Free-living marine nematodes are small ubiquitous roundworms that inhabit nearly every ecosystem but are not well studied in several parts of the world. We collected sediment samples from two locations in the Strait of Singapore and analysed the nematode diversity with microscopy and molecular methods. The study revealed the presence of 20 genera previously unrecorded in the Singapore Strait, and two new records from Southeast Asian sediments, as well as an unusual abundance of epistrate-feeders.

Abstract Palytoxin, first isolated from Palythoa toxica , is among the most potent marine toxins known. Despite decades of biochemical investigation, genetic bases underlying its potential biosynthesis in Palythoa remain unresolved. Here we present four high-quality genome assemblies of Palythoa species, including Palythoa cf. toxica , and integrate these with a chromosome-scale genome assembly of P. caribaeorum . Performing comparative genomic analyses, we screened for candidate genes potentially involved in palytoxin biosynthesis and examined patterns of genome evolution. Unexpectedly, we identified only two classes of ketosynthase (KS) domain-containing genes in Palythoa : fatty acid synthases (FAS) and bacterial-like polyketide synthases (PKSs). Contrasting other anthozoans, animal FAS-like PKS (AFPK) genes common to all Palythoa species were not detected. We found no evidence for lineage-specific expansion of PKS genes unique to Palythoa , suggesting that if palytoxin/palytoxin-like molecule biosynthesis is host-encoded, it may involve functional modification or co-opting pre-existing FAS and/or bacterial-like PKS pathways. Comparative analyses revealed expansions of gene families associated with transport and binding functions in Palythoa , potentially reflecting molecular adaptations linked to their sand-incorporating body structure. We identified TPT1 and CLEC4A as rapidly evolving genes in multiple Palythoa species, consistent with possible roles in growth regulation and host-microbe interactions. Additionally, comparison between azooxanthellate and zooxanthellate species revealed mutations within conserved protein domains of LePin, which has been implicated in cnidarian endosymbiosis, suggesting lineage-specific modifications associated with symbiotic state. This study establishes a foundation for zoantharian genomic research, provides insights into lineage-specific genomic signatures, and advances molecular and evolutionary biological knowledge of this ecologically important group.

Octocorals are noted for their high diversity, with the identification of species and sometimes even genera often difficult based solely on morphological characteristics. Thus, many recent studies have employed DNA barcoding techniques to acquire diversity data. There are many octocoral specimens already deposited within zoological collections that could provide potentially important taxonomic and historical information, but due to their age, often the DNA contained in such specimens has degraded severely. One potential approach to overcome this issue is DNA mini barcoding, amplifying a shorter subset of the original barcode region. This study aimed to utilize a mini barcoding method using novel octocoral-specific primers for validating octocoral species from the Okinawa Churaumi Aquarium Zoological Collection, with specimens dating back to 1982. Based on in silico evaluations using reference sequence data including nucleotide variations and match ratio values of species delimitations, using newly designed primers, mini barcodes performed as well as full-length barcodes. Subsequently, mini barcodes were generated by these novel primers, amplifying a 215 base pairs (bp) fragment of the mitochondrial MutS-like protein (mtMutS), successfully amplifying 92.7% of 166 specimens, and sequences could be used to identify to genus level, while full-length barcoding primers amplified only 45.8% of specimens. Moreover, mini barcodes identified 67 different operational taxonomic units (OTUs) of octocorals within the specimens based on the species delimitation method of Assemble Species by Automatic Partitioning (ASAP) and unique sequences. With most octocoral specimens from the Okinawa Churaumi Aquarium Zoological Collection identified only to genus level, these additional molecular data were significantly beneficial in identifying specimens. Our study shows this DNA mini barcoding approach can cheaply and quickly acquire molecular data from comparatively older octocoral specimens, helping to identify such specimens, and adding further value to historical museum specimen collections.

