360 × 106 L/day) of point source pollution into the bay. Initially the discharge was raw sewage, but since 1977 it has received advanced primary treatment. Non-point source run-off from the Honolulu watershed also enters the bay on a daily basis. The results of the study show that discharge of raw sewage had a serious but highly localized impact on shallow (˜10 m) reef corals in the bay prior to 1977. After 1977, when treatment was upgraded to the advanced primary level and outfalls were extended to deep water (> 65 m), impacts to reef corals were no longer significant. No measurable effects of either point or non-point source pollution on coral calcification, growth, species composition, diversity or community structure related to pollution can now be detected. Conversely the effects of hurricane waves in 1982 and 1992 together caused major physical destruction to the reefs. In 1982, average coral cover of well-developed offshore reefs dropped from 60-75% to 5-15%. Only massive species in high relief areas survived. Today, recovery is occurring, and notwithstanding major future disturbance events, long-term biological processes should eventually return the coral ecosystems to a more mature successional stage. This case history illustrates the complex nature of

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef.

Science.gov (United States)

Hackerott, Serena; Valdivia, Abel; Cox, Courtney E; Silbiger, Nyssa J; Bruno, John F

2017-01-01

Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0-10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef

Directory of Open Access Journals (Sweden)

Serena Hackerott

2017-05-01

Full Text Available Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0–10 cm total length at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

Evaluating the human impact on groundwater quality discharging into a coastal reef lagoon

Science.gov (United States)

Rebolledo-Vieyra, M.; Hernandez-Terrones, L.; Soto, M.; Lecossec, A.; Monroy-Rios, E.

2008-12-01

The Eastern coast of the Yucatan Peninsula has the fastest growth rate in Mexico and groundwater is the only source of drinking water in the region. The consequences of the lack of proper infrastructure to collect and treat wastewater and the impact of human activities on the quality of groundwater are addressed. The groundwater in the coastal aquifer of Quintana Roo (SE Mexico) discharges directly into the ocean. In addition, the coral reef of the Eastern Yucatan Peninsula is part of the Mesoamerican Coral Reef System, one of the largest in the world. The interaction of the reef-lagoon hydraulics with the coastal aquifer of Puerto Morelos (NE Yucatan Peninsula), and a major input of NH4, SO4, SiO2, as a consequence of the use of septic tanks and the lack of modern wastewater treatment plants are presented. No seasonal parameters differences were observed, suggesting that groundwater composition reaching the reef lagoon is not changing seasonally. A conceptual model of the coastal aquifer was developed, in order to explain how the human activities are impacting directly on the groundwater quality that, potentially, will have a direct impact on the coral reef. The protection and conservation of coral reefs must be directly related with a policy of sound management of coastal aquifers and wastewater treatment.

Monitoring the impacts of Ocean Acidification on coral reef bioerosion: challenges, methods, recommendations

Science.gov (United States)

Enochs, I.; Manzello, D.; Carlton, R.

2013-05-01

Coral reef habitats exist as a dynamic balance between the additive process of calcification and the destructive effects of erosion. A disruption to either the positive or negative side of the coral reef carbonate budget can push a reef system towards rapid collapse. It is well understood that Ocean Acidification (OA) may impair calcification and emerging experimental evidence suggests that it will likely increase the erosive potential of a diverse suite of bioeroding taxa. This may lead to previously unforeseen scenarios where reef framework degradation occurs at a faster pace than that predicted by more simplistic models, resulting from the multifaceted impacts of both slower coral growth and enhanced rates of habitat erosion. As such, it is of paramount importance that monitoring plans tasked with assessing reef resilience to climate change and OA incorporate methods for quantifying bioerosion. This is a complex undertaking as reef ecosystem bioerosion is the result of numerous behaviors, employed by diverse flora and fauna, operating at vastly different scales. Furthermore, these erosive processes are highly variable, dependent on seasonal fluctuations and differing between reef regions, species, individuals, and even the physical characteristics of the substrates acted upon. The strengths and weaknesses of existing bioerosion monitoring methodologies are discussed, ranging from quantification of single species erosion rates to multi-phyletic census-based approaches. Traditional techniques involving the weight change of carbonate blocks are compared alongside more modern methodologies such as micro computed tomography. Finally, recommendations are made for a comprehensive monitoring strategy, incorporating multiple methodologies in a time and cost-effective manner.

Predicting climate-driven regime shifts versus rebound potential in coral reefs.

