Red Sponge Research Articles

Antifungal Potential of Marine Organisms of the Yucatan Peninsula (Mexico) against Medically Important Candida spp.

Invasive fungal infections represent a global health threat. They are associated with high mortality and morbidity rates, partly due to the ineffectiveness of the available antifungal agents. The rampant increase in infections recalcitrant to the current antifungals has worsened this scenario and made the discovery of new and more effective antifungals a pressing health issue. In this study, 65 extracts from marine organisms of the Yucatan Peninsula, Mexico, were screened for antifungal activity against Candida albicans and Candida glabrata, two of the most prevalent fungal species that cause nosocomial invasive fungal infections worldwide. A total of 51 sponges, 13 ascidians and 1 gorgonian were collected from the coral reef and mangrove forest in the Yucatan Peninsula (Mexico) and extracted with organic solvents. Nine crude extracts showed potent antifungal activity, of which four extracts from the sponge species Aiolochroia crassa, Amphimedon compressa, Monanchora arbuscula and Agelas citrina had promising activity against Candida spp. Bioassay-guided fractionation of the M. arbuscula extract revealed the remarkable fungicidal activity of some fractions. Analysis of the chemical composition of one of the most active fractions by UHPLC-HRMS and NMR indicated the presence of mirabilin B and penaresidin B, and their contribution to the observed antifungal activity is discussed. Overall, this work highlights marine organisms of the Yucatan Peninsula as important reservoirs of natural products with promising fungicidal activity, which may greatly advance the treatment of invasive fungal infections, especially those afflicting immunosuppressed patients.

Depth-dependent trophic strategies of Caribbean sponges on mesophotic coral reefs

Mesophotic coral reef ecosystems (MCEs) are characterized by gradients in irradiance, temperature and trophic resources. As depth increases on Caribbean mesophotic reefs, particulate organic matter increases while dissolved organic matter decreases, and the increase in particulate organic matter is directly related to the increase in sponge abundances and growth rates on MCEs. To further understand the trophic ecology of sponges, changes in microbiome composition and function, stable isotopic composition and proximate biochemical composition of 4 Caribbean reef sponges (Amphimedon compressa, Agelas tubulata, Plakortis angulospiculatus and Xestospongia muta) were quantified along a shallow to mesophotic depth gradient on Grand Cayman Island. Increases in δ15N for all sponges were observed as depth increased, indicating an increasing reliance on heterotrophic food resources. Species-specific changes in symbiotic microbial community composition were also observed as depth increased, and the predicted functional genes associated with nitrogen and carbon cycling showed species-specific changes between depths. Regardless of species-specific changes in microbiome community structure or function, or whether sponges were classified as high microbial or low microbial abundance, sponges increased their consumption of particulate organic matter with increasing depth into the lower mesophotic zone.

Biochemical variability in sponges across the Caribbean basin

AbstractSponges are a diverse phylum of sessile filter‐feeding invertebrates that are abundant on Caribbean reefs and provide essential ecological services, including nutrient cycling, reef stabilization, habitat, and food for a variety of fishes and invertebrates. As prominent members of the benthic community, and thus potential food resources, factors determining the biochemical and energetic content of sponges will affect their trophic contributions to coral reef ecosystems. In order to evaluate the influence of geographic variation on biochemical composition and energetic content in the tissue of sponges, we collected several common and widespread species (Agelas conifera, Agelas tubulata, Amphimedon compressa, Aplysina cauliformis, Niphates amorpha, Niphates erecta, and Xestospongia muta) from multiple shallow reefs in four countries across the Caribbean Basin, including Belize, Curaçao, Grand Cayman, and St. Croix, U.S. Virgin Islands. In addition, we correlated inherent species‐level traits, including the production of antipredator chemical defenses and the relative abundance of microbial symbionts, with biochemical and energetic content. We found that energetic content was higher in sponges with antipredator chemical defenses, and was significantly correlated with the concentration of chemical extracts from these sponges. We also noted that sponges with high microbial abundance contained significantly more soluble protein than sponges with low microbial abundance. Finally, both biochemical and energetic content varied significantly among sponges from different locations; sponges from Grand Cayman had the highest lipid and energetic content, whereas sponges from Belize had the highest carbohydrate content but lowest energetic content. Despite similar environmental conditions at these sites, our results demonstrate that biochemical and energetic content of sponges exhibits geographic variability, with potential implications for the trophic ecology of sponges throughout the Caribbean Basin.

