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Maine to collect ocean acidification data with new sensors

BOOTHBAY HARBOR (AP) — Maine marine officials said three new sensors installed in a coastal community will help scientists get a better understanding of ocean acidifcation.

The growing acid levels in the ocean are a hazard for some kinds of sea life, including some of those sought by Maine fishermen. Scientists have linked acidification to factors that also drive climate change.

The Maine Department of Marine Resources said it has installed the three sensors in Boothbay Harbor. The department said the sensors will help researchers get a better understanding of how ocean acidification and dissolved oxygen levels can change the health of the state’s marine life and ecosystems.

Marine department scientist Jesica Waller said data from the sensors will also be incorporated into undergraduate programs at the University of Maine and Bigelow Laboratory for Ocean Sciences.

Continue reading ‘Maine to collect ocean acidification data with new sensors’

Coastal Rivers to host online talk on coastal acidification in Midcoast May 27

Coastal Rivers volunteers collect water quality data in the Damariscotta River estuary.

Levels of acidification can be different in coastal marine waters than in the open ocean. Inputs from freshwater rivers and nutrient runoff from land can change water chemistry in coastal areas.

Sarah Gladu and Kathleen Thornton will offer an online presentation from 4 to 6 p.m. Wednesday, May 27, about the coastal acidification and what data gathered by the Maine Coastal Observing Alliance are documenting in Midcoast Maine. They will also cover what is being done locally to better understand this problem and related water quality issues.

The presentation is free. Registration is required online at coastalrivers.org.

MCOA is a coalition of nonprofits focusing on gathering water quality data along the coast from Harraseeket to Belfast Harbor. Kathleen Thornton is a research specialist at the University of Maine’s Darling Marine Center. Sarah Gladu chairs MCOA and is director of education and citizen science at Coastal Rivers.

Coastal Rivers Conservation Trust is a nonprofit, nationally accredited land trust with active programs in land conservation, water quality, trails and public access, and nature education in the Damariscotta-Pemaquid region. For more information, email info@coastalrivers.org or visit coastalrivers.org.

Continue reading ‘Coastal Rivers to host online talk on coastal acidification in Midcoast May 27’

Porewater carbonate chemistry dynamics in a temperate and a subtropical seagrass system

Seagrass systems are integral components of both local and global carbon cycles and can substantially modify seawater biogeochemistry, which has ecological ramifications. However, the influence of seagrass on porewater biogeochemistry has not been fully described, and the exact role of this marine macrophyte and associated microbial communities in the modification of porewater chemistry remains equivocal. In the present study, carbonate chemistry in the water column and porewater was investigated over diel timescales in contrasting, tidally influenced seagrass systems in Southern California and Bermuda, including vegetated (Zostera marina) and unvegetated biomes (0–16 cm) in Mission Bay, San Diego, USA and a vegetated system (Thallasia testudinium) in Mangrove Bay, Ferry Reach, Bermuda. In Mission Bay, dissolved inorganic carbon (DIC) and total alkalinity (TA) exhibited strong increasing gradients with sediment depth. Vertical porewater profiles differed between the sites, with almost twice as high concentrations of DIC and TA observed in the vegetated compared to the unvegetated sediments. In Mangrove Bay, both the range and vertical profiles of porewater carbonate parameters such as DIC and TA were much lower and, in contrast to Mission Bay where no distinct temporal signal was observed, biogeochemical parameters followed the semi-diurnal tidal signal in the water column. The observed differences between the study sites most likely reflect a differential influence of biological (biomass, detritus and infauna) and physical processes (e.g., sediment permeability, residence time and mixing) on porewater carbonate chemistry in the different settings.

Continue reading ‘Porewater carbonate chemistry dynamics in a temperate and a subtropical seagrass system’

Irreversibility of marine climate change impacts under carbon dioxide removal

Artificial carbon dioxide removal (CDR) from the atmosphere has been proposed as a measure for mitigating climate change and restoring the climate system to a target state after exceedance (“overshoot”). This research investigates to what extent overshoot and subsequent recovery of a given cumulative CO2 emissions level by CDR leaves a legacy in the marine environment using an Earth system model. We use RCP2.6 and its extension to year 2300 as the reference scenario and design a set of cumulative emissions and temperature overshoot scenarios based on other RCPs. Our results suggest that the overshoot and subsequent return to a reference cumulative emissions level would leave substantial impacts on the marine environment. Although the changes in sea surface temperature, pH and dissolved oxygen are largely reversible, global mean values and spatial patterns of these variables differ significantly from those in the reference scenario when the reference cumulative emissions are attained.

