Elevated sea surface temperatures between February and April 2016 resulted in the most extensive and severe thermal bleaching event on record on the Great Barrier Reef (GBR), with the majority of northern reefs experiencing extreme bleaching (>60% of corals bleached) (Hughes et al. 2017). Most research has documented the effects of the bleaching on reef building corals, yet there are less-studied microhabitats that bleach, such as sea anemones that provide essential habitat for one of the reefs most iconic fishes, the anemonefishes (Hobbs et al. 2013; Hill and Scott 2012). We tracked the fate of tagged sea anemones and associated anemonefishes within the Lizard Island lagoon (14°40′S, 145°27′E, 1–5 m depth) for 6 months following the thermal anomaly.
Between 10 and 15 April, all Entacmaea quadricolor (n = 2 solitary and 10 clonal clusters), Heteractis cripsa (n = 1), and H. magnifica (n = 1) found were bleached (Fig. 1a, b). These bleached anemones provided habitat for 19 Amphiprion melanopus, three A. percula, and two Premnas biaculeatus. We also found three Stichodactyla mertensii with nine resident A. clarkii that showed no signs of bleaching. When they were revisited from 17 to 22 October, the H. magnifica had recovered (Fig. 1c), while the H. crispa was no longer there, presumed dead. One solitary E. quadricolor remained bleached and three clusters were recovering, but the majority were gone (one solitary individual and six clusters comprising at least 23 individuals). This reduction in habitat resulted in the disappearance of nine (47.4%) A. melanopus. There were no changes in the abundance of A. clarkii, A. percula, or P. biaculeatus. The differential susceptibility and mortality of host anemones to bleaching have direct implications for the anemonefish occupying those habitats.
Hill R, Scott A (2012) The influence of irradiance on the severity of thermal bleaching in sea anemones that host anemonefish. Coral Reefs 31:273–284CrossRefGoogle Scholar
Hobbs JPA, Frisch AJ, Ford BM, Thums M, Saenz-Agudelo P, Furby KA, Berumen ML (2013) Taxonomic, spatial and temporal patterns of bleaching in anemones inhabited by anemonefishes. PLoS One 8:e70966CrossRefPubMedPubMedCentralGoogle Scholar
Hughes TP, Kerry JT, Álvarez-Noriega M, Álvarez-Romero JG, Anderson KD, Baird AH, Babcock RC, Beger M, Bellwood DR, Berkelmans R, Bridge TC (2017) Global warming and recurrent mass bleaching of corals. Nature 543:373–377CrossRefPubMedGoogle Scholar