Evaluating the relationship of temperature and growth of larval Colorado River catostomids through otolith aging and stable isotopes (?18O)

Authors: Adam L. Barkalow, Tom F. Turner, Nicu-Viorel Atudorei, Seth D. Newsome, Mark C. Mckinstry, Steve P. Platania

Year: 2016 (xlviii)

Abstract

It is well understood, through laboratory experiments, that growth rates of larval catostomids are related to environmental temperature. However, assessing the relationship between growth and temperature of riverine larvae is confounded by larval movement (e.g., via drift and diel movements) and because larvae can use thermally heterogeneous mesohabitats. Isotopic analysis of otoliths from larval Colorado River catastomids could facilitate better understanding of thermal ecology of wild caught la rvae. Isotope ratio mass spectrometry (IRMS) is a technique that reveals integral aspects of an individuals’ life history that are often difficult or impossible to assess with traditional sampling methods. Analysis of oxygen isotope ratio (?18O ) of an otolith is a validated method for evaluating the environmental temperature experienced by a fish. Here we present a method of obtaining the oxygen isotope ratio of individual larval otoliths and compare ?18O results with daily growth rates of the same fish. For our preliminary analysis we used specimens of two Colorado River catostomids, Flannelmouth Sucker Catostomus latipinnis and Bluehead Sucker Pantosteus discobolus collected within 160 river kilometers of the lower Grand Canyon in 2015.