Climate Refugia Research Articles

Climate refugia in the Great Barrier Reef may endure into the future.

Although global warming is leading to more frequent mass coral bleaching events worldwide, parts of the Great Barrier Reef (GBR) have consistently escaped severe coral bleaching. Modeling and satellite observations show that climate refugia are created by the upwelling of cooler water to the surface through the interactions of tides and currents with dense reef structures. Here, we use a high-resolution nested regional ocean model to investigate the future status of two relatively large refugia. On the basis of model projections under a high-emission scenario, we find that the upwelling mechanisms will stay active in a warming climate, and these regions are likely to remain approximately more than 1°C cooler than surrounding waters until at least into the 2080s, providing thermal relief to corals. Identification and protection of these refugia may help facilitate reef survival and related biodiversity preservation by allowing their corals time to acclimatize and adapt and ultimately provide source populations to replenish the rest of the reef.

Marginalised agrarian traditions as a tool for climate justice

Many marginalised communities have long-standing food-growing traditions, yet the climate crisis imperils global food security and disproportionately impacts marginalised communities. Increasingly, researchers posit that networks of decentralised peri-urban agriculture can strengthen food security. In this qualitative study, I ask: what can we learn from marginalised agrarian traditions that might be useful to those marginalised communities in collectively surviving climate change? To answer that question, I conducted in-depth, semi-structured interviews with 23 marginalised food growers and community leaders in the deindustrialised city of Ypsilanti, Michigan, USA. I find that growing food helps to build resilience to food insecurity and climate change but is difficult because of land injustice. Policy and practice implications include the need for the following: (1) housing justice; (2) proactive planning in areas that are expected to serve as climate refuges; and (3) reparations and land rematriation to address the disparate impacts of climate disaster in marginalised communities.

Identifying climate‐smart tropical Key Biodiversity Areas for protection in response to widespread temperature novelty

AbstractKey Biodiversity Areas (KBAs) are a cornerstone of 21st‐century area‐based conservation targets. In tropical KBAs, biodiversity is potentially at high risk from climate change, because most species reside within or beneath the canopy, where small increases in temperature can lead to novel climate regimes. We quantify novelty in temperature regimes by modeling hourly temperatures below the forest canopy across tropical KBAs between 1990 and 2019. We find that up to 66% of KBAs with tropical forests have recently transitioned to novel temperature regimes. Nevertheless, 34% of KBAs are providing refuge from novelty, 58% of which are not protected. By conducting the first pan‐tropical analyses of changes in below‐canopy temperature conditions in KBAs, we identify KBAs that are acting as climate refugia and should be considered for expansion of the conservation network in response to the post‐2020 Global Biodiversity Framework target to conserve 30% of land area by 2030.

Redistribution of vocal snapping shrimps under climate change

A variety of marine organisms can produce sounds that are important components of the marine soundscape and play a critical role in maintaining marine biodiversity. Climate change has greatly altered the geographical ranges of many marine species, including sound-producing organisms. However, the direction and the magnitude of the potential impact of climate change on the geographical distribution of sound-producing marine organisms in future remain largely unknown. To address this knowledge gap, we selected snapping shrimp, one of the most well-known marine sound-producing organisms, as a model species and explored their redistribution under climate change via species distribution models. We aimed to predict the redistribution of snapping shrimps under climate change and identify the influencing factors, which have important implications for marine conservation. Our models exhibited good discrimination abilities and identified maximum temperature as the most influential predictor of snapping shrimp distribution. Model predictions suggested that species richness is higher in tropical and temperate coastal waters and peaks in the Indo-Pacific region. The majority of snapping shrimp species are expected to respond to the changing climate by shifting their geographical ranges to deeper waters and higher latitudes. Our results showed that, in the future, high-latitude species were more likely to experience range expansion, whereas low-latitude species might experience range contraction. Moreover, the Central Indo-Pacific are predicted to suffer the biggest decline in species richness, whereas areas such as the coastal waters of southern Australia and northern China might serve as climate refuges for snapping shrimps in the future. In summary, this study highlights the potential effects of climate change on the distribution of sound-producing snapping shrimps, which may result in cascading effects on marine ecosystems.

