Abstract
(1) Many forage fishes, such as Leucisids (minnows) have depauperate studies on diet composition or stable isotope signatures, as these fishes are often only viewed as food for higher trophic levels. The need exists to understand and document the diet and stable isotope signatures of Leucisids (redside shiner, longnose dace, lake chub) in relation to the community ecology and food-web dynamics in Yellowstone Lake, especially given an invasive piscivore introduction and potential future effects of climate change on the Yellowstone Lake ecosystem. (2) Diet data collected during summer of 2020 were analyzed by species using proportion by number, frequency of occurrence, and mean proportion by weight, and diet overlap was compared using Schoener’s index (D). Stable isotope (δ15N and δ13C) values were estimated by collecting tissue during the summer of 2020 by species, and isotopic overlap was compared using 40% Bayesian ellipses. (3) Nonnative redside shiners and lake chub had similar diets, and native longnose dace diet differed from the nonnative Leucisids. Diet overlap was also higher between the nonnative Leucisids, and insignificant when comparing native and nonnative Leucisids. No evidence existed to suggest a difference in δ15N signatures among the species. Longnose dace had a mean δ13C signature of −15.65, indicating an decreased reliance on pelagic prey compared to nonnative Leucisids. Nonnative redside shiners and lake chub shared 95% of isotopic niche space, but stable isotope overlap was <25% for comparisons between native longnose dace and the nonnative Leucisids. (4) This study established the diet composition and stable isotope signatures of Leusicids residing in Yellowstone Lake, thus expanding our knowledge of Leucisid feeding patterns and ecology in relation to the native and nonnative species in the ecosystem. We also expand upon our knowledge of Leucisids in North America. Additionally, quantifying minnow diets can provide a baseline for understanding food web response to invasive suppression management actions.
Highlights
(4) This study established the diet composition and stable isotope signatures of Leusicids residing in Yellowstone Lake, expanding our knowledge of Leucisid feeding patterns and ecology in relation to the native and nonnative species in the ecosystem
Of the 44 redside shiners, 22 lake chub (TL; 33–129 mm), and 50 longnose dace (TL; 40–86 mm) diets, we identified 12 prey taxa, including Amphipoda, Ostracoda, Apatania, Trichoptera, Chironomidae Non-tanypodinae, Chironomidae Tanypodinae, Ephemerella, Baetidae, Copepoda, Daphnia, and Rotifera
Frequency of occurrence (Oi ), proportion by number (Ni ), and mean proportion by weight (MWi ) of diet items were similar for nonnative minnows, but not when comparing native and nonnative minnows (Table 1)
Summary
Fish diets can integrate many ecological characteristics of a species, including behavior, habitat use, energy intake, and interactions within populations or communities [1]. Research on fish diets can compare consequences of environmental change [2,3,4,5] or species introductions [6,7,8,9]. Descriptions of fish diet can clarify trophic interactions in aquatic food webs [6,7,14,15,16]. In addition to diet analysis, stable isotope analysis can be used to evaluate stages of ontogeny, habitat use [1], or compare trophic positioning of species
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