Archive for October, 2015

Vacancy: Marine Research Specialist II, University of Rhode Island, USA

Deadline for submission of applications: 9 November 2015!

This is a fulltime, calendar year position, limited to 04/30/2016 with extension contingent on funding.

Basic function

Perform experimental and developmental work in support of major research programs on ocean acidification and marine microbial ecology. Develop new or modify existing research methods and procedures, most prominently in –omics analyses and development of ecological and metabolic models.

Essential duties and responsibilities

  • Use established analytical, experimental and investigative methods and techniques, with minor modifications and adaptations.
  • Collect, process, monitor and analyze samples and/or data obtained on Narragansett Bay, Southern Ocean and additional ocean expeditions and cruises in the future.
  • Maintain laboratory, equipment and analytical protocols for conformance with research priorities.
  • Responsible for problem definition and solution within above mentioned research projects.
  • Assist with the preparation for publication of manuscripts containing the results of research efforts.

Continue reading ‘Vacancy: Marine Research Specialist II, University of Rhode Island, USA’

Session addressing ocean acidification at the 7th World Fisheries Congress, 23-27 May 2016, Busan, Korea

Session title: “Future of Marine Fisheries under Climate Change: Exploring Uncertainties, Future Scenarios and Multi-Scale Transformative Pathways”

Deadline for abstract submission: 15 November 2015!

Session abstract

Climate change and acidification impact ocean systems and fisheries in multifaceted ways, through changes in ocean productivity, redistribution of species and fisheries resources and increased variability of some fish stocks. These impacts have large implications for fishing sectors, coastal communities and society, particularly for those that are already vulnerable due to, for instance, resource depletion, existence of perverse subsidies and institutional barriers that inhibit consideration of transboundary issues. To help build climate-resilience for marine fisheries, we need to understand adaptive capacity of both biophysical and human systems, and explore the need and potential for transformations at multiple levels to ensure sustainable oceans and fisheries. Because of the complexity of the marine social-ecological system and the interdisciplinary nature of the issues involved, we need to assess these measures at multiple scales (local, regional and global) and domains (biophysical, economic, social and legal) to avoid mal-adaptation and incompatibility in achieving sustainable fisheries goals.

Continue reading ‘Session addressing ocean acidification at the 7th World Fisheries Congress, 23-27 May 2016, Busan, Korea’

Maine isn’t doing enough to protect the Gulf from the effects of climate change

Photo credit: Gregory Rec

Photo credit: Gregory Rec

When the Maine Legislature’s commission on ocean acidification reported its findings – that the state’s fisheries and aquaculture industries were threatened by this baleful byproduct of global warming – officials here were not exactly spurred to action.

Acidification, driven by increased carbon dioxide from the atmosphere and freshwater runoff from extreme rainfall in river basins, has been implicated in failures at oyster hatcheries and mussel farms, and has been shown to weaken clams and other shell-building animals vital to Maine’s fishing and aquaculture industries. But bills introduced in the last session – one each by a Democratic marine scientist and a Republican lobsterman – to implement many of the panel’s findings were withdrawn, one for lack of resources, the other for lack of support from Gov. Paul LePage’s administration.

“I could see the bill wasn’t going to go anywhere and that the governor was going to veto it,” Rep. Mick Devin, a Democrat from Newcastle, says of legislation he sponsored to allow the commission to continue its work for another three years.

Patricia Aho, who was the commissioner of environmental protection until she resigned in August, opposed Devin’s bill, saying the status quo was sufficient. “Since the issues of climate change and ocean acidification are inextricably linked, we think it will be more efficient to consider this issue in the broader context of climate change and adaptation programs,” she said in written testimony to legislators.

Continue reading ‘Maine isn’t doing enough to protect the Gulf from the effects of climate change’

Ocean acidification increases the accumulation of toxic phenolic compounds across trophic levels

Increasing atmospheric CO2 concentrations are causing ocean acidification (OA), altering carbonate chemistry with consequences for marine organisms. Here we show that OA increases by 46–212% the production of phenolic compounds in phytoplankton grown under the elevated CO2 concentrations projected for the end of this century, compared with the ambient CO2 level. At the same time, mitochondrial respiration rate is enhanced under elevated CO2 concentrations by 130–160% in a single species or mixed phytoplankton assemblage. When fed with phytoplankton cells grown under OA, zooplankton assemblages have significantly higher phenolic compound content, by about 28–48%. The functional consequences of the increased accumulation of toxic phenolic compounds in primary and secondary producers have the potential to have profound consequences for marine ecosystem and seafood quality, with the possibility that fishery industries could be influenced as a result of progressive ocean changes.

Continue reading ‘Ocean acidification increases the accumulation of toxic phenolic compounds across trophic levels’

Shellfish can’t keep up with shifting ocean chemistry

Photo credit: Gregory Rec

Photo credit: Gregory Rec

In seawater tanks in a refrigerated room at the Darling Marine Center, the baby mussels are thriving.

