How to quantify aquatic connectivity?: verifiying the effectiveness of the dendritic connectivity index as a tool for assessing stream fragmentation

Bourne, Christina (2013) How to quantify aquatic connectivity?: verifiying the effectiveness of the dendritic connectivity index as a tool for assessing stream fragmentation. Masters thesis, Memorial University of Newfoundland.

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Abstract

In recent decades the study of landscape ecology has moved beyond its terrestrial roots to explore the impacts of habitat fragmentation in aquatic systems, where populations of freshwater fish are declining at an alarming rate worldwide. Quantifying fragmentation within these habitats has been a challenge for ecologists, as the spatial arrangement of stream networks influences the distribution of both organisms and habitat features. I used the dendritic Connectivity Index (DCI) to evaluate aquatic connectivity in Terra Nova National Park, Newfoundland, and Prince Edward Island National Park, testing the impacts of barrier assessment methods and inclusion of biological data in the index to evaluate functional connectivity. I found that while the passability values of individual barriers (road culverts) can vary widely with assessment methods, connectivity estimates provided by the DCI for entire catchments did not show the same degree of variability and overall assessment results did not change when using different methods. When a Functional parameter (biomass) was substituted for structural one in the DCI, connectivity values for catchments changed, but not significantly. These simulations demonstrated that the DCI is a robust tool for evaluating stream connectivity which can provide meaningful results to managers, even when resources and data are limited.

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