An invasive and readily adaptable algae has taken hold in the Marmara Sea and threatens the Black Sea, scientists report. The seaweed, identified as the genus Caulerpa in the family of green seaweeds, is unique in that an individual consists of a single cell, making it one of the largest single-cell plants in the world. Caulerpa has the nickname “killer algae” because of the speed of adaptation to new environments (limited, however, to tropical and subtropical climates) and the invasive nature of its behavior, given that it has no natural predators. Some scientists believe it may have arrived from the Indo-Pacific region through the Suez Canal, and invaded the Mediterranean and Aegean Seas. In the Marmara Sea it has already displaced native flora, such as seagrass, limiting their viable range.
The algae Caulerpa can be exterminated, as shown by successful efforts to eradicate it from southern California waters, but only if caught early enough. The spread of invasive species can be attributed to climate change, rising seawater temperatures, increased salinity, pollution, and fishing and shipping activities. Efforts to control or eliminate invasive species include controlling the discharge of ship ballast waters and expanding marine protected areas to limit human activity. The loss of native species such as seagrass can adversely affect marine environment’s whole food chain, including fish and shellfish resources.