Expected Climate Change Scenarios Research Articles

Future impacts of climate change on black spruce growth and mortality: review and challenges

Black spruce ( Picea mariana (Mill.) B.S.P.) is the dominant conifer species across a large part of North American boreal forests, providing many goods and services essential to human activities, and playing a major climatic role through the global carbon cycle. However, a comprehensive synthesis of the effects of climate change on black spruce has not yet been undertaken. The dynamics of black spruce are influenced by various living (biotic) and non-living (abiotic) factors, as well as their combined effects, which are particularly responsive to changes in climate. Climate change predictions suggest that northern ecosystems will experience the world's most significant impact. Therefore, black spruce is likely to undergo profound disruptions in its growth and mortality rate in the next few decades, resulting in significant changes in forestry and carbon storage. However, these changes will not be uniform throughout the entire distribution of the species. Future changes in temperature and precipitation will create more stress for water availability in the boreal forests of western and central North America than in their eastern counterparts. Thus, significant longitudinal and latitudinal gradients in tree growth and mortality variability are expected throughout the range of the species. This literature review aims to summarise the impacts of climate change on individual tree growth and mortality of this major species. While enhanced black spruce productivity could occur through both increased air temperature and nitrogen mineralisation in the soil, moisture limitation in central and western North America will result in significant growth reduction and mortality events across these regions. Conversely, under the expected climate change scenarios, black spruce forests may be more resilient in eastern North America, where climatic conditions appear more suitable, particularly in their northernmost range. In this review, we identify current research gaps for some disturbances, which should be addressed to better understand the impact of climate change on black spruce. Finally, we identify issues associated with sustainable forest management and the maintenance of black spruce under projected future climate changes.

Warming appears as the main risk of non-adaptedness for western Mediterranean relict fir forests under expected climate change scenarios.

Circum-Mediterranean firs are considered among the most drought-sensitive species to climate change. Understanding the genetic basis of trees' adaptive capacity and intra-specific variability to drought avoidance is mandatory to define conservation measures, thus potentially preventing their extinction. We focus here on Abies pinsapo and Abies marocana, both relict tree species, endemic from south Spain and north Morocco, respectively. A total of 607 samples were collected from eight nuclei: six from Spanish fir and two from Moroccan fir. A genotyping by sequencing technique called double digestion restriction site-associated DNA sequencing (ddRAD-seq) was performed to obtain a genetic matrix based on single-nucleotide polymorphisms (SNPs). This matrix was utilized to study the genetic structure of A. pinsapo populations and to carry out selection signature studies. In order to understand how Spanish fir and Moroccan fir cope with climate change, genotype-environment associations (GEAs) were identified. Further, the vulnerability of these species to climate variations was estimated by the risk of non-adaptedness (RONA). The filtering of the de novo assembly of A. pinsapo provided 3,982 SNPs from 504 out of 509 trees sequenced. Principal component analysis (PCA) genetically separated Grazalema from the rest of the Spanish populations. However, FST values showed significant differences among the sampling points. We found 51 loci potentially under selection. Homolog sequences were found for some proteins related to abiotic stress response, such as dehydration-responsive element binding transcription factor, regulation of abscisic acid signaling, and methylation pathway. A total of 15 associations with 11 different loci were observed in the GEA studies, with the maximum temperature of the warmest month being the variable with the highest number of associated loci. This temperature sensitivity was also supported by the risk of non-adaptedness, which yielded a higher risk for both A. pinsapo and A. marocana under the high emission scenario (Representative Concentration Pathway (RCP) 8.5). This study sheds light on the response to climate change of these two endemic species.

Feeding response and dynamic of intoxication and detoxification in two populations of the flat oyster Ostrea chilensis exposed to paralytic shellfish toxins (PST)

Juvenile oysters (Ostrea chilensis) from two populations (Quempillén estuary and Pullinque bay) were exposed to a toxic diet containing paralytic shellfish toxins (PST), produced by Alexandrium catenella, followed by a detoxification period. Feeding behaviour, toxin profile, dynamics of intoxication/detoxification, and survival were evaluated over the entire experimental period. Both populations reduced their feeding rates during the 30-day exposure to the toxic diet. This negative effect was reversible when the diet was switched to the non-toxic one. Oysters from the estuary accumulated PST more rapidly than the population from the bay, suggesting their increased ability to cope with more adverse conditions. Both populations showed low detoxification capacity. Survival was significantly higher in oysters from the estuary, compared to those from the bay. Due to the increasing frequency and intensity of A. catenella blooms in southern Chile, it is necessary to better understand the responses of O. chilensis in different environments. This is important not only because of the ecological and commercial relevance of the bivalve, but also in consideration of expected climate change scenarios, where the new environmental conditions could favour the frequency and intensity of harmful algal bloom events.

