Archive for January, 2014

Acidificación y depredadores invasores amenazan a las ostras (in Spanish)

spanish blog picLas ostras nativas Olimpia, que alguna vez fueron abundantes en la costa oeste, ahora están luchando por su supervivencia, ya que podrían enfrentarse a una doble amenaza por la acidificación del océano y los depredadores invasores, según una nueva investigación.

Investigadores del Laboratorio Marino Bodega, de la Universidad de California Davis, descubrieron que caracoles invasores comieron un 20% más de ostras juveniles cuando las ostras y los caracoles fueron criados bajo las condiciones oceánicas previstas para finales de este siglo. Los resultados enfatizan los peligros de los múltiples factores de estrés en los ecosistemas, sostiene Eric Sanford, profesor de Evolución y Ecología en la UC Davis y autor principal del estudio.
Continue reading ‘Acidificación y depredadores invasores amenazan a las ostras (in Spanish)’

Influence of sediment acidification and water flow on sediment acceptance and dispersal of juvenile soft-shell clams (Mya arenaria L.)

Although ocean acidification is expected to reduce carbonate saturation and yield negative impacts on open-ocean calcifying organisms in the near future, acidification in coastal ecosystems may already be affecting these organisms. Few studies have addressed the effects of sedimentary saturation state on benthic invertebrates. Here, we investigate whether sedimentary aragonite saturation (Ωaragonite) and proton concentration ([H+]) affect burrowing and dispersal rates of juvenile soft-shell clams (Mya arenaria) in a laboratory flume experiment. Two size classes of juvenile clams (0.5–1.5 mm and 1.51–2.5 mm) were subjected to a range of sediment Ωaragonite and [H+] conditions within the range of typical estuarine sediments (Ωaragonite 0.21–1.87; pH 6.8–7.8; [H+] 1.58 × 10− 8–1.51 × 10– 7) by the addition of varying amounts of CO2, while overlying water pH was kept constant ~ 7.8 (Ωaragonite ~ 1.97). There was a significant positive relationship between the percent of juvenile clams burrowed in still water and Ωaragonite and a significant negative relationship between burrowing and [H+]. Clams were subsequently exposed to one of two different flow conditions (flume; 11 cm s− 1 and 23 cm s− 1) and there was a significant negative relationship between Ωaragonite and dispersal, regardless of clam size class and flow speed. No apparent relationship was evident between dispersal and [H+]. The results of this study suggest that sediment acidification may play an important role in soft-shell clam recruitment and dispersal. When assessing the impacts of open-ocean and coastal acidification on infaunal organisms, future studies should address the effects of sediment acidification to adequately understand how calcifying organisms may be affected by shifting pH conditions.
Continue reading ‘Influence of sediment acidification and water flow on sediment acceptance and dispersal of juvenile soft-shell clams (Mya arenaria L.)’

One hundred-fold difference between perceived and actual levels of marine protection in New Zealand

Anthropogenic threats to the global marine environment are increasing, and the Convention of Biological Diversity has set a target of 10% global ocean protection by 2020. Social factors are an important component of coastal marine protected area and no-take marine reserve creation. In order to understand social factors influencing marine reserve creation in New Zealand, public surveys were conducted in 2005 and 2011 about marine protection and threats to the marine environment (Territorial Sea and Exclusive Economic Zone). These results are compared to an experts’ opinion survey of threats to the New Zealand marine environment, and actual marine protection levels. Generally, the New Zealand public identified similar New Zealand originated threats to the marine environment as those identified by experts, in contrast to expert identified global threats originating from climate change, which were minimally identified by the public. Experts identified that shallow, coastal waters were under greater threat than deep water habitats. On average, the New Zealand public thought that ~30% of New Zealand’s marine environment was protected by no-take marine reserves, and that 36% should be protected, while in fact only 0.3% is protected by no-take marine reserves. There is considerable potential for publicly driven marine protection initiatives in New Zealand with sufficient awareness, education, and outreach programs to better inform New Zealanders about actual marine protection levels. The results of this study are globally important, as similar knowledge gaps about marine environmental issues have been identified in the United States and the United Kingdom.
Continue reading ‘One hundred-fold difference between perceived and actual levels of marine protection in New Zealand’

Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease

Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.
Continue reading ‘Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease’

Las algas compiten entre ellas por sobrevivir a la acidificación del océano (in Spanish)

competing algaeA medida que el océano absorbe más dióxido de carbono de la atmósfera, el agua se vuelve más ácida, haciendo que algas coralinas costrosas y mariscos tengan dificultades para producir sus esqueletos y conchas (Europa Press).

