Effects Of Predator Size Research Articles

Evaluating the Impact of Mesopredators on Oyster Restoration in the New York Metropolitan Region

ABSTRACT Predation of newly settled juvenile Crassostrea virginica often dominates post-settlement mortality. Resident mesopredators such as the xanthid mud crabs are abundant (>200/m2) on constructed subtidal oyster reefs in the New York metropolitan region and may contribute to post-settlement oyster mortality. Two study sites with differing mesopredator species, Hastings and Soundview Park, were selected to examine the role of small crustacean predators in post-settlement mortality. The white-fingered mud crab (Rhithropanopeus harrisii) inhabits Hastings, whereas the flat mud crab (Eurypanopeus depressus) and Sayi mud crab (Dyspanopeus sayi) inhabit Soundview Park. Using size-selective mesh cages to exclude predators, the effects of predator size on oyster predation and recruitment at Hastings and Soundview Park were examined. Overall, Soundview Park had higher consumption rates than Hastings. The highest consumption at Soundview Park occurred when predators of all sizes had access to the oyster prey. ...

Predation by fish on assemblages of intertidal epibiota: effects of predator size and patch size

We tested the hypothesis that effects of predation by fish on epibiota are independent of the size of fish and the area foraged. We used cages with different sizes of mesh to exclude fish of different sizes. Sizes of mesh were chosen following observations that there were small (<200 mm TL) and large (>200 mm TL) predatory fish at the study site. Predation by fish was intense on oysters and directly or indirectly reduced the density of the gastropod, Bembicium auratum. The cover of algae was positively affected by predation, possibly because predation on oysters created more space for algae. Predation by small fish (toadfish) was intense, but the effects of large fish were negligible. Predation was, however, independent of the sizes of experimental panels (i.e. area foraged) over the range examined (5×5, 10×10, 20×20 cm). Our results highlight the importance of doing experiments to test hypotheses derived from known aspects of the biology of the predators and prey being studied.

Foraging Behaviour Patterns of Four Sympatric Demersal Fishes

The trophic relationships of four sympatric demersal fish species ( Mullus barbatus , Mullus surmuletus , Pagrus pagrus and Gobius niger ) which dominate the shallow coastal areas (25–30 m) of Iraklion Bay (S Aegean, NE Mediterranean) were investigated from samples collected on a monthly basis (August 1990–August 1992). Stomach content analysis revealed that all four species were carnivorous, feeding mainly on benthic invertebrates. Although these species displayed different feeding modes based on principal prey type utilization, they all consumed a considerable number of polychaetes. In order to understand any underlying patterns of predation on polychaetes, prey items were identified to the lowest possible taxonomic level. The polychaete species were further classified into groups according to their microhabitat (surface or burrowing) and feeding (feeding mode, motility and morphology) guilds. Comparisons of the feeding habits were made using the percentage contribution by number of each prey species in the diet of the predators. Similarities in the diets between the fish species were calculated and cluster analysis was used to describe interspecific variations in food selection, concerning polychaetes. The predatory preferences of each fish species were related to the microhabitat distribution of prey species in the sediment. The differential exploitation of polychaete species was a good indicator of disparate foraging behaviour among the fish species examined, since it reflects a transition from a non-selective to a specialized feeding method. The effects of predator size and morphology of feeding apparatus and the availability of polychaete species in the environment are also discussed to explain the differential exploitation of polychaetes exhibited by the fish.

The effects of predator size, temperature, and prey characteristics on gastric evacuation in whiting

The effects of predator size, temperature, and prey characteristics on gastric evacuation in whiting

The effects of predator size, temperature, and prey characteristics on gastric evacuation in whiting

No effect of prey size on gastric evacuation rate was found in whiting Merlangius merlangus.Prey energy density explained most of the data variation among fish prey, and evacuation time increased by a factor 1·6–1·7 with prey energy density increasing from 3·4 to 5·6 kJ g−1. The power model expanded to include predator size, temperature, and prey energy density could describe gastric evacuation in whiting fed fish prey. Krill Meganyctiphanes norvegica was evacuated at a rate similar to fish prey of equal energy density, while the evacuation of brown shrimp Crangon crangon took almost twice as long.

Selective piscivory by perch: Effects of predator size, prey size, and prey species

Selective piscivory by perch: Effects of predator size, prey size, and prey species