Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Feb. 7, 2007). PDF text: xvi, 181 p. : ill. (some col.). UMI publication number: AAT 3220389. Includes bibliographical references. Also available in microfilm and microfiche format.

Thesis (Ph.D.)--University of Rhode Island, 2009. / Includes bibliographical references (leaves 270-288).

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.E.)--University of Texas at Austin, 2003. / "May 2003." Published reprint of thesis. Includes bibliographical references (leaves 77-78). Available also electronically on the Internet.

No description available.

In situ light and dark planktonic and benthal respirometers were used to measure the oxygen requirements of Yaquina estuary water and benthal deposits. Respirometer devices were constructed so that actual conditions of mixing could be simulated and benthal deposit disturbance would be minimized. A mathematical model of a benthal respirometer was developed and was used to make corrections for respirometer leakage and to conduct oxygen transfer parameter sensitivity studies. The effect of mixing on benthal oxygen uptake was studied by varying the simulated mixing velocities. Studies were made to determine the effects of scour of bottom material on the salinity of the respirometer water and on the benthal oxygen uptake rates. Plots of various parameters such as benthal oxygen uptake versus dissolved oxygen concentration and respirometer leakage versus time were made to attempt to evaluate relationships that may exist. / Graduation date: 1970

Many of the processes on earth which are essential for sustaining life are driven by biological systems and it is functional diversity aswell as species richness which determines the health and sustainability of ecosystems. Ecosystem functions, from primary production to decomposition, are determined by the interactions both between organisms and between organisms and their environment. As such, there has long been an appeal in classifying species by their roles in ecological communities rather than by taxonomic groupings. However, there is often a disconnect between the criteria used to classify species into functional groups, often common morphological attributes, and the effect that the organisms within those groups have on specific ecosystem functions as the appropriateness of the classification criteria is rarely empirically tested. This thesis investigates inter- and intra-species variation in benthic invertebrates with respect to their effects on ecosystem processes (particle reworking and bioirrigation) and functions (nutrient cycling) and considers whether species can be grouped for single and multiple ecosystem functions in different environmental contexts. Overall the results show that species can be grouped by their effects on specific single ecosystem functions, but that these groups cannot be applied across multiple functions and processes. Further they show that species’ contributions to ecosystem functions change with environmental context (salinity, organic enrichment, seawater acidification and temperature), and that changes in the ecosystem processes known to mediate functions do not necessarily reflect a change in functioning. In addition intra-species variation in functional activity indicates that it may not be appropriate for all members of a population to be ascribed to the same functional group. This thesis highlights a need to test that different functional groups reflect different effects on ecosystem functioning. Further it shows that functional groups are not constant, individuals within populations are not necessarily functional equivalents, and that individuals have the capacity to change their contributions to ecosystem functions and processes. Future research needs to acknowledge and incorporate both biotic and abiotic sources of variability in species effects on ecosystem functions and processes.

Thesis (Ph. D.)--University of California, Santa Cruz, 1982. / Typescript. Includes bibliographical references (leaves 181-193).

Tésis (Biólogo)--Universidad Autónoma de Guadalajara, 1979. / Summary in English. Includes bibliographical references (leaves 69-71).

Climate change is rapidly reducing the Arctic Ocean summer sea ice cover, consequently altering the patterns of primary production, with reducing ice algal-, but increasing phytoplankton primary production. As benthic consumers rely on the sinking phytodetritus for food, changes to food availability could render the benthos vulnerable if they prefer ice algae as a food source. The aim this thesis was to investigate the benthic macroinfaunal dietary reliance on ice algae and phytoplankton in North Water Polynya (NOW) and Lancaster Sound (LS) in Canadian Arctic Archipelago, and how a shift from one food source to another impacts the benthic community resource utilisation and nutrient cycling processes. I hypothesised that ice algae would be preferentially consumed and respired by the benthos. Natural abundance stable isotope analysis showed that phytoplankton is the main food source for macroinfauna in NOW and LS. 13C-15N isotope tracer experiments showed that while in NOW the accumulative macroinfaunal uptake of ice algal C was higher than uptake of ice algae, in LS more ice algal C and N was consumed. None of the major taxonomic groups exclusively preferred ice algae. No difference in bacterial uptake of the two algal types was observed at either site, but the respiration of phytoplankton C was significantly higher than respiration of ice algal C. The processing rates of phytoplankton-derived C were 39–46% higher than processing rates of ice algal C. Therefore, the hypothesis of ice algal preference by benthos must be rejected. I conclude that benthic macroinfauna exhibit great dietary flexibility, making them resilient against climate mediated changes in food sources, and that increasing availability of phytoplankton food can benefit the benthos in the future. Additionally, the transition from ice algae to phytoplankton dominated food can significantly enhance benthic organic matter processing, and especially respiration, rates in the future.