Coral reefs worldwide are experiencing rapid declines due to the effects of climate change and other anthropogenic stressors. Losses of scleractinian hard corals in these ecosystems can lead to shifts in community compositions. Tracking these shifts is necessary to understand the current and future states of coral reefs undergoing such rapid change. In Okinawa, Japan, Palythoa tuberculosa is a common zoantharian species that can dominate the benthos in and around coral reefs. This study compared the compositions of hard coral-dominated benthic communities with those of nearby P. tuberculosa -dominated benthic communities at three Okinawa coral reef sites, representing among the first such datasets from the Indo-Pacific. Image data were collected from each site, and percent covers of different benthic categories were estimated based on stratified random point counts. PERMANOVA showed that benthic community composition differed significantly ( P < 0.0001) between sites, and between coral reef and P. tuberculosa patch areas within sites. Specifically, hard coral-dominated communities supported more benthic diversity than the P. tuberculosa -dominated communities, with the absence of macroalgae in P. tuberculosa -dominated communities, and lower cover of hard and soft corals. Hard coral-communities hosted more benthic categories than P. tuberculosa communities across all sites. Further research pinpointing the causes of shifts in benthic dominance could help predict future outcomes of these ecosystems, contributing to coral reef conservation.

The widespread zoantharian Palythoa caribaeorum is known for its competitive behavior, characterized by rapid growth and high dispersal capacity. In the subtropical Canary Islands, populations of P. caribaeorum have expanded due to tropicalization, transforming macroalgae-dominated ecosystems into extensive areas of this species. This shift has reduced structural complexity and biodiversity, raising concerns for local ecosystems under global warming, especially given the limited historical data available on these populations. Here, we investigated the phylogeographic patterns of P. caribaeorum populations in the Canary Islands by genetically characterizing the holobiont from various sites and assessing phylogenetic relationships with global populations of P. caribaeorum and P. tuberculosa. We analyzed the ITS-rDNA of the host and Cytb, CoxI, ITS2, and psb(Ancr) markers of the associated Symbiodiniaceae. In addition, 6 microsatellite loci were used to analyze Symbiodiniaceae population structure and connectivity across locations. Our results reveal that all P. caribaeorum specimens are phylogenetically nested within the same clade as the Indo-Pacific sibling species P. tuberculosa, with bPTP analysis supporting their inclusion within a shared species complex, thus prompting a taxonomic reassessment. Cladocopium proliferum, a generalist Symbiodiniaceae species found in Indo-Pacific coral reefs, was the only symbiont associated with P. caribaeorum in the Canary Islands. Symbiodiniaceae populations exhibited high levels of clonality and reduced allelic variation, even across a distance of similar to 400 km. This study highlights the non-native nature of P. caribaeorum in the archipelago, having likely arrived with C. proliferum, and reinforces the need to reconsider the current status and management of this colonizer species.

Anemonefish in association with anemones are iconic images of tropical coral reefs and essential to maintaining the structure and function of coral reefs. Coral reef degradation may influence host-associated microbiomes, yet its effects on anemonefish gut microbial communities remain poorly understood. This study compared the gut microbiomes of the tomato anemonefish, Amphiprion frenatus, in symbiosis with the bubble anemone host Entacmaea quadricolor, inhabiting two contrasting reef ecosystems: a degraded reef system (Nha Trang Bay - NTB) and a relatively pristine reef system (Van Phong Bay - VPB), Vietnam. Gut microbiomes from 30 fish (n = 15 per bay) were analyzed using 16S rRNA amplicon sequencing. Although Shannon diversity and Evenness did not differ significantly between bays (Shannon: 7.22 ± 0.71 in VPB vs. 6.86 ± 0.70 in NTB; Evenness: 0.84 ± 0.04 vs. 0.85 ± 0.05), fish from VPB harbored significantly richer gut microbiomes, with higher observed ASV richness (407.9 ± 144.7 vs. 282.6 ± 95.3) and Chao1 diversity estimates (626.5 ± 300.9 vs. 367.5 ± 142.8). Beta-diversity analyses showed statistically significant differences in microbial composition and density between sample groups in NTB and VPB (PERMANOVA, R2=0.094 p = 0.006). Proteobacteria and Firmicutes were dominant phyla in both communities with Firmicutes accounted for 41.59% of sequences in VPB compared with 38.04% in NTB, whereas Proteobacteria represented 35.88% and 42.59%, respectively. In contrast, NTB fish showed a greater relative abundance of Proteobacteria and Planctomycetota. PICRUSt2-based functional predictions suggested enrichment of fermentation and energy acquisition pathways in VPB fish, whereas microbiomes from NTB were associated with predicted functions related to a variety of biosynthetic and metabolic processes. These findings suggest that habitat conditions may be associated with the carbon and nitrogen cycles mediated by the microbial communities within the anemonefish-anemone symbiotic relationship.

