Invasive Species Spreading Off Israel's Coast, Heralding Ecological Hazard

Large populations were found in the shallow waters between Haifa and Netanya last summer; researchers say it is already affecting the food chain in the sea

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Brown mussels at Havatzelet Hasharon Beach near Netanya on Sunday.
Brown mussels at Havatzelet Hasharon Beach near Netanya on Sunday.Credit: Kfir Gayer

In the shallow waters off Israel’s coast, extensive spread of the brown mussel, an invasive species that could harm the marine ecosystem, has been observed. Researchers believe the species reached the area by adhering to ships.

Last summer, researchers collected specimens of the mussel in the Haifa Bay, at Ne’urim Beach and Havatzelet Hasharon Beach near Netanya. In several locations, several dozen mussels were counted within a single square meter.

The mussels were examined in the laboratory to determine which species they are and where they originated. They were identified as brown mussels (Perna perna) that came to Israel’s shores from different regions. The research findings were published last week in the journal BioInvasions Records, which covers invasive species in the marine environment. The research was conducted by Jacob Douek, Guy Paz and Baruch Rinkevich of the Israeli Oceanographic and Limnological Research Institute and by Bella Galil and Kfir Gayer of the Steinhardt Museum of Natural History at Tel Aviv University. Diver and photographer Moti Mendelson also took part in the research.

The brown mussel’s original habitat is in the Red Sea and Indian Ocean. Over time it spread to other parts of the world, by attaching itself to ships. Large populations have been observed in the Bay of Mexico, along South America’s Atlantic coast and in southern India, among other places.

The brown mussel later arrived in the western Mediterranean. At the port of Trieste, Italy, it was found on an ocean oil rig that was brought from the coast of Senegal in Africa. Until recently, it had not been observed in large numbers in the eastern Mediterranean.

Several specimens of this mussel were collected in Israel decades ago. In the 1960s, they were discovered on tankers that carried oil to the Reading Power Station in Tel Aviv, and in 1982, they were found in Achziv. They had not been seen here since. The mussels that have now been observed were found attached to rocks in shallow waters. In places where there is a large outbreak of the brown mussel, it can become an ecological hazard, since it crowds out local species.

Along Israel’s shores, the brown mussel is coming to an environment that has already been affected by invasive species that arrived from the Red Sea via the Suez Canal and replaced the local populations. A recent study done at the marine sciences department of the Ruppin Academic Center found that invasive species of mussels originating in the Red Sea have completely taken over extensive areas off the coast.

The brown mussel can impact the food chain, and apparently is already doing so along Israel’s shores. The researchers note that since the brown mussels' arrival, there has been in an increase in the numbers of the native whelk known as the red-mouthed rock shell. This whelk preys on the mussels by drilling a small hole in their shell and injecting a paralyzing toxin. This type of mussel is a preferred food for the whelk.

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