Science.gov (United States)

Graham, Nicholas A J; Jennings, Simon; MacNeil, M Aaron; Mouillot, David; Wilson, Shaun K

2015-02-05

Climate-induced coral bleaching is among the greatest current threats to coral reefs, causing widespread loss of live coral cover. Conditions under which reefs bounce back from bleaching events or shift from coral to algal dominance are unknown, making it difficult to predict and plan for differing reef responses under climate change. Here we document and predict long-term reef responses to a major climate-induced coral bleaching event that caused unprecedented region-wide mortality of Indo-Pacific corals. Following loss of >90% live coral cover, 12 of 21 reefs recovered towards pre-disturbance live coral states, while nine reefs underwent regime shifts to fleshy macroalgae. Functional diversity of associated reef fish communities shifted substantially following bleaching, returning towards pre-disturbance structure on recovering reefs, while becoming progressively altered on regime shifting reefs. We identified threshold values for a range of factors that accurately predicted ecosystem response to the bleaching event. Recovery was favoured when reefs were structurally complex and in deeper water, when density of juvenile corals and herbivorous fishes was relatively high and when nutrient loads were low. Whether reefs were inside no-take marine reserves had no bearing on ecosystem trajectory. Although conditions governing regime shift or recovery dynamics were diverse, pre-disturbance quantification of simple factors such as structural complexity and water depth accurately predicted ecosystem trajectories. These findings foreshadow the likely divergent but predictable outcomes for reef ecosystems in response to climate change, thus guiding improved management and adaptation.

Conservation genetics and the resilience of reef-building corals.

Science.gov (United States)

van Oppen, Madeleine J H; Gates, Ruth D

2006-11-01

Coral reefs have suffered long-term decline due to a range of anthropogenic disturbances and are now also under threat from climate change. For appropriate management of these vulnerable and valuable ecosystems it is important to understand the factors and processes that determine their resilience and that of the organisms inhabiting them, as well as those that have led to existing patterns of coral reef biodiversity. The scleractinian (stony) corals deposit the structural framework that supports and promotes the maintenance of biological diversity and complexity of coral reefs, and as such, are major components of these ecosystems. The success of reef-building corals is related to their obligate symbiotic association with dinoflagellates of the genus Symbiodinium. These one-celled algal symbionts (zooxanthellae) live in the endodermal tissues of their coral host, provide most of the host's energy budget and promote rapid calcification. Furthermore, zooxanthellae are the main primary producers on coral reefs due to the oligotrophic nature of the surrounding waters. In this review paper, we summarize and critically evaluate studies that have employed genetics and/or molecular biology in examining questions relating to the evolution and ecology of reef-building corals and their algal endosymbionts, and that bear relevance to coral reef conservation. We discuss how these studies can focus future efforts, and examine how these approaches enhance our understanding of the resilience of reef-building corals.

Tsunami survey expedition: preliminary investigation of Maldivian coral reefs two weeks after the event.

Science.gov (United States)

Goffredo, Stefano; Piccinetti, Corrado; Zaccanti, Francesco

2007-08-01

On December 26th 2004, a earthquake west of Sumatra generated a devastating tsunami. Hundreds of thousands of people fell victim. Economic losses were greatest in those countries dependant on tourism. The impact in the Maldives on persons and things was modest. Immediately following the event and notwithstanding the lack of scientific data, the mass media gave catastrophic reports on the state of coral reefs in the area. This paper reports on the first survey on coral reefs in the Maldives after the Tsunami. Ocean walls, passes, inner reefs, and shoals in the North and South Malé atolls, were surveyed two weeks after the event. Significant damage was recorded in the passes in the South Malé atoll. Our observations showed that the damage was more or less extensive depending on latitude and topography. Sri Lanka may have broken the wave's rush, reducing the extent of the impact on northern atolls. The water's acceleration inside the passes was so intense as to cause reef collapses. The observed damage represents a minimum fraction of the entire coral reef system. Tourist perception of the area seems unchanged. These data may be used to disseminate correct information about the state of Maldives coral reefs, which would be useful in relaunching local economy.

Identifying the ichthyoplankton of a coral reef using DNA barcodes.

