Participation of actin filaments,myosin and phosphatidylinositol 3‐kinase in the formation and polarisation of tetraspore germ tube of Gelidium floridanum (Rhodophyta,Florideophyceae)

• This study aimed to examine the evidence of direct interaction among actin, myosin and phosphatidylinositol 3‐kinase (PI3K) in the polarisation and formation of the tetraspore germ tube of Gelidium floridanum.
• After release, tetraspores were exposed to cytochalasin B, latrunculin B, LY294002 and BDM for a period of 6 h.
• In control samples, formation of the germ tube occurred after the experimental period, with cellulose formation and elongated chloroplasts moving through the tube region in the presence of F‐actin. In the presence of cytochalasin B, an inhibitor of F‐actin, latrunculin B, an inhibitor of G‐actin, and BDM, a myosin inhibitor, tetraspores showed no formation of the germ tube or cellulose. Spherical‐shaped chloroplasts were observed in the central region with a few F‐actin filaments in the periphery of the cytoplasm. Tetraspores treated with LY294002, a PI3K inhibitor, showed no formation of the tube at the highest concentrations. Polarisation of cytoplasmic contents did not occur, only cellulose formation.
• It was concluded that F‐actin directs the cell wall components and contributes to the maintenance of chloroplast shape and elongation during germ tube formation. PI3K plays a fundamental role in signalling for the asymmetric polarisation of F‐actin. Thus, F‐actin regulates the polarisation and germination processes of tetraspores of G. floridanum.

     

Effects of brefeldin A on the endomembrane system and germ tube formation of the tetraspore of Gelidium floridanum (Rhodophyta,Florideophyceae)

Gelidium floridanum W.R. Taylor tetraspores are units of dispersal and are responsible for substrate attachment. This study aimed to examine evidence of direct interaction between germ tube formation and Golgi activity during tetraspore germination of G. floridanum. After release, the tetraspores were incubated with brefeldin A (BFA) in concentrations of 4 and 8 μM over a 6 h period. The controls and treatments were analyzed with light, fluorescence (FM4‐64 dye) and transmission electron microscopy. In the control samples, the Golgi bodies were responsible for germ tube formation. In contrast, BFA‐treated samples were observed to inhibit spore adhesion and germ tube formation. These tetraspores also showed an increase in volume (≥30 μm width). BFA treatment also resulted in the disassembly of Golgi cisternae and the formation of vesiculated areas of the cytoplasm, blocking the secretion of protein and amorphous matrix polysaccharides. When stained with FM4‐64, the control samples showed fluorescence in the apical region of the germ tube, but the treated samples showed an intense fluorescence throughout the cytoplasm. From these results, we can conclude that the germ tube is formed by the incorporation of vesicles derived from Golgi. Thus, vesicle secretion and Golgi organization are basic processes and essential in adhesion and tube formation. By blocking the secretion of protein and amorphous matrix polysaccharides, BFA treatment precluded tetraspore germination.     

Effects of light and temperature on the attachment and development of <Emphasis Type="BoldItalic">Gloiopeltis tenax</Emphasis> and <Emphasis Type="BoldItalic">Gloiopeltis furcata</Emphasis> tetraspores

Two 60-day experiments were conducted to study the influence of photon flux density (PFD) and temperature on the attachment and development of Gloiopeltis tenax and Gloiopeltis furcata tetraspores. In the first experiment, tetraspores of the two Gloiopeltis species were incubated at five temperature ranges (8°C, 12°C, 16°C, 20°C, 24°C) under a constant PFD of 80 μmol photons m⁻² s⁻¹ with a photoperiod of 12:12. In a second experiment, tetraspores were incubated under five PFD gradients (30, 55, 80, 105, 130 μmol photons m⁻² s⁻¹) at a constant temperature of 16°C with a photoperiod of 12:12. Maximum density of attached tetraspores was observed at 16°C for both species. Maximum per cent of spore germinating into disc was recorded at 12–16°C for G. tenax and 8–12°C for G. furcata. Maximum per cent of discs producing erect axes for G. tenax and G. furcata were recorded at 24°C and 20°C, respectively. Light had no significant effect on tetraspore attachment and developing into disc, but it affected the growth, sprouting and survival of its discs. Under 30–55 μmol photons m⁻² s⁻¹, the discs of the two species of Gloiopeltis did not form thallus until the end of the experiment. Optimum PFD range for G. tenax discs was 80–105 μmol photons m⁻² s⁻¹, whilst it was 80–130 μmol photons m⁻² s⁻¹ for G. furcata. Results presented in this study are expected to assist the progress of artificial seeding of Gloiopeltis.     

