Feeding ecology of the pandalid shrimp, Plesionika semilaevis (Spence Bate 1888) in South Eastern Arabian Sea

Abstract

The feeding ecology of deep-sea crustaceans is crucial in understanding the ecological roles and interactions of deep-sea organisms as they play a critical role in deep-sea food webs as intermediate trophic level organisms. This study provides the first examination of the feeding ecology of deep-sea shrimp Plesionika semilaevis (Spence Bate 1888) and provides new insights into deep-sea community structure. An aggregate number of 2213 individuals (842 males, 1016 berried and 355 non-berried females) were collected from the South Eastern Arabian Sea from 2019 to 2022 and their feeding ecology was studied in relation to the environmental (season) and biological (maturity, sex and size) factors. The index of preponderance values indicates the species has a diversified diet with a wide trophic niche ranging from smaller foraminifera to larger crustaceans and fishes. Frequency of occurrence (FOC) reveals that crustaceans, detritus and foraminifera forms the main prey while fishes, molluscs and sponges form the secondary prey. Berried females had the highest feeding intensity compared to males and non-berried females. Among the studied groups,the percentage of full stomachs was higher during the pre-monsoon period than post-monsoon. Feeding intensity was highest for smaller individuals and decreased gradually with an increase in size. Statistical analyses (ANOVA) also confirmed the significant differences (p<0.05) in the diet composition and feeding intensity of berried and non-berried females, pre-monsoon and post-monsoon samples and, juveniles and adults. The PERMANOVA test showed that there were significant differences in diet in the interaction between sex and size (p=0.003) and between sex and season (p=0.001). The present study also suggests that the seasonal variation in feeding intensity could be attributed to oceanographic phenomena like upwelling prevailing in the South Eastern Arabian Sea.