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Open AccessArticle

The Impacts of Recently Established Fish Populations on Zooplankton Communities in a Desert Spring, and Potential Conflicts in Setting Conservation Goals

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Environmental and Conservation Sciences Graduate Program, Department of Biological Sciences, North Dakota State University Dept. 2715, P.O. Box 6050, Fargo, ND 58108-6050, USA
2
Biosciences Department, Minnesota State University Moorhead, 1104 7th Avenue South, Moorhead, MN 56563, USA
*
Author to whom correspondence should be addressed.
Present address: Department of Biological
Academic Editor: Thilina Surasinghe
Diversity 2015, 7(1), 3-15; https://doi.org/10.3390/d7010003
Received: 1 December 2014 / Accepted: 4 January 2015 / Published: 9 January 2015
(This article belongs to the Special Issue Global Freshwater Biodiversity)
Desert springs, which harbor diverse and endemic invertebrate assemblages, are often used as refuge habitats for protected fish species. Additionally, many of these springs have been colonized by invasive fish species. However, the potential impacts of recently established fish populations on invertebrate communities in desert springs have been relatively unexplored. We conducted a mesocosm experiment to assess the impact of both protected and invasive fish on community structure of spring-dwelling invertebrates focusing on zooplankton. Experimental populations of spring zooplankton communities were established and randomly assigned to one of three treatments, (1) invasive western mosquitofish (Gambusia affinis); (2) endangered Mohave tui chub (Siphateles bicolor mohavensis); and (3) fishless control. Final populations of zooplankton and fish were sampled, sorted, identified and counted. The treatment differences of zooplankton communities were analyzed by comparing the densities of six major zooplankton taxa. Further, we performed nonmetric multidimensional scaling (NMDS) to visualize the patterns of zooplankton community assemblages. Four zooplankton taxa, crustacean nauplii, cladocera, calanoid and cyclopoid copepods had significantly lower densities in fish treatments compared to fishless control. Overall, invasive mosquitofish caused a 78.8% reduction in zooplankton density, while Mohave tui chub caused a 65.1% reduction. Both protected and invasive fish had similar effects on zooplankton except for cladocerans where tui chub caused a 60% reduction in density, whereas mosquitofish virtually eliminated cladocerans. The presence of fish also had a significant effect on zooplankton community structure due to population declines and local extirpations presumably due to fish predation. This work shows that conservation-translocations undertaken to conserve protected fish species may impact spring-dwelling invertebrate communities, and such impacts are similar to impacts due to colonization by invasive fish species. View Full-Text
Keywords: desert springs; spring invertebrates; spring zooplankton; protected species; endangered species; invasive species; alien species desert springs; spring invertebrates; spring zooplankton; protected species; endangered species; invasive species; alien species
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Henkanaththegedara, S.M.; Fisher, J.D.L.; McEwen, D.C.; Stockwell, C.A. The Impacts of Recently Established Fish Populations on Zooplankton Communities in a Desert Spring, and Potential Conflicts in Setting Conservation Goals. Diversity 2015, 7, 3-15.

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