Deep-sea Sponge Research Articles

Optimization of a lattice structure inspired by glass sponge

The biomimetic design of engineering structures is based on biological structures with excellent mechanical properties, which are the result of billions of years of evolution. However, current biomimetic structures, such as ordered lattice materials, are still inferior to many biomaterials in terms of structural complexity and mechanical properties. For example, the structure of Euplectella aspergillum, a type of deep-sea glass sponge, is an eye-catching source of inspiration for biomimetic design, many researches have introduced similar architecture in cellular solids. However, guided by scientific theory, how to surpass the mechanical properties of E. aspergillum remains an unsolved problem. We proposed the lattice structure which firstly surpass the E. aspergillum mechanically. The lattice structure of the skeleton of E. aspergillum consists of vertically, horizontally, and diagonally oriented struts, which provide superior strength and flexural resistance compared with the conventional square lattice structure. Herein, the structure of E. aspergillum was investigated in detail, and by using the theory of elasticity, a lattice structure inspired by the biomimetic structure was proposed. The mechanical properties of the sponge-inspired lattice structure surpassed the sponge structure under a variety of loading conditions, and the excellent performance of this configuration was verified experimentally. The proposed lattice structure can greatly improve the mechanical properties of engineering structures, and it improves strength without much redundancy of material. This study achieved the first surpassing of the mechanical properties of an existing sponge-mimicking design. This design can be applied to lattice structures, truss systems, and metamaterial cells.

Oceanographic variability drives the distribution but not the density of the aggregation forming deep-sea sponge Pheronema carpenteri

Identifying and understanding environmental drivers of deep-sea sponge aggregations is critical for effective protection and management. Current literature suggests an association between internal wave activity, regions of enhanced currents, and the distribution of deep-sea sponge aggregations. It is hypothesised that sponges utilise particulate organic matter associated with internal waves and enhanced currents and therefore aggregate in these regions. Random Forest algorithms – as well as preliminary Generalised Additive Models (GAMs) – were fitted to the presence-pseudo-absence and density datasets to characterise the relationship with each environmental variable. Additionally, residual autocovariate variables were calculated and included in models to account for spatial autocorrelation. All variables were statistically significant when GAMs were fitted to the presence-pseudo-absence datasets, but spatial autocorrelation could not be successfully accounted for. In contrast, a Random Forest model was fitted that also successfully accounted for spatial autocorrelation. No relationships were detected when GAMs were fitted to the density dataset – results confirmed by a poorly performing Random Forest model. Our findings suggest that average temperature variability is an important driver of P. carpenteri distribution and should be incorporated into habitat suitability models. However, available environmental data do not capture key drivers of P. carpenteri density, limiting our ability to model, and therefore identify areas where aggregations are likely to occur. This may reflect a mismatch in the spatial scales in which environmental and biological processes occur. We conclude that further research is required, particularly into feeding strategy and reproduction, to identify missing drivers of P. carpenteri density.

Malassezia: A Commensal, Pathogen, and Mutualist of Human and Animal Skin.

Identified in the late nineteenth century as a single species residing on human skin, Malassezia is now recognized as a diverse genus comprising 18 species inhabiting not only skin but human gut, hospital environments, and even deep-sea sponges. All cultivated Malassezia species are lipid dependent, having lost genes for lipid synthesis and carbohydrate metabolism. The surging interest in Malassezia results from development of tools to improve sampling, culture, identification, and genetic engineering, which has led to findings implicating it in numerous skin diseases, Crohn disease, and pancreatic cancer. However, it has become clear that Malassezia plays a multifaceted role in human health, with mutualistic activity in atopic dermatitis and a preventive effect against other skin infections due to its potential to compete with skin pathogens such as Candida auris. Improved understanding of complex microbe-microbe and host-microbe interactions will be required to define Malassezia's role in human and animal health and disease so as to design targeted interventions.