Implications of climate change on the distribution and conservation of Cabo Verde endemic trees

Climate change is one of the most significant challenges to biodiversity conservation, particularly in dry tropical islands, such as the Cabo Verde archipelago where only three endemic tree taxa occur – Dracaena draco subsp. caboverdeana, Phoenix atlantica and Sideroxylon marginatum – all classified as threatened. The main goal of this study was to predict the possible shifts in the climatically suitable habitat ranges for Cabo Verdean endemic tree species under different climate change scenarios. We applied species distribution models (SDMs) to the available occurrence data, and projected the distribution of the three taxa for 2050 and 2080, according to the expected climate change scenarios. The best models were obtained using the Random Forest algorithm; they showed that, by 2080, the suitable habitat for Dracaena draco subsp. caboverdeana and Sideroxylon marginatum will have decreased by 28% and 34%, respectively; conversely, the suitable habitat will have increased by 59% for Phoenix atlantica, the taxon best adapted to arid conditions. Additionally, Santo Antão is the island where endangered trees are more encompassed by protected areas. Overall, this study contributed with new integrated data to support the design and implementation of a strategic plan to promote the conservation and ecological value of Cabo Verde endemic trees in this climatically vulnerable country.

Complementary Differences in Primary Production and Phenology among Vegetation Types Increase Ecosystem Resilience to Climate Change and Grazing Pressure in an Iconic Mediterranean Ecosystem

Plant primary production is a key factor in ecosystem dynamics. In environments with high climatic variability such as the Mediterranean region, plant primary production shows strong seasonal and inter-annual fluctuations, which both drive and interplay with herbivore grazing. Knowledge on the responses of different vegetation types to the variability in both rainfall and grazing pressure by wild and domestic ungulates is a necessary starting point for the sustainable management of these ecosystems. In this work we combine a 15 year series of remote sensing data on plant production (NDVI) with meteorological (daily precipitation data) and ungulate abundance (annual counts of four species of wild and domestic ungulates: red deer, fallow deer, cattle, and horses) in an iconic protected area (the Doñana National Park, SW Spain) to (i) estimate the impact of intra- and inter-annual variation in rainfall and herbivore pressure on primary production, for each of four main vegetation types; and (ii) evaluate the potential impact of different policy (i.e., herbivore management) strategies under expected climate change scenarios. Our results show that the production of different vegetation types differed strongly in their responses to phenology (a surrogate of the effect of climatology on vegetation development), water availability (rainfall accumulated until the phenological peak), and grazing pressure. Although the density of domestic ungulates shows a linear, negative effect on the primary production of three of the four vegetation types, differences in primary production and phenology among vegetation types increase ecosystem resilience to both climatological variability and grazing pressure. Such resilience may, however, be reduced under the conditions predicted by climate change models, if the moderate predicted reduction in rainfall levels combines with moderate to high densities of domestic ungulates, resulting in important reductions in primary production that may compromise plant regeneration, leading to irreversible degradation. New management strategies taking advantage of habitat heterogeneity and phenological alternation, more flexible stocking rates, and the redistribution of management units should be considered to mitigate these effects. The use of available remote sensing data and techniques in combination with statistical models represents a valuable tool for developing, monitoring, and refining such strategies.

Hydrologic Analysis of an Intensively Irrigated Area in Southern Peru Using a Crop-Field Scale Framework

