The shifting trophodynamics in four southern Nova Scotia lakes after the introduction of Chain Pickerel (Esox niger)

Abstract

<p><span>Invasive fish species Chain pickerel (<em>Esox niger</em>) was first reported within Kejimkujik National Park and Historical Site in 2018. I used stable carbon (&delta;¹³C) and nitrogen (&delta;¹⁵N) ratios to assess food web structure and trophodynamics in four four lakes ranging over an invasion spectrum: Loon Lake (first Chain Pickerel report in 2018), Grafton Lake (2019), Big Dam West Lake (2020) and Cobrielle Lake (2021). It was shown that <em>E. niger</em> can be grouped into two clusters based on their feeding habits, CP1 and CP2; 4.2cm &le; TL &le; 10.9cm and 20.2cm &le; TL &le; 58.6cm. Mixing model results indicate CP1 individuals feed primarily on Odonata with a mean dietary proportion of 0.736 &plusmn; 0.079. Those assigned to CP2 feed primarily on native fish with a mean dietary proportion of 0.724 &plusmn; 0.032. Post-invasion there was a consistent decrease in overall trophic position for fish and Odonata prey items.</span></p>