Non-overlapping isotopic niches of hydrothermal vent fauna from North Fiji Basin, Southwest Pacific

Abstract

Food web studies provide information on resource partitioning and function of organisms in an ecosystem. It is important to study source and flow of energy in vent fauna across different vents as these patterns are closely related to their adaptation and survival in such an extreme environment. This study explored food web structure, more specifically, nutritional sources and trophic relationship of vent fauna from active hydrothermal vents in North Fiji Basin (NFB), southwest Pacific using sulfur, carbon, and nitrogen stable isotopes. Symbionts of the host taxa such as hairy snail Alviniconcha boucheti., black snail Ifremeria nautilei, and vent mussels Bathymodiolus sp. either had different carbon fixation pathways or nutrient preferences. Secondary consumers such as shrimp Rimicaris variabilis, scale worm Branchinotogluma segonzaci, and squat lobster Munidopsis spp. also varied greatly in terms of their energy sources depending on food availability either specializing on specific diets or feeding more generally. Crab was a top predator in the NFB possibly consuming everything with less preference for mussels when diverse carbon sources are available. Overall, we found non-overlapping isotopic niches of the vent fauna in the NFB, each taxon having unique source and composition of diets. Such diversification of niches and flexible resource use may play as an important role in sustaining stability and biodiversity of vent ecosystem.