Juvenile Scallops Research Articles

Results of economic activity and problems of aquaculture development in the Possiet Bay (Japan Sea) in 2000–2015

The Possiet Bay in the western Japan Sea is crucially important for marine aquaculture of Primorye because of the environments favorable for cultivation of many aquatic species. The local marine farms cultivate sea cucumber and several bivalve species, including the most valuable yesso scallop, which output production is counted in hundreds of tons. The number of farms in the Possiet Bay increases recently, as well as their production of seeding materials and marketable output of seafood. Cultivation of 3 bivalve species (yesso scallop, pacifc blue mussel, and pacifc oyster) and 1 holothurian species (japanese spiky sea cucumber) is considered. The seeding material is collected by the farms located in the Possiet Bay, which prefer to collect more valuable spat of the scallop and sea cucumber, while the mussel and oyster are collected in smaller amounts. In total, more than 640 million of the scallop juveniles and about 1.2 million of the sea cucumber juveniles were collected by local farms in the period from 2000 to 2015, including both the spat collected on their own collectors or bought from other vendors. Dynamics of the output is presented for these species. The greatest harvest of the marketable scallop (over 1800 t) was produced in 2006–2010, with the highest annual output over 510 t. The summary production of all marine farms in the Possiet Bay within the 15-year period (2001–2015) is estimated as 4,300 t, that exceeds the registered catch of scallop in this area in the whole history of its fshery (that was banned in the middle of 1980s). Even before the fshery opening in the early XX century, the yeaso scallop biomass in this area did not exceed 1,000 t. Dynamics of anthropogenic pressure to the Possiet Bay waters is analyzed, as well. There is concluded that yesso scallop has natural ability to considerable growth of its biomass because of high fecundity, though this potential is limited by lack of substrate for the spat settling that is successfully compensated with artifcial substrata provided by marine farms. However, the growth of scallop biomass and production causes higher phytoplankton consumption, increasing of water pollution by dissolved and particulate organic matter, and accumulation of metabolic by-products in marine organisms. Rapid development of aquaculture causes some social and ecological risks, as well, as territorial disputes, legislative problems (with harvesting permits, etc.), starfsh expansion, grazing of farmed mollusks by marine birds, destruction of aquaculture facilities in new areas located in the insuffciently closed bights by typhoons, and epizootics (most dangerous for the sea cucumbers).

Embryo-larvae and juvenile toxicity of Pb and Cd in Northern Chilean scallop Argopecten purpuratus.

This study aimed to investigate the effects of Cd and Pb on earlier stage of the commercially important scallop (Argopecten purpuratus) in the contamination context of Northern Chile where this specie is farmed, through acute exposure bioassays in embryo-larvae measuring cumulative abnormality (EC50) and juvenile cumulative mortality (LC50) as endpoints, based on environmentally detected concentrations and available toxicological data from similar species. Embryo-larvae exposure indicates 48h EC50 of 1.55mg/L Cd, and 0.044mg/L Pb. On the contrary, 96h LC50 in juvenile scallops was 0.48mg/L Cd and 1.47mg/L Pb. Our results demonstrated differential toxicity between embryo and juvenile scallops that might relate to different primary defense mechanisms or effect in morphological development of individuals in each ontogenetic stage. Compared to similar bivalve metal toxicity tests, this study demonstrated that A. purpuratus embryos are more sensitive to Pb than most other bivalve species. Our results indicate that maximum permitted levels of Pb in marine waters and estuaries (according to Chilean regulation) could pose a risk for scallops' first stage of life (embryo-larvae) development, and needs to be reviewed. Furthermore, Chilean environmental regulations do not have quality standards for marine sediments (currently under discussion), where high levels of metals have been continuously reported.

Breaking out of the comfort zone: El Niño-Southern Oscillation as a driver of trophic flows in a benthic consumer of the Humboldt Current ecosystem.

