The significance of marine-derived biogenic nitrogen in anadromous Pacific salmon freshwater food webs

Thesis (Ph.D.) University of Alaska Fairbanks, 1991The natural abundance of the stable isotope ratios \sp{15}N/\sp{14}N and \sp{13}C/\sp{12}C expressed as \delta\sp{15}N and \delta\sp{13}C was used to trace biogenic nutrients delivered by returning adult anadromous Pacific salmon into freshwater systems. These systems were Sashin Creek, a rapidly flushing stream located on Baranof Island, southeastern Alaska and Iliamna Lake, the major sockeye salmon, Oncorhynchus nerka, nursery lake in the Kvichak River watershed, Bristol Bay, southwestern Alaska. Marine-derived nitrogen (MDN) was quantifiable by use of an isotope mixing model based on comparison of biota \delta\sp{15}N in areas used for spawning by anadromous salmon with salmon-free controls within the same watershed. Control periphyton (benthic primary producers) \delta\sp{15}N values $\sim$0 suggested that the control N pool was derived from N\sb2 fixation without significant recycling. In contrast, periphyton abundant in areas of intense spawning activity or carcass aggregation had \delta\sp{15}N $\sim$ +7. These two values were the basis for comparison of \delta\sp{15}N values of higher trophic level biota. A mixing model relating \delta\sp{15}N to MDN with trophic level was used to estimate consumer MDN through incorporation of a priori isotopic trophic enrichment factors established in the literature. Distinctive \delta\sp{13}C signatures along the Sashin Creek stream gradient and between Iliamna Lake littoral and limnetic production were used in concert with \delta\sp{15}N. Sashin Creek fishes reflected isotopic signatures of periphyton and thus production within the same stream section. Isotopic data suggested an overall importance of limnetic production in Iliamna Lake resident fish and juvenile sockeye salmon diets. Salmon eggs and emergent fry retaining the parental marine isotopic signature were distinguishable from autochthonous production derived from marine N, and appear to be a minor dietary component in both Sashin Creek or Iliamna Lake fishes. The proportion of MDN in resident fish N, including juvenile salmon after turnover of the natal N pool, was proportional to the escapement of spawners. Thus there is now direct evidence for a significant natural fertilization process: the flow of remineralized marine-derived biogenic nutrients from returning anadromous Pacific salmon into freshwater food webs

Nothing but the Law of the Land Robert C. Grier: jacksonian unionist

From 1846 to 1870 Robert Cooper Grier, a Pennsylvania Jacksonian Democrat, served as an Associate Justice of the United States Supreme Court and Third Circuit Court Justice. In judicial opinions and decisions and in personal and polictical correspondence, he expressed an unyielding commitment to the preservation of the Union

Programmable Automated Welding System (PAWS): Control of welding through software and hardware

The ATD phase of the PAWS program ended in November 1992 and the follow-on ManTech program was started in September 1993. The system will be industrially hardened during the first year of this program. Follow-on years will focus upon the transition into specific end-user sites. These implementations will also expand the system into other welding processes (e.g. FCAW, GTAW, PAW). In addition, the architecture is being developed for application to other non-welding robotic processes (e.g. inspection, surface finishing). Future development is anticipated to encompass hardening for extreme environments, expanded exception handling techniques, and application to a range of manipulators

Applying modern Omic technologies to the Neuronal Ceroid Lipofuscinoses

The Neuronal Ceroid Lipofuscinoses are a group of severe and progressive neurodegenerative disorders, which generally present during childhood. With new treatments emerging on the horizon, there is a growing need to understand the specific disease mechanisms as well as identify prospective biomarkers for use to stratify patients and monitor treatment. The use of Omics technologies to NCLs has the potential to address this need. We discuss the recent use and outcomes of Omics to various forms of NCL including identification of interactomes, affected biological pathways and potential biomarker candidates. We also identify common pathways affected in NCL across the reviewed studies

A Preliminary List of the Flora of the Perkiomen Region

41 page annotated list of vascular plants collected by the authors in and around the Perkiomen Creek in Montgomery County, Pennsylvania. About the year 1915 Dr. Kline, Brendle and Mumbauer began to make weekly collecting trips. This preliminary catalogue rests mostly upon the work done on these trips. [from the Foreword]https://digitalcommons.ursinus.edu/faculty_books/1011/thumbnail.jp