Archive for April, 2015

Co-variation of metabolic rates and cell-size in coccolithophores

Coccolithophores are sensitive recorders of environmental change. The size of their coccosphere varies in the ocean along gradients of environmental conditions and provides a key for understanding the fate of this important phytoplankton group in the future ocean. But interpreting field changes in coccosphere size in terms of laboratory observations is hard, mainly because the marine signal reflects the response of multiple morphotypes to changes in a combination of environmental variables. In this paper I examine the large corpus of published laboratory experiments with coccolithophores looking for relations between environmental conditions, metabolic rates and cell size (a proxy for coccosphere size). I show that growth, photosynthesis, and to a lesser extent calcification, co-vary with cell size when pCO2, irradiance, temperature, nitrate, phosphate and iron conditions change. With the exception of phosphate and temperature, a change from limiting to non-limiting conditions always results in an increase in cell size. An increase in phosphate or temperature produces the opposite effect. The magnitude of the coccosphere size changes observed in the laboratory is comparable to that observed in the ocean. If the biological reasons behind the environment-metabolism-size link are understood, it will be possible to use coccosphere size changes in the modern ocean and in marine sediments to investigate the fate of coccolithophores in the future ocean. This reasoning can be extended to the size of coccoliths if, as recent experiments are starting to show, coccolith size reacts to environmental change proportionally to coccosphere size. I introduce a simple model that simulates the growth rate and the size of cells forced by nitrate and phosphate concentrations. By considering a simple rule that allocates the energy flow from nutrient acquisition to cell structure (biomass) and cell maturity (biological complexity, eventually leading to cell division), the model is able to reproduce the co-variation of growth rate and cell size observed in the laboratory when these nutrients become limiting. These results support ongoing efforts to interpret coccosphere and coccolith size measurements in the context of climate change.

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Corrigendum to “Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry” published in Biogeosciences, 12, 1753–1763, 2015

The authors regret that a typographical error appeared in the above paper on page 1756, first column, lines 8–9. The authors apologise for any inconvenience caused, and the correct lines should read as follows: Our estimate of δ11Bsw of 39.8 ± 0.4 ‰ (2 SD, n = 30) is independent of sample size and is in agreement with published values of 39.6 ± 0.2 ‰ (2 SD) (Foster et al., 2010) and 39.7 ± 0.6 ‰ (2 SD) (Spivack and Edmond, 1987).

Continue reading ‘Corrigendum to “Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry” published in Biogeosciences, 12, 1753–1763, 2015’

CERF 2015 Call for abstracts: “Ocean acidification and hypoxia: connecting science to decision-making”

Abstract Submission Deadline: 1 May 2015

The session that will highlight opportunities for linking information from the scientific community with natural resource managers to promote effective science-based decision making on the topics of ocean acidification and hypoxia (OAH). This session will explore pathways for tapping into cutting-edge OAH science, tools for understanding the information needs of managers,
and mechanisms to connect the two. Participants are encouraged to contribute talks about ocean acidification and hypoxia in the following areas:

– Social or natural science, focusing on connecting science to ocean and coastal policy, regulation, industry, and/or management

– Decision-making in natural resource management

Continue reading ‘CERF 2015 Call for abstracts: “Ocean acidification and hypoxia: connecting science to decision-making”’

Casco Bay deemed healthy, but trouble spots grow

The water quality is good overall, but near coastal areas it is quickly degrading because of nitrogen overload and acidification, a decade of data shows.

Casco Bay is healthy, but water quality near coastal areas and estuaries is rapidly degrading because of man-made pollution, according to a study released Tuesday by the Friends of Casco Bay.

The report containing more than 10 years of data collected between Cape Elizabeth and Cape Small shows that the effects of global climate change and the local introduction of nitrogen and other pollutants have significantly altered the chemistry of Casco Bay’s waters.

The most pressing problem is the acidification of mud flats and coastal waters, a process that has led to reduced stocks of clams, mussels and other sea life, threatening the balance of a treasured resource, the report said.

Continue reading ‘Casco Bay deemed healthy, but trouble spots grow’

A new report reveals the answer to “How healthy is Casco Bay?”

Portland, Maine–The chemistry of the water in Casco Bay is changing, and not for the better. It is also changing more rapidly than anyone could have predicted. Those are some of the key conclusions in the report, A Changing Casco Bay, released by Friends of Casco Bay on April 28th.

The report answers the question, “How healthy is Casco Bay?” Decades of research by the conservation organization suggests that our Bay, though generally healthy, is facing an uncertain future.
The coastal waters of Maine’s most populous region are becoming more acidic, making it harder for shellfish, such as clams, oysters, and mussels, to build and maintain their shells. As the water becomes more acidic, shell-building material—calcium carbonate—dissolves back into the water.

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Seaweed might have the power to make the oceans less acidic

The thick, slimy brown ribbons are notorious for tangling the ankles of beachgoers and rotting in pungent piles. But kelp, according to its growing fan base, could also prove potent in protecting the health of oceans — and us.

“We’ve got some bad water heading our way,” said Betsy Peabody, founder and executive director of the Puget Sound Restoration Fund. In April, Peabody’s small organization in Bainbridge Island, Washington, won a $1.5 million grant from the Paul Allen Family Foundation to investigate how cultivating the seaweed might help lessen the impacts of ocean acidification.

