Archive for August, 2018

New NOAA PMEL data portal

NOAA’s Pacific Marine Environmental Laboratory released their new ocean carbon and ocean acidification data portal.

Continue reading ‘New NOAA PMEL data portal’

«Ici, on peut étudier le futur comme le passé» (in French)

Des biologistes au cours d’une expédition en juillet près de l’île de Shikine-jima, au Japon.

Des biologistes au cours d’une expédition en juillet près de l’île de Shikine-jima, au Japon. Photo M. Kohzuka       

Sur la petite île volcanique japonaise de Shikine-jima, «Libé» a accompagné une équipe scientifique chargée d’observer l’acidification qui guette nos océans. Une expérience alarmante.

Il semble neiger sous l’eau. Des flocons ronds et brillants glissent entre les plongeurs et remontent en ondulant vers la surface. «C’est comme nager dans du champagne !» s’exclame le biologiste marin Jason Hall-Spencer. Près de l’île de Shikine-jima, à 160 kilomètres au sud de Tokyo, du gaz carbonique suinte des profondeurs de la Terre et s’échappe en un ballet de bulles. Rien de plus naturel car le confetti de moins de 4 km² fait partie d’un chapelet d’îles volcaniques qui s’égrènent entre l’océan Pacifique et la mer des Philippines. Cet été, une équipe scientifique internationale a stationné dans la zone pendant une semaine, partageant ses heures entre expérimentations à terre sur Shikine-jima et plongées en bateau autour de la source. Libération a participé à l’expédition.

Dans la baie de Mikawa, les côtes déchiquetées et plissées laissent deviner les remous de la lave à l’origine de leur formation. C’est là, au fond d’une crique, que les eaux bouillonnent. Longtemps boudées par les pêcheurs de l’île qui se plaignaient de l’absence de poissons, elles attirent aujourd’hui les chercheurs du monde entier. «Ce site est exceptionnel car il nous permet d’étudier le futur comme le passé des océans», résume Sylvain Agostini, de l’université de Tsukuba, près de Tokyo.

Continue reading ‘«Ici, on peut étudier le futur comme le passé» (in French)’

CO2, la mer défoncée à l’acide (in French)

Près de l’île de Shikine-jima, au Japon.

Près de l’île de Shikine-jima, au Japon. Photo docteur Ben Harvey 

Depuis la révolution industrielle, les émissions de dioxyde de carbone n’ont eu de cesse d’augmenter dans l’atmosphère, modifiant et menaçant les organismes et les écosystèmes marins indispensables à la régulation du réchauffement climatique.

Le CO2, toujours le CO2. Le principal gaz à effet de serre que les humains émettent en quantité depuis l’époque industrielle est le grand responsable du réchauffement climatique. Seulement, on l’oublie souvent, ce mauvais garçon provoque l’acidification des océans, une des conséquences majeures de nos émissions.

Comment le changement climatique engendre-t-il l’acidification des océans ?

«L’océan et l’atmosphère échangent depuis toujours naturellement du dioxyde de carbone, explique la chercheuse au CNRS spécialiste de la géochimie marine Catherine Jeandel. C’est un gaz soluble dans l’eau, surtout les eaux froides. Il s’y dissocie pour former des ions H+ qui rendent l’eau plus acide.» C’est le même phénomène que pour les sodas. Chaque jour, 30 millions de tonnes de CO2 sont absorbées sur les premières centaines de mètres de surface marine, soit entre un quart et un tiers de ce qui est émis par les activités humaines. Tout comme les forêts qui stockent près de 40 % du carbone terrestre (en incluant à la fois biomasse végétale et sol). «Grâce au phytoplancton, l’océan crée 50 % de l’oxygène qu’on respire, ajoute le directeur de l’Observatoire océanologique de Banyuls-sur-Mer (Pyrénées-Orientales), Vincent Laudet. Seulement, cette pompe marche tant que le plancton se développe bien. Avec l’acidification des océans, qui empêche une bonne fixation du carbone dans le carbonate de calcium, cette fonction pourrait bien diminuer.» Jusqu’à quel point les surfaces marines arriveront-elles à capter du carbone ? Difficile à dire. Pour la chercheuse Françoise Gaill, de la plateforme Océan et Climat, il existe «une limite de chaleur que l’océan peut capturer, mais nous ne la connaissons pas encore. Atteindre ce seuil de saturation aura des conséquences dramatiques pour la vie sur Terre».

