Trophic relationships of two species of grebe on a prairie lake based on stable isotope analysis |
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Authors: | Jennifer L Newbrey Cynthia A Paszkowski Beverly A Gingras |
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Institution: | (1) Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP, UK;(2) Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Glasgow, G12 8QQ, UK;(3) Freshwater Laboratory, Marine Scotland, Faskally, Pitlochry, PH16 5LB, UK;(4) Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK;(5) Kinross Estate Office, Kinross, KY13 8AS, UK |
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Abstract: | Loch Leven, U.K., contains brown trout (Salmo trutta), eel (Anguilla anguilla), minnow (Phoxinus phoxinus), perch (Perca fluviatilis), pike (Esox lucius) and three-spined stickleback (Gasterosteus aculeatus), with brook lamprey (Lampetra planeri) and stone loach (Barbatula barbatula) also present in its tributaries. Arctic charr (Salvelinus alpinus), Atlantic salmon (Salmo salar) and flounder (Platichthys flesus) are now extinct. The brown trout population has supported a world-renowned recreational fishery for over a century, although
a decline in fishery performance led to extensive stocking between 1983 and 2006, including with non-native rainbow trout
(Oncorhynchus mykiss). This review combines historical information with contemporary gill-net and hydroacoustic surveys. In 2008, brown trout,
perch and three-spined sticklebacks were abundant, but pike and stone loach were rare. The obstruction of migratory routes
was probably responsible for the loss of Atlantic salmon and flounder, while a lowering of water level likely caused the extinction
of Arctic charr and contributed to a reduction in pike abundance. Perch abundance has fluctuated markedly, being influenced
by disease and eutrophication, although a reduction in nutrients and associated recovery of macrophytes are likely to have
benefitted this species. Although the brown trout population has undoubtedly shown a long-term decline, individuals are currently
in excellent condition. |
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