Biodiversity, environmental drivers, and sustainability of the global deep-sea sponge microbiome

In the deep ocean symbioses between microbes and invertebrates are emerging as key drivers of ecosystem health and services. We present a large-scale analysis of microbial diversity in deep-sea sponges (Porifera) from scales of sponge individuals to ocean basins, covering 52 locations, 1077 host individuals translating into 169 sponge species (including understudied glass sponges), and 469 reference samples, collected anew during 21 ship-based expeditions. We demonstrate the impacts of the sponge microbial abundance status, geographic distance, sponge phylogeny, and the physical-biogeochemical environment as drivers of microbiome composition, in descending order of relevance. Our study further discloses that fundamental concepts of sponge microbiology apply robustly to sponges from the deep-sea across distances of >10,000 km. Deep-sea sponge microbiomes are less complex, yet more heterogeneous, than their shallow-water counterparts. Our analysis underscores the uniqueness of each deep-sea sponge ground based on which we provide critical knowledge for conservation of these vulnerable ecosystems.

New Genera, Species and Occurrences of Deep-Sea Asteroidea (Valvatacea, Forcipulatacea, Echinodermata) collected from the North Pacific Ocean by the CAPSTONE Expedition.

Between 2015 and 2018, the NOAA ship Okeanos Explorer embarked on the CAPSTONE expedition, that collected video and specimen data from the Hawaiian Islands region and other American territories in the Central and South Pacific Ocean. Ultimately 20 species, 12 of which are newly described, from 14 genera in 3 families are described herein with one further undescribed species of Pythonaster currently in preparation. Okeanos Explorer collected a total of 17 sea star specimens, of which 9 represent new species and 4 new genera. Additionally, one species imaged by Okeanos Explorer during the campaign was discovered in a museum collection is described herein. Supplementary collections from the tropical Pacific by the R/V Nautilus resulted in a further 11th newly described species which had been originally observed by Okeanos Explorer. A total of 21 specimens were involved as part of this effort. Heligmaster n. gen. is the first new genus of the rarely encountered deep-sea Myxasteridae since Fisher (1906). The Goniasteridae, particularly the corallivorous subfamily Hippasterinae were most heavily represented in the collected material. Video imagery was extensive and provided new occurrence data for rarely seen species as well as several new records that likely represent undescribed species. Many of the new species collected were observed preying on of deep-sea octocorals and sponges.

Three New Carnivorous sponge species (Demospongiae: Cladorhizidae) from the Seamounts of the Central Indian Ridge.

Deep-sea sponges are an imperative component of benthos. They accumulate the suspended organic matter by filtering large quantities of water and, with their intricate structures, provide the most suitable habitats for various associated organisms. We describe three new cadorhizid sponges from the Central Indian Ridge (CIR), Indian Ocean. The sponges are part of the benthic sledge collection conducted onboard the MGS Sagar in the CIR region. A detailed taxonomic description of two novel species, Asbestopluma (Asbestopluma) indiyansis sp. nov., and Asbestopluma (A.) bharatiyae sp. nov. are provided based on the morphological and molecular (mtCOI and 28S) markers. In addition, another new carnivorous species Chondrocladia sagari sp. nov. is described based on the morphological and mtCOI marker. The systematic and descriptions of new species are discussed based on the structural and phylogenetic analysis. Our study shows that the cladorhizid fauna of the seamounts from the CIR are unique and represent regionally endemic benthic habitats.

A new deep-sea sponge Fibulia occiensis sp. nov. (Poecilosclerida: Dendoricellidae) from the 25 South Oceanic Core Complex in the Central Indian Ocean Ridge.

We describe a new deep-sea sponge species, Fibulia occiensis sp. nov., from the Central Indian Ocean Ridge (CIOR) at Rodrigues Triple Junction (RTJ), of the family Dendoricellidae Hentschel, 1923. Two sponge specimens were collected between 19822079 m depth using a benthic sledge in the 25 South Oceanic Core Complex (OCC) region. The megabenthic fauna was collected to establish a baseline of environmental and benthic ecological data. This data will be handy in assessing the impact of sulfide mining in the near future. Fibulia occiensis sp. nov. is fragile and stalked, has a single type of oxea, and no sigma. The new species is different from the congeneric Fibulia species by its larger oxeas and the strongly curved isochelae.

