Adult demography and larval processes in coastal benthic populations intertidal barnacles in Southern California and Baja California

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2005
The geographic distribution and dynamics of coastal benthic populations are shaped by physical biological interactions affecting larval dispersal and the demography of juvenile and adult individuals. This thesis focused on nearshore patterns of larval distribution and regional patterns in demography of intertidal barnacles in Southern and Baja California. Horizontal and vertical distributions, and the mortality rates of larvae, were assessed from short tenn (i.e. days) smallscale observations (0.1-1 km) in nearshore waters. Observations on spatial variability of adult barnacle demography were gathered over 1.5 years at scales of hundreds of kilometers. Stage-specific horizontal distributions and nearshore current measurements suggested that larvae of Balanus glandula and Chthamalus spp. may experience limited dispersal. High mortality rates could further limit travel distances and the exchange of individuals among disjunct populations. Data on vertical distributions indicated that nauplii and cyprids of Balanus nubilus and Pollicipes polymerus occur at different depths. Nauplii remained near the surface at all times, whereas cyprids occurred in the bottom half of the water column. Such distributions, combined with vertical variability in horizontal flows, might cause the observed horizontal segregation ofnauplii and cyprids. Differences in survival, growth rate,· size structure, and per capita fertility of adult Balanus glandula were observed between Dana Point (Southern California) and Punta Baja (Baja California), a site located near the species' southern limit of distribution. Effects of spatial differences in demography on population persistence were assessed with a stage-structured matrix model. Model analyses indicated that the Punta Baja population is more susceptible to environmental stochasticity and more prone to local extinction than populations located further north. This thesis emphasizes the importance of characterizing factors that affect the dynamics
I must thank the Chilean MIDEPLAN (Ministerio de Plartificacion y Cooperacion), which provided funds for the first three years of my doctoral studies through a Presidential Fellowship (Beca Presidente de la Republica). Tuition, stipend, and research funds for the rest of my time. as a Joint Program student carne from National Science Foundation grants OCE-0083976 and OCE-9986627 to my thesis supervisor (Jesus Pineda), and through the WHOI Academic Programs Office.