Morphology and sedimentology of (clustered) cold-water coral mounds at the south Rockall Trough margins,NE Atlantic Ocean

Cold-water coral mounds on both margins of the Rockall Trough (NE Atlantic Ocean) have a strongly different morphology. Single, isolated mounds occur on the SE margin and are mainly found on the upper slope between 900 and 650 m water depth, while large mound clusters are found on the SW margin in water depths between 600 and 1,000 m, in a narrow zone almost parallel to the slope. Sedimentation rates on the mounds are higher than on the surrounding seabed as a result of baffling of biogenic carbonate debris and siliciclastic particles by the coral framework covering the mounds. This is confirmed by ²¹⁰Pb measurements. The individual coral growth rate can be three times higher then the vertical growth rate of the coral cover (±10 mm year⁻¹) which in turn is more than an order of magnitude higher then the present-day overall mound growth rate (±0.25 mm year⁻¹). The presence of extensive hardgrounds and firmgrounds and the three-dimensional coral framework are considered to be responsible for the stability of the relatively steep slopes of the mounds. High current velocities in the intramound areas result in local non-sedimentation and erosion, as is shown by the presence of IRD (ice-rafted debris) lag deposits on the seabed and moats around some of the mounds. The morphology and sedimentology of cold-water coral-covered (mainly Lophelia pertusa and Madrepora oculata) mounds on the southern Rockall Trough margins (NE Atlantic Ocean) is discussed and a model describing the development of these mounds is presented.     

Boring sponges,an increasing threat for coral reefs affected by bleaching events

Coral bleaching is a stress response of corals induced by a variety of factors, but these events have become more frequent and intense in response to recent climate‐change‐related temperature anomalies. We tested the hypothesis that coral reefs affected by bleaching events are currently heavily infested by boring sponges, which are playing a significant role in the destruction of their physical structure. Seventeen reefs that cover the entire distributional range of corals along the Mexican Pacific coast were studied between 2005/2006, and later between 2009/2010. Most of these coral reefs were previously impacted by bleaching events, which resulted in coral mortalities. Sponge abundance and species richness was used as an indicator of bioerosion, and coral cover was used to describe the present condition of coral reefs. Coral reefs are currently highly invaded (46% of the samples examined) by a very high diversity of boring sponges (20 species); being the coral reef framework the substrate most invaded (56%) followed by the rubbles (45%), and the living colonies (36%). The results also indicated that boring sponges are promoting the dislodgment of live colonies and large fragments from the framework. In summary, the eastern coral reefs affected by bleaching phenomena, mainly provoked by El Niño, present a high diversity and abundance of boring sponges, which are weakening the union of the colony with the reef framework and promoting their dislodgment. These phenomena will probably become even more intense and severe, as temperatures are projected to continue to rise under the scenarios for future climate change, which could place many eastern coral reefs beyond their survival threshold.     

Benthic foraminifera associated with a hydrocarbon seep in the Rockall Trough (NE Atlantic)

Recent benthic foraminiferal assemblages in surface sediments of the Rockall Trough (NE Atlantic) have been qualitatively and quantitatively studied in order to investigate the effects of hydrocarbon seepage on benthic foraminiferal populations. Species diversity and abundance data have been examined in samples of similar lithology collected from hydrocarbon seep and non-seep (control) areas at a water depth of about 1000 m. Three species groups with different environmental preferences can be recognized. Group 1 dominates seep samples, and includes species tolerant to hydrocarbon emission, especially Angulogerina bradyana. In contrast, the less tolerant Group 2 species are weakly represented at seeps but dominate control samples. Group 3 species occur in low frequencies in both seep and non-seep samples. Furthermore, the measurement of species diversity (Shannon-Wiener and Simpson indices) demonstrates a difference in foraminiferal occurrence and frequencies between the seep and non-seep sites. Thus, the benthic foraminiferal distribution pattern is guided by different sensitivities of the species to hydrocarbons, reduced bottom-water oxygen usually associated with seepage and/or to a relatively elevated organic matter content in the sediment.     

The predation of mysids by fish of the Rockall Trough,northeastern Atlantic Ocean

The stomach contents of representatives of approximately 100 species of pelagic and demersal fish caught in the Rockall Trough, northeastern Atlantic ocean, have been examined for the occurrence of mysids. More than 40 species of fish included mysids in their diets. The majority of the 21 species of mysids identified in the stomachs live in close association with the sediment and are rarely caught in pelagic nets. Mysids contributed significantly to the diets of many demersal fish but were not apparently important constituents of the food of pelagic fish.     

In situ observation of chimaerid species in the Gorringe Bank: new distribution records for the north‐east Atlantic Ocean

In the framework of the R.V. Nautilus exploration programme, remotely operated vehicle (ROV) surveys were conducted at bathyal depths in the Gorringe Bank. Video transects revealed the presence of the chimaerids Chimaera opalescens and Hydrolagus affinis in the region. An identification key for the north‐east Atlantic species of the family Chimaeridae is proposed.     

Reproductive cycle of the coral-excavating sponge Thoosa mismalolli (Clionaidae) from Mexican Pacific coral reefs

Abstract. Individuals of the recently described demosponge Thoosa mismalolli are common on Mexican Pacific coral reefs, excavating burrows in living corals and in other calcareous substrata. To better understand the propagative abilities of this sponge, we conducted a histological study over an 18-month period (May 2007–November 2008) to identify sexual and asexual reproductive structures. Members of the species are viviparous and hermaphroditic, with various developmental stages of oocytes, spermatic cysts, and embryos co-occurring in the mesohyl for most of the year. This nearly continuous reproductive activity intensified during the warm season. Fertilization was internal, and embryos developed inside the parental sponge to produce an unciliated hoplitomella larva, characterized by a peculiar siliceous skeleton. In addition to the sexually generated larvae, adults of T. mismalolli formed gemmules for asexual reproduction. Gemmules occurred within the mesohyl during all months of the year, but were most abundant in the coldest months. This combination of sexual and asexual processes enables individuals of T. mismalolli to reproduce almost continuously. This strategy may facilitate both long-term persistence within reefs and effective dispersal between distant reefs.     

Analysis of bacterial communities in sponges and coral inhabiting Red Sea,using barcoded 454 pyrosequencing

Microbial communities are linked with marine sponge are diverse in their structure and function. Our understanding of the sponge-associated microbial diversity is limited especially from Red Sea in Saudi Arabia where few species of sponges have been studied. Here we used pyrosequencing to study two marine sponges and coral species sampled from Obhur region from Red sea in Jeddah. A total of 168 operational taxonomic units (OTUs) were identified from Haliclona caerulea, Stylissa carteri and Rhytisma fulvum. Taxonomic identification of tag sequences of 16S ribosomal RNA revealed 6 different bacterial phyla and 9 different classes. A proportion of unclassified reads were was also observed in sponges and coral sample. We found diverse bacterial communities associated with two sponges and a coral sample. Diversity and richness estimates based on OUTs revealed that sponge H. caerulea had significantly high bacterial diversity. The identified OTUs showed unique clustering in three sponge samples as revealed by Principal coordinate analysis (PCoA). Proteobacteria (88–95%) was dominant phyla alonwith Bacteroidetes, Planctomycetes, Cyanobacteria, Firmicutes and Nitrospirae. Seventeen different genera were identified where genus Pseudoalteromonas was dominant in all three samples. This is first study to assess bacterial communities of sponge and coral sample that have never been studied before to unravel their microbial communities using 454-pyrosequencing method.     

