Search results for "kunnostus"
showing 10 items of 13 documents
Synthesis of habitat restoration impacts on young-of-the-year salmonids in boreal rivers
2019
River restoration offers the potential to enhance biological integrity, often measured as fish population changes. We used a meta-analytical approach to synthesize density responses to in-stream habitat restoration by young-of-the year (YOY) brown trout and Atlantic salmon in 28 rivers (overall 32 restoration projects) in Finland. We also examined which local and watershed-scale factors most influenced restoration success. Finally, we conducted an expert survey to obtain an independent estimate of a sufficient density enhancement for restoration to be considered successful. Despite strong context-dependency, habitat restoration had an overall positive effect on YOY salmonid density. When co…
Lake restoration influences nutritional quality of algae and consequently Daphnia biomass
2020
AbstractFood quality is one of the key factors influencing zooplankton population dynamics. Eutrophication drives phytoplankton communities toward the dominance of cyanobacteria, which means a decrease in the availability of sterols and long-chain polyunsaturated fatty acids (EPA and DHA). The effects of different restoration measures on the nutritional quality of the phytoplankton community and subsequent impacts on zooplankton biomass have rarely been considered. We analyzed the nutritional quality of phytoplankton in the eutrophic Lake Vesijärvi in southern Finland over a 37-year period, and studied the impacts of two restoration measures, biomanipulation and hypolimnetic aeration, on th…
Lakes in the era of global change: moving beyond single‐lake thinking in maintaining biodiversity and ecosystem services
2020
The Anthropocene presents formidable threats to freshwater ecosystems. Lakes are especially vulnerable and important at the same time. They cover only a small area worldwide but harbour high levels of biodiversity and contribute disproportionately to ecosystem services. Lakes differ with respect to their general type (e.g. land-locked, drainage, floodplain and large lakes) and position in the landscape (e.g. highland versus lowland lakes), which contribute to the dynamics of these systems. Lakes should be generally viewed as ‘meta-systems’, whereby biodiversity is strongly affected by species dispersal, and ecosystem dynamics are contributed by the flow of matter and substances among locati…
Lipeälampi - sitkeä vastustaja : tapaustutkimus keskisuomalaisesta ympäristökonfliktista
2011
Tämän pro gradu-tutkielman tehtävänä on tarkastella, miksi Laukaan Koivusuolle sellutehtaan päästöistä muodostuneesta Lipeälammesta on vuosikymmenten mittaan kehittynyt vaikeasti ratkaistava ympäristökonflikti. Tutkimus selvittää, millaisia vaiheita ympäristökonfliktin ympärillä on eletty ja kuinka konfliktia on tuotu esille yhteiskunnallisessa keskustelussa. Kolmen eri teoreettisen näkökulman (taloudellinen- ympäristöllinen- toimijakeskeinen) kautta on pyritty löytämään vastauksia siihen, miten Lipeälammen ympäristökonfliktia on viranomaisten ja paikallisten toimesta käsitelty ja kuinka mielipiteet ovat määrittyneet eri toimijoiden kesken. Lipeälammesta kärsineelle, laajan järvialueen käsi…
Effects of activated carbon ageing in three PCB contaminated sediments: Sorption efficiency and secondary effects on Lumbriculus variegatus.
2015
The sorption efficiency and possible secondary effects of activated carbon (AC) (o 63-200 μm) was studied with Lumbriculus variegatus in three PCB contaminated sediments applying long AC-sediment contact time (3 years). AC amendment efficiently reduced PCB bioavailability as determined with both, L. variegatus bioaccumulation test and passive samplers. However, dose related secondary effects of AC on egestion rate and biomass were observed (applied doses 0.25% and 2.5% sediment dry weight). The sorption capacity and secondary effects remained similar when the experiments were repeated after three years of AC-sediment contact time. Further, transmission electron microscopy (TEM) samples reve…
Rehabilitation of two northern river lamprey (Lampetra fluviatilis) populations impacted by various anthropogenic pressures : lessons learnt in the p…
2019
The pioneering work done during the past three decades in the regulated Rivers Perhonjoki and Kalajoki, Finland, to study and rehabilitate river lamprey populations is presented. The effects of various anthropogenic activities and rehabilitation measures are evaluated based on habitat surveys and long-term monitoring of larval densities, numbers of adults migrating upstream and of transformers migrating downstream. Telemetric tracking and tagging experiments were used to determine the efficacy of fishways. Lamprey populations in both rivers decreased in the 1980s and 1990s. This was linked to obstructed upstream migration of adults and deterioration of habitats for different life stages due…
Alusveden hapetuksen vaikutus pienten humusjärvien syvännepohjaeläimistön tilaan
2016
Järvien vedenlaatua ja ekologista tilaa voidaan pyrkiä parantamaan erilaisilla kunnostusmenetelmillä, joista alusveden hapetus on yksi käytetyimmistä. Alusvettä hapetetaan kierrättämällä päällysvettä pohjanläheisyyteen, ja menetelmän avulla pyritään ehkäisemään järven sisäistä kuormitusta. Hapetus kuitenkin nostaa alusveden lämpötilaa ja estää järven luontaisen kerrostumisen. Tieteellisiä tutkimuksia hapetuksen pitkäaikaisista vaikutuksista järvien tilaan on niukasti, vaikka hapetus on ollut suosittu kunnostusmenetelmä jo 1970-luvulta lähtien. Tässä tutkimuksessa tarkasteltiin kolmen keskisuomalaisen järven (Jyväsjärvi, Tuomiojärvi ja Alvajärvi) syvännepohjaeläinyhteisöissä tapahtuneita muu…
Effects of mechanical mixing on lake water quality, with special emphasis on under-ice phytoplankton
2015
The IPBES assessment report on land degradation and restoration
2018
The Assessment Report on Land Degradation and Restoration by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) provides a critical analysis of the state of knowledge regarding the importance, drivers, status, and trends of terrestrial ecosystems. The Report recognizes that combatting land degradation, which is a pervasive, systemic phenomenon occurring in all parts of the world, is an urgent priority in order to protect the biodiversity and ecosystem services that are vital to all life on Earth and to ensure human well-being. The Report identifies a mix of governance options, policies and management practices that can help support stakeholders work…
Ecology, fisheries and management of wild brown trout populations in boreal inland waters
2010
Eutrophication of aquatic ecosystems is an increasing problem, especially threatening small and shallow freshwater lakes. While the extreme inputs of nutrients (phosphorus and nitrogen) can nowadays be reduced and controlled rather efficiently, additional measures to reverse eutrophication may be needed. These often involve biomanipulation, typically mass removal of cyprinid fish. However, the success of biomanipulations has many times been limited or short lived. The reasons for this are not well known, perhaps because the more subtle impacts of biomanipulation on the ecosystem-wide processes of lakes have not been thoroughly studied. Natural abundance stable isotopes may provide a cost-ef…