Coral assemblages at higher latitudes favor short-term potential over long-term performance.

The persistent exposure of coral assemblages to more variable abiotic regimes is assumed to augment their resilience to future climatic variability. Yet, while the determinants of coral population resilience across species remain unknown, we are unable to predict the winners and losers across reef ecosystems exposed to increasingly variable conditions. Using annual surveys of 3171 coral individuals across Australia and Japan (2016-2019), we explore spatial variation across the short- and long-term dynamics of competitive, stress-tolerant, and weedy assemblages to evaluate how abiotic variability mediates the structural composition of coral assemblages. We illustrate how, by promoting short-term potential over long-term performance, coral assemblages can reduce their vulnerability to stochastic environments. However, compared to stress-tolerant, and weedy assemblages, competitive coral taxa display a reduced capacity for elevating their short-term potential. Accordingly, future climatic shifts threaten the structural complexity of coral assemblages in variable environments, emulating the degradation expected across global tropical reefs.

Temperate functional niche availability not resident-invader competition shapes tropicalisation in reef fishes.

Temperate reefs are at the forefront of warming-induced community alterations resulting from poleward range shifts. This tropicalisation is exemplified and amplified by tropical species' invasions of temperate herbivory functions. However, whether other temperate ecosystem functions are similarly invaded by tropical species, and by what drivers, remains unclear. We examine tropicalisation footprints in nine reef fish functional groups using trait-based analyses and biomass of 550 fish species across tropical to temperate gradients in Japan and Australia. We discover that functional niches in transitional communities are asynchronously invaded by tropical species, but with congruent invasion schedules for functional groups across the two hemispheres. These differences in functional group tropicalisation point to habitat availability as a key determinant of multi-species range shifts, as in the majority of functional groups tropical and temperate species share functional niche space in suitable habitat. Competition among species from different thermal guilds played little part in limiting tropicalisation, rather available functional space occupied by temperate species indicates that tropical species can invade. Characterising these drivers of reef tropicalisation is pivotal to understanding, predicting, and managing marine community transformation.

Battle of the bands: systematics and phylogeny of the white Goniobranchus nudibranchs with marginal bands (Nudibranchia, Chromodorididae).

Species identities of Goniobranchus nudibranchs with white bodies and various marginal bands have long been problematic. In this study, specimens of these Goniobranchus nudibranchs from the Philippines, Peninsular Malaysia, Japan, Papua New Guinea, and Madagascar were analyzed and molecular data were obtained in order to re-examine the relationships between species within this "white Goniobranchus with marginal bands" group. The analyses clearly recovered six species groups corresponding to the described species Goniobranchusalbonares, G.preciosus, G.rubrocornutus, G.sinensis, and G.verrieri as well as one new species, G.fabulus Soong & Gosliner, sp. nov. Notably, G.preciosus, G.sinensis, G.rubrocornutus, G.verrieri, and G.fabulus Soong & Gosliner, sp. nov. exhibit color variation and polymorphism, suggesting that some aspects of color patterns (e.g., presence or absence of dorsal spots) may not always be useful in the identification of species in the "white Goniobranchus with marginal bands" group, whereas other features such as gill and rhinophore colors and the arrangement and colors of the mantle marginal bands are more diagnostic for each species.

Downslope migration of free-living corals (Scleractinia: Fungiidae) in typhoon-exposed reef habitats at Okinawa, Japan.

Offshore Onna Village, Okinawa Island, Japan, there is a large and densely covered coral assemblage of free-living mushroom corals (Scleractinia: Fungiidae) on a reef slope at depths from 20 m to 32 m, covering an area of approximately 350 × 40 m2. From previous research, it is known that migration distances of mushroom corals may depend on coral shapes, coral sizes, substrate, and bottom inclination. However, until now there have been no published examples of regular Fungiidae movement and behavior from typhoon-exposed coastlines, such as those in the western Pacific Ocean. Our surveys across three years offshore Onna Village show that mushroom corals always move in down-slope direction from shallow to deeper reef zones. The results indicated that mushroom corals migrated faster in autumn than in other seasons, and that oval-elongate fungiids, and particularly those with a smooth underside, migrated more quickly than species with other shapes. Surprisingly, we observed a negative relationship between the presence of typhoons and migration rates. We also observed active migration by fungiid individuals to escape situations in which they were threatened to become overgrown by Acropora corals, or when they needed to escape from burial underneath coral debris.

