Small fish crucial for coral reef biodiversity


This 2018 video is called The Coral Reef: 10 Hours of Relaxing Oceanscapes | BBC Earth.

From the Smithsonian Institution in the USA:

Live fast, die young: Study shows tiny fishes fuel coral reefs

May 23, 2019

Scientists have long sought to understand how coral reefs support such an abundance of fish life despite their location in nutrient-poor waters. According to a new study published May 23 in the journal Science, an unlikely group fuels these communities: tiny, mostly bottom-dwelling creatures called “cryptobenthic” reef fishes.

The study shows that these fishes perform a critical role on coral reefs, supplying almost 60% of consumed fish food by constantly replenishing their populations in a rapid cycle of life and death.

“Scientists have puzzled over coral reefs for centuries, wondering how such productive, diverse ecosystems survive in what is essentially a marine desert,” said lead author Simon Brandl, formerly with the Smithsonian’s Tennenbaum Marine Observatories Network and currently a postdoctoral research fellow with Simon Fraser University. “It’s remarkable to find that these tiny, almost universally overlooked fishes actually serve as the cornerstone of coral-reef fish communities.”

Cryptobenthic reef fishes, such as gobies, blennies or cardinalfishes, are the smallest of all marine vertebrates. Although they vary in size, the tiniest cryptobenthics will never reach 1 inch and weigh almost nothing. Other coral-reef dwellers eat these fishes in large quantities, most within the first few weeks of their existence.

Instead of disappearing, however, cryptobenthic fish populations somehow flourish in the face of constant predation. The researchers solved this paradox by studying the larvae of reef fishes. While the larvae of most fish species disperse into the open ocean, where only a few survive, cryptobenthics behave differently. Brandl and his team found that most cryptobenthic larvae appear to remain close to their parents’ reefs, yielding many more survivors among their babies. These larvae then rapidly replace cryptobenthic adults eaten on the reef, sustaining the growth of larger reef fishes.

“We found that cryptobenthic fish larvae absolutely dominate the larval-fish communities near reefs, which provides a continuous stream of new generations of tiny fish as a food source for other reef creatures,” said Carole Baldwin, co-author on the study and curator of fishes at the Smithsonian’s National Museum of Natural History. “It’s incredible that these fishes contribute so much to coral reefs. They’re so small that historically we haven’t recognized their enormous significance.”

Scientists from Australia, Canada, France and the United States contributed to this research. The team studied cryptobenthics in Belize, French Polynesia and Australia, combed decades of data on coral-reef fish larvae and developed a population model to better understand how cryptobenthics contribute to the diet of coral-reef dwellers.

The study began in 2015, when Brandl was a postdoctoral fellow at the Smithsonian’s Marine Global Earth Observatory (MarineGEO), but these tiny fishes are more relevant today than ever. As coral reefs undergo dramatic declines, their fish communities — and the people who depend on them — may be in jeopardy. The researchers hope that the vast diversity of cryptobenthics and their unique way of life can make them a resilient foundation for coral reefs.

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Red Sea coral reef wildlife, video


This video says about itself:

The Incredible Sea Life of the Red Sea Coral Reef | BBC Earth

Simon Reeve dives into the Red Sea to get close to its incredible fish and marine wildlife.

Scientists offer a new way to accurately map coral reefs using a combination of Earth-orbiting satellites and field observations. This first-ever global coral reef atlas contains maps of over 65,000 square kilometers (25,097 square miles) of coral reefs and surrounding habitats: here.

New deep sea animal discoveries off Cocos Island


This 2015 German language video is called Cocos Island (Isla del Coco) “Mountain of sharks“.

From the Schmidt Ocean Institute:

New deep sea animal discoveries warrant expanded protections in Costa Rican waters

February 11, 2019

Summary: Scientists surveyed deep-sea seamounts outside Isla del Coco UNESCO World Heritage site revealing coral communities with surprising diversity.

A three week expedition off the coast of Costa Rica has just expanded our knowledge of deep sea ecosystems in the region. Led by Dr. Erik Cordes, Temple University, the scientists aboard research vessel Falkor surveyed the continental margin for seamounts and natural gas seeps, where specialized biological communities are found. The seamounts extending from the mainland to the Cocos Island National Park provide an important corridor for the animals occupying the area.

Investigating these systems on all biological size scales, the team focused on relationships between species, from microbes to fauna like fish and corals. At least four new species of deep-sea corals and six other animals that are new to science were found. This expedition represents the first time that seven of the seamounts in the area have been surveyed. The survey results, including description of the coral communities that they host, will support the effort to create a new marine protected area around these seamounts ensuring that they are not impacted by fishing or potential mining activities.

