June 2016 - Page 2 of 6 - Ocean Acidification

Archive for June, 2016

A popular seafood is in danger because of one key change in the water

Published 21 June 2016 Media coverage Closed

Mussels, the popular shellfish staple, are growing thinner shells, which could put them at great risk.

In a study published June 15 in the Proceedings of the Royal Society B, researchers looked into differences in shell thickness among California mussels over time.

They found that compared to mussel shells found today in the Pacific Ocean, the ones from 1,000 years ago were 27% thicker, while ones from the 1970s were 33% thicker.

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Scienziati di chiara fama e nuovi progetti, i “vents” di Ischia sono un riferimento mondiale (in Italian)

Published 21 June 2016 Web sites and blogs Closed

Nell’autunno 2014, tutto il mondo scientifico scoprì che NEL MARE DI ISCHIA, oltre a quello già notissimo sotto al Castello Aragonese, erano presenti ALTRI QUATTRO VENTS, ovvero siti subacquei caratterizzati da emissioni di anidride carbonica. Accadde quando sul notiziario della Società Internazionale di Biologia Marina fu pubblicata una comunicazione di MARIA CRISTINA GAMBI del Laboratorio di Ecologia del Benthos della Stazione Zoologica di Napoli, che presentava quegli altri “possibili laboratori naturali per lo studio dell’acidificazione e cambiamento climatico a mare”. La notizia suscitò subito un notevole interesse, ma nessuno avrebbe potuto immaginare allora che quell’attenzione si sarebbe tradotta in tanto significative collaborazioni come quelle che si sono andate poi concretizzando. Anche nelle ultime ore, perchè è di ieri la notizia di un nuovo progetto della TOTAL FOUNDATION relativo a quei siti, mentre è in pieno svolgimento il progetto finanziato dal NATIONAL GEOGRAPHIC AMERICA e prosegue la partnership con la STANFORD UNIVERSITY.

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Awareness of climate change and sustainable development among undergraduates from two selected universities in Oyo State, Nigeria

Published 21 June 2016 Science Closed
Tags: education

This study investigated awareness of climate change and sustainable development among undergraduates in two universities: University of Ibadan, Ibadan and Ladoke Akintola University of Technology, Ogbomoso in Oyo Stateof Nigeria. This was aimed at increasing the knowledge of undergraduates on climate change and sustainable development. The study adopted a survey design. The population for the study consisted of 300 hundred undergraduates in University of Ibadan, Ibadan and Ladoke Akintola University of Technology, Ogbomoso in Oyo State, Nigeria. The students were selected using purposively random sampling technique. A 45-item each with Likert type response format titled ‘’Awareness of Climate Change and Sustainable Development among Undergraduates Students’’tagged ACCSDUS were administered. Data obtained were analyzed using simple percentages and t-test.The results showed that undergraduates possessed high level of awareness on the concept of climate change, have access to the sources of information and factors of personal experience, public sources and education greatly influence their awareness. The results further showed that there was no significant difference in the level of climate change and sustainable development awareness in term of gender (t= 0.733 > 0.05). There is a significant difference in the level of awareness of undergraduates on the concept of climate change based on school ownership (t= 0.013 <0.05). The study concluded that climate change education should be structured and embedded in the curricula of schools at all levels and that training, re-training, empowerment or enlightenment of the public and stakeholders in climate change should be carried out without bias, discrimination or marginalization of any form.

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The measurement of pH in saline and hypersaline media at sub-zero temperatures: characterization of Tris buffers

Published 21 June 2016 Science Closed
Tags: chemistry, methods

Highlights

The pH_T of the Tris-HCl buffer system in synthetic seawater and synthetic seawater-based brines was measured with the Harned cell to the freezing point of the synthetic solutions.
The measured pH_T of the common equimolal and a non-equimolal buffer variants was consistent with the stoichiometric dissociation equilibrium of Tris-H⁺.
The measurement of pH will now be facilitated at below-zero temperatures, such as in sea ice brines.