Phylogenomics, Origin, and Diversification of Anthozoans (Phylum Cnidaria).

Anthozoan cnidarians (corals and sea anemones) include some of the world's most important foundation species, capable of building massive reef complexes that support entire ecosystems. Although previous molecular phylogenetic analyses have revealed widespread homoplasy of the morphological characters traditionally used to define orders and families of anthozoans, analyses using mitochondrial genes or rDNA have failed to resolve many key nodes in the phylogeny. With a fully resolved, time-calibrated phylogeny for 234 species constructed from hundreds of ultraconserved elements and exon loci, we explore the evolutionary origins of the major clades of Anthozoa and some of their salient morphological features. The phylogeny supports reciprocally monophyletic Hexacorallia and Octocorallia, with Ceriantharia as the earliest diverging hexacorals; two reciprocally monophyletic clades of Octocorallia; and monophyly of all hexacoral orders with the exception of the enigmatic sea anemone Relicanthus daphneae. Divergence dating analyses place Anthozoa in the Cryogenian to Tonian periods (648-894 Ma), older than has been suggested by previous studies. Ancestral state reconstructions indicate that the ancestral anthozoan was a solitary polyp that had bilateral symmetry and lacked a skeleton. Colonial growth forms and the ability to precipitate calcium carbonate evolved in the Ediacaran (578 Ma) and Cambrian (503 Ma) respectively; these hallmarks of reef-building species have subsequently arisen multiple times independently in different orders. Anthozoans formed associations with photosymbionts by the Devonian (383 Ma), and photosymbioses have been gained and lost repeatedly in all orders. Together, these results have profound implications for the interpretation of the Precambrian environment and the early evolution of metazoans.[Bilateral symmetry; coloniality; coral; early metazoans; exon capture; Hexacorallia; Octocorallia photosymbiosis; sea anemone; ultraconserved elements.].

Two new species of the genus Chironephthya (Octocorallia, Alcyonacea, Nidaliidae, Siphonogorgiinae) from the Gulf of Thailand.

Two new species of the genus Chironephthya, C. sirindhornae sp. nov. and C. cornigera sp. nov., are described based on three specimens collected from the Gulf of Thailand. Both species are well distinguished from the previously described species of the genus Chironephthya by their colonies consisting of multiple stems that stand upright from a common base, and by a significantly thinner canal wall without large spindles. As a result of phylogenetic analyses using COI, mtMutS, and 28S rDNA sequences of these two species, these three specimens constituted an independent small clade within a large mixed clade of Siphonogorgia and Chironephthya, with the two species slightly different from each other. The discrepancy in the morphology suggested the erection of a new genus to accommodate these species, however, as the subclade was included in a large mixed clade of Siphonogorgia and Chironephthya, we place these species within genus Chironephthya. Our results further highlight the continuing confusion between Siphonogorgia and Chironephthya, and demonstrate the need for taxonomic revision of these genera.

Palaeoclimate ocean conditions shaped the evolution of corals and their skeletons through deep time.

Identifying how past environmental conditions shaped the evolution of corals and their skeletal traits provides a framework for predicting their persistence and that of their non-calcifying relatives under impending global warming and ocean acidification. Here we show that ocean geochemistry, particularly aragonite-calcite seas, drives patterns of morphological evolution in anthozoans (corals, sea anemones) by examining skeletal traits in the context of a robust, time-calibrated phylogeny. The lability of skeletal composition among octocorals suggests a greater ability to adapt to changes in ocean chemistry compared with the homogeneity of the aragonitic skeleton of scleractinian corals. Pulses of diversification in anthozoans follow mass extinctions and reef crises, with sea anemones and proteinaceous corals filling empty niches as tropical reef builders went extinct. Changing environmental conditions will likely diminish aragonitic reef-building scleractinians, but the evolutionary history of the Anthozoa suggests other groups will persist and diversify in their wake.

