Comparative genotype and toxin interactions at three polymorphic enzyme loci were examined in a laboratory population of amphipods (Hyalella azteca) during acute exposure to cadmium, zinc, copper, lead, or low pH. Significant toxin-genotype interactions were observed using logistic regression to model mortality in ten of 15 analyses. Both stressor-specific and nonspecific modes of selection wer...

We studied salmon feeding selectivity and diel feeding chronology in the Columbia River plume. Juvenile chinook and coho salmon were caught by trawling at 2–3 h intervals throughout a diel period on three consecutive days (21–23 June 2000) at stations located 14.8 and 37 km offshore from the mouth of the Columbia River. A total of 170 chinook salmon were caught at the inshore and 79 chinook and...

The co-occurrence of cryptic species of Hyalella amphipods is a challenge to our traditional views of how species assemble. Since these species have similar morphologies, it is not evident that they have developed phenotypic differences that would allow them to occupy different ecological niches. We examined the structure of a community of Hyalella amphipods in the littoral zone of a boreal lak...

Although sexually dimorphic traits are often well studied, we know little about sex-specific resource use strategies that should underlie such dimorphism. We measured sex-specific responses in acquisition and assimilation of two fundamental resources, carbon (C) and phosphorus (P) in juvenile and mature Hyalella amphipods given low and high supplies of inorganic phosphate, analogous to oligotro...

1. Native species might be able to persist in the face of a detrimental exotic invader by occupying refuge habitats where the exotic is not successful. These refuges might then provide demographic subsidies that enhance persistence of the native species in areas of coexistence with the exotic species. Phenotypic plasticity of the native species could play a critical role in this process by allo...

Abstract Conservation programs often aim to protect the abundance of individual species and biodiversity simultaneously. We quantified relations between amphipod densities aquatic macrophyte (large plants algae) diversity test a hypothesis that can support high single taxonomic group. Amphipods ( Gammarus lacustris Hyalella azteca ) are key forage for waterfowl declining in Prairie Pothole Regi...

Recent findings suggest that grouping with conspecifics is part of the behavioural defences developed by amphipod crustaceans to face predation risk by fish. Amphipods commonly serve as intermediate hosts for trophically transmitted parasites. These parasites are known for their ability to alter intermediate host phenotype in a way that promotes predation by definitive hosts, where they reprodu...

Tandem mass spectrometry (MS) was used to detect herbicide residues in wild populations of amphipods collected from microcosms spiked with a single pulse of either Avadext-BW (triallate) or HoeGrasst (diclofop-methyl) at three different concentrations (1.0, 10.0, and 100.0 mg·L21). Independent confirmations of both herbicides were obtained by spiking amphipod tissues with 50 pg of authentic sta...

This study has investigated the taxon-specific responses of fauna to patch edges, and how these relate to patch attributes (patch size, seagrass biomass and water depth), and hydrodynamics in the seagrass habitat. Faunal abundances were sampled at the edge, 2 m in from the edge, and in the middle of 10 seagrass patches of variable size in Port Phillip Bay, Australia. Five of nine taxa showed ed...

: A three-tiered approach involving autoradiography, measurement of seasonal lipid patterns and deployment of in situ microcosms, was used to assess the potential of the moderately lipophilic herbicide triallate to accumulate in two amphipod species (Hyalella azteca and Gammarus lacustris) in two prairie lakes and one prairie pond. Autoradiography revealed that the storage sites for triallate i...