Majes is one of the largest agricultural areas in the Arequipa region (southern Peru). Low seasonal precipitation and increasing water demands for agricultural irrigation, industry, and human consumption have made water supply projections a major concern. Agricultural development is becoming more extensive in this dry, sunny climate where crops can be grown year-round. However, because this type of project usually involves significant perturbations to the regional water cycle, understanding the effects of irrigation on local hydrology is crucial. Based on the watershed-scale Soil and Water Assessment Tool (SWAT), this investigation focuses on the impacts of intensive irrigation on hydrological responses in the Majes region. This study is unique because we allow for crop-field scale input within our regional-scale model to provide information at this smaller scale, which is important to inform local stakeholders and decision makers. Each hydrologic response unit (HRU) was generated to represent an individual crop field, so that management practices could be applied according to real-world scenarios. The management file of each HRU was modified to include different operation schedules for crop rotation, irrigation, harvest, and tillage. The model was calibrated and validated against monthly observed stream discharge during the 2009–2020 period. Additionally, evapotranspiration, irrigation water volume, and daily stream discharge downstream of the local river (Siguas) were used to verify the model performance. A total of 49 sub-basins and 4222 HRUs were created, with 3000 HRUs designated to represent individual crop fields. The simulation results revealed that infiltration from agricultural activities in Majes represents the majority of annual groundwater return flow, which makes a substantial contribution to streamflow downstream of the Siguas River. Simulations also suggested that groundwater flow processes and the interactions between surface and groundwater have a major impact on the water balance of the study area. Additionally, climate variability had a higher impact on surface runoff than on groundwater return flow, illustrating that the groundwater component in the study area is important for future water resources resiliency under expected climate change scenarios. Finally, there is a need to perform a follow-up implementation to provide a guideline for decision-makers to assess future sustainable water resources management under varying climatic conditions for this arid irrigated system.

Global bioclimatic suitability for the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), and potential co-occurrence with major host crops under climate change scenarios

The fall armyworm, Spodoptera frugiperda, is a highly invasive species native to North America that is rapidly spreading to other parts of the world. Since its first discovery outside its native range, the species has rapidly spread to more than 26 countries in Africa and has been recently discovered in India, demonstrating its high potential to spread and invade. This species can have massive damage to crops, especially maize, posing major socioeconomic challenges. While its spread is attributed to transportation in fruits and vegetables, its invasiveness is attributed to its high capacity to adapt in different environments. With expected climate change scenarios, it is possible that this species will invade other areas to the planet, thus increasing the damage to major agricultural crops. This paper aims to understand the global potential for the spread of the species and its associated impacts on major host plants, globally. For this, the article is based on modelling the distribution of species, combining records of occurrence of species globally and bioclimatic variables to identify the areas that are climatically suitable for species in present and future scenarios under climate change. Simulations indicate that there is an enormous climatic potential for the spread of the species, with potential increases between 12 and 44% in the future, mostly affecting border areas between the USA and Canada, Sub-Saharan Africa and central Europe. This spread will increase the potential for interactions between the fall armyworm and its main host plants, thus increasing the potential crop damage globally.

Catastrophic Mortality, Allee Effects, and Marine Protected Areas

For many species, reproductive failure may occur if abundance drops below critical Allee thresholds for successful breeding, in some cases impeding recovery. At the same time, extreme environmental events can cause catastrophic collapse in otherwise healthy populations. Understanding what natural processes and management strategies may allow for persistence and recovery of natural populations is critical in the face of expected climate change scenarios of increased environmental variability. Using a spatially explicit continuous-size fishery model with stochastic dispersal parameterized for abalone-a harvested species with sedentary adults and a dispersing larval phase-we investigated whether the establishment of a system of marine protected areas (MPAs) can prevent population collapse, compared with nonspatial management when populations are affected by mass mortality from environmental shocks and subject to Allee effects. We found that MPA networks dramatically reduced the risk of collapse following catastrophic events (75%-90% mortality), while populations often continued to decline in the absence of spatial protection. Similar resilience could be achieved by closing the fishery immediately following mass mortalities but would necessitate long periods without catch and therefore economic income. For species with Allee effects, the use of protected areas can ensure persistence following mass mortality events while maintaining ecosystem services during the recovery period.

The ``-omics’’ contributions to the understanding of mycotoxin production under diverse environmental conditions

Extreme environmental changes and fluctuations mainly driven by climate change will have a profound effect on natural food contaminants. Among these contaminants mycotoxins will be very important due the high adaptability of the producing fungal genera to the forecasted conditions. The availability of modern, high through-put –omic techniques, including genomics, transcriptomics, metagenomics, proteomics and metabolomics has facilitated a rapid expansion of data on the biology of mycotoxigenic fungi. This has facilitated a significant increase in our knowledge of the biological, biochemical and biophysical molecular processes regulating the production of mycotoxins, and the adaptation of these fungi to environmental stresses. In this paper we highlight recent advances where -omics approaches have been used and where they have contributed to the knowledge on how mycotoxigenic fungi adapt to diverse interacting environmental conditions and their relationship with phenotypic toxin production. We also highlight potential future directions where these approaches can be effectively utilised for the development of minimisation strategies in the context of expected climate change scenarios and the food security agenda.

