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Biofouling has been reported to be both harmful and innocuous on the growth and survival of cultured bivalves. If harmful, it could increase the operational cost substantially in an attempt to mitigate it. The study investigated the effect of sedentary biofoulers on the growth and survival of Crassostrea tulipa cultured on coconut shell and oyster shell cultches in the Densu Delta, Ghana, from December 2017 to July 2018. Physico-chemical parameters were monitored. Environmental temperature (26.4 ± 0.07 °C–29.5 ± 0.50 °C) and pH (7.2 ± 0.01–8.8 ± 0.01) were found to be within optimum levels for oyster propagation. The low levels of salinity (0.2 ± 0.01 ‰) and DO (0.6 ± 0.01 mg/l) and high turbidity (31.4 ± 2.91 NTU) could explain the observed high mortality of cultured oysters in July 2018. The observed fouling organisms were Fistubalanus pallidus (barnacle), Brachidontes sp. (mussel), Ficopomatus sp. (tube worm), Chaetomorpha antennina (green alga), and sea anemone. Oysters cultured on the undersurface of biofouled oyster shell cultches exhibited significantly faster growth than their cleaned counterparts but comparable on the upper surfaces of the cultches. The growth of cultured oysters on biofouled coconut shell cultches exhibits faster but insignificant growth than the oysters on cleaned cultches. There was no significant difference between the survival of oysters cultured on biofouled and cleaned coconut shell and oyster shell cultches. Marketable size oysters (≥ 6 cm shell height) are attainable in 7 to 8 months for both treatments. It was concluded that biofouling had no deleterious effect on the growth and survival of oysters. Besides, given the preferred shucked oysters in the Ghanaian market, it is inessential to incur further cost to control biofoulers.

Rhamphobrachium (Rhamphobrachium) agassizii is reported from the Cantabrian Sea, Spain, from depths of 925–1207 m. This is its first record off the Iberian Peninsula and in European waters, representing its northernmost distribution in the North Atlantic Ocean to date. Previous reports of R. (R.) agassizii from the eastern and western North Atlantic demonstrate its apparent amphi-Atlantic distribution, which appears consistent with the distribution of the main Atlantic currents. It is a typical deep-water species with its deepest record at 2165 m from the Azores archipelago. The specimens were collected singly at two stations, attesting to the rarity of the species in contrast to its congener R. (Spinigerium) brevibrachiatum which was the most dominant polychaete species in a previous study.

[Resumo] Diopatra é un xénero de poliquetos cunha elevada diversidade taxonómica e ecolóxica, polo que resulta ideal á hora de investigar diferentes hipóteses evolutivas en relación coas estratexias reprodutivas e modos de desenvolvemento. Pese a importancia ecolóxica e económica que presenta, este traballo demostra que aínda existe un baleiro importante no noso coñecemento acerca dos aspectos máis básicos da súa bioloxía e ecoloxía. En concreto, unicamente se atopou información reprodutiva para un terzo das especies que compoñen o xénero e, ademais, na mesma puideron detectarse diferentes sesgos. Por outra banda, a información xenética dispoñible, se ben considerable, foi obtida en numerosos casos a partir de espécimes sen identificar. As anteriores trabas unidas ao escaso solapamento entre o conxunto de datos reprodutivos e o conxunto de datos xenéticos limitaron enormemente a formulación de inferencias evolutivas. Porén, este traballo constitúe un importante punto de partida e marca futuras liñas de investigación. [Resumen] Diopatra es un género de poliquetos con una elevada diversidad taxonómica y ecológica, por lo que resulta ideal a la hora de investigar diferentes hipótesis evolutivas en relación con las estrategias reproductivas y los modos de desarrollo. Pese a la importancia ecológica y económica que presenta, este trabajo demuestra que aún existe un vacío importante en nuestro conocimiento acerca de los aspectos más básicos de su biología y ecología. En concreto, únicamente se encontró información reproductiva para un tercio de las especies que componen el género y, además, en la misma pudieron detectarse diferentes sesgos. Por otro lado, la información genética disponible, se bien considerable, fue obtenida en numerosos casos a partir de especímenes sin identificar. Los anteriores inconvenientes unidos al escaso solapamiento entre el conjunto de datos reproductivos y el conjunto de datos genéticos limitaron enormemente la formulación de inferencias evolutivas. Sin embargo, este trabajo constituye un importante punto de partida y marca futuras líneas de investigación. [Abstract] Diopatra is a genus of polychaetes with high taxonomic and ecological diversity, making it ideal for investigating different evolutionary hypotheses regarding reproductive strategies and developmental modes. Despite its ecological and economic importance, this work shows that there is still an important gap in our knowledge about the most basic aspects of its biology and ecology. Specifically, reproductive information was found for only one third of the species that compose the genus and, in addition, different biases could be detected in this information. On the other hand, the available genetic information, although considerable, was obtained in many cases from unidentified specimens. These drawbacks, together with the low overlap between the reproductive data set and the genetic data set, greatly limited the formulation of evolutionary inferences. Nevertheless, this work constitutes an important starting point and marks future lines of research. Traballo fin de grao (UDC.CIE). Bioloxía. Curso 2021/2022

