0000000001288597
AUTHOR
Hanna-kaisa Lakka
Acclimation capacity and rate change through life in the zooplankton Daphnia
When a change in the environment occurs, organisms can maintain an optimal phenotypic state via plastic, reversible changes to their phenotypes. These adjustments, when occurring within a generation, are described as the process of acclimation. While acclimation has been studied for more than half a century, global environmental change has stimulated renewed interest in quantifying variation in the rate and capacity with which this process occurs, particularly among ectothermic organisms. Yet, despite the likely ecological importance of acclimation capacity and rate, how these traits change throughout life among members of the same species is largely unstudied. Here we investigate these re…
Large differences in catch per unit of effort between two minnow trap models
Background: Little is known about variation in catch per unit of effort (CPUE) in stickleback fisheries, or the factors explaining this variation. We investigated how nine-spined stickleback (Pungitius pungitius) CPUE was influenced by trap model by comparing the CPUEs of two very similar minnow trap models fished side-by-side in a paired experimental design. Results: The galvanized trap type (mean CPUE = 1.31 fish h–1) out-fished the black trap type (mean CPUE = 0.20 fish h–1) consistently, and yielded on average 81% more fish. Conclusions: The results demonstrate that small differences in trap appearance can have large impacts on CPUE. This has implications for studies designed to investi…
Measuring phenotypes in fluctuating environments
Despite considerable theoretical interest in how the evolution of phenotypic plasticity should be shaped by environmental variability and stochasticity, how individuals actually respond to these aspects of the environment within their own lifetimes remains unclear. We propose that this understanding has been hampered by experimental approaches that expose organisms to fluctuating environments (typically treatments where fluctuations in the environment are cyclical vs. erratic) for a pre‐determined duration while ensuring that the mean environment over that the entire exposure period is invariable. This approach implicitly assumes that responses to the mean and variance/predictability in the…
Äyriäis- ja nilviäistyöryhmän retki Käsivarteen elokuussa 2019
Teimme elokuussa 2019 kauan suunnitellun ja unelmoidun retken Käsivarren Lappiin. Tarkoituksena oli käydä etsimässä ja kartoittamassa Lapin uhanalaisia ja vähän havainnoituja äyriäis- ja nilviäislajeja perustuen osin hyvin vanhoihinkin havaintoihin. Hanna-Kaisa Lakka on kartoittanut Enontekiön äyriäispopulaatioita ja niiden ympäristövaatimuksia jo vuodesta 2012 alkaen. Hannu Ormio on kartoitellut nilviäisiä Kilpisjärven ympäristössä vuonna 2011 ja Katriina Könönen on havainnut ensimmäisen lehtijalkaisäyriäisensä 1990-luvulla yliopiston tunturivesikurssilla ja myöhemmin muutamia havaintoja on kertynyt myös kesäisillä lomareissuilla. Yövyimme Kilpisjärven asemalla ja kartoitimme lähialueen la…
Upper thermal threshold of Lepidurus arcticus (Branchiopoda, Notostraca) in lakes on the southern outreach of its distribution range
Qvenild T, Fjeld E, Fjellheim A, Hammar J, Hesthagen T and Lakka H-K. 2021. Upper thermal threshold of Lepidurus arcticus (Branchiopoda, Notostraca) in lakes on the southern outreach of its distribution range. Fauna norvegica 41: 50–88. The Arctic tadpole shrimp Lepidurus arcticus has a circumpolar distribution and the Scandes (Fennoscandian Mountains) marks its southernmost limit in Europe. Within this area, 391 natural and 88 regulated lakes with L. arcticus have been identified, of which 87% are above the treeline. The lakes hosting L. arcticus decrease in altitude from south to north, which results from its temperature preferences. The majority of the locations are at a lower lake air t…
Acclimation capacity and rate change through life in the zooplankton Daphnia
When a change in the environment occurs, organisms can maintain an optimal phenotypic state via plastic, reversible changes to their phenotypes. These adjustments, when occurring within a generation, are described as the process of acclimation. While acclimation has been studied for more than half a century, global environmental change has stimulated renewed interest in quantifying variation in the rate and capacity with which this process occurs, particularly among ectothermic organisms. Yet, despite the likely ecological importance of acclimation capacity and rate, how these traits change throughout life among members of the same species is largely unstudied. Here we investigate these rel…
Impacts of reduced Lepidurus arcticus availability on brown trout life history traits in a mountain reservoir
Lepidurus arcticus (the Arctic tadpole shrimp) is a vulnerable keystone species in Arctic and alpine water bodies where its occurrence and population size may influence the viability and life history traits of resident salmonids. Using data from a Norwegian mountain hydropower reservoir, Aursjoen, we illustrate how reduced availability of L. arcticus as prey resulted in the reduced condition, growth and delayed maturation of resident brown trout (Salmo trutta). We further link changes in the relative abundance of L. arcticus as prey to changing reservoir conditions, e.g. water level changes in the spring period, thereby establishing an indirect link between reservoir operation regimes and b…
Impacts of piscicide-induced fish removal on resource use and trophic diversity of lake invertebrates
Chemical eradication of non-native species has become a widely used method to mitigate the potential negative im- pacts of altered competitive or predatory dynamics on biodiversity and natural ecosystem processes. However, the re- sponses of non-target species can vary from rapid full recovery to delayed or absent recolonization, and little is known about the potential shifts in resource use and trophic diversity of native species following chemical treatments. We used a before-after-control-impact approach to study the effects of rotenone piscicide treatment on abundance and tro- phic niche of benthic invertebrates in three untreated and three treated lakes in central Norway, the latter gr…
Supplementary Results from Acclimation capacity and rate change through life in the zooplankton daphnia
Variation in parameter estimates resulting from different threshold velocities used in heat tolerance algorithm, Timm data on arithmetic scale
Jatkuvapeitteisen metsänkäsittelyn vaikutukset luonnon monimuotoisuuteen, vesistöihin, ilmastoon, virkistyskäyttöön ja metsätuhoriskeihin
Sekä jatkuvapeitteistä että jaksollista metsänkäsittelyä tehdään eri voimakkuuksilla ja erilaisin hakkuutavoin. Ei ole olemassa yksiselitteistä sääntöä, jolla voitaisiin todeta, kuuluuko jokin tietty hakkuutapa jatkuva-peitteiseen vai jaksolliseen käsittelyyn (avohakkuita lukuun ottamatta). Esimerkiksi yläharvennuksia tehdään molemmissa käsittelytavoissa. Kaikkien metsänkäsittelytapojen aiheuttama häiriö on tyypillisesti sitä voimakkaampi, mitä voimakkaampi hakkuu tehdään. Avohakkuut aiheuttavat suurimman haitallisen vaikutuksen sekä luontoon että moniin metsien tarjoamiin ekosysteemipalveluihin. Yhteiskunnan kokonais-edun kannalta jatkuvapeitteisen käsittelyn osuuden lisääminen puuntuotann…
Supplementary Results from Acclimation capacity and rate change through life in the zooplankton Daphnia
Variation in parameter estimates resulting from different threshold velocities used in heat tolerance algorithm, Timm data on arithmetic scale