Observations of life history traits of Typton carneus Holthuis, 1951 (Caridea, Palaemonidae): a poorly known sponge-dwelling shrimp

The objective of this study was to investigate some life history traits of the palaemonid shrimp Typton carneus collected from a reef in northeastern Brazil. Samples of the sponges Amphimedon compressa, A. viridis, Desmapsamma anchorata, Dysidea etheria, Haliclona implexiformis and Tedania ignis were analyzed and shrimps were removed from them. A total of 41 individuals were found in Te. ignis, three in H. implexiformis and one in D. etheria; the latter two sponges are new records of sponge hosts for Ty. carneus. Of the specimens associated with Te. ignis, 24 were males, 10 ovigerous females, six non-ovigerous females and one juvenile male. Fecundity varied between 19 to 56 eggs (37 ± 14) per female, and the mean egg volume was 0.033 ± 0.010 mm³. Eleven heterosexual pairs were obtained. Characteristics of the pairs suggest a monogamous mating system for the studied population, such as: the absence of sexual dimorphism in weaponry and body size and presence of paired non-brooding and brooding females carrying eggs in different development stages; and a sex ratio that does not differ from the expected 1:1. However, the lack of size-assortative pairing as well as the low proportion of pairs, compared to solitary individuals, have been observed in polygamous mating systems.

Marine Organisms from the Yucatan Peninsula (Mexico) as a Potential Natural Source of Antibacterial Compounds.

A total of 51 sponges (Porifera) and 13 ascidians (Chordata) were collected on the coast of the Yucatan Peninsula (Mexico) and extracted with organic solvents. The resulting extracts were screened for antibacterial activity against four multidrug-resistant (MDR) bacterial pathogens: the Gram-negative Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentrations (MICs) of the organic extracts of each marine organism were determined using a broth microdilution assay. Extracts of eight of the species, in particular the Agelas citrina and Haliclona (Rhizoniera) curacaoensis, displayed activity against some of the pathogens tested. Some of the extracts showed similar MIC values to known antibiotics such as penicillins and aminoglycosides. This study is the first to carry out antimicrobial screening of extracts of marine sponges and ascidians collected from the Yucatan Peninsula. Bioassay-guided fractionation of the active extracts from the sponges Amphimedon compressa and A. citrina displayed, as a preliminary result, that an inseparable mixture of halitoxins and amphitoxins and (-)-agelasine B, respectively, are the major compounds responsible for their corresponding antibacterial activities. This is the first report of the antimicrobial activity of halitoxins and amphitoxins against major multidrug-resistant human pathogens. The promising antibacterial activities detected in this study indicate the coast of Yucatan Peninsula as a potential source of a great variety of marine organisms worthy of further research.

Biological activities of marine invertebrates extracts from the northeast brazilian coast.

