David,

I'm not surprised at all the fornicata on Martha's Vineyard!

Humor aside, I have done similar retracing on and near Galveston Texas and have found populations of certain species to rise and fall with the climatic conditions (i.e. - 22 year solar cycle), and human influences such as general pollution and turbidity, or chemical spills in Galveston Bay.  Some species have never returned, whereas the grasses never came back after events.

One such spot on Galveston Island is at the mouth of Offatt's Bayou, a location which I have monitored off-and-on for 35 years or so, and is often exposed during winter low tides.

In the early 1980's I watched the grass die off at this location.  A combination of refinery pollution golf-course fertilized, and an extremely harsh winter. It was the only Galveston Bay locality I knew of Cerithid populations (Cerithidea pliculosa, and Bittium varium).  There are also beds of Tagelus plebeius and Ensis minor, which seemed to play tug-o-war for territory.  There was some 5 Oyster species, and 4 mussels. Generally the larger gastropods were limited to Littorina, Sharks Eyes, Thais, Lightning and Pear whelks.  I also cataloged 7 species of Crabs there in 1978.

I have not surveyed it in about 5 winters to see what the heath and diversity levels are, ...and certainly not since Hurricane Ike. Perhaps it is about time....

I do still visit the spot a couple times a year and park and look across the bay, often just to watch the sunset.

Les

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