Archive for July, 2017

How farming giant seaweed can feed fish and fix the climate

Bren Smith, an ex-industrial trawler man, operates a farm in Long Island Sound, near New Haven, Connecticut. Fish are not the focus of his new enterprise, but rather kelp and high-value shellfish. The seaweed and mussels grow on floating ropes, from which hang baskets filled with scallops and oysters. The technology allows for the production of about 40 tonnes of kelp and a million bivalves per hectare per year.

The kelp draw in so much carbon dioxide that they help de-acidify the water, providing an ideal environment for shell growth. The CO₂ is taken out of the water in much the same way that a land plant takes CO₂ out of the air. But because CO₂ has an acidifying effect on seawater, as the kelp absorb the CO₂ the water becomes less acid. And the kelp itself has some value as a feedstock in agriculture and various industrial purposes.

Continue reading ‘How farming giant seaweed can feed fish and fix the climate’

Feeding in deep-sea demosponges: influence of abiotic and biotic factors

In shallow benthic communities, sponges are widely recognized for their ability to contribute to food webs by cycling nutrients and mediating carbon fluxes through filter feeding. In comparison, little is known about filter feeding in deep-sea species and how it may be modulated by environmental conditions. Here, a rare opportunity to maintain live healthy deep-sea sponges for an extended period led to a preliminary experimental study of their feeding metrics. This work focused on demosponges collected from the continental slope of eastern Canada at ~1000 m depth. Filtration rates (as clearance of phytoplankton cells) at holding temperature (6 °C) were positively correlated with food particle concentration, ranging on average from 18.8 to 160.6 cells ml-1 h-1 at nominal concentrations of 10 000 to 40 000 cells ml-1. Cell clearance was not significantly affected by decreasing seawater temperature, from 6 °C to 3 °C or 0 °C, although two of the sponges showed decreased filtration rates. Low pH (~7.5) and the presence of a predatory sea star markedly depressed or inhibited feeding activity in all sponges tested. While performed under laboratory conditions on a limited number of specimens, this work highlights the possible sensitivity of deep-sea demosponges to various types and levels of biotic and abiotic factors, inferring a consequent vulnerability to natural and anthropogenic disturbances.

Continue reading ‘Feeding in deep-sea demosponges: influence of abiotic and biotic factors’

Non-uniform ocean acidification and attenuation of the ocean carbon sink

Surface ocean carbon chemistry is changing rapidly. Partial pressures of carbon dioxide gas (pCO2) are rising, pH levels are declining, and the ocean’s buffer capacity is eroding. Regional differences in short-term pH trends primarily have been attributed to physical and biological processes; however, heterogeneous seawater carbonate chemistry may also be playing an important role. Here we use Surface Ocean CO2 Atlas (SOCAT) Version 4 data to develop 12-month gridded climatologies of carbonate system variables and explore the coherent spatial patterns of ocean acidification and attenuation in the ocean carbon sink caused by rising atmospheric pCO2. High-latitude regions exhibit the highest pH and buffer capacity sensitivities to pCO2 increases, while the equatorial Pacific is uniquely insensitive due to a newly defined aqueous CO2 concentration effect. Importantly, dissimilar regional pH trends do not necessarily equate to dissimilar acidity ([H+]) trends, indicating that [H+] is a more useful metric of acidification.

Continue reading ‘Non-uniform ocean acidification and attenuation of the ocean carbon sink’

Two Saildrones collecting OA data are on their way to the Bering Strait

Photo credit: NOAA

In mid July, two autonomous vehicles resembling small sailboats set off from Dutch Harbor in an effort to help scientists better understand ocean acidification in the Bering Sea and Arctic waters.  Known as Saildrones, the vehicles are about the size of a Hobie Cat sailboat and are capable of traveling unsupported for thousands of miles using only wind and solar energy.  In the past few years, NOAA scientists have conducted pilot work using the Saildrones in the Bering Sea, however this is the first year a Saildrone will be actively collecting ocean acidification parameters and sailing into the Arctic ocean.

