East African fish in need of recovery

FEBRUARY 7, 2020

by Wildlife Conservation Society

A study of East African coral reefs has uncovered an unfolding calamity for the region: plummeting fish populations due to overfishing, which in turn could produce widespread food insecurity.

In a newly published paper in the journal Marine Ecology Progress Series titled "Coral reef fish communities, diversity, and their fisheries and biodiversity status in East Africa," WCS Senior Conservation Zoologist Dr. Tim McClanahan reports that overfishing is widespread across the region.

The remedy, says the sole author of the study, is to recognize the need to rebuild fish stocks to ensure they are providing the maximum possible catch for the developing countries of Kenya, Tanzania, and Mozambique. The African continent has among the highest human population growth rates and associated food security issues.

"Whereas fish stocks within marine parks and areas in distant or turbulent locations were found to be at healthy levels, coastal areas open to fishing were another story," said McClanahan. "We have found that fish catches have been declining in Africa in recent years by a million tons a year, and this study shows that much of this decline in East Africa is due to declining fish stocks."

Based on a sample of 239 sites—data gathered over several years—the study and previous estimates show that 70 percent of the reefs have fish stocks below the levels that will produce the maximum fisheries yields. The few areas above this level were in marine parks, rural areas, and remote or dangerous seas.

The study further shows that low stocks not only affects food production but also the diversity of fish and reef ecology. Numbers of fish species decline rapidly when stocks decline below sustainable levels. This loss of species will have consequences for the long-term recovery and the potential to produce food.

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Clownfish reproduction threatened by artificial light in coral reefs

JULY 10, 2019

by Flinders University

The popular story about a clownfish that got lost at sea in the movie Finding Nemo could have a much darker sequel—as artificial light in coral reefs leaves the famous fish unable to reproduce offspring, according to a new study.

Results from a new study published in Biology Letters show an increasing amount of artificial light at night (ALAN) in coral reefs, even at relatively low levels, masks natural cues which trigger clownfish eggs to hatch after dusk.

Lead author Dr. Emily Fobert, Research Associate in biodiversity and conservation at Flinders University, says test eggs that were incubated in the presence of artificial light had a zero success rate of hatching, with no offspring surviving as a result.

"The overwhelming finding is that artificial light pollution can have a devastating effect on reproductive success of coral reef fish," says Dr. Fobert

"When ALAN is present, no eggs hatched but when the light was removed during the recovery period, eggs from the ALAN exposure hatched like normal, so the presence of light is clearly interfering with an environmental cue that initiates hatching in clownfish."

"The results indicate increasing amounts of light have the potential to significantly reduce the reproductive fitness of reef fish who settle in a habitat near shore lines."

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Wakanda forever! Scientists describe new species of 'twilight zone' fish from Africa

JULY 11, 2019

by California Academy of Sciences

Africa has new purple-clad warriors more than 200 feet beneath the ocean's surface. Deep-diving scientists from the California Academy of Sciences' Hope for Reefs initiative and the University of Sydney spotted dazzling fairy wrasses—previously unknown to science—in the dimly lit mesophotic coral reefs of eastern Zanzibar, off the coast of Tanzania. The multicolored wrasses sport deep purple scales so pigmented, they even retain their color (which is typically lost) when preserved for research. The scientists name this "twilight zone" reef-dweller Cirrhilabrus wakanda (common name "Vibranium Fairy Wrasse") in honor of the mythical nation of Wakanda from the Marvel Entertainment comics and movie Black Panther. The new fish is described today in ZooKeys.

"When we thought about the secretive and isolated nature of these unexplored African reefs, we knew we had to name this new species after Wakanda," says Yi-Kai Tea, lead author and ichthyology Ph.D. student from the University of Sydney. "We've known about other related fairy wrasses from the Indian Ocean, but always thought there was a missing species along the continent's eastern edge. When I saw this amazing purple fish, I knew instantly we were dealing with the missing piece of the puzzle."

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Menu change for corals in warming reefs

March 26, 2019, University of Queensland

Warming coral reefs are losing their capacity to feed themselves from sunlight, making nutritious deep ocean water critical for their survival, according to a University of Queensland study.

UQ Ph.D. candidate Veronica Radice analysed coral samples from the Maldives to find out what corals were feeding on in a remote atoll system.

"Corals depend on different sources of nutrition including sunlight and nutrients in the water," she said.

"What many people don't realise is that corals have algae living in their tissue, which allows them to photosynthesise sunlight, giving the coral some plant-like properties.

"However, ocean warming due to climate change is causing these corals to be stressed, which makes them lose this nutritional source from their symbiotic algae.

"So we thought it was important to see what other food sources corals were relying on."

Ms Radice and her colleagues collected fragments of three species of coral from reefs at 10 metres and 30 metres depths in the Maldives.

"We separated the tissue of the symbiotic algae from its coral host tissue, and samples were then prepared for isotopic analysis," she said.

"This allowed us to break apart a coral's diet and nutrients, looking at the ratios of different isotopes – for example, carbon or nitrogen – giving us clues to where these nutrients might come from."

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Spectacular rebirth of Belize's coral reefs threatened by tourism and development

Report reveals improvement but also details danger posed by tourist-generated pollution, oil extraction and climate change

Nina Lakhani in Laughing Bird Caye, Belize

Tuesday 22 August 2017 06.00 BSTLast modified on Tuesday 22 August 2017 10.35 BST

Just below the surface of the turquoise sea, coral flutters majestically amid schools of puffed up porcupinefish and fluorescent blue and yellow angelfish.

The gangly staghorn and fanning elkhorn corals are thriving in swimming distance of Laughing Bird Caye, a tiny Caribbean sandy islet in southern Belize, thanks to a restoration project that is yielding striking results.

More than 90,000 corals grown in sea nurseries have been planted in shallow reefs, increasing coral cover in these southern warm waters by 35%. Marine creatures are reproducing, and about 90% have survived natural and manmade pressures for almost a decade.

Hailed as the most impressive coral reef restoration effort in the Caribbean, its success is linked to a grassroots movement uniting fisherman, tour guides, scientists and environmentalists working to conserve the 700-mile Mesoamerican Reef (MAR) – the second largest barrier reef in the world.

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Study finds parrotfish are critical to coral reef health

January 23, 2017

An analysis of fossilized parrotfish teeth and sea urchin spines by researchers at Scripps Institution of Oceanography at the University of California San Diego showed that when there are more algae-eating fish on a reef, it grows faster.

In the new study, published in the Jan. 23 issue of the journal Nature Communications, Scripps researchers Katie Cramer and Richard Norris developed a 3,000-year record of the abundance of parrotfish and urchins on reefs from the Caribbean side of Panama to help unravel the cause of the alarming modern-day shift from coral- to algae-dominated reefs occurring across the Caribbean.

"Our reconstruction of past and present reefs from fossils demonstrates that when overfishing wipes out parrotfish, reef health declines," said Cramer, a postdoctoral researcher at Scripps and lead author of the study.

Algae-eating parrotfish, like other herbivorous reef fish, play an important role in coral reef ecosystems by removing the algae that compete with corals. According to the study, the decline in herbivorous fish such as parrotfish over the last several decades from fishing is considered a main factor in the shift to more algae-dominated reefs in the Caribbean.

The Scripps researchers examined the amount and composition of fish, coral, and urchin fossils in 3 to 5-meter (10 to 33-feet) long sediment cores from three reef sites offshore of Bocas del Toro, Panama to understand the natural state of the reefs before humans began intensive fishing and land clearing, and to assess the role of these activities in recent reef declines. The analysis was aimed at determining if coral growth rates are affected by change in the population levels of parrotfish or urchins that eat algae.

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Most species-rich coral reefs are not necessarily protected

Date: November 22, 2016

Source: Leiden, Universiteit

Coral reefs throughout the world are under threat. After studying the reefs in Malaysia, Zarinah Waheed concluded that there is room for improvement in coral reef conservation.

One-third of the corals of the Great Barrier Reef are dead. This was the sombre conclusion drawn by Australian scientists six months ago. Pollution, shipping and climate change are destroying the world's largest continuous reef, and other coral reefs seem to be facing the same fate.

Home country

PhD candidate Zarinah Waheed studied coral reefs in her home country Malaysia over recent years. She looked specifically at the coral diversity of these reefs and also at the connectivity between the reef locations. She found that the areas with the highest numbers of coral species are not necessarily protected.

94 species

During her research, Waheed examined how many species of three coral families -- Fungiidae, Agariciidae and Euphylliidae -- occur in different reefs spread throughout Malaysia. She made a number of diving trips in the region, together with her co-supervisor and coral expert Dr Bert W. Hoeksema of Naturalis Biodiversity Center in Leiden. Before the diving trips, she first examined all specimens of the target species in the extensive coral collection held by Naturalis.

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Scientists discover hidden world of Hawaii's coral 'twilight zone'

20-year study of deep reefs finds algae meadows and swaths of continuous coral with the highest rate of species found nowhere else in Earth’s seas

Jessica Aldred

Tuesday 4 October 2016 15.39 BST Last modified on Tuesday 4 October 2016 15.40 BST 

The “twilight zone” of Hawaii’s deep coral reefs are home to vast algae meadows and support the highest rates of species found nowhere else in Earth’s seas, scientists have discovered.

A 20-year study of the archipelago’s poorly-explored mesophotic – middle light – coral zone also found the deep-reef habitats are home to many unique and distinct species not found on shallow reefs with vast areas of 100% coral cover.

While much is known about shallow, tropical coral habitats, the richness, diversity and ecological importance of these deep sea ecosystems, found at depths of 30-150 metres, has only recently been understood. 

In one of the largest and most comprehensive studies of its kind, published on Tuesday in the journal PeerJ, the entire 2,590km Hawaiian archipelago was covered over two decades using a combination of submersibles, remote-operated vehicles, drop cameras, data recorders and advanced diving techniques. 

A major focus of the study was to document extensive areas of 100% coral cover at depths of 90m (300 feet) or more off the islands of Maui and Kauai. Vast expanses of continuous coral cover were found extending for tens of square kilometres, dominated by stony, reef-building corals in the genus Leptoseris, a plate-like coral adapted for deepwater environments.

“These are some of the most extensive and densely populated coral reefs in Hawaii,” said Anthony Montgomery, a US Fish and Wildlife biologist and co-author of the study. “It’s amazing to find such rich coral communities down so deep.”

The study identified more than 70 species of macroalgae in extensive meadows that support unique communities of fish and invertebrates. Both corals and algae depend on sunlight for photosynthesis, and the study attributed the existence of many of the deep reef habitats to exceptionally clear water.

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