Where Have All The Limpets Gone?
Like our Irregular Times writer Jim, I had the opportunity to visit the coast of Maine several times back in the 1980s and have vivid memories of the animals that I found living in the slippery, rock-and-seaweed tidal zone. I also remember the bright green and purple sea urchins that were common back then. When I recently took a trip back to the same places I had been to over 20 years ago, I noticed the absence of sea urchins as well.
I also noticed the absence of other animals. There wasn’t a starfish to be seen. Mussels, back in the 1980s, were plentiful in the tidal zone, hanging on to the rocks. Now, all I found were broken mussel shells.
Most alarming to me were the limpets, or rather, the absence of limpets. I looked in several locations, and could not find a single limpet.
A limpet is a mollusc with a single conical shell about the diameter of a nickel or smaller. Its shell has a large opening, which provides the animal a lot of surface area with which to stick to rocks using its muscular foot.
It’s particularly alarming to me that the limpets have gone missing, because they’re not used as seafood and they’re not regarded as pests. So, unlike sea urchins, they’re not simply being overharvested. Something else more systemic has led to the disappearance of limpets along the coast of Maine.
There is a precedent to the disappearance of these limpets. It seems that another species of limpet, the eelgrass limpet, went extinct in the early 20th century. The last time it was seen was in 1929.
An experiment in 1986 on the Pacific Coast found that removal of limpets led to change in the ecological structure of tidal areas. I have not been able to find any scientific confirmation of population decline or extinction of the limpets that were once abundant along the coast of Maine. I know what I’ve seen, but whether there is any marine biologist who is studying the problem, I can’t say.
(By the way, a good discussion of the spelling of the word mollusc -or mollusk – can be found at the site of the Conchologists of America. I love a specialist’s attention to detail.)