Crustaceans and acidification –

Crustaceans and acidification Published:  25 March, 2014

Red king crab

RESEARCHERS have used red king crabs in an experiment on ocean acidification.

Based at the Kodiak Laboratory, researchers used red king crabs from the Alutiiq Pride Shellfish Hatchery, from eastern Bering Sea broodstock, in the experiment.

Red king crab may be vulnerable to ocean acidification because their shells are made of calcium carbonate, which can dissolve in acidic waters.

Newly settled crabs, about 2 mm long, were placed in individual holding chambers at three pH treatments: pH 8.1 (control, current oceanic conditions), pH 7.8 (expected global average by the year 2100), and pH 7.5 (expected by 2200).

Researchers monitored growth and survival of the crabs for 200 days and measured calcium content in the crabs.

The results were not encouraging. Crabs in both pH 7.8 and pH 7.5 water died much faster than those in the control water. All the crabs in pH 7.5 water were dead within 95 days.

By the end of the experiment the crabs at pH 7.8 were 38% smaller than in control water. However, at the end of the experiment the calcium content in the control and pH 7.8 crabs were not different.

The reduced survival and growth at lower pH means that ocean acidification could have substantial negative effects on the populations of red king crab and crab fisheries within the next 100 years.

Further research will consider daily and seasonal fluctuations in pH naturally experienced by crab throughout their life history.

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