Small water bodies in agricultural areas as important habitats for euglenoids in Poland

Temporary water bodies of glacial origin, known as kettle holes, are typical elements of the young moraine landscape in many countries. Unfortunately, they are very exposed to effects of anthropogenic changes, especially in agricultural areas. Due to their small area and depth, as well as to the great fluctuations in water level, they create specific conditions for organisms that inhabit them. Consequently, kettle holes are unique biodiversity hotspots in landscape, rich in some microalgal species, particularly euglenoids (euglenophytes). In this study, the taxonomic composition of euglenoids was studied in three temporary water bodies in an agricultural landscape of Wielkopolska Province (western Poland). In total, 65 euglenoid taxa were identified there during one year. Euglenoids in the investigated field ponds were the most species-rich group of microalgae. They accounted for 26% of the total number of phytoplankton taxa. According to the constancy (frequency) of occurrence most of the species were incidental. The most common taxa were: Trachelomonas volvocina, Euglenaformis proxima, Trachelomonas intermedia, Lepocinclis tripteris, and Lepocinclis acus. The high species richness of euglenoids in aquatic ecosystems of agricultural areas shows how valuable ponds are for preserving local biodiversity and for aquatic food webs. The small water bodies in farmlands should be protected against progressive anthropogenic eutrophication and degradation.