Ceriantharia (Cnidaria) of the World: an annotated catalogue and key to species.

The diversity of Ceriantharia is known from studies formally describing species from the late 18th Century onwards. However, no nomenclators including a list and discussion of all valid species have been produced since a list discussed by Carlgren in 1912. The present nomenclator presents a complete list of adult species of Ceriantharia of the World, including a discussion on each species. It includes the three families (Arachnactidae, Botrucnidiferidae, Cerianthidae) and the currently accepted 54 species based on their adult form. This study serves as a presentation of the "state-of-the-art" list of species of Ceriantharia, and includes a species identification key to support taxonomic identification. Additional in-depth species-by-species investigations for almost all cerianthid species is still needed, as the information available for most of these species is quite superficial.

Environmental DNA can act as a biodiversity barometer of anthropogenic pressures in coastal ecosystems.

Loss of biodiversity from lower to upper trophic levels reduces overall productivity and stability of coastal ecosystems in our oceans, but rarely are these changes documented across both time and space. The characterisation of environmental DNA (eDNA) from sediment and seawater using metabarcoding offers a powerful molecular lens to observe marine biota and provides a series of 'snapshots' across a broad spectrum of eukaryotic organisms. Using these next-generation tools and downstream analytical innovations including machine learning sequence assignment algorithms and co-occurrence network analyses, we examined how anthropogenic pressures may have impacted marine biodiversity on subtropical coral reefs in Okinawa, Japan. Based on 18 S ribosomal RNA, but not ITS2 sequence data due to inconsistent amplification for this marker, as well as proxies for anthropogenic disturbance, we show that eukaryotic richness at the family level significantly increases with medium and high levels of disturbance. This change in richness coincides with compositional changes, a decrease in connectedness among taxa, an increase in fragmentation of taxon co-occurrence networks, and a shift in indicator taxa. Taken together, these findings demonstrate the ability of eDNA to act as a barometer of disturbance and provide an exemplar of how biotic networks and coral reefs may be impacted by anthropogenic activities.

Corrigenda: Hanah, a replacement name for Hana Lau, Stokvis, Ofwegen & Reimer, 2018 (preoccupied name).

[This corrects the article DOI: 10.3897/zookeys.790.28875.].

A first phylogenetic study on stoloniferous octocorals off the coast of Kota Kinabalu, Sabah, Malaysia, with the description of two new genera and five new species.

Sabah, Malaysia, is well known for its extensive and diverse coral reefs. It is located on the northwestern edge of the Coral Triangle, the region with the highest marine biodiversity. Much of the marine fauna here is still unknown, especially inconspicuous animals, such as small stoloniferous octocorals, which are common on coral reefs. Here, we describe two new monospecific genera of the family Arulidae found off the coast of Kota Kinabalu, Sabah, East Malaysia; Bunga payung gen. nov. et sp. nov. and Laeta waheedae gen. nov. et sp. nov. As well, the stoloniferan genus Phenganax Alderslade & McFadden, 2011 belonging to the family Clavulariidae is expanded with three new species, P. marumi sp. nov., P. subtilis sp. nov., and P. stokvisi sp. nov., which are all sclerite-free. Additionally, we report a possibly undescribed species, closely related to the clavulariid genera Azoriella Lopez-Gonzalez & Gili, 2001 and Cervera Lopez-Gonzalez et al., 1995. As this and other recent studies have shown, discoveries of small stoloniferous octocorals are helping to fill gaps in our knowledge of the overall systematics of Octocorallia.

Expanding walls and shrinking beaches: loss of natural coastline in Okinawa Island, Japan.

Okinawa is the largest and most populated island of the Ryukyu Archipelago in southern Japan and is renowned for its natural resources and beauty. Similar as to what has been happening in the rest of the country, Okinawa Island has been affected by an increasing amount of development and construction work. The trend has been particularly acute after reversion to Japanese sovereignty in 1972, following 27 years of post-war American administration. A coastline once characterized by extended sandy beaches surrounded by coral reefs now includes tracts delimited by seawalls, revetments, and other human-made hardening structures. Additionally, part of coastal Okinawa Island was obtained by land-filling shallow ocean areas (land reclamation). Nevertheless, the current extension of the artificial coastline, as well as the level of fragmentation of the natural coastline are unclear, due to the lack of both published studies and easily accessible and updated datasets. The aims of this research were to quantify the extension of coastline alterations in Okinawa Island, including the amount of land-filling performed over the last 41 years, and to describe the coastlines that have been altered the most as well as those that are still relatively pristine. The analyses were performed using a reference map of Okinawa Island based on GIS vector data extracted from the OpenStreetMap (OSM) coastline dataset (average node distance for Okinawa Island = 24 m), in addition to satellite and aerial photography from multiple providers. We measured 431.8 km of altered coastline, equal to about 63% of the total length of coastline in Okinawa Island. Habitat fragmentation is also an issue as the remaining natural coastline was broken into 239 distinct tracts (mean length = 1.05 km). Finally, 21.03 km2 of the island's surface were of land reclaimed over the last 41 years. The west coast has been altered the most, while the east coast is in relatively more natural conditions, particularly the northern part, which has the largest amount of uninterrupted natural coastline. Given the importance of the ecosystem services that coastal and marine ecosystems provide to local populations of subtropical islands, including significant economic income from tourism, conservation of remaining natural coastlines should be given high priority.

Phylogenetic relationships among the clownfish-hosting sea anemones.

The clownfish-sea anemone symbiosis has been a model system for understanding fundamental evolutionary and ecological processes. However, our evolutionary understanding of this symbiosis comes entirely from studies of clownfishes. A holistic understanding of a model mutualism requires systematic, biogeographic, and phylogenetic insight into both partners. Here, we conduct the largest phylogenetic analysis of sea anemones (Order Actiniaria) to date, with a focus on expanding the biogeographic and taxonomic sampling of the 10 nominal clownfish-hosting species. Using a combination of mtDNA and nuDNA loci we test (1) the monophyly of each clownfish-hosting family and genus, (2) the current anemone taxonomy that suggests symbioses with clownfishes evolved multiple times within Actiniaria, and (3) whether, like the clownfishes, there is evidence that host anemones have a Coral Triangle biogeographic origin. Our phylogenetic reconstruction demonstrates widespread poly- and para-phyly at the family and genus level, particularly within the family Stichodactylidae and genus Stichodactyla, and suggests that symbioses with clownfishes evolved minimally three times within sea anemones. We further recover evidence for a Tethyan biogeographic origin for some clades. Our data provide the first evidence that clownfish and some sea anemone hosts have different biogeographic origins, and that there may be cryptic species of host anemones. Finally, our findings reflect the need for a major taxonomic revision of the clownfish-hosting sea anemones.

Digging for DNA at depth: rapid universal metabarcoding surveys (RUMS) as a tool to detect coral reef biodiversity across a depth gradient.