This paper reports the in vitro antiproliferative effects, antiprotozoal, anti-herpes and antimicrobial activities of 32 organic extracts of 14 marine sponges and 14 corals collected in northeast Brazilian coast. The ethanolic extracts of the sponges Amphimedon compressa and Tedania ignis, and the acetone extract of Dysidea sp. showed relevant results concerning the antiproliferative effects against A549, HCT-8, and PC-3 cell lines by sulforhodamine B assay, but also low specificity. Concerning the antiprotozoal screening, the ethanolic extract of Amphimedon compressa and the acetone and ethanolic extracts of Dysidea sp. were the most active against Leishmania amazonensis and Trypanosoma cruzi expressing β-galactosidase in THP-1 cells. In the preliminary anti-HSV-1 (KOS strain) screening, the ethanolic extracts of the sponges Amphimedon compressa, Haliclona sp. and Chondrosia collectrix inhibited viral replication by more than 50%. The most promising anti-herpes results were observed for the ethanolic extract of Haliclona sp. showing high selective indices against HSV-1, KOS and 29R strains (SI> 50 and >79, respectively), and HSV-2, 333 strain (IS>108). The results of the antibacterial screening indicated that only the ethanolic extract of Amphimedon compressa exhibited a weak activity against Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli by the disk diffusion method. In view of these results, the extracts of Amphimedon compressa, Tedania ignis and Dysidea sp. were selected for further studies aiming the isolation and identification of the bioactive compounds with antiproliferative and/or antiprotozoal activities. The relevant anti-herpes activity of the ethanolic extract of Haliclona sp. also deserves special attention, and will be further investigated.

Three new Raspailiidae Hentschel, 1923 (Axinellida, Demospongiae) from Peru.

Currently 26 sponge species are known for the Peruvian coast, but so far no raspailiids had been recorded from this region. Raspailiidae are distributed worldwide and its species are characterized by encrusting, massive, lobate, fan-shaped or branching growth forms, usually with a very hispid surface. In the present study, three new species of Raspailiidae are described from the Peruvian coast. Two new Eurypon spp. were collected at Islas Lobos de Afuera (Lambayeque). Eurypon lacertus sp. nov. is a thinly encrusting orange sponge with choanosomal skeleton composed of large tylostyles and small acanthostyles, and ectosomal skeleton with anisoxeas. Eurypon hookeri sp. nov. is a crustose, ruby red sponge, with choanosomal skeleton composed of large (subtylo)styles and acanthostyles, and ectosomal skeleton pierced by acanthostyles and (subtylo)styles, often surrounded by bouquets of smaller styles. The third new species, Plocamione matarani sp. nov., was collected at Matarani (Arequipa). It is a thinly encrusting orange sponge, the only Plocamione with two categories of choanosomal styles, and a single category of ectosomal styles, acanthostyles and anisoacanthostrongyles. These are the first records of Eurypon and Plocamione for the Peruvian coast, and the entire Southeastern Pacific, in the case of the latter.

The coral-killing red sponge Clathria (Microciona) aceratoobtusa (Porifera: Demosponigiae) invades various coral communities of Gulf of Mannar Marine National Park, southeast India

Accounts of the encrusting, coral-killing sponges are increasing at an alarming rate. The present paper details about a thinly encrusting red sponge Clathria (Microciona) aceratoobtusa (Carter, 1887) which is invasive or locally spreading species and create deleterious outbreaks on Gulf of Mannar coral reefs. Earlier it has also been recorded from Yemen, but not taxonomically identified. This sponge is regarded as an aggressive space-competitor locally overgrowing and killing corals, mostly belonging to the coral genera such as Porites, Acropora, Montipora, Favia and Turbinaria. We observed that Turbinaria colonies were the substrate more preferred by the sponge than other coral colonies in the entire study site. The present observation analyses detail the taxonomical and ecological data of Clathria (M.) aceratoobtusa with a comprehensive review of its ecological preference.

Diversity and structure of sponge communities of the Isla de Aves Wildlife Refuge, Caribbean Sea, Venezuela