Benthic-pelagic coupling on coral reefs: Feeding and growth of Caribbean sponges

Benthic-pelagic coupling and the role of bottom-up versus top-down processes are recognized as having a major impact on the community structure of intertidal and shallow subtidal marine communities. Bottom-up processes, however, are still viewed as principally affecting the outcome of top-down processes. Sponges on coral reefs are important members of the benthic community and provide a crucial coupling between water-column productivity and the benthos. Other than scleractinian corals, sponges dominate many of these habitats where water column productivity is composed of mostly autotrophic and heterotrophic picoplankton that sponges actively filter. While predation upon sponges by invertebrates, fish, and turtles occurs, the sponges Callyspongia vaginalis, Agelas conifera, and Aplysina fistularis from Florida, Belize, and the Bahamas, respectively, exhibit a consistent and significant pattern of greater biomass, rates of growth, and feeding, as does their food supply, with increasing depth. Sponges consume 65-93% of the available particulate food supply and, at all sites, sponges increase in size and growth rate as depth increases, suggesting that food supply and, therefore, bottom-up processes significantly influence the distribution and abundance of sponges in these habitats.     

Diversity and abundance of climbers from the Atlantic Forest, southeastern Brazil

Climbing plant community composition and abundance was compared between the Alto da Serra de Paranapiacaba Biological Reserve (ASPRB) and the Nascentes de Paranapiacaba Municipal Natural Park (NPMNP), two protected areas in the largest Atlantic Forest remnant, southeastern Brazil. Climbing plants ≥1 cm in diameter were sampled in 52 quadrats of 10 × 20 m (1.04 ha). From these data we calculated the Shannon–Wiener diversity index, calculated abundance and importance values for families, performed a principal coordinate analysis, and created a similarity dendrogram (TWINSPAN). The composition and abundance of species between ASPRB and NPMNP differed significantly due to the successional state of the ASPRB forest, which was affected by more recent disturbance. There we found 34 species, while in the NPMNP, species richness was 72, with only 24 species in common. The two areas formed two groups corresponding to two distinct floristic subsets. These montane forests were characterized by a predominance of species of the Asteraceae. The high species richness, floristic composition, and community composition reflect the greater degree of conservation in the area of NPMNP. The high density and community composition of climbers in the more conserved area of rainforest may be due to the low intensity of disturbance.     

Retention efficiencies of the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis determined by Coulter counter and plate culture analysis

Sponges are the dominant organisms on many coral reefs and through feeding they may greatly reduce the concentration of suspended food particles. Retention efficiencies of the tubular sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis were examined on a coral reef located in the Florida Keys. Replicate ambient and exhalant water samples were collected in situ from individuals of each species and analysed using two methods. Retention efficiencies of suspended particles (0.75-18 µm) examined using Coulter counter analysis were similar among the three sponge species, averaging 86%. For all sponges, particle retention decreased as particle size increased from 0.7 to 18 µm. Water samples plated on to Marine Agar produced 54 microbial types. Retention efficiencies of culturable microbes were similar among the three species, averaging 82%. This study suggests that the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis play an important role in the transfer of energy between the pelagic and benthic environments.     

Marine sponges of the Dampier Archipelago, Western Australia: patterns of species distributions, abundance and diversity

Quantitative surveys revealed high diversity (species richness) of sponges (150 species) in the previously little explored Dampier Archipelago, northwestern Australia. Classification analyses disclosed 11 station groups with high internal heterogeneity in species composition, however some spatial patterns were evident. The composition of sponge assemblages varied with environmental factors such as substrate type (coral, igneous rock, limestone rock), aspect (exposed, protected), substrate configuration (limestone platform, dissected reef) and depth. Most of the species (61%) reported from the Dampier Archipelago were rare (found at one or two stations). The number of species found at only one location was high (48%), supporting previous findings that northwestern Australia has high sponge endemism. As a result of all sponge surveys undertaken in the archipelago (qualitative and quantitative, subtidal and intertidal), 275 sponge species have now been reported from the area. This number indicates high species diversity in the region. Estimations of diversity based on non-parametric modelling suggests that there are potentially more species (range 245–346) than presently recorded in the archipelago.     

