Impact of aragonite saturation state changes on migratory pteropods

Thecosome pteropods play a key role in the food web of various marine ecosystems and they calcify, secreting the unstable CaCO₃ mineral aragonite to form their shell material. Here, we have estimated the effect of ocean acidification on pteropod calcification by exploiting empirical relationships between their gross calcification rates (CaCO₃ precipitation) and aragonite saturation state Ω_a, combined with model projections of future Ω_a. These were corrected for modern model-data bias and taken over the depth range where pteropods are observed to migrate vertically. Results indicate large reductions in gross calcification at temperate and high latitudes. Over much of the Arctic, the pteropod Limacina helicina will become unable to precipitate CaCO₃ by the end of the century under the IPCC SRES A2 scenario. These results emphasize concerns over the future of shelled pteropods, particularly L. helicina in high latitudes. Shell-less L. helicina are not known to have ever existed nor would we expect them to survive. Declines of pteropod populations could drive dramatic ecological changes in the various pelagic ecosystems in which they play a critical role.

A multi-year assessment of biological perturbations of CO2 in the Northeast Channel of the Gulf of Maine

The University of New Hampshire (UNH), in collaboration with the University of Maine at Orono (UMO) and the University of Montana, has been monitoring surface ocean dissolved carbon dioxide and oxygen in the Northeast Channel, at a site on the northeast flank, of the Gulf of Maine for the last several years. UMO has maintained a buoy at this site (Buoy N) since 2004, and UNH has deployed two instruments (the SAMI-CO2 Sensor (Sunburst Sensors, LLC) and an Aanderraa Instrument Oxygen Optode 3835) since March 2008. The controls on the CO2 system are examined to determine the dominating biological seasonal influences that occur alongside physical processes. We evaluate several approaches to isolate these factors and processes using the buoy data and following previous studies. Preliminary results suggest measurable interannual biochemical variability may be attributed to water mass dynamics at this site.

Is Panarea Island (Italy) a valid and cost-effective natural laboratory for the development of detection and monitoring techniques for submarine CO2 seepage?

Developing reliable detection and monitoring techniques for underwater CO2 seepage and its effects on the marine environment is important for a wide range of topics; for example: volcanic surveillance, risk assessment of potential leakages from sub-seabed CO2 storage sites, and to forecast the effects of ocean acidification. A novel approach is to use areas where natural release of CO2 is present as ‘field-laboratories’ for validation of CO2 monitoring techniques and procedures. One such area was identified close to the volcanic island of Panarea (Italy). Here, CO2 seeps from the seafloor in shallow water allowing scuba divers to collect the needed data. Moreover, the coastal setting allows use of small boats for the marine operations, thus strongly reducing the costs. The applied study techniques examined are mainly sampling methods for free and dissolved gases, direct measurement of the CO2 fluxes, pH measurement along the water column, and verification of the impact of CO2 on the local environment.

From these first results, the submarine degassing area of Panarea can be realistically considered a natural laboratory where it is possible to test and validate detection methods for the prompt identification of potential seepage from sub-seabed CO2 storage areas. The particularly favorable environment permits the use of simplified logistics, thus reducing the costs of the research to almost negligible values if compared with any high-seas operation.

Elevated carbon dioxide affects behavioural lateralization in a coral reef fish

Elevated carbon dioxide (CO₂) has recently been shown to affect chemosensory and auditory behaviour, and activity levels of larval reef fishes, increasing their risk of predation. However, the mechanisms underlying these changes are unknown. Behavioural lateralization is an expression of brain functional asymmetries, and thus provides a unique test of the hypothesis that elevated CO₂ affects brain function in larval fishes. We tested the effect of near-future CO₂ concentrations (880 µatm) on behavioural lateralization in the reef fish, Neopomacentrus azysron. Individuals exposed to current-day or elevated CO₂ were observed in a detour test where they made repeated decisions about turning left or right. No preference for right or left turns was observed at the population level. However, individual control fish turned either left or right with greater frequency than expected by chance. Exposure to elevated-CO₂ disrupted individual lateralization, with values that were not different from a random expectation. These results provide compelling evidence that elevated CO₂ directly affects brain function in larval fishes. Given that lateralization enhances performance in a number of cognitive tasks and anti-predator behaviours, it is possible that a loss of lateralization could increase the vulnerability of larval fishes to predation in a future high-CO₂ ocean.

