Boore, Jeffrey L.; Staton, Joseph
We have determined the sequence of about half (7470 nts) of the mitochondrial genome of the sipunculid Phascolopsis gouldii, the first representative of this phylum to be so studied. All of the 19 identified genes are transcribed from the same DNA strand. The arrangement of these genes is remarkably similar to that of the oligochaete annelid Lumbricus terrestris. Comparison of both the inferred amino acid sequences and the gene arrangements of a variety of diverse metazoan taxa reveals that the phylum Sipuncula is more closely related to Annelida than to Mollusca. This requires reinterpretation of the homology of several embryological features and of patterns of animal body plan evolution.
Thomas, S P
The energetic cost of flight in a wind-tunnel was measured at various combinations of speed and flight angle from two species of bats whose body masses differ by almost an order of magnitude. The highest mean metabolic rate per unit body mass measured from P. hastatus (mean body mass, 0.093 kg) was 130.4 Wkg-1, and that for P. gouldii (mean body mass, 0.78 kg) was 69.6 Wkg-1. These highest metabolic rates, recorded from flying bats, are essentially the same as those predicted for flying birds of the same body masses, but are from 2.5 to 3.0 times greater than the highest metabolic rates of which similar-size exercising terrestrial mammals appear capable. The lowest mean rate of energy utilization per unit body mass P. hastatus required to sustain level flight was 94.2 Wkg-1 and that for P. gouldii was 53.4 Wkg-1. These data from flying bats together with comparable data for flying birds all fall along a straight line when plotted on double logarithmic coordinates as a function of body mass. Such data show that even the lowest metabolic requirements of bats and birds during level flight are about twice the highest metabolic capabilities of similar-size terrestrial mammals. Flying bats share with flying birds the ability to move substantially greater distance per unit energy consumed than walking or running mammals. Calculations show that P. hastatus requires only one-sixth the energy to cover a given distance as does the same-size terrestrial mammal, while P. gouldii requires one-fourth the energy of the same-size terrestrial mammal. An empirically derived equation is presented which enables one to make estimates of the metabolic rates of bats and birds during level flight in nature from body mass data alone. Metabolic data obtained in this study are compared with predictions calculated from an avian flight theory.
Full Text Available Southwest Australia (SWA is a global biodiversity hotspot and a centre of diversity and endemism for the Australo-Papuan myobatrachid frogs. Myobatrachus gouldii (the turtle frog has a highly derived morphology associated with its forward burrowing behaviour, largely subterranean habit, and unusual mode of reproduction. Its sister genera Metacrinia and Arenophryne have restricted distributions in Western Australia with significant phylogeographic structure, leading to the recent description of a new species in the latter. In contrast, Myobatrachus is distributed widely throughout SWA over multiple climatic zones, but little is known of its population structure, geographic variation in morphology, or reproduction. We generated molecular and morphological data to test for genetic and morphological variation, and to assess whether substrate specialisation in this species may have led to phylogeographic structuring similar to that of other plant and animal taxa in SWA. We assembled sequence data for one mitochondrial and four nuclear DNA loci (3628 base pairs for 42 turtle frogs sampled throughout their range. Likelihood phylogenetic analyses revealed shallow phylogeographic structure in the mtDNA locus (up to 3.3% genetic distance and little variation in three of the four nDNA loci. The mtDNA haplotype network suggests five geographically allopatric groups, with no shared haplotypes between regions. These geographic patterns are congruent with several other SWA species, with genetic groups restricted to major hydrological divisions, the Swan Coastal Plain, and the Darling Scarp. The geographically structured genetic groups showed no evidence of significant morphological differentiation (242 individuals, and there was little sexual size dimorphism, but subtle differences in reproductive traits suggest more opportunistic breeding in lower rainfall zones. Call data were compared to sister genera Metacrinia and Arenophryne and found to be highly
appears to be the meticulous work of Feng (1962, 1965, etc) on the oyster, Crassostrea vir- ginica. Also, there are groups of animals ... Work is also in progress on the sipunculid,. Golfingia, and the tunicate, Ciona. ..... REFERENCES. BAXTER, E. w. 1960. Combined oil-immersion, phase-contrast and dark-ground viewing of.