The trophic flow of a species is considered a characteristic trait reflecting its trophic position and function in the ecosystem and its interaction with the environment. However, climate patterns are changing and we ignore how patterns of trophic flow are being affected. In the Humboldt Current ecosystem, arguably one of the most productive marine systems, El Niño-Southern Oscillation is the main source of interannual and longer-term variability. To assess the effect of this variability on trophic flow we built a 16-year series of mass-specific somatic production rate (P/B) of the Peruvian scallop (Argopecten purpuratus), a species belonging to a former tropical fauna that thrived in this cold ecosystem. A strong increase of the P/B ratio of this species was observed during nutrient-poor, warmer water conditions typical of El Niño, owing to the massive recruitment of fast-growing juvenile scallops. Trophic ecology theory predicts that when primary production is nutrient limited, the trophic flow of organisms occupying low trophic levels should be constrained (bottom-up control). For former tropical fauna thriving in cold, productive upwelling coastal zones, a short time of low food conditions but warm waters during El Niño could be sufficient to waken their ancestral biological features and display massive proliferations.

Physiological and histopathological impacts of increased carbon dioxide and temperature on the scallops Argopecten purpuratus cultured under upwelling influences in northern Chile

In addition to the increase in temperature occurring in the world's oceans, new evidences suggest a tendency for an increase in upwelling-favorable winds, bringing to surface cold and high pCO2 corrosive waters. Changing temperature and pCO2 conditions may have significant implications for the shellfish farming socio-ecological system. In order, to setup the basis for understand the impact of both environmental variables, in this study, we investigated the combined effects of changing temperature and pCO2 on the physiological rates and histopathology of scallops Argopecten purpuratus farmed in Tongoy Bay, an area permanently influenced by coastal upwelling. Juvenile scallops were reared at two pCO2 levels (400 and 1000μatm) and two temperatures (14 and 18°C). After 18d of experimental exposure, growth, metabolic and clearance rates increased significantly at high temperature but independent of pCO2 level, indicating a positive effect of warming on the physiological processes associated with energy acquisition. However, ingestion rates of scallops showed a synergistic interactive effect when exposed to both stressors. Increased pCO2 also impacts the health of A. purpuratus through atrophy in the digestive gland. These results suggest that, the presence of trade-offs in energy allocation during upwelling-induced stress (low temperature and high pCO2) can impact growth, metabolism, ingestion rates and health status of scallops cultured in Tongoy Bay. But, less severe response to high pCO2 levels, suggest that natural variability in upwelling areas may promote acclimation and adaptation potential in this farmed scallops.

Homeopathy outperforms antibiotics treatment in juvenile scallop Argopecten ventricosus: effects on growth, survival, and immune response.

Mortality from vibriosis in mollusk production is attributed to pathogenic bacteria, particularly Vibrio alginolyticus. Use of increasingly potent antibiotics has led to bacterial resistance and increased pathogenicity. Alternatives in sanitation, safety, and environmental sustainability are currently under analysis. To-date, homeopathy has been investigated in aquaculture of freshwater fish, but not in marine mollusks. The effect of the homeopathic complexes in the growth, survival, and immune response of the Catarina scallop Argopecten ventricosus were assessed. A bioassay to assess the potential of homeopathy in improving cultivation of juvenile A. ventricosus was conducted for 21 days, with a final challenge of 120h with V. alginolyticus. The experimental design included two homeopathic formulas The homeopathic complex Passival, consisting of Passiflora incarnata 30 CH, Valeriana officinalis 30 CH, Ignatia amara 30 CH and Zincum valerianicum 30 CH plus Phosphoricum acid 30 CH (treatment TH1) or Silicea terra 30 CH (TH2), two antibiotics (ampicillin=AMP, oxytetracycline=OXY), and two reference treatments (without homeopathic or antibiotic treatment=CTRL, ethanol 30° GL=ETH). Additionally, a negative control CTRL-(untreated/uninfected) is included in the challenge test. Juvenile scallops (4.14±0.06mm, 13.33mg wet weight) were cultivated in 4L tanks provided with aerated, filtered (1μm), and UV-sterilized seawater that was changed every third day. They were fed a blend of the microalgae Isochrysis galbana and Chaetoceros calcitrans (150,000cellsmL-1 twice a day). All treatments were directly added to the tank water and then 500mL challenge units were inoculated with 1×107CFU/mL (LD50) of V. alginolyticus. Juveniles grew significantly larger and faster in height and weight with TH2 compared to the ETH and CTRL (P < 0.05, ANOVA). Higher concentrations of proteins occurred in scallops exposed to TH2 (160.57±7.79mgg-1), compared to other treatments and reference treatments. Higher survival rate during the challenge bioassay occurred with TH1 (85%), compared to AMP (53%), OXY (30%), and CTRL (0%), and superoxide dismutase (P < 0.05) was significantly higher in scallops treated with TH1, compared to other treatments and reference treatments. Homeopathic treatments improved growth and survival and enhanced survival against V. alginolyticus in juvenile A. ventricosus. This suggests that homeopathy is a viable treatment for this mollusk to reduce use of antibiotics in scallops and its progressive increase in pathogenicity in mollusk hatcheries.

