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

Artemia cyst production in salt pans of the Mekong Delta, Vietnam.

The Mekong Delta in south Vietnam has a long coastline with the provinces of Ben Tre, Kien Giang, Long An, Minh Hai, Soc Trang, Tien Giang and Tra Vinh. Traditional salt production is the major source of income for most of the local farmers who live along the coastline, despite the low and unstable price of salt. The introduction of Artemia (brine shrimp) from San Francisco Bay, USA, into the Mekong Delta salt pans, especially in Soc Trang and Bac Lieu provinces, opened a new trend in diversification of aquaculture species to create a better income source for local farmers. In Bac Lieu and Soc Trang provinces, Artemia cyst production is the preferred activity. Normally, they are stocked in salt pans from crystallizer to evaporation areas, even in reservoir areas where the salinity can be maintained at more than 70 ppt. The culture period lasts 5-6 months in the dry season and yields vary from 40 to 150 kg cysts ha-1(in wet weight) per crop, depending on locality, culture technique, and experience of Artemia farmers.

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