Université du Québec à Montréal
M.Sc. candidate
Supervisor: Alison Derry
Andrew Hendry
Start: 2025-05-01

Project

RECONSTRUCTING THE IMPACT OF NATIVE PREDATOR INTRODUCTION IN THREESPINE STICKLEBACK POPULATIONS OF EASTERN QUEBEC
In nearly four decades, populations of the threespine stickleback (Gasterosteus aculeatus) from isolated lakes in Parc-National du Lac-Témiscouata (PNLT) transformed drastically, from null to nearly complete pelvis expression. Between 1967 and 1991, provincial management programs stocked stickleback predator brook trout (Salvelinus fontinalis) and several stickleback competitor cyprinids into these lakes. The rapid morphological reversal of these phenotypically unique stickleback populations suggests that predation and competition re-emerged as potent selective forces, yet the chronology and ecological context of these changes remain undocumented. Through digital droplet real-time polymerase chain reaction (ddPCR) of sedimentary environmental DNA (sedDNA), this study seeks to reconstruct that history and evaluate how predator and competitor introductions affected threespine stickleback persistence and adaptation, tracing a century of ecological change to understand how human-mediated movements of native fishes influence freshwater biodiversity and the maintenance of distinct evolutionary lineages. Preliminary results will quantify layered species-specific DNA copy numbers, time-resolved with ²¹⁰Pb radioisotope dating of 18-30 cm sediment cores retrieved in three lakes of PNLT, allowing for (i) chronology of introductions; (ii) characterization of threespine stickleback population response, and; (iii) comparison of pre- and post-stockings ecosystem productivity via chlorophyll-a pigment concentration analysis. This study establishes itself as the first sedDNA historical reconstruction of fish introductions and their impacts in Québec, developing the molecular assay toolbox with the creation of species-specific ddPCR primer/probe pairs for threespine stickleback and several cyprinids.

Publications

1- Caddisfly larvae (Trichoptera: Limnephilidae) facilitate the uptake of microplastics by a freshwater fish (Ameiurus nebulosus)
Pfister, Hélène, Geneviève D'Avignon, Aimy Wang, Miguel Eduardo L. Felismino, Anthony Ricciardi
2025 Environmental Pollution