Archive for December, 2011

West Coast shellfish farms impacted by ocean acidification

West Coast shellfish growers have learned to work around upwellings of corrosive waters and save the lives of their bivalve stocks.

Increased levels of carbon dioxide, or CO2, in the atmosphere are changing the chemistry of the oceans, making it more acidic. The CO2 surge stems mostly from coal and, to a lesser degree, oil-fired power plants. The resulting off kilter acidity reduces carbonate, the mineral building block of shells, skeletons and corals.

In 2005, oystermen first noticed failures in natural sets in Willipa Bay in southern Puget Sound, followed by failures at two of four of the region’s major shellfish hatcheries.

Continue reading ‘West Coast shellfish farms impacted by ocean acidification’

Community shifts and productivity changes in the Southern Ocean

The Southern Ocean exerts an exceptionally large influence on the marine carbon cycle and likely played a key role in glacial-interglacial atmospheric CO2 transitions. CO2-related changes in environmental conditions, both directly through ocean seawater acidification and indirectly via increasing thermal stratification, are expected to be particularly pronounced in high latitudes and hence provide the possibility for strong feedbacks on atmospheric CO2. Despite these implications, little information is currently available on the potential CO2 sensitivity of Southern Ocean phytoplankton.

Continue reading ‘Community shifts and productivity changes in the Southern Ocean’

Ocean acidification and the future of native oysters in California estuaries

Ocean acidification and the future of native oysters in california estuaries

Seminar by Eric Sanford, Bodega Marine Laboratory, UC Davis

Continue reading ‘Ocean acidification and the future of native oysters in California estuaries’

Some species tolerate ocean acidification

Increasing carbon dioxide levels lead to rising ocean acidity, which can harm corals and many other species of ocean life. Acidification causes calcium carbonate, which corals usually need to build skeletons, to dissolve. “Every day, ocean acidification is taking up the weight of 6 million midsize cars’ worth of carbon, said Nina Keul, a graduate student at the Alfred Wegener Institute for Polar and Marine Research in Germany during a 7 December press conference at the AGU Fall Meeting.

Continue reading ‘Some species tolerate ocean acidification’

Harry Elderfield gave the Cesare Emiliani lecture at AGU 2011

The Cesare Emiliani Lecture honors the memory of Cesare Emiliani. It recognizes individuals who have made outstanding scientific contributions to our understanding of past oceans and climates.

Professor Harry Elderfield, University of Cambridge, gave this year’s lecture in recognition of his outstanding contribution to the development and use of paleoproxies, including ocean acidification. His presentation, “What a Single Celled Organism Can Tell Us About Climate History: A Status Report On Paleocean Proxies With Examples” was given at the 2011 Fall AGU meeting.

Continue reading ‘Harry Elderfield gave the Cesare Emiliani lecture at AGU 2011’

Ocean Acidification Presentation and Roundtable Discussion – Jan. 9, 2012

Acclaimed University of Alaska Fairbanks researcher Jeremy Mathis will be in Dillingham on January 9th, 2012.  He will be presenting his research findings on ocean acidification and moderators will lead a discussion with the community on what the changing oceans mean for a fishing community such as Dillingham.

Continue reading ‘Ocean Acidification Presentation and Roundtable Discussion – Jan. 9, 2012’

Assessing the magnitude of anthropogenic ocean acidification using the boron isotopic composition of corals and coralline algae

Gavin Foster, Toby Tyrrell, Dr Branwen Williams (Claremont Colleges, US), Dr Justin Ries (University of North Carolina, US)

Rationale

Global warming is not the only consequence of rising levels of carbon dioxide (CO2) in the atmosphere. Half of human emissions of CO2 are mixed into the ocean creating carbonic acid, which raises the hydrogen ion (H+) concentration and causes the oceans to become more acidic (so far, a pH drop of ~0.1 unit). This has resulted in a significant reorganisation of the ocean carbonate system, causing the concentration of CO3=, and hence the saturation state of calcium carbonate (CaCO3), to drop. Determining exactly how marine organisms that build their skeletons from CaCO3, such as corals, are impacted by this change is imperative, particularly since by the end of the 21st century pH is expected to drop by a further 0.3-0.5 units as the oceans continue to absorb humanity’s growing emissions of CO2. One way to improve our understanding of how marine calcifiers will be affected by future ocean acidification is to reconstruct how they have already responded to historic acidification (e.g. De’ath et al., 2009). However, the utility of this approach is limited at present because seawater pH measurements are restricted to the last 20 years or so. The aim of this proposal is to use the boron isotope-pH proxy as a means to directly quantify ocean acidification over the recent past (ca. 100 yrs) for several regions deemed particularly high risk (e.g. the high latitudes)

Continue reading ‘Assessing the magnitude of anthropogenic ocean acidification using the boron isotopic composition of corals and coralline algae’

Ocean acidification (video, in French)

The recent article by Frommel et al. was covered in today’s edition of the news programme on the French TV channel France 2.

