Energy metabolism and regeneration impaired by seawater acidification in the infaunal brittlestar, Amphiura filiformis

Seawater acidification due to anthropogenic release of CO2 as well as the potential leakage of pure CO2 from sub-seabed carbon capture storage sites (CCS) may impose a serious threat to marine organisms. Although infaunal organisms can be expected to be particularly impacted by decreases in seawater pH, due to naturally acidified conditions in benthic habitats, information regarding physiological and behavioral responses is still scarce. Determination of pO2 and pCO2 gradients within the burrows of the brittlestar Amphiura filiformis during environmental hypercapnia demonstrated that besides hypoxic conditions, increases of environmental pCO2 are additive to the already high pCO2 (up to 0.08 kPa) within the burrows. In response to up to 4 weeks exposure to pH 7.3 (0.3 kPa pCO2) and pH 7.0 (0.6 kPa pCO2), metabolic rates of A.filiformis were significantly reduced in pH 7.0 treatments accompanied by increased ammonium excretion rates. Gene expression analyses demonstrated significant reductions of acid-base (NBCe and AQP9) and metabolic (G6PDH, LDH) genes. Determination of extracellular acid-base status indicated an uncompensated acidosis in CO2 treated animals, which could explain depressed metabolic rates. Metabolic depression is associated with a retraction of filter feeding arms into sediment burrows. Regeneration of lost arm tissues following traumatic amputation is associated with significant increases in metabolic rate, and hypercapnic conditions (pH 7.0, 0.6 KPa) dramatically reduce the metabolic scope for regeneration reflected in 80% reductions in regeneration rate. Thus, the present work demonstrates that elevated seawater pCO2 significantly affects the environment and the physiology of infaunal organisms like A. filiformis.

Continue reading ‘Energy metabolism and regeneration impaired by seawater acidification in the infaunal brittlestar, Amphiura filiformis’

Response of corals to ocean acidification: what can be learned from field studies?

It has been predicted that rates of coral calcification, as well as the photosynthetic rates of their symbiotic algae, will dramatically decline in response to what is typically referred to as an acidification of the world’s oceans, as the atmosphere’s CO2 concentration continues to rise in the years, decades, and centuries to come. As ever more pertinent evidence accumulates, however, the true story appears to be just the opposite. This summary examines such evidence obtained from field-based studies conducted in the natural ocean.

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Interactions between filamentous turf algae and coralline algae are modified under ocean acidification

Ocean acidification is a decrease in seawater pH and carbonate ion concentration due to increased uptake of atmospheric carbon dioxide by the world’s oceans. This has major implications for many marine organisms, particularly the calcifiers. Crustose coralline algae (CCA) are among the most sensitive calcifying organisms to ocean acidification. In contrast, filamentous turf algae, which compete with CCA for space on the substratum, could potentially benefit from high pCO2 conditions, suggesting that the effects of filamentous turf on coralline algae may be amplified in a high pCO2 environment. The effect of ocean acidification on the growth of coralline algae, however, has rarely been investigated in combination with ecological interactions such as competition with filamentous turfing algae. Here we tested the combined effects of ocean acidification and overgrowth by filamentous turf algae on CCA calcification, photosynthetic capacity and quantum yield of photosynthesis. We observed a positive effect of algal turfs on CCA calcification but a negative effect on photosynthesis in the high pCO2 treatments, however, these effects were variable over time. Our results have demonstrated the importance of investigating how inter-species interactions such as competition will complicate the impacts of ocean acidification.

Continue reading ‘Interactions between filamentous turf algae and coralline algae are modified under ocean acidification’

Principal Investigator/Scientist position: fate and impacts of ocean greenhouse gases

The Monterey Bay Aquarium Research Institute (MBARI) seeks a Principal Investigator (PI) to develop and direct a small team working in the general area of the fate and impacts of ocean greenhouse gases. A Ph.D. in the physical or biological sciences, D.Eng., or equivalent is required. Applicants who are at an early- to mid-stage in their career (equivalent to assistant or associate professor) with a demonstrated ability to work in an interdisciplinary environment are encouraged to respond.

Applicants should have a minimum of three years of postdoctoral work experience, a positive personnel management track record, proven ability to work with a diverse group of people, and be capable of securing extramural funding. A research focus that includes instrument development for detecting and quantifying key elements and chemical compounds that actively influence the growth and distribution of marine organisms is desired.

Continue reading ‘Principal Investigator/Scientist position: fate and impacts of ocean greenhouse gases’

Octocoral tissue provides protection from declining oceanic pH

Increase in anthropogenic pCO2 alters seawater chemistry and could lead to reduced calcification or skeleton dissolution of calcifiers and thereby weaken coral-reef structure. Studies have suggested that the complex and diverse responses in stony coral growth and calcification, as a result of elevated pCO2, can be explained by the extent to which their soft tissues cover the underlying skeleton. This study compared the effects of decreased pH on the microstructural features of both in hospite (within the colony) and isolated sclerites (in the absence of tissue protection) of the zooxanthellate reef-dwelling octocoral Ovabunda macrospiculata. Colonies and isolated sclerites were maintained under normal (8.2) and reduced (7.6 and 7.3) pH conditions for up to 42 days. Both in hospite and isolated sclerites were then examined under SEM and ESEM microscopy in order to detect any microstructural changes. No differences were found in the microstructure of the in hospite sclerites between the control and the pH treatments. In stark contrast, the isolated sclerites revealed dissolution damage related to the acidity of the water. These findings suggest a protective role of the octocoral tissue against adverse pH conditions, thus maintaining them unharmed at high pCO2. In light of the competition for space with the less resilient reef calcifiers, octocorals may thus have a significant advantage under greater than normal acidic conditions.

Continue reading ‘Octocoral tissue provides protection from declining oceanic pH’

Lost in an acid sea: a fish’s sense of smell

Acidic ocean water blunts the sense of smell in fish, making them bolder – perhaps recklessly so, according to a new study offering a glimpse of the oceans of the future.

The findings suggest that, if greenhouse gas emissions continue unabated, fish could suffer debilitating behavioral effects.

“If reef fish behavior does not adapt to rising CO2 levels over coming generations, there could be serious consequences for the structure and function of future reef communities,” the authors wrote in the study published in Nature Climate Change.

Continue reading ‘Lost in an acid sea: a fish’s sense of smell’

Rising ocean acidity levels affecting sea-life sense of smell (text and audio)

Scientists from the Georgia Institute of Technology and the Australian Institute of Marine Science say the acidic sea water is starting to disrupt the ocean’s food chain, damaging sea-life’s sense of smell – making it hard for fish to sniff out the predators they need to avoid and the prey they want to catch. VoR’s Nima Green spoke to Danielle Dixson, one of the biologists who carried out the study.

Rising carbon dioxide levels are making the planet’s oceans more acidic. According to a new study – by the end of the century, the ocean’s PH will have dropped from 8.14 to 7.8.

Fish under ocean acidification conditions show an inability to learn, their brain lateralisation is disrupted, and their vision is disrupted slightly, says Dixson.

Continue reading ‘Rising ocean acidity levels affecting sea-life sense of smell (text and audio)’


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