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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Food Webs 3
Macroinvertebrate colonization and incorporation of marine-derived nutrients from Atlantic salmon carcasses in a Scottish Highland stream
K.H. Nislow1, P. Collen2, J. Keay2, J.D. Armstrong2, and B.P. Kennedy3. 1USDA Forest Service, Northeastern Research Station, Amherst, MA 01003, 2Scottish Fisheries Service Freshwater Laboratory, Faskally, UK PH16 5LB, 3Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109
The role of Pacific salmonids as a source of nutrients to stream ecosystems has been extensively demonstrated, but the role of anadromous Atlantic salmon, their counterparts in the Atlantic basin, is relatively unknown. We experimentally stocked the carcasses of adult salmon in a small oligotrophic upland rearing stream after spawning in the fall, then monitored invertebrate colonization on and adjacent to carcasses monthly through the following summer. Carcasses lost little mass throughout the winter, with loss rates increasing markedly after April. Carcasses were rapidly and extensively colonized, first by simuliid larvae, followed by ephemerellid mayflies, baetid mayflies, and finally chironomid larvae in the final stages of decomposition. Abundance was significantly greater on carcasses than in substrate samples for a number of taxa. Stable isotope analyses revealed that salmon-derived nitrogen was readily incorporated into macroinvertebrate tissue, with marine-derived signatures present in samples collected more than 200 m downstream of the carcass addition site. These results indicate that nutrients transported by migratory Atlantic salmon may significantly influence Atlantic-basin stream ecosystems, and that uptake by macroinvertebrates may be an important part of this process.
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