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Stoichiometry and the relative importance of autochthonous and allochthonous food sources for a dominant detritivorous fish

Pilati, Alberto
http://rave.ohiolink.edu/etdc/view?acc_num=miami1180713695

Abstract Details

2007, Doctor of Philosophy, Miami University, Zoology.
Many stoichiometric models assume that animals have ontogenetically constant body nutrient composition and excretion rates, but this assumption has not been adequately tested. I quantified ontogenetic variation in stoichiometry and diet in two fish, one with (gizzard shad) and one without (zebrafish) diet shift (Chapter 2). Both species showed considerable ontogenetic variation in body stoichiometry, driven by body P, which was associated with bone formation. Similar trends in both species suggest that ontogenetic variation in diet is not the main factor mediating fish body stoichiometry in larval and early juvenile stages. However, the N:P ratio of nutrient excretion also varied ontogenetically in gizzard shad, declining from larvae to juveniles, and this decline was apparently driven by changes in diet N:P rather than ontogenetic variation in fish body N:P. Diet instead, seemed to affect more growth and excretion rates. Adult gizzard shad feeds on lake sediments, which are composed by allochthonous and autochthonous detritus. Using experimental ponds, I manipulated the amount of phytodetritus (via dissolved nutrient addition) and allochthonous detritus (via sediment addition) and examined the response of two gizzard shad cohorts (Chapter 3). Shad spawned in all the ponds and young-of –the-year (YOY) recruitment appeared to be higher in conditions with elevated nutrients. Juvenile and adult shad grew better when sediments were added, probably because of their reliance on increased algal sedimentation through flocculation with clays. Yet, their biomass increased with the addition of either type of detritus as compared to the control. Mass specific N and P excretion rates by gizzard shad were higher in ponds with nutrients (phytodetritus) than in ponds with allochthonous detritus. This confirms the positive feedback to phytoplankton via nutrient translocation. To differentiate if gizzard shad is relying on allochthonous particulate organic matter (POM) or on the algae that flocculate with the sediments I labeled autochthonous and allochthonous detritus with stable isotopes and I offered them to the shad (Chapter 4). The use of a mixing model indicated that shad generally consumed algae, and not allochthonous POM. POM generally enters the food web via shad consumption because bacteria release nutrients which are later taken up by the algae, labeling algae with a terrestrial signal.
Michael Vanni (Advisor)
140 p.
gizzard shad; Dorosoma cepedianum; stoichiometry; ontogeny; autochthonous and allochthonous subsidies; stable isotopes

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Citations

  • Pilati, A. (2007). Stoichiometry and the relative importance of autochthonous and allochthonous food sources for a dominant detritivorous fish [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1180713695

    APA Style (7th edition)

  • Pilati, Alberto. Stoichiometry and the relative importance of autochthonous and allochthonous food sources for a dominant detritivorous fish. 2007. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1180713695.

    MLA Style (8th edition)

  • Pilati, Alberto. "Stoichiometry and the relative importance of autochthonous and allochthonous food sources for a dominant detritivorous fish." Doctoral dissertation, Miami University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1180713695

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.