Eutrophication favours both mesopredatory fish, such as cyprinids, and reed in Baltic Sea archipelagos. While reed provides important habitat for many fish species, large and dense reed beds can reduce biodiversity and limit predation on mesopredatory fish. The removal of reed to restore predatory fish and decrease mesopredatory fish is rarely investigated. Here, we created channels and lagoons in reed beds in one Baltic Sea coastal bay, predicting the resulting increased water-reed interface would favour predatory fish (pike and perch), while reducing mesopredatory fish. Using a BACI-design (before-after-control-impact), we identified an increase in pike catches and a similar to 50% reduction in cyprinid catches after reed cutting, relative to a reference bay, but no change in perch catches. We conclude that increasing heterogeneity through reed cutting may be one measure to locally improve conditions for pike and lower the abundance of cyprinids, but more studies are required to confirm this.
This review describes the tracking and assessment of eutrophication in boreal lakes, using Finland as an example. The coverage of key ecosystem components sensitive to eutrophication in the ecological status assessment was evaluated. Key approaches for the assessment of these components are reported and discussed to offer a comprehensive view of eutrophication dynamics in Finland as a good example of cold climate regions sensitive to climate change. Our review revealed that, whereas parameters included in the monitoring schemes of the Water Framework Directive (water quality, phytoplankton, benthic invertebrates, macrophytes, and fish) were frequently addressed by Finnish eutrophication studies, other relevant indicators were also included. Such parameters include zooplankton and the overall quality of the sediment, which offer key insights into internal nutrient loading and help define a lake's reference conditions. The discussion highlights overlooked issues in ecological assessments and offers recommendations for improving eutrophication assessment and guiding future monitoring and research.
This study examines the historical occurrence of the harbour porpoise (Phocoena phocoena) in Finnish coastal waters using a dataset of 413 records derived from digitised Finnish press, written in Finnish and Swedish, from the 19th century to the 1970s. The records identified through multilingual search terms, and analysed by time and location, reveal that porpoises were encountered across the Finnish coastline, particularly in summertime from 1828 to 1939, but sightings declined sharply after the 1940s. Most reported individuals were adults. In addition to occasional encounters, porpoises were frequently killed or caught as bycatch in fisheries. The study demonstrates the value of historical datasets in reconstructing long-term population changes and demonstrates the potential of combining cultural-historical and ecological perspectives. It provides new insights into the human-porpoise relationship and supports conservation efforts for this critically endangered Baltic population by integrating digitised archival materials with ecological interpretation.
Some atmospheric compounds are emitted by both natural and anthropogenic sources, making them hard to distinguish. For instance, sawmills emit large amounts of volatile organic compounds, which are released from wood in different processing stages. SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations) is located near sawmills in Korkeakoski (6 km southeast from atmosphere interactions, to avoid a distinct anthropogenic influence from the nearest sawmills.
Long-term observations of coastal ecosystems and atmosphere are crucial for addressing global challenges like air pollution, water, energy, and food supply. Coastal environments are ecological hotspots acting as greenhouse gas sinks/sources, emitting volatile organic compounds (VOCs) and trace gases, and impacting marine aerosol formation. The Tv & auml;rminne Zoological Station (TZS) in the northern Baltic Sea has a long history of marine biology observations. In 2022, a comprehensive atmospheric observatory was established at TZS, leading to the creation of coastal-SMEAR (Station for Measuring Earth surface-Atmosphere Relations). Equipped with advanced instrumentation, the key aim of this station is to understand potential feedbacks between coastal ecosystems and the atmosphere. Initial results indicate that the sea-air exchange of aerosol precursor gases, VOCs and CO2 at the coast are highly dynamic, influenced by meteorological and biological conditions. Establishing SMEAR stations in different coastal environments would greatly help to understand coastal ecosystem-atmosphere feedbacks.
