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Coral reef ecosystems in Indonesia are under threat due to changes in the environment driven by global climate change, along with local disturbances such as sedimentation and eutrophication. Consequently, comprehensive coral reef monitoring activities have been initiated at numerous locations across Indonesia. In this study, the findings from coral reef health surveys across 14 reef sites (within 40 hectares) in the Bintan area (Riau Archipelago, Indonesia; 100 km southeast of Singapore) revealed a potentially novel epizoic yellow sponge species (Phorbas sp.) that overgrows coral colonies. This species, tentatively classified as a new Phorbas sp. (order Poecilosclerida: family Hymedesmiidae), was identified through a combined approach employing classical taxonomic methods along with DNA barcoding using the cytochrome c oxidase I (COI) gene. At every site, three permanent 20‐m transects were established to annually monitor live coral coverage and species composition between 2014 and 2017. The survey indicated a notable change in the overall coral cover during this period. The abundance of coral diseases was investigated in 2014 and 2017. Additionally, the progress of Phorbas sp., was closely monitored (i.e., every second day for one week) at Bintan Island (site 11) during the dry season in August 2017. This approach aimed to approximate the relative impact of each incident on the coral's condition. The results indicated that the most comprehensive change occurred due to the overgrowth of Phorbas sp., which affected 12 scleractinian coral species across eight genera in almost all sites except one. The abundance of this epizoic sponge infestation was highest at Pulau Beralas Pasir (site 10), constituting 22.9% of all recorded life forms, and lowest at Pulau Pangkil‐Besar (site 13), with only 0.7%. The expansion of the thin yellow sponge tissue was estimated to increase by up to 0.51 ± 0.48 cm2 per day on Porites coral. [ABSTRACT FROM AUTHOR]

Understanding the maintenance and origin of beta diversity is a central topic in ecology. However, the factors that drive diversity patterns and underlying processes remain unclear, particularly for host‐prokaryotic associations. Here, beta diversity patterns were studied in five prokaryotic biotopes, namely, two high microbial abundance (HMA) sponge taxa (Xestospongia spp. and Hyrtios erectus), one low microbial abundance (LMA) sponge taxon (Stylissa carteri), sediment and seawater sampled across thousands of kilometres. Using multiple regression on distance matrices (MRM), spatial (geographic distance) and environmental (sea surface temperature and chlorophyll α concentrations) variables proved significant predictors of beta diversity in all five biotopes and together explained from 54% to 82% of variation in dissimilarity of both HMA species, 27% to 43% of variation in sediment and seawater, but only 20% of variation of the LMA S. carteri. Variance partitioning was subsequently used to partition the variation into purely spatial, purely environmental and spatially‐structured environmental components. The amount of variation in dissimilarity explained by the purely spatial component was lowest for S. carteri at 11% and highest for H. erectus at 55%. The purely environmental component, in turn, only explained from 0.15% to 2.83% of variation in all biotopes. In addition to spatial and environmental variables, a matrix of genetic differences between pairs of sponge individuals also proved a significant predictor of variation in prokaryotic dissimilarity of the Xestospongia species complex. We discuss the implications of these results for the HMA‐LMA dichotomy and compare the MRM results with results obtained using constrained ordination and zeta diversity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Seven new kalihinene diterpenoids, kalihioxepanes A—G (1—7) bearing a rare oxepane ring, were isolated from sponge Acanthella cavernosa collected from the South China Sea. The structures and absolute configurations were elucidated by comprehensive spectroscopic analysis, single crystal X‐ray diffraction, and quantum chemical calculation methods. Kalihioxepane A (1) displayed strong cytotoxicity against H69 and K562 tumor cells, while kalihioxepane B (2) showed moderate cytotoxicity against K562 cells. [ABSTRACT FROM AUTHOR]

Chemical examination of the Chinese marine sponge Xestospongia testudinaria resulted in the isolation and characterization of twelve new brominated acetylenic acids, namely xestospongienols A-L ( 1a- 1d, 2a- 2d, and 3a- 3d), together with the known analog 4. The structures of xestospongienols A-L were determined on the basis of 1D- and 2D-NMR, IR, and MS analysis in association with the modified Mosher method. The structural patterns are characteristic of brominated unbranched C16-alkyl chains containing polyene and acetylene moieties. [ABSTRACT FROM AUTHOR]

Botanical and zoological collections may serve as archives for historical ecological research on the effects of global change and human impact on coral reef biota. Museum collections may harbour old specimens of reef-dwelling species that have become locally extinct. Such collections also help to determine whether early records of invasive species can be obtained from times when they were not yet recognized as such. A case study (2006) involving Saba Bank, Caribbean Netherlands (former Netherlands Antilles), suggests that the coral reef fauna here may have become impoverished when compared with data obtained during an earlier expedition in 1972. However, the 1972 sampling may have been incomplete, as it was performed by professional divers who were not trained taxonomists, whereas the collecting in 2006 was done by experienced marine biologists who knew the taxa they were sampling. As Saba Bank has been under stress due to the anchoring of large vessels, and invasive species have been a potential threat as well, future studies are needed to obtain more insights into the changing reef biota of Saba Bank. Using this Saba Bank example, we want to address the importance of natural history collections as reservoirs of valuable data relevant to coral reef biodiversity studies in a time of global change. As such, these collections are still underexplored and underexploited. [ABSTRACT FROM AUTHOR]