The efficiency of Yesso scallop (Mizuhopecten yessoensis) aquaculture in Ussuri Bay (Sea of Japan)

Data on cultivation of the Yesso scallop, Mizuhopecten yessoensis, in Ussuri Bay are summarized. The sea-based farms that are established in the shallow waters at depths of 2–18 m differ in the area occupied by their facilities and the hydrodynamic characteristics. A farm with a complex structure (collectors, cages, and bottom cultures) operates in the semi-enclosed Sukhodol Bay. In the other two bays, mostly bottom facilities for ranching scallop and sea cucumber are used. The local scallop broodstocks were formed by introducing juveniles from Posyet Bay. As a result, at least 20 million scallop spat were collected in these three bays from 2000 to 2014. The total yield of market-size scallops was approximately 216 tons, of which over 111 t were obtained in Sukhodol Bay, 70 t in Ilmovaya Bay, and 35 t in Malye Kushi Bay. Analysis showed that the potential for the development of this type of aquaculture in the region was limited. The mean long-term value of the spat density was not higher than 200 spat per collector and did not increase throughout the period of operation of the farms. Thus, farmers had to increase the number of collectors to obtain the required quantity of scallop seed. Some years were unfavorable for harvesting juvenile scallop at all of the farms along the eastern coast of Ussuri Bay. The environmental conditions in these waters are not optimal for Yesso scallop cultivation by the extensive method.

Characterization of bacterial communities associating with larval development of Yesso Scallop (Patinopecten yessoensisis Jay, 1857) by high-throughput sequencing

Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop (Patinopecten yessoensisis Jay, 1857) larval development stages. The aim of this study was to characterize and compare the bacterial communities associating with Yesso scallop larval development at fertilized egg S1, trochophora S2, D-shaped larvae S3, umbo larvae S4, and juvenile scallop S5 stages by Illumina high-throughput sequencing. Genomic DNA was extracted from the larvae and their associating bactera, and a gene segment covering V3-V4 region of 16S rRNA gene was amplified and sequenced using an Illumina Miseq sequencer. Overall, 106760 qualified sequences with an average length of 449 bp were obtained. Sequences were compared with those retrieved from 16S rRNA gene databases, and 4 phyla, 7 classes, 15 orders, 21 families, 31 genera were identified. Proteobacteria was predominant phylum, accounting for more than 99%, at all 5 larval development stages. At genus level, Pseudomonas was dominant at stages S1 (80.60%), S2 (87.77%) and S5 (68.71%), followed by Photobacterium (17.06%) and Aeromonas (1.64%) at stage S1, Serratia (6.94%), Stenotrophomonas (3.08%) and Acinetobacter (1.2%) at stage S2, Shewanella (25.95%) and Pseudoalteromonas (4.57%) at stage S5. Moreover, genus Pseudoalteromonas became dominant at stages S3 (44.85%) and S4 (56.02%), followed by Photobacterium (29.82%), Pseudomonas (11.86%), Aliivibrio (8.60%) and Shewanella (3.39%) at stage S3, Pseudomonas (18.16%), Aliivibrio (14.29%), Shewanella (4.11%), Psychromonas (4.04%) and Psychrobacter (1.81%) at stage S4. From the results, we concluded that the bacterial community changed significantly at different development stages of Yesso Scallop larvae.

