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Associations between different taxa constitute critical data to recognize ecological symbioses. Acoela flatworms of the genus Waminoa are an overlooked but often present group in coral reef ecosystems. More than 97% of the reports on Waminoa individuals until now have found them on scleractinian coral species, and the relationships between Waminoa species and other potential hosts such as octocorals, which are often large and ecologically important components in coral reefs, are not known well. Here we report the first observation of Waminoa sp. from a species of Dendronephthya, at Zanpa, Okinawa, Japan. We observed three morphotypes on a colony of D. aff. rigida (Studer, 1888), with almost all Waminoa individuals in shaded locations. [ABSTRACT FROM AUTHOR]

Here, we sequenced and annotated the complete mitochondrial genome for the sea-pen, Cavernularia obesa (Valenciennes, 1850). The complete mitogenome of C. obesa is 18,641 bp, with 34.7% of GC ratio. The mitogenome comprises 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a non-coding region. Phylogenomic analysis based on 19 in-group taxa belonging to the orders Alcyonacea and Pennatulacea has congruent with published phylogenetic relationship for Octocorallia, which C. obesa was grouped to members of the Pennatulacea. This mitogenome resource will be useful for future phylogenetic studies of water fleas. [ABSTRACT FROM AUTHOR]

A new soft coral species, Xenia konohana sp. nov. (Alcyonacea, Xeniidae), is described from Miyazaki in the warm-temperate region of Japan. This new species has conspicuous and unique spindle sclerites in addition to the simple ellipsoid platelet-shaped sclerites typically found in the genus Xenia. These unique spindles are a specific key morphological characteristic for this new species and for differentiating this species among congeneric species. [ABSTRACT FROM AUTHOR]

Up to one‐third of all described marine species inhabit coral reefs, but the future of these hyperdiverse ecosystems is insecure due to local and global threats, such as overfishing, eutrophication, ocean warming and acidification. Although these impacts are expected to have a net detrimental effect on reefs, it has been shown that some organisms such as octocorals may remain unaffected, or benefit from, anthropogenically induced environmental change, and may replace stony corals in future reefs. Despite their potential importance in future shallow‐water coastal environments, the molecular mechanisms leading to the resilience to anthropogenically induced stress observed in octocorals remain unknown. Here, we use manipulative experiments, proteomics and transcriptomics to show that the molecular toolkit used by Pinnigorgia flava, a common Indo‐Pacific gorgonian octocoral, to deposit its calcium carbonate skeleton is resilient to heat and seawater acidification stress. Sublethal heat stress triggered a stress response in P. flava but did not affect the expression of 27 transcripts encoding skeletal organic matrix (SOM) proteins. Exposure to seawater acidification did not cause a stress response but triggered the downregulation of many transcripts, including an osteonidogen homologue present in the SOM. The observed transcriptional decoupling of the skeletogenic and stress‐response toolkits provides insights into the mechanisms of resilience to anthropogenically driven environmental change observed in octocorals. [ABSTRACT FROM AUTHOR]

The hydrozoan family Cladocorynidae inhabits tropical to temperate waters and comprises the two genera Pteroclava and Cladocoryne. Pteroclava lives in association with some octocorals and hydrozoans, whereas Cladocoryne is more generalist in terms of substrate choice. This work provides a thorough morpho‐molecular reassessment of the Cladocorynidae by presenting the first well‐supported phylogeny of the family based on the analyses of three mitochondrial and four nuclear markers. Notably, the two nominal genera were confirmed to be monophyletic and both morphological and genetic data led to the formal description of a new genus exclusively associated with octocorals, Pseudozanclea gen. nov. Maggioni & Montano. Accordingly, the diagnosis of the family was updated. The ancestral state reconstruction of selected characters revealed that the symbiosis with octocorals likely appeared in the most recent common ancestor of Pteroclava and Pseudozanclea. Additionally, the presence of euryteles aggregation in the polyp stage and the exumbrellar nematocyst pouches with euryteles represent synapomorphies of all cladocorynid taxa and probably emerged in their most recent common ancestor. The analysis of several Pteroclava krempfi colonies from Indo‐Pacific and Caribbean localities associated with several host octocorals revealed a high intra‐specific genetic variability. Single‐ and multi‐locus species delimitations resulted in three to five species hypotheses, but the statistical analysis of morphometric data showed only limited distinction among the clades of P. krempfi. However, P. krempfi clades showed differences in both host specificity, mostly at the octocoral family level, and geographic distribution, with one clade found exclusively in the Caribbean Sea and the others found in the Indo‐Pacific. [ABSTRACT FROM AUTHOR]

For many years an undescribed species of the genus Bathypathes has been misidentified as Bathypathes alternata Brook, 1889 (a species currently re-assigned to the genus Alternatipathes). This new species is rather common at mid- and lower bathyal depths of the Pacific, Atlantic and Indian oceans, often in areas with high concentrations of commercially valuable cobalt-rich ferromanganese crusts, where it was observed in underwater photo and video transects to occur in high densities. Under the name B. alternata this species is recorded in several inventories and databases. There is an urgent need for a formal description of this misidentified and widely distributed species to avoid further confusion. The new species is superficially similar to A. alternata in having a monopodial corallum and simple, bilateral and alternately arranged pinnules. However, it differs from the former in that it has an upright corallum with a straight pinnulated part (vs. a horizontally bent pinnulated part), pinnules of uniform length and density (vs. decreasing regularly distally), and a constant distal angle formed by the pinnules and the stem along different parts of the corallum (vs. a decreasing distal angle near the top). The new species can therefore be easily distinguished from A. alternata in underwater imagery. We formally describe this new species in the genus Bathypathes and assign it the new name B. pseudoalternata. An extensive synonymy list with previous misidentified records is provided. To evaluate the distributional patterns of the new species we review the geographic distribution of antipatharians reported below 800 m. The majority of the hitherto described lower bathyal and abyssal species have been recorded from one biogeographic province; however, 20 species are known from more than two provinces, and only three species are widely distributed (>5 provinces), including the newly described Bathypathes pseudoalternata. Members of the family Schizopathidae, to which the new species belongs, represent the majority of the lower bathyal (50.54%) and abyssal (82.35%) species. [ABSTRACT FROM AUTHOR]

Mutualistic nutrient cycling in the coral-algae symbiosis depends on limited nitrogen (N) availability for algal symbionts. Denitrifying prokaryotes capable of reducing nitrate or nitrite to dinitrogen could thus support coral holobiont functioning by limiting N availability. Octocorals show some of the highest denitrification rates among reef organisms; however, little is known about the community structures of associated denitrifiers and their response to environmental fluctuations. Combining 16S rRNA gene amplicon sequencing with nirS in-silico PCR and quantitative PCR, we found differences in bacterial community dynamics between two octocorals exposed to excess dissolved organic carbon (DOC) and concomitant warming. Although bacterial communities of the gorgonian Pinnigorgia flava remained largely unaffected by DOC and warming, the soft coral Xenia umbellata exhibited a pronounced shift toward Alphaproteobacteria dominance under excess DOC. Likewise, the relative abundance of denitrifiers was not altered in P. flava but decreased by 1 order of magnitude in X. umbellata under excess DOC, likely due to decreased proportions of Ruegeria spp. Given that holobiont C:N ratios remained stable in P. flava but showed a pronounced increase with excess DOC in X. umbellata, our results suggest that microbial community dynamics may reflect the nutritional status of the holobiont. Hence, denitrifier abundance may be directly linked to N availability. This suggests a passive regulation of N cycling microbes based on N availability, which could help stabilize nutrient limitation in the coral-algal symbiosis and thereby support holobiont functioning in a changing environment. [ABSTRACT FROM AUTHOR]