Sponges (Phylum Porifera) are abundant, diverse and usually with high substrate coverage in coral reef environments. In 2009, we initiated the systematic study of the coralline bottoms of the Isla de Aves, the most remote island of Venezuela. The study consisted in the identification and quantification of the sponges at 16 localities along 1x10 m transects (n=60). The surveys were done in shallow and deep sites, and on the windward and leeward sides. The average sponge coverage was 8.19% (SE=0.12 max=35.4%), which is considered high in comparison with other reefs from the Caribbean Region. A total of 1450 sponges were identified, which represents 77 species, nine of them representing new records for Venezuela. There is a dominance of a few species in these communities, where Amphimedon compressa is the most abundant (16.29%), followed by Agelas sventres (14.24%), Plakortis angulospiculatus (7.44%), Scopalina ruetzleri (6.80%), Ailochroia crassa (6.73%) and Cliona dioryssa (5.74%). The average diversity (SW index) for all transects was 1.66 (SE=0.07), and the equitability 0.81 (SE=0.02). The nmMDS analysis of the sponge communities produced two main groups of localities, responding to depth. The SIMPER analysis (according to depth criteria) produced 83% of overall average dissimilarity between the groups, being A. compressa, the species that most contribute with this difference (12.38%). Depth (and its associated physics parameters) could be the most determinant factor of the differences in structure of these communities.

Evidences for the antitumor potentiality of Hemimycale arabica and Negombata magnifica mesohyls in hepatocellular carcinoma rat model

The current study was constructed to explore the antitumor activity of Hemimycale arabica (blue sponge) and Negombata magnifica (red sponge) mesohyls in rat model of HCC. Forty adult female albino rats were distributed into: (1) negative control group, (2) HCC group, (3) Doxorubcin (DOXO)-treated group, (4) mesohyl of H. arabica-treated group, and (5) mesohyl of N. magnifica-treated group. Serum AST, ALT, GGT, α-fucosidase (AFU) activities; bilirubin, AFP and CEA levels was evaluated. Histopathological investigation of liver tissue sections was performed. The findings of this study indicated the presence of significant enhancement in serum AST, ALT, GGT, AFU, bilirubin, AFP, and CEA values in HCC-afflicted rats vs. the control counterparts. Insignificant change in serum AST, ALT, and GGT activity as well as bilirubin levels has been detected upon treatment of HCC-afflicted rats with DOXO. DOXO treatment revealed significant depletion in AFU, CEA, and AFP serum values comparing with HCC-afflicted ones. Treatment of HCC-afflicted rats with mesohyl blue (Hemimycale arabica) or red (Negombata magnifica) sponges evoked significant blunting in the measured biochemical parameters with respect to the untreated HCC-afflicted ones. The favorable impact of the natural treatments was documented by the great recovery of the structural organization of the liver of the treated rats. The current study provides an experimental evidence for the antitumor potential of Hemimycale arabica and Negombata magnifyica mesohyls in HCC rat model which may be ascribed to the strong hepatoprotective activity, the powerful free radical scavenging ability, and the highly apoptotic property of their active constitutes.

Brefeldin-A: an Antiproliferative Metabolite of the Fungus Curvularia trifolii Collected from the Veracruz Coral Reef System, Mexico

In this paper the isolation and structure analysis of three sterols and brefeldin-A from the mycelial extract of the liquid fermentation of fungus Curvularia trifolii isolated from the marine sponge Amphimedon compressa collected from the Coral Reef System of Veracruz is reported. This is the first report on the production of brefeldin-A by the fungus C. trifolii. The results on isolation biological activity support the importance of the conservation of the Mexican ecosystems of coral reefs as a source of microorganisms with a pharmaceutical potential.

Sponges and cnidarians (Hydrozoa and Anthozoa) from Oro Verde reef; benthic coverage and faunal affinity with the reef systems of Veracruz, Mexico.