Efficiency of scallop &lt;i&gt;Mizuhopecten yessoensis&lt;/i&gt; cultivation in the Ussuri Bay (Japan Sea)

Data on cultivation of scallop Mizuhopecten yessoensis in the Ussuri Bay are generalized. The marine farms are located in the shallow waters at depths of 2-18 m, their plantations occupy different areas with different hydrodynamics. Complex structure of the plantations (collectors, cages and bottom facilities) is formed in the semi-closed Sukhodol Bay, but bottom plantations only for growing of scallop and sea cucumber are mounted in two other bays. The local broodstocks of scallop were formed by juveniles transported from the Posyet Bay, after that at least 20 million individuals of scallop spat were collected in three bays in 2000-2014, and their growing gave the total commercial output about 216 t (111 t in the Sukhodol Bay, 70 t in the Ilmovaya Bay, and 35 t in the Malye Kushi Bay). This is rather weak result that shows that the area has limited abilities for development of this type of aquaculture. The main reason was low density of spat on substrata: it never exceeded 200 ind./collector and did not increase during the farms development, so the farmers were forced to increase the number of collectors to obtain required number of spat; moreover, some years were unfavorable for collecting of juvenile scallops. There is concluded that environmental conditions in the eastern Ussuri Bay are not optimal for the scallop cultivation by extensive method.

Influence of water depth on growth and mortality of Chlamys varia (Linnaeus, 1758): implications for cage culture in Mali Ston Bay, Croatia

This study investigated growth and mortalities of juvenile variegated scallops Chlamys varia (Linnaeus, 1758) grown in suspension at Mali Ston Bay in the Adriatic Sea. Juveniles collected from the previous year’s natural breeding, mean length of 14.58 mm, were placed in cages at three depths (1, 3 and 5 m), for 21 months. We compared results on shell heights at the end of growth period in relation to seawater temperature and salinity. Shell lengths averaged 45.30 ± 4.10 mm (range 39–54 mm) at 1 m depths, 42.48 ± 2.40 mm (39–48 mm) at 3 m, and 41.90 ± 4.25 mm (37–50 mm) at 5 m. Average monthly growth of shell height throughout the experimental period was 1.7 (1 m), 1.6 (3 m) and 1.7 mm (5 m). Total mortality throughout the experimental period was 25.0 % (1 m), 16.6 % (3 m) and 71.4 % (5 m). Furthermore, we estimate von Bertalanffy growth parameters from growth increment models, where extensions of the von Bertalanffy model that allow growth rate to vary with changing body size and with periodic (seasonal) changes in the growth parameter K are presented. The goal of this research was to evaluate the potential for commercial aquaculture of C. varia (growth rate, degree of survival and quality of the soft tissue) caged at different depths. Based on a combination of mortality and growth rate, we found that the most suitable depth for culture was at 1 m, but culture at all three depths is viable and the main issue is being the source of mortality at 5 m, seasonally. We conclude that Mali Ston Bay has good potential for variegated scallop mariculture.

Overview of the biology of Flexopecten glaber in the North Western Adriatic Sea (Italy): A good candidate for future shellfish farming aims?

To assess the potential for rearing in smooth scallops (Flexopecten glaber) from the North Western Adriatic Sea, various biological traits were studied in both fished and reared individuals. Condition and gonadosomatic indices, gonadic cycle, biochemical components and histopathological conditions were investigated in adults from commercial fishing. Throughout two consecutive years, juvenile scallops were collected by means of artificial collectors and maintained in an experimental rearing facility. Growth, onset of sexual maturity, size/age at first maturity were investigated in reared individuals. In fished scallops, spawning and resting periods occurred mostly between July and September and from October to December, respectively. Gonadosomatic index and condition index increased from January to June and decreased from July to October; these main variations corresponded to gametogenesis and spawning, respectively. In both somatic and gonadic tissues, proteins were the major biochemical component (about 80%), with no evident seasonal variation. In somatic tissues, total carbohydrates were always higher than lipids; in gonads, lipids exceeded total carbohydrates for most of the year, peaking at maximum values when only mature or spawning animals were found. Observation and quantification of abnormal features of gonadic tissues, like oocyte atresia, haemocytic infiltration, neoplasia, and presence of parasites, suggest the overall good health conditions of scallops in the study area, no serious threat due to diseases being evident. In reared scallops, sexual maturity was attained within the first year, thus indicating F. glaber as a fairly early maturation species compared with other scallop species. The first maturity event occurred in about 330days from the immersion of the collectors, at mean shell height values ranging from 22.4 to 25.1mm, well below the minimum landing size (40mm) established by the EU for queen scallop fishery in Atlantic waters. Appreciable growth rates and a relatively short grow-out period, precociousness in maturation, high availability of wild spat, easily and inexpensively collected, absence of diseases and other mortality factors are promising elements to introduce the cultivation of F. glaber in the North Western Adriatic coastal waters. Statement of relevanceTo assess the potential for rearing in smooth scallops (F. glaber) from the North Western Adriatic Sea, various biological traits in both fished and reared individuals were studied for the first time. The overall results indicate this species as a potential candidate to diversify Italian marine bivalve aquaculture.

Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification.

Future ocean acidification (OA) will affect physiological traits of marine species, with calcifying species being particularly vulnerable. As OA entails high energy demands, particularly during the rapid juvenile growth phase, food supply may play a key role in the response of marine organisms to OA. We experimentally evaluated the role of food supply in modulating physiological responses and biomineralization processes in juveniles of the Chilean scallop, Argopecten purpuratus, that were exposed to control (pH ~ 8.0) and low pH (pH ~ 7.6) conditions using three food supply treatments (high, intermediate, and low). We found that pH and food levels had additive effects on the physiological response of the juvenile scallops. Metabolic rates, shell growth, net calcification, and ingestion rates increased significantly at low pH conditions, independent of food. These physiological responses increased significantly in organisms exposed to intermediate and high levels of food supply. Hence, food supply seems to play a major role modulating organismal response by providing the energetic means to bolster the physiological response of OA stress. On the contrary, the relative expression of chitin synthase, a functional molecule for biomineralization, increased significantly in scallops exposed to low food supply and low pH, which resulted in a thicker periostracum enriched with chitin polysaccharides. Under reduced food and low pH conditions, the adaptive organismal response was to trade-off growth for the expression of biomineralization molecules and altering of the organic composition of shell periostracum, suggesting that the future performance of these calcifiers will depend on the trajectories of both OA and food supply.Thus, incorporating a suite of traits and multiple stressors in future studies of the adaptive organismal response may provide key insights on OA impacts on marine calcifiers.

Homeopathy for mollusk aquaculture: Increased growth, survival, and protection of juvenile Catarina scallop Argopecten ventricosus against bacterial pathogen-challenge

Angel I. Campa-Cordova 1d, Pedro E. Saucedo 1e & Carmen Rodriguez-Jaramillo 1. 1 Centro de Investigaciones Biologicas del Noroeste ( CIBNOR ), La Paz, B.C.S., MEXICO. 2 Centro de Bioactivos Quimicos ( CBQ ), Universidad Central de Las Villas, Villa Clara, CUBA. 3 Instituto Nacional de Pesca ( INAPESCA ), La Paz, B.C.S., MEXICO. * Email: jmazon04@cibnor.mx Homeopathy for mollusk aquaculture: Increased growth, survival, and protection of juvenile Catarina scallop Argopecten ventricosus against bacterial pathogen-challenge

Current productivity of the scallop ( &lt;i&gt;Mizuhopecten yessoensis&lt;/i&gt;) plantations in the bights of the Ussuri Bay (Japan Sea)