Marine Natural Products (MNPs) isolated from samples collected in Colombia have been an object of study since the early 1980's; however, this information is neither integrated nor compiled. This systematic review describes the articles published in scientific journals up to December 2019. 173 papers met the inclusion criteria of focusing on MNPs obtained from specimens collected from Colombian seas; all original papers written in English, Portuguese or Spanish. The selected papers were mostly authored by researchers from Colombian groups, with low interaction amongst themselves. 99.4% of the papers studied samples collected from the Caribbean Sea; 183 species were studied, mainly sponges and octocorals. In this study, 1,690 compounds (238 new ones) were reviewed, mainly diterpenes and sterol derivatives. Of the selected papers, 76.8% measured various biological activities, including antibiotic (34%) and anticancer (30%). These papers were published in 51 journals (74.6% were international). In conclusion, scientific work on natural marine products of Colombian origin has incremented over time. The most relevant opportunities to address and fill existing gaps comprise: exploring Pacific Ocean organisms and several of the misrepresented taxa; promoting strong interactions amongst the MNPs research groups, and accordingly with other areas of knowledge; and having the productive sector participate in MNPs research. [ABSTRACT FROM AUTHOR]

The assessment of effective and affordable restoration interventions is pivotal to developing new tools to mitigate habitat loss and enhance natural recovery. Gorgonians create important three‐dimensional habitats in the Mediterranean Sea providing several ecosystem services associated with coralligenous reefs. Transplantations of the octocorals Eunicella cavolini, Eunicella singularis, and Paramuricea clavata were carried out at the site impacted by the wreck of the Costa Concordia in 2012. A total of 135 by‐caught gorgonians, caught in the gears of local artisanal fishermen or found lying on the seabed by SCUBA divers, were transplanted on impacted coralligenous reefs between 20 and 35 m depth and monitored for 2.5 years. A high survival rate (82.1%) was recorded, with main losses attributable to the detachment of the organisms from the substrate rather than death of the colonies. Eunicella cavolini transplanted colonies and natural colonies used as controls were monitored and showed similar, and seasonally influenced, growth and healing rates. Epibiosis and necrosis events were reported in both transplanted and natural colonies during summer, highlighting the sensitivity of the species to thermal stress. The present study emphasizes the importance of a management framework as a stepping‐stone to achieve effective restoration outcomes, including the removal of pressures that caused changes in natural communities and the participation of local stakeholders. The effectiveness of the methods and procedures proposed in this work allowed the restoration activities to continue at a larger scale during summer and autumn 2020. [ABSTRACT FROM AUTHOR]

Background and Objectives: Paralemnalia thyrsoides is an octocoral species of the family Nephtheidae. It has established as platform for the production of a varied array of sesquiterpenoids such as africanane, nardosinane, and neolemnane -type compounds. Antiviral and cytotoxic effects of sesquiterpenes from P. thyrsoides were reported. Materials and Methods: The animal sample of P. thyrsoides was repeatedly extracted with organic solvents. Then, the animal extract was fractionated and purified employing different planar chromatographic methods. The chemical structures of all isolated metabolites were identified by employing spectroscopic tools (ultraviolet [UV], IR, and nuclear magnetic resonance) along with MS. The anti-inflammatory activity (membrane stabilization%), and histamine release inhibitory effect, the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, along with cytotoxic activity against four-cancer cells: hepatocellular carcinoma (Hep G-2), colon (HCT-116), prostate (PC-3), and breast (MCF-7) cancers were evaluated. Results: Three new sesquiterpenoids along with two known ones and a gorgostane steroid. The three new sesquiterpenoids were identified as eudesma-1, 2, 15-trihydroxy-3-en-7-one (1), eudesma-1, 2, 15-trihydroxy-5-ene (2), and nardosinanol J (3). Whereas the known compounds were identified as lemnolin A (4) and gorgostane (5). The in-vitro assays results revealed that the total organic extract showed anti-inflammatory activity (membrane stabilization %) with IC50 of 88.3 ± 1.2 compared to positive control (indomethacin with IC50 of 17.02 ± 1.2 μg/ml) and strong histamine release inhibitory effect with IC50 of 17.94 ± 1.08 compared to a positive control (diclofenac with IC50 of 17.94 ± 1.26 μg/ml). It also showed that the total organic extract has antioxidant activity using DPPH assay with an IC50 of 157.5 ± 4.24μg/ml. Moreover, the total organic extract has strong inhibitory activities against Hep G-2 with an IC50 of 12.1 ± 1.1 μg/ml, HCT-116 with an IC50 of 13.4 ± 1.8 μg/ml, PC-3 with an IC50 of 28.6 ± 2.7 μg/ml, and good inhibitory activity against MCF-7 with an IC50 of 49.0 ± 3.9 μg/ml. Conclusion: The observed bioactivity and the variety of carbon skeletons isolated warrants further work on the constituents of P. thyrsoides. [ABSTRACT FROM AUTHOR]

Understanding the resilience of temperate reefs to climate change requires exploring the recovery capacity of their habitat-forming species from recurrent marine heatwaves (MHWs). Here, we show that, in a Mediterranean highly enforced marine protected area established more than 40 years ago, habitat-forming octocoral populations that were first affected by a severe MHW in 2003 have not recovered after 15 years. Contrarily, they have followed collapse trajectories that have brought them to the brink of local ecological extinction. Since 2003, impacted populations of the red gorgonian Paramuricea clavata (Risso, 1826) and the red coral Corallium rubrum (Linnaeus, 1758) have followed different trends in terms of size structure, but a similar progressive reduction in density and biomass. Concurrently, recurrent MHWs were observed in the area during the 2003–2018 study period, which may have hindered populations recovery. The studied octocorals play a unique habitat-forming role in the coralligenous assemblages (i.e. reefs endemic to the Mediterranean Sea home to approximately 10% of its species). Therefore, our results underpin the great risk that recurrent MHWs pose for the long-term integrity and functioning of these emblematic temperate reefs. [ABSTRACT FROM AUTHOR]

The objective of the present study is to assess the status of the octocoral communities, and the extent of bleaching they suffered in 2016 (in line with the third Global Bleaching Event). Bleaching survey was carried out in the permanently fixed study sites in the 21 island of Gulf of Mannar. A focused study was carried out in Kariyachalli Island to monitor post-bleaching effects on octocorals. The overall octocoral cover in 2015 was 1.59±0.29%, and octocoral genera such as Sinularia, Sarcophyton, Lobophytum and Subergorgia were observed predominantly in GoM (Gulf of Mannar). Temperature reached a maximum of 32.5°C (March) during 2016 bleaching. The extent of bleaching in 2016 was 1.05±0.65% and the overall octocoral cover was reduced to 1.16±0.22%. Multiple paired t-test results indicate a significant variation in the octocoral covers between 2015 and 2016 (t = 3.173, p < 0.01). Sinularia, Xenia, and Subergorgia were the most affected genera during this bleaching episode. The percentage bleaching in octocorals was the highest in Vembar group of islands (1.9±0.62%) and the continuous monitoring studies reveal the increase in the octocorals diversity from 1.16±0.22% to 1.34±0.21% in 2018 indicating the recovery pattern of octocorals in GoM. Post-bleaching surveys carried out in Kariyachalli Island revealed the occurrence of tissue degradation and algal overgrowth following the bleaching event. However, this study concludes that octocorals in GoM could adapt and flourish in the context of changing climatic conditions. However, more studies on octocoral ecology and biology are warranted. Research highlights: Percentage cover of the octocorals in Gulf of Mannar was assessed with a total of 16 octocoral genera was recorded during the study. The octocoral cover decreased from 1.59±0.29% (2015) to 1.16±0.22% (2016) and then again increased to 1.34% (2018); with the extent of bleaching of 1.05±0.65% (2016). Sinularia, Xenia and Subergorgia were the most affected genera during this bleaching episode of octocorals. Unusual tulf algal overgrowth with tissue degradation was witnessed in the octocoral genera Sinularia sp. [ABSTRACT FROM AUTHOR]

