Ecological validity of river-floodplain system assessment by planktonic crustacean survey (Branchiata: Branchiopoda)

Abstract

Studies of the Slovakian Danube have indicated profound changes in the structures of several invertebrate assemblages in the section of the river bypassed by the Gabčíkovo hydroelectric project in 1992 and in adjacent floodplain water bodies. The present study investigates the relationship between hydrological connectivity and species diversity in the old main channel and adjacent left-bank water bodies, using resident cladocerans as indicators of the ecological integrity of the river-floodplain system. The work aimed to quantify cladoceran habitat preferences using habitat values (HV) and indication weights (IW) calculated from data accumulated during long-term monitoring of planktonic communities of the Danube floodplain (1,840.5-1,804 rkm) and supplemented with data from the literature. Although not listed as an indicator group in the European Union Water Framework Directive, cladocerans are shown to be highly apposite in the ecological assessment of river-floodplain systems. Of 71 recorded cladoceran species, 19 taxa showed a preference for eupotamal habitats, 24 species preferred eupotamal B/parapotamal waters, and 28 cladocerans were found to prefer the plesiopotamal/paleopotamal habitat type. Identified habitat types follow a gradient of hydrological connectivity with the main river channel, ranging from the eupotamal to more or less isolated floodplain water bodies. A secondary aim was to use the calculated values to assess the ecological integrity of the river-floodplain system. The key element of this procedure is the calculation of the Floodplain Index (FI) (Chovanec et al. Large Rivers, 15(1-4), 169-185 2005) from the summation of the habitat values and indication weights of all species present at the sampling sites. Calculated index values indicate the extent of disruption to lateral connectivity in the floodplain area.

Variations in the Zooplankton Species Structure of Eutrophic Lakes in Turkey

“…Cladocera is important on the water quality and ecology of the lakes when appeared in the middle level of trophic degree [24]. Also, Cladocera has been defined as a good indicator of hydrological dynamism of the water floor and the heterogeneity of the habitat [25]. Rotifera, Cladocera, and Copepoda are the basic groups of zooplankton in freshwaters.…”

Sedimentary-vegetation response to the channel by-pass: A case study of the Danube river

“…owing to several problems (economical, social, ecological or political), Slovakia begun to build water scheme without the support of Hungary (Jansky et al, 2004). The main disadvantages of this decision were major ecological consequences in surrounding areas (Lehotský et al, 2013;illyová, Matečný, 2014;oťaheľová et al, 2007;Jansky et al, 2004). average annual discharge in the by-passed Danube river channel (measured in section 1 848, 4 rkm) was decreased after waterworks initiation in 1993 from 1 900 to 350 m 3 s −1 , resp.…”

“…average annual discharge in the by-passed Danube river channel (measured in section 1 848, 4 rkm) was decreased after waterworks initiation in 1993 from 1 900 to 350 m 3 s −1 , resp. to 220 m 3 s −1 in 1994 (in the winter) and maximum current velocities declined from 2.0−3.5 to 1 m s −1 (vranovský, 1997;illyová, Matečný, 2014). Landforms accumulation on groynes started to form a scrollbar that has developed into floodplain pockets.…”