Archive for April, 2013

UCSB biologists find contradictory new organism with unique function

Researchers in the Department of Ecology, Evolution and Marine Biology have discovered a line of marine organisms that actually increase their calcification, or creation of new shells, in ocean waters with dropping pH levels, despite prior evidence indicating that ocean acidification leads to decreased calcification and the dissolving of marine life shells.

UCSB professor Debora Iglesias-Rodriguez and postdoctoral researcher Bethan Jones — who is now working with Rutgers University — led a study which they found the unicellular marine coccolithophore Emiliania huxleyi still managed to develop shells when exposed to waters with high carbon dioxide levels. Such evidence runs contrary to previous scientific thought which theorized that water affected by ocean acidification lead to the dissolving of shells and decreased calcification.

Continue reading ‘UCSB biologists find contradictory new organism with unique function’

Cascading effects of ocean acidification in a rocky subtidal community

Temperate marine rocky habitats may be alternatively characterized by well vegetated macroalgal assemblages or barren grounds, as a consequence of direct and indirect human impacts (e.g. overfishing) and grazing pressure by herbivorous organisms. In future scenarios of ocean acidification, calcifying organisms are expected to be less competitive: among these two key elements of the rocky subtidal food web, coralline algae and sea urchins. In order to highlight how the effects of increased pCO2 on individual calcifying species will be exacerbated by interactions with other trophic levels, we performed an experiment simultaneously testing ocean acidification effects on primary producers (calcifying and non-calcifying algae) and their grazers (sea urchins). Artificial communities, composed by juveniles of the sea urchin Paracentrotus lividus and calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea var stricta, Dictyota dichotoma) macroalgae, were subjected to pCO2 levels of 390, 550, 750 and 1000 µatm in the laboratory. Our study highlighted a direct pCO2 effect on coralline algae and on sea urchin defense from predation (test robustness). There was no direct effect on the non-calcifying macroalgae. More interestingly, we highlighted diet-mediated effects on test robustness and on the Aristotle’s lantern size. In a future scenario of ocean acidification a decrease of sea urchins’ density is expected, due to lower defense from predation, as a direct consequence of pH decrease, and to a reduced availability of calcifying macroalgae, important component of urchins’ diet. The effects of ocean acidification may therefore be contrasting on well vegetated macroalgal assemblages and barren grounds: in the absence of other human impacts, a decrease of biodiversity can be predicted in vegetated macroalgal assemblages, whereas a lower density of sea urchin could help the recovery of shallow subtidal rocky areas affected by overfishing from barren grounds to assemblages dominated by fleshy macroalgae.

Continue reading ‘Cascading effects of ocean acidification in a rocky subtidal community’

Calcification response to climate change in the Pliocene?

As a result of anthropogenic pCO2 increases future oceans are growing warmer and lower in pH and oxygen, conditions that are likely to impact planktic communities. Past intervals of elevated and changing pCO2 and temperatures can offer a glimpse into the response of marine calcifying plankton to changes in surface oceans under conditions similar to those projected for the future. Here we present new records of planktic foraminiferal and coccolith calcification from Deep Sea Drilling Project Site 607 (mid North Atlantic) and Ocean Drilling Program Site 999 (Caribbean Sea) from the Pliocene, the last time that pCO2 was similar to today, and extending through a global cooling event into the Intensification of Northern Hemisphere Glaciation (3.3 to 2.6 million years ago). Test weights of both surface-dwelling foraminifera Globigerina bulloides and thermocline-dwelling foraminifera Globorotalia puncticulata vary, with a potential link to regional temperature variation in the North Atlantic, whereas in the tropics Globigerinoides ruber test weight remains stable. In contrast, reticulofenestrid coccoliths show a narrowing size range and a decline in the largest lith diameters over this interval. Our results suggest no major changes in plankton calcification during the high pCO2 Pliocene or during the transition into an icehouse world.

Continue reading ‘Calcification response to climate change in the Pliocene?’

Marine algae show resilience to carbon dioxide emissions

A type of marine algae could become bigger as increasing carbon dioxide emissions are absorbed by the oceans, according to research led by scientists based at the National Oceanography Centre, Southampton (NOCS).

The study, published this month in PLoS ONE, investigated how a strain of the coccolithophore Emiliania huxleyi might respond if all fossil fuels are burned by the year 2100 – predicted to drive up atmospheric CO2 levels to over four times the present day. Specimens grown under this high CO2 scenario were compared with specimens grown under present day CO2 levels.

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Obama’s much-needed ocean plan falls short on warming, acidification

SAN FRANCISCO— The Obama administration released its National Ocean Policy Implementation Plan today, intended to strengthen ocean health and coordinate national management. The plan calls for actions aimed at improving ocean science, planning marine reserves and conservation, reducing risks from increased industrial activity in the Arctic, and bolstering the ocean economy. Missing in the plan are badly needed steps to reduce carbon pollution that’s plaguing oceans and rapidly transforming marine life.

