Relative importance of water column vs zooplankton variables in the determination of late-stage larval fish assemblage structure in coastal waters of a coral reef lagoon

Laure Carassou,Dominique Ponton

doi:10.3989/scimar.2009.73s1073

Abstract

SUMMARY: The relationship between fish larvae and their zooplanktonic prey has not been fully explored for late-stage larvae of coral-reef fish in lagoonal environments. However, compared to most temperate taxa, these larvae are characterized by strong sensory and swimming abilities, which may influence their feeding behaviour in the water column. The present study aims to determine the relative importance of the water column and zooplankton variables for the structure of pre-settlement larval fish assemblages within a single season in three bays of the coral reef lagoon of New Caledonia, southwest Pacific. The structure of larval assemblages was found to be explained better by water column variables in two out of the three bays examined. Zooplankton variables only played a role in one bay out of the three, probably due to the lower variability in the water column variables. Moreover, the relationship between total larval fish abundance and zooplankton density was not significant in any of the three bays. These results suggest that the relationship between late-stage coral-reef fish larvae and their prey: 1) is difficult to detect at small spatial and temporal scales, 2) is probably complex and non-linear, 3) depends on environmental conditions, and 4) probably varies between fish taxa.

Highlights

According to the “match-mismatch” hypothesis (Cushing, 1975, 1990), the temporal co-occurrence of fish larvae and their prey is responsible for the variability in larval survival rates, and for the interannual variations in recruitment success
The principal component analysis (PCA) on water column and zooplankton variables made it possible to account for 53.4% of the variability between samples with the first two components
The first axis of the PCA was explained by variations in the density of most zooplanktonic categories, whereas the second axis mainly represented variations in the Chl, POC, PON and POP concentrations (Fig. 2a)

Summary

Introduction

According to the “match-mismatch” hypothesis (Cushing, 1975, 1990), the temporal co-occurrence of fish larvae and their prey is responsible for the variability in larval survival rates, and for the interannual variations in recruitment success. The postulate that larval survival improves when the distribution of larvae and that of their prey are closely related is widely accepted and has been demonstrated in some studies (Hartmann, 1983; McCormick and Molony, 1992). Significant relationships between larval fish abundance and zooplankton density have been observed in a number of case studies and for particular larval fish species in temperate ecosystems (Brander et al, 2001; Pepin et al, 2003; Voss et al, 2006). In spite of its significant ecological relevance, our current knowledge on the relationships between total larval fish abundance and total zooplankton biomass or density is still limited (Sanvicente-Añorve et al, 2006)

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