Archive for May, 2017



Enhancing global ocean acidification monitoring and research

The policy and scientific needs for coordinated, worldwide information-gathering on ocean acidification and its ecological impacts are now widely recognized. The importance of obtaining such measurements has been endorsed by the United Nations General Assembly, as well as by many other governmental and non-governmental bodies.

The Global Ocean Acidification Observing Network (GOA-ON), a collaborative international network of 367 members representing 66 nations, is committed to increasing global ocean acidification observing capacity in support of SDG target 14.3: Average marine acidity (pH) measured at agreed suite of representative sampling stations.

To achieve this commitment, GOA-ON and its partners are expected to continue to develop and nurture this global network. Importantly, we plan to work to build capacity in regions that currently have limited observation records and little ocean science capacity by conducting targeted training workshops on ocean acidification monitoring and experimentation best practices. We are committed to distributing sensor kits that will allow scientists in resource-poor countries to collect reliable data and so contribute to the global ocean acidification monitoring effort.

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It’s getting hot in here: how ocean acidification and warming affect shark hunting and behavior

Background

Sharks have an advanced sensory system that allows for efficient foraging using various senses such as sight, hearing, smelling, and touch.  They can even detect movement, and differences in pressure! Because of this, some sharks are high in the food web. So, any changes in their physiology and behavior due to the changing climate is likely to trickle down into lower trophic levels and alter the structure of the marine food web. What causes such changes, though?  When we burn fossil fuels such as coal, oil and gas for energy or transportation, excess carbon dioxide (CO2) gets released into the atmosphere. This excess CO2 acts like a heat trapping blanket and the ocean absorbs much of this heat. The ocean also absorbs about quarter of this excess CO2 where it reacts with seawater and making the ocean more acidic. This is called ocean acidification.

Continue reading ‘It’s getting hot in here: how ocean acidification and warming affect shark hunting and behavior’

Ocean acidification compromises a planktic calcifier with implications for global carbon cycling

Anthropogenically-forced changes in ocean chemistry at both the global and regional scale have the potential to negatively impact calcifying plankton, which play a key role in ecosystem functioning and marine carbon cycling. We cultured a globally important calcifying marine plankter (the foraminifer, Globigerina bulloides) under an ecologically relevant range of seawater pH (7.5 to 8.3 total scale). Multiple metrics of calcification and physiological performance varied with pH. At pH > 8.0, increased calcification occurred without a concomitant rise in respiration rates. However, as pH declined from 8.0 to 7.5, calcification and oxygen consumption both decreased, suggesting a reduced ability to precipitate shell material accompanied by metabolic depression. Repair of spines, important for both buoyancy and feeding, was also reduced at pH < 7.7. The dependence of calcification, respiration, and spine repair on seawater pH suggests that foraminifera will likely be challenged by future ocean conditions. Furthermore, the nature of these effects has the potential to actuate changes in vertical transport of organic and inorganic carbon, perturbing feedbacks to regional and global marine carbon cycling. The biological impacts of seawater pH have additional, important implications for the use of foraminifera as paleoceanographic indicators.

Continue reading ‘Ocean acidification compromises a planktic calcifier with implications for global carbon cycling’

Carbon assimilation and losses during an ocean acidification mesocosm experiment, with special reference to algal blooms

A mesocosm experiment was conducted in Wuyuan Bay (Xiamen), China, to investigate the effects of elevated pCO2 on bloom formation by phytoplankton species previously studied in laboratory-based ocean acidification experiments, to determine if the indoor-grown species performed similarly in mesocosms under more realistic environmental conditions. We measured biomass, primary productivity and particulate organic carbon (POC) as well as particulate organic nitrogen (PON). Phaeodactylum tricornutum outcompeted Thalassiosira weissflogii and Emiliania huxleyi, comprising more than 99% of the final biomass. Mainly through a capacity to tolerate nutrient-limited situations, P. tricornutum showed a powerful sustained presence during the plateau phase of growth. Significant differences between high and low CO2 treatments were found in cell concentration, cumulative primary productivity and POC in the plateau phase but not during the exponential phase of growth. Compared to the low pCO2 (LC) treatment, POC increased by 45.8–101.9% in the high pCO2 (HC) treated cells during the bloom period. Furthermore, respiratory carbon losses of gross primary productivity were found to comprise 39–64% for the LC and 31–41% for the HC mesocosms (daytime C fixation) in phase II. Our results suggest that the duration and characteristics of a diatom bloom can be affected by elevated pCO2. Effects of elevated pCO2 observed in the laboratory cannot be reliably extrapolated to large scale mesocosms with multiple influencing factors, especially during intense algal blooms.

