Macroinvertebrate density, biomass and drift were studied from moss-covered and moss-free channels in the South Fork Salmon River, Idaho. Insect densities were compared for 10 different substrate types and locations involving moss (Fontinalis neo-mexicana), sand, pebbles and cobbles. An ANOVA test demonstrated that insect densities varied significantly with substrate type (P < 0.05), and that total insect density in moss clumps differed significantly from densities in mineral substrates. Insect densities were 4-18 times greater in moss clumps than in mineral substrates under and adjacent to moss; sands under moss supported the lowest densities. During most tests, densities in pebble and cobble substrates adjacent to moss clumps were not significantly different from those found in similar substrates in the moss-free channel. The 20% moss-covered channel had 1.6 to 7.2 greater insect density and 1.4 to 6.1 greater biomass than did the moss-free channel for the tests conducted. Generally, midges (Chironomidae) made up over 50% of the insect community; annelids were the principal non-insect invertebrates.In spite of greater insect density and biomass in a moss-covered than in the moss-free channel, we did not demonstrate universally increased drift of the immature stages from the moss-covered channel, at least during daylight hours. As a consequence, we infer that salmonid fishes, feeding primarily on drifting insects during the daytime, may not derive increased caloric benefit from moss habitats until the insects emerge as adults.

The 'evolution of increased competitive ability' (EICA) hypothesis is an extension of optimal defense theory and predicts that reduced pressure from insect herbivores in the introduced range results in evolution of reduced defenses in invading plant populations, allowing greater allocation of resources to competitive traits such as growth rate and reproduction. The EICA hypothesis considered levels of defensive chemistry to be fixed within a particular genotype. In this paper, we propose that if herbivory is reduced in the introduced range, but chemical defenses are inducible in response to herbivory, evolution of reduced defenses and any associated increase competitive ability should not occur. Rather, mean induced and constitutive levels of induced defenses should be similar in introduced and native ranges, but the variance about mean induced levels should be greater in the introduced range. This is predicted because induced levels will occur less frequently in the introduced range where herbivory is reduced, thereby insulating these levels from the stabilizing selection expected in the native range where induced levels occur more frequently. We conducted a preliminary study to examine this by comparing constitutive and induced concentrations of total pyrrolizidine alkaloids (PAs) from native (European) and introduced (western North America) populations of Cynoglossum officinale L. The mean constitutive and induced concentrations of PAs did not differ between continents, but the variability of the induced concentrations was significantly greater for plants from the introduced range. Although our study with C. officinale is provisional due to a small sample size, it supports our predictions for evolution of inducible defenses in introduced ranges where herbivore pressure is reduced. Most chemical defenses in plants have been found to be inducible, so similar patterns may occur widely. If so, this weakens the generality of EICA's predictions concerning chemical defenses. The effects of inducible defenses should be considered in cross-continent comparisons of other invasive plant species.

zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Mining has severely impacted the biota in the Coeur d'Alene River drainage of northern Idaho. The benthic community of the South Fork and mainstem was monitored from 1968 to 1971 and from 1987 to 1991 to determine the effects of improved mine wastewater treatment and mine closures. With the decrease of heavy metal levels, the benthic community showed a gradual recovery as evidenced by large increases in taxonomic richness (0 to 18), EphemeropteraPlecoptera Trichoptera index (0 to 8), and species diversity (0 to 1.8). Although considerable recovery has occurred, the biotic integrity of impacted sites continues to lag behind reference sites, probably due to poor habitat structure and metals leaching from mine tailings.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Water Environ. Res., 66, 84 (1994).

Crop traits can alter economically important interactions between plants, pests, and biological control agents. For example, a reduced waxy bloom on the surface of pea plants alters interactions between pea aphids and their natural enemies. In this study, we assess whether the effect of wax reduction extends beyond the 2 or 3 arthropod species closely associated with the plants and into the structure of the broader arthropod community of over 200 taxa at our site. We sampled arthropods on lines of peas with normal and reduced wax in Latah Co., Idaho using pitfall traps within randomly assigned pairs of 5 × 5 meter plots. During the 1998 and 1999 growing seasons, we collected 12,113 individual arthropods from 221 unambiguously identified morphospecies. The number of individuals collected from each morphospecies responded idiosyncratically to the reduced wax peas. To test whether arthropod community structure differed between the collections from plots having peas with normal or reduced wax, we performed a randomization test. The collection from peas with reduced wax had higher species evenness and thus higher community diversity despite having lower species richness. Our results demonstrate the potential of a single plant trait, epicuticular wax, to affect a community of arthropods. Two pests of peas had opposite responses to peas with reduced wax. The number of pea aphids collected was greater from peas with normal wax peas than those with reduced wax. In contrast, the number of pea leaf weevils collected was greater from peas with reduced wax.

Field investigations and simulation modelling studies were conducted on an agriculturally perturbed watershed draining into the regulated Lower Clearwater-Snake Rivers of Idaho and Washington. Ecological-economic analyses were conducted to develop an integrated systems framework to assess the impacts of alternative farming practices on sustainable farming, sediment erosion and stream health on Tom Beall Creek, with ecological implications and consequences to Lower Granite Reservoir on the Snake River. A geographic information system (GIS) was used to spatially delineate field boundaries, soil types, drainage patterns and erosion rates. An AGNPS (agricultural nonpoint source) pollution model was interfaced with the GIS to project water quality impacts of land use in the watershed. The AGNPS model was integrated with a mixed integer linear programming model (MIP) to facilitate modelling cost effectiveness on land as it related to eroded soil entering the receiving streams. Biological health assessment was performed using benthic macroinvertebrates. The biological condition of Tom Beall Creek was rated as slightly and moderately impaired for 1992 and 1993, respectively. A wheat-pea rotation under conventional tillage and cross-slope farming had the highest weighted average on-site erosion damage of $20 per ha; the lowest damage was $3.63 per ha using a wheat-barley-fallow rotation with reduced tillage and divided slopes. Simulating a 'no programme' policy scenario, the MIP model showed the dramatic impact of the current farm programme with conservation compliance in the region of highly erodible land and high participation rate in the government farm programme. Under current farming practices and > 50 yr spring runoff event, it was estimated that nearly 5000 t of suspended solids would be exported from the Tom Beall watershed. During low flow years, less than 200 t were exported.Sedimentation in Tom Beall Creek is the most debilitating environmental factor impacting the aquatic biota. High erosion rates from all of the anthropogenically impacted streams above Lower Granite Dam tend to shorten the productive storage life of the reservoir, alter the hydroelectric power generating capacity and interfere with the ecological food web and biodiversity. Although the implementation of better conservation practices in anthropogenically disturbed watersheds will not eliminate watershed erosion, it will reduce the frequency and the amounts of sediment dredged from reservoirs in the future, and will reduce on-site and off-site costs of erosion and sediment damage.