BACKGROUND: Effective biodiversity monitoring is fundamental in tracking changes in ecosystems as it relates to commercial, recreational, and conservation interests. Current approaches to survey coral reef ecosystems center on the use of indicator species and repeat surveying at specific sites. However, such approaches are often limited by the narrow snapshot of total marine biodiversity that they describe and are thus hindered in their ability to contribute to holistic ecosystem-based monitoring. In tandem, environmental DNA (eDNA) and next-generation sequencing metabarcoding methods provide a new opportunity to rapidly assess the presence of a broad spectrum of eukaryotic organisms within our oceans, ranging from microbes to macrofauna. METHODS: We here investigate the potential for rapid universal metabarcoding surveys (RUMS) of eDNA in sediment samples to provide snapshots of eukaryotic subtropical biodiversity along a depth gradient at two coral reefs in Okinawa, Japan based on 18S rRNA. RESULTS: Using 18S rRNA metabarcoding, we found that there were significant separations in eukaryotic community assemblages (at the family level) detected in sediments when compared across different depths ranging from 10 to 40 m (p = 0.001). Significant depth zonation was observed across operational taxonomic units assigned to the class Demospongiae (sponges), the most diverse class (contributing 81% of species) within the phylum Porifera; the oldest metazoan phylum on the planet. However, zonation was not observed across the class Anthozoa (i.e., anemones, stony corals, soft corals, and octocorals), suggesting that the former may serve as a better source of indicator species based on sampling over fine spatial scales and using this universal assay. Furthermore, despite their abundance on the examined coral reefs, we did not detect any octocoral DNA, which may be due to low cellular shedding rates, assay sensitivities, or primer biases. DISCUSSION: Overall, our pilot study demonstrates the importance of exploring depth effects in eDNA and suggest that RUMS may be applied to provide a baseline of information on eukaryotic marine taxa at coastal sites of economic and conservation importance.

Urban coral reefs: Degradation and resilience of hard coral assemblages in coastal cities of East and Southeast Asia.

Given predicted increases in urbanization in tropical and subtropical regions, understanding the processes shaping urban coral reefs may be essential for anticipating future conservation challenges. We used a case study approach to identify unifying patterns of urban coral reefs and clarify the effects of urbanization on hard coral assemblages. Data were compiled from 11 cities throughout East and Southeast Asia, with particular focus on Singapore, Jakarta, Hong Kong, and Naha (Okinawa). Our review highlights several key characteristics of urban coral reefs, including "reef compression" (a decline in bathymetric range with increasing turbidity and decreasing water clarity over time and relative to shore), dominance by domed coral growth forms and low reef complexity, variable city-specific inshore-offshore gradients, early declines in coral cover with recent fluctuating periods of acute impacts and rapid recovery, and colonization of urban infrastructure by hard corals. We present hypotheses for urban reef community dynamics and discuss potential of ecological engineering for corals in urban areas.

Speciation among sympatric lineages in the genus Palythoa (Cnidaria: Anthozoa: Zoantharia) revealed by morphological comparison, phylogenetic analyses and investigation of spawning period.

Zoantharians are sessile marine invertebrates and colonial organisms possessing sexual and asexual reproductive ability. The zooxanthellate zoantharian genus Palythoa is widely distributed in coral reef ecosystems. In the Ryukyu Archipelago, Japan, sympatric Palythoa tuberculosa and P. mutuki are the dominant species of this genus in the intertidal zone. Previous phylogenetic analyses have shown that these two species are closely related, and additionally revealed a putative sympatric hybrid species (designated as Palythoa sp. yoron). In this study, we attempted to delineate Palythoa species boundaries and to clarify the relationships among these three groups plus another additional putative sympatric species (P. aff. mutuki) by multiple independent criteria. The morphology of these four lineages was clearly different; for example the number of tentacles was significantly different for each species group in all pairwise comparisons. From observations of gonadal development conducted in 2010 and 2011, P. sp. yoron and P. aff. mutuki appear to be reproductively isolated from P. tuberculosa. In the phylogenetic tree resulting from maximum likelihood analyses of the ITS-rDNA sequence alignment, P. tuberculosa and P. sp. yoron formed a very well supported monophyletic clade (NJ = 100%, ML = 95%, Bayes = 0.99). This study demonstrates that despite clear morphological and/or reproductive differences, P. tuberculosa and P. sp. yoron are phylogenetically entangled and closely related to each other, as are P. mutuki and P. aff. mutuki. Additionally, no single molecular marker was able to divide these four lineages into monophyletic clades by themselves, and a marker that has enough resolution to solve this molecular phylogenetic species complex is required. In summary, the morphological and reproductive results suggest these lineages are four separate species, and that incomplete genetic lineage sorting may prevent the accurate phylogenetic detection of distinct species with the DNA markers utilized in this study, demonstrating the value of morphological and reproductive data when examining closely related lineages.

