Scallop Chlamys Islandica Research Articles

Adding fish waste to the diet of Iceland scallop Chlamys islandica: effects on feeding and reproductive ability

Organic enrichment from fish farming may impact benthic species and habitats in adjacent areas. Norwegian salmon farming is continuously growing, but, due to area conflicts and severe sea-lice problems in the western areas, growth of the industry is focused in the northern areas. Knowledge is scarce on how an increase in fish farming will impact Arctic and subarctic species and habitats. One such species is the Iceland scallop Chlamys islandica, distributed from the Lofoten Islands in Nordland County to the Varangerfjord in Troms and Finnmark County. To study the impact of fine-particle fish faeces on feeding and reproductive ability in adult Iceland scallop, particles <41 µm of finfish waste were added to the diet. Effects were tested via short-term (weeks) feeding studies using 2 diets, 100% cultured algal species and a 50% mix of algae and fish waste. In addition, a 100% fish waste diet was used to study longer-term effects on reproductive ability (months). Feeding (% particle clearance and feeding rate) on the microalgae diet tended to be higher than that on the diet containing fish waste, but the difference was significant only in 2 out of 4 cases. We did not find any effect of diets on reproductive ability (gonad development and fatty acid profiles) of scallops. Lack of knowledge on sufficient food levels for gonad maturation in this species may have affected the results. We suggest that future work includes the transplant of scallops from a reference site to fish production sites and that investigations begin immediately after spawning early in scallop gonad development.

The presence of Apicomplexan parasites in king scallops (Pecten maximus) in Scottish waters

The king scallop (Pecten maximus) is a commercially important species found around the United Kingdom coast. The association of an Apicomplexan-like parasite with mass mortality of Icelandic scallop (Chlamys islandica) in Iceland and the presence of identical parasites in king scallop (Pecten maximus) and queen scallop (Aequipecten opercularis) in Scotland raised serious concerns regarding the health of Scottish king scallops. Marine Scotland Science (MSS) conducted a survey in 2016 to assess the prevalence and the intensity of parasite infection in king scallops. King scallops were collected and sampled during the annual scallop dredge surveys in the Shetland Isles and the east and west coast of Scotland. The king scallop adductor muscle was macroscopically examined and tissue imprints taken to grade the intensity of infection. The parasite was present in the majority of the king scallops sampled in all surveyed areas: Shetland Isles 87.1%, east coast 76.0% and west coast of Scotland 64.1%. However, the parasitic infestations were light in intensity with the majority of the king scallops graded as 1 (≤20 zoites per microscopic field). No macroscopic changes in the adductor muscle were observed and histopathology examination revealed minor localized fiber degeneration of adjacent fibers to parasite clusters. The results suggested the parasite to be widespread around the Scottish coast and it appears to be able to live within the king scallop at low intensity of infection without causing significant downgrade of the adductor muscle (in terms of colour or texture) or mortality. The partial genome sequence of the parasite in king scallops from Scottish waters was identical to the one reported by Kristmundsson and Freeman (2018) in the Icelandic scallop in Icelandic waters.

Structure and long-term dynamics of zoobenthos communities in the areas of scallop Chlamys islandica beds at Kola Peninsula

Current state of zoobenthos in the areas of scallop Chlamys islandica beds in the southern Barents Sea and eastern White Sea (Voronka) is described. The scallop stock is ex­ploited there with the landing by specialized vessels, without separation of catch, so bycatch of other species is considerable. As the result, significant changes occurred in structure of benthic communities during the times of scallop fishery. To assess the fishery effect, species composition of benthos, its dominant species and trophic structure is considered separately for 4 regions with different degree of exploitation. Dynamics of zoobenthos abundance is traced over the last 25 years. Changes in trophic structure of the benthic community at Cape Svyatoy Nos (southern Barents Sea) are analyzed in details. Although up to ¼ of its total biomass is presented by carnivorous species and the biomass of C. islandica has decreased, the portion of sestonophages has increased in this community. Recently a recovery of zoob­enthos is observed in its southern part, supposedly because of the animals redistribution from adjacent areas unaffected by fishery. On the contrary, extremely low biomass of zoobenthos, in particular scallop, is observed in the northern part of the community. Biomass of benthos in the Voronka area is high, but it is formed mainly by mussels. There is concluded that more than a decade is required for full recovery of the scallop stock and accompanying zoobenthos communities to the native state.