Global Distribution of Mammalian Cradles and Museums is Driven by Past Climate Dynamics and Present Water–Energy Balance

ABSTRACTAimTo describe worldwide distribution of mammalian cradles and museums using the rates of phylogenetic lineage turnover as a surrogate. Additionally, we investigated the influences of current water–energy dynamics, climate instability, past climate changes and elevational ranges on the distribution of these evolutionary zones.LocationGlobal.Time PeriodCurrent.Major Taxa StudiedTerrestrial mammals.MethodsWe developed a new methodology that consists of calculating the spatial phylogenetic turnover for non‐overlapping temporal segments of phylogenetic trees. By calculating the relative turnover in each tree segment, we quantified the rate of accumulation of phylogenetic turnover through time. We depicted cold and hotspots of rates of lineage turnover using bivariate maps and examined the effects of environmental factors using a path model.ResultsThe distributions of cradles and museums of biodiversity are primarily driven by water–energy dynamics. Environments with higher water availability than energetic demand predominantly act as cradles, as seen in tropical rainforests, while xeric‐like environments predominantly serve as museums. Conversely, regions undergoing higher historical climate changes become cradles, such as in higher northern latitudes, while climatically stable areas function as museums. Mountains play a dual role, acting as both cradles and museums by generating new lineages along their elevation bands while simultaneously providing climate refuges for ancient mammal lineages.Main ConclusionsOur findings demonstrate that cradles and museums are not merely a dichotomy but exist along an evolutionary continuum. Furthermore, they reveal how spatial patterns of mammalian cradles and museums are intricately shaped by biogeographical processes governed by environmental forces. Uncovering these hidden effects provides insights into the ecological mechanisms by which ongoing climate changes continually shape evolutionary assemblages over time.

Species persistence and climatic stability have shaped plant communities of the Atlantic forest biodiversity hotspot

ABSTRACT Background The remarkable floristic diversity of the Atlantic Forest is partly related to the diversity of environmental conditions across its vast geographic extent that has resulted in distinct plant communities. Four areas (Pernambuco, Bahia and Northern Espírito Santo, São Paulo, and Araguaia-Tocantins refugia) have been hypothesised to have particularly high modern diversity due to their being located in areas of multi-millennial climate stability. Aims To test if species persistence and climatic stability over the last 21,000 years can predict hypothesised refugia in the Atlantic Forest domain. Methods We modelled the distributions of 282 tree species from various habitats and projected them using eight past climate scenarios in the last c. 21000 years. Based on the spatial overlaps among these projections, we inferred three types of refugia: species persistence refugium based on probability of occurrence, climatic stability refugium based on climate suitability and bioclimatic refugium based on the intersection of the previous two. We validated model projections with fossil pollen data. Results We identified five potential bioclimatic refugia (Bahia and Northern Espírito Santo, São Paulo, Paranaíba, Serra do Espinhaço and Subtropical Serra do Mar) and one climatic stability refugium (Pernambuco). Conclusions We validated three of four previously hypothesised refugia and detected two additional ones by considering both species persistence and climatic stability as key determinants of refugia.

Present and future distribution of the deep-sea habitat-forming sponge - Pheronema carpenteri ( ) in a changing ocean

Sponges play vital roles in the ecosystem function of the deep sea. Some species, such as the birds' nest sponge Pheronema carpenteri, can form highly structured and dense habitats (i.e., aggregations), which contribute to the increase of nearby biodiversity. Climate change is expected to have a pronounced impact on the deep sea, particularly on Vulnerable Marine Ecosystems such as those formed by the glass sponge Pheronema carpenteri. These ecosystems are especially vulnerable to climate change and other anthropogenic activities since they are formed by sensitive species with slow growth rates and limited dispersal capability, which can hinder their adaptive capability and recovery after disturbance. The impact that climate change will have on Pheronema carpenteri remains unclear, although it is expected to influence the species' available suitable habitat and distribution range. The aim of this study was to predict the distribution of the glass sponge Pheronema carpenteri both for present day and under several future climate scenarios in the North Atlantic. An ensemble modelling approach was employed, combining Maximum Entropy, Generalized Additive Models and Random Forest techniques. Changes in available suitable habitat were projected to present day and to three future climatic scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). Depth, temperature and dissolved oxygen were identified as the key predictor variables of habitat suitability, which patterns suggest a strong influence of the Mediterranean Outflow Water in shaping the present day distribution of the species, particularly in the eastern North Atlantic. Our results indicate a potential expansion of available suitable habitat in the northernmost region of the study area, with a contraction at lower latitudes, more prominent in the Portuguese archipelago of the Azores. Under the worst-case scenario (RCP 8.5), the area of suitable habitat will likely double compared to present, occupying approximately 6% of the total study area. The management and conservation of areas where Pheronema aggregations can occur should be articulated between different countries, particularly in the Northeast Atlantic since, cumulatively, most of Pheronema's climate refugia occurs within their EEZs. Nonetheless, a significant proportion of the species' climate refugia is located in areas within the High Seas (i.e., Rockall plateau).

