Inferring processes from spatial patterns: the role of directional and non-directional forces in shaping fish larvae distribution in a freshwater lake system

PLoS One. 2012;7(11):e50239. doi: 10.1371/journal.pone.0050239. Epub 2012 Nov 20.

Abstract

Larval dispersal is a crucial factor for fish recruitment. For fishes with relatively small-bodied larvae, drift has the potential to play a more important role than active habitat selection in determining larval dispersal; therefore, we expect small-bodied fish larvae to be poorly associated with habitat characteristics. To test this hypothesis, we used as model yellow perch (Perca flavescens), whose larvae are among the smallest among freshwater temperate fishes. Thus, we analysed the habitat association of yellow perch larvae at multiple spatial scales in a large shallow fluvial lake by explicitly modelling directional (e.g. due to water currents) and non-directional (e.g. due to aggregation) spatial patterns. This allowed us to indirectly assess the relative roles of drift (directional process) and potential habitat choice on larval dispersal. Our results give weak support to the drift hypothesis, whereas yellow perch show a strong habitat association at unexpectedly small sizes, when compared to other systems. We found consistent non-directional patterns in larvae distributions at both broad and medium spatial scales but only few significant directional components. The environmental variables alone (e.g. vegetation) generally explained a significant and biologically relevant fraction of the variation in fish larvae distribution data. These results suggest that (i) drift plays a minor role in this shallow system, (ii) larvae display spatial patterns that only partially covary with environmental variables, and (iii) larvae are associated to specific habitats. By suggesting that habitat association potentially includes an active choice component for yellow perch larvae, our results shed new light on the ecology of freshwater fish larvae and should help in building more realistic recruitment models.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Distribution*
  • Animals
  • Body Size
  • Ecosystem
  • Fresh Water
  • Larva / physiology*
  • Perches / physiology*
  • Quebec

Grants and funding

This project was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Canada Research Chair in Freshwater Ecology to P. Magnan and from funds from the MRNF to M. Mingelbier. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.