Mass mortality event of the giant barrel sponge Xestospongia sp.: population dynamics and size distribution in Koh Phangan, Gulf of Thailand.

Marine sponges are prominent organisms of the benthic coral reef fauna, providing important ecosystem services. While there have been increasing reports that sponges are becoming one of the dominant benthic organisms in some locations and ecoregions (e.g. Caribbean), they can be impacted by changing environmental conditions. This study presents the first documentation of a mass mortality event of the barrel sponge Xestospongia sp. in the lower Gulf of Thailand and its consequences on population dynamics and size distribution. Two anthropogenic impacted reefs (Haad Khom and Mae Haad) of the island Koh Phangan and two anthropogenic non-impacted reefs of the islands Koh Yippon and Hin Yippon within the Mu Ko Ang Thong Marine National Park were surveyed in the years 2015 and 2016. The results showed a strong shift in population densities at Koh Phangan. Fatal "bleaching" ending up in mass mortality was observed for these reefs in 2015. Xestospongia sp. abundance decreased from 2015 to 2016 by 80.6% at Haad Khom and by 98.4% at Mae Haad. Sponges of all sizes were affected, and mortality occurred regardless of the survey depth (4 and 6 m). However, Xestospongia population densities in the Marine Park were at a constant level during the surveys. The abundances in 2015 were 65% higher at the Marine Park than at Koh Phangan and 92% higher in 2016. The most likely causes of the mass mortality event was a local harmful algal bloom event, pathogens, undetected local higher water temperatures, or a combination of these factors, whereas sea surface temperature analyses showed no marine heatwave during the observed mass mortality event in 2015. Considering the ecological importance of sponges such as Xestospongia sp., long-term monitoring of reefs and their environmental parameters should be implemented to prevent such mass die-offs.

Metabolites and Bioactivity of the Marine Xestospongia Sponges (Porifera, Demospongiae, Haplosclerida) of Southeast Asian Waters.

Sponges are aquatic, spineless organisms that belong to the phylum Porifera. They come in three primary classes: Hexactinellidae, Demospongiae, and Calcarea. The Demospongiae class is the most dominant, making up over 90% of sponge species. One of the most widely studied genera within the Demospongiae class is Xestospongia, which is found across Southeast Asian waters. This genus is of particular interest due to the production of numerous primary and secondary metabolites with a wide range of biological potentials. In the current review, the antioxidant, anticancer, anti-inflammatory, antibacterial, antiviral, antiparasitic, and cytotoxic properties of metabolites from several varieties of Southeast Asian Xestospongia spp. were discussed. A total of 40 metabolites of various natures, including alkaloids, fatty acids, steroids, and quinones, were highlighted in X. bergquistia, X. testudinaria, X. muta, X. exigua, X. ashmorica and X. vansoesti. The review aimed to display the bioactivity of Xestospongia metabolites and their potential for use in the pharmaceutical sector. Further research is needed to fully understand their bioactivities.

Target Identification of 22-(4-Pyridinecarbonyl) Jorunnamycin A, a Tetrahydroisoquinoline Derivative from the Sponge Xestospongia sp., in Mediating Non-Small-Cell Lung Cancer Cell Apoptosis.

