• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 325
  • 25
  • 22
  • 5
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 433
  • 433
  • 176
  • 176
  • 157
  • 151
  • 146
  • 112
  • 49
  • 42
  • 36
  • 33
  • 31
  • 30
  • 27
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

A systems approach to pelagic ecosystem dynamics in an estuarine environment

Iverson, Richard L. 22 December 1971 (has links)
Phytoplankton dynamics in Auke Bay, Alaska, were studied during summer, 1969. Nitrate, chlorophyll a, particulate organic carbon, phytoplankton and zooplankton species composition and hydrographic and meteorological data were collected and analyzed. Nitrate input into Auke Bay through freshwater runoff was negligible. A bloom of Thalassiosira aestivalis formed the spring bloom in Auke Bay in 1969. No phytoplankton bloom occurred during a June period when winds were light and variable. Two major blooms of Skeletonema costatum occurred after periods when Auke Bay surface layers were mixed by wind-induced turbulence. The water column became nearly isothermal after periods of high wind mixing although a pronounced density and halal structure persisted, a consequence of input of freshwater to the bay from Auke Creek. Examination of fecal pellets collected from the bay and results of laboratory grazing experiments suggested that Skeletonema costatum was not grazed by zooplankton living in Auke Bay. Nonlinear ordinary differential equations were written to describe phytoplankton and nitrate dynamics in Auke Bay. The phytoplankton dynamics equation included formulations for time-varying insolation and for time-varying wind mixing coefficients. Formulations for effects of nitrate concentration on the photosynthetic assimilation number and for effects of phytoplankton standing crop on the extinction coefficient of light in the water column were included. The nitrate dynamics equation included a formulation for effects of wind-mixing of nitrate-rich water into the euphotic zone from deeper layers of the water column, as well as a formulation for utilization of nitrate in phytoplankton growth. Computer simulation response of the equations reproduced the bloom pattern observed in the field data with some discrepancies caused by assumptions used in model development. The phytoplankton and nitrate model response was strongly coupled to the pattern of the wind-mixing coefficient, as required by the field data. Variations in model parameters had little effect on phase relations between model response and field data but strongly affected model response magnitude. / Graduation date: 1972

Plants, plant communities, net production and tide levels : the ecological biogeography of the Nehalem salt marshes, Tillamook County, Oregon /

Eilers, Hio Peter, III. January 1974 (has links)
Thesis (Ph. D.)--Oregon State University, 1975. / Typescript (photocopy). Includes bibliographical references. Also available online.

Investigations into the seasonal deep chlorophyll maximum in the western North Atlantic, and its possible significande to regional food chain relationships /

Ortner, Peter B. January 1977 (has links)
Thesis (Ph. D.)--Woods Hole Oceanographic Institution, 1977. / "October 1978." "Technical report." WHOI-78-59. "AD-A060 220." Includes bibliographical references (p. 201-220).

The ecology of the Manx strand line

Andrews, James Ward January 1991 (has links)
No description available.

Heavy-metal pollution and its effects on recent foraminiferids from Southampton Water, southern England, UK

Sharifi, Abdol Rahim January 1991 (has links)
No description available.

Studies on the development of fouling communities on experimental panels in Langstone Harbour

Schmidt, G. H. January 1983 (has links)
No description available.

The impact and management of visitor pressure on Rocky Shore communities

Fletcher, Helen January 1997 (has links)
No description available.

Ecological investigations of the British intertidal nephtyidae (Annelida : polychaeta)

Morgan, P. J. January 1984 (has links)
No description available.

Fishery ecology of the Pokai artificial reef / Pokai artificial reef

McVey, James Paul January 1970 (has links)
Typescript. / Includes bibliographies. / xvi, 267, [1] l illus., map, graphs, tables

Effects of habitat structure on tropical fish assemblages

Garpe, Kajsa January 2007 (has links)
<p>Rates of habitat alteration and degradation are increasing worldwide due to anthropogenic influence. On coral reefs, the loss of live coral reduces structural complexity while facilitating algal increase. In many coastal lagoons seagrass and corals are cleared to make room for cultivated macroalgae. This thesis deals with reef and lagoon habitat structure and how fish assemblage patterns may be related to physical and biological features of the habitat. It further examines assemblage change following habitat disturbance. Four studies on East African coral reefs concluded that both the abundance and species richness of recruit and adult coral reef fish were largely predicted by the presence of live coral cover and structural complexity (Papers I-III, VI). Typically, recruits were more selective than adults, as manifested by limited distributions to degraded sites. Paper VI compared short- and long-term responses of fish assemblages to the 1997-1998 bleaching event. The short-term response to coral mortality included the loss of coral dwelling species in favour of species which feed on algae or associated detrital resources. Counterintuitively, fish abundance and taxonomic richness increased significantly at one of two sites shortly after the bleaching. However, the initial increase was later reversed and six years after the death of the coral, only a limited number of fish remained. The influence of fleshy algae on fish assemblages was studied in algal farms (Paper IV), and examined experimentally (Paper V). The effects of algal farming in Zanzibar were significant. Meanwhile, manually clearing algal-dominated patch reefs in Belize from macroalgae resulted in short-term increases of abundance, biomass and activity of a few species, including major herbivores. The findings of this thesis demonstrate the significance of habitat as a structuring factor for tropical fish assemblages and predicts that coral death, subsequent erosion and algal overgrowth may have substantial deleterious impacts on fish assemblage composition, abundance and taxonomic richness, with recovery being slow and related to the recovery of the reef framework.</p>

Page generated in 0.0692 seconds