Hydrologic and Water Quality Functions of a Disturbed Wetland in an Agricultural Setting1

Abstract: In 2006, we collected flow, sediment, and phosphorus (P) data at stream locations upstream and downstream of a small degraded wetland in south‐central Wisconsin traversed by a stream draining a predominantly agricultural watershed. The amount of sediment that left the wetland in the two largest storms, which accounted for 96% of the exported sediment during the observation period, was twice the amount that entered the wetland, even though only 50% of the wetland had been inundated. This apparently anomalous result is due to erosion of sediment that had accumulated in the low‐gradient channel and to the role of drainage ditches, which trapped sediment during the wetland‐filling phase. In the case of total P, the inflow to the wetland approximately equaled the outflow, although the wetland sequestered 30% of the incoming dissolved reactive P. The discrepancy is almost certainly due to net export of sediment. Many wetlands in the glaciated midwestern United States are ditched and traversed by low‐gradient channels draining predominantly agricultural areas, so the processes observed in this wetland are likely to be common in that region. Knowledge of this behavior presents opportunities to improve water quality in this and similar regions.     

Sediment quality triad assessment of an industrialized estuary of the northeastern USA

The lower Passaic River in northern New Jersey (USA) has been heavily industrialized since the mid-nineteenth century and its shoreline and aquatic habitats degraded or destroyed. Similar to other urban systems, Passaic River sediments, both surface and buried, historically have contained elevated levels of numerous contaminants that may pose risks to ecological receptors and humans. Sediments from 15 stations in the lower Passaic River and 3 reference stations in the Mullica River in southern New Jersey were sampled in 1999 and characterized for chemical contamination, toxicity, and impairment of the benthic community. The objective of this study was to determine the incidence, degree, and nature of degraded surficial sediments in the area to support subsequent plans for restoration of the system. Results demonstrated that Passaic River sediments had concentrations of many organic and inorganic contaminants at levels significantly greater than the reference area and effect-based guidelines. Sediments were toxic to marine amphipods at 11 stations and the benthic assemblages were impaired relative to the reference area at all stations. The weight-of-evidence of this sediment quality triad (SQT) assessment indicates that impacts from multiple contaminants are occurring throughout the lower Passaic River and, that these impacts must be evaluated further and addressed as part of ongoing restoration initiatives for the river.     

Liver lesions in demersal fishes near a large ocean outfall on the San Pedro Shelf, California

The prevalence of toxicopathic liver lesions in demersal fish on the San Pedro Shelf, California was determined for a 15-year period (1988–2003). Fish livers were sampled at fixed locations as part of the Orange County Sanitation Districts (OCSD) ocean monitoring program. Histopathological examination of selected fish liver tissues was studied to determine whether the wastewater discharge had affected fish health. The prevalence of toxicopathic lesion classes neoplasms (NEO), preneoplastic foci of cellular alteration (FCA), and hydropic vacuolation (HYDVAC) varied among species and locations. For all species sampled, severe lesions occurred in 6.2% of the fish examined (n = 7,694). HYDVAC (4.1%) was the most common toxicopathic lesion type followed by FCA (1.4%) and NEO (0.7%). HYDVAC occurred only in white croaker (Genyonemus lineatus), accounting for 84.8% of the toxicopathic lesions for this species. Prevalence of HYDVAC, NEO, and FCA in white croaker was 15.2, 2.0, and 0.7%, respectively. The prevalence of HYDVAC and NEO in white croaker increased with age and size but there was no sexual difference. A linear regression model was used for hypothesis testing to account for significant differences in fish size (and age for croakers) at the different sampling locations. This analysis showed that for HYDVAC there was no spatial or location effect for lesion rate or size/age of onset. For NEO, the model predicted that white croaker near the wastewater outfall may acquire these lesions at a smaller size/younger age, and at a higher rate, than at other sites. However, this result may be biased due to the unequal size frequency distributions and the low prevalence of NEO in white croaker at the different sampling sites. Bigmouth sole (Hippoglossina stomata) had a prevalence of FCA and NEO of 1.3 and 0.35%, respectively, but the prevalence and distribution of lesions was too few for statistical testing. There was no sexual difference for lesion prevalence in hornyhead turbot (Pleuronichthys verticalis) and the prevalence of FCA and NEO was 3.4 and 0.37%, respectively. FCA prevalence increased with size in hornyhead turbot and there were no significant spatial differences for lesion rates and fish size at lesion onset. Overall, consistent spatial differences for lesion prevalence were not demonstrated and highlight the analytical difficulties of detecting a possible point source impact when the effect is rare, correlated with the size/age structure of the population, and may be caused by exposure to unknown multiple sources. Thus, the usefulness of liver histopathology as a point-source monitoring tool is best applied to where the spatial scale of impact generally exceeds the home range of the target species.     

A Stream–Wetland–Riparian (SWR) index for assessing condition of aquatic ecosystems in small watersheds along the Atlantic slope of the eastern U.S.

As part of a regional study by the Atlantic Slope Consortium (ASC) to develop ecological and socioeconomic indicators of aquatic ecosystem condition, we developed and tested a protocol for rapidly assessing condition of the stream, wetland, and riparian components of freshwater aquatic ecosystems. Aspects of hydrology, vegetation, in-stream and wetland characteristics, and on-site stressors were measured in the field. The resulting metrics were used to develop an index of overall condition, termed the Stream–Wetland–Riparian (SWR) Index. Values of this Index were compared to existing biotic indices and chemical measures, and to a Landscape Index created using satellite-based land cover data and a geographic information system (GIS). Comparisons were made at several levels of spatial aggregation and resolution, from site to small watershed. The SWR Index and associated Landscape Indices were shown to correlate highly with biological indicators of stream condition at the site level and for small contributing areas. The landscape patterns prevalent throughout the entire watershed do not necessarily match the patterns found adjacent to the stream network. We suggest a top-down approach that managers can use to sequentially apply these methods, to first prioritize watersheds based on a relative condition measure provided by the Landscape Index, and then assess condition and diagnose stressors of aquatic resources at the subwatershed and site level.     