Potential impacts of climate change on cephalopods in a highly productive region (Northwest Pacific): Habitat suitability and management

Cephalopods occupy a mid-trophic level in marine ecosystems and are vital both ecologically and as fishery resources. However, under the pressure of climate change and fishing, the sustainability of cephalopod resources requires reasonable management. This study aims to study climate change and fishing impacts on the common economic cephalopod species habitats using species distribution models. We take the northwest Pacific Ocean region as an example, which stands out as a significant region for cephalopod production around the world. Results found that the habitats of cephalopods are moving to higher latitudes or deeper waters (Bohai Sea, mid-bottom Yellow Sea, and the Okinawa Trough waters) under climate change. Additionally, these regions are currently under lower fishing pressure, which suggests that species migration might mitigate the effects of warming and fishing. This study provides the large-scale assessment of the distribution range of cephalopods affected by climate change coping with fishing pressure in the northwest Pacific Ocean. By identifying climate refuges and key fishing grounds, we underscore the importance of this information for managing cephalopod resources in the context of climate adaptation and sustainable fishing practices.

Bridging climate refuges for climate change adaptation: A spatio-temporal connectivity network approach

Enhancing the spatio-temporal connectivity of dynamic landscapes is crucial for species to adapt to climate change. However, a spatio-temporal connectivity network approach considering climate change and species movement is often overlooked. Taking Tibetan wild ass on the Qinghai-Xizang Plateau as an example, we simulated species distribution under current (2019) and future scenarios (2100), constructed spatio-temporal connectivity networks, and assessed the spatio-temporal connectivity. The results show that under the current, SSP2-4.5 and SSP3-7.0 scenarios, the suitable habitats for Tibetan wild ass account for 21.11%, 21.34%, and 20.95% of the total area, respectively, which show more fragmentation in 2100. 78.35% of habitats which are predicted to be suitable under current conditions will remain suitable in the future, which can be regarded as stable climate refuges. With the increase in future emission intensity, the number percentage of auxiliary connectivity corridors increases from 27.65% to 33.57%. This indicates that more patches will function as temporary refuges and the auxiliary connectivity corridors will gradually weaken the dominance of direct connectivity corridors. Under different SSP-RCP scenarios, the internal spatio-temporal connectivity is the highest, accounting for 42%–43%. Compared with the spatio-temporal perspective, the purely spatial perspective overestimates network connectivity by about 28% considering all current and future patches, and underestimates network connectivity by 16%–21% when only considering all current or future patches. In this study, a new approach of spatio-temporal connectivity network is proposed to bridge climate refuges, which contributes to the long-term effectiveness of conservation networks for species’ adaptation to climate change.

Incorporating projected climate conditions to map future riparian refugia

AbstractIdentifying areas expected to remain buffered from climate change and maintain biodiversity and ecological function (i.e., climate refugia) is important for climate adaptation planning. As structurally diverse transitional zones between terrestrial and aquatic environments, riparian areas are often biological hotspots and provide critical corridors for species movement, particularly in arid and semi‐arid regions. In our study region in the western and central USA, identifying riparian areas that could serve as climate refugia is a priority for wildlife managers. We mapped areas with connected riparian habitats that, based on landscape diversity and projected changes in summer temperatures and landscape runoff, are expected to serve as climate refugia. To incorporate uncertainty and balance the need for near‐ and long‐term planning, we mapped potential refugia for 2 future time periods (2040–2069, 2070–2099) based on 2 climate models that represented divergent but plausible climate outcomes. The approach we developed is not constrained by physiology or behavior of target species and can be used to identify areas expected to fare comparatively well under a wide range of future climate scenarios. Our approach can also be used to identify areas where restoration could increase riparian connectedness and climate resilience.