Mid‐ocean ridges generate a myriad of physical oceanographic processes that favor the supply of food and nutrients to suspension‐ and filter‐feeding organisms, such as cold‐water corals and deep‐sea sponges. However, the pioneering work conducted along the Mid‐Atlantic Ridge failed to report the presence of large and dense living coral reefs, coral gardens, or sponge aggregations. Here, we describe the densest, near‐natural, and novel octocoral garden composed of large red and white colonies of Paragorgia johnsoni Gray, 1862 discovered at 545–595 m depth on the slopes of the Mid‐Atlantic Ridge, in the Azores region. This newly discovered octocoral garden is a good candidate for protection since it fits many of the FAO criteria that define what constitutes a Vulnerable Marine Ecosystem. The observations described here corroborate the existence of a close relationship between the octocoral structure and the ambient currents on ridge‐like topographies, providing new insights into the functioning of mid‐ocean ridges' ecosystems. The ubiquitous presence of biogenic and geological topographies associated with mid‐ocean ridges, which could act as climate refugia, suggests their global importance for deep‐sea biodiversity. A better understanding of the processes involved is, therefore, required. Our observations may inspire future deep‐sea research initiatives to narrow existing knowledge gaps of biophysical connections with benthic fauna at small spatial scales along mid‐ocean ridges. [ABSTRACT FROM AUTHOR]

The current knowledge on the diversity of the genus Plexaurella is based on a series of dated revisions, often with no examination of types. Although being common octocorals in western Atlantic reefs, there is no consensus on an exact number of valid species. Furthermore, phylogenetic reconstructions do not support the current classification of Plexaurella within the family Plexauridae. Thus, this study reviews the genus based on examination of available types and assesses monophyly using mitochondrial (COI+igr , mtMutS) and nuclear (28S) markers, mostly from available molecular data. Until now, up to six species were considered valid. Our results show that the group is composed of at least seven previously described species: P. dichotoma , P. nutans , P. grisea , P. teres , P. grandiflora , P. regia and P. obesa ; and one new species: Plexaurella rastrera sp. nov. An illustrated key to the valid species and a list of all available names are provided and the current classification of the genus is discussed. Based on congruent phylogenetic reconstructions and genetic distances, we propose the elevation of the former plexaurid subfamily Plexaurellinae to family level. Finally, based on examination of types, we propose the synonymy between Pseudoplexaura crucis and Plexaurella tenuis under Pseudoplexaura tenuis new comb. Corals of the genus Plexaurella are conspicuous sea fans from Caribbean and Brazilian reefs. Although known for more than a century, there was an uncertainty regarding on how many species comprised the group or in which family they should be placed. Herein, based on morphological and molecular evidence, we review the species of the genus and reconstruct the recent evolutionary history, concluding that eight species are valid, one of which is new. Our analyses also illustrate the need to establish a family for these corals, called Plexaurellidae. [ABSTRACT FROM AUTHOR]

Quantifying recruitment of corals is important for evaluating their capacity to recover after disturbances through natural processes, yet measuring recruitment rates in situ is challenging due to the minute size of the study organism and the complexity of benthic communities. Settlement tiles are widely used in studies of coral recruitment because they can be viewed under a microscope to enhance accuracy, but methodological choices such as the rugosity of tiles used and when and how to scan tiles for recruits post-collection may cause inconsistencies in measured recruitment rates. We deployed 2,880 tiles with matching rugosity on top and bottom surfaces to 30 sites along the Florida Reef Tract for year-long saturations during a three year study. We scanned the top and bottom surfaces of the same tiles for scleractinian recruits before (live scans) and after treating tiles with sodium hypochlorite (corallite scans). Recruit counts were higher in corallite than live scans, indicating that scleractinian recruitment rates should not be directly compared between studies using live scans and those scanning tiles which have been processed to remove fouling material. Recruit counts also were higher on tile tops in general, but the proportion of settlement to the top and bottom surfaces varied significantly by scleractinian family. Thus, biases may be introduced in recruitment datasets by differences in tile rugosity or by only scanning a subset of tile surfaces. Finally, we quantified octocoral recruitment during live scans and found they preferentially settled to tile tops. We recommend that recruitment tile studies include corallite scans for scleractinian skeletons, deploy tiles with matching rugosity on top and bottom surfaces, and scan all tile surfaces. [ABSTRACT FROM AUTHOR]

Background: Chitin ranks as the most abundant polysaccharide in the oceans yet knowledge of shifts in structure and diversity of chitin-degrading communities across marine niches is scarce. Here, we integrate cultivation-dependent and -independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater. Results: We found that cultivatable host-associated bacteria in the genera Aquimarina, Enterovibrio, Microbulbifer, Pseudoalteromonas, Shewanella, and Vibrio were able to degrade colloidal chitin in vitro. Congruent with enzymatic activity bioassays, genome-wide inspection of cultivated symbionts revealed that Vibrio and Aquimarina species, particularly, possess several endo- and exo-chitinase-encoding genes underlying their ability to cleave the large chitin polymer into oligomers and dimers. Conversely, Alphaproteobacteria species were found to specialize in the utilization of the chitin monomer N-acetylglucosamine more often. Phylogenetic assessments uncovered a high degree of within-genome diversification of multiple, full-length endo-chitinase genes for Aquimarina and Vibrio strains, suggestive of a versatile chitin catabolism aptitude. We then analyzed the abundance distributions of chitin metabolism-related genes across 30 Illumina-sequenced microbial metagenomes and found that the endosymbiotic consortium of Spongia officinalis is enriched in polysaccharide deacetylases, suggesting the ability of the marine sponge microbiome to convert chitin into its deacetylated—and biotechnologically versatile—form chitosan. Instead, the abundance of endo-chitinase and chitin-binding protein-encoding genes in healthy octocorals leveled up with those from the surrounding environment but was found to be depleted in necrotic octocoral tissue. Using cultivation-independent, taxonomic assignments of endo-chitinase encoding genes, we unveiled previously unsuspected richness and divergent structures of chitinolytic communities across host-associated and free-living biotopes, revealing putative roles for uncultivated Gammaproteobacteria and Chloroflexi symbionts in chitin processing within sessile marine invertebrates. Conclusions: Our findings suggest that differential chitin degradation pathways, utilization, and turnover dictate the processing of chitin across marine micro-niches and support the hypothesis that inter-species cross-feeding could facilitate the co-existence of chitin utilizers within marine invertebrate microbiomes. We further identified chitin metabolism functions which may serve as indicators of microbiome integrity/dysbiosis in corals and reveal putative novel chitinolytic enzymes in the genus Aquimarina that may find applications in the blue biotechnology sector. 4kjGuZRPCftKy_HwBHqQX8 Video abstract [ABSTRACT FROM AUTHOR]