Continue reading ‘Irreversibility of marine climate change impacts under carbon dioxide removal’

Pacific-wide pH snapshots reveal that high coral cover correlates with low, but variable pH

Ocean acidification (OA) is impairing the construction of coral reefs while simultaneously accelerating their breakdown. The metabolism of different reef organism assemblages alters seawater pH in different ways, possibly buffering or exacerbating OA impacts. In spite of this, field data relating benthic community structure and seawater pH are sparse. We collected pH time-series data snapshots at 10 m depth from 28 different reefs (n = 13 lagoon, n = 15 fore reef) across 22 Pacific islands, spanning 31° latitude and 90° longitude. Coincident with all deployments, we measured percent cover of the benthic community. On fore reefs, high coral cover (CC) negatively correlated with mean and minimum pH, but positively correlated with pH variability. Conversely, pH minima were positively correlated to coverage of coralline and turf algae. Benthic cover did not correlate with pH in lagoonal reefs. From 0%–100% CC, mean pH and aragonite saturation state (Ωarag ) declined −0.081 and −0.51, respectively, while declines in minimum values were greater (Δmin pH = −0.164, Δmin Ωarag = −0.96). Based upon previously published relationships, the mean pH decline from 0%–100% CC would depress coral calcification 7.7%–18.0% and increase biologically-mediated dissolution 13.5%–27.9%, with pH minima depressing dark coral calcification 14.4%–35.2% and increasing biologically-mediated dissolution 31.0%–62.2%. This spatially expansive dataset provides evidence that coral reefs with the highest coral cover may experience the lowest and most extreme pH values with OA.

Continue reading ‘Pacific-wide pH snapshots reveal that high coral cover correlates with low, but variable pH’

Warming and acidification threaten glass sponge Aphrocallistes vastus pumping and reef formation

The glass sponge Aphrocallistes vastus contributes to the formation of large reefs unique to the Northeast Pacific Ocean. These habitats have tremendous filtration capacity that facilitates flow of carbon between trophic levels. Their sensitivity and resilience to climate change, and thus persistence in the Anthropocene, is unknown. Here we show that ocean acidification and warming, alone and in combination have significant adverse effects on pumping capacity, contribute to irreversible tissue withdrawal, and weaken skeletal strength and stiffness of A. vastus. Within one month sponges exposed to warming (including combined treatment) ceased pumping (50–60%) and exhibited tissue withdrawal (10–25%). Thermal and acidification stress significantly reduced skeletal stiffness, and warming weakened it, potentially curtailing reef formation. Environmental data suggests conditions causing irreversible damage are possible in the field at +0.5 °C above current conditions, indicating that ongoing climate change is a serious and immediate threat to A. vastus, reef dependent communities, and potentially other glass sponges.

Continue reading ‘Warming and acidification threaten glass sponge Aphrocallistes vastus pumping and reef formation’

External pH modulation during the growth of Vibrio tapetis , the etiological agent of Brown Ring Disease

Aims
Brown Ring Disease (BRD) is an infection of the Manila clam Ruditapes philippinarum due to the pathogen Vibrio tapetis . During BRD, clams are facing immunodepression and shell biomineralization alteration. In this paper, we studied the role of pH on the growth of the pathogen and formulated hypothesis on the establishment of BRD by V. tapetis .

Methods and Results
In this study, we monitored the evolution of pH during the growth of V. tapetis in a range of pH and temperatures. We also measured the pH of Manila clam hemolymph and extrapallial fluids during infection by V. tapetis . We highlighted that V. tapetis modulates the external pH during its growth, to a value of 7.70. During the development of BRD, V. tapetis also influences extrapallial fluids and hemolymph pH in vitro in the first hours of exposure and in vivo after 3 days of infection.

Conclusions
Our experiments have shown a close interaction between V. tapetis CECT4600, a pathogen of Manila clam that induces BRD, and the pH of different compartments of the animals during infection. These results indicate that that the bacterium, through a direct mechanism or as a consequence of physiological changes encountered in the animal during infection, is able to interfere with the pH of Manila clam fluids. This pH modification might promote the infection process or at least create an imbalance within the animal, that would favor its persistence. This last hypothesis should be tested in future experiment.

Significance and Impact of Study
This study is the first observation of pH modifications in the context of BRD and might orient future research on the fine mechanisms of pH modulation associated to BRD.

Continue reading ‘External pH modulation during the growth of Vibrio tapetis , the etiological agent of Brown Ring Disease’


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Ocean acidification in the IPCC AR5 WG II

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