Continue reading ‘CO2, la mer défoncée à l’acide (in French)’

SDG Indicator 14.3.1 Methodology accepted by the IOC-UNESCO Executive Council

During its 51st Executive Council Meeting from 3-6 July 2018, the Member States of the Intergovernmental Oceanographic Commission (IOC) of UNESCO welcomed the Methodology for the Sustainable Development Goal (SDG) Target Indicator 14.3.1 and recommended to the IOC secretary as the custodian agency for this indicator to propose its upgrade from Tier III to Tier II. The SDG Target Indicator 14.3.1 calls for “average marine acidity measured at an agreed suite of representative sampling stations“. The Methodology provides guidance to scientists and countries about how to carry out measurements following the best practices established by experts in the ocean acidification community, including members of the Global Ocean Acidification Observing Network (GOA-ON), and explains how to report the collected information.
Continue reading ‘SDG Indicator 14.3.1 Methodology accepted by the IOC-UNESCO Executive Council’

Lawsuit launched over federal failure to address ocean acidification in Oregon

PORTLAND, Ore.— The Center for Biological Diversity today filed a notice of intent to sue the Trump administration for refusing to recognize that ocean acidification caused by fossil fuel pollution is impairing waterways in Oregon.

Today’s filing notes that the U.S. Environmental Protection Agency has failed to fulfill its requirement under the Clean Water Act to identify waters impaired by ocean acidification so that they can then be subject to pollution controls and other mitigation measures.

Continue reading ‘Lawsuit launched over federal failure to address ocean acidification in Oregon’

A simple colorimetric method for determining seawater alkalinity using bromophenol blue

The development of small portable USB‐spectrophotometer systems makes monitoring alkalinity and pH possible in the field and remote locations. Here, we present a method utilizing purified bromophenol blue (BPB) as an end‐point indicator for making simple one‐point alkalinity measurements with spectrophotometric detection. The approach utilizes purified BPB dye whose absorbance characteristics have been determined over a range of temperatures and salinities. The end‐point pH for titrated samples was determined using the BPB absorbance ratio (R(t) = 25 A590/A436) for the acid and base forms via the following equation: urn:x-wiley:15415856:media:lom310253:lom310253-math-0001, where, e1 = 0.00533, e2 = 2.232, e3 = 0.0319. A pKa of 3.513 was determined for the dissociation of the second proton from the BPB dye. The temperature (t) dependence of R can be expressed using the following relationship: urn:x-wiley:15415856:media:lom310253:lom310253-math-0002. The dependence of the pKa on salinity (S) was weak and can be expressed as urn:x-wiley:15415856:media:lom310253:lom310253-math-0003. Application of the method for determining the alkalinity of in‐house and certified standards typically produced an uncertainty of ± 1.5 μmol kg−1 for purified BPB dye. When the impure BPB dye was used as an end‐point indicator the uncertainty for alkalinity measured was slightly higher at approximately ± 3–4 μmol kg−1. Hence, if high‐precision alkalinity measurements are not required (≥ 4 μmol kg−1) then utilization of the unpurified BPB maybe suitable. We also compared the use of BPB to two other dyes: bromocresol purple (BCP) and bromocresol green (BCG). The utilization of all three dyes for end‐point determination produced comparable results with an overall precision of ± 4 μmol kg−1. The one‐point titration method using BPB was utilized at a remote field location, One Tree Island, Australia and was found to be suitable for producing accurate and precise alkalinity data in a timely manner; ∼ 10–15 samples can be determined per hour. When combined with seawater pH measurements, the one‐point titration method allows the full marine carbonate system to be fully constrained without the need for high‐tech spectrophotometric equipment and comprehensive laboratory facilities.

Continue reading ‘A simple colorimetric method for determining seawater alkalinity using bromophenol blue’

Resistance of corals and coralline algae to ocean acidification: physiological control of calcification under natural pH variability

Ocean acidification is a threat to the continued accretion of coral reefs, though some undergo daily fluctuations in pH exceeding declines predicted by 2100. We test whether exposure to greater pH variability enhances resistance to ocean acidification for the coral Goniopora sp. and coralline alga Hydrolithon reinboldii from two sites: one with low pH variability (less than 0.15 units daily; Shell Island) and a site with high pH variability (up to 1.4 pH units daily; Tallon Island). We grew populations of both species for more than 100 days under a combination of differing pH variability (high/low) and means (ambient pH 8.05/ocean acidification pH 7.65). Calcification rates of Goniopora sp. were unaffected by the examined variables. Calcification rates of H. reinboldii were significantly faster in Tallon than in Shell Island individuals, and Tallon Island individuals calcified faster in the high variability pH 8.05 treatment compared with all others. Geochemical proxies for carbonate chemistry within the calcifying fluid (cf) of both species indicated that only mean seawater pH influenced pHcf. pH treatments had no effect on proxies for Ωcf. These limited responses to extreme pH treatments demonstrate that some calcifying taxa may be capable of maintaining constant rates of calcification under ocean acidification by actively modifying Ωcf.

