D. A. Bruns

Elemental composition of mosses from a remote Nothofagus forest site in southern Chile

Abstract Concentrations of elemental nutrients (e.g., Ca, Mg) and anthropogenic trace metals (e.g., Pb, Cu) were measured in terrestrial ( Acrocladium auriculatum ) and aquatic ( Vittia pachyloma ) mosses in southern Chile as part of a pilot project for integrated global baseline monitoring (United Nations Global Environmental Monitoring System). The study site was a forested ( Nothofagus pumilio ) watershed located in Torres del Paine National Park and was expected to be relatively free of airborne pollutants due to its remote location in the southern hemisphere. Elemental and trace metal concentrations plus two enrichment indices supported this hypothesis. For example, concentrations of K and P in terrestrial mosses were enriched to support metabolic needs, while concentrations of trace metals like Pb (0.8 μg/g and Cu (4.6 μg/g) were lower than any reported in the published literature; enrichment factors for Pb and Cu also indicated a lack of atmospheric pollution. In addition, Pb and Cu concentrations in aquatic mosses (7.7 and 8.2 μg/g, respectively) were low compared to other published studies. However, Zn levels in aquatic mosses were somewhat high but most likely were due to local mineralogy rather than anthropogenic impacts. Overall, moss data support the use of the park as an excellent site for integrated global baseline monitoring.

Macroinvertebrate response to land cover, habitat, and water chemistry in a mining-impacted river ecosystem: A GIS watershed analysis

Abstract.This study addressed potential land use impacts to macroinvertebrate communities and water quality from past coal mining activities in the watershed of the North Branch of the Susquehanna River (located in northeastern Pennsylvania and southern New York). Landscape tools of GIS and remote sensing (RS) were used to calculate percent land cover (forest, agriculture, barren, urban, and water) from SPOT imagery (for tributaries) and Multi-Resolution Land Characteristics (MRLC) data (for river sites) on 17 subcatchments in the study area. The study design included field sampling at reach locations at four first- and second-order sites with low urban and low barren (mining) land cover, four similar sized sites with high mining and high barren land cover, five sites with intermediate combinations of urban and barren, and four mainstem river sites (60% forest and 35% agriculture). Sites were sampled in early fall for macroinvertebrates (17 parameters, e. g., EPT richness, percent filterers), benthic substrates (including deposits from mine waters), and 10 water chemistry parameters. A principal component analysis (PCA) on the macroinvertebrate parameters provided plot-clustering of subcatchments based generally on the above study design groupings; river sites clustered closer to smaller streams with low mining and urban land cover. Correlations identified six macroinvertebrate parameters (e. g., EPT richness, collector-gatherers) best associated with the three major axes of the PCA; each of these six indicators was analyzed in step-wise multiple regressions as dependent variables against land cover, benthic substrate, and water chemistry parameters. The strongest regressions were for percent barren land cover that explained the greatest amount of variation in both EPT richness and taxa richness. This mining affect was confirmed with dissolved iron and sulfate concentrations and levels of sedimentation and iron deposition explaining variability across several macroinvertebrate parameters. Comparison to the published literature on mining impacts indicated advantages to using a GIS watershed approach in multivariate analyses of stream ecosystem response. Also, this appears to be the first GIS watershed assessment of mining land use affects since most published studies of land use impacts to watersheds and lotic ecosystems have focused on either agriculture or urbanization.

Ordination of Functional Groups and Organic Matter Parameters from the Middle Fork of the Salmon River, Idaho

Classes of parameters (macroinvertebrate functional feeding groups, periphyton, transported and benthic organic matter) were examined by means of polar ordination techniques to determine distribution along a gradient from headwaters to large rivers. Functional group composition changed in a curvilinear fashion along the gradient. The largest portion of ecological change occurred within the headwater and small stream portion of the gradient and only slight changes occurred above a stream size of link magnitude 1000. The composition of stored and transported organic matter, together, changed in a linear fashion along the gradient in a manner similar to that found for macroinvertebrates. However, the difference in the form of the response suggests that environmental factors affect the combined composition of organic matter more evenly than functional feeding groups over the whole of a river system. All ordinations considered in this study sustain the conclusion that the ecological characterization of a study site is a function of its position along the stream environmental gradient. Thus, macroscopic patterns of ecological change within river systems as detected by the polar ordination technique, are both orderly and predictable in a downstream direction.

Ecosystem monitoring at global baseline sites

Integrated ecosystem and pollutant monitoring is being conducted at prototype global baseline sites in remote areas of the Noatak National Preserve, Alaska, the Wind River Mountains, Wyoming, and Torres del Paine National Park, Chile. A systems approach has been used in the design of these projects. This approach includes: (1) evaluation of source-receptor relationships, (2) multimedia (i.e., air, water, soil, biota) monitoring of key contaminant pathways within the environment, (3) the use of selected ecosystem parameters to detect anthropogenic influence, and (4) the application of a systems conceptual framework as a heuristic tool.Initial short-term studies of air quality (e.g. SO2, NO2) plus trace metal concentrations in mosses generally indicate pristine conditions at all three of the above sites as expected although trace metals in mosses were higher at the Wyoming site. Selected ecosystem parameters for both terrestrial (e.g. litter decomposition) and aquatic (e.g. shredders, a macroinvertebrate functional feeding group) habitats at the Wyoming site reflected baseline conditions when compared to other studies.Plans also are being made to use U.S. Department of Energy Research Parks for global change monitoring. This will involve cross-site analyses of existing ecological databases and the design of a future monitoring network based on a systems approach as outlined in this paper.

