Archive for December, 2015

The effect of pH on natural settlement and metamorphosis in the invasive limpet, Crepidula fornicata

The average pH of ocean surface waters has dropped by about 30%, due to absorption of anthropogenic CO2 emissions. In the past decade, much research has been conducted examining the effect of this “ocean acidification” on marine organisms. Larvae seem especially sensitive. Acidification has been shown to affect chemosensory mechanisms and behavior of clownfish larvae, but little is known about how acidification may affect the sensory biology of marine invertebrate larvae. Like many marine invertebrates, the gastropod Crepidula fornicata settles and metamorphoses in response to chemical cues associated with favorable habitat for juveniles. Other studies on marine invertebrates have found decreased settlement and metamorphosis at lower pH, but none have measured how pH affects settlement and metamorphosis in response to cues from adult conspecifics. We tested the effect of pH on settlement and metamorphosis of four broods of larvae of C. fornicata that were derived from different parents. pH had a significant overall effect on both settlement and metamorphosis in the presence of adults, but not in the direction expected. Larvae settled and metamorphosed at higher frequency at pH 7.5 and 7.7 than at pH 8.0. While this pattern was seen in three of the four broods tested, response to pH treatment varied between broods. Further research is needed to determine if differences between broods remain consistent throughout the larval period, and might therefore reflect adaptations to variable pH regimes in estuarine environments.

Continue reading ‘The effect of pH on natural settlement and metamorphosis in the invasive limpet, Crepidula fornicata’

NOAA scientists quantify coral reef growth to monitor the effects of ocean acidification

Often referred to as the “rainforests of the sea,” coral reefs are some of the most biologically rich and economically valuable ecosystems on Earth. Most coral reefs occur in warm, shallow, clear waters and are built by stony corals together with other organisms that form hard, calcium carbonate skeletons over decades and centuries.

Scientists at the Coral Reef Ecosystem Program of NOAA’s Pacific Islands Fisheries Science Center are conducting long-term research to monitor the rates at which reef organisms build their calcium carbonate skeletons and how changes in ocean chemistry, particularly ocean acidification, might impact their growth.

Ocean acidification is a global phenomenon in which increasing carbon dioxide in the atmosphere is absorbed into the ocean making the seawater more acidic. The lower pH and higher acidity of the ocean makes it harder for marine creatures, such as shellfish and corals, to build their calcium carbonate shells or skeletons.

Continue reading ‘NOAA scientists quantify coral reef growth to monitor the effects of ocean acidification’

Baseline assessment of net calcium carbonate accretion rates on U.S. Pacific reefs

This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm-2 yr-1) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years) of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA) percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons makes CCA extremely susceptible changes in ocean water pH, emphasizing the far-reaching threat that ocean acidification poses to the ecological function and persistence of coral reefs worldwide.

Continue reading ‘Baseline assessment of net calcium carbonate accretion rates on U.S. Pacific reefs’

Limited effects of increased CO2 and temperature on metal and radionuclide bioaccumulation in a sessile invertebrate, the oyster Crassostrea gigas

This study investigated the combined effects of reduced pH and increased temperature on the capacities of the Pacific cupped oyster Crassostrea gigas to bioconcentrate radionuclide and metals. Oysters were exposed to dissolved radiotracers (110mAg, 241Am, 109Cd,57Co,54Mn, and 65Zn) at three pH (7.5, 7.8, 8.1) and two temperatures (21 and 24°C) under controlled laboratory conditions. Although calcifying organisms are recognized as particularly vulnerable to ocean acidification, the oyster did not accumulate differently the studied metals when exposed under the different pH conditions. However, temperature alone or in combination with pH somewhat altered the bioaccumulation of the studied elements. At pH 7.5, Cd was accumulated with an uptake rate constant twofold higher at 24°C than 21°C. Bioaccumulation of Mn was significantly affected by an interactive effect between seawater pH and temperature, with a decreased uptake rate at pH 7.5 when temperature increased (27 ± 1 vs. 17 ± 1 d−1 at 21 and 24°C, respectively). Retention of Co and Mn tended also to decrease at the same pH with decreasing temperature. Neither pH nor temperature affected strongly the elements distribution between shell and soft tissues. Significant effects of pH were found on the bioaccessibility of Mn, Zn, and 241Am during experimental in vitro simulation of human digestion.

Continue reading ‘Limited effects of increased CO2 and temperature on metal and radionuclide bioaccumulation in a sessile invertebrate, the oyster Crassostrea gigas’

Young marine scientists making a difference at the Paris Climate Conference

Ocean more present than ever at the 21st conference of the parties

Marine Scientists from France, the United Kingdom, the United States and Germany presented ocean research at the United Nations Framework Convention on Climate Change (UNFCCC) 21st Conference of the Parties (COP 21) in Paris. Especially young scientists benefitted greatly from participating in the climate summit.

In a joint effort, scientists from Plymouth Marine Laboratory (UK), the Cluster of Excellence LabexMER (France), Scripps Institution of Oceanography (United States), the University Pierre and Marie Curie (France), the UK Ocean Acidification research programme (UKOA) and the German research network Biological Impacts of Ocean Acidification (BIOACID) engaged with public and policymakers at COP 21. At their booths in both the public “Zone Générations Climat” and the UN area where the negotations are held, young scientists discussed aspects of ocean change with negotiators, stakeholders and other visitors. PhD students and postdocs from all partner institutions were invited to introduce ocean and climate science and to participate in events – a unique experience for more than 20 young researchers. It has been estimated that there were 40.000 people attending COP 21.

Continue reading ‘Young marine scientists making a difference at the Paris Climate Conference’

Video presentation of the OA-ICC online resources

As a reminder of its online resources and ways to access and utilize their features, the OA-ICC has put together a short video presentation you can watch below.

