Friday, July 31, 2015

Crab Lab!

In our last post, you heard us mention that one of the reasons we do OA surveys is to find out when and where OA events happen, and how they might impact biology. The link between the chemistry and the ecosystem is a big reason why we deploy the Bongo nets. On this project, one of the organisms we are most interested in during this mission are larval crabs.
Some of the larval crabs we have collected during this mission. Photo by Jennifer Questel (UAF).
When I asked Jennifer Questel, one of our ecologists on board how old these crabs were, she told me just a couple of weeks! These larval stages are the most vulnerable for red king crab, the face of the Bristol Bay crab fishery (and one of the types of crab they pull in during Deadliest Catch).  Scientists at NOAA’s Alaska Fisheries Science Center here in Kodiak, Alaska have shown that larval king crab have less than half the survival rate of normal crabs when exposed to ocean acidification levels expected during the next century. This means that fewer crabs would surviving to adulthood, which could shrink the overall adult population.

Lower crab populations likely mean lower crab harvests, and this could be a big challenge for Alaska given that so much of the state’s fishing revenue comes from crabbing. Annually, the crab fishery pulls in around $200 million USD.

Jennifer and Caitlin have been setting aside larval crabs they find in the bongo nets for Dr. Robert Foy of the Alaska Fisheries Science Center, and the informally named ‘Crab Lab.’ These specimens will be carefully examined for any potential physiological impacts of ocean acidification. We’ll also take a look at the spatial distribution of these baby crabs to see if there are any corresponding patterns in ocean chemistry and the presence of these organisms.

It’s important to remember that we still have a long way to go towards understanding the complete impacts of ocean acidification on crab fisheries around Alaska, but there is a lot of current research being done. Dr. Foy’s team is working on laboratory studies that show how acidification impacts king and tanner crabs. This data is then built into models that predict just how much acidification it will take to impact future crab populations. OARC is also working to understand how acidification will play into the overall Alaskan economy.

Want to know more? Check out these links: 


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