Nolella stipate 1 Phylum S ipuncula Sipunculid (undet.) 14 Phylum Echiura Echiurid (undet.) 1 Phylum-. Annelida Hvdroides dianthus 27 Sabellaria...undet.) LEr-idomotus subievi.s Sab)ellaria \\’ulgaris HIvdroides dianthus 9 lu- Mloliusca * Polinices duplicatus0 Modiclus mocilolus squarnosus...tenuis Microporella ciliata Schizoporella cornuta Phvlum Annelida H-vdroides dianthus Sabelliaria x’ulgaris 41Ph’iu MToi 7lusca Creoidula olana Phylum
Tahani El Ayari
Full Text Available To better understand the impacts of biofouling on the biological processes of the basibiont, the effects of epibiotic barnacles on the relative growth and reproductive indices of Stramonita haemastoma (Linnaeus, 1767 were assessed. A total of 1035 specimens were collected monthly for one year from Bizerta Channel (northern Tunisia. Endobiotic species comprised the lithophagous bivalves Lithophaga aristata and Rocellaria dubia of different sizes, communicating with the outside through tiny perforations. Intra-shell tunnels and galleries also sheltered annelids and sipunculids. Epibiotic species comprised algae and highly diversified invertebrates represented by crustaceans, polychaetes, molluscs, echinoderms, ascidians, sponges, bryozoans and sipunculids, with barnacles being the most common group. Comparison of growth features between non-fouled and fouled S. haemastoma revealed higher growth in non-fouled specimens. Differences in reproductive condition indices were detected in few months, being mostly higher in non-fouled snails, but showed no asynchrony in the spawning period for either fouled or non-fouled gastropods hosts.
Full Text Available Specimens of Mustelus punctulatus were collected between January 2002 and December 2005 from commercial fisheries in the Gulf of Gabès (central Mediterranean Sea. Males and females reached a maximum total length (TL of 111 and 122 cm respectively. Males matured between 76 and 88.5 cm TL, with a size at maturity (TL50 of 81.4 cm TL. Females matured between 88 and 100 cm TL with a TL50 of 95.6 cm. Females had an annual reproductive cycle. Mating occurred through late-May and June. Ovulation occurred from early July to mid-August with parturition occurring from mid-May to early June, after a gestation period of 11 months. The size at birth was estimated to be 24.5 to 30.5 cm TL. Positive linear relationships were detected between the TL of mature females and ovarian and uterine fecundities. Mustelus punctulatus is an opportunistic predator that consumes a wide range of demersal and benthic prey items. It preys mainly on crustaceans, teleosts and molluscs. Polychaetes, sipunculids, echinoderms and tunicates are also consumed. The species change their main food item as they grow, from crustaceans to teleosts then to molluscs.
Chen, Tianran; Li, Shu; Yu, Kefu
Bioerosion is an important limiting factor in carbonate accretion and reef framework development; however, few studies have quantified the direct impact of macroborers on high-latitude coral communities, which are viewed as potential refuge during a period of global warming. In this study, internal macrobioerosion of Porites corals was examined at Daya Bay, subtropical northern South China Sea. The principal borers were the bivalve Lithophaga spp. and the sponges Cliona spp. and Cliothosa spp. (≥80 %), while sipunculid and polychaete worms and barnacles accounted for small amounts of bioerosion (≤20 %). Porites corals were heavily bioeroded in areas impacted by aquacultural and urban activities (10.34-27.55 %) compared with corals in relatively unpolluted areas (2.18-6.76 %). High levels of bioerosion, especially boring bivalve infestation, significantly weaken the corals and increase their susceptibility to dislodgement and fragmentation in typhoons, limiting accumulation of limestone framework. This study implies that carbonate accretion and reef development for high-latitude coral communities may be limited in future high-CO2 and eutrophication-stressed environments.
