Global Warming’s Impact on Lobsters Has Scientists in a Stew


The Ellsworth American – December 27, 2007

I have written before on the possible repercussions of global warming on plant and animal life (a few examples are here, here, and here).  Most of these repercussions come off as solid conclusions even though they really are just educated guesses on the reaction of the given species. In this case, the author was much more balanced and more fair, as he states that it could be good for lobsters or it could be bad. This acknowledgement that a complicated climate model interacting with a complicated species is not a sure science is refreshing. (Follow the feed link to read the rest of the story).

Lobsters are influenced by the temperature and the chemical composition of the ocean water. The calcium carbonate in the ocean is extracted to allow them to build their shells. So if that compound is reduced in concentration, it will stress the animal and hurt its longevity. Warmer water has been known to increase the lobster population however it can also disrupt the food source for larval lobsters which could reduce their numbers. Warmer water could also increase the likelihood of diseases in lobsters.

With multiple influences that may counteract each other, definitive conclusions are simply not possible. While many writers would focus only on one part of this discussion and make a prediction based on that partial data, Mr. Rappaport has the strength to say that solid conclusions are not possible.

The specific impacts of that warming, however, are matters of considerable debate.

According to Steneck and his colleagues, as the Earth’s atmosphere grows warmer and the concentration of carbon dioxide (CO2) continues its increase, global sea temperatures will also rise, and the oceans will become more acidic.

Like coral reefs, lobsters (and bivalves such as clams) depend on drawing calcium carbonate from the water to build their shells. In theory, if the waters of the northeast Atlantic ocean grow more acidic, crustaceans and bivalves will have to work harder to build their shells and will have less energy available to forage for food, but scientists are unsure of how lobsters in the Gulf of Maine would be affected.

Lobsters precipitate calcium out of the ocean through their blood system. To predict what impact acidification might have on the lobster population over the next 50 to 100 years, Incze said, it is necessary to have “some idea of how much ocean acidity will increase” during that period.

Over the past 20 to 25 years, scientists have seen a “pretty steady increase” in water temperatures in the Gulf of Maine, according to Department of Marine Resources (DMR) biologist Carl Wilson. Over the same period, “the lobster population has seen an exponential increase favorable to Maine,” he said.

As yet, no one knows what causes shell disease, but some scientists believe its prevalence may be related to warmer water. Wilson won’t make that connection directly but, he said, “some pathogens become increasingly active and virulent as the temperature increases.”

This is very good article and it gives a balanced perspective of the complexity of the issues. I encourage you to click through here.

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