Though these diseases do not pose a threat to human health, the warm-water bacterium Vibrio vulnificus does. Responsible for 95 percent of all seafood-borne deaths, according to an article published last year in the journal Microbial Ecology, the naturally-occurring bacteria historically has not been found in northern latitudes. But recent reports place it as far north as Alaska, said Barbara Brennessel, a biology professor at Wheaton College in Massachusetts and author of the book Good Tidings: the History and Ecology of Shellfish Farming in the Northeast (University Press of New England, 2008).
Even more alarming than the spread of disease, said Rheault, is the rate at which the ocean's chemistry is changing. As the globe warms, more carbon dioxide enters the oceans, acidifying the water. This spells trouble for shellfish that depend on a higher pH in order for their hard shells to form properly.
While ocean acidification has yet to plague the East Coast oyster industry, hatcheries in Oregon have struggled with persistent production failures, as oyster larvae fail to survive in more acidic waters.
"Carbon dioxide from the atmosphere is entering the ocean almost everywhere, but local environmental conditions can magnify its effects," said Sarah Cooley, a marine chemist at Woods Hole Oceanographic Institute in Massachusetts. "Ocean acidification effects will likely become obvious on the East Coast within the next few decades," she said.
But when you are out on a boat, trying to make a living off the sea, 20 years can seem like ages.
"Climate change is not something I worry about on a daily basis, but I am becoming more aware of it," said Arnoux, who started growing in 2005 in the same lagoon where Opton-Himmel tends his plot. Still, he's in it for the long haul, and Arnoux sees himself preparing for an uncertain future by branching out into other species, such as scallops, across several locations.
Opton-Himmel doesn't see himself exclusively farming oysters either. Though he continues to expand his business, he does some environmental consulting on the side.
Back on shore, warm thermos in hand, he pauses to mull the need for a Plan B before packing up his truck and heading to Maine for a few days to work on a consulting project. "So many things could go wrong. It's so risky."
This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.