“This research will support Costa Rica’s efforts to conserve these important habitats by providing a baseline of the incredible species and ecosystems found in the deeper areas that don’t always attract the attention that they deserve,” said Schmidt Ocean Institute Cofounder Wendy Schmidt. “One of the most important things we can do now is understand how these communities work, so if there are changes in the future we can measure human impact.”

Even in deep waters, humans pose a threat to these fragile ecosystems. During one of the 19 remotely operated vehicle dives the accumulation of trash at 3,600 meters depth (more than 2 miles) was discovered. Threats to the deep sea already exist, including fishing and energy industries that are moving into deeper water, and the persistent risk of climate change. There are rare organisms and spectacular habitats on the seamounts; it is important to preserve them before they are impacted by these and other threats.

One unique discovery during the expedition was the consistent zonation of seamounts related to the amount of oxygen present. Decreasing oxygen in the ocean due to a warming planet may eventually affect these zones dominated by corals, sea fans, sponges, brittle stars and small oysters. “Every dive continues to amaze us,” said Cordes. “We discovered species of reef-building stony corals at over 800 meters depth on two different seamounts. The closest records of this species are from the deep waters around the Galapagos Islands. The deep sea is the largest habitat on Earth. Understanding how that habitat functions will help us to understand how the planet as a whole works.”

How damselfish live together


This 2012 video from Hawaii says about itself:

Two different species, a female Indo-Pacific Sergeant (Abudefduf vaigiensis) and a male Hawaiian Sergeant (Abudefduf abdominalis) spawning at Reef’s End, Molokini.

From the University of California – Santa Barbara in the USA:

A close look at the specific feeding habits of territorial damselfish reveals strategies for coexistence without competition

January 22, 2019

In the animal kingdom, food access is among the biggest drivers of habitat preference. It influences, among other things, how animals interact, where they roam and the amount of energy they expend to maintain their access to food. But how do different members of ecologically similar species manage to live close to each other?

This question was on the mind of UC Santa Barbara postdoctoral scholar Jacob Eurich as he studied territorial damselfish in Kimbe Bay, Papua New Guinea. Located within the Coral Triangle of the Indo-Pacific region, which is recognized for the greatest richness of marine life in the world, the coral reefs in the area are home to a variety of damselfish. This includes seven species that inhabit their own particular spaces, in some cases within mere meters of one another.

“Previously, scientists thought that all territorial damselfishes were herbivorous, farm algae and basically do the same thing ecologically on reefs,” explained Eurich, who conducted this research while at James Cook University in Australia. “Damselfish” is a very broad category, he added, with members such as clownfishes and the Californian garibaldi in the same family. The species of damselfish that are the subject of this research are the tropical territorial types, known to cultivate and protect algal beds on coral reefs.

In research published in the science journal Marine Biology, Eurich sought to understand how neighboring communities of these fish — which live in an ecological community of intense competition for resources — manage to thrive.

“We set out to understand how they live so close to one another without directly competing, and why,” he said.

The answer came after an in-depth look at the fishes’ diets using stable isotope analysis, which detects certain types of elements in their muscle tissues and links them to potential food items.

“It is based on the principle, ‘you are what you eat'”, Eurich explained. Rather than getting a snapshot of an animal’s diet by looking at its stomach contents, stable isotope analysis provides a long-term picture of what the animal consumes on a regular basis because the food is incorporated into the animal’s tissue.

The result? These farming fish are not exclusively farmers, nor are they exclusively vegetarian.

“The analysis proved that in fact not all territorial damselfish are herbivorous and we found evidence of planktivory, quite the opposite feeding regime,” Eurich said. Further, he added, these species had previously only been known to eat things off the reef. “We found evidence of two species foraging for food that drift by in the water column.”

These findings are significant on several levels. They indicate that certain broad ecological categorizations — such as the classification of territorial damselfish as herbivores — may not adequately serve some species, or the scientists and conservationists that study them.

“I think it is a cautionary flag to scientists in all ecological-related fields to be careful when generalizing groups of similar species,” Eurich said. “Each species is likely partitioning a resource and if it doesn’t look like they are, there is a chance a technology with a finer resolution is needed to detect differences.”

Also, the study demonstrates an example of adaptation in areas of high competition for resources.

“An animal can’t spend all of their time and energy fighting a neighbor,” Eurich said. “In this study we showed some of the species switched diets to reduce competition.”

