Paul J. Godfrey

Ecological effects of urban stormwater runoff on benthic macroinvertebrates inhabiting the Green River, Massachusetts

Although it has been demonstrated that urban stormwater can alter the quality of receiving waters, the corresponding impact on aquatic biota remains essentially undocumented. A year-long intensive study, therefore, was implemented to monitor and describe the ecological effects exerted by urban runoff on benthic macroinvertebrates.Rock-filled, basket-type artificial substrates deployed periodically in nonurban and urban river reaches yielded collections of macroinvertebrates that furnished data for: (1) species diversity (the Brillouin index, H), (2) hierarchical diversity, (3) major taxa composition, and (4) collection dissimilarity at the species level.The overall results from these four analytical procedures strongly indicate that the macrobenthic community became progressively disrupted downstream in the urban reach. The high degree of correspondence between the known sources of urban runoff and the observed effects on the benthic community are forceful arguments that urban runoff is the causal agent of disruption. The impact is not confined to periods following heavy rains. Instead the pollutants appear to remain in the system. The stress imposed by them was most acute during the summer low flow and was probably localized in or near the stream bed.To assess the impact of urban runoff on an aquatic ecosystem, physical, chemical, and biological monitoring should routinely consider the stream bed microzone. Urban runoff pollutant loading standards must take into account the apparent long-term residence of pollutants in the substrate and the associated stress of summer low flows.

Effects of Hurricane Ginger on the Barrier Islands of North Carolina

The two barrier-island systems of North Carolina responded to the storm waves and surges of Hurricane Ginger in a strikingly different manner. Within the northern sector, which has been stabilized by man, erosion and dune recession were extensive. In the southern sector, as yet relatively unmodified, overwash and associated deposition were the dominant processes. This difference offers important geologic, ecologic, and land management implications.

Identification of road salt contamination using multiple regression and GIS

A multiple regression model of atmospheric deposition of salt, combined with geographic information systems (GIS) data on four classes of roads, is used to predict sodium concentrations in 162 randomly chosen streams in Massachusetts. All four classes of roads, as well as atmospheric deposition, were found to be highly significant in a model that explains 68% of the observed variation in sodium concentration. The highest salt loading rates are associated with interstate and major state roads with an estimated 22,500 and 17,700 kg of salt per kilometer, respectively. Our mass balance calculations indicate road salt is the major source of salt to the streams in Massachusetts.We examined some of the common statistical problems associated with the use of multiple regression for this type of analysis. Our confidence in the accuracy of the loading rates estimated above are limited by the collinear nature of environmental data and uncertainties related to model specification. Our results suggest multiple regression techniques can lead to overconfidence in the accuracy of the estimated loading rates and thus should not be used as the basis for policy unless the model is validated.

EVIDENCE OF RECOVERY FROM ACIDIFICATION IN MASSACHUSETTS STREAMS

A ten year survey of water quality in 330 Massachusetts streams was conducted to examine the rate and pattern of recovery from acidification. Meta-analysis was used to combine the results of the 330 non-parametric trend tests into an overall test for trend in a variety of water quality variables including pH, acid neutralizing capacity (ANC), and major inorganic ions. Analysis of trends in the raw data indicates both pH and ANC are increasing. After detrending for variations in stream runoff, we estimate the streams are recovering from acidification at a rate of +0.021 pH units/year and +2.4μeq/L/year, for pH and ANC respectively. These trends appear to be related to declines in sulfate (−1.8μeq/L/year), while base cation trends were mixed. Meta-analysis reveals the trends are not always homogeneous between seasons or between sites.While it is commonly assumed that the low ANC systems are most ‘sensitive’ to changes in acid or base inputs, we found the greatest rates of change in ANC were associated with the high ANC systems. The greatest increases in pH were seen in the low ANC streams as expected. The results also suggest streams respond quickly to changes in precipitation inputs and stream monitoring networks may be valuable as an early detection technique for changes in environmental quality.

Acidity status of surface waters in Massachusetts

The Massachusetts Acid Rain Monitoring project surveyed 80.5% of the states 5294 named water bodies between 1983 and 1985. PH and acid neutralizing capacity (ANC) were measured monthly the first 14 mo and semi-annually afterwards. Sample collection and analysis were performed by volunteers. The majority of surface waters in Massachusetts were found to be sensitive to possible long term acidification, with 63% exhibiting ANC less than 200 μeq L−1 and 22% with ANC less than 40 μeq L−1. Seasonal patterns in ANC were observed, the median ANC being 384 μeq L−1 in summer/fall and 134 μeq L−1 in winter/spring. Geographical differences were also found across the state: the streams and lakes with lowest pH and ANC were located in the southeastern and north-central parts of the state, while the most alkaline surface waters were found in the western-most part of the state, which is the only area of the state with significant limestone deposits.

Preliminary Evaluation of Forced Air-Drying for Preserving Chlorophyll on Glass Fiber Filters

ABSTRACT An alternative method of preserving filtered chlorophyll samples allows immediate filtration of samples by professional lake managers and volunteer monitors with inexpensive transfer to a laboratory. Using a simple forced air-drying device, samples can be preserved for two weeks and, perhaps, as long as 1–1/2 months without significant change in pigment levels. Filters may be sent by first class mail to a laboratory after wrapping the filters in aluminum foil. A series of 5 experiments was conducted to explore the parameters for maximum extension of the holding time. Results suggest that preserving filters by forced air-drying may be equivalent to other methods such as immediate analysis or freezing, and may be better under many conditions common to field sampling.