Archive for October, 2009

Ocean acidity may cause shellfish decline

U.S. scientists say they have discovered ocean acidification might be contributing to global shellfish declines.

Stony Brook University researchers said they’ve determined relatively minor increases in ocean acidity caused by elevated carbon dioxide concentrations can impede the growth and survival of hard clams, bay scallops and Eastern oysters.

The scientists at the university’s school of marine and atmospheric sciences said their research is among the first studies looking at the effect of ocean acidification on shellfish.
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Ocean acidification may contribute to global shellfish decline

Relatively minor increases in ocean acidity brought about by high levels of carbon dioxide have significant detrimental effects on the growth, development, and survival of hard clams, bay scallops, and Eastern oysters, according to researchers at Stony Brook University’s School of Marine and Atmospheric Sciences. In one of the first studies looking at the effect of ocean acidification on shellfish, Stephanie Talmage, PhD candidate, and Professor Chris Gobler showed that the larval stages of these shellfish species are extremely sensitive to enhanced levels of carbon dioxide in seawater. Their work will be published in the November issue of the journal Limnology and Oceanography and is now online at http://www.aslo.org/lo/toc/vol_54/issue_6/index.html.

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EPOCA will release a special introductory guide for policy advisers and decision makers, “Ocean Acidification – the facts”

A special introductory guide for policy advisers and decision makers

Release date: 10th December 2009

Copenhagen, December 2009, is when the world will wait to see how we will meet the greatest challenge of our generation – climate change. Copenhagen is where we will also release a ground-breaking new guide to ocean acidification – how the ocean is becoming progressively more acidic due to the carbon dioxide we emit.
With an overall message to dramatically cut our emissions of carbon dioxide the guide places the ocean centre stage. It shows in simple and clear words how our ocean is being driven towards unnaturally more acidic conditions and why this matters. It explains what this means now and in the future for all of us, and what is being done about it. For the first time an easy to understand guide on this most critical of issues will be simultaneously available in English, French, Spanish, Arabic and Chinese, with global distribution.
Continue reading ‘EPOCA will release a special introductory guide for policy advisers and decision makers, “Ocean Acidification – the facts”’

Ocean acidity

We have all heard about the burning of fossil fuels and climate change. Climate change, or as it is commonly referred to as “global warming” resulting from carbon dioxide and other greenhouse gas emissions, is real and impacting our world in a multitude of negative ways. We must act now to reduce these emissions.

While the focus is on controlling carbon dioxide emissions to mitigate climate change, there is another, perhaps more insidious, way carbon dioxide is affecting the environment, and we are beginning to see its effects. Yet we really never — or rarely — hear it mentioned. This problem is ocean acidification, the ongoing increase in the acidity of the Earth’s oceans caused by the uptake of carbon dioxide produced as a result of fossil fuel combustion. According to the National Oceanic and Atmospheric Administration, an increase of acidity of about 30 percent has occurred since the start of the industrial revolution.
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Coral ‘cryobank’ saves reef species

Should the Great Barrier Reef perish as a result of rising ocean temperatures and acidity levels, it appears scientists will have, at least, a small consolation prize.

The Zoological Society of London is planning the world’s first coral “cryobank”, which would preserve hundreds of samples of each species in liquid nitrogen.

Samples taken from the Great Barrier Reef would be included in the radical preservation effort, although none has so far been removed for this purpose.

For some marine scientists, however, the concept is deeply flawed since it fails to tackle the root of the problem — the feared obliteration of coral reefs by mid-century.
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Impacts of ocean acidification on large benthic foraminifers: Results from laboratory experiments

Ocean acidification has become recognized recently to be a major threat to calcifying organisms. Previous studies have reported that calcification rates of calcareous marine organisms (e.g., corals, foraminifers, coccolithophores, pteropods, mussels, and oysters) change in response to lowering pH levels even in waters oversaturated with respect to calcium carbonate. However, the impact of ocean acidification on large benthic foraminifers, which are major contributors to organic and inorganic carbon production in coral reefs, is still unclear. In this study, we cultured asexually-produced individuals of Marginopora kudakajimensis under four different pH conditions to examine the effects of lowering pH on their growth rates. Experimental results indicate that growth rate, measured by shell diameter, shell weight, and the number of chambers added, generally decreased with lowering pH after 10 weeks of culture. Shell weight was most closely dependent upon pH, suggesting that fossil shell weight can be more useful for reconstruction of paleo-pH changes. The relationship between the shell weight and shell size also showed significant differences among the four pH conditions. Between pH 8.3 and 7.7 (NBS scale), the tendency of the growth rate of M. kudakajimensis to decrease with pH was consistent with that of most other calcifying organisms. However, the calcification/growth rates at pH 7.9 and ~ 8.2 (present seawater value, control) were not significantly different, and other organisms also display a nonlinear response to elevated pCO2 at around this pH range. These results suggest that 1) they already may have experienced a reduction in growth in natural environments since pre-industrial times and 2) although the seawater CO2 system of reef water shows great variation, the calcification rate of these large foraminifers should remain at the present level at pH 7.9–8.2. However, at around pH 7.7, their calcification rate would decline steeply, which would probably preclude their survival.
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Modelling effects of geoengineering options in response to climate change and global warming: Implications for coral reefs

