MEPS 655:157-170 (2020)  -  DOI: https://doi.org/10.3354/meps13529

ABSTRACT: Caribbean whiptail and southern stingrays are large-bodied mesopredators, occupying shallow, nearshore ecosystems of The Bahamas, yet virtually nothing is known of their diet or potential resource competition. We used stomach content analysis via gastric lavage and stable isotope analysis to investigate the diet of 94 Caribbean whiptail rays Styracura schmardae and 112 southern stingrays Hypanus americanus across 3 locations in the central Bahamas. Gastric lavage was used to identify prey consumed and compared to stable isotope analysis of δ¹⁵N, δ¹³C and δ³⁴S of barb, muscle, blood and skin, representing different temporal integration periods. Both species appeared to consume a majority of crustaceans and annelids, although δ¹³C values suggested that Caribbean whiptail rays have larger isotopic niche space across isotopes sampled (potentially broader diet) than southern stingrays, ranging from 5.82-3.43‰², and a greater variance in δ¹³C. This suggests Caribbean whiptail rays potentially feed on prey from either a wider geographic range or from different habitats. Caribbean whiptail and southern stingrays are known to spatio-temporally overlap, and their isotopic niche overlapped by 35.6%. This study represents the first integrated diet estimate for southern stingrays obtained using multiple techniques, and the first ever diet assessment in Caribbean whiptail rays. These data are critical for conservation of coastal ray species and management of coastal and nearshore environments throughout the region.

KEY WORDS: Atlantic chupare · Bahamas · Diet composition · Elasmobranch · Gastric lavage · Foraging · Trophic ecology