Previous Research

Prior to being a data sharing and open science advocate, I was a marine scientist. Projects I worked on are below.

Development of a population model for invasive species

SupervisorsMark Lewis at the University of Alberta Centre for Mathematical Biology and Claudio DiBacco at Dalhousie University and the Bedford Institute of Oceanography.

I was funded by the Canadian Aquatic Invasive Species Network (CAISN) to explore the use of copepod population models to understand the potential for invasion via ship ballast water.  I reared the estuarine copepod Eurytemora affinis in the laboratory under a suite of environmental characteristics.  This work was conducted at the Department of Fisheries and Oceans Center for Aquaculture and Environmental Research in West Vancouver, BC.  I used the data collected during these experiments to parameterize a population model that describes population growth rate as a function of temperature and salinity.  See Strasser et al. 2011. (OA copy available here).

Demographic model of the endangered North Atlantic Right Whale

SupervisorHal Caswell, Woods Hole Oceanographic Institution

I used a matrix model of the endangered North Atlantic Right Whale to understand its population dynamics and predict its future success.  I used the photographic identification catalogue and multi-stage mark-recapture methods to produce maximum likelihood estimates of population parameters, such as stage-specific survival, breeding, and maturation rates. I applied information-theoretic methods to identify the most well-supported model out of several possibilities, then constructed deterministic and stochastic matrix population models.  From these, I obtained maximum likelihood estimates of the population growth rate, net reproductive rate, life  expectancy, and current population size.

Metapopulation model of a harvested shellfish population

SupervisorsMike Neubert and Hal Caswell, Woods Hole Oceanographic Institution

I developed and implemented a theoretical model to explore metapopulation dynamics when a population is subjected to stochastic environmental variability, with a focus on the softshell clam, Mya arenaria.  Studies of time-invariant matrix metapopulation models indicate that metapopulation growth rate is usually more sensitive to the vital rates of individuals in high-quality patches than in low-quality patches. This suggests that, given a choice, management efforts should focus on preserving high-quality patches. I examined the sensitivity of metapopulation growth rate for a two-patch matrix metapopulation model, with and without stochastic disturbance, and found cases where managers can more efficiently increase metapopulation growth rate by focusing efforts on the low-quality patch.  This was a surprising result, with implications for management of not only M. arenaria, but also for other spatially structured populations. See Strasser et al. 2010. (OA copy available here).

Development of bivalve shell chemistry as a natural tag of habitat

Supervisors: Lauren Mullineaux and Simon Thorrold, Woods Hole Oceanographic Institution

Calcium carbonate composition of some tracers depends primarily on water chemistry and can therefore be used as a natural tag of an organism’s environment.  This technique has proven successful in studies of fish connectivity.  In an effort to develop larval shell chemistry as a natural tag, I used experimental manipulations to determine how the environment (temperature and salinity) and physiology (growth rate and age) influences carbonate chemistry in M. arenaria (Strasser et al. 2008a, Strasser et al. 2008b).  I also investigated potential methods for identifying larval signatures on juvenile bivalves, concluding that further technological advances in measurement capabilities are required before the approach can be applied effectively in some taxa (Strasser et al. 2007).

Population genetic study of softshell clams in the Northwest Atlantic

Supervisor: Paul Barber, UCLA (formerly of Boston University and MBL)

I pursued the use of genetics as a natural tag of environment to estimate gene flow.  I investigated the genetic structure of M. arenaria populations across the current distribution of the species, testing for patterns of regional differentiation.  I found that populations exhibited extremely low genetic variation, with a single haplotype of the mitochondrial COI gene dominating at all of the sites. Populations sampled outside of the Northwest Atlantic exhibited higher diversities despite their more recent introduction.  This work had implications for management of M. arenaria: one of the most commonly used management strategies for increasing softshell clam populations in New England is by seeding less productive flats with juvenile clams that usually originated from other locations. My work suggested that this management strategy is not likely to significantly impact the regional distribution of genetic variation. See Strasser and Barber 2009. (OA copy available here).

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