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John H. Himmelman - One of the best experts on this subject based on the ideXlab platform.
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Effect of different predators on the escape response of Placopecten magellanicus
Marine Biology, 2015Co-Authors: Helga Guderley, Isabelle Tremblay, John H. Himmelman, Madeleine Nadeau, Hernan Pérez Cortes, Xavier JanssooneAbstract: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, Québec, 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.
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Swimming away or clamming up: the use of phasic and tonic adductor muscles during escape responses varies with shell morphology in scallops
Journal of Experimental Biology, 2012Co-Authors: Isabelle Tremblay, Helga Guderley, John H. HimmelmanAbstract:SUMMARY The simple locomotor system of scallops facilitates the study of muscle use during locomotion. We compared five species of scallops with different shell morphologies to see whether shell morphology and muscle use change in parallel or whether muscle use can compensate for morphological constraints. Force recordings during escape responses revealed that the use of tonic and phasic contractions varied markedly among species. The active species, Amusium balloti , Placopecten magellanicus and Pecten fumatus , made more phasic contractions than the more sedentary species, Mimachlamys asperrima and Crassadoma gigantea . Tonic contractions varied considerably among these species, with the two more sedentary species often starting their response to the predator with a tonic contraction and the more active species using shorter tonic contractions between series of phasic contractions. Placopecten magellanicus made extensive use of short tonic contractions. Pecten fumatus mounted an intense series of phasic contractions at the start of its response, perhaps to overcome the constraints of its unfavourable shell morphology. Valve closure by the more sedentary species suggests that their shell morphology protects them against predation, whereas swimming by the more active species relies upon intense phasic contractions together with favourable shell characteristics.
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RESEARCH ARTICLE Swimming away or clamming up: the use of phasic and tonic adductor muscles during escape responses varies with shell morphology in scallops
2012Co-Authors: Isabelle Tremblay, Helga Guderley, John H. HimmelmanAbstract:SUMMARY The simple locomotor system of scallops facilitates the study of muscle use during locomotion. We compared five species of scallops with different shell morphologies to see whether shell morphology and muscle use change in parallel or whether muscle use can compensate for morphological constraints. Force recordings during escape responses revealed that the use of tonic and phasic contractions varied markedly among species. The active species, Amusium balloti, Placopecten magellanicus and Pecten fumatus, made more phasic contractions than the more sedentary species, Mimachlamys asperrima and Crassadoma gigantea. Tonic contractions varied considerably among these species, with the two more sedentary species often starting their response to the predator with a tonic contraction and the more active species using shorter tonic contractions between series of phasic contractions. Placopecten magellanicus made extensive use of short tonic contractions. Pecten fumatus mounted an intense series of phasic contractions at the start of its response, perhaps to overcome the constraints of its unfavourable shell morphology. Valve closure by the more sedentary species suggests that their shell morphology protects them against predation, whereas swimming by the more active species relies upon intense phasic contractions together with favourable shell characteristics.
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Experimental examination of movement of the giant scallop, Placopecten magellanicus
Marine Biology, 1996Co-Authors: Kevin D. E. Stokesbury, John H. HimmelmanAbstract:We quantified movements of tagged giant scallops, Placopecten magellanicus (Gmelin, 1791), (40 to 115 mm in shell height) released in 1991 and 1992 at nine stations in Port Daniel Bay, Baie des Chaleurs, Gulf of St. Lawrence, Canada, for periods of 10 to 52 d. Both the mean distances moved per day and dispersion distances from release points were usually greater at the two stations with sand substratum, low scallop densities and high rock crab, Cancer irroratus, densities. Movement rate and dispersion of scallops from the release points at the other seven stations were similar, even though there were marked differences in substratum type (gravel, cobble or bedrock), predator density, and scallop density. Most mean dispersal directions were random, and scallops did not appear to migrate from unsuitable to suitable habitats. Although movement did reduce predation rate, scallop movement was weakly correlated with the abundance of only one predator, C. irroratus.
