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Rocky Intertidal Food Web (rocky + intertidal_food_web)
Selected AbstractsField evidence of trait-mediated indirect interactions in a rocky intertidal food webECOLOGY LETTERS, Issue 2 2002Geoffrey C. Trussell Studies on the implications of food web interactions to community structure have often focused on density-mediated interactions between predators and their prey. This approach emphasizes the importance of predator regulation of prey density via consumption (i.e. lethal effects), which, in turn, leads to cascading effects on the prey's resources. A more recent and contrasting view emphasizes the importance of non-lethal predator effects on prey traits (e.g. behaviour, morphology), or trait-mediated interactions. On rocky intertidal shores in New England, green crab (Carcinus maenas) predation is thought to be important to patterns of algal abundance and diversity by regulating the density of herbivorous snails (Littorina littorea). We found, however, that risk cues from green crabs can dramatically suppress snail grazing, with large effects on fucoid algal communities. Our results suggest that predator-induced changes in prey behaviour may be an important and under-appreciated component of food web interactions and community dynamics on rocky intertidal shores. [source] Spatio-temporal variation of avian foraging in the rocky intertidal food webJOURNAL OF ANIMAL ECOLOGY, Issue 1 2001Masakazu Hori Abstract 1While birds are top predators in most rocky intertidal communities, the relationship between foraging pattern and variability in food web structure has not been studied. This study examined the spatio-temporal variation of both avian foraging and food web structure at an intertidal rocky shore in northern Japan over a 1-year period. 2Seventeen bird species foraged on the intertidal rocky shore. Crows and gulls were dominant, and their major prey was sea urchins that migrated from the sub-tidal to intertidal habitat. Interspecific interactions (i.e. stealing of food, utilization of food waste by other species) occurred between crows and gulls especially when feeding on sea urchins. The prey of the birds showed spatial and temporal partitioning. 3The number of prey items consumed per day by the dominant birds varied with various factors. Factors strongly affecting the foraging pattern of crows were waves, tides, humans and gulls, and those strongly affecting the foraging pattern of gulls were tides, humans, sea urchins and crows. 4In the rocky intertidal food web, most of the top predators were birds, and most of the birds were omnivores. The birds consumed many more species than did other consumers. Food-resource partitioning caused spatio-temporal compartmentation among subwebs in which the top predators were dominant birds. 5Analysis of food web statistics (i.e. web size, numbers of links, linkage density, chain lengths) revealed that the presence/absence of birds did not change the relationships between web size and the other statistics. The food web statistics depended on web size, and the web size was positively related with time spent emersed and temperature when birds were both present and not present. 6Birds often foraged across habitat boundaries, and the main food resource of top predators was the prey species from the subtidal habitat. Therefore, the spatial scale of the Hiura rocky intertidal food web temporally varied with birds foraging across habitat boundaries. [source] | ||||||||||