July 19, 2016

Bob Foy covers crab tanks at the NOAA lab, Kodiak

Bob Foy covers crab tanks at the NOAA lab, Kodiak

This is Fish Radio. I’m Laine Welch – Baby Tanner crabs get clobbered by an off kilter ocean. More after this –

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A project on how Bering Sea Tanner crabs respond to acidic oceans yields some red flags for the future. Results from a first ever project showed that higher acidity, or pH, affects shell production and the immune systems of baby Tanners. The project followed the tiny crabs from birth for two years in acidic water tanks.

We put the mom in a treatment. We allowed her embryos to grow and hatch in the acidified treatment, we took them and put them in controlled different levels of pH to represent acidification and we let them grow. We then took the moms and mated them and ran them again for another year. What that means is those moms who we mated, their full reproductive development occurred in acidified conditions.

Bob Foy is director of the NOAA lab at Kodiak. The first year didn’t show many effects, he says, but the second year of exposure really had an impact on the tiny crabs’ ability to molt, which they do weekly or monthly depending on their growth stage.

It’s those larval and juvenile animals where they are going that constantly where we are seeing the effect because they are constantly going through these physiological stressful times to build a shell. And that’s where we are seeing the effects.     

Researchers also studied the baby crab blood cells that bring calcium to the shell. Crabs don’t have an immune system and the cells also fight off illnesses. Those functions went down as well.

 The bottom line is long term exposure to acidified sea water negatively impacts Tanner crabs ability to grow and survive and likely impacts their ability to defend against disease.   

The outcomes were modeled with Bering Sea stock assessment survey data.

  We are able to simulate the whole thing, increased mortality, all the way out to the end. And that is where we’ve come up with in this second year you see a very similar affect where after about two decades you start to see a decrease in recruitment in Tanner crab. 

The Tanner crab project is being published in five scientific journals.

Up next is a paper on Bristol Bay red king crab, which Foy says are getting a double whammy from higher acidity and ocean temperatures. Computer models predict the clock will start ticking on that stock in 50 to 80 years.

Fish Radio is also brought to you by Ocean Beauty Seafoods, an Alaska corporation proudly supporting Alaska’s coastal communities and the Alaskans who depend on fishing for their livelihoods and culture.  www.oceanbeauty.com    In Kodiak, I’m Laine Welch.