Biology ETDs

Publication Date

Summer 7-12-2017

Abstract

Knowledge of early life history strategies and ecological dynamics of larval fish growth and development is invaluable for effectively managing and conserving common and endangered fish species. Isotopic analysis of otoliths (bony structures of the inner ear) from larval Flannelmouth Suckers Catostomus latipinnis obtained from the Colorado River in Grand Canyon could greatly facilitate understanding of thermally-regulated growth rates, thermal preferences, and ontogenetic habitat use by these fishes. Colorado River water temperatures in the Grand Canyon are highly modified from projected historic water temperatures present before closure Glen Canyon Dam. Cold water as result of Glen Canyon dam and hypolimnetic releases from Lake Powell are predicted to slow growth and development of ectothermic fish larvae unless young fish can occupy warmer aquatic microhabitats (i.e., channel margins or shallow backwaters) within the river. Isotope ratio mass spectrometry (IRMS) is a technique that reveals integral aspects of an individuals’ life history that are often difficult to infer with traditional sampling methods. I developed and evaluated IRMS of oxygen isotopes (δ18O) of larval fish otoliths as a means to reconstruct water temperatures experienced by fish during early developmental phases. Stable isotope analysis of larval fish otoliths allowed for confident determination of relative water temperatures experienced by individual larvae and the potential for larvae to influence the temperatures they experience through active transport. Water temperatures experienced by larval C. latipinnis closely mirrored the seasonal temperature variation and on average were slightly warmer ≅ 2°C than the temperatures present in the mainstem river. Ultimately, this technique, while not completely tested, may provide a better understanding of potential limiting factors for other catostomids. Further, this research has identified potential impacts to the interpretation of growth rates of wild caught catostomid larvae spawned in cold-water temperatures. This unforeseen result may indicate an adaptive response to colder temperature by changes in resource provisioning to eggs and changes in early developmental ontogeny.

Keywords

otolith, stable isotope, sucker, aging, oxygen, temperature

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Thomas F. Turner

Second Committee Member

Seth D. Newsome

Third Committee Member

Nicu-Viorel Atudorei

Fourth Committee Member

Mark C. McKinstry

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