Jacopo Giuntoli  Aikaterini K. Boulamanti  Sara Corrado  Mahsa Motegh  Alessandro Agostini  David Baxter 《Global Change Biology Bioenergy》2013,5(5):497-512

This study presents the life cycle assessment of electricity generation from straw bales and pellets. Straw is the most abundant biomass residue in Europe and its use for energy purposes is promoted on the premise of high greenhouse gas savings. This assumption has delayed the study of sustainability of straw‐fired systems on a broader sense and the literature on the topic is almost absent. This study uses data from specific literature and emissions inventories to model a number of straw pathways. The plant modeled is a medium‐scale straw‐fired power plant of 50 MWth capacity. The results show that electricity from straw‐fired power plants can indeed realize high greenhouse gas savings compared both with existing coal plants and with the European electricity mix. The savings are in the range 70–94%. The influence of the geographical origin of straw is analyzed by using datasets for the cultivation of wheat in five different European countries. The highest emissions are recorded for the case of straw from Spain due to the small yields, whereas cultivation processes in United Kingdom and the Netherlands show high environmental impacts due to the high level of fertilization. Other environmental impacts are evaluated, such as acidification potential, eutrophication, particulate matter emissions, and photochemical ozone formation. The bioenergy system scores worse than the current European electricity mix for all the categories. However, it is important to notice that in Spain and United Kingdom the straw system shows lower impacts compared with the local average coal electricity. Finally, the study investigates the ‘break‐even’ distance at which the higher emissions from the pellets production are paid off by the saved emissions in their transport compared with the bales. The results show that no reasonable break‐even distance exists for road transport, whereas advantages for pellets are evident in any configuration for transoceanic transport.  相似文献   

    

Luke F. Dodd  Jonathan H. Grabowski  Michael F. Piehler  Isaac Westfield  Justin B. Ries 《Proceedings. Biological sciences / The Royal Society》2015,282(1810)

Anthropogenic elevation of atmospheric CO₂ is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism''s ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO₂ levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour.  相似文献   

    

S. J. McCoy  C. A. Pfister 《Ecology letters》2014,17(4):475-483

As the ocean environment changes over time, a paucity of long‐term data sets and historical comparisons limits the exploration of community dynamics over time in natural systems. Here, we used a long‐term experimental data set to present evidence for a reversal of competitive dominance within a group of crustose coralline algae (CCA) from the 1980s to present time in the northeast Pacific Ocean. CCA are cosmopolitan species distributed globally, and dominant space holders in intertidal and subtidal systems. Competition experiments showed a markedly lower competitive ability of the previous competitively dominant species and a decreased response of competitive dynamics to grazer presence. Competitive networks obtained from survey data showed concordance between the 1980s and 2013, yet also revealed reductions in interaction strengths across the assemblage. We discuss the potential role of environmental change, including ocean acidification, in altered ecological dynamics in this system.  相似文献   

    

Ulisse Cardini  Vanessa N. Bednarz  Rachel A. Foster  Christian Wild 《Ecology and evolution》2014,4(9):1706-1727

Tropical coral reefs are among the most productive and diverse ecosystems, despite being surrounded by ocean waters where nutrients are in short supply. Benthic dinitrogen (N₂) fixation is a significant internal source of “new” nitrogen (N) in reef ecosystems, but related information appears to be sparse. Here, we review the current state (and gaps) of knowledge on N₂ fixation associated with coral reef organisms and their ecosystems. By summarizing the existing literature, we show that benthic N₂ fixation is an omnipresent process in tropical reef environments. Highest N₂ fixation rates are detected in reef‐associated cyanobacterial mats and sea grass meadows, clearly showing the significance of these functional groups, if present, to the input of new N in reef ecosystems. Nonetheless, key benthic organisms such as hard corals also importantly contribute to benthic N₂ fixation in the reef. Given the usually high coral coverage of healthy reef systems, these results indicate that benthic symbiotic associations may be more important than previously thought. In fact, mutualisms between carbon (C) and N₂ fixers have likely evolved that may enable reef communities to mitigate N limitation. We then explore the potential effects of the increasing human interferences on the process of benthic reef N₂ fixation via changes in diazotrophic populations, enzymatic activities, or availability of benthic substrates favorable to these microorganisms. Current knowledge indicates positive effects of ocean acidification, warming, and deoxygenation and negative effects of increased ultraviolet radiation on the amount of N fixed in coral reefs. Eutrophication may either boost or suppress N₂ fixation, depending on the nutrient becoming limiting. As N₂ fixation appears to play a fundamental role in nutrient‐limited reef ecosystems, these assumptions need to be expanded and confirmed by future research efforts addressing the knowledge gaps identified in this review.  相似文献   

    

Michael Y. Roleda  Jaz N. Morris  Christina M. McGraw  Catriona L. Hurd 《Global Change Biology》2012,18(3):854-864

