Wednesday, August 13, 2014

Penguins Act As Coalmine-Canaries for the Southern Ocean

Miners used to bring caged canaries down into the mines with them. The notion was that if toxic gases like methane or carbon monoxide leaked into the mine, then the canaries would die before the humans, giving the miners a chance to escape. The idea of a sentinel species is the same. Sentinels are groups of animals who are particularly or uniquely sensitive to changes to their ecosystem. If a sentinel species begins to suffer, it might mean that the broader ecosystem is under attack as well, sometimes giving us a brief window of opportunity to try to address the problem. In some ways, penguins are a sentinel species for southern ocean ecosystems.

Seabirds in general are useful indicators of ecosystem health because they are so dependent on having suitable habitats for breeding and on finding sufficient amounts of prey. Penguins in particular reflect local (or regional) conditions perhaps better than any other group of seabirds. That’s according to Head of Conservation Biology at the British Antarctic Survey Phil N. Trathan and colleagues, who reasoned that understanding the threats to penguins might allow us a better understanding of the Southern Oceans more generally.

Seabirds are the most threatened group of birds, and after albatrosses, penguins are the second most threatened group of all the seabirds. Some seabirds can travel quite far to find food; if there isn’t enough nearby, they can fly a little farther, and are therefore better able to withstand certain pressures. But penguins – all 18 species of them – tend to stick close to home. Penguin populations can therefore reflect both natural, seasonal variations in the health of the ecosystems within several hundred kilometers of their colonies, as well as the more artificial changes brought about by human activities.

In general, the regions with the most cumulative impacts from human activities are in the northern hemisphere. That makes sense, since proportionally, more humans live in the northern hemisphere. But that doesn’t mean that the southern hemisphere in unaffected by human activity. The Southern Oceans, however, are less studied. If researchers can figure out the factors that cause penguin populations to suffer, then they might be able to determine what factors are threatening the Southern Oceans more generally. For Trathan’s team, penguins might as well be canaries.

768px Location Southern Ocean.svg  Penguins Act As Coalmine Canaries for the Southern Ocean
The Southern Ocean, highlighted in blue.

They found that penguin populations are in some ways resilient and, if given sufficient habitat and food, can recover from historic threats like hunting (for oil and feathers) and egg harvesting. Given the threats we aren’t equipped to mitigate in the near- or medium-terms like climate change, infectious disease transmission, and toxic algal blooms, Trathan argues that it is more important that we address those stressors over which we do have control.

The threats from habitat degradation, invasive species, oil pollution, plastic pollution, fisheries bycatch, and competition with fisheries over their prey sources, represent major concerns and “require concerted action to mitigate future population declines for many species.” In other words, the ability for penguins to survive global pressures like climate change and ocean acidification will depend on our ability to protect their prey, to protect their breeding grounds, and to eliminate the pollution from the waters in which they swim. “A risk averse or precautionary approach to the conservation of penguins would thus take immediate action to off-set these impacts,” writes Trathan.

The best solution identified by Trathan’s group is the establishment of marine protected areas (MPAs) both in sovereign waters and on the high seas. Because penguins have different spatial needs as they age, most existing MPAs are inadequate to protect penguins throughout their lifespan. Despite the challenge of coordinating local, national, and international conservation efforts, protecting penguins would also have a positive effect on the other species who share their ecosystems, including fish and marine mammals.

MPAs alone won’t get the job done, however, which is why Trathan and colleagues say that other, flexible, creative approaches will be required to supplement them. Coastal breeding habitats should be protected, especially since penguins have such extreme site fidelity. Introduced or invasive species need to be strictly controlled. Shipping lanes ought to be routed away from critical penguin resting, transit, and foraging areas. “Concerted action to conserve penguin populations today,” they write, “will be essential to facilitate populations that are robust and resilient to climate change impacts in the future.” 

– Jason G. Goldman | 13 August 2014

Source: Trathan P.N., García-Borboroglu P., Boersma D., Bost C.A., Crawford R.J.M., Crossin G.T., Cuthbert R.J., Dann P., Davis L.S. & DE LA Puente S. et al. (2014). Pollution, Habitat Loss, Fishing, and Climate Change as Critical Threats to Penguins., Conservation biology : the journal of the Society for Conservation Biology, PMID:
Header image: Rockhopper penguin, Patagonia, Argentina via; Southern ocean graphic via Connormah/Wikimedia commons


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