La acidificación del océano provocada por el cambio climático global está alterando la biodiversidad marina, según concluye un estudio sobre la vida en las aguas costeras templadas del noreste del Océano Pacífico al mostrar una reversión de la dominancia competitiva entre especies de algas.
Continue reading ‘Las algas compiten entre ellas por sobrevivir a la acidificación del océano (in Spanish)’

New studies needed to predict how marine organisms may adapt to the future’s acidic oceans

The world’s oceans are becoming more acidic, changing in a way that hasn’t happened for millions of years. But will marine organisms from tiny coccolithophores to king crabs change along with the waters?

SF State Associate Professor of Biology Jonathon Stillman has joined with an international team of scientists in calling for more studies of how these plants and animals might adapt to ocean acidification. Beyond a short-term adjustment to acidic waters, adaptation involves heritable changes in a species brought about by natural selection.

Their article in the journal Trends in Ecology & Evolution offers “a way to move forward from people studying how organisms react to changes in the environment to being able to understand how they may evolve as the ocean changes,” Stillman said.
Continue reading ‘New studies needed to predict how marine organisms may adapt to the future’s acidic oceans’

Exploring aberrant bivalve shell ultrastructure and geochemistry as proxies for past sea water acidification

Throughout much of Earth’s history, marine carbonates have represented one of the most important geological archives of environmental change. Several pivotal events during the Phanerozoic, such as mass extinctions or hyperthermal events have recently been associated with ocean acidification. Nevertheless, well-defined geological proxies for past ocean acidification events are, at best, scarce. Here, experimental work explores the response of bivalve shell ultrastructure and isotope geochemistry (δ13C, δ18O and δ26 Mg) to stressful environments, in particular to sea water acidification. In this study, the common blue mussel, Mytilus edulis, was cultured (from early juvenile stages to one year of age) at four pH regimes (pHNBS 7.2 to pH 8.0). Shell growth rate and ultrastructure of mainly the calcitic portion of the shells were compared between experimental treatments. Specimens exposed to low pH environments show patches of disordered calcitic fibre orientation in otherwise well-structured shells. Furthermore, the electron backscatter diffraction analyses reveal that under acidified conditions, the c-axis of the calcite prisms exhibit a bi-modal or multi-modal distribution pattern. Similar shell disorder patterns have been reported from mytilids kept under naturally acidified sea water conditions. In contrast, we find at present no evidence that different pH regimes affect shell carbon, oxygen or magnesium isotope ratios. Based on these observations, it is proposed that: (i) stressful environments, in this case low sea water pH predictably affect bivalve biomineralization patterns; and (ii) these findings bear potential as a novel (petrographic) proxy for ancient sea water acidification. An assessment of the applicability of these data to well-preserved fossil shell material from selected time intervals requires additional work.
Continue reading ‘Exploring aberrant bivalve shell ultrastructure and geochemistry as proxies for past sea water acidification’

Increasing pCO2 correlates with low concentrations of intracellular dimethylsulfoniopropionate in the sea anemone Anemonia viridis

