Sick oceans news

The biggest political surprise this week was that Bob Katter, who I took to be a climate change skeptic, came out with this comment on radio in explaining why he didn't bother meeting Nicholas Stern & Garnaut:

"Just to indicate how stupid those people are, there is a very unassailable scientific case that there will be a problem arising in the oceans. They don't mention that."

What? I can only assume he means ocean acidification. He's about the last politician I would have expected to have concerns about that. But then why would he not meet leading economists who want to talk about the best way to reduce CO2? He's an enigma under an akubra wrapped in a banana skin.

Anyhow, onto other sick ocean news:

* a study of naturally low pH ocean waters near some CO2 vents in the Mediterranean indicates that it's very bad for the biodiversity of single celled organisms called Foraminifera:

The study, published in the September issue of the Journal of the Geological Society, found that increasing CO₂ levels caused foram diversity to fall from 24 species to only 4.

'Previous studies have shown a reduction in diversity of 30%, but this is even bigger for forams', said Dr Jason Hall-Spencer, one of the study's co-authors. 'A tipping point occurs at mean pH 7.8. This is the pH level predicted for the end of this century'.

...

'At a mean pH level of 7.8, calcified organisms begin to disappear, and non calcifying ones take over. We are headed towards that being the case in this century. The big concern for me is that unless we curb carbon emissions we risk mass extinctions, degrading coastal waters and encouraging outbreaks of toxic jellyfish and algae.'

Not exactly encouraging.

* Meanwhile, the krill in the Southern Ocean is being increasingly fished (to provide feed for acquaculture, it appears), and there is concern about its sustainability. Nature reports:

The total krill catch this season is expected to be 150,000–180,000 tonnes, exceeding last year's total by about 40%.

Another worry is the number of fishing vessels being deployed in the Southern Ocean. Norway is now operating three ships, for example, and China is expected to rapidly increase its krill fishing after sending its first vessel this year. "If China starts fishing in a big way, catch will expand rapidly, outstripping our ability to orderly manage it," says Steve Nicol, a marine ecologist with the Australian Antarctic Division in Kingston, Tasmania, who advises the Australian government on krill fisheries.

But more generally, climate change may well be an issue with them too:

Researchers suspect that Antarctic krill are also feeling the effect of climate change. Krill larvae feed on algae living on the bottom of sea ice, which is rapidly dwindling around the Antarctic Peninsula. According to one estimate, the number of krill in the Southern Ocean may have dropped by 80% since the 1970s. But "there is no definite answer as to how the krill responds to warming", says Nicol. It is also unclear whether krill stocks are transient or fixed to given areas, and how many live deeper than 200 metres, below the most heavily fished and studied region of the ocean.

So keep your concerns about the oceans going, Bob.

UPDATE: Curious as to how big 180,000 tonnes of krill really is, in terms of the total amount of fish caught in the sea? I turned up this from 2005:

AFTER DECADES OF GROWTH, the reported global wild fish catch peaked in 2000 at 96,000,000 tons, then fell to 90,000,000 tons by 2003, the last year for which worldwide data are available. The catch per person dropped from an average of 17 kilograms in the late 1980s to 14 kilograms in 2003--the lowest figure since 1965.

As fishing fleets expanded through the late 1980s and fish-finding and harvesting technologies became more efficient, the world's fishers systematically have gone after their catch at greater depths and in more remote waters. Over the past 50 years, the number of large predatory fish in the oceans has dropped by a startling 90%. Catches of many popular food fish such as cod, tuna, flounder, and hake have been cut in half despite a tripling in fishing effort.