Ecological Correlates of Species Richness in Three Guilds of Lotic Macroinvertebrates

ABSTRACT Habitat factors were correlated with species richness for three guilds of lotic macroinvertebrates within the drainage basin of the Middle Fork of the Salmon River, Idaho. Species richness of filter feeders and scrapers increased with stream size whereas no significant longitudinal pattern was evident for gatherers. Annual variation in stream flow was inversely correlated with species richness for both filter feeders and scrapers, and food abundance was positively associated with scraper species richness. These relationships were consistent with the habitat templet concept of Southwood (1977). In contrast, our descriptive data gave no support for alternative, nonequilibrium models of community organization.

Problems of Long-Term Monitoring of Lotic Ecosystems

The scientific community has proposed a major long-term interdisciplinary research program [Global Change or the International Geosphere-Biosphere Program (IGBP)] to address environmental change on a global scale (National Research Council, 1986, 1988) with much recent attention directed toward the impacts of global warming from greenhouse gases (e.g., Houghton and Woodwell, 1989; Abrahamson, 1989). A crucial component of this program will be a worldwide network of interacting research sites dedicated to both experimental studies and long-term observations; these sites have been called “geo-biosphere observatories” by the IGBP (National Research Council, 1988) but are simply referred to as biosphere observatories in this chapter (see also SCOPE/MAB, 1987; University Corporation for Atmospheric Research, 1985). It is the observational or long-term environmental monitoring feature of these proposed biosphere observatories that we address.

Testing and application of ecosystem monitoring parameters

Our research has focused on the design, testing, and application of integrated monitoring programs from a multimedia (air, water, soil, biota) systems approach at several types of study sites. The goals of this paper are: 1) to evaluate selected atmospheric, terrestrial, and aquatic parameters at a high‐elevation site in Wyoming (USA), and 2) to illustrate the use of two of these parameters in the appraisal of aquatic ecosystem health at a biosphere reserve (Peoples Republic of China) and in the design of a landscape‐scale (over 6500 hectares) study of ecosystem impacts in Pennsylvania (USA). At the Wyoming site, five evaluation criteria were used to assess monitoring parameters: ecosystem conceptual framework, data variability, uncertainty, usability of methods, and cost‐effectiveness. Atmospheric concentrations of nitrates and nitric acid, and stream pH scored lowest overall because of high data variability, high uncertainty, and low cost‐effectiveness. Tropospheric ozone was ranked intermediate on mos...

Atmospheric trace element sampling at Torres del Paine national park, Chile

Atmospheric particulate samples were collected from 1985 through 1991 at a remote site in Torres del Paine National Park, Chile. High‐volume air monitors were used to collect these samples on polycarbonate membrane filters. The filters were then analyzed for trace elements including metals such as aluminum, copper, cadmium, lead, and zinc. The results indicate that atmospheric concentrations of metals at Torres del Paine are comparable or lower than those measured at other remote locations worldwide. Enrichment factors were calculated for each metal to compare the relative concentrations of these metals in the atmosphere to that of the soil. These enrichment factors indicate that despite the very low atmospheric levels observed to date at Torres del Paine, cadmium, lead and copper appear enriched in the atmosphere.

In situ nitrogen enrichment experiments in two Idaho (U.S.A.) streams

We conducted a series ofin situ experimental nutrient additions in two Idaho streams: Deep Creek, a desert stream located in Southeastern Idaho, and Big Wood River, situated in a mountainous region of Central Idaho. In both streams, a homogeneous reach was partitioned into almost identical channels. This allowed us to vary nutrient levels and measure algal response in experiments uncomplicated by differences in other factors.Ammonium nitrate was added to the treatment channels in Deep Creek. After nine days,Cladophora glomerata still predominated in both the control and treatment channels and algal biomass was not statistically different between the two. In the Big Wood River experiment significant differences in chlorophylla concentrations were not detected among three treatments of differing nitrogen enrichment and the control for both natural and artificial substrates. Also chlorophylla levels were not correlated with nitrogen concentrations, and the composition of algal communities remained similar among all treatments.We conclude that macronutrient enrichment of streams does not necessarily result in an increase in algal density or a change in algal community structure so long as other factors, which may limit the use of nutrients by algae, remain unaltered. Our results suggest that light, current velocity, and macroinvertebrate grazing may account for the failure of the periphyton to respond toin situ additions of nitrogen (and phosphorus) in our study streams.