Growth and temperature relationships for juvenile fish species in seagrass beds: implications of climate change

The effect of water temperature on growth responses of three common seagrass fish species that co‐occur as juveniles in the estuaries in Sydney (34° S) but have differing latitudinal ranges was measured: Pelates sexlineatus (subtropical to warm temperate: 27–35° S), Centropogon australis (primarily subtropical to warm temperate: 24–37° S) and Acanthaluteres spilomelanurus (warm to cool temperate: below 32° S). Replicate individuals of each species were acclimated over a 7 day period in one of three temperature treatments (control: 22° C, low: 18° C and high: 26° C) and their somatic growth was assessed within treatments over 10 days. Growth of all three species was affected by water temperature, with the highest growth of both northern species (P. sexlineatus and C. australis) at 22 and 26° C, whereas growth of the southern ranging species (A. spilomelanurus) was reduced at temperatures higher than 18° C, suggesting that predicted increase in estuarine water temperatures through climate change may change relative performance of seagrass fish assemblages.     

Patterns of distribution for southern Australian marine echinoderms and decapods

Aim To relate patterns of distribution of marine echinoderms and decapods around southern Australia to major ecological and historical factors. Location Shallow‐water (0–100 m) marine waters off southern Australia, south of 30° S. Methods (1) Record the presence/absence of known echinoderm and decapod species in cells of c. 1° latitude and longitude, along the coast of southern mainland Australia and Tasmania. (2) Describe patterns in species composition, species richness and endemism through gradient analysis, ordination and cluster analysis. (3) Relate these patterns to distance and temperature gradients, the area of continental shelf, the average size of species range, and known historical factors. Results Species composition varied with both latitude and longitude. Species richness was relatively constant from east to west but graded with latitude from high in the warm‐temperate regions around Perth and Sydney to low in cool‐temperate southern Tasmania. Species richness was not related to the area of continental shelf or average species range size. Species turnover was not correlated with rates of temperature change. It was problematic to separate distance from temperature gradients, but there was evidence that the southern distribution limits of some species are related to minimum sea surface temperature. Within the taxonomic groups surveyed, evolutionary radiation has been largely limited to a few cosmopolitan species‐rich genera. Main conclusions There are historical as well as ecological hypotheses explaining the latitudinal gradient of marine species richness in southern Australia: (1) the continual invasion and speciation of species of tropical origin as Australia has split from Gondwana and drifted northward; (2) progressive extinction of some Gondwanan cool‐temperate species at the limits of their range; (3) low level of immigration of additional cool‐temperate species; and (4) some in situ endemic speciation.     

Ocean acidification has little effect on developmental thermal windows of echinoderms from Antarctica to the tropics

As the ocean warms, thermal tolerance of developmental stages may be a key driver of changes in the geographical distributions and abundance of marine invertebrates. Additional stressors such as ocean acidification may influence developmental thermal windows and are therefore important considerations for predicting distributions of species under climate change scenarios. The effects of reduced seawater pH on the thermal windows of fertilization, embryology and larval morphology were examined using five echinoderm species: two polar (Sterechinus neumayeri and Odontaster validus), two temperate (Fellaster zelandiae and Patiriella regularis) and one tropical (Arachnoides placenta). Responses were examined across 12–13 temperatures ranging from ?1.1 °C to 5.7 °C (S. neumayeri), ?0.5 °C to 10.7 °C (O. validus), 5.8 °C to 27 °C (F. zelandiae), 6.0 °C to 27.1 °C (P. regularis) and 13.9 °C to 34.8 °C (A. placenta) under present‐day and near‐future (2100+) ocean acidification conditions (‐0.3 pH units) and for three important early developmental stages 1) fertilization, 2) embryo (prehatching) and 3) larval development. Thermal windows for fertilization were broad and were not influenced by a pH decrease. Embryological development was less thermotolerant. For O. validus, P. regularis and A. placenta, low pH reduced normal development, albeit with no effect on thermal windows. Larval development in all five species was affected by both temperature and pH; however, thermal tolerance was not reduced by pH. Results of this study suggest that in terms of fertilization and development, temperature will remain as the most important factor influencing species' latitudinal distributions as the ocean continues to warm and decrease in pH, and that there is little evidence of a synergistic effect of temperature and ocean acidification on the thermal control of species ranges.     