Экология и распределение исландского гребешка Chlamys islandica (Bivalvia, Pectinidae) в Кольском заливе (Баренцево море)

Экология и распределение исландского гребешка Chlamys islandica (Bivalvia, Pectinidae) в Кольском заливе (Баренцево море)

In the darkness of the polar night, scallops keep on a steady rhythm.

Although the prevailing paradigm has held that the polar night is a period of biological quiescence, recent studies have detected noticeable activity levels in marine organisms. In this study, we investigated the circadian rhythm of the scallop Chlamys islandica by continuously recording the animal’s behaviour over 3 years in the Arctic (Svalbard). Our results showed that a circadian rhythm persists throughout the polar night and lasts for at least 4 months. Based on observations across three polar nights, we showed that the robustness and synchronicity of the rhythm depends on the angle of the sun below the horizon. The weakest rhythm occurred at the onset of the polar night during the nautical twilight. Surprisingly, the circadian behaviour began to recover during the darkest part of the polar night. Because active rhythms optimize the fitness of an organism, our study brings out that the scallops C. islandica remain active even during the polar night.

Is an Apicomplexan Parasite Responsible for the Collapse of the Iceland Scallop (Chlamys islandica) Stock?

Due to the total and unexpected collapse of the Iceland scallop, Chlamys islandica, stocks around Iceland during the 2000s, a commercial fishing ban has been imposed on this valuable resource since 2003. Following the initial identification of an apicomplexan parasite in the scallops, a long-term surveillance program was established to evaluate the effect of the parasite on the population. The infections were highly prevalent in all shell sizes throughout the study. However, the parasite only impacts mature scallops where they cause severe macroscopic changes, characterized by an extensively diminished and abnormally coloured adductor muscle. A highly significant relationship was observed between infection intensity and gonad and adductor muscle indices. The first four years of the study, were characterized by high infection intensity and very poor condition of the adductor muscle and gonads, whilst during subsequent years, infections gradually decreased and the condition of the scallops improved. Histopathological changes were restricted to the presence of apicomplexan zoites which were widely distributed, causing varying degrees of pathology in all organs. In heavy infections, muscular and connective tissues were totally necrotized, destroying significant parts of numerous organs, especially the adductor muscle, digestive gland and gonads. The progression of the disease was in good synchrony with the mortality rates and the subsequent decline observed in the scallop stock and recruitment indices. Our findings strongly suggest that the apicomplexan parasite played a major role in the collapse of the Iceland scallop stock in Breidafjordur. In addition to causing mortality, the infections significantly impact gonad development which contributes further to the collapse of the stock in the form of lower larval recruitment. Furthermore, compelling evidence exists that this apicomplexan pathogen is causing serious disease outbreaks in other scallop populations. Similar abnormal adductor muscles and the parasite itself have been identified or observed in association with other mass mortality events in several different scallop species and commercial stocks in the northern hemisphere.

Biomarker modulation associated with marine diesel contamination in the Iceland scallop (Chlamys islandica).

The decrease of ice cover in the Arctic will lead to an increase of ship traffic in the upcoming decades. Consequently, oil pollution is expected. In this context, the goals of this study were to evaluate the biological impact of marine diesel contamination and, on this basis, to determine analytical tools of interest (biomarkers) for future biomonitoring of diesel spills. Using a 7-day contamination protocol, this study investigated biochemical modulations in the digestive gland of the Iceland scallop (Chlamys islandica). Incorporation of contaminants was verified assessing haemolymph metabolites. Results showed a response of glutathione-S-transferase to contamination suggesting detoxification processes and the suitability of such a tool for diesel spill biomonitoring. The lack of modulation of superoxide dismutase activity and lipid peroxidation suggests no oxidative stress and the unsuitability of these molecular tools for biomonitoring.

