Trophic relationships of three deep-sea crustacean species (Aristeus varidens, Plesionika martia and Funchalia woodwardi) off Namibia

Abstract

Trophic ecology of deep-sea crustaceans in the marine waters off Namibia is not well understood, although they form part of diets of important commercial species off Namibia. Study of their trophic relationships enhances our understating of the functioning of marine food webs and avail information needed for consideration of trophic interaction in fisheries management decisions. This study aimed at investigating the trophic relationships of striped red shrimp (Aristeus varidens), golden shrimp (Plesionika martia) and Woodward’s pelagic shrimp (Funchalia woodwardi) using stable isotope (nitrogen 15N) measurements of their muscle tissues. Samples were collected during the 2010 annual hake biomass survey off Namibia. Significant differences were observed in the mean trophic levels and nitrogen (15) measurements of the three species. Funchalia woodwardi showed a negative linear relationship between size and 15 and between depth and 15. Aristeus varidens and P. martia showed no significant linear relationship between 15 and depth or size. This work is the first to examine trophic relationships of the three deep sea crustaceans in the Northern Benguela current ecosystem using stable isotope analysis.