Dynamics of the scallop spat settling to collectors of marine farms in the Sukhodol Bay and Malye Kushi Bay (Ussuri Bay) in 2012-2014 is considered. In the Sukhodol Bay, the spat density was 225 ind./m 2 in 2012 that is close to usual value, but only 31 ind./m 2 in 2013. In the Malye Kushi Bay, both years of 2013 and 2014 were low-productive for the spat, with its density in 2.5 times lower than in the Sukhodol Bay. On the contrary, the number of starfish spat on collectors was extremely high in 2013 - up to 42 ± 3 ind./m 2 . Size and weight parameters of juvenile scallops and starfish on collectors had year-to-year changes, as well. The starfish grown in conditions of high density in the 2013 had relatively small diameter (45.9 mm on average) and weight (1.8 g on average) in the age 1 year (in 2014), whereas the starfish spat grown in the 2014 with the density lower in 5.5 times reached larger mean size (55.5 mm) and weight (3.3 g). The scallop spat harvest in the bights of the Ussuri Bay is assessed in 0.5-1.5 · 10 6 ind./hectare. In general, the spat settling in this area is less intensive than in the Posyet Bay, Vostok Bay, and Nakhodka Bay. Environmental conditions in the Ussuri Bay are not favorable for collection of juvenile scallops, so the technology of scallop cultivation should be adapted for this area.

Early post-settlement mortality of the scallop Pecten fumatus and the role of algal mats as a refuge from predation

Abstract Early post-settlement mortality is one of the main processes determining distribution and abundance patterns of marine benthic invertebrates. Most scallops have an attached phase as spat before they release the byssus and move onto the soft sediments. Thus, spat differ from other stages of life in their use of microhabitat, lack of mobility, and therefore in their vulnerability to mortality processes such as predation. However, the contribution of predation to explain levels of mortality experienced by spat and early juvenile scallops is unknown. Complex habitats such as seagrasses and algae provide a substrate upon which spat can attach and might confer an advantage as a refuge from predation. This study investigates the contribution of early post-settlement predation on abundance of Pecten fumatus and determines the role of the algae Hincksia sordida as a refuge from predation. Data were collected using field observations, a predator exclusion experiment, and tethering techniques. Mortality of up to 85% during the first weeks after settlement appeared to have prevented the establishment of an adult population at our study site. Mats of the macroalgae H. sordida provided a settlement substrate for P. fumatus spat. However, increased algal biomass did not provide greater protection from predation to juvenile scallops than lower algal biomass. Our study suggests that prey survival in submersed vegetation is likely to be dynamic among years, and affected by prey behaviour and density as well as the characteristics of the submerged vegetation.

Effect of different predators on the escape response of Placopecten magellanicus

To assess whether giant scallops, Placopecten magellanicus use distinct escape strategies to respond to their seastar and crustacean predators, escape responses to two major seastar predators, Asterias vulgaris and Leptasterias polaris, two seastars with little predatory impact, Crossaster papposus and Solaster endeca, and two crustacean predators, Cancer irroratus and Hyas araneus were compared. A glass rod served as a mechanical control. The responses of juvenile [2+ year (y), ~36-mm shell height (SH)] and adult (6+ y, ~100-mm SH) scallops from the Magdalen Islands, Quebec, Canada, were assessed in early summer 2005. The predatory seastars evoked the strongest response, in terms of both response latency and minimum interval between phasic contractions and numbers of phasic contractions, particularly early in the escape response. Both the minor seastar predators and crabs stimulated stronger responses than the mechanical control. Juvenile scallops were livelier than adult scallops. As P. magellanicus consistently responded to predators with an initial flurry of phasic contractions that tapered off to spaced phasic contractions separated by increasingly long tonic contractions, only the intensity of the escape response seems to have been modified by selection.

Development of the pallial eye in Nodipecten nodosus (Mollusca: Bivalvia): insights into early visual performance in scallops

Scallop pallial eyes have been the most studied optical system in bivalve mollusks. Despite recent advances in our understanding of the function and evolution of scallop eyes, little attention has been focused on eye development and early visual performance. Here, the anatomy and development of pallial eyes were investigated in the scallop Nodipecten nodosus (Linnaeus, 1758) by means of integrative microscopy techniques (i.e., light, electron, and confocal microscopy). After metamorphosis, juvenile scallops bear small papillae that rapidly transform into minute ocular organs on the middle mantle fold. The distal epithelium gradually becomes pigmented, except for the cornea formed at the distal center of the eye. Internally, the optic vesicle comprises undifferentiated cells in the distal region, while mirror plates are secreted at the base of the eye, next to pigmented cells. Within the undifferentiated cell mass, the proximal retina is the first to be formed, followed by the distal retina and then by the lens. In this respect, the late development of the scallop lens from retina precursor cells may represent a unique condition among animal eyes. Adult eyes are characterized by large pigment distribution in the epithelium, tall columnar cornea, and lens above a slightly curved double retina. Whereas the pallial eyes from adult scallops are a complex visual system based on a mirror mechanism to form a focused image on the retina, early eye condition suggests a simple degree of directional photoreception, with no spatial vision.