Science.gov (United States)

Hubert, Nicolas; Espiau, Benoit; Meyer, Christopher; Planes, Serge

2015-01-01

Marine fishes exhibit spectacular phenotypic changes during their ontogeny, and the identification of their early stages is challenging due to the paucity of diagnostic morphological characters at the species level. Meanwhile, the importance of early life stages in dispersal and connectivity has recently experienced an increasing interest in conservation programmes for coral reef fishes. This study aims at assessing the effectiveness of DNA barcoding for the automated identification of coral reef fish larvae through large-scale ecosystemic sampling. Fish larvae were mainly collected using bongo nets and light traps around Moorea between September 2008 and August 2010 in 10 sites distributed in open waters. Fish larvae ranged from 2 to 100 mm of total length, with the most abundant individuals being <5 mm. Among the 505 individuals DNA barcoded, 373 larvae (i.e. 75%) were identified to the species level. A total of 106 species were detected, among which 11 corresponded to pelagic and bathypelagic species, while 95 corresponded to species observed at the adult stage on neighbouring reefs. This study highlights the benefits and pitfalls of using standardized molecular systems for species identification and illustrates the new possibilities enabled by DNA barcoding for future work on coral reef fish larval ecology. © 2014 John Wiley & Sons Ltd.

Changes in Reef Fish Abundances Associated with the Introduction of Indo-Pacific Lionfish to the Florida Keys National Marine Sanctuary: a Twenty Year Time Series.

Science.gov (United States)

Hepner, M.; Muller-Karger, F. E.; Gittings, S.; Stallings, C.

2016-02-01

The Marine Biodiversity Observation Network (MBON) is a partnership between academic, private, and government researchers seeking to understand how marine biodiversity changes over long periods of time. In this context, a study of the multi-agency Reef Visual Census (RVC) data, collected over twenty years in the Florida Keys National Marine Sanctuary (FKNMS), was analyzed to measure possible changes in reef fish abundances as a result of possible predation by lionfish predation or due to related trophic cascading. Lionfish were first sighted in the FKNMS in January 2009, with abundances and frequency of occurrence increasing three to six fold throughout the sanctuary by 2011. Their high consumption rates of smaller fish, coupled with their rapidly increasing densities may be having a significant effect on coral reef fish communities. The study compares the natural variability in reef fish abundances from 1994-2009 in the FKNMS, 15 years prior to the first lionfish detected in the sanctuary, to changes in reef fish abundances 5 years after the invasion. The MBON project also aims to develop environmental DNA (eDNA) technology for conducting biodiversity assessments. eDNA is an emerging technique that seeks to quantify biodiversity in an area by obtaining genetic material directly from environmental samples (soil, sediment, water, etc.) without any obvious signs of biological source material. All marine organisms shed DNA into their surrounding habitat, leaving a "fingerprint." Similar to forensic science, the DNA can be collected from seawater and analyzed to determine what species were recently present. The MBON team is evaluating whether eDNA can be used to adequately monitor reef fish biodiversity in coral reef ecosystems. We will compare species detected in our samples to the taxonomic composition of reef fish communities at the sample site as recorded over the past twenty years in the Reef Visual Census data.

Shifting paradigms in restoration of the world's coral reefs.

Science.gov (United States)

van Oppen, Madeleine J H; Gates, Ruth D; Blackall, Linda L; Cantin, Neal; Chakravarti, Leela J; Chan, Wing Y; Cormick, Craig; Crean, Angela; Damjanovic, Katarina; Epstein, Hannah; Harrison, Peter L; Jones, Thomas A; Miller, Margaret; Pears, Rachel J; Peplow, Lesa M; Raftos, David A; Schaffelke, Britta; Stewart, Kristen; Torda, Gergely; Wachenfeld, David; Weeks, Andrew R; Putnam, Hollie M

2017-09-01

Many ecosystems around the world are rapidly deteriorating due to both local and global pressures, and perhaps none so precipitously as coral reefs. Management of coral reefs through maintenance (e.g., marine-protected areas, catchment management to improve water quality), restoration, as well as global and national governmental agreements to reduce greenhouse gas emissions (e.g., the 2015 Paris Agreement) is critical for the persistence of coral reefs. Despite these initiatives, the health and abundance of corals reefs are rapidly declining and other solutions will soon be required. We have recently discussed options for using assisted evolution (i.e., selective breeding, assisted gene flow, conditioning or epigenetic programming, and the manipulation of the coral microbiome) as a means to enhance environmental stress tolerance of corals and the success of coral reef restoration efforts. The 2014-2016 global coral bleaching event has sharpened the focus on such interventionist approaches. We highlight the necessity for consideration of alternative (e.g., hybrid) ecosystem states, discuss traits of resilient corals and coral reef ecosystems, and propose a decision tree for incorporating assisted evolution into restoration initiatives to enhance climate resilience of coral reefs. © 2017 John Wiley & Sons Ltd.

Coral reefs as indicators of marine environmental health

International Nuclear Information System (INIS)

Kumaraguru, A.K.