UNUSUAL PHENOMENA IN THE LIFE HISTORIES OF FLORIDEAE IN CULTURE1

Several Florideae grown in natural seawater media under defined laboratory conditions have interesting and unusual life histories. Antithamnion occidentale males of one generation produced tetraspores that gave rise to nonsporangiate males. The functional females of A. pygmaeum developed spermatangia and tetrasporangia; the tetraspores formed new females. Antithamnion defectum tetrasporophytes of one generation bore spermatangia in addition to tetrasporangia; the tetraspores gave rise to typical gametophytes. Tetraspores from successive generations of Callitham-nion sp. developed into tetrasporophytes and males but no females were produced. Functional female gametophytes of Platythamnion sp. bore abortive tetrasporangia. Field-collected plants of two species of Fauchea produced tetraspores that yielded additional sporangiate plants: those of F. pygmaea being bispo-rangiate and tetrasporangiate, and those of F. lacini-ata being strictly tetrasporangiate. Male plants of Pleonosporium vancouverianum from a running seawater table bore spermatangia and polysporangia when collected. The same plants in unialgal culture produced only spermatangia.     

The influence of irradiance on the severity of thermal bleaching in sea anemones that host anemonefish

Entacmaea quadricolor is a geographically widespread species of sea anemone that forms a three-way symbiosis with anemonefish and Symbiodinium. This species dominates the reef substrata at North Solitary Island, Australia, which is located in a region identified as a climate change hot spot. Their geographic location places these anemones under significant threat from rising ocean temperatures, although their upper thermal limit and risk of bleaching are unknown. To address this knowledge gap, anemones were exposed to one of four temperatures (23, 25, 27, or 29°C) and one of two irradiance treatments (high or low light) over 6 days. At moderate temperatures (27°C, 1°C above summer average), anemone bleaching was characterised by symbiont expulsion, while extreme temperatures (29°C) resulted in an additional loss of photosynthetic pigments from within symbionts, and in some cases, host mortality. Irradiance influenced the susceptibility to thermal stress with high light promoting the bleaching response, along with significant reductions in the effective quantum yield of anemone symbionts. The long-term loss of photosystem II photochemical efficiency within in hospite symbionts was observed during exposure to temperatures exceeding the summer average, indicating photosynthetic damage. The resident Symbiodinium, identified as clade C using 28S rRNA gene sequences, therefore represents the partner within the symbiosis that is likely to be most vulnerable to rising seawater temperatures. Results suggest that E. quadricolor is living within approximately 1°C of the upper thermal maximum at the Solitary Islands, and given the predictions for rising seawater temperature on Australia’s east coast, the thermal threshold at which bleaching will occur is expected to be reached and exceeded more frequently in the future.     

Arbuscular mycorrhizal influence on growth,photosynthetic pigments,osmotic adjustment and oxidative stress in tomato plants subjected to low temperature stress

