Mesophotic coral ecosystems (MCEs), often referred to as the ocean’s “twilight zone,” occur at depths of approximately 30–150 meters where light becomes increasingly limited and ecological conditions differ markedly from shallow reefs. Despite their ecological importance, these ecosystems remain among the least explored marine habitats due to the logistical and technical challenges of working at depth. Our research seeks to understand the ecological and evolutionary processes shaping mesophotic fish communities and their relationship to adjacent shallow reef systems.

We investigate how fish assemblages change across depth gradients, the extent to which populations are connected between shallow and mesophotic habitats, and the ecological mechanisms that structure biodiversity in these environments. A central question guiding this work is whether mesophotic reefs function as refugia - providing habitat capable of supporting biodiversity and potentially contributing to the persistence or recovery of shallow reef populations following disturbance.

Our research combines ecological surveys, genomics, and emerging technologies with advanced scientific diving methods, including closed-circuit rebreathers, to access habitats beyond the limits of conventional SCUBA. Ongoing and future projects include investigations of mesophotic fish communities and connectivity in the Caribbean, including Puerto Rico, with the broader goal of improving our understanding and conservation of these understudied ecosystems.

Photo: Conducting fish surveys at mesophotic depths (250') at Pohnpei, Federated States of Micronesia. Diving on closed-circuit rebreathers lets us dive to deeper depths and stay underwater for up to 5 hours or more allowings us to begin exploring mesophotic ecosystems (150-500'). These areas are too deep for conventional SCUBA and too shallow to invest the use of ROV's, thus we are pioneers in unexplored habitat. This is exhibited by new species of marine life being discovered on almost every dive that we do to mesophotic depths. Photo credit: Robert Whitton