On the life cycle of Paramononchus alimovi Tsalolichin, 1990 and the influence of climatic factors on the quantitative development of this species in the Lake Krivoe

Abstract

The life cycle of nematode Paramononchus alimovi Tsalolichin on two deepwater stations (St. 2 and St. 18) in Lake Krivoe and the contribution of the long-term climate variability to the dynamics of the quantitative development of this species were investigated. As a result of the research, it was shown that the life cycle of this species in Lake Krivoe is 2–3 months. The temperature conditions of this species existence are stable and close to the temperature optimum for this species. Climatic factors indirectly influence the quantitative development of this species in Lake Krivoe. To analyze the influence of climate on the dynamics of quantitative development of P. alimovi, we calculated the correlation coefficients of the relationship between the average seasonal (May-September) nematode abundance and biomass and indices of the North-Atlantic Oscillation (NAO), arctic oscillation (AO). We found a significant effect of the North Atlantic Oscillation on the quantitative development of nematodes at St.2 for the period July-September (NAO_JAS) with a lag of 2 years, for the period December – March (NAO_DJFM) with a lag of 1 year. For St. 18 a reliable relationship of quantitative development of nematodes with the index for the period March-May (NAO_MAM) without lag is shown. Correlations of climatic indices with benthic biomass with a lag of 1 year and without lag are characteristic of many northern lakes. The maximum income of nutrients should be observed after complete thawing of soils and should be confined to autumn floods. Thus, years with positive index anomalies provide favorable opportunities for the development of phytoplankton in the next year, which is indirectly reflected in the zoobenthos through the trophic chain. Correlation of the NAO index with the values of quantitative development of nematodes in current year is related to the weather preceding the ice disappearance on the lake. Explanation of the obtained two-year lag is associated with another component of the ecosystem – macrozoobenthos. The main component of macrozoobenthos in the depths of the Lake Krivoe is amphipod Monoporeia affinis. This species has 2-year cycle and competes for resources with P. alimovi.