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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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We dived at regular intervals (8, 12 or 14 h) over periods of 9 to 23 days to quantify the allocation of time to different activities by large adults of the four common sea stars foraging in a sediment bottom community (8 to 11 in depth) in the northern Gulf of St. Lawrence. The relative time spent at different activities was similar for Leptasterias polaris and Asterias vulgaris, the most frequent activity being moving over the bottom (42-46% of the time), presumably in search of prey, secondly being stationary (26-27%), and thirdly digesting prey (17-20%). Capture of prey was less frequent, 13% of the time for L. polaris (mainly digging for bivalves) and 5% for A. vulgaris. Compared to L. polaris and A. vulgaris, Crossaster papposus spent more time being stationary and periods of moving were of shorter duration. Solaster endeca differed from the other sea stars because of the high proportion of time spent digesting prey (40%) and the small proportion of time spent moving (22%). Capture events were not observed for C. papposus and S. endeca, likely because they exclusively fed on epifaunal species, which were rapidly captured. For all four species, the most frequent changes between activities were between moving and being stationary. The number of days per prey eaten (length of a feeding bout) was about 11 for S. endeca, 6.6 for L. polaris, 3.1 for C. papposus and 2.8 for A. vulgaris. All sea stars appear to be energy maximizers that spend most of their time finding, capturing and digesting prey. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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We examined the association between green turtle nesting activities and plasma profiles of hormones that are widely implicated in aspects of heightened metabolism and energy regulation; epinephrine (EPI), norepinephrine (NE) and corticosterone. In conjunction, we examined plasma profiles of glucose and lactate to infer metabolic processes associated with green turtle nesting behaviour. Finally, because these hormones are also involved in mediating behaviour and physiology associated with stressful situations, we examined the effect of a stressor encountered during nesting, physical disturbance, on hormone levels. Plasma profiles of epinephrine, norepinephrine and corticosterone were not significantly altered across different stages of nesting. Plasma glucose and lactate both exhibited significant increases related to nesting activity; glucose increased dramatically during the emergence stage of nesting before stabilizing, and lactate levels continued to increase throughout the nesting process. There was no significant association between plasma hormones and glucose. For female turtles that abandoned nesting activities due to competition for nest space, there was no significant difference in plasma levels of epinephrine, norepinephrine and corticosterone compared to females that persisted with nesting activities. Overall, while distinct metabolic changes took place in nesting females, there was little association in profiles of hormones typically considered important for regulating heightened metabolism and nesting activity. This disassociation could arise because hormonal action may be altered in breeding female green turtles to facilitate reproductive processes. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Nitrogenous excretion and arginase specific activity were measured while Marsupenaeus japnoicus Bate (7.4+/-1.2 g) were exposed to 0 (control), 0.36 and 1.39 mM nitrite at 30%% (g kg^-^1) salinity for 24 h. Excretions of total-N, organic-N, urea-N, and ammonia-N increased significantly with an increase of ambient nitrite. Arginase specific activities of hepatopancreas and hemolymph increased directly with ambient nitrite. The fact that M. japonicus following exposure to 1.39 mM nitrite increased its arginase specific activity indicated an argininolysis in reducing joint toxicities of metabolic ammonia and incorporated nitrite. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In its habitat, Chasmagnathus granulata is exposed to many different environmental challenges according to the season of the year. For this reason, the investigation of the participation of the gluconeogenic pathway in the acclimation to hypo- and hyperosmotic conditions in summer and winter was considered interesting. By comparing the gluconeogenesis capacity, phosphoenolpyruvate carboxykinase (PEPCK) activity, and mRNA PEPCK gene expression values obtained in control crabs during summer and winter, we found two opposite tendencies: a decrease in winter and an increase in summer. The present results show that, in the C. granulata jaw muscle, PEPCK activity is divided almost equally between the cytosol and mitochondria in winter crabs. This distribution is different