Patterns in distribution of stream fishes in the Eastern Rivers and Mountains Network: a multi-species occupancy approach

Open Access
Author:
Faulk, Evan Adams
Graduate Program:
Wildlife and Fisheries Science
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 25, 2015
Committee Members:
  • Tyler Wagner, Thesis Advisor
Keywords:
  • streams
  • fish
  • occupancy
  • habitat
  • distribution
  • hierarchical models
Abstract:
Stream fish communities are frequently utilized as bioindicators of water quality and stream ecosystem health, because environmental and anthropogenic processes that control and alter physicochemical properties of streams are often reflected in fish community composition. Research staff of the Eastern Rivers and Mountains Network (ERMN), an Inventory and Monitoring network of the National Park Service, annually monitor core indicators of wadeable stream condition using measures of ecological integrity; however, no continuous stream fish community monitoring existed. Given the usefulness of stream fish as bioindicators and the potential benefits of adding long-term fish monitoring to the ERMN wadeable stream monitoring program, I developed and initiated the framework and methodology of a continuous, long-term fish community monitoring program for ERMN wadeable streams. During spring and summer of 2013 and 2014, an occupancy sampling framework was used to collect stream fish detection/non-detection data at 68 randomly-selected, spatially-balanced sites across two ERMN parks: Delaware Water Gap National Recreation Area (DEWA) and New River Gorge National River (NERI). Hierarchical community occupancy models were used to describe stream fish distribution and determine the relative importance of stream habitat, measured at multiple spatial scales, in structuring stream fish communities. Results indicated that occupancy probabilities and effects of habitat, with respect to direction and magnitude, differed among species. In most cases, natural longitudinal gradients of stream habitat were reflected in species-specific and species group-specific occupancy probabilities, but anthropogenic disturbance (e.g., species introductions, impoundments, deforestation, and water quality impairment) also influenced the frequency of species occurrence and native-introduced species dynamics. These results highlighted the importance of considering multiple processes and spatial scales when studying how stream fish communities are shaped by stream habitat; moreover, that occupancy may be a valuable state variable for use in long-term species monitoring programs.