Octocorals are relatively understudied than other coral reef organisms despite their ecological and economic values. The Philippines is known to have high marine biodiversity, but information on octocorals is lacking. This study investigated spatial and temporal variations in the assemblage of octocorals in selected reef sites in the West Philippine Sea (WPS)- the Kalayaan Island Group (i.e., Pag-asa, Sabina, Lawak, and Northeast Investigator) and Ulugan in 2017 and 2019. Results showed high octocoral taxonomic richness (at least 10 families) in the study sites. Mean percent octocoral cover in WPS was 5.35% SE ± 0.55, with Sabina having the highest octocoral cover in both years. Significant differences in octocoral cover were observed among sites in both years, but among-station differences were only observed in 2017. Octocoral assemblage also differed among sites in both years (ANOSIM: R > 0.5, p < 0.05), wherein different octocoral taxa dominated in different sites. In particular, variations were driven by high cover of holaxonians, nephtheids, and coelogorgiids in Sabina, and clavulariids, tubiporiids, and xeniids in Northeast Investigator in 2017. In 2019, significant variations were driven by high cover of helioporiids in Pag-asa, while Sabina had higher abundance of holaxonians, nephtheids, alcyoniids, and xeniids. Short-term temporal variation on octocoral cover in monitoring stations in Pag-asa was not observed (Kruskal-Wallis, p > 0.05), although the overall mean octocoral cover increased from 1.23% ± SE 0.47 in 2017 to 2.09% SE ± 0.37 in 2019. Further, there was no significant change in the octocoral assemblage in Pag-asa between years (ANOSIM, R = 0.11, p = 0.07). This study highlights high octocoral taxonomic richness in the WPS relative to other sites in the Indo-Pacific Region and provides baseline information on the octocoral assemblages, which can be useful for future ecological studies and marine biodiversity conservation efforts.

Quantifying recruitment of corals is important for evaluating their capacity to recover after disturbances through natural processes, yet measuring recruitment rates in situ is challenging due to the minute size of the study organism and the complexity of benthic communities. Settlement tiles are widely used in studies of coral recruitment because they can be viewed under a microscope to enhance accuracy, but methodological choices such as the rugosity of tiles used and when and how to scan tiles for recruits post-collection may cause inconsistencies in measured recruitment rates. We deployed 2,880 tiles with matching rugosity on top and bottom surfaces to 30 sites along the Florida Reef Tract for year-long saturations during a three year study. We scanned the top and bottom surfaces of the same tiles for scleractinian recruits before (live scans) and after treating tiles with sodium hypochlorite (corallite scans). Recruit counts were higher in corallite than live scans, indicating that scleractinian recruitment rates should not be directly compared between studies using live scans and those scanning tiles which have been processed to remove fouling material. Recruit counts also were higher on tile tops in general, but the proportion of settlement to the top and bottom surfaces varied significantly by scleractinian family. Thus, biases may be introduced in recruitment datasets by differences in tile rugosity or by only scanning a subset of tile surfaces. Finally, we quantified octocoral recruitment during live scans and found they preferentially settled to tile tops. We recommend that recruitment tile studies include corallite scans for scleractinian skeletons, deploy tiles with matching rugosity on top and bottom surfaces, and scan all tile surfaces.

Fraction 5 was chromatographed with Si column chromatography (CC) using I n i -hexane-EtOAc-acetone (from 100% I n i -hexane to 100% acetone) to obtain subfractions 5A-5K. Subfraction 5D was separated by NP-HPLC using a mixture of I n i -hexane-acetone (50:1) to yield B 1 b (11.9 mg). Subfraction 5E was separated by NP-HPLC using a mixture of I n i -hexane-acetone (5:1) to yield B 4 b (23.1 mg). Fraction 10 was chromatographed with Si CC using I n i -hexane-EtOAc-acetone (from 100% I n i -hexane to 100% acetone) to obtain subfractions 10A-10L. Subfraction 10H8 was separated by NP-HPLC using a mixture of I n i -hexane-acetone (3:1) to yield B 6 b (22.0 mg) and B 7 b (1.3 mg). [Extracted from the article]

Three previously undescribed nardosinane-type sesquiterpenes (1–3), together with six known compounds (4–9) were isolated from the alcyonacean soft coral Rhytisma fulvum fulvum.2 and 3 are 13-nornardosinane, and 6,7-seco-13-nornardosinane derivatives, respectively. 2 could be an artifact due to C-6 epimerization of the known one 4. Chemical structures were elucidated based on 1 D, 2 D NMR and MS spectral data. Compounds 1-8 showed cytotoxic activity against NCI-H1299, HepG2 and MCF-7 with IC50 values between 0.0352–0.0974, 0.0717–0.3745 and 0.0341–0.1325 mM, respectively. The antibacterial activity of all isolated compounds have examined against a number of Gram-positive (Bacillus cereus, Staphylococcus aureas) and Gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas sp.) bacteria. Compounds 6 and 7 showed a high degree of inhibition against B. cereus, S. aureus and Pseudomonas sp. Interestingly, neolemnane (6) showed strong inhibition against two fungi, Aspergillus niger and Fusarium oxysporum; while 8 showed positive inhibition against Fusarium oxysporum at 150 µg/mL. [ABSTRACT FROM AUTHOR]

Soft corals (Cnidaria, Anthozoa, Octocorallia, Alcyonacea) produce internal sclerites of calcium carbonate previously shown to be composed of calcite, the most stable calcium carbonate polymorph. Here we apply multiple imaging and physical chemistry analyses to extracted and in-vivo sclerites of the abundant Red Sea soft coral, Ovabunda macrospiculata, to detail their mineralogy. We show that this species' sclerites are comprised predominantly of the less stable calcium carbonate polymorph vaterite (> 95%), with much smaller components of aragonite and calcite. Use of this mineral, which is typically considered to be metastable, by these soft corals has implications for how it is formed as well as how it will persist during the anticipated anthropogenic climate change in the coming decades. This first documentation of vaterite dominating the mineral composition of O. macrospiculata sclerites is likely just the beginning of establishing its presence in other soft corals. Vaterite is typically considered to be a metastable polymorph of calcium carbonate. While calcium carbonate structures formed within the tissues of octocorals (phylum Cnidaria), have previously been reported to be composed of the more stable polymorphs aragonite and calcite, we observed that vaterite dominates the mineralogy of sclerites of Ovabunda macrospiculata from the Red Sea. Based on electron microscopy, Raman spectroscopy, and X-ray diffraction analysis, vaterite appears to be the dominant polymorph in sclerites both in the tissue and after extraction and preservation. Although this is the first documentation of vaterite in soft coral sclerites, it likely will be found in sclerites of other related taxa as well. [Display omitted] [ABSTRACT FROM AUTHOR]

The ecological physiology of anthozoans, as well as their resistance to stressors, are strongly influenced by environmental factors and the availability of resources. The energy budget of anthozoans can vary seasonally in order to find an equilibrium between the available resources and respiration, polyp activity, growth, and reproduction processes. The variation in the biochemical composition of the animal tissues in these organisms results from a combination of the productivity processes of the water column coupled with the reproductive effort and potential starvation periods of the anthozoans. Here, the seasonal variation in the polyp activity of a slow-growing passive suspension feeder, the octocoral Alcyonium acaule, as well as their carbohydrate, protein and lipid contents, was investigated in a warm temperate environment using in-situ observations and biochemical analyses. Polyp activity exhibited a significant variability that was moderately dependent on season, while an aestivation phenomenon in A. acaule (i.e., a resting period in which the anthozoan is not capable of any polyp activity) during the warmer months is clearly observed. Carbohydrate concentrations in the coral species showed a significant increase in the late winter and spring seasons, and the lipid content increased during the spring. A higher abundance of lipids and carbohydrates coincided with a higher primary productivity in the water column, as well as with the octocoral reproduction period. In late autumn, there was a depletion of these biomolecules, with protein levels exhibiting great variability across sampling times. Complex alterations driven by climate change could affect the energy fluxes that depend on the dead or alive particles that are intercepted by marine animal forests. The obtained findings show a food shortage in late summer and autumn of the benthic suspension feeder A. acaule through the integrative descriptors of the ecophysiology of these anthozoans. This research contributes to the knowledge of energy storage capabilities in benthic suspension feeders in general, highlighting the importance of understanding the limits of resistance to starvation periods through these indicators. [ABSTRACT FROM AUTHOR]