Continue reading ‘Ocean acidification (video, in French)’

Temperature and pCO2 effect on the bioaccumulation of radionuclides and trace elements in the eggs of the common cuttlefish, Sepia officinalis

The increasing release of CO2 by human activities leads to ocean acidification and global warming. Both those consequences (i.e., increase in seawater pCO2 and temperature) may drastically affect the physiology of marine organisms. The effects of low pH and elevated temperature on the bioaccumulation of radionuclides (241Am, 134Cs) and trace elements (60Co, 54Mn or 75Se) were studied during the embryonic development of the common cuttlefish Sepia officinalis. The lowered accumulation of essential 60Co and 54Mn with decreasing pH was larger at 16 °C than at 19 °C. Se was not detected in the embryo whereas it penetrated through the eggshell, suggesting that an alternative pathway ensures the supply of this essential metal for the embryo. 241Am was totally retained by the eggshell irrespective of pH and temperature. Finally, the amount of Cs found in the peri-vitelline fluid increased with decreasing pH likely because of an enhanced swelling of the cuttlefish egg under elevated CO2.

Continue reading ‘Temperature and pCO2 effect on the bioaccumulation of radionuclides and trace elements in the eggs of the common cuttlefish, Sepia officinalis’

The evolution of mid Paleocene – early Eocene coral communities: how to survive during rapid global warming

Today, diverse communities of zooxanthellate corals thrive, but do not build reef, under a wide range of environmental conditions. In these settings they inhabit natural bottom communities, sometimes forming patch-reefs, coral carpets and knobs. Episodes in the fossil record, characterized by limited coral-reef development but widespread occurrence of coral-bearing carbonates, may represent the fossil analogues of these non-reef building, zooxanthellate coral communities. If so, the study of these corals could have valuable implications for paleoenvironmental reconstructions. Here we focus on the evolution of early Paleogene corals as a fossil example of coral communities mainly composed by zooxanthellate corals (or likely zooxanthellate), commonly occurring within carbonate biofacies and with relatively high diversity but with a limited bioconstructional potential as testified by the reduced record of coral reefs. We correlate changes of bioconstructional potential and community compositions of these fossil corals with the main ecological/environmental conditions at that time. The early Paleogene greenhouse climate was characterized by relatively short pulses of warming with the most prominent occurring at the Paleocene-Eocene boundary (PETM event), associated with high weathering rates, nutrient fluxes, and pCO2 levels. A synthesis of coral occurrences integrated with our data from the Adriatic Carbonate Platform (SW Slovenia) and the Minervois region (SW France), provide evidence for temporal changes in the reef-building capacity of corals associated with a shift in community composition towards forms adapted to tolerate deteriorating sea-water conditions. During the middle Paleocene coral-algal patch reefs and barrier reefs occurred from shallow-water settings, locally with reef-crest structures. A first shift can be traced from middle Paleocene to late Paleocene, with small coral-algal patch reefs and coral-bearing mounds development in shallow to intermediate water depths. In these mounds corals were highly subordinated as bioconstructors to other groups tolerant to higher levels of trophic resources (calcareous red algae, encrusting foraminifera, microbes, and sponges). A second shift occurred at the onset of the early Eocene with a further reduction of coral framework-building capacity. These coral communities mainly formed knobs in shallow-water, turbid settings associated with abundant foraminiferal deposits. We suggest that environmental conditions other than high temperature determined a combination of interrelated stressors that limited the coral-reef construction. A continuous enhancement of sediment load/nutrients combined with geochemical changes of ocean waters likely displaced corals as the main bioconstructors during the late Paleocene-early Eocene times. Nonetheless, these conditions did not affect the capacity of some corals to colonize the substrate, maintain biodiversity, and act as locally important carbonate-sediment producers, suggesting broad environmental tolerance limits of various species of corals. The implications of this study include clues as to how both ancient and modern zooxanthellate corals could respond to changing climate.

Continue reading ‘The evolution of mid Paleocene – early Eocene coral communities: how to survive during rapid global warming’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,417,456 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book

Archives