Environmental effects monitoring at the Terra Nova offshore oil development (Newfoundland, Canada): Program design and overview

An environmental effects monitoring (EEM) program was developed by Suncor (formerly Petro-Canada) in 1997/98 to assess effects of the Terra Nova offshore oil and gas development on the receiving environment. The Terra Nova Field is located on the Grand Banks approximately 350km southeast of Newfoundland (Canada), at approximately 100m water depth. The EEM program was developed with guidance from experts in government, academia and elsewhere, and with input from the public. The EEM program proposed by Suncor was accepted by Canadian regulatory agencies and the program was implemented in 2000, 2001, 2002, 2004, 2006, 2008 and 2010, with pre-development sampling in 1997. The program continues to be implemented every two years. EEM includes an assessment of alterations in sediment quality through examination of changes in sediment chemistry, particle size, toxicity and benthic invertebrate community structure. A second component of the program examines potential effects on two species of commercial fishing interest: Iceland scallop (Chlamys islandica) and American plaice (Hippoglossoides platessoides). Chemical body burden for these two species is examined and taste tests are performed to assess the presence of taint in edible tissues. Effects on American plaice bioindicators are also examined. A final component of the program assesses potential effects of the Terra Nova development on water quality and examines water column chemistry, chlorophyll concentration and physical properties. The papers presented in this collection focus on effects of drill cuttings and drilling muds on the seafloor environment and, as such, report results on sediment quality and bioaccumulation of drilling mud components in Iceland scallop and American plaice. This paper provides information on drilling discharges, an overview of the physical oceanography at the Terra Nova Field, and an overview of the field program designed to assess environmental effects of drilling at Terra Nova.

Examination of body burden and taint for Iceland scallop (Chlamys islandica) and American plaice (Hippoglossoides platessoides) near the Terra Nova offshore oil development over ten years of drilling on the Grand Banks of Newfoundland, Canada

This paper presents results of analyses of body burdens of metals and hydrocarbons, and taste tests for taint, in Iceland scallop and American plaice performed as part of the Environmental Effects Monitoring (EEM) program for the Terra Nova offshore oil development (Grand Banks of Newfoundland, Canada). Scallop and plaice were collected in a Study Area located within approximately 1km of drill centres at Terra Nova and in a Reference Area located approximately 20km from the development. Samples were collected in 1997 to establish a baseline, and from 2000 to 2010, during drilling periods. Scallop adductor muscle tissue was contaminated with >C10–C21 aliphatic hydrocarbons resembling the drilling fluid in the synthetic drilling mud (SBM) used at Terra Nova in 2000, 2002 and 2004, but contamination of adductor muscle was not noted in 2006, 2008 and 2010. The maximum concentration in muscle was 28mg/kg wet weight, noted in 2002. Scallop viscera was contaminated with hydrocarbons resembling drilling fluid in SBMs near drill centres in all EEM years except 2010. Viscera contamination with >C10–C21 hydrocarbons gradually decreased from a maximum of 150mg/kg in 2000, to a maximum of 27mg/kg in 2008; all values were below the laboratory reporting detection limit of 15mg/kg in 2010. Therefore, evidence from both muscle and viscera indicates a decrease in tissue hydrocarbon contamination in recent years. Barium, another major constituent in drilling muds, has not been noted in scallop adductor muscles at concentrations above the reporting detection limit, but barium was detected in viscera in baseline and EEM years. The maximum concentration of barium in viscera during baseline sampling was 8mg/kg. The maximum concentration in EEM years (29mg/kg) was noted in 2000. The maximum concentration in 2010 was 25mg/kg. The concentration of metals other than barium in scallop tissues was similar between the Terra Nova Study Area and the Reference Area. Hydrocarbons resembling the fluid in SBMs were noted in one American plaice liver sample collected near drill centres in 2000. Otherwise, there has been no evidence of project-related metals or hydrocarbon contamination in plaice liver or fillet samples. There has been no evidence of taint (off-taste) for scallop adductor muscle and plaice fillet tissue in baseline or EEM years. Combined with a parallel study on fish bioindicators at Terra Nova that showed that fish health at Terra Nova was similar to that at the Reference Area (Mathieu et al., 2011), these results indicate little to no detectable biological effects on Iceland scallop and American plaice as a result of Terra Nova activities.

Phenotypic structure of the Iceland scallop (Chlamys islandica,Pectinidae,Bivalvia) settlements in the Barents and White seas

Phenotypic structure of the Iceland scallop (<i>Chlamys islandica,</i>Pectinidae<i>,</i>Bivalvia) settlements in the Barents and White seas

In vitro growth of calcium carbonate crystals on bivalve shells: Application of two methods of synthesis

The classic ammonium carbonate vapor diffusion method (VDM) and the coprecipitation method (CM) in its modified form were applied for in vitro growth of calcium carbonate crystals on glass substrate and on calcitic and aragonitic shell layers of blue mussel Mytilus edulis (L.) and Iceland scallop Chlamys islandica (M.). The experiments were carried out using large volumes of growth medium (250ml and 1000ml). Crystallization using the VDM is relatively slow, but faster with the CM. The formation of calcium carbonate polymorphs is strongly influenced by the mineralogical phase in the uppermost layer of the shell substrate bathed in the experimental solution, even if magnesium ions are added to solution with the CM. The morphology of calcium carbonate crystals clearly differs between methods, and is influenced by the type of substrate. The effect of biomacromolecules released from the shell substrate on morphology and organization of calcium carbonate crystals is clearly observed with both methods of crystallization.