Widespread and large populations of the non-native eastern Pacific ophiuroid brittle star Ophiothela mirabilis now occur in southeastern Florida, extending the range of this recently introduced species from southern Brazil northward to the eastern Caribbean Sea and Florida. The Florida brittle stars, representing two lineages, are epibionts on shallow (3–18 m depth), tropical/subtropical plexaurid (e.g., Eunicea spp., Muricea spp.) and gorgoniid (Antillogorgia spp.) octocorals. The scope of this study includes recent distributional records of O. mirabilis in south Florida, field abundances in relation to the cohabiting endemic ctenophore Coeloplana waltoni, behavioral observations of the ophiuroid, ctenophore and the predatory amphipod Caprella penantis, as well as a laboratory experiment testing the effects of the non-native ophiuroid on the native ctenophore. Individuals of O. mirabilis have been collected near St. Lucie Inlet, extending its northern-most range by about 110 km since 2019. Two years of field sampling have demonstrated significant declines of the native, benthic ctenophore with increasing abundances of the non-native ophiuroid. Evidence suggests that the ophiuroid is negatively affecting the abundances of the ctenophore through interference competition, greatly aided by its abrasive armature of calcareous spines, plates and hooks. This detrimental effect justifies considering O. mirabilis as an invasive species in south Florida. Sporadic and intense predation by a caprellid amphipod also probably contributes to the ctenophore's decline, but to a lesser extent than that caused by the ophiuroid. Adding to the risk of extinction of C. waltoni is its narrow requirement of living octocorals as hosts and restricted distribution in southeast Florida and the Bahamas. [ABSTRACT FROM AUTHOR]

MutS is a key component of the mismatch repair (MMR) pathway. Members of the MutS protein family are present in prokaryotes, eukaryotes, and viruses. Six MutS homologs (MSH1–6) have been identified in yeast, of which three function in nuclear MMR, while MSH1 functions in mitochondrial DNA repair. MSH proteins are believed to be well conserved in animals, except for MSH1—which is thought to be lost. Two intriguing exceptions to this general picture have been found, both in the class Anthozoa within the phylum Cnidaria. First, an ortholog of the yeast-MSH1 was reported in one hexacoral species. Second, a MutS homolog (mtMutS) has been found in the mitochondrial genome of all octocorals. To understand the origin and potential functional implications of these exceptions, we investigated the evolution of the MutS family both in Cnidaria and in animals in general. Our study confirmed the acquisition of octocoral mtMutS by horizontal gene transfer from a giant virus. Surprisingly, we identified MSH1 in all hexacorals and several sponges and placozoans. By contrast, MSH1 orthologs were lacking in other cnidarians, ctenophores, and bilaterian animals. Furthermore, while we identified MSH2 and MSH6 in nearly all animals, MSH4, MSH5, and, especially, MSH3 were missing in multiple species. Overall, our analysis revealed a dynamic evolution of the MutS family in animals, with multiple losses of MSH1, MSH3, some losses of MSH4 and MSH5, and a gain of the octocoral mtMutS. We propose that octocoral mtMutS functionally replaced MSH1 that was present in the common ancestor of Anthozoa. [ABSTRACT FROM AUTHOR]

Thouarella Gray, 1870, is one of the most speciose genera among gorgonians of the family Primnoidae (Cnidaria : Octocorallia : Anthozoa), being remarkably diverse in the Antarctic and sub-Antarctic seafloor. However, their diversity in the Southern Ocean is likely underestimated. Phylogenetic analyses of mitochondrial and nuclear DNA markers were integrated with species delimitation approaches as well as morphological colonial and polyps features and skeletal SEM examinations to describe and illustrate three new species within Thouarella , from the Weddell Sea, Southern Ocean: T. amundseni sp. nov., T. dolichoespinosa sp. nov. and T. pseudoislai sp. nov. Our species delimitation results suggest, for the first time, the potential presence of Antarctic and sub-Antarctic cryptic species of primnoids, based on the likely presence of sibling species within T. undulata and T. crenelata. With the three new species here described, the global diversity of Thouarella has increased to 41 species, 15 of which are endemic to the Antarctic and sub-Antarctic waters. Consequently, our results provide new steps for uncovering the shelf benthonic macrofauna's hidden diversity in the Southern Ocean. Finally, we recommend using an integrative taxonomic framework in this group of organisms and species delimitation approaches because the distinctions between some Thouarella species based only on a superficial examination of their macro- and micromorphological features is, in many cases, limited. The family Primnoidae includes common and diverse gorgonian lineages in the Antarctic benthic communities, where they play an essential role in structuring these habitats. However, taxonomic identifications of primnoids to the species level can be challenging. The complementary use of molecular and morphological data of dozens of primnoid colonies recovered from the Weddell Sea has allowed us to recognise new species within the primnoid genus Thouarella , providing further steps to uncover the shelf benthonic macrofauna's hidden diversity in the Southern Ocean. [ABSTRACT FROM AUTHOR]

A new species of bubblegum coral, Paragorgia papillata sp. nov., discovered from a seamount located on the Caroline Ridge at the water depth of 858 m, is studied using morphological and molecular approaches. The new gorgonian is white-colored, uniplanar with prominent autozooids, and measures about 670-mm high and 690-mm wide. The genetic distance and phylogenetic analysis showed that P. papillata sp. nov. was closely related to P. coralloides Bayer, 1993, but the former differs morphologically from the latter by its prominent calyces (diameter 2.0–4.0 mm and height 1.5–3.0 mm vs. both diameter and height about 1 mm), white cortex (vs. pink), regular 8-radiates in surface cortex (vs. mostly 8-radiate derived globular radiates) and highly ornate medullar spindles (length 185–100 µm vs. no more than 150 µm). P. papillata sp. nov. is the third known white-colored species of the genus, and the fifth species found in the tropical Western Pacific. [ABSTRACT FROM AUTHOR]

Two new species of Chrysogorgia Duchassaing & Michelotti, 1864 collected from the Caroline seamounts in the tropical Western Pacific Ocean are described. Chrysogorgia pinniformis sp. nov. belongs to Versluys' group C (Squamosae typicae) with only scales in polyp body wall and tentacles. C. pinniformis sp. nov. is characterized by large branches pinnately branched and forming multiple fans with its small branches regularly and quasi-dichotomous branched, and scales and rods present in the polyp mouth area. It is most similar to C. pinnata Cairns, 2007 by the pinnate trait, but differs from the latter by its group C pattern (vs. group A, Spiculosae) and having sclerites present in the polyp mouth area (vs. absent). Chrysogorgia varians sp. nov. belongs to the Chrysogorgia group A (Spiculosae) with rods distributed in the polyp body wall and tentacles. It is characterized by warty rods and elongated scales in the tentacles, many warts and ridges on the scales, conspicuously toothed margins at the rounded ends in the pinnules, and small rods with ridge-like warts in the polyp mouth area. This species was frequent and abundant in the Caroline seamounts during our cruises and its morphological variability in growth period was obvious. The phylogenetic analyses based on mtMutS and 28S rDNA regions supported the assignment of the new species to the genus Chrysogorgia. However, the mtMutS marker showed very limited usefulness for species delimitation and inner relationship inference of Chrysogorgia. In contrast, the 28S rDNA showed much higher level of genetic variation, and it may be a potential barcode for this genus. In the 28S rDNA trees, the two new species clustered together. Additionally, compilation of our data showed that 42 of 78 (ca. 54%) Chrysogorgia species were found in the Indo-West Pacific convergent region, indicating that this area may be a hotspot of deep-water Chrysogorgia species. [ABSTRACT FROM AUTHOR]

