Some corals may survive climate change without paying a metabolic price
These resilient corals may dominate reef ecosystems of the future
Peer-Reviewed PublicationIMAGE: RESEARCHERS FOUND THAT CORALS ASSOCIATING WITH THE DURUSDINIUM GLYNNII SYMBIONT (LEFT) ARE MORE RESILIENT TO WARM WATER TEMPERATURES THAN CORALS ASSOCIATING WITH THE CLADOCOPIUM LATUSORUM SYMBIONT (RIGHT). view more
CREDIT: MATTHEW ASCHAFFENBURG
UNIVERSITY PARK, Pa. — If, as the saying goes, ‘nothing in life is free,’ then corals might pay a price for being resilient to climate change. Indeed, the prevailing belief among scientists has been that corals must suffer reduced growth or other tradeoffs when they partner with symbiotic algae that help them tolerate warmer water. Yet, new research led by Penn State demonstrates that certain corals can have their cake and eat it too, and as a result, these coral-symbiont partnerships may come to dominate reef ecosystems in a climate-changed future.
“Our findings refute the general perception that reef-building corals with thermally tolerant algal symbionts grow poorly,” said Todd LaJeunesse, professor of biology, Penn State. “Instead, these warm-adapted partnerships better tolerate severe marine heatwaves and are likely to expand ecologically and dominate reef ecosystems in the future. While reefs of the future may not look pretty — with low diversity and greatly diminished ecosystem services — the resilient animals left behind will likely continue to provide food and habitat for other animals, and some reef growth to the ecosystems they’ve created.”
LaJeunesse explained that coral reefs are geologic structures created by coral colonies comprising tiny individual sea-anemone-like polyps whose tissues contain dense populations of photosynthetic algae, called ‘dinoflagellates.’ These dinoflagellates — which researchers call ‘symbionts’ — vary in their ability to tolerate high temperatures. When the ocean gets too warm, many symbiont species die, and their coral hosts die along with them. And when coral reefs collapse, fisheries, tourism and ecosystem services, such as hurricane buffers, are also at risk.
According to LaJeunesse, the first documentation of differences in coral mortality based on the species of symbiont present occurred in the Eastern Pacific Ocean following the 1997-1998 El Niño Southern Oscillation event when water temperatures were 2-4°C warmer than historical average temperatures. Following that event, he said, corals that hosted Durusdinium glynnii symbionts survived, while corals that hosted Cladocopium latusorum symbionts died.
“Clearly,” said Mark Warner, professor of marine science and policy, University of Delaware, “corals that associated with D. glynnii were at an advantage during that extreme heat event, but does hosting these temperature-resistant symbionts come at a cost? Previous research has suggested that the costs of thermal tolerance manifest as reduced nutrient translocation from symbiont to host and significant negative physiological tradeoffs, such as reduced growth and reproductive success. We wanted to know if a similar tradeoff could occur in corals and whether this could affect the fate of coral reef ecosystems.”
Kira Turnham, lead author of the study, which published today (July 19) in Proceedings of the Royal Society B, explained that to investigate possible tradeoffs in thermally tolerant partnerships, the research team compared the growth and reproduction of Pocillopora corals hosting the thermally tolerant D. glynnii symbiont and the more sensitive C. latusorum symbiont.
“These symbioses are common throughout the Indian and Pacific oceans, representing co-evolved and ecologically successful relations,” she said.
Specifically, the team measured skeletal growth, total mass increase and calcification rates — or the rate at which corals produce calcium carbonate, which is a measure of their growth. The team also measured reproductive output and response to thermal stress to assess the functional performance of these partner combinations.
“We found that D. glynnii provided the capacity to endure water temperatures that compromise most coral-dinoflagellate mutualisms without noticeable tradeoffs,” said Turnham. “This partner combination grows and reproduces just as well as the more temperature-sensitive partnership.”
Turnham noted that the differences in performance and function between the two partnerships were apparent only during experimental heating, highlighting the ability of D. glynnii to tolerate higher temperatures and provide heat tolerance to their hosts. The team is also studying similar coral-algal mutualisms involving numerous coral species in the Western Pacific nation of Palau to determine the breadth of these findings.
“This study highlights the contextual importance and incredible biology of coral symbioses,” said Turnham. “By investigating the coevolutionary history of the symbioses, providing a contextual lens and using improved symbiont species recognition, we can make more meaningful predictions about the persistence of corals as oceans continually warm from climate change.”
Other authors on the paper include Matthew Aschaffenburg, University of Delaware; Tye Pettay, University of South Carolina Beaufort; David Paz-García, Centro de Investigaciones Biológicas del Noroeste; Hector Reyes-Bonilla, Universidad Autónoma de Baja California Sur; Jorge Pinzón, University of Texas at Arlington; Ellie Timmins, Penn State; Robin Smith, University of the Virgin Islands; and Michael McGinley, University of Delaware.