Marine anthozoans maintain a mutualistic symbiosis with dinoflagellates that are prolific producers of the algal secondary metabolite dimethylsulfoniopropionate (DMSP), the precursor of the climate-cooling trace gas dimethyl sulfide (DMS). Surprisingly, little is known about the physiological role of DMSP in anthozoans and the environmental factors that regulate its production. Here, we assessed the potential functional role of DMSP as an antioxidant and determined how future increases in seawater pCO2 may affect DMSP concentrations in the anemone Anemonia viridis along a natural pCO2 gradient at the island of Vulcano, Italy. There was no significant difference in zooxanthellae genotype and characteristics (density of zooxanthellae, and chlorophyll a) as well as protein concentrations between anemones from three stations along the gradient, V1 (3232 μatm CO2), V2 (682 μatm) and control (463 μatm), which indicated that A. viridis can acclimate to various seawater pCO2. In contrast, DMSP concentrations in anemones from stations V1 (33.23 ± 8.30 fmol cell−1) and V2 (34.78 ± 8.69 fmol cell−1) were about 35% lower than concentrations in tentacles from the control station (51.85 ± 12.96 fmol cell−1). Furthermore, low tissue concentrations of DMSP coincided with low activities of the antioxidant enzyme superoxide dismutase (SOD). Superoxide dismutase activity for both host (7.84 ± 1.37 U·mg−1 protein) and zooxanthellae (2.84 ± 0.41 U·mg−1 protein) at V1 was 40% lower than at the control station (host: 13.19 ± 1.42; zooxanthellae: 4.72 ± 0.57 U·mg−1 protein). Our results provide insight into coastal DMSP production under predicted environmental change and support the function of DMSP as an antioxidant in symbiotic anthozoans.
Continue reading ‘Increasing pCO2 correlates with low concentrations of intracellular dimethylsulfoniopropionate in the sea anemone Anemonia viridis’

Population trajectories for the Antarctic bivalve Laternula elliptica: identifying demographic bottlenecks in differing environmental futures

The world’s oceans are changing, and dramatic shifts have been documented in the Southern Ocean. The consequences of these shifts to coastal benthic organisms are difficult to predict at present, as ocean warming may increase primary production and food resources for benthic consumers, whilst OA may have negative impacts that differentially affect various species and life stages. A model was developed to investigate how different scenarios of change may influence population size of the Antarctic bivalve Laternula elliptica. The model describes potential implications of both pH and temperature change on survivorship and reproductive output of a population of this bivalve species in McMurdo Sound, Ross Sea. Implications of increases and decreases in mortality rate across different life stages of the population (early, mid and late) were assessed. Additionally, effects on energetic resource partitioning and dictating reproductive potential (RP) were also investigated. Significant declines in RP, due to increased basal metabolic demand, were associated with even relatively small changes in temperature and pH, resulting in populations declining to 25 % of the starting equilibrium density within 60 years. As L. elliptica is a pivotal species to the functionality of the Antarctic coastal benthic ecosystem, wide spread repercussions are expected if populations are impacted as the model predicts. Although further model development is required to explore the ecosystem implications of the population decline described in this paper, this work allows a better understanding of the consequences of change as soon as data on the direction and magnitude of the changes affecting Antarctic seas become available.
Continue reading ‘Population trajectories for the Antarctic bivalve Laternula elliptica: identifying demographic bottlenecks in differing environmental futures’

Calcium carbonate corrosivity in an Alaskan inland sea (update)

Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (Ω) to levels that are corrosive (i.e., Ω ≤ 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacial melt. Carbonate system data collected in May and September from 2009 through 2012 in Prince William Sound (PWS), a semienclosed inland sea located on the south-central coast of Alaska and ringed with fjords containing tidewater glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity. Initial limited sampling was expanded in September 2011 to span large portions of the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive Ω levels seen below the mixed layer over a portion of the sound, and (2) as point sources for surface plumes of glacial melt with corrosive Ω levels (Ω for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. CaCO3 corrosivity in glacial melt plumes is poorly reflected by pCO2 or pHT, indicating that either one of these carbonate parameters alone would fail to track Ω in PWS. The unique Ω and pCO2 conditions in the glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would rapidly exacerbate CaCO3 corrosivity in a positive feedback. The cumulative effects of glacial melt and air–sea gas exchange are likely responsible for the seasonal reduction of Ω in PWS, making PWS highly sensitive to increasing atmospheric CO2 and amplified CaCO3 corrosivity.
Continue reading ‘Calcium carbonate corrosivity in an Alaskan inland sea (update)’

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Ocean acidification in the IPCC AR5 WG II

OUP book