Abstract

The pH on the total proton scale of the Tris-HCl buffer system (pH_Tris) was characterized rigorously with the electrochemical Harned cell in salinity (S) 35 synthetic seawater and S = 45 – 100 synthetic seawater-derived brines at 25 and 0°C, as well as at the freezing point of the synthetic solutions (–1.93°C at S = 35 to –6°C at S = 100). The electrochemical characterization of the common equimolal Tris buffer [R_Tris = m_Tris/m_{Tris ‐ H⁺} = 1.0, with m_Tris = m_{Tris ‐ H⁺} = 0.04 mol kg_H₂O^‐1 = molality of the conjugate acid-base pair of 2-amino-2-hydroxymethyl-1,3-propanediol (Tris)] yielded pH_Tris values which increased with increasing salinity and decreasing temperature. The electrochemical characterization of a non-equimolal Tris buffer variant (R_Tris = 0.5, with m_Tris = 0.02 mol kg_H₂O^‐1 and m_{Tris − H⁺} = 0.04 mol kg_H₂O^‐1) yielded pH_Tris values that were consistently less alkaline by 0.3 pH unit than those of the equimolal Tris buffer. This is in agreement with the values derived from the stoichiometric equilibrium of the Tris-H⁺ dissociation reaction, described by the Henderson – Hasselbalch equation, pH_Tris = pK_Tris^⁎ + log R_Tris, with pK_Tris^⁎ = stoichiometric equilibrium dissociation constant of Tris-H⁺, equivalent to equimolal pH_Tris. This consistency allows reliable use of other R_Tris variants of the Tris-HCl buffer system within the experimental conditions reported here. The results of this study will facilitate the pH measurement in saline and hypersaline systems at below-zero temperatures, such as sea ice brines.

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A unique coral biomineralization pattern has resisted 40 million years of major ocean chemistry change

Published 20 June 2016 Science Closed
Tags: biological response, corals, morphology, paleo

Today coral reefs are threatened by changes to seawater conditions associated with rapid anthropogenic global climate change. Yet, since the Cenozoic, these organisms have experienced major fluctuations in atmospheric CO₂ levels (from greenhouse conditions of high pCO₂ in the Eocene to low pCO₂ ice-house conditions in the Oligocene-Miocene) and a dramatically changing ocean Mg/Ca ratio. Here we show that the most diverse, widespread, and abundant reef-building coral genus Acropora (20 morphological groups and 150 living species) has not only survived these environmental changes, but has maintained its distinct skeletal biomineralization pattern for at least 40 My: Well-preserved fossil Acropora skeletons from the Eocene, Oligocene, and Miocene show ultra-structures indistinguishable from those of extant representatives of the genus and their aragonitic skeleton Mg/Ca ratios trace the inferred ocean Mg/Ca ratio precisely since the Eocene. Therefore, among marine biogenic carbonate fossils, well-preserved acroporid skeletons represent material with very high potential for reconstruction of ancient ocean chemistry.

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Response of subtropical coastal sediment systems of Okinawa, Japan, to experimental warming and high pCO2

Published 20 June 2016 Science Closed
Tags: abundance, biological response, BRcommunity, community composition, laboratory, multiple factors, North Pacific, otherprocess, photosynthesis, primary production, prokaryotes, respiration, sediment, temperature

Increasing seawater temperatures and CO2 levels associated with climate change affect the shallow marine ecosystem function. In this study, the effects of elevated seawater temperature and partial pressure of CO2 (pCO2) on subtropical sediment systems of mangrove, seagrass, and coral reef lagoon habitats of Okinawa, Japan, were examined. Sediment and seawater from each habitat were exposed to four pCO2-temperature treatments, including ambient pCO2- ambient temperature, ambient pCO2-high temperature (ambient temperature + 4°C), high pCO2 (936 ppm)-ambient temperature, and high pCO2-high temperature. Parameters including primary production, nutrient flux, pigment content, photosynthetic community composition, and bacterial abundance were examined. Neither high temperature nor high pCO2 alone impacted mangrove and seagrass sediment primary production significantly (Tukey’s test, P > 0.05). However, the combined stress significantly (Tukey’s test, P < 0.01) increased primary production in these two habitats. In sediments from the coral reef lagoon, single and combined stress treatments induced a shift from heterotrophy to autotrophy. Significant increases in net primary production (Tukey’s test, P < 0.01), and gross primary production (Tukey’s test, P < 0.05) under the combined stress suggested that benthic microalgae in mangrove and seagrass sediments were more responsive to high temperature and pCO2 conditions than those in coral reef lagoon sediments. Additionally, combined stress significantly increased the sediment chlorophyll a content (Tukey’s test, P < 0.05) in all habitats. These increases were associated with increased net primary production, indicating that combined stress stimulates primary production activity by the photosynthetic benthic microalgae in all habitats. Diatom activity increased, as silicate uptake increased in all habitats. Microbial abundance significantly increased under the combined stress treatment (Tukey’s test, P < 0.01), but did not exceed autotrophic activity. Respiration did not change significantly in any of the three habitats (Tukey’s test, P > 0.05) under the combined stress, suggesting that heterotrophic processes were less affected by the combined stress than autotrophic processes. In summary, mangrove and seagrass sediments minimize the negative impacts of elevated temperature and pCO2 via increased primary production and carbon storage. Lagoonal sediments also act as a carbon sink under temperature and ocean acidification stress.