Continue reading ‘Obama’s much-needed ocean plan falls short on warming, acidification’

Tasman Sea takes acid test

A new facility to detect increasing ocean acidification is currently monitoring carbon cycling in the Tasman Sea, off the south east coast of Australia.

The A$150,000 mooring with its suite of environmental sensors is one of three in Australia’s Integrated Marine Observing System (IMOS) that are included in the international network in which Australian scientists at CSIRO and the Australian Institute of Marine Science are playing a central role.

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Effects of seawater temperature and pH on the boring rates of the sponge Cliona celata in scallop shells

Warmer, more acidic water resulting from greenhouse gas emissions could influence ecosystem processes like bioerosion of calcifying organisms. Based on summer-maxima values (temperature = 26 °C; pH = 8.1) at a collection site in New York (40°56″ N, 72°30″ W), explants of the boring sponge Cliona celata Grant, 1826 were grown for 133 days on scallop shells in seawater ranging from current values to one scenario predicted for the year 2100 (T = 31 °C; pH = 7.8). High water temperature had little effect on sponge growth, survival, or boring rates. Lower pH slightly reduced sponge survival, while greatly influencing shell boring. At pH = 7.8, sponges bored twice the number of papillar holes and removed two times more shell weight than at pH = 8.1. Greater erosion resulted in weaker scallop shells. This study suggests that lower seawater pH may increase boring rates of C. celata in shellfish, with potentially severe implications for wild and farmed shellfish populations.

Continue reading ‘Effects of seawater temperature and pH on the boring rates of the sponge Cliona celata in scallop shells’

Production and carbonate dynamics of Halimeda incrassata (Ellis) Lamouroux altered by Thalassia testudinum Banks and Soland ex König

Ocean acidification poses a serious threat to a broad suite of calcifying organisms. Scleractinian corals and calcareous algae that occupy shallow, tropical waters are vulnerable to global changes in ocean chemistry because they already are subject to stressful and variable carbon dynamics at the local scale. For example, net heterotrophy increases carbon dioxide concentrations, and pH varies with diurnal fluctuations in photosynthesis and respiration. Few researchers, however, have investigated the possibility that carbon dioxide consumption during photosynthesis by non-calcifying photoautotrophs, such as seagrasses, can ameliorate deleterious effects of ocean acidification on sympatric calcareous algae. Naturally occurring variations in the density of seagrasses and associated calcareous algae provide an ecologically relevant test of the hypothesis that diel fluctuations in water chemistry driven by cycles of photosynthesis and respiration within seagrass beds create microenvironments that enhance macroalgal calcification. In Grape Tree Bay off Little Cayman Island BWI, we quantified net production and characterized calcification for thalli of the calcareous green alga Halimeda incrassata growing within beds of Thalassia testudinum with varying shoot densities. Results indicated that individual H. incrassata thalli were ~ 6% more calcified in dense seagrass beds. On an areal basis, however, far more calcium carbonate was produced by H. incrassata in areas where seagrasses were less dense due to higher rates of production. In addition, diel pH regimes in vegetated and unvegetated areas within the lagoon were not significantly different, suggesting a high degree of water exchange and mixing throughout the lagoon. These results suggest that, especially in well-mixed lagoons, carbonate production by calcareous algae may be more related to biotic interactions between seagrasses and calcareous algae than to seagrass-mediated changes in local water chemistry.

Continue reading ‘Production and carbonate dynamics of Halimeda incrassata (Ellis) Lamouroux altered by Thalassia testudinum Banks and Soland ex König’

Unikt experiment om havsförsurning (video; in Swedish)

Hur ser havet ut om hundra år och vilka marina växter och djur finns kvar? Just nu studerar ett 60-tal forskare försurningens effekter i Gullmarsfjorden, som del i en unik internationell forskningssatsning.
Bakom projektet BIOACID står Helmholtz Centre for Ocean research Kiel (GEOMAR).

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Panel: Ocean acidification threatening sea life here

PORT ANGELES — Acidification of the world’s oceans could have a profound effect on the North Olympic Peninsula, a panel of experts told Clallam County commissioners Monday.

Caused by carbon dioxide from the burning of fossil fuels, ocean acidification can destroy shells of crabs, clams, oysters and scores of creatures at the bottom of the food chain.

The Strait of Juan de Fuca, Puget Sound and outer coast of Washington are particularly vulnerable because acidic water is upwelled off the coast every spring and summer.

The state supports 42,000 jobs in the seafood industry.

Continue reading ‘Panel: Ocean acidification threatening sea life here’

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Ocean acidification in the IPCC AR5 WG II

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