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Discovered: Nuclear disaster lingers in Japanese waters; the hole in the Antarctic ozone hasn't been this small since the '90s; the problem with algae-derived biofuels; the amazing shrinking ancient hippo.

Fukushima continues to ripple through Japanese fish population. Well over a year and a half after the Tohoku earthquake, and the resulting Dai-ichi power disaster, fish caught off Japan's east coast still have radioactive contamination, officials have found. Four out of 10 fish caught in the affected regions are unfit for human consumption, according to Japanese seafood regulation. Woods Hole Oceanographic Institution marine chemist Ken Buesseler looked over the data, and published a paper in Science this week in which he explains, "It all points to this issue being long-term and one that will need monitoring for decades into the future." Most fish caught in northeastern Japan should be safe to eat, Buesseler insists, especially considering that Japanese authorities reduced the regulatory threshold from 500 becquerels of caesium per kilogram of wet weight to 100 Bq/kg. [BBC News]

Ozone hole above Antarctica shrinks to 20-year low. The gap in the ozone layer above the Antarctic has been smaller this year compared with trends observed over previous decades. It reached a maximum area of 8.2 million square miles in late September. That's undoubtedly huge—roughly the size of the North American continent—but is noticeably smaller than records set in recent years (compare this year's number with 2000's, 11.5 million square miles). So what's causing the shrinkage? Warmer than average temperatures in the South Pole, says NOOA's Earth System Research Laboratory scientist Jim Butler: "It happened to be a bit warmer this year high in the atmosphere above Antarctica, and that meant we didn't see quite as much ozone depletion as we saw last year, when it was colder." This doesn't suggest, however, that CFC pollution has abated enough to repair the ozone, or that climate change is slowing down. [Christian Science Monitor]

Lets wait a minute before going forward with algae biofuels. Manufacturing biofuels from algae has seemed to many like a promising idea. Barack Obama has even touted it as one possible way for the U.S. to end its reliance on foreign oil. But scientists with the U.S. National Research Council remain skeptical that we could implement such plans without relying on environmentally unsustainable tradeoffs. Jennie Hunter-Cevera, a microbial physiologist who headed up the committee behind the report, says, "to scale up any more is going to put really big demands on ... not only energy input, but water, land, and the nutrients you need, like carbon dioxide, nitrate, and phosphate." The issue has to do with scale more than anything. Start-ups like Sapphire Energy Inc. are able to produce "green crude" fuel with algae, sunlight, and carbon dioxide alone. But to bring this kind of biofuel up to the capacity to account for even five percent of the U.S.'s transportation fuel requirements, companies would be overly reliant on unsustainable water and fertilizer inputs. [Reuters]

Germany's ancient shrinking giant hippos. Another way to gauge the progression of climate change: go to the zoo and watch the hippos shrink. Well, if this round at all mirrors the warming climates of the Pleistocene Era, that's what might happen. 1.8 million years ago, a warming trend caused giant German hippopotamuses to shrink to the size of pygmies, according to University of Florence paleontologists. "Species of hippo ranged across pre-historic Europe, including the giant Hippopotamus antiquus a huge animal which often weighed up to a tonne more than today's African hippos," says the study's lead author Dr Paul Mazza. "While these giants ranged across Spain, Italy, and Germany, ancestors of the modern Hippo, Hippopotamus amphibius, reached as far north as the British Isles." Mazza found fossils in Untermaßfeld, Germany of hippos that weighed up to 3.5 tons. Fossils found in central Italy of later specimens were nearly 40 percent smaller. [Wiley]