Continue reading ‘Resistance of corals and coralline algae to ocean acidification: physiological control of calcification under natural pH variability’

Carbonate system distribution, anthropogenic carbon and acidification in the western tropical South Pacific (OUTPACE 2015 transect) (update)

The western tropical South Pacific was sampled along a longitudinal 4000km transect (OUTPACE cruise, 18 February, 3 April 2015) for the measurement of carbonate parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago (MA) and the western part of the South Pacific gyre (WGY). This paper reports this new dataset and derived properties: pH on the total scale (pHT) and the CaCO3 saturation state with respect to aragonite (Ωara). We also estimate anthropogenic carbon (CANT) distribution in the water column using the TrOCA method (Tracer combining Oxygen, inorganic Carbon and total Alkalinity). Along the OUTPACE transect a deeper penetration of CANT in the intermediate waters was observed in the MA, whereas highest CANT concentrations were detected in the subsurface waters of the WGY. By combining our OUTPACE dataset with data available in GLODAPv2 (1974–2009), temporal changes in oceanic inorganic carbon were evaluated. An increase of 1.3 to 1.6µmolkg−1a−1 for total inorganic carbon in the upper thermocline waters is estimated, whereas CANT increases by 1.1 to 1.2µmolkg−1a−1. In the MA intermediate waters (27kgm−3 < σθ < 27.2kgm−3) an increase of 0.4µmolkg−1a−1 CANT is detected. Our results suggest a clear progression of ocean acidification in the western tropical South Pacific with a decrease in the oceanic pHT of up to −0.0027a−1 and a shoaling of the saturation depth for aragonite of up to 200m since the pre-industrial period.

Continue reading ‘Carbonate system distribution, anthropogenic carbon and acidification in the western tropical South Pacific (OUTPACE 2015 transect) (update)’

Trophic functioning of macrobenthic fauna in a tropical acidified Bornean estuary (Southeast Asia)

The trophic structure of a community is used to infer ecosystem functioning (e.g. energy transfer and nutrient cycling). Here the trophic structure of the benthic infaunal and epifaunal communities in the Brunei Estuary are characterized, and their distribution along an estuarine pH gradient is analyzed using univariate and multivariate techniques. This analysis revealed that surface deposit feeders (e.g., polychaetes) were numerically dominant within the infaunal communities whereas in the epifaunal communities filter feeders (e.g., bivalves) were highly abundant. Species richness for almost all trophic groups increased toward the lower estuary, except for omnivores in the epifaunal communities, which decreased markedly. Both Analysis of Variance (ANOVA) and Analysis of Similarities (ANOSIM) detected significant differences in the density of respective trophic groups among stations. Within infaunal communities, both Biological and Environmental procedure (BIO-ENV) and Canonical Correspondence Analysis (CCA) showed that trophic shifts were associated with environmental gradients. Surface-deposit feeders and omnivores were the most abundant macrobenthos of the upper estuary characterized by low salinity, low pH, and a higher percentage of mud particles. The proportion of filter feeders and carnivores increased with salinity/pH and sand. A more uniform distribution of trophic structure was found in the lower estuary, with high salinity and pH over sandy habitat. In contrast, within epifaunal trophic groups, the percentage of surface deposit feeders and omnivores declined, but filter feeders remarkably increased toward the sea. The proportion of carnivores remained similar at all stations. Non-Metric Multidimensional Scaling (nMDS) ordination for epifaunal trophic groups clearly demarcated higher salinity/pH stations from lower salinity/pH stations, suggesting different trophic compositions along the estuarine pH gradient.

Continue reading ‘Trophic functioning of macrobenthic fauna in a tropical acidified Bornean estuary (Southeast Asia)’

High-resolution time-series reveals seasonal patterns of planktonic fungi at a temperate coastal ocean site (Beaufort, North Carolina, USA)

There is a growing awareness of the ecological and biogeochemical importance of fungi in coastal marine systems, while highly diverse fungi have been discovered in these marine systems, still little is known about their seasonality and associated drivers in coastal waters. Here, we examined fungal communities over three years of weekly samples at a dynamic, temperate coastal site (Piver’s Island Coastal Observatory (PICO), Beaufort NC USA). Fungal 18S rRNA gene abundance, OTU richness and Shannon’s diversity exhibited prominent seasonality. Fungi 18S rRNA gene copies peak in abundance during the summer and fall, with positive correlations with chlorophyll a, SiO4 and oxygen saturation. Diversity (measured using Internal Transcribed Spacer: ITS libraries) was highest during winter and lowest during summer; it was linked to temperature, pH, chlorophyll a, insolation, salinity, and DIC. Fungal community ITS libraries were dominated throughout the year by Ascomycota with contributions from Basidiomycota, Chytridiomycota and Mucoromycotina, with seasonal patterns linked to water temperature, light, and the carbonate system. Network analysis revealed that while co-occurrence and exclusion existed within fungal network, exclusion dominated the fungi and phytoplankton network, in contrast with reported pathogenic and nutritional interactions between marine phytoplankton and fungi. Compared with the seasonality of bacterial community in the same samples, the timing, extent and associated environmental variables for fungi community are unique. These results highlighted the fungal seasonal dynamics in coastal water and improve our understanding of the ecology of planktonic fungi.

Continue reading ‘High-resolution time-series reveals seasonal patterns of planktonic fungi at a temperate coastal ocean site (Beaufort, North Carolina, USA)’


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