The status of invasive species along a gradient of depth in the Mediterranean coast of Israel

Fishing in the Mediterranean Sea

Fishing in the Mediterranean Sea

Two major anthropogenic factors have affected the Mediterranean in the last decade: global warming and the invasion of thermophile biota through the Suez Canal. Global warming affects water temperature, mainly in the eastern Mediterranean, as reported by the European Environment Agency. This facilitates the expansion of thermophilic invasive species that have become very abundant within a few years.

In the preset stage of the study, we investigated the status of invasive species along a gradient of depth (= gradient of temperature) off Asdod coast (Israel).

During the first year of the present study we sampled animal at depths of 20, 40, 60, 80, 100 and 120 meters. A total of 73,634 individual fish belonging to 95 species were collected. Sixty-eight of the species are native to the Mediterranean and 27 are aliens.

A comparison of fish communities along the depth gradient revealed a moderate decrease in the number of alien species from 40 to 120 m (fig. 5). However, the proportion of alien species (individuals and biomass) remained steady at depths of 20 to 60 m, while decreasing at depths of 80 to 120 m.