Slovenian marine scientists have sounded the alarm after measuring record-high temperatures at the bottom of the sea. The phenomenon is known as a bottom marine heatwave and can have major repercussions for the ecosystem.

Scientists at the Piran Marine Biological Station of the National Institute of Biology said measurements show the water temperature at the bottom of the Gulf of Trieste, meaning at 22 metres, has risen sharply. At the surface the increase has been more moderate but is still higher than average.

Martin Vodopivec of the Piran Marine Biology Station said the record-high temperature is 24.65 degrees Celsius, with the current bottom marine heatwave being by far the worst in the period since 2002, when the station started regularly measuring bottom sea temperature.

The scientists said the bottom marine heatwave currently experienced was of second to third-category out of 4, which is comparable to the extremely hot summers recorded in 2003. However, this time it is not humans and land organisms that are in peril, but organisms that live on the seabed.

Borut Mavrič from the Institute of Biology warned that elevated temperatures can be very stressful for organisms living on the seabed, as they are mostly unable to retreat to cooler waters.

"We do not yet know what the consequences for the ecosystem will be. In particular, such events point to the need for continuous monitoring of benthic organisms," he said.

The institute said the situation underscores the urgency of measures to protect the marine ecosystem from climate change. The bottom marine heatwave in the Gulf of Trieste serves as a warning that climate change is a reality affecting the environment and the lives of marine inhabitants, it noted.