Aquatic and terrestrial organic matter in the diet of stream consumers: implications for mercury bioaccumulation

The relative contribution of aquatic vs. terrestrial organic matter to the diet of consumers in fluvial environments and its effects on bioaccumulation of contaminants such as mercury (Hg) remain poorly understood. We used stable isotopes of carbon and nitrogen in a gradient approach (consumer isotope ratio vs. periphyton isotope ratio) across temperate streams that range in their pH to assess consumer reliance on aquatic (periphyton) vs. terrestrial (riparian vegetation) organic matter, and whether Hg concentrations in fish and their prey were related to these energy sources. Taxa varied in their use of the two sources, with grazing mayflies (Heptageniidae), predatory stoneflies (Perlidae), one species of water strider (Metrobates hesperius), and the fish blacknose dace (Rhinichthys atratulus) showing strong connections to aquatic sources, while Aquarius remigis water striders and brook trout (Salvelinus fontinalis) showed a weak link to in-stream production. The aquatic food source for consumers, periphyton, had higher Hg concentrations in low-pH waters, and pH was a much better predictor of Hg in predatory invertebrates that relied mainly on this food source vs. those that used terrestrial C. These findings suggest that stream biota relying mainly on dietary inputs from the riparian zone will be partially insulated from the effects of water chemistry on Hg availability. This has implications for the development of a whole-system understanding of nutrient and material cycling in streams, the choice of taxa in contaminant monitoring studies, and in understanding the fate of Hg in stream food webs.     

Correction to: Energetic trade-offs and feedbacks between behavior and metabolism influence correlations between pace-of-life attributes

Behavioral Ecology and Sociobiology - Comparative analyses have demonstrated the existence of a ”pace-of-life” (POL) continuum of life-history strategies, from fast-reproducing...     

Spatiotemporal calibration of atmospheric nitrogen dioxide concentration estimates from an air quality model for Connecticut

Environmental and Ecological Statistics - A spatiotemporal calibration and resolution refinement model was fitted to calibrate nitrogen dioxide ($$\hbox {NO}_2$$) concentration estimates from the...     

WATERSHED BASED,INSTITUTIONAL APPROACH TO DEVELOPING CLEAN WATER RESOURCES1

ABSTRACT: Access to clean and sufficient amounts of water is a critical problem in many countries. A watershed approach is vital in understanding pollution pathways affecting water resources and in developing participatory solutions. Such integration of information with participatory approaches can lead to more sustainable solutions than traditional “crisis‐to‐crisis” management approaches. This study aims at applying a watershed based joint action approach to manage water resources. Since most watersheds have urban and rural sources of pollution and a wide disparity in access to and use of water, alternative solutions need to take an integrated approach through cooperative actions. An institutional model was applied to seven subwatersheds in Honduras to evaluate various sources and effects of water contamination and water shortages. Two specific pathways of water resources degradation were studied (contamination from coffee pulp manufacturing and urban nonpoint sources) to develop alternative solutions that mitigate downstream impacts of access to clean water. A locally driven joint mechanism to reuse coffee pulp in farming systems is proposed. Such an institutional solution can maximize benefits to both farms and the coffee pulp industry. A combination of education and investment in sanitary facilities in urbanizing areas is proposed to minimize urban sources of water contamination.     

LOW FLOW SPATIAL CHARACTERISTICS IN FORESTED HEADWATER CHANNELS OF SOUTHWEST WASHINGTON1

ABSTRACT: Patterns of dry season surface flow in forested headwater channels of southwest Washington were observed during August to September 2001 and July to October 2002. In 2001, 17 channels were sampled once, and the uppermost points of continuous flow (CF) and surface water (SW) were located. In 2002, sampling was replicated three to five times at each of 21 channels. Annual and seasonal data suggested that the location of SW varied less than CF. In most channels, SW remained at or near the channel head year around. The pattern of surface flow between CF and the channel head was used to test alternative hypotheses describing dry season recession patterns: (A) surface flow consistently retreats in a downstream direction, and (B) flow comes from fixed sources along the channel, thus surface flow retreats up‐channel towards these sources. The dominant surface flow spatial pattern in streams less than 30 percent slope was increased intermittency without a clear pattern of retreat, and thus inconsistent with either hypothesis. High gradient channels (< 30 percent slope) exhibited a combination of increased intermittency, and extensive upward retreats of surface water consistent with Hypothesis B. Differences between 2001 and 2002 suggest late summer flows in small headwater basins were controlled by spring precipitation, rather than the typically greater winter precipitation.     

Demystifying the EMIS purchasing process and decisions: Look (and plan) before you leap

The proliferation of environmental, health, and safety regulations in recent years has increased the complexity and cost of regulatory compliance for companies. In response to the growing complexities of environmental management, many firms are turning to information systems for tracking, managing, and automating their environmental activities and information. An environmental management information system (EMIS), however, is not an end in itself. A successful EMIS supports and facilitates the integration of environmental management into business functions. Effective planning is essential for placing short-term information system development in the context of a long-range comprehensive environmental management strategy. This article presents specific pitfalls to avoid when purchasing environmental management software. Numerous companies have discovered that the true costs of EMIS implementation stem from the political and organizational costs of getting employees to use systems, particularly when they require alterations in existing work processes. The up-front purchase price often represents less than 50 percent of the total system implementation cost. Failure to adequately research and plan frequently results in costly training, high modification or user fees, incompatibilities with other applications, or vendor dependence. The article then discusses the range of options in the EMIS marketplace and offers many practical suggestions to approach and plan effective implementation of an EMIS.     

EFFECTS OF BASIN-SCALE TIMBER HARVEST ON WATER YIELD AND PEAK STREAMFLOW1

ABSTRACT: Streamflow changes resulting from clearcut harvest of lodgepole pine (Pinus contorta) on a 2145 hectare drainage basin are evaluated by the paired watershed technique. Thirty years of continuous daily streamflow records were used in the analysis, including 10 pre-harvest and 20 post-harvest years of data. Regression analysis was used to estimate the effects of timber harvest on annual water yield and annual peak discharge. Removal of 14 million board feet of lodgepole pine (Pinus contorta) from about 526 hectares (25 percent of the basin) produced an average of 14.7 cm additional water yield per year, or an increase of 52 percent. Mean annual daily maximum discharge also increased by 1.6 cubic meters per second or 66 percent. Increases occurred primarily during the period of May through August with little or no change in wintertime streamflows. Results suggest that clearcutting conifers in relatively large watersheds (> 2000 ha) may produce significant increases in water yield and flooding. Implications of altered streamflow regimes are important for assessing the future ecological integrity of stream ecosystems subject to large-scale timber harvest and other disturbances that remove a substantial proportion of the forest cover.     

A CONFIRMATION OF MOUNT'S AUTOPSY TECHNIQUE FOR ZINC-CAUSED FISH MORTALITY1

ABSTRACT. A total of 203 bluegill sunfish (Lepornis macrochirus, Rafinesque) which had been used in several acute zinc experiments carried out under varied environmental conditions were autopsied according to Mount's procedure for determining fish mortality due to zinc poisoning. Three classes of fish were used: those exposed to but not killed by zinc; those killed by zinc; and those not exposed to zinc. Two statistical tests were used to analyze these data and both tests gave results indicating significant differences (a = .05) between all three classes of fish. This indicates that the Mount autopsy technique is very probably a valid generalization. The possibilities of using Mount's technique as a predictive tool are discussed.