“…Dinoflagellates of the genus Alexandrium are reported from many geographical areas in the world's oceans (Anderson et al ., ) and are known to release bioactive compounds, potent toxins (Anderson et al ., ) and allelochemicals that are poorly chemically characterized (Ma et al ., ), which can interact with microbial food web dynamics (Weissbach et al ., ). Alexandrium populations display a large intraspecific phenotypic diversity, in terms of growth rate (Suikkanen et al ., ; Brandenburg et al ., ), toxin production (Tillmann et al ., ; Suikkanen et al ., ; Martens et al ., ; Brandenburg et al ., ), allelochemical activity (Hakanen et al ., ; Brandenburg et al ., ), nutritional strategies (Glibert and Legrand, ) and ability to bioluminesce (Valiadi et al ., ). Due to this large phenotypic diversity Alexandrium is an ideal model organism for investigating the consistency of microbiomes over host specific, intraspecific or environmental variations (Tahvanainen et al ., ; Suikkanen et al ., ; Hakanen et al ., ).…”