Comparative Genomics of Thaumarchaeota From Deep-Sea Sponges Reveal Their Niche Adaptation.

Thaumarchaeota account for a large portion of microbial symbionts in deep-sea sponges and are even dominant in some cases. In this study, we investigated three new sponge-associated Thaumarchaeota from the deep West Pacific Ocean. Thaumarchaeota were found to be the most dominant phylum in this sponge by both prokaryotic 16S rRNA amplicons and metagenomic sequencing. Fifty-seven published Thaumarchaeota genomes from sponges and other habitats were included for genomic comparison. Similar to shallow sponge-associated Thaumarchaeota, those Thaumarchaeota in deep-sea sponges have extended genome sizes and lower coding density compared with their free-living lineages. Thaumarchaeota in deep-sea sponges were specifically enriched in genes related to stress adapting, symbiotic adhesion and stability, host–microbe interaction and protein transportation. The genes involved in defense mechanisms, such as the restriction-modification system, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system, and toxin-antitoxin system were commonly enriched in both shallow and deep sponge-associated Thaumarchaeota. Our study demonstrates the significant effects of both depth and symbiosis on forming genomic characteristics of Thaumarchaeota, and provides novel insights into their niche adaptation in deep-sea sponges.

Complete genome of Mycetocola spongiae MSC19T isolated from deep-sea sponge Cacospongia mycofijiensis indicates the adaptation to deep-sea environment and sponge-microbe symbioses.

Genome of Mycetocola spongiae MSC19T, a novel marine sponge-associated Actinobacteria isolated from the Mariana Trench sponge Cacospongia mycofijiensis, was sequenced. The genome has one circular chromosome of 3,196,754bp, with an average GC content of 66.43mol%, and 2887 coding sequences. Gene annotation shows that M. spongiae MSC19T possesses series of genes related to adaptation to deep-sea environmental stresses including cold shock, heat shock, osmotic stress and oxidative stress. Genes encoding for heavy metal resistance, multidrug resistance and multiple natural product biosynthesis which are crucial for survival in the extreme environment are also detected in the genome. The potentials to synthesize kinds of vitamins and eukaryotic-like proteins indicates the possible nutrient exchange and mutual recognization between M. spongiae MSC19T and its sponge host. The genome provides insights into the stress resistance and ecological fitness of bacterial symbionts in the deep-sea sponge holobionts.

Two New Species and One New Genus of Glass Sponges (Hexactinellida: Euplectellidae and Euretidae), From a Transect on a Seamount in the Northwestern Pacific Ocean

Hexactinellid sponges often form structural habitats for other organisms and thus support high biodiversity. Two representative morphotypes of hexactinellid sponges were sampled by a remotely operated vehicle along a transect (depths of 2377–2758 m) on the Ko-Hakucho Guyot in the northwestern Pacific Ocean, both new to science. One new species,Flavovirens hemiglobusgen. et sp. nov., which is pedunculate and bears the main choanosomal spicules of diactins, is clearly attributed to the euplectellid subfamily Bolosominae. Its set of microscleres present (namely, predominating oxyhexasters and discasters, and rare discohexasters and staurodiscs) characterizes it as a new genus. The other new species,Chonelasma tyloscopulatumsp. nov., which is funnel in form without dichotomous branching tubes or lateral oscula and has firm body walls supported by a three-layered dictyonal framework, is clearly attributed to the euretid genusChonelasma(subfamily Chonelasmatinae). Its presence of surface pentactins, two types of scopules, and both oxy- and disco-tipped hexasters or hemihexasters as common microscleres, characterizes it as a new species. The placements are also supported by molecular phylogenetic evidence from nuclear 18S rDNA and 28S rDNA, and mitochondrial 16S rDNA and cytochrome c oxidase subunit I (COI) gene. More sampling efforts should be conducted to improve the understanding of the biodiversity of deep-sea seamount sponges.

