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A cal. 20-year-resolution pollen record from Gonghai Lake presented the detailed process of mountain vegetation succession and East Asian Summer Monsoon (EASM) changes since the last deglaciation in Shanxi Province, North China. Modern vegetation distribution and lake surface pollen assemblages suggested that the fossil pollen mainly came from local and surrounding vegetation in Gonghai Lake, which reflected the elevational changes of plant communities in study area. From 14,700 to 11,100 cal. yr BP, open forests and mountain meadows dominated by shrubs and herbaceous species in surrounding area, suggesting a weak EASM with less precipitation. In the period between 11,100 and 7300 cal. yr BP, bushwoods and grasses were gradually replaced by mixed broadleaf-conifer forest, first developed by pioneer species of Betula and Populus and then replaced by Picea, Pinus, and Quercus, implying an enhanced EASM and increased temperature and precipitation. During the period of 7300–5000 cal. yr BP, warm-fitted trees became expanded and widespread, indicating a climax community of mixed broadleaf-conifer forest and warm and humid climate with higher temperature and sufficient precipitation and the strongest period of EASM. From 5000 to 1600 cal. yr BP, Pinus pollen increased, but Quercus pollen decreased, showing the breakup of the climax community and the recession of the EASM. Since 1600 cal. yr BP, under the threats of land reclamation and deforestation, forest cover sharply decreased, and mountain grass lands were developed. The EASM changes inferred from pollen record of Gonghai Lake were asynchronous to the oxygen isotope records of stalagmites from southern China. We suggest that the existence of remnant Northern Hemisphere ice sheets and relative low sea levels might hampered the northward penetration of the EASM in early Holocene, which caused the maximum monsoon precipitation to reach northern China until mid-Holocene.

A priority of the industrial applications of microalgae is the reduction of production costs while maximizing algae biomass productivity. The purpose of this study was to carry out a comprehensive evaluation of the effects of pH control on the production of Nannochloropsis gaditana in tubular photobioreactors under external conditions while considering the environmental, biological, and operational parameters of the process. Experiments were carried out in 3.0 m3 tubular photobioreactors under outdoor conditions. The pH values evaluated were 6.0, 7.0, 8.0, 9.0, and 10.0, which were controlled by injecting pure CO2 on-demand. The results have shown that the ideal pH for microalgal growth was 8.0, with higher values of biomass productivity (Pb) (0.16 g L-1 d-1), and CO2 use efficiency ([Formula: see text]) (74.6% w w-1); [Formula: see text]/biomass value obtained at this pH (2.42 [Formula: see text] gbiomass-1) was close to the theoretical value, indicating an adequate CO2 supply. At this pH, the system was more stable and required a lower number of CO2 injections than the other treatments. At pH 6.0, there was a decrease in the Pb and [Formula: see text]; cultures at pH 10.0 exhibited a lower Pb and photosynthetic efficiency as well. These results imply that controlling the pH at an optimum value allows higher CO2 conversions in biomass to be achieved and contributes to the reduction in costs of the microalgae production process.

Coral reefs in the tropical Pacific region are exposed to a range of anthropogenic local pressures. Climate change is exacerbating local impacts, causing unprecedented declines in coral reef habitats and bringing negative socio-economic consequences to Pacific communities who depend heavily on coral reefs for food, income and livelihoods. Continued increases in greenhouse gas emissions will drive future climate change, which will accelerate coral reef degradation. Traditional systems of resource governance in Pacific island nations provide a foundation to address local pressures and build reef resilience to climate change. Management and adaptation options should build on the regional diversity of governance systems and traditional knowledge to support community-based initiatives and cross-sectoral cooperation to address local pressures and minimize climate change impacts. Such an inclusive approach will offer enhanced opportunities to develop and implement transformative adaptation solutions, particularly in remote and regional areas where centralized management does not extend.

The gas production behavior of methane hydrate in porous media using the huff and puff method was investigated in the Cubic Hydrate Simulator (CHS), a novel developed three-dimensional 5.8-L cubic pressure vessel. Three horizontal layers equally divide the CHS into four regions. A 9-spot distribution of the vertical wells, a single horizontal well and a 25-spot distribution of the thermometers are arranged on each layer, respectively. The vertical wells at the axis of the CHS were used as the injection and production wells. The huff and puff method includes the injection, soaking and production stages. The amount of water injected and produced, the gas production rate, the percentage of the hydrate dissociation and the gas-to-water ratio were evaluated. Under the thermodynamic conditions in this work, the gas production from the sediment in this work using the huff and puff method is economically profitable from the relative criterion point of view. The sensitivity analysis demonstrates the dependence of the gas production on the initial hydrate saturation, and the temperature and the injection rate of the injected hot water.

Among the various quality elements which the Water Framework Directive requires should be monitored are macroalgae. One aspect of these is the presence, in transitional waters particularly, of large blooms of opportunistic macroalgae, such as Ulva and Enteromorpha. Within the United Kingdom (UK) and Republic of Ireland (RoI) there are currently no set ecological quality objectives or standards for macroalgae. Nor are there standard methods for monitoring macroalgal blooms, although various combinations of aerial photography, remote sensing and measurements on the ground are used. This paper attempts to set a logical framework for the prioritisation of sites for monitoring, the development of a tiered monitoring procedure and the derivation of thresholds for classification. Draft threshold limits for percentage cover and biomass of macroalgae have been derived from the literature. The importance of secondary effects and physico-chemical parameters is discussed.