Simple, tubular clusters from a single boundstone hand specimen, collected from loose material in the Permian (Lopingian) Cadeby Formation at Hazel Lane Quarry, Doncaster Metropolitan Borough, are tentatively identified as the serpulid worm, Filograna sp. A. The tubes are calcareous, found in vertical clusters, with some short sections growing horizontally, and with external diameters between 0.6 and 1 mm. Recent work on the Permian Tethyan deposits of Italy have identified occurrences of the genus Filograna from before the Permian–Triassic extinction, but the importance of this example is its provenance in the Zechstein English Shelf biota, where reported occurrences of Serpulidae have been rare.

Ecosystem engineers are predicted to have stronger facilitative effects when environmental stress is higher. Here we examined whether facilitation of the invasive porcelain crab Petrolisthes elongatus by the ecosystem engineering serpulid tube worm Galeolaria caespitosa increased with wave exposure. Petrolisthes occurs beneath intertidal boulders which often have a high cover of Galeolaria on their underside. Surveys across nine sites demonstrated Petrolisthes abundance beneath boulders increased with wave exposure and Galeolaria cover, although only when the habitat matrix beneath boulders was rock or mixed rock and sand. Moreover, as wave exposure increased, the strength of relationship between Petrolisthes abundance and the surface area of Galeolaria also increased. Experimentally, the presence of Galeolaria on the underside of boulders increased Petrolisthes abundance by 50% compared to boulders lacking Galeolaria. Our findings suggest the facilitative role of Galeolaria is stronger at more wave-exposed sites, which appears to contribute to a higher abundance of invasive Petrolisthes.

Small fionid nudibranch specimens collected within a Chaetopterus sp. tube worm are described here as a new species Tenellia chaetopterana sp. nov. This case is the first example of symbiotic association between a mollusk and an annelid host amongst cladobranch sea slugs. The external morphology of this species suggests it is adapted for living inside the worm’s tube: flattened body, laterally directed cerata and rhinophores, and wide foot. Molecular data, including partial sequences of mitochondrial COI and 16S and nuclear H3 genes, indicates that this species is distinct from other members of the genus Tenellia as well as other fionids. The species is close to the coral-feeding fionids of the genus Tenellia (formerly in genus Phestilla) in several morphological characters such as general radula morphology, absence of cnidosacs, and flattened body shape, as well as by molecular data. Tenellia chaetopterana sp. nov. has unique biology, implicating possible diversity previously overlooked by nudibranch faunistic studies.

