The softshell clam (Mya arenaria), which occurs around the Atlantic coast of North America, is a commercially important bivalve with a wide distribution. Certain species of dinoflagellates (such as Alexandrium spp.) can bloom all over the world, including locations with large clam populations. These dinflagellates produce paralytic shellfish toxins (PSTs) capable of causing paralysis in Mya arenaria, who aquire these toxins by suspension feeding on these microscopic algae. Paralytic shellfish poisoning (PSP) results from the ingestion of shellfish which have been recently feeding on the toxic algae. This resulting PSP constitutes a large public health hazard and is the cause for severe economic losses in the shellfish industry on both coasts of North America.
The Connell lab has discovered a mutation in the gene responsible for the voltage gated sodium channel in certain populations of softshell clam. This mutation allows for a greatly increased resistance to PSTs among populations carrying the mutation. While this resistance protects the clams against paralysis, it also allows them to continue feeding during a bloom of toxic algae which leads to a much higher biomagnification of the toxin. This directly affects the shellfish industry as it can increase the severity of possible poisoning. We are currently undergoing further investigation on the scale of this mutation in the wild.
For a more detailed description of the voltage gated sodium channel mutation, click here.