Short-term heat shock perturbation affects populations of Daphnia magna and Eurytemora carolleeae: a warning to the water thermal pollution

Kacper Nowakowski,Łukasz Sługocki

doi:10.1038/s41598-021-96464-8

Abstract

Thermal pollution leads to short-term heat shock in aquatic invertebrates; however, the modulation of tolerance and life history of these invertebrates by thermal stress varies among regions, phenology, species, and their acclimation. To assess the effect of thermal shock, we conducted experiments on Daphnia magna and Eurytemora carolleeae at 25 °C, 30 °C, 35 °C, and 40 °C (in relation to 20 °C) in a different exposure time of the stressor (10, 30, and 60 min). The results showed that short-term heat shock leads to increased mortality and reduced fertility of the studied planktonic crustaceans. D. magna was more resistant to thermal shock than E. carolleeae according to all variants of exposure based on the calculated LT50 values for 24, 48, and 72 h. Thermal shock decreased the potential of the Daphnia population in terms of the total number of births, however, with regard to individual reproductive abilities, the non-lethal heat shock did not reduce the birth rate. Although Eurytemora is more sensitive to thermal shock than Daphnia, the type of parental care in Eurytemora might be more favorable for offspring survival following thermal shock than in Daphnia. In Eurytemora, despite maternal deaths, a relatively high number of newborns who survived high temperatures were observed. The obtained results can help to understand the ecological processes occurring due to anthropogenic thermal pollution.

Highlights

Thermal pollution leads to short-term heat shock in aquatic invertebrates; the modulation of tolerance and life history of these invertebrates by thermal stress varies among regions, phenology, species, and their acclimation
D. magna was used as a model species in thermal pollution studies on a molecular level[13] but less is known about population response to the stressor
Calanoid copepods as Acartia, Calanus, Labidocera, and Pseudodiaptomus were used in acute thermal pollution studies[6] but still less is known about genus Eurytemora

Summary

Introduction

Thermal pollution leads to short-term heat shock in aquatic invertebrates; the modulation of tolerance and life history of these invertebrates by thermal stress varies among regions, phenology, species, and their acclimation. The results showed that short-term heat shock leads to increased mortality and reduced fertility of the studied planktonic crustaceans. Thermal pollution can lead to a sudden short-term heat shock that affects aquatic organisms. This applies to both vertebrates and small organisms that are carried through the river current[4]. Experimental studies on the influence of heat shock on representatives of these taxa are important to understand how a short-term thermal shock affects the formation of heated water communities. For the present experiment, model species of crustaceans were chosen, namely Dapnia magna Straus 1820 and Eurytemora carolleeae Alekseev & Souissi 2011 (Eurytemora affinis species complex)

Methods

Results

Conclusion