Bioenergetics model for the nonnative Redside Shiner

Abstract

Objective Redside Shiner Richardsonius balteatus has expanded from its native range in the Pacific Northwest region of North America to establish populations in six other western states. This expansion has fueled concerns regarding competition between Redside Shiner and native species, including salmonids. We developed a bioenergetic model for Redside Shiner, providing a powerful tool to quantify its trophic role in invaded ecosystems and evaluate potential impacts on native species. Methods Mass‐ and temperature‐dependent functions for consumption and respiration were fit based on controlled laboratory experiments of maximum consumption rates and routine metabolic rates using intermittent‐flow respirometry, across a range of fish sizes (0.6–27.3 g) and temperatures (5–31°C). Laboratory growth experiments were conducted to corroborate model performance across different temperatures and feeding rates. Result Initial bioenergetic simulations of long‐term growth experiments indicated large model error for predicted consumption and growth, and deviations from observed responses varied systematically as a function of daily consumption rate (J·g−1·d−1) and water temperature. A growth rate error correction function was developed and included in the bioenergetics model framework on a daily time step, resulting in decreased absolute model error in all experimental groups. Predicted values from the corrected model were highly correlated with observed values (R2; consumption = 0.97, final weight = 0.99) and unbiased. These results show that the optimal temperature for Redside Shiner growth (18°C) exceeds that of Pacific salmon Oncorhynchus spp. by 2–6°C under a scenario of high food availability and moderate food quality. Conclusion Consequently, increases in water temperature associated with climate change may favor growth and expansion of Redside Shiner populations, while negatively affecting some salmonids. The bioenergetics model presented here provides the necessary first step in quantifying trophic impacts in sensitive ecosystems where Redside Shiner have invaded or in ecosystems where anadromous salmonid reintroductions are being considered.

Realized thermal niche approach eliminates temperature bias in bioenergetic model estimates

“…Bias in bioenergetics model results is a well‐known issue (see Chipps & Wahl, 2008 ; Ney, 1993 ) and the assumption of thermal habitat selection near the optimum has been debated since the early onset of those models (e.g., Bevelheimer, 1990 ; Spigarelli et al., 1982 ). Lab studies comparing growth and consumption rates at various holding temperatures have shown wide variation in results (e.g., Canale, 2014 ; Johnson et al., 2023 ). Comparisons quantifying bias of lab‐obtained thermal versus field‐observed preference of wild populations are rare and indirect (e.g., Brodie et al., 2016 ) and to our knowledge, none exist that include multiple age classes across all seasons.…”