2007-01-01

Coral reefs are one of the most productive and diverse of all ecosystems on the Earth. Although they occupy less than 0.25 percent of the marine environment, the reefs support more than a quarter of all known fish species. They serve as critical habitats for numerous tropical species including reef fishes of ornamental nature and edible fishes. They protect the shores from storms and wave actions

Seascape and life-history traits do not predict self-recruitment in a coral reef fish

KAUST Repository

Herrera Sarrias, Marcela

2016-08-10

The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4-0.5% at 0.15 km2) and the lagoon scale (0.6-0.8% at approx. 700 km2). While approximately 25%of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes. © 2016 The Authors.

Coral reefs for coastal protection: A new methodological approach and engineering case study in Grenada.

Science.gov (United States)

Reguero, Borja G; Beck, Michael W; Agostini, Vera N; Kramer, Philip; Hancock, Boze

2018-03-15

Coastal communities in tropical environments are at increasing risk from both environmental degradation and climate change and require urgent local adaptation action. Evidences show coral reefs play a critical role in wave attenuation but relatively little direct connection has been drawn between these effects and impacts on shorelines. Reefs are rarely assessed for their coastal protection service and thus not managed for their infrastructure benefits, while widespread damage and degradation continues. This paper presents a systematic approach to assess the protective role of coral reefs and to examine solutions based on the reef's influence on wave propagation patterns. Portions of the shoreline of Grenville Bay, Grenada, have seen acute shoreline erosion and coastal flooding. This paper (i) analyzes the historical changes in the shoreline and the local marine, (ii) assess the role of coral reefs in shoreline positioning through a shoreline equilibrium model first applied to coral reef environments, and (iii) design and begin implementation of a reef-based solution to reduce erosion and flooding. Coastline changes in the bay over the past 6 decades are analyzed from bathymetry and benthic surveys, historical imagery, historical wave and sea level data and modeling of wave dynamics. The analysis shows that, at present, the healthy and well-developed coral reefs system in the southern bay keeps the shoreline in equilibrium and stable, whereas reef degradation in the northern bay is linked with severe coastal erosion. A comparison of wave energy modeling for past bathymetry indicates that degradation of the coral reefs better explains erosion than changes in climate and historical sea level rise. Using this knowledge on how reefs affect the hydrodynamics, a reef restoration solution is designed and studied to ameliorate the coastal erosion and flooding. A characteristic design provides a modular design that can meet specific engineering, ecological and

Reef demise and back-stepping during the last interglacial, northeast Yucatan

Science.gov (United States)

Blanchon, Paul

2010-06-01

The elevation of reefs and coastal deposits during the last Interglaciation (MIS-5e) indicates that sea level reached a highstand of as much as 6 m above the present, but it is uncertain how rapidly this level was attained and how it impacted reef development. To investigate this problem, I made a detailed sedimentological analysis of a well-dated reef from the northeast coast of the stable Yucatan Peninsula. Two linear reef tracts were delineated which are offset and at different elevations. The lower reef tract crops out along northern shore for 575 m and extends from below present mean sea level to +3 m. The reef crest facies consists of large Acropora palmata colonies dispersed within a coral boulder-gravel and is flanked by an A. cervicornis-dominated reef-front and a large area of lagoonal framework formed by coalesced patches of A. cervicornis and Montastraea spp. Constituents in the upper centimetre of the lower tract are heavily encrusted by a cap of crustose corallines and, in places, are levelled by a discontinuous marine-erosion surface. The upper reef tract crops out ~150 m inland up to an elevation of +5.8 m and parallels the southern section of shore for ~400 m. It also consist of an A. palmata-dominated crest facies flanked by reef-front, back-reef and lagoonal frameworks. In this case, however, lagoonal frameworks are dominated by a sediment-tolerant assemblage of branching coralline algae. Also different is the lack of encrustation by corallines, and the infiltration of upper tract facies by beach-derived shell-gravels from regressive shoreface deposits above. These results indicate that the lower reef tract and lagoonal patch-reefs formed at a sea level of +3 m. Final capping by crustose corallines and discontinuous marine erosion indicates that the lower tract was terminated by the complete demise of corals on the crest but only patchy demise in the lagoon. Areas of continuous framework accretion between the lagoonal patch reefs and the upper

Hyperspectral remote sensing of wild oyster reefs

Science.gov (United States)

Le Bris, Anthony; Rosa, Philippe; Lerouxel, Astrid; Cognie, Bruno; Gernez, Pierre; Launeau, Patrick; Robin, Marc; Barillé, Laurent

