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Myriam A Barbeau - One of the best experts on this subject based on the ideXlab platform.
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sediment selection by juvenile sea scallops placopecten magellanicus gmelin sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say
Journal of Shellfish Research, 2006Co-Authors: Melisa C Wong, Lisa D Wright, Myriam A BarbeauAbstract:Abstract We examined sediment selection by juvenile sea scallops (Placopecten magellanicus) and their predators, sea stars (Asterias vulgaris) and rock crabs (Cancer Irroratus). In laboratory trials, groups of scallops (~30 mm shell height) were simultaneously offered four sediment types in the presence and absence of a sea star or a rock crab: (1) glass representing a homogeneous, hard bottom; (2) sand; (3) granule and (4) pebble. As well, individual predators were offered the four sediment types without scallops. The number of scallops and the proportion of time predators spent on each sediment type were monitored over time. When compared with the expected distribution, scallops avoided glass and tended to select granule and pebble sediments when alone. In the presence of a rock crab, scallops also avoided glass. However, scallop distribution was similar to the expected distribution when a sea star was present, because sea star encounters are an important trigger of scallop swimming, leading to frequent...
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protective refuges for seeded juvenile scallops placopecten magellanicus from sea star asterias spp and crab Cancer Irroratus and carcinus maenas predation
Canadian Journal of Fisheries and Aquatic Sciences, 2005Co-Authors: Melisa C Wong, Myriam A Barbeau, Allan W Hennigar, Shawn M C RobinsonAbstract:We examined two methods to provide refuge for seeded juvenile sea scallops (Placopecten magellanicus) from sea star (Asterias spp.) and crab (Cancer Irroratus and Carcinus maenas) predation by cons...
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temperature effects on predation of juvenile sea scallops placopecten magellanicus gmelin by sea stars asterias vulgaris verrill and crabs Cancer Irroratus say
Journal of Experimental Marine Biology and Ecology, 1994Co-Authors: Myriam A Barbeau, Robert Eric ScheiblingAbstract:Abstract Predation of juvenile sea scallops Placopecten magellanicus by sea stars Asterias vulgaris (80–100 mm diameter) and crabs Cancer Irroratus (80–98 mm carapace width) was examined in the laboratory at different seawater temperatures. Prey sizes used were those demonstrated previously to be preferentially consumed by the respective predators. Consumption rate of small (5–9 mm shell height, SH) scallops by sea stars was not significantly different at 4° and 8 °C, but was significantly higher at 15 ° C ( Q 10 = 6.9). Similarly, consumption rate of large (19–23 mm SH) scallops by crabs was not significantly different at 3 ° and 8 ° C, but was significantly higher at 15 ° C ( Q 10 = 2.1). Increased predator activity, as indicated by increased time spent searching for prey, increased predator searching movement velocities (which, for sea stars, resulted in increased encounter rates with scallops), and shorter prey handling times, explained part of the increased predation rate by sea stars and most of that by crabs. Predation rate by sea stars also increased with temperature because of decreased effectiveness of the scallops' escape response, as evidenced by a significantly higher probability of capture upon encounter at 15 °C than at 4° and 8 ° C, although the probability of sea stars capturing scallops was very low ( 0.3) and independent of temperature. The probability of sea stars and crabs consuming captured scallops was ~ 1 and temperature independent.
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behavioral mechanisms of prey size selection by sea stars asterias vulgaris verrill and crabs Cancer Irroratus say preying on juvenile sea scallops placopecten magellanicus gmelin
Journal of Experimental Marine Biology and Ecology, 1994Co-Authors: Myriam A Barbeau, Robert Eric ScheiblingAbstract:Abstract Predation upon different size classes of juvenile sea scallops Placopecten magellanicus (Gmelin) (5–25 mm shell height) by different size classes of predatory sea stars Asterias vulgaris Verill (30–150 mm diameter) and crabs Cancer Irroratus Say (45–120 mm carapace width) was studied in laboratory experiments using single prey size (no choice) and multiple prey size (choice) designs. Components of predation rate were quantified to assess the relative importance of prey vulnerability and active predator choice in determining observed prey selection. All sizes of sea stars consumed more small scallops than medium or large ones. Encounter rates between predator and prey were similar, irrespective of sea star and scallop size, and did not differ from encounter rates calculated on the basis of body sizes and movement velocities. Scallops assumed a ready-to-swim position when contacted by sea stars, and often actively escaped. The probability of capture by sea stars upon encounter was generally low ( 0.2) than that observed with sea stars. Therefore, prey size selection by crabs appears to be determined by both size-related differences in prey vulnerability, due to differential encounter rates, and active selection of larger prey.