Seasonal variation in biomarkers in blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua)—Implications for environmental monitoring in the Barents Sea

In the Barents Sea, the limited data on biological relevant indicators and their responses to various anthropogenic stressors have hindered the development of a consistent scientific basis for selecting indicator species and developing practical procedures for environmental monitoring. Accordingly, the main aim of the present study was to develop a common set of baseline values for contaminants and biomarkers in three species, and to identify their strengths and limitations in monitoring of the Barents Sea. Blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua) were sampled from a north Norwegian fjord in March, June, September and December 2010. Digestive glands from the bivalve species and liver from Atlantic cod were analysed for biomarkers of oxidative stress (catalase [CAT], glutathione peroxidase [GPX], glutathione-S-transferase activities [GST], lipid peroxidation as thiobarbituric reactive substances [TBARS] and total oxyradical scavenging capacity [TOSC]), biotransformation (ethoxyresorufine-O-deethylase activity [EROD]) and general stress (lysosomal membrane stability [LMS]). Concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals in the bivalves and PAH metabolites in fish bile were quantified. Finally, energy reserves (total lipids, proteins and carbohydrates) and electron transport system (ETS) activity in the digestive gland of the bivalves and liver of Atlantic cod provided background information for reproductive cycle and general physiological status of the organisms. Blue mussel and Icelandic scallop showed very similar trends in biological cycle, biomarker expression and seasonality. Biomarker baselines in Atlantic cod showed weaker seasonal variability. However, important biological events may have been undetected due to the large time intervals between sampling occasions. Physiological biomarkers such as energy reserves and ETS activity were recommended as complementary parameters to the commonly used stress biomarkers, as they provided valuable information on the physiological status of the studied organisms. Interpretation of the seasonality in oxidative stress biomarkers was in general difficult but TOSC and lipid peroxidation were preferred over the antioxidant enzyme activities. This study is the first reporting seasonal baseline in these three species in a sub-Arctic location. Overall, the Icelandic scallop was considered the most adequate organism for environmental monitoring in the Barents Sea due to the interpretability of the biomarker data as well as its abundance, ease to handle and wide distribution from the southern Barents Sea to Svalbard.

High carbon demand of dominant macrozoobenthic species indicates their central role in ecosystem carbon flow in a sub-Arctic fjord

The sea urchin Strongylocentrotus droebachiensis and the scallop Chlamys islandica dominate the shallow macrobenthic community in Kobbefjord, southwest Greenland (64° 09’ N, 51° 36’ W). Densities were estimated from seafloor photographs along 3 depth transects (0 to 120 m). Annually formed growth bands in the interambulacral plates of S. droebachiensis and in the ligament of C. islandica were used to establish growth functions. Growth data combined with size frequencies, size–mass relationships and fjord bathymetry were used to estimate annual production and carbon demand of the 2 species in order to assess their ecological importance. Distributions of the 2 species were strongly related to depth and partially separated. Averaged over all depths, the densities were estimated at 4.9 ind. m–2 (range: 0 to 38 ind. m–2) and 5.6 ind. m–2 (range: 0 to 57 ind. m–2) for S. droebachiensis and C. islandica, respectively. Maximum ages of S. droebachiensis and C. islandica were estimated at 24 and 39 yr, respectively. Somatic growth of both species was relatively slow, and their reproductive output constituted the bulk (62 to 73%) of their total annual production. Mean annual production in the fjord was estimated at 3.2 g ash-free dry weight (AFDW) m–2 for S. droebachiensis and 2.5 g AFDW m–2 for C. islandica. The total annual carbon demand of the 2 species was estimated at 30.6 g C m–2, corresponding to 21–45% of annual pelagic primary production in this area. In conclusion, S. droebachiensis and C. islandica play important roles in carbon cycling of Kobbefjord and can be regarded as central species of the shallow benthic community. A comparison with literature estimates of annual macrozoobenthic carbon demand in Arctic and sub-Arctic habitats revealed that the macrozoobenthic carbon demand in Kobbefjord is relatively high and that annual carbon requirements of macrozoobenthos in the Arctic seem to reflect the level of pelagic primary production.