A dysregulation of the cell-death mechanism contributes to poor prognosis in lung cancer. New potent chemotherapeutic agents targeting apoptosis-deregulating molecules have been discovered. In this study, 22-(4-pyridinecarbonyl) jorunnamycin A (22-(4'py)-JA), a synthetic derivative of bistetrahydroisoquinolinequinone from the Thai blue sponge, was semisynthesized by the Steglich esterification method, and its pharmacological mechanism in non-small-cell lung cancer (NSCLC) was elucidated by a network pharmacology approach. All predicted targets of 22-(4'py)-JA and genes related to NSCLC were retrieved from drug-target and gene databases. A total of 78 core targets were identified, and their associations were analyzed by STRING and Cytoscape. Gene ontology and KEGG pathway enrichment analyses revealed that molecules in mitogen-activated protein kinase (MAPK) signaling were potential targets of 22-(4'py)-JA in the induction of NSCLC apoptosis. In silico molecular docking analysis displayed a possible interaction of ERK1/2 and MEK1 with 22-(4'py)-JA. In vitro anticancer activity showed that 22-(4'py)-JA has strong cytotoxic and apoptosis-inducing effects in H460, H292 and A549 NSCLC cells. Furthermore, immunoblotting confirmed that 22-(4'py)-JA induced apoptotic cell death in an ERK/MEK/Bcl-2-dependent manner. The present study demonstrated that 22-(4'py)-JA exhibited a potent anticancer effect that could be further developed for clinical application and showed that network pharmacology approaches are a powerful tool to illustrate the molecular pathways of new drugs or compounds.

Xestospongia muta Fraction-7 and Linoleic Acid: Effects on SR-BI Gene Expression and HDL Cholesterol Uptake.

Xestospongia muta is a marine sponge belonging to the family Petrosiidae. It is an important source of biologically active marine natural products, with different kinds of essential fatty acids. Scavenger receptor class B type I (SR-BI) is the main receptor for high-density lipoprotein (HDL) cholesterol, which plays a pivotal role in preventing atherosclerosis. It removes cholesterol from HDL cholesterol, returning lipid-poor lipoprotein into blood circulation. The present study investigated the effects of X. muta Fraction-7 and linoleic acid on SR-BI gene expression and HDL cholesterol uptake. In vitro studies of the activity of X. muta and linoleic acid against the therapeutic target for hypercholesterolemia were conducted using the HDL receptor SR-BI via luciferase assay and HepG2 cells. In the present study, Fraction-7 of X. muta showed the highest expression level of the SR-BI gene via luciferase assay. Profiling of Fraction-7 of X. muta by GC-MS revealed 58 compounds, comprising various fatty acids, particularly linoleic acid. The in vitro study in HepG2 cells showed that the Fraction-7 of X. muta and linoleic acid (an active compound in X. muta) increased SR-BI mRNA expression by 129% and 85%, respectively, compared to the negative control. Linoleic acid increased HDL uptake by 3.21-fold compared to the negative control. Thus, the Fraction-7 of X. muta and linoleic acid have the potential to be explored as adjuncts in the treatment of hypercholesterolemia to prevent or reduce the severity of atherosclerosis development.

Sponges present a core prokaryotic community stable across Tropical Western Atlantic.

Sponges are among the earliest lineages of metazoans, with first fossil records dated back to 890 million years ago. All sponge species present associations with microorganisms to some extension, which influence sponges' survival and adaptation. Sponge species can be divided into two categories, Low Microbial Abundance and High Microbial Abundance, depending on the abundance of the microbial community that they host. Monanchora arbuscula (a Low Microbial Abundance sponge species) and Xestospongia muta (a High Microbial Abundance sponge species) are sponges with widespread distribution in the Tropical Western Atlantic. Despite previous studies on the major features of these species, little is known whether M. arcuscula and X. muta prokaryotic communities are stable across vast geographic regions. We obtained a total of ~9.26 million 16S rRNA gene Illumina sequences for M. arbuscula samples collected at seven locations and for X. muta samples collected at three locations, corresponding to five ecoregions of the Caribbean and the Southwestern Atlantic (N = 105, 39 from M. arcuscula and 66 from X. muta). These samples reflected different ecological strategies for prokaryotic communities assembly, since the core prokaryotic communities of M. arbuscula are more heterotrophic and shared with different sources (corals, sponges, seawater, sediments), while X. muta has more significant photosynthetic prokaryotic communities, mainly outsourced from other sponges. Results of M. arbuscula and X. muta prokaryotic communities analysis demonstrate that both sponge species have core prokaryotic communities stable across a vast geographic area (> 8000 km), and the world's most notable coastal marine biogeographic filter, the Amazon River Mouth, in spite of the significant differences found among transient prokaryotic communities of both sponge species.

