Robert A. Coler

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.

A procedure for the routine biological evaluation of urban runoff in small rivers

Abstract A rationale and stepwise procedure for the biological evaluation of urban runoff in small rivers is described. The protocol is predicated on the application of the Brillouin diversity index to collections of benthic macroinvertebrates isolated from artificial substrates in the course of a year.

Changes in oxygen consumption and nitrogen metabolism in the dragonfly Somatochlora cingulata exposed to aluminum in acid waters

Oxygen consumption, ammonia excretion and changes in O:N ratios by the dragonfly Somatochlora cingulata were measured in four nymphal growth stages, relative to aluminum concentrations and low pH. A differential reduction in respiration and ammonia excretion rates resulted in an increase in ON ratios for all nymphal stages. The earlier stages, however, were the most sensitive. The ratios obtained were indicative of a decreased dependence on protein reserves and increased utilization of carbohydrates or lipid reserves. Also observed was an increase in the haemolymph pH and glutamate levels with a concomitant accumulation of tissue ammonia.

The effect of aluminum in soft water at low pH on oxygen consumption by the dragonfly Libellula julia Uhler

When subjected to a series of elevated Al and H+ concentrations spanning environmentally relevant levels, the dragonfly Libellula julia respired at a rate lower than the controls. This trend was consistent at all levels but only attained significance (p < 0.05) at pH 4.0 with A1 levels of 3.0 and 30 mg 1−1. Low pH alone does not depress respiratory rates as greatly as Al and low pH combined. The authors speculate on some apparent inconsistencies found in the literature.

The effect of aluminum in soft water at low pH on water balance and hemolymph ionic and acid-base regulation in the dragonflyLibellula julia Uhler

The physiological responses of last instarLibellula julia nymphs exposed for 96 (or 192) h to low pH (4.0 and 2.3) and elevated Al concentrations (0.3, 3, and 30 mg l−1) at low pH were investigated. To some extent, both low pH alone and Al at low pH were found to affect water balance (wet weight and hemolymph volume), ionic regulation (hemolymph osmolality and concentrations of Na+, Cl−, and K+), and acid-base balance (hemolymph pH). The extent and significance of these alterations are discussed.

The Effect of Mineral Acids and Aluminum from Coal Leachate on Substrate Periphyton Composition and Productivity

Taylor Brook drains agricultural and grazing land surrounding Hawley swamp in North Amherst, Massachusetts. It is a second order stream with an average flow of less than 4 cfs in the study area, and a total length of 5 km. Riparian vegetation occurs mainly as aspens. Silt and sand, together with stretches of gravel, make up the stream bed. The test site is within a pasture, 1 km below a coal leachate seepage problem and 10 m above the confluence of a first order tributary. Shifts in pH from 6.8 to 4.4 and in aluminum from 0.03 to 3.8 ppM were noted in the stream. Tubular substrates, colonized by the indigenous periphyton of a clean water tributary were transferred to the contaminated stream and monitored for structural and functional perturbations. Net productivity, measured by oxygen evolution, was reduced to zero after 20 days exposure to the polluted stream. All diatom and cyanobacteria motility ceased. Low pH alone proved sufficient to eliminate net productivity, but it did not restrict algal movement. 22 references, 3 figures, 2 tables.

Oxygen Consumption by Nymphs of Dragonfly Somatochlora cingulata (Odonata: Anisoptera)

Abstract Determination of oxygen consumption a t 20 ± 1 °C was made in nymphs of the dragonfly Somatochlora cingulata. Three methods of measuring oxygen uptake rates were compared with respect to reproducibility and sensitivity. A flow-through regime, employing chemical titration of oxygen yielded the most reproducible results, though titration is not as sensitive as manometric based procedures. The Gilson respirometer and static chemical titration procedures were both more variable.

Oxygen consumption and ammonia excretion in the detritivore caddisfly Limnephillus sp. exposed to low pH & aluminum

Respiration and excretion were measured relative to pH and aluminum in three nymphal weight groups of a detritivore caddisfly. Although a reduction in respiration rates was consistently observed within all stages exposed to a pH of 4 and 0.3 mg 1−1 of aluminum, the differencewas not statistically significant among treatments. Excretion rates, on the other hand, were significantly increased throughout the low pH treatment, but not when exposed to low pH and aluminum combined. The derived O:N ratios indicate low pH causes a shift to a protein-oriented metabolism which was most pronounced in the smallest size group. Aluminum mitigates this effect.

A laboratory assessment of the toxicity of urban runoff oh the fathead minnow (pimephales promelas)

Abstract The early life stage effects of urban runoff (rain and snowmelt) on hatching, growth and survival of the fathead minnow (Pimephales promelas) was assessed in static and flow‐through systems. The data indicate a Maximum Allowable Toxicant Concentration (MATC) and a reduction of growth to 50% of controls at 28% and 60% runoff, respectively. Hatchability and average lengths were not as sensitive indicators of stress as millimeters produced per treatment. The data indicate a maximum toxicity in the fall which coincided with the reported drop in macroinvertebrate diversity during the same period, when untreated runoff events can contribute up to 1/4 of the river flow.

Microbial populations as determinants in protozoan succession

Abstract Twelve species of ubiquitous soil and water bacteria were randomly selected as substrates for a soil ciliate. Six species (particularly Escherichia coli and Aerobacter aerogenes) supported a flourishing protozoan population, while the remaining six (predominantly of the genus Arthrobacter) were of meagre nutritive value. Preliminary investigations indicate the presence of a toxic cytoplasmic principle that limits protozoan predation. This factor may account for the universal distribution and persistence of Arthrobacter while their nutritive attractiveness may explain the rapid disappearance of coliforms from soil and water.