By Daniel Kelly From Fishsens Magazine

Using a manned submersible vehicle privately owned by the Substation Curacao, researchers with the Smithsonian Institution have discovered a new goby species. The fish was found off the coast of Curacao, a small island nation in the southern Caribbean Ocean around 40 miles north of Venezuela.

Like round gobies that inhabit the Great Lakes, Coryphopterus curasub is a small fish and part of the Gobiidae family, but it belongs to an entirely different subfamily and genus. The clearest difference between the two gobies is that those in the Great Lakes are invasive, whereas the species discovered off the coast of Curacao is part of a native group of gobies found in the eastern Pacific and western Atlantic oceans.

The discovery comes after years of work by scientists involved with the Smithsonian’s Deep Reef Observation Project that relies on the submersible to study biodiversity in Curacao reefs between 200 and 1,000 feet below the surface. These reefs are called “deep reefs,” and boast life similar to reefs found around the world, including corals, crustaceans and fishes. But given their locations, too deep to be accessed by scuba divers and too shallow for deep-ocean submersibles, they have largely been unstudied by scientists the world over.

“The discovery of this new goby in particular involved collecting small, mostly white-colored fishes living on and blending in with sand. They are hard to see!” said Carole Baldwin, curator of fishes at the Smithsonian’s National Museum of Natural History. In making the discovery, she was joined by Ross Robertson, a staff scientist with the Smithsonian Tropical Research Institute. “When we collected the specimens, we did not know initially that they represented an undescribed species. Discovering new species is rarely a Eureka moment.”

Instead, as she describes the processes behind the discovery, scientists took the fish back to a lab for analysis and only then realized the differences between it and other described goby species. The fish’s color patterns first tipped them off because they didn’t resemble others out there. They noted that the morphology of the new fish was a little different too.

To confirm that their suspicions were accurate, scientists leveraged DNA analysis techniques and saw that the DNA of their specimens did not match with any species known to exist at the time.

Is there something special about the area that contributed to this new fish find? Baldwin says that she and others don’t yet know.

“So little exploration has been conducted on deep reefs, we don’t know if the new species is restricted to Curacao or occurs more broadly in the southern Caribbean, throughout the Caribbean, or even along the southeast coast of the U.S.,” said Baldwin.

But researchers do know the scientific implications of this new fish find. Notably, it lets them know that Coryphopterus gobies that are typically found in shallow reefs have transitioned to also living in deep-reef areas. With that knowledge, scientists can now set about answering questions relating to when the move occurred and what the reasons were behind it. The best way to find the answers is to reconstruct the evolutionary history of the fish, Baldwin says, and then date transitional speciation events.

“Let’s say we had reconstructed the evolutionary history of Coryphopterus gobies prior to discovering the new species. That history would have been wrong, because it would have suggested that there were no members of the group inhabiting deep waters,” said Baldwin. “So exploring new depths and finding new species help us fill in the gaps and get a more complete picture of biodiversity.”

She adds that better understanding of that evolutionary history could improve knowledge of ongoing changes in ocean fish populations due to climate change. One recent study, by scientists at Australia’s James Cook University, appears to have made a related find. In an investigation tracking red-throated emperor fish off the Great Barrier Reef, researchers found that some of the tagged fish dive to deeper areas off the reef to escape warmer waters.

Up next for the Smithsonian team is to investigate other deep-reef areas to chart how other lifeforms near Curacao are distributed. But first they are looking to raise funds to support transporting the submersible on a shipboard platform.

“We are also monitoring temperature and some biological conditions on a shallow-to-deep reef slope off of Curacao,” said Baldwin. “There are no long-term data sets that allow us to detect environmental and biological changes on deep reefs, so we have acquired the baseline data necessary to detect changes in the future.”

IMAGES:
Smithsonian researchers are using this five-person submersible to study the biodiversity of the deep reefs of Curacao in the southern Caribbean. (Credit: Barry Brown, Substation Curacao)
Coryphopterus curasub, a new goby species from 70 to 80 meters depth off Curacao, southern Caribbean. The maximum known length of the new species is 33 millimeters (1.3 inches). (Credit: Carole Baldwin and Ross Robertson, Smithsonian Institution)
Smithsonian researchers are using this five-person submersible to study the biodiversity of the deep reefs of Curacao in the southern Caribbean. (Credit: Barry Brown, Substation Curacao)

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