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 plankton – to 8 thousand/m3, in floating green algae mats – up to 3 thousand/m2, and in benthos – up to 9 thousand/m2. 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.