Molluscs and clean water

Long walk today up to Riverside Cemetery in Fairhaven; from there, I walked out on the point for views of the upper New Bedford harbor. Found some of the older gravestones in the cemetery, dating from the late 18th C.

On the walk back, I went down one of the side streets that terminates at the edge of the water. The tide was low, and I was able to walk out onto the shore, mostly sand but with an admixture of mud. A greater diversity of seashells than I had expected: people say that New Bedford harbor is essentially dead, that only killifish and quahogs live in its waters, but that was certainly not true this far up into the harbor. I first noticed some long meandering tracks through the sand of some small gastropod, which proved to be Common European Periwinkles (Littorina littorea). I picked one up by its shell: the mollusc clenched its body into the shell, but after I held it still for fifteen seconds, it relaxed, letting its foot come out, and then its two delicate black tentacles, which it wriggled gently; if the tentacles are where its chemoreceptor cells are located, and if its eyes are at the base of its tentacles, perhaps it was exhibiting a kind of molluskan curiosity. I placed it back on the sand, and it resumed its course down towards the verge of the water.

There was a small patch of salt marsh hay growing from the muck, which, when I got close to it, proved to support a large number of Atlantic Ribbed Mussels (Geukensia demissa), packed in so tightly that their shells touched and it was only in the interstices between the shells that the salt marsh hay could grow. All these living mussels pointed upwards; with the tide so low, they were all closed tightly. In addition to these living molluscs, I saw quite a few shells and shell fragments, of course including Northern Quahog (Mercenaria mercenaria) which is well-known to grow in the most polluted waters of the harbor, but also Atlantic Jackknife Clam (Ensis directus) which we always called “razor clams” when we were children, and Eastern Oyster (Crassostrea virginica).

It was getting late when I stopped at this little beach, and I suspect if I had had more time I could have found a few more species. Given this diversity of species, it may be that the water quality towards the upper end of the harbor (that is, nearer to the Interstate 195 bridge) may be fairly good; and this is the only place in the harbor thus far where I have seen living molluscs.

(Reference: Seashells of North America: A guide to field identification, R. Tucker Abbot (New York: St. Martin’s Press, 1968, 1986, 1996); in the “Golden Field Guide Series”.)

2 thoughts on “Molluscs and clean water

  1. Susan Baker-Schloth

    I am interested in the many species of gastropods and mollusks living in the Atlantic bays and estuaries. My ocean once was the Atlantic Ocean, I grew up near it — maybe 15 miles away. I lived with a Cape Cod husband next to the sea on that strange little hooked piece of land. Since he was a fisherman by trade, I was on the ocean frequently. I remember the Atlantic well – the smell and look and saltiness of it, the waves and surf, the taste of the ocean when you plunge into it on a hot day and the many amazing things living in it.
    Since –I am amazed when visiting Martha and Bob on the Vineyard to find their little beachhead filled with those same sensate impressions and special feelings.

    Now my ocean is the Pacific. I have lived on the West Coast in Oregon for 12 years, another year in Seattle, holidays in the San Juans and in British Columbia, some time spent in San Francisco. The Pacific is grayer, darker, colder and seems more massive than the Atlantic. The small creatures have given way to huge timbers tossed onto the beach on Washington’s Olympic Peninsula and the mussells, oysters, crabs and kelp and large seaweeds are much larger. In Chile where I travel frequently, the Pacific Ocean is waiting there too. No sights of the small sea creatures of the Eastern shores…nada.

    Thanks for the opportunity to write these thoughts.

  2. Administrator

    Hiya Susan — Yeah, but you’ve got really cool birds out there on the Pacific Rim!

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