Biological adhesion occurs in various circumstances. Differences of sessile organisms in size, shape, physiology, lifecycle, living environment, and phylogenic relationship would have different design implications in their adhesives, and the structures and mechanisms have yet to be properly unraveled at the molecular level. This chapter focused on the structure and mechanism of underwater adhesion and adhesives of three representative aquatic organisms, barnacle, mussel and tube worm, and the conceptual gap between chemical synthetic adhesives and bio-molecular ones was discussed. Collectively, it was proposed that the combination of unraveling the natural system and the design of analogous protein/peptide-based materials may eventually fill the gap between bio-molecular materials and synthetic chemical polymers.

Tube worms and phytobenthic assemblages in three infralittoral and shallow circalittoral Mediterranean benthic communities developed between 5 and 35 m depth at Punta del Lazzaretto (Giglio Island, Central Thyrrenian sea) were investigated. Despite being three algae-dominated habitats, these displayed different covering both in terms of algal layers and algal morphologies, reflecting different structural organizations. Twenty-eight serpulid taxa have been reported, increasing both diversity and density values from most photophilic to most sciaphilous habitats. Multivariate analyses showed how algal thalli and tube worm assemblages were strongly correlated; substrata are influenced both physically and biologically, providing different conditions for tube worm settlement.

Ficopomatus enigmaticus (Fauvel 1923) is a reef-building serpulid polychaete that is found in warm and temperate estuaries across the globe. This ecosystem engineer causes ecological and socio-economic impacts in invaded systems through efficient filtering of the water column and the formation of large calcareous reefs. As such it is important to monitor F. enigmaticus invasions and track changes in distribution and abundance. Although recent genetic studies have highlighted cryptic sympatric species within invasions previously ascribed to F. enigmaticus the genetic status in South Africa remains unresolved. This study provides an assessment of the invasion by this tube worm in three estuaries of conservation importance in the Western Cape, South Africa. Through the use of historical data, the trajectories of these invasions were considered. Zandvlei Estuary supported the largest standing stock (29 194.22 kg) while Berg River Estuary supported only 3.39 kg. It was notable that in both estuaries the worm was almost totally confined to artificial substrata. Despite the presence of large intact reefs in Milnerton Lagoon, no live worms were recorded in 2019. Comparisons with historical data revealed that populations have declined in all three estuaries. These results highlight the need for routine monitoring of Ficopomatus populations. It is suggested that episodic removal of the small reefs from Berg River Estuary could minimise spread within the estuary and prevent the negative impacts known from elsewhere. Strategic removal from Zandvlei Estuary, and Milnerton Lagoon should the worm be detected again, could limit its negative impacts in these systems while retaining the benefit of enhanced water quality associated with this prolific filter feeder.

Owing to high sample complexity, metaproteomic investigations on bacteria-animal symbioses with two or more uncultured partners can be challenging. A selective isolation or enrichment of distinct (sub-)populations within those consortia can solve this problem. Subsequent discrete proteomic analyses benefit from increased sample purity and higher proteome coverage for each of the individual organisms. Here, we describe centrifugation-based methods that allow for a separation of the host and its bacterial symbiont population(s), or even for an enrichment of distinct symbiotic cell cycle stages in the deep-sea mussels Bathymodiolus azoricus and B. thermophilus, the gutless oligochaete Olavius algarvensis and the deep-sea tube worm Riftia pachyptila, respectively.

Recent developments in marine drug discovery from three South African marine invertebrates, the tube worm Cephalodiscus gilchristi, the ascidian Lissoclinum sp. and the sponge Topsentia pachastrelloides, are presented. Recent reports of the bioactivity and synthesis of the anti-cancer secondary metabolites cephalostatin and mandelalides (from C. gilchristi and Lissoclinum sp., respectively) and various analogues are presented. The threat of drug-resistant pathogens, e.g., methicillin-resistant Staphylococcus aureus (MRSA), is assuming greater global significance, and medicinal chemistry strategies to exploit the potent MRSA PK inhibition, first revealed by two marine secondary metabolites, cis-3,4-dihydrohamacanthin B and bromodeoxytopsentin from T. pachastrelloides, are compared.

