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Bowhead whales meet in North-West passage clearing
THIS WEEK
Marine life shifts as temperatures rise IN AUGUST 2010, a bowhead whale from the Bering Sea swam into the North-West Passage. Having negotiated Alaska and picked its way through the maze of ice-ridden channels off the north coast of Canada, it made its way to Viscount Melville sound. There it met a second bowhead, which had entered the passage from Baffin bay, next to Greenland. The two met because the passage, long blocked by ice, is opening as the climate warms. The anecdote, which came to light thanks to satellite transmitters on the whales, is part of increasing data showing how ocean life is being transformed by rising sea temperatures, with some bits of apparently good news to sweeten the pill. The two bowheads were tagged by Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources in Nuuk and his colleagues. Bowheads entered the passage in 2002 and 2006, but this was the first time two were seen to cross paths (Biology Letters, DOI: 10.1098/rsbl.2011.0731).
Brainy molluscs’ four-time evolution feat Slimy and often sluggish they may be, but some molluscs deserve credit for their brains and complex nervous systems – which, to top it off, they evolved independently. Four times. The mollusc family includes some of the most intelligent invertebrates: octopuses, squid and cuttlefish. The latest and most sophisticated analysis of their evolutionary history overturns our understanding of how 12 | NewScientist | 24 September 2011
Heide-Jørgensen thinks whales have been sneaking through, undetected, since the ice began to retreat. The Greenland population, once decimated by whalers, has grown suspiciously fast since 2000, and Heide-
Warmer seas Rising ocean temperatures are already shifting species worldwide
*Temperature change (°C) 3 to 5
Bowhead whale sub population
1 to 3
Pod of narwals spotted in Cambridge bay, Nunavut, Canada, on 15 August 2011 should have been further east
0.5 to 1 0 to 0.5 0 to -0.5
Following opening of North-West Passage, a bowhead from each sub population met in the Viscount Melville sound in August 2010
-0.5 to -1 -1 to -3 No data
Bowhead whale sub population
Cold-adapted species like cod are being forced north
Warm-adapted species like red gurnard are becoming more common in UK waters
Grey whale spotted off coast of Israel 8 May 2010 – should have been in Pacific
*2011 temperature compared with the average temperature taken between 1961 and 1990
they got so brainy. It relies on an analysis of genetic sequences common to all molluscs, which Kevin Kocot of Auburn University, Alabama, and his colleagues compared to find differences that have accumulated over time. The more a shared sequence differs between two species, the less related they are. In the traditional tree, snails and slugs (gastropods) are most closely related to octopuses, cuttlefish and squid (cephalopods). This tallies with their nervous systems, which are highly centralised compared with those of other molluscs. Gastropods have clusters of ganglia – bundles of
nerve cells – which, in many species, are fused into a single organ; cephalopods have highly developed central nervous systems that enable them to navigate a maze, use tools and solve complex problems. But in Kocot’s tree, gastropods sit next to clams, oysters and mussels (bivalves), which have much simpler nervous systems. And cephalopods are shifted to one of the earliest branches, meaning they evolved
“The centralised nervous systems of octopuses and snails must have evolved independently”
SOURCE: MET OFFICE (TEMPERATURES)
Michael Marshall
Jørgensen suspects the hand of immigration from Alaska. That’s perfectly possible, says Aviad Scheinin of the University of Haifa in Israel. In May 2010, he spotted a Pacific grey whale in the Mediterranean Sea, which probably got there via the Arctic. Further evidence of links between Atlantic and Pacific ecosystems comes from Cambridge bay in Nunavut, Canada, where pods of narwhals appeared on 15 August. They do not normally
venture so far west, but shrinking ice seems to be changing that. It’s not just whales that are affected by warming seas. Steve Simpson at the University of Bristol, UK, looked at 25,612 trawls in fisheries around the UK and in the North Sea between 1980 and 2008. There waters have warmed by 0.05 °C a year since 1980. Populations grew for 27 of the 50 most common fish; nine declined and 14 held steady (Current Biology, DOI: 10.1016/j. cub.2011.08.016). “I had expected to see many struggling and maybe one or two doing well,” he says In his surveys, cold-adapted species like cod were all in decline, replaced by warm-adapted ones like red gurnard, which breed faster. Markets are catching on. “Five years ago fishermen were selling red gurnard as bait to crab fishermen for 50 pence a fish,” Simpson says. Now restaurants buy them for £5 a fish. But the pill is bitter-sweet. An open North-West Passage may be good news for bowheads, which will have more places to feed, but many Inuit will struggle, since they rely on walruses that are running out of sea ice on which to breed. And although UK fish markets may be boosted, that’s no help to fishing communities in the tropics. If temperatures rise dramatically, many species there will either move out or die. n
before the other groups (Nature, DOI: 10.1038/nature10382). The bottom line? The centralised nervous systems of octopuses and snails must have evolved independently. That’s a remarkable feat. “Most biologists think complex structures usually evolve only once,” says team member Leonid Moroz of the University of Florida in St Augustine. Instead, the new study shows the evolution of complex nervous systems was not linear in molluscs. And the dawn of the mollusc brainiacs didn’t just happen twice, but at least four times, according to Moroz’s calculations. Ferris Jabr n
Marine life shifts as temperatures rise IN AUGUST 2010, a bowhead whale from the Bering Sea swam into the North-West Passage. Having negotiated Alaska and picked its way through the maze of ice-ridden channels off the north coast of Canada, it made its way to Viscount Melville sound. There it met a second bowhead, which had entered the passage from Baffin bay, next to Greenland. The two met because the passage, long blocked by ice, is opening as the climate warms. The anecdote, which came to light thanks to satellite transmitters on the whales, is part of increasing data showing how ocean life is being transformed by rising sea temperatures, with some bits of apparently good news to sweeten the pill. The two bowheads were tagged by Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources in Nuuk and his colleagues. Bowheads entered the passage in 2002 and 2006, but this was the first time two were seen to cross paths (Biology Letters, DOI: 10.1098/rsbl.2011.0731).