Detrimental conditions affecting Xestospongia muta across shallow and mesophotic coral reefs off the southwest coast of Puerto Rico.

Sponges are fundamental components of coral reef communities and, unfortunately, like other major benthic members, they too have been impacted by epizootic and panzootic events. We report on the prevalence of disease-like conditions affecting populations of the giant barrel sponge Xestospongia muta across shallow and mesophotic coral reefs off La Parguera Natural Reserve (LPNR) and Mona Island Marine Reserve (MIMR) in Puerto Rico. Four different conditions affecting X. muta were observed during our surveys, of which 3 have been previously reported: cyclic spotted bleaching (CSB; apparently non-lethal), Xestospongia-tissue wasting disease (X-TWD; apparently lethal), and sponge orange band disease (SOB; sparsely associated with X-TWD infected individuals). Additionally, we describe a fourth condition, Xestospongia-tissue hardening condition (X-THC), a previously unreported disease recently observed along the insular shelf margin off LPNR and MIMR. Within LPNR, a total of 764 specimens of X. muta were inspected and measured. Of these, 590 sponges (72.2%) had CSB, 25 (3.27%) had signs of X-TWD, 7 (0.92%) had SOB, and the remaining 142 (18.6%) were apparently healthy. Three colonies inhabiting upper mesophotic depths on the LPNR insular shelf showed signs of CSB and X-TWD. At MIMR, video-transect surveys revealed a total of 514 colonies, of which 40 (7.78%) had signs of CSB and/or XTWD, 14 (2.72%) were affected by X-THC, while the remaining 460 (89.5%) showed no external signs of disease and appeared healthy. The presence of 4 concomitant disease-like conditions in barrel sponges of Puerto Rico is alarming, and indicative of the deteriorating status of Caribbean coral reefs.

Metabolic variation in Caribbean giant barrel sponges: Influence of age and sea-depth.

The biochemical differentiation of widely distributed long-living marine organisms according to their age or the depth of waters in which they grow is an intriguing topic in marine biology. Especially sessile life forms, such as sponges, could be expected to actively regulate biological processes and interactions with their environment through chemical signals in a multidimensional manner. In recent years, the development of chemical profiling methods such as metabolomics provided an approach that has encouraged the investigation of the chemical interactions of these organisms. In this study, LC-MS based metabolomics followed by Feature-based molecular networking (FBMN) was used to explore the effects of both biotic and environmental factors on the metabolome of giant barrel sponges, chosen as model organisms as they are distributed throughout a wide range of sea-depths. This allowed the identification of differences in the metabolic composition of the sponges related to their age and depth.

An Efficient DNA Extraction for a Blue Xestospongia sp. Sponge and Its Associated Microorganisms Containing Cytotoxic Substances.

Extraction of high quantity and quality DNAs from marine sponges, which contain diverse and abundant microbial communities, is important to molecular biology techniques for the analysis of nucleic acids. Several marine sponges and their associated microorganisms have been known to produce cytotoxic natural products on several cancer cell lines via DNA damage mechanisms. These marine cytotoxic substances might be one of the factors that cause the low quantity and quality of DNAs during the DNA extraction from its living origin. Therefore, the extraction of DNA of a Thai blue marine sponge Xestospongia sp. with sufficient purity and quantity for molecular study can be challenging. In this study, we developed an efficient extraction method to prepare DNAs from a Thai blue marine sponge Xestospongia sp. which accumulated a highly potent cytotoxic alkaloid with DNA-damaging activity, named Renieramycin M (RM), as a major constituent in high quantity. We demonstrated that removal of RM from the sponge samples by a simple methanolic extraction before DNA extraction dramatically increased the yield and purity of DNAs compared to the RM-unremoved sponge samples. High molecular weight (HMW) genomic DNA was obtained from sponge samples with 8 times of RM elimination by using modified NaOAc salting-out extraction method. The quantity and quality of the prepared DNAs were comparatively determined via spectrophotometry, electrophoresis, and 16S rRNA gene amplification. Our result suggests that the removal of DNA-damaging constituents from the samples is a crucial step and must be seriously taken as the necessary consideration for the practical protocol of DNA extraction.