2016-04-01

The invasion of the wild oyster Crassostrea gigas along the western European Atlantic coast has generated changes in the structure and functioning of intertidal ecosystems. Considered as an invasive species and a trophic competitor of the cultivated conspecific oyster, it is now seen as a resource by oyster farmers following recurrent mass summer mortalities of oyster spat since 2008. Spatial distribution maps of wild oyster reefs are required by local authorities to help define management strategies. In this work, visible-near infrared (VNIR) hyperspectral and multispectral remote sensing was investigated to map two contrasted intertidal reef structures: clusters of vertical oysters building three-dimensional dense reefs in muddy areas and oysters growing horizontally creating large flat reefs in rocky areas. A spectral library, collected in situ for various conditions with an ASD spectroradiometer, was used to run Spectral Angle Mapper classifications on airborne data obtained with an HySpex sensor (160 spectral bands) and SPOT satellite HRG multispectral data (3 spectral bands). With HySpex spectral/spatial resolution, horizontal oysters in the rocky area were correctly classified but the detection was less efficient for vertical oysters in muddy areas. Poor results were obtained with the multispectral image and from spatially or spectrally degraded HySpex data, it was clear that the spectral resolution was more important than the spatial resolution. In fact, there was a systematic mud deposition on shells of vertical oyster reefs explaining the misclassification of 30% of pixels recognized as mud or microphytobenthos. Spatial distribution maps of oyster reefs were coupled with in situ biomass measurements to illustrate the interest of a remote sensing product to provide stock estimations of wild oyster reefs to be exploited by oyster producers. This work highlights the interest of developing remote sensing techniques for aquaculture applications in coastal

Plastic waste associated with disease on coral reefs.

Science.gov (United States)

Lamb, Joleah B; Willis, Bette L; Fiorenza, Evan A; Couch, Courtney S; Howard, Robert; Rader, Douglas N; True, James D; Kelly, Lisa A; Ahmad, Awaludinnoer; Jompa, Jamaluddin; Harvell, C Drew

2018-01-26

Plastic waste can promote microbial colonization by pathogens implicated in outbreaks of disease in the ocean. We assessed the influence of plastic waste on disease risk in 124,000 reef-building corals from 159 reefs in the Asia-Pacific region. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. Structurally complex corals are eight times more likely to be affected by plastic, suggesting that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately affected. Plastic levels on coral reefs correspond to estimates of terrestrial mismanaged plastic waste entering the ocean. We estimate that 11.1 billion plastic items are entangled on coral reefs across the Asia-Pacific and project this number to increase 40% by 2025. Plastic waste management is critical for reducing diseases that threaten ecosystem health and human livelihoods. Copyright © 2018, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

U.S. coral reefs; imperiled national treasures

Science.gov (United States)

Field, M.E.; Cochran, S.A.; Evans, K.R.

2002-01-01

Coral reefs are home to 25% of all marine species. However, the tiny colonial animals that build these intricate limestone masses are dying at alarming rates. If this trend continues, in 20 years the living corals on many of the world's reefs will be dead and the ecosystems that depend on them severely damaged. As part of the effort to protect our Nation's extensive reefs, U.S. Geological Survey (USGS) scientists are working to better understand the processes that affect the health of these ecologically and economically important ecosystems.

Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic reefs.

Science.gov (United States)

Kikuchi, Ruy K P; Leão, Zelinda M A N; Oliveira, Marília D M

2010-05-01

Coral reefs along the Eastern Brazilian coast extend for a distance of 800 km from 12 degrees to 18 degrees S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90's in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA) Regional Node of the Global Coral Reef Monitoring Network (GCRMN) by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts) and similarity percentages (SIMPER) tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonics > 20cm per reef site) and of the coral recruits (colonies coast, are in poorer condition than the reefs located more than 5 km off the coast. A higher density of coral colonies, lower macroalgal index, higher relative percent of turf algae and higher density of coral recruits in offshore reefs compared to the nearshore reefs are the conditions that contribute more than 80% to the dissimilarity between them. The offshore reefs are in better vital condition than the nearshore reefs and have a set of vitality indices more closely related to the Northwestern Atlantic reefs than the nearshore reef. These have been most severely impacted by the effects of direct

Human disturbances on coral reefs in Sri Lanka: A case study

Energy Technology Data Exchange (ETDEWEB)

Oehman, M C; Linden, O [Stockholm Univ. (Sweden). Dept. of Zoology; Rajasuriya, A [NARA, Crow Island, Colombo (Sri Lanka)