Sampling was conducted in twelve geographical points of the Oro Verde reef during the June-August 2015 period, in-order-to record species of sponges, hydrocorals and anthozoans, and to estimate the coverage of algae, sponges, corals, sea fans and abiotic components (e.g., sand and pavement) using 50 m long photo transects. We explored the northern, southern, central, eastern and western section of the reef. Analysis of non-metric multidimensional scaling (NMDS) was performed to explain similarities of the sampling units based on the information obtained. In addition, the composition of sponges and coral reefs from Oro Verde reef was compared with the other reef systems of Veracruz to determine affinities using the NMDS method. The similarity test ANOSIMwas used to explain significant differences among dissimilar groups. A total of 35 species of Phylum Porifera and 29 species of Phylum Cnidaria were recorded. The most common species in the reef were the sponges Callyspongia armigera, Niphates erecta, and Amphimedon compressa, and the corals Montastraea cavernosa, Porites astreoides, Siderastrea siderea, Colpophyllia natans. Filamentous and frondose algae were the most abundant in coverage (49.4 ± 7.7% and 20 ± 9.7%, respectively), compared to reef corals that showed low coverage (9.5 ± 6.1%), which consisted mainly of M. cavernosa, C. natans and S. siderea. The faunal richness and the benthic coverage are distributed in a homogeneous way in the reef as sampling sites revealed similarities in these community attributes. The composition of sponges from Oro Verde reef presented higher affinity with the adjacent reefs and with the submerged reefs of southern of Veracruz. However, Oro Verde reef is more similar with neighboring reefs in species richness of corals. Discrepancies with the other reefs are attributed to the lack of complete inventories (e. g., Tuxpan) and / or by presenting species with limited distribution.

Faunistics and distribution of Demospongiae: Porifera from the Enmedio Reef, Lobos-Tuxpan Reef System, Mexico

Information on sponges from reefs of northern of Veracruz has increased, however coral formationsstill exist for which there are no faunal lists. For this reason, this report provides the first inventory of sponges for the Enmedio reef. Sampling was completed during the November 2014-October 2015 period; five sampling sites were established in the leeward, flatland and windward area for recording species along belt transects of 50 m x2 m. The distribution of species of sponges was determined by estimating the relative frequency in each zone; to determine similarities and significant differences multivariate techniques were applied, such as similarity percentage analysis (SIMPER), analysis of similarity (ANOSIM) and non-metric multidimensional scaling (NMDS). We recorded 32 species of sponges belonging to the Class Desmospongiae; the Order Haploscerida had the most species diversity. The geographic range distribution of of Spirastrella aff. Mollis is extended to the southwest Gulf of Mexico. Species of wide distribution on the reef were Amphimedon compressa, Amphimedon viridis, Scopalinaruetzleri, Aplysina muryciana, Cribrochalina dura and Iotrochota birotulata, which accumulated 50.54% of the relative frequency. Leeward was the reef area with the highest species richness with 25 species and the flatland gathered the lowest species richness with nine. These differences were statistically significant. The composition and distribution of the sponges are heterogeneous on the reef. The leeward area being a deep zone, protected from swell, was the most favorable habitat for the surveyed sponges.

Micro- and nano-structural characterization of six marine sponges of the class Demospongiae.

The sponges produce their skeletal elements and silicateins are the key enzymes in this process. The mechanism underlying the formation of their silica skeleton and its structural properties are of exceptional interest for applications in technology. Micro- and nano-scale structural analysis of the six marine sponges belonging to Demospongiae [Callyspongia (Cladochalia) plicifera (Lamarck, 1814), Cervicornia cuspidifera (Lamarck, 1815), Cinachyrela sp., Niphates erecta (Duchassaing and Michelotti, 1864), Xestospongia muta (Schmidt, 1870) and Amphimedon compressa (Duchassaing and Michelotti, 1864)] were carried out by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and Small-Angle X-ray Scattering (SAXS) techniques. The nano-structural characterizations give some informative evidence about the manner in which silica/silicatein in spicule skeletons is produced by the sponges. The sponge species were successfully discriminated using cluster analysis (HCA) based on FTIR spectra. This study demonstrates and detection of structural differences among sponges and their spicules using combined techniques.