Symbioses between anemonefish and anemones are iconic images of tropical coral reefs, and important natural resources for tourism. It is critical to quantify anemones and their communities to help better protect these natural resources. This study examined the community structure of host anemones and surrounding associated organisms in two contrasting coral reef ecosystems in central Viet Nam. Via scuba-based ecological surveys, we examined communities in a comparatively disturbed reef area, Nha Trang Bay (NTB), suffering from poor water quality, destructive fishing, coral bleaching, and Crown-of-Thorns starfish outbreaks, and at a comparatively pristine reef in nearby Van Phong Bay (VPB). Seven species of host anemones and four species of anemonefish were observed across both bays. Anemones in VPB were observed to exist in shallower waters than in NTB, and to be larger in size. Immature damselfish D. trimaculatus, inhabited anemone species and coexisted with Amphiprion spp. We observed six additional species of fish that likely used host anemones as temporary shelters, and two cleaning fish species of wrasse (Labridae) that also coexisted with anemonefish. We also confirmed the presence of three species of cleaner shrimps and one species of anemone crab. There were distinct patterns of anemone-fauna associations with organisms tending to prefer specific host anemone species. For both host anemones and anemonefish, β-diversity in NTB was higher and had a more nested structure than that of VPB. However, β-diversity and its nestedness were observed to be reduced or comparable between the two regions after excluding study sites influenced by fishing and tourism. Until now, research on anemones has almost completely focused on hosts and anemonefish, but our data also show much is to be learned from associated invertebrate fauna as well, and future anemone studies would benefit from including such data. Overall, our results show differences in the depth distribution, host anemone sizes, diversity patterns, and associated communities of host anemones between NTB and VPB. Multivariate analyses indicated that associated community composition showed weak bay-level differences but clearer site-level structure, suggesting that local habitat conditions, disturbance histories, and host-anemone composition could be more important than general bay identity alone. These patterns are consistent with previously documented differences in reef conditions between the bays, although unbalanced site-level replication and limited site-level environmental data mean that causes of such differences need to be cautiously interpreted.

Precious and semi-precious corals have been harvested all over the world since the dawn of recorded history. Their skeletons are used to make jewelry that is often perceived to possess medicinal or spiritual benefits. In the Philippines, all coral species are protected under Republic Act No. 8550 (Philippine Fisheries Code of 1998) and Republic Act No. 10654 (the amended Philippine Fisheries Code). However, many species of corals are threatened by illegal and unreported harvesting. In order to gain a better understanding of what species are targeted by such illegal activities, we investigated images and videos of non-scleractinian corals posted on Facebook between December 2014 to September 2024. Species targeted in illegal trade were identified as belonging to class Octocorallia or order Antipatharia, and encompassed at least nine families. Among them, common taxa listed as precious and semi-precious in the commercial trade included the families Antipathidae (black corals), Isididae (bamboo corals), Melithaeidae (sponge corals), Myriopathidae (black corals), Plexauridae (sea fans/sea rods), and Primnoidae. Trading activities involved corals being sold either as barter or for amounts ranging from 1 for fragments to8 – 60 for entire colonies. Potential uses included using non-scleractinian corals as decorative objects, as raw ingredients for coconut oil infusions, or making them into jewelry accessories with claimed benefits of protection against diseases, witchcraft, and evil spirits. Issues and policy recommendations for the possession and trade of non-scleractinian corals are discussed.

Japan spans one of the world’s widest latitudinal ranges of scleractinian corals, encompassing tropical accreting coral reefs in the southern Ryukyus (~ 24°N) to marginal, non-reef-building temperate coral communities along the Pacific coast of Honshu (~ 32°N). Bleaching is driven by relative thermal anomalies above local baselines rather than by absolute temperature, making even high-latitude sites susceptible when warming is sufficiently anomalous.. Using daily satellite-derived sea surface temperature (SST) and Degree Heating Week (DHW) information from NOAA Coral Reef Watch, combined with field-verified bleaching observations, we mapped the spatial extent and severity of thermal stress across Japanese coral habitats from ~ 24°N to 34°N during the 2024 global bleaching event. Maximum SST frequently exceeded 31°C in tropical and subtropical regions and surpassed 30°C at temperate sites, with all surveyed locations reaching DHW Alert Level 3. Bleaching was confirmed from southern Iriomote and Okinawa, to high-latitude sites in Kochi and Shikinejima, demonstrating elevated summer temperatures now affect corals far beyond the traditional subtropical range. Repeated bleaching since the 1990s has contributed to declining coral cover and shifts toward stress-tolerant and non-coral benthic communities on many southern subtropical reefs, whereas temperate coral populations remain constrained by episodic disturbances, storm impacts, thermal variability, and winter cold spells. Our findings highlight the exceptional latitudinal extent of the 2024 Global Coral Bleaching Event in Japan and emphasize the need for integrated, climate-adaptive conservation strategies across Japanese coral ecosystems.