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Seawater pH, and not inorganic nitrogen source, affects pH at the blade surface of Macrocystis pyrifera: implications for responses of the giant kelp to future oceanic conditions

Published 20 June 2016 Science Closed
Tags: algae, biological response, chemistry, laboratory, physiology

Ocean acidification (OA), the ongoing decline in seawater pH, is predicted to have wide-ranging effects on marine organisms and ecosystems. For seaweeds, the pH at the thallus surface, within the diffusion boundary layer (DBL), is one of the factors controlling their response to OA. Surface pH is controlled by both the pH of the bulk seawater and by the seaweeds’ metabolism: photosynthesis and respiration increase and decrease pH within the DBL (pH_DBL), respectively. However, other metabolic processes, especially the uptake of inorganic nitrogen (N_i; NO₃⁻ and NH₄⁺) may also affect the pH_DBL. Using Macrocystis pyrifera, we hypothesized that (1) NO₃⁻ uptake will increase the pH_DBL, whereas NH₄⁺ uptake will decrease it, (2) if NO₃⁻ is co-transported with H⁺, increases in pH_DBL would be greater under an OA treatment (pH = 7.65) than under an ambient treatment (pH = 8.00), and (3) decreases in pH_DBL will be smaller at pH 7.65 than at pH 8.00, as higher external [H⁺] might affect the strength of the diffusion gradient. Overall, N_i source did not affect the pH_DBL. However, increases in pH_DBL were greater at pH 7.65 than at pH 8.00. CO₂ uptake was higher at pH 7.65 than at pH 8.00, whereas HCO₃⁻ uptake was unaffected by pH. Photosynthesis and respiration control pH_DBL rather than N_i uptake. We suggest that under future OA, Macrocystis pyrifera will metabolically modify its surface micro-environment such that the physiological processes of photosynthesis and N_i uptake will not be affected by a reduced pH.

Continue reading ‘Seawater pH, and not inorganic nitrogen source, affects pH at the blade surface of Macrocystis pyrifera: implications for responses of the giant kelp to future oceanic conditions’

Interactive effects of ocean acidification and neighboring corals on the growth of Pocillopora verrucosa

Published 20 June 2016 Science Closed
Tags: biological response, communityMF, corals, growth, laboratory, morphology, South Pacific

The physical and chemical environment around corals, as well as their physiology, can be affected by interactions with neighboring corals. This study employed small colonies (4 cm diameter) of Pocillopora verrucosa and Acropora hyacinthus configured in spatial arrays at 7 cm s⁻¹ flow speed to test the hypothesis that ocean acidification (OA) alters interactions among them. Interaction effects were quantified for P. verrucosa using three measures of growth: calcification (i.e., weight), horizontal growth, and vertical growth. The study was carried out in May–June 2014 using corals from 10 m depth on the outer reef of Moorea, French Polynesia. Colonies of P. verrucosa were placed next to conspecifics or heterospecifics (A. hyacinthus) in arrangements of two or four colonies (pairs and aggregates) that were incubated at ambient and high pCO₂ (~1000 µatm) for 28 days. There was an effect of pCO₂, and arrangement type on multivariate growth (utilizing the three measures of growth), but no interaction between the main effects. Conversely, arrangement and pCO₂ had an interactive effect on calcification, with an overall 23 % depression at high pCO₂ versus ambient pCO₂ (i.e., pooled among arrangements). Within arrangements, there was a 34–45 % decrease in calcification for solitary and paired conspecifics, but no effect in conspecific aggregates, heterospecific pairs, or heterospecific aggregates. Horizontal growth was negatively affected by pCO₂ and arrangement type, while vertical growth was positively affected by arrangement type. Together, our results show that conspecific aggregations can mitigate the negative effects of OA on calcification of colonies within an aggregation.