The National Science Foundation supported this research.
Corals that associate with D. glynnii (right) are at an advantage during extreme heat events compared to corals that associate with C. latusorum (left).
CREDIT
David A. Paz-García
The researchers studied measured skeletal growth, total mass increase and calcification rates — or the rate at which corals produce calcium carbonate, which is a measure of their growth — in controlled tank environments under different temperature regimes.
CREDIT
Matthew Aschaffenburg
JOURNAL
Proceedings of the Royal Society B Biological Sciences
From nature, a solution to save coral from climate change
Researchers at Istituto Italiano di Tecnologia – IIT and University of Milan-Bicocca have demonstrated the efficacy of a natural substance in protecting coral from the damage caused by climate change.
Peer-Reviewed PublicationIMAGE: STYLOPHORA PISTILLATA CORAL COVERED WITH BIOMATERIAL DURING THERMAL STRESS TESTS view more
CREDIT: IIT/UNIVERSITÀ MILANO-BICOCCA
Genoa (Italy), 19 July 2023 – Researchers at Istituto Italiano di Tecnologia (Italian Institute of Technology - IIT) and Università degli Studi di Milano-Bicocca (University of Milan-Bicocca), in cooperation with Acquario di Genova (Genoa Aquarium) in Italy, have recently published a study in ACS Applied Materials and Interfaces, which demonstrates the efficacy of curcumin, a natural antioxidant substance extracted from turmeric, in reducing coral bleaching, a phenomenon caused primarily by climate change. The research group developed a biodegradable biomaterial to deliver the molecule without causing damage to the surrounding marine environment. Tests conducted at the Genoa Aquarium have shown significant efficacy in preventing coral bleaching.
Coral bleaching is a phenomenon that, in extreme events, causes the death of these organisms with devastating consequences for coral reefs, which are crucial for the global economy, the protection of coastlines from natural disasters, and marine biodiversity. Most corals live in symbiosis with microscopic algae, which are indispensable for their survival and are responsible for their vibrant colours. Due to climate change, sea and ocean temperatures are rising, a condition that disrupts the relationship between these two organisms. When this happens, the coral, which turns white due to the loss of algae, literally risks starvation.
In recent years, as a result of climate change, this condition has affected most of the world’s major coral barrier reefs, including Australia’s Great Barrier Reef. However, to date there are no effective methods of countering this phenomenon and preventing coral bleaching without seriously endangering the survival of these habitats and the exceptional biodiversity associated with them.
Researchers at Istituto Italiano di Tecnologia and the University of Milan-Bicocca, in collaboration with the Genoa Aquarium, have demonstrated the efficacy of a natural molecule, curcumin, in blocking coral bleaching caused by climate change. Curcumin is administered to the coral in a controlled manner by applying a biomaterial based on zein, a protein derived from maize, a system developed by the partners themselves in order to ensure safety for the environment.
During the tests, performed at the Genoa Aquarium, overheating conditions in tropical seas were simulated by raising the water temperature up to 33°C. Under these conditions, all untreated corals were affected by the bleaching phenomenon as would occur in nature, while, on the contrary, all specimens treated with curcumin showed no signs of this tendency, a result that makes this technique effective in reducing the susceptibility of corals to thermal stress. A coral species (Stylophora pistillata) typical of the tropical Indian Ocean, included in the IUCN (International Union for the Conservation of Nature) Red List of endangered species, was used for this study.
“This technology is the subject of a patent application that has been filed, and in fact the next steps of this research will focus on its application in nature and on a large scale,” said Marco Contardi, first author of the study, research affiliate of the Smart Materials group at Istituto Italiano di Tecnologia and researcher in DISAT (Department of Environmental and Earth Sciences) at the University of Milan-Bicocca. “At the same time, we will examine the use of other antioxidant substances of natural origin to block the bleaching process and thus prevent the destruction of coral reefs.”
“The use of new biodegradable and biocompatible materials capable of releasing natural substances that can reduce coral bleaching is something entirely new,” said Simone Montano, researcher at DISAT and deputy director of the MaRHE centre (Marine Research and High Education Centre) at the University of Milan-Bicocca. “I strongly believe that this innovative approach will represent a significant breakthrough in the development of strategies for the recovery of marine ecosystems.”
Stylophora pistillata coral covered with biomaterial during thermal stress tests
CREDIT
IIT/Università Milano-Bicocca
JOURNAL
ACS Applied Materials & Interfaces
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Biodegradable Zein-Based Biocomposite Films for Underwater Delivery of Curcumin Reduce Thermal Stress Effects in Corals
No comments:
Post a Comment