Spatial and temporal variation in fish populations and assemblages in coastal waters of the northern Baltic Proper

摘要: The distribution and traits of  sh are interest both ecologically socio-economically. In this thesis, phenotypic structural variation in populations assemblages was studied on multiple spatial temporal scales shallow coastal areas the archipelago northern Baltic Proper. Lumparn basin Aland Islands, assemblage displayed signi cant seasonal depth zone distribution. results indicate that investigating small scale is crucial for understanding patterns community structure large scale. local population Eurasian perch Perca  uviatilis L habitat-speci c morphological dietary variation. Perch pelagic were average deeper their body shape than littoral ones fed benthic invertebrates. differ from previous studies conducted freshwater habitats, where typically streamlined zooplanktivorous. Stable isotopes carbon nitrogen differed between with different stomach contents, suggesting differentiation individual diet preferences. study Ivarskarsfjarden Islands Galtfjarden Swedish east coast, development during 2000’s indicated a general shift towards higher abundances small-bodied lower-order consumers, especially cyprinids. For European pikeperch Sander lucioperca L., recent declines adult high mortalities (Z = 1.06–1.16) observed, which suggests unsustainably shing pressure pikeperch. Based it can be hypothesized has reduced predatory sh, together bottom-up forcing by eutrophication allowed consumer species to increase abundances. This thesis contributes scienti aquatic ecosystems new descriptions adaptations brackish water, small-scale also demonstrate anthropogenic effects communities underline urgency further reducing nutrient inputs regulating sheries Sea region.