A new international study shows yellow damselfish on the Great Barrier Reef prefer starting-out life on brightly coloured corals, emphasising how important colourful fine branching corals are to fish ...

Blue damselfish may appear to be thriving along Okinawa’s urbanized coastlines, but their genes reveal signs of environmental stress that could offer an early warning of trouble for coral reefs.

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3” Dusky Damselfish (Stegastes adustus) caught in San Juan, PR

Blue damselfish remain abundant along Okinawa’s urbanized coasts, but gene activity reveals physiological stress that conventional environmental monitoring may miss.

Blue damselfish, with their striking blue hue, are easy to spot, even along Okinawa's heavily urbanized coastlines. But while abundant, their gene activity reveals a hidden cost to living in human-impacted environments.

Blue damselfish, with their striking blue hue, are easy to spot, even along Okinawa's heavily urbanized coastlines.

To determine whether coastal habitats influence gene expression, we characterised the transcriptomic profiles of juvenile whole-body and adult liver samples of C. cyanea across 18 sites. The distribution of this blue damselfish species across varied environmental conditions on the subtropical island of Okinawa, Japan, allowed us to span a gradient from relatively pristine northern reefs to heavily urbanised southern coastlines (Fig. 1a,b). We first checked that transcriptomic profiles were not confounded by genomic variation; variant calling using the juvenile whole-body transcriptomes retrieved no significant population structure across Okinawa (Supplementary Fig. 1). Dimensional reduction with Principal Component Analysis (PCA) highlighted that, although transcriptomic profiles were modulated by fish size or sex (Supplementary Fig. 2), samples from the same sites clustered closely (significant effect of site on PC1/2, PERMANOVA, F(17, 72) = 13.51, R2 = 0.76, p = 0.001, for juvenile whole-body; F(17, 71) = 8.57, R2 = 0.67, p = 0.001, for adult livers). This suggested a coherent and site-associated transcriptomic signal rich in information (Fig. 1c,d). Local environmental conditions exerted a consistent influence on molecular phenotypes across life stages: the number of differentially expressed genes in juveniles and adults for the same site pairs was correlated (Fig. 1e). Juveniles exhibited...

New research has revealed a surprising ally in coral recovery: damselfish. Scientists found that wounded corals living alongside yellowtail damselfish healed faster, with recovery rates increasing by up to 55%. Researchers are still investigating exactly how the fish help; possibilities include supplying nutrients, improving water flow and cleaning wounds. The findings highlight how protecting coral-dwelling […]