|
|
Effect of ponds and pond systems on the composition of the benthos in horní Lužnice
SVAČINA, Petr
The work is focused on monitoring changes in benthic communities in the longitudinal gradient of the river Lužnice. The river flows through to the pond area Třeboňsko and the largest pond of the Czech Republic - Rožmberk. It is examine affect of pond on benthic communities. The work involves collecting benthos according to the PERLA method on four profile in four seasons, the analysis of chemical parameters and data processing. The values of SI (saprobiological index) in the longitudinal gradient were from SI 1.8 to SI 2.6. SI values were at the outflow of Rožmberk higher than at inflow. The lowest values were in the first profile Suchdol (SI 1,8 ? SI 2,1) and higher values were in the last profile Vlkov (SI 2,4 ? 2,6). The chemical parameters at outflow were observed increased values of BOD5, TOC, NL105, NL505, chlorophyll and total P but lower values of nitrogen forms (Ntotal,NH4, N-NO3-). On the each profile was the significant change in the incidence or absence of certain groups. Profiles Suchdol and Hlína were diferent than Lužnice and Vlkov especially in the presence of stoneflies, dragonflies, beetles, and individuals generally indicates good water quality. Profiles at outflows from Rožmberk (Lužnice and Vlkov) showed a continued presence of bloodsuckers and more species indicating high organic pollution. NMDS method confirmed impact of sites in communities rather than period (R2 = 0.6 at significance level of p = 0.001).
|
guest ::
