Turbulence effects on the feeding dynamics in European sea bass (Dicentrarchus labrax) larvae

Abstract

Turbulence, unless reaching a threshold level, is generally assumed to enhance ingestion rates in larval fish by increasing encounters with prey. This hypothesis is mainly based on the assumption of a prey-limited environment. In some estuarine areas characterized by high turbulence levels, this hypothesis is rarely met. This study experimentally investigated the effects of flow turbulence (flow Reynolds number Re, ranging from 0 to 55×103) on prey ingestion in European sea bass (Dicentrarchus labrax) larvae exposed to prey densities comparable to what is found in a nursery area (i.e., Seine estuary, English Channel). This paper also estimated the prey ingestion rates in sea bass larvae exposed to three different flow conditions (Re=0, 21.6×103, and 43.9×103) during various time periods. Contrary to predictions regarding limiting prey densities, the analysis of individual gut contents under different levels of turbulence revealed that increasing Reynolds number (Re) decreased prey ingestion. In addition, increased turbulence affected the feeding to satiation levels in sea bass larvae.