The influence of the arbuscular mycorrhizal (AM) fungus, Glomus mosseae, on characteristics of growth, photosynthetic pigments, osmotic adjustment, membrane lipid peroxidation and activity of antioxidant enzymes in leaves of tomato (Lycopersicon esculentum cv Zhongzha105) plants was studied in pot culture under low temperature stress. The tomato plants were placed in a sand and soil mixture at 25°C for 6 weeks, and then subjected to 8°C for 1 week. AM symbiosis decreased malondialdehyde (MDA) content in leaves. The contents of photosynthetic pigments, sugars and soluble protein in leaves were higher, but leaf proline content was lower in mycorrhizal than non-mycorrhizal plants. AM colonization increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) in leaves. The results indicate that the AM fungus is capable of alleviating the damage caused by low temperature stress on tomato plants by reducing membrane lipid peroxidation and increasing the photosynthetic pigments, accumulation of osmotic adjustment compounds, and antioxidant enzyme activity. Consequently, arbuscular mycorrhiza formation highly enhanced the cold tolerance of tomato plant, which increased host biomass and promoted plant growth.     

Antimicrobial and stress responses to increased temperature and bacterial pathogen challenge in the holobiont of a reef‐building coral

Global increases in coral disease prevalence have been linked to ocean warming through changes in coral‐associated bacterial communities, pathogen virulence and immune system function. However, the interactive effects of temperature and pathogens on the coral holobiont are poorly understood. Here, we assessed three compartments of the holobiont (host, Symbiodinium and bacterial community) of the coral Montipora aequituberculata challenged with the pathogen Vibrio coralliilyticus and the commensal bacterium Oceanospirillales sp. under ambient (27°C) and elevated (29.5 and 32°C) seawater temperatures. Few visual signs of bleaching and disease development were apparent in any of the treatments, but responses were detected in the holobiont compartments. V. coralliilyticus acted synergistically and negatively impacted the photochemical efficiency of Symbiodinium at 32°C, while Oceanospirillales had no significant effect on photosynthetic efficiency. The coral, however, exhibited a minor response to the bacterial challenges, with the response towards V. coralliilyticus being significantly more pronounced, and involving the prophenoloxidase‐activating system and multiple immune system‐related genes. Elevated seawater temperatures did not induce shifts in the coral‐associated bacterial community, but caused significant gene expression modulation in both Symbiodinium and the coral host. While Symbiodinium exhibited an antiviral response and upregulated stress response genes, M. aequituberculata showed regulation of genes involved in stress and innate immune response processes, including immune and cytokine receptor signalling, the complement system, immune cell activation and phagocytosis, as well as molecular chaperones. These observations show that M. aequituberculata is capable of maintaining a stable bacterial community under elevated seawater temperatures and thereby contributes to preventing disease development.     

Acclimation of photosynthetic temperature optima of temperate and boreal tree species in response to experimental forest warming

Rising temperatures caused by climate change could negatively alter plant ecosystems if temperatures exceed optimal temperatures for carbon gain. Such changes may threaten temperature‐sensitive species, causing local extinctions and range migrations. This study examined the optimal temperature of net photosynthesis (T_opt) of two boreal and four temperate deciduous tree species grown in the field in northern Minnesota, United States under two contrasting temperature regimes. We hypothesized that T_opt would be higher in temperate than co‐occurring boreal species, with temperate species exhibiting greater plasticity in T_opt, resulting in better acclimation to elevated temperatures. The chamberless experiment, located at two sites in both open and understory conditions, continuously warmed plants and soils during three growing seasons. Results show a modest, but significant shift in T_opt of 1.1 ± 0.21 °C on average for plants subjected to a mean 2.9 ± 0.01 °C warming during midday hours in summer, and shifts with warming were unrelated to species native ranges. The 1.1 °C shift in T_opt with 2.9 °C warming might be interpreted as suggesting limited capacity to shift temperature response functions to better match changes in temperature. However, T_opt of warmed plants was as well‐matched with prior midday temperatures as T_opt of plants in the ambient treatment, and T_opt in both treatments was at a level where realized photosynthesis was within 90–95% of maximum. These results suggest that seedlings of all species were close to optimizing photosynthetic temperature responses, and equally so in both temperature treatments. Our study suggests that temperate and boreal species have considerable capacity to match their photosynthetic temperature response functions to prevailing growing season temperatures that occur today and to those that will likely occur in the coming decades under climate change.     

