Search results for "Vieraslaji"

Assessing the Impact of Road and Land Use on Species Diversity of Trees, Shrubs, Herbs and Grasses in the Mountain Landscape in Southern Africa

2022

Mountain landscape, described as a global biodiversity hotspot due to high endemism, is threatened by land-use change, including management and modification of vegetation. However, there is little knowledge about how road and land use affect plant diversity in mountains landscapes, particularly in southern Africa. Previous studies have studied the impact of the road or land use on plant species diversity separately and have concentrated on a single plant species. Here we compare the plant diversity of regenerated trees, shrubs, herbaceous plant, and grasses among Forest, Fallow, Agriculture, and Road in the Moribane Forest Reserve (MFR), in Eastern Chimanimani Mountain landscape in Mozambiq…

Trophic role of marbled crayfish in a lentic freshwater ecosystem

2019

Species’ introductions may cause severe adverse effects on freshwater ecosystems and their biota. The marbled crayfish, Procambarus virginalis Lyko, 2017, is an invasive parthenogenetically reproducing crayfish with rapid reproduction, maturation and tolerance to a wide range of environmental conditions, which was introduced to many sites across Europe during the last decade. Due to its recent speciation and limited number of field studies, the knowledge of trophic interactions of the marbled crayfish in freshwater food webs is scarce. An invaded area located in Central Europe was studied to identify the marbled crayfish food web interactions using analysis of carbon 13 C and nitrogen 15N i…

A comparison of the impacts of introduced signal crayfish and native noble crayfish in boreal lake ecosystems

2014

Invasive crayfish increase habitat connectivity

2012

Several studies have shown that distinct compartments of lake ecosystems are coupled via transportation of organic matter, nutrients and energy across habitat boundaries. Here we evaluate the potential of the invasive signal crayfish (Pacifastacus leniusculus (Dana)) to modify energy pathways in large boreal lakes. Using a stable isotope mixing model and calculation of the isotopic niches we estimated the contribution of different food sources to the diets of crayfish captured from different habitats, and from that inferred their potential to transport energy across the littoral-profundal gradient. The crayfish caught from the littoral area utilized mainly littoral food sources, whereas the…

First record of an established marbled crayfish Procambarus virginalis (Lyko, 2017) population in Estonia

2019

Invasive marbled crayfish Procambarus virginalis (Lyko, 2017) is spreading alarmingly fast across European countries and beyond. Early maturation, parthenogenetic reproduction mode and high growth rate contribute to a high potential invasiveness. Marbled crayfish can pose severe effects on native communities impacting the native crayfish populations being carrier of the crayfish plague disease caused by Aphanomyces astaci. Here we report the first record of marbled crayfish in Estonia. In total, 104 individuals were found in the artificially warm outflow channel of the cooling system of Balti Power Plant, entering to the water reservoir of the River Narva. Molecular analyses confirmed the m…

Ongelmaeläimyyden monet ja muuttuvat määrittelyt

2022

Suomeen 1900-luvun puolivälin paikkeilla levinnyt supikoira (Nyctereutes procyonoides) on herättänyt monenlaista huolta ja keskustelua yhteiskunnan eri tasoilla ja ryhmittymissä. Supikoirakannan vähentämiselle löytyy vähän vastustajia, mutta osalle tämä keskikokoinen nisäkäs näyttää olevan niin iso ongelma, että supikoirapuhe saa paikoin raivokkaita sävyjä. Tarkastelen tässä tutkimuksessa keskustelun ongelmaeläinkäsityksiä kehysanalyysillä. Käytän uusstrukturalistiseen kehikkoon sijoittuvassa tarkastelussa sanomalehtien supikoirakirjoituksia aikaväliltä 1970–2020, jolle sijoittuu myös rakennemuutosten ja ympäristöheräämisen kaltaisia suomalaista yhteiskuntaa ja sen ympäristösuhdetta uudelle…

Interannual variation in littoral benthic macroinvertebrate communities under contrasting crayfish predation in a large boreal lake

2014

Long term studies are widely used nowadays in many fields of ecology. For instance, records over years represent a valuable tool to monitor and comprehend environmental changes. In freshwater ecology, long term studies are often applied in restoration effect assessments using a before-after-control-impact design. Little is known about the long term effects of freshwater predators on their prey, for example of how crayfish as omnivorous predators affect macroinvertebrate prey communities. Bottom substrate of stony littoral shores in three sites of Lake Päijänne, in Central Finland, were sampled for macroinvertebrates (MI) during five consecutive years and identified mainly to species. Of the…

The role of agroecosystems for invasion of a generalist herbivore

2014

Vieraslajin, komealupiinin (Lupinus polyphyllus), vaikutus koiranputken (Anthriscus sylvestris) kasvun allokointiin ja siemenpainoihin

2013

Vieraslajin leviäminen uudelle alueelle luo haasteita niin vieras- kuin paikalliselle lajille. Molempien lajien on sopeuduttava ja vastattava toistensa aiheuttamiin valintapaineisiin. Koska vieraslajit ovat monesti uudessa ympäristössä voimakkaita kilpailijoita, ja siten vaikuttavat muihin lajeihin sekä ympäristöönsä voimakkaasti ja jopa haitallisesti, on mahdollista, että vieraslajin kanssa esiintyvissä paikallisissa lajeissa on havaittavissa muutoksia niiden elinkiertopiirteissä. Vaikka kilpailun tiedetään olevan yksi merkittävimpiä valintapaineita, tietoa vieraslajien vaikutuksista yksittäisiin suomalaisiin lajeihin on vähän. Tutkimalla vieraslajin aiheuttamia evolutiivisia muutoksia pai…

Cormorant predation mortality of perch (Perca fluviatilis) in coastal and archipelago areas, northern Baltic Sea

2021

Abstract Perch (Perca fluviatilis) is an important prey species of the great cormorant (Phalacrocorax carbo sinensis) in the coastal waters of the northern Baltic Sea. The annual predation mortality caused by cormorants was estimated based on the consumed numbers of perch in relation to the abundance of perch in vulnerable age groups in the sea. We used existing stock assessment data (Archipelago Sea) or a simple population model in other areas (Gulf of Finland, Bothnian Sea, and Quark), based on commercial and recreational perch catches, and estimated fishing and natural mortalities, with distributions describing our understanding about the likelihood of different values for every variable…