Precopulatory guarding-time of the male amphipod Eogammarus oclairi: effect of population structure

This study shows that population structure affects guarding time in the amphipod Eogammarus oclairi Bousfield. In the laboratory, mean guarding time depended on the male weight-frequency distribution, operational sex ratio, and male density. It was longer when the male population encompassed a broad range of weights than when the weight distribution was narrower; however, guarding time did not differ when the population's weight distribution was narrow and composed of either small or large males. Mean guarding time varied between a few hours when the operational sex ratio (male:female) was 1:3 to>7 d when the sex ratio was 2:1. It was also affected by male density, increasing as male density increased. The results suggest that the stimulus to guard depends on the intensity of male-male competition.     

Some of the Nineteenth Century Origins of the Sustainability Concept

Interpreting and applying the concept of sustainable development is increasingly viewed as being the way to promulgate just and practicable economic, environmental and social policy. It is thus important that there be increased public and political awareness concerning the origins of economic theory, and its early relationship to sustainability concepts. While the term 'sustainable development' was popularised by the World Commission on Environment and Development report Our Common Future in 1987, it is generally recognised that notions of sustainability were promoted in `limits to growth' and 'green' discourses in the early 1970s (Meadows et al.: 1974, The Limits to Growth: A Report for the Club of Rome, Potomac Associates and Pan Books, London and Sydney). However, there is little acknowledgement of the way in which nineteenth century intellectuals, from a range of disciplines, conceptualised the importance of balancing economic, social and environmental sustainability in their quest for justice and the conservation of nature.There was a considerable exchange of ideas on `political economy' and nature across Europe, and later the Americas, from the middle of the eighteenth century. This discourse reached its intellectual peak in the nineteenth century. During that era there was a proliferation of literature that was aimed at improving the human condition and recognising humanity's dependence upon nature. In Europe and the USA the participants in the debate included Cantillon, Quesnay, Condorcet, Galiani, Von Hayek, Marx and George. Due to the breadth of this influential body of work, we focus here on the British Victorian thinkers such as Darwin, Malthus, Martineau and Mill. These thinkers influenced each other in developing their theories and ideas in science, politics, economics and philosophy, and were influenced in turn by an earlier generation of intellectuals, such as Adam Smith. For the Victorian thinkers, conserving nature while trying to improve the distribution of wealth was a not a paradox, but a moral duty, and for them Smith's `rational' pursuit of self-interest could only be followed if it did not interfere with 'the rules of justice'. We argue that the manner in which these thinkers conceptualised their theories and ideas represents the nineteenth century origins of sustainability concepts.     

Growth and average growth rates of tanner crab zoeae collected from the plankton

Growth of the two zoeal stages of Tanner crabs, Chionoecetes bairdi and C. opilio, was estimated by changes in total dry weight of individuals sampled from plankton of the southeastern Bering Sea during the springs of 1977, 1978, 1980 and 1981. Since the age of larvae within a stage cannot be determined, approximate beginning and end weights of each stage were used. Epidermal retraction, conspicuous under low magnification of a dissecting microscope, was used to identify larvae presumed to be in advanced stages of growth (biomass) for their respective larval stage. This assumption was corroborated by holding retracted larvae that subsequently molted on board ship, by comparison of dry weight measurements from extensive field sampling, and by the low proportion of larvae showing such conspicuous retraction. An exponential growth model was used to calculate the average daily growth rate based on estimates of stage duration in the field. The adequacy of this model for describing the average rate, rather than the pattern, of growth is discussed. Carbon-specific rates of respiration from discrete measurements and of growth averaged for each zoeal stage indicate average net growth efficiencies comparable to laboratory results for other species. The method used to estimate growth should be applicable to other larval decapods and offers the advantage of estimating this parameter from data gathered from natural populations.Contribution No. 652 of the School of Fisheries, University of Washington     

Follow-up on a 1962 case-control study of trace elements as risk factors for stomach cancer in Iceland

In 1988 a follow-up investigation was made of a case-control study conducted in 1962 in Iceland which tested hypotheses that trace elements in pasture grass, drinking water and cow's milk were associated through diet with cancer of the stomach. Samples were collected in 1962 from 26 farms in the northern county of Skagafjardarsysla and 30 farms in the southern county of Rangarvallasysla. The main objective of the present study was to establish the cancer experience of the 297 residents of the 56 farms since 1962. In the records of the Icelandic Cancer Registry 31 cases of cancer of all types were identified. Six were cancers of the stomach and four of these were from control farms. The revised comparison of trace element analyses for case and control farms yielded no change in earlier results for pasture grass in Skagafjardarsysla (excess levels of B, Na, AI, Fe and Cu on cancer farms), but B appeared as a significant deficiency on cancer farms in Rangarvallasysla. Drinking water results were unchanged (no significant differences), but for milk the significantly high mean values of Fe and Zn reported earlier for Rangarvallasysla did not appear. The pronounced geographical variation in Icelandic stomach cancer incidence that was widely cited from 1961–65 is now believed to have been spurious.