Japan spans one of the world’s widest latitudinal ranges of zooxanthellate coral ecosystems, from tropical reefs in the southern Ryukyus to marginal temperate coral communities along the Pacific coast of Honshu. While high-latitude coral populations have often been viewed as potential thermal refugia, the 2024 global bleaching event provided a rare opportunity to assess their vulnerability under extreme heat stress. Using daily satellite-derived sea surface temperature (SST) and Degree Heating Week (DHW) information from NOAA Coral Reef Watch, combined with field-verified bleaching observations, we mapped the spatial extent and severity of thermal stress across Japanese coral habitats from ~ 24°N to 34°N. Maximum SST frequently exceeded 31°C in tropical and subtropical regions and surpassed 30°C at temperate sites, with all surveyed locations reaching DHW Alert Level 3. Bleaching was confirmed from southern Iriomote and Okinawa, to high-latitude sites in Kochi and Shikinejima, demonstrating elevated summer temperatures now affect corals far beyond the traditional subtropical range. Repeated bleaching since the 1990s has contributed to declining coral cover and shifts toward stress-tolerant and non-coral benthic communities on many southern subtropical reefs, whereas temperate coral populations remain constrained by episodic disturbances, storm impacts, thermal variability, and winter cold spells. The 2024 Global Coral Bleaching Event shows, Japanese mainland coral communities are not insulated from heat stress and their role as climate refugia needs reconsideration. Our findings highlight the exceptional latitudinal extent of the 2024 Global Coral Bleaching Event in Japan and emphasize the need for integrated, climate-adaptive conservation strategies across Japanese coral ecosystems.

Benthic ecosystems in the oceans around Japan are notable for their high levels of biodiversity, and many new species have been described from these waters. Among this diversity, several new taxa of the order Zoantharia (Cnidaria; Anthozoa; Hexacorallia) have been discovered in the last three decades, including the family Abyssoanthidae. Here, we report the discovery of a novel abyssoanthid from the outer slopes of an underwater volcanic seamount, formally describing Vulcanthus odoroki Reimer Kise gen. nov. et sp. nov., representing the second genus of the family. This new species can be distinguished from its confamilials by its combination of comparatively small size with comparatively low numbers of tentacles and mesenteries, by occasionally being stoloniferous and not exclusively unitary, by its zig-zagged white “ruffled” pattern following the outside edge of the oral disc, and by its unique placement as sister to Abyssoanthus within the zoantharian phylogeny. We also report the first mitogenome from the family Abyssoanthidae from this species. Based on this and other recent findings, we speculate members of the Abyssoanthidae may be far more common than are currently known. This finding reinforces the hypothesis that the deep sea yet harbors numerous undescribed zoantharians.

Coral reef ecosystems, such as those surrounding Okinawa Island, have high levels of biodiversity, especially among benthic communities. Over the last century, and particularly after World War II, major coastal development and reclamation works have been carried out along the coasts of Okinawa Island, and there are concerns about their adverse effects on the communities of organisms living in coral reef areas. Examples of methods for investigating the distribution and ecology of organisms that live on the seabed, as well as environmental impacts, include several transect and photo-quadrat techniques. However, such survey methods aim to roughly grasp the benthic biota at a spatial scale that does not target relatively small (< 5 cm) benthic organisms. Therefore, in this study, we focused on the microenvironment and conducted surveys of benthic organisms using quadrats of 0.0025 m2 (5 cm × 5 cm) (hereinafter referred to as micro-quadrats). Field surveys were conducted by scuba diving at nine coastal locations on Okinawa Island, where photographs were taken including the entire micro-quadrats (5 cm per side) in the field of view. In addition to the micro-quadrats, conventional transect (10 m length) methods were also used. Benthic coverage was calculated based on the data obtained by the identification, and the similarity of the biological communities was also compared. For the similarity comparison, we confirmed differences in community composition between sites and depending on the category of coastal development (natural, armoring, land reclamation). At the sites where reclamation had occurred, the coverage of octocorals was higher in the transect method, while the coverage of sand was highest in the micro-quadrats. In addition, significant differences were found in the community composition of organisms with the transect method and between the reclaimed and unreclaimed sites (p < 0.001). A similarly significant difference was found in the micro-quadrat method (p < 0.001). Transect results indicated that sites categorized as natural and armoring were characterized by hard coral or rock and rubble, while sites categorized as land reclamation were characterized by octocorals (mainly soft corals) or sand. In addition, micro-quadrat results indicated that sites categorized as natural or armoring were more likely to have hard coral, ascidian, and CCA, and that sites categorized as land reclamation were characterized as sand. Thus, depending on the method, the organisms and categories characterized at each site were also different. By focusing on more minute environments than conventional methods, this study demonstrates the importance of understanding the biota in microhabitats at different spatial scales.

