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Blog Posts by: Santi

Most potential effects of climate change - considerable changes in air and sea temperature, sea level rise, increased flooding and desertification, and so on - are now so well established that the topic has recently been turned into a major summer blockbuster. That was Hollywood of course, which the Webster's American Dictionary defines as 'exaggeration with intent to thrill'. Yet, global warming is certainly real, and considerable research is being carried out to try and better grasp its likely consequences. That research has turned up some interesting results, published in Science last month.

Global warming and coral reefs: like pinstripe pants and a plaid shirt

The main greenhouse gas is of course carbon dioxide, or CO2. Like rainforests on land, the oceans are an enormous 'sink' for the gas. Nearly half of the extra CO2 produced since the Industrial Revolution has ended up in the sea. For those of us on land, that's great news, right? In some ways yes, as the oceans are acting as a buffer to the effects of global warming. In reality though, that's long term, as in thousands-of-years long term. For sea creatures it may be quite the opposite. By the end of next century, rising levels of CO2 in the atmosphere may halve the rate at which organisms such as corals, plankton and shellfish (bivalve mollusks) grow. This happens because increased CO2 levels in the sea make it more acidic, dissolving the calcium carbonate that the creatures use to make their skeletons and shells. This problem impacts the ecosystem immediately, and will only get worse over time. The effects of these changes on the wider ecosystem are unknown, but are likely to be significant because these organisms make up the foundation of the marine food web or provide shelter and protection for countless other species.

Is no place safe?

If I'd have seen a chance to bet on the deep sea being the only place on the planet that would not be affected by global warming, I'd have put half my monthly salary on it. Thankfully I saw no such bet, and as a result am now 6 cents better off. Changes in the atmosphere do affect the deep sea. Scientists have found that the prevalence of sea cucumbers - close relatives of starfish and sea urchins - at 13,000 feet off California varies depending on how much food is falling through the waters above. And these rainfalls of food depend on atmospheric climate events like El Nino and global warming.

For more info on these studies see Acid Seas and No Cucumbers.

The Australian Government closed a third of the GBR to fishing at the beginning of this month, giving it the highest level of protection seen on any reef system yet. This monumental move came after countless studies indicating massive declines in coral reefs in Australian waters and around the world. Banning fishing will relieve one of the pressures on reefs, allowing them to cope better with other major threats like climate change, pollution and storms.

The GBR and other coral reef ecosystems are well known for being home to an incredible array of marine species, full of vitality and color. The GBR itself is inhabited by 1,500 species of fish, 359 types of hard coral, 175 species of birds and more than 30 species of mammals, including dugongs and six of the world's seven threatened species of sea turtles.

Yet, contrary to what common sense might tell you, the waters in which the GBR makes its home are actually very poor quality. From a nutritional standpoint, they are like marine 'deserts'. So how do the reefs survive? Scientists have found that reefs and the myriad species that depend on them are all part of incredibly finely tuned ecosystems, in which nutrients are continually recycled. There is continual turnover of life as animals are born and die, but there is very little new input of nutrients. Thus they are not very 'productive' areas, in the way that the North Atlantic and Pacific Oceans are, with their once seemingly endless populations of cod and other fish. These waters, though now massively overfished, can cope with much higher levels of fishing than the poorly productive reef waters. Removal of any of these finely tuned elements could result in big changes in the reef ecosystem. For example, the crown-of-thorns starfish outbreaks that have left enormous areas of the GBR dead might well be as a result of man's removal of their natural predators.

The GBR is a global treasure. In protecting it, the Australian government has done a service not only to Australians, but to the entire world.

A new study (here is the abstract) has found that the quantity of large fishes weighing 4-16kg in the North Sea has declined by 97% since the onset of fishing. For bigger fish (16-66kg) that percentage is 99%. Pretty shocking numbers I think you'll agree. Perhaps even more remarkably, the total amount of fish (expressed by weight), including all species, ages, and sizes, has dropped by nearly 40% since fishing started. That's more than a third of the fish in the North Sea.

No wonder it's so difficult to get fish and chips made with cod anymore - pop into a British 'chippy' and you'll likely get dogfish in batter. At least that's still a fish I guess (though it's a closer relative to sharks than bony fishes like cod, bass and herring). Perhaps soon we'll only get deep fried squid or shrimp, animals that were once scorned from the dinner table for being 'bait' food.

Oh, wait, that's already happened.

The following is a blurb from Science magazine's writeup (subscribers only) about the new study (cite at the bottom).

"There is abundant evidence that fish stocks are being exploited at unsustainable rates in many sectors of the world's oceans. In order to gauge the extent of human impacts, it is necessary to assess where stocks stood in prefishery times; however, accurate analyses are hampered because records did not begin until many years, and often centuries, after initial exploitation.

"Jennings and Blanchard [the authors] have devised a method for estimating what fish abundances would be in the absence of fishing, using macroecology theory that relates abundance, biomass, predator-prey mass ratio, and efficiency of energy transfer between trophic levels in an ecosystem. Applying it to the North Sea fishery, they estimate that the current biomass of fishes larger than 4 kg is only about 2.5% of its pretrawling level, and the total biomass of all fishes is nearly 40% lower than it would have been. These effects are larger than those predicted from existing time-series data, and this approach may provide a useful basis for comparing the impacts of fishing across different ecosystems and different fish communities."

Fish abundance with no fishing: predictions based on macroecological theory, Journal of Animal Ecology, Volume 73 Issue 4 Page 632 - July 2004

That's not an environmental group's message, though it might as well have been. It's the theme chosen by the United Nations Environment Programme for this year's World Environment Day, June 5. As UNEP puts it, the "theme asks that we make a choice as to how we want to treat the Earth's seas and oceans. It also calls on each and every one of us to act. Do we want to keep seas and oceans healthy and alive or polluted and dead?"

Photo credit Alaska, Alberto Lindner, NOAA

The oceans are vast of course, and our impacts on them many, so we are unfortunately spoilt for choice when deciding which issues to work on. It is heartwarming then that UNEP has highlighted deep water corals as a new Global Conservation Challenge, paralleling the focus of Oceana's ongoing Stop Destructive Trawling campaign.

The plight of deep sea coral and sponge communities has come to light only in the last few years, but has been so dramatic that several countries have already closed off large areas of the seabed to bottom trawling, the main cause of their destruction. These remarkable animals are very similar to the shallow water varieties we all love to snorkel over, except that they are found hundreds or thousands of feet below the surface. They are among of the oldest creatures on the planet, some having been around since before the discovery of the Americas, and others being old already when the Roman Empire fell. The vast majority of these communities are still unprotected from our more damaging activities.

Photo credit California, MBARI/NOAA

UNEP plans on releasing a report next month entitled, "Cold-Water Coral Reefs: Out of Sight- No Longer Out of Mind." Ring a bell with anyone? For those of you new to Oceana, "Out of Sight, but no Longer out of Mind" was the tagline of our deep sea coral report last year. The reports share other similarities. The new report, though not yet released, promises to expand on the information presented in our report. It documents cold water corals from areas as far apart as Galapagos Islands and Brazil and Indonesia and Angola, as well as in the North Atlantic and Pacific Oceans off Great Britain, Scandinavia, Canada, and the US, and off Australia and New Zealand. It is also likely to strengthen calls for greater conservation of these spectacular deep sea communities.

So, thank-you to everyone involved with Oceana, in whatever way, small or large. It's good to see our work, enabled by you, paying off in such a big way.

UNEP's press release on Deep Sea Corals and Oceana's report are both available online.