Portage connectivity does not predict establishment success of canoe-mediated dispersal for crustacean zooplankton |
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Authors: | Ashley D Stasko Theresa Patenaude Angela L Strecker Shelley E Arnott |
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Institution: | (1) Department of Biology, Queen’s University, 116 Barrie St., Kingston, ON, K7L 3J9, Canada;(2) Present address: Living With Lakes Centre, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 3C6, Canada;(3) Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada;(4) Department of Environmental Science and Management, Portland State University, PO Box 751, Portland, OR 97207, USA; |
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Abstract: | Although community structure may be largely determined by local abiotic and biotic conditions under moderate levels of dispersal,
anthropogenic activities can enhance dispersal rates far beyond what would otherwise occur in natural systems. We investigated
the potential impact of recreational canoeing on crustacean zooplankton community structure in Killarney Provincial Park,
Canada, where canoes that are transported between lakes via portage routes may enhance zooplankton community connectivity
by providing a dispersal “short-cut.” We conducted a study to (1) quantify zooplankton attachment to canoe hulls after paddling
through a lake and assess the importance of canoes to overall seasonal dispersal within a lake relative to other means of
dispersal, (2) test the prediction that zooplankton survivorship is negatively correlated with portage duration using a mesocosm
experiment, and (3) test whether variation in lake community composition was better explained by models based on reduced portage-corrected
distances or true edge-to-edge distances between lakes along popular canoe routes. Here, we report the findings that canoes
have the potential to act as frequent dispersal vectors, but appear to have little impact on community structure in portage-connected
lakes. Substantial numbers of adult zooplankton became attached to canoe hulls and were able to establish viable populations
even after exposure to portage conditions for 30 min. However, canoe-mediated dispersal only accounted for a very small proportion
(<1% in this case) of overall seasonal dispersal. Moreover, environmental variables explained the greatest amount of variation
in community composition among park lakes. Nevertheless, this study indicates that canoe dispersal could be more effective
for specific species such as Sida crystallina than is evident by analysis of entire communities and could facilitate the spread of invasive species amenable to attaching
to boat hulls. Thus, the debate about whether community composition is more strongly influenced by local environmental conditions
or regional dispersal may vary depending on the scale of consideration (i.e., individual species vs. whole community). |
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