Geology topics

R.P. Morgan

Publications and source records attributed to R.P. Morgan.

6 recordsLinked to original sources

USGS2008

Interaction between urbanization and climate variability amplifies watershed nitrate export in Maryland

We investigated regional effects of urbanization and land use change on nitrate concentrations in approximately 1,000 small streams in Maryland during record drought and wet years in 2001-2003. We also investigated changes in nitrate-N export during the same time period in 8 intensively monitored small watersheds across an urbanization gradient in Baltimore, Maryland. Nitrate-N concentrations in Maryland were greatest in agricultural streams, urban streams, and forest streams respectively. During the period of record drought and wet years, nitrate-N exports in Baltimore showed substantial variation in 6 suburban/urban streams (2.9-15.3 kg/ha/y), 1 agricultural stream (3.4-38.9 kg/ha/y), and 1 forest stream (0.03-0.2 kg/ ha/y). Interannual variability was similar for small Baltimore streams and nearby well-monitored tributaries and coincided with record hypoxia in Chesapeake Bay. Discharge-weighted mean annual nitrate concentrations showed a variable tendency to decrease/increase with changes in annual runoff, although total N export generally increased with annual runoff. N retention in small Baltimore watersheds during the 2002 drought was 85%, 99%, and 94% for suburban, forest, and agricultural watersheds, respectively, and declined to 35%, 91%, and 41% during the wet year of 2003. Our results suggest that urban land use change can increase the vulnerability of ecosystem nitrogen retention functions to climatic variability. Further work is necessary to characterize patterns of nitrate-N export and retention in small urbanizing watersheds under varying climatic conditions to improve future forecasting and watershed scale restoration efforts aimed at improving nitrate-N retention. ?? 2008 American Chemical Society.

Environmental Science & Technology↗

USGS1984

Inheritance patterns of enzymes and serum proteins of mallard-black duck hybrids

From 1974 to 1976, a breeding program was used to produce hybrids of black ducks and mallards for the evaluation of inheritance patterns of serum proteins and serum, liver and muscle enzymes. In addition to the crosses designed to produce hybrids, a series of matings in 1975 and 1976 were designed to evaluate inheritance patterns of a hybrid with either a black duck or mallard. At the F1 level, hybrids were easily distinguished using serum proteins. However, once a hybrid was crossed back to either a mallard or black duck, only 12?23% of the progeny were distinguishable from black ducks or mallards using serum proteins and 23?39% using esterases. Muscle, serum and liver enzymes were similar between the two species.

Biochemical Systematics and Ecology↗

USGS1978

Biochemical identification of mallard-black duck hybrids through a breeding program and in nature

From 1974 to 1976, a breeding program was used to produce black duck-mallard hybrids for the evaluation of inheritance patterns of serum proteins and esterases. In addition to the initial crosses, a series of matings in 1975 and 1976 were designed to evaluate inheritance patterns in hybrid matings with either black duck or mallards. At the F1 level, hybrids were easily distinguished. However, mallard or black duck crosses with hybrids were detectable as hybrids in only 11.5 - 22.6% of the progeny using serum proteins, and 22.6 - 38.8% using serum esterases. Concurrent with the breeding program, a field survey indicated hybrid frequencies ranging from 4% to 28%.

Transactions of the Northeast Section of the Wildl↗

USGS1977

Serum proteins of Canada goose (Branta canadensis) subspecies

Serum proteins from nine subspecies of Canada Geese (Brunta canadensis) were analyzed through the use of column and slab acrylamide electrophoresis. Variation was minimal within a subspecies, although all the subspecies were closely related. B. c. leucopareia appeared to be the most distinct subspecies, while maxima and moffitti were the most similar. Our preliminary findings suggest that the electrophoresis techniques are sensitive enough to identify some of the subspecies; however, baseline data from breeding ranges of all subspecies are required.

Condor↗

USGS1976

Biochemical identification of the mallard, Anas platyrhynchos , and black duck, A. rubripes

1. Eleven tissue systems from mallards and black ducks were examined for soluble proteins, lactate dehydrogenases and non-specific esterases through discontinuous polyacrylamide techniques. 2. Biochemical relationships between the black duck and mallard are extremely similar. 3. Hemoglobins and lactate dehydrogenase appear to be common in electrophoretic mobility between the two species. 4. Approximately 89% of the soluble proteins and 58% of the non-specific esterases are common among the two species, indicating both biochemical similarity at the genus level and species-specificity.

Comparative Biochemistry and Physiology, Part B: C↗

USGS1974

Electrophoresis as a management tool

The theme of this 1974 Northeast Fish and Wildlife Conference is 'A New Era'. Indeed, it is a new era for improved techniques to assist in management of our fish and wildlife resources for the maximum benefit of all. In some cases, the new techniques are primarily used in research.on fish and wildlife, and the results from the research are used to aid management and enforcement agencies in the decision-making process. One of the newer techniques that is being applied to problems in fisheries and wildlife is electrophoresis. In this paper, we review briefly the techniques of electrophoresis and illustrate research problems in wildlife and fisheries where the use of electrophoresis is now assisting or may potentially aid in management decisions.

Transactions of the Northeast Fish and Wildlife Co↗