Reduced Pollution Can Prevent Coral Bleaching When Things Get Hot

Reduced Pollution Can Prevent Coral Bleaching When Things Get Hot

Reducing nutrient pollution can help prevent coral from bleaching during moderate heatwaves, researchers report.

The results offer new strategies for managing these highly threatened yet important ecosystems.

Reef-building corals host beneficial algae within their tissues. In exchange for protection and nitrogen, the algae provide the coral with sugars. All is well until the water gets too warm.

At higher temperatures, the algae’s photosynthesis goes into overdrive, and the chemical balance between the coral and the algae breaks down. At a certain point, the coral ejects its tenant in a process known as bleaching.

Coral can survive for a time without their algae, so recovery is possible if conditions return to normal quickly. But in the absence of its partner the coral will eventually die, and the worse the bleaching is, the more likely that is to happen.

Experiments in the lab, as well as a few small field studies, began to suggest to researchers that nitrogen pollution, such as from fertilizer and sewage runoff, could exacerbate bleaching. Excess nitrogen in the water can short-circuit the beneficial partnership between corals and the algae. However, until now, it was not known if nutrient effects on bleaching occurred in many corals over large areas.

Nitrogen pollution and coral bleaching

The researchers decided to investigate the effects of nitrogen on coral bleaching—on the scale of an entire island—as part of their long-term ecological research project on the island of Moorea in French Polynesia.

The team surveyed more than 10,000 corals around Moorea during a moderate heatwave in 2016. They studied individual coral colonies in different habitats to capture the variability at a high resolution across the island as a whole. Since nitrogen concentrations naturally fluctuate in seawater, the researchers took samples from Turbinaria ornata, a large alga common on the reefs around Moorea. This provided a record of the nitrogen available to corals in the months leading up to the heatwave.

“These relationships are very complex,” says Mary Donovan, a postdoctoral researcher at the Marine Science Institute at the University of California, Santa Barbara, and lead author of the paper in the Proceedings of the National Academy of Sciences. “So, studying them at spatial and temporal scales that match those happening in nature is critical to revealing these really important interactions.”

The team found that high levels of nitrogen pollution lowered the temperature at which coral began to bleach. It also increased the severity of bleaching.

“It basically doubles how severe the bleaching is,” says Russ Schmitt, a professor in the ecology, evolution, and marine biology (EEMB) department. Coral bleached at extreme temperatures regardless of how much nitrogen was in the system, but even a little excess nitrogen could tip the scale toward severe bleaching under moderate heat conditions.

The researchers looked at the two most common types of branching coral in Moorea. They expected them to respond differently to nutrient pollution, since one is more sensitive to temperature stress than the other. However, both types of corals showed identical responses. This suggested that the strong effect nitrogen pollution has on coral at temperatures normally below levels that trigger bleaching may apply broadly to many coral species.

What’s more, a related study by coauthor Mallory Rice, an EEMB doctoral student, showed that bio-erosion on coral reefs increased in tandem with nitrogen pollution. The researchers looked at 10 years’ worth of data from Moorea on animals that erode coral skeletons. They found that boring invertebrates were more numerous, and coral-eating parrotfish more destructive, when nitrogen pollution was high. This result appears in the journal Coral Reefs.

The ‘defining challenge’ for coral reefs

Climate change has increased the strength and frequency of marine heatwaves, which has increased the severity of bleaching, according to the researchers. Coral reefs are at a tipping point, they explain, so every strategy available to encourage reef health and resilience needs to be explored.

“This study shows that it is possible to take some local actions such as reducing nutrient pollution to give reefs a chance, at least in the near term,” says coauthor Sally Holbrook, also a professor in EEMB.

The researchers plan to continue investigating how the effect of nutrient pollution on bleaching translates into coral mortality. The team conducted a similar survey in 2019, a year that saw some of the highest water temperatures on record around the island of Moorea. Their findings should offer a better account of longer-term effects nutrient pollution has on coral reef ecosystems.

“Marine heatwaves and coral bleaching are the defining challenge facing coral reefs in the 21st century,” says coauthor Deron Burkepile, a professor in EEMB.

“Managing CO2 emissions requires global action, so as ecologists and conservationists, we’re are also looking for levers we can pull at the local scale to help coral reef ecosystems withstand these global stressors while we also take action to address climate change.”

