Zooplankton (Rotifera, Cladocera, Copepoda) of Tributaries of the Cheboksary Reservoir (Middle Volga, Russia)

Study Extent

The presented data set on the taxonomic composition and abundance of zooplankton in tributaries of the Cheboksary Reservoir is based on original materials (samples) of the authors. The species list includes native species and naturalised species, including invasive species. The dataset represents mainly native species (98.4%), with invasive species accounting for no more than 1.6%. Studies were carried out in tributaries of the Cheboksary Reservoir (Nizhny Novgorod Region and the Republic of Mari El, European Russia). Hydrobiological data were obtained and published from 2015 to 2022 from 13 rivers: Vetluga, Sura, Kerzhenets, Sundovik, Kudma, Vezloma, Linda, Pyra, Trestyanka, Chernaya (Zavolzhye), Zhuzhla, Chernaya (Pravoberezhye) and Uzola.

Sampling

The identification of the species composition of zooplankton was performed in 2015–2022. Standard hydrobiological methods for studying zooplankton were applied (Methodology…, 1975; Taxonomic key…, 2010). Sampling grids have been developed. Own data were used to compile the species list.

Quality Control

All samples were identified by the researchers working in the Lobachevsky State University of Nizhnii Novgorod, and were stored in the scientific collection of the university. The reliability of the taxonomic definitions was confirmed by taxonomists of Aitem-0.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences (Korovchinsky et al, 2021; Sinev, Gavrilko, 2020). The taxonomic nomenclature is given in accordance with the taxonomic system GBIF Backbone Taxonomy (GBIF Secretariat, 2021). In order to publish the dataset on the GBIF network, the records have been adjusted according to the Darwin Core specifications (Wieczorek et al., 2012).

Method steps

1. Zooplankton samples were collected by towing a plankton net (70 μm mesh) from the bottom to the water surface. The samples were concentrated to 100 mL and were fixed to a final concentration of 4% formalin solution. Samples were analyzed using light microscopy to identify, count, and measure organisms, determine zooplankton density. Zooplankton specimens were examined using a Zeiss Stemi 2000C stereomicroscope (Carl Zeiss Microscopy, Munich, Germany), and a detailed morphological analysis was performed using an Olympus CX43 light microscope (Olympus Corporation, Tokyo, Japan). When specifying the taxonomic affiliation of zooplankton, we used proper manuals and guides (Błedzki, Rybak, 2016; Rogers, Thorp, 2019; Korovchinsky et al., 2021, Kutikova, 1970; Taxonomic key…, 2010).

Freshwater zooplankton Rotifera

1. Rotifera
   rank: phylum

Freshwater zooplankton Cladocera

1. Cladocera
   rank: suborder

Freshwater zooplankton Copepoda

1. Copepoda
   rank: class

The studies were conducted in tributaries of the Cheboksary Reservoir (Nizhny Novgorod Region and the Republic of Mari El, Russian)