The worldwide effects of ocean acidification (OA) on marine species are a growing concern. In temperate coastal seas, seaweeds are dominant primary producers that create complex habitats and supply energy to higher trophic levels. Studies on OA and macroalgae have focused on calcifying species and adult stages, but critically, they have overlooked the microscopic stages of the reproductive life cycle, which, for other anthropogenic stressors, e.g., UV‐B radiation, are the most susceptible life‐history phase. Also, environmental cues and stressors can cause changes in the sex ratio, which has implications for the mating system and recruitment success. Here, we report the effects of pH (7.59–8.50) on meiospore germination and sex determination for the giant kelp, Macrocystis pyrifera (Laminariales), in the presence and absence of additional dissolved inorganic carbon (DIC). Lowered pH (7.59–7.60, using HCl‐only) caused a significant reduction in germination, whereas added DIC had the opposite effect, indicating that increased CO₂ at lower pH ameliorates physiological stress. This finding also highlights the importance of appropriate manipulation of seawater carbonate chemistry when testing the effects of OA on photosynthetic organisms. The proportion of male to female gametophytes did not vary significantly between treatments, suggesting that pH was not a primary environmental modulator of sex. Relative to the baseline (pH 8.19), gametophytes were 32% larger under moderate OA (pH 7.86) and 10% larger under extreme OA (pH 7.61). We suggest that metabolically active cells can compensate for the acidification of seawater. This homeostatic function minimizes the negative effects of lower pH (high H⁺ ions) on cellular activity. The 6–9% reduction in germination success under extreme OA suggests that meiospores of M. pyrifera may be resistant to future OA.  相似文献   

  总被引：1，自引：0，他引：1  

Peter J. Edmunds  Darren Brown  Vincent Moriarty 《Global Change Biology》2012,18(7):2173-2183

This study tested the hypothesis that the response of corals to temperature and pCO ₂ is consistent between taxa. Juvenile massive Porites spp. and branches of P. rus from the back reef of Moorea were incubated for 1 month under combinations of temperature (29.3 °C and 25.6 °C) and pCO ₂ (41.6 Pa and 81.5 Pa) at an irradiance of 599 μmol quanta m^?2 s^?1. Using microcosms and CO₂ gas mixing technology, treatments were created in a partly nested design (tanks) with two between‐plot factors (temperature and pCO ₂), and one within‐plot factor (taxon); calcification was used as a dependent variable. pCO ₂ and temperature independently affected calcification, but the response differed between taxa. Massive Porites spp. was largely unaffected by the treatments, but P. rus grew 50% faster at 29.3 °C compared with 25.6 °C, and 28% slower at 81.5 Pa vs. 41.6 Pa CO₂. A compilation of studies placed the present results in a broader context and tested the hypothesis that calcification for individual coral genera is independent of pH, [HCO₃ ^?], and [CO₃ ^2?]. Unlike recent reviews, this analysis was restricted to studies reporting calcification in units that could be converted to nmol CaCO₃ cm^?2 h^?1. The compilation revealed a high degree of variation in calcification as a function of pH, [HCO₃ ^?], and [CO₃ ^2?], and supported three conclusions: (1) studies of the effects of ocean acidification on corals need to pay closer attention to reducing variance in experimental outcomes to achieve stronger synthetic capacity, (2) coral genera respond in dissimilar ways to pH, [HCO₃ ^?], and [CO₃ ^2?], and (3) calcification of massive Porites spp. is relatively resistant to short exposures of increased pCO ₂, similar to that expected within 100 y.  相似文献   

    

Hong D. Nguyen  Steve S. Doo  Natalie A. Soars  Maria Byrne 《Global Change Biology》2012,18(8):2466-2476

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.  相似文献   

    

Sue‐Ann Watson  Lloyd S. Peck  Paul A. Tyler  Paul C. Southgate  Koh Siang Tan  Robert W. Day  Simon A. Morley 《Global Change Biology》2012,18(10):3026-3038

There is great concern over the future effects of ocean acidification on marine organisms, especially for skeletal calcification, yet little is known of natural variation in skeleton size and composition across the globe, and this is a prerequisite for identifying factors currently controlling skeleton mass and thickness. Here, taxonomically controlled latitudinal variations in shell morphology and composition were investigated in bivalve and gastropod molluscs, brachiopods, and echinoids. Total inorganic content, a proxy for skeletal CaCO₃, decreased with latitude, decreasing seawater temperature, and decreasing seawater carbonate saturation state (for CaCO₃ as calcite (Ω_cal)) in all taxa. Shell mass decreased with latitude in molluscs and shell inorganic content decreased with latitude in buccinid gastropods. Shell thickness decreased with latitude in buccinid gastropods (excepting the Australian temperate buccinid) and echinoids, but not brachiopods and laternulid clams. In the latter, the polar species had the thickest shell. There was no latitudinal trend in shell thickness within brachiopods. The variation in trends in shell thickness by taxon suggests that in some circumstances ecological factors may override latitudinal trends. Latitudinal gradients may produce effects similar to those of future CO₂‐driven ocean acidification on CaCO₃ saturation state. Responses to latitudinal trends in temperature and saturation state may therefore be useful in informing predictions of organism responses to ocean acidification over long‐term adaptive timescales.  相似文献   

    

David J. Suggett  Jason M. Hall‐Spencer  Riccardo Rodolfo‐Metalpa  Toby G. Boatman  Ross Payton  D. Tye Pettay  Vivienne R. Johnson  Mark E. Warner  Tracy Lawson 《Global Change Biology》2012,18(10):3015-3025

Increased seawater pCO₂, and in turn ‘ocean acidification’ (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef‐forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA‐like conditions can simultaneously enhance the ecological success of non‐calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft‐bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO₂ gradient at Vulcano, Italy. Both gross photosynthesis (P_G) and respiration (R) increased with pCO₂ indicating that the increased growth was, at least in part, fuelled by bottom up (CO₂ stimulation) of metabolism. The increase of P_G outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO₂ limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO₂, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non‐calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO₂. Understanding how CO₂‐enhanced productivity of non‐ (and less‐) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress.  相似文献   

    

Tyler G. Evans  Francis Chan  Bruce A. Menge  Gretchen E. Hofmann 《Molecular ecology》2013,22(6):1609-1625

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