Mycobiota of deep-sea benthic communities on the Piip submarine volcano, Bering Sea, Russia

The mycobiota of deep-sea benthic communities on the Piip submarine volcano, Bering Sea, Russia, has been studied for the first time. Filamentous fungi were isolated from deep-sea bottom sediments, sponges, and holothurians using traditional culture-based methods. The fungi were identified using a combination of methods based on morphology of reproductive structures, cultural colony characteristics, and the ITS1-5.8S-ITS2and partial β-tubulin (BenA) gene sequencing. A total of 11 species of filamentous fungi from three Ascomycota genera (Aspergillus, Penicillium, and Cladosporium) were recorded from deep-sea benthic communities that formed on the Piip submarine volcano. Levels of the major fatty acids in strains of these fungi were determined.The taxa found are typical of both deep-sea habitats and deep-sea volcanoes. However, the absence of some genera (Acremonium, Aureobasidium, Alternaria …) indicates the weakening of the influence of the volcano on the slopes and base.

Polyesterase activities in bacterial isolates from seaweed and sponges, with potential utility in polyethylene terephthalate plastic and nanoparticle hydrolysis

Many marine bacteria have evolved to produce a range of extracellular enzymes which facilitate their growth and survival in the harsh, oligotrophic conditions often present in marine environments. Marine sponge derived Streptomycesstrains have previously been reported to produce polyesterase enzymes, which are of interest for several biotechnological applications, including polyethylene terephthalate (PET) plastic hydrolysis. Bacteria isolated from sponges and seaweed were screened for polyester hydrolysis activities using plate-clearing assays. Lipolytic and polyesterolytic activities were initially identified by employing tributyrin and polycaprolactone diol agar-based assay systems, respectively. Polyesterase activity was subsequently confirmed on both polycaprolactone and on PET-nanoparticle agar plates, resulting in the prioritisation of six isolates for Illumina next-generation genome sequencing. These include three Bacillusspp., isolated from the brown seaweed Ascophyllum nodosum,and from marine lake sponges Stelligera stuposaand Eurypon major, together with a Maribacterstrain again isolated from S. stuposa, and Brachybacteriumsp. and Micrococcussp. isolates of deep-sea sponges Pheronemasp. and Inflatella pellicula, that were sampled at depths of 2129m and 2900m, respectively. Genome mining and comparative genomic analysis of these isolates is currently underway to identify genes encoding the observed activities and to assess homology with known PET hydrolases. Microbes found living in association with filter-feeding sponges may have increased exposure to the plastics and microplastics that widely contaminate our marine ecosystems, thus representing a promising source of degradative activities towards synthetic polymers that could contribute to new plastic waste management strategies.

Tensile and fracture behavior of silica fibers from the Venus flower basket (Euplectella aspergillum)

The extraordinary mechanical properties shown by many biological materials stem from their unique hierarchical structures. The spicules of the deep-sea glass sponge, Euplectella aspergillum, show layered architecture and are known to improve toughness in various loading conditions. In the present work, we conducted a systematic study on the tensile and fracture behavior of E. aspergillum’s spicules. Tensile tests were performed on three different gage lengths of spicules that compose anchoring structures of E. aspergillum. The cross-sectional area of each spicule was accurately measured using an x-ray microscope. The effect of gage length and varying cross-sectional area on the tensile behavior of spicules is discussed in detail. The interplay between two failure initiation sites, namely, weakest-link flaws and minimum cross-sectional area locations was observed. Weibull statistics were used to quantify the variability in the strengths of spicules as a function of their gage length. The Weibull modulus was observed to decrease with the increase in gage length. The possibility of a bimodal flaw population for a higher gage length of spicules due to the interplay between failure initiation sites is also discussed. The fractography study was utilized to understand the failure and toughening mechanisms of spicules in tensile loading. The fracture toughness of the central core was quantified from fracture surfaces using a linear elastic fracture mechanics model. The present study shows that the failure of spicules initiates in the outer layers and proceeds progressively to the center. The layers surrounding the central core of the spicule resist the crack propagation and increase its toughness.

