The role of salinity as an environmental filtering factor in the determination of the Diptera taxonomic composition in the Crimean waters

Shadrin

2019

Aquac Res

Bay Sivash was a hypersaline lagoon but after construction of the North Crimean canal, it shifted to a brackish water state. In 2014, the canal was closed; a salinity increase started. In 2018 and 2019, plankton sampling was conducted in the bay at salinity from 30 to 100 g/L. A decrease in taxonomic diversity and total abundance was observed. Before November of 2018, Harpacticoida and chironomid larvae were the most common and abundant groups. Different stages of Artemia were consumed by invertebrate predators and fish at that time. In November 2018, Artemia stages contributed more than 90% to total zooplankton abundance at all sites excepting with salinity lower than 55 g/L. In June–July 2019, adult Artemia were at all sites with salinity higher than 82 g/L when there was no suppression by predators. A self‐sustaining Artemia population in the bay may recover in 2 or 3 years, when the average salinity would reach 80–90 g/L; total abundance of the active Artemia stages may reach 3000–5000 ind. M−3 between April and August. The lagoon may become one of the world main habitats of Artemia having a significant impact to provide world's supply by its cysts.

Section: Discussionsupporting

confidence: 69%

The long‐term changes in plankton composition: Is Bay Sivash transforming back into one of the world's largest habitats ofArtemiasp. (Crustacea, Anostraca)?

Shadrin

2019

Aquac Res

“…The purpose of this work was, after conducting experimental and field studies, to answer the question: Can G. aequicauda effectively feed on chironomid larvae and to some extent influence the development of benthic animal populations, in particular chironomid larvae? Larvae of Baeotendipes noctivagus (Kieffer, 1911), the most common and widespread species of chironomids in the Crimean hypersaline waterbodies, and also promising to use in aquaculture, were used as a model prey (Anufriieva, 2018; Shadrin et al., 2017, 2019b).…”

Section: Introductionmentioning

confidence: 99%

CanGammarus aequicauda(Amphipoda) suppress a population ofBaeotendipes noctivagus(Chironomidae) in a hypersaline lake? A case of Lake Moynaki (Crimea)

Shadrin

Yakovenko

2020

Aquaculture Research

The ecosystems of hypersaline waters are characterized by the simplified trophic webs with the ‘loss’ of predators. In the absence of predators, their role can be effectively performed by omnivorous as Gammaridae species. In Lake Moynaki, a small hypersaline lake, Gammarus aequicauda is one of the most abundant animal species along with chironomid larvae Baeotendipes noctivagus. Both these species are promising objects to use in polyaquaculture, and this adds an importance to know their trophic relations. To analyse G. aequicauda feeding on B. noctivagus, the field and experimental studies were conducted in 2018 and 2019. In two habitats (Ruppia thickets and free water), the abundance of both species significantly differed, and in the thickets of Ruppia, the Gammarus abundance was higher, and of chironomid larvae was less. Taking into account our experimental results and chironomid larvae abundance in the lake during the study period (from 460 to 3,200 ind./m2), the authors conclude that larvae abundance did not limit the rate of their consumption in the lake by G. aequicauda, and one can consume up to 4 larvae per day. Thus, G. aequicauda could receive a diet of about 45% of their weight consuming about 2% of the available larvae daily in areas without the marine grass Ruppia thickets. In Ruppia thickets, chironomid larvae are not important food of G. aequicauda because the Ruppia leaves play a more important role in gammarid diet. With sufficient plant food resources, G. aequicauda can be successfully cultivated together with chironomid larvae.

“…The general conclusion following from all this is that salinity by itself is not a reliable predictor of possible ecosystem changes in the range from about 25 to 120-140 g L −1 . Salinity becomes a hard environmental filter for the existence of certain animal species at its value above 120-140 g L −1 [54]. Consequently, the ecosystem outcomes of anthropogenically induced changes of salinity in saline water bodies are poorly predictable and should therefore be avoided.…”

Section: Discussionmentioning

confidence: 99%

Human-Induced Sharp Salinity Changes in the World’s Largest Hypersaline Lagoon Bay Sivash (Crimea) and Their Effects on the Ecosystem

Колесникова

Revkova

et al. 2022

Water

Lakes and lagoons play an important role worldwide, and salinity fluctuations significantly affect their ecosystems. Bay Sivash, the world’s largest hypersaline water body, underwent a sharp change in salinity, induced by the closing of the North Crimean Canal. To monitor a shift in the ecosystem, a study was carried out from 2014 to 2020 at 15 sites of the lagoon. Since the closure of the canal, the average salinity increased from 22 g L−1 (2013) to 94 g L−1 (2020). Suspended solids and dissolved organic matter also increased. When salinity increased above 50 g L−1, the number of taxa significantly decreased; this was a negative linear relation. The increase in salinity significantly changed the structure of zooplankton and benthos. The most dramatic changes occurred with the salinity increase from 25 to 70 g L−1. Chironomidae larvae numbers began to increase greatly in the ecosystem of the bay, and since 2014, they have rapidly increased their contribution to the abundance of benthos and plankton. The concentration of benthic–planktonic species increased in plankton, in particular, in Harpacticoida and Chironomidae. At salinity above 80–90 g L−1, nauplii and adult brine shrimp appeared to become abundant in plankton and benthos. The transit of the ecosystem to a new alternative state occurred.