Chemosymbiotic bivalves from the mud volcanoes of the Gulf of Cadiz, NE Atlantic, with descriptions of new species of Solemyidae, Lucinidae and Vesicomyidae

The chemosymbiotic bivalves collected from the mud volcanoes of the Gulf of Cadiz are reviewed. Of the thirteen species closely associated with chemosynthetic settings two Solemyidae, Solemya (Petrasma) elarraichensissp. n. and Acharax gadiraesp. n., one Lucinidae, Lucinoma asapheussp. n., and one Vesicomyidae, Isorropodon megadesmussp. n. are described and compared to close relatives of their respective families. The biodiversity and distribution of the chemosymbiotic bivalves in the Gulf of Cadiz are discussed and compared to the available information from other cold seeps in the Eastern Atlantic and Mediterranean. Although there is considerable similarity at the genus level between seep/mud volcano fields in the Eastern Atlantic and Mediterranean, there is little overlap at the species level. This indicates a high degree of endemism within chemosymbiotic bivalve assemblages.     

Organization and microanatomy of the Sclerolinum contortum trophosome (Polychaeta, Siboglinidae)

The trophosome-an organ especially evolved to accommodate symbiotic bacteria-is a key character of the polychaete family Siboglinidae. Astonishingly, the trophosomes vary in organization and origin between the different siboglinid taxa. The trophosome of the small genus Sclerolinum was nearly unknown until now. Here we investigated the trophosome of S. contortum from the Gulf of Mexico, using light and electron microscopy. We show that this organ derives from the visceral mesