Big Island's Mesophotic Fish

Published 2017-05-03

Photo: NOAA PIFSC

In the waters off Hawaii Island, Hawaii (Big Island) marine researchers have documented fish communities in under-explored mesophotic reefs. These reef communities provide essential habitat for fish and invertebrates and may play an important role in preserving biodiversity. The depth at which these reefs exist (beyond the photic zone) may offer a “refuge” from disturbance and stress as compared to shallower reef environments. However, this depth poses a challenge for marine researchers in collecting and observing the biological communities. Until the development of trimix scuba technology, these reefs were inaccessible to divers. Recently, a study published in the journal Coral Reefs, authored by Corinne Kane and Brian Tissot of Washington State University, presents a more complete picture of the fish communities around Hawaii Island.

Previous work in mesophotic reefs estimates that nearly half of the Northwestern Hawaiian Island fish are endemic and occur no where else in the world. This rate of endemism is much higher than in any other tropical region. For the first time on Big Island, Kane and Tissot’s study documented the composition of reef fish communities and found that the fish community in the upper portion of mesophotic reefs is similar to that of shallower reefs. The authors suggest these results show evidence that mesophotic reefs provide additional critical habitat for shallow reef fishes. Similar trends have been documented in the Atlantic Ocean and the Red Sea. These studies also show that in deeper waters, herbivorous fish are nearly absent, suggesting differences in the relative importance of key functional groups between these habitat types.

Corinne N. Kane, Brian N. Tissot. Trophic designation and live coral cover predict changes in reef-fish community structure along a shallow to mesophotic gradient in Hawaii. Coral Reefs, 2017; DOI: 10.1007/s00338-017-1581-x