Imperiled Mussels (with Chorizo)
August 2, 2012
Global warming is too serious for the world any longer to ignore its danger or split into opposing factions on it.
Another sad example of how humankind has altered the ocean environment — exhausting the limits of an ecosystem’s endurance. The iconic coastal California mussel may be the casualty this time.
A recent study published in the journal Science predicts that by mid-century, western coastal waters will become sufficiently acidic to hinder shell formation by mussels, oysters and corals. These waters are particularly fecund because winds that blow surface water out to sea allow water laden with nutrients to swell near the shore. This upwelling renders those waters especially vulnerable to ocean acidification. Increased acidity levels develop in the waters as they absorb carbon dioxide which accelerate as trends of anthropogenic greenhouse gases continue to soar. Ocean acidification has been dubbed the osteoporosis of the seas.
What does this have to do with our cherished shellfish? As carbon dioxide dissolves in sea water, saturation levels of the mineral calcium carbonate, a critical building block for shells and skeletons, decreases. Undersaturation can reach perilous levels depriving these sea creatures of the basic component needed to develop and maintain their shells. According to these researchers (who were using optimistic models), by 2050 west coast seawater will no longer have sufficient saturation states to maintain adequate calcium carbonate levels. This places mussel populations at serious risk. This is indeed a dire finding given that mussels provide habitat, refuge, and food for some 300 other species.
A correlative finding was reached in a later study conducted at UC Davis Bodega Marine Laboratory. Researchers there noted that increased concentrations of carbon dioxide in the atmosphere that climate scientists attribute to human activity have resulted in increased ocean acidification. This team focused on mussel larvae, which swim in the open ocean before settling down on the shoreline and attaching to reefs as adults. As with many other marine creatures, mussel larvae are more vulnerable to environmental stresses.
Larvae were grown in the lab at present acid levels, levels projected for the end of the century if carbon dioxide emissions continue, and at levels which might be reached if emissions are reduced. The shells were measurably thinner and the mussels’ bodies smaller at projected acid levels.
Other researchers have sung the same refrain: if human actions continue unabated, oceans will continue to absorb rising levels of atmospheric carbon dioxide which causes ocean acidification whose corrosive effect ultimately threatens to decimate certain shellfish species.
Do we welcome such a sea change?
As always, follow the cleaning and culling ritual. Thoroughly scrub the mussels and rinse with several changes of cold water. If an open mussel closes when you press on it, it is good. If the mussel remains open, you should discard it. Pull off beards (the tuft of fibers that attach each mussel to the shell) cutting them at the base with a paring knife. Do not beard the mussels more that a few minutes in advance of the cooking process or they will die and spoil. Set bearded mussels aside.
MUSSELS & CHORIZO
1 T extra virgin olive oil
2 Spanish chorizo sausages, diced
3 plump, fresh garlic cloves, peeled and thinly sliced
3 shallots, peeled and thinly sliced
2 lbs mussels, cleaned
1 t fresh thyme leaves, chopped
1 t fresh oregano leaves, chopped
2 plum tomatoes, seeded and diced
1/2 C dry white wine
1/2 C fish stock or clam juice
2 T unsalted butter
1 t fresh parsley leaves, chopped
Roughly ground black pepper
In large, heavy Dutch oven or deep sauté pan, heat olive oil over medium and add chorizo, garlic and shallots. Sauté until shallots soften and become transparent, about 4-5 minutes. Add mussels, thyme, oregano and tomatoes. Stir well.
Add wine and stock to pan. Cover, and cook over medium heat until the mussels open, about 6-8 minutes. Uncover and simmer for a few minutes to reduce liquid by half. Add butter, and stir vigorously into the sauce.
Transfer mixture to a large serving bowl. Sprinkle with parsley and pepper, and salt to taste. Serve with toasted or grilled slices of artisanal bread rubbed with fresh garlic cloves.