As a consequence of increasing atmospheric CO(2), the world's oceans are warming and slowly becoming more acidic (ocean acidification, OA) and profound changes in marine ecosystems are certain. Calcification is one of the primary targets for studies of the impact of CO(2)-driven climate change in the oceans and one of the key marine groups most likely to be impacted by predicted climate change events are the echinoderms. Echinoderms are a vital component of the marine environment with representatives in virtually every ecosystem, where they are often keystone ecosystem engineers. This paper reviews and analyses what is known about the impact of near-future ocean acidification on echinoderms. A global analysis of the literature reveals that echinoderms are surprisingly robust to OA and that important differences in sensitivity to OA are observed between populations and species. However, this is modulated by parameters such as (1) exposure time with rare longer term experiments revealing negative impacts that are hidden in short or midterm ones; (2) bottlenecks in physiological processes and life-cycle such as stage-specific developmental phenomena that may drive the whole species responses; (3) ecological feedback transforming small scale sub lethal effects into important negative effects on fitness. We hypothesize that populations/species naturally exposed to variable environmental pH conditions may be pre-adapted to future OA highlighting the importance to understand and monitor environmental variations in order to be able to to predict sensitivity to future climate changes. More stress ecology research is needed at the frontier between ecotoxicology and ecology, going beyond standardized tests using model species in order to address multiple water quality factors (e.g. pH, temperature, toxicants) and organism health. However, available data allow us to conclude that near-future OA will have negative impact on echinoderm taxa with likely significant consequences at the ecosystem level.

AbstractThe landscape of the Barrow Peninsula in northern Alaska is thought to have formed over centuries to millennia, and is now dominated by ice‐wedge polygonal tundra that spans drained thaw‐lake basins and interstitial tundra. In nearby tundra regions, studies have identified a rapid increase in thermokarst formation (i.e., pits) over recent decades in response to climate warming, facilitating changes in polygonal tundra geomorphology. We assessed the future impact of 100 years of tundra geomorphic change on peak growing season carbon exchange in response to: (i) landscape succession associated with the thaw‐lake cycle; and (ii) low, moderate, and extreme scenarios of thermokarst pit formation (10%, 30%, and 50%) reported for Alaskan arctic tundra sites. We developed a 30 × 30 m resolution tundra geomorphology map (overall accuracy:75%; Kappa:0.69) for our ~1800 km² study area composed of ten classes; drained slope, high center polygon, flat‐center polygon, low center polygon, coalescent low center polygon, polygon trough, meadow, ponds, rivers, and lakes, to determine their spatial distribution across the Barrow Peninsula. Land‐atmosphere CO2 and CH4 flux data were collected for the summers of 2006–2010 at eighty‐two sites near Barrow, across the mapped classes. The developed geomorphic map was used for the regional assessment of carbon flux. Results indicate (i) at present during peak growing season on the Barrow Peninsula, CO2 uptake occurs at ‐902.3 106gC‐CO2 day−1 (uncertainty using 95% CI is between −438.3 and −1366 106gC‐CO2 day−1) and CH4 flux at 28.9 106gC‐CH4 day−1(uncertainty using 95% CI is between 12.9 and 44.9 106gC‐CH4 day−1), (ii) one century of future landscape change associated with the thaw‐lake cycle only slightly alter CO2 and CH4 exchange, while (iii) moderate increases in thermokarst pits would strengthen both CO2 uptake (−166.9 106gC‐CO2 day−1) and CH4 flux (2.8 106gC‐CH4 day−1) with geomorphic change from low to high center polygons, cumulatively resulting in an estimated negative feedback to warming during peak growing season.

River ecosystems are most often subject to multiple co-occurring anthropogenic stressors. Mediterranean streams are particularly affected by water scarcity and organic loads that commonly lead to a simultaneous reduction in flow and increasing depletion of dissolved oxygen. In the present study, the single and combined effects of water scarcity (flow velocity reduction) and dissolved oxygen depletion were used to evaluate alterations of drifting macroinvertebrates on a channel mesocosm system, by employing a multiple trait-based approach. Our main findings confirmed that the impact of the two combined stressors can be implicated in alterations of ecosystem functions as result of the changes in proportions of biological traits. Overall, our results showed that, individually, flow velocity reduction and a severe oxygen depletion promoted a shift in community traits. In more detail, biological traits describing the dispersal of organisms and their respiration showed the strongest responses. The respiration mode responded to low flow with drift increase of gill breathers and decrease of individuals with tegument, whereas dispersal was clearly affected by the combination of stressors. Resistance through eggs was higher with the single effect of flow reduction, while swimmers´ relative abundance increased in individuals that drift after exposure to the combination of stressors. Thus, while flow reduction alone is expected to specifically filter out the gill breathers and the egg producers, the combination of stressors will impact more drastically organism's dispersal and swimmers. Such changes in biological traits can result in variations in ecosystem functioning through, for example, local changes in biomass, secondary production, stream metabolism as well as resulting in biodiversity losses or alterations of its distribution patterns.