Individual-based modeling of colony growth in an encrusting bryozoan, Watersipora subtorquata

Graduation Date

2014

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Environmental Systems: Mathematical Modeling, 2014

Committee Chair Name

Borbala Mazzag

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Modeling, Netlogo, Encrusting, Colony, Subtorquata, Morphology, Bryozoan, Humboldt State University -- Theses -- Mathematical Modeling, Growth, Individual-based, Watersipora

Abstract

Watersipora subtorquata is a species of marine Bryozoan which has been identified as an invasive species with global distribution. The growth of W. subtorquata is affected by factors related to food availability and environmental conditions. We set out to use individual-based modeling framework to simulate asexual reproduction in young encrusting colonies. Colony growth is determined by a probabilistic mechanism that describes the transition from developing "bud" on the colony perimeter to adult "zooid". Using regular hexagons to model individual buds and zooids, we simulate colony growth over a period of 92 days. The age of a developing bud and the number of adult neighbors are predictor variables for two theoretical submodels which describe the probability of transitioning into adulthood. These two submodels along with two assumptions governing the orientation of zooids relative to their neighbors are used to generate simulation sets to compare to experimental colonies. A measure quantifying circularity is used to compare simulated colonies to data extracted from photographs of colonies grown under two different temperature treatments. Resampling methods are then used to compare the laboratory colony circularity measures to circularity measures of colonies generated by each set of simulations. Along with a basic assumption about the orientation of newly developed zooids at the colony perimeter, we found that letting the number of living neighbors dominate the transition probability submodel generated colonies with circularity measures consistent with W. subtorquata growth in warm water conditions.

https://scholarworks.calstate.edu/concern/theses/ht24wm870

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