Jorunnamycin A Suppresses Stem-Like Phenotypes and Sensitizes Cisplatin-Induced Apoptosis in Cancer Stem-Like Cell-Enriched Spheroids of Human Lung Cancer Cells.

It has been recognized that cancer stem-like cells (CSCs) in tumor tissue crucially contribute to therapeutic failure, resulting in a high mortality rate in lung cancer patients. Due to their stem-like features of self-renewal and tumor formation, CSCs can lead to drug resistance and tumor recurrence. Herein, the suppressive effect of jorunnamycin A, a bistetrahydroisoquinolinequinone isolated from Thai blue sponge Xestospongia sp., on cancer spheroid initiation and self-renewal in the CSCs of human lung cancer cells is revealed. The depletion of stemness transcription factors, including Nanog, Oct-4, and Sox2 in the lung CSC-enriched population treated with jorunnamycin A (0.5 µM), resulted from the activation of GSK-3ß and the consequent downregulation of ß-catenin. Interestingly, pretreatment with jorunnamycin A at 0.5 µM for 24 h considerably sensitized lung CSCs to cisplatin-induced apoptosis, as evidenced by upregulated p53 and decreased Bcl-2 in jorunnamycin A-pretreated CSC-enriched spheroids. Moreover, the combination treatment of jorunnamycin A (0.5 µM) and cisplatin (25 µM) also diminished CD133-overexpresssing cells presented in CSC-enriched spheroids. Thus, evidence on the regulatory functions of jorunnamycin A may facilitate the development of this marine-derived compound as a novel chemotherapy agent that targets CSCs in lung cancer treatment.

A new antiplasmodial sterol from Indonesian marine sponge, Xestospongia sp.

A new antimalarial sterol, kaimanol (1), along with a known sterol, saringosterol (2) was isolated from the Indonesian Marine sponge, Xestospongia sp. The chemical structure of the new compound was determined on the basis of spectroscopic evidences and by comparison to those related compounds previously reported. Isolated compounds, 1 and 2 were evaluated for their antiplasmodial effect against Plasmodium falciparum 3D7 strains. Compounds 1 and 2 exhibited antiplasmodial activity with IC50 values of 359 and 0.250 nM, respectively.

Marine sponges Sarcotragus foetidus, Xestospongia carbonaria and Spongia obscura constituents ameliorate IL-1 ß and IL-6 in lipopolysaccharide-induced RAW 264.7 macrophages and carrageenan-induced oedema in rats.

Marine sponges are prolific producers of an array of diverse chemical structures containing compounds with multiple biological activities. In this study, whole methanol extracts and fractionated compounds from three marine sponges namely Xestospongia carbonaria, Sarcotragus foetidus and Spongia obscura were thoroughly investigated for their antibacterial, antifungal, antioxidant and anti-inflammatory activities. Methanol extracts and fractionated compounds were characterised using high performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Extracts were checked for cytotoxicity in RAW macrophages by MTT assay, before using them for the treatment study. Enzyme linked immunosorbent assay kits were used to check the effects on inflammatory mediator's levels (PGE2, COX-2, IL-6, IL-1ß, TNF-α) in vitro. The results demonstrated good anti-inflammatory activity of all the three marine sponges; X. carbonaria, S. foetidus and S. obscura suppressed the levels of anti-inflammatory cytokines in vitro. Reverse transcriptase-polymerase chain reaction confirmed the inhibition of IL-1ß and IL-6 genes expression by the isolates of X. carbonaria and S. foetidus, while reducing cytokine levels in lipopolysaccharide-induced inflammation in vitro as well as in carrageenan-induced inflammation in rats. Two semi pure compounds isolated from X. carbonaria and S. foetidus also confirmed suppression of IL-1ß and IL-6 genes expression in RAW macrophages.