Hydrological assessment of atmospheric forcing uncertainty in the Euro-Mediterranean area using a land surface model

Abstract. Physically consistent descriptions of land surface hydrology are crucial for planning human activities that involve freshwater resources, especially in light of the expected climate change scenarios. We assess how atmospheric forcing data uncertainties affect land surface model (LSM) simulations by means of an extensive evaluation exercise using a number of state-of-the-art remote sensing and station-based datasets. For this purpose, we use the CO2-responsive ISBA-A-gs LSM coupled with the CNRM version of the Total Runoff Integrated Pathways (CTRIP) river routing model. We perform multi-forcing simulations over the Euro-Mediterranean area (25–75.5∘ N, 11.5∘ W–62.5∘ E, at 0.5∘ resolution) from 1979 to 2012. The model is forced using four atmospheric datasets. Three of them are based on the ERA-Interim reanalysis (ERA-I). The fourth dataset is independent from ERA-Interim: PGF, developed at Princeton University. The hydrological impacts of atmospheric forcing uncertainties are assessed by comparing simulated surface soil moisture (SSM), leaf area index (LAI) and river discharge against observation-based datasets: SSM from the European Space Agency's Water Cycle Multi-mission Observation Strategy and Climate Change Initiative projects (ESA-CCI), LAI of the Global Inventory Modeling and Mapping Studies (GIMMS), and Global Runoff Data Centre (GRDC) river discharge. The atmospheric forcing data are also compared to reference datasets. Precipitation is the most uncertain forcing variable across datasets, while the most consistent are air temperature and SW and LW radiation. At the monthly timescale, SSM and LAI simulations are relatively insensitive to forcing uncertainties. Some discrepancies with ESA-CCI appear to be forcing-independent and may be due to different assumptions underlying the LSM and the remote sensing retrieval algorithm. All simulations overestimate average summer and early-autumn LAI. Forcing uncertainty impacts on simulated river discharge are larger on mean values and standard deviations than on correlations with GRDC data. Anomaly correlation coefficients are not inferior to those computed from raw monthly discharge time series, indicating that the model reproduces inter-annual variability fairly well. However, simulated river discharge time series generally feature larger variability compared to measurements. They also tend to overestimate winter–spring high flows and underestimate summer–autumn low flows. Considering that several differences emerge between simulations and reference data, which may not be completely explained by forcing uncertainty, we suggest several research directions. These range from further investigating the discrepancies between LSMs and remote sensing retrievals to developing new model components to represent physical and anthropogenic processes.

Growth and mortality of mangrove seedlings in the wettest neotropical mangrove forests during ENSO: Implications for vulnerability to climate change

Assessing factors affecting growth and mortality of mangrove seedlings, the critical transition between propagule dispersal and recruitment to the sapling state, is crucial to understand and predict the fate of mangrove forests in our changing climate. This work aimed to understand seedling’s responses to contrasting temperature and precipitation regimes and analyze consequences for the persistence of these ecosystems under expected climate change scenarios. Growth rate and mortality of seedlings were monitored monthly in an array of mangrove forests located along a tidal and salinity gradient in the central Pacific coast of Colombia, one of the rainiest places on Earth. Seedlings were monitored from January to December 2016, coinciding with a major El Niño (EN) episode and the abrupt transition to La Niña (LN) conditions. Seedling growth rates were generally low and observed spatial patterns generally mirrored interspecific differences in the tolerance to stress induced by salinity and inundation levels. Seedlings in basin forests showed higher growth rates than those in riverine and fringe forests. Mortality was not different among species and unexpectedly low, considering the rates reported in the literature and the supposedly stressful conditions associated with the EN-LN cycle. According to our analyses the magnitude of local anomalies in air temperature and precipitation throughout the EN-LN cycle can be stronger than those expected locally for 2071–2100 in relation to global climate change. Current and expected shifts in precipitation regimes seem the main macroclimatic drivers of ecological changes in mangrove forests thriving in the Pacific coast of Colombia.