The monotypic soft coral genus Stragulum van Ofwegen and Haddad, 2011 (Octocorallia: Malacalcyonacea: Tubiporidae) was originally described from Brazil, southwest Atlantic Ocean. Here, we report the first records of the genus from the eastern Caribbean and the Persian Gulf in the northwest Indian Ocean. We compare the morphological features of specimens, together with molecular data from three commonly used barcoding markers (COI, mtMutS, 28S rDNA) and 308 ultraconserved elements (UCE) and exon loci sequenced using a target-enrichment approach. The molecular and morphological data together suggest that specimens from all three localities are the same species, i.e., Stragulum bicolor van Ofwegen and Haddad, 2011. It is still not possible to establish the native range of the species or determine whether it may be an introduced species due to the limited number of specimens included in this study. However, the lack of historical records, its fouling abilities on artificial substrates, and a growing number of observations support the invasive nature of the species in Brazilian and Caribbean waters and therefore suggest that it may have been introduced into the Atlantic from elsewhere. Interestingly, the species has not shown any invasive behaviour in the Persian Gulf, where it has been found only on natural, rocky substrates. The aim of the present report is to create awareness of this taxon with the hope that this will lead to new records from other localities and help to establish its native range.

Marine invertebrates harbour a complex suite of bacterial and archaeal symbionts, a subset of which are probably linked to host health and homeostasis. Within a complex microbiome it can be difficult to tease apart beneficial or parasitic symbionts from nonessential commensal or transient microorganisms; however, one approach is to detect strong cophylogenetic patterns between microbial lineages and their respective hosts. We employed the Procrustean approach to cophylogeny (PACo) on 16S rRNA gene derived microbial community profiles paired with COI, 18S rRNA and ITS1 host phylogenies. Second, we undertook a network analysis to identify groups of microbes that were co‐occurring within our host species. Across 12 coral, 10 octocoral and five sponge species, each host group and their core microbiota (50% prevalence within host species replicates) had a significant fit to the cophylogenetic model. Independent assessment of each microbial genus and family found that bacteria and archaea affiliated to Endozoicomonadaceae, Spirochaetaceae and Nitrosopumilaceae have the strongest cophylogenetic signals. Further, local Moran's I measure of spatial autocorrelation identified 14 ASVs, including Endozoicomonadaceae and Spirochaetaceae, whose distributions were significantly clustered by host phylogeny. Four co‐occurring subnetworks were identified, each of which was dominant in a different host group. Endozoicomonadaceae and Spirochaetaceae ASVs were abundant among the subnetworks, particularly one subnetwork that was exclusively comprised of these two bacterial families and dominated the octocoral microbiota. Our results disentangle key microbial interactions that occur within complex microbiomes and reveal long‐standing, essential microbial symbioses in coral reef invertebrates. [ABSTRACT FROM AUTHOR]

The octocoral research in Chile has been concentrated along the Patagonian coast; there are few reports about octocoral taxa living north of the fjord region. Although some species have been recorded and collected, the taxonomy is not clear and is in need of reappraisal. Herein we revisit the genus Phycogorgia. The original type material of the monospecific genus Phycogorgia was analysed in this study. Additional material was collected along the Chilean coast, and information on geographic distribution gathered, which reflects the limited biogeographic distribution of this genus throughout the eastern Pacific Ocean. Phycogorgia fucata is characterized by having conspicuous frondose, leaf-like branches which are wide, and strongly flattened; the axes are flat and expanded with carbonate hydroxylapatite mineralized fibres in the central core; the polyps are totally retractile in the coenenchyme in low polyp-mounds; the sclerites are basically capstans, and spindles. The species is re-described and a paratype is designated from the original type material of Valenciennes, establishing the species name correctly following the International Code of Zoological Nomenclature regulations. Phycogorgia fucata was found along the Chilean coast from Concepción to Valdivia, 29–40°S, biogeographically called the Intermediate Area, showing colony morphological variation. [ABSTRACT FROM AUTHOR]

Deep-sea octocorals are common habitat-formers in deep-sea ecosystems, however, our knowledge on their early life history stages is extremely limited. The present study focuses on the early life history of the species Dentomuricea aff. meteor, a common deep-sea octocoral in the Azores. The objective was to describe the embryo and larval biology of the target species under two temperature regimes, corresponding to the minimum and maximum temperatures in its natural environment during the spawning season. At temperature of 13 ±0.5 °C, embryos of the species reached the planula stage after 96h and displayed a median survival of 11 days. Planulae displayed swimming only after stimulation, swimming speed was 0.24 ±0.16 mm s−1 and increased slightly but significantly with time. Under a higher temperature (15 °C ±0.5 °C) embryos reached the planula stage 24 h earlier (after 72 h), displayed a median survival of 16 days and had significantly higher swimming speed (0.3 ±0.27 mm s−1). Although the differences in survival were not statistically significant, our results highlight how small changes in temperature can affect embryo and larval characteristics with potential cascading effects in larval dispersal and success. In both temperatures, settlement rates were low and metamorphosis occurred even without settlement. Such information is rarely available for deep-sea corals, although essential to achieve a better understanding of dispersal, connectivity and biogeographical patterns of benthic species. [ABSTRACT FROM AUTHOR]

Algal cover has increased and scleractinian coral cover has steadily declined over the past 40 years on Caribbean coral reefs, while octocoral abundance has increased at sites where abundances have been monitored. The effects of algal cover on recruitment may be a key component in these patterns, as upright octocoral recruits may escape competition with algae by growing above the ubiquitous algal turfs. We used laboratory and field recruitment experiments to examine impacts of algal turf on recruitment of the common, upright, and zooxanthellate Caribbean octocoral Plexaura homomalla. Laboratory recruitment rate was significantly higher in lower turf cover treatments. The survival of recruits in the field was significantly reduced by increased turf cover; for every 1% increase in turf cover, polyps died 1.3% faster. In a model parameterized by the observed field survival, polyps exposed to 100% turf cover had a 2% survival rate over 51 days, while polyps exposed to no turf cover had a 32% survival rate over the same time. We found that high densities of turf algae can significantly inhibit recruitment of octocorals. Experimentally obtained octocoral survival rates were higher than those published for Caribbean octocorals. The factors that influence recruitment are critical in understanding the dynamics of octocorals on Caribbean reefs as continuing declines in scleractinian cover may lead to more octocoral-dominated communities. [ABSTRACT FROM AUTHOR]

Emerging infectious diseases affecting marine ecosystems are increasing worldwide. Nevertheless, there are very few histopathological analyses describing the tissue damage associated with a specific disease. This makes it difficult to study the host response and to relate the findings to the isolated agent. Octocoral disease research has focused on the observation of lesions and on the identification of the potential pathogens involved. The aim of this investigation was to identify macroscopic lesions and describe histopathological findings in octocorals to determine potential causes. Fifty-five octocorals were investigated, and 18 of them had visible lesions (32.7%). Samples from the injured tissues of nine individuals of Gorgonia spp., seven individuals of Eunicea spp., one individual of Plexaurella dichotoma and one individual of Pseudopterogorgia acerosa were collected and processed for histopathological analysis. Algal and crustacean abrasions were the main causes of lesions detected in the field. Lesions with a focal distribution were present in most of the colonies, together with changes in tissue coloration. Histopathology revealed that melanization, amoebocytosis and polyp necrosis were the main reactions associated with algae and crustaceans. Histopathology allowed us to confirm the algae and crustacean involvement even when they were not macroscopically evident by the tissue damage and the associated response of these octocorals. [ABSTRACT FROM AUTHOR]

