NON-INDIGENOUS SPECIES Sample Clauses

NON-INDIGENOUS SPECIES. Assessment of the share of non-native species in taxonomical groups and their role in the investigated regions were based on the principles and methodologies of the MSFD. The introduction of non-native and invasive species into open and especially coastal waters is among the highest risks for the marine environment, which may be even further increased in relation to the global climate change and cause serious adverse environmental, economic and public health impacts. The non-native invaders induced considerable changes in the structure and dynamics of marine ecosystems and the food web by outcompeting original inhabitants. The most pronounced event was the invasion byM. leidyi, which caused cascading effects at higher trophic levels, from a decrease in zooplankton to collapsing planktivorous fish and drastic declines among large pelagic fish and dolphins. After arrival of B. ovata, the Black Sea ecosystem began to recover progressively (Shiganova et al., 2014; 2018). An additional factor that favoured the recovery of the ecosystem was a decrease in level of eutrophication, which resulted from reduced anthropogenic nutrient inputs (Cociasu et al., 2008). That was accompanied by decreasing in total phytoplankton biomass and harmful algae blooms. A combination of these factors in the late 1990s led to a general improvement of the Black Sea ecosystem (Shiganova et al., 2014). The observations during 2016-2019 showed that the abundance of the most harmful invader M. leidyi significantly dropped after arrival of B.ovata. However, in 2019 with very low presence of B.ovata and higher temperatures M. leidyi could reach higher abundance and biomass during its peak, even in December. In this case biomass of edible zooplankton was lower and both of these parameters resulted The introduction of the predatorBeroe ovata into the Black Sea demonstrates a meaningful example of internal biological control. The number of species in the Black Sea is presently relatively small (3,786 as of December 2020). The contribution of non-native species in total abundance amounted for 3.8% (UA region), 9.9% (RF) and 2.6% (GE), while their participation in total number of species was 4.3% (UA), 5.1% (RF) and 6% (GET).he Black Sea natural system is still resilient for the new incoming species and permit naturalisation of most of them without currently noted significant impact. Here, the exception might be geographical expanding of D. quadrilobata and S. gynobranchiata across the basin. So...