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

Species diversity: moderate → low → high Moderate wave exposure = highest alpha Overall low beta (changeover in species)

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?