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Influence of spatial distribution of submerged macrophytes on Chironomidae assemblages in the shallow lakes

Tarkowska-Kukuryk M., Kornijów R.

Polish Journal of Ecology

2008

Vol. 56, nr 4

569-579

The influence of submerged macrophytes on composition, abundance and distribution of epiphytic and benthic chironomids was investigated in five lakes differing in the development of vegetation cover. Studied lakes represented three types, classified according to the concept of Alternative Stable States as: macrophyte dominated MD (dense vegetation), phytoplankton-macrophyte dominated PMD (sparse, patchy vegetation) and phytoplankton dominated PD (lack of submerged vegetation). Both zoocenosis responded differently to the changes in macrophyte cover. The density and biomass of benthic midges (density and biomass per m[^2] of bottom surface) were visibly higher in the patchy vegetated lakes; the abundance of epiphytic chironomids did not show any regularity. The species composition of epiphytic chironomids differed visibly between particular lake types, changed with the decrease of macrophyte cover. The composition of benthic midges was similar in all lake types. The studies showed at strong dependence of the proportion of epiphytic to benthic chironomids on the cover of macrophytes. In MD lakes the phytophilous midges were more abundant than benthic; in PMD lakes we observed the opposite pattern.

Deposition rate of lake sediments under different alternative stable states

Gąsiorowski M.

Geochronometria

2008

Vol. 32

29-35

Sediments of five shallow lakes in Polesie Lubelskie region (Eastern Poland), representing a wide range of nutrient concentration, were dated by Pb-210 method and reliable age-depth models were constructed. These models were a base for studies of relationship between status of lake biocenoses and rate of sedimentation in the lakes. The sedimentation rate does not depend on ecological status of studied lakes. The highest mean sedimentation rate was found in phytoplankton-dominated (Lake Syczyńskie) and phytoplanktonmacrophyte- dominated (Lake Sumin) lakes. Macrophyte-dominated lakes represented intermediate values of deposition rate. Lake depth, area and hydrology are more important factors controlling sedimentation rate. The sedimentation rate was rather stable or changed over the time, depending on human management in the lakes’ drainage basins.