Cultivation of Sponge-Associated Bacteria from Agelas sventres and Xestospongia muta Collected from Different Depths.

Sponge-associated bacteria have been mostly cultured from shallow water (≤30 m) sponges, whereas only few studies targeted specimens from below 30 m. This study assessed the cultivability of bacteria from two marine sponges Xestospongia muta and Agelas sventres collected from shallow (<30 m), upper mesophotic (30-60 m), and lower mesophotic (60-90 m) reefs. Sponge-associated bacteria were cultivated on six different media, and replicate plates were used to pick individual colonies or to recover the entire biomass. Prokaryotic community analysis was conducted using Illumina MiSeq sequencing of 16S rRNA gene amplicons. A total of 144 bacterial isolates were picked following a colony morphology coding scheme and subsequently identified by 16S rRNA gene sequence analysis. Sponge individuals at each depth-range harboured specific cultivable bacteria that were not retrieved from specimens collected at other depths. However, there were substantial differences in the number of colonies obtained for replicate sponges of the same species. In addition, source of inoculum and cultivation medium had more impact on the cultured prokaryotic community than sample collection depth. This suggests that the "plate count anomaly" is larger than differences in sponge-associated prokaryotic community composition related to depth.

Synergistic Cytotoxicity of Renieramycin M and Doxorubicin in MCF-7 Breast Cancer Cells.

Renieramycin M (RM) is a KCN-stabilized tetrahydroisoquinoline purified from the blue sponge Xestospongia sp., with nanomolar IC50s against several cancer cell lines. Our goal is to evaluate its combination effects with doxorubicin (DOX) in estrogen receptor positive MCF-7 breast cancer cells. MCF-7 cells were treated simultaneously or sequentially with various combination ratios of RM and DOX for 72 h. Cell viability was determined using the MTT assay. Synergism or antagonism was determined using curve-shift analysis, combination index method and isobologram analysis. Synergism was observed with pharmacologically achievable concentrations of DOX when administered simultaneously, but not sequentially. The IC95 values of RM and DOX after combination were reduced by up to four-fold and eight-fold, respectively. To gain insights on the mechanism of synergy, real-time profiling, cell cycle analysis, apoptosis assays, and transcriptome analysis were conducted. The combination treatment displayed a similar profile with DNA-damaging agents and induced a greater and faster cell killing. The combination treatment also showed an increase in apoptosis. DOX induced S and G2/M arrest while RM did not induce significant changes in the cell cycle. DNA replication and repair genes were downregulated commonly by RM and DOX. p53 signaling and cell cycle checkpoints were regulated by DOX while ErbB/PI3K-Akt, integrin and focal adhesion signaling were regulated by RM upon combination. Genes involved in cytochrome C release and interferon gamma signaling were regulated specifically in the combination treatment. This study serves as a basis for in vivo studies and provides a rationale for using RM in combination with other anticancer drugs.

Jorunnamycin A from Xestospongia sp. Suppresses Epithelial to Mesenchymal Transition and Sensitizes Anoikis in Human Lung Cancer Cells.

