Multistress effects on goldfish (Carassius auratus) behavior and metabolism

Crossed effects between climate change and chemical pollutions were identified on community structure and ecosystem functioning. Temperature rising affects the toxic properties of pollutants and the sensitiveness of organisms to chemicals stress. Inversely, chemical exposure may decrease the capacity of organisms to respond to environmental changes. The aim of our study was to assess the individual and crossed effects of temperature rising and pesticide contamination on fish. Goldfish, Carassius auratus, were exposed during 96 h at two temperatures (22 and 32 °C) to a mixture of common pesticides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin, and tebuconazol) at two environmentally relevant concentrations (total concentrations MIX1 = 8.4 μg L(-1) and MIX2 = 42 μg L(-1)). We investigated the sediment reworking behavior, which has a major ecological functional role. We also focused on three physiological traits from the cellular up to the whole individual level showing metabolic status of fish (protein concentration in liver and muscle, hepatosomatic index, and Fulton's condition factor). Individual thermal stress and low concentrations of pesticides decreased the sediment reworking activity of fish and entrained metabolic compensation with global depletion in energy stores. We found that combined chemical and thermal stresses impaired the capacity of fish to set up an efficient adaptive response. Our results strongly suggest that temperature will make fish more sensitive to water contamination by pesticides, raising concerns about wild fish conservation submitted to global changes.

Changes in composition, ecology and structure of high-mountain vegetation: a re-visitation study over 42 years

High-mountain ecosystems are increasingly threatened by climate change, causing biodiversity loss, habitat degradation and landscape modifications. However, very few detailed studies have focussed on plant biodiversity in the high mountains of the Mediterranean. In this study, we investigated the long-term changes that have occurred in the composition, structure and ecology of high-mountain vegetation in the central Apennines (Majella) over the last 42 years. We performed a re-visitation study, using historical and newly collected vegetation data to explore which ecological and structural features have been the most successful in coping with climatic changes. Vegetation changes were analysed by comparing geo-referenced phytosociological relevés collected in high-mountain habitats (dolines, gentle slopes and ridges) on the Majella massif in 1972 and in 2014. Composition analysis was performed by detrended correspondence analysis, followed by an analysis of similarities for statistical significance assessment and by similarity percentage procedure (SIMPER) for identifying which species indicate temporal changes. Changes in ecological and structural indicators were analysed by a permutational multivariate analysis of variance, followed by a post hoc comparison. Over the last 42 years, clear floristic changes and significant ecological and structural variations occurred. We observed a significant increase in the thermophilic and mesonitrophilic plant species and an increment in the frequencies of hemicryptophytes. This re-visitation study in the Apennines agrees with observations in other alpine ecosystems, providing new insights for a better understanding of the effects of global change on Mediterranean high-mountain biodiversity. The observed changes in floristic composition, the thermophilization process and the shift towards a more nutrient-demanding vegetation are likely attributable to the combined effect of higher temperatures and the increase in soil nutrients triggered by global change. The re-visitation approach adopted herein represents a powerful tool for studying climate-related changes in sensitive high-mountain habitats.

Velocity of density shifts in Finnish landbird species depends on their migration ecology and body mass

A multitude of studies confirm that species have changed their distribution ranges towards higher elevations and towards the poles, as has been predicted by climate change forecasts. However, there is large interspecific variation in the velocity of range shifts. From a conservation perspective, it is important to understand which factors explain variation in the speed and the extent of range shifts, as these might be related to the species' extinction risk. Here, we study shifts in the mean latitude of occurrence, as weighted by population density, in different groups of landbirds using 40 years of line transect data from Finland. Our results show that the velocity of such density shifts differed among migration strategies and increased with decreasing body size of species, while breeding habitat had no influence. The slower velocity of large species could be related to their longer generation time and lower per capita reproduction that can decrease the dispersal ability compared to smaller species. In contrast to some earlier studies of range margin shifts, resident birds and partial migrants showed faster range shifts, while fully migratory species were moving more slowly. The results suggest that migratory species, especially long-distance migrants, which often show decreasing population trends, might also have problems in adjusting their distribution ranges to keep pace with global warming.

Impact of global change on karst groundwater mineralization in the Jura Mountains

Chemistry of karst groundwater is related to conditions prevailing within the karst underground as well as at the land-surface within the recharge area. It is dominated by the dissolution of calcite and/or dolomite, which is strongly triggered by the presence of high pCO2 in soils at the top of the bedrock. Dissolution (water mineralization) is clearly influenced by soil pCO2, i.e. by global changes such as land-use, agriculture practices and climate change. However, the dissolution of carbonates is considered as a quite significant carbon sink for the Earth Atmosphere. Assessing the evolution of carbonate water mineralization can thus help characterizing the evolution of the carbon sink related to carbonate dissolution. The main goal of the study is to check the presence of trends with a high statistical relevance in groundwater quality data along the past 20 years. Causes potentially explaining the observed trends, such as land-use, agriculture practices and global warming are analyzed and discussed. The long term evolution of parameters related to carbonate dissolution are discussed and extrapolated as they may have consequences for the Global Carbon Cycle. The analysis is based on three independent data-sets stretching over more than 20 years each, coming from more than 40 sources. Statistical tests (Mann-Kendall trend test) indicate clear trends for compounds related to groundwater mineralization: increase in temperature (by about 0.5 °C/25 years), decrease in pH, increase in bicarbonate (by about 5%), and positive or negative trends for major ions directly related to human practices. Data and analysis suggest that carbonate dissolution is quickly increasing as a consequence of climate warming. Considering the largely accepted fact that carbonate dissolution acts as carbon sink for the atmosphere, it can be postulated that the observed increase could act as a negative feedback mechanism, tending to slow down the atmospheric increase in CO2.

Future Global Change and Cognition

The 11 articles in this issue explore how people respond to climate change and other global challenges. The articles pursue three broad strands of enquiry that relate (1) to the effects and causes of "skepticism" about climate change, (2) the purely cognitive challenges that are posed by a complex scientific issue, and (3) the ways in which climate change can be communicated to a wider audience. Cognitive science can contribute to understanding people's responses to global challenges in many ways, and it may also contribute to implementing solutions to those problems.

Heat waves reduce ecosystem carbon sink strength in a Eurasian meadow steppe

BACKGROUND

As a consequence of global change, intensity and frequency of extreme events such as heat waves (HW) have been increasing worldwide.

METHODS

By using a combination of continuous 60-year meteorological and 6-year tower-based carbon dioxide (CO2) flux measurements, we constructed a clear picture of a HWs effect on the dynamics of carbon, water, and vegetation on the Eurasian Songnen meadow steppe.

RESULTS

The number of HWs in the Songnen meadow steppe began increasing since the 1980s and the rate of occurrence has advanced since the 2010s to higher than ever before. HWs can reduce the grassland carbon flux, while net ecosystem carbon exchange (NEE) will regularly fluctuate for 4-5 days during the HW before decreasing. However, ecosystem respiration (Re) and gross ecosystem production (GEP) decline from the beginning of the HW until the end, where Re and GEP will decrease 30% and 50%, respectively. When HWs last five days, water-use efficiency (WUE) will decrease by 26%, soil water content (SWC) by 30% and soil water potential (SWP) will increase by 38%. In addition, the soil temperature will still remain high after the HW although the air temperature will recover to its previous state.

CONCLUSIONS

HWs, as an extreme weather event, have increased during the last two decades in the Songnen meadow steppe. HWs will reduce the carbon flux of the steppe and will cause a sustained impact. Drought may be the main reason why HWs decrease carbon flux. At the later stages of or after a HW, the ecosystem usually lacks water and the soil becomes so hot and dry that it prevents roots from absorbing enough water to maintain their metabolism. This is the main reason why this grassland carbon exchange decreases during and after HWs.

Temperature modulates phototrophic periphyton response to chronic copper exposure

Streams located in vineyard areas are highly prone to metal pollution. In a context of global change, aquatic systems are generally subjected to multi-stress conditions due to multiple chemical and/or physical pressures. Among various environmental factors that modulate the ecological effects of toxicants, special attention should be paid to climate change, which is driving an increase in extreme climate events such as sharp temperature rises. In lotic ecosystems, periphyton ensures key ecological functions such as primary production and nutrient cycling. However, although the effects of metals on microbial communities are relatively well known, there is scant data on possible interactions between temperature increase and metal pollution. Here we led a study to evaluate the influence of temperature on the response of phototrophic periphyton to copper (Cu) exposure. Winter communities, collected in a 8 °C river water, were subjected for six weeks to four thermal conditions in microcosms in presence or not of Cu (nominal concentration of 15 μg L(-1)). At the initial river temperature (8 °C), our results confirmed the chronic impact of Cu on periphyton, both in terms of structure (biomass, distribution of algal groups, diatomic composition) and function (photosynthetic efficiency). At higher temperatures (13, 18 and 23 °C), Cu effects were modulated. Indeed, temperature increase reduced Cu effects on algal biomass, algal class proportions, diatom assemblage composition and photosynthetic efficiency. This reduction of Cu effects on periphyton may be related to lower bioaccumulation of Cu and/or to selection of more Cu-tolerant species at higher temperatures.

Effects of nitrogen deposition on carbon cycle in terrestrial ecosystems of China: A meta-analysis

Nitrogen (N) deposition in China has increased greatly, but the general impact of elevated N deposition on carbon (C) dynamics in Chinese terrestrial ecosystems is not well documented. In this study we used a meta-analysis method to compile 88 studies on the effects of N deposition C cycling on Chinese terrestrial ecosystems. Our results showed that N addition did not change soil C pools but increased above-ground plant C pool. A large decrease in below-ground plant C pool was observed. Our result also showed that the impacts of N addition on ecosystem C dynamics depend on ecosystem type and rate of N addition. Overall, our findings suggest that 1) decreased below-ground plant C pool may limit long-term soil C sequestration; and 2) it is better to treat N-rich and N-limited ecosystems differently in modeling effects of N deposition on ecosystem C cycle.

Changes in the Synechococcus Assemblage Composition at the Surface of the East China Sea Due to Flooding of the Changjiang River

The aim of this study was to elucidate how flooding of the Changjiang River affects the assemblage composition of phycoerythrin-rich (PE-rich) Synechococcus at the surface of the East China Sea (ECS). During non-flooding summers (e.g., 2009), PE-rich Synechococcus usually thrive at the outer edge of the Changjiang River diluted water coverage (CDW; salinity ≤31 PSU). In the summer of 2010, a severe flood occurred in the Changjiang River basin. The plentiful freshwater injection resulted in the expansion of the CDW over half of the ECS and caused PE-rich cells to show a uniform distribution pattern, with decreased abundance compared with the non-flooding summer. The phylogenetic diversity of 16S rRNA gene sequences indicated that the flooding event also shifted the picoplankton community composition from being dominated by Synechococcus, mainly attributed to the clade II lineage, to various orders of heterotrophic bacteria, including Actinobacteria, Flavobacteria, α-Proteobacteria, and γ-Proteobacteria. As an increasing number of studies have proposed that global warming might result in more frequent floods, combining this perspective with the information obtained from our previous [1] and this studies yield a more comprehensive understanding of the relationship between the composition of the marine Synechococcus assemblage and global environmental changes.

Nitrogen supply modulates the effect of changes in drying-rewetting frequency on soil C and N cycling and greenhouse gas exchange

Climate change and atmospheric nitrogen (N) deposition are two of the most important global change drivers. However, the interactions of these drivers have not been well studied. We aimed to assess how the combined effect of soil N additions and more frequent soil drying-rewetting events affects carbon (C) and N cycling, soil:atmosphere greenhouse gas (GHG) exchange, and functional microbial diversity. We manipulated the frequency of soil drying-rewetting events in soils from ambient and N-treated plots in a temperate forest and calculated the Orwin & Wardle Resistance index to compare the response of the different treatments. Increases in drying-rewetting cycles led to reductions in soil NO3- levels, potential net nitrification rate, and soil : atmosphere GHG exchange, and increases in NH4+ and total soil inorganic N levels. N-treated soils were more resistant to changes in the frequency of drying-rewetting cycles, and this resistance was stronger for C- than for N-related variables. Both the long-term N addition and the drying-rewetting treatment altered the functionality of the soil microbial population and its functional diversity. Our results suggest that increasing the frequency of drying-rewetting cycles can affect the ability of soil to cycle C and N and soil : atmosphere GHG exchange and that the response to this increase is modulated by soil N enrichment.

