Archive for August, 2014

Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions

We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO2, low aragonite saturation state (Ωa) conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (~460–500 µatm CO2, Ωa≈1.59), current deep water or surface conditions during upwelling (~760 and ~1600–1700 µatm CO2, Ωa≈1.17 and 0.56), and future deep water or surface conditions during upwelling (~2800–3400 µatm CO2, Ωa≈0.28). We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ωa, and conducted analyses considering Ωa both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound’s main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.

Continue reading ‘Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions’

Workshop to tackle big threat of ocean acidification (audio)

Ahead of next week’s Small Island Developing States conference, experts have been meeting to discuss the problem of ocean acidification.

It’s considered to be one of the biggest threats to small island developing nations – with the potential to impact on local fisheries and in turn, the livelihoods of many people in the Pacific.

Presenter: Bruce Hill

Speaker: Dr Melchio Mataki, Solomon Islands Permanent Secretary for Climate Change

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Proteomic and metabolomic responses of Pacific oyster Crassostrea gigas to elevated pCO2 exposure

The gradually increased atmospheric CO2 partial pressure (pCO2) has thrown the carbonate chemistry off balance and resulted in decreased seawater pH in marine ecosystem, termed ocean acidification (OA). Anthropogenic OA is postulated to affect the physiology of many marine calcifying organisms. However, the susceptibility and metabolic pathways of change in most calcifying animals is still far from been well understood. In this work, the effects of exposure to elevated pCO2 were characterized in gills and hepatopancreas of Crassostrea gigas using integrated proteomic and metabolomic approaches. Metabolic responses indicated that high CO2 exposure mainly caused disturbances in energy metabolism and osmotic regulation marked by differentially altered ATP, glucose, glycogen, amino acids and organic osmolytes in oysters, and the depletions of ATP in gills and the accumulations of ATP, glucose and glycogen in hepatopancreas accounted for the difference in energy distribution between these two tissues. Proteomic responses suggested that OA could affect energy and primary metabolisms, stress responses and calcium homeostasis in both tissues, but also influence the nucleotide metabolism in gills and cytoskeleton structure in hepatopancreas. This study demonstrated that the combination of proteomics and metabolomics could provide an insightful view into the effects of OA on oyster C. gigas.

Continue reading ‘Proteomic and metabolomic responses of Pacific oyster Crassostrea gigas to elevated pCO2 exposure’

Protect our oceans, urges Samoa minister


Scientists at the Ocean Acidification workshop aboard the P&O cruiseliner Pacific Jewel in Apia, Samoa– Samisoni Pareti

Small Island states need to do more to rehabilitate, protect and preserve their threatened marine environment. That advice came from Samoa’s Environment Minister Faamoetauloa-Lealaiauloto Taito Dr Faale Tumaalii when he opened a two-day workshop on ocean acidification in Apia today. It’s being held aboard the luxurious cruise-liner, the Pacific Jewel docked at the Apia Port to assist accommodate delegates who will be attending the United Nations Conference on Small Islands Developing States (SIDS).

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20 corals protected under Endangered Species Act because of global warming, ocean acidification

SAN FRANCISCO— The federal government announced today that 20 species of coral are now protected as “threatened” under the Endangered Species Act because global warming, disease and ocean acidification are driving them toward extinction. Today’s decision by the National Marine Fisheries Service responds to a 2009 scientific petition by the Center for Biological Diversity seeking the Act’s protection for 83 corals in U.S. waters. Of the corals receiving protection, five occur in Florida and the Caribbean, and 15 live in the Pacific.

Today’s decision is the single-largest protection decision for corals under the Endangered Species Act.

“This decision is a big step forward for corals,” said Miyoko Sakashita, the Center’s oceans director. “The world’s coral reefs are in crisis from global warming and acidifying oceans, and it’s great news that 20 coral species will get the safety net of Endangered Species Act to help them survive these threats.”

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Ocean acidification impacts mussel control on biomineralisation

Ocean acidification is altering the oceanic carbonate saturation state and threatening the survival of marine calcifying organisms. Production of their calcium carbonate exoskeletons is dependent not only on the environmental seawater carbonate chemistry but also the ability to produce biominerals through proteins. We present shell growth and structural responses by the economically important marine calcifier Mytilus edulis to ocean acidification scenarios (380, 550, 750, 1000 µatm pCO2). After six months of incubation at 750 µatm pCO2, reduced carbonic anhydrase protein activity and shell growth occurs in M. edulis. Beyond that, at 1000 µatm pCO2, biomineralisation continued but with compensated metabolism of proteins and increased calcite growth. Mussel growth occurs at a cost to the structural integrity of the shell due to structural disorientation of calcite crystals. This loss of structural integrity could impact mussel shell strength and reduce protection from predators and changing environments.

