Zooplankton prey selection among three dominant ichthyoplankton species in the northwest Gulf of St Lawrence

Abstract

The diets and feeding niches of early-stage larval sandlance (Ammodytes spp.), arctic shanny (Stichaeus punctatus), and snakeblenny (Lumpenus lampreytaeformis) were examined to study interactions among these dominant fish species and to better understand the ecological processes involved in structuring the ichthyoplankton community in the northwest Gulf of St Lawrence (GSL). Results indicate that sandlance and arctic shanny larvae have similar feeding niches but also that arctic shanny is more of a generalist and could be better adapted to cope with changes in the zooplankton community. The feeding incidence of sandlance larvae was lower than expected when compared with other similar studies. Snakeblenny larvae were larger and more developed at sampling time; they occupied a different feeding niche with larger prey species compared with sandlance and arctic shanny larvae. In the northwest GSL, the presence of Calanus glacialis and Calanus hyperboreus may be favourable for arctic shanny and snakeblenny since these copepod species are less exploited by sandlance larvae. This study is the first to describe diet selectivity and feeding niches of early-stage larval snakeblenny and arctic shanny in the natural environment. Our results demonstrate that detailed diet descriptions based on prey species and developmental stage identification should be used for a better interpretation of interactions within ichthyoplankton communities. © The Author 2012. Published by Oxford University Press. All rights reserved.