Metastasis is a key driving force behind the high mortality rate associated with lung cancer. Herein, we report the first study revealing the antimetastasis activity of jorunnamycin A, a bistetrahydroisoquinolinequinone isolated from a Thai blue sponge Xestospongia sp. evidenced by its inhibition of epithelial to mesenchymal transition (EMT), sensitization of anoikis, and suppression of anchorage-independent survival in human lung cancer cells. Treatment with jorunnamycin A (0.05-0.5 µM) altered the expression of p53 and Bcl-2 family proteins, particularly causing the down-regulation of antiapoptosis Bcl-2 and Mcl-1 proteins. Under detachment conditions for 12 h, jorunnamycin A-treated cells exhibited diminution of pro-survival proteins p-Akt and p-Erk as well as the survival-promoting factor caveolin-1. Corresponding with the inhibition on the Akt and Erk pathway as well as activation of p53, there was an increase in the epithelial marker E-cadherin and a remarkable decrease of EMT markers and associated proteins including vimentin, snail, and claudin-1. As the loss of anchorage dependence is an important barrier to metastasis, the observed inhibitory effects of jorunnamycin A on the coordinating networks of EMT and anchorage-independent growth emphasize the potential development of jorunnamycin A as an effective agent against lung cancer metastasis.

5-O-Acetyl-Renieramycin T from Blue Sponge Xestospongia sp. Induces Lung Cancer Stem Cell Apoptosis.

Lung cancer is one of the most significant cancers as it accounts for almost 1 in 5 cancer deaths worldwide, with an increasing incident rate. Management of the cancer has been shown to frequently fail due to the ability of the cancer cells to resist therapy as well as metastasis. Recent evidence has suggested that the poor response to the current treatment drugs and the ability to undergo metastasis are driven by cancer stem cells (CSCs) within the tumor. The discovery of novel compounds able to suppress CSCs and sensitize the chemotherapeutic response could be beneficial to the improvement of clinical outcomes. Herein, we report for the first time that 5-O-acetyl-renieramycin T isolated from the blue sponge Xestospongia sp. mediated lung cancer cell death via the induction of p53-dependent apoptosis. Importantly, 5-O-acetyl-renieramycin T induced the death of CSCs as represented by the CSC markers CD44 and CD133, while the stem cell transcription factor Nanog was also found to be dramatically decreased in 5-O-acetyl-renieramycin T-treated cells. We also found that such a CSC suppression was due to the ability of the compound to deplete the protein kinase B (AKT) signal. Furthermore, 5-O-acetyl-renieramycin T was able to significantly sensitize cisplatin-mediated apoptosis in the lung cancer cells. Together, the present research findings indicate that this promising compound from the marine sponge is a potential candidate for anti-cancer approaches.

A new sterol from the Vietnamese marine sponge Xestospongia testudinaria and its biological activities.

A new sterol, langcosterol A (1), together with two known sterols 2 and 3, were isolated from the marine sponge Xestospongia testudinaria collected in Vietnam. Their chemical structures were elucidated on the basis of extensive spectroscopic analyses and comparisons with published data. The new compound 1 and the known compound 3 exhibited moderate cytotoxic activities against three human cancer cell lines (A549, lung cancer; MCF7, breast cancer; HeLa, cervical cancer) and a human normal cell line (WI-38 fibroblast), with IC50 values ranging from 29.0 to 68.0 µM.

Macrocyclic bis-quinolizidine alkaloids from Xestospongia muta.

A new stereoisomer Meso-araguspongine C together with nine reported macrocyclic bis-quinolizidine alkaloids araguspongines A, C, E, L, N-P, petrosin, and petrosin A were isolated from marine sponge Xestospongia muta. Stereochemistry of meso-araguspongine C (2) and araguspongines N-P (3-5) were established by their NMR data and conformational analyses. Both araguspongine C (1) and meso-araguspongine C (2) exhibited great cytotoxic activity towards HepG-2, HL-60, LU-1, MCF-7, and SK-Mel-2 human cancer cells (IC50 in the range of 0.43-1.02 µM). At a concentration of 20 µM, isolated compounds (1-10) also showed modest inhibitory effects (from 7.6 to 40.8%) on the NO production in LPS activated RAW264.7 macrophages.

Variations in Microbial Diversity and Metabolite Profiles of the Tropical Marine Sponge Xestospongia muta with Season and Depth.