Climate change will have serious effects on the planet and on its ecosystems. Currently, mitigation efforts are proving ineffectual in reducing anthropogenic CO2 emissions. Coral reefs are the most sensitive ecosystems on the planet to climate change, and here we review modelling a number of geoengineering options, and their potential influence on coral reefs. There are two categories of geoengineering, shortwave solar radiation management and longwave carbon dioxide removal. The first set of techniques only reduce some, but not all, effects of climate change, while possibly creating other problems. They also do not affect CO2 levels and therefore fail to address the wider effects of rising CO2, including ocean acidification, important for coral reefs. Solar radiation is important to coral growth and survival, and solar radiation management is not in general appropriate for this ecosystem. Longwave carbon dioxide removal techniques address the root cause of climate change, rising CO2 concentrations, they have relatively low uncertainties and risks. They are worthy of further research and potential implementation, particularly carbon capture and storage, biochar, and afforestation methods, alongside increased mitigation of atmospheric CO2 concentrations.
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Sea urchin fertilization in a warm, acidified and high pCO2 ocean across a range of sperm densities

Marine invertebrate gametes are being spawned into an ocean simultaneously warming, acidifying and increasing in pCO2. Decreased pH/increased pCO2 narcotizes sperm indicating that acidification may impair fertilization, exacerbating problems of sperm limitation, with dire implications for marine life. In contrast, increased temperature may have a stimulatory effect, enhancing fertilization. We investigated effects of ocean change on sea urchin fertilization across a range of sperm densities. We address two predictions: 1) low pH/increased pCO2 reduces fertilization at low sperm density and 2) increased temperature enhances fertilization, buffering negative effects of acidification and increased pCO2. Neither prediction was supported. Fertilization was only affected by sperm density. Increased acidification and pCO2 did not reduce fertilization even at low sperm density and increased temperature did not enhance fertilization. It is important to identify where vulnerabilities lie across life histories and our results indicate that sea urchin fertilization is robust to climate change stressors. However, developmental stages may be vulnerable to ocean change.
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Global warming demonstration today

A global warming demonstration is scheduled for noon to 1:30 p.m. today at the Kincaid Park outdoor center, part of a synchronized global protest. The goal is to send a message to national and world leaders asking them to champion legislation on climate change and ocean acidification and to draft a strong international climate treaty in December in Copenhagen, according to organizers of the event.

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Future high CO2 in the intertidal may compromise adult barnacle Semibalanus balanoides survival and embryonic development rate

The effects of CO2-induced acidification on survival, shell mineralogy, embryonic development and the timing of larval release were investigated in the intertidal barnacle Semibalanus balanoides using an intertidal microcosm system. Compared to that in the control (CO2 = 344 ppm, pH = 8.07), adult survival was 22% lower in the high-CO2 treatment (CO2 = 922 ppm, pH = 7.70) and significant changes in the mineral structure of the adult shell were observed. Embryonic development rate was significantly slower in the high-CO2 treatment than in the control but still resembled ‘natural’ rates seen in populations found in similar locations. There was an estimated 19 d delay in development under high-CO2 conditions, which resulted in a 60% reduction in the number of nauplii reaching hatching stage at the time when over 50% of the control nauplii had hatched. We conclude that ocean acidification could potentially further compromise embryonic development in a species already stressed by temperature, which could in turn impact naupliar development and recruitment. S. balanoides, the adults of which live in a highly variable environment, has been shown to be detrimentally impacted by a chronic change in chemical conditions (pH lowered beyond the current range) over a crucial period in their life cycle. Under experimental high-CO2 conditions, some adults were able to survive and larvae were able to hatch. This may indicate that there is still potential for organisms to find suitable habitats and for populations to develop and survive.
Continue reading ‘Future high CO2 in the intertidal may compromise adult barnacle Semibalanus balanoides survival and embryonic development rate’


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