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Biological and physical variables associated with aggregations of the giant scallop Placopecten magellanicus
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Kevin D. E. Stokesbury, John H. HimmelmanAbstract:To identify factors that may determine where aggregations (beds) of giant scallops (Placopecten magellanicus) develop, we compared physical and biological conditions in two scallop beds in Port Daniel Bay, Baie des Chaleurs, Gulf of St. Lawrence, with conditions in seven adjacent areas. Gravel substratum predominantly characterized scallop beds. Physical hydrographic conditions and the intensity of asteroid predation were similar within scallop beds and in surrounding areas with few scallops. High P. magellanicus spat settlement density was not consistently correlated with existing scallop aggregations, but filamentous organisms, on which scallops preferentially settle, were more abundant in scallop beds, possibly enhancing recruitment. Scallop growth rate varied among areas and was intermediate within scallop beds. Winter flounder (Pseudopleuronectes americanus) and Atlantic wolffish (Anarhichas lupus) preyed on P. magellanicus and may influence scallop distribution. Scallop tethering experiments indicat...
Conrad A. Pilditch - One of the best experts on this subject based on the ideXlab platform.
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Seston supply to sea scallops (Placopecten magellanicus) in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (
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seston supply to sea scallops Placopecten magellanicus in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (<5%) within the lease (80 × 50 m), consistent with field observations. However, expanding the lease to occupy the area available for cu...
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Effect of temperature fluctuations and food supply on the growth and metabolism of juvenile sea scallops (Placopecten magellanicus)
Marine Biology, 1999Co-Authors: Conrad A. Pilditch, Jonathan GrantAbstract:On the eastern shore of Nova Scotia late summer atmospheric systems cause upwelling of shelf water; the associated temperature variations of 10 °C with a 6 to 8 d period are comparable in magnitude to the seasonal variation. A laboratory study was undertaken to assess the effects of these temperature fluctuations on sea scallop (Placopecten magellanicus) growth and metabolism. In a factorial design, scallops were subjected to constant (10 °C) or a variable (6 to 15 °C) 8 d temperature cycle, and either a low (seston in filtered seawater) or high (seston supplemented with cultured phytoplankton) food diet. During the 48 d experiment scallop mortality was low and growth positive in all treatments. Shell and total tissue growth rate did not differ between temperature treatments, but growth in the high food treatments was 40 to 50% higher than in the low food treatments. However, soft tissue (excluding adductor) growth did show a temperature treatment effect; growth rates were significantly higher in the fluctuating temperature treatment, due in part to greater gonad development. Weight-standardized rates of scallop oxygen consumption (V sO2 , μmol O2 g−1 h−1) were 20 to 25% higher in high food than in low food treatments, consistent with the expected increase in respiration due to the higher growth rates. Scallop metabolism did not acclimate to the fluctuating temperature cycle; V sO2 and ammonium excretion (V sNH+ 4, μmol O2 g−1 h−1) remained dependent on ambient temperature throughout the experiment. V sNH+ 4 Q10 (2.77) was higher than V sO2 Q10 (2.01) which was reflected in a decrease in the O:N ratio at 15 °C, indicating a shift toward increased protein catabolism and a stressed state. At 10 °C, V sO2 and V sNH+ 4 in the variable temperature treatments were 15 to 18% lower than in the constant temperature treatments, a difference that was not detected in growth measurements. Results demonstrate that the metabolism of Placopecten magellanicus, unlike some bivalve species, is tightly coupled to fluctuations in ambient temperature. Although an absence of compensatory acclimation had a minimal effect on growth in this study, if high temperatures were combined with low food conditions a reduction in scallop production could result.
Jonathan Grant - One of the best experts on this subject based on the ideXlab platform.
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seston supply to sea scallops Placopecten magellanicus in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (<5%) within the lease (80 × 50 m), consistent with field observations. However, expanding the lease to occupy the area available for cu...