from the one found in muscle from summer crabs, in which most of the PEPCK activity (85%) takes place in the mitochondria. The data reported here show that the natural light/dark cycle typical for winter regulated the proportion of PEPCK activity in the cytosolic and mitochondrial fractions at the transcriptional level, with a marked decrease in the mitochondrial PEPCK activity and, as a result, in the gluconeogenic capability. The gluconeogenic activity decreased 48% after 24 h of hyperosmotic stress in summer. Furthermore, this treatment reverted the proportion of PEPCK activity in cytosolic and mitochondrial fractions: it decreased in the mitochondrial fraction and increased in the cytosolic one. However, at 72 h of hyperosmotic shock, the incorporation of label from alanine into glucose increased 45% as compared to a 24-h group. Hence, it is possible that the increase in gluconeogenic capacity after 72 h of hyperosmotic stress is due to the enhanced PEPCK gene expression at 24 h of osmotic stress. The present study shows that the rises in the incorporation of ^1^4C-alanine into glucose and in the mitochondrial and cytosolic activities in the jaw muscle of C. granulata after 24 h of acclimation to a dilute media in summer did not require an increase in PEPCK gene expression. During hypoosmotic shock in winter, the gluconeogenenic capacity and the PEPCK activity are still remarkably low, and the PEPCK gene expression remains undetectable. The muscle gluconeogenesis seems to be one of the pathways implicated in the metabolic adjustment during hypo- and hyperosmotic shock in C. granulata. On the other hand, the present study highlights the importance of seasonal environmental differences in determining the development of metabolic patterns. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The American horseshoe crab, Limulus polyphemus (Linnaeus), typically inhabits estuaries and coastal areas with pronounced semi-diurnal and diurnal tides that are used to synchronize the timing of spawning, larval hatching, and emergence. Horseshoe crabs spawn in the intertidal zone of sandy beaches and larval emergence occurs when the larvae exit the sediments and enter the plankton. However, L. polyphemus populations also occur in areas that lack significant tidal changes and associated synchronization cues. Endogenous activity rhythms that match predictable environmental cycles may enable larval horseshoe crabs to time swimming activity to prevent stranding on the beach. To determine if L. polyphemus larvae possess a circatidal rhythm in vertical swimming, larvae collected from beach nests and the plankton were placed under constant conditions and their activity monitored for 72 h. Time-series analyses of the activity records revealed a circatidal rhythm with a free-running period of ~12.5 h. Maximum swimming activity consistently occurred during the time of expected falling tides, which may serve to reduce the chance of larvae being stranded on the beach and aid in seaward transport by ebb currents (i.e., ebb-tide transport). To determine if agitation serves as the entrainment cue, larvae were shaken on a 12.4 h cycle to simulate conditions during high tide in areas with semi-diurnal tides. When placed under constant conditions, larval swimming increased near the expected times of agitation. Thus, endogenous rhythms of swimming activity of L. polyphemus larvae in both tidal and nontidal systems may help synchronize swimming activity with periods of high water and inundation. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Three closely related marine teleosts with similar size, swimming mode, and habitat preference were compared to test the hypothesis that energy metabolism is linked to diet choice in the wild. Key substrate-utilization enzyme activities were assayed from white locomotory muscle and liver in a carnivore (Scorpis violaceus), an omnivore (Girella tricuspidata), and a herbivore (Kyphosus sydneyanus) collected from their natural reef habitat in northeastern New Zealand. The similar energy requirements of the study fishes were reflected in specific enzyme activities of white muscle and suggested high dependence on endogenous fuel that is independent of dietary carbohydrate intake. Clear differences were found in enzymes of hepatic carbohydrate, fat, and ketone body metabolism that appear linked to diet choice and levels of gastrointestinal fermentation. Hepatic metabolism of fat and ketone bodies was also examined in New Zealand samples of the omnivorous Girella cyanea and the herbivorous Kyphosus bigibbus, and the tropical herbivorous species Kyphosus vaigiensis and Kyphosus cinerascens collected from the Great Barrier Reef, Australia. Overall, the results suggest that, like ruminants, herbivorous fishes such as Kyphosus species that rely upon gastrointestinal fermentation preferentially use lipids as major metabolic substrates by an increased capacity for lipid metabolism, and a lower capacity for glycolysis. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The abalone, Haliotis asinina, is a large, highly active tropical abalone that feeds at night on shallow coral reefs where oxygen levels of the water may be low and the animals can be exposed to air. It is capable of more prolonged and rapid exercise than has been reported for temperate abalone. These unusual behaviours raised the question of whether H. asinina possesses enhanced capacities for aerobic or anaerobic metabolism. The blood oxygen transport system of H. asinina resembles that of temperate abalone in terms of a large hemolymph volume, similar hemocyanin concentrations, and in most hemocyanin oxygen binding properties; however, absence of a Root effect appears confined to hemocyanin from H. asinina and may assist oxygen uptake when hemolymph pH falls during exercise or environmental hypoxia. During exposure to air, H. asinina reduces oxygen uptake by at least 20-fold relative to animals at rest in aerated seawater, and there is no significant ATP production from anaerobic glycolysis or phosphagen hydrolysis in the foot or adductor muscles. This slowing of metabolism may contribute to survival at lower water oxygen levels than normally encountered by most temperate abalone. While crawling speeds of H. asinina in water are not exceptionally high, an aerobic expansibility of 5.5-fold at speeds less than 20% of maximum is more than 2.7-fold greater than reported for several temperate abalone. The high aerobic expansibility also supports the enhanced frequency and duration of flipping behaviour without recourse to the additional inputs from anaerobic glycolysis required by other abalone. Metabolic profiles of foot and adductor muscles of H. asinina are similar to those of other abalone. Common features are low activities of enzymes unique to aerobic ATP production, relatively high activities of arginine kinase, tauropine and d-lactate dehydrogenase as the predominant pyruvate reductases, and low intracellular pH buffering capacities. It is concluded that the exceptional abilities of H. asinina for prolonged and rapid exercise are supported by higher rates of aerobic metabolism rather than any enhanced capacity for anaerobic muscle work. It is unexpected, and instructive, that the exceptional aerobic expansibility is not apparent in obvious adjustments of the blood oxygen delivery system or muscle properties associated with aerobic ATP production. The absence of a hemocyanin Root effect, and the extent to which both aerobic and anaerobic metabolism can be reduced may be special features that assist prolonged exercise and survival of H. asinina when environmental oxygen becomes limiting. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In order to investigate the influence of anoxic stress on haemocyte immune response, specimens of Chamelea gallina were exposed to 24 and 48 h anoxia. To evaluate recovery capacity, clams were maintained, at the end of the anoxic phase, for 24 h in reoxygenated seawater. In this paper, activity and expression of the antioxidant enzyme superoxide dismutase (SOD) were studied on haemocyte lysate and haemolymph. Reported results have shown that the anoxic stress changed strongly the response of C. gallina blood cells. Indeed, at the end of the anoxic phase in both experiments (24 and 48 h of anoxia exposure), SOD activity in haemocyte lysate decreased significantly with respect to the control, likely because of a decreasing superoxide anion generation in anoxia. Expression analyses were coherent with activity values. In the first experiment (24 h anoxia), reoxygenation determined an increase in activity of both Cu/Zn-SOD and Mn-SOD, but with values that remained significantly lower than those of the controls. It seems that after the applied anoxic stress, 24 h of recovery is not sufficient to restore pre-anoxic conditions. In the second experiment (48 h anoxia), SOD isoforms showed a different response during the recovery of animals. Cu/Zn-SOD activity dropped below the values showed by haemocytes of anoxic bivalves, while Mn-SOD activity values exceeded significantly those of controls. The different haemocyte response could be probably due to a further stress suffered by the clams because of a massive spawning during the reoxygenation phase. Therefore, the high values of activity shown by Mn-SOD during the recovery are likely to be due to the high inducibility of this isoform. In Cu/Zn-SOD expression analyses, two immunoreactive bands were highlighted in both experiments. The former (apparent molecular weight of 16 kDa) corresponds to the expression of SOD1 and the latter (apparent molecular weight of 28-30 kDa) could be attributed to EC-SOD (SOD3), a Cu/Zn-SOD isoform located in extracellular ambient and identified both in vertebrates and invertebrates. The strong SOD3 expression during anoxia exposure and the further spawning stress (second experiment) testified its inducibility in C. gallina haemocytes and haemolymph in response to stressful conditions. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In upwelling ecosystems, such as the Humboldt Current system (HCS) off Concepcion, the effects of solar radiation on bacterioplankton incorporation rates have been related to previous light acclimation and responses to irradiance. In this paper, we study the daily effect of Photosynthetic Active Radiation (PAR, 400-700 nm) and ultraviolet radiation UVR (280-400 nm) on bacterial secondary production (BSP). We also considered the DNA damage-repair response to solar radiation stress by the induction of cyclobutane pyrimidine dimers (CPDs). Experiments were conducted with natural bacterioplankton assemblages (0.2-0.7 @mm) collected off Concepcion (36^oS), during the austral Spring, October-November, 2004. Surface (0.5 m) and subsurface (80 m) bacterioplankton samples were exposed to different solar radiation treatments for 5-20 h. BSP was estimated by ^1^4C-leucine and ^3H-thymidine incorporation at several time intervals, whereas CPDs accumulation was assessed using immunoassay techniques. During high irradiance periods, BSP was mainly affected by PAR in both surface and subsurface assemblages and, to a lesser, but significant (Tukey<0.05) extent, by UV-A (320-400 nm) and UV-B (280-320 nm) radiation. Maximum inhibition of BSP in surface waters was 78%; growth rates (@m) and bacterial growth efficiency (BGE) were also low (78% and 66% respectively). Subsurface water assemblages, on the contrary, showed a ~25 fold enhancement of BSP, @m, and BGE. Both types of assemblages had a rapid CPDs accumulation (maximum 60 CPDs Mb^-^1) during high irradiance periods. Recovery of BSP inhibition and DNA damage in surface bacteria was total after sunset and after the night incubation period, resembling pre-exposure levels. Despite subsurface BSP enhancement during day-night exposure, residual DNA damage was detected at the end of the experiment (20 CPDs Mb^-^1) suggesting a chronic DNA damage. Our results represent the worst case scenario (i.e., assemblages receiving surface irradiances as may occur in this upwelling zone) and indicate that surface and subsurface bacterial assemblages in the HCS are both highly sensitive to solar irradiance. However, they showed different responses, with surface bacteria having more effective photorepair mechanisms, and sustaining higher BSP than subsurface assemblages. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The sandy beaches of Zakynthos Island support the largest single nesting aggregation in the Mediterranean Region of the endangered loggerhead turtle Caretta caretta. The present study attempts to determine possible correlations between a series of habitat variables and nest site selection. Nesting activities, including total and nesting emergences were examined in response to the recorded biotic and abiotic variables. The results of the analysis indicate that beach width is the most critical habitat variable affecting nest site selection. Further analysis of nesting performance implies that sea turtles use multiple environmental cues for nest site selection during the different steps of the nesting processes such as emergence from the surf and nesting. Nevertheless, we caution that a detailed study needs to be conducted over a more extensive period of time to verify these suggestions. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Flounder were exposed to waterborne phenanthrene (0.5, 1 and 2 @mM) for 4 weeks to test effects of waterborne phenanthrene on growth and hematological properties of the olive flounder (Paralichthys olivaceus). The average weight gain (WG) of flounder was significantly decreased in fish exposed to phenanthrene at 2.0 @mM for 2 weeks, whereas WGs of fish treated by 1.0 and 2.0 @mM phenanthrene for 4 weeks were significantly decreased. However, hepatosomatic index (HSI) and condition factor (CF) of flounder were not significantly affected by phenanthrene exposure. Red blood cell (RBC) count, hemoglobin (Hb) concentration, hematocrit (Ht), the mean corpuscular hemoglobin (MCH) and the mean corpuscular hemoglobin concentration (MCHC) mean levels were decreased with an increase in exposure time of phenanthrene to the fish, but the level of the mean corpuscular volume (MCV) was increased. Plasma bilirubin concentrations were significantly increased following exposure to waterborne phenanthrene (2.0 @mM) for 2 and 4 weeks; however, there were no significant changes in plasma total cholesterol in fish of all treated groups compared to control. The phenanthrene-exposed groups (>=1.0 @mM) showed significantly higher mean plasma lysozyme activity. Kidney lysozyme activity of fish exposed to phenanthrene (>=1.0 @mM) was also significantly higher than that of control fish. The central finding from these data is that olive flounder exposed to waterborne phenanthrene at more than 1.0 @mM are likely to experience negative impacts on fish health and basic physiological functions. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The main objective of this study was to measure the impact of benthic invertebrate diversity on processes occurring at the water-sediment interface. We analyzed the effects of interactions between three shallow water species (Cerastoderma edule, Corophium volutator, and Nereis diversicolor). The impacts of different species richness treatments were measured on sediment reworking, bacterial characteristics, and biogeochemical processes (bromide fluxes, O"2 uptake, nutrient fluxes, and porewater chemistry) in sediment cores. The results showed that the three species exhibited different bioturbation activities in the experimental system: C. edule acted as a biodiffusor, mixing particles in the top 2 cm of the sediments; C. volutator produced and irrigated U-shaped tubes in the top 2 cm of the sediments; and N. diversicolor produced and irrigated burrow galleries in the whole sediment cores. C. edule had minor effects on biogeochemical processes, whereas the other species, through their irrigation of the burrows, increased the solute exchange between the water column and the sediment two-fold. These impacts on sediment structure and solute transport increased the O"2 consumption and the release of nutrients from sediments. As N. diversicolor burrowed deeper in the sediment than C. volutator, it irrigated a greater volume of sediments, with great impact on the sediment cores. Most treatments with a mixture of species indicated that observed values were often lower than predicted values from the addition of the individual effects of each species, demonstrating a negative interaction among species. This type of negative interaction measured between species on ecosystem processes certainly resulted from an overlap of bioturbation activities among the three species which lived and foraged in the same habitat (water-sediment interface). All treatments with N. diversicolor (in isolation and in mixture) produced similar effect on sediment reworking, water fluxes, nutrient releases, porewater chemistry, and bacterial characteristics. Whichever species associated with N. diversicolor, the bioturbation activities of the worm hid the effect of the other species. The results suggest that, in the presence of several species that use and modify the same sediment space, impact of invertebrates on ecosystem processes was essentially due to the most efficient bioturbator of the community (N. diversicolor). In consequence, the functional traits (mode of bioturbation, depth of burrowing, feeding behaviour) of an individual species in a community could be more important than species richness for some ecosystem processes. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Temperature determines all physiological responses by limiting cellular reaction rates. Daily temperature variation differs between microhabitats, which means that subpopulations of the same species may respond differently to temperature. The aim of this study is to determine how physiological responses to temperature of the limpet Cellana tramoserica differ between limpets from variable and from stable thermal environments. Oxygen consumption and anaerobic and aerobic metabolic capacities were measured over a range of temperatures in limpets from thermally stable and variable field sites in summer and winter, and in laboratory acclimation treatments. Limpets from both variable and stable sites, showed acclimatisation of anaerobic and aerobic potentials. Limpets from stable environments, but not from variable environments, showed increased oxygen consumption in winter. Comparison of field and laboratory data showed that temperature was the signal for acclimatisation. The physiological response of C. tramoserica to temperature depends on season and microhabitat. Care must therefore be taken when conducting interspecies comparisons of response to temperature to address the confounding effects of phenotypic plasticity. Differences in physiological response to temperature in phenotypically flexible species like C. tramoserica may simply reflect individual reactions to immediate environmental conditions. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Sepia apama were tagged with acoustic transmitters and monitored on their native House Reef, Boston Bay, South Australia, with a radio acoustic positioning telemetry (RAPT) system. Cuttlefish were tagged with position-only and intra-mantle jet pressure transmitters. New data analyses were developed to handle problem data that arise with an uneven reef environment. Maximum range for the cuttlefish varied from 90 m to 550 m. Cuttlefish home range was between 5300 m^2 and 23,700 m^2. S. apama were found to be diurnal as average distance travelled was higher in the day than at night, and cuttlefish were active for 32 days, but only 18 nights. After the cuttlefish settled into reef crevices, activity spectrum and positioning analysis showed foraging behaviour at only 3.7% per day and 2.1% per night. Cuttlefish were found to spend more than 95% of the day resting, which suggests that their bioenergetics are more akin to those of octopus than of squid. The cuttlefish combination of predator avoidance, efficient foraging and quiescent lifestyle allows energy to be channelled into growth and fulfillment of the live-fast-die-young cephalopod philosophy. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The fate of ingested eukaryotic photoautotrophic fatty acids during gut transit in the lugworm Arenicola marina (L.) and the influence of A. marina's faeces on the evolution of fatty acid distribution and bacterial community structure in superficial sediments were studied under laboratory conditions. Dead phytoplanktonic cells (food portions) were fed to individual A. marina and subsequently incubated, or allowed to directly incubate in the presence of fresh egesta or non-ingested sediment. Changes in fatty acid composition and genetic structure of bacterial communities during gut transit and/or incubation were monitored using gas-chromatography/mass-spectrometry and a DNA fingerprint approach (RISA), respectively. Results, supported by principal component analyses, suggest that A. marina's feeding activity can directly and indirectly affect the lipid biomarker composition and the bacterial community structure of inhabited sediments. Faecal casts produced from food portions appeared qualitatively enriched in saturated fatty acids relative to (poly)unsaturated ones due, partly, to an increase of some bacterial fatty acids and to the preferential removal of some polyunsaturated fatty acids (PUFAs). The incubation of food portions in the presence of fresh A. marina's egesta (designed to study the indirect impact of feeding by A. marina) induced a significant increase in the concentrations of C"2"0 and C"2"2 polyunsaturated fatty acids (PUFAs), whereas these compounds almost disappeared following direct feeding and subsequent incubation, indicating that some dietary fatty acids may be more accessible to biodegradation following passage through the gut of A. marina. The aforementioned increase in PUFAs was attributed to a bacterial production during incubation, suggesting the presence of PUFA-producing bacteria in the fresh egesta of A. marina. Those bacteria were either enteric bacteria that were released with the egesta or ingested bacteria that have survived gut passage, as suggested by the variations of the bacterial community structure (i.e. RISA profiles) during incubation. The results suggest that aged faeces from A. marina might be, in some circumstances, of relatively high nutritional value to trophic levels which are unable to synthesize essential PUFAs de novo. The presence of PUFA-producing bacteria in guts of marine lugworms deserves further attention. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The free lipid content of extracts from the spawn of 17 molluscs were analysed by gas chromatography/mass spectrometry. These extracts encompass the encapsulated embryos and extraembryonic structures from benthic gelatinous egg masses and leathery egg capsules covering five taxonomic groups. Palmitic and stearic acids were the dominant saturated fatty acids and oleic acid was the principal unsaturated acid found in the spawn. Cholesterol was the dominant sterol and the only sterol found in the spawn from every species. Extracts from gelatinous egg masses were found to contain proportionally more fatty acids compared to leathery egg capsules. No unsaturated fatty acids were found in any of the leathery egg capsules, including five neogastropods and one littorinimorph. Unsaturated fatty acids were present in all of the gelatinous egg masses, including two other littorinimorphs. This is the first study to demonstrate that unsaturated fatty acids possess significant bacteriolytic activity against four aquatic pathogens. Encapsulated Anaspidea egg masses contain relatively high concentrations of these unsaturated fatty acids and a lipid mixture modeled on these extracts was strongly bacteriolytic at concentrations down to 0.0001 mg/ml. By comparison, lipid mixtures modeled on extracts from the spawn of four other molluscan taxa with higher proportions of saturated fatty acid and cholesterol, were only partially active against some of the bacteria at 0.1 mg/ml. Thus, unsaturated fatty acids could explain the antimicrobial activity previously reported in lipid extracts of some, but not most, molluscan spawn. MDS ordination and ANOSIM revealed significant taxonomic differences in the composition of free lipids from molluscan spawn, suggesting that lipid analyses may be useful in future systematic studies of the Mollusca. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The diving behaviour of four leatherback turtles (Dermochelys coriacea) was recorded for periods of 0.5-8.1 months during their postnesting movements in the Indian and Atlantic Oceans, when they covered 1569-18,994 km. Dive data were obtained using satellite-linked transmitters which also provided information on the dive depths and profiles of the turtles. Turtles mainly dove to depths <200 m, with maximum dive durations under 30-40 min and exhibited diel variations in their diving activity for most part of the routes, with dives being usually longer at night. Diurnal dives were in general quite short, but cases of very deep (>900 m) and prolonged (>70 min) dives were however recorded only during daytime. The three turtles that were tracked for the longest time showed a marked change in behaviour during the tracking, decreasing their dive durations and ceasing to dive deeply. Moreover, diel variations disappeared, with nocturnal dives becoming short and numerous. This change in turtle diving activity appeared to be related to water temperature, suggesting an influence of seasonal prey availability on their diving behaviour. The turtle diving activity was independent on the shape of their routes, with no changes between linear movements in the core of main currents or looping segments in presence of oceanic eddies. ... Read more

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U.S. mariculture production of bivalve molluscs-those cultivated in the marine environment-has roughly doubled over the last 25 years. Although mariculture operations may expand the production of seafood without additional exploitation of wild populations, they still depend upon and affect natural ecosystems and ecosystem services. Every additional animal has an incremental effect arising from food extraction and waste excretion. Increasing domestic seafood production in the United States in an environmentally and socially responsible way will likely require the use of policy tools, such as best management practices (BMPs) and performance standards.

BMPs represent one approach to protecting against undesirable consequences of mariculture. An alternative approach to voluntary or mandatory BMPs is the establishment of performance standards for mariculture. Variability in environmental conditions makes it difficult to develop BMPs that are sufficiently flexible and adaptable to protect ecosystem integrity across a broad range of locations and conditions. An alternative that measures performance in sustaining key indicators of ecosystem state and function may be more effective. Because BMPs address mariculture methods rather than monitoring actual ecosystem responses, they do not guarantee that detrimental ecosystem impacts will be controlled or that unacceptable impact will be avoided.

Ecosystem Concepts for Sustainable Bivalve Mariculture finds that while performance standards can be applied for some broad ecosystem indicators, BMPs may be more appropriate for addressing parameters that change from site to site, such as the species being cultured, different culture methods, and various environmental conditions. This book takes an in-depth look at the environmental, social, and economic issues to present recommendations for sustainable bivalve mariculture.


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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The effect of turbulence, light level, and ontogeny on herring larva's attack rate and swimming activity was tested in a previous study. However, during larval seasons (spring and autumn), water clarity is frequently impaired by alga blooms, which also most probably will affect larva feeding rate. Therefore, this study was to investigate the effects of turbidity, turbulence, and ontogeny on the attack rate and swimming activity of herring larvae. By adding diatomaceous earth (DE) to the water, three turbidity levels were established: 0, 35, and 80 Jackson Turbidity Unit [JTU; which coincide with a beam attenuation (c) of 0.1, 2.5, and 4.8 m^-^1, respectively]. An unfavourable (8x10^-^6 W/kg) and a favourable turbulence level (1x10^-^6 W/kg) were chosen based on results from the earlier study. The results show that intermediate turbidity (35 JTU) has a positive effect on the attack rate of smaller larvae (20 mm), while high turbidity (80 JTU) has a negative effect on attack rate of all tested larvae size groups. In general, attack rate was lower at the highest turbulence compared to the low level, independent of turbidity level. However, there was one exception, when turbidity was at the highest, the largest larvae (29 mm) seemed to gain from feeding in the highest turbulence level. The overall activity level was higher in the presented study than in the earlier study without turbidity. The favourable turbidity level (35 JTU) coincides with turbidity levels normally found at the equivalent depth during spring and autumn blooms in the area of where the experimental larvae originate. In addition, turbidity's effect on light absorbtion and how it influences the maximum feeding depth of the larva are discussed. ... Read more