Bioindicator aquatic insects at risk from climate change in a biodiversity hotspot

Climate change can affect biological assemblages by shifting their species' geographic range and changing species richness. Aquatic insects represent more than half of the freshwater animal species but have been neglected mainly in climate change assessments, particularly in tropical ecosystems. Among the aquatic insect taxa, Ephemeroptera, Plecoptera, and Trichoptera (EPT) are well-known bioindicators of environmental changes and encompass an essential metric for rivers and streams' biomonitoring. Here, we use ecological niche models to project the impact of climate change on the distribution range and richness of EPT in the Atlantic Forest biodiversity hotspot. We found EPT to be at high risk from future climate change, with Plecoptera as the order of greatest concern. We projected range contraction of ca. 90 % of the analyzed EPT genera, resulting in a reduction in the richness of EPT genera under future climatic conditions. We projected >50 % contraction in the distribution of 50 % of Plecoptera, ≈14 % of Trichoptera, and ≈7 % of Ephemeroptera genera. The remaining climatically suitable regions in the Atlantic Forest are concentrated in the high-altitude areas, which may act as climate refuges for EPT biodiversity in the future. The projected changes in EPT's distribution range and richness may impact biomonitoring programs conducted in tropical ecosystems. Restricting EPT's geographic distribution may undermine its potential as a bioindicator and influence the composition of EPT assemblages at reference sites, which may lead to shifting baseline conditions. We reinforce the importance of considering future climatic conditions when planning long-term biomonitoring and priority areas for conservation.

Fish and tips: Historical and projected changes in commercial fish species' habitat suitability in the Southern Hemisphere

Global warming has significantly altered fish distribution patterns in the ocean, shifting towards higher latitudes and deeper waters. This is particularly relevant in high-latitude marine ecosystems, where climate-driven environmental changes are occurring at higher rates than the global average. Species Distribution Models (SDMs) are increasingly being used for predicting distributional shifts in habitat suitability for marine species as a response to climate change. Here, we used SDMs to project habitat suitability changes for a range of high-latitude, pelagic and benthopelagic commercial fish species and crustaceans (10 species); from 1850 to two future climate change scenarios (SSP1–2.6: low climate forcing; and SSP5–8.5: high climate forcing). The study includes 11 Large Marine Ecosystems (LME) spanning South America, Southern Africa, Australia, and New Zealand. We identified declining and southward-shifting patterns in suitable habitat areas for most species, particularly under the SSP5–8.5 scenario and for some species such as Argentine hake (Merluccius hubbsi) in South America, or snoek (Thyrsites atun) off Southern Africa. Geographical constraints will likely result in species from Southern Africa, Australia, and New Zealand facing the most pronounced habitat losses due to rising sea surface temperatures (SST). In contrast, South American species might encounter greater opportunities for migrating southward. Additionally, the SSP5–8.5 scenario predicts that South America will be more environmentally stable compared to other regions. Overall, our findings suggest that the Patagonian shelf could serve as a climate refuge, due to higher environmental stability highlighting the importance of proactive management strategies in this area for species conservation. This study significantly contributes to fisheries and conservation management, providing valuable insights for future protection efforts in the Southern Hemisphere.

Future trends of marine fish biomass distributions from the North Sea to the Barents Sea

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species’ ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes.

Forest habitat diversity in the Cantabrian Mixed Forests ecoregion (NW Iberian Peninsula), a climatic refugium in western Europe

AbstractAims(i) To classify forest habitat diversity in the Cantabrian Mixed Forests ecoregion, a putative biodiversity refugium in Western Europe, and (ii) to evaluate how the distribution of functional and ecological habitat types is explained by climatic drivers.LocationCantabrian Mixed Forests ecoregion (northwestern Iberian Peninsula).MethodsWe compiled a vegetation database for the ecoregion using data stored in the Iberian and Macaronesian Vegetation Information System (SIVIM). Then, we used the EUNIS Habitat Classification expert system, the modified Two‐Way Indicator Species Analysis (TWINSPAN) and the semi‐supervised k‐means classification to classify all Forest plots into regionalised EUNIS habitat types. We determined the environmental space of each ecological forest type with bioclimatic and soil variables, and computed principal components analysis (PCA), generalised linear models (GLMs) and PERMANOVA to evaluate climatic differences among forests.ResultsWe identified 24 ecological forest habitat types (12 broadleaved deciduous, seven broadleaved evergreen and five coniferous), whose regional distribution is mainly driven by the oceanic influence and the amount and seasonality of annual precipitation. Most forest types had a specific climatic optimum, but there were also climatic overlaps in habitats traditionally favoured by human activities.ConclusionsThe Cantabrian Mixed Forests ecoregion is a hotspot of forest diversity within the temperate deciduous forest biome in Europe, including multiple functional and ecological forest types. Such forest diversity is explained by present macro‐ and mesoclimatic heterogeneity, Pleistocene refugia, and the legacy of human intervention during the Holocene.