Immune function in the Arctic Scallop, Chlamys islandica, following dispersed oil exposure

With the current expansion of offshore oil activities in Arctic regions, there is an urgent need to establish the potential effects of oil-related compounds on Arctic organisms. As susceptibility to growth, disease and survival is determined partly by the condition of an organism's immune system, measurement of endpoints linked to the latter system provide important early warning signals of the sub-lethal effects of exposure to contaminants. This study assessed the impact of dispersed oil exposure on immune endpoints in the Arctic Scallop Chlamys islandica, using a combination of cellular and humoral biological responses. Laboratory exposures of C. islandica to sub-lethal dispersed oil concentrations (0.06 and 0.25 mg l −1) were conducted over 15 days, followed by a 7-day recovery period in clean, filtered seawater. Cellular endpoints were significantly altered following dispersed oil exposure: haemocyte counts ( P < 0.01) and protein levels ( P < 0.01) were significantly elevated, whilst cell membrane stability ( P < 0.001) and phagocytosis ( P < 0.01) demonstrated a significant reduction. Whilst these results indicate alteration in the immune endpoints measured, this appears to be reversible upon removal of the contaminant stress. However, the impact of long-term continuous exposure and high-level acute exposure to oil is still unknown, and may have consequences for disease resistance and hence survival.

Toward a sustainable Iceland scallop fishery in Gilbert Bay, a marine protected area in the eastern Canada coastal zone

Iceland scallop ( Chlamys islandica) stocks in the North Atlantic are usually pulse harvested, resulting in boom and bust local landings. We describe an adaptive management strategy for a sustainable harvest of Iceland scallops in Gilbert Bay, a Marine Protected Area (MPA) of coastal Labrador. The current management plan for the MPA closes pristine scallop habitat, a practice that under favourable ocean conditions may lead to local reseeding. The community-based co-management structure for the MPA utilizes the local ecological knowledge of fishermen. Scallop harvesters are participating in research on the present state of the resource. Currently scallops are smaller near the mouth of the bay where fishing effort has been concentrated historically. The cooperation of fishers in enforcing area closures and in monitoring the scallop harvest may lead to a sustainable scallop fishery.

Multi-decadal changes in the megabenthos of the Bay of Fundy: The effects of fishing

Analysis of presence / absence records from two comparable megabenthic surveys of scallop grounds in the Bay of Fundy, Canada, in 1966–67 and 1997 showed profound change over three decades. There were no indications that any species were lost and the average number of taxa per station remained steady. However, spatial heterogeneities in the community were reduced and species composition changed significantly. Some taxa widespread in 1966–67 declined while others expanded, with frequencies of occurrence of individual taxa changing by up to 71%. The whelks Buccinum undatum and Colus spp., the bivalves Astarte spp. and Cyclocardia borealis, the toad crabs Hyas spp., the sea urchin Strongylocentrotus droebachiensis and the brittle stars (Ophiurida) showed particular increases. Corresponding declines were seen in the boring sponges Cliona spp., the horse mussel Modiolus modiolus, the scallop Chlamys islandica, the fan worm Pseudopotamilla reniformis and the stalked tunicate Boltenia ovifera. Replacement of attached, fragile, epifaunal, filter-feeding taxa by a combination of motile scavengers, motile filter-feeders and robust, burrowing filter-feeders suggests that the primary cause of the temporal change was physical impacts by fishing gear, even though trawling and scallop dragging in the area were neither intense nor new developments. Secondary causes of change may have included other ecosystem effects of fishing (supply of discards and bait), a mass mortality of scallops and a range expansion of a bryozoan ( Flustra foliacea).