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Seston supply to sea scallops (Placopecten magellanicus) in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (
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Effect of temperature fluctuations and food supply on the growth and metabolism of juvenile sea scallops (Placopecten magellanicus)
Marine Biology, 1999Co-Authors: Conrad A. Pilditch, Jonathan GrantAbstract:On the eastern shore of Nova Scotia late summer atmospheric systems cause upwelling of shelf water; the associated temperature variations of 10 °C with a 6 to 8 d period are comparable in magnitude to the seasonal variation. A laboratory study was undertaken to assess the effects of these temperature fluctuations on sea scallop (Placopecten magellanicus) growth and metabolism. In a factorial design, scallops were subjected to constant (10 °C) or a variable (6 to 15 °C) 8 d temperature cycle, and either a low (seston in filtered seawater) or high (seston supplemented with cultured phytoplankton) food diet. During the 48 d experiment scallop mortality was low and growth positive in all treatments. Shell and total tissue growth rate did not differ between temperature treatments, but growth in the high food treatments was 40 to 50% higher than in the low food treatments. However, soft tissue (excluding adductor) growth did show a temperature treatment effect; growth rates were significantly higher in the fluctuating temperature treatment, due in part to greater gonad development. Weight-standardized rates of scallop oxygen consumption (V sO2 , μmol O2 g−1 h−1) were 20 to 25% higher in high food than in low food treatments, consistent with the expected increase in respiration due to the higher growth rates. Scallop metabolism did not acclimate to the fluctuating temperature cycle; V sO2 and ammonium excretion (V sNH+ 4, μmol O2 g−1 h−1) remained dependent on ambient temperature throughout the experiment. V sNH+ 4 Q10 (2.77) was higher than V sO2 Q10 (2.01) which was reflected in a decrease in the O:N ratio at 15 °C, indicating a shift toward increased protein catabolism and a stressed state. At 10 °C, V sO2 and V sNH+ 4 in the variable temperature treatments were 15 to 18% lower than in the constant temperature treatments, a difference that was not detected in growth measurements. Results demonstrate that the metabolism of Placopecten magellanicus, unlike some bivalve species, is tightly coupled to fluctuations in ambient temperature. Although an absence of compensatory acclimation had a minimal effect on growth in this study, if high temperatures were combined with low food conditions a reduction in scallop production could result.
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Carbon and Nitrogen Scope for Growth as A Function of Diet in the Sea Scallop Placopecten Magellanicus
Journal of the Marine Biological Association of the United Kingdom, 1991Co-Authors: Jonathan Grant, Peter J. CranfordAbstract:Laboratory feeding experiments with the sea scallop Placopecten magellanicus were carried out to compare scope for growth (SFG) to measured growth and determine the effect of diet on carbon and nitrogen SFG. Diets consisting of cultured phytoplankton, kelp detritus, and resuspended sediment were provided daily for 52 days (October-December). Measurements of clearance rate, absorption efficiency, respiration, O/N ratio, and carbon and nitrogen content of diets and scallop tissue were used to construct carbon and nitrogenbudgets for each diet. Growth coefficients were calculated from change in tissue weight during the study period.
Karin R. Bryan - One of the best experts on this subject based on the ideXlab platform.
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Seston supply to sea scallops (Placopecten magellanicus) in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (
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seston supply to sea scallops Placopecten magellanicus in suspended culture
Canadian Journal of Fisheries and Aquatic Sciences, 2001Co-Authors: Conrad A. Pilditch, Jonathan Grant, Karin R. BryanAbstract:The filtration activity of dense aggregations of bivalves can locally reduce the concentration of seston, potentially limiting production. Under these conditions, the currents that supply seston cannot offset ingestion by the bivalves and the carrying capacity is exceeded. We conducted a field and modelling study to examine factors affecting seston supply to a culture of suspended sea scallops (Placopecten magellanicus) in Whitehaven Harbour, Nova Scotia. Even though seston flux to the scallops was reduced by 40% due to the attenuation of flow by culture gear, a reduction in seston concentration was not observed. The field data were then used to parameterize a quasi two-dimensional advection-diffusion model that quantified the relationship between the tidally driven seston supply and consumption by scallops. The model predicted a minimal reduction in seston concentration (<5%) within the lease (80 × 50 m), consistent with field observations. However, expanding the lease to occupy the area available for cu...
Helga Guderley - One of the best experts on this subject based on the ideXlab platform.
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Effect of different predators on the escape response of Placopecten magellanicus
Marine Biology, 2015Co-Authors: Helga Guderley, Isabelle Tremblay, John H. Himmelman, Madeleine Nadeau, Hernan Pérez Cortes, Xavier JanssooneAbstract: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, Québec, 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.
