LITTORAL COMMUNITIES AND ZONATION ON ROCKY SHORES IN THE BAY OF FUNDY, CANADA - AN AREA OF HIGH TIDAL RANGE

The Bay of Fundy, on the east coast of Canada, has a maximum tidal ran ge slightly higher than that of the Bristol Channel and similar enviro nmental conditions, but a more extreme climate. However, the littoral community, despite the common presence of many species, differs greatl y. Fundy shores show universal domination by Ascophyllum nodosum under all exposure conditions and its biomass is very high. Fucus vesiculos us is common but its distribution is unrelated to exposure. Fucoid alg ae normally cover all but a few percent of the midlittoral. As a conse quence of this intertidal primary primary productivity is very high an d a protected sub-canopy environment very extensive. The standard litt oral zones do show a typical pattern but respond only slightly to expo sure. Many typical and important species show constant zonation under all exposure conditions. Typical of this group are A. nodosum and the other fucoid algae. Although the high tidal range does reduce the effe ct of wave action, this factor alone does not explain the results sinc e they are not repeated in the Bristol Channel. Differences in the sui te of herbivores, particularly the absence of Patella species in Fundy , is considered to be an equally important causative factor. Also sign ificant is the modifying effect of the heavy algal canopy itself Clear ance experiments have shown that dominance by A. nodosum is not restor ed within 10 years and that herbivory, especially by littorinids and l impets, does play a critical role in succession.