EAPSI:Examining the Connectivity of Fish Populations Between Mesophotic and Shallower Reefs of Southern Japan

Johnson Garrett B, Kaneohe HI

Investigators

Abstract

While coral reefs worldwide are threatened by climate change, overfishing, and pollution, an enormous and unexplored coral reef zone may provide a refuge from many of these threats. Most coral ecosystem research has focused on shallow reefs less than 30m depth, though photosynthetic corals extend to 165m in many areas. This disparity is due to the physiological limitations of conventional scuba that confines researchers to the shallows. This study will utilize new technology in subsea instrument recovery, closed circuit rebreathers and standard diver-based transects to provide the first comprehensive analysis of MCEs of Japan. Research will be conducted in collaboration with Dr. James Reimer, a noted expert on genetics at the MISE Lab of the University of the Ryukyus in Okinawa, Japan. Results will yield empirical data to assess the level of connectivity of fish and invertebrate populations between MCEs and shallower reefs by genetic analysis. and will provide valuable insight into MCE habitat composition that will prove beneficial to marine resource managers. Mesophotic Coral Ecosystems (MCEs) are tropical light-dependent reef communities that extend from 30m to the bottom of the photic zone (165m). Remarkably MCEs account for two-thirds of zooxanthellate coral habitat, yet remain almost entirely unexplored. In particular the relationships between shallow and deep communities are unknown; MCE fish populations may overlap with those of shallower reefs, as suggested by the Deep Reef Refugia Hypothesis (DRRH), making MCEs a potential refuge from environmental stress. The objectives of this study are two-fold. First, the diversity of benthic covers of MCEs will be assessed at four sites. Second, the DRRH will be examined to assess the role of MCEs in providing larval fish and invertebrate recruits to shallow and deep reefs and to determine the overall extent of vertical gene flow. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.