Continue reading ‘Seaweed might have the power to make the oceans less acidic’

Negative effects of ocean acidification on calcification vary within the coccolithophore genus Calcidiscus

A large percentage of CO2 emitted into the atmosphere is absorbed by the oceans, causing chemical changes in surface waters known as ocean acidification (OA). Despite the high interest and increased pace of OA research to understand the effects of OA on marine organisms, many ecologically important organisms remain unstudied. Calcidiscus is a heavily calcified coccolithophore genus that is widespread and genetically and morphologically diverse. It contributes substantially to global calcium carbonate production, organic carbon production, oceanic carbon burial, and ocean–atmosphere CO2 exchange. Despite the importance of this genus, relatively little work has examined its responses to OA. We examined changes in growth, morphology, and carbon allocation in multiple strains of Calcidiscus leptoporus in response to ocean acidification. We also, for the first time, examined the OA response of Calcidiscus quadriperforatus, a larger and more heavily calcified Calcidiscus congener. All Calcidiscus coccolithophores responded negatively to OA with impaired coccolith morphology and a decreased ratio of particulate inorganic to organic carbon (PIC:POC). However, strains responded variably; C. quadriperforatus showed the most sensitivity, while the most lightly calcified strain of C. leptoporus showed little response to OA. Our findings suggest that calcium carbonate production relative to organic carbon production by Calcidiscus coccolithophores may decrease in future oceans and that Calcidiscus distributions may shift if more resilient strains and species become dominant in assemblages. This study demonstrates that variable responses to OA may be strain or species specific in a way that is closely linked to physiological traits, such as cellular calcite quota.

Continue reading ‘Negative effects of ocean acidification on calcification vary within the coccolithophore genus Calcidiscus’

Five teams advance to Hawaii for final stage of $2 million Wendy Schmidt Ocean Health XPRIZE

Global Competition to Revolutionize Ocean pH Sensor Technology Heads to the Pacific Ocean for Deep Sea Testing

Los Angeles (April 28, 2015) XPRIZE, the global leader in incentivized prize competition, today announced the five finalist teams competing for the $2M Wendy Schmidt Ocean Health XPRIZE, a global competition to create pH sensor technology that will accurately measure ocean acidification.

Beginning on May 14 in Honolulu, teams will board the R/V Kilo Moana, a research vessel owned by the U.S. Navy and operated through UNOLS by the University of Hawaii Marine Center, and embark on a week-long deep sea trial to assess ocean pH values throughout the water column at Station ALOHA, a 110 square mile region in the Pacific Ocean, located approximately 100 miles off the northern shore of Oahu. During this six-day period, sensors will be put through rigorous performance tests focused on stability and precision, while battling real-world pressure scenarios and depths of up to 3,000 meters.

Continue reading ‘Five teams advance to Hawaii for final stage of $2 million Wendy Schmidt Ocean Health XPRIZE’

Spatiotemporal variability of alkalinity in the Mediterranean Sea (update)

The paper provides a basin-scale assessment of the spatiotemporal distribution of alkalinity in the Mediterranean Sea. The assessment is made by integrating the available observations into a 3-D transport–biogeochemical model. The results indicate the presence of complex spatial patterns: a marked west-to-east surface gradient of alkalinity is coupled to secondary negative gradients: (1) from marginal seas (Adriatic and Aegean Sea) to the eastern Mediterranean Sea and (2) from north to south in the western region. The west–east gradient is related to the mixing of Atlantic water entering from the Strait of Gibraltar with the high-alkaline water of the eastern sub-basins, which is correlated to the positive surface flux of evaporation minus precipitation. The north-to-south gradients are related to the terrestrial input and to the input of the Black Sea water through the Dardanelles. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1) that is driven by physical processes (seasonal cycle of evaporation and vertical mixing) and, to a minor extent, by biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships: in regions of freshwater influence, the two quantities are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open sea areas of the Mediterranean Sea.

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The Oceans 2015 Initiative, Part II: An updated understanding of the observed and projected impacts of ocean warming and acidification on marine and coastal socioeconomic activities/sectors


Between 1971 and 2010, the oceans have absorbed approximately 93% of the excess heat caused by global warming, leading to several major changes such as the increase in stratification, limitation in the circulation of nutrients from deep waters to the surface, and sea level rise. In addition, the oceans absorbed 26% of anthropogenic CO2 emitted since the start of the Industrial Revolution, which resulted in ocean acidification. Together, these processes strongly affect marine and coastal species’ geographic distribution, abundance, migration patterns and phenology. As a consequence of these complex environmental changes, marine and coastal human sectors (i.e., fisheries, aquaculture, coastal tourism and health) are in turn at risk. This report provides an updated synthesis of what the science tells us about such a risk, based upon IPCC AR5 (2013- 2014) and published scientific articles and grey literature that have been published between July 2013 and April 2015.

Continue reading ‘The Oceans 2015 Initiative, Part II: An updated understanding of the observed and projected impacts of ocean warming and acidification on marine and coastal socioeconomic activities/sectors’

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Ocean acidification in the IPCC AR5 WG II

OUP book