Coupling Between and Among Ammonia Oxidizers and Nitrite Oxidizers in Grassland Mesocosms Submitted to Elevated CO2 and Nitrogen Supply

Many studies have assessed the responses of soil microbial functional groups to increases in atmospheric CO2 or N deposition alone and more rarely in combination. However, the effects of elevated CO2 and N on the (de)coupling between different microbial functional groups (e.g., different groups of nitrifiers) have been barely studied, despite potential consequences for ecosystem functioning. Here, we investigated the short-term combined effects of elevated CO2 and N supply on the abundances of the four main microbial groups involved in soil nitrification: ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (belonging to the genera Nitrobacter and Nitrospira) in grassland mesocosms. AOB and AOA abundances responded differently to the treatments: N addition increased AOB abundance, but did not alter AOA abundance. Nitrobacter and Nitrospira abundances also showed contrasted responses to the treatments: N addition increased Nitrobacter abundance, but decreased Nitrospira abundance. Our results support the idea of a niche differentiation between AOB and AOA, and between Nitrobacter and Nitrospira. AOB and Nitrobacter were both promoted at high N and C conditions (and low soil water content for Nitrobacter), while AOA and Nitrospira were favored at low N and C conditions (and high soil water content for Nitrospira). In addition, Nitrobacter abundance was positively correlated to AOB abundance and Nitrospira abundance to AOA abundance. Our results suggest that the couplings between ammonia and nitrite oxidizers are influenced by soil N availability. Multiple environmental changes may thus elicit rapid and contrasted responses between and among the soil ammonia and nitrite oxidizers due to their different ecological requirements.

Contrasting effects of elevated CO2 and warming on temperature sensitivity of soil organic matter decomposition in a Chinese paddy field

Climate changes including elevated CO2 and temperature have been known to affect soil carbon (C) storage, while the effects of climate changes on the temperature sensitivity of soil organic matter (SOM) are unclear. A 365-day laboratory incubation was used to investigate the temperature sensitivity for decomposition of labile (Q 10-L) and recalcitrant (Q 10-R) SOMs by comparing the time required to decompose a given amount of C at 25 and 35 °C. Soils were collected from a paddy field that was subjected to four treatments: ambient CO2 and temperature, elevated CO2 (500 μmol/mol), enhanced temperature (+2 °C), and their combination. The results showed that the temperature sensitivity of SOM decomposition increased with increasing SOM recalcitrance in this paddy soil (Q 10-L = 2.21 ± 0.16 vs. Q 10-R = 2.78 ± 0.42; mean ± SD). Elevated CO2 and enhanced temperature showed contrasting effects on the temperature sensitivity of SOM decomposition. Elevated CO2 stimulated Q 10-R but had no effect on Q 10-L; in contrast, enhanced temperature increased Q 10-L but had no effect on Q 10-R. Furthermore, the elevated CO2 combined with enhanced temperature treatment significantly increased Q 10-L and Q 10-R by 18.9 and 10.2 %, respectively, compared to the ambient conditions. Results suggested that the responses of SOM to temperature, especially for the recalcitrant SOM pool, were altered by climate changes. The greatly enhanced temperature sensitivity of SOM decomposition by elevated CO2 and temperature indicates that more CO2 will be released to the atmosphere and losses of soil C may be even greater than that previously expected in paddy field.

The response of tropical rainforests to drought-lessons from recent research and future prospects

KEY MESSAGE

We review the recent findings on the influence of drought on tree mortality, growth or ecosystem functioning in tropical rainforests. Drought plays a major role in shaping tropical rainforests and the response mechanisms are highly diverse and complex. The numerous gaps identified here require the international scientific community to combine efforts in order to conduct comprehensive studies in tropical rainforests on the three continents. These results are essential to simulate the future of these ecosystems under diverse climate scenarios and to predict the future of the global earth carbon balance.