Photosynthesis of temperate Eucalyptus globulus trees outside their native range has limited adjustment to elevated CO2 and climate warming

Eucalyptus species are grown widely outside of their native ranges in plantations on all vegetated continents of the world. We predicted that such a plantation species would show high potential for acclimation of photosynthetic traits across a wide range of growth conditions, including elevated [CO₂] and climate warming. To test this prediction, we planted temperate Eucalyptus globulus Labill. seedlings in climate‐controlled chambers in the field located >700 km closer to the equator than the nearest natural occurrence of this species. Trees were grown in a complete factorial combination of elevated CO₂ concentration (eC; ambient [CO₂] +240 ppm) and air warming treatments (eT; ambient +3 °C) for 15 months until they reached ca. 10 m height. There was little acclimation of photosynthetic capacity to eC and hence the CO₂‐induced photosynthetic enhancement was large (ca. 50%) in this treatment during summer. The warming treatment significantly increased rates of both carboxylation capacity (V_cmax) and electron transport (J_max) (measured at a common temperature of 25 °C) during winter, but decreased them significantly by 20–30% in summer. The photosynthetic CO₂ compensation point in the absence of dark respiration (Γ*) was relatively less sensitive to temperature in this temperate eucalypt species than for warm‐season tobacco. The temperature optima for photosynthesis and J_max significantly changed by about 6 °C between winter and summer, but without further adjustment from early to late summer. These results suggest that there is an upper limit for the photosynthetic capacity of E. globulus ssp. globulus outside its native range to acclimate to growth temperatures above 25 °C. Limitations to temperature acclimation of photosynthesis in summer may be one factor that defines climate zones where E. globulus plantation productivity can be sustained under anticipated global environmental change.     

Contrasting responses of steppe Stipa ssp. to warming and precipitation variability

Climate change, characterized by warming and precipitation variability, restricted the growth of plants in arid and semiarid areas, and various functional traits are impacted differently. Comparing responses of functional traits to warming and precipitation variability and determining critical water threshold of dominate steppe grasses from Inner Mongolia facilitates the identification and monitoring of water stress effects. A combination of warming (ambient temperature, +1.5°C and +2.0°C) and varying precipitation (?30%, ?15%, ambient, +15%, and +30%) manipulation experiments were performed on four Stipa species (S. baicalensis, S. bungeana, S. grandis, and S. breviflora) from Inner Mongolia steppe. The results showed that the functional traits of the four grasses differed in their responses to precipitation, but they shared common sensitive traits (root/shoot ratio, R/S, and specific leaf area; SLA) under ambient temperature condition. Warming increased the response of the four grasses to changing precipitation, and these differences in functional traits resulted in changes to their total biomass, with leaf area, SLA, and R/S making the largest contributions. Critical water thresholds of the four grasses were identified, and warming led to their higher optimum precipitation requirements. The four steppe grasses were able to adapt better to mild drought (summer precipitation decreased by 12%–28%) when warming 1.5°C rather than 2.0°C. These results indicated that if the Paris Agreement to limit global warming to 1.5°C will be accomplished, this will increase the probability for sustained viability of the Stipa steppes in the next 50–100 years.     

Ocean acidification and warming scenarios increase microbioerosion of coral skeletons