Two months ago they were near-invisible larvae, swimming around in the tanks. Now tens of thousands of the tiny mollusks, each just a few millimeters long, have attached themselves to the different kinds of rope scientists have been testing here, and are eating the lab’s stock of algal food at an impressive clip.

Mick Devin, the lab manager at this University of Maine marine research facility, has been overseeing this experiment, part of an effort to master the art of hatching mussels, something mussel farmers – who grow their product on lines hanging in seawater – have never previously needed to do.

“Mussel farmers have been able to just throw their lines out and collect all the larvae they want from nature,” Devin says. “But mussel populations are down drastically in this state, so that may not be working so well now.” Hatcheries, he expects, may have to step up in the not-too-distant future.

Continue reading ‘Shellfish can’t keep up with shifting ocean chemistry’

No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community

Nitrogen fixation by filamentous cyanobacteria supplies significant amounts of new nitrogen (N) to the Baltic Sea. This balances N loss processes such as denitrification and anammox and forms an important N source supporting primary and secondary production in N-limited post-spring bloom plankton communities. Laboratory studies suggest that filamentous diazotrophic cyanobacteria growth and N2-fixation rates are sensitive to ocean acidification with potential implications for new N supply to the Baltic Sea. In this study, our aim was to assess the effect of ocean acidification on diazotroph growth and activity as well as the contribution of diazotrophically-fixed N to N supply in a natural plankton assemblage. We enclosed a natural plankton community in a summer season in the Baltic Sea near the entrance to the Gulf of Finland in six large-scale mesocosms (volume ~ 55 m3) and manipulated fCO2 over a range relevant for projected ocean acidification by the end of this century (average treatment fCO2: 365–1231 μatm). The direct response of diazotroph growth and activity was followed in the mesocosms over a 47 day study period during N-limited growth in the summer plankton community. Diazotrophic filamentous cyanobacteria abundance throughout the study period and N2-fixation rates (determined only until day 21 due to subsequent use of contaminated commercial 15N-N2 gas stocks) remained low. Thus estimated new N inputs from diazotrophy were too low to relieve N limitation and stimulate a summer phytoplankton bloom. Instead regeneration of organic N sources likely sustained growth in the plankton community. We could not detect significant CO2-related differences in inorganic or organic N pools sizes, or particulate matter N : P stoichiometry. Additionally, no significant effect of elevated CO2 on diazotroph activity was observed. Therefore, ocean acidification had no observable impact on N cycling or biogeochemistry in this N-limited, post-spring bloom plankton assemblage in the Baltic Sea.

Continue reading ‘No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community’

Ocean acidification and its impact on marine biodiversity, seafood security & livelihoods – a short review

Ocean acidification (OA) is an effect of climate change. OA can be defined as long-term decrease in seawater pH, principally due to anthropogenic increase in atmospheric carbon dioxide (CO2). The absorption of CO2 has already acidified the surface layers of the ocean causing an overall decrease of 0.1 pH units (30% increase in acidity) since the pre-industrial period, and the surface ocean pH is projected to decrease by 0.3-0.4 pH units (150% increase in acidity) by 2100. A recent study reveals that increased OA may amplify further global warming due to reduced dimethylsulphide (DMS, a biogenic marine sulphur compound) in the oceans. Ocean acidification is one of the most critical anthropogenic threats to marine life, in particular to calcifying organisms. There are both negative and positive effects of OA. Negative effects include reduced calcification, reduced abundance, reduced growth, reduced development and reduced survival in calcifying organisms (krill, pteropods, molluscs, corals, echinoderms, early life stage of fish and phytoplankton) and positive effects include enhanced growth and enhance photosynthesis in seaweeds and seagrasses. Economic loss and impacts on food security due to OA could be substantial. Eighty two developing nations including many island nations depend heavily on calcifying species to support subsistence or artisanal fisheries that provide both income and protein. Many of these small-island nations have limited agricultural alternatives. Ocean acidification could not only impacts on the commercial fisheries and shellfish production but could also threaten protein supply and food security and livelihoods for millions of the world’s poorest people. To avoid substantial damage to ocean ecosystems and marine life, deep and rapid reductions of global CO2 emissions are needed from human activities.

Continue reading ‘Ocean acidification and its impact on marine biodiversity, seafood security & livelihoods – a short review’

Carbonate chemistry dynamics and biological processes along a river-sea gradient (Gulf of Trieste, northern Adriatic Sea)

In this paper we investigated, for two years and with a bi-monthly frequency, how physical, chemical, and biological processes affect the marine carbonate system in a coastal area characterized by high alkalinity riverine discharge (Gulf of Trieste, northern Adriatic Sea, NE Mediterranean Sea).