Collapse of the fishery for Iceland scallop (Chlamys islandica) in Breidafjordur, West Iceland

AbstractJonasson, J. P., Thorarinsdottir, G., Eiriksson, H., Solmundsson, J., and Marteinsdottir, G. 2007. Collapse of the fishery for Iceland scallop (Chlamys islandica) in Breidafjordur, West Iceland. – ICES Journal of Marine Science, 64: 298–308. The stock index of the Iceland scallop (Chlamys islandica) in Breidafjordur on the west coast of Iceland has declined drastically in recent years. Total fishing mortality was very high throughout the study period from 1993 to 2003, a period characterized by a steady increase in summer sea surface temperature, in 2003 reaching the highest estimated level of the previous century. Between 1998 and 2005, estimates of chlorophyll a (food availability) fluctuated with periods of low chlorophyll followed by a reduction in muscle weight and high natural mortality. High levels of natural mortality were observed in the main fishing area in the southern part of Breidafjordur. There the stock index had been declining since 1994. Recruitment to the fishable stock was highly variable during the study period, with low recruitment towards the end of the 1990s. Subsequently the fishery has been on relatively few year classes, and the stock has been fragile because of several years of poor recruitment and high natural mortality. Consequently, the stock appeared unable to withstand the fishing pressure and declined to historically low levels, leading to a halt to fishing in 2004.

Swimming Performance, Metabolic Rates, and Their Correlates in the Iceland ScallopChlamys islandica

The dramatic escape response of some scallops is modified by reproductive investment and by acclimation temperature. Despite considerable knowledge of the physiology of the escape response, functional links between escape response performance, organismal rates of oxygen uptake, and tissue metabolic capacities are little known. We measured oxygen consumption rates (standard, maximal, and aerobic scope), escape behavior (initial and repeat performance), tissue mass, condition index, protein content, and tissue metabolic capacities in the Iceland scallop Chlamys islandica to examine links between these parameters. Postexercise oxygen consumption rates were positively linked to contraction rate (repeat test) and to pyruvate kinase activity in the adductor muscle but negatively linked to digestive gland wet mass. Swimming behavior was mainly related to activity of glycolytic enzymes, and enzymatic activities were related to anatomic parameters. Scallop behavior and physiology change with size, both within our samples and on a larger scale. Small scallops showed more intense swimming activity and had higher arginine kinase activities but lower glycolytic enzyme activities in their adductor muscle than larger scallops. This corresponds to the ontogenetic change in susceptibility to predation and in habitat use observed in C. islandica.

Deoxyribonuclease II from the Icelandic scallop ( Chlamys islandica): Isolation and partial characterization

A deoxyribonuclease (DNase) was isolated from viscera of the cold-adapted marine bivalve Icelandic scallop. The 42 kDa DNase was shown to be a single polypeptide which catalyses DNA hydrolysis in the absence of divalent cations. The isolated enzyme showed maximal activity at pH 6 and no activity above pH 7.2 against native DNA. The scallop DNase was slightly more susceptible to heat denaturation than porcine DNase II and makes double-strand breaks in circular DNA substrate as the porcine enzyme. The N-terminal sequence of the scallop DNase was shown to be closely similar to DNase II (EC 3.1.22.1) proteins from other organisms. The scallop DNase is in addition to plancitoxin I from A. planci, the only DNase II enzyme isolated from marine invertebrates.

Impact Scenario for an Introduced Decapod on Arctic Epibenthic Communities

The intentional introduction of a species for the enhancement of stock or establishment of new fisheries, often has unforeseen effects. The red king crabs, Paralithodes camtschaticus, which was introduced into the Barents Sea by Russian scientists, has established a self-sustaining population that has expanded into Norwegian waters. As top benthic predators, the introduced red king crabs may have possible effects upon native epifaunal scallop (Chlamys islandica) communities. These benthic communities may be a source of prey species in late spring, when the red king crabs feed most intensively. Foraging rates (consumption, killing or severely damaging) of red king crab on native prey organisms were measured by factorial manipulation of crab density (0.5, 1.5 and 3 per m 2), size classes (immature, small mature, and large mature crabs), and by evaluating prey consumption after 48 h, in order to extrapolate a scenario of the likely impacts. Foraging rates of the red king crab on scallops ranged between 150 and 335 g per m2 within 48 h. These rates did not change when crab density was altered, though an increased amount of crushed scallops left uneaten at the tank floor, were correlated with high density of small mature crabs. Foraging rate changed significantly with crab size. Consequently, the susceptibility of native, shallow water epibenthic communities to red king crab predation in the early life history stages, and during the post-mating/molting spring period, must be considered significant when foraging rates are contrasted with natural scallop biomass between 400 and 1200 g scallops per m2.