Biological mediation of carbonate dissolution represents a fundamental component of the destructive forces acting on coral reef ecosystems. Whereas ocean acidification can increase dissolution of carbonate substrates, the combined impact of ocean acidification and warming on the microbioerosion of coral skeletons remains unknown. Here, we exposed skeletons of the reef‐building corals, Porites cylindrica and Isopora cuneata, to present‐day (Control: 400 μatm – 24 °C) and future pCO₂–temperature scenarios projected for the end of the century (Medium: +230 μatm – +2 °C; High: +610 μatm – +4 °C). Skeletons were also subjected to permanent darkness with initial sodium hypochlorite incubation, and natural light without sodium hypochlorite incubation to isolate the environmental effect of acidic seawater (i.e., Ω_aragonite <1) from the biological effect of photosynthetic microborers. Our results indicated that skeletal dissolution is predominantly driven by photosynthetic microborers, as samples held in the dark did not decalcify. In contrast, dissolution of skeletons exposed to light increased under elevated pCO₂–temperature scenarios, with P. cylindrica experiencing higher dissolution rates per month (89%) than I. cuneata (46%) in the high treatment relative to control. The effects of future pCO₂–temperature scenarios on the structure of endolithic communities were only identified in P. cylindrica and were mostly associated with a higher abundance of the green algae Ostreobium spp. Enhanced skeletal dissolution was also associated with increased endolithic biomass and respiration under elevated pCO₂–temperature scenarios. Our results suggest that future projections of ocean acidification and warming will lead to increased rates of microbioerosion. However, the magnitude of bioerosion responses may depend on the structural properties of coral skeletons, with a range of implications for reef carbonate losses under warmer and more acidic oceans.     

Temperature response of photosynthetic light‐ and carbon‐use characteristics in the red seaweed Gracilariopsis lemaneiformis (Gracilariales,Rhodophyta)

The red seaweed Gracilariopsis is an important crop extensively cultivated in China for high‐quality raw agar. In the cultivation site at Nanao Island, Shantou, China, G. lemaneiformis experiences high variability in environmental conditions like seawater temperature. In this study, G. lemaneiformis was cultured at 12, 19, or 26°C for 3 weeks, to examine its photosynthetic acclimation to changing temperature. Growth rates were highest in G. lemaneiformis thalli grown at 19°C, and were reduced with either decreased or increased temperature. The irradiance‐saturated rate of photosynthesis (P_max) decreased with decreasing temperature, but increased significantly with prolonged cultivation at lower temperatures, indicating the potential for photosynthesis acclimation to lower temperature. Moreover, P_max increased with increasing temperature (~30 μmol O₂ · g^?1FW · h^?1 at 12°C to 70 μmol O₂ · g^?1FW · h^?1 at 26°C). The irradiance compensation point for photosynthesis (I_c) decreased significantly with increasing temperature (28 μmol photons · m^?2 · s^?1 at high temperature vs. 38 μmol photons · m^?2 · s^?1 at low temperature). Both the photosynthetic light‐ and carbon‐use efficiencies increased with increasing growth or temperatures (from 12°C to 26°C). The results suggested that the thermal acclimation of photosynthetic performance of G. lemaneiformis would have important ecophysiological implications in sea cultivation for improving photosynthesis at low temperature and maintaining high standing biomass during summer. Ongoing climate change (increasing atmospheric CO₂ and global warming) may enhance biomass production in G. lemaneiformis mariculture through the improved photosynthetic performances in response to increasing temperature.     

Thermotolerance of the photosynthetic light reactions in two <Emphasis Type="Italic">Phaseolus</Emphasis> species: a comparative study

The common bean (Phaseolus vulgaris L.) is sensitive to high temperature, while an ecologically contrasting species (Phaseolus acutifolius A. Gray) is cultivated successfully in hot environments. In this study, the two bean species were respectively acclimated to a control temperature of 25 °C and a moderately elevated temperature of 35 °C in order to compare the thermotolerance capabilities of their photosynthetic light reactions. Growth at 35 °C appeared to have no obvious adverse effect on the photosynthetic activities of the two beans, but changed their thermotolerance. After a short period of heat shock (40 °C for up to 4 h), the photosynthetic activities of 25 °C-grown P. vulgaris declined more severely than those of P. acutifolius grown at 25 °C, implying that the basal thermotolerance of P. vulgaris is inferior to that of P. acutifolius. But after acclimating to 35 °C, the thermotolerances of the two species were both greatly enhanced to about the same level, clearly demonstrating the induction of acquired thermotolerance in their chloroplasts, and P. vulgaris could be as good as P. acutifolius. Temperature acclimation also changed plants’ resistance to photoinhibition in a manner similar to those toward heat stress. In addition, acquisition of tolerance to heat and strong irradiance would reduce the dependency of the two beans on xanthophyll pigments to dissipate heat, and also seemed irrelevant to the agents with antioxidant activities such as SOD.     

