- A new species of wrasse discovered in mesophotic reefs off the coast of Zanzibar, Tanzania, underlines how little is known about marine environments.
- Deeper-lying reefs are just as threatened by climate change and other human impacts as shallow reefs and need greater protection.
- Mesophotic reefs could be an important and under-recognised source of fish larvae that supports coastal fisheries.
A striking new species of wrasse discovered off the coast of Zanzibar, Tanzania, underlines how little is known about marine environments — even those relatively close to shore. Deeper-lying reefs like the one that is home to the newly described fish are ecologically connected to their shallower neighbors, and need greater protection.
Luiz Rocha and Hudson Pinheiro, from the California Academy of Sciences (CAS), were into the fourth day of a Hope for Reefs diving expedition off the coast of Zanzibar. In the dim light 70 to 80 meters (230 to 260 feet) down, the team saw rock falls, sponges, hard, pinkish-red coralline algae and soft corals; there were plenty of fish, glimpses of familiar anthias, damselfish, and other reef species.
Hope for Reefs is a five-year project aimed at better understanding and protecting reefs, and Pinheiro and Rocha’s team was conducting a general biodiversity assessment of a mesophotic reef, which are found at depths of between 30 and 150 meters (100 to 500 feet), are less well-studied than shallower reefs, but are also richly diverse ecosystems.
Then something spectacular swam by.
“When we saw the fish we stopped right away and thought ‘Wow,’” Pinheiro says. “It was super beautiful. That is the first impression that we had.”
The fish Rocha and Pinheiro saw was a kaleidoscope of colors: a pale yellow head, fading into white or pinkish scales, a bluish-purple dorsal fin, bright fuchsia on other parts, with almost translucent magenta pelvic fins, a transparent blue tail, and a chain link of purple markings across the rest of its body. This unique shading inspired the name the researchers gave the fish: the vibranium fairy wrasse, or Cirrhilabrus wakanda, after the mythical African kingdom of Wakanda from the Marvel comic books and movies, and the miracle element from which it draws its power.
Rocha, the CAS curator of fishes and Follett Chair of Ichthyology, has discovered and described more than 30 species. “We were both 99 percent certain it was a new species. I really knew it was different though when I looked at the picture I took (with strobes) which revealed the purple markings,” he tells Mongabay.
Rocha and Pinheiro sent a picture to a fish taxonomy savant in Sydney named Tea Yi-Kai. Tea, an ichthyology Ph.D. student at the University of Sydney, was aware of other fairy wrasse species in the Indian Ocean, but he knew there was a missing species.
“Cirrhilabrus wakanda happens to belong to a particular group that is pretty well studied. We can predict, based on their patterns of distribution, that a species could very well occur along the East African coast — and this was it,” he tells Mongabay.
The wrasse family is hugely diverse, with close to 600 species; there are nearly 60 known species of Cirrhilabrus alone — “habitat specific”, Tea says, mostly living in rubble zones adjacent to coral reefs. If C. wakanda is like other wrasses, it lives in large groups of mostly females, juveniles and a few males.
“The bright purple markings and the overall pattern of this fish is very reminiscent of the fabric motifs and colour scheme of the clothes worn by the native Wakandans,” Tea says. “The details are also similar to Black Panther’s suit, which is made of a rare substance called vibranium. We thought this was a nice complement to its species name, wakanda,” Tea says.
Extend protection to deep-lying reefs
While fairy wrasses are common across a range of oceans, including the Pacific and Indian oceans and the Red Sea, the identification of a new wrasse species here is particularly significant for its habitat and future conservation.
Scientists know relatively little about mesophotic reefs as these areas are too deep for conventional diving, yet too shallow for submersible research vessels. Diving to these depths requires scientists to be trained in the rebreather method, carrying additional tanks that recycle the air they breathe as they go.
Last year, Rocha, Pinheiro and others published a report in Science outlining how these deeper-lying reefs are just as threatened by the climate crisis and other human impacts as shallow reefs and urging greater protection for them.
“The species that are down there are different than the shallow ones, it’s a different community,” Rocha says. “Think rainforests versus savanna, they share a few trees but most species are different between these two habitats, and both are threatened, so nobody claims that one is a refuge for the other. Same for deep versus shallow reefs.”
Dominic Andradi-Brown, a scientist at the WWF working to support marine protected area (MPA) monitoring and evaluation activities, is familiar with the Science report and has collaborated with several of the scientists who produced the research.
“It’s hard to truly predict what’s at stake when we still have so much to learn about the biodiversity that inhabits mesophotic reefs,” he tells Mongabay in an email. “Much of the unknown biodiversity that relies on these unique ecosystems could be destroyed before we discover and identify it.”
He adds that the role of mesophotic reefs in supporting coastal communities is likely overlooked, as “deeper reefs could be an important and under-recognised source of fish larvae for supporting coastal fisheries.”
The Hope for Reefs dive off Zanzibar found trash, abandoned fishing gear and sedimentation (likely linked to coastal soil erosion and can affect coral health). One way to better protect mesophotic reefs like the one where C. wakanda was discovered is to extend marine protected areas to include them.
There are currently 23 MPAs in Tanzania, including in Zanzibar, that protect mangroves, coral reefs, seagrass beds and the open sea.
“Because most people thought deep reefs were immune to human impacts, many marine protected areas don’t include them. We are trying to change that view and include them in more protected areas, as well as create some specifically for them,” Rocha says.
But the ecosystems of shallow and deeper-lying reefs are connected. Many species, born and raised in the shallow reefs, cross the continental shelves and spend other parts of their life cycle in the deeper reefs.
The discovery of the beautiful vibranium fairy wrasse may be the way to ensure these areas are protected, Pinheiro says.
“It’s very important for us to be discovering and showing this biodiversity we have and be discussing with the public and managers about how to better take care of these habitats,” he says.
Tea, Y-K, Pinheiro, HT, Shepherd, B, Rocha, LA (2019) Cirrhilabrus wakanda, a new species of fairy wrasse from mesophotic ecosystems of Zanzibar, Tanzania, Africa (Teleostei, Labridae). ZooKeys 863: 85-96. doi.org/10.3897/zookeys.863.35580
Rocha, LA, Pinheiro, HT, Shepherd, B, Papastamatiou, Y, Luiz, OJ, Pyle, RL, Bongaerts, P (2018) Mesophotic coral ecosystems are threatened and ecologically distinct from shallow water reefs. Science vol 361, issue 6399: 281-284. doi: 10.1126/science.aaq1614
Banner image: Female Cirrhilabrus wakanda. Photo: Luiz Rocha/California Academy of Sciences.
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