Seasonal Dynamics of Growth and Production of Monoporeia affinis (Amphipoda: Pontoporeiidae) in a Subarctic Lake: The Role of Temperature and Trophic Conditions

Abstract

The growth and production of glacial relic amphipods Monoporeia affinis in a small subarctic lake were studied based on detailed seasonal observations in 2019–2021. Growth and production were closely related to trophic conditions (chlorophyll a concentration). The maximum values were observed at low water temperatures (~5°C) in early summer, coinciding with the spring maximum of chlorophyll. The summer warming of bottom waters was accompanied by a decrease in the growth rate of amphipods, which is apparently associated with the consumption of most of the primary production in the pelagic zone. It is concluded that current climatic conditions can adversely affect glacial relicts even in cold-water lakes of the subarctic zone.