Oogenesis and lipid metabolism in the deep-sea sponge Phakellia ventilabrum (Linnaeus, 1767)

Sponges contain an astounding diversity of lipids that serve in several biological functions, including yolk formation in their oocytes and embryos. The study of lipid metabolism during reproduction can provide information on food-web dynamics and energetic needs of the populations in their habitats, however, there are no studies focusing on the lipid metabolism of sponges during their seasonal reproduction. In this study, we used histology, lipidome profiling (UHPLC-MS), and transcriptomic analysis (RNA-seq) on the deep-sea sponge Phakellia ventilabrum (Demospongiae, Bubarida), a key species of North-Atlantic sponge grounds, with the goal to (i) assess the reproductive strategy and seasonality of this species, (ii) examine the relative changes in the lipidome signal and the gene expression patterns of the enzymes participating in lipid metabolism during oogenesis. Phakellia ventilabrum is an oviparous and most certainly gonochoristic species, reproducing in May and September in the different studied areas. Half of the specimens were reproducing, generating two to five oocytes per mm2. Oocytes accumulated lipid droplets and as oogenesis progressed, the signal of most of the unsaturated and monounsaturated triacylglycerides increased, as well as of a few other phospholipids. In parallel, we detected upregulation of genes in female tissues related to triacylglyceride biosynthesis and others related to fatty acid beta-oxidation. Triacylglycerides are likely the main type of lipid forming the yolk in P. ventilabrum since this lipid category has the most marked changes. In parallel, other lipid categories were engaged in fatty acid beta-oxidation to cover the energy requirements of female individuals during oogenesis. In this study, the reproductive activity of the sponge P. ventilabrum was studied for the first time uncovering their seasonality and revealing 759 lipids, including 155 triacylglycerides. Our study has ecological and evolutionary implications providing essential information for understanding the molecular basis of reproduction and the origins and formation of lipid yolk in early-branching metazoans.

Identification of BgP, a Cutinase-Like Polyesterase From a Deep-Sea Sponge-Derived Actinobacterium.

Many marine bacteria produce extracellular enzymes that degrade complex molecules to facilitate their growth in environmental conditions that are often harsh and low in nutrients. Marine bacteria, including those inhabiting sea sponges, have previously been reported to be a promising source of polyesterase enzymes, which have received recent attention due to their potential ability to degrade polyethylene terephthalate (PET) plastic. During the screening of 51 marine bacterial isolates for hydrolytic activities targeting ester and polyester substrates, a Brachybacterium ginsengisoli B129SM11 isolate from the deep-sea sponge Pheronema sp. was identified as a polyesterase producer. Sequence analysis of genomic DNA from strain B129SM11, coupled with a genome “mining” strategy, allowed the identification of potential polyesterases, using a custom database of enzymes that had previously been reported to hydrolyze PET or other synthetic polyesters. This resulted in the identification of a putative PET hydrolase gene, encoding a polyesterase-type enzyme which we named BgP that shared high overall similarity with three well-characterized PET hydrolases—LCC, TfCut2, and Cut190, all of which are key enzymes currently under investigation for the biological recycling of PET. In silico protein analyses and homology protein modeling offered structural and functional insights into BgP, and a detailed comparison with Cut190 revealed highly conserved features with implications for both catalysis and substrate binding. Polyesterase activity was confirmed using an agar-based polycaprolactone (PCL) clearing assay, following heterologous expression of BgP in Escherichia coli. This is the first report of a polyesterase being identified from a deep-sea sponge bacterium such as Brachybacterium ginsengisoli and provides further insights into marine-derived polyesterases, an important family of enzymes for PET plastic hydrolysis. Microorganisms living in association with sponges are likely to have increased exposure to plastics and microplastics given the wide-scale contamination of marine ecosystems with these plastics, and thus they may represent a worthwhile source of enzymes for use in new plastic waste management systems. This study adds to the growing knowledge of microbial polyesterases and endorses further exploration of marine host-associated microorganisms as a potentially valuable source of this family of enzymes for PET plastic hydrolysis.