Coral reef ecosystems are under threat from the frequent and severe impacts of anthropogenic climate change, particularly rising sea surface temperatures. The effects of thermal stress may be ameliorated by adaptation and/or acclimation of the host, symbiont, or holobiont (host + symbiont) to increased temperatures. We examined the role of the symbiont in promoting thermal tolerance of the holobiont, using Antillogorgia bipinnata (octocoral host) and Breviolum antillogorgium (symbiont) as a model system. We identified five distinct genotypes of B. antillogorgium from symbiont populations isolated from Antillogorgia colonies in the Florida Keys. Three symbiont genotypes were cultured and maintained at 26 °C (ambient historical temperature), and two were cultured and maintained at 30 °C (elevated historical temperature) for 2 yrs. We analyzed the growth rate and carrying capacity of each symbiont genotype at both ambient and elevated temperatures in culture (in vitro). All genotypes grew well at both temperatures, indicating that thermal tolerance exists among these B. antillogorgium cultures. However, a history of long-term growth at 30 °C did not yield better performance for B. antillogorgium at 30 °C (as compared to 26 °C), suggesting that prior culturing at the elevated temperature did not result in increased thermal tolerance. We then inoculated juvenile A. bipinnata polyps with each of the five symbiont genotypes and reared these polyps at both ambient and elevated temperatures (in hospite experiment). All genotypes established symbioses with polyps in both temperature treatments. Survivorship of polyps at 30 °C was significantly lower than survivorship at 26 °C, but all treatments had surviving polyps at 56 d post-infection. Our results suggest broad thermal tolerance in B. antillogorgium, which may play a part in the increased resilience of Caribbean octocorals during heat stress events. [ABSTRACT FROM AUTHOR]

The unusual findings of Lower and Middle Ordovician tiny sclerite-type elements in the San Juan Formation of the Argentine Precordillera are described and analysed. The well-preserved silicified and phosphatized association consists of spindle-shaped morphotypes, ornamented with small regular granules or tubercles with some elements connected by their tips in a linear manner. Some morphologic characteristics of these mostly fused or connected sclerite-type elements are present in the alcyonacean octocorals. Their affinities with sponge spicules are also discussed. The oldest records of alcyonacean sclerites have been dated as late Llandovery to late Wenlock (Silurian). The discovery of possible octocoral skeletal elements in the Lower Ordovician of western Argentina may represent the oldest occurrence of such fundamental skeletal elements in the evolutionary history of the octocorals. Although a proper group assignment is still speculative at this state of knowledge, there is an implication that these early forms could be axial skeletal elements comparable to those seen in the Scleraxonia or Calcaxonia octocorals. One new genus Catenatus and new species Catenatus argentinus are described. [ABSTRACT FROM AUTHOR]

Modern systematics integrating molecular and morphological data has greatly improved our understanding of coral evolutionary relationships during the last two decades and led to a deeply revised taxonomy of the order Scleractinia. The family Merulinidae (Cnidaria: Scleractinia) was recently subjected to a series of revisions following this integrated approach but the phylogenetic affinities of several genera ascribed to it remain unknown. Here, we partially fill this gap through the study of 89 specimens belonging to all 10 valid species from four genera (Caulastraea, Erythrastrea, Oulophyllia and Dipsastraea) collected from 14 localities across the Indo‐Pacific realm. Four molecular loci (histone H3, COI, ITS and IGR) were sequenced, and a total of 44 skeletal morphological characters (macromorphology, micromorphology and microstructure) were analysed. Molecular phylogenetic analyses revealed that the phaceloid Caulastraea species are split into two distinct lineages. A species previously ascribed to the genus Dipsastraea, Dipsastraea maxima, is also recovered in one on these lineages. Furthermore, Erythrastrea is nested within Oulophyllia. The molecular reconstructions of evolutionary relationships are further corroborated by multiscale morphological evidence. To resolve the taxonomy of these genera, Astraeosmilia is resurrected to accommodate Astraeosmilia connata, Astraeosmilia curvata, Astraeosmiliatumida and Astraeosmilia maxima, with Caulastraea retaining Caulastraeafurcata and Caulastraeaechinulata. Based on the examination of type material, Erythrastrea flabellata is considered an objective synonym of Lobophyllia wellsi, which is transferred to Oulophyllia following the obtained morpho‐molecular results. This work further confirms that an integrated morpho‐molecular approach based on a rigorous phylogenetic framework is fundamental for an objective classification that reflects the evolutionary history of scleractinian corals. [ABSTRACT FROM AUTHOR]

Recent anecdotal reports from seafood processors in eastern Australia have described an increased occurrence of post-mortem myoliquefaction ('jellymeat') in broadbill swordfish Xiphias gladius, and macroscopic cysts throughout the musculature of yellowfin tuna Thunnus albacares. A genus of parasitic cnidarians, Kudoa (Myxosporea, Multivalvulida), species of which are known to occur in economically important wild-caught fish species globally, can cause similar quality-deterioration issues. However, Kudoa sp. epizootiology within commercially harvested, high-value fish caught within Australia is poorly understood, despite the parasite's economic importance. To determine the causative agent responsible for the observed quality deterioration in swordfish and yellowfin tuna, muscle-tissue samples from seafood processors in Mooloolaba, Australia, collected from October 2019–February 2020, were examined for parasitic infection. Kudoid myxospores were identified from both hosts and were subquadrate in shape, with four equal-sized polar capsules. The SSU rDNA sequences from both fish shared > 99% identity to Kudoa species. Kudoa musculoliquefaciens was isolated from 87.1% of swordfish sampled, suggesting that it is a widespread parasite in swordfish from the southwest Pacific Ocean. This study provides the first molecular and morphological characterisation of Kudoa thunni in yellowfin tuna and K. musculoliquefaciens in swordfish harvested from the waters of eastern Australia, expanding the geographical distribution of K. thunni and K. musculoliquefaciens to include the Coral and Tasman Seas. We demonstrate that not all infected swordfish progress to jellymeat, show the usefulness of molecular tools for reliably identifying infection by Kudoa spp., and add to the overall knowledge of kudoid epizootiology in wild-caught fish. [ABSTRACT FROM AUTHOR]

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.] [ABSTRACT FROM AUTHOR]

Patterns of population biology and community structure can be studied by looking closely at the ontogeny and reproductive biology of reef‐building organisms. This knowledge is particularly important for Caribbean octocorals, which seem to be more resilient to long‐term environmental change than scleractinian corals and provide some of the same ecological services. We monitored the development of the black sea rod, Plexaura homomalla, a common, widely distributed octocoral on shallow Caribbean reefs, from eggs to three‐polyp colonies over the course of 10 weeks. Gametes were collected ex situ on St. John, U.S. Virgin Islands, during spawning events that occurred 3–6 days after the July full moon. Cleavage started 3.0 hr after fertilization and was holoblastic, equal, and radial. Embryos were positively buoyant until becoming planulae at 3 days after fertilization. Planulae were competent to settle 4 days after fertilization. Symbiodiniaceae began infecting polyps ~8 days after fertilization. Overall, development was typical for Caribbean octocorals, except for an increase in the number of embryos between 3.5 and 6.0 hr after fertilization. [ABSTRACT FROM AUTHOR]