Ocean acidification’s decalcifying effects explained in detail (video)

Study provides clearer data on the impact of atmospheric CO2 on the calcium carbonates of coral and shellfish

The negative response of corals and mollusks to ocean acidification stemming from increasing atmospheric carbon dioxide levels and warming temperatures varies widely, which has perplexed scientists because they have not been able to pin down general patterns for how the shells and skeletons of calcifying sea creatures grow and dissolve under lower pH conditions. Studies led by Riccardo Rodolfo-Metalpa of the University of Plymouth, in England, now provide clearer results by showing that the animals’ tissues and organic skinlike layers play a major role in protecting their calcium carbonate structures (Nat. Clim. Change, DOI: 10.1038/nclimate1200). The researchers transplanted corals, limpets, and mussels in the ocean off the coast of Italy near Mount Vesuvius, where CO₂ bubbles up from the seabed as a result of volcanic activity. The test area serves as a natural laboratory to see how the animals respond to acidifying conditions. They also studied animals exposed to ⁴⁵Ca-labeled water in the lab, which allowed them to measure CaCO₃ formation and dissolution rates under varying conditions. The team observed that the creatures generally calcify more quickly at higher CO₂ levels, but their unprotected surfaces dissolve away faster at lower pH, especially in combination with warmer water temperature. The net detrimental decline in calcification depends on how much protection individual species have.

Ocean acidification event in Portland

Care about the Pacific Northwest’s oceans? Worried our fossil-fuel addiction is jeopardizing our marine and shellfish industries? Learn more about ocean acidification in the Northwest at E2′s event, the Acid Test: Ocean Acidification and the Pacific Northwest.

Speakers will include Washington Representative Brian Baird, NRDC oceans attorney Leila Monroe, and commercial fisherman Amy Grondin. E2 will also screen NRDC’s new short film, Acid Test: The Global Challenge of Ocean Acidification.

Calcifiers cover up changes in ocean pH

Corals and molluscs are able to protect themselves from the affects of acidic oceans, but only to a point, say marine scientists who have measured individual species resilience to pH change.

Australian researcher Dr Ross Jeffree, one of the study’s principal investigators, says as pH levels fall protective structures such as shells that are based on calcium carbonate dissolve.

But their loss is offset by calcification or rebuilding of the lost skeleton or shells.

Jeffree, who until recently headed a marine environment laboratory at the International Atomic Energy Agency in Monaco, explains that they wanted to distinguish the rate of loss and the rate of accrual from the net rate of calcification.

“We wanted to understand in greater detail the ability to possibly enhance calcification rates when exposed to acidified waters and also to see whether the exposed parts of the shell will still dissolve.”

The study, which is published in Nature Climate Change, examined three types of marine calcifiers: mussels, limpets and two species of corals. One of the coral species is completely covered by tissue while the other has regions of its skeleton exposed.

Shell-shock! Damage to marine ecosystems revealed

A team of marine experts is helping predict the future of coastal ecosystems after discovering that warming temperatures may exacerbate ocean acidification.

In a paper published in full by Nature Climate Change magazine this month, the scientists warn that rapidly deteriorating Mediterranean coastal ecosystems are further threatened by increasing CO2 levels.

Dr Riccardo Rodolfo-Metalpa, Plymouth University Postdoctoral Research Fellow, based at the International Atomic Environmental Agency (IAEA), has been studying marine life off the Island of Ischia in Italy where carbon dioxide bubbles up through vents in the seabed due to volcanic activity around Mount Vesuvius in Naples.

Dr Rodolfo-Metalpa, said: “Our transplant experiments with corals, limpets and commercially important mussels have shown the severe risks associated with increasing carbon dioxide emissions for marine life. These animals try to grow their shells and skeletons faster but they simply dissolve away. Mediterranean coastal ecosystems are being degraded by increasing temperatures and we now know that this warming can make the effects of ocean acidification worse.”

Dr Jason Hall-Spencer, a Reader in Marine Biology at Plymouth University, coordinated the team of scientists from Monaco, Italy, Israel and France as part of a project to assess the risks related to ocean acidification and seawater temperature increase at organism, ecosystem and economic scales.