Jessica Cross, an oceanographer with NOAA’s Pacific Marine Environmental Lab, is a principal investigator on the project. Cross notes, “The Saildrones are a really important asset for Arctic surveys. They can reach farther and carry more sensors than ever before, and most important—they are fast and flexible!” The Saildrones can access newly emerging features on short notice, adding a lot of adaptability to current research tactics.

Continue reading ‘Two Saildrones collecting OA data are on their way to the Bering Strait’

CMS students on NOAA ocean acidification cruise

KEY WEST, FL – USF College of Marine Science students Jon Sharp, Katelyn Schockman, and Ellie Hudson-Heck from the Byrne Lab, along with Eckerd College intern Courtney Tierney, are currently sailing aboard NOAA’s R/V Ronald H. Brown on the 2017 Gulf of Mexico Ecosystems and Carbon Cycle Cruise (GOMECC-3). The Brown departed Key West, Florida on July 18, 2017 and will return to Ft. Lauderdale, Florida on August 21, 2017, after a full loop around the Gulf of Mexico.

This is the most comprehensive ocean acidification cruise in this region to date, and the first of its kind to explore Mexican waters. Jon, Katelyn, Ellie, and Courtney are measuring pH and carbonate ion concentrations in the Gulf. These data will be vital for evaluating the progression of ocean acidification across the basin and on regional scales, with a particular focus on coastal dynamics.

Continue reading ‘CMS students on NOAA ocean acidification cruise’

Call for applications: “Practical Training Courses on Ocean Acidification”, October – November 2017, Suva, Fiji

Course I (30 October – 3 November): Introduction to Ocean Acidification Monitoring and Research 

Course II (6 November – 10 November): Applied Ocean Acidification Monitoring and Research Techniques 

Host institute: University of the South Pacific, Suva, Fiji


These courses are part of a broad effort by The Ocean Foundation, through its International Ocean Acidification Initiative, to expand the capacity of scientists and resource managers around the world to monitor, understand, and respond to ocean acidification in their region. The Ocean Foundation’s work is supported by the partners listed above and is coordinated closely with the Global Ocean Acidification Observing Network (GOA-ON). We invite interested participants to apply for one or both courses described here.

The courses advertised here are meant for those who have the skills and interest in implementing monitoring programs. Though we have specified educational and occupational requirements for participants, our primary goal is to ensure that stakeholders from the Pacific Islands have access to information about how ocean acidification might affect them locally. Therefore, if you do not meet the educational or occupational requirements listed for the courses below, please contact Alexis Valauri-Orton at to discuss how you might be able to participate.

Continue reading ‘Call for applications: “Practical Training Courses on Ocean Acidification”, October – November 2017, Suva, Fiji’

Determination of pH in estuarine and brackish waters: Pitzer parameters for Tris buffers and dissociation constants for m-cresol purple at 298.15 K

Measurements of pH in seawater are important to determine the natural and anthropogenic trends in the oceans. Spectrophotometry or glass electrode potentiometry measurements of pH require calibration with help of buffers. One common buffer solution is the Tris/Tris·H+ couple, which should be well characterised both experimentally and theoretically for optimum accuracy. Chemical speciation modelling in the complex seawater medium is best addressed with an ion interaction approach, with Pitzer equations being the most widely used. The published Pitzer coefficients for Tris and Tris·H+ in artificial seawater are based on isopiestic measurements, which necessarily give strong weight to the third virial coefficient C for the key interaction between Tris·H+and chloride. However, in low salinity waters it is the second virial coefficient B that is of greater importance. We have used Harned cell measurements of Tris solutions at ionic strengths up to 1 mol kg− 1 to reassess the relevant Pitzer parameters, and have found improved agreement with experimental measurements in artificial seawater. We suggest that additional measurements should be undertaken to address the remaining differences between model calculations and experimental data in artificial seawater. We have used the revised Pitzer parameters to reassess the acid-base constant of the indicator m-cresol purple in low salinity waters.

