Inter- and intra-specific variation in the pelagic larval duration of four Tropical Eastern Pacific damselfishes (Pomacentridae: Stegastes) with contrasting distribution patterns

Abstract

Dispersal is a key ecological function in marine populations that are naturally fragmented and sometimes isolated. Pelagic larval duration (PLD) is thought to approximate the dispersal potential of coral reef fishes and may reflect the extent of connectivity in reef fish populations. Inter- and intra-specific variation in PLD of four damselfish species was investigated in the Colombian Pacific at four locations (two on the mainland coast, one at a continental island and one at an oceanic island) at multiple spatial scales (between localities and between sites within a single locality). Two of the species (Stegastes acapulcoensis and S. flavilatus) are broadly distributed on the continental coast while the other two (S. beebei and S. arcifrons) are largely restricted to oceanic islands. Nonetheless, individuals of continental species sporadically colonize oceanic habitats, and vice-versa. The PLD was estimated using counts of otolith growth increments from juveniles collected at all localities. Species with an oceanic distribution had longer PLDs than their congeners with continental distributions. Differences in PLD between the two continental species varied between localities and significant intra-specific spatial variability was observed between localities but not within a single locality. Although the species studied have the necessary PLD to reach all available habitat, there are no apparent colonization events between mainland and oceanic islands suggesting that their distribution is not limited by dispersal but by other processes. We discuss the possible underlying causes of the observed variability, and suggest the need to consider spatial variability in the development of dispersal models and connectivity patterns for better management of coral reef fish populations.