Memorial University DAI: Bi-dimensional feeding ecologies and food web structure : a conceptual framework linking trophic and spatial processes in aquatic ecosystems, with application to mercury bioaccumulation in fish

advanced search

Digital Archives Initiative
Memorial University - Electronic Theses and Dissertations 4

menu off

add document to favorites : add page to favorites : reference url

back to results : previous : next

Search this object:

0 hit(s) :: previous hit : next hit

View:

previous page : next page

Document Description

Title	Bi-dimensional feeding ecologies and food web structure : a conceptual framework linking trophic and spatial processes in aquatic ecosystems, with application to mercury bioaccumulation in fish
Author	Roux, Marie-Julie.
Description	Thesis (Ph.D.)--Memorial University of Newfoundland, 2009. Earth Sciences
Date	2009
Pagination	xviii, 211 leaves : col. ill., maps
Subject	Fishes--Food--Newfoundland and Labrador--Labrador; Fishes--Mercury content--Newfoundland and Labrador--Labrador; Mercury cycle (Biogeochemistry)--Newfoundland and Labrador--Labrador; Mercury--Bioaccumulation--Newfoundland and Labrador--Labrador;
Degree	Ph.D.
Degree Grantor	Memorial University of Newfoundland. Dept. of Earth Sciences
Discipline	Earth Sciences
Language	Eng
Spatial Coverage	Canada--Newfoundland and Labrador--Labrador
Notes	Includes bibliographical references
Abstract	This thesis presents the results of a study of the ecology of fish communities of lakes and reservoirs in Labrador, Canada. The first objective of the thesis was to evaluate the relevance and implications of a bi-dimensional framework to integrate spatially-explicit energy flows in consumer feeding ecology and food web structure. Second objective was to assess whether spatially-explicit bi-dimensional feeding ecologies and food web structures can improve the assessment of mercury (Hg) bioaccumulation in fish. A bi- dimensional framework consists in the integration of horizontal (spatially-explicit) and vertical (trophic) energy flows. This approach is demonstrated in comparative studies of fish populations and communities from four pristine lakes. Horizontal energy flows here distinguished between littoral and pelagic carbon contributions to fish consumers in lakes, quantified by variations in stable isotope ratios of carbon in fish tissue. Vertical energy flows described variations in fish trophic position quantified by variations in stable isotope ratios of nitrogen. Comparing life-stage and among-lake patterns of trophic position and littoral-pelagic resource use in four fish species demonstrated that bi-dimensional feeding strategies are determined by species ontogeny and ecosystem characteristics. Comparisons of lake-specific bi-dimensional food web structures estimated from community averages of fish trophic position and littoral-pelagic foraging demonstrated that spatially-explicit community organization is related to consumer species composition, to primary productivity constraints and to physical ecosystem structure. Applied to the understanding of Hg bioaccumulation, a bi-dimensional framework integrated spatial influences on Hg exposure and trophic transfers in aquatic ecosystems and improved predictions of fish Hg concentrations. Horizontal energy flows in this case further distinguished between allochthonous-autochthonous carbon contributions to primary producer-consumer. A bi-dimensional approach revealed that aquatic ecosystems with longer food chains, greater assimilation of autochthonous carbon at lower trophic levels and greater reliance on littoral carbon by fish, reach greater Hg contamination. The influence of littoral-pelagic resource use on fish Hg levels varied with the type and size of prey consumed across habitat boundaries. Autecological types distinguish consumers bi-dimensional feeding ecologies as shaped mainly by ontogeny (Quis type), by ecosystem features (Ubi type) or both (Aequivocus type). This classification provided species-specific distinctions for the importance of biological and environmental determinants of Hg bioaccumulation in fish. A bi-dimensional framework provides a solid conceptual basis for spatially-explicit cological understanding that can improve the assessment of environmental issues.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	a3241910
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(25.07 MB) -- http://collections.mun.ca/PDFs/theses/Roux_Marie-Julie.pdf
CONTENTdm file name	27972.cpd