Indo-Pacific corals are home to various species of fish in Palau, Micronesia. sifish / E+ / Getty Images
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As the climate crisis causes an increase in global temperatures and other changes in our environment, corals around the world have been affected. Corals in the Atlantic Ocean were among those that saw steep declines, while those in the Indian and Pacific Oceans fared better.
in a new studyan international team of researchers led by Pennsylvania State University (Penn State) described five new algae species of the genus symbiodiniacean Cladocopium which have a symbiotic relationship with corals. They found that algal associations with Indo-Pacific corals may be more flexible and resilient to warmer temperatures. ocean temperatures than those with Atlantic Ocean corals.
“The existence of widespread species that can withstand diverse or variable environments (is) important for ecological and genetic research and conservation. These ‘ecological generalists’ are more likely to have key adaptations that allow them to better tolerate the physiological challenges of a climate change“, wrote the authors of the study.
The study “Formal recognition of host-generalist species of dinoflagellates (CladocopiumSymbiodiniaceae) mutualistic with the corals of the Indo-Pacific reefs”, was published in the Journal of Phycology.
Coral reefs are made up of calcium carbonate produced by colonies of coral animals with concentrated populations of algae living in their tissues. Researchers have referred to this photosynthetic algae in the family Symbiodiniaceae as “symbionts,” a Penn State Press release said.
When environmental conditions such as warming ocean temperatures cause the delicate relationship between coral animals and algae to break, it can lead to coral bleaching. Depending on the duration and intensity of stressful ocean conditions, corals can recover from a bleaching event, but it can also lead to colony death.
“Coral bleaching not only affects corals themselves, but entire ecosystems of organisms – from invertebrates, like sea urchins and lobsters, to vertebrates, like fish And sea turtlessaid Todd LaJeunesse, a biology professor at Penn State, in the press release. “It is important to study the biology of corals and their symbionts in order to be able to predict how they will react to future environmental changes, in particular the warming of the oceans.”
LaJeunesse pointed out that not all corals and symbionts have the same response to warming oceans. This is due to the variety of species, each with its own set of characteristics. LaJeunesse said it’s only recently that people have begun to appreciate the diversity of symbiont species and the important role they play in coral resilience.
“Scientists have previously grouped all symbionts into a few large groups,” LaJeunesse said in the press release. “My lab’s work over the past few years has been to describe individual species of symbionts so we know what we’re dealing with. Without this information, you really cannot adequately study coral ecology, physiology, and biogeography.
In their research, the team of scientists found that some species of symbionts are specialists and can only relate to one or a few species of coral, which act as their hosts. Others are generalists and may have many coral species as hosts.
The research team found that Indo-Pacific corals have symbiotic relationships with generalists, while some of the other corals – particularly those in the Caribbean — associate with specialists. Because Caribbean corals depend on fewer symbiont species, they may be more vulnerable to environmental change than those in the Indo-Pacific.
LaJeunesse said that since the symbiont species described by the researchers are critical to so many coral species and coral reef ecosystems spanning huge geographic areas, they “could come to dominate coral communities as Earth’s oceans are warming and more sensitive symbionts are disappearing.”
During their study, the research team collected coral samples from reefs in Thailand, the Phoenix Islands, Palau, New Caledonia, Zanzibar in Tanzania and AustraliaIt is Great Barrier Reef. They then extracted the symbionts and identified five species that have the ability to associate with many species of coral hosts by sequencing their DNA.
“It’s hard to communicate about things that we don’t know about, or even have a name for,” Caleb Butler, a graduate student in biology at Penn State and the paper’s first author, said in the press release. . “When we formally describe a species, we give those organisms a name, helping to build an identity that we can talk about and allowing us to link past studies to future research. The organisms we have described are widespread and, as as the oceans warm, these thermally tolerant generalists are likely to spread to new coral communities.Recognizing these distinct species allows for informed research into their ecology, and then the ability to accurately communicate the implications of our findings.
Matthew Nitschke, a researcher at the Australian Institute of Marine Science, said genus symbionts Cladocopium are particularly rich in biodiversity, but few have been successfully cultivated.
“One of the species described by the team, C. proliferum, can be cultured in a test tube, allowing significant progress in understanding the mechanisms underlying coral-algae symbiosis, and it has become a model species for such research in Australia.Our Australian team, led by Professor Madeleine van Oppen, is currently using cultures of C. proliferum in reef restoration research and development, with a focus on how which these algal symbionts contribute to the heat tolerance of corals,” Nitschke said in the press release.