First visual record of rare purple-colored dogwhelks ( Nucella lapillus) on the Atlantic coast of Nova Scotia, Canada

The dogwhelk Nucella lapillus is a rocky intertidal gastropod of the North Atlantic coast. Individual shell color varies. Common colors range between white and brown, with darker dogwhelks being more affected by heat stress than lighter-colored conspecifics. Other reported shell colors are purple, black, mauve, pink, yellow, and orange from UK coasts, red and gray from the Bay of Fundy coast of New Brunswick and Nova Scotia (Canada), and purple, black, gray, yellow, and orange from the coasts of Maine and Massachusetts (USA), with purple being considered as a rare color. On the Atlantic coast of Nova Scotia, dogwhelks are active from April until November, but information on dogwhelk shell color is missing for this coast. On 16 June 2016, we found two purple-colored dogwhelks in the mid-to-high intertidal zone of a moderately wave-exposed rocky shore near Duncans Cove, on the Atlantic coast of Nova Scotia while collecting dogwhelks (n= 1000) during low tide for manipulative field experiments. All other dogwhelks collected on that day were of common white and brown colors. During earlier dogwhelk collections in Atlantic Nova Scotia (between 2011-2013) and field surveys in Duncans Cove (between 2014-2016), we did not find any purple-colored dogwhelks, indicating the rareness of this color in that region. Apparently, our observations provide the first visual record of rare purple-colored dogwhelks on the Atlantic coast of Nova Scotia, Canada.