RAPID: Phase Shift to Algal Dominated Mesophotic Reef Communities in Response to Lionfish Invasion

University Of New Hampshire, Durham NH

Investigators

Abstract

Abstract Intellectual Merit: Shallow coral reefs in the Caribbean basin have been severely degraded due to regional impacts from global climate change, and local effects of overfishing and pollution. This decline in coral reef health has promoted interest in mesophotic coral reefs (reefs at depths of 30 to 150 m) because they are often physically and biologically connected to their shallow water counterparts, and thus may serve as potential refugia for shallow reef taxa and a source of larvae that could promote the resiliency of shallow water reefs. The recent invasion of the red lionfish (Pterois volitans), a native of the sub-tropical and tropical Indo-Pacific ocean basin, onto shallow reefs of the Caribbean and Bahamas has had a profound effect on endemic coral reef fish populations. The investigators propose that the impacts of these lionfish have extended to mesophotic reef depths throughout the Bahamas. The PIs will examine the effects of lionfish on mesophotic reefs using a comparative approach for reefs within a region and reefs between regions (Bahamas versus Little Cayman). In the Bahamas these predators have had a significant negative effect on five distinct guilds of mesophotic reef fishes, and the ensuing trophic cascade has facilitated a phase shift towards an algal dominated (>50% cover) community to depths of 60 m, or greater, due to reduced grazing pressure. This has further resulted in a significant decline in the percent cover of corals and sponges. The direct and indirect effects of this invasive species to mesophotic reefs exceeds other natural and anthropogenic stressors, and casts doubt on whether these important deep reef communities can actually stimulate the recovery of shallow Caribbean reefs where lionfish now reside. Broader Impacts: Mesophotic coral reefs are greatly understudied and represent unique habitats compared to their shallow water counterparts. The studies that have been done suggest that mesophotic reefs could be a refuge from anthropogenic change or a supplier of propagules to shallow reefs for certain coral reef taxa. The insights provided by work on the effects of the recent lionfish invasion to mesophotic depths suggest that quick response to this novel threat to mesophotic reefs is warranted to understand the extent of change on reefs with and without lionfish. This research will complement work already funded in the shallow reefs of the same system, and nowhere else is a combined shallow and mesophotic reef approach to the lionfish invasion being carried out. Broader Impacts will provide unique educational and outreach opportunities at high schools through the participation of the principal investiagtors in regional Junior Science and Humanities Symposia and UNH's Science and Mathematics Achievement Through Research program (SMART) by providing mentorship and lectures about the ecology, biology, and value of coral reefs. Data, graphics, and publications will be made available to both the oceanographic and marine ecology communities through the "Mesophotic Coral Ecosystems" web site.