Diversity and functional analysis of luxS genes in Vibrios from marine sponges Mycale laxissima and Ircinia strobilina

Sponges harbor highly diverse and dense microbial communities, providing an environment in which bacterial signaling may be important. Quorum sensing (QS) is a cell density-dependent signaling process that bacteria employ to coordinate and regulate their gene expression. Previous studies have found that bacteria isolated from sponges are able to produce acyl-homoserine lactones (AHLs), an important class of QS molecules found in proteobacteria. Autoinducer-2 (AI-2) is a second class of QS molecule, and is considered to be an interspecies signal. However, AI-2 signaling has not been reported in sponge bacterial symbionts. In this study, degenerate primers were designed based on known Vibrio luxS sequences to amplify the luxS genes encoding AI-2 synthases of several Vibrio isolates from marine sponges Mycale laxissima and Ircinia strobilina. All the vibrios isolated from these two sponges had luxS genes and were able to produce signals with AI-2 activity as detected using a biological reporter. A novel group of luxS sequences was found, thus extending the known diversity of luxS genes. One isolate was chosen for further analysis of its luxS gene by expression of the gene in Escherichia coli DH5α and by characterization of the profile of AI-2 activity. This work provides the first information about luxS genes and AI-2 activity in sponge-associated bacterial communities.     

Characterization of 13 microsatellite loci for the deep-sea coral, Lophelia pertusa (Linnaeus 1758), from the western North Atlantic Ocean and Gulf of Mexico

A suite of 13 polymorphic tri- and tetranucleotide microsatellite loci were isolated from the ahermatypic deep-sea coral, Lophelia pertusa. Among 51 individuals collected from three disjunct oceanic regions, allelic diversity ranged from six to 38 alleles and averaged 9.1 alleles per locus. Observed heterozygosity ranged from 9.1 to 96.8% and averaged 62.3% in the Gulf of Mexico population. For some loci, amplification success varied among collections, suggesting regional variation in priming site sequences. Four loci showed departures from Hardy-Weinberg equilibrium in certain collections which may reflect nonrandom mating.     

Distribution and ecology of freshwater sponges in Connecticut

A survey of Connecticut lakes and rivers revealed the presence of 7 species of freshwater sponge: Spongilla lacustris, Ephydatia muelleri, Eunapius fragilis, Anheteromeyenia ryderi, A. argyrosperma, Corvomeyenia carolinensis, and Corvospongilla novaeterrae in order of decreasing frequency of occurrence. Corvomeyenia carolinensis has not been reported previously beyond its type locality in South Carolina. In addition, microscleres of Spongilla lacustris, Anheteromeyenia-like megascleres, Ephydatia muelleri-like megascleres, and smooth megascleres (amphioxeas), which could not be assigned to a particular species, were found in surface sediments from lake cores. Spongilla lacustris inhabiting small rivers produced brown, thick-capsuled gemmules during the summer and yellow, thin-capsuled gemmules during the fall. The thick-capsuled gemmules, but not the thin-capsuled gemmules, are tolerant of desiccation; and populations of Spongilla lacustris and Ephydatia muelleri survived severe drying of their habitats during the summer.     

Diversity,structure and interactions of encrusting lithophyllic macrofaunal assemblages from Belgica Bank,East Greenland

Drop stones with lithophyllic macrofauna from Belgica Bank, Greenland Sea (79–81°N and 5–17°W) were collected during the Polarstern cruise in August 2000. The investigation focussed on species richness, diversity, abundance, and interactions of organisms colonizing rocks. On 101 stones collected by 10 dredges from nine sites, 113 taxa (58 genera, 38 families, 12 orders and 8 phyla) were recognized. Among the most abundant groups of organisms were foraminiferans, bryozoans and polychaetes, while the least abundant were anthozoans and ascidians. Abundance ranged from 1239 to 11,383 individuals m⁻² of rock surface area. Bryozoans were the most species-rich group, while anthozoans and ascidians were represented by the least number of species. Colonization occurred at various topographical levels and was classified into two categories. Stones were classified as primary space and were colonized by erect membranous, erect flexible, erect rigid, and flat encrusting organisms. The second level of colonization by epibionts occurred on erect forms of organisms (e.g. erect bryozoans) and was classified as a secondary space. Species composition and abundance between faunal assemblages of primary and secondary space differed greatly. Colonization occurred only on the top of stones and was considered a special adaptation to avoid burial by sedimentation and to enhance food supply. Only 3% of recruits were involved in any competitive interactions. Competition was considered to be of minor importance in structuring lithophyllic assemblages.     