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predator prey interactions between juvenile sea scallops placopecten magellanicus and predatory sea stars asterias spp and crabs Cancer Irroratus
1994Co-Authors: Myriam A BarbeauAbstract:This study examines the effects of biological and physical factors on predation of juvenile sea scallops (Placopecten magellanicus; 5-28 mm shell height) by two major predators, sea stars (Asterias spp.) and crabs (Cancer Irroratus). Predator-prey size laboratory experiments with sea stars (30-150 mm diameter) showed that predation rates increased with increasing sea star size and decreasing scallop size. Preference for small scallops by sea stars was determined by prey vulnerability resulting from differential probabilities of capture upon encounter, even though the probability of capture was $$0.20, since scallops often closed their valves upon encounter with crabs. In laboratory experiments, predation rates on preferred prey sizes increased with water temperature (3-15$\sp\circ$C) with Q$\sb $ values of 6.9 and 2.1 for sea stars and crabs, respectively. The increase in predation rate with temperature was attributable to increased foraging activity of sea stars and crabs, and decreased escape effectiveness of scallops with sea stars. In a field experiment manipulating scallop density, crab predation rate increased with scallop density, but crab density did not, indicating a functional response. Sea star predation rate on scallops was not affected by scallop density. In a series of experiments with different size classes of scallops tethered at different sites and water temperatures (seasons), and in different densities of predators and free-living scallops, the effects of covariates on scallop survival times were assessed using the statistical procedure of survival analysis. Since the tethering technique affected crab and sea star predation differently, the competing causes of scallop mortality were analysed separately. Water temperature, site, and scallop density were the important variables affecting crab predation. There was a significant interaction between temperature and site, such that crab predation on scallops increased with temperature at one site and was independent of temperature at the other site. Predation by crabs also increased with scallop density and, to a lesser extent, with crab density. Water temperature and scallop size were the primary variables affecting sea star predation. Sea star predation on scallops increased with temperature and decreased with scallop size. The results of this study further our understanding of predator-prey interactions in the marine benthic environment as well as suggest options for minimizing predation of scallops by crabs and sea stars in bottom culture operations.
Melisa C Wong - One of the best experts on this subject based on the ideXlab platform.
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sediment selection by juvenile sea scallops placopecten magellanicus gmelin sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say
Journal of Shellfish Research, 2006Co-Authors: Melisa C Wong, Lisa D Wright, Myriam A BarbeauAbstract:Abstract We examined sediment selection by juvenile sea scallops (Placopecten magellanicus) and their predators, sea stars (Asterias vulgaris) and rock crabs (Cancer Irroratus). In laboratory trials, groups of scallops (~30 mm shell height) were simultaneously offered four sediment types in the presence and absence of a sea star or a rock crab: (1) glass representing a homogeneous, hard bottom; (2) sand; (3) granule and (4) pebble. As well, individual predators were offered the four sediment types without scallops. The number of scallops and the proportion of time predators spent on each sediment type were monitored over time. When compared with the expected distribution, scallops avoided glass and tended to select granule and pebble sediments when alone. In the presence of a rock crab, scallops also avoided glass. However, scallop distribution was similar to the expected distribution when a sea star was present, because sea star encounters are an important trigger of scallop swimming, leading to frequent...