Cambodia’s coral reefs are vital for supporting marine biodiversity and coastal livelihoods, but they remain understudied and are increasingly threatened by overfishing, habitat degradation, and climate change. Using Reef Check citizen science data from 91 reef sites (2021–2023), we examined how turbidity and productivity, sea surface temperature (SST), hard coral cover and marine protected area (MPA) designation shape coral reef communities across nearshore and offshore reefs. Our analyses revealed distinct benthic, fish, and invertebrate communities nearshore and offshore. Offshore reefs, characterized by lower turbidity and dominated by branching corals, hosted more fusiliers (Caesionidae) and wrasses (Labridae), and had higher abundances of fish and invertebrates. Nearshore turbid reefs dominated by massive and encrusting corals exhibited higher invertebrate diversity despite lower fish and invertebrate abundance. Hard coral cover increased fish abundance and biomass. Warmer SSTs were associated with reduced fish diversity. Reefs within the Koh Rong Marine National Park did not have higher fish or invertebrate diversity, abundance or targeted fish biomass than outside the MPA, which may reflect mixed zoning, site selection history and enforcement limitation. Our findings showcase the contemporary status of Cambodian reefs, and the potential of citizen science to support baseline monitoring. We recommend expanding MPAs to connect offshore and nearshore reefs while accounting for fishing pressure and enforcement capacity. We also show that integrating satellite data with citizen monitoring can aid adaptive marine conservation planning.

The delineation of closely related species remains a persistent challenge in Zoantharia, where morphological plasticity and limited genetic differentiation complicate taxonomy. In this study, we investigated the phylogenetic relationship between the widely distributed sibling taxa Palythoa tuberculosa (Indo-Pacific) and Palythoa caribaeorum (Atlantic) using ultraconserved elements (UCEs) recovered from genome skimming. A dataset comprising 116 loci (35,699 bp) across 37 specimens from Brazil, the Red Sea, Okinawa, and New Caledonia was analysed using both concatenated maximum-likelihood and coalescent-based approaches. Phylogenetic reconstructions did not recover monophyletic relationships corresponding to either species or geographic origin, instead revealing intermixed lineages across the Indo-Pacific and Atlantic regions. Concordance factor analyses indicated low gene concordance and moderate site concordance, suggesting pervasive gene tree discordance rather than a lack of phylogenetic signal. These patterns are consistent with previous studies based on mitochondrial, nuclear, and reduced-representation datasets, indicating that increased marker resolution does not resolve species boundaries within this complex. The observed lack of differentiation may reflect ongoing or recent connectivity among populations, potentially facilitated by long-distance dispersal promoted by anthropogenic rafting or historical range expansion, biological invasion, or biological processes such as incomplete lineage sorting. The results support the hypothesis that P. tuberculosa and P. caribaeorum represent a species complex or a case of incipient speciation rather than fully distinct evolutionary lineages. These findings indicate that genome-scale data alone may be insufficient to resolve very recent divergences, supporting the need for integrative approaches to resolve complicated species boundaries in zoantharians.

