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

Sujan Henkanaththegedara,Daniel Mcewen,Craig Stockwell,Justin Fisher

doi:10.3390/d7010003

Sujan Henkanaththegedara, Daniel Mcewen + Show 2 more

Open Access

https://doi.org/10.3390/d7010003

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Abstract

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

Highlights

Desert springs function as “keystone” ecosystems playing a major role in evolutionary processes and regional biodiversity [1,2]
Many desert springs have been stocked with non-native fish species [13,14,15,16] mainly to control mosquito-borne diseases, to promote sport fishing, and as breeding ponds for aquarium fish
We examined the effects of non-native western mosquitofish and protected Mohave tui chub (S. b. mohavensis) on spring zooplankton communities using a mesocosm experiment

Summary

Introduction

Desert springs function as “keystone” ecosystems playing a major role in evolutionary processes and regional biodiversity [1,2]. Recent studies have uncovered unique, highly diverse and endemic invertebrate assemblages, both macroinvertebrates and zooplankton, from North American desert springs [4,5,6,7,8,9,10,11,12]. These systems are of particular conservation concern because many spring invertebrates are threatened with extinction due to anthropogenic impacts, such as water mining, habitat alterations, and introduction of non-native species [1,3,13]. Endangered species such as the Gila topminnow Poeciliopsis occidentalis occidentalis [18], Mohave tui chub Siphateles bicolor mohavensis [20] and Pahrump poolfish Empetrichthys latos latos [21]

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