As climate change and subsequent ocean acidification and coral bleaching continue to affect life on the reef, territorial damselfish will remain one species to watch as they adapt to shifting conditions. So far they seem to be successful, in fact they are regarded “winners” of coral bleaching.

“Where most species die off due to the coral habitat loss, these algae-farmers actually increase in abundance,” said Eurich, who is now based in the McCauley Lab at UC Santa Barbara’s Marine Science Institute. “The study here shows how many of these species may coexist in the future. I think it is important to look at the competition and coexistence of species that may be the most abundant on future reefs.”

Coral species need other corals


This 2012 video says about itself:

Coral Gardening | South Pacific | BBC Earth

Conservationists work to garden coral and help preserve these unique life forms.

From the Georgia Institute of Technology in the USA:

When coral species vanish, their absence can imperil surviving corals

January 23, 2019

Summary: As coral species die off, they may be leaving a death spiral in their wake: Their absence could be sapping life from the corals that survive. In a new study, when isolated from other species, corals got weak, died off or grew in fragile structures. The study has shown it is possible to quantify positive effects of coral biodiversity and negative effects of its absence.

Waves of annihilation have beaten coral reefs down to a fraction of what they were 40 years ago, and what’s left may be facing creeping death: The effective extinction of many coral species may be weakening reef systems thus siphoning life out of the corals that remain.

In the shallows off Fiji’s Pacific shores, two marine researchers from the Georgia Institute of Technology for a new study assembled groups of corals that were all of the same species, i.e. groups without species diversity. When Cody Clements snorkeled down for the first time to check on them, his eyes instantly told him what his data would later reveal.

“One of the species had entire plots that got wiped out, and they were overgrown with algae,” Clements said. “Rows of corals had tissue that was brown — that was dead tissue. Other tissue had turned white and was in the process of dying.”

36 ghastly plots

Clements, a postdoctoral researcher and the study’s first author, also assembled groups of corals with a mixture of species, i.e. biodiverse groups, for comparison. In total, there were 36 single-species plots, or monocultures. Twelve additional plots contained polycultures that mixed three species.

By the end of the 16-month experiment, monocultures had faired obviously worse. And the study had shown via the measurably healthier growth in polycultures that science can begin to quantify biodiversity’s contribution to coral survival as well as the effects of biodiversity’s disappearance.

“This was a starter experiment to see if we would get an initial result, and we did,” said principal investigator Mary Hay, a Regents Professor and Harry and Linda Teasley Chair in Georgia Tech’s School of Biological Sciences. “So much reef death over the years has reduced coral species variety and made reefs more homogenous, but science still doesn’t understand enough about how coral biodiversity helps reefs survive. We want to know more.”

The results of the study appear in the February issue of the journal Nature Ecology and Evolution and were made available online on January 7, 2018. The research was funded by the National Science Foundation, by the National Institutes of Health’s Fogarty International Center, and by the Teasley Endowment.

The study’s insights could aid ecologists restocking crumbling reefs with corals — which are animals. Past replenishing efforts have often deployed patches of single species that have had trouble taking hold, and the researchers believe the study should encourage replanting using biodiverse patches.

40 years’ decimation

The decimation of corals Hay has witnessed in over four decades of undersea research underscores this study’s importance.

“It’s shocking how quickly the Caribbean reefs crashed. In the 1970s and early 1980s, reefs consisted of about 60 percent live coral cover,” Hay said. “Coral cover declined dramatically through the 1990s and has remained low. It’s now at about 10 percent throughout the Caribbean.”

“You used to find living diverse reefs with structurally complex coral stands the size of city blocks. Now, most Caribbean reefs look more like parking lots with a few sparse corals scattered around.”

84 percent loss

The fact that the decimation in the Pacific is less grim is bitter irony. About half of living coral cover disappeared there between the early 1980s and early 2000s with declines accelerating since.

“From 1992 to 2010, the Great Barrier Reef, which is arguably the best-managed reef system on Earth, lost 84 percent,” Clements said. “All of this doesn’t include the latest bleaching events reported so widely in the media, and they killed huge swaths of reef in the Pacific.”

The 2016 bleaching event also sacked reefs off of Fiji where the researchers ran their experiment. The coral deaths have been associated with extended periods of ocean heating, which have become much more common in recent decades.

10 times more species

Still, there’s hope. Pacific reefs support ten times as many coral species as Caribbean reefs, and Clements’ and Hay’s new study suggests that this higher biodiversity may help make these reefs more robust than the Caribbean reefs. There, many species have joined the endangered list, or are “functionally extinct,” still present but in traces too small to have ecological impact.