Decametric-scale buffering of climate extremes in forest understory within a riparian microrefugia: the key role of microtopography.

Riparian corridors often act as low-land climate refugia for temperate tree species in their southern distribution range. A plausible mechanism is the buffering of regional climate extremes by local physiographic and biotic factors. We tested this idea using a 3-year-long microclimate dataset collected along the Ciron river, a refugia for European beech (Fagus sylvatica) in southwestern France. Across the whole network, canopy gap fraction was the main predictor for spatial microclimatic variations, together with two other landscape features (elevation above the river and woodland fraction within a 300m radius). However, within the riparian forest only (canopy gap fraction < 25%, distance to the river < 150m), variations of up to -4°C and + 15% in summertime daily maximum air temperature and minimum relative humidity, respectively, were still found from the plateau to the cooler, moister river banks, only ~ 5-10m below. Elevation above the river was then identified as the main predictor, and explained the marked variations from the plateau to the banks much better than canopy gap fraction. The microclimate measured near the river is as cool but moister than the macroclimate encountered at 700-1000m asl further east in F. sylvatica's main distribution range. Indeed, at all locations, we found that air relative humidity was higher than expected from a temperature-only effect, suggesting that extra moisture is brought by the river. Our results explain well why beech trees in this climate refugium are restricted to the river gorges where microtopographic variations are the strongest and canopy gaps are rare.

A comprehensive analysis to optimizing national-scale protected area systems under climate change

With the intensification of climate change, incorporating climate information into protected areas planning has become crucial in reducing biodiversity loss. However, the current natural reserve system in China does not take climate information into account. Therefore, we assessed the effectiveness of existing protected areas through climate refuge and connectivity rankings, and Zonation software was used to identify the ecological priority zone in China by combining climate indicators and human footprint. The results show that the current natural protected areas in China have certain limitations in dealing with climate change, and some protected areas may struggle to maintain their value in biodiversity conservation under climate change. Moreover, China still has lots of important areas that can maintain biodiversity under climate change, but most of them are not covered by protected areas. The results provide support for the planning of China's nature protected area system in response to climate change.

Climate refugia along Lake Superior’s shores: disjunct arctic–alpine plants rely on cool shoreline temperatures but are restricted to highly exposed habitat under climate warming

Abstract Climate refugia can serve as a remnant habitat or stepping stones for species dispersal under climate warming. The largest freshwater lake by surface area, Lake Superior, USA and Canada, serves as a model system for understanding cooling-mediated local refugia, as its cool water temperatures and wave action have maintained shoreline habitats suitable for southern disjunct populations of arctic–alpine plants since deglaciation. Here, we seek to explain spatial patterns and environmental drivers of arctic–alpine plant refugia along Lake Superior’s shores, and assess future risk to refugia under moderate (+3.5 °C) and warmest (+5.7 °C) climate warming scenarios. First, we examined how the interactive effects of summer surface water temperatures and wind affected onshore temperatures, resulting in areas of cooler refugia. Second, we developed an ecological niche model for the presence of disjunct arctic–alpine refugia (pooling 1253 occurrences from 58 species) along the lake’s shoreline. Third, we fit species distribution models for 20 of the most common arctic–alpine disjunct species and predicted presence to identify refugia hotspots. Finally, we used the two climate warming scenarios to predict changes in the presence of refugia and disjunct hotspots. Bedrock type, elevation above water, inland distance, July land surface temperature from MODIS/Terra satellite and near-shore depth of water were the best predictors of disjunct occurrences. Overall, we predicted 2236 km of the shoreline (51%) as disjunct refugia habitat for at least one species under current conditions, but this was reduced to 20% and 7% with moderate (894 km) and warmest (313 km) climate change projections.

