Presenter: Alyssa Bjorkquist
Faculty Mentor: Richard Emlet, Kelly Sutherland
Presentation Type: Poster 47
Primary Research Area: Science
Major: Marine Biology, Psychology
Funding Source: Undergraduate Research Opportunity Mini-Grant, UROP, $1000
Pisaster ochraceus (the Ochre Sea Star) is a keystone species in the NE Pacific whose role as an ecological engineer influences intertidal diversity by predating on space-competing organisms. Individuals inhabit a broad range of habitats ranging from sheltered coves to exposed cliffs and experience large temporal and spatial variability in water flow throughout their lifetime. However, it is largely unknown how sea star body shape changes between wave- exposed and wave-sheltered environments throughout an organism’s lifetime. Wave exposure was measured at each study site near Charleston, OR using dissimilar metal dissolution and intertidal zonation of sessile organisms. Furthermore, I analyzed how aspects of juvenile and adult P. ochraceus morphology differed between sites as functions of wave exposure.
Sites with more wave exposure were associated with greater anode mass loss over time (F1,30 = 256.21, p < 0.001) and broader vertical zone boundaries relative to mean water level than sheltered sites (F2,8 = 3.03, p < 0.01). Adult sea star populations from wave-exposed sites had longer, narrower arms and smaller central discs relative to individuals from sheltered habitats for a given weight (F2,152 = 70.0, p < 0.001). Juveniles appeared to exhibit similar morphological trends but results were inconclusive. The relationship between wave exposure and sea star morphology indicate that hydrodynamic conditions play a large role in shaping sea star development and environmental adaptability post-larval metamorphosis.