Detecting elusive aspects of wildlife ecology using drones: New insights on the mating dynamics and operational sex ratios of sea turtles

Abstract Offspring and breeding (operational) sex ratios (OSR) are a key component of demographic studies. While offspring sex ratios are often relatively easy to measure, measuring OSRs is often far more problematic. Yet, highly skewed OSRs, and a lack of male–female encounters, may be an important extinction driver. Using loggerhead sea turtles (Caretta caretta) as a case study, we showed the utility of drones, i.e. unmanned aerial vehicles (UAVs), to distinguish adult males and females in a marine breeding area, using a combination of morphological characteristics (tail length) and behavioural differences (active mating, courting and searching by males versus resting by females). Through repeated surveys, we documented seasonal changes in the OSR. While the number, and ratio, of males and females on the breeding grounds changed massively, the ratio of receptive females (derived from the rate of influx of new individuals to the area) to breeding males remained close to 1:1 for much of the period before nesting commenced. Hence, we show how large imbalances in the number of adult males and females may translate into relatively balanced OSRs. Our results suggest that the departure of males from the breeding grounds is linked to a decline in female receptivity, with female sea turtles being known to store sperm to ensure high clutch fertility throughout the nesting season. In conclusion, while we detected up to three times more females than males at the breeding ground, at present, OSRs appear stable. However, because most males breed annually (vs. biannually by females), there might only be c. 100 males in the adult population (i.e. adult sex ratio of 1:7.5), which might become further skewed under expected climate change scenarios; thus, we need to identify the minimum number of males required to prevent extinction. Finally, we highlight the use of UAVs for assessing the mating dynamics of other marine, terrestrial or avian species, in which adults might exhibit visually detectable differences, such as sexual dimorphism, external body characteristics or grouping tendencies. A plain language summary is available for this article.

Interactive effects of competition and water availability on above- and below-ground growth and functional traits of European beech at juvenile level

European beech (Fagus sylvatica) is one of the most important commercial tree species in Europe. This species is known to suffer from strong intraspecific competition for above- and below-ground resources and recent studies suggest that mixing beech with other species enhances its growth. European Beech is also known to be very sensitive to drought and natural regeneration of this species is therefore threatened under expected climate change scenarios. Whether beech regeneration under future climate conditions could be favoured in mixed forests is still unknown. In the present study, we analysed how species interactions affect the response of beech seedlings to drought. We tested the followings hypotheses: (i) competitor presence and identity impact seedling performance, and (ii) water availability influences the strength and nature of the interactions. In a greenhouse pot experiment, beech seedlings were grown either alone or in the presence of one competitor seedling (beech, sessile oak, Scots pine). A drought treatment was applied to half of the pots and the other half was well-watered. After one growing season, the seedlings were harvested and above- and below-ground growth and functional traits were measured. Under well-watered conditions, functional traits and growth allocation favouring roots indicate that competition occurred mainly for soil resources. Specific fine root length as clearly altered by the presence of pine only, probably through allelopathy or soil acidification. Drought, however, had a strong impact on beech seedling performance whatever the treatment. Drought decreased the importance of negative interactions between seedlings and a positive interaction even occurred between beech and oak. Our results suggest that under the drier climatic conditions expected in the future, naturally regenerating European beech in mixtures with oak may be advantageous for beech seedling survival and growth. In contrast, favouring regeneration or developing plantations which include beech and pine seems less advantageous.

Statistical integration of tracking and vessel survey data to incorporate life history differences in habitat models.

Habitat use is often examined at a species or population level, but patterns likely differ within a species, as a function of the sex, breeding colony, and current breeding status of individuals. Hence, within-species differences should be considered in habitat models when analyzing and predicting species distributions, such as predicted responses to expected climate change scenarios. Also, species' distribution data obtained by different methods (vessel-survey and individual tracking) are often analyzed separately rather than integrated to improve predictions. Here, we eventually fit generalized additive models for Streaked Shearwaters Calonectris leuconelas using tracking data from two different breeding colonies in the Northwestern Pacific and visual observer data collected during a research cruise off the coast of western Japan. The tracking-based models showed differences among patterns of relative density distribution as a function of life history category (colony, sex, and breeding conditions). The integrated tracking-based and vessel-based bird count model incorporated ecological states rather than predicting a single surface for the entire species. This study highlights both the importance of including ecological and life history data and integrating multiple data types (tag-based tracking and vessel count) when examining species-environment relationships, ultimately advancing the capabilities of species distribution models.

