Implications of disperser phenotype on vertical migration and dispersal outcomes of a temperate reef fish

Larval dispersal is a key process in determining population connectivity, community structure, and biodiversity. It has recently been established that the environment encountered by dispersing larvae can contribute to... [ view full abstract ]

Larval dispersal is a key process in determining population connectivity, community structure, and biodiversity. It has recently been established that the environment encountered by dispersing larvae can contribute to differences in the quality of dispersers (disperser phenotype), and can lead to carry-over effects such as post-settlement survival and/or decreased fitness in subsequent life-stages. Although recent research has focused on quantifying the environmental determinants of dispersal outcomes, very little is known about how individual variability (e.g. size, growth rate) influences this process. We investigate what factors affect this dispersal experience for an individual larval fish by assessing the influence of disperser phenotype on the vertical distribution throughout the water column. Using a series of 24-hour depth-stratified ichthyoplankton sampling periods and a 3-dimensional bio-physical larval dispersal model, we quantified disperser phenotypes (based on larval condition indices and otolith growth history), their vertical distribution patterns (sampling depth), and potential dispersal outcomes (dispersal model) for the southern hulafish, Trachinops caudimaculatus, in Port Phillip Bay, Australia. Analyses to date reveal patterns in the depth distribution of hulafish larvae, with the majority of larvae found in the bottom two depth strata, and depth distribution varies with larval size. Understanding the influence of larval phenotype on dispersal outcomes will contribute to our understanding of marine population connectivity and persistence.