Rountrey, Adam N; Coulson, Peter G; Meeuwig, Jessica J; Meekan, Mark
Ecological modeling shows that even small, gradual changes in body size in a fish population can have large effects on natural mortality, biomass, and catch. However, efforts to model the impact of climate change on fish growth have been hampered by a lack of long-term (multidecadal) data needed to understand the effects of temperature on growth rates in natural environments. We used a combination of dendrochronology techniques and additive mixed-effects modeling to examine the sensitivity of growth in a long-lived (up to 70 years), endemic marine fish, the western blue groper (Achoerodus gouldii), to changes in water temperature. A multi-decadal biochronology (1952-2003) of growth was constructed from the otoliths of 56 fish collected off the southwestern coast of Western Australia, and we tested for correlations between the mean index chronology and a range of potential environmental drivers. The chronology was significantly correlated with sea surface temperature in the region, but common variance among individuals was low. This suggests that this species has been relatively insensitive to past variations in climate. Growth increment and age data were also used in an additive mixed model to predict otolith growth and body size later this century. Although growth was relatively insensitive to changes in temperature, the model results suggested that a fish aged 20 in 2099 would have an otolith about 10% larger and a body size about 5% larger than a fish aged 20 in 1977. Our study shows that species or populations regarded as relatively insensitive to climate change could still undergo significant changes in growth rate and body size that are likely to have important effects on the productivity and yield of fisheries. © 2014 John Wiley & Sons Ltd.
Currie, Shannon E; Stawski, Clare; Geiser, Fritz
Many hibernating animals thermoregulate during torpor and defend their body temperature ( T b ) near 0°C by an increase in metabolic rate. Above a critical temperature ( T crit ), animals usually thermoconform. We investigated the physiological responses above and below T crit for a small tree-dwelling bat ( Chalinolobus gouldii , ∼14 g) that is often exposed to sub-zero temperatures during winter. Through simultaneous measurement of heart rate ( f H ) and oxygen consumption ( V̇ O 2 ), we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures ( T a 5-20°C). T crit for this species was at a T a of 0.7±0.4°C, with a corresponding T b of 1.8±1.2°C. Below T crit , animals began to thermoregulate, as indicated by a considerable but disproportionate increase in both f H and V̇ O 2 The maximum increase in f H was only 4-fold greater than the average thermoconforming minimum, compared with a 46-fold increase in V̇ O 2 The differential response of f H and V̇ O 2 to low T a was reflected in a 15-fold increase in oxygen delivery per heart beat (cardiac oxygen pulse). During torpor at low T a , thermoregulating bats maintained a relatively slow f H and compensated for increased metabolic demands by significantly increasing stroke volume and tissue oxygen extraction. Our study provides new information on the relationship between metabolism and f H in an unstudied physiological state that may occur frequently in the wild and can be extremely costly for heterothermic animals. © 2018. Published by The Company of Biologists Ltd.
Beatty, William; Jay, Chadwick V.; Fischbach, Anthony S.; Grebmeier, Jacqueline M.; Taylor, Rebecca L.; Blanchard, Arny L.; Jewett, Stephen C.
Sea ice dominates marine ecosystems in the Arctic, and recent reductions in sea ice may alter food webs throughout the region. Sea ice loss may also stress Pacific walruses (Odobenus rosmarus divergens), which feed on benthic macroinvertebrates in the Bering and Chukchi seas. However, no studies have examined the effects of sea ice on foraging Pacific walrus space use patterns. We tested a series of hypotheses that examined walrus foraging resource selection as a function of proximity to resting substrates and prey biomass. We quantified walrus prey biomass with 17 benthic invertebrate families, which included bivalves, polychaetes, amphipods, tunicates, and sipunculids. We included covariates for distance to sea ice and distance to land, and systematically developed a series of candidate models to examine interactions among benthic prey biomass and resting substrates. We ranked candidate models with Bayesian Information Criterion and made inferences on walrus resource selection based on the top-ranked model. Based on the top model, biomass of the bivalve family Tellinidae, distance to ice, distance to land, and the interaction of distances to ice and land all positively influenced walrus foraging resource selection. Standardized model coefficients indicated that distance to ice explained the most variation in walrus foraging resource selection followed by Tellinidae biomass. Distance to land and the interaction of distances to ice and land accounted for similar levels of variation. Tellinidae biomass likely represented an index of overall bivalve biomass, indicating walruses focused foraging in areas with elevated levels of bivalve and tellinid biomass. Our results also emphasize the importance of sea ice to walruses. Projected sea ice loss will increase the duration of the open water season in the Chukchi Sea, altering the spatial distribution of resting sites relative to current foraging areas and possibly affecting the spatial structure of benthic communities.