Effects of ecosystem protection on scallop populations within a community-led temperate marine reserve

This study investigated the effects of a newly established, fully protected marine reserve on benthic habitats and two commercially valuable species of scallop in Lamlash Bay, Isle of Arran, United Kingdom. Annual dive surveys from 2010 to 2013 showed the abundance of juvenile scallops to be significantly greater within the marine reserve than outside. Generalised linear models revealed this trend to be significantly related to the greater presence of macroalgae and hydroids growing within the boundaries of the reserve. These results suggest that structurally complex habitats growing within the reserve have substantially increased spat settlement and/or survival. The density of adult king scallops declined threefold with increasing distance from the boundaries of the reserve, indicating possible evidence of spillover or reduced fishing effort directly outside and around the marine reserve. However, there was no difference in the mean density of adult scallops between the reserve and outside. Finally, the mean age, size, and reproductive and exploitable biomass of king scallops were all significantly greater within the reserve. In contrast to king scallops, the population dynamics of queen scallops (Aequipecten opercularis) fluctuated randomly over the survey period and showed little difference between the reserve and outside. Overall, this study is consistent with the hypothesis that marine reserves can encourage the recovery of seafloor habitats, which, in turn, can benefit populations of commercially exploited species, emphasising the importance of marine reserves in the ecosystem-based management of fisheries.

큰가리비 (Patinopecten yessoensis) 치패의 양성지역에 따른 성장 특성 연구

현 시점에서 동해 북부에 한정되어 양식이 이루어지고 있는 큰가리비 양식생산량 확대를 위하여 동부 북부에서 남부까지 양식시험을 통하여 성장 특성을 분석하여 생식생산량 확대를 위한 기초자료를 활용하고자 한다. 조기 종묘의 성장 특성으로 2014년 2월에 채란 및 채묘한 치패의 평균 각장, 각고는 <TEX>$0.23{\pm}0.002mm$</TEX>이였다. 고성장군의 경우, 6월에 평균 각장, 각고는 각각 <TEX>$4.11{\pm}0.08mm$</TEX>, <TEX>$4.28{\pm}0.09mm$</TEX>이였다. 10월에는 <TEX>$23.63{\pm}3.4mm$</TEX>, <TEX>$24.19{\pm}4.5mm$</TEX>이었다. 저성장군의 경우, 6월에 평균 각장, 각고는 각각 <TEX>$2.23{\pm}0.7mm$</TEX>, <TEX>$1.99{\pm}0.9mm$</TEX>이였고, 10월에 <TEX>$1.99{\pm}0.9mm$</TEX>, <TEX>$17.59{\pm}4.5mm$</TEX>로 성장하였다. 일간성장률은 고성장군은 0.037 mm/day, 저성장군은 0.027 mm/day 이었다. 8월에 지역별로 큰가리비의 성장을 보면 양양군, 강릉시, 영덕군, 포항시의 평균각장은 <TEX>$7.93{\pm}0.2mm$</TEX>으로 지역별로 큰가리비를 양성 시험한 결과, 포항 지역에서 각장 <TEX>$26.90{\pm}3.6mm$</TEX>로 가장 성장이 양호하였다. 이어서 영덕 지역이 <TEX>$23.56{\pm}3.4mm$</TEX>으로 나타났다. 이러한 결과로는 포항, 영덕 해수온과 식물플랑크톤이 큰가리비 성장에 적합하게 형성된 것으로 판단된다. Patinopecten yessoensis is known to be farmed only in the northern part of the East Sea today. In an attempt to extend its production area, we have conducted experiments both in the northern and southern parts of the East Sea and studied on their growth in an aim to use the results for increasing overall productivity of the species. Early juvenile scallops producted in February 2014 showed an average shell length of <TEX>$0.23{\pm}0.002$</TEX>. The high growth group showed an average shell length and shell height of <TEX>$4.11{\pm}0.08mm$</TEX> and <TEX>$4.28{\pm}0.09mm$</TEX>, respectively, in June while they were <TEX>$23.63{\pm}3.4mm$</TEX> and <TEX>$24.19{\pm}4.5mm$</TEX> in October. The low growth group showed an average shell length and shell height of <TEX>$2.23{\pm}0.7mm$</TEX> and <TEX>$1.99{\pm}0.9mm$</TEX>, respectively, in June while they were <TEX>$1.99{\pm}0.9mm$</TEX> and <TEX>$17.59{\pm}4.5mm$</TEX> in October. The daily growth rate of the high growth group was 0.037 mm/day and 0.027 mm/day for the low growth group. In August, we measured the shell length of Patinopecten yessoensis from Yangyang-gun, Gangneung-si, Yeongdeok-gun, and Pohang-si. Patinopecten yessoensis from Pohang-si showed the best growth performance with its shell length of <TEX>$26.90{\pm}3.6mm$</TEX>. Patinopecten yessoensis from Yeongdeok was the second largest with its shell length of <TEX>$23.56{\pm}3.4mm$</TEX>. We presume that optimal water temperature and phytoplankton abundance of the two regions have contributed to the good growth performance of the species.