Paromoionchis tumidus (Semper, 1880) is currently listed as a Vulnerable (VU) species in the Red List of Japan in 2020, as well as a Near Threatened (NT) species in the Red Data Book of Okinawa in 2017. However, there is only limited information regarding the distribution and diversity of this species in southern Japan, leading to prolonged taxonomic confusion surrounding this species. Here, we surveyed sites around Okinawa-jima Island and provided mitochondrial cytochrome c oxidase subunit I (COI) and 16S rRNA gene sequences to elucidate the distribution and genetic diversity. We newly record P. tumidus from two artificial mangrove areas, the Suzaki Waterway and the Hiyagon Marsh in Nakagusuku Bay. Additional museum specimens were investigated to reveal the species distribution and diversity of P. tumidus across the Ryukyu Islands further. Based on our phylogenetic tree, all specimens examined in this study clustered with Indo-West Pacific specimens and belonged to P. tumidus unit #1 sensu Dayrat et al. (2019). By using a targeted mini-barcoding approach, we successfully retrieved molecular data from decades-old museum specimens, demonstrating that this method can effectively amplify short DNA fragments of P. tumidus. Although this study showed that P. tumidus can be found in artificially modified areas, the potential impact of anthropogenic stressors from the surrounding land on mangrove tidal habitat remains uninvestigated. Thus, further surveys comparing the presence of onchidiids in both artificial mangrove areas as in this study, and natural/pristine mangrove areas, will be crucial to understand the species' potential tolerance to environmental changes.

Plastic pollution has become a significant concern for marine environments with adverse effects on critical ecosystems such as coral reefs. Marine plastic litter items transform into new variants after prolonged exposure to the environment and interactions with organic and inorganic materials. While earlier documented variants such as plastiglomerates and plasticrusts are chiefly formed between plastic and abiogenic substrates, this study introduces plasticorals, a new form of plastic litter variant formed from plastic materials thermally adhered to or agglutinated to coral rubble. Plasticorals were incidentally observed on three beaches in Okinawa Island, Japan, during routine marine litter surveys. The plastic components of these plastic-coral agglutinate samples, examined with Raman spectroscopy showed spectral consistencies with polyethylene and polypropylene. The infiltration of skeletal pores and plastic coral interface were visualized using micro-CT scanning and microscopy. This new plastic variant provides fresh perspectives on the persistence of plastic litter in coral reef environments and highlights the potential for plasticorals to serve as future stratigraphic markers within the contemporary sedimentary record of tropical reef systems. We recommend further studies to better understand formation processes, distribution, and potential ecotoxicological impacts of plasticorals on coral reef environments.

Emerging plastic pollution forms such as plastiglomerates, pyroplastics, plasticrusts and plastitars are increasingly recognized as anthropogenic markers of the Anthropocene, yet their presence and properties remain underreported in subtropical marine environments. This study investigated the occurrence of these marine plastic litter variants on four beaches (Agu, Maehama, Hizushi and Nishibama) around Aka Island, a marine protected area located in the Kerama Islands of Okinawa in southern Japan. A total of six incidences of plastic litter variants, all pyroplastics, were confirmed from all surveyed beaches except one. Raman spectroscopy was used to assess polymer composition, and spectra indicated that all variants were consistent with polyethylene. One of the variants was colonised and encrusted by a scleractinian coral skeleton with a diameter of 15.12 mm. These findings highlight the persistence and transformation of marine plastic litter in critical marine ecosystems such as coral reefs. We recommend incorporation of these plastic variants into marine litter monitoring frameworks. This study provides baseline data on pyroplastic formation within subtropical coral reef island environments.

Shallow water coral reefs in many parts of the world are experiencing phase shifts due to various disturbances, resulting in increases in the abundance of non-scleractinian taxa, including soft corals (Octocorallia). Soft corals are known to have varied ecological roles, such as serving as habitat and food source for different organisms. However, limited studies in only a few regions have examined how different fish species utilize soft corals. In this note, we report on the different behaviors of reef fishes towards soft corals on sarcophytid soft coral-dominated reefs of Okinawa Island, Japan. We also compared the frequency of interactions of reef fishes with soft corals of varying colony morphologies. Different behaviors such as hovering over soft corals, sheltering, swimming around and through soft coral interstices, epiphyte feeding, territory defense, and cleaning behaviors were observed. Results also showed that interactions of reef fishes were higher in structurally complex branching colonies when compared to encrusting colonies of soft corals. The results of this study highlight the potential of soft corals as habitats for reef fishes, and suggest potential effects of the dominance of different soft coral taxa with different morphotypes. This study adds to our knowledge of fish behavior on and around “other” reef benthic fauna other than stony corals, which is especially important given that many reefs are undergoing shifts towards dominance of non-scleractinian taxa.