Posts Tagged 'mitigation'

Differing responses of the estuarine bivalve Limecola balthica to lowered water pH caused by potential CO2 leaks from a sub-seabed storage site in the Baltic Sea: an experimental study

Highlights

  • CO2-induced seawater acidification affected behavioral and physiological traits of Limecola balthica from the Baltic Sea.
  • In response to hypercapnia, the bivalves approached the sediment surface and increased respiration rates.
  • Lower seawater pH reduced shell weight and growth, and increased soft tissue weight that places L. balthica in a unique position among marine invertebrates.

Abstract

Sub-Seabed CCS is regarded as a key technology for the reduction of CO2 emissions, but little is known about the mechanisms through which leakages from storage sites impact benthic species. In this study, the biological responses of the infaunal bivalve Limecola balthica to CO2-induced seawater acidification (pH 7.7, 7.0, and 6.3) were quantified in 56-day mesocosm experiments. Increased water acidity caused changes in behavioral and physiological traits, but even the most acidic conditions did not prove to be fatal. In response to hypercapnia, the bivalves approached the sediment surface and increased respiration rates. Lower seawater pH reduced shell weight and growth, while it simultaneously increased soft tissue weight; this places L. balthica in a somewhat unique position among marine invertebrates.

Continue reading ‘Differing responses of the estuarine bivalve Limecola balthica to lowered water pH caused by potential CO2 leaks from a sub-seabed storage site in the Baltic Sea: an experimental study’

Investigating the collective effect of two ocean acidification adaptation strategies on juvenile clams (Venerupis philippinarum)

Anthropogenic CO2 emissions have altered Earth’s climate system at an unprecedented rate, causing global climate change and ocean acidification. Surface ocean pH has increased by 26% since the industrial era and is predicted to increase another 100% by 2100. Additional stress from abrupt changes in carbonate chemistry in conjunction with other natural and anthropogenic impacts may push populations over critical thresholds. Bivalves are particularly vulnerable to the impacts of acidification during early life-history stages. Two substrate additives, shell hash and macrophytes, have been proposed as potential ocean acidification adaptation strategies for bivalves but there is limited research into their effectiveness. This study uses a split plot design to examine four different combinations of the two substratum treatments on juvenile Venerupis philippinarum settlement, survival, and growth and on local water chemistry at Fidalgo Bay and Skokomish Delta, Washington. Results show no macrophyte or shell hash treatment effect on V. philippinarum settlement or survival. A significant macrophyte treatment effect was detected on clam growth, with mean length higher when macrophytes were absent regardless of the presence or absence of shell hash. Additionally, the macrophyte treatment appeared to have an opposite effect on pH than was anticipated, where pH was higher outside of macrophyte beds than inside. Although these results do not support the use of either treatment as an ocean acidification adaptation strategy, the mixed results reported in the literature for both treatments highlight the nascent nature of this research. As atmospheric CO2 concentrations continue to increase, there is an exigent need for additional studies to determine the specific conditions under which these strategies might help produce conditions conducive to settlement, growth, and survival of bivalves and other calcifying organisms. Such research could help guide local adaptation actions, especially among resource-dependent communities that rely on sustainable fisheries for their health and well-being.

Continue reading ‘Investigating the collective effect of two ocean acidification adaptation strategies on juvenile clams (Venerupis philippinarum)’

Ecological performance of construction materials subject to ocean climate change

Artificial structures will be increasingly utilized to protect coastal infrastructure from sea-level rise and storms associated with climate change. Although it is well documented that the materials comprising artificial structures influence the composition of organisms that use them as habitat, little is known about how these materials may chemically react with changing seawater conditions, and what effects this will have on associated biota. We investigated the effects of ocean warming, acidification, and type of coastal infrastructure material on algal turfs. Seawater acidification resulted in greater covers of turf, though this effect was counteracted by elevated temperatures. Concrete supported a greater cover of turf than granite or high-density polyethylene (HDPE) under all temperature and pH treatments, with the greatest covers occurring under simulated ocean acidification. Furthermore, photosynthetic efficiency under acidification was greater on concrete substratum compared to all other materials and treatment combinations. These results demonstrate the capacity to maximise ecological benefits whilst still meeting local management objectives when engineering coastal defense structures by selecting materials that are appropriate in an ocean change context. Therefore, mitigation efforts to offset impacts from sea-level rise and storms can also be engineered to alter, or even reduce, the effects of climatic change on biological assemblages.

