Mediterranean Sea ecosystems are considered as hotspots of biological introductions, exposed to possible negative effects of non-indigenous species. In such temperate ecosystems, macroalgae may be dominant, with presence of many introduced species.

This study used an experimental approach to assess the interaction between the introduced alga Asparagopsis taxiformis and the indigenous coral Astroides calycularis. The biological response measurements included meta-barcoding of the associated microbial communities and metabolomic fingerprinting of both species.

The results showed significant changes among both associated microbial communities, and with the interspecific differences decreasing with stronger host interaction. No short term effects of the macroalga on the coral health were detected, neither on its polyp activity or its metabolism. However, it is highlighted that the contact interaction with the coral induced a change in the macroalgal metabolomic fingerprint with a significant increase of its bioactivity against the marine bacteria Aliivibrio fischeri, which according to the authors, might represent an immediate defensive response of the macroalga or an allelopathic offense against coral.

Greff et al. (2019) The interaction between the proliferating macroalga Asparagopsis taxiformis and the coral Astroides calycularis induces changes in microbiome and metabolomic fingerprints. Scientific Reports 7:42625.