Ferritin, a multimeric cage-like enzyme, is integral to iron metabolism across all phyla through the sequestration and storage of iron through efficient ferroxidase activity. While ferritin sequences from ∼900 species have been identified, crystal structures from only 50 species have been reported, the majority from bacterial origin. We recently isolated a secreted ferritin from the marine invertebrate Chaetopterus sp. (parchment tube worm), which resides in muddy coastal seafloors. Here, we present the first ferritin from a marine invertebrate to be crystallized and its biochemical characterization. The initial ferroxidase reaction rate of recombinant Chaetopterus ferritin (ChF) is 8-fold faster than that of recombinant human heavy-chain ferritin (HuHF). To our knowledge, this protein exhibits the fastest catalytic performance ever described for a ferritin variant. In addition to the high-velocity ferroxidase activity, ChF is unique in that it is secreted by Chaetopterus in a bioluminescent mucus. Previous work has linked the availability of Fe2+ to this long-lived bioluminescence, suggesting a potential function for the secreted ferritin. Comparative biochemical analyses indicated that both ChF and HuHF showed similar behavior toward changes in pH, temperature, and salt concentration. Comparison of their crystal structures shows no significant differences in the catalytic sites. Notable differences were found in the residues that line both 3-fold and 4-fold pores, potentially leading to increased flexibility, reduced steric hindrance, or a more efficient pathway for Fe2+ transportation to the ferroxidase site. These suggested residues could contribute to the understanding of iron translocation through the ferritin shell to the ferroxidase site.

Strain ER-Te-48 isolated from a deep-ocean hydrothermal vent tube worm is capable of resisting and reducing extremely high levels of tellurite, tellurate, and selenite, which are used for respiration anaerobically. Tellurite and tellurate reduction is accomplished by a periplasmic enzyme of 215 kDa comprised of 3 subunits (74, 42, and 25 kDa) in a 2:1:1 ratio. The optimum pH and temperature for activity is 8.0 and 35 °C, respectively. Tellurite reduction has a V max of 5.6 µmol/min/mg protein and a K m of 3.9 mM. In the case of the tellurate reaction, V max and K m were 2.6 µmol/min/mg protein and 2.6 mM, respectively. Selenite reduction is carried out by another periplasmic enzyme with a V max of 2.8 µmol/min/mg protein, K m of 12.1 mM, and maximal activity at pH 6.0 and 38 °C. This protein is 165 kDa and comprised of 3 subunits of 98, 44, and 23 kDa in a 1:1:1 ratio.

Evidence for abrupt coastal uplifts has been found in emerged sessile assemblages in a sea cave at the southern end of the Izu Peninsula, central Japan. We identified five sessile assemblage zones: Zones I to V, in ascending order. The uppermost zone (Zone I), located at an elevation of 2.7–3.5 m above the present-day mean sea level (amsl), is a hard massive shellcrust consisting mainly of the barnacles Chthamalus challenger and the tube worm Pomatoleios kraussii. Zone II, at 2.35–2.7 m amsl, is dominated by well-preserved individuals of C. challenger. Zone III, at 2.0–2.35 m amsl, is strongly eroded and consists mainly of C. challenger and P. kraussii. Zone IV, at 1.6–2.0 m amsl, is characterized by the co-occurrence of very fresh shells of C. challenger and P. kraussii. Zone V (the lowest zone), at 1.0–1.60 m amsl, is characterized by the co-occurrence of very fresh shells of Saccostrea kegaki and P. kraussii, and by the absence of C. challenger. Radiocarbon dating by accelerator mass spectrometry (AMS) and the presence of modern taxa in the sessile assemblages suggest that three episodes of coastal uplift have occurred in the area, during AD 570–820, AD 1000–1270, and AD 1430–1660, with magnitudes of 0.9–2.0 m, 0.3–0.8 m, and 1.9–2.2 m, respectively.

