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Comparative feeding rates of native and invasive ascidians

TitleComparative feeding rates of native and invasive ascidians
Publication TypeJournal Article
Year of Publication2018
AuthorsHoxha T, Crookes S, Lejeusne C, Dick JTA, Chang X, Bouchemousse S, Cuthbert RN, MacIsaac HJ
JournalMarine Pollution Bulletin
Keywords2018, Ascidians, Functional response, Invasive species, Non-native species, Nonindigenous species, rcc, RCC1349, Relative impact

Ascidians have a recent history of species introductions globally, often with strong ecological impacts. Comparisons of per capita effects of invaders and comparable natives are useful to assess such impacts. Here, we explore ingestion rates (IR) and clearance rates (CR) of Ciona intestinalis and Ciona robusta, co-occurring native and non-native ascidians, respectively, from Brittany, France. IR was positively related to food concentration, with the invader responding more strongly to increasing food concentration. CR also differed by species, with the invader demonstrating higher values. C. robusta exhibited a higher functional response (Type I) than did C. intestinalis (Type II). Relative impact measured using seasonal abundance and IR revealed that C. robusta has a much greater impact than C. intestinalis at all food concentrations tested, though the former has a constrained distribution which limits its regional impact. Nevertheless, when abundant, we expect C. robusta to exert a greater impact on algal foods.