If you think the two pictures in this post look the same, then you are nearly right! They both show the same degree of infestation damage from marine worms of the P. ciliata type – but the image above showing a Flat Oyster shell riddled with u-shaped burrows was dredged from Poole Harbour in Dorset in 1989. The image below shows similar infestation characteristics. However, 1,200 years separate the two specimens since the shell below was recovered from the archaeological excavations of Saxon Southampton, Hampshire, at Melbourne Street.
Although the level of infestation in these individual shells looks alike, the proportion of oyster shells affected in the respective samples was different: with a smaller number of oyster shells like this in the Saxon sample. Examination of many oyster samples from all historical periods during the last two thousand years in Southern England seems to demonstrate that the level and intensity of infestation by marine polychaetes has increased through time and is at its highest level in the twentieth century. It is possible to speculate that this may be, at least in part, the result of present day nutrient enrichment of coastal waters by, for example, run off water from fertilised arable land.
COPYRIGHT JESSICA WINDER 2011
All rights reserved