engleski

Epiphytic gastropods and food supplies in relation to macrophyte stands

Macrophyte stands constitute numerous diverse habitats and determine environmental conditions suitable for communities rich in diversity and abundance of protozoans, micro- and macroinvertebrates. We studied gastropod and epiphyton structure in three water bodies differing in morphometry (depth, area), transparency, nutrient concentrations, macrophyte cover percentages and plant architecture types (undissected, flotant, Nuphar luteum ; dissected, submerged, Ceratophyllum demersum ). The main goals were to ascertain: 1) spatial changes of epiphytic gastropod communities in stands with different plant architecture ; 2) influence of environmental factors and epiphytic food supplies in the gastropod community structuring. Results of our study suggest that plant coverage and architecture are main factors governing differences in the zooepiphyton and gastropod community structures, in Ceratophyllum pond up to 70 % of macrophyte coverage and in Nuphar water bodies with less than 20 % of coverage. Small sized planorbid snails, mainly presented with Gyraulus taxa, showed affinity to Ceratophyllum stands characterised by higher algal biomass, zooepiphyton diversity and abundance. Larger sized physid snail, Physella acuta, showed preference to Nuphar stands, marked by lower epiphyton abundance and biomass. Grazers were dominant gastropod functional feeding guild in both macrophyte stands. Consequently, attached protozoans (gymnoamoebae, testaceans) and bdelloid rotifers constitute major amount in their feeding preferences. Thus, changes in macrophyte coverage would switch biotic interactions and concomitantly gastropod and aquatic community structures.

shallow lakes/ponds; dissected/undissected plants; algae; protozoans; rotifers

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