Temporal variation of epi- and endofaunal assemblages associated with the red sponge Tedania ignis on a rocky shore (São Sebastião Channel), SE Brazil

ABSTRACT Sponges are biogenic substrates that increase the available space on rocky shores and provide shelter for many groups of the benthic fauna, which can live both inside and on these sessile invertebrates. In order to assess the differences in temporal variation of endobiont and epibiont groups, samples of the red sponge Tedania ignis (Duchassaing & Michelotti, 1864) were obtained each month for one year. The density, richness and diversity of endobiont and epibiont groups were analyzed in relation to abiotic factors. The dry mass of the sponge was negatively correlated with the density of individuals in both groups and positively with the diversity of endobionts, while organic matter was positively correlated with the diversity of epibionts. Endobiont diversity was more highly correlated with intrinsic factors of the sponge, whereas the diversity of epibionts was more highly correlated with factors related to the surrounding environment.

Transcriptome Changes during the Life Cycle of the Red Sponge, Mycale phyllophila (Porifera, Demospongiae, Poecilosclerida).

Sponges are an ancient metazoan group with broad ecological, evolutionary, and biotechnological importance. As in other marine invertebrates with a biphasic life cycle, the developing sponge undergoes a significant morphological, physiological, and ecological transformation during settlement and metamorphosis. In this study, we compare new transcriptome datasets for three life cycle stages of the red sponge (Mycale phyllophila) to test whether gene expression (as in the model poriferan, Amphimedon queenslandica) also varies more after settlement and metamorphosis. In contrast to A. queenslandica, we find that the transcriptome of M. phyllophila changes more during the earlier pre-competent larva/post-larva transition that spans these defining events. We also find that this transition is marked by a greater frequency of significantly up-regulated Gene Ontology terms including those for morphogenesis, differentiation, and development and that the transcriptomes of its pre-competent larvae and adult are distinct. The life cycle transcriptome variation between M. phyllophila and A. queenslandica may be due to their long separate evolutionary histories and corresponding differences in developmental rates and timing. This study now calls for new transcriptome datasets of M. phyllophila and other sponges, which will allow for tests of the generality of our life cycle expression differences and for the greater exploitation of poriferans in both basic and applied research.

ASSOCIATION OF SYNALPHEUS (CRUSTACEA, DECAPODA, ALPHEIDAE) WITH THE SPONGES FROM PARQUE MARINO NACIONAL SISTEMA ARRECIFAL VERACRUZANO, SW GULF OF MEXICO

We assessed the association between five Synalpheus shrimp species (Synalpheus brevicarpus, Synalpheus fritzmuelleri, Synalpheus minus, Synalpheus scaphoceris, and Synalpheus towsendi) and five sponges (Amphimedon compressa, Aplysina fistularis, Ircinia fistularis, Ircinia. strobilina, and Sidonops neptuni) from parque marino nacional Sistema Arrecifal Veracruzano. Abundance of shrimp in each sponge species collected was noted. The Jaccard index (J) of association was applied to verify this association in six reefs in the park. Further, the correlation between shrimp carapace depth and sponge canal diameter was assessed. The total number of shrimps collected was 102, with the highest number of individuals (n = 62) for S. fritzmuelleri. The highest association was noted between S. towsendi and A. compressa (J = 1), followed by S. fritzmuelleri and I. fistularis (J = 0.88) and S. minus and I. strobilina (J = 0.66). The largest carapace depth (3.40 ± 0.20 mm) was observed for females of S. minus. A positive and significant correlation was noted between shrimp carapace depth and sponge canal diameter (P < 0.001).

Specificity of larval settlement of the Caribbean Orange Icing Sponge, Mycale laevis