Examples of simple phenotypic relationships, where variation in one stage directly affects phenotypic variation in a subsequent stage, are documented in most taxa. However, environmental variation can mediate these relationships, and because most organisms develop through multiple life-history stages, each stage-dependent environment has the potential to create new phenotypic relationships and interfere with existing relationships. Despite the likelihood of complex phenotypic interactions among life-history stages, and the potential for these interactions to resonate throughout the life history, there are few tests of the problem and few predictions of how these phenotypic interactions are resolved. Here, we examined the interdependent effects of three sources of phenotypic variation on the performance of a marine tube worm. Sources of phenotypic variation included: offspring size, larval nutrition and juvenile density. We found highly context-dependent relationships between these factors and postmetamorphic performance. Within the overarching result of context dependence, we found: interactions could negate and reverse relationships; early-stage phenotypes could persist to postmetamorphosis; later, life-history environments could contribute more to recruit phenotypes than early-stages; and late-stage variation can depend on early-stage phenotypes. Our results demonstrate that while simple phenotypic links among the egg, larval and postrecruitment stages may be common and important contributors to growth and survival, these relationships should be considered in the context of the organism's life experience. Each phenotypic link among stages can potentially be complex and depend on prior experience, current state and the subsequent environments experienced.

Bivalve aquaculture currently utilizes two main farming practices: intertidal (beach) and deep-water (suspended) culture. Although suspended culture offers a number of advantages during both nursery and grow-out phases, two commonly encountered issues – shell deformities and biofouling – lead to reduced seed and final product quality in some species and preclude other species from being cultured in suspension. None of the existing strategies for controlling these issues is efficient and fully reliable. In this study we tested the efficiency of two new methods for controlling biofouling and shell deformities in suspended culture of bivalves using basket cockle Clinocardium nuttallii as a model species. The first method involved a short-term increase in bivalve stocking density during peak plankton concentrations and biofouling settlement periods. The second method comprised adding artificial growth medium (expanded clay aggregate) to culture enclosures. Both high-density and growth medium treatments significantly reduced the incidence of C. nuttallii shell deformities compared to the control treatment (by 86 and 72%, respectively). This finding suggests that clam shell deformities in suspended culture primarily develop due to the lack of structural support normally offered by the substratum. Both treatments also significantly reduced barnacle fouling rate (by 67 and 83%, respectively). Additionally, growth medium treatment led to a significant reduction in tube worm fouling, as well as combined fouling rate and intensity, but it was less effective in controlling sponge fouling. Overall, both high-density and growth medium treatments showed promise in reducing the incidence of shell deformities and the amount of biofouling on C. nuttallii in suspended culture. These treatments are inexpensive, environmentally-friendly, readily available to shellfish growers, and may be further refined and adapted for a variety of cultured bivalve species. They have the potential to improve the efficiency of suspended grow-out systems and extend the option of suspended culture to bivalve species currently grown on the beach only.

This paper reports on a study of the associated epibiota of the spider crab, Hyastenus hilgendorfi (De Man, 1887), inhabiting the Suez Canal. Ten species of macro-epibionts were identified. The barnacle Balanus amphitrite , the tunicate Microcosmus sp., and the tube worm Hydroides elegans were the major epibionts recorded. The carapace was the most covered body part followed by the chelae in males and the pereopods in non-ovigerous and ovigerous females. Considerable variation in the various covering materials was found between males, non-ovigerous, and ovigerous females. Seasonality of coverage occurred, with males and non-ovigerous females heavily covered in winter but without coverage in spring. The extremely heavy encrustation in this species is unusual among pisid crabs. Ce travail porte sur l'etude des epibiontes associes a l'araignee de mer, Hyastenus hilgendorfi (De Man, 1887), vivant dans le canal de Suez. Dix especes de macro-epibiontes ont ete identifiees. Le cirripede Balanus amphitrite , le tunicier Microcosmus sp., et le polychete Hydroides elegans sont les principaux epibiontes identifies. La carapace est la partie du corps la plus couverte, puis ce sont les pinces chez les mâles et les pereiopodes chez les femelles non-ovigeres et ovigeres. Une variation considerable concernant les divers materiaux recouvrant les specimens a ete observee entre les mâles, les femelles non-ovigeres et ovigeres. Une variation saisonniere existe, les mâles et les femelles non-ovigeres presentant une lourde charge en epibiontes pendant l'hiver, mais en etant depourvus au printemps. L'incrustation extremement lourde chez cette espece est inhabituelle chez les crabes Pisidae.

