explosion

What happened to the sea stars?

September 11, 2025 By EarthWise Leave a Comment

Billions of sea stars off the Pacific coast of North America from Mexico to Alaska have died from a wasting disease since 2013. This die-off is considered to be the largest ever marine epidemic. Over 90% of the population of sunflower sea stars has succumbed to the disease.

The result has been an explosion in the population of the sea urchins that the sea stars feed on. In turn, the sea urchins have devoured kelp forests that provide habitat for thousands of marine creatures. These kelp forests support a multi-million-dollar economy through fisheries and tourism as well as sequestering carbon dioxide and protecting vulnerable coastlines.

The disease begins with lesions and eventually kills sea stars by seemingly melting their tissues over a period of about two weeks. Sea stars with the disease become contorted and lose their arms.

For years, the definitive cause of the wasting disease has been elusive. But researchers from the University of British Columbia, the Hakai Institute, and the University of Washington have now identified a bacterium that is the disease-causing agent.

A strain of the Vibrio pectenicida bacteria – named FHCF-3 – is responsible. The Vibrio genus of bacteria includes pathogens that infect corals, shellfish, and even humans. Vibrio cholerae is the cause of cholera.

Research is now underway to understand the link between the disease and warming ocean temperatures due to climate change. The hope is that the discovery of the cause of the wasting disease will help guide management and recovery efforts for sea stars and impacted ecosystems.

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‘Disease detectives’ discover cause of sea star wasting disease that wiped out billions of sea stars

Photo, posted April 16, 2011, courtesy of Brian Gratwicke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lots of female turtles

November 3, 2023 By EarthWise Leave a Comment

Green sea turtles were listed under the Endangered Species Act in 1978. Since that time, there have been conservation measures put in place in many locations. One such place is Florida, where restrictions on beachfront development and careful monitoring of turtle nests has helped to get hatchlings safely into the water. A gill net ban in 1995 sharply reduced the number of young turtles killed by fishing gear.

All of this has resulted in what is described as an explosion in turtle populations in Florida. Volunteers monitoring the 2023 nesting season on Florida’s beaches have counted more than 74,000 nests. That beats the previous record – set in 2017 – by an incredible 40%.

Unfortunately, this does not represent a guaranteed great future for the species. Sea turtles are particularly sensitive to the warming climate. The sex of a baby sea turtle is not determined by DNA, but rather by the temperature of the sand in which its egg develops. Cooler temperatures mean more males; warmer ones mean more females.

In recent years, the proportion of male green sea turtles has dwindled substantially. In the past few seasons, between 87 percent and 100 percent of the hatchlings tested in Florida have been female.

In the short term, the skewed sex ratio might be a boon for the species. Lots of females laying lots of eggs means lots of turtles. Sea turtles don’t reach sexual maturity until their twenties or thirties. So, for the next few decades, there are likely to be growing numbers of turtle nests. But down the line, there is going to be a real problem. Where will for all the female turtles find the mates to populate the species in the future?

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Florida Turtle Nests Are Recovering. When They Hatch, Expect Mostly Girls.

Photo, posted October 5, 2011, courtesy of Keenan Adams / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Help For Kelp | Earth Wise

April 10, 2023 By EarthWise Leave a Comment

The warming of the oceans has been causing the decimation of kelp forests. The thick canopies covering coastal ocean regions have been wilting in warmer and nutrient-poor water. Making matters much worse has been the explosion in population of sea urchins that thrive in warmer water. The urchins gobble up the kelp, often resulting in so-called urchin barrens, largely devoid of life.

Kelp are considered a foundation species that occupy nearly half of the world’s marine ecoregions. They thrive in cold water, where they form large underwater forests that provide essential habitat, food, and refuge for many species. Kelp are often harvested for use in products ranging from toothpaste and shampoo to puddings and cakes. Including the other services kelp provide, they are associated with billions of dollars in value annually.

On the North American Pacific Coast, a species of sea star consumes sea urchins. However, these creatures are critically endangered. A marine wildlife epidemic known as sea star wasting syndrome, which began 10 years ago, has killed off more than 90% of the sunflower sea star population. A new study by researchers at Oregon State University looked at the ability of sea stars to control sea urchin populations.

Lab experiments showed that sea stars consume urchins at a rate sufficient to maintain and possibly even restore the health of kelp forests. The study shows that there is a clear link between the population crash of sea stars, the explosion in sea urchin populations, and the decline in kelp.

The study’s authors are calling for active management and a coordinated sea star recovery program to try to deal with the effects of a disease whose cause has not been determined.

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Sea stars able to consume kelp-eating urchins fast enough to protect kelp forests, research shows

Photo, posted December 14, 2015, courtesy of Ed Dunens via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Deepwater Impacts Lingering

May 10, 2019 By EarthWise Leave a Comment

On April 20, 2010, an explosion on the BP-owned Deepwater Horizon drilling rig released an estimated 210 million of gallons of oil into the Gulf of Mexico. Some of the oil was recovered, burned, or dispersed at sea, while some washed up onto coastal shorelines.

Now, more than nine years later, a long-term study suggests the oil is still affecting the salt marshes of the Gulf Coast. A multi-institutional research team began sampling in the region once the spill was contained and continue their work to this day.

The researchers found that heavily-oiled marsh areas remained less healthy than less polluted sites more than six years after the spill. They fear that complete recovery of these oil-soaked regions will likely take more than a decade.

But the researchers also discovered that salt marsh grasses play a key role in coastal wetland recovery. Two plants dominate healthy salt marshes in the Gulf: smooth cordgrass and black needlerush. Single-celled, plant-like organisms known as benthic microalgae also abound in healthy salt marshes, as do many small invertebrates.

In heavily-oiled areas, the researchers found that nearly all the plants died, and benthic microalgae and small invertebrate populations declined significantly. Importantly, however, they also found that it was only after smooth cordgrass started its comeback in these areas that invertebrate populations began to recover. They noted that these salt marsh grasses provide habitat, bind soil, slow water, facilitate colonization, and fuel the food web.

Plants are the foundation of and play a crucial role in salt marshes. The researchers hope these findings will help shape the mitigation strategies of any future oil spills.

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Continuing impacts of Deepwater Horizon oil spill

Photo, posted April 21, 2010, courtesy of Deepwater Horizon Response via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.