Dependence of Long-Term Dynamics of Zooplankton in the Ob River on Interannual Changes in Hydrological and Hydrochemical Parameters

Abstract

Here we summarize a long-term study on qualitative and quantitative composition of zooplankton (Cladocera, Copepoda, Rotifera) in the Ob River. We carried out these investigations at 13 sampling stations of the Middle and Low Ob in the years 1994, 1996, 1999, 2001, 2002 and 2009. It was found that the species richness of all zooplankton and abundance of cladocerans and rotifers is significantly determined by the temperature conditions of the month preceding sampling. In contrast, among other factors, we revealed that pH decreases as well as phosphate and nitrate concentrations increase zooplankton abundance. Dissolved oxygen and oxidizable organic substances (BOD5) were positively correlated to copepod population levels (according to abundance and biomass); on the other hand, an increase in difficult-to-oxidize substances (COD) inhibited their development. During this study, we found that high water levels had a positive influence on zooplankton richness in river itself probably due to being downstream from Ob River floodplain lakes.

Physicochemical Parameters of River Water and their Relation to Zooplankton: A Review

“…Essien-Ibok and Ekpo [59] found that the highest zooplankton density coincides with the high values of phosphate and nitrates. Also, Yermolaeva et al [60] showed that increasing phosphates and nitrates stimulate the growth of rotifera and cladocera in Ob River western of Siberia.…”

Interaction among Hydrological, Environmental, and Ecological Processes in Aquatic Ecosystems

“…The hydrochemical characteristics of rivers could influence the growth of zooplankton. To investigate this influence, Yermolaeva et al [6] performed a long-term experiment for the composition of zooplankton in the Ob River, Russia, in the years 1994, 1996, 1999, 2001, 2002, and 2009. This experiment found that species richness and abundance were closely related to the temperature in the month before sampling; PH had a negative correlation, while phosphate and nitrate concentrations had a positive correlation with zooplankton abundance.…”

Phytoplankton as an indicator of the current ecological status of the Ob River

“…The total length of the river is 3,680 km. With respect to the nature of the valley and watercourse, the river is conventionally divided into 3 parts: the upper part stretches from the confluence of the Biya and the Katun to the Tom mouth (1,020 km), the middle part stretches from the Tom to the Irtysh mouth (1,500 km), and the lower part stretches from the Irtysh mouth to the Ob Bay (1,160 km) (Plaschev and Chekmarev 1967;Mitrofanova 2019;Yermolaeva et al 2021).…”