A new species of the palaemonid shrimp genusPericlimenes, P. cannaphilus, is described from upper bathyal hydrothermal vents of the Bonin-Mariana Arc in the north-western Pacific at depths of 392–456 m. A symbiotic relationship between the new shrimp species and a siboglinid tube wormLamellibrachia satsumais suggested by their simultaenuous collection and further observationsin situ. Similarities in the morphology and symbiotic association suggest that the new species is closely related toP. thermohydrophilus, also associated withL. satsumain shallow hydrothermal vent fields in Kagoshima Bay, southern Japan, but differences in the rostral shape, the position of the epigastric tooth on the carapace, and the development of the hepatic tooth on the carapace morphologically differentiate the two species. Phylogenetic analysis based on sequences of the mitochondrial DNA COI gene supports the recognition of two clades corresponding to these two taxa.

Of the approximately 350 described species of serpulid polychaetes, only Marifugia cavatica inhabits fresh water. It is distributed in ground waters of the Dinaric Karst in northeastern Italy, Slovenia, Croatia, and Bosnia and Hercegovina. Five other serpulid species, comprising the genus Ficopomatus, are found in brackish water locations worldwide; otherwise serpulids are all marine organisms. We re‐describe M. cavatica and examine the fine structure of its chaetae with SEM as well as summarise its distribution. The morphology of Marifugia provides an ambiguous indication of its phylogenetic relationships, thus DNA sequence data was also used. Phylogenetic analysis of nuclear rDNA 18S and 28S sequences using maximum parsimony, maximum likelihood and Bayesian analyses places Marifugia as a sister group to a clade of brackish‐water Ficopomatus species. Osmoconformity and penetration into non‐marine waters hence appears to have taken place once in the evolutionary history of Serpulidae. The transit...

Submarine caves at the Cape of Otranto (SE, Italy) host pseudostalactites. Only recently have they been recognised as originating mainly from the marine tube worm Protula tubularia (Serpulidae, Polychaeta). Their formation depends on the adaptability, life history and behaviour of that species in the cave habitat. The dating of calcareous tubes in the pseudostalactite core represents the first attempt to describe the formation of such bio-construction, and the gregarious behaviour of the species. Calcareous tubes along the core axis of three pseudostalactites removed from the cave lu Lampiu`ne (Otranto, South East Italy) have been dated using the 14C method. Measures established ages from 2600 to 5000 years for the three structures. This extremely long period (when compared with the life span of each worm) suggests that each tube aggregation is the result of punctuated growth periods alternated with long standstill phases. At the end of a growth period, each tube aggregation was covered with a brownish concretion, completing the pseudostalactite.

Hydroides elegans is a major fouling organism in tropical waters around the world, including Pearl Harbor, Hawaii. To determine the importance of initial surface characteristics on biofilm community composition and subsequent colonization by larvae of H. elegans, the settlement and recruitment of larvae to biofilmed surfaces with six different initial surface wettabilities were tested in Pearl Harbor. Biofilm community composition, as determined by a combined approach of denaturing gradient gel electrophoresis and fluorescence in situ hybridization, was similar across all surfaces, regardless of initial wettability, and all surfaces had distinct temporal shifts in community structure over a 10 day period. Larvae settled and recruited in higher numbers to surfaces with medium to low wettability in both May and August, and also to slides with high wettability in August. Pearl Harbor biofilm communities developed similarly on a range of surface wettabilities, and after 10 days in Pearl Harbor all surfaces were equally attractive to larvae of Hydroides elegans, regardless of initial surface properties.

