Spatiotemporal patterns of trophic niche variation within and among species of tropical coastal fishes

Intraspecific niche variation shapes the structure and function of food webs, but we still know little about the magnitude and drivers of trophic variation within species in species-rich communities. Here, we examined how intrinsic (sex and life stage) and extrinsic (locality and season) factors affect the diet composition and trophic niche width of tropical fish species. Specifically, we studied co-occurring species with benthopelagic (Stellifer ericymba, S. melanocheir, S. zestocarus, and Larimus argenteus) and benthic feeding habits (S. strabo, Cathorops manglarensis, Notarius troschelii, and Urotrygon rogersi) on the central Pacific coast of Colombia. Overall, we observed strong spatial and seasonal effects driving variation in the consumption of (i) amphipods, copepods, and decapods for benthopelagic species and (ii) molluscs and polychaetes for benthic species. As expected, we observed little sexual diet variation; however, surprisingly, most species showed little ontogenetic diet variation. Seasonality strongly shaped the trophic niche width for most species, but effects were species-specific, suggesting no general pattern of seasonal niche expansion across species. In turn, spatial effects on the trophic niche width were congruent across species, which might be related to differences in the diversity of available resources between bays. Our results reveal the complex interplay between intrinsic and extrinsic factors in shaping resource exploitation by coastal fish. This high level of trophic plasticity may be a critical component for both the persistence of marine populations and the stability of local food webs.

Methods
This data set corresponds to the prey items found in the stomach contents of the fish species analyzed. Each data base contains the locality, season, sex (female, male, indeterminate), size (total length, standard length), and life stage (Adult, Juvenile, indeterminate) of each individual. For each prey item, we provide the specific abundance and weight (to the nearest milligram).