According to the latest scientific data, there are 26 invasive species in the Black Sea. Nine of them are crustaceans and the rest are zoobenthos, said Prof. Valentina Todorova from the Institute of Oceanology at the Bulgarian Academy of Sciences, who together with Assoc. Prof. Kremena Stefanova, presented a report on the current state of the marine environment and along the Bulgarian coast. The discussion was attended by the Minister of Environment and Water Julian Popov, the head of the Varna Basin Directorate, Yavor Dimitrov, among others. The meeting was hosted by the BTA National Press Club in Varna.
Invasive species can pose a risk to biodiversity, Todorova said. She recalled that estimates of their presence in the sea over the years vary between 41 and 293 species. According to the latest data, however, the invasive species for the Bulgarian Black Sea coast are 26.
Two of the invasive species have serious impacts on local biodiversity and the Black Sea food network- the Rapana venosa (veined rapa whelk) and the Mnemiopsis leidyi. The rapa whelk was introduced to the Black Sea in the 1940s. In about 15 years this special became widespread along the coast. The appearance of these snails is linked with the disappearance of the edible oyster and the strong decline of the black abalone and scallop populations. Today, the distribution of the veined rapa whelk off the Bulgarian coast is limited to depths of about 45 metres, with the greatest distribution at 10-20 metres.
The zooplankton species Mnemiopsis leydi was first identified in the early 1980s. The species is highly adaptable, establishing extensive populations, and has an impact especially on zooplankton-eating fish because it is their competitor for food. After 1995, another species of ctenophora jellyfish, the Beroe ovata, also a carnivore, was introduced. Other alien species of zooplankton are now also found in the sea, but they can also be considered as food resources for some fish.
/RY/
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