1993-01-01

The degradation of coral reefs in Sri Lanka has increased substantially over the last decades. Human activities causing this degradation include: mining for lime production, sewage discharges, discharges of oil and other pollutants in connection with shipping and port activities, destructive fishing practices, land and mangrove destruction, tourism and the collecting of fauna such as fish, shells and corals. In this study, three adjacent coral reefs; Bar Reef, Talawila Reef, and Kandakuliya Reef, which are widely scattered patch reefs off Kalpitiya Peninsula, northwestern Sri Lanka, were surveyed and compared in terms of their fish and coral diversity and abundance as well as human and natural disturbances. Information was gathered by snorkeling in visual overview surveys and by scuba diving in detailed transect surveys. When each reef was ranked according to the extent of live coral cover, and chaetodontid diversity, the results indicated that Bar Reef was in excellent condition, Talawila Reef was intermediate, and Kandakuliya Reef was in poor condition. The diversity of coral genera, the topographic relief and the proportion of coral rubble, did not follow the same pattern. The number of coral genera found was 49, while 283 fish species belonging to 51 families were recorded. Human disturbance factors on the reefs were found to be net fishing, boat anchoring and ornamental fish collection for the aquarium trade. Bottom.set nylon nets in particular were found to have a very destructive impact on the bottom fauna. 33 refs, 7 figs, 1 tab

Coral Reef Ecosystems under Climate Change and Ocean Acidification

Directory of Open Access Journals (Sweden)

Ove Hoegh-Guldberg

2017-05-01

Full Text Available Coral reefs are found in a wide range of environments, where they provide food and habitat to a large range of organisms as well as providing many other ecological goods and services. Warm-water coral reefs, for example, occupy shallow sunlit, warm, and alkaline waters in order to grow and calcify at the high rates necessary to build and maintain their calcium carbonate structures. At deeper locations (40–150 m, “mesophotic” (low light coral reefs accumulate calcium carbonate at much lower rates (if at all in some cases yet remain important as habitat for a wide range of organisms, including those important for fisheries. Finally, even deeper, down to 2,000 m or more, the so-called “cold-water” coral reefs are found in the dark depths. Despite their importance, coral reefs are facing significant challenges from human activities including pollution, over-harvesting, physical destruction, and climate change. In the latter case, even lower greenhouse gas emission scenarios (such as Representative Concentration Pathway RCP 4.5 are likely drive the elimination of most warm-water coral reefs by 2040–2050. Cold-water corals are also threatened by warming temperatures and ocean acidification although evidence of the direct effect of climate change is less clear. Evidence that coral reefs can adapt at rates which are sufficient for them to keep up with rapid ocean warming and acidification is minimal, especially given that corals are long-lived and hence have slow rates of evolution. Conclusions that coral reefs will migrate to higher latitudes as they warm are equally unfounded, with the observations of tropical species appearing at high latitudes “necessary but not sufficient” evidence that entire coral reef ecosystems are shifting. On the contrary, coral reefs are likely to degrade rapidly over the next 20 years, presenting fundamental challenges for the 500 million people who derive food, income, coastal protection, and a range of

Comparative visual ecophysiology of mid-Atlantic temperate reef fishes

Directory of Open Access Journals (Sweden)

Andrij Z. Horodysky

2013-11-01

The absolute light sensitivities, temporal properties, and spectral sensitivities of the visual systems of three mid-Atlantic temperate reef fishes (Atlantic spadefish [Ephippidae: Chaetodipterus faber], tautog [Labridae: Tautoga onitis], and black sea bass [Serranidae: Centropristis striata] were studied via electroretinography (ERG. Pelagic Atlantic spadefish exhibited higher temporal resolution but a narrower dynamic range than the two more demersal foragers. The higher luminous sensitivities of tautog and black sea bass were similar to other benthic and demersal coastal mid-Atlantic fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of the three species spanned 400–610 nm, with high likelihood of cone dichromacy providing the basis for color and contrast discrimination. Significant day-night differences in spectral responses were evident in spadefish and black sea bass but not tautog, a labrid with characteristic structure-associated nocturnal torpor. Atlantic spadefish responded to a wider range of wavelengths than did deeper-dwelling tautog or black sea bass. Collectively, these results suggest that temperate reef-associated fishes are well-adapted to their gradient of brighter to dimmer photoclimates, representative of their unique ecologies and life histories. Continuing anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may however impede visual foraging and reproductive signaling in temperate reef fishes.

Remote Sensing Tropical Coral Reefs: The View from Above

Science.gov (United States)

Purkis, Sam J.