Effects of ocean warming and acidification on survival,growth and skeletal development in the early benthic juvenile sea urchin (Heliocidaris erythrogramma)

Co‐occurring ocean warming, acidification and reduced carbonate mineral saturation have significant impacts on marine biota, especially calcifying organisms. The effects of these stressors on development and calcification in newly metamorphosed juveniles (ca. 0.5 mm test diameter) of the intertidal sea urchin Heliocidaris erythrogramma, an ecologically important species in temperate Australia, were investigated in context with present and projected future conditions. Habitat temperature and pH/pCO₂ were documented to place experiments in a biologically and ecologically relevant context. These parameters fluctuated diurnally up to 10 °C and 0.45 pH units. The juveniles were exposed to three temperature (21, 23 and 25 °C) and four pH (8.1, 7.8, 7.6 and 7.4) treatments in all combinations, representing ambient sea surface conditions (21 °C, pH 8.1; pCO₂ 397; Ω_Ca 4.7; Ω_Ar 3.1), near‐future projected change (+2–4 °C, ?0.3–0.5 pH units; pCO₂ 400–1820; Ω_Ca 5.0–1.6; Ω_Ar 3.3–1.1), and extreme conditions experienced at low tide (+4 °C, ?0.3–0.7 pH units; pCO₂ 2850–2967; Ω_Ca 1.1–1.0; Ω_Ar 0.7–0.6). The lowest pH treatment (pH 7.4) was used to assess tolerance levels. Juvenile survival and test growth were resilient to current and near‐future warming and acidification. Spine development, however, was negatively affected by near‐future increased temperature (+2–4 °C) and extreme acidification (pH 7.4), with a complex interaction between stressors. Near‐future warming was the more significant stressor. Spine tips were dissolved in the pH 7.4 treatments. Adaptation to fluctuating temperature‐pH conditions in the intertidal may convey resilience to juvenile H. erythrogramma to changing ocean conditions, however, ocean warming and acidification may shift baseline intertidal temperature and pH/pCO₂ to levels that exceed tolerance limits.     

Long‐term elevated air [CO2] strengthens photosynthetic functioning and mitigates the impact of supra‐optimal temperatures in tropical Coffea arabica and C. canephora species

The tropical coffee crop has been predicted to be threatened by future climate changes and global warming. However, the real biological effects of such changes remain unknown. Therefore, this work aims to link the physiological and biochemical responses of photosynthesis to elevated air [CO₂] and temperature in cultivated genotypes of Coffea arabica L. (cv. Icatu and IPR108) and Coffea canephora cv. Conilon CL153. Plants were grown for ca. 10 months at 25/20 °C (day/night) and 380 or 700 μl CO₂ l^?1 and then subjected to temperature increase (0.5 °C day^?1) to 42/34 °C. Leaf impacts related to stomatal traits, gas exchanges, C isotope composition, fluorescence parameters, thylakoid electron transport and enzyme activities were assessed at 25/20, 31/25, 37/30 and 42/34 °C. The results showed that (1) both species were remarkably heat tolerant up to 37/30 °C, but at 42/34 °C a threshold for irreversible nonstomatal deleterious effects was reached. Impairments were greater in C. arabica (especially in Icatu) and under normal [CO₂]. Photosystems and thylakoid electron transport were shown to be quite heat tolerant, contrasting to the enzymes related to energy metabolism, including RuBisCO, which were the most sensitive components. (2) Significant stomatal trait modifications were promoted almost exclusively by temperature and were species dependent. Elevated [CO₂], (3) strongly mitigated the impact of temperature on both species, particularly at 42/34 °C, modifying the response to supra‐optimal temperatures, (4) promoted higher water‐use efficiency under moderately higher temperature (31/25 °C) and (5) did not provoke photosynthetic downregulation. Instead, enhancements in [CO₂] strengthened photosynthetic photochemical efficiency, energy use and biochemical functioning at all temperatures. Our novel findings demonstrate a relevant heat resilience of coffee species and that elevated [CO₂] remarkably mitigated the impact of heat on coffee physiology, therefore playing a key role in this crop sustainability under future climate change scenarios.     

