Decomposing Codium Causing Stench

Harwich Natural Resources Special Report (7/24/98)

Codium "seaweed" piled deep along Bank Street Beach in Harwich Port is causing an unpleasant odor at the beach

    By Tom Leach

    The Codium known locally to commercial fishermen as spaghetti grass is being coughed up by Nantucket Sound, where it lays and grows in the shallows in great mass where the primitive plant can gain everything it needs, fertilizer from near shore nitrogen sources and sunlight. The southwesterly storms and surf then toss the unanchored "weed" high up on the rack line, to the bane of all that frequent the beach. Here the weed rots as it dies producing an offensive septic smelling methane gas bringing complaints, often neighbor accusing neighbor of septic system failure. The Harwich Highway Department has been on top of things on the Town side. Highway Superintendant Alice Norgeot has been sending trucks and equipment regularly to the public beaches to remove the never ending piles of the stinky weed in this endless battle against nature. When the beach is cleared of nearly every shred, the ocean serves up another batch of green weed with the next southwesterly and high tide.

    Certainly the worst thing you could do is bury the spaghetti grass in a shallow beach grave as was attempted at Old Mill Point. The most offensive odorous areas walking along the beach are noted where the Codium has been naturally covered or buried shallow by the beach sand. Then the rotting seems to emit a more intensive gas upward through the sands. You get within 200' of these spots and the nose immediately picks up the scent.

    Marine algae are causing great concern as they incite blooms and mass entanglements in salt as well as fresh-water systems outside of their native range. We have heard two plausible stories about the of how non- indigenous Codium reached Cape Cod waters. It was introduced into the North Atlantic via water ballast from ships arriving from the Pacific and/or it was introduced to New England attached to Pacific oysters in an aquaculture experiment in the late sixties.

    Either way, the seaweed's population has exploded as their seems no predator or grazer in our local waters interested in making this "spaghetti" part of its diet. Instead the macro algae blooms unchecked. This nuisance seaweed consists of a body of spongy, siphonous tubes that interfere with recreational swimming and impact mollusk populations. In the early 70's Morris Johnson of Yarmouth Natural Resources attempted to have the shellfish bed choking weed dragged from Lewis Bay. It was determined these attempts were futile and in fact if the strands of the weed were broken into pieces each piece would become its own plant exasperating the situation. Left to its own however, the codium is seen anchoring itself to rocks and shells of often live shellfish. In areas of Bay Scallop beds, live scallops are often dragged ashore by the attached codium.

    Codium as all green algae are primitive chlorophyll containing plants which during sunny days produce oxygen. However, during cloudy days, nighttime and winter when the sun is low in the sky the algae turns its physiological system around and become an oxygen user. In embayments algaes send dissolved oxygen levels plummeting and thus stress out the oxygen dependent marine ecosystem.

    We are seeing large increases of other macro algae also, including several types of red wool, sea lettuce ulva, and a green stringy variety of algae called enteromorpha. Chatham weir operator Mark Simonitsch along with other trap fishermen this season noticed that the red wool floated in the water column and was easily getting caught on the leader nets or "fence" of each weir running to and from shallow water to the heart of the trap. So much so that the added resistance from the red wool plugging up the fence netting caused the leader poles to bend over with the ebb and flow of the tide. This annoying condition they point out as new. Fishermen often think like scientists, and though they always remember the red wool, they point out that it has never been in the east end of Nantucket Sound with such abandon and are concerned that the increase in macro algae may be due to the general increase in nitrogen outflow on the elbow of the Cape.

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