Geology topics

M. C. Christman

Publications and source records attributed to M. C. Christman.

3 recordsLinked to original sources

USGS2020

Understanding nekton use of estuarine habitats in the northern Gulf of Mexico: Guidebook for natural resource managers and restoration practitioners

Without a comprehensive understanding of nekton use of key habitats across locations, natural resource managers and restoration practitioners in the northern Gulf of Mexico region lack a key tool to assist in their efforts to design, implement, and monitor effective coastal restoration and protection efforts in the decades to come. To address this need, Abt helped conduct a systematic literature review, data compilation, and meta-analysis to evaluate nekton use of estuarine habitats in the northern Gulf of Mexico.

Louisiana, Texas↗

USGS2006

Evaluation of osprey habitat suitability and interaction with contaminant exposure

Ospreys (Pandion haliaetus) have been the focus of conservation efforts since their dramatic population decline attributed to dichlorodiphenyltrichloroethane and related chemicals in the 1960s. Several recent studies of ospreys nesting in the United States have indicated improved reproduction. However, the density of breeding ospreys varies greatly among locations, with some areas seemingly habitable but not occupied. Because of concerns about pollution in the highly industrialized portions of the Delaware River and Bay, USA, we evaluated contaminant exposure and productivity in ospreys nesting on the Delaware River and Bay in 2002. We characterized habitat in the coastal zone of Delaware, USA, and the area around the river in Pennsylvania, USA, using data we collected as well as extant information provided by state and federal sources. We characterized habitat based on locations of occupied osprey nests in Delaware and Pennsylvania. We evaluated water clarity, water depth, land use and land cover, nest availability, and contaminants in sediment for use in a nest-occupancy model. Our results demonstrated that the presence of occupied nests was associated with water depth, water clarity, distance to an occupied osprey nest, and presence of urban land use, whereas a companion study demonstrated that hatching success was associated with the principal components derived from organochlorine-contaminant concentrations in osprey eggs (total polychlorinated biphenyls, p,p'-dichlorodiphenylethylene, chlordane and metabolites, and heptachlor epoxide). Our study provides guidelines for resource managers and local conservation organizations in management of ospreys and in development of habitat models that are appropriate for other piscivorous and marsh-nesting birds.

Journal of Wildlife Management↗

USGS2005

Effects of contaminant exposure on reproductive success of ospreys (Pandion haliaetus) nesting in Delaware River and Bay, USA

Despite serious water-quality problems and pollutant loading and retention, Delaware River and Bay(USA) provide important wildlife habitat. In 2002, we conducted a comprehensive evaluation of contaminant exposure and reproduction of ospreys ( Pandion haliaetus ) breeding in Delaware River and Bay. Sample eggs were collected from 39 nests and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury; a subset of 15 eggs was analyzed for perfluorinated compounds and polybrominated diphenyl ethers (PBDEs). The fate of each nest was monitored weekly. Concentrations of 10 organochlorine pesticides or metabolites, total PCBs, and several toxic PCB congeners were greater ( p < 0.05) in eggs collected between the Chesapeake and Delaware Canal (C and D Canal) and Trenton (Delaware River and northern Bay) compared to other sites. Concentrations of p,p ′-dichlorodiphenyldichloroethylene ( p,p ′-DDE; 0.785–3.84 μg/g wet wt) and total PCBs (5.50–14.5 μg/g wet wt) in eggs collected between the C and D Canal and Trenton were similar to levels recently found in the Chesapeake Bay. In all study segments, at least one young fledged from 66 to 75% of nests. Productivity for Delaware Inland Bays (reference area) and southern Delaware Bay was 1.17 and 1.42 fledglings/active nest, respectively; north of the C and D Canal, productivity was 1.00 fledgling/active nest, which is marginally adequate to maintain the population. Using these data, a logistic regression model found that contaminant concentrations ( p,p ′-DDE, heptachlor epoxide, chlordane and metabolites, and total PCBs) were predictive of hatching success. Several perfluorinated compounds and PBDEs were detected in eggs at concentrations approaching 1 μg/g wet weight. These findings provide evidence that contaminants continue to be a significant stressor on osprey productivity in the northern Delaware River and Bay.

Delaware, New Jersey, Pennsylvania,↗