Animal-algal Relationships of the Amphipod Hyale Nilssoni (Rathke) in the Rocky Intertidal

Abstract

Hyale nilssoni was the most abundant algal-inhabiting amphipod at two New Hampshire study sites, and algal morphology was important for algal species preference. The filamentous alga Polysiphonia lanosa was readily consumed and the most preferred habitat by H. nilssoni in laboratory and field studies. Laboratory studies showed that in the absence of P. lanosa, II. nilssoni chooses ephemeral algal species over the robust perennials Fucus spiralis and Ascophyllum nodosum for shelter. Polysiphonia lanosa, with its densely and finely branched fronds, was easily clung to, and was available throughout the year.