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Ecology of Atlantic Shores
Personal Info
Field Experiments
Intertidal Zone
Upper Intertidal Zone
Middle Intertidal Zone
Lower Intertidal Zone
Oranisms Involved in Study
Algae (Green, Red, Brown)
Intertida Mollusks
Intertidal Echinoderms
Intertidal Urochordate
Intertidal Arthropods
Types of Competition
-Effects of Competition
Algal Study
Materials & Methods
Positive and Negative Effects of Competitive Interactions

            The positive effect that competitive interactions provide is the ability to "influence the distribution of plants and animals across shoreline habitats (Bertness)."  The creations of abundance of species through competitive interactions produce a positive interaction in the intertidal zone.  Such positive interactions in the intertidal zones are facilitation and mutualism.  Facilitation occurs when an organisms benefits from another organism that does not receive any benefits from the other.  Mutualism occurs when both organisms benefit from each other.  An example of positive interaction in the intertidal zone is when there exists a thick dense algae covering.  This allows other organisms to be protected from desiccation from the sun, and/or harsh weather. 

            The negative effects of competitive interactions occur when there exists a competitive dominance.  Competitive dominance does not necessarily a negative effect, but its most devastating effect on the intertidal community is that it lessens the growth of species richness.  Competition can only increase species richness if a total dominant organism does not exit.  If one were to grow and take over the limited space then growth and species richness would decrease.  But, there is usually a hierarchical food chain, so not one organism can actually take over.  Also, each organism that is in the intertidal zone will introduce an organism that preys on it, a cycle of predation, limiting competitive dominance.  Competition only helps in increasing species richness but we have to be aware of its capability to decrease species richness.  An example of a negative effect of a competitive interaction occurs between the Enteromopha and the Chondurs crispus.  The Enteromorpha can totally decrease the growth of C. crispus by occupying space.  But due to other interactions and mediations, Enteromorpha does not cause an extinction of Enteromopha.