Taxonomic changes in mountain zooplankton communities over a 50-year period reveal a loss of calanoid copepods

• Author / Creator

  Keenan, Kathleen M

• Historical species datasets are key to evaluating community responses to long-term environmental change. Yet, ecological studies related to assessing species diversity are often dominated by spatial scales, with less attention dedicated to temporal applications. The main goal of my research was to determine whether crustacean zooplankton communities in 64 lakes along a 1400-m elevation gradient across the Canadian Rocky Mountains have shifted between 1966 and 2017. A generalized estimating equation (GEE) analysis of two measures of community change revealed that cladocerans showed greater taxonomic turnover at lower elevations, while their species richness remained relatively static over time. In contrast, copepods showed a temporal decline in species richness and limited turnover along the elevation gradient. An evaluation of colonization and extinction rates, as related to the Island Biogeography Theory, provided further insight into these patterns. Cladocerans displayed offsetting colonization and extinction events, thereby maintaining relatively constant species diversity. In contrast, copepods did not show compensatory dynamics in that extinction rates exceeded colonization rates, rendering communities less species-rich over time. Further, an analysis of body size revealed the decline in copepod richness may be best explained by the loss of large-bodied calanoids through relatively higher extinction rates across the entire study region. My findings highlight how the survivorship of calanoid copepods may be compromised due to poor dispersal potential, mate limitation and lack of tolerance to increased environmental temperatures.

• Subjects / Keywords

  • Community change
  • Elevation
  • Generalized estimating equation
  • Island Biogeography Theory
  • Zooplankton

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-981n-hr97

• License

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