2018-01-01

Carbonate precipitation has been a common life strategy for marine organisms for 3.7 billion years, as, therefore, has their construction of reefs. As favored by modern corals, reef-forming organisms have typically adopted a niche in warm, shallow, well-lit, tropical marine waters, where they are capable of building vast carbonate edifices. Because fossil reefs form water aquifers and hydrocarbon reservoirs, considerable effort has been dedicated to understanding their anatomy and morphology. Remote sensing has a particular role to play here. Interpretation of satellite images has done much to reveal the grand spatial and temporal tapestry of tropical reefs. Comparative sedimentology, whereby modern environments are contrasted with the rock record to improve interpretation, has been particularly transformed by observations made from orbit. Satellite mapping has also become a keystone technology to quantify the coral reef crisis—it can be deployed not only directly to quantify the distribution of coral communities, but also indirectly to establish a climatology for their physical environment. This article reviews the application of remote sensing to tropical coralgal reefs in order to communicate how this fast-growing technology might be central to addressing the coral reef crisis and to look ahead at future developments in the science.

Remote Sensing Tropical Coral Reefs: The View from Above.

Science.gov (United States)

Purkis, Sam J

2018-01-03

Carbonate precipitation has been a common life strategy for marine organisms for 3.7 billion years, as, therefore, has their construction of reefs. As favored by modern corals, reef-forming organisms have typically adopted a niche in warm, shallow, well-lit, tropical marine waters, where they are capable of building vast carbonate edifices. Because fossil reefs form water aquifers and hydrocarbon reservoirs, considerable effort has been dedicated to understanding their anatomy and morphology. Remote sensing has a particular role to play here. Interpretation of satellite images has done much to reveal the grand spatial and temporal tapestry of tropical reefs. Comparative sedimentology, whereby modern environments are contrasted with the rock record to improve interpretation, has been particularly transformed by observations made from orbit. Satellite mapping has also become a keystone technology to quantify the coral reef crisis-it can be deployed not only directly to quantify the distribution of coral communities, but also indirectly to establish a climatology for their physical environment. This article reviews the application of remote sensing to tropical coralgal reefs in order to communicate how this fast-growing technology might be central to addressing the coral reef crisis and to look ahead at future developments in the science.

Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic Reefs

Directory of Open Access Journals (Sweden)

Ruy K.P Kikuchi

2010-05-01

Full Text Available Coral reefs along the Eastern Brazilian coast extend for a distance of 800km from 12° to 18°S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90’s in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA Regional Node of the Global Coral Reef Monitoring Network (GCRMN by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts and similarity percentages (SIMPER tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonies >20cm per reef site and of the coral recruits (colonies<2cm per square meter, and the percentage of macroalgae indicate that the nearshore reefs, which are located less than 5km from the coast, are in poorer condition than the reefs located more than 5km off the coast. A higher density of coral colonies, lower macroalgal index, higher relative percent of turf algae and higher density of coral recruits in offshore reefs compared to the nearshore reefs are the conditions that contribute more than 80% to the dissimilarity between them. The offshore reefs are in better vital condition than the nearhore reefs and have a set of vitality indices more closely

National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in the Northwestern Hawaiian Islands from Water Samples collected in 2015 (NCEI Accession 0160330)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and...

Coral-macroalgal phase shifts or reef resilience: links with diversity and functional roles of herbivorous fishes on the Great Barrier Reef

Science.gov (United States)

Cheal, A. J.; MacNeil, M. Aaron; Cripps, E.; Emslie, M. J.; Jonker, M.; Schaffelke, B.; Sweatman, H.

2010-12-01

Changes from coral to macroalgal dominance following disturbances to corals symbolize the global degradation of coral reefs. The development of effective conservation measures depends on understanding the causes of such phase shifts. The prevailing view that coral-macroalgal phase shifts commonly occur due to insufficient grazing by fishes is based on correlation with overfishing and inferences from models and small-scale experiments rather than on long-term quantitative field studies of fish communities at affected and resilient sites. Consequently, the specific characteristics of herbivorous fish communities that most promote reef resilience under natural conditions are not known, though this information is critical for identifying vulnerable ecosystems. In this study, 11 years of field surveys recorded the development of the most persistent coral-macroalgal phase shift (>7 years) yet observed on Australia’s Great Barrier Reef (GBR). This shift followed extensive coral mortality caused by thermal stress (coral bleaching) and damaging storms. Comparisons with two similar reefs that suffered similar disturbances but recovered relatively rapidly demonstrated that the phase shift occurred despite high abundances of one herbivore functional group (scraping/excavating parrotfishes: Labridae). However, the shift was strongly associated with low fish herbivore diversity and low abundances of algal browsers (predominantly Siganidae) and grazers/detritivores (Acanthuridae), suggesting that one or more of these factors underpin reef resilience and so deserve particular protection. Herbivorous fishes are not harvested on the GBR, and the phase shift was not enhanced by unusually high nutrient levels. This shows that unexploited populations of herbivorous fishes cannot ensure reef resilience even under benign conditions and suggests that reefs could lose resilience under relatively low fishing pressure. Predictions of more severe and widespread coral mortality due to global