The Caribbean’s coral collapse may have been a warning shot on the dangers of species loss. Some coral species protect others from getting eaten or infected, for example.

“A handful of species may be critical for the survival of many others, and we don’t yet know well enough which are most critical. If key species disappear, the consequences could be enormous,” said Hay, who believes he may have already witnessed this in the Caribbean. “The decline of key species may drive the decline of others and potentially create a death spiral.”

864 abrasive animals

Off Fiji’s shores, Clements transported by kayak, one by one, 48 concrete tables he had built on land. He dove them into place and mounted on top of them 864 jaggy corals in planters he had fashioned from the tops of plastic soda bottles.

“I scratched a lot of skin off of my fingers screwing those corals onto the tables,” he said, laughing at the memory. “I drank enough saltwater through my snorkel doing it, too.”

Clements laid out 18 corals on each tabletop: Three groups of monocultures filled 36 tables (12 with species A, 12 with species B, 12 with species C). The remaining 12 tabletops held polycultures with balanced A-B-C mixtures. He collected data four months into the experiment and at 16 months.

The polycultures all looked great. Only one monoculture species, Acropora millepora, had nice growth at the 16-month mark, but that species is more susceptible to disease, bleaching, predators, and storms. It may have sprinted ahead in growth in the experiment, but long-term it would probably need the help of other species to cope with its own fragility.

“Corals and humans both may do well on their own in good times,” Hay said. “But when disaster strikes, friends may become essential.”

Corals lurking in deeper, darker waters could one day help to replenish shallow water reefs under threat from ocean warming and bleaching events, according to researchers: here.

What factors govern algae’s success as “tenants” of their coral hosts both under optimal conditions and when oceanic temperatures rise? A Victoria University of Wellington-led team of experts that includes Carnegie’s Arthur Grossman investigates this question: here.

Bonaire coral spawning, video


This 2011 video says about itself:

How does an animal like coral that lives attached to the bottom (and can’t move around) create new colonies far away? Jonathan spends a week in Bonaire studying coral spawning. He learns how these animals release eggs into the water at the right time of the year to create new coral colonies. But they only do it at night, at certain times of the year. Jonathan’s film expedition requires careful timing.

A new study has found that a common coral species might have evolved unique immune strategies to cope with environmental change: here.

Corals know how to attract good company. New research finds that corals emit an enticing fluorescent green light that attracts the mobile microalgae, known as Symbiodinium, that are critical to the establishment of a healthy partnership: here.

New coral species discovery in Panama


This 2011 video is called Coral reefs near Bocas Del Toro, Panama.

From the Smithsonian Tropical Research Institute:

New soft coral species discovered in Panama

September 14, 2018

Summary: Another new coral found in Panama’s Coiba National Park, a UNESCO National Heritage Site, the location of the Smithsonian’s newest research site.

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the only other species in the genus in the eastern Pacific, T. variabilis.

T. dalioi is named for Ray Dalio, a supporter of marine exploration. Its name is intended to recognize Dalio’s valuable contributions to marine research and public outreach. Hannibal Bank, part of the Coiba National Park and a UNESCO World Heritage Site, is a coastal seamount and a biodiversity hot spot that has only been explored recently. “After just two expeditions using submersibles down to 300 meters, we have identified 17 species of octocorals for the Hannibal Bank, including the discovery and description of three new species”, said Hector M. Guzman, marine ecologist at STRI and one of the authors of the study.

Light-dependent coral and algae, as well as other life-forms found in low-light environments, live on mesophotic reefs: meso means middle and photic means light. These reefs, such as the one where T. dalioi was found, are considered fragile habitats with a high diversity of corals, algae and sponges. They are also generally neglected in most environmental and conservation policies because they are difficult to reach. Hannibal Bank is one of the spots requiring more attention for its protection. “The present study should provide the basis for further research on the genus and contributes to the diversity and distribution knowledge of octocorals from the mesophotic zone in the eastern Pacific Ocean”, said Odalisca Breedy, marine biologist at CIMAR and one of the authors of the study.

“Medical researchers have identified therapeutic benefits derived from both soft and hard corals such as anti-inflammatory and anti-cancer properties, bone repair and neurological benefits”, said Guzman. “But our ability to contribute to the understanding of soft corals and their habitats, depends not only on steady funding for the use of submersibles, but also on our continued ability to obtain permission to work in Coiba National Park.”