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TROPHIC INTERACTIONS AMONG DETRITUS, BENTHIC MIDGES, AND PREDATORY FISH IN A FRESHWATER MARSH
Author(s) -
Batzer Darold P.
Publication year - 1998
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(1998)079[1688:tiadbm]2.0.co;2
Subject(s) - midge , biology , piscivore , ecology , gambusia , predation , juvenile fish , population , fishery , juvenile , predator , larva , demography , sociology , fish <actinopterygii>
I conducted field experiments in a western New York marsh to quantify concurrently the impacts of resource limitation and predation on benthic midge populations ( Chironomus plumosus, Chironomus tentans, and Glyptotendipes barbipes ). Biomass of cattail litter ( Typha sp.), numbers of small insectivorous fish (primarily juvenile carp, Cyprinus carpio, and to a lesser extent juvenile brown bullhead, Ictalurus nebulosus ), or numbers of large fish (primarily adult brown bullhead, which will consume both midges and small fish) were manipulated in mesh‐walled mesocosms (1.5 × 1.5 × 1.2 m). Using core sampling, midge population responses to manipulations were monitored from early May through late August. Trophic responses of marsh midges to resources and predation changed temporally over the summer. In June, neither resource limitation nor predation by fish significantly influenced midge numbers. In July, after juvenile carp and brown bullhead first became abundant from the spawn, these small insectivorous fish significantly reduced midge larval densities. At that time, midge densities still did not respond to variable detritus supplies. By August, both predation by small fish and available supplies of cattail litter significantly affected midge numbers. Because midges did not respond to a nonnutritive mimic of cattail litter, it suggests that resource limitation of midge abundance was nutritionally based. Feeding by large adult bullhead had no apparent direct or indirect influence on midge densities in any month. Small fish largely disappeared from the study habitats by August, but populations of midge larvae did not rebound because they had stopped breeding for that year. This study supports emerging concepts on the integrated influences of top‐down and bottom‐up trophic interaction on food web function. Predation and resource limitation were simultaneously influencing midge abundance. Results also emphasize how life history phenologies of predators and prey can contribute to temporal variation in food web structure and function.