Multi-Decadal Habitat Changes Mapped via Remote Sensing and Implications for Juvenile Lemon Sharks (Negaprion Brevirostris) and their Nursery Areas.

Abstract

Shark species currently face anthropogenic pressures, including loss of critical habitat. In Bimini, the Bahamas, two nursery areas exist for juvenile lemon sharks (Negaprion brevirostris) with mangrove and seagrass providing protection from predators and habitat for prey. Over two decades, coastal development has removed large areas of mangrove in these nurseries. To quantify construction impacts, mangrove and seagrass extents were mapped from 1999 to 2020 using satellite imagery. Maps revealed that terrestrial vegetation removal impacted aquatic habitat through sedimentation of seagrass beds. I then analyzed the relationship between habitat extents and annual shark survival estimates from a long-term mark-recapture dataset. I found the amount of habitat change in a year significantly affected survival, but that this relationship varied between the two nurseries. My results highlight the nuanced impacts of coastal construction on shark survival and the importance of mitigating construction impacts while protecting remaining habitat to ensure continued shark resiliency.