CONTEXT

Tropical rainforest ecosystems are characterized by high annual rainfall. Nevertheless, rainfall regularly fluctuates during the year and seasonal soil droughts do occur. Over the past decades, a number of extreme droughts have hit tropical rainforests, not only in Amazonia but also in Asia and Africa. The influence of drought events on tree mortality and growth or on ecosystem functioning (carbon and water fluxes) in tropical rainforest ecosystems has been studied intensively, but the response mechanisms are complex.

AIMS

Herein, we review the recent findings related to the response of tropical forest ecosystems to seasonal and extreme droughts and the current knowledge about the future of these ecosystems.

RESULTS

This review emphasizes the progress made over recent years and the importance of the studies conducted under extreme drought conditions or in through-fall exclusion experiments in understanding the response of these ecosystems. It also points to the great diversity and complexity of the response of tropical rainforest ecosystems to drought.

CONCLUSION

The numerous gaps identified here require the international scientific community to combine efforts in order to conduct comprehensive studies in tropical forest regions. These results are essential to simulate the future of these ecosystems under diverse climate scenarios and to predict the future of the global earth carbon balance.

Home advantage? Decomposition across the freshwater-estuarine transition zone varies with litter origin and local salinity

Expected increases in the frequency and intensity of storm surges and river flooding may greatly affect the relative salinity of estuarine environments over the coming decades. In this experiment we used detritus from three contrasting environments (marine Fucus vesiculosus; estuarine Spartina anglica; terrestrial Quercus robur) to test the prediction that the decomposition of the different types of litter would be highest in the environment with which they are associated. Patterns of decomposition broadly fitted our prediction: Quercus detritus decomposed more rapidly in freshwater compared with saline conditions while Fucus showed the opposite trend; Spartina showed an intermediate response. Variation in macro-invertebrate assemblages was detected along the salinity gradient but with different patterns between estuaries, suggesting that breakdown rates may be linked in part to local invertebrate assemblages. Nonetheless, our results suggest that perturbation of salinity gradients through climate change could affect the process of litter decomposition and thus alter nutrient cycling in estuarine transition zones. Understanding the vulnerability of estuaries to changes in local abiotic conditions is important given the need to better integrate coastal proceses into a wider management framework at a time when coastlines are increasingly threatened by human activities.

Small-scale drivers: the importance of nutrient availability and snowmelt timing on performance of the alpine shrub Salix herbacea

Alpine plant communities are predicted to face range shifts and possibly extinctions with climate change. Fine-scale environmental variation such as nutrient availability or snowmelt timing may contribute to the ability of plant species to persist locally; however, variation in nutrient availability in alpine landscapes is largely unmeasured. On three mountains around Davos, Switzerland, we deployed Plant Root Simulator probes around 58 Salix herbacea plants along an elevational and microhabitat gradient to measure nutrient availability during the first 5 weeks of the summer growing season, and used in situ temperature loggers and observational data to determine date of spring snowmelt. We also visited the plants weekly to assess performance, as measured by stem number, fruiting, and herbivory damage. We found a wide snowmelt gradient which determined growing season length, as well as variations of an order of magnitude or more in the accumulation of 12 nutrients between different microhabitats. Higher nutrient availability had negative effects on most shrub performance metrics, for instance decreasing stem number and the proportion of stems producing fruits. High nutrient availability was associated with increased herbivory damage in early-melting microhabitats, but among late-emerging plants this pattern was reversed. We demonstrate that nutrient availability is highly variable in alpine settings, and that it strongly influences performance in an alpine dwarf shrub, sometimes modifying the response of shrubs to snowmelt timing. As the climate warms and human-induced nitrogen deposition continues in the Alps, these factors may contribute to patterns of local plants persistence.

Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa

Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha(-1) yr(-1)) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr(-1), the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr(-1) than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m(-2) and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr(-1). The δ (13)C for leaves averaged -14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ (15)N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha(-1)yr(-1) to -3.1 ± 0.2‰ under 80 kg N ha(-1)yr(-1), indicating that orchids preferentially assimilate NH4 (+) rather than NO3 (-) of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species.

