Albion College Mathematics and Computer Science Colloquium

Title: How does variation in life history strategies effect long term population trajectories of eelgrass?
Speaker:Stephanie Thurner, '17
Senior Mathematics Major
Albion College
Albion, Michigan
Abstract: Seagrasses are important habitat forming marine angiosperm in coastal ecosystems. Contemporary declines in seagrass habitats worldwide warrant understanding factors that may allow managers to predict change and recovery in these habitats. In the Pacific Northwest, eelgrass (Zostera marina) forms these critically productive meadows and has experienced instances of localized population decline. These site specific declines are often persistent, lacking natural recovery. In an attempt to combat these declines, human aided restoration is endeavored with worldwide success rates around 30%. Eelgrass reproduces using two different life history strategies, asexual and sexual reproduction, with varying life history strategies between populations. It is unknown how variation in life history strategy affects the long term population trajectories of eelgrass. In this study we develop a stage-based matrix population model, parameterized by field data collection, previous experiments, and data mining to map the effects of life history variation on population growth. The eelgrass lifecycle was mathematically defined as three stages (vegetative shoots, flowering shoots, and seeds) as well as by the vital rates describing the transitions between these stages (branching rate, flowering rate, fecundity, germination rate, and seedling survival rate). By analyzing populations with variations in sexual and asexual reproduction and validating the model through a comparison with a long term field study experiment, we saw that the model is a highly conservative estimate for solely sexually reproducing populations, and an over estimate for populations with asexual reproduction. When the field recovery experiment was analyzed, we could also see that recovery of a population back to initial population levels after a disturbance is different when density is determined spatially rather than by looking at the entire area. Further data collection and refinement of vital rates as well as the addition of other environmental conditions will increase the accuracy of the model and help inform management and conservation strategies.
Location: Palenske 227
Time: 3:30 PM

author  = "{Stephanie Thurner, '17}",
title   = "{How does variation in life history strategies effect long term population trajectories of eelgrass?}",
month   = "{1 December}",
year    = "{2016}"