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1.
BMC Ecol ; 20(1): 70, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33334346

RESUMO

BACKGROUND: Earlier breeding is one of the strongest responses to global change in birds and is a key factor determining reproductive success. In most studies of climate effects, the focus has been on large-scale environmental indices or temperature averaged over large geographical areas, neglecting that animals are affected by the local conditions in their home ranges. In riverine ecosystems, climate change is altering the flow regime, in addition to changes resulting from the increasing demand for renewable and clean hydropower. Together with increasing temperatures, this can lead to shifts in the time window available for successful breeding of birds associated with the riverine habitat. Here, we investigated specifically how the environmental conditions at the territory level influence timing of breeding in a passerine bird with an aquatic lifestyle, the white-throated dipper Cinclus cinclus. We relate daily river discharge and other important hydrological parameters, to a long-term dataset of breeding phenology (1978-2015) in a natural river system. RESULTS: Dippers bred earlier when winter river discharge and groundwater levels in the weeks prior to breeding were high, and when there was little snow in the catchment area. Breeding was also earlier at lower altitudes, although the effect dramatically declined over the period. This suggests that territories at higher altitudes had more open water in winter later in the study period, which permitted early breeding also here. Unexpectedly, the largest effect inducing earlier breeding time was territory river discharge during the winter months and not immediately prior to breeding. The territory river discharge also increased during the study period. CONCLUSIONS: The observed earlier breeding can thus be interpreted as a response to climate change. Measuring environmental variation at the scale of the territory thus provides detailed information about the interactions between organisms and the abiotic environment.


Assuntos
Hidrologia , Passeriformes , Animais , Cruzamento , Mudança Climática , Ecossistema
2.
Ecol Evol ; 10(15): 8153-8165, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788968

RESUMO

Covariation in species richness and community structure across taxonomical groups (cross-taxon congruence) has practical consequences for the identification of biodiversity surrogates and proxies, as well as theoretical ramifications for understanding the mechanisms maintaining and sustaining biodiversity. We found there to exist a high cross-taxon congruence between phytoplankton, zooplankton, and fish in 73 large Scandinavian lakes across a 750 km longitudinal transect. The fraction of the total diversity variation explained by local environment alone was small for all trophic levels while a substantial fraction could be explained by spatial gradient variables. Almost half of the explained variation could not be resolved between local and spatial factors, possibly due to confounding issues between longitude and landscape productivity. There is strong consensus that the longitudinal gradient found in the regional fish community results from postglacial dispersal limitations, while there is much less evidence for the species richness and community structure gradients at lower trophic levels being directly affected by dispersal limitation over the same time scale. We found strong support for bidirectional interactions between fish and zooplankton species richness, while corresponding interactions between phytoplankton and zooplankton richness were much weaker. Both the weakening of the linkage at lower trophic levels and the bidirectional nature of the interaction indicates that the underlying mechanism must be qualitatively different from a trophic cascade.

3.
Ecol Evol ; 8(8): 4065-4073, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29721280

RESUMO

Interactions between birds and fish are often overlooked in aquatic ecosystems. We studied the influence of Atlantic salmon and brown trout on the breeding population size and reproductive output of the white-throated dipper in a Norwegian river. Acidic precipitation led to the extinction of salmon, but salmon recolonized after liming was initiated in 1991. We compared the dipper population size and reproductive output before (1978-1992) and after (1993-2014) salmon recolonization. Despite a rapid and substantial increase in juvenile salmon, the breeding dipper population size and reproductive output were not influenced by juvenile salmon, trout, or total salmonid density. This might be due to different feeding strategies in salmonids and dippers, where salmonids are mainly feeding on drift, while the dipper is a benthic feeder. The correlation between the size of the dipper population upstream and downstream of a salmonid migratory barrier was similar before and after recolonization, indicating that the downstream territories were not less attractive after the recolonization of salmon. Upstream dipper breeding success rates declined before the recolonization event and increased after, indicating improved water quality due to liming, and increasing invertebrate prey abundances and biodiversity. Surprisingly, upstream the migratory barrier, juvenile trout had a weak positive effect on the dipper population size, indicating that dippers may prey upon small trout. It is possible that wider downstream reaches might have higher abundances of alternative food, rending juvenile trout unimportant as prey. Abiotic factors such as winter temperatures and acidic precipitation with subsequent liming, potentially mediated by prey abundance, seem to play the most important role in the life history of the dipper.