Mediterranean warming triggers seagrass (Posidonia oceanica) shoot mortality

Rapid warming of the Mediterranean Sea threatens marine biodiversity, particularly key ecosystems already stressed by other impacts such as Posidonia oceanica meadows. A 6‐year monitoring of seawater temperature and annual P. oceanica shoot demography at Cabrera Archipelago National Park (Balearic Islands, Western Mediterranean) allowed us to determine if warming influenced shoot mortality and recruitment rates of seagrasses growing in relative pristine environments. The average annual maximum temperature for 2002–2006 was 1 °C above temperatures recorded in 1988–1999 (26.6 °C), two heat waves impacted the region (with seawater warming up to 28.83 °C in 2003 and to 28.54 °C in 2006) and the cumulative temperature anomaly, above the 1988–1999 mean annual maximum temperature, during the growing season (i.e. degree‐days) ranged between 0 °C in 2002 and 70 °C in 2003. Median annual P. oceanica shoot mortality rates varied from 0.067 year^?1 in 2002 to 0.123 year^?1 in 2003, and exceeded recruitment rates in all stations and years except in shallow stations for year 2004. Interannual fluctuations in shoot recruitment were independent of seawater warming (P>0.05). P. oceanica meadows experienced a decline throughout the study period at an average rate of ?0.050±0.020 year^?1. Interannual variability in P. oceanica shoot mortality was coupled (R²>0.40) to seawater warming variability and increasing water depth: shoot mortality rates increased by 0.022 year^?1 (i.e. an additional 2% year^?1) for each additional degree of annual maximum temperature and by 0.001 year^?1 (i.e. 0.1% year^?1) for each accumulated degree water temperature remained above 26.6 °C during the growing season. These results demonstrate that P. oceanica meadows are highly vulnerable to warming, which can induce steep declines in shoot abundance as well indicating that climate change poses a significant threat to this important habitat.     

Warming effects on growth and physiology in the seedlings of the two conifers <Emphasis Type="Italic">Picea asperata</Emphasis> and <Emphasis Type="Italic">Abies faxoniana</Emphasis> under two contrasting light conditions

The short-term effects of two levels of air temperature (ambient and warmed) and light (full light and ca. 10% of full light regimes) on the early growth and physiology of Picea asperata and Abies faxoniana seedlings was determined using open-top chambers (OTC). The OTC manipulation increased mean air temperature and soil surface temperature by 0.51°C and 0.34°C under the 60-year plantation, and 0.69°C and 0.41°C under the forest opening, respectively. Warming, with either full-light or low-light conditions, generally caused a significant increase in plant growth, biomass accumulation, and stimulated photosynthetic performance of P. asperata seedlings. However, the warming of A. faxoniana seedlings only significantly increased their growth under low-light conditions, possibly as a result of photoinhibition caused by full light, which may shield and/or impair the effects of warming manipulation, per se, on the growth and physiological performance of A. faxoniana seedlings. In response to warming, P. asperata seedlings allocated relatively more biomass to roots and A. faxoniana more to foliage under similar environments. This might provide A. faxoniana with an adaptive advantage when soil moisture was not limiting and an advantage to P. asperata if substantial moisture stress occurred. Warming markedly increased the efficiency of PSII in terms of the increase in F _v/F _m and photosynthetic pigment concentrations for the two conifer seedlings, but the effects of warming were generally more pronounced under low-light conditions than under full-light conditions. On balance, this study suggested that warming had a beneficial impact on the early growth and development of conifer seedlings, at least in the short term. Consequently, warming may lead to changes in forest regeneration dynamics and species composition for subalpine coniferous ecosystems under future climate change.     