Vulnerability of the Pteridoflora Towards Climate Change in the West Albertine Rift: Case of the Mountain’s Stages of the Kahuzi-Biega National Park in the Democratic Republic of the Congo

The present article aims at analysing the floristic composition of Lycophytes and Ferns to test the disturbances on the vegetation structure occurring in the mountains zones of the Kahuzi-Biega National Park (KBNP), further, to prove/underline the main threat and the vulnerability which actually is impacting the biodiversity in the mountains of the Western Albertine Rift due to climate changes and resulting in habitat loss as well as result of anthropogenic activities. The KBNP is located at the crossroad of the phytogeography regions of the Guinea-Congolese and Afromontane between 650 to 3326 m of altitude. During 10 years, we conducted comparison studies in the habitats (disturbed and undisturbed) encountered on the vegetation that scales between 1250 à 3300 m of altitude in 30 plots, 15 transects on a one kilometre. The results obtained reveal a variation in the flora composition within the three stages. The difference in the height, the diametric distribution (trees and shrubs) as well as the presence of Pteridophytes between undisturbed and disturbed habitats is highly significant within the 10 years’ observations. In stable and mature parcels, Pteridophytes constitute a very rich, diversified and stable population. Permanent threat manifested through the fragility of the habitats and is further translated by a modification of the floristic composition of the canopy, and sometimes trough the taming of the undergrowth in disturbed parcels. The mountainous part of the KBNP might probably constitute a climatic refuge for Pteridophytes in the Albertine Rift considering their diversity. Furthermore, considering these adaptations, the diversity and the specificity of the biotopes occupied, as well as the bioecological services recognized to Lycophytes and Ferns, they are the real markers for bioindicators of the delicatessen towards climate changes observed in the western rift Albertine. However, anthropogenic effects and sometimes, natural hazards resulting in this protected area, may also constitute a source of vulnerability for Pteridophytes

Historical biogeography of the Saharan horned viper enlightens past dynamics of hyperarid desert habitats

Hyperarid habitats comprise the most dominant and harsh portion of the Sahara Desert, yet how local biotas have responded to paleoclimatic shifts and landscape heterogeneity remains unclear. Here, we assess the historical biogeography of Cerastes cerastes, a conspicuous but poorly known vertebrate inhabiting the hyperarid Sahara, to understand the links between intermittent and stable climatic suitability and patterns of genetic diversity and differentiation in these extreme environments. We combine phylogeographic and ecological modelling tools using a comprehensive species dataset, which includes DNA samples (n = 62) and occurrence records (n = 557) covering most of its range. We show that paleoclimatic oscillations were major evolutionary and biogeographic drivers in C. cerastes, which exhibits different levels of intra-specific diversity and allopatric lineage structuration across the desert. High lineage richness in the north-western Sahara contrasts with an overall lack of genetic diversity throughout the central and eastern Sahara. Climatic refugia along the desert's periphery and around mountain patches harbour single endemic lineages, stressing the links between stable climatic conditions and population isolation and divergence. Increasing climatic suitability during historical arid phases prompted widespread connectivity across the desert. This study lays the groundwork for better understanding the historical dynamics of the hyperarid Sahara.

Shaded streams with permeable watersheds provide naturally resilient fish habitat refugia during heatwaves

AbstractStreamflow, dissolved oxygen, and water temperature underpin stream fish habitat suitability, so climate change could cause widespread habitat deterioration. Identifying stream characteristics that mediate habitat resilience to heatwaves will allow conservation effort prioritisation. Here, a set of readily applied metrics were used to assess hydrological and oxythermal responses of neighbouring salmonid streams, with distinctive geologies, soil‐types, and localised riparian shading, to periods of anomalously warm conditions. During heatwaves, low flows, warm‐water temperatures, and diel oxygen variability, associated with biogenic production and respiration, predominated. In a low‐shade stream lacking significant catchment water storage, high daytime (&gt;22°C) and night‐time (&gt;19°C) water temperatures and low early morning O2 concentrations (&lt;5 mg L−1) accumulated oxythermal stress for salmonids throughout summer. A stream with localised shading and a higher proportion of underlying aquifers and permeable soils throughout its watershed experienced considerably less cumulative oxythermal stress (O2 &gt; 6 mg L−1; temperatures &lt;19°C), whilst slower release of subsurface water bolstered base flows during dry spells. Our findings support conservation of shaded streams with permeable watersheds characterised by higher soil infiltration rates and aquifer storage capacity as salmonid sanctuaries under a warmer, drier summer climate. Preventing water quality and hydromorphological deterioration are paramount for safeguarding their role as climate refugia.