Aggregations of the tube worm Serpula vermicularis were discovered in July 2006 in the upper basin of Loch Teacuis, Morvern, Western Scotland. Serpula vermicularis aggregations have been previously described only from five other locations in Europe. Occurrence of the habitat in Loch Teacuis was mapped by scuba diving. Small aggregations of mean (±SD) height 26±9 cm (n=59) and mean diameter 19±10 cm (n=59) were found growing on rocks and amongst kelp holdfasts around the margins of the loch at a depth of 1–5 m. A brief sublittoral survey of Loch Teacuis carried out in 1996 did not find any S. vermicularis aggregations despite the fact that one of the transects dived was very close to where aggregations were found during this study. It is possible that the transect passed through an area where no serpulid aggregations were present, but more likely that the serpulid aggregations in Loch Teacuis have only been developing since 1996.

Chemosynthetic ecosystems teeming with tubeworm colonies were discovered at hydrothermal vents in the Galapagos Ridge in 1977 and at cold seeps at the base of the Florida Escarpment in 1984. As a result of these reports a number of fossil examples were identified in the rock record. One such assemblage was recognized in the Western Interior Seaway, in the Middle Campanian Pierre Shale Formation, where previous researchers noted siboglinid (formerly vestimentiferan and pogonophoran) tubeworms in methane-derived nodular limestones with tubules. On the inside these tubules have an outer ring of micrite with microparticulate siliciclastic materials and a core of calcite cement. Alternatively, they have an outer annulus of calcite cement and a core of microparticulate siliciclastic materials with calcite cements. Interestingly, the cemented cores can contain meniscate and vesiculate fabrics in association with the microparticulate linings. With this evidence we infer that the tubules preserve fabrics of former gas bubbles; the microparticulate linings are deposits that accumulated on the walls of the tubules as fluids streamed through them. Methane bubbles would have carried adhered siliciclastic microparticles and bubble wakes would have held entrained microparticles. We, thus, interpret the tubules to be former, small, subseafloor conduits along which fluid and particulate transport occurred. Particle transport by gas bubbles is a well-known process in chemical and mineral industries. Our observations highlight this process for the first time in an ancient geologic conduit system and provide a mechanism for maintaining particulate plumes that accompany effusing methane streams at modern seeps and vents.

The phylogenetic relationships were analysed based on nucleotide sequences of a mitochondrial gene for cytochrome c oxidase subunit I (COI) for the vestimentiferan tube worm Lamellibrachia juni, which inhabits three extremely acidic hydrothermal vent fields in the South Pacific: the TOTO Caldera in the South Mariana Volcanic Arc, the DESMOS site in the Manus Basin, and the Brothers Caldera in the Kermadec Arc. Six haplotypes were obtained from 34 lamellibrachiids from the three sites. Each haplotype was obtained only from a single site, which suggests that the three populations have been isolated from each other. Haplotypes from the DESMOS site formed a monophyletic cluster. All ten individuals from the TOTO Caldera were classified into the same haplotype, which was shown to form a monophyletic cluster with one of three haplotypes from the Brothers Caldera. The population in the Brothers Caldera was shown to consist of two genetically distinct groups.

he mature sperm morphology and spermatogenesis ultrastructure have been fully described in Pomatoleios krassii, which is a spirobranchian polychoaete attached to rocks, wrecked boats, rods and hard substrates at some polluted sites on Suez Bay coast. Sperms develop in the coelom as free-floating plasmodial cells. At the end of spermatogenesis, mature sperms float freely in the coelom. The spermatogonia are relatively large in size (13 µ in diameter). The spermatozoon of the present species differs from that of other polychaete species by having a large head (6 µ in length) formed of rounded nucleus and large acrosome which forms a large curved terminal cap on the nucleus. This may be an indication that fertilization occurs by some mechanisms that limit exposure of such fragile gametes to any possiple pollution. Meanwhile, female of P.kraussii protects its eggs with a jelly mass attached to the branchial crown, and the sperm is required to penetrate the matrix of egg mass. The large pair of mitochondria (2 µ in diameter) and presence of two pairs of proximal and distal centrioles which are not recorded so for in previous studies, as well as the long tail may be correlated with a characteristic movement of the sperm to reach female branchial crown, where the egg masses are found.