Continue reading ‘Carbon assimilation and losses during an ocean acidification mesocosm experiment, with special reference to algal blooms’

Ocean acidification: Pacific conversations with SPREP

In June this year, the Pacific islands are amplifying their voice at the United Nations Ocean Conference at the UN Headquarters in New York, focusing on Sustainable Development Goal 14 – Life Below Water.

This Pacific Conversation discusses ocean acidification and its impacts on Pacific species, providing you with more information to help make a difference in our region.

Did you know that a lower pH, the potential of hydrogen, makes the ocean a louder place? By 2050, under conservative projections of ocean acidification, sounds could travel as much as 70% farther in some ocean areas. This means ocean acidification affects whales and other animals, not just coral reefs and shellfish.

The ocean absorbs about 25% of the CO2 that we emit. If we had to pay for it, the value of this ‘ocean service’ to the global economy is USD 60 to 400 billion annually (EPOCA).

By taking up our extra CO2, the ocean has acidified by 30% since the start of the Industrial Revolution. The current rate of decrease is 0.02 units per decade, faster than any rate in the past 300 million years. Projections show that by 2060, seawater acidity could have increased by 120%.

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Net community metabolism and seawater carbonate chemistry scale non-intuitively with coral cover

Coral cover and reef health have been declining globally as reefs face local and global stressors including higher temperature and ocean acidification (OA). Ocean warming and acidification will alter rates of benthic reef metabolism (i.e., primary production, respiration, calcification, and CaCO3 dissolution), but our understanding of community and ecosystem level responses is limited in terms of functional, spatial, and temporal scales. Furthermore, dramatic changes in coral cover and benthic metabolism could alter seawater carbonate chemistry on coral reefs, locally alleviating or exacerbating OA. This study examines how benthic metabolic rates scale with changing coral cover (0-100%), and the subsequent influence of these coral communities on seawater carbonate chemistry based on mesocosm experiments in Bermuda and Hawaii. In Bermuda, no significant differences in benthic metabolism or seawater carbonate chemistry were observed for low (40%) and high (80%) coral cover due to large variability within treatments. In contrast, significant differences were detected between treatments in Hawaii with benthic metabolic rates increasing with increasing coral cover. Observed increases in daily net community calcification and nighttime net respiration scaled proportionally with coral cover. This was not true for daytime net community organic carbon production rates, which increased the most between 0 to 20% coral cover and then less so between 20% to 100%. These differences in scaling resulted in larger diel variability in seawater carbonate chemistry as coral cover increased. To place the results of the mesocosm experiments into a broader context, in situ seawater carbon dioxide (CO2) at three reef sites in Bermuda and Hawaii were also evaluated; reefs with higher coral cover experienced a greater range of diel CO2 levels, complementing the mesocosm results. The results from this study highlight the need to consider the natural complexity of reefs and additional biological and physical factors that influence seawater carbonate chemistry on larger spatial and longer temporal scales. Coordinated efforts combining various research approaches (e.g. experiments, field studies, and models) will be required to better understand how benthic metabolism integrates across functional, spatial, and temporal scales, and for making predictions on how coral reefs will respond to climate change.

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What a decade (2006-15) of journal abstracts can tell us about trends in ocean and coastal sustainability challenges and solutions

