Abstract ID
biodiv34
Type
Poster
Theme
biodiv
Full title
Effect of Hydrological Regime on the Macrozoobenthos Structure in Floodplain Lakes in Postglacial River
Valleys in Poland
Abstract text
The role of hydrological regime, which is a driving force of essential ecological processes such as production,
decomposition and consumption in river floodplain ecosystems, has been recognized as one of the key factors in
the structure and functioning of riparian wetlands. The amplitude of the flood pulse and the time of inundation
vary amongst floodplains, depending on the floodplain’s geomorphology and the river’s catchment area
and climatic conditions. Hydrological regime of transitional zone of temperate climate is characterized by two
distinct periods of an accelerated water circulation: first period results from snow melting during mid-winter
(January –February) and spring months (March –April), while the second takes place in summer
(June-July). The variable hydrological conditions imposed by the flood pulse pattern underpin a pronounced
seasonal response in the macroinvertebrate composition in floodplain lakes. The impact of hydrological regime
on the hydrobionts and specific process of river –flood systems we studied in 23 floodplain lakes located
along the meandering sections of three river valleys: the Łyna, Drwęca and Słupia rivers located in the
southern watershed of the Baltic Sea (N Poland). The research was carried out in the period of 2005-2009 based
on quarterly sampling. In addition, hydrological data were available from water level loggers installed in each
river channel (DT-Divers, van Essen Instruments, the Netherlands). The results of 5-year study, allowed us to
identify 36 taxa of bottom organisms, among which Crustacea and Diptera dominated. The highest biodiversity
we observed in those ecosystems which were periodically flooded, but daily changes of water were
insignificant. We observed the highest abundance of benthic invertebrates in floodplain lakes with a seasonal
depth range ~1.5 m, which tend to have short periods of hydraulic isolation as well as the frequent or permanent
exchange of water. We found that macrozoobenthos dynamics in temperate floodplain lakes is likely to be just
as variable as seasonal patterns of flooding and isolation. However, the changes in structure and biomass of the
organisms are also related to their life span. Having in mind the Flood Pulse concept, we have found also that
the existence of bottom macroinvertebrates is related to some physical properties of water (temperature,
aeration, transparency) driven to a large extent by hydrological conditions. Due to the relatively low mobility of
bottom invertebrates in water/sediment environment and a relatively simple method of the taxa identification,
the hydrobionts may serve as indicative species of environmental health what follows the implementation of the
European Framework Directive, aimed at restoring all aquatic ecosystems to good ecological status.
Submission date
2009-10-13
Keywords
macroinvertebrate, wetlands, flood pulse, rivers, Poland
Will be submitting paper?
Yes