Diversity and Structure of Pelagic Zooplankton (Crustacea, Rotifera) in NE Poland

Maciej Karpowicz,Jolanta Ejsmont-Karabin

doi:10.3390/w13040456

Abstract

This study presents the diversity and structure of pelagic zooplankton in north-eastern Poland. The research was conducted in 47 lakes with different trophic conditions in the middle of summer. Samples were collected close to the deepest part of the lakes to avoid the diverse benthic and littoral zones. We found 119 zooplankton species of which 32 were Cladocera, 16 were Cyclopoida, 4 were Calanoida, and 67 were Rotifera. We determined which species occurred most frequently in the region, as well as the species that were characteristic of different trophic conditions. We also recorded the presence of eight cold-adapted species which some of them are considered as glacial relicts (e.g., Eurytemora lacustris, Heterocope appendiculata, Cyclops lacustris). Our research revealed potential glacial refugia for planktonic species in 14 lakes of NE Poland. Our study suggests that the presence of stenotherm species may be an excellent indicator of the ecological status of deep lakes and could be considered in lake monitoring programs. Furthermore, we did not find Bythotrephes longimanus which has been reported from Poland. Instead, we found that B. brevimanus was the most common representative of the genus in the study area.

Highlights

Zooplankton are a key component of aquatic food webs that transfer energy and matter from primary producers to higher trophic levels and play a pivotal role in biogeochemical cycling [1]
We found the presence of species that could be considered glacial relicts: Eurytemora lacustris, Heterocope appendiculata, Cyclops abyssorum, Cyclops lacustris, Holopedium gibberum, Daphnia longiremis, Bythotrephes brevimanus, and Bythotrephes cf. lilljeborgi
We did not find Bythotrephes longimanus, which was the only species within this genus that was previously reported from Poland

Summary

Introduction

Zooplankton are a key component of aquatic food webs that transfer energy and matter from primary producers to higher trophic levels and play a pivotal role in biogeochemical cycling [1]. The pelagic zone is generally considered as a homogeneous habitat, vertical environmental gradients (light, temperature, oxygen, food, predation pressure) create niches for different organisms [9]. The magnitude of these gradients increases with water transparency [10] which are the main factors promoting the diel vertical migration of zooplankton in clear lakes [11,12,13]. Food and oxygen conditions are often optimal in the surface waters, where visual predators are abundant and UV radiation levels are low. Cryptophytes which are very motile with mixotrophic feeding strategies [16] could benefit from higher bacteria biomass and

Results

Discussion

Conclusion