Bacterial colonization and extinction on marine aggregates: stochastic model of species presence and abundance

• Published in: Ecology and evolution 2013-11, Vol.3 (13), p.4300-4309
• Main Authors: Kramer, Andrew M., Lyons, M. Maille, Dobbs, Fred C., Drake, John M.
• Format: Article
• Language: English
• Subjects: Aggregates; Aquatic habitats; Aquatic pathogens; attached bacteria; Bacteria; Colonization; Computer simulation; Density; Disease transmission; Ecological effects; Ecosystems; Endangered & extinct species; Extinction; Laboratories; microbial population dynamics; Model testing; organic aggregates; Original Research; Pathogens; Shellfish; Species; stochastic extinction; Stochastic models; Stochasticity; waterborne disease
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.789

Organic aggregates provide a favorable habitat for aquatic microbes, are efficiently filtered by shellfish, and may play a major role in the dynamics of aquatic pathogens. Quantifying this role requires understanding how pathogen abundance in the water and aggregate size interact to determine the presence and abundance of pathogen cells on individual aggregates. We build upon current understanding of the dynamics of bacteria and bacterial grazers on aggregates to develop a model for the dynamics of a bacterial pathogen species. The model accounts for the importance of stochasticity and the balance between colonization and extinction. Simulation results suggest that while colonization increases linearly with background density and aggregate size, extinction rates are expected to be nonlinear on small aggregates in a low background density of the pathogen. Under these conditions, we predict lower probabilities of pathogen presence and reduced abundance on aggregates compared with predictions based solely on colonization. These results suggest that the importance of aggregates to the dynamics of aquatic bacterial pathogens may be dependent on the interaction between aggregate size and background pathogen density, and that these interactions are strongly influenced by ecological interactions and pathogen traits. The model provides testable predictions and can be a useful tool for exploring how species‐specific differences in pathogen traits may alter the effect of aggregates on disease transmission. Organic aggregates provide a favorable habitat for aquatic microbes, are efficiently filtered by shellfish, and may play a major role in the dynamics of aquatic pathogens. We develop a model for the stochastic dynamics of an “average” pathogen species on such aggregates. Model results suggest that presence and abundance are nonlinearly related to bacterial density and aggregate size and provide useful insight into how species‐specific differences in bacterial pathogen traits may alter the effect of aggregates on disease transmission.