4.
Sci Adv ; 3(2): e1602298, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28164157

RESUMO

Climate change will affect the population dynamics of many species, yet the consequences for the long-term persistence of populations are poorly understood. A major reason for this is that density-dependent feedback effects caused by fluctuations in population size are considered independent of stochastic variation in the environment. We show that an interplay between winter temperature and population density can influence the persistence of a small passerine population under global warming. Although warmer winters favor an increased mean population size, density-dependent feedback can cause the local population to be less buffered against occasional poor environmental conditions (cold winters). This shows that it is essential to go beyond the population size and explore climate effects on the full dynamics to elaborate targeted management actions.


Assuntos
Aquecimento Global , Modelos Biológicos , Dinâmica Populacional , Estações do Ano , Humanos
5.
Sci Total Environ ; 478: 36-47, 2014 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-24530583

RESUMO

Numerous boreal lakes across the Northern Hemisphere recovering from acidification are experiencing a simultaneous increase in chloride (Cl) concentrations from road salting. Increasing Cl may have profound effects on the lake ecosystem. We examine if an increase in Cl from road salting has modified the recovery of the microcrustacean community in an acidified boreal lake undergoing chemical recovery (study lake). Results from the study lake were compared with an acidified "reference lake". The community changed during the study period in the study lake mainly driven by the reduction in acidification pressure. Despite the community changes and an increase in species richness, the absence of several acid sensitive species, previously occurring in the lake, indicates a delayed biological recovery relative to the chemical recovery. Moreover, changes in occurrence of acid sensitive and acid tolerant species indicated that the biological recovery was slower in the study lake compared to the "reference". Although recurrent episodes of high aluminum and low pH and decreasing Ca are likely important factors for the delay, these do not explain, for instance, the shift from Cyclops scutifer to Bosmina longispina in the study lake. Although the contribution of Cl was not significant, the correlation between Cl and the variation in microcrustacean community was twice as high in the study lake compared to the "reference". We argue that small, sheltered forest lakes may be especially sensitive to increased Cl levels, through changes in pattern of stratification, thus providing a mechanism for the shift from C. scutifer to B. longispina. The reduction of the acidification pressure seems to override the Cl effects on microcrustaceans at low Cl levels in salt-affected lakes recovering from acidification. However, prognoses for growing traffic and increasing road salting raise concern for many recovering lakes located in proximity to roads and urbanized areas.


Assuntos
Chuva Ácida , Lagos/química , Cloreto de Sódio/análise , Poluentes Químicos da Água/análise , Animais , Automóveis , Cladóceros/classificação , Cladóceros/crescimento & desenvolvimento , Copépodes/classificação , Copépodes/crescimento & desenvolvimento , Ecossistema , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Cloreto de Sódio/toxicidade , Poluentes Químicos da Água/toxicidade
6.
Environ Pollut ; 186: 115-25, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24370669

RESUMO

The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. The fitted results give toxic potencies increasing in the order H(+) < Al < Cu < Zn < Ni. In general, observed species richness is lower than predicted, but in some instances agreement is close, and is rarely higher than predictions. The model predicts recovery in agreement with observations for three regions, namely Sudbury (Canada), Bohemian Forest (Czech Republic) and a subset of lakes across Norway, but fails to predict observed recovery from acidification in Adirondack lakes (USA).


Assuntos
Monitoramento Ambiental/métodos , Lagos/química , Metais/toxicidade , Modelos Químicos , Poluentes Químicos da Água/toxicidade , Zooplâncton/efeitos dos fármacos , Animais , Canadá , Crustáceos/classificação , Crustáceos/efeitos dos fármacos , Crustáceos/crescimento & desenvolvimento , República Tcheca , Noruega , Prótons , Zooplâncton/classificação , Zooplâncton/crescimento & desenvolvimento
7.
Int J Biometeorol ; 55(6): 797-804, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21710281

RESUMO

To study the ecological and evolutionary effects of climate change on timing of annual events, scientists need access to data that have been collected over long time periods. High-quality long-term phenology data are rare and costly to obtain and there is therefore a need to extract this information from other available data sets. Many long-term studies on breeding birds include detailed information on individually marked parents and offspring, but do not include information on timing of breeding. Here, we demonstrate how a study of repeated standard measurements of white-throated dipper Cinclus cinclus nestlings in our study system in southernmost Norway can be used for modeling nestling growth, and how this statistical model can be used to estimate timing of breeding for birds with sparser data. We also evaluate how the accuracies of nestling growth models based on different morphological traits (mass and feather length) differ depending on the nestling age, present user guidelines and demonstrate how they can be applied to an independent data set. In conclusion, the approach presented is likely to be useful for a wide variety of species, even if the preferred measurement may differ between species.