Continue reading ‘Determination of pH in estuarine and brackish waters: Pitzer parameters for Tris buffers and dissociation constants for m-cresol purple at 298.15 K’

Daily variation in net primary production and net calcification in coral reef communities exposed to elevated pCO2 (update)

The threat represented by ocean acidification (OA) for coral reefs has received considerable attention because of the sensitivity of calcifiers to changing seawater carbonate chemistry. However, most studies have focused on the organismic response of calcification to OA, and only a few have addressed community-level effects, or investigated parameters other than calcification, such as photosynthesis. Light (photosynthetically active radiation, PAR) is a driver of biological processes on coral reefs, and the possibility that these processes might be perturbed by OA has important implications for community function. Here we investigate how CO2 enrichment affects the relationships between PAR and community net O2 production (Pnet), and between PAR and community net calcification (Gnet), using experiments on three coral communities constructed to match (i) the back reef of Mo’orea, French Polynesia, (ii) the fore reef of Mo’orea, and (iii) the back reef of O’ahu, Hawaii. The results were used to test the hypothesis that OA affects the relationship between Pnet and Gnet. For the three communities tested, pCO2 did not affect the Pnet–PAR relationship, but it affected the intercept of the hyperbolic tangent curve fitting the Gnet–PAR relationship for both reef communities in Mo’orea (but not in O’ahu). For the three communities, the slopes of the linear relationships between Pnet and Gnet were not affected by OA, although the intercepts were depressed by the inhibitory effect of high pCO2 on Gnet. Our result indicates that OA can modify the balance between net calcification and net photosynthesis of reef communities by depressing community calcification, but without affecting community photosynthesis.

Continue reading ‘Daily variation in net primary production and net calcification in coral reef communities exposed to elevated pCO2 (update)’

Ocean acidification hampers sperm-egg collisions, gamete fusion, and generation of Ca2+ oscillations of a broadcast spawning bivalve, Tegillarca granosa

Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca2+oscillations. Therefore, the realistic effects of future ocean pCO2 levels on these specific aspects of fertilization of Tegillarca granosa were investigated in the present study through sperm velocity trials, fertilization kinetics model analysis, and intracellular Ca2+assays, respectively. Results obtained indicated that ocean acidification significantly reduced the fertilization success of T. granosa, which could be accountable by (i) decreased sperm velocity hence reducing the probability for sperm-egg collisions; (ii) lowered probability of gamete fusion for each gamete collision event; and (iii) disrupted intracellular Ca2+ oscillations.

Continue reading ‘Ocean acidification hampers sperm-egg collisions, gamete fusion, and generation of Ca2+ oscillations of a broadcast spawning bivalve, Tegillarca granosa’

Altered sediment biota and lagoon habitat carbonate dynamics due to sea cucumber bioturbation in a high-pCO2 environment

The effects of global change on biological systems and functioning are already measureable, but how ecological interactions are being altered is poorly understood. Ecosystem resilience is strengthened by ecological functionality, which depends on trophic interactions between key species and resilience generated through biogenic buffering. Climate-driven alterations to coral reef metabolism, structural complexity and biodiversity are well documented, but the feedbacks between ocean change and trophic interactions of non-coral invertebrates are understudied. Sea cucumbers, some of the largest benthic inhabitants of tropical lagoon systems, can influence diel changes in reef carbonate dynamics. Whether they have the potential to exacerbate or buffer ocean acidification over diel cycles depends on their relative production of total alkalinity (AT) through the dissolution of ingested calcium carbonate (CaCO3) sediments and release of dissolved inorganic carbon (CT) through respiration and trophic interactions. In this study, the potential for the sea cucumber, Stichopus herrmanni, a bêche-de-mer (fished) species listed as vulnerable to extinction, to buffer the impacts of ocean acidification on reef carbonate chemistry was investigated in lagoon sediment mesocosms across diel cycles. Stichopus herrmanni directly reduced the abundance of meiofauna and benthic primary producers through its deposit-feeding activity under present-day and near-future pCO2. These changes in benthic community structure, as well as AT (sediment dissolution) and CT (respiration) production by S. herrmanni, played a significant role in modifying seawater carbonate dynamics night and day. This previously unappreciated role of tropical sea cucumbers, in support of ecosystem resilience in the face of global change, is an important consideration with respect to the bêche-de-mer trade to ensure sea cucumber populations are sustained in a future ocean.

Continue reading ‘Altered sediment biota and lagoon habitat carbonate dynamics due to sea cucumber bioturbation in a high-pCO2 environment’

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Ocean acidification in the IPCC AR5 WG II

OUP book