Text mining and analytics may offer possibilities to assess scientists’ professional writing and identify patterns of co-occurrence between words and phrases associated with different environmental challenges and their potential solutions. This approach has the potential to help to track emerging issues, semi-automate horizon scanning processes, and identify how different institutions or policy instruments are associated with different types of ocean and coastal sustainability challenges. Here I examine ecologically-oriented ocean and coastal science journal article abstracts published between 2006 and 2015. Informed by the Institutional Analysis and Development (IAD) framework, I constructed a dictionary containing phrases associated with 40 ocean challenges and 15 solution-oriented instrument or investments. From 50,817 potentially relevant abstracts, different patterns of co-occurring text associated with challenges and potential solutions were discernable. Topics receiving significantly increased attention in the literature in 2014-15 relative to the 2006-13 period included: marine plastics and debris; environmental conservation; social impacts; ocean acidification; general terrestrial influences; co-management strategies; ocean warming; licensing and access rights; oil spills; and economic impacts. Articles relating to global environmental change were consistently among the most cited; marine plastics and ecosystem trophic structure were also focal topics among the highly cited articles. This exploratory research suggests that scientists’ written outputs provide fertile ground for identifying and tracking important and emerging ocean sustainability issues and their possible solutions, as well as the organizations and scientists who work on them.

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Bacterial community responses during a possible CO2 leaking from sub-seabed storage in marine polluted sediments

Carbon capture and storage (CCS) is a viable option to reduce high concentrations of CO2 and mitigate their negative effects. This option has associated risks such as possible CO2 leakage from the storage sites. So far, negative effects deriving from a CO2 release have been reported for benthic macrofauna in both polluted and nonpolluted sediments. However, bacterial communities has no considered. In this work, risk assessment was carried out in order to evaluate the possible effects in a contaminated area considering bacterial responses (total number of cells, respiring activity, changes in the bacterial community composition and diversity). Four microcosms were placed into an integrated CO2 injection system with a non-pressurized chamber to simulate four different pH treatments (pH control 7.8, 7, 6.5 and 6). Results showed an impact on bacterial communities because of the CO2 treatment. Changes in respiring activity, community composition groups and diversity were found. This study highlights the use of respiring bacteria activity not only as bioindicator for environmental risk assessment and monitoring purposes but also as a bioindicador during a CO2 leakage event or CO2 enrichment process among all the responses studied.

Continue reading ‘Bacterial community responses during a possible CO2 leaking from sub-seabed storage in marine polluted sediments’

Acidification et réchauffement extrêmement rapides en Méditerranée nord-occidentale (in French)

Ayant analysé une série temporelle de haute fréquence acquise dans la rade de Villefranche-sur-Mer, des chercheurs du Laboratoire d’océanographie de Villefranche (LOV/OOV, UPMC / CNRS) et de l’Institut des relations internationales et du développement durable (Sciences Po, Paris) ont mis en évidence les changements très rapides qu’a connu l’eau de mer dans cette région entre 2007 et 2015. L’augmentation de la température y a été plus rapide que partout ailleurs dans l’océan global et celle de son acidité l’une des plus élevées jamais mesurées dans l’océan. En conséquence, plusieurs organismes sont affectés, ce qui pourrait altérer la chaîne alimentaire méditerranéenne.

Les mers et océans sont affectés de multiples manières par les activités humaines. Il est bien établi que les rejets de gaz carbonique (CO2) par les activités humaines entraînent un réchauffement. Environ 25 % de ces rejets sont absorbés par l’océan, soit 26 millions de tonnes de CO2. Cela permet de limiter les changements climatiques, mais au prix d’un bouleversement de la chimie de l’eau de mer, notamment une augmentation de son acidité.

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Impact of climate change on direct and indirect species interactions

Recent marine climate change research has largely focused on the response of individual species to environmental changes including warming and acidification. The response of communities, driven by the direct effects of ocean change on individual species as well the cascade of indirect effects, has received far less study. We used several rocky intertidal species including crabs, whelks, juvenile abalone, and mussels to determine how feeding, growth, and interactions between species could be shifted by changing ocean conditions. Our 10 wk experiment revealed many complex outcomes which highlight the unpredictability of community-level responses. Contrary to our predictions, the largest impact of elevated CO2 was reduced crab feeding and survival, with a pH drop of 0.3 units. Surprisingly, whelks showed no response to higher temperatures or CO2 levels, while abalone shells grew 40% less under high CO2 conditions. Massive non-consumptive effects of crabs on whelks showed how important indirect effects can be in determining climate change responses. Predictions of species outcomes that account solely for physiological responses to climate change do not consider the potentially large role of indirect effects due to species interactions. For strongly linked species (e.g. predator-prey or competitor relationships), the indirect effects of climate change are much less known than direct effects, but may be far more powerful in reshaping future marine communities.

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