AbstractThe Caribbean sponge Mycale laevis is often found growing in close proximity to living scleractinian corals. This commonly observed sponge–coral association has been considered a mutualism, with the coral providing substratum for the sponge, and the sponge protecting the coral skeleton from boring organisms. We examined the specificity of sponge recruitment to live corals, expecting a positive and specific settlement response if a mutualism exists. Benthic surveys conducted off Key Largo, Florida, and Bocas del Toro, Panama, revealed that individuals of M. laevis grew on substrata that included dead coral and other species of sponges. Selectivity analysis indicated that at three of the four survey sites, M. laevis was not randomly distributed, but associated with live corals more frequently than expected from proportional coral cover. However, settlement assays demonstrated that larvae of M. laevis did not preferentially respond to the presence of live coral. We have previously demonstrated that adults of M. laevis are chemically undefended and readily eaten by spongivorous fishes unless protected by adjacent substrata such as live corals. In overfished areas, where spongivore density is low, the sponge is not selectively distributed near corals. Initial results of settlement experiments with different substrata suggested that larvae of M. laevis responded positively to the presence of the chemically defended sponge Amphimedon compressa, perhaps indicating an associational defense. Further experiments revealed that larvae were reacting to artificially high concentrations of exudates from cut surfaces of Am. compressa; settlement was not enhanced in response to healed pieces of Am. compressa. In addition, the larvae of M. laevis did not selectively respond to live coral or to chemically defended heterospecifics. These results indicate that the commonly observed proximity of M. laevis to live corals is not driven by larval settlement behavior, but instead by post‐settlement mortality due to predation.

Height matters: position above the substratum influences the growth of two demosponge species

AbstractIn benthic communities sponges commonly outcompete other organisms in the race for suitable space. Superior competitive ability allows them to grow and overgrow other sessile organisms, some of these being octocorals. Acquiring substratum space, a resource often more limiting than food, is the obvious benefit of these competitive interactions. However, sponges that overgrow larger structures such as branching octocorals also change their position in the water column, and potentially their access to food and exposure to grazers. This study explored the potential benefit of sponge–octocoral associations by examining the effect of height off the bottom on growth of two species of ropelike demosponges under natural conditions. The growths of Amphimedon compressa and Iotrochota birotulata were monitored over 12 months at Cross Harbour, Great Abaco, The Bahamas, using small (5‐cm) sponge fragments that were established at three heights above the bottom (0–5, 30, 60 cm). Growth rates differed among the two species and among different heights. Over 12 months, the mean volumetric growth for A. compressa was 17.7 cm3 ± 1.4 compared with 8.9 cm3 ± 1.4 for I. birotulata. Both species had a higher growth rate at the 60‐cm level. These results suggest that these ropelike sponges benefit from their association and growth on octocorals, not only by using the octocoral skeletal axis as support, but also by acquiring exposure to higher water flow.

Sponge white patch disease affecting the Caribbean sponge Amphimedon compressa

We report on a novel sponge disease, hereafter termed 'sponge white patch' (SWP), affecting the Caribbean sponge species Amphimedon compressa. SWP is characterized by distinctive white patches of variable size that are found irregularly on the branches of diseased sponges. Nearly 20% of the population of A. compressa at Dry Rocks Reef, Florida, USA, showed symptoms of SWP at the time of investigation (November 2007-July 2010). Approximately 21% of the biomass of SWP individuals was bleached, as determined by volume displacement. Scanning electron microscopy analysis showed severe degradation of bleached tissues. Transmission electron microscopy of the same tissues revealed the presence of a spongin-boring bacterial morphotype that had previously been implicated in sponge disease (Webster et al. 2002; Mar Ecol Prog Ser 232:305-309). This particular morphotype was identified in 8 of 9 diseased A. compressa individuals investigated in this study. A close relative of the aforementioned disease-causing alphaproteobacterium was also isolated from bleached tissues of A. compressa. However, whether the spongin-boring bacteria are true pathogens or merely opportunistic colonizers remains to be investigated. Molecular fingerprinting by denaturing gradient gel electrophoresis (DGGE) demonstrated a distinct shift from the microbiota of healthy A. compressa to a heterogeneous mixture of environmental bacteria, including several phylotypes previously implicated in sponge stress or coral disease. Nevertheless, tissue transplantation experiments conducted in the field failed to demonstrate infectivity from diseased to healthy sponges, leaving the cause of SWP in A. compressa to be identified.