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Wave Exposure and its Effects on the Diversity of a Shoreline Anne Haley, Lauren Jonah, Riki Krentz, Jessica Hingley & Caroline Méthé Introduction - diversity • Health and survival of ecosystem • 2 variables: richness & evenness • Two diversity indices: Shannon-Wiener and Simpson’s • Physical & biological stressors affect diversity - eg. wave exposure Wave Exposure • Strong influence on diversity • Contradictory past research in animal species • More agreement in botanical species − Greater diversity in wave-exposed Effects of wave exposure • Research question: What is the optimal amount of wave exposure to yield the greatest diversity? • Intermediate Disturbance Hypothesis • Our hypothesis: greater diversity at moderate → high → low • Three sites: low, moderate and high Methods • Indian Point, Greens Point and Bar road • 10 quadrants of 1x1m • 100m transect line Methods • Quadrant counts − Animal counts & estimates − % plant coverage estimates • Unknown species were taken back to the lab for further identification Results • No significant difference between sites − Data was not normalized • Diversity indices − Moderate → Low → High Results - Fauna Results - Fauna • • Species diversity: moderate → low → high • Moderate wave exposure = highest alpha • Overall low beta (changeover in species) Results - Flora Results - Flora • • Species diversity: high → moderate → low • High and low wave exposure = highest alpha • Overall high beta (changeover in species) Discussion • Support for the intermediate disturbance hypothesis − Moderate wave exposure = greatest species diversity • High wave exposure sites did not have greater diversity than sites with low wave exposure • These results were analyzed only on animal species, due to plant abundance was measured in percent coverage Discussion Crashing of waves on intertidal substrate (disturbance): independent variable Habitat disturbances: − Renew limiting resources: oxygen, nutrients − Prevent dominating species Excessive amounts = unsuitable habitat Discussion High Wave Exposure Greater number of plants • Plants are colonizers after disturbance due to succession No barnacles recorded • Desiccation, duration of emergence • Whiplash effect (Grant, 1997) − Fronds physically remove barnacles with wave motion • Interaction with whelks? Discussion Low Wave Exposure Very few plants were found • Soft, muddy substrate which does not provide a surface for fauna to grow Areas for improvement • Samples collected from the immediate surface • Some species gone unnoticed • Brief sampling time (low tide) • Estimations • Varying counting methods • Normalize data • Inaccurate identification • Little differences in barnacle and periwinkle species Conclusions • Species diversity was highest in areas with moderate wave intensity • Proven by the intermediate disturbance hypothesis − Balance of disturbances yields the greatest amount of species richness and evenness → diversity Questions?