Thermal Acclimation of Respiration and Photosynthesis in the Marine Macroalga Gracilaria lemaneiformis (Gracilariales,Rhodophyta)

The responses of respiration and photosynthesis to temperature fluctuations in marine macroalgae have the potential to significantly affect coastal carbon fluxes and sequestration. In this study, the marine red macroalga Gracilaria lemaneiformis was cultured at three different temperatures (12, 19, and 26°C) and at high‐ and low‐nitrogen (N) availability, to investigate the acclimation potential of respiration and photosynthesis to temperature change. Measurements of respiratory and photosynthetic rates were made at five temperatures (7°C–33°C). An instantaneous change in temperature resulted in a change in the rates of respiration and photosynthesis, and the temperature sensitivities (i.e., the Q₁₀ value) for both the metabolic processes were lower in 26°C‐grown algae than 12°C‐ or 19°C‐grown algae. Both respiration and photosynthesis acclimated to long‐term changes in temperature, irrespective of the N availability under which the algae were grown; respiration displayed strong acclimation, whereas photosynthesis only exhibited a partial acclimation response to changing growth temperatures. The ratio of respiration to gross photosynthesis was higher in 12°C‐grown algae, but displayed little difference between the algae grown at 19°C and 26°C. We propose that it is unlikely that respiration in G. lemaneiformis would increase significantly with global warming, although photosynthesis would increase at moderately elevated temperatures.     

Communal nesting under climate change: fitness consequences of higher incubation temperatures for a nocturnal lizard

Communal nesting lizards may be vulnerable to climate warming, particularly if air temperatures regulate nest temperatures. In southeastern Australia, velvet geckos Oedura lesueurii lay eggs communally inside rock crevices. We investigated whether increases in air temperatures could elevate nest temperatures, and if so, how this could influence hatching phenotypes, survival, and population dynamics. In natural nests, maximum daily air temperature influenced mean and maximum daily nest temperatures, implying that nest temperatures will increase under climate warming. To determine whether hotter nests influence hatchling phenotypes, we incubated eggs under two fluctuating temperature regimes to mimic current ‘cold’ nests (mean = 23.2 °C, range 10–33 °C) and future ‘hot’ nests (27.0 °C, 14–37 °C). ‘Hot’ incubation temperatures produced smaller hatchlings than did cold temperature incubation. We released individually marked hatchlings into the wild in 2014 and 2015, and monitored their survival over 10 months. In 2014 and 2015, hot‐incubated hatchlings had higher annual mortality (99%, 97%) than cold‐incubated (11%, 58%) or wild‐born hatchlings (78%, 22%). To determine future trajectories of velvet gecko populations under climate warming, we ran population viability analyses in Vortex and varied annual rates of hatchling mortality within the range 78– 96%. Hatchling mortality strongly influenced the probability of extinction and the mean time to extinction. When hatchling mortality was >86%, populations had a higher probability of extinction (PE: range 0.52– 1.0) with mean times to extinction of 18–44 years. Whether future changes in hatchling survival translate into reduced population viability will depend on the ability of females to modify their nest‐site choices. Over the period 1992–2015, females used the same communal nests annually, suggesting that there may be little plasticity in maternal nest‐site selection. The impacts of climate change may therefore be especially severe on communal nesting species, particularly if such species occupy thermally challenging environments.     

Detecting latitudinal and altitudinal expansion of invasive bamboo Phyllostachys edulis and Phyllostachys bambusoides (Poaceae) in Japan to project potential habitats under 1.5°C–4.0°C global warming

