Chironomidae larvae in hypersaline waters of the Crimea: diversity, distribution, abundance and production

Abstract

Chironomidae larvae may represent more than 70% of total Arthropoda numbers in hypersaline waters. Crimea, the largest peninsula of the Black Sea, has more than 50 hypersaline water bodies of marine and continental origin. Chironomidae larvae are common components of their ecosystems, but they still are poorly understood. This paper summarizes the results of a long-term study (2007-2016) of chironomids in Crimean hypersaline waters. More than 400 samples from 38 water bodies were used for analysis. The maximum salinity of water bodies containing Сhironomidae larvae was between 320 and 340 g/L. At first it was shown that Baeotendipes noctivagus (Kieffer, 1911) is the most halotolerant chironomid species in the world. Frequency of larvae occurrence varied and was negatively dependent on salinity. Four chironomid species were found: B. noctivagus, Cricotopus gr. cylindraceus (Kieffer, 1908), Tanytarsus gr. mendax Kieffer, 1925 and Paratanytarsus sp. Ceratopogonidae larvae were also found twice, at salinities of 150 and 270 g/L. B. noctivagus was the most common species, which occurred in 81% of samples with chironomids. Abundance of larvae fluctuated widely and reached high numbers: in planktonto 8 thousand/m 3 , in floating green algae matsup to 3 thousand/m 2 , and in benthosup to 9 thousand/m 2. Nonlinear dependence of chironomid abundance from salinity was observed; maximum abundance was at salinity levels of between 150 and 170 g/L. The average weight of larvae of 0.05-1.50 mm in length varied little in the samples; however, larvae of greater length had a significantly different average weight. Larvae of 8 mm in the samples had the average actual weight, which ranged from 0.750 to 2.203 mg.

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

“…In plankton, chironomid larvae had become a constant component. Abundance of chironomid larvae sharply increased in the bottom community (Shadrin et al, ; Soloveva et al, ), and B. noctivagus , the most halotolerant species among Chironomidae worldwide, is the dominant species in the bay now (Shadrin, Anufriieva, Belyakov, & Bazhora, ). It was previously shown that at high salinity, a significant number of the chironomid larvae transit from life on the bottom to existence in plankton and/or in floating mats of the green filamentous alga Cladophora (Shadrin et al, ).…”

Macrozoobenthic communities of the saline Bolshaya Samoroda River (Lower Volga region, Russia): species composition, density, biomass and production

“…Among Diptera, the permanent inhabitants of the B. Samoroda River were Chironomidae, Ceratopogonidae, Ephydridae and Psychodidae. Species of these families are widespread in saline waters of the world (Armitage et al 1994;Velasco et al 2006;Przhiboro 2014;Shadrin et al 2017). Chironomid larvae were found in rivers with salinity up to 115 g l -1 (Rutherford and Kefford 2005), Ceratopogonid larvae can tolerate salinity up to 108 g l -1 (Rutherford and Kefford 2005) and Ephydridae larvae up to 100 g l -1 (Velasco et al 2006).…”

Salinity influence on chironomid larvae (Diptera, Chironomidae) in the Crimean hypersaline lakes

“…Не менее 38 их видов разных подсемейств могут существовать при солёности более 35 г/л, 16 из них обитают и при солёности более 100 г/л (Shadrin et al, 2017). При этом при 150 г/л и выше отмечено присутствие лишь 3 видов.…”

“…Осмоадаптация у них осуществляется на клеточном уров-не путем синтеза или/и получения извне и накопления в клетках совместимых ос-молитов -низкомолекулярных органических соединений. Среди Diptera, включая хирономид, есть виды, использующие одну из этих стратегий или сразу оба меха-низма (Patrick, Bradley, 2000;Renault et al, 2016;Shadrin et al, 2017). Механизмы осморегуляции, как и синтез осмолитов, требуют больших затрат энергии, поэтому получение осмолитов из внешней среды может существенно снижать затраты энергии на процессы осмоадаптации.…”

“…Ранее этот феномен отме-чен для хирономид Tanytarsus barbitarsis Freeman, 1961 в водоёмах Австралии при солёности до 177 г/л (Kokkinn, 1986) и копепод в гиперсолёных озёрах Крыма (Ануфриева, 2016;Shadrin, Anufriieva, 2013 b;Anufriieva, 2015). Микроводоросли могут обеспечивать хирономид не только необходимой энергией, но и осмолитами (Shadrin et al, 2017). Все это приводит к предположению, что верхний уровень солёности, при котором хирономиды обитают в природе, не определяется только их физиологическими особенностями, биотическое окружение (пищевые объекты, хищники) является не менее важным фактором.…”