Fertilisation and larval development in an Antarctic bivalve, Laternula elliptica, under reduced pH and elevated temperatures

Elevated temperatures associated with ocean warming and acidification can influence development and, ultimately, success of larval molluscs. The effect of projected oceanic changes on fertilisation and larval development in an Antarctic bivalve, Laternula elliptica, was investigated through successive larval stages at ambient temperature and pH conditions (-1.6°C and pH 7.98) and conditions representative of projections through to 2100 (-0.5°C to +0.4°C and pH 7.80 to pH 7.65). Where significant effects were detected, increased temperature had a consistently positive influence on larval development, regardless of pH level, while effects of reduced pH varied with larval stage and incubation temperature. Fertilisation was high and largely independent of stressors, with no loss of gamete viability. Mortality was unaffected at all development stages under experimental conditions. Elevated temperatures reduced occurrences of abnormalities in D-larvae and accelerated larval development through late veliger and D-larval stages, with D-larvae occurring 5 d sooner at 0.4°C compared to ambient temperature. Reduced pH did not affect occurrences of abnormalities in larvae, but it slowed the development of calcifying stages. More work is required to investigate the effects of developmental delays of the magnitude seen here in order to better determine the ecological relevance of these changes on longer term larval and juvenile success.

Continue reading ‘Fertilisation and larval development in an Antarctic bivalve, Laternula elliptica, under reduced pH and elevated temperatures’

Resilience of SAR11 bacteria to rapid acidification in the high latitude open ocean

Ubiquitous SAR11 Alphaproteobacteria numerically dominate marine planktonic communities. Because they are excruciatingly difficult to cultivate, there is comparatively little known about their physiology and metabolic responses to long- and short- term environmental changes. As surface oceans take up anthropogenic, atmospheric CO2, the consequential process of ocean acidification could affect the global biogeochemical significance of SAR11. Shipping accidents or inadvertent release of chemicals from industrial plants can have strong short-term local effects on oceanic SAR11. This study investigated the effect of 2.5 fold acidification of seawater on the metabolism of SAR11 and other heterotrophic bacterioplankton along a natural temperature gradient crossing the North Atlantic Ocean, Norwegian and Greenland Seas. Uptake rates of the amino acid leucine by SAR11 cells as well as other bacterioplankton remained similar to controls despite an instant ∼50% increase in leucine bioavailability upon acidification. This high physiological resilience to acidification even without acclimation, suggests that open ocean dominant bacterioplankton are able to cope even with sudden and therefore more likely with long-term acidification effects.

Continue reading ‘Resilience of SAR11 bacteria to rapid acidification in the high latitude open ocean’

Carbon-13 labelling shows no effect of ocean acidification on carbon transfer in Mediterranean plankton communities

Despite an increasing number of experiments, no consensus has emerged on the effect of ocean acidification on plankton communities and carbon flow. During two experiments, performed in the Bay of Calvi (France, Corsica; summer 2012) and the Bay of Villefranche (France; winter 2013), nine off-shore mesocosms (∼50 m3) were deployed among which three served as controls and six were enriched with CO2 to reach partial pressure of CO2 (pCO2) levels from 450 to 1350 μatm and 350 to 1250 μatm in the Bay of Calvi and the Bay of Villefranche, respectively. In each mesocosm, inorganic 13C was added in order to follow carbon transfer from inorganic via bulk particulate organic carbon and phytoplankton to bacteria by means of biomarkers as well as to zooplankton and settling particles. Despite very low plankton biomasses, labelled carbon was clearly transferred through plankton communities. Incorporation rates in the various plankton compartments suggested a slow-growing community based on regenerated production in the Bay of Calvi while in the Bay of Villefranche, fast-growing species were clearly dominating community production at the start with a shift toward slow-growing species during the experiment due to nutrient limitation. Both bulk and group-specific productions rates did not respond to increasing pCO2 levels. These experiments were the first conducted in the Mediterranean Sea under low nutrient concentrations and phytoplankton biomasses and suggest that ocean acidification may not significantly impact plankton carbon flows in low nutrient low chlorophyll (LNLC) areas.

Continue reading ‘Carbon-13 labelling shows no effect of ocean acidification on carbon transfer in Mediterranean plankton communities’

ESSAS Annual Science Meeting, Yokohama, Japan, 7-9 March 2016

There are several sessions relevant to ocean acidification at the ESSAS Annual Science Meeting, Yokohama, Japan.

Dates: 7-9 March 2016

Yokohama World porters, Hall B, at Sakuragi-cho, Yokohama

Theme of meeting: “Scientific Challenges in a Changing Arctic & Subarctic”

The decline of biodiversity (the biomass, composition, and distribution of species) on Earth reflects the fact that the ability of Earth to sustain biodiversity in a dynamic environment has been seriously compromised by environmental stressors such as climate change and ocean acidification. Furthermore, the reduction of sea ice in the Arctic Ocean, which has progressed more rapidly than previously predicted, could exacerbate several environmental stresses, including ocean warming, acidification, and stratification. This meeting will focus on the observed and projected changes in the climate and marine environment of the Arctic and Subarctic and in the biological responses to these changes: How did the ancient climate and environment of the Arctic and its marginal subarctic regions change over time? How are the climate and environment of the subarctic and Arctic regions changing during the current Anthropocene? How do marine organisms in subarctic and polar regions respond to multiple environmental stressors? Active discussions will be encouraged to enhance our understanding of observed and anticipated changes and to explore how the natural sciences, humanities and socio-economic sciences can address and adapt to these challenges.

Continue reading ‘ESSAS Annual Science Meeting, Yokohama, Japan, 7-9 March 2016’

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Ocean acidification in the IPCC AR5 WG II

OUP book