KB343, a Cyclic Tris-guanidine Alkaloid from Palauan Zoantharian Epizoanthus illoricatus.

A new tris-guanidine alkaloid, KB343 (1), was isolated from the aqueous extract of a Palauan zoantharian, Epizoanthus illoricatus. The structure of 1 was determined on the basis of spectral analyses of 1 and its derivatives. The absolute configuration for 1 was determined upon comparison of the CD spectrum of 1 to those obtained from density functional theory calculations. The structure of 1 is highly unusual, as three guanidine groups are present in one ring system.

Shifting communities after-- typhoon damage on an upper mesophotic reef in Okinawa, Japan.

Very few studies have been conducted on the long-term effects of typhoon damage on mesophotic coral reefs. This study investigates the long-term community dynamics of damage from Typhoon 17 (Jelawat) in 2012 on the coral community of the upper mesophotic Ryugu Reef in Okinawa, Japan. A shift from foliose to bushy coral morphologies between December 2012 and August 2015 was documented, especially on the area of the reef that was previously recorded to be poor in scleractinian genera diversity and dominated by foliose corals. Comparatively, an area with higher diversity of scleractinian coral genera was observed to be less affected by typhoon damage with more stable community structure due to less change in dominant coral morphologies. Despite some changes in the composition of dominant genera, the generally high coverage of the mesophotic coral community is facilitating the recovery of Ryugu Reef after typhoon damage.

Evolutionary history of the extant amphioxus lineage with shallow-branching diversification.

Amphioxus or lancelets have been regarded as a key animal in understanding the origin of vertebrates. However, the evolutionary history within this lineage remains unexplored. As the amphioxus lineage has likely been separated from other chordates for a very long time and displays a marked left-right asymmetry, its evolutionary history is potentially helpful in better understanding chordate and vertebrate origins. We studied the phylogenetic relationships within the extant amphioxus lineage based on mitochondrial genomes incorporating new Asymmetron and Epigonichthys populations, and based on previously reported nuclear transcriptomes. The resulting tree patterns are consistent, showing the Asymmetron clade diverging first, followed by the Epigonichthys and Branchiostoma clades splitting. Divergence time estimates based on nuclear transcriptomes with vertebrate calibrations support a shallow diversification of the extant amphioxus lineage in the Tertiary. These estimates fit well with the closure of seaways between oceans by continental drift, ocean currents, and present geographical distributions, and suggest a long cryptic history from the origin of amphioxus to its most recent diversification. Deduced character polarities based on phylogenetic analyses suggest that the common ancestor of the extant amphioxus existed in a tiny epibenthic state with larva-like appearance of extant amphioxus, likely with ciliate epidermis.

Diversity of Microbial Communities and Quantitative Chemodiversity in Layers of Marine Sediment Cores from a Causeway (Kaichu-Doro) in Okinawa Island, Japan.

Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan "Kaichu-Doro" Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima) to the Okinawan main island. This causeway was not built on pilings, but by land reclamation; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores (n = 10) from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (<150 m) than to other pairs, but now the members of each pair are isolated by the causeway. Each core was 60-80 cm long and was divided into 15-cm layers. We examined the vertical diversity of microbial communities and chemical compounds to determine the correlation between chemodiversity and microbial communities among marine sediment cores and layers. Principal coordinate analyses (PCoA) of detected compounds and of bacterial and archaeal operational taxonomic units (OTUs) revealed that the north and south sides of the causeway are relatively isolated, with each side having unique microbial OTUs. Additionally, some bacterial families (e.g., Acidaminobacteraceae, Rhizobiaceae, and Xanthomonadaceae) were found only on the south side of Kaichu-Doro. Interestingly, we found that the relative abundance of OTUs for some microbial families increased from top to bottom, but this was reversed in some other families. We conclude that the causeway has altered microbial community composition and metabolite profiles in marine sediments.