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Effects of ocean and coastal acidification on stressor responses in estuarine organisms and reef-building corals (job opportunity)

Published 20 June 2016 Jobs Closed

Project number: GED-06-16-2016-02
Lab/Center/Office: NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
Division: GULF ECOLOGY DIVISION
Branch: BIOLOGICAL EFFECTS AND POPULATION RESPONSE BRANCH

Brief description of research project: Research focuses on determining how changes in coastal water chemistry from ocean acidification and nutrient enrichment influence stressor responses in estuarine organisms and reef-building corals under controlled laboratory conditions. The project will investigate the interactive effects of projected high levels of pC02 and selected land-based stressors on genomic, biochemical, cellular and organismal level responses in selected species. The post-doc will develop and utilize exposure and testing systems and various biological response endpoints to determine sensitive species and life stages of estuarine invertebrates, fish and corals. The post doc will investigate how changes in carbonate chemistry, dissolved oxygen, and other water quality parameters affect calcification and other genomic and cellular responses to allow a mechanistic interpretation of species sensitivity and to facilitate predictive model development.

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Environmental carbonate chemistry selects for phenotype of recently isolated strains of Emiliania huxleyi

Published 17 June 2016 Science Closed
Tags: Antarctic, biological response, calcification, chemistry, field, laboratory, North Atlantic, otherprocess, phytoplankton

Coccolithophorid algae, particularly Emiliania huxleyi, are prolific biomineralisers that, under many conditions, dominate communities of marine eukaryotic plankton. Their ability to photosynthesise and form calcified scales (coccoliths) has placed them in a unique position in the global carbon cycle. Contrasting reports have been made with regards to the response of E. huxleyi to ocean acidification. Therefore, there is a pressing need to further determine the fate of this key organism in a rising CO₂ world. In this paper, we investigate the phenotype of newly isolated, genetically diverse, strains of E. huxleyi from UK Ocean Acidification Research Programme (UKOA) cruises around the British Isles, the Arctic, and the Southern Ocean. We find a continuum of diversity amongst the physiological and photosynthetic parameters of different strains of E. huxleyi morphotype A under uniform, ambient conditions imposed in the laboratory. This physiology is best explained by adaptation to carbonate chemistry in the former habitat rather than being prescribed by genetic fingerprints such as the coccolithophore morphology motif (CMM). To a first order, the photosynthetic capacity of each strain is a function of both aqueous CO₂ availability, and calcification rate, suggestive of a link between carbon concentrating ability and calcification. The calcification rate of each strain is related linearly to the natural environmental [CO₃²⁻] at the site of isolation, but a few exceptional strains display low calcification rates at the highest [CO₃²⁻] when calcification is limited by low CO₂ availability and/or a lack of a carbon concentrating mechanism. We present O₂-electrode measurements alongside coccolith oxygen isotopic composition and the uronic acid content (UAC) of the coccolith associated polysaccharide (CAP), that act as indirect tools to show the differing carbon concentrating ability of the strains. The environmental selection revealed amongst our recently isolated strain collection points to the future outcompetition of the slow growing morphotypes B/C and R (which also lack a carbon concentrating mechanism) by more rapidly photosynthesising, and lightly calcified strains of morphotype A but with their rate of calcification highly dependent on the surface ocean saturation state. The mechanism of E. huxleyi response to carbonate chemistry in the modern ocean appears to be selection from a continuum of phenotype.

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How ocean acidification impacts Florida’s ecosystems

Published 17 June 2016 Web sites and blogs Closed

Dr. Kimberly Yates will be a panelist at an ocean acidification roundtable we are hosting in Miami this week. There, she will join other scientists, Florida elected officials and local businesspeople in discussing what ocean acidification has in store for Florida’s marine life and its coastal communities. Follow the meeting on Twitter via #FL_OA on Friday, June 17!

OC: Your research focuses on several marine habitats in Florida: coral reefs, estuaries and mangroves. How are they coping with ocean acidification?

Dr. Yates: Most of what we know about how ocean acidification is affecting these environments comes from experimental research. We know some marine organisms will be negatively impacted, and some may benefit. For example, some species that form their skeletons and shells from minerals made of calcium carbonate, like corals and some shellfish, are negatively impacted. Ocean acidification slows the rate at which they grow their skeletons and shells, and can also cause calcium carbonate minerals to dissolve.

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