First records of freshwater Gastrotrichs (Gastrotricha) in Lithuania

Abstract

Gastrotrichs (phylum Gastrotricha) are worm-like microinvertebrates that represent an important component of the miobenthic fauna of marine, brakish-water and freshwater habitats. This phylum includes about 780 free living species of which 450 species can be found in freshwater habitat. As there are no researches about gastrotrichs species composition and ecology in Lithuania the objective of this study was to explore the knowledge of freshwater gastrotrichs in Lithuania. During the study gastrotrichs specimens were collected by sampling freshwater bodies in different regions of Lithuania. There were selected 8 still water bodies in Kaunas district for seasonal sampling (4 times in 2016 year vegetation period - April, June, August, October). Other 23 selected still water bodies in different regions of Lithuania were examined one time in vegetation period. In order to increase species diversity water bodies were selected according to the different ecological characteristics and spatial distribution. After every collection water samples were stored in laboratory (4 °C, no specialised aeration, no lightning) and observed with a light microscope in 14 days after collection. The specimens that were found in water samples have been captured in photos which were used for following species identification. This research resulted in the collection of photographs of 98 gastrotrich specimens. Preliminary were identified 6 species belonging to Chaetonotidae family. As observation of gastrotrichs with light microscope may not provide all morphological data needed for species identification, some specimens were identificated only to genus. This is a completely new data on Lithuanian gastrotrichs, no researches have been carried out before in Lithuania.