The next invasive fish species to enter the Mediterranean may already be known. Tel Aviv University researchers have developed a prediction model that identifies the Red Sea fish most likely to establish themselves in the Mediterranean, giving scientists a chance to prepare for ecological changes before they spread.
While scientists cannot prevent fish from crossing the Suez Canal, the model helps researchers and environmental authorities identify likely invaders before they become widespread, guiding monitoring efforts and protecting native marine species as the Mediterranean continues to warm.
More than 120 fish species have already made the journey from the Red Sea to the Mediterranean through the Suez Canal, which has connected the two seas since it opened in 1869.
Scientists say the Mediterranean’s rising temperatures are accelerating the process, making conditions more suitable for tropical species that previously could not survive there.
The migration is overwhelmingly one-way. While some Mediterranean species have entered the Red Sea, far fewer have established themselves there because of differences in temperature and salinity. Climate change has made the Mediterranean increasingly hospitable to tropical fish arriving from the south.
The phenomenon, known as Lessepsian migration after Suez Canal builder Ferdinand de Lesseps, has already reshaped eastern Mediterranean marine life.
The study identified the stellate pufferfish (Arothron stellatus), the cinnabar goatfish (Parupeneus heptacantha) and the yellowspotted trevally (Turrum fulvoguttatum) as among the species most likely to successfully migrate from the Red Sea into the Mediterranean.
Researchers caution that identifying a species as a likely invader does not mean it will necessarily become a major ecological threat. However, each new tropical species that establishes itself in the Mediterranean can increase competition with native fish for food, shelter and habitat.
Predicting future invaders
The study was led by Dr. Shahar Chaikin as part of his doctoral research at Tel Aviv University, under the supervision of Professor Jonathan Belmaker of the university’s School of Zoology, Wise Faculty of Life Sciences, and the Steinhardt Museum of Natural History.
Rather than examining only species that had already invaded the Mediterranean, the researchers studied fish populations in both seas to identify traits that make a species more likely to complete the journey and survive in a new environment.
The researchers found that the strongest predictor of invasion success was not whether a fish could live in many different environments, as previously believed, but whether it depended on coral reefs.
“The Suez Canal and the Mediterranean contain very few coral reefs like those found in the Red Sea,” Chaikin said. “Species that depend on coral reefs are therefore unlikely to complete the journey. The fish that succeed in invading are those that do not rely on coral reefs for survival in the first place.”
The findings have important consequences for the Mediterranean ecosystem. Once invasive fish establish themselves, they compete directly with native species for food, shelter and space. The study found that newly arrived fish often use the same habitats as native Mediterranean species rather than filling unused ecological roles.
This means invasive species may place additional pressure on existing marine communities, affecting biodiversity and fisheries that depend on healthy fish populations.
The researchers also found that invasive fish quickly adapt after arriving in the Mediterranean, adjusting their behavior to take advantage of conditions in their new surroundings rather than continuing to use the habitats they preferred in the Red Sea.
The study was published in the peer-reviewed Journal of Animal Ecology.
