65% of fish caught in Gulf of Acre contaminated with mercury

The Eastern Mediterranean is heating twice as fast as the global average – report

Research finds sea level rising almost 40% faster than global average, water is saltier, and invasive species comprise more than half the prey caught in sampling nets

Sue Surkes is The Times of Israel's environment reporter

A lionfish hides behind a rock as researchers monitor the Mediterranean Sea. (Guy Ra'anan and Mikey Bar-Adon)
A lionfish hides behind a rock as researchers monitor the Mediterranean Sea. (Guy Ra'anan and Mikey Bar-Adon)

The Mediterranean Sea continues to become saltier and more acidic and is heating twice as fast as the global average, according to the latest annual report of the Israel Oceanographic and Limnological Research Institute.

Between 1992 and 2023, the level of the Eastern Mediterranean rose by around 15 centimeters (nearly six inches), which averages out at a rise of around 4.7 millimeters (0.185 inches) per year. This is compared to a global annual average of 3.4 millimeters (0.134 inches), meaning it is rising almost 40 percent faster.

Invasive algae are replacing native seaweed without the benefits to marine life of the latter, and two local species of previously common edible fish were worryingly absent from sample nets.

But the report, based on the latest in a series of scientific voyages, also featured some good news, including a decline in plastic bags on beaches following government regulation and a trend of recovery of certain marine populations in northern Israel’s industry-heavy Haifa Bay.

The report, covering 2023, said that temperatures in the upper layer of the Eastern Mediterranean Sea were rising by 0.12 degrees Celsius per year — more than twice the World Climate Organization’s estimate that the world’s seas are warming by an average of 0.055 degrees annually.

Changes in sea acidity, caused by rising carbon dioxide in the air, could impact the marine food web, according to the researchers, particularly creatures that build their skeletons out of calcium carbonite.

A diver carries out a measurement as part of the monitoring of the Mediterranean Sea carried out in 2023. (Guy Ra’anan and Mikey Bar-Adon)

As in 2022, invasive (non-native) species comprised more than half of the prey caught in sampling nets. Disturbing increases were noted in the number of lionfish and black sea urchins in shallow kurkar (fossilized sand) ridges. Black urchins, native to the Red Sea, have disappeared from Eilat in southern Israel due to a pathogenic parasite. Those in the Mediterranean are invasive.

The report described blooms of invasive red algae — Asparagopsis taxiformis — along all the country’s coasts. These were first spotted in 2019. As they are eaten neither by fish nor invertebrates, the algae grow unchecked and detach from the rocks during storms, piling up on beaches, especially in towns north of Haifa in northern Israel.

In 2023, two local species of edible fish — red mullet and striped seabream — were absent from the sampling nets. The researchers called for ongoing monitoring, saying this was “worrying” and suggesting it was either due to sea warming and/or invasive species that compete with them for food or push them out of their habitat.

Two divers carry out measurements as part of the monitoring of the Mediterranean Sea carried out in 2023. (Guy Ra’anan and Mikey Bar-Adon)

In 2021, two species of stingray were declared protected for a year. By 2022, a certain upward trend in the number of those fish was measured, but that appeared to have stopped in 2023.

On pollution, monitored annually in seawater, the seabed, river estuaries, anchorages, and marine animal tissue, the findings for 2023 indicated less industrial discharge from factories into the sea in southern Haifa Bay.

However, the research also found a renewed increase in mercury concentrations in edible fish in the Gulf of Acre, north of Haifa, where 65% of the catch was contaminated. The report said that the rise was likely due to heavier rainfall in 2023, causing additional mercury to reach the sea through the groundwater.

The ongoing mercury leaching comes from the groundwater beneath an abandoned factory site slated for restoration, where groundwater rehabilitation has not yet been carried out.

Corals monitored in the Mediterranean Sea as part of an annual research program. (Guy Ra’anan and Mikey Bar-Adon)

Some coastal streams continued to contain “unusual and problematic” concentrations of metals and fertilizers, chiefly from the discharge of poor-quality effluent from wastewater treatment plants and illegal sewage discharges.

“Unusual contamination” with arsenic metal was found in the Tel Aviv Marina from an unknown source, and pollution caused by illegal hexachlorobenzene, a pesticide, was identified at Acre port.

On the positive side, the report noted a downward trend in the amount of plastic bags in beach waste, saying this was likely due to Environmental Protection Ministry steps such as the Clean Beach Program, the Bag Law, and the capture of bags from urban drains.

However, the concentration of floating microplastics in shallow water was higher than in the western Mediterranean (1.2 items per square meter in Israel compared to about 0.7 in Italy).

A young turtle tangled up in a green plastic ‘jute’ bag, photographed at the Israel Sea Turtle Rescue and Rehabilitation Center. (YouTube/Israel Nature and Parks Authority screenshot)

Out of all sea turtles tested between 2020 and 2023, 79% had plastic waste in their digestive tracts, with the number of plastic particles per turtle ranging from hundreds to thousands.

Israel’s expanded national monitoring program has been operating since 2019, with joint funding from the Environmental Protection and Energy ministries, and in line with the Convention for the Protection of the Mediterranean Sea Against Pollution (Barcelona Convention).

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