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Report: Barnstable Sea Farms, Oct 25th, 2011 Jeanette Wheeler, WHOI/MIT Joint Program Graduate Student Fall Semester “Marine Invertebrates of Cape Cod” Oyster Farming at Barnstable On October 25th, we visited one of the oyster production sites of Barnstable Sea Farms in Barnstable Harbour. The charmingly incomplete website can be found here: http://www.barnstableseafarms.net/ Click on “staff” to get some idea of the charmingness. Oyster farming is a productive and lucrative trade in Barnstable, bringing in over 2.5 million dollars per year to the community. We visited a two acre plot on the mud flats of Barnstable Harbour, where multiple year classes of oysters are reared during the spring-fall months. The oysters are eastern oysters (Crassostrea virginica) and are non-spawning triploids. These are specifically developed to waste no energy on spawning and therefore produce a faster-growing, higher quality oyster. In the spring, a first year cohort will be initially kept in a fine mesh bag with approximately 6000 individuals. The oysters are moved to larger raised mesh bags as they grow (the bags are kept raised according to a curious Massachusetts state law). The bags are covered with seawater as the tide comes in, and the bags have some amount of biofouling (primarily barnacles and an unidentified tunicate), though biofouling is considerably worse closer to the edge of the channel. An example of tunicate biofouling. The oysters must be removed from the water prior to the winter, because low water temperatures (<28oF) will cause ice crystals to lacerate their organs if they are moved beyond this point. Interestingly, a first year cohort can be removed from the water and kept in a walk-in cooler (at 38o F) in coolers with some snow shoveled on top of them, and they will hibernate or suspend development until replaced in seawater (~50o F) in the spring. This is a property of the first year cohort only. In the second year, the cohort is placed in an open topped cage on the mud flat. The second year cohort oysters reach legal selling size (3 inches across) usually by September. Despite their relative unguardedness, predation is uncommon, with human activity being attributed for most predation in the population. Barnacles are knocked off the shells by hand before they are sent to market, as dead barnacles impart a less than pleasant odor to still-live oysters. Other Invertebrates at Barnstable Annelida: The most obviously abundant polychaete species on the mud flats were Diopatra (maybe Diopatra cuprea?) polychaete worms, identified by their characteristic debris-covered tubes which protrude from the sediment. The other commonly found polychaete was a Hydroides species colonizing the insides of old oyster shells surrounding the farm. We also found a sipunculan, a peanut worm, on our walk back, a lucky find because it was certain to show up on our final exam and nobody had any chance of identifying a sipunculan as an annelid otherwise (lack of segmentation). Mollusca: We found three species of Crepidula (fornicata, plana, and convexa) colonizing various mollusc shells on the mudflat. On the right is a horseshoe crab molt with colonizing crepidula species. We found very abundant mud snail (Ilyanassa obsoleta) populations on the mud flat, probably the most commonly seen gastropod. We also found a moon snail (family Naticidae), as pictured, as well as softshell clams (Mya arenaria), quahogs (Mercenaria mercenaria), bay scallops (Argopecten irradians), blue mussels (Mytilus edulis), jingle shells (Anomia simplex) and a razor clam shell fragment on a Diopatra tube. Arthopods: We found multiple species of crab: rock crab (Cancer sp.?), a sadly homeless hermit crab (family Paguridae), green crab (Carcinus maenas), and carapaces of horseshoe crab (Limulus polyphemus) and spider crab (Libinia sp.?).