Grebmeier, J. M.; Cooper, L. W.; Moore, S. E.
A key ecological organizing principle for the northern Bering Sea and the adjoining southern Chukchi Sea just north of Bering Strait is that the shallow, seasonally productive waters lead to strong pelagic-benthic coupling to the sea floor, with deposition of fresh chlorophyll coinciding with the spring bloom as sea ice retreats. Both in situ production and advection of upstream phytodetritus to these regions support persistent biological hotspots that connect benthic prey to upper trophic benthivores. This northern marine ecosystem is dominated by marine macroinvertebrates (e.g. clams, polychaetes, sipunculids, and amphipods) that feed on the high production deposited rapidly to the seafloor, which in turn serve as food resources for diving mammals and seabirds, such as gray whales, bearded seals, eiders, and walruses. Between St. Lawrence Island and Bering Strait and northwards into the Chukchi Sea, the persistence of seasonal sea ice has significantly declined over the past two decades, and along with warming seawater temperatures, these changes have potential ramifications to ecosystem structure. Times-series data over the last 25 years indicate that these regions have experienced a northward shift in macrofaunal composition and a decline in core benthic biomass that matches patterns of reduced sea ice, warming seawater, and changing sediment grain size that relates to varying current patterns. This presentation will discuss these data in the context of both process studies from the region and results from the Distributed Biological Observatory (DBO), an international network of time series transects that is providing a framework to evaluate status and trends on a latitudinal bases in the Pacific Arctic region.
Zalmon, I. R.; Macedo, I. M.; Rezende, C. E.; Falcão, A. P. C.; Almeida, T. C.
The environmental heterogeneity of the Campos Basin on the northern coast of Rio de Janeiro State was assessed by the benthic macrofauna on the platform adjacent to the Paraíba do Sul River (PSR) on the dry and rainy seasons. The samples were collected in triplicate from 33 sites using a van Veen grab during March 2009 - a period of higher precipitation and flow rate - and July 2009 - a period of lower precipitation and flow rate. The grab depths ranged from 12 to 97 m and were grouped into three strata: 1: 50 m. The particle size, total carbonate and total organic carbon in each sample were analyzed. Subsamples for the macrofauna analysis were washed, sieved with a 500 μm mesh and identified. The sediment was predominantly composed of sand, with mud pockets near the mouth of the river. The macrofauna included annelids, crustaceans, mollusks, echinoderms, cnidarians, nemerteans, cephalochordates, sipunculids and bryozoans. The density and richness were directly related to the depth, with both descriptors being higher during the rainy season and at depths greater than 50 m. This result is probably due to the higher availability of food in the river during this period and is corroborated by the predominance of deposit feeders in the deepest stratum. The number of individuals of each species was higher in the shallowest stratum, probably due to the higher productivity of this stratum. The rate of organic particulate matter flow from the coastal regions to the deeper regions can also be influenced by the material export dynamics of the river, which are more intense during the rainy season. These dynamics explain why a significantly higher number of individuals were observed in the rainy period in comparison to the dry one. Multivariate analyses identified differences between the sampling sites in the deepest stratum during both periods and revealed a stronger similarity between the shallow and intermediate strata, especially during the rainy season, which has a
Bioerosion of coral reefs, especially when related to the activity of macroborers, is considered to be one of the major processes influencing framework development in present-day reefs. Macroboring communities affecting both living and dead corals are widely distributed also in the fossil record and their role is supposed to be analogously important in determining flourishing vs demise of coral bioconstructions. Nevertheless, many aspects concerning environmental factors controlling the incidence of bioerosion, shifting in composition of macroboring communities and estimation of bioerosion rate in different contexts are still poorly documented and understood. This study presents an attempt to quantify bioerosion rate on reef limestones characteristic of some Oligocene outcrops of the Tertiary Piedmont Basin (NW Italy) and deposited under terrigenous sedimentation within prodelta and delta fan systems. Branching coral rubble-dominated facies have been recognized as prevailing in this context. Depositional patterns, textures, and the generally low incidence of taphonomic features, such as fragmentation and abrasion, suggest relatively quiet waters where coral remains were deposited almost in situ. Thus taphonomic signatures occurring on corals can be reliably used to reconstruct environmental parameters affecting these particular branching coral assemblages during their life and to compare them with those typical of classical clear-water reefs. Bioerosion is sparsely distributed within coral facies and consists of a limited suite of traces, mostly referred to clionid sponges and polychaete and sipunculid worms. The incidence of boring bivalves seems to be generally lower. Together with semi-quantitative analysis of bioerosion rate along vertical logs and horizontal levels, two quantitative methods have been assessed and compared. These consist in the elaboration of high resolution scanned thin sections through software for image analysis (Photoshop CS3) and point
McTigue, N. D.; Dunton, K. H.