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prey selection and the functional response of sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say preying on juvenile sea scallops placopecten magellanicus gmelin and blue mussels mytilus edulis linnaeus
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Melisa C Wong, Myriam A BarbeauAbstract:Abstract Predators in nature include an array of prey types in their diet, and often select certain types over others. We examined (i) prey selection by sea stars ( Asterias vulgaris ) and rock crabs ( Cancer Irroratus ) when offered two prey types, juvenile sea scallops ( Placopecten magellanicus ) and blue mussels ( Mytilus edulis ), and (ii) the effect of prey density on predation, prey selection, and component behaviours. We quantified predation rates, behavioural components (proportion of time spent searching for prey, encounter probabilities) and various prey characteristics (shell strength, energy content per prey, handling time per prey) to identify mechanisms underlying predation patterns and to assess the contribution of active and passive prey selection to observed selection of prey. Sea stars strongly selected mussels over scallops, resulting from both active and passive selection. Active selection was associated with the probability of attack upon encounter; it was higher on mussels than on scallops. The probability of capture upon attack, associated with passive selection, was higher for mussels than for scallops, since mussels can not swim to escape predators. Sea stars consumed few scallops when mussels were present, and so did not have a functional response on scallops (the target prey). Rock crabs exhibited prey switching: they selected mussels when scallop density was very low, did not select a certain prey type when scallop density was intermediate, and selected scallops when scallop density was high relative to mussel density. The interplay between encounter rate (associated with passive selection) and probability of consumption upon capture (associated with both active and passive selection) explained observed selection by crabs. Scallops were encountered by crabs relatively more often and/or mussels less often than expected from random movements of animals at all scallop densities. However, the probability of consumption varied with scallop density: it was lower for scallops than mussels at low and intermediate scallop densities, but tended to be higher for scallops than mussels at high scallop densities. When mussels were absent, crabs did not have a functional response on scallops, but rather were at the plateau of the response. When mussels were present with scallops at relatively low density, crabs exhibited a type II functional response on scallops. Our results have implications for the provision of protective refuges for species of interest (i.e., scallops) released onto the sea bed, such as in population enhancement operations and bottom aquaculture.
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protective refuges for seeded juvenile scallops placopecten magellanicus from sea star asterias spp and crab Cancer Irroratus and carcinus maenas predation
Canadian Journal of Fisheries and Aquatic Sciences, 2005Co-Authors: Melisa C Wong, Myriam A Barbeau, Allan W Hennigar, Shawn M C RobinsonAbstract:We examined two methods to provide refuge for seeded juvenile sea scallops (Placopecten magellanicus) from sea star (Asterias spp.) and crab (Cancer Irroratus and Carcinus maenas) predation by cons...
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effects of substrate on interactions between juvenile sea scallops placopecten magellanicus gmelin and predatory sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say
Journal of Experimental Marine Biology and Ecology, 2003Co-Authors: Melisa C Wong, Myriam A BarbeauAbstract:Abstract We investigated the effect of substrate (glass bottom, sand, granule, pebble) on predation of juvenile sea scallops ( Placopecten magellanicus ) by sea stars ( Asterias vulgaris ) and rock crabs ( Cancer Irroratus ) at two prey sizes (11–15 mm and 24–28 mm shell height), and two prey densities (10 and 30 scallops per aquarium) in laboratory experiments. Specifically, we quantified predation rate and underlying behaviours (proportion of time a predator spent searching for and handling prey, encounter rate between predators and prey, and various outcomes of encounters). We detected a significant gradual effect of particle size of natural substrates on sea star predation: specifically, predation rate on and encounter rate with small scallops tended to decrease with increasing particle size (being highest for sand, intermediate for granule, and lowest for pebble). Substrate type did not significantly affect predation rates or behaviours of sea stars preying on large scallops or of rock crabs preying on either scallop size classes. Other factors, such as prey size and density, were important in the scallop-sea star and scallop-rock crab systems. For example, predation rate by sea stars and crabs and certain sea star behaviours (e.g. probability of consuming scallops upon capture) were significantly higher with small scallops than with large scallops. As well, in interactions between small scallops and sea stars, predation rate and encounter rate increased with prey density, and the proportion of time sea stars spent searching was higher at low prey density than high prey density. Thus, substrate type may be a minor factor determining predation risk of seeded scallops during enhancement operations; prey size and prey density may play a more important role. However, substrate type still needs to be considered when choosing a site for scallop enhancement, as it may affect other scallop behaviours (such as movement).
Myriam A Barbeau - One of the best experts on this subject based on the ideXlab platform.
