New fish species discovered in the Caribbean’s “rariphotic” ocean zones

One of the new fish species discovered in the Caribbean deep reefs. Image: Carole Baldwin, Smithsonian
Biodiversity

Researchers at the Smithsonian Institute’s Deep Reef Observation Project (DROP) and the University of Washington have discovered several new deep reef fish species in the Caribbean:

University of Washington scientists are joining the Smithsonian to identify fish in deep reefs that are still a total mystery.

Preliminary work suggest that one-third of these Caribbean deep reef fishes still have no name.

“We have been going down in two different submersibles in the Caribbean across five different locations,” said masters student Rachel Manning. “These two-manned submersibles are the only subs in the world that have these fish collection devices. We spray out this anesthetic onto a fish we want to catch. It puts the fish to sleep. The fish starts floating on its side and then we have this giant vacuum cleaner basically attached to the outside of the sub. We suck that fish up, we put it into a holding tank, take it up to the surface. When we get up to the surface these fish are still alive so we can see their in-life coloration.”

Manning is currently describing six new gobies as a result of these dives. Gobies are one of the largest fish families comprising more than 2,000 species.

The principal scientists are Dr. D. Ross Robertson and Dr. Carole Baldwin of the Smithsonian as well as Dr. Luke Tornabene of UW. They have already described many new species thanks to the dives and are racing to finish the work.

Deep reefs are some of the least-explored, most diverse marine ecosystems in the world. Scientists have studied how climate change harms shallow reefs but have almost no idea if deep reefs experience the same kind of damage, if they’re protected, or if they’re facing a future that’s unpredictable.

Some of the new species identified are coral reef-dwelling fishes that scientists didn’t know could adapt to deeper systems. That could mean that all of the biodiversity around coral reefs could survive if the animals can move further towards the seafloor.

As a result of the DROP expeditions, Smithsonian scientists have also named a new ocean zone, the “rariphotic”:

Based on the unique fish fauna observed from a manned submersible on a southern Caribbean reef system in Curaçao, Smithsonian explorers defined a new ocean-life zone, the rariphotic, between 130 and 309 meters (about 400 to 1,000 feet) below the surface. The rariphotic occurs just below a previously defined reef zone, the mesophotic, which extends from about 40 to as deep as 150 meters (about 120-450 feet). The role of this new zone as a refuge for shallower reef fishes seeking relief from warming surface waters or deteriorating coral reefs is still unclear.

The initial motivation for studying deep-reef ecosystems was the declining health of shallow reefs. Many researchers wonder if deeper reef areas, sometimes known as the “coral reef twilight zone,” might act as refuges for shallow-water organisms. As the Smithsonian researchers sought to answer this question, it became clear to them that scientists have only scratched the surface when it comes to understanding the biodiversity of reef fishes.

For more information, see King 5 News, the Smithsonian DROP website, Phys.org, and the open access journal article Below the Mesophotic.

 

[Image: Carole Baldwin, Smithsonian, via phys.org]

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