Rotifera of lake psammon: community structure Versus trophic state of lake waters

• Autorzy: Ejsmont-Karabin J
• Języki publikacji: EN

Abstrakty

EN

Rotifer communities inhabiting wet sands of lake beaches are dependent in their functioning on permanent input of organic matter from neighbouring sites. The aim of the study is to test the hypothesis that trophic state of lake waters may influence densities and structure of psammon communities of Rotifera. Studies were carried out in hydro-, hygro- and euarenal of 44 beaches in 18 lakes of different trophy in summer 1999 (since 2 till 17 July) and 38 beaches in 16 lakes in spring 2000 (since 10 till 23 May). Psammon was sampled always between 10 a.m. and 2 p.m. at similar weather conditions (no shadow, rains and strong winds). Interstitial waters were mostly alkaline and contained less oxygen than lake ones and oxygen concentrations decreased upward water line. Very high variability of phosphate P content made differences between trophic groups of lakes not significant. Similarly, concentrations of P total were more or less similar in all studied trophic groups of lakes. Total nitrogen values were increasing from meso-eutrophic to hypertrophic lakes in spring, whereas this trend was not observed in summer. Chlorophyll a concentrations were similar in meso-, meso-eu- and eutrophic and markedly higher in hypertrophic lakes. In general, some tendency to increasing values of chemical parameters with increasing trophy may be seen if their ranking list is compared. Rotifers were present in all studied stations. In total, 110 species (i.e. ca. 26% of all records of rotifer species in Poland) were found with 22 species occurring exclusively in psammon. Three species new in rotifer fauna of Poland were discovered Cephalodella psammophila, Collotheca wiszniewski and Euchlanis dapidula. Generally all trophic groups of lakes were relatively similar as regards species structure of rotifer communities with rotifers of the genus Lecane playing most important role. The index of Percentage Similarity of Community calculated tbr randomly chosen 30 pairs of particular beaches from the same lake and for beaches of different lakes was in both cases almost identical. Species of high frequency constituted the overwhelming majority of individuals forming rotifer communities of all beaches. Taxons met in 1 to 5 lakes decided on faunistic originality of the communities. Some tendency was observed for higher diversity of psammon rotifer communities in mesotrophic and eutrophic lakes. The lowest values of diversity index occurred mostly in hypertrophic lakes. Psammobionts constituted only 20% and psammoxens 10% of the community abundance in all lakes and all zones of the beaches, whereas psammophilic rotifers decidedly dominated (70%). Rotifer abundance was relatively similar in eu- and hypertrophic lakes and markedly higher in mesotrophic and lower in meso-eutrophic lakes. However, due to high fluctuations of the values noted in particular beaches the differences were not significant in any of the possible configurations of compared data. Monogononta played much more important role in rotifer densities than bdelloids. The hypothesis on advantageous influence of high trophy of lake waters on abundance of psammon communities of Rotifera cannot be supported by results of this work. In lakes of moderate trophy (from meso- to eutrophy) the amount of nutrients and chlorophyll does not seem to influence psammon communities. In hypertrophic lakes this impact is observed, but it seems to be rather unfavourable for psammon rotifers. The communities in hypertrophic lakes are poorer in species, less diversified and less original. The group of animals developing well in this group of lakes are bdelloids. Species composition nad community structure of psammon rotifers seem to be rather determined by many different factors, lake trophy being only one of them and probably not the main one.

Słowa kluczowe

EN

organic matter; nutrient; community; Rotifera; trophic status; chlorophyll; rotifer; lake water; lake psammon; psammon

• Wydawca: -
• Czasopismo: Polish Journal of Ecology
• Rocznik: 2003
• Tom: 51
• Numer: 1
• Opis fizyczny: p.5-35,fig.

Twórcy

autor

Ejsmont-Karabin J

• Polish Academy of Sciences, Lesna 13, 11-730 Mikolajki, Poland