No. 26–Questions and Answers
Q. At some point during every beach walk I conduct, someone will ask what makes the holes with the little pellets around them.
A. More closely related to hermit crabs than shrimp, there are three species of ghost shrimp which burrow in the lower intertidal and sub tidal sands of our beaches that are responsible for the holes in question. The largest of these is the Carolinian ghost shrimp, Callianassamajor. It may reach four inches in length and burrow tunnels of up to six feet. Water observed welling from the holes is being pumped by a rapid pulsating movement of the creature’s abdominal appendages as it cleans house, so to speak, expelling excess sand and the fecal pellets observed around the hole.
Q. My very inquisitive grandson, visiting from Chicago, brought in a jar of water with seaweed from our floating dock. There was a tiny shrimp and other small critters both on the seaweed and swimming around. He’d like to know what they are.
A. They are crustaceans in the 6,000 plus strong Pericardium order, Amphipoda. While most Amphipods are benthic (live on the bottom), there are a number of species that reside in and upon alga, hydroids and bryozoans attached to your floating dock. Hydroids and bryozoans, by the way, are animals. They just get lumped in as seaweed because they look like plants. Your grandson can go on line, key word amphipod, and find a number of sites with photos and drawings of some very interesting creatures. He might check out the copepods and isopods while he’s at it.
Q. A friend told me he caught and ate a ten inch black sea bass from his dock, I thought black sea bass were off shore on the wrecks.
A. One of the reasons estuaries are so important is that they serve as nurseries for many near and off shore fish species. Black sea bass spawn off shore with the fry migrating to the estuary where they will spend a year or more growing before returning to the sea. A ten or eleven inch sea bass has a lot of meat on it and unfortunately a lot of people keep and eat them. Black sea bass are now a species of concern with regard to their dwindling numbers. Please encourage your friend to release any he may catch in the future. Red drum, spadefish, southern flounder and gray snapper are some of the other species who’s fry seek estuarine shelter and food sources.
Q. Someone told me that snails were eating up the marshes. Is that true and if so, what kind are they and what is being done about it?
A. The snail of concern is the salt marsh periwinkle, Littorina irrorata. It’s the white snail observed on spartina grass. There is a growing body of evidence that the species became a serious problem in some parts of its range during the draught that enveloped the southeast beginning in 2000. It had long been accepted scientific fact that draught negatively impacted salt marsh plant life through degraded soil conditions brought on by higher salinity due to the reduced volume of fresh water entering estuaries exacerbated by high summer evaporation rates. Ongoing research now supports the view that draught also triggers large concentrations of snails to move in mass on draught weakened spartina. The snails do their damage by slicing the stems which encourages a fungal growth which the snails feed on. Spartina grass is apparently able to tolerate this feeding behavior under normal climatic conditions but unable to withstand the onslaught when weakened by draught. I received an article,www.sciencedaily.com/release/2005/12/051219091308.htm, in December “05 that goes into considerable detail on the subject. It is available on line at the address given.