Assuntos
Evolução Biológica , Ecossistema , Comportamento de Nidação/fisiologia , Passeriformes/fisiologia , Animais , Peso Corporal , Cruzamento , Mudança Climática , Modelos Biológicos , Modelos Estatísticos , Noruega , Passeriformes/crescimento & desenvolvimento , Fatores de Tempo
8.
J Anim Ecol ; 80(1): 235-43, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20880020

RESUMO

1. Climate change may have profound consequences for many organisms. We have studied fluctuations in a population of the white-throated dipper Cinclus cinclus during 31 years (1978-2008) in a river system in southern Norway in relation to both large-scale and local weather conditions occurring during the non-breeding season. 2. Multiple regression and partial least squares regression were used to model the growth rate of the population, accounting for population size in the previous year. 3. Population growth was influenced by North Atlantic Oscillation (NAO), mean winter temperature, precipitation and timing of ice formation on the main lake in the river system in autumn. These variables explained 84% of the variation in population growth over the 31-year study period. 4. Local winter conditions played a prominent role in explaining the population fluctuations, which is plausible because the dipper depends on open water for foraging. In the study area, winters can be harsh and rivers and lakes may freeze and severely affect the subsequent population size of the dipper in spring. 5. The breeding population of the dipper does not seem yet to have reached a level where all possible territories in the area have been occupied, even after mild winters, and the estimated carrying capacity is also decidedly lower (66 breeding pairs) than the number of available territories. If the trend of milder winters continues, the population might increase in the future. However, strong climate variation is expected to continue in the future, and hence periods of rapid growth of the dipper population will probably be followed by severe declines.


Assuntos
Mudança Climática , Passeriformes/fisiologia , Animais , Ecossistema , Gelo , Dinâmica Populacional , Chuva , Estações do Ano , Temperatura , Fatores de Tempo
9.
Ecology ; 87(2): 433-43, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16637368

RESUMO

Pelagic crustacean zooplankton were collected from 336 Norwegian lakes covering a wide range of latitude, altitude, lake area, mean depth, production (as chlorophyll a), and fish community structure. Mean zooplankton species richness during the ice-free season was generally low at high latitudes and altitudes. Further, lower species richness was recorded in western lakes, possibly reflecting constraints on migration and dispersal. However, despite obvious spatial limitations, geographic boundaries were only weak predictors of mean zooplankton richness. Similarly, lake surface area did not contribute positively to mean richness such as seen in other ecosystem surveys. Rather, intrinsic factors such as primary production and fish community (planktivore) structure were identified by regression analysis as the major predictors of zooplankton diversity, while a positive correlation was observed between species richness and total zooplankton biomass. However, in spite of a large number of variables included in this study, the predictive power of multiple regression models was modest (<50% variance explained), pointing to a major role for within-lake properties, as yet unidentified intrinsic forces, stochasticity, or dispersal as constraints on zooplankton diversity in these lakes.


Assuntos
Zooplâncton/classificação , Animais , Ecossistema , Água Doce , Modelos Lineares , Noruega , Especificidade da Espécie
10.
Ambio ; 32(3): 208-13, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12839197

RESUMO

We identify littoral microcrustacean indicators of acidification in 2 surveys of Canadian Shield lakes conducted 10 years apart. We found a total of 90 cladoceran and copepod species with richness increasing severalfold from acidic to nonacidic lakes. The fauna of the nonacidic lakes differed between the surveys. The 1987 survey employed activity traps, and caught more littoral taxa than the more recent, net-haul-based survey. Similar faunas were identified in the acidified lakes in both surveys, and several good indicator species were identified. For example, Acanthocycops vernalis was restricted to lakes with pH < 6. Sinobosmina sp. was very common but only in lakes with pH > 4.8. Tropocyclops extensus, Mesocyclops edax, and Sida crystallina were commonly found but only at pH > 5, and Chydorus faviformis only at pH > 5.9. These indicators showed promise in gauging the early stages of recovery from acidification in 3 lakes that were included in both surveys.


Assuntos
Chuva Ácida/efeitos adversos , Cladóceros , Copépodes , Animais , Canadá , Coleta de Dados , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Dinâmica Populacional , Abastecimento de Água
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