A Case Study on Ocean Acidification

INTRODUCTION

 

One of most important topics for scientists is to understand what are the economical, sociological, and environmental aspects that may alter the sustainability of all species on Earth. The traditional definition of sustainability calls for policies and strategies that meet society’s present economic, social and environmental needs without compromising the ability of future generations to meet their own needs1 .

 

Groups of marine and environmental scientists have being studying ocean acidification for years. Recent literature suggests that the concentration of carbon dioxide (CO2) will almost certainly be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years (Figure 2). The oceans are a principal sink for CO2 coming from human activity where it is estimated to have caused a 30% increase in the concentration of H+ ( or H3O + ) in ocean surface waters since the early 1900s and may lead to a drop in seawater pH of up to 0.5 units by 2100.

 

CAUSES

 

Ocean acidification's impact is not yet known for every commercially and recreationally valuable species, but emerging data suggest that the number or quality of many high-value, aragonite-forming mollusks could decrease, and declining economic revenues in that fishery sector may follow. This possibility is supported by findings such as decreased mollusk populations in acidified ecosystems, malformation of juvenile oyster shells in aragonite-undersaturated laboratory studies, and decreased survival of oyster larvae in upwelling Oregon seawater with decreased pH and altered biogeochemistry.

 

Mollusks and crustaceans comprise the bottom or middle trophic levels of many ecosystems, implying that acidificationrelated damage to either of these groups also may negatively impact their primary and secondary predators. Effects of prey losses on predator numbers are poorly quantified at present, however, and the total ecosystem impact will depend on whether alternative prey species are available and whether predators can switch among prey. Currently, predictions of ex-vessel losses from declining mollusk harvests must depend on translating laboratory experiments showing damage to individual organisms into population losses in nature4 . Substantial revenue declines, job losses, and indirect economic costs may occur if ocean acidification broadly damages marine habitats, alters marine resource availability, and disrupts other ecosystem services.

 

 A marine scientist, Jason M. Hall-Spencer, from the Marine Biology and Ecology research Center at University of Plymouth recently published: “Our understanding of how increased ocean acidity may affect marine ecosystems is at present very limited as almost all studies have been in vitro, short-term, rapid perturbation experiments on isolated elements of the ecosystem”5 . The scientist and his research group started a series of experiments in order to show the effects of acidification on benthic ecosystems at shallow coastal sites where volcanic CO2 vents lower the pH of the water column. Between 18 April and 9 May 2007, surface and bottom water samples were regularly taken for measurements of the spatial and temporal variability in pH (in total scale), total alkalinity and salinity in various weather conditions. They found that along gradients of normal pH (8. 1–8.2) to lowered pH (mean 7.8–7.9, minimum 7.4–7.5), typical rocky shore communities with abundant calcareous organisms shifted to communities lacking scleractinian corals with significant reductions in sea urchin and coralline algal abundance. Hall-Sprncer’s group commented: “To our knowledge, this is the first ecosystem-scale validation of predictions that these important groups of organisms are susceptible to elevated amounts of CO2.” They found that sea-grass production was highest in an area at mean pH of 7.6 where coralline algal biomass was significantly reduced and gastropod shells were dissolving due to periods of carbonate sub-saturation. The species populating the vent sites comprise a suite of organisms that are resilient to naturally high concentrations of pCO2 and indicate that ocean acidification may benefit highly invasive nonnative algal species. Their results provide the first in situ insights into how shallow water marine communities might change when susceptible organisms are removed owing to ocean acidification.

 

 

Why should we all care, and what can you do?

 

If you live in Kansas or Oklahoma, you may think that ocean acidification doesn’t affect you. But it does. Ocean acidification impacts important sectors of the US economy, like fisheries and tourism, it affects food supply, and makes global warming worse by hindering the oceans’ ability to absorb CO2. For communities that depend on coastal resources, their way of life and cultural identity are on the line.

 

If CO2 emissions continue unabated, by the end of the century, ocean acidification is expected to reduce harvests of U.S. shellfish. It’s estimated that by the end of the century annual supplies of clams could decrease by 35 percent, oysters supplies could fall by 50 percent, and scallops could see a decline of 55 percent. Overall, the shellfish industry could experience cumulative consumer losses of $230 million. In this same scenario, ocean acidification paired with warming could cost $140 billion in today’s dollars in lost recreational benefits associated with coral reefs, and the US coral reef recreation industry could decline in value by more than 90 percent by 2100.

 

The most effective way to limit ocean acidification is to act on climate change, implementing solutions to dramatically reduce the use of fossil fuels. If we dramatically cut our global warming emissions, and we limit future warming, we can significantly reduce the harm to marine ecosystems.

 

The most recent National Climate Assessment projects that by taking action now we could avoid steep declines in fish catch potential, thus reducing harm to fisheries.

The IPCC report highlights that with significant emissions reductions, 30% of coral reefs would be spared from extinction.

We also need to ensure that resources reach those communities that will be most affected by ocean acidification. At present, taxpayers foot the bill for climate damages and adaptation costs. However, climate change negatively impacts local economies and stymies these communities’ ability to adapt.

 

Courts are beginning to consider holding fossil fuel producers accountable for damage they knew their products were causing because they chose to misinform investors and the public about those risks instead of acting to mitigate them. Making a case for these companies’ responsibility, Henry Shue, professor of politics and international relations at the University of Oxford, argues “Companies knowingly violated the most basic moral principle of 'do no harm,' and now they must remedy the harm they caused by paying damages and their proportion of adaptation costs.” Scientific findings that show the extent of the damage caused by carbon pollution can inform those efforts.