By combining synoptic measurements of the carbonate system with in situ determinations of the primary production (14C incorporation technique) and secondary prokaryotic carbon production (3H-leucine incorporation) along a river-sea gradient, we showed that the conservative mixing between river endmember and off-shore waters was the main driver of the dissolved inorganic carbon (DIC) distribution and seasonal variation. However, during spring and summer seasons also the influence of biological uptake and release of DIC was significant. In the surface water of June 2012, the spreading and persistence of nutrient-rich freshwater stimulated the primary production (3.21 μg C L− 1 h− 1) and net biological DIC uptake (− 100 μmol kg− 1), reducing the dissolved CO2 concentration and increasing the pHT. Below the pycnocline of August 2012, instead, an elevated bacterial carbon production rate (0.92 μg C L− 1 h− 1) was related with net DIC increase (92 μmol kg− 1), low dissolved oxygen concentration, and strong pHT reduction, suggesting the predominance of bacterial heterotrophic respiration over primary production.

The flux of carbon dioxide estimated at the air-sea interface exerted a low influence on the seasonal variation of the carbonate system. A complex temporal and spatial dynamic of the air-sea CO2 exchange was also detected, due to the combined effects of seawater temperature, river discharge, and water circulation. On annual scale the system was a sink of atmospheric CO2. However, in summer and during elevated riverine discharges, the area close to the river’s mouth acted as a source of carbon dioxide. Also the wind speed was crucial in controlling the air-sea CO2 exchange, with strong Bora events (a typical ENE wind of the Gulf of Trieste) that drastically increased the absorption (− 32.2 mmol m− 2 day− 1) or the release (5.34 mmol m− 2 day− 1) of carbon dioxide.

Continue reading ‘Carbonate chemistry dynamics and biological processes along a river-sea gradient (Gulf of Trieste, northern Adriatic Sea)’

Interactive effects of parasitic infection and ocean acidification on the calcification of a marine gastropod

The interactive effects of ocean acidification (OA) and parasitic infection have the potential to alter the performance of many marine organisms. Parasitic infection can affect host organisms’ response to abiotic stressors, and vice versa, while the response of marine organisms to stressors associated with OA can vary within and between taxonomic groups (host or parasite). Accordingly, it seems likely that the combination of infection stress and the novel stressors associated with OA could alter previously stable host–parasite interactions. This study is a detailed investigation into the changes to shell growth, dissolution, and tensile strength in the New Zealand mud snail Zeacumantus subcarinatus caused by trematode infection in combination with exposure to simulated OA conditions. This study also tests the effects of reduced pH on snails infected by 3 different trematode species to investigate potential species-specific effects of infection. After a 90 d exposure to 3 pH treatments (pH 8.1, 7.6, and 7.4), acidified seawater caused significant reductions in shell growth, length, and tensile strength in all snails. Trematode infected snails displayed increased shell growth and dissolution and reduced shell strength relative to uninfected conspecifics. In all measured variables, there were also significant differences between snails maintained at the same pH but infected by different species of parasite. These results indicate that parasitic infection has the potential to alter host organisms’ response to OA and that the magnitude of this effect varies among parasite species.

Continue reading ‘Interactive effects of parasitic infection and ocean acidification on the calcification of a marine gastropod’

Physiological responses of a model marine diatom to fast pH changes: special implications of coastal water acidification

Diatoms and other phytoplankton in coastal waters experience rapid pH changes in milieu due to high biological activities and/or upwelled CO2-rich waters. While CO2 concentrating mechanisms (CCMs) are employed by all diatoms tested to counter low CO2 availability in seawater, little is known how this mechanism responds to fast pH changes. In the present study, the model diatom Thalassiosira pseudonana was acclimated for 20 generations to low pH (7.81) at an elevated CO2 of 1000 μatm (HC) or to high pH (8.18) at ambient CO2 levels of 390 μatm (LC), then its physiological characteristics were investigated as cells were shifted from HC to LC or vice versa. The maximal electron transport rate (ETRmax) in the HC-acclimated cells was immediately reduced by decreased CO2 availability, showing much lower values compared to that of the LC-acclimated cells. However, the cells showed a high capacity to regain their photochemical performance regardless of the growth CO2 levels, with their ETRmax values recovering to initial levels in about 100 min. This result indicates that this diatom might modulate its CCMs quickly to maintain a steady state supply of CO2, which is required for sustaining photosynthesis. In addition, active uptake of CO2 could play a fundamental role during the induction of CCMs under CO2 limitation, since the cells maintained high ETR even when both intracellular and periplasmic carbonic anhydrases were inhibited. It is concluded that efficient regulation of the CCM is one of the key strategies for diatoms to survive in fast changing pH environment, e.g. for the tested species, which is a dominant species in coastal waters where highly fluctuating pH is observed.

Continue reading ‘Physiological responses of a model marine diatom to fast pH changes: special implications of coastal water acidification’

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Ocean acidification in the IPCC AR5 WG II

OUP book