Climate change, food systems and population health risks in their eco-social context

The establishment of ecological public health as crucial to modern public health is overdue. While the basic concepts have been gestating for decades, receptivity within broader public health has been limited. This position is changing, not least as the population-level impacts of climate change and, more broadly, of limits to growth are emerging from theory and forecasting into daily reality. This paper describes several key elements of ecological public health thinking. These include the 'environmental' risks to human health (often systemic and disruptive, rather than local and toxic) posed by climate change and other forms of adverse global environmental change. Closer recognition of the links between social and environmental factors has been urged--an 'eco-social' approach--and, relatedly, for greater co-operation between social and natural sciences. The authors revisit critics of capitalism who foresaw the global capture and transformation of ecosystems for material human ends, and their resultant despoliation. The perennial call within public health to reduce vulnerability by lessening poverty is more important than ever, given the multifactored threat to the health of the poor which is anticipated, assuming no radical strategies to alleviate these pressures. But enhanced health security for the poor requires more than the reconfiguring of social determinants; it also requires, as the overarching frame, ecological public health.

Breeding of ozone resistant rice: relevance, approaches and challenges

Tropospheric ozone concentrations have been rising across Asia, and will continue to rise during the 21st century. Ozone affects rice yields through reductions in spikelet number, spikelet fertility, and grain size. Moreover, ozone leads to changes in rice grain and straw quality. Therefore the breeding of ozone tolerant rice varieties is warranted. The mapping of quantitative trait loci (QTL) using bi-parental populations identified several tolerance QTL mitigating symptom formation, grain yield losses, or the degradation of straw quality. A genome-wide association study (GWAS) demonstrated substantial natural genotypic variation in ozone tolerance in rice, and revealed that the genetic architecture of ozone tolerance in rice is dominated by multiple medium and small effect loci. Transgenic approaches targeting tolerance mechanisms such as antioxidant capacity are also discussed. It is concluded that the breeding of ozone tolerant rice can contribute substantially to the global food security, and is feasible using different breeding approaches.

Elevated CO₂ mitigates drought and temperature-induced oxidative stress differently in grasses and legumes

Increasing atmospheric CO2 will affect plant growth, including mitigation of stress impact. Such effects vary considerably between species-groups. Grasses (Lolium perenne, Poa pratensis) and legumes (Medicago lupulina, Lotus corniculatus) were subjected to drought, elevated temperature and elevated CO2. Drought inhibited plant growth, photosynthesis and stomatal conductance, and induced osmolytes and antioxidants in all species. In contrast, oxidative damage was more strongly induced in the legumes than in the grasses. Warming generally exacerbated drought effects, whereas elevated CO2 reduced stress impact. In the grasses, photosynthesis and chlorophyll levels were more protected by CO2 than in the legumes. Oxidative stress parameters (lipid peroxidation, H2O2 levels), on the other hand, were generally more reduced in the legumes. This is consistent with changes in molecular antioxidants, which were reduced by elevated CO2 in the grasses, but not in the legumes. Antioxidant enzymes decreased similarly in both species-groups. The ascorbate-glutathione cycle was little affected by drought and CO2. Overall, elevated CO2 reduced drought effects in grasses and legumes, and this mitigation was stronger in the legumes. This is possibly explained by stronger reduction in H2O2 generation (photorespiration and NADPH oxidase), and a higher availability of molecular antioxidants. The grass/legume-specificity was supported by principal component analysis.

Sensitivity analysis of a sediment dynamics model applied in a Mediterranean river basin: global change and management implications