A regional impact assessment of climate and land-use change on alpine vegetation

Aim Assessing potential response of alpine plant species distribution to different future climatic and land‐use scenarios. Location Four mountain ranges totalling 150 km² in the north‐eastern Calcareous Alps of Austria. Methods Ordinal regression models of eighty‐five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land‐use impacts on vegetation patterns in combination with climatic changes. Results A regionalized GCM scenario for 2050 (+ 0.65 °C, ?30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 °C, ?30 mm August precipitation; + 2 °C, ?60 mm August precipitation) however, will bring about a severe contraction of the alpine, non‐forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 °C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non‐forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved.     

Short photoperiod reduces the temperature sensitivity of leaf‐out in saplings of Fagus sylvatica but not in horse chestnut

Leaf phenology is one of the most reliable bioindicators of ongoing global warming in temperate and boreal zones because it is highly sensitive to temperature variation. A large number of studies have reported advanced spring leaf‐out due to global warming, yet the temperature sensitivity of leaf‐out has significantly decreased in temperate deciduous tree species over the past three decades. One of the possible mechanisms is that photoperiod is limiting further advance to protect the leaves against potential damaging frosts. However, the “photoperiod limitation” hypothesis remains poorly investigated and experimentally tested. Here, we conducted a photoperiod‐ and temperature‐manipulation experiment in climate chambers on two common deciduous species in Europe: Fagus sylvatica (European beech, a typically late flushing species) and Aesculus hippocastanum (horse chestnut, a typically early flushing species). In agreement with previous studies, we found that the warming significantly advanced the leaf‐out dates by 4.3 and 3.7 days/°C for beech and horse chestnut saplings, respectively. However, shorter photoperiod significantly reduced the temperature sensitivity of beech only (3.0 days/°C) by substantially increasing the heat requirement to avoid leafing‐out too early. Interestingly, the photoperiod limitation only occurs below a certain daylength (photoperiod threshold) when the warming increased above 4°C for beech trees. In contrast, for chestnut, no photoperiod threshold was found even when the ambient air temperature was warmed by 5°C. Given the species‐specific photoperiod effect on leaf phenology, the sequence of the leaf‐out timing among forest tree species may change under future climate warming conditions. Nonphotoperiodic species may benefit from warmer springs by starting the growing season earlier than photoperiodic sensitive species, modifying forest ecosystem structure and functions, but this photoperiod limitation needs to be further investigated experimentally in numerous species.     

Photosynthetic performance at low temperature of Bouteloua gracilis Lag., a high-altitude C4 grass from the Rocky Mountains, USA

The mechanisms controlling the photosynthetic performance of C₄ plants at low temperature were investigated using ecotypes of Bouteloua gracilis Lag. from high (3000 m) and low (1500 m) elevation sites in the Rocky Mountains of Colorado. Plants were grown in controlled‐environment cabinets at a photon flux density of 700 μ mol m^?2 s^?1 and day/night temperatures of 26/16 °C or 14/7 °C. The thermal response of the net CO₂ assimilation rate (A) was evaluated using leaf gas‐exchange analysis and activity assays of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPCase) and pyruvate,orthophosphate dikinase (PPDK). In both ecotypes, a reduction in measurement temperature caused the CO₂‐saturated rate of photosynthesis to decline to a greater degree than the initial slope of A versus the intercellular CO₂ response, thereby reducing the photosynthetic CO₂ saturation point. As a consequence, A in normal air was CO₂‐saturated at sub‐optimal temperatures. Ecotypic variation was low when grown at 26/16 °C, with the major difference between the ecotypes being that the low‐elevation plants had higher A; however, the ecotypes responded differently when grown at cool temperature. At temperatures below the thermal optimum, A in high‐elevation plants grown at 14/7 °C was enhanced relative to plants grown at 26/16 °C, while A in low‐elevation plants grown at 14/7 °C was reduced compared to 26/16 °C‐grown plants. Photoinhibition at low growth temperature was minor in both ecotypes as indicated by small reductions in dark‐adapted F_v/F_m. In both ecotypes, the activity of Rubisco was equivalent to A below 17 °C but well in excess of A above 25 °C. Activities of PEPCase and PPDK responded to temperature in a similar proportion relative to Rubisco, and showed no evidence for dissociation that would cause them to become principal limitations at low temperature. Because of the similar temperature response of Rubisco and A, we propose that Rubisco is a major limitation on C₄ photosynthesis in B. gracilis below 17 °C. Based on these results and for theoretical reasons associated with how C₄ plants use Rubisco, we further suggest that Rubisco capacity may be a widespread limitation upon C₄ photosynthesis at low temperature.     