Golden corals (chrysogorgiids sensu lato) are conspicuous components in deep-sea gorgonian assemblages. Although common, their taxonomy still conflicts with evolutionary histories, mostly due to low character availability and poor taxonomic knowledge. This is the case for the genus Pleurogorgia , which has been frequently reported in ROV surveys, dominating hard-bottoms throughout the Indo-Pacific. Herein, molecular phylogenetic reconstructions based on mitochondrial and nuclear datasets, and examination of new and old type material led us to suggest new systematic arrangements for some of the genera. We create a new genus, Ramuligorgia , to accommodate Pleurogorgia militaris , redescribing it as Ramuligorgia militaris comb. nov. within the family Chrysogorgiidae sensu stricto. Additionally, we describe Aurogorgia tasmaniensis gen. nov. et sp. nov., including it and the type species, Pleurogorgia plana , within Pleurogorgiidae fam. nov. [ABSTRACT FROM AUTHOR]

Telestula humilis (Thomson, 1927) is a rare deep-sea stoloniferan octocoral distributed in the eastern Atlantic. Here we compared seven putative colonies of this species collected off Spain with the lectotype from the Oceanographic Museum of Monaco and found them to be identical morphologically. Phylogenetic analyses on both full mitogenomes and a concatenated alignment containing two mtDNA genes (mtMutS and Cox1) and nuclear 28S rRNA gene recovered Telestula humilis sister to Incrustatus and Inconstantia rather than to other species of Telestula. This therefore supports its taxonomic reassignment to Pseudotelestula gen. nov. as Pseudotelestula humilis comb. nov. The taxonomic reassignment is also supported by subtle differences observed between the morphology of the colony and the sclerome of Pseudotelestula humilis comb. nov. and the two sister genera. The occurrence of an intrusion tissue with sclerites in the basal part of the gastric cavity of the adult polyps is shared among Telestula and Pseudotelestula gen. nov. However, Pseudotelestula gen. nov. has sclerites arranged in a collaret and points below the tentacles, the sclerites of the calyx wall and the stolon are plump warty spindles, and the intrusion tissue has long sticks and spindles with cone-like spines. [ABSTRACT FROM AUTHOR]

Evidence‐based decisions relating to effective marine protected areas as a means of conserving biodiversity require a detailed understanding of the species present. The Caribbean island nation of St Lucia is expanding its current marine protected area network by designating additional no‐take marine reserves on the west coast. However, information on the distribution of fish species is currently limited.This study used baited remote underwater stereo‐video to address this shortcoming by investigating the effects of depth and seabed habitat structure on demersal fish assemblages and comparing these assemblages between regions currently afforded different protection measures.From the 87 stations visited a total of 5,921 fish were observed comprising 120 fish taxa across 22 families. Species richness and total abundance were higher within the highly managed region, which included no‐take reserves. Redundancy analysis explained 17% of the total variance in fish distribution, driven predominantly by the seabed habitats. The redundancy analysis identified four main groups of demersal fishes each associated with specific seabed habitats.The current no‐take marine reserves protected two of these groups (i.e. fishes associated with the 'soft corals, hard corals or gorgonians' and 'seagrass' groups). Importantly, habitats dominated by sponges, bacterial mats, algal turfs or macroalgae, which also supported unique fish assemblages, are not currently afforded protection via the marine reserve network (based on the five reserves studied). These results imply that incorporation of the full breadth of benthic habitat types present would improve the efficacy of the marine reserve network by ensuring all fish assemblages are protected. [ABSTRACT FROM AUTHOR]

Bottom trawling significantly impacts benthic communities, reducing habitat complexity and biodiversity. The distribution and abundance of key species in the northeastern Gulf of Cádiz, Spanish waters of Atlantic Ocean, such as soft-bottom octocorals and burrowing megafauna, were examined using video observations and Spatial Distribution Models developed with Random Forest. The study was conducted in the Site of Community Importance " Volcanes de fango del golfo de Cádiz " focusing on depths between 300 and 950 metres depth. The effects of environmental variables and bottom trawling on octocoral distribution and abundance were assessed, and management strategies for habitat protection were proposed. Bottom trawling was found to decrease habitat suitability for large octocoral species while the abundance of Norway lobster was positively correlated with certain values of bottom trawling effort. The study suggests that bottom trawling causes significant reduction in octocoral distributions, substrate homogenization, and habitat differentiation. A 200 km2 area is recommended for a specific bottom trawling regulation to protect soft-bottom octocorals and support the recovery of commercial burrowing megafauna. • Soft-bottom octocorals and Nephrops norvegicus distributions were examined using video and Spatial Distribution Models. • Bottom trawling was found to decrease habitat suitability for large octocoral species. • N. norvegicus exhibit high densities in mud and trawling effort apparently does not significantly impact their density. • N. norvegicus abundance predictions was positively correlated with certain values of fishing effort. • A 200 km2 area is recommended for a specific bottom trawling regulation to protect soft-bottom octocorals. [ABSTRACT FROM AUTHOR]

Gorgonian octocorals are threatened by global and local stressors that can act synergistically to affect their health. In recent years, mass mortality events triggered by marine heatwaves have caused demographic declines in Mediterranean gorgonian populations that may lead to their collapse. Potential changes in microbiome composition under stressful conditions may further increase the susceptibility of the gorgonian holobiont to disease. Given the low recovery capacity of gorgonians, restoration approaches using transplantation are becoming an increasingly attractive option to counteract their decline. Here, we compared the survival and microbiome diversity of Paramuricea clavata colonies transplanted to sites differing in depth and local environmental conditions. Gorgonians sampled at a greater depth than the transplantation site were more likely to suffer necrosis after 1 year of monitoring. Gorgonian transplantation into environments disturbed by an anthropogenic source of pollution resulted in an imbalance of the microbiome with potential consequences on the success of restoration initiatives. • Necrosis and survival rates vary by site of origin and site of transplantation. • Transplantation can affect the composition and variability of the microbiome. • Dysbiosis of transplants is associated with colonisation by pathogenic bacteria. [ABSTRACT FROM AUTHOR]

In this study, the complete mitochondrial genome (mitogenome) of Sinularia humilis van Ofwegen, 2008 was determined using next-generation sequencing (NGS) method. The mitogenome of S. humilis is 18,743 bp in length, containing 14 protein-coding genes (PCGs), two ribosomal RNAs (rRNA) and one tRNA (tRNA-Met), which has same gene order with other species of Sinularia. ATG was determined as start codon in all 14 PCGs. Eight TAG, five TAA, and one incomplete codons (T-) were found as stop codon. Phylogenetic analysis of the small number of available mitogenomes showed that S. humilis is closely related to Sinularia ceramensis and Sinularia peculiaris. [ABSTRACT FROM AUTHOR]

This paper presents the first record of Viminella Gray 1870 from the Persian Gulf. This genus has a global distribution and its largest distribution is in the Indo-Pacific region. A single specimen was collected by a local fisherman from south Hengam Island (the north Persian Gulf) from 60-70 m depth. Colony morphology characteristics were examined by stereomicroscope and optical microscope. Descriptions of the colony and other taxonomic characteristics are provided. The colony is unbranched with a height of 12 cm and its basal diameter is approximately 1.63 mm. The sclerites of the coenenchyme comprise a variety of symmetrical double heads and capstan-like forms (0.05-0.11 mm). In the wall of calyces, slightly elongated double heads, capstans and spindles (about 0.08-0.19 mm) are present. Our finding extends the known geographical distribution of this genus in the Indo-Pacific region to the Persian Gulf.