Climate change and land-use change are major factors influencing sediment dynamics. Models can be used to better understand sediment production and retention by the landscape, although their interpretation is limited by large uncertainties, including model parameter uncertainties. The uncertainties related to parameter selection may be significant and need to be quantified to improve model interpretation for watershed management. In this study, we performed a sensitivity analysis of the InVEST (Integrated Valuation of Environmental Services and Tradeoffs) sediment retention model in order to determine which model parameters had the greatest influence on model outputs, and therefore require special attention during calibration. The estimation of the sediment loads in this model is based on the Universal Soil Loss Equation (USLE). The sensitivity analysis was performed in the Llobregat basin (NE Iberian Peninsula) for exported and retained sediment, which support two different ecosystem service benefits (avoided reservoir sedimentation and improved water quality). Our analysis identified the model parameters related to the natural environment as the most influential for sediment export and retention. Accordingly, small changes in variables such as the magnitude and frequency of extreme rainfall events could cause major changes in sediment dynamics, demonstrating the sensitivity of these dynamics to climate change in Mediterranean basins. Parameters directly related to human activities and decisions (such as cover management factor, C) were also influential, especially for sediment exported. The importance of these human-related parameters in the sediment export process suggests that mitigation measures have the potential to at least partially ameliorate climate-change driven changes in sediment exportation.

The dynamics and drivers of fuel and fire in the Portuguese public forest

The assumption that increased wildfire incidence in the Mediterranean Basin during the last decades is an outcome of changes in land use warrants an objective analysis. In this study we examine how annual area burned (BA) in the Portuguese public forest varied in relation to environmental and human-influenced drivers during the 1943-2011 period. Fire behaviour models were used to describe fuel hazard considering biomass removal, cover type changes, area burned, post-disturbance fuel accumulation, forest age-classes distribution and fuel connectivity. Biomass removal decreased rapidly beyond the 1940s, which, along with afforestation, increased fuel hazard until the 1980s; a subsequent decline was caused by increased fire activity. Change point analysis indicates upward shifts in BA in 1952 and in 1973, both corresponding to six-fold increases. Fire weather (expressed by the 90th percentile of the Canadian FWI during summer) increased over the study period, accounting for 18 and 36% of log(BA) variation before 1974 and after 1973, respectively. Regression modelling indicates that BA responds positively to fire weather, fuel hazard and number of fires in descending order of importance; pre-summer and 2-year lagged precipitation respectively decrease and increase BA, but the effects are minor and non-significant when both variables are included in the model. Land use conflicts (expressed through more fires) played a role, but it was afforestation and agricultural abandonment that supported the fire regime shifts, explaining weather-drought as the current major driver of BA as well. We conclude that bottom-up factors, i.e. human-induced changes in landscape flammability and ignition density, can enhance or override the influence of weather-drought on the fire regime in Mediterranean humid regions. A more relevant role of fuel control in fire management policies and practices is warranted by our findings.

Temporal constraints on predation risk assessment in a changing world

Habitat degradation takes various forms and likely represents the most significant threat to our global biodiversity. Recently, we have seen considerable attention paid to increasing global CO2 emissions which lead to ocean acidification (OA). Other stressors, such as changing levels of ultraviolet radiation (UVR), also impact biodiversity but have received much less attention in the recent past. Here we examine fundamental questions about temporal aspects of risk assessment by coral reef damselfish and provide critical insights into how OA and UVR influence this assessment. Chemical cues released during a predator attack provide a rich source of information that other prey animals use to mediate their risk of predation and are the basis of the majority of trait-mediated indirect interactions in aquatic communities. However, we have surprisingly limited information about temporal aspects of risk assessment because we lack knowledge about how long chemical cues persist after they are released into the environment. Here, we showed that under ambient CO2 conditions (~385 μatm), alarm cues of ambon damselfish (Pomacentrus amboinensis) did not degrade within 30 min in the absence of ultraviolet radiation (UVR), but were degraded within 15 min when the CO2 was increased to ~905 μatm. In experiments that used filters to eliminate UVR, we found minimal degradation of alarm cues within 30 min, whereas under ambient UVR conditions, alarm cues were completely degraded within 15 min. Moreover, in the presence of both UVR and elevated CO2, alarm cues were broken down within 5 min. Our results highlight that alarm cues degrade surprisingly quickly under natural conditions and that anthropogenic changes have the potential to dramatically change rates of cue degradation in the wild. This has considerable implications for risk assessment and consequently the importance of trait-mediated indirect interactions in coral-reef communities.

