What drives benthic macroinvertebrate dispersal in different lake substrata? The case of three Mediterranean lakes

Benthic macroinvertebrate communities from different lake zones are known to respond differently to environmental parameters and human pressures. The objectives of this study were to explore the spatial and temporal variability of benthic communities, investigate the effect of environmental factors on their assemblages and assess their response to eutrophication in the profundal and sublittoral zones of three Greek eutrophic lakes (Volvi, Kastoria and Mikri Prespa). These lakes are subjected to different land uses in their catchment areas. Samplings were conducted bi-annually (spring and autumn). Sixteen taxa were collected in the sublittoral and eleven in the profundal zone of the studied lakes. Among them, some species were recorded for the first time in the studied lakes. The dominant species were Potamothrix hammoniensis (Michaelsen, 1901) (Oligochaeta), Chaoborus ( Chaoborus ) flavicans (Meigen, 1830) and Chironomus ( Chironomus ) gr. plumosus Linnaeus, 1758 (Diptera), reflecting the eutrophic status of these waterbodies. Benthic communities, their functional traits (microhabitat preferences and feeding types), diversity and rarity species differed among lakes. Especially Lake Prespa, as a potentially ancient lake, hosts an endemic oligochaete community. Altitude and eutrophication (expressed as P–PO 4 and BOD 5 concentrations) were the main environmental factors explaining spatial and temporal variability in the assemblages. Based on the Greek Lake Benthic invertebrate Index, the ecological quality of the studied lakes was estimated as good to moderate. Benthic macroinvertebrates from both lake zones are associated with eutrophication, which is related to anthropogenic activities. Therefore, these lake zones should be included in assessment methods linking benthic invertebrate assemblages to eutrophication.