Rapid expansion of exotic bamboos has lowered species diversity in Japan's ecosystems by hampering native plant growth. The invasive potential of bamboo, facilitated by global warming, may also affect other countries with developing bamboo industries. We examined past (1975–1980) and recent (2012) distributions of major exotic bamboos (Phyllostachys edulis and P. bambusoides) in areas adjacent to 145 weather stations in central and northern Japan. Bamboo stands have been established at 17 sites along the latitudinal and altitudinal distributional limit during the last three decades. Ecological niche modeling indicated that temperature had a strong influence on bamboo distribution. Using mean annual temperature and sun radiation data, we reproduced bamboo distribution (accuracy = 0.93 and AUC (area under the receiver operating characteristic curve) = 0.92). These results infer that exotic bamboo distribution has shifted northward and upslope, in association with recent climate warming. Then, we simulated future climate data and projected the climate change impact on the potential habitat distribution of invasive bamboos under different temperature increases (i.e., 1.5°C, 2.0°C, 3.0°C, and 4.0°C) relative to the preindustrial period. Potential habitats in central and northern Japan were estimated to increase from 35% under the current climate (1980–2000) to 46%–48%, 51%–54%, 61%–67%, and 77%–83% under 1.5°C, 2.0°C, 3.0°C, and 4.0°C warming levels, respectively. These infer that the risk areas can increase by 1.3 times even under a 1.5°C scenario and expand by 2.3 times under a 4.0°C scenario. For sustainable ecosystem management, both mitigation and adaptation are necessary: bamboo planting must be carefully monitored in predicted potential habitats, which covers most of Japan.     

High temperature promotes the inhibition of Zn2+ to physiological performance of green tide-forming seaweed Ulva prolifera

Since 2007, Ulva prolifera-induced green tide occurred every year in the offshore waters of the Yellow Sea in China, which have resulted in large economic loss and heavy damage to local marine ecosystems. In addition, ocean warming and heavy metal pollution have become two main marine environmental issues in the world. However, the interactive effects of ocean warming and zinc (Zn²⁺) exposure on macroalgae remain poorly studied. An experiment was conducted to determine the relative growth rate (RGR) and photosynthetic performance at different temperatures (15, 20, 25 °C) and Zn²⁺ concentrations (0, 0.0026, 0.026, 0.26, and 0.52 mg/L). Results showed that low temperature (15 °C) increased the RGR under the medium levels of Zn²⁺ (0.026 mg/L) compared with high temperature (20 and 25 °C). On the other hand, at 20 and 25 °C the inhibition of Zn²⁺ on the PSII quantum yield and electron transport rate of U. prolifera was promoted. Furthermore, dark respiration rate increased with increases in temperature and Zn²⁺ concentration, while at the high temperature, the ratio of the net photosynthetic rate and dark respiration rate were (P_n/R_d) inhibited, and the inhibition was positively related to the Zn²⁺ concentration at ≥0.26 mg/L. in addition, the photoprotective ability was hindered under high temperature (20 and 25 °C) and the potential photosynthetic ability was restricted under higher levels of Zn²⁺ concentration. We conclude that ocean warming could promote the inhibition effects of heavy metal pollutions on physiological performance of U. prolifera, and probably other marine microalgae as well, on which future studies shall be conducted     

Will climate warming exceed lethal photosynthetic temperature thresholds of lichens in a southern African arid region?

Predicted elevated temperatures and a shift from a winter to summer rainfall pattern associated with global warming could result in the exposure of hydrated lichens during summer to more numerous temperature extremes that exceed their thermal thresholds. This hypothesis was tested by measuring lethal temperature thresholds under laboratory and natural conditions for four epilithic lichen species (Xanthoparmelia austro‐africana, X. hyporhytida, Xanthoparmelia sp., Xanthomaculina hottentotta) occurring on quartz gravel substrates at a hot arid inland site two epigeous lichen species (Teloschistes capensis, Ramalina sp.) occurring on gypsum‐rich topsoil at a warm humid coastal site. Extrapolated lethal temperatures for photosynthetic quantum yield under laboratory conditions were up to 4°C higher for lichens from a dry inland site than those from a humid coastal site. Lethal temperatures extrapolated for photosynthetic quantum yield at a saturating photosynthetic photon flux density of ≥11,000 μmol photons m^?2 s^?1 under natural conditions were up to 6°C higher for lichens from the dry inland site than the more humid coastal site. It is concluded that only under atypical conditions of lichen exposure in a hydrated state to temperature extremes at high midday solar irradiances during summer could lethal photosynthetic thresholds in sensitive lichen species be potentially exceeded, but whether the increased frequency of such conditions with climate warming would lead to increased likelihood of lichen mortality is debatable.