Field-based oxygen isotope fractionation for the conservation of imperilled fishes: an application with the threatened silver shiner Notropis photogenis

Abstract

<jats:p>Identifying the realized thermal habitat of animals is important for understanding life history and population processes, yet methods to estimate realized thermal use are lacking for many small-bodied organisms, including imperilled fishes. Analysis of oxygen isotopes provides one solution, but requires the development of species-specific fractionation equations. To date, such equations have generally been limited to commercial or game fish species. Here, we developed a field-based fractionation equation for the threatened silver shiner <jats:italic>Notropis photogenis</jats:italic> to better understand the thermal ecology of the species in an urban watershed. Archived otoliths were analyzed for oxygen isotope values (δ<jats:sup>18</jats:sup>O). There was a significant linear relationship between otolith isotope fractionation and water temperature, described by δ<jats:sup>18</jats:sup>O<jats:sub>otolith(VPBD)</jats:sub> - δ<jats:sup>18</jats:sup>O<jats:sub>water(VPBD)</jats:sub> = 32.03 - 0.21(°C). Results indicate that otolith isotope techniques can be used to identify the average relative temperature occupied by silver shiner, representing the first investigation of oxygen isotopes to understand thermal occupancy of the species. This field-based equation provides an opportunity to understand how silver shiner may respond to alterations in stream temperatures resulting from urbanization and climate effects and may be useful in identifying thermal refugia for the species. Field-based, species-specific fractionation equations can provide insights into the thermal ecology of many small-bodied fishes, which are increasingly imperilled due to thermal stressors.</jats:p>

Silver shiner,Notropis photogenis, fecundity and parasite infections during the reproductive period

“…Silver shiner exists in only five drainages within Canada; Bronte Creek, Grand River, Thames River, Sixteen Mile Creek, and Saugeen River (Glass et al 2016;Burbank et al 2020Burbank et al , 2021bGáspárdy et al 2021), but is found throughout the Ohio and Tennessee river drainages in the east-central and southeastern United States. Due to its limited distribution in Canada, caution is warranted about the use of vital rate data from surrogate species.…”

Limited evidence for species‐specific sensitivity of temperature‐dependent fractionation of oxygen stable isotope in biominerals: A meta‐analysis

“…The regression coefficients of Equation were estimated for the Patterson (1998) study, as raw data were published in the article in which only Equation was reported. Additionally, fractionation equations for four studies (Burbank et al, 2020; Kastelle et al, 2022; Storm‐Suke et al, 2007; Willmes et al, 2019) were corrected from the published version, linked to a divergent calculation of Equation . Those studies based their estimation of both carbonate and water δ 18 O values relative to the same standard material (Vienna Peedee Belemnite, VPDB), rather than using VSMOW for water samples as commonly conducted.…”

Use of stable isotopes for assessing urbanization impacts on freshwater fishes

“…For example, when attempting to reconstruct realized temperature use with previously developed otolith thermometry equations, quantification of δ 18 O in the water where fish were captured is required to calculate otolith isotope fractionation (Godiksen et al, 2010). Additionally, the method is confined to situations where archived otoliths are available or lethal sampling is permitted (Burbank et al, 2020). Nevertheless, otolith thermometry can be applied to a wide range of fishes to understand realized or relative temperature use within and among species in the face of continuing urbanization.…”