Ecosystems in transition: How life at the interface of two food webs shapes the diet fishes in the freshwater tidal zone

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University of New Brunswick


Freshwater tidal zones exist at the interface of marine and freshwater food-webs and stimulate diverse foraging strategies. This thesis characterizes the trophic ecology of fishes using the freshwater tidal zone of the Northwest Miramichi River (New Brunswick, Canada). I used estimations of resource use, dietary niche width, and trophic position to classify fishes as tidal generalist, marine specialist, or freshwater specialist and determine whether their resource use impacts both niche width and trophic position. I asked whether fishes exhibited differences in consumer diet across species, among individuals, and within the same individual over time. Using stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) I found that resource use, niche width, trophic position, and individual specialization vary across species. Resource use did not impact niche width or influence trophic omnivory. Fish total length, resource use, and isotopic niche width did not impact individual specialization.



NATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Freshwater ecology