Effect of warming rate on the critical thermal maxima of crabs, shrimp and fish

The threat of global warming has prompted numerous recent studies on the thermal tolerance of marine species. A widely used method to determine the upper thermal limit has been the Critical Thermal Maximum (CTMax), a dynamic method, meaning that temperature is increased gradually until a critical point is reached. This method presents several advantages over static methods, however, there is one main issue that hinders interpretation and comparison of CTMax results: the rate at which the temperature is increased. This rate varies widely among published protocols. The aim of the present work was to determine the effect of warming rate on CTMax values, using different animal groups. The influence of the thermal niche occupied by each species (intertidal vs subtidal) and habitat (intertidal vs subtidal) was also investigated. CTMax were estimated at three different rates: 1°Cmin(-1), 1°C30min(-1) and 1°Ch(-1), in two species of crab, Eurypanopeus abbreviatus and Menippe nodifrons, shrimp Palaemon northropi and Hippolyte obliquimanus and fish Bathygobius soporator and Parablennius marmoreus. While there were significant differences in the effect of warming rates for some species, for other species warming rate produced no significant differences (H. obliquimanus and B. soporator). While in some species slower warming rates lead to lower CTMax values (P. northropi and P. marmoreus) in other species the opposite occurred (E. abbreviatus and M. nodifrons). Biological group has a significant effect with crabs' CTMax increasing at slower warming rates, which did not happen for shrimp and fish. Subtidal species presented lower CTMax, at all warming rates tested. This study highlights the importance of estimating CTMax values at realistic rates that species encounter in their environment and thus have an ecological value.

Influence of light history on the photosynthetic and motility responses of Gymnodinium chlorophorum exposed to UVR and different temperatures

In the wake of global climate change, phytoplankton productivity and species composition is expected to change due to altered external conditions such as temperature, nutrient accessibility, pH and exposure to solar visible (PAR) and ultraviolet radiation (UVR). The previous light history is also of importance for the performance of phytoplankton cells. In order to assess the combined impacts of UVR and temperature on the dinoflagellate Gymnodinium chlorophorum we analyzed the effective photochemical quantum yield (Y), relative electron transport rate vs. irradiance curves (rETR vs. I), percentage of motile cells and swimming velocity. Cells were grown at three different temperatures (15, 20 and 25 °C) and two PAR intensities: low light (LL, 100 μmol photons m(-2) s(-1)) and high light (HL, 250 μmol photons m(-2) s(-1)). Pre-acclimated cells were then exposed to either PAR only (P), PAR+UV-A (PA) or PAR+UV-A+UV-B (PAB) radiation at two different irradiances, followed by a recovery period in darkness. The Y decreased during exposure, being least inhibited in P and most in PAB treatments. Inhibition was higher and recovery slower in LL-grown cells than in HL-grown cells at 15° and 20 °C, but the opposite occurred at 25 °C, when exposed to high irradiances. Maximal values of rETR were determined at t0 as compared to the different (before and after exposure) radiation treatments. The effects of temperature and UVR on rETR were antagonistic in LL-grown cells (i.e., less UVR inhibition at higher temperature), while it was synergistic in HL cells. Swimming velocity and percentage of motile cells were not affected at all tested temperatures and exposure regimes, independent of the light history. Our results indicate that, depending on the previous light history, increased temperature and UVR as predicted under climate change conditions, can have different interactions thus conditioning the photosynthetic response of G. chlorophorum.

Transforming management of tropical coastal seas to cope with challenges of the 21st century

Over 1.3 billion people live on tropical coasts, primarily in developing countries. Many depend on adjacent coastal seas for food, and livelihoods. We show how trends in demography and in several local and global anthropogenic stressors are progressively degrading capacity of coastal waters to sustain these people. Far more effective approaches to environmental management are needed if the loss in provision of ecosystem goods and services is to be stemmed. We propose expanded use of marine spatial planning as a framework for more effective, pragmatic management based on ocean zones to accommodate conflicting uses. This would force the holistic, regional-scale reconciliation of food security, livelihoods, and conservation that is needed. Transforming how countries manage coastal resources will require major change in policy and politics, implemented with sufficient flexibility to accommodate societal variations. Achieving this change is a major challenge - one that affects the lives of one fifth of humanity.