The cold‐adapted population of Folsomia manolachei (Hexapoda,Collembola) from a glaciated karst doline of Central Europe: evidence for a cryptic species?

Folsomia manolachei Bagnall, 1939 (Collembola), is a widespread and common European species. However, it may represent a complex of species also associated with the climatically more extreme environments of the karst landforms. Three species of the genus Folsomia, distributed in the Slovak Karst region (Central Europe), namely three different populations of F. manolachei, and one population of F. penicula and F. candida, were analysed using a partial sequence of the mitochondrial cytochrome c oxidase subunit I (COI barcoding section). The DNA barcoding suggested the existence of cryptic diversity in populations of the eurytopic species Folsomia manolachei. The cold‐adapted population of ‘F. manolachei’ was abundant in primary soil on stony debris near the permanent floor ice (yearly air temperature ~0°C) in the collapsed karst doline of the Silická ?adnica Ice Cave. It showed a genetic differentiation supported by intra‐ and interspecific distances that ranged from 0.0% to 1.4% and from 19.2% to 24.0%, respectively. Analysis using Taxon DNA showed a large barcoding gap between intra‐ and interspecific COI sequences. Genetic differentiation suggests a scenario of cryptic speciation in the population of ‘F. manolachei’ occupying harsh soils near the floor ice. A survival test showed the different responses of ‘F. manolachei’ and other populations to low temperature. Within a temperature range from ?3 to ?10°C, the ‘F. manolachei’ population from Silická ?adnica was the most cold‐resistant, showing a lethal dose LD₅₀ of ?7.8°C. The two forest populations of F. manolachei had LD₅₀ ?6.1°C and ?6.0°C, respectively; the most cold‐sensitive F. penicula showed an LD₅₀ of ?5.4°C. The survival of the tested springtails significantly decreased with temperature (p < 0.0001). The lethal temperature and the shape of the survival–temperature curves were different in different populations. The impact of population was significant at p < 0.0001, and the interaction between population and temperature at p < 0.039 was significant as well. Crypticity vs. phenotypic plasticity in Folsomia manolachei populations is discussed in terms of DNA barcoding and the cold tolerance data provided by this study.     

Evolution of total net fitness in thermal lines: Drosophila subobscura likes it 'warm'

Fisher's fundamental theorem states that heritable variation for net fitness sets a limit to the rate of response to natural selection. How will temperate (i.e. cold‐tolerant) species cope with contemporary rapid global warming? Using three‐fold replicated lines of Drosophila subobscura that had been allowed to evolve for 4 years (between 32 and 59 generations) at 13 °C (cold), 18 °C (the supposed optimum temperature), and 22 °C (warm) I assess here how net fitness changes according to thermal environments. Net fitness was estimated following the classical approach in population genetics of competing over a number of generation in outbred experimental populations multiple wild‐type O chromosomes (homologous to arm 3R in D. melanogaster) independently derived from each base thermal stock in an otherwise homogeneous genetic background against a balancer chromosome. Warm‐adapted populations (‘warm‐adapted O chromosomes’) performed comparatively well at all tested temperatures. However, net fitness was severely reduced in cold‐adapted populations when transferred to warmer conditions. It seems, therefore, that thermal fitness breath for D. subobscura flies is positively associated to temperature. These findings are discussed in relation to the fast world‐wide clinal shifts in the frequency of genetic markers correlated with current climate change.     

Forest phenology and a warmer climate – growing season extension in relation to climatic provenance

