Feeding Ecology and Seasonal Shifts in Diet of the Daisy Stingray Fontitrygon margarita (Günther, 1870) off Lagos Coastal Waters, Nigeria

Abstract

A total of 360 specimens of the daisy stingray (Fontitrygon margarita), ranging in disc width from 12.5 to 41.8 cm, were collected from February 2023 to July 2024 off the Lagos Coastal Waters, Nigeria, to examine their feeding ecology and dietary variation. The proportion of empty stomachs ranged between 23.33% and 28.57%, with an overall mean of 26.23%, suggesting consistent feeding activity throughout the study period. Stomach content analysis revealed that F. margarita is an opportunistic carnivore, preying mainly on benthic organisms. Crustaceans were the dominant food item across all size groups, accounting for the highest numerical (49.9%), volumetric (50.8%), and occurrence (33.8%) values, with an Index of Relative Importance (IRI) of 72.4%. Fish and annelids were secondary prey, contributing 20.1% and 20.6% numerically, with corresponding IRI values of 12.7% and 11.6%, while molluscs were least important (IRI = 3.3%). Ontogenetic dietary shifts were observed, with larger individuals consuming more fish, whereas smaller stingrays relied predominantly on crustaceans and annelids. The observed stability in feeding pattern indicates favourable environmental conditions and prey availability. These findings highlight the trophic adaptability of F. margarita and its ecological significance as a benthic predator within the Lagos coastal ecosystem, providing baseline information for effective management and conservation.