Brainy molluscs’ four-time evolution feat Slimy and often sluggish they may be, but some molluscs deserve credit for their brains and complex nervous systems – which, to top it off, they evolved independently. Four times. The mollusc family includes some of the most intelligent invertebrates: octopuses, squid and cuttlefish. The latest and most sophisticated analysis of their evolutionary history overturns our understanding of how 12 | NewScientist | 24 September 2011
Heide-Jørgensen thinks whales have been sneaking through, undetected, since the ice began to retreat. The Greenland population, once decimated by whalers, has grown suspiciously fast since 2000, and Heide-
Warmer seas Rising ocean temperatures are already shifting species worldwide
*Temperature change (°C) 3 to 5
Bowhead whale sub population
1 to 3
Pod of narwals spotted in Cambridge bay, Nunavut, Canada, on 15 August 2011 should have been further east
0.5 to 1 0 to 0.5 0 to -0.5
Following opening of North-West Passage, a bowhead from each sub population met in the Viscount Melville sound in August 2010
-0.5 to -1 -1 to -3 No data
Bowhead whale sub population
Cold-adapted species like cod are being forced north
Warm-adapted species like red gurnard are becoming more common in UK waters
Grey whale spotted off coast of Israel 8 May 2010 – should have been in Pacific
*2011 temperature compared with the average temperature taken between 1961 and 1990
they got so brainy. It relies on an analysis of genetic sequences common to all molluscs, which Kevin Kocot of Auburn University, Alabama, and his colleagues compared to find differences that have accumulated over time. The more a shared sequence differs between two species, the less related they are. In the traditional tree, snails and slugs (gastropods) are most closely related to octopuses, cuttlefish and squid (cephalopods). This tallies with their nervous systems, which are highly centralised compared with those of other molluscs. Gastropods have clusters of ganglia – bundles of
nerve cells – which, in many species, are fused into a single organ; cephalopods have highly developed central nervous systems that enable them to navigate a maze, use tools and solve complex problems. But in Kocot’s tree, gastropods sit next to clams, oysters and mussels (bivalves), which have much simpler nervous systems. And cephalopods are shifted to one of the earliest branches, meaning they evolved
“The centralised nervous systems of octopuses and snails must have evolved independently”
SOURCE: MET OFFICE (TEMPERATURES)
Michael Marshall
Jørgensen suspects the hand of immigration from Alaska. That’s perfectly possible, says Aviad Scheinin of the University of Haifa in Israel. In May 2010, he spotted a Pacific grey whale in the Mediterranean Sea, which probably got there via the Arctic. Further evidence of links between Atlantic and Pacific ecosystems comes from Cambridge bay in Nunavut, Canada, where pods of narwhals appeared on 15 August. They do not normally
venture so far west, but shrinking ice seems to be changing that. It’s not just whales that are affected by warming seas. Steve Simpson at the University of Bristol, UK, looked at 25,612 trawls in fisheries around the UK and in the North Sea between 1980 and 2008. There waters have warmed by 0.05 °C a year since 1980. Populations grew for 27 of the 50 most common fish; nine declined and 14 held steady (Current Biology, DOI: 10.1016/j. cub.2011.08.016). “I had expected to see many struggling and maybe one or two doing well,” he says In his surveys, cold-adapted species like cod were all in decline, replaced by warm-adapted ones like red gurnard, which breed faster. Markets are catching on. “Five years ago fishermen were selling red gurnard as bait to crab fishermen for 50 pence a fish,” Simpson says. Now restaurants buy them for £5 a fish. But the pill is bitter-sweet. An open North-West Passage may be good news for bowheads, which will have more places to feed, but many Inuit will struggle, since they rely on walruses that are running out of sea ice on which to breed. And although UK fish markets may be boosted, that’s no help to fishing communities in the tropics. If temperatures rise dramatically, many species there will either move out or die. n
before the other groups (Nature, DOI: 10.1038/nature10382). The bottom line? The centralised nervous systems of octopuses and snails must have evolved independently. That’s a remarkable feat. “Most biologists think complex structures usually evolve only once,” says team member Leonid Moroz of the University of Florida in St Augustine. Instead, the new study shows the evolution of complex nervous systems was not linear in molluscs. And the dawn of the mollusc brainiacs didn’t just happen twice, but at least four times, according to Moroz’s calculations. Ferris Jabr n