Predicting forest responses to warming climates relies on assumptions about niche and temperature sensitivity that remain largely untested. Observational studies have related current and historical temperatures to phenological shifts, but experimental evidence is sparse, particularly for autumn responses. A 4 year field experiment exposed four deciduous forest species from contrasting climates (Liquidambar styraciflua, Quercus rubra, Populus grandidentata, and Betula alleghaniensis) to air temperatures 2 and 4 °C above ambient controls, using temperature‐controlled open top chambers. Impacts of year‐round warming on bud burst (BB), senescence, and abscission were evaluated in relation to thermal provenance. Leaves emerged earlier in all species by an average of 4–9 days at +2 °C and 6–14 days at +4 °C. Magnitude of advance varied with species and year, but was larger for the first 2 °C increment than for the second. Effect of warming increased with early BB, favoring Liquidambar, but even BB of northern species advanced, despite temperatures exceeding those of the realized niche. Treatment differences in BB were inadequately explained by temperature sums alone. In autumn, chlorophyll was retained an average of 4 and 7 days longer in +2 and +4 °C treatments, respectively, and abscission delayed by 8 and 13 days. Growing seasons in the warmer atmospheres averaged 5–18 days (E2) and 6–28 days (E4) longer, according to species, with the least impact in Quercus. Results are compared with a 16 years record of canopy onset and offset in a nearby upland deciduous forest, where BB showed similar responsiveness to spring temperatures (2–4 days °C^?1). Offset dates in the stand tracked August–September temperatures, except when late summer drought caused premature senescence. The common garden‐like experiment provides evidence that warming alone extends the growing season, at both ends, even if stand‐level impacts may be complicated by variation in other environmental factors.     

Cold hardiness of diapausing and non-diapausing pupae of the European grapevine moth, Lobesia botrana

Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) is a key pest of grapes in Europe. It overwinters as a pupa in the bark crevices of the plant. Supercooling point (SCP) and low temperature survival was investigated in the laboratory and was determined using a cool bath and a 1 °C min^?1 cooling rate. Freezing was fatal both to diapausing and non‐diapausing pupae. SCP was significantly lower in diapausing male (?24.8 °C) and female (?24.5 °C) pupae than in non‐diapausing ones (?22.7 and ?22.5 °C, respectively). Sex had no influence on SCP both for diapausing and non‐diapausing pupae. Supercooling was also not affected by acclimation. However, acclimation did improve survival of diapausing pupae at temperatures above the SCP. Survival increased as acclimation period increased and the influence was more profound at the lower temperatures examined. Diapausing pupae could withstand lower temperatures than non‐diapausing ones and lethal temperature was significantly lower than for non‐diapausing pupae. Freezing injury above the SCP has been well documented for both physiological stages of L. botrana pupae. Our findings suggest a diapause‐related cold hardiness for L. botrana and given its cold hardiness ability, winter mortality due to low temperatures is not expected to occur, especially in southern Europe.     

Extreme rainfall events and cooling of sea turtle clutches: Implications in the face of climate warming

Understanding how climate change impacts species and ecosystems is integral to conservation. When studying impacts of climate change, warming temperatures are a research focus, with much less attention given to extreme weather events and their impacts. Here, we show how localized, extreme rainfall events can have a major impact on a species that is endangered in many parts of its range. We report incubation temperatures from the world's largest green sea turtle rookery, during a breeding season when two extreme rainfall events occurred. Rainfall caused nest temperatures to drop suddenly and the maximum drop in temperature for each rain‐induced cooling averaged 3.6°C (n = 79 nests, min = 1.0°C, max = 7.4°C). Since green sea turtles have temperature‐dependent sex determination, with low incubation temperatures producing males, such major rainfall events may have a masculinization effect on primary sex ratios. Therefore, in some cases, extreme rainfall events may provide a “get‐out‐of‐jail‐free card” to avoid complete feminization of turtle populations as climate warming continues.     

Plants adapted to warmer climate do not outperform regional plants during a natural heat wave

With ongoing climate change, many plant species may not be able to adapt rapidly enough, and some conservation experts are therefore considering to translocate warm‐adapted ecotypes to mitigate effects of climate warming. Although this strategy, called assisted migration, is intuitively plausible, most of the support comes from models, whereas experimental evidence is so far scarce. Here we present data on multiple ecotypes of six grassland species, which we grew in four common gardens in Germany during a natural heat wave, with temperatures 1.4–2.0°C higher than the long‐term means. In each garden we compared the performance of regional ecotypes with plants from a locality with long‐term summer temperatures similar to what the plants experienced during the summer heat wave. We found no difference in performance between regional and warm‐adapted plants in four of the six species. In two species, regional ecotypes even outperformed warm‐adapted plants, despite elevated temperatures, which suggests that translocating warm‐adapted ecotypes may not only lack the desired effect of increased performance but may even have negative consequences. Even if adaptation to climate plays a role, other factors involved in local adaptation, such as biotic interactions, may override it. Based on our results, we cannot advocate assisted migration as a universal tool to enhance the performance of local plant populations and communities during climate change.     