Continue reading ‘Ecological performance of construction materials subject to ocean climate change’

Future marine ecosystem drivers, biodiversity, and fisheries maximum catch potential in Pacific Island countries and territories under climate change

Highlights

  • Under the RCP 8.5 scenario, tropical Pacific temperature will rise by ≥ 3 °C by 2100.
  • This is accompanied by declines in dissolved oxygen, pH, and net primary production.
  • This will lead to local extinctions of up to 80% of marine species in some regions.
  • 9 of 17 Pacific Island entities experience ≥ 50% declines in maximum catch potential.
  • Impacts can be greatly reduced by mitigation measures under the RCP 2.6 scenario.


Abstract

The increase in anthropogenic CO2 emissions over the last century has modified oceanic conditions, affecting marine ecosystems and the goods and services that they provide to society. Pacific Island countries and territories are highly vulnerable to these changes because of their strong dependence on ocean resources, high level of exposure to climate effects, and low adaptive capacity. Projections of mid-to-late 21st century changes in sea surface temperature (SST), dissolved oxygen, pH, and net primary productivity (NPP) were synthesized across the tropical Western Pacific under strong climate mitigation and business-as-usual scenarios. These projections were used to model impacts on marine biodiversity and potential fisheries catches. Results were consistent across three climate models, indicating that SST will rise by ≥ 3 °C, surface dissolved oxygen will decline by ≥ 0.01 ml L−1, pH will drop by ≥ 0.3, and NPP will decrease by 0.5 g m−2 d−1 across much of the region by 2100 under the business-as-usual scenario. These changes were associated with rates of local species extinction of > 50% in many regions as fishes and invertebrates decreased in abundance or migrated to regions with conditions more suitable to their bio-climate envelope. Maximum potential catch (MCP) was projected to decrease by > 50% across many areas, with the largest impacts in the western Pacific warm pool. Climate change scenarios that included strong mitigation resulted in substantial reductions of MCP losses, with the area where MCP losses exceeded 50% reduced from 74.4% of the region under business-as-usual to 36.0% of the region under the strong mitigation scenario.

Continue reading ‘Future marine ecosystem drivers, biodiversity, and fisheries maximum catch potential in Pacific Island countries and territories under climate change’

A perspective for reducing environmental impacts of mussel culture in Algeria

Purpose

In Algeria, the Ministry of Fisheries and Halieutic Resources has designed a strategic plan for the development of marine aquaculture for the years 2015–2025, which aims at expanding the annual production of Mediterranean mussel from less than 150 metric tonnes year−1 in 2013 to 7600 metric tonnes year−1 in 2025. We used Life Cycle Assessment (LCA) for evaluating the environmental impact of suspended mussel culture in Algeria and suggest management practices which could reduce it.

Methods

In order to estimate the current and perspective impact of this industry, we (1) applied LCA to one of the few farms currently operating in Algeria and (2) investigated two management scenarios for the farms to be established in the future in the same coastal area. The first scenario (Comp_S) represents the continuity with the current situation, in which each farm is competing with the other ones and is therefore managing the production cycle independently. In the second scenario (Coop_S), mussel farms are grouped in an aquaculture management area and shared the same facilities for post-processing harvested mussels before sending them to the market. The midpoint-based CML-IA method baseline 2000 V 3.01 was employed using SimaPro software. Furthermore, we carried out a Monte Carlo simulation, in order to assess the uncertainty in the results.

Results and discussion

The analysis focused on impact categories related to acidification and global warming potential. We took into account the energy consumptions (electricity and vessel fuel), the rearing infrastructure, including longlines, and a building for stabling, grading, and packing the mussel. Electricity contributes with 38.1 and 31.8 % respectively to global warming potential (GWP) and acidification, while fuel consumption contributes with 19.5 % to GWP and 31.8 % to acidification. Results of this work are compared with other LCA studies recently carried out in France (Aubin and Fontaine 2014) and in Spain (Iribarren et al. 2010c).

Conclusions

The LCA results show that important reductions in environmental impacts could be attained if the mussel farming activity would be operated according to the cooperative scenario here proposed. In this case, the environmental benefits will be a reduction of 3150 MJ and 156 kg CO2 eq per metric tonne of mussel produced, compared with the alternative scenario. The results of this study suggest that LCA should be applied to the seafood production sector in Algeria, in order to identify best management practices.

