Digging Happy Clams along Nova Scotia’s Shores

by Sadie Beaton
 

Two soft-shell clams enjoying a day at the beach. Illustration by Sydney Smith.

“I love the expression, ‘happy as a clam’”, notes poet Dean Young, in an ode to the oft-overlooked beach resident. “How it imparts buoyant emotion to a rather, when you get down to it, non-expressive creature.”

The soft-shell clams (Mya Arenaria) found deep in mud and sand flats across Nova Scotia’s beaches, bays and estuaries may have chalky, inscrutable faces. This does not, however, mean that these creatures are uninteresting or insensitive. Many of us already know that they are delicious steamed and dipped in garlic butter  - but their sensitivity also makes them tremendously valuable as ecological indicators of good water quality and beach health.

Soft shell clams belong to the animal kingdom family Mollusca, which includes bivalves (two-shelled shellfish), gastropods  (snails) and cephalopods (squids, cuttlefish and octopi). They have a thin, brittle shell of calcium carbonate, hence the name, which sets them apart from their tougher-shelled cousins the quahogs (Mercenaria mercenaria). They’ve also earned the nickname of ‘squirt clam’ or ‘piss clam’, because of their habit of ejecting a spurt of water when disturbed by diggers.

This spurt of water is shot from a distinguishing leathery tube which can be up to three times as long as the shell and encases two well-developed retractable siphons. Voracious filter feeders, soft-shelled clams use their siphons like a snorkel to respire and to filter food particles from the water column. These creatures pump incredible quantities of water through one siphon, often straining two litres or more per hour over their gills, where food particles can collect, and then back out the other siphon. 

Soft-shell clams are “happiest” five to ten centimeters deep in wet coastal sediment where the seawater ‘s saltiness is tempered by a source of freshwater. This makes them especially well adapted to bays, the mouths of estuaries and barachois ponds. Shellfish harvesters, often called “clammers” look for tell tale siphon-holes during low tide, using hand tools to quickly dig down into the sediment, collecting the mature clams in buckets.

Most clam food comes in the form of microscopic plant cells known as phytoplankton, but also includes a helping of microscopic animals, bacteria, dead plant material, and detritus.  In areas where fresh water is polluted, soft-shell clams may concentrate harmful contaminants in their guts. This capacity to concentrate toxins can impact their health and also makes them harmful to eat.

Unfortunately, sewage and septic contamination has compromised beach health and water quality in many important clamming areas, with serious implications for Nova Scotia’s shellfish harvesting industry. The number of beach closures due to water quality concerns has more than doubled in Nova Scotia over the past 15 years at an estimated cost of $8 million each year in lost revenues.

These sensitive, if non-expressive, bivalves serve as a vital reminder of the importance of protecting Nova Scotia’s watersheds. Soft-shell clams also provide an opportunity for communities to monitor the health of their local watersheds and beach ecosystems, and to ask the government for land use policy changes and infrastructure upgrades where and when they are needed.  A beach full of happy, healthy clams means that local septic and sewer systems are in good working order, the local watershed is being protected from runoff and spillage pollution, and that our hard-working clammers are happy, too.

Sadie Beaton coordinates the Coastlines monthly natural history column and is currently craving a feed of local fresh hand-dug non-depurated clams, steamed and dipped in garlic butter. Coastlines is coordinated by the Coastal Issues Committee at Ecology Action Centre and supported by the Nova Scotia Habitat Conservation Fund with contributions from hunters and trappers.

Coastal Issues Committee

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How do you like your coast? Take action on coastal issues that matter to you. The Coastal Issues Committee meets at the EAC on the last Thursday of every month at 5:30PM.