The Study of Interactions between mussels and their Environment, as well as, between different species of intertidal organisms within a particular Intertidal Community
By Arlene Reynolds
California State Polytechnic University, Pomona, CA
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Abstract. (The relationship between mussels and intertidal organisms within a particular community in the intertidal zone is a great example of the competitive exclusion principle. The alternative hypothesis for this study would be that there is a direct relationship between organisms due to interspecific competition,

Introduction: California mussels (Mytilus californianus) are abundant where there is surf along the outer coast. They form massive beds, sometimes several meters across, on surf exposed rocks and wharf pilings in the upper middle intertidal zone and offshore, up to 24 meters deep. Like barnacles, mussels like to gather in dense clusters in the middle intertidal zone. Mussel beds are often large enough to be a home to many other creatures, like snails and worms. California mussel beds accumulate a gritty mixture of sand and bits of shell which provide a home for a various assemblage of animals including a number of polychaete worms, snails, crabs and a blackish sea cucumber. The Ochre sea stars are California mussels' main predator. Ochre sea stars affect the distribution of the mussels because the sea star generally occurs lower on the shore than the mussels and moves up to feed during high tide. Mussels are also eaten by shorebirds, crabs and snails. When a predator eats the dominant species, then predation may prevent the dominant species from monopolizing a limited resource, thereby increasing diversity of species in that area. Mortality in intertidal open coastal environments is often high, resulting from battering driftwood and other debris, wave pounding, predation, desiccation, and disease.