The introduction ofSargassum muticummodifies epifaunal patterns in a Moroccan seagrass meadow

Marine macrophytes sustain valuable epiphytic biodiversity. Nonindigenous macroalgae may induce changes in composition and structure of epifaunal assemblages and therefore support different assemblages from those associated with native species. In this study, differences in faunal community structure between the introduced fucoidSargassum muticumand the native seagrassCymodocea nodosawere tested over a year on an intertidal shallow sandy bottom at the southern introduction front, the El Jadida coastline (NW Morocco). Epifaunal community structure consistently differed between macrophytes through seasons, with more species‐rich assemblages associated withS. muticumthanC. nodosadespite comparable abundances. The significantly greater epifauna diversity onS. muticummay be related to its structural complexity. However, the species contributing most to differences in assemblages between both macrophytes, such asSteromphala umbilicalisandS. pennanti, were found on both habitats with temporally varying abundances. Some species‐specific affinities were detected (Stenosomacf.acuminatum, Elasmopus vachoni, Chauvetia brunnea). Nitrogen, dissolved oxygen, suspended matter and temperature were identified as the best explanatory variables contributing to the observed macroepifaunal patterns. This study provides evidence thatS. muticumacts as a favourable and additional habitat for epifaunal species and supports a more diverse epifaunal assemblage in this Moroccan seagrass meadow.