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Size matters: plasticity in metabolic scaling shows body-size may modulate responses to climate change

Variability in metabolic scaling in animals, the relationship between metabolic rate (R) and body mass (M), has been a source of debate and controversy for decades. R is proportional to Mb, the precise value of b much debated, but historically considered equal in all organisms. Recent metabolic theory, however, predicts b to vary among species with ecology and metabolic level, and may also vary within species under different abiotic conditions. Under climate change, most species will experience increased temperatures, and marine organisms will experience the additional stressor of decreased seawater pH (‘ocean acidification’). Responses to these environmental changes are modulated by myriad species-specific factors. Body-size is a fundamental biological parameter, but its modulating role is relatively unexplored. Here, we show that changes to metabolic scaling reveal asymmetric responses to stressors across body-size ranges; b is systematically decreased under increasing temperature in three grazing molluscs, indicating smaller individuals were more responsive to warming. Larger individuals were, however, more responsive to reduced seawater pH in low temperatures. These alterations to the allometry of metabolism highlight abiotic control of metabolic scaling, and indicate that responses to climate warming and ocean acidification may be modulated by body-size.

Continue reading ‘Size matters: plasticity in metabolic scaling shows body-size may modulate responses to climate change’

US/NZ host international workshop on ocean acidification

An International Workshop on Ocean Acidification: State-of-the-Science Considerations for Small Island Developing State, August 28-29, 2014, Apia, Samoa

Jointly hosted by New Zealand and the United States in partnership with the Secretariat of the Pacific Regional Environment Programm. Parallel Event of the UN Third International Conference on Small Island Developing States

Leading international ocean scientists and policy experts are tomorrow gathering in Apia, Samoa to better understand the threat ocean acidification poses to Pacific Island nations.

The workshop, co-hosted by the United States and New Zealand Governments in partnership with the Secretariat of the Pacific Regional Environment Programme, will be held on the margins of the Small Island Developing States Conference, on the 28-29 August.

The workshop participants, who hail from the nations attending the Small Island Developing States conference, will discuss best practices, solutions and ocean acidification monitoring programmes for island nations to implement.

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Limpets counteract ocean acidification induced shell corrosion by thickening of aragonitic shell layers

Specimens of the patellogastropod limpet Patella caerulea were collected within (pHlow-shells) and outside (pHn-shells) a CO2 vent site at Ischia, Italy. Four pHlow-shells and four pHn-shells were sectioned transversally and scanned for polymorph distribution by means of confocal Raman microscopy. The pHlow-shells displayed a twofold increase in aragonite area fraction and size normalised aragonite area. Size normalised calcite area was halved in pHlow-shells. Taken together with the increased apical and the decreased flank size normalised thickness of the pHlow-shells, these data led us to conclude that low pH exposed P. caerulea specimens counteract shell dissolution by enhanced shell production. The latter is different from normal elongation growth and proceeds through addition of aragonitic layers only, while the production of calcitic layers is confined to elongation growth. Therefore aragonite cannot be regarded as a per se disadvantageous polymorph under ocean acidification conditions.

Continue reading ‘Limpets counteract ocean acidification induced shell corrosion by thickening of aragonitic shell layers’

Interactive effects of ocean acidification and warming on subtidal mussels and sea stars from Atlantic Canada

Anthropogenic CO2 is decreasing oceanic pH and contributing to seawater warming. We tested the effects of low pH and high temperature at levels predicted for 2100 on an ecologically important predator–prey system (sea stars, Asterias rubens, and mussels, Mytilus edulis) from the NW Atlantic coast. Mussels are dominant competitors for space and important ecosystem engineers, while sea stars control mussel populations and thus local community structure. We found sea stars to be negatively affected in growth rate by low pH, with growth further reduced by a high temperature. In contrast, mussel growth rate was positively affected by low pH, with no response to temperature within the tested range. Predation of sea stars on mussels, measured as per-capita consumption rate, decreased in acidified conditions by 50 %. Our study suggests that mussels may not be negatively affected by pH at the levels predicted for the end of this century and that mussels may be subjected to a reduced predation from sea stars under future conditions.

Continue reading ‘Interactive effects of ocean acidification and warming on subtidal mussels and sea stars from Atlantic Canada’

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Ocean acidification in the IPCC AR5 WG II

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