Seagrass and rhodolith beds are important seascapes for the development of fish eggs and larvae in tropical coastal areas

Abstract

In this study, the ichthyoplankton in two distinct tropical seascapes, gravelly sand with rhodolith beds (SRB) and muddy sand with seagrasses, were compared. The number of eggs was higher in the seagrass beds; however, the number of fish larvae was slightly higher in the SRB. Seagrass beds present less turbulent hydrodynamics and favor the retention of eggs and spawning. A more structured habitat provides better shelter, especially for eggs. However, as ontogeny progresses, the fish can explore areas with less shelter. This behavior was observed in this study, where the less structured SRB habitat had a high density of larvae in the later developmental stage. The dominance of earlier larval stages demonstrates a preference for more protected and less turbulent seascapes for nursery and offspring rearing. The results highlight that mapping of these seascapes (e.g., seagrass and rhodolith beds) will help to establish conservation measures to protect ecological connectivity and important tropical species.

Keywords: Connectivity; Fisheries; Ichthyoplankton; Rhodolith beds; Seagrass meadow.