Benthic transition zones in the Atlantic gateway to a changing Arctic ocean

The biogeographic transition from boreal to Arctic marine communities entails a strong taxonomic and functional turnover. Communities living in these areas are being strongly affected by climate warming with rapid reorganizations and change in ecosystem functioning. We assess the megabenthic species composition and functional character in a transition zone around Svalbard. The relationships between environment, taxonomic composition and functional traits are investigated and discussed regarding the potential impacts of climate warming. The biomass data from 293 taxa, coded with 6 functional traits (29 modalities), from 144 trawl stations, were analyzed by multivariate statistics based on taxonomy, RLQ- and fourth corner analysis, based on environment and traits. We find that boundaries between water masses and depths are associated gradual taxonomic and sharp functional transitions. We document a biogeographic transition zone on the slope northeast of Svalbard where surface deposit feeding crustacean associations meet crawling Arctic echinoderm predators. Further we show a sharp transition at 500 m depth along the shelf of Svalbard where boreal filtrating deep-sea sponges meet a unique upraised large-bodied assemblage of bathyal species on the Yermak Plateau. Global warming will likely cause rapid taxonomic and functional shifts in these transition areas, with filtrating sponges and deposit feeding crustaceans possibly expanding into Arctic communities while large, upright, predators further down the slope. There is a need for both monitoring of the transition areas, and for protecting the most vulnerable deep and arctic fauna on the Yermak Plateau.

Anisotropic compression behaviors of bio-inspired modified body-centered cubic lattices validated by additive manufacturing

Bio-inspired lattices have been proved to possess better energy absorption capacity than conventional structures. Here, the two-dimensional deep-sea glass sponge structure is extended to three-dimensional and further topologically optimized to design a novel lattice called modified body-centered cubic (MBCC) lattice. The quasi-static compression behavior of different lattices was investigated via extensive finite element (FE) simulations validated by the experimental tests. The results indicated that the proposed MBCC design can further increase the energy absorption capacity compared with the previous bio-inspired and the conventional body-centered cubic designs. Impressively, the new lattice made of steel exhibits specific energy absorption close to that of foams made of titanium alloy. In addition, the influences of the deviation coefficient and the loading direction on the compressive behaviors of MBCC lattice are investigated parametrically. The proposed lattice structures present a new deformation mode and peculiar anisotropy regarding to the specific strength and the oscillation in the stress-strain curves.

High-Throughput Screening of a Marine Compound Library Identifies Anti-Cryptosporidium Activity of Leiodolide A.

Cryptosporidium sp. are apicomplexan parasites that cause significant morbidity and possible mortality in humans and valuable livestock. There are no drugs on the market that are effective in the population most severely affected by this parasite. This study is the first high-throughput screen for potent anti-Cryptosporidium natural products sourced from a unique marine compound library. The Harbor Branch Oceanographic Institute at Florida Atlantic University has a collection of diverse marine organisms some of which have been subjected to medium pressure liquid chromatography to create an enriched fraction library. Numerous active compounds have been discovered from this library, but it has not been tested against Cryptosporidium parvum. A high-throughput in vitro growth inhibition assay was used to test 3764 fractions in the library, leading to the identification of 23 fractions that potently inhibited the growth of Cryptosporidium parvum. Bioassay guided fractionation of active fractions from a deep-sea sponge, Leiodermatium sp., resulted in the purification of leiodolide A, the major active compound in the organism. Leiodolide A displayed specific anti-Cryptosporidium activity at a half maximal effective concentration of 103.5 nM with selectivity indexes (SI) of 45.1, 11.9, 19.6 and 14.3 for human ileocecal colorectal adenocarcinoma cells (HCT-8), human hepatocellular carcinoma cells (Hep G2), human neuroblastoma cells (SH-SY5Y) and green monkey kidney cells (Vero), respectively. The unique structure of leiodolide A provides a valuable drug scaffold on which to develop new anti-Cryptosporidium compounds and supports the importance of screening natural product libraries for new chemical scaffolds.