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behavioural mechanisms of sea stars asterias vulgaris verrill and leptasterias polaris muller and crabs Cancer Irroratus say and hyas araneus linnaeus preying on juvenile sea scallops placopecten magellanicus gmelin and procedural effects of scallop
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Madeleine Nadeau, Myriam A Barbeau, Jeanclaude BrethesAbstract:Abstract We compared predation rates and behaviours of sea stars ( Asterias vulgaris and Leptasterias polaris ) and crabs ( Cancer Irroratus and Hyas araneus ) preying on juvenile sea scallops ( Placopecten magellanicus , 25-35 mm shell height) in laboratory. These predatory species co-occur with sea scallops on the sea bed of the Gulf of St. Lawrence, Canada, and limit scallop survival in seeding operations. We also examined, under controlled conditions, the effect of tethering scallops on predator–prey interactions. Predation rates, time budgets and encounter behaviours observed for A. vulgaris and C. Irroratus preying on free (untethered) scallops were comparable to previous studies. C. Irroratus were more effective predators as they consumed 3.1 scallops predator − 1 day − 1 , although they spent only 0.9% of their time searching for prey. A. vulgaris consumed 0.9 scallops predator − 1 day − 1 and spent 7.6% of their time searching. Sea stars L. polaris had a lower predation rate (0.02 scallop predator − 1 day − 1 ) than A. vulgaris . The frequent avoidance behaviour of L. polaris and its low ability to capture scallops support the notion that scallops are not a main component of this sea star's diet. Crabs H. araneus had similar predation rates (1.3 scallops predator − 1 day − 1 ) and behaviours to C. Irroratus , although the probability of consumption upon capture was affected by relatively high numbers of rejections and post-capture escapes of scallops. As expected, the tethering procedure increased predation rate of L. polaris (about 19 times higher), but surprisingly did not significantly affect that of A. vulgaris . Examination of behaviours indicated that A. vulgaris offered tethered scallops tended to have a higher probability of capture, but spent less time searching for prey (possibly because satiation was reached) than A. vulgaris offered free scallops. Predation rates and behaviours of both crab species were not affected by tethering, since encounter rate was the primary determinant of crab-scallop interactions. Identification and quantification of behaviours underlying the predation process allowed us to mathematically model predator-related mortality for the four predator species.
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prey selection and the functional response of sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say preying on juvenile sea scallops placopecten magellanicus gmelin and blue mussels mytilus edulis linnaeus
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Melisa C Wong, Myriam A BarbeauAbstract:Abstract Predators in nature include an array of prey types in their diet, and often select certain types over others. We examined (i) prey selection by sea stars ( Asterias vulgaris ) and rock crabs ( Cancer Irroratus ) when offered two prey types, juvenile sea scallops ( Placopecten magellanicus ) and blue mussels ( Mytilus edulis ), and (ii) the effect of prey density on predation, prey selection, and component behaviours. We quantified predation rates, behavioural components (proportion of time spent searching for prey, encounter probabilities) and various prey characteristics (shell strength, energy content per prey, handling time per prey) to identify mechanisms underlying predation patterns and to assess the contribution of active and passive prey selection to observed selection of prey. Sea stars strongly selected mussels over scallops, resulting from both active and passive selection. Active selection was associated with the probability of attack upon encounter; it was higher on mussels than on scallops. The probability of capture upon attack, associated with passive selection, was higher for mussels than for scallops, since mussels can not swim to escape predators. Sea stars consumed few scallops when mussels were present, and so did not have a functional response on scallops (the target prey). Rock crabs exhibited prey switching: they selected mussels when scallop density was very low, did not select a certain prey type when scallop density was intermediate, and selected scallops when scallop density was high relative to mussel density. The interplay between encounter rate (associated with passive selection) and probability of consumption upon capture (associated with both active and passive selection) explained observed selection by crabs. Scallops were encountered by crabs relatively more often and/or mussels less often than expected from random movements of animals at all scallop densities. However, the probability of consumption varied with scallop density: it was lower for scallops than mussels at low and intermediate scallop densities, but tended to be higher for scallops than mussels at high scallop densities. When mussels were absent, crabs did not have a functional response on scallops, but rather were at the plateau of the response. When mussels were present with scallops at relatively low density, crabs exhibited a type II functional response on scallops. Our results have implications for the provision of protective refuges for species of interest (i.e., scallops) released onto the sea bed, such as in population enhancement operations and bottom aquaculture.