Predicting how alterations in sea ice-mediated primary production will impact Arctic food webs remains a challenge in forecasting ecological responses to climate change. One top-down approach to this challenge is to elucidate trophic roles of consumers as either specialists (i.e., consumers of predominantly one food resource) or generalists (i.e., consumers of multiple food resources) to categorize the dependence of consumers on each primary producer. At Hanna Shoal in the Chukchi Sea, Alaska, we used stable carbon and nitrogen isotope data to quantify trophic redundancy with standard ellipse areas at both the species and trophic guild levels. We also investigated species-level trophic plasticity by analyzing the varying extents that three end-members were assimilated by the food web using the mixing model simmr (Stable Isotope Mixing Model in R). Our results showed that ice algae, a combined phytoplankton and sediment organic matter composite (PSOM), and a hypothesized microphytobenthos (MPB) component were incorporated by consumers in the benthic food web, but their importance varied by species. Some primary consumers relied heavily on PSOM (e.g, the amphipods Ampelisca sp. and Byblis sp.; the copepod Calanus sp.), while others exhibited generalist feeding and obtained nutrition from multiple sources (e.g., the holothuroidean Ocnus glacialis, the gastropod Tachyrhynchus sp., the sipunculid Golfingia margaritacea, and the bivalves Ennucula tenuis, Nuculana pernula, Macoma sp., and Yoldia hyperborea). Most higher trophic level benthic predators, including the gastropods Buccinum sp., Cryptonatica affinis, and Neptunea sp, the seastar Leptasterias groenlandica, and the amphipod Anonyx sp. also exhibited trophic plasticity by coupling energy pathways from multiple primary producers including PSOM, ice algae, and MPB. Our stable isotope data indicate that consumers in the Hanna Shoal food web exhibit considerable trophic redundancy, while few species were specialists
Silvia K. Moreno-Forero
Full Text Available Cryptobiota of dead fragments of five branches in live position and five fallen pieces of the coral Acropora palmata each one of approximate 1dm3, covered by filamentous algae were extracted from the north reef crest of Isla Grande (Colombian Caribbean, in April 1991. There were three groups of organisms according to size and position (on and within the coral: 1 mobile epibenthos, mainly microcrustaceans that live among the filamentous algae 2 boring microcryptobiota, located in the layer between the epilithic organisms and the coral skeleton itself and, 3 perforating macrocryptobionts that bore and penetrate the coral skeleton. Polychaetes, sipuncu-lids, mollusks and crustaceans were most abundant in the last group. There were no differences in macrocryptobiont composition between standing dead branches and fallen fragments. There was a large variation in total biomass and type and density of macro-cryptobionts, possibly associated to stochastic factors such as placement and thickness of branches and small scale variations in recruitmentLa criptobiota de diez fragmentos coralinos muertos de Acropora palmata, de 10 dm3 cada uno, cubiertos de algas filamentosas, se colectó en abril de 1991en la cresta arrecifal de Isla Grande (Caribe colombiano. Se halló tres grupos: 1 móviles epibentónicos asociados a las algas filamentosas y conformados principalmente por microcrustáceos; 2 microcriptobiontes perforantes, ubicados en la capa intermedia entre los organismos epilíticos y el esqueleto del coral y 3 macrocriptobiontes que perforan todo el cuerpo del esqueleto coralino (principalmente poliquetos, sipuncúlidos, moluscos y crustáceos. No se encontraron diferencias en la composición de los macrocriptobiontes que habitan los corales en posición de vida y los fragmentos caidos sobre el fondo. Se presentó una amplia variación en biomasa total, tipo y densidad de macrocriptobiontes, posiblemente asociada a factores estocásticos tales como la