Environmental Change at Deep-Sea Sponge Habitats Over the Last Half Century: A Model Hindcast Study for the Age of Anthropogenic Climate Change

Deep-sea sponges inhabit multiple areas of the deep North Atlantic at depths below 250 m. Living in the deep ocean, where environmental properties below the permanent thermocline generally change slowly, they may not easily acclimatize to abrupt changes in the environment. Until now consistent monitoring timeseries of the environment at deep sea sponge habitats are missing. Therefore, long-term simulation with coupled bio-physical models can shed light on the changes in environmental conditions sponges are exposed to. To investigate the variability of North Atlantic sponge habitats for the past half century, the deep-sea conditions have been simulated with a 67-year model hindcast from 1948 to 2014. The hindcast was generated using the ocean general circulation model HYCOM, coupled to the biogeochemical model ECOSMO. The model was validated at known sponge habitats with available observations of hydrography and nutrients from the deep ocean to evaluate the biases, errors, and drift in the model. Knowing the biases and uncertainties we proceed to study the longer-term (monthly to multi-decadal) environmental variability at selected sponge habitats in the North Atlantic and Arctic Ocean. On these timescales, these deep sponge habitats generally exhibit small variability in the water-mass properties. Three of the sponge habitats, the Flemish Cap, East Greenland Shelf and North Norwegian Shelf, had fluctuations of temperature and salinity in 4–6 year periods that indicate the dominance of different water masses during these periods. The fourth sponge habitat, the Reykjanes Ridge, showed a gradual warming of about 0.4°C over the simulation period. The flux of organic matter to the sea floor had a large interannual variability, that, compared to the 67-year mean, was larger than the variability of primary production in the surface waters. Lateral circulation is therefore likely an important control mechanism for the influx of organic material to the sponge habitats. Simulated oxygen varies interannually by less than 1.5 ml/l and none of the sponge habitats studied had oxygen concentrations below hypoxic levels. The present study establishes a baseline for the recent past deep conditions that future changes in deep sea conditions from observations and climate models can be evaluated against.

Mycetocola spongiae sp. nov., isolated from deep-sea sponge Cacospongia mycofijiensis.

A novel bacterial strain (MSC19T) was isolated from a deep-sea sponge Cacospongia mycofijiensis collected in the Mariana Trench at a depth of 2681 m. The cells of the new isolate were Gram-stain-positive, non-motile, oxidase- and catalase-positive, rod-shaped and yellow-coloured. They could grow at 4-32 °C (optimum, 28 °C), pH 5.5-12 (optimum, pH 7.0) and with 0-12 % (w/v) NaCl (optimum, 4 %). The strain's 16S rRNA gene sequence showed 98.41 % similarity to that of Mycetocola saprophilus CM-01T. Phylogenetic analysis further suggested that strain MSC19T represents a new species within the genus Mycetocola. The total genome of MSC19T was approximately 3 196 754 bp in size with a G+C content of 66.43 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among MSC19T and other Mycetocola type strains were 70.35-75.37 % (ANIb), 83.79-84.73 % (ANIm) and 20.3-21.7 % (dDDH). The major fatty acids of MSC19T were composed of anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0, and its predominant menaquinones were MK-10 and MK-9. The polar lipids of MSC19T mainly consisted of diphosphatidylglycerol, phosphatidylglycerol and glycolipid. The diagnostic cell-wall diamino acid was lysine. Combined molecular, physiological, biochemical and chemotaxonomic analyses suggest that strain MSC19T represents a novel species of the genus Mycetocola, for which the name Mycetocola spongiae sp. nov. is proposed. The type strain is MSC19T (=MCCC 1K06265T=KCTC 49701T).