Scott J. Herrmann

Cadmium and Zinc Accumulation in Aquatic Bryophytes Immersed in the Arkansas River, Colorado: Comparison of Fall versus Spring

ABSTRACT A bryophyte, Hygrohypnum ochraceum, was used as an indicator of heavy metals in the upper Arkansas River below the historical mining district at Leadville, Colorado. Plants were immersed in the river at nine sites near Leadville for 10 days during fall 2000 and spring 2001. Cadmium and zinc tissue-metals in plants were higher in the fall than in spring. The plants showed site-to-site differences in concentrations of cadmium and zinc in the Arkansas River, and metals were markedly higher in California Gulch, a contaminated tributary draining the mining district of Leadville, Colorado. There were strong correlations between total cadmium in Arkansas River water and cadmium in bryophyte tissues and between dissolved and total zinc in the Arkansas River water and zinc in the bryophytes. Our study suggests that bryophytes could potentially be valuable monitoring organisms for assessing site and seasonal bioavailability of metals.

Species Richness, Diversity, and Ecology of Chironomidae (Diptera) in Fountain Creek: A Colorado Front Range Sandy-Bottom Watershed

Abstract. The primary purpose of this study was to assess the chironomid species diversity of a high-gradient sandy-bottom watershed along the Colorado Front Range. Adult male Chironomidae were collected concurrently in 2007 and 2008 from 14 sites in the Fountain Creek Watershed (FCW), south central Colorado, USA, using ultraviolet night lights and sweep netting methods. Species-level identifications resulted in 151 species including 24 new species from 65 genera and 6 subfamilies. Forty species are reported here as new Colorado records, and many North American range extensions were recorded. Some species had geographical ranges that included the Neotropical, Afrotropical or Oriental regions. Species from high elevations and northern latitudes were common. Individual species accounts include annotated North American distributions, associated water quality and sediment (particle size) analyses for each site, and ecological notes. Species richness calculations using Jaccard and Sørensen similarity indices indicated, with some exceptions, that sites in closest proximity shared the most common species. Chironomus decorus was the most commonly collected species in the FCW, occurring at 13 of 14 sites; the orthoclad Cricotopus infuscatus was collected at 12 of the sites. In 2007–2008, the FCW had a very diverse chironomid species assemblage. How species composition changes in the watershed will be influenced by urbanization, global warming, and increased base flows from water diversions.

Caloric and Micronutrient Content of Nuphar polysepalum

Caloric equivalents are cited for eight vegetative and reproductive tissue types of Nuphar polysepalum; leaf blade tissue was highest (4499 cal/g ash-free dry weight) and rhizome tissue lowest (3976 cal/g ash-free dry weight). In addition, the concentration of Fe, Mn, Cu, and Zn was determined for each tissue type; leaf blade tissue was consistently highest for each micronutrient while seed tissue was consistently lowest. N. polysepalum is nearly always restricted to Colorado semidrainage mountain lakes; lakes whose waters have consistently high levels of total Fe, N03-N, and humic acid (color). Energy and micronutrient content of aquatic macrophytes is becoming increasingly important economically and ecologically. Westlake (1965) emphasized the need for data concerning the caloric and chemical composition of aquatic vascular plants, particularly as they relate to our study and understanding of energy flow in aquatic ecosystems. Caloric values for about 35 species of aquatic angiosperms have been cataloged (Cummins and Wuycheck 1971). In nearly all cases either the entire plant was used or conspicuous (above ground) vegetative and reproductive parts were combined before analysis. The primary objective of this paper is to present caloric equivalents for eight vegetative and reproductive parts of the yellow pond-lily Nuphar polysepalum Engelm. 1865 (-Nuphar luteum subsp. polysepalum). A second objective is the presentation of micronurient (Cu, Fe, Mn, and Zn) content within these eight tissue types. A final and tertiary objective is to document a unique set of limnological conditions of a Colorado semidrainage mountain lake (Red Rock Lake) for which Nuphar polysepalum is an indicator species of lake type in Colorado and is the predominant hydrophyte and photoautotroph. METHODS AND MATERIALS. Selected structural parts of Nuphar polysepalum, a perennial herb common to the unique semidrainage lakes of western North America (Pennak 1969), were collected from Red Rock Lake, Colorado, (Fig. 1) during the period June-September 1968 and 1969. Red Rock Lake is a 1Contribution No. 1 from the Water Resources Research Laboratory, The University of Southern Colorado.