Original Study

Related Books

Climate Adaptation Finance and Investment in California

by Jesse M. Keenan
0367026074This book serves as a guide for local governments and private enterprises as they navigate the unchartered waters of investing in climate change adaptation and resilience. This book serves not only as a resource guide for identifying potential funding sources but also as a roadmap for asset management and public finance processes. It highlights practical synergies between funding mechanisms, as well as the conflicts that may arise between varying interests and strategies. While the main focus of this work is on the State of California, this book offers broader insights for how states, local governments and private enterprises can take those critical first steps in investing in society’s collective adaptation to climate change. Available On Amazon

Nature-Based Solutions to Climate Change Adaptation in Urban Areas: Linkages between Science, Policy and Practice

by Nadja Kabisch, Horst Korn, Jutta Stadler, Aletta Bonn
3030104176
This open access book brings together research findings and experiences from science, policy and practice to highlight and debate the importance of nature-based solutions to climate change adaptation in urban areas. Emphasis is given to the potential of nature-based approaches to create multiple-benefits for society.

The expert contributions present recommendations for creating synergies between ongoing policy processes, scientific programmes and practical implementation of climate change and nature conservation measures in global urban areas. Available On Amazon

A Critical Approach to Climate Change Adaptation: Discourses, Policies and Practices

by Silja Klepp, Libertad Chavez-Rodriguez
9781138056299This edited volume brings together critical research on climate change adaptation discourses, policies, and practices from a multi-disciplinary perspective. Drawing on examples from countries including Colombia, Mexico, Canada, Germany, Russia, Tanzania, Indonesia, and the Pacific Islands, the chapters describe how adaptation measures are interpreted, transformed, and implemented at grassroots level and how these measures are changing or interfering with power relations, legal pluralismm and local (ecological) knowledge. As a whole, the book challenges established perspectives of climate change adaptation by taking into account issues of cultural diversity, environmental justicem and human rights, as well as feminist or intersectional approaches. This innovative approach allows for analyses of the new configurations of knowledge and power that are evolving in the name of climate change adaptation. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration

LATEST VIDEOS

The Great Climate Migration Has Begun
The Great Climate Migration Has Begun
by Super User
The climate crisis is forcing thousands around the world to flee as their homes become increasingly uninhabitable.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
by Toby Tyrrell
It took evolution 3 or 4 billion years to produce Homo sapiens. If the climate had completely failed just once in that…
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
by Brice Rea
The end of the last ice age, around 12,000 years ago, was characterised by a final cold phase called the Younger Dryas.…
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
by Frank Wesselingh and Matteo Lattuada
Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a…
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
by Richard Ernst
We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of…
Five Climate Disbeliefs: A Crash Course In Climate Misinformation
The Five Climate Disbeliefs: A Crash Course In Climate Misinformation
by John Cook
This video is a crash course in climate misinformation, summarizing the key arguments used to cast doubt on the reality…
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
by Julie Brigham-Grette and Steve Petsch
Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44…

LATEST ARTICLES

green energy2 3
Four Green Hydrogen Opportunities for the Midwest
by Christian Tae
To avert a climate crisis, the Midwest, like the rest of the country, will need to fully decarbonize its economy by…
ug83qrfw
Major Barrier to Demand Response Needs to End
by John Moore, On Earth
If federal regulators do the right thing, electricity customers across the Midwest may soon be able to earn money while…
trees to plant for climate2
Plant These Trees To Improve City Life
by Mike Williams-Rice
A new study establishes live oaks and American sycamores as champions among 17 “super trees” that will help make cities…
north sea sea bed
Why We Must Understand Seabed Geology To Harness The Winds
by Natasha Barlow, Associate Professor of Quaternary Environmental Change, University of Leeds
For any country blessed with easy access to the shallow and windy North Sea, offshore wind will be key to meeting net…
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
by Bart Johnson, Professor of Landscape Architecture, University of Oregon
A wildfire burning in hot, dry mountain forest swept through the Gold Rush town of Greenville, California, on Aug. 4,…
China Can Meet Energy and Climate Goals Capping Coal Power
China Can Meet Energy and Climate Goals Capping Coal Power
by Alvin Lin
At the Leader’s Climate Summit in April, Xi Jinping pledged that China will “strictly control coal-fired power…
Blue water surrounded by dead white grass
Map tracks 30 years of extreme snowmelt across US
by Mikayla Mace-Arizona
A new map of extreme snowmelt events over the last 30 years clarifies the processes that drive rapid melting.
A plane drops red fire retardant on to a forest fire as firefighters parked along a road look up into the orange sky
Model predicts 10-year burst of wildfire, then gradual decline
by Hannah Hickey-U. Washington
A look at the long-term future of wildfires predicts an initial roughly decade-long burst of wildfire activity,…

 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities

InnerSelf.comClimateImpactNews.com | InnerPower.net
MightyNatural.com | WholisticPolitics.com | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.