27 December 2009

Monocacy flood and terrestrial gastropods

Yesterday's relatively warm weather and day-long rain suddenly melted most of the snow from last weekend. So today, taking advantage of the mild weather, we went on the last field trip of 2009. When we were on MD144 crossing the bridge over the Monocacy River east of the city of Frederick, we noticed that the west bank of the river south of the bridge was flooded.

MonocacyFlood

In this picture the river itself is the narrow line of water below the hill and behind the row of trees in the back. The "lake" in the front is a flooded farm field. The next picture, taken from the river side, shows the same field at the end of November during our previous field trip.

MonocacyField

Several species of snails, notably the ubiquitous Ventridens ligera, and several species of introduced slugs, Limax, Arion and Deroceras, live in the narrow strip of woods along the river. Obviously, this wasn't the first time the banks of the river were flooded. So how do the terrestrial snails and slugs survive the floods?

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