Geology topics

P.M. Stewart

Publications and source records attributed to P.M. Stewart.

4 recordsLinked to original sources

USGS2000

Land use, habitat, and water quality effects on macroinvertebrate communities in three watersheds of a Lake Michigan associated marsh system

Three watersheds within a marsh system draining into Lake Michigan in northwest Indiana, USA, were studied for differences among land use, habitat conditions and water quality to determine their influence on macroinvertebrate community structure. Much of this area had been altered for agricultural, commercial, industrial and residential land uses. Land use, habitat conditions and water quality were significantly different among watersheds. Water quality varied more among streams than within streams. Several variables were related to land use, especially dissolved ions. Macroinvertebrate communities depicted neither a healthy wetland nor a healthy stream system. Some sites were typical of a sand-based, erosional stream system and others were more typical of a wetland system. Communities were different both in and among streams; relationships with water chemistry variables and land use suggested that community structure was a function of local-scale, abiotic factors rather than watershed-scale characteristics. These results show the importance of local-scale influences on the structure and function of macroinvertebrate communities. The development of the methods used to measure these local-scale landscape factors is important to restoration and management.

Indiana↗

USGS1999

The use of aquatic macrophytes in monitoring and in assessment of biological integrity

Aquatic plant species, populations, and communities should be used as indicators of the aquatic environment, allowing detection of ecosystem response to different stressors. Plant tissues bioaccumulate and concentrate toxin levels higher than what is present in the sediments; and this appears to be related to organic matter content, acidification, and buffering capacity. The majority of toxicity studies, most of these with heavy metals, have been done with several Lemna species and Vallisneria americana. Organic chemicals reviewed include pesticides and herbicides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and other industrial contaminants. The use of aquatic plant communities as bioindicators of environmental quality was evaluated for specific characteristics and indices that may assess biological integrity. Indices such as the floristic quality index (FQI) and coefficient of conservatism (C) are pioneering efforts to describe the quality of natural areas and protect native biodiversity. Our case study in the Grand Calumet Lagoons found that 'least-impacted' sites had the greatest aquatic plant species richness, highest FQI and C values, and highest relative abundance. Lastly, we introduce the concepts necessary for the development of a plant index of biotic integrity. Development of reference conditions is essential to understanding aquatic plant community structure, function, individual health, condition, and abundance. Information on guild development and tolerance definition are also integral to the development of a multi-metric index.

Book chapter↗

USGS1998

Application of an index of biotic integrity for dunal, palustrine wetlands: Emphasis on assessment of nonpoint source landfill effects on the Grand Calumet Lagoons

Using a newly modified index of biotic integrity for assessing biological integrity of fish communities in dunal, palustrine wetlands, we assessed the non-point source influence of an industrial landfill on the Grand Calumet Lagoons. The landfill is primarily an iron and steel manufacturer's slag waste. No sensitive species, hybrids, headwater species, and either few or no simple lithophilic spawning species were collected from any of the sites in the Grand Calumet Lagoons. Species catch-per-unit of effort varied significantly between reaches in the Middle Lagoon and the West Lagoon. The most disturbed areas were adjacent to the industrial landfill and along the southern shore near the outflow from the West Lagoon. Near- and far-field stations possessed similar numbers of species and relative abundance. The near-field stations showed an increase in tolerant species, a higher proportion of omnivores and carnivores, and a lower environmental quality rating of ‘poor-very poor’. The far-field sites were classified as having ‘fair’ biological integrity and showed an increase in relative abundance, proportion of sensitive species, and an increase in simple lithophils. The loss of biological integrity in the West Pond was not accurately predicted using the modified index of biotic integrity, even though it was rated as extremely degraded by the biological diversity indices. Fish communities were negatively impacted by proximity to the landfill.

Indiana↗

USGS1996

Seepage measurements from Long Lake, Indiana Dunes National Lakeshore

Long Lake, located near Lake Michigan within the dune-complexes of Indiana Dunes National Lakeshore, USA, was formed some time during the Pleistocene and Holocene epochs. A surficial aquifer underlies Long Lake, which is either a source or sink for the later. The hydrologic processes in the lakeshore and surrounding environs have been significantly altered during the agricultural, municipal, and industrial development of the region. Limited data suggest that the organisms of Long Lake have elevated levels of several contaminants. This study attempts to quantify seepage within the lake to assess the potential threat to groundwater quality. Seepage measurements and minipiezometric tests were used to determine seepage within the lake. Seepage measurements and minipiezometric tests suggest that water seeps out of Long Lake, thus recharging the groundwater that flows southwest away from the lake. There is a great deal of variability in the seepage rate, with a mean of 11.5×10 -4 ±11.2×10 -4 m d -1 . The mean seepage rate of 0.3 m yr -1 for Long Lake is greater than the 0.2 m yr -1 recharge rate estimated for the drainage basin area. The Long Lake recharge volume of 2.5 × 10 5 m 3 yr -1 is approximately 22% of the volume of the lake and is significant when compared to the total surface recharge volume of 4.8 × 10 5 m 3 yr -1 to the upper aquifer of the drainage area. There is a potential for contamination of the groundwater system through seepage from the lake from contaminants derived from aerial depositions.

Indiana↗