Xestospongia muta is among the most emblematic sponge species inhabiting coral reefs of the Caribbean Sea. Besides being the largest sponge species growing in the Caribbean, it is also known to produce secondary metabolites. This study aimed to assess the effect of depth and season on the symbiotic bacterial dynamics and major metabolite profiles of specimens of X. muta thriving in a tropical marine biome (Portobelo Bay, Panamá), which allow us to determine whether variability patterns are similar to those reported for subtropical latitudes. The bacterial assemblages were characterized using Illumina deep-sequencing and metabolomic profiles using UHPLC-DAD-ELSD from five depths (ranging 9-28 m) across two seasons (spring and autumn). Diverse symbiotic communities, representing 24 phyla with a predominance of Proteobacteria and Chloroflexi, were found. Although several thousands of OTUs were determined, most of them belong to the rare biosphere and only 23 to a core community. There was a significant difference between the structure of the microbial communities in respect to season (autumn to spring), with a further significant difference between depths only in autumn. This was partially mirrored in the metabolome profile, where the overall metabolite composition did not differ between seasons, but a significant depth gradient was observed in autumn. At the phyla level, Cyanobacteria, Firmicutes, Actinobacteria, and Spirochaete showed a mild-moderate correlation with the metabolome profile. The metabolomic profiles were mainly characterized by known brominated polyunsaturated fatty acids. This work presents findings about the composition and dynamics of the microbial assemblages of X. muta expanding and confirming current knowledge about its remarkable diversity and geographic variability as observed in this tropical marine biome.

Prokaryotic communities of Indo-Pacific giant barrel sponges are more strongly influenced by geography than host phylogeny.

Sponges harbor complex communities of microorganisms that carry out essential roles for the functioning and survival of their hosts. In some cases, genetically related sponges from different geographic regions share microbes, while in other cases microbial communities are more similar in unrelated sponges collected from the same location. To better understand how geography and host phylogeny cause variation in the prokaryotic community of sponges, we compared the prokaryotic community of 44 giant barrel sponges (Xestospongia spp.). These sponges belonged to six reproductively isolated genetic groups from eight areas throughout the Indo-Pacific region. Using Illumina sequencing, we obtained 440 000 sequences of the 16S rRNA gene V3V4 variable region that were assigned to 3795 operational taxonomic units (OTUs). The prokaryotic community of giant barrel sponges was characterized by 71 core OTUs (i.e. OTUs present in each specimen) that represented 57.5% of the total number of sequences. The relative abundance of these core OTUs varied significantly among samples, and this variation was predominantly related to the geographic origin of the sample. These results show that in giant barrel sponges, the variation in the prokaryotic community is primarily associated with geography as opposed to phylogenetic relatedness.

Growth and longevity in giant barrel sponges: Redwoods of the reef or Pines in the Indo-Pacific?

Describing life history dynamics of functionally important species is critical for successful management. Barrel sponges (Xestospongia spp.) fill ecologically important roles on coral reefs due to their large size and water column interactions. Studies of Caribbean X. muta suggest they may be up to 1000 s of years old. However, nothing is known of barrel sponge growth rates outside the Caribbean. We assessed Indo-Pacific barrel sponge demography with a focus on specific growth rate (SGR), density, and mean volume across four sites of varying habitat quality. Four growth models were compared using Akaike's Information Criterion using a multi-model inference approach. Age was extrapolated and validated based on sponge size on a shipwreck of known age. Sponges from different sites showed differences in density, volume gained, and mean volume, but not growth rates. Interestingly, SGRs were slightly slower than that of X. muta, yet growth models supported rapid growth; Indo-Pacific sponges were over twice as old as published estimates of comparably sized X. muta (53-55 as compared to 23 years of age, respectively), although extrapolation errors are likely to increase with sponge size. This suggests that barrel sponge growth rates in the Indo-Pacific might be more comparable to Pines rather than Redwoods.