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Salmincola californiensis is a Lernaeopodid copepod parasitizing Pacific salmon and trout of the genus Oncorhynchus. Salmincola californiensis is of increasing concern in both native and introduced ranges because of its potential fish health impacts and high infection prevalence and intensity in some systems. Discrepancies in the documented life history phenology of S. californiensis with the sister species Salmincola edwardsii, as well as our laboratory observations, led us to question the existing literature. We documented a naupliar stage, thought lost for S. californiensis. In addition, we found a high degree of thermal sensitivity in egg development, with eggs developing faster under warmer conditions. Survival of copepodids was also highly dependent on temperature, with warmer conditions reducing lifespan. The longest lived copepodid survived 18 days at 4°C in stark contrast to the generally accepted S. californiensis and related taxa will be a necessary step to improving our knowledge of the parasite life history and development that will be critical to disease management.

Streams that dry during part of the year are common throughout the world, yet studies of the macroinvertebrate assemblages in these types of streams are rare compared to those in permanent streams; and studies that assess the effects of agriculture on temporary stream invertebrates are even rarer. We studied macroinvertebrate assemblages in lowland temporary streams of a region with high agricultural land use, the southern Willamette Valley, Oregon, USA. Overall assemblages were dominated by non-insects, and invertebrates tolerant of organic pollution. Nonetheless, these invertebrates displayed adaptations to life in temporary habitats, and as such they may be unique to temporary streams and seasonal wetlands, providing an important addition to regional biodiversity. Stream invertebrates are also important as a prey base for native fish and amphibians using these channels. Benthic invertebrate densities were higher at sites with slower water and more in-stream vegetation; to a lesser degree greater agricultural land use was associated with lower densities. Taxon richness was also negatively affected by agriculture, but this was most evident when least disturbed and highly agricultural sites were compared. Sites in watersheds with a lower proportion of their area under agriculture (mostly west of the Willamette River) had a variety of taxa in disturbance-sensitive insect orders Ephemeroptera, Plecoptera, and Trichoptera (EPT), plus flies in the family Simuliidae present. In addition, they had greater relative abundances of 2 types of flies in the family Chironomidae. In contrast, sites in watersheds with high agricultural land use (mainly east of the Willamette River) had greater relative abundances of non-insects, including ostracods, nematodes, and oligochaete worms. In highly agricultural watersheds, when stream-bottom vegetation was abundant, it was associated with greater benthic invertebrate density, but not with higher taxon richness. Our results suggest that increasing stream-bottom vegetation could be useful when food is limiting for native vertebrates. On the other hand, reduced agricultural land use allows for the development of more diverse benthic invertebrate assemblages.

To examine seasonal and spatial factors affecting prey consumption by Oncorhynchus trout, we examined trout diet from mainstem and tributary sites at Hinkle Creek, Oregon. Benthic invertebrate densities were similar across seasons and did not differ between tributaries and the mainstem. Fluctuations in diet followed seasonal changes in invertebrate sizes and abundances. Average prey biomass consumed was positively correlated with fish size. Consumption rates were high in spring and summer but fell significantly in fall when fewer and smaller prey were eaten. A switch in consumption from 36% terrestrial prey biomass in spring to 85% in summer coincided with an increase in terrestrial prey size and a decrease in benthic prey size. Location within the watershed also affected prey consumption. Despite similarities in diet composition, tributary trout consumed somewhat more biomass than trout in the mainstem but grew relatively slower. Because stream fishes such as Oncorhynchus trout feed opportunistically on varied prey, studies incorporating multiple seasons and stream types are important to understanding energy exchanges between terrestrial and aquatic ecosystems.

One of the dilemmas in designing any large-scale macroinvertebrate bioassessment is deciding where to sample within streams. Streams contain a wide variety of habitats with varying macroinvertebrate assemblages, yet consistency in sampling protocol is needed to interpret results across sites in a region. The Environmental Monitoring and Assessment Program (EMAP) conducted large regional probability surveys in the mid-Atlantic (1993–1998) and the western US (2000–2001). In these surveys, 2 macroinvertebrate sample types were collected at each site: pool and riffle in the mid-Atlantic region, and reachwide and riffle in the western US. We analyzed data from sites where both types of samples had been collected (206 mid-Atlantic and 293 western US sites) to examine the effects of sample type on typical metric and multivariate analyses done in bioassessments. Sample types differed in terms of taxon richness measures and assemblage composition, and differences were more pronounced between mid-Atlantic r...

An Oregon resident returned from a photography trip to Ethiopia with a male Hyalomma truncatum tick attached to the skin on his lower back. The tick was identified morphologically and deposited in the U.S. National Tick Collection housed at Georgia Southern University, Statesboro, Georgia. The public health importance of Hyalomma species of ticks and diagnostic dilemmas with identifying exotic ticks imported into the U.S. are discussed.

We quantified the patterns in macroinvertebrate assemblages and their associated environmental gradients from 457 least-disturbed wadeable stream sites across the 48 contiguous United States sampled as part of US EPA’s National Wadeable Stream Assessment. The majority of the variation in assemblage composition at the finest taxonomic resolution was related to substrate size, %fastwater habitat, water chemistry, as well as east-west geographic position and elevation. Sites were classified into 5 groups with cluster analysis, and group membership was predicted from environmental data using classification tree analysis (CTA). CTA correctly classified 69.1% of test sites and indicated that groups were distinguished by east-west location, and by factors distinguishing mountain streams from lowland/plains streams. Eastern and western groups that had similar environmental characteristics had very similar coarse scale taxa composition and convergent taxa traits. Ordinations confirmed that composition patterns using coarse level taxa resolution and taxa traits no longer reflected geographic distinctions, but were only related to non-geographic environmental factors. However, composition patterns based on traits, coarse taxa, and macroinvertebrates identified to the finest practical level were all correlated with the same dominant non-geographic environmental gradients.