The Effects of Artemia Cyst Harvesting on the Salt Lake Ecosystem

In Russia, the main stocks of Artemia cysts and cyst harvesting activities are concentrated in Western Siberia. About 1,100 tons of cysts are harvested annually, including 180 tons in the Kurgan Region and 140 tons from Medvezhye Lake (about 2 % of their world harvest). The purpose of this study was to determine the degree of influence of Artemia cyst harvesting on the ecosystem of a salt lake in a case study of Medvezhye Lake. The main trophic components of the ecosystem – phytoplankton, zooplankton, and zoobenthos – were analyzed. The salinity of the brine of Medvezhye Lake varied between 110 and 320 g/dm3 in different years. Phytoplankton in the lake function throughout the year. They are characterized by small cell sizes, low biomass (0.76±0.24 mg/L) and daily production (1.03±0.18 mgO2/L or 0.3±0.05 gC/m2), and high levels of A/B and P/B coefficients. Zooplankton and zoobenthos are represented mainly by Artemia. The biomass of Artemia shrimp reached 21.9±3.2 mg/L (219 kg/ha) on average during 1995-2018. During this period, the stock of cysts formed annually in the lake was 114.5±14.3 kg/ha; the harvest was 23.7±3.0 kg/ha (21 % of the stock). The main components of the ecosystem – phytoplankton – Artemia shrimp – Artemia cysts – were produced annually in the following proportions: 8390:2678:115 kg/ha·year (75:24:1 %). The removal of 23.7 kg/ha of the cysts (0.22 % of the production of all components) from the lake is negligible compared to the other components of the ecosystem. The residual density of cysts after harvesting, which is necessary for the reproduction of the Artemia population for the next season during the 1st generation, is 10 kg/ha. Averaged data indicate that the amount of Artemia cysts left in the ecosystem of Medvezhye Lake after cyst harvesting is 91 kg/ha, i.e. 9 times greater than the minimum required density. The results reported in the present study indicate that the current level of cyst harvesting cannot have any significant impact on the ecosystem of the hypersaline lake

THE STATUS OF THE POPULATION OF ARTEMIA IN THE DEPRESSIVE PERIOD IN THE LAKE OF THE GREAT ALERT EDGE OF THE ALTAI

Research on hypergalin lakes began in 1977. Commercial interest in Artemia (at the cysts stage) as a starter feed for aquatic organisms served as the basis for monitoring studies of hypergalin lakes in the Altai Territory. Lake Bolshaya Yarovoye is noted as one of the largest bodies of water in the region with a population of toad crustacean Artemia Leach, 1819. Considering the depressed state of development of the Artemia population in the lake Great Spring in the growing season of 2017 (the reservoir productivity was 5.8 kg / ha), monitoring studies were conducted to clarify the status of the productivity of aquatic bioresources. As a result of complex hydrobiological surveys in the spring period (April – May), 2018, the dynamics of indicators of the number of early stages of development of the first generation Artemia crustaceans and cysts in the lake are presented. Big Spring Altai Territory. The analysis of the influence of the temperature and salinity of the water in the spring of 2018 on the condition of Artemia crustaceans and the reservoir productivity was carried out. In the course of monitoring studies of the hypergalin reservoir in April and May 2018, during the development of the first generation of crustaceans, a depressive state of development of the Artemia crustacean population was revealed. The temperature at the beginning of the growing season of the current year was unfavorable for the development of Artemia in the lake, which resulted in low numbers of crustaceans. Given the depressed state of the development of the Artemia population in the lake. In the growing season of 2017, the Great Spring, the extraction of bioresources (Artemia (at the cysts stage)) at the current state of the population can significantly undermine the fishing base of the reservoir and damage the further development of Artemia.

Morphometric studies of artemia males from different populations of the Altai region

The long-term data from morphometric studies of Artemia males from bisexual and parthenogenetic populations from hyperhaline reservoirs of the Altai region (Bolshoe Yarovoe Lake, Maloe Shklo Lake, and the Tanatar Lakes system) is analyzed in this paper. The description of signs of sexual dimorphism and sexual structure in different populations is given. The influence of brine salinity and hydrogen index on morphometric parameters of males was analyzed. There are differences in the sexual structure of the Artemia population: in the lakes Maloe Shklo and the thanatar system, the populations are bisexual (the share of males is 28.5 — 75.0 %), in the lake Bolshoe yarovoe — parthenogenetic (the share of males on average does not exceed 3 %). At the same time, sexual dimorphism is typical for both types of populations: females are larger than males, males have a larger head (the distance between the eyes is greater by 15.5 %, the diameter of the eye is 26.1 %, the length of the antenna is 22.3 %) and a larger number of bristles (36.1 %). The greatest variability is observed in the parameters of the Furka structure associated with the salinity of water by feedback and the pH — line indicator. Significant differences between the samples of males were revealed. The largest number of significant differences in morphometric indicators was found between samples of males from bisexual populations (lake thanatar and lake Maloe Shklo), the smallest — between males from the parthenogenetic population of lake Bolshoe yarovoe and males from lake Maloe Shklo.

DEVELOPMENT OF THE ARTEMIA POPULATION OF THE ARAL SEA

Information on the biomass of Artemia in the Aral Sea during 2000-2018 is presented. Biomass peaks were observed in June-July. The data on total mineralization and ionic composition are given. Since the beginning of the Artemia cyst fishery in 2010 (30 tons of cysts were collected), the volume of cysts collection has constantly and many times increased and reached 542 tons in 2018

Annual and Seasonal Variation in Artemia Population in Relation to Water Quality Parameters in Lake Galgas in Crimea, Russia

Aim: To study seasonal changes of hydrological parameters of the water and Artemia population status in the hypersaline Galgas Lake in the period of 2017-2019. Study Area and Duration: The study was carried out in the Crimea, a peninsula on the northern coast of the Black Sea in Eastern Europe in 2017-2019. Methodology: Water (brine) and Artemia samples were collected monthly from the lake located at the coastal line of the Black Sea. The parameters namely temperature, pH, salinity, Eh, and oxygen concentration of were determined in the water. Artemia population including the developmental stages and the cysts hatching rate of the cysts were measured in different seasons in the study period. The differences in hydrochemical characteristics of the study area in different years and seasons were observed. Results: The results showed that the hydrochemical characteristics of the study area varied with the climate peculiarities. In summer months 2017, the lake was dried out. In the hot period, the temperature of the air and water was above +30°C, the pH ranged insignificantly, and the oxygen concentration was low. Artemia cysts were found throughout the year, however the nauplii were mostly available during spring and autumn seasons, while the adults were found in spring and summer months. Conclusion: The study concluded that the changes of the water parameters depended on season and especially on air temperature. The changes of Artemia population were different in examined years and depended on the water characteristics and especially on temperature and oxygen concentration. The obtained results could be helpful for the local climate changes consequences studies and their influence on aquatic biota.