The marine heat wave that gripped Florida in 2023 was hotter than anything the state has seen in 150 years, and claimed at least two victims
The marine heat wave that gripped Florida in 2023 was hotter than anything the state has seen in 150 years, and claimed at least two victims — species of corals now marked “functionally extinct” from Florida’s reefs.
That finding comes from a newly published scientific paper that reads more like an obituary for two of the most visible and important coral species on Florida’s reefs: elkhorn and staghorn corals. In 2023, the ocean was warmer than it had ever been. When corals spend too long in hot water, they spit out the algae that live within their bodies, providing them food and shade.
Without them, corals are ghostly white and bleached. If they stay bleached for too long, they starve and sunburn to death over a few weeks. But in 2023, scientists saw something new for Florida. The water got so hot so fast that corals cooked to death in a matter of days.
Scientists are predicting that this summer, there will be the strongest El Niño in decades. What this means is that the ocean in the central and South Pacific will warm 2 C above what it is now. Obviously, this is catastrophic for weather patterns and climate change, as warmer waters mean stronger hurricanes and storms. All of this is devastating, and I feel a lot of grief for our future.
What can we do? We as individuals cannot stop this or slow it, but collectively we can. This doesn’t mean just boycotting or protesting, but engaging in strikes, forming unions, joining a community garden, growing native plants, finding ways to support your local ecosystem, etc.
Fish levels fall by 7.2% with as little as 0.1C of warming per decade, northern hemisphere research shows
Chronic ocean heating is fuelling a “staggering and deeply concerning” loss of marine life, a study has found, with fish levels falling by 7.2% from as little as 0.1C of warming per decade.
Researchers examined the year-to-year change of 33,000 populations in the northern hemisphere between 1993 and 2021, and isolated the effect of the decadal rate of seabed warming from short shifts such as marine heatwaves. They found the drop in biomass from chronic heating to be as high as 19.8% in a single year.
“To put it simply, the faster the ocean floor warms, the faster we lose fish,” said Shahar Chaikin, a marine ecologist at the National Museum of Natural Sciences in Spain and the study’s lead author.
“A 7.2% decline for every tenth of a degree per decade might sound small,” he added. “But compounded over time, across entire ocean basins, it represents a staggering and deeply concerning loss of marine life.”
The study, published in Nature Ecology & Evolution on Wednesday, also found marine heatwaves were leading to short-term booms in some populations that masked long-term harm from climate breakdown.
For instance, a heatwave that could cause sprat populations to fall in the Mediterranean Sea, which is at the warm edge of their natural range, would lead to a boom in the North Sea, at the cold edge of their range.
Fish in cold areas are better able to capitalise on these shifts than those in warm areas, the researchers found, but these temporary cold-water gains mask “widespread loss” due to ocean warming.
Carlos García-Soto, a scientist at the Spanish National Research Council and co-author of the UN’s world ocean assessment, said the study revealed a “concerning” dynamic for ocean governance.
“Overall warming reduces fish biomass, while heatwaves can generate temporary increases that mask the underlying trend,” said García-Soto, who was not involved in the study. “This combination introduces a clear risk of poor interpretation when taking decisions.”
Goth YouTubers wearing synthetic fabrics and enthusiastically promoting brands that produce clothes in synthetic fabrics will be the death of me. And also the planet.
OCEAN WARMING DISRUPTS ANGELSHARK MATING IN THE CANARY ISLANDS
Angelsharks (Squatina squatina), listed as Critically Endangered are showing adverse behaviour related to climate change. Females are avoiding traditional mating grounds during periods of unusually high ocean temperatures, prioritising cooler waters instead. This female absence, documented in La Graciosa Marine Reserve during the 2022 breeding season, contrasts with the continued presence of males, suggesting an increasing mismatch in the species’ reproductive patterns.
The study, led by Lancaster University and the Angel Shark Project: Canary Islands, found that temperatures above 22.5 °C throughout much of autumn and winter may exceed the thermal tolerance of females. Using acoustic telemetry, researchers tracked more than 100 individuals between 2018 and 2023, revealing a clear link between female presence and sea temperature.
These findings highlight the angelshark’s vulnerability to extreme events linked to climate change, particularly in regions like the Canaries, which already represent the species’ thermal distribution limit. The authors stress the urgent need to protect key habitats and maintain long-term monitoring to mitigate the impacts of ocean warming on threatened marine species.
Reference: Mead et al. 2025. Rapid Ocean Warming Drives Sexually Divergent Habitat Use in a Threatened Predatory Marine Ectotherm.” Global Change Biology
Fish levels fall by 7.2% with as little as 0.1C of warming per decade, northern hemisphere research shows
Chronic ocean heating is fuelling a “staggering and deeply concerning” loss of marine life, a study has found, with fish levels falling by 7.2% from as little as 0.1C of warming per decade.
Researchers examined the year-to-year change of 33,000 populations in the northern hemisphere between 1993 and 2021, and isolated the effect of the decadal rate of seabed warming from short shifts such as marine heatwaves. They found the drop in biomass from chronic heating to be as high as 19.8% in a single year.
“To put it simply, the faster the ocean floor warms, the faster we lose fish,” said Shahar Chaikin, a marine ecologist at the National Museum of Natural Sciences in Spain and the study’s lead author.
“A 7.2% decline for every tenth of a degree per decade might sound small,” he added. “But compounded over time, across entire ocean basins, it represents a staggering and deeply concerning loss of marine life.”
The study, published in Nature Ecology & Evolution on Wednesday, also found marine heatwaves were leading to short-term booms in some populations that masked long-term harm from climate breakdown.
For instance, a heatwave that could cause sprat populations to fall in the Mediterranean Sea, which is at the warm edge of their natural range, would lead to a boom in the North Sea, at the cold edge of their range.
Fish in cold areas are better able to capitalise on these shifts than those in warm areas, the researchers found, but these temporary cold-water gains mask “widespread loss” due to ocean warming.
