Standardized diet compositions and trophic levels of skates (Chondrichthyes: Rajiformes: Rajoidei)

摘要: Skates by virtue of their abundance and widespread occurrence appear to play an influential role in the food webs demersal marine communities. However, few quantitative dietary studies have been conducted on this elasmobranch group. Therefore, better understand ecological skates, standardized diet compositions trophic level (TL) values were calculated from studies, compared within among skate shark taxa. Prey items grouped into 11 general categories facilitate composition TL calculations. Trophic for 60 species with estimates ranging 3.48 4.22 (mean = 3.80 ± 0.02 SE). Standardized results revealed that decapods fishes main prey taxa most followed amphipods polychaetes. Correspondingly, cluster analysis data four major guilds, each dominated one these groups. Fish decapod guilds dominant comprising 39 48 analyzed. Analysis families Arhynchobatidae Rajidae had similar 3.86 3.79 (t-test, P 0.27), respectively. The Anacanthobatidae represented a single species, Cruriraja parcomaculata, 3.53. Statistical comparison five genera (Bathyraja, Leucoraja, Raja, Rajella, Rhinoraja) significant difference between Bathyraja Rajella 0.03). A positive correlation was observed total length (L T) larger skates (e.g. >100 cm L tending higher value (>3.9). found occupy TLs those several co-occurring including Scyliorhinidae, Squatinidae, Triakidae. Results study support recent assertions utilize resources other upper trophic-level predators, e.g. seabirds, mammals, sharks. These preliminary findings will hopefully encourage future research relationships impact interesting important predators.