UNEP-IOC-WMO-IUCN meeting of experts on a long-term global monitoring system of coastal and near-shore phenomena related to climate change, pilot projects and mangroves and coral reefs

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

This meeting was held to develop strategies for long-term global monitoring of coastal and near-shore phenomena related to climate change, specifically mangroves and coral reefs. The agenda included an overview of the Global Ocean Observing System (GOOS) initiative, modules and pilot phase activities. Action plans for the implementation of long-term monitoring of mangrove and coral reef ecosystems were developed including; potential impacts of climate change and sea level rise on mangroves and coral reefs, consideration of parameters, consideration of methodologies, relationships of proposed activities to relevant national, regional and international developments, consideration of monitoring sites, and future implementation.

Climate-driven coral reorganisation influences aggressive behaviour in juvenile coral-reef fishes

Science.gov (United States)

Kok, Judith E.; Graham, Nicholas A. J.; Hoogenboom, Mia O.

2016-06-01

Globally, habitat degradation is altering the abundance and diversity of species in a variety of ecosystems. This study aimed to determine how habitat degradation, in terms of changing coral composition under climate change, affected abundance, species richness and aggressive behaviour of juveniles of three damselfishes ( Pomacentrus moluccensis, P. amboinensis and Dischistodus perspicillatus, in order of decreasing reliance on coral). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced coral bleaching, and reefs with more bleaching-robust coral taxa, thereby simulating the likely future of coral reefs under a warming climate. Fish communities were allowed to establish naturally on the reefs during the summer recruitment period. Climate-robust reefs had lower total species richness of coral-reef fishes than climate-vulnerable reefs, but total fish abundance was not significantly different between reef types (pooled across all species and life-history stages). The nature of aggressive interactions, measured as the number of aggressive chases, varied according to coral composition; on climate-robust reefs, juveniles used the substratum less often to avoid aggression from competitors, and interspecific aggression became relatively more frequent than intraspecific aggression for juveniles of the coral-obligate P. moluccensis. This study highlights the importance of coral composition as a determinant of behaviour and diversity of coral-reef fishes.

The structure and composition of Holocene coral reefs in the Middle Florida Keys

Science.gov (United States)

Toth, Lauren T.; Stathakopoulos, Anastasios; Kuffner, Ilsa B.

2016-07-21

The Florida Keys reef tract (FKRT) is the largest coral-reef ecosystem in the continental United States. The modern FKRT extends for 362 kilometers along the coast of South Florida from Dry Tortugas National Park in the southwest, through the Florida Keys National Marine Sanctuary (FKNMS), to Fowey Rocks reef in Biscayne National Park in the northeast. Most reefs along the FKRT are sheltered by the exposed islands of the Florida Keys; however, large channels are located between the islands of the Middle Keys. These openings allow for tidal transport of water from Florida Bay onto reefs in the area. The characteristics of the water masses coming from Florida Bay, which can experience broad swings in temperature, salinity, nutrients, and turbidity over short periods of time, are generally unfavorable or “inimical” to coral growth and reef development.Although reef habitats are ubiquitous throughout most of the Upper and Lower Keys, relatively few modern reefs exist in the Middle Keys most likely because of the impacts of inimical waters from Florida Bay. The reefs that are present in the Middle Keys generally are poorly developed compared with reefs elsewhere in the region. For example, Acropora palmata has been the dominant coral on shallow-water reefs in the Caribbean over the last 1.5 million years until populations of the coral declined throughout the region in recent decades. Although A. palmata was historically abundant in the Florida Keys, it was conspicuously absent from reefs in the Middle Keys. Instead, contemporary reefs in the Middle Keys have been dominated by occasional massive (that is, boulder or head) corals and, more often, small, non-reef-building corals.Holocene reef cores have been collected from many locations along the FKRT; however, despite the potential importance of the history of reefs in the Middle Florida Keys to our understanding of the environmental controls on reef development throughout the FKRT, there are currently no published