Diet and annual production of two boreal river fishes following clearcut logging

Abstract

SynopsisDiet and annual production of two cyprinid fishes in the Piscataquis River, Maine, were investigated before and after extensive deforestation of the surrounding watershed. Observed patterns were evaluated relative to post-logging changes in the benthic macroinvertebrate community, and to differences in ecomorphology between the two fishes. Prey selection was generally density-dependent for both predator species throughout the study, but significant exceptions to density-dependence were observed for several aquatic insect lifemode groups (e.g., swimmers, climbers, burrowers). This apparent preferencelavoidance for certain prey taxa by fish predators could be adequately explained by differential availability (vulnerability) among prey taxa. Compared to the year before logging, significant post-logging changes in diet composition and gut fullness were observed for both blacknose dace, Rhinichthys atratulus, and creek chub, Semotilus atromaculatus, concomitant with post-logging changes in the availability of benthic prey. Annual production of blacknose dace was significantly lower (52.7 vs. 37.7 kg ha-' y-') in the year following logging. In contrast, annual production of creek chub increased significantly after logging, from 8.6 to 17.4 kg ha-' y-l. Because post-logging changes in the physical environment were probably not sufficient to directly affect fish populations, we hypothesize that blacknose dace were morphologically constrained to feed on a declining aquatic prey resource, with a resultant decline in production. In contrast, the generalist creek chub switched to a non-aquatic prey resource (terrestrial arthropods) and no decline in production was observed for that species.

Effect of riparian land use on contributions of terrestrial invertebrates to streams

“…Such factors may negate quantitative changes in terrestrial inputs under different riparian management regimes . Although perhaps of little consequence in the Taieri River drainage, riparian factors that influence inputs of terrestrial invertebrates are predicted to have greater consequences for fish production elsewhere, particularly in oligotrophic streams with low levels of benthic prey production during summer when energy demands of fish are high and biomass of benthic invertebrates may be at a minimum (Hynes, 1970;Hunt, 1975 ;Cada et al ., 1987 ;Garman & Moring, 1993) .…”

“…The effect of forestry practices on the proportion of terrestrial invertebrates composing the diets of stream fishes has been reported by Wilzbach et al . (1986) and Garman & Moring (1993) . However, the effects of different land-management regimes on quantities of terrestrial invertebrates actually entering streams is unknown .…”

Forest drainage: a threat to benthic biodiversity of boreal headwater streams?

“…In particular, while both the hydrological and limnological impact of forest clear-cutting have been described in many studies (e.g. Gurtz and Wallace, 1984;Wallace and Gurtz, 1986;Golladay et al, 1989;Bilby and Bisson, 1992;Garman and Moring, 1993;Ormerod et al, 1993), only a few have dealt with the ecological impact of forest drainage on lotic ecosystems (Bergquist et al, 1984;Holopainen and Huttunen, 1992;Vuori and Joensuu, 1996).…”

The artisanal fishery of the River Piracicaba (São Paulo, Brazil): Fish landing composition and environmental alterations

“…Clearance of riparian forests in southwestern Brazilian rivers caused a decline in the Brycon lundii fishery at MogiRiver Guaçu (Godoy, 1975) and extinction of the River Jacaré-Pepira fishes that eat fruits (Barrela et al, 1994). Removal of marginal vegetation cover in temperate streams of North America affected their fish communities, leading to alterations in food habits (Garman & Moring, 1993) and to reductions in the species diversity (Pearsons & Li, 1992).…”