Thursday, October 20, 2011

Alaska Day and Oil Spills

Happy (Belated) Alaska Day! It was on October 18th, so I'm a little late (again), but I hope everyone had a great day and a great week celebrating the 49th state! What did you do? I graded salmon and rockfish skeletons for how accurately each bone was identified (I'm TA-ing Ichthyology over at UAS)!

Since this Alaska Day is so close to the 18 month anniversary of the Deepwater Horizon oil spill (which occurred April 20, 2010), and Alaskans know a thing or two about the lasting effects of oil spills, I thought it'd be interesting to check in on how the Gulf of Mexico crustacean populations are doing today. Just because, you know, this happened:

a ghost crab on the shore line (picture from this photographer)

a dead blue crab floating in some oil

a little hermit crab trying to make its way through the muck

So what's happening now? A lot of the oil has been consumed by microbes (go microbes!) but there's still a layer of oil and ashes from the burned oil on swaths of the Gulf of Mexico sediment (via a report from the Gulf of Mexico Research Initiative, funded by BP). This layer could affect any benthic animal, like, say a crab, who may walk around and dig through the oil layer to forage for food. That foraging behavior was also a concern in Prince William Sound after the Exxon Valdez oil spill: researchers were worried about sea otters digging in the sediment for their prey and, in the process, dispersing the settled oil throughout the water column and onto themselves.

a ghost crab amid the oil, glowing under UV light
(to help with clean-up and all... the light, that is... not the crab)

Lingering oil may affect growth, reproduction, and ultimately survival, but Gulf of Mexico fisheries continue as long as the animals are deemed safe for consumption. It may be tricky to estimate spawning biomass for subsequent stocks, since there's little background data available about the spawning habits of crabs and shrimp around the Gulf, and so much is unknown about potential effects of oil on their reproductive physiology, but we'll just have to keep an eye on how those fisheries progress the next few years. There may still be hope: as far as crabs go, those that survived the spill may have one more trick up their sleeves:

For an interesting first-person account of an oil spill back in Alaska you can listen to Dune Lankard of Cordova's reaction to the Exxon Valdez oil spill here. Alaska Day: not just for celebrating, but also for learning!

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