Continue reading ‘A perspective for reducing environmental impacts of mussel culture in Algeria’

Understanding the impacts of anthropogenic stressors on species, ecosystems, and fishing communities

Anthropogenic modifications of marine environments result from a variety of activities and have effects across social and ecological dimensions. Humans inhabit linked systems, where our actions such as resource extraction, pollution and development influence species in both direct and indirect ways and feedback to influence the human communities dependent on living marine resources. In order to understand the consequences of our actions and develop strategies to plan for future environmental change, we need a diverse set of tools able to incorporate various levels of complexity. This necessitates the improvement and modification of existing tools, development of novel approaches and unique applications of methods from across fields. In this dissertation I address the ways in which we can use and improve existing tools in ecology to advance our understanding and management of marine resources. In the first Chapter I introduce a method to incorporate life stage specific responses to a stressor, ocean acidification, to gain a broader understanding of population level vulnerability. In the second Chapter I extend this work to address ecosystem level change from ocean acidification in the California Current, using an ecosystem model to determine changes in biomass and fisheries catch. In the third chapter, I work to improve our understanding of how multiple stressors acting across life history can be magnified or mitigated, based solely on biological characteristics of populations. Finally, in the fourth Chapter I introduce ecologists and natural scientists to a broader understanding of research on risk in order to improve our methods for approaching ecosystem based fisheries management. My work spans ecological scales from populations to ecosystems and links between social and ecological systems.

Continue reading ‘Understanding the impacts of anthropogenic stressors on species, ecosystems, and fishing communities’

Potential for very deep ocean storage of CO2 without ocean acidification: a discussion paper

Carbon Capture and Storage (CCS) is an essential contributor to the mitigation of climate change. CCS will require vast CO2 storage capacity. At present only geological storage is being considered. This paper revisits an alternative CO2 storage possibility in enclosed basins on the deep and very deep ocean floor.

For example, the Indonesian Sunda trench, the Japanese Ryukyu trench and the Puerto Rico trench are more than 6 km deep. If liquid CO2 were to be placed in such a trench, it would be 7% more dense than seawater and could remain permanently as a lake of liquid CO2 on the ocean floor, possibly becoming a solid hydrate over time which could inhibit mixing between the stored CO2 and ocean currents.

At depths greater than about 4 to 5 km metres, seawater is under-saturated in calcium carbonate, so ocean ecosystems are significantly different. Any impact on deep marine fauna would need to be investigated.

The London Dumping Convention has provisions for disposal of material into the ocean provided the absence of adverse effects can be proven.

Deep ocean CO2 entrapment is more certain than geological CO2 storage in deep aquifers. A CO2 delivery concept by ship and vertical pipe is suggested for exploratory trials, with subsea pipelines for permanent installations, which might be much cheaper than geological CO2 storage.

There is vast capacity for storage of CO2 in the world’s very deep ocean trenches. The Sunda trench below 6 km has the capacity to accommodate 19,000 gigatonnes of liquid CO2, which is greater than the CO2 yield from all currently known global fossil fuel reserves. The Puerto Rico trench has capacity for 24,000 Gt of liquid CO2 deeper than 7 km. Enclosed basins of limited area could easily accommodate captured CO2.

China has the largest potential demand for CO2 storage from power generation and industrial sources, which could be 3 Gt per year by 2050. The Ryukyu trench, which is 700 km from the Chinese coast and is in Japanese water, has two sections deeper than 7 km. Those sections of the Ryukyu trench would have the capacity to accommodate all the CO2 captured in China at 3 Gt per year for over 200 years.

In the event that very deep ocean storage of CO2 is found to be practicable and acceptable, the minimum practical depth would need to be determined as a criterions for acceptable additional storage locations. For consideration, there is an enclosed basin on the floor of the Mediterranean Sea 60 km off Southern Greece, with capacity for 84 Gt of CO2 deeper than 4.5 km. Also, there is an enclosed basin in the Arabian Sea, 320 km south west of Karachi, with capacity for 86 Gt of CO2 deeper than 3.5 km. The potential storage of CO2 in such locations would be temperature dependent.

The global CCS community has previously considered ocean storage of CO2 on the basis of ultimate dissolution and dispersion of CO2 in ocean water. Those studies have dismissed ocean storage as environmentally unacceptable due to ocean acidification.

This paper postulates that very deep ocean trenches (>6 km) and deep ocean floor depressions (>4 km) are environments for CO2 storage, where permanent storage without dissolution, acidification or adverse effects on fauna may be possible.

The purpose of this paper is to pose the question “Why not?” to the CCS community and to suggest that active research is timely.

Continue reading ‘Potential for very deep ocean storage of CO2 without ocean acidification: a discussion paper’


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Ocean acidification in the IPCC AR5 WG II

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