MSCI Dissertation Qualifying Exam - Brendan TurleyTuesday, August 15, 2017 - 1:00pm
Storms and stratification: drivers of larval fish mortality in the California Current ecosystem
Populations of northern anchovy and Pacific sardine off the coast of western North America are notoriously variable. Recently, the populations of both species have declined to low levels disrupting the food web and forcing the closure of directed commercial fisheries. Because the early-life-history of these fishes is vital to population growth and the California Current is a turbulent upwelling ecosystem, my dissertation will focus on the physical influences on the early stages of these fishes. First, multi-decadal time-series of wind and oceanographic data will be used to investigate sequential patterns of wind events, stratification, and phytoplankton concentrations. Ichthyoplankton data, collected concurrently with physical data and consisting of eggs and larval fish abundances, will be used to estimate larval mortality and compared to concentrations of phytoplankton during turbulent and calm periods. Second, new mortality estimates related to periods of turbulence and calm will be used in a population model to simulate the effects that sequential larval mortality can have on overall population trajectories. Third, output from climate change projection models will be used to investigate the potential changes in the California Current ecosystem relevant to larval fish habitat and survival to the end of the 21st century. The results of my dissertation will provide new evidence concerning the role that wind, stratification, and phytoplankton have on larval fish mortality and population fluctuations.