Warming increases plant biomass and reduces diversity across continents,latitudes, and species migration scenarios in experimental wetland communities

Atmospheric warming may influence plant productivity and diversity and induce poleward migration of species, altering communities across latitudes. Complicating the picture is that communities from different continents deviate in evolutionary histories, which may modify responses to warming and migration. We used experimental wetland plant communities grown from seed banks as model systems to determine whether effects of warming on biomass production and species richness are consistent across continents, latitudes, and migration scenarios. We collected soil samples from each of three tidal freshwater marshes in estuaries at three latitudes (north, middle, south) on the Atlantic coasts of Europe and North America. In one experiment, we exposed soil seed bank communities from each latitude and continent to ambient and elevated (+2.8 °C) temperatures in the greenhouse. In a second experiment, soil samples were mixed either within each estuary (limited migration) or among estuaries from different latitudes in each continent (complete migration). Seed bank communities of these migration scenarios were also exposed to ambient and elevated temperatures and contrasted with a no‐migration treatment. In the first experiment, warming overall increased biomass (+16%) and decreased species richness (?14%) across latitudes in Europe and North America. Species richness and evenness of south‐latitude communities were less affected by warming than those of middle and north latitudes. In the second experiment, warming also stimulated biomass and lowered species richness. In addition, complete migration led to increased species richness (+60% in North America, + 100% in Europe), but this higher diversity did not translate into increased biomass. Species responded idiosyncratically to warming, but Lythrum salicaria and Bidens sp. increased significantly in response to warming in both continents. These results reveal for the first time consistent impacts of warming on biomass and species richness for temperate wetland plant communities across continents, latitudes, and migration scenarios.     

Noncalcifying larvae in a changing ocean: warming,not acidification/hypercapnia,is the dominant stressor on development of the sea star Meridiastra calcar

Climate change driven ocean warming and acidification is potentially detrimental to the sensitive planktonic life stages of benthic marine invertebrates. Research has focused on the effects of acidification on calcifying larvae with a paucity of data on species with alternate developmental strategies and on the interactive effects of warming and acidification. To determine the impact of climate change on a conspicuous component of the intertidal fauna of southeast Australia, the development of the noncalcifying lecithotrophic larvae of the sea star Meridiastra calcar was investigated in the setting of predicted ocean warming (+2 to 4 ^°C) and acidification (?0.4 to 0.6 pH units) for 2100 and beyond in all combinations of stressors. Temperature and pH were monitored in the habitat of M. calcar to place experiments in context with current environmental conditions. There was no effect of temperature or pH on cleavage stage embryos but later development (gastrula‐larvae) was negatively effected by a +2 to 4 ^°C warming and there was a negative effect of ?0.6 pH units on embryos reaching the hatched gastrula stage. Mortality and abnormal development in larvae increased significantly even with +2 ^°C warming and larval growth was impaired at +4 ^°C. For the range of temperature and pH conditions tested, there were no interactive effects of stressors across all stages monitored. For M. calcar, warming not acidification was the dominant stressor. A regression model incorporating data from this study and projected increasing SST for the region suggests an increase in larval mortality to 70% for M. calcar by 2100 in the absence of acclimation and adaptation. The broad distribution of this species in eastern Australia encompassing subtropical to cold temperate thermal regimes provides the possibility that local M. calcar populations may be sustained in a warming world through poleward migration of thermotolerant propagules, facilitated by the strong southward flow of the East Australian Current.     

Sponge erosion under acidification and warming scenarios: differential impacts on living and dead coral

Ocean acidification will disproportionately impact the growth of calcifying organisms in coral reef ecosystems. Simultaneously, sponge bioerosion rates have been shown to increase as seawater pH decreases. We conducted a 20‐week experiment that included a 4‐week acclimation period with a high number of replicate tanks and a fully orthogonal design with two levels of temperature (ambient and +1 °C), three levels of pH (8.1, 7.8, and 7.6), and two levels of boring sponge (Cliona varians, present and absent) to account for differences in sponge attachment and carbonate change for both living and dead coral substrate (Porites furcata). Net coral calcification, net dissolution/bioerosion, coral and sponge survival, sponge attachment, and sponge symbiont health were evaluated. Additionally, we used the empirical data from the experiment to develop a stochastic simulation of carbonate change for small coral clusters (i.e., simulated reefs). Our findings suggest differential impacts of temperature, pH and sponge presence for living and dead corals. Net coral calcification (mg CaCO₃ cm^?2 day^?1) was significantly reduced in treatments with increased temperature (+1 °C) and when sponges were present; acidification had no significant effect on coral calcification. Net dissolution of dead coral was primarily driven by pH, regardless of sponge presence or seawater temperature. A reevaluation of the current paradigm of coral carbonate change under future acidification and warming scenarios should include ecologically relevant timescales, species interactions, and community organization to more accurately predict ecosystem‐level response to future conditions.     

