Dynamics of a Boreal Lake Ecosystem during a Long-Term Manipulation of Top Predators

Findlay, D. L.; Vanni, Michael J.; Paterson, Michael; Mills, Kenneth H.; Kasian, S. E. M.; Findlay, Willie J.; Salki, Alex

doi:10.1007/s10021-005-1221-0

Cited by 39 publications

(40 citation statements)

References 46 publications

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“…In the ElA lakes, the introduction of Northern Pike into naïve prey fish communities has consistently, in three independent experiments, resulted in a major initial restructuring of those communities (Elser et al 1998(Elser et al , 2000Findlay et al 2005) and, ultimately, as we have shown here, their apparent extirpation in these lakes. Although the extirpation of prey fish in lake 227 was known before this study, it was thought that lake 110 continued to support a remnant prey population and that lake 221 continued to support Yellow Perch based on surveys conducted during 1995-2000. our survey, more than a decade later, demonstrated otherwise.…”

Section: Discussionsupporting

confidence: 57%

“…lake 222 has long-standing co-existing populations of Northern Pike, Yellow Perch, and minnows (Blacknose shiners, Notropis heterolepis) and was the source of many of the Northern Pike added to lakes 110, 221, and 227 (Elser et al 1998;Findlay et al 2005). Methods were identical to those described above, although we were unable to check the traps on the sixth day and assumed that the resultant catch on the seventh day was equally distributed over the twoday period.…”

Section: Survey Of Prey Fish Communitiesmentioning

confidence: 99%

“…In 1987, Northern Pike were stocked in lake 221 at 6.9 kg/ha (Findlay et al 2005). the forage fish abundance was dramatically reduced within a year and remained low until 1994-95, when 85% of the Northern Pike were removed by gill net (Findlay et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

2015

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We examined the long-term effects on prey fish communities of introducing Northern Pike (Esox lucius), a top predator fish, into small, Boreal Shield lakes lacking natural piscivore populations. During 1987–1994, Northern Pike were introduced into Lakes 110, 221, and 227 in the Experimental Lakes Area in northwestern Ontario, Canada. In Lake 227, prey fish were undetectable three years after the addition of Northern Pike. Although Northern Pike were removed from the lake by 1996, multiple independent visual and trapping surveys have yielded no evidence of any fish in Lake 227 since then. In 1994–1995, 85% of the Northern Pike were removed from Lake 221. In 2012, despite intensive sampling efforts using baited minnow traps, fyke nets, trap netting, gill netting, angling, and visual observation, no forage fish of any species was observed or caught in Lake 110 or 221. In all three lakes where Northern Pike were added, prey fish populations were extirpated or too small to detect. In Lake 221, we estimated the current population of Northern Pike to be 49 ± 37, a 59% decrease since 2000 when prey fish were still present. The mean total length and body condition of Northern Pike in Lake 221 had not changed since the prey community collapsed. Our findings suggest that the introduction of Northern Pike into lakes without natural piscivore populations has long-lasting effects on fish community structure, to the detriment of both Northern Pike and prey fish populations.Note: an erratum for this article was published in the subsequent issue, and is attached to the end of this article's pdf. Table 2 had not been justified properly; the revised table corrects this issue.

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Section: Discussionsupporting

confidence: 57%

Section: Survey Of Prey Fish Communitiesmentioning

confidence: 99%

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Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

2015

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“…Manipulations of ELA lakes resulting in major changes in fish abundance and/or community composition have often not resulted in strong trophic cascades and responses of lower trophic levels were often delayed for several years (e.g. [33,57]). …”

Section: Discussionmentioning

confidence: 99%

Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen

Kidd

Paterson

Rennie

et al. 2014

Phil. Trans. R. Soc. B

160

143

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Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l −1 ), indicating no direct toxic effects. Recruitment of fathead minnow ( Pimephales promelas ) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout ( Salvelinus namaycush ) and male and female white sucker ( Catostomus commersonii ) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus , and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin ( Cottus cognatus ). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors.

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“…Trophic cascades can cause large changes in fish-derived nutrient fluxes. For example, fish excretion in a planktivore-dominated lake supported 30% of primary production, but fish excretion in a piscivoredominated lake only supported 6-14% of primary production in a lake in Ontario, Canada (Findlay et al 2005). Similarly, Schindler et al (1993) calculated that fish excreted ;90% of P in a planktivore-dominated lake and ;20% of P in a piscivore-dominated lake in Michigan, USA (;80% by invertebrates).…”

Section: Invasive Lake Trout Disrupted Excretion Fluxes From Native Cmentioning

confidence: 99%

Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake

2015

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Citation: Tronstad, L. M., R. O. Hall Jr., and T. M. Koel. 2015. Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake. Ecosphere 6(11):224. http://dx.doi.org/10.1890/ES14-00544.1Abstract. Introduced predators can have large effects on the ecosystem in which they were introduced, but how much these effects extend to other ecosystems beyond the invaded one is less known. We compared how lake trout (Salvelinus namaycush) affected nutrient cycling in an invaded and adjacent ecosystem in Yellowstone National Park, Wyoming, USA. Introduced lake trout in Yellowstone Lake caused the native Yellowstone cutthroat trout (Oncoryhynchus clarkii bouvieri ) population to decline. Native cutthroat trout are a dominant animal in the lake and may alter nutrient cycling in both Yellowstone Lake where they reside and in tributary streams used for spawning. We estimated changes in nutrient transport and nutrient uptake in both Yellowstone Lake and Clear Creek, a spawning stream, before and after the invasion of lake trout. Annual area-specific excretion fluxes from cutthroat trout were nine times higher in Clear Creek compared to Yellowstone Lake when cutthroat trout were abundant. However, fluxes within the lake and stream were similar after cutthroat trout declined. In Yellowstone Lake, zooplankton excretion supplied 86% of ammonium (NH 4 þ ) that was taken up, but cutthroat trout only supplied ,0.3% after the introduction of lake trout. Conversely, NH 4 þ excreted by cutthroat trout was likely a major flux in ClearCreek, because NH 4 þ fluxes from cutthroat trout exceeded watershed export of NH 4 þ in years when .3000 cutthroat trout spawned. Furthermore, NH 4 þ excretion fluxes from spawning cutthroat trout in ClearCreek supplied up to 6.1% of the NH 4 þ demanded by microbes after the introduction of lake trout.However, based on modeled past NH 4 þ uptake, we estimated that up to 60% of NH 4 þ excreted by spawning cutthroat trout may have been taken up by stream microbes when cutthroat trout were abundant. Therefore, transported NH 4 þ from spawning cutthroat trout was likely an integral part of N cycling in tributary streams in the past. By comparing the effects of declining cutthroat trout on two ecosystems, we show that lake trout had a larger effect on N cycling within an adjacent stream ecosystem than the invaded lake ecosystem itself, because the migratory behavior of cutthroat trout concentrated them in spawning streams increasing their effect.

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Dynamics of a Boreal Lake Ecosystem during a Long-Term Manipulation of Top Predators

Cited by 39 publications

References 46 publications

Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen

Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake

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