Micro-photoautotroph predation as a driver for trophic niche specialization in 12 syntopic Indo-Pacific parrotfish species.

This article investigates the dietary composition and trophic resource partitioning of 12 syntopic Scarinine parrotfish species on mid-shelf reefs around Lizard Island, Great Barrier Reef, Australia. Using a combination of in situ bite core sampling, microscopic analysis, and 16S and 18S rRNA metabarcoding, the study identifies filamentous cyanobacteria—particularly genera such as Calothrix and Lyngbya morphotypes—as dominant and consistent micro-photoautotrophic components of parrotfish feeding substrata, alongside crustose coralline algae and other microalgae. The findings reveal interspecific differences in the taxonomic composition of these microbial assemblages and associated calcareous substrata, supporting the hypothesis that these parrotfish species partition trophic resources rather than acting as generalist turf feeders. This research enhances understanding of parrotfish roles in coral reef bioerosion and carbonate cycling by clarifying their nutritional targets at fine spatial and taxonomic scales.