Influence of Surface Currents in the Dispersal Pathways of Eggs of Cubera Snapper, Lutjanus cyanopterus (Cuvier, 1828), at a Spawning Aggregation Site at Gladden Spit, Belize
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Most large reef fish use a migratory reproductive strategy and tend to spawn in aggregations that occur at predictable locations and times. Though numerous hypotheses have been formulated to explain the reasons behind this phenomenon, there remain few data to evaluate the relative merits of various hypotheses. Oceanographic variables and lunar cycles are believed to drive the timing and location of this reproductive strategy. However, the dynamics of the interaction between coastal currents, water temperature, biomass concentrations, spawning site selection and gamete transport are still unclear. This study aimed to examine the influence that currents exert on gametes released at spawning aggregations of Cubera snapper Lutjanus cyanopterus (Cuvier, 1828) at Gladden Spit, Belize. It was hypothesized that surface currents flowed offshore at the time and location of spawning. However, observations from this study, using Lagrangian and Eulerian methods, indicated that eggs most likely travel westerly towards the reef and into the reef channel. The dispersal rate of eggs appeared to be explained by a power relationship, with buoyant fertilized eggs dispersing horizontally such that the area of the spawning cloud increased with time. Egg density within the spawning cloud generally decreased over time as it dispersed with the predominant surface currents. Most importantly low-cost surface drifters area an appropriate, highly replicable way to monitor surface ocean currents at spawning sides in areas where more sophisticated methods are not available. Understanding how abiotic factors influence the occurrence of multispecies spawning aggregations will lead to better conservation and management strategies in the Western Caribbean.