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Scallops Show That Muscle Metabolic Capacities Reflect Locomotor Style and Morphology
Physiological and Biochemical Zoology, 2013Co-Authors: Isabelle Tremblay, Helga GuderleyAbstract:AbstractAlthough all scallops swim using their adductor muscle to close their valves, scallop species differ considerably in how they use their muscle during escape responses, in parallel with the striking interspecific differences in shell morphology. This provides an excellent opportunity to study links between muscle metabolic capacities and animal performance. We found that the capacity for anaerobic glycolysis and aerobic metabolism, as well as phosphoarginine levels in the phasic adductor muscle, differ with escape response strategy. Phosphoarginine contents were high in species that rely on phasic contractions (Amusium balloti, Placopecten magellanicus, and Pecten fumatus). Arginine kinase activities reflect reliance on rapid initial bursts of phasic contractions. Scallops that maintain their valves in a closed position for prolonged periods (P. fumatus, Mimachlamys asperrima, and Crassadoma gigantea) have high activities of enzymes of anaerobic glycolysis in their phasic adductor muscle. Myosin AT...
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Swimming away or clamming up: the use of phasic and tonic adductor muscles during escape responses varies with shell morphology in scallops
Journal of Experimental Biology, 2012Co-Authors: Isabelle Tremblay, Helga Guderley, John H. HimmelmanAbstract:SUMMARY The simple locomotor system of scallops facilitates the study of muscle use during locomotion. We compared five species of scallops with different shell morphologies to see whether shell morphology and muscle use change in parallel or whether muscle use can compensate for morphological constraints. Force recordings during escape responses revealed that the use of tonic and phasic contractions varied markedly among species. The active species, Amusium balloti , Placopecten magellanicus and Pecten fumatus , made more phasic contractions than the more sedentary species, Mimachlamys asperrima and Crassadoma gigantea . Tonic contractions varied considerably among these species, with the two more sedentary species often starting their response to the predator with a tonic contraction and the more active species using shorter tonic contractions between series of phasic contractions. Placopecten magellanicus made extensive use of short tonic contractions. Pecten fumatus mounted an intense series of phasic contractions at the start of its response, perhaps to overcome the constraints of its unfavourable shell morphology. Valve closure by the more sedentary species suggests that their shell morphology protects them against predation, whereas swimming by the more active species relies upon intense phasic contractions together with favourable shell characteristics.
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RESEARCH ARTICLE Swimming away or clamming up: the use of phasic and tonic adductor muscles during escape responses varies with shell morphology in scallops
2012Co-Authors: Isabelle Tremblay, Helga Guderley, John H. HimmelmanAbstract:SUMMARY The simple locomotor system of scallops facilitates the study of muscle use during locomotion. We compared five species of scallops with different shell morphologies to see whether shell morphology and muscle use change in parallel or whether muscle use can compensate for morphological constraints. Force recordings during escape responses revealed that the use of tonic and phasic contractions varied markedly among species. The active species, Amusium balloti, Placopecten magellanicus and Pecten fumatus, made more phasic contractions than the more sedentary species, Mimachlamys asperrima and Crassadoma gigantea. Tonic contractions varied considerably among these species, with the two more sedentary species often starting their response to the predator with a tonic contraction and the more active species using shorter tonic contractions between series of phasic contractions. Placopecten magellanicus made extensive use of short tonic contractions. Pecten fumatus mounted an intense series of phasic contractions at the start of its response, perhaps to overcome the constraints of its unfavourable shell morphology. Valve closure by the more sedentary species suggests that their shell morphology protects them against predation, whereas swimming by the more active species relies upon intense phasic contractions together with favourable shell characteristics.
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Allozyme heterozygosity and escape response performance of the scallops, Argopecten purpuratus and Placopecten magellanicus
Marine Biology, 2011Co-Authors: Hernán Mauricio Pérez, Katherina Brokordt, Rejean Tremblay, Helga GuderleyAbstract:Multilocus allozyme heterozygosity (MLH) has been positively correlated with growth in some marine bivalves and was suggested to facilitate swimming activity in pectinids. Using two highly mobile scallops, Placopecten magellanicus and Argopecten purpuratus, we examined escape response performance and morphometric characteristics as a function of allelic variability at metabolic loci. Ten allozyme systems were used for A. purpuratus and 7 for P. magellanicus. In each species, the morphometric characteristics and escape response parameters were analyzed separately using principal components analysis (PCA) and the scores of the major principal components were related to allozyme heterozygosity. In both P. magellanicus and A. purpuratus, positive correlations were found between MLH and morphometric parameters, but escape response parameters were only positively linked to MLH in P. magellanicus, and then weakly. The hypothesis that MLH improves fitness of pectinids by increasing the capacity to escape predators is not supported.
