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Introduction

Carcinus maenas

Sea star & Mussel

Literina littorea

A. nodosum and L. obtusda

Mytilus edulis Mussel bed

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This project began in the fall of 2004 during my undergraduate work at Clark University. I enrolled in the class Ecology of Atlantic Shores which provided me, for the first time, with the opportunity to conduct some of my very own research. As part of the class we had access to a site on the coast of northern Massachusetts affiliated with Northeastern University. It was here on the rocky shores of the marine research station in Nahant, MA, that it all began.

The rocky inter-tidal zone consists of the area between extreme high and low tides. At Nahant, on the day my samples were collected, the distance between water level and the high tide mark was approximately 45m. There is also great variation in elevation in the inter-tidal due to the rockiness of the coastline. Tide pools and large rocks create a variety of habitats in this area that provide suitable habitat for many of marine organisms.

The organisms often found in the rocky inter-tidal of New England include a number of invertebrate species. The Literina snails, L. littorea, L. obtusada, and L. saxatilis make their home along a vertical gradient in the inter-tidal (see Dani’s site for more information). Other invertebrates include Nucella lapillus (snail), Semibalanus balanoides (barnacle), Mytilus edulis (mussel), Hemigrapsus sanguineus (crab), Carcinus maenas (green crab, see Brigham's site), S. droebachiensis (sea urchin), two species of Cancer crabs and two species of Asterias sea stars (see Judd's site). Of course this list is not exclusive, but these are some of the key players in the inter-tidal.

Algae are extremely important to the inter-tidal ecosystem. Not only do they supply a crucial source of nutrients, they provide substrate for benthic organisms and protection from environmental and biological factors such as desiccation and predation. There are a number of algal species present in the rocky inter-tidal zone. They include Chondrus crispus, usually found in the low inter-tidal along with the Ulva lactuca. The Stramenopiles, Fucus spiralis, Fucus visculosis, and Ascophyllum nodosum are usually found in the mid and upper inter-tidal zones. Presumably these Fucoids are excluded from the lower inter-tidal due to competition and predation of their gametes by juvenile fish and invertebrate species (Knox, George 2001).

The inter-tidal is an interesting ecosystem because it is the edge environment of land and sea. Organisms present in the inter-tidal are subject to the influences of the terrestrial environment such as predation by mammals, as well as influences from the marine environment like wave action and competition among marine animals.

This study looks at the distribution of Ascophyllum nodosum and P. lanosa throughout the inter-tidal. I examine the micro-communities present on the seaweeds at varying tidal heights, further substantiating the importance of Ascophyllum as a foundation species in the rocky inter-tidal of New England.