Non-indigenous species (NIS) have the potential to colonize and become established in a wide range of coastal habitats. Species with broad environmental tolerances can quickly adapt to local conditions and expand their niches along environmental gradients, and even colonize habitats with extreme abiotic conditions. Here we report and document the distribution of eight marine NIS (four seaweed and four invertebrate species) found in tidepools along a 3000 km latitudinal gradient along the Pacific coast of Chile (18.4 degrees S to 41.9 degrees S). The seaweed NIS Codium fragile, Capreolia implexa, Schottera nicaeensis and Mastocarpus latissimus were mostly distributed towards high latitudes (i.e., more southerly locations), where temperatures in tidepools were low. The invertebrate NIS Anemonia alicemartinae, Ciona robusta, Bugula neritina and Bugulina flabellata were more common towards low latitudes, where high temperatures were registered in the tidepools. Across the intertidal gradient, seaweed NIS were mostly found in pools in the mid and low intertidal zone, while invertebrate NIS occurred mostly in pools from the mid and upper intertidal zones. The realized niche spaces of NIS (based on the Outlying Mean Index, OMI) in the study area were mainly influenced by environmental conditions of temperature and salinity (along the latitudinal and intertidal gradients), while other tidepool characteristics (depth, surface area, exposition, and complexity) only had minor effects. Five of the eight NIS exhibited a realized niche space coinciding with the average tidepool environmental conditions, while marginal niches were occupied by species with affinities for specific temperatures and salinities along the latitudinal and intertidal gradients. Our results indicate that physiological tolerances to environmental factors play a fundamental role in the distribution of seaweed and invertebrate NIS in tidepools along the Chilean coast. This study confirms that tidepools offer suitable conditions for some seaweed and invertebrate NIS, potentially facilitating their invasion into new natural habitats. C1 [Jofre-Madariaga, David; Arias, Rene Matias; Kappes, Martin Munizaga; Arancibia, Leslie Nicole Ortiz; Pino, Oscar; Rech, Sabine; Thiel, Martin] Univ Catolica Norte, Fac Ciencias Mar, Dept Biol Marina, Larrondo 1281, Coquimbo, Chile. [Jofre-Madariaga, David] Univ Antofagasta, Fac Ciencias Mar & Recursos Biol, Doctorado Ciencias Aplicadas Menci Sistemas Marin, Antofagasta, Chile. [Moya, Moises A. Aguilera] Univ Adolfo Ibanez, Fac Artes Liber, Dept Ciencias, Diagonal Torres 2640, Santiago, Chile. [Alves-de-Souza, Catharina] Univ Concepcion, Fac Ciencias Nat & Oceanog, Dept Oceanog, Concepcion 4030000, Chile. [Alves-de-Souza, Catharina] Univ Concepcion, Ctr Invest Oceanog COPAS Coastal, Concepcion, Chile. [Gutow, Lars] Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Handelshafen 12, D-27570 Bremerhaven, Germany. [Polanco, Ricardo Antonio Jeldres; Macaya, Erasmo C.] Univ Concepcion, Lab Estudios Algales ALGALAB, Dept Oceanog, Fac Ciencias Nat & Oceanog, Casilla 160-C, Concepcion, Chile. [Polanco, Ricardo Antonio Jeldres; Macaya, Erasmo C.] Ctr FONDAP Invest Dinam Ecosistemas Marinos Altas, Valdivia, Chile. [Rech, Sabine; Thiel, Martin] Ctr Ecol & Sustainable Management Ocean Isl ESMOI, Coquimbo, Chile. [Rothausler, Eva] Univ Atacama, Ctr Invest Costeras CIC UDA, Copiapo, Chile. [Harrod, Chris] Univ Antofagasta, Inst Antofagasta, Univ Antofagasta Stable Isotope Facil, Antofagasta, Chile. [Harrod, Chris] Univ Antofagasta, Fac Ciencias Mar & Recursos Biol, Inst Ciencias Nat Alexander Von Humboldt, Antofagasta, Chile. [Harrod, Chris] Nucleo Milenio INVASAL, Concepcion, Chile. [Thiel, Martin] Smithsonian Environm Res Ctr, MarineGEO Program, Edgewater, MD USA. C3 Universidad Catolica del Norte; Universidad de Antofagasta; Universidad Adolfo Ibanez; Universidad de Concepcion; Universidad de Concepcion; Helmholtz Association; Alfred Wegener Institute, Helmholtz Centre for Polar & Marine Research; Universidad de Concepcion; Universidad de Atacama; Universidad de Antofagasta; Universidad de Antofagasta; Smithsonian Institution; Smithsonian Environmental Research Center