Evidence for Cohesive Dispersal in the Sea

Ofer Ben-Tzvi,Georges L Paradis,Giacomo Bernardi,Steven D Gaines,Michael S Sheehy,Moshe Kiflawi,Avigdor Abelson,Ricardo Beldade

doi:10.1371/journal.pone.0042672

Abstract

As with many marine species, the vast majority of coral-reef fishes have a bipartite life cycle consisting of a dispersive larval stage and a benthic adult stage. While the potentially far-reaching demographic and ecological consequences of marine dispersal are widely appreciated, little is known of the structure of the larval pool and of the dispersive process itself. Utilizing Palindrome Sequence Analysis of otolith micro-chemistry (PaSA;) we show that larvae of Neopomacentrus miryae (Pomacentridae) appear to remain in cohesive cohorts throughout their entire pelagic larval duration (PLD; ∼28 days). Genetically, we found cohort members to be maternally (mtDNA) unrelated. While physical forcing cannot be negated as contributing to initial cohort formation, the small scale of the observed spatial structure suggests that some behavioral modification may be involved from a very early age. This study contributes to our ongoing re-evaluation of the processes that structure marine populations and communities and the spatial scales at which they operate.

Highlights

Upon hatching, the larvae of most coastal marine species may be passively advected considerable distances before settling back onto the benthos [1]
The larvae of most coastal marine species may be passively advected considerable distances before settling back onto the benthos [1]. Such dispersal is commonly modelled as a diffusive process that mixes larvae from different source locations; gradually erasing, within the larval pool, any spatial patterns introduced by adultpopulation structure [2,3]
The degree of intra-cohort similarity in otolith micro-chemistry reported here for N. miryae provides evidence which suggests that small-scale aggregations of larval fish can appear early in ontogeny and persist through weeks of pelagic dispersal

Summary

Introduction

The larvae of most coastal marine species (including those having benthic eggs) may be passively advected considerable distances before settling back onto the benthos [1]. Such dispersal is commonly modelled as a diffusive process that mixes larvae from different source locations; gradually erasing, within the larval pool, any spatial patterns introduced by adultpopulation structure [2,3]. Evaluation of the mechanisms that could potentially structure the larval pool is hampered, by a dearth of direct ‘observations’ of the paths followed by marine larvae as they disperse [11]

Methods

Results

Conclusion