Leucothoe eltoni sp. n., a new species of commensal leucothoid amphipod from coral reefs in Raja Ampat,Indonesia (Crustacea,Amphipoda)

A new species of leucothoid amphipod, Leucothoeeltoni sp. n., is described from coral reefs in Raja Ampat, Indonesia where it inhabits the branchial chambers of solitary tunicates. With an inflated first gnathopod superficially resembling the genus Paraleucothoe, this new species has a two-articulate maxilla 1 palp characteristic of the genus Leucothoe. While described from coral reef environments in tropical Indonesia and the Philippines, it is an established invasive species in the Hawaiian Islands. The most likely mode of introduction was a US Navy dry dock transported to Pearl Harbor in 1992 from Subic Bay, Philippines.     

The Seasonal Relationship Between Meroplankton and Megabenthos on Georges Bank,Gulf of Maine,Northwest Atlantic

A broad based environmental study of Georges Bank included samples of zooplankton and dredge samples of megabenthos for four seasons. The purpose of this account is to examine the seasonal relationship between meroplankton and megabenthos. Mean densities of meroplankton were relatively high at shallow near shore stations and the central Bank and low at deeper stations. Densities were highest in the summer and lowest in the winter for major taxa. For megabenthos the number of species, relative abundance and relative biomass was also highest in the summer and lowest in the winter. Dominant megabenthos provided year round occupants and seasonal pulses. Year round occupants and seasonal peaks of some megabenthos facilitate year round foraging by demersal finfish enhancing the general production of the Bank. It was concluded that Georges Bank megabenthos was part of a broad ranging continental shelf, sand bottom fauna extending at least from Gaspe Bay to the offing of Chesapeake Bay.     

Prevalence and extent of coral diseases in shallow and mesophotic reefs of the Southwestern Atlantic

Coral Reefs - Coral reef ecology has advanced in many fields, but disease patterns across depth gradients remain unclear. By comparing the prevalence and extent of bleaching and diseases in 160...     

Diversity and relative abundance of corals, octocorals and sponges at Jaragua National Park, Dominican Republic

The Jaragua National Park is located in a remote area to the SW coast of the Dominican Republic. Fishing and mining are the major human activities. The main reef formations of the Park include: (a) long bank reefs (spur and groove) growing as bands over the platform and running in a SW-NW direction at 12-25 m depth, (b) well developed, deep, fringing reefs at the platform edge (drop-off) areas which could extend from 10 to 45 m depth, and (c) small patch reefs and poorly developed coral-octocoral-sponge-algal communities in shallow platforms near shore, rocky bottoms, and over the submerged walls of the uplifted reef. Nine reef localities were surveyed between Cabo Beata and Bahia Honda using Scuba diving to inventory the diversity and relative abundance of scleractinian corals, octocorals and sponges. Fringing reefs were surveyed starting at the bottom (30 m) and swimming in a zig-zag pattern (50 m on each side) to shallower areas. Bank reefs were surveyed by swimming in zig-zag across the spur-groove formation along 500 m. Sponges were the most diverse group with 83 species in 50 genera followed by the scleractinian corals with 56 species in 26 genera and the octocorals with 47 species in 15 genera. New records included eight coral species, 29 octocoral species and 59 sponges. The diversity, species composition and abundance of particular groups varied across the different localities. Northern reefs within the park and the Los Frailes Island offshore had the highest live cover, relative abundance and diversity for the three groups. In general, the Jaragua National Park had the highest diversity of corals, octocorals and sponges reported for the Dominican Republic and rank amongst the highest reported for the northern Caribbean. It is recommended that the area be protected and that fishing activities be regulated or eliminated altogether.