Predation of Sea Scallops and Other Indigenous Bivalves by Invasive Green Crab,Carcinus maenas, from Newfoundland, Canada

ABSTRACT Populations of green crab (Carcinus maenas) have expanded within Newfoundland, and this has raised concern from fish harvesters and scientists regarding bivalve predation in coastal areas on species such as juvenile sea scallops (Placopecten magellanicus). We used 2 microcosm experiments to determine (1) the effects of water temperature (5°C and 12°C) on scallop predation; (2) scallop size selection in small and large green crabs and a large indigenous predator, the rock crab (Cancer irroratus); and (3) bivalve prey selection in large green crabs between softshell clams (Mya arenaria), blue mussels (Mytilus edulis), and sea scallops. Overall, green and rock crabs captured 4 times more scallops in warm water (12°C) than cold (5°C). Large green (60–70 mm) and rock (75–90 mm) crabs captured similar numbers of scallops, selected medium-size (30–40 mm) scallops, and avoided small (10–20 mm) scallops. Small green crabs (40–50 mm) captured only small scallops. Large green crabs selected softshell clams ...

Bioaccumulation and oxidative damage in juvenile scallop Chlamys farreri exposed to benzo[a]pyrene, benzo[b]fluoranthene and chrysene

The study is aimed at investigating the bioaccumulation and oxidative damage of juvenile scallops (Chlamys farreri) exposed to three selected PAHs: benzo[a]pyrene (BaP), benzo[b]fluoranthene (BbF) and chrysene (CHR). For this purpose, a study was performed on juvenile scallops exposed to BaP (0.01, 0.2 and 4μg/L), BbF (0.02, 0.2 and 2μg/L) and CHR (0.2, 0.8 and 3.2μg/L) for 21 days. Accumulations of these three PAHs in soft parts of scallops, except the 0.01μg/L BaP group and the 0.02μg/L BbF group, showed obvious time and dose dependence, and CHR accumulation was higher when compared to BaP and BbF. Oxidative damage indicators, including lipid peroxidation (LPO), protein carbonyl (PC) and DNA strand breaks, were also measured in soft parts to assess effects of the selected PAHs. The results showed that the LPO levels, PC contents and DNA damage were induced significantly (P<0.05 or P<0.01), except in the low level groups of BaP and BbF, and different trends were detected with time of exposure. According to the correlation analysis results, PC content in soft parts showed a good correlation with the target contaminant and seemed to be proposed as a potential early indicator of BaP, BbF and CHR. In addition the sequence of toxicity is BaP>BbF>CHR, judging by the level of induction of oxidative damage at 0.2μg/L levels. The results of this research are expected to contribute to the establishment of a good biochemical index of exposure to PAHs in laboratory experiments, which can be further useful in field studies.