Thermal niche predicts tolerance to habitat conversion in tropical amphibians and reptiles

Habitat conversion is a major driver of the biodiversity crisis, yet why some species undergo local extinction while others thrive under novel conditions remains unclear. We suggest that focusing on species' niches, rather than traits, may provide the predictive power needed to forecast biodiversity change. We first examine two Neotropical frog congeners with drastically different affinities to deforestation and document how thermal niche explains deforestation tolerance. The more deforestation‐tolerant species is associated with warmer macroclimates across Costa Rica, and warmer microclimates within landscapes. Further, in laboratory experiments, the more deforestation‐tolerant species has critical thermal limits, and a jumping performance optimum, shifted ~2 °C warmer than those of the more forest‐affiliated species, corresponding to the ~3 °C difference in daytime maximum temperature that these species experience between habitats. Crucially, neither species strictly specializes on either habitat – instead habitat use is governed by regional environmental temperature. Both species track temperature along an elevational gradient, and shift their habitat use from cooler forest at lower elevations to warmer deforested pastures upslope. To generalize these conclusions, we expand our analysis to the entire mid‐elevational herpetological community of southern Costa Rica. We assess the climatological affinities of 33 amphibian and reptile species, showing that across both taxonomic classes, thermal niche predicts presence in deforested habitat as well as or better than many commonly used traits. These data suggest that warm‐adapted species carry a significant survival advantage amidst the synergistic impacts of land‐use conversion and climate change.     

Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish

Large‐bodied fish are critical for sustaining coral reef fisheries, but little is known about the vulnerability of these fish to global warming. This study examined the effects of elevated temperatures on the movement and activity patterns of the common coral trout Plectropomus leopardus (Serranidae), which is an important fishery species in tropical Australia and throughout the Indo West‐Pacific. Adult fish were collected from two locations on Australia's Great Barrier Reef (23°S and 14°S) and maintained at one of four temperatures (24, 27, 30, 33 °C). Following >4 weeks acclimation, the spontaneous swimming speeds and activity patterns of individuals were recorded over a period of 12 days. At 24–27 °C, spontaneous swimming speeds of common coral trout were 0.43–0.45 body lengths per second (bls^?1), but dropped sharply to 0.29 bls^?1 at 30 °C and 0.25 bls^?1 at 33 °C. Concurrently, individuals spent 9.3–10.6% of their time resting motionless on the bottom at 24–27 °C, but this behaviour increased to 14.0% at 30 °C and 20.0% of the time at 33 °C (mean ± SE). The impact of temperature was greatest for smaller individuals (<45 cm TL), showing significant changes to swimming speeds across every temperature tested, while medium (45–55 cm TL) and large individuals (>55 cm TL) were first affected by 30 °C and 33 °C, respectively. Importantly, there was some indication that populations can adapt to elevated temperature if presented with adequate time, as the high‐latitude population decreased significantly in swimming speeds at both 30 °C and 33 °C, while the low‐latitude population only showed significant reductions at 33 °C. Given that movement and activity patterns of large mobile species are directly related to prey encounter rates, ability to capture prey and avoid predators, any reductions in activity patterns are likely to reduce overall foraging and energy intake, limit the energy available for growth and reproduction, and affect the fitness and survival of individuals and populations.     

Climate‐induced warming imposes a threat to north European spring ecosystems

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate‐related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater‐dependent ecosystems (GDEs) remains poorly known. Here we report long‐term water temperature trends in 66 northern European cold‐water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968–2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high‐emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst‐case scenario, water temperature of these originally cold‐water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring‐fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold‐stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring‐fed streams. Climate change‐induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems.