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DOI: https://doi.org/10.59893/abud.23(1).001
Paidere J., Brakovska A. 2023. A continued study of amphipod life histories in the Daugava River under varying meteorological conditions. Acta Biol. Univ. Daugavp., 23(1): 1–11.
Abstract
The Amphipoda Gammarus varsoviensis (Jazdzewski 1975) and Pontogammarus robustoides (Sars, 1894) are dominant amphipod species in the Daugava River. The study aims to describe the structure and fecundity of these populations continuing the previous investigations of 2017–2019 (Paidere & Brakovska 2022). To do this, we surveyed the Daugava River at four sites from April to September 2020. The meteorological conditions of spring and summer of this year were more typical for Latvian conditions than in 2018 and 2019. The population of G. varsoviensis had a univoltine life cycle with one generation per year. The average fecundity was 33 eggs per female, and the average size of ovigerous females was 10.6 mm. The population of P. robustoides had a bivoltine life cycle with two generations per year. The average fecundity was 51 eggs per female, and the average size of ovigerous females was 11.8 mm. The study confirmed that spring temperatures are an influential environmental factor for amphipod reproduction. Low spring temperatures are related to the release of juveniles approximately two weeks later than in 2018 and 2019 as particularly observed in the case of G. varsoviensis.
Temperature rising and prolonged summer season allows higher reproductive success, which can also be expected accordingly to climate change. Evidently, alien P. robustoides has a more successful life cycle than G. varsoviensis and native G. pulex.
Keywords: Gammarus varsoviensis, Pontogammarus robustoides, population structure, reproduction traits, Daugava River
*Corresponding author: Jana Paidere. Laboratory of Hydroecology, Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, Daugavpils, Parādes Str. 1a, Latvia, Email: jana.paidere@du.lv
Aija Brakovska. Laboratory of Hydroecology, Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, Daugavpils, Parādes Str. 1a, Latvia, Email: aija.brakovska@inbox.lv
