Event Title

How Do Habitat Connectivity and Dispersal Rates Affect Population of an Imperiled Freshwater Fish?

Presenter Information

Kristen Yeager

Location

Eccles Conference Center

Event Website

http://water.usu.edu/

Start Date

3-29-2011 10:55 AM

End Date

3-29-2011 11:00 AM

Description

The effects of habitat fragmentation on population size, connectivity, and dispersal are important impacts to understand for metapopulations of fishes that occupy stream networks. Using a patch framework, we assessed how habitat connectivity and dispersal affected both population size and trend for an imperiled freshwater fish, bull trout (Salvelinus confluentus). First, we delineated patches of potentially suitable habitat within a large watershed based on a linear relationship between temperature and elevation. Next, we developed a metapopulation model using estimates of population size and growth rate based on empirical studies, and connectivity based upon the patch delineation, to investigate the effect of dispersal rates on population persistence over time. We used exact logistic regression to assess the relationship between species occurrence and patch characteristics, and found a significant positive relationship between patch size and occupancy. Results from the metapopulation model indicated that dispersal significantly decreased patch extinction probability, and even very small rates of dispersal helped mitigate negative effects of stochastic variability on population size. When considered together, these results suggest that in some systems, the trade-off between protecting habitat size vs. connectivity should not be an either/or decision, but that management should be prioritized to enhance connectivity between critical habitat patches while simultaneously maintaining adequate habitat patch size.

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Mar 29th, 10:55 AM Mar 29th, 11:00 AM

How Do Habitat Connectivity and Dispersal Rates Affect Population of an Imperiled Freshwater Fish?

Eccles Conference Center

The effects of habitat fragmentation on population size, connectivity, and dispersal are important impacts to understand for metapopulations of fishes that occupy stream networks. Using a patch framework, we assessed how habitat connectivity and dispersal affected both population size and trend for an imperiled freshwater fish, bull trout (Salvelinus confluentus). First, we delineated patches of potentially suitable habitat within a large watershed based on a linear relationship between temperature and elevation. Next, we developed a metapopulation model using estimates of population size and growth rate based on empirical studies, and connectivity based upon the patch delineation, to investigate the effect of dispersal rates on population persistence over time. We used exact logistic regression to assess the relationship between species occurrence and patch characteristics, and found a significant positive relationship between patch size and occupancy. Results from the metapopulation model indicated that dispersal significantly decreased patch extinction probability, and even very small rates of dispersal helped mitigate negative effects of stochastic variability on population size. When considered together, these results suggest that in some systems, the trade-off between protecting habitat size vs. connectivity should not be an either/or decision, but that management should be prioritized to enhance connectivity between critical habitat patches while simultaneously maintaining adequate habitat patch size.

https://digitalcommons.usu.edu/runoff/2011/Posters/5