Very few coral reefs are located close enough to large cities to study the influence of large urban populations on reef assemblages. An exception is the Thousand Islands reef complex to the north of Jakarta, the capital city of Indonesia, and one of the largest conurbations in the world. Here we present data from a detailed survey where sponge assemblages were assessed at 30 patch reefs associated with islands in three coastal zones along an in-to-offshore gradient. Sponge assemblages are described at three taxonomic levels of detail (species, genus and family level). We recorded a total of 118 sponge species, 64 genera and 36 families, Aaptos suberitoides (Brønsted, 1934), Clathria (Thalysias) reinwardti (Vosmaer, 1880), Petrosia (Petrosia) nigricans (Lindgren, 1897) and Xestospongia testudinaria (Lamarck, 1813) were the most common species overall. There was a pronounced difference in composition among zones with the most distinct difference between the inshore zone and the other two zones. The inshore environment was characterised by very high turbidity and low live coral cover; the dominant substrate consisted of algal turf and sand. Environmental conditions improved and sponge diversity increased further offshore, although most areas appeared to have been affected by some form of disturbance. Ordinations were also largely congruent, at species, generic and family levels of taxonomic resolution. This indicates that variation in composition at higher taxonomic levels is a good indicator of variation at lower taxonomic levels, at least when there is a pronounced environmental gradient. [ABSTRACT FROM AUTHOR]

In order to preserve diversity it is essential to understand how assemblages change across space. Despite this fact, we still know very little about how marine diversity is spatially distributed, especially among lesser-studied invertebrate taxa. In the present study beta-diversity patterns of sea urchins, sponges, mushroom corals and larger foraminifera were assessed in the Spermonde Archipelago (Indonesia). Using ordinations we showed that the inshore zone (<5 km offshore), midshore zone (5 < x < 30 km offshore) and distance offshore zone (>30 km offshore) all contained distinct assemblages of sponges and corals, while only foraminifera assemblages from the inshore (<5 km offshore) zone were distinct. There was a significant spatial pattern of community similarity for all taxa surveyed, but this pattern proved to be wholly related to environmental variables for sponges and foraminifera, and primarily for mushroom corals and sea urchins. The lack of a pure spatial component suggests that these taxa may not be dispersal limited within the spatial scales of this study ( c. 1600 km2). The analyses of the corals and foraminifera were additionally tested at two spatial scales of sampling. Both taxa were primarily associated with local-scale environmental variables at the local scale and larger-scale variables at the larger scale. Mean inter-plot similarity was also higher and variation lower at the larger scale. The results suggest that substantial variation in similarity can be predicted using simple locally assessed environmental variables combined with remotely sensed parameters. [ABSTRACT FROM AUTHOR]

Marine sponges are known to host diverse and abundant communities of microbial symbionts. It has been generally assumed that the bacterial communities of low microbial abundance (LMA) sponges are less diverse than those of high microbial abundance (HMA) sponges. In this study, we used next‐generation sequencing technology to explore the bacterial communities of several biotopes including sponges, seawater, and sediment from the remote Western Indian Ocean island of Mayotte. The species investigated were the known LMA sponges: Jaspis splendens, Stylissa carteri, and Stylissa massa, and the known HMA sponges: Hyrtios erectus and Xestospongia testudinaria. In addition to this, we also investigated the following sponge species: Ectyoplasia coccinea, Paratetilla bacca,Liosina paradoxa, and Petrosia aff. spheroida of which the exact HMA/LMA status is unknown although we preliminarily classified them as HMA or LMA based on the status of closely related species. Certain HMA sponges shared similar bacterial communities dominated by Actinobacteria and Chloroflexi, whereas another species (E. coccinea) had a bacterial community closer to that of LMA sponges. Most LMA sponges housed a bacteriome dominated by Proteobacteria and Cyanobacteria, but the bacteriome of P. bacca also included dominant Chloroflexi and actinobacterial OTUs. Together with S. carteri, this sponge housed a more diverse bacterial community at the phylum, class, and order levels than HMA sponges. Although certain LMA sponges housed a bacterial community similar to the surrounding environment (seawater), they also included highly abundant, possibly species or genus specific, OTUs. Based on this study and small set of sponges studied, we conclude that a clear dichotomy between HMA and LMA sponges does not appear to exist. [ABSTRACT FROM AUTHOR]