Dense lawns of tube worms modify their immediate environment. They alter sediment properties, offer refuge from predation and provide a settlement surface for larvae and small organ- isms. The terebellid polychaete Lanice conchilega is among the tube dwellers that, when present at high densities, alter the community structure of other benthic fauna. However, L. conchilega often occurs individually or at low densities over large areas, and it is not known whether single tubes also affect the surrounding fauna. In this study a low density population of L. conchilega (15.7 ± 15.6 m -2 ) was investigated on an exposed beach in South Wales, UK, from May 1998 to April 1999. Effects of single tubes and small groups of 2 to 5 tubes on the benthic community were examined over 1 yr. The relationship between L. conchilega and an associated amphipod (Urothoe poseidonis) was studied more closely in the field and the laboratory. Of a total of 56 species, 27 were found exclusively in sam- ples with L. conchilega tubes. In comparison with tube-free samples, species richness and abundance of individuals was significantly higher in samples containing L. conchilega tubes. The community structure differed significantly between samples containing groups of tubes and tube-free samples in 10 out of 11 cases and in 9 of 11 cases for samples with 1 tube compared to samples with no tubes. Throughout the year, the polychaete Eumida sanguinea and the haustoriid amphipod U. poseidonis benefited from the presence of L. conchilega. E. sanguinea lives among the fringe filaments of the tube top, and U. poseidonis inhabits areas deep in the sediment in close vicinity to the tube. Labora- tory experiments indicated that, unlike other haustoriids, the amphipod is not prone to bentho- pelagic migration but remains in the sediment for long periods of time and may benefit from an improved oxygen supply arising from L. conchilega's activity inside the tube. It is concluded that not only groups of tubes, but also single polychaete tubes bioengineer their environment.

Twenty two specimens of vestimentiferan tube worms Riftia pachyptila were collected from Guaymas Basin. The distribution of ten trace metals in trophosome and vestimentum was investigated. Highest mean concentrations of Co, Cu and Fe were detected in the trophosome; while higher mean levels of Cd, Hg, Mn, Ni, Pb and Zn were measured in the vestimentum. However, the t-student test resulted in significant differences ( p 0.05 ) only in the case of Co. Cd and Fe concentrations in vestimentum increased accordingly with the size of specimens. With respect to vent fluids, extreme uptake seems to be a characteristic of R. pachyptila in the case of Cu and Zn but not for the rest of the analyzed metals. Studies concerning accumulation mechanisms of trace metals in R. pachyptila are needed, particularly on the capacity of this organism to tolerate elevated levels of elements considered as non-essential.

The Gulf of Mexico supports dense aggregations of megafauna associated with hydro- carbon seeps on the Louisiana Slope. The visually dominant megafauna at the seeps — mussels and tube worms — derive their nutrition from symbiotic relationships with sulfide or methane-oxidizing bacteria. The structure of the tube worm aggregations provide biogenic habitat for numerous species of heterotrophic animals. Carbon, nitrogen and sulfur stable isotope analyses of heterotrophic fauna collected with tube worm aggregations in the Green Canyon Lease area (GC 185) indicate that most of these species derive the bulk of their nutrition from chemoautolithotrophic sources. The isotope analyses also indicate that although 2 species may be deriving significant nutritional input from the bivalves, none of the species analyzed were feeding directly on the tube worms. Grazing gastropods and deposit-feeding sipunculids were used to estimate the isotopic value of the free-living chemoau- tolithotrophic bacteria associated with the tube worms (δ 13 C -32 to -20‰; δ 15 N 0 to 7‰; δ 34 S -14 to -1‰). The use of tissue δ 34 S analyses in conjunction with tissue δ 13 C and δ 15 N led to several insights into the trophic biology of the communities that would not have been evident from tissue stable C and N analyses alone.