Soil salinization as a threat to the sustainability of deficit irrigation under present and expected climate change scenarios

Deficit irrigation (DI) strategies using moderately saline waters save water, but may enhance soil salinization. Based on data gathered during years 2007–2012 in three drip-irrigated grapevine, peach, and nectarine crops subjected to several irrigation and soil-mulching treatments, we assessed trends in root-zone soil salinity [saturation extract electrical conductivity (ECe)], related the changes in soil salinity (ΔECe) to field-wide leaching fraction (LF), evaluated management strategies for soil salinity control, and examined the sustainability of DI strategies under present and expected climate change (CC) scenarios in the Middle Ebro River Basin (ERB, Spain). ECe increased in 82 % of the irrigation seasons and decreased in 75 % of the non-irrigation seasons examined. Soil salinization trends were not apparent during the study years due to these annual salt accumulation–salt leaching cycles. ECe increases were higher in the more severe DI treatments and in the geotextile-mulched soil and lower in the full and less severe irrigation treatments and in the organic-mulched soil. As expected, ΔECe and LF were linearly and negatively correlated (P < 0.01), indicating that soil salinization increased with decreasing LF. These linear relationships provided a way to evaluate best management strategies (increased irrigation, rainfall harvesting, and soil mulching) for soil salinity control. These strategies decreased soil salinization, but did not guarantee the sustainability of severe DIs in the study area. The application of these relationships to the CC precipitation and crop evapotranspiration projections in the ERB shows that the examined DI strategies will be unsustainable due to soil salinization.

Linking climate, gross primary productivity, and site index across forests of the western United States

Assessing forest productivity is important for developing effective management regimes and predicting future growth. Despite some important limitations, the most common means for quantifying forest stand-level potential productivity is site index (SI). Another measure of productivity is gross primary production (GPP). In this paper, SI is compared with GPP estimates obtained from 3-PG and NASA’s MODIS satellite. Models were constructed that predict SI and both measures of GPP from climate variables. Results indicated that a nonparametric model with two climate-related predictor variables explained over 68% and 76% of the variation in SI and GPP, respectively. The relationship between GPP and SI was limited (R2 of 36%–56%), while the relationship between GPP and climate (R2 of 76%–91%) was stronger than the one between SI and climate (R2 of 68%–78%). The developed SI model was used to predict SI under varying expected climate change scenarios. The predominant trend was an increase of 0–5 m in SI, with some sites experiencing reductions of up to 10 m. The developed model can predict SI across a broad geographic scale and into the future, which statistical growth models can use to represent the expected effects of climate change more effectively.

The distribution of littoral chironomids along an altitudinal gradient in High Tatra Mountain lakes: Could they be used as indicators of climate change?

We studied assemblages of littoral chironomids from three alpine lakes in the High Tatra Mountains (Slovakia) along an altitude range of 1725-2157 m. The study sites were selected in order to em- phasize differences in their thermal regimes. Littoral samples were taken quantitatively in the ice-free seasons of 2000 and 2001. In total, 3468 chironomid larvae and pupae were collected and 29 taxa were identified. Some parameters of the littoral chironomid assemblages showed clear patterns along the altitude gradient. The number of taxa and Shannon diversity increased markedly with decreasing altitude. Density, however, did not show any correlation with altitude. Even though gatherers highly dominated in all sites, their relative abundance decreased with decreasing altitude. The ratio of scrapers and predators correlated negatively with altitude. According to the results of a Detrended Correspondence Analysis, Pseudodiamesa arctica and Micropsectra radialis were chosen as indicator species for alpine lakes > 2000 m a.s.l. Typical subalpine lake inhabitants are Zavrelimyia sp., Prodiamesa olivacea, Corynoneura scutellata group, Cricotopus polaris, Micropsectra bavarica and Paratanytarsus austriacus. A single species, Micropsectra junci, seemed to be char- acteristic of alpine lakes < 2000 m a.s.l. This gradient lake concept could be used to predict changes in mountain lake fauna under expected climate change scenarios. Generally, an upward shift of subalpine species would be expected. The thermal regime of lakes, however, also depends on several local factors. Consequently, the schemes outlined here would not be valid for the entire Tatra lake district.