Coral reef ecosystems have high biodiversity and unique species interactions. One example is predation on corals by parrotfish species, known for their grazing on surfaces of massive Porites stony corals. However, factors causing variations of grazing scars on Porites colonies remain largely unknown. In this study, we investigated the relationship between ocean depth of Porites colonies, grazing scar ratios, and photosynthetic efficiency, reflecting the health of coral-zooxanthellae symbiosis in Sekisei Lagoon, the largest coral reef in Japan, with distinct seasonality. We documented seasonal variation in photosynthetic efficiency of symbiotic algae and the frequency of grazing scars. Our results suggest that during the cooler season, Porites colonies with higher photosynthetic efficiency may recover from grazing more quickly than colonies with lower photosynthetic efficiency. We also suggest that fish-coral interactions may vary seasonally, possibly in relation to coral reproductive stages and environmental conditions. Further research is needed to understand the complex dynamics of these interactions in coral reefs.

Soundscape monitoring can provide valuable information on habitat quality and biodiversity of soniferous organisms in a coral reef ecosystem. However, the impacts of acute natural perturbations such as typhoons on coral reef soundscapes are poorly understood. Thus, we aimed to elucidate whether coral reef soundscapes reflect the degradation caused by Typhoon 6 (Khanun). Coral reef soundscapes were recorded by HydroMoths and quantified using the Acoustic Complexity Index (ACI) at three sites (Chinazaki, Kakinouchi and Sunabe) in Okinawa Island, Japan. In these sites, ecological data, including hard coral cover, fish species richness and abundance were obtained by visual-based surveys. We found a drastic decline in all frequency bandwidths of ACI analyzed (0.5-1 kHz, 1-2 kHz and 2-7 kHz), hard coral cover and fish species richness in Kakinouchi following the severe typhoon damage. Meanwhile, these values remained relatively constant at the other two, less impacted sites. This indicates that ACI can reliably reveal the acute impacts of typhoons on potential reef degradation. This study is the first of its kind to investigate the typhoon impacts on coral reef soundscape utilizing HydroMoths. We suggest that the simultaneous utilization of multiple HydroMoths could be a cost-effective PAM method for assessing coral reef ecological parameters across spatiotemporal scales.

The largest coral reef region in Japan, Sekisei Lagoon, experienced widespread coral bleaching and mortality in the summer of 2022 as a result of anomalously high sea surface temperatures. Bleaching impacts were recorded at 30 sites within Sekisei Lagoon. With Degree Heating Weeks (DHWs) exceeding 13.20°C-weeks, resulted in 63% of corals experiencing bleaching and 14% of the corals facing bleaching-induced mortality. Similar to the 2016 bleaching episode, Acropora species were the most affected coral genera in terms of abundance in Sekisei Lagoon, with 54.8% of the population experiencing severe bleaching and 20.7% of colonies experiencing colony mortality. Our analysis suggests that repeated heat events may have enhanced bleaching resistance at some sites in Sekisei Lagoon, as the total coral cover remained stable one year after bleaching.

Coral reefs are experiencing significant degradation caused by anthropogenic environmental changes. Sponges, such as the cyanobacteriosponge Terpios hoshinota, are becoming increasingly abundant in these ecosystems. This study examines the likelihood that T. hoshinota is invasive, identifies the types of corals that are overgrown, and investigates patterns and possible drivers of T. hoshinota outbreaks on Maldivian reefs over the past 23 years. From 1990 to 2012 reefs throughout the Maldives were surveyed using transects, photoquadrats and visual surveys. The types of corals overgrown and possible correlations between sponge prevalence and environmental variables were noted. T. hoshinota was first observed in South Malé Atoll in 1990 and has since been found in many Maldivian atolls, predominantly overgrowing massive and encrusting corals. Both large and small blooms of the sponge have been transient, possibly periodic, and increased in magnitude after 1998. Both corals and T. hoshinota exhibit boom-bust population ecologies. For corals vulnerable to bleaching, these cycles are relatively predictable and largely driven by environmental factors like sea surface temperature (SST) (Morais et al. 2021). In contrast, the ecology of T. hoshinota is poorly understood and apparently shaped by stochastic environmental factors. Interactions between the sponge and corals seem to be influenced by the effects of environmental changes on the competitive balance between the two. If current trends continue, the survival of both organisms may be at risk as the degradation of reef structures accelerates.

Due to their evolutionary conservation, mitochondrial DNA sequences are often utilized for taxonomic identification. Mushroom corals (Scleractinia: Fungiidae) are some of the most widely recognized scleractinian corals; however, their complete mitochondrial genomes have not been reported. In this study, we sequenced complete mitochondrial genomes of four species belonging to the family Fungiidae (Lithophyllon undulatum, Pleuractis paumotensis, Podabacia crustacea, and Sandalolitha robusta). In addition, we also determined the complete mitochondrial genome of Coelastrea aspera belonging to the family Merulinidae. The mitochondrial genome of this species had not been sequenced previously, although mitochondrial genomes of several other merulinids have been reported. The purpose of including this species was to confirm the accuracy of our molecular phylogenetic analysis. All fungiids sequenced in this study possessed typical mitochondrial genes, as in other scleractinians. The molecular phylogenetic position of the Fungiidae, based on complete mitochondrial genomes, is consistent with previous reports that used partial mitochondrial or nuclear gene markers. Mitochondrial sequence information presented here will contribute to our understanding of the biology, ecology, and evolution of the Scleractinia.

The coral reefs of East Peninsular Malaysia suffered a severe bleaching event in 2010, with poor scientific records of the incidents that followed. Here, a massive coral bleaching event is reported to be reoccurring in Bidong and Karah Islands, the two famous islets in the region. The phenomenon follows the second longest El Niño recorded in this past decade. This bleaching was first observed in late May 2024 and has the potential for regional-scale impacts. Secondary data from NOAA indicate that high average sea surface temperatures (SST) and Degree Heating Weeks (DHW) during this bleaching exceed records from the 2010 bleaching episode. In-situ observations confirmed the extensive impact on over 60% of coral cover, mostly affecting solitary, branching, and massive coral which predominant in the study sites. The enduring effects of this bleaching event could significantly alter coral community structures in the Bidong Archipelago for post-catastrophic scenario.

Montipora angulata (Lamarck, 1816) is one of the oldest known species in the genus, but the original description is very brief and not illustrated, so the identity of this species remains uncertain. Here, we clarify the morphological features and variation of M. angulata by redescribing the species from the type material and specimens collected from Japan. Furthermore, we review the taxonomic status of related species in the previous literature and conclude that Montipora rigida Verrill, 1866, Montipora contorta Nemenzo & Montecillo, 1981 and Montipora porites Veron, 2000 are junior synonyms of M. angulata. M. angulata sensu Veron & Wallace (1984) is reidentified as Montipora mollis Bernard, 1897 and Montipora venosa sensu Shirai & Sano (1985), Montipora digitata sensu Uchida & Fukuda (1989) and Kameda et al. (2013) and Montipora altasepta sensu Nishihira & Veron (1995) and Veron (2000) are reidentified as M. angulata. In addition, Montipora ramosa Bernard, 1897, Montipora libera Bernard, 1897, Montipora rotunda Bernard, 1897, Montipora cocosensis Vaughan, 1918 and Montipora fossae Crossland, 1952, which were considered to be junior synonyms of M. angulata by Veron and Wallace (1984), are here considered different species from M. angulata.