Claremont McKenna College
Ecological research on rocky intertidal ecosystems has increasingly focused on the regional oceanographic processes that shape community structure over functional group interactions. Intertidal communities’ dependence on onshore and offshore transport of intertidal species larvae, dissolved inorganic nutrients, and phytoplankton signal that upwelling and nearshore currents can have an influential role in determining the growth and composition of intertidal systems. The community structure of rocky intertidal areas was compared between two locations along an upwelling gradient in the Gulf of Panama: Nueva Gorgona, with intermittent seasonal upwelling, and Playa Venao, with fringe seasonal upwelling. The surface cover of algae, barnacles, and mussels, along with species richness, abundance, diversity, and evenness were determined using threaded quadrats along transect lines set parallel to the shoreline in low, medium, and high tide zones. Sites in Nueva Gorgona, the central upwelling location, were dominated by mat-forming barnacles and mussels as well as aggregating anemones. Barnacles were also the largest surface occupiers in Playa Venao, the location on the edge of upwelling, whose sites had a comparatively high abundance of gastropods. Statistically significant differences were detected in species richness and abundance as well as algae and mussel cover between the two locations, potentially indicating an influence of nutrient and planktonic transport on Nueva Gorgona’s community structure from upwelling and shelf currents. Across most variables, tidal zones were distinct from each other in both locations. Additional significant differences were detected between sites in each location, most notably in barnacle coverage and species abundance, which indicates that neighboring sites had a high potential for variation. Tidal elevation and hyperlocal differences—including sedimentation, rocky surface complexity, and surf activity—likely played a greater role in sculpting the two rocky intertidal systems than regional dynamics.
Biodiversity | Environmental Indicators and Impact Assessment | Latin American Studies | Marine Biology | Oceanography | Zoology
Brady, Claire, "Rocky intertidal community structure along an upwelling gradient between Playa Venao and Nueva Gorgona on Panama’s Pacific coast" (2023). Independent Study Project (ISP) Collection. 3646.