coastal ecosystems

The World’s Largest Harmful Algal Bloom | Earth Wise

July 1, 2021 By EarthWise Leave a Comment

Brown sargassum seaweed floats in surface water in a bloom that stretches all the way from West Africa to the Gulf of Mexico. Sargassum provides habitat for turtles, crabs, fish, and birds.

The stuff carpets beaches along the tropical Atlantic, the Caribbean Sea, the Gulf of Mexico, and the east coast of Florida disrupting tourism. Florida’s Miami-Dade County alone spends $45 million a year cleaning up sargassum. Annual Caribbean clean-up is in excess of $120 million.

A study by Florida Atlantic University has discovered dramatic changes in the chemistry and composition of sargassum which has transformed the so-called Great Atlantic Sargassum Belt into a toxic dead zone.

The findings of the study suggest that increased nitrogen availability from both natural and human-generated sources, including sewage, is supporting blooms of sargassum and turning a critical marine nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health.

The study found that today’s sargassum tissues compared with those of the 1980s have 35% more nitrogen content and 42% less phosphorus. Much of the nitrogen increase is a result of agricultural and industrial runoff from the Congo, Amazon, and Mississippi Rivers.

The fact that the bloom itself has expanded so tremendously was already suspected to be the result of significant changes in the ocean’s chemistry. Given the negative effect that the Great Atlantic Sargassum Belt is having on the coastal communities, additional research is essential to guide mitigation and adaptation efforts.

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Sargassum now world’s largest harmful algal bloom due to nitrogen

Photo, posted June 5, 2016, courtesy of J Brew via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Coastal Ecosystems | Earth Wise

February 1, 2021 By EarthWise Leave a Comment

Research published by CSIRO, Australia’s national science agency, examined the positive effects of restoration efforts for coastal ecosystems in terms of biodiversity, local economies, and human wellbeing.

Coastal ecosystems include saltmarshes, mangroves, seagrasses, oyster reefs, kelp beds, and coral reefs. All of these have suffered declines of up to 85% over recent decades. The research identified a number of successful coastal and marine restoration projects in recent years that indicate the likelihood that such efforts could be expanded by as much as a factor of ten to support human health and wellbeing, boost the adaptation response to climate change, and generate jobs.

Some of the successful efforts identified included projects in the Great Barrier Reef to harvest coral larvae to boost large-scale coral restoration efforts. Simple changes to how saltmarshes are planted have resulted in doubled survivorship and biomass. In the U.S., the propagation of seagrass seeds has resulted in seagrass meadows recovering in areas where they had been lost decades ago. In Indonesia, recovery of reefs impacted by blast fishing has been achieved by placing rocks or other hard structures underwater to help with coral colonization.

Investing in coral restoration creates jobs and can be used as a strategy to boost economic recovery and coastal marine health. Restoration of marine habitats like kelp forests and oyster reefs has improved commercial and recreational fishing.

The United Nations has recognized the importance of coastal restoration and has declared the Decade on Ecosystem Restoration to start from 2021.

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Scientists shine light on ‘bright spots’ to restore coastal ecosystems

Photo, posted November 29, 2012, courtesy of Robert Linsdell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coastal Plants And Climate Change | Earth Wise

March 18, 2020 By EarthWise Leave a Comment

Rising sea levels and the increased frequency and intensity of extreme weather events are leaving observable effects on beaches, cliffs, and coastal infrastructures all around the world. But a new study suggests that the impact of climate change on coastal plant communities needs more attention.

According to research recently published in the journal Annals of Botany, coastal plants are a critical element of global sea defense. But coastal plants are increasingly under threat from flooding, erosion, and other human-induced effects of climate change. Habitats like salt marshes, mangrove forests, sand dunes, and kelp beds make important contributions to coastal protection.

The research was led by scientists from the University of Plymouth, in conjunction with researchers at Utrecht University and Manchester Metropolitan University.

The study follows a recent assessment by the Intergovernmental Panel on Climate Change, which found that anthropogenic climate change poses a severe threat to estuaries and coastal ecosystems.

Conservative estimates of the capital investments needed to combat rising seas and intensifying storms run into the hundreds of billions of dollars in the coming decades. However, coastal vegetation could offer a dynamic, natural, and relatively low-cost defense strategy at a fraction of the cost when compared with the cost of so-called hard defenses like concrete walls and barriers.

According to the research team, identifying the key species and habitats for coastal defense and how coasts can be protected and promoted is critical. More long-term monitoring is also needed in order to better understand and predict where and how storms and other effects of climate change will impact coastal ecosystems.

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The gathering storm: optimizing management of coastal ecosystems in the face of a climate-driven threat

Losing coastal plant communities to climate change will weaken sea defences

Photo, posted September 14, 2018, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.