Environmental Science & Technology
Permanent URI for this communityhttp://hdl.handle.net/1903/2216
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Item Pueraria lobata Willd. (Ohwi) kudxa: Limitations to Sexual Reproduction(1983) Abramovitz, Janet Naomi; Teramura, Alan H.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)The success of kudzu, Pueraria lobata Willd. (Ohwi), as a weedy invader in the southeastern United States is a result of its rapid growth rate, high leaf area index and ability to reproduce vegetatively. Populations at three sites near College Park, Maryland varied in their growth and reproduction, leaf area index, specific leaf weight, vine elongation rates, raceme density and seed production and dispersal. Soil characteristics, air temperature, humidity and photosynthetically active radiation (PAR) were measured at each site. The site which had the greatest vegetative productivity received significantly higher levels of PAR. Virtually no flowers or seeds were produced at the other two sites. At the site which produced a large number of flowers, successful sexual reproduction was limited by insufficient pollinator service during some periods of the season and low germination and seedling survivorship. Measurements of specific leaf weight, leaf area index, biomass, raceme production and seed set suggest that kudzu is a sun adapted plant. Even though it is capable of establishing itself in habitats of low or moderate irradiance, a greater ability for sexual reproduction was apparent in sun populations versus no sexual reproduction was apparent in sun populations versus no sexual reproductive success in populations occurring in shaded habitats. While its primary mode of reproduction is vegetative, successful sexual reproduction may occur despite several limiting factors.Item Preliminary Stock Assessment of The Chesapeake Bay Blue Crab Population(1989) Knotts, Karen Sue; Rothschild, Brian J.; Environmental Science & Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)A preliminary stock assessment using data from a commercial fishery survey was completed. The maximum average attainable size (Linf) was found to be 174.25 mm (6.9 in) for males, and 171.7 mm (6.8 in) for females. The von Bertalanffy growth coefficient (K) was determined to be 0.83 for males and 0.57 for females. Yield-per-recruit analysis indicated that a significant amount of yield-per-recruit is lost if males are fished before reaching approximately 145 mm (5.7 inches). Results for females show that the size at first capture should be approximately 124 mm (5 inches), after which the yield-per-recruit gained by waiting is minimal. The nature of the recruitment-stock relationship could not be characterized in this study; however, results indicate that a relationship does exist. A comparison of early and late season catch curves indicated surplus production of biomass in the 1987 pot fishery. The potential use of change in sex ratios estimators for stock assessment is discussed.