Todd A. Wellnitz

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SUMMARY 1. An experiment conducted in streamside channels was used to document the regrowth of grazed periphyton. Our objective was to determine the relative importance of current velocity, grazing duration, and grazer type in shaping the trajectory of algal and periphytic regrowth. 2. The grazing mayflies Baetis bicaudatus and Epeorus longimanus were used(More)
We conducted streamside experiments to determine if the ability of herbivorous insects to remove algal periphyton varies with local current velocity. We used two mayfly species (Baetis bicaudatusand Drunella grandis) and one caddisfly species (Glossosoma verdona), which differ from one another in body morphology and mobility. Periphyton was grown for 30(More)
The effects of the acanthocephalan parasite Pomphorhynchus laevis on the behavior of its crustacean intermediate host, the amphipod Echinogammarus stammeri, were studied. A drift study revealed that infected amphipods were disproportionately represented in drift samples taken throughout a 24-hr period; infection with more than 1 parasite enhanced this(More)
Current velocity is a pervasive feature of lotic systems, yet this defining environmental variable is rarely examined as a factor for regulating stream herbivory. To investigate how current modifies herbivory in the upper Colorado River, U.S.A., loops of electrified fencing wire were used to reduce in situ grazer densities on 30 × 30 cm tile substrates.(More)
By shaping the architecture and taxonomic composition of periphyton, stream current may create periphytic mats on which some grazers can feed and forage more effectively than others. Current-mediated periphytic structure also has the potential to foster positive interactions among grazers if one grazer’s foraging facilitates another’s access to algal food.(More)
The modification of flows in lotic ecosystems can have dramatic effects on abiotic and biotic processes and change the structure of basal trophic levels. In high-gradient streams, most of the biota are benthic, and decreased flow may homogenize and reduce benthic current velocity, potentially changing stream ecosystem function. Grazing by macroinvertebrates(More)
The acanthocephalan parasite Pomphorhynchus laevis (Müller, 1776) uses freshwater amphipods as its intermediate host. In order to complete the life cycle, the infected amphipod must be consumed by a fish, where the acanthocephalan will mature and reproduce. Parasite transmission, and therefore fitness, could be enhanced if infected amphipods fail to detect(More)
Understanding the factors controlling insect emergence from streams has applications to ecological theory regarding cross-boundary flux, along with practical value for monitoring stream function after restoration projects. We hypothesized that stream microhabitat would have effects on emergence that were independent of those mediated by the local stock of(More)
Redundancy among three herbivorous insects across an experimental current velocity gradient Abstract We conducted streamside experiments to determine if the ability of herbivorous insects to remove algal periphyton varies with local current velocity. We used two mayfly species (Baetis bicaudatus and Drunella grandis) and one caddisfly species (Glossosoma(More)