Hoxha T Crookes S Lejeusne C Dick JTA Chang X Bouchemousse S Cuthbert RN MacIsaac HJ 2018 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. application/pdf https://sonar.ch/global/documents/98875 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.marpolbul.2018.08.039 info:eu-repo/semantics/altIdentifier/pmid/30301002 info:eu-repo/semantics/openAccess Marine pollution bulletin. - 2018 Ascidians Functional response Invasive species Non-native species Nonindigenous species Relative impact Animals Ciona Ciona intestinalis Feeding Behavior France Introduced Species Species Specificity Comparative feeding rates of native and invasive ascidians. http://purl.org/coar/resource_type/c_6501