Retention and export of planktonic fish eggs in the northeastern Gulf of Mexico

Abstract

To help determine whether planktonic eggs of fishes on the West Florida Shelf (WFS) are retained locally or exported elsewhere, we collected fish eggs by plankton net from 17 locations (stations) and identified them using DNA barcoding. We then entered the station coordinates into the West Florida Coastal Ocean Model (WFCOM) and simulated the trajectories of the passively drifting eggs over 2 weeks at three depths (surface, midwater, and near bottom). The results indicated there were two groups of trajectories: a nearshore group that tended to be retained and an offshore group that tended toward export and potential long-distance dispersal. We also found evidence of a relationship between retention and higher fish-egg abundance; nearshore stations were associated with higher fish-egg abundances and higher retention. We suggest this is the result of (1) increased spawning in high-retention areas, (2) increased drift convergence in high-retention areas, or both processes acting together. Community analysis using SIMPROF indicated the presence of a depth-related (retention-related) difference in species assemblages. Fish-egg species were also categorized as pelagics or non-pelagics; there was no evidence of pelagic species being more likely to be exported.