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effects of substrate on interactions between juvenile sea scallops placopecten magellanicus gmelin and predatory sea stars asterias vulgaris verrill and rock crabs Cancer Irroratus say
Journal of Experimental Marine Biology and Ecology, 2003Co-Authors: Melisa C Wong, Myriam A BarbeauAbstract:Abstract We investigated the effect of substrate (glass bottom, sand, granule, pebble) on predation of juvenile sea scallops ( Placopecten magellanicus ) by sea stars ( Asterias vulgaris ) and rock crabs ( Cancer Irroratus ) at two prey sizes (11–15 mm and 24–28 mm shell height), and two prey densities (10 and 30 scallops per aquarium) in laboratory experiments. Specifically, we quantified predation rate and underlying behaviours (proportion of time a predator spent searching for and handling prey, encounter rate between predators and prey, and various outcomes of encounters). We detected a significant gradual effect of particle size of natural substrates on sea star predation: specifically, predation rate on and encounter rate with small scallops tended to decrease with increasing particle size (being highest for sand, intermediate for granule, and lowest for pebble). Substrate type did not significantly affect predation rates or behaviours of sea stars preying on large scallops or of rock crabs preying on either scallop size classes. Other factors, such as prey size and density, were important in the scallop-sea star and scallop-rock crab systems. For example, predation rate by sea stars and crabs and certain sea star behaviours (e.g. probability of consuming scallops upon capture) were significantly higher with small scallops than with large scallops. As well, in interactions between small scallops and sea stars, predation rate and encounter rate increased with prey density, and the proportion of time sea stars spent searching was higher at low prey density than high prey density. Thus, substrate type may be a minor factor determining predation risk of seeded scallops during enhancement operations; prey size and prey density may play a more important role. However, substrate type still needs to be considered when choosing a site for scallop enhancement, as it may affect other scallop behaviours (such as movement).
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dynamics of juvenile sea scallop placopecten magellanicus and their predators in bottom seeding trials in lunenburg bay nova scotia
Canadian Journal of Fisheries and Aquatic Sciences, 1996Co-Authors: Myriam A Barbeau, Allan W Hennigar, Robert Eric Scheibling, Bruce G Hatcher, Lawrence H Taylor, A C RiskAbstract:Des milliers de juveniles du petoncle geant (Placopecten mugellanicus) ont ete lâches en deux endroits sur le fond de la mer (un secteur a la topographie ouverte, un autre a la topographie fermee) le long de la cote sud-ouest de la Nouvelle-Ecosse, Canada, a deux saisons, soit en ete et en hiver. Les petoncles indigenes et introduits ainsi que leurs predateurs (les etoiles de mer Asterias vulgaris et A. forbesi ainsi que le crabe Cancer Irroratus) ont fait l'objet d'une surveillance video et d'examens visuels par des plongeurs sur une periode de 17 mo. La densite des petoncles introduits a diminue rapidement apres les lâchers et s'est stabilisee au bout d'une a 8 sem; a la fin du projet, l'ecart de densite entre les stations etait plus grand que celui entre les saisons d'ensemencement. La temperature saisonniere influe sur la vitesse a laquelle la densite finale est atteinte. L'ensemencement a permis de doubler effectivement la densite des petoncles a chaque endroit. Le taux de survie a ete d'environ 10 % sur le site ouvert, a cause de la predation exercee par le crabe et de la dispersion des petoncles introduits, et d'environ 1 % sur l'autre site, principalement a cause de la predation par le crabe. Il n'existe pas de correlation entre les variations dans le temps de l'abondance et de la distribution spatiale des predateurs et celles du petoncle introduit; cela suggere que la mortalite par predation de ce dernier est attribuable a une reponse fonctionnelle plutot qu'a une reponse par agregation des predateurs. Le developpement des petoncles introduits etait sensiblement le meme aux deux endroits. La dynamique des populations de petoncles introduits refletait les interactions entre la predation, la dispersion et le developpement.
Shawn M C Robinson - One of the best experts on this subject based on the ideXlab platform.
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protective refuges for seeded juvenile scallops placopecten magellanicus from sea star asterias spp and crab Cancer Irroratus and carcinus maenas predation
Canadian Journal of Fisheries and Aquatic Sciences, 2005Co-Authors: Melisa C Wong, Myriam A Barbeau, Allan W Hennigar, Shawn M C RobinsonAbstract:We examined two methods to provide refuge for seeded juvenile sea scallops (Placopecten magellanicus) from sea star (Asterias spp.) and crab (Cancer Irroratus and Carcinus maenas) predation by cons...
Robert Eric Scheibling - One of the best experts on this subject based on the ideXlab platform.
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dynamics of juvenile sea scallop placopecten magellanicus and their predators in bottom seeding trials in lunenburg bay nova scotia
Canadian Journal of Fisheries and Aquatic Sciences, 1996Co-Authors: Myriam A Barbeau, Allan W Hennigar, Robert Eric Scheibling, Bruce G Hatcher, Lawrence H Taylor, A C RiskAbstract:Des milliers de juveniles du petoncle geant (Placopecten mugellanicus) ont ete lâches en deux endroits sur le fond de la mer (un secteur a la topographie ouverte, un autre a la topographie fermee) le long de la cote sud-ouest de la Nouvelle-Ecosse, Canada, a deux saisons, soit en ete et en hiver. Les petoncles indigenes et introduits ainsi que leurs predateurs (les etoiles de mer Asterias vulgaris et A. forbesi ainsi que le crabe Cancer Irroratus) ont fait l'objet d'une surveillance video et d'examens visuels par des plongeurs sur une periode de 17 mo. La densite des petoncles introduits a diminue rapidement apres les lâchers et s'est stabilisee au bout d'une a 8 sem; a la fin du projet, l'ecart de densite entre les stations etait plus grand que celui entre les saisons d'ensemencement. La temperature saisonniere influe sur la vitesse a laquelle la densite finale est atteinte. L'ensemencement a permis de doubler effectivement la densite des petoncles a chaque endroit. Le taux de survie a ete d'environ 10 % sur le site ouvert, a cause de la predation exercee par le crabe et de la dispersion des petoncles introduits, et d'environ 1 % sur l'autre site, principalement a cause de la predation par le crabe. Il n'existe pas de correlation entre les variations dans le temps de l'abondance et de la distribution spatiale des predateurs et celles du petoncle introduit; cela suggere que la mortalite par predation de ce dernier est attribuable a une reponse fonctionnelle plutot qu'a une reponse par agregation des predateurs. Le developpement des petoncles introduits etait sensiblement le meme aux deux endroits. La dynamique des populations de petoncles introduits refletait les interactions entre la predation, la dispersion et le developpement.
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temperature effects on predation of juvenile sea scallops placopecten magellanicus gmelin by sea stars asterias vulgaris verrill and crabs Cancer Irroratus say
Journal of Experimental Marine Biology and Ecology, 1994Co-Authors: Myriam A Barbeau, Robert Eric ScheiblingAbstract:Abstract Predation of juvenile sea scallops Placopecten magellanicus by sea stars Asterias vulgaris (80–100 mm diameter) and crabs Cancer Irroratus (80–98 mm carapace width) was examined in the laboratory at different seawater temperatures. Prey sizes used were those demonstrated previously to be preferentially consumed by the respective predators. Consumption rate of small (5–9 mm shell height, SH) scallops by sea stars was not significantly different at 4° and 8 °C, but was significantly higher at 15 ° C ( Q 10 = 6.9). Similarly, consumption rate of large (19–23 mm SH) scallops by crabs was not significantly different at 3 ° and 8 ° C, but was significantly higher at 15 ° C ( Q 10 = 2.1). Increased predator activity, as indicated by increased time spent searching for prey, increased predator searching movement velocities (which, for sea stars, resulted in increased encounter rates with scallops), and shorter prey handling times, explained part of the increased predation rate by sea stars and most of that by crabs. Predation rate by sea stars also increased with temperature because of decreased effectiveness of the scallops' escape response, as evidenced by a significantly higher probability of capture upon encounter at 15 °C than at 4° and 8 ° C, although the probability of sea stars capturing scallops was very low ( 0.3) and independent of temperature. The probability of sea stars and crabs consuming captured scallops was ~ 1 and temperature independent.
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behavioral mechanisms of prey size selection by sea stars asterias vulgaris verrill and crabs Cancer Irroratus say preying on juvenile sea scallops placopecten magellanicus gmelin
Journal of Experimental Marine Biology and Ecology, 1994Co-Authors: Myriam A Barbeau, Robert Eric ScheiblingAbstract:Abstract Predation upon different size classes of juvenile sea scallops Placopecten magellanicus (Gmelin) (5–25 mm shell height) by different size classes of predatory sea stars Asterias vulgaris Verill (30–150 mm diameter) and crabs Cancer Irroratus Say (45–120 mm carapace width) was studied in laboratory experiments using single prey size (no choice) and multiple prey size (choice) designs. Components of predation rate were quantified to assess the relative importance of prey vulnerability and active predator choice in determining observed prey selection. All sizes of sea stars consumed more small scallops than medium or large ones. Encounter rates between predator and prey were similar, irrespective of sea star and scallop size, and did not differ from encounter rates calculated on the basis of body sizes and movement velocities. Scallops assumed a ready-to-swim position when contacted by sea stars, and often actively escaped. The probability of capture by sea stars upon encounter was generally low ( 0.2) than that observed with sea stars. Therefore, prey size selection by crabs appears to be determined by both size-related differences in prey vulnerability, due to differential encounter rates, and active selection of larger prey.
