@phdthesis{Baptista2012, author = {Baptista, Melissa}, title = {Phytoplankton succession and diversity-productivity relation in German and Brazilian shallow lakes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-24386}, school = {BTU Cottbus - Senftenberg}, year = {2012}, abstract = {Phytoplankton succession linked to productivity-diversity relationship at steady-state/non steady state conditions, mixing events as predominant disturbance in sense of Connell (1978) and influence of conditional differentiation (temperature) on phytoplankton diversity were investigated. Water samples were taken two times a week in 4 German shallow lakes in Brandenbug region (Melangsee, Petersdorfer See, Wolziger See, and Langer See) from 2007 to 2010 and in 2009/2010 during cold and rainy season in a Brazilian coastal lagoon Peri. A comparison between literature data from 4 Brazilian lakes, in order to investigate the influence of temperature on diversity and dynamic of phytoplankton species was also done. The cyanobacterial species dominated all studied lakes and the mixing had a positive effect on the supremacy of this group in tropical lakes. The high biovolume of cyanobacteria contributed to the achievement of steady state conditions in sense of Sommer et al. (1993) during consecutive periods in Petersdorfer See and in Peri lagoon practically during all phases. The monodominance of Cylindrospermopsis raciborskii was observed in warm water, under no stratification regime. Oscillatoriales of group S1 (Reynolds 2002), represented by Limnothrix redekei and Pseudanabaena limnetica, typical in turbid mixed layers and with high nitrogen affinity, were typical in Petersdorfer See. In Melangsee, steady state was observed during colder periods under dominance of Bacillariophyceae and Chrysophyceae. Lower diversity coincided with steady state conditions and higher values of resource use efficiency (RUE), while higher diversity occurred mainly at transitional state during the spring in temperate lakes, supporting the non-equilibrium concept (Hutchinson 1961) at lower RUE values. Higher biovolume occurred mainly during the late summer in temperate lakes under dominance of cyanobacteria, and/or at steady state. Concerning the temporal variation of phytoplankton, the highest peak of species richness preceded the resource use efficiency, suggesting the productivity as consequence of diversity. The richness was much higher in temperate shallow lakes, which were more similar to each other in terms of seasonality, species number and biovolume. A positive correlation between richness and biovolume of temperate lakes was found and the opposite was observed in tropical lakes. The biovolume and richness in tropical lakes were more variable and in temperate lakes presented higher richness at intermediate level of biovolume (annual mean from 10 to 18 mm3/l). Low level of biodiversity allows an ecosystem to function under constant conditions, but a greater biodiversity occurred in fluctuating environments.}, subject = {Brandenburg; Brasilien; Flachsee; Phytoplankton; {\"O}kosystem; Phytoplanktondiversit{\"a}t; Prim{\"a}rproduktion; Phytoplanktonsukzession; Paradoxon des Phytoplankton; Steady-state; Phytoplankton diversity; Succession; Primary productivity; Paradox of phytoplankton}, language = {en} } @phdthesis{Paetzig2015, author = {P{\"a}tzig, Marlene}, title = {Effect of lakeshore modification on structure and secondary production of macroinvertebrates in a large temperate lowland lake of Northeast Germany}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-36445}, school = {BTU Cottbus - Senftenberg}, year = {2015}, abstract = {Many lake water bodies not attained the goal of the European Water Framework Directive (WFD) to achieve a good ecological state by 2015. This is, among other things, because the assessment and improvement of hydromorphological conditions of lakeshores has been neglected as an important component ensuring the ecological integrity of lake ecosystems. In recent years, macroinvertebrates were emphasized to be useful indicators for the assessment of lakeshore hydromorphology. Hence, in Europe macroinvertebrate-based assessment methods were developed to evaluate the hydromorphological conditions of lakeshores. In this thesis, some of the uncertainties and missing aspects of existing macroinvertebrate-based assessment methods were addressed. The results were obtained by sampling macroinvertebrates and macrophytes at natural shores and at shores modified by marinas and beaches in three depth zones between April and November 2011 in a large lowland lake (Lake Scharm{\"u}tzelsee, Germany). Firstly, I clarified that upper littoral macroinvertebrates should be used for assessing the hydromorphology of lakeshores. It was shown that the effect of lakeshore modification on macroinvertebrate diversity and community composition was most pronounced in the upper littoral and decreased to the profundal zone. Secondly, I demonstrated that a single seasonal sampling is sufficient to capture the compositional differences of macroinvertebrate communities associated with human lakeshore modification. Seasonal effects on upper littoral macroinvertebrate diversity and composition were less important than shore type in comparison with the middle littoral and profundal zone. Thirdly, upper littoral macrophyte communities were also affected by lakeshore modification and at the same time the most important variable structuring macroinvertebrate communities. Hence, the effects of different shore types on macrophytes were transferred to macroinvertebrates, but artificial substrates were also able to partly substitute macrophyte habitats as it was shown for the studied marinas. Since lakeshore modification affected macrophytes slightly differently than macroinvertebrates, macrophytes should be considered as an additional component in lakeshore assessment. Finally, secondary production as proxy to determine the effect of lakeshore modification on the functioning of macroinvertebrates was estimated. Estimation of secondary production requires the determination of biomass. Biomass was indirectly determined by using length-mass regressions established for macroinvertebrates from temperate lakes of the central European lowland. The result showed that total secondary production and secondary production of native taxa in the upper littoral was substantially lower at the studied beaches compared to natural sites. In contrast, upper littoral secondary production at marinas did not differ to natural sites, but secondary production of non-native taxa was significantly higher at marinas. No effects of lakeshore modification on secondary production were found with increasing depth. Different scenarios based on upscaling of site-specific production to whole lake ecosystem level gave evidence that the observed local impacts of lakeshore modification can translate into alterations of the functioning of macroinvertebrates at whole lake ecosystem level. In addition, it was emphasized that secondary production as a functional measure is more sensitive in detecting hydromorphological alterations than the structural measures diversity or biomass. Secondary production should therefore be included in existing lakeshore assessment methods. In order to obtain a comprehensive overview about the changes in the functioning of macroinvertebrates following lakeshore modification, it is recommended to consider not only total secondary production but also secondary production of functional groups. With these results, this thesis contributes to the mechanistic understanding of the effect of lakeshore modification on the functioning of macroinvertebrates and the consequences for the functioning of the whole lake ecosystem. The newly generated knowledge helps to optimize the development of successful lakeshore assessment tools and identification of management measures.}, subject = {Lakeshore modification; Macroinvertebrates; Secondary production; Lowland lake; Ecosystem functioning; Seeufermodifikation; Makroinvertebraten; Sekund{\"a}rproduktion; Tieflandsee; {\"O}kosystemfunktionalit{\"a}t; Scharm{\"u}tzelsee; Makroinvertebraten; Sekund{\"a}rproduktion ; Schichtung ; Seeufer; {\"O}kosystem}, language = {en} }