Words: Rachel Hahn
Photography: Bobby Doherty
Two boxes of oysters sit side by side on tidal flat lands that look out onto Barnstable Harbor. They’re the same type of oyster, given the exact same conditions for growth: the same mineral-rich, brackish waters, the same consistent stream of phytoplanktons coming from the creek, and the same amount of monitoring and care. They each have the same life cycle: Oysters spawn in the spring, releasing millions of eggs and sperm that fertilize in the water and grow into free-swimming larvae. After two to three weeks, these floating larvae develop a foot that helps them crawl to the seafloor, where they settle on a rock or another hard surface. They filter up to 50 gallons of water a day, feeding on algae, phytoplankton, and free-floating nutrients, slowly building up their shells until they’re juveniles (aka, spats). In one to three years, they reach full maturation, ready to be harvested, iced, and shucked. But right now, on the Yarmouth tidal flats, oysters in one crate are covered in barnacles while the others are not. Why do some oysters grow barnacles while others don’t?
Rick Binaco, a volunteer with Yarmouth Port’s Mill Creek Oyster Company, posed the question as we peered out into the bay on a gusty early morning in July. We were about to walk a mile into the muck where neatly arranged cages of oysters look more like a land art installation than the eyesore marine equipment I’ve seen in aquariums and laboratories. John and Stephanie Reeve, husband and wife owners of the small oyster farm, come out here most days when the tide is low and the sun is out. When Binaco treks out there with them, his job is to carefully scrape the barnacles off each afflicted oyster. Barnacles and oysters compete for nutrients and sunlight, and the calcified hanger-ons can alter the final shape of a fledgling oyster. And nobody wants to feel a barnacle snag their lip as they suck down one of Mill Creek’s small, sweet bivalves. Binaco likens the practice to gardening — a zen escape from what already seems like a pretty zen life in retirement on the Cape.
When I return home after a few hours of watching the Reeves and Binaco carefully tending to their oysters, I try to find an answer to this Binaco’s question online. Microhabitat conditions like water flow and sedimentation can vary even in close proximity, making some oysters more susceptible to barnacles than others. The texture and topography of each oyster shell also play a role. Healthier oysters can produce biofilms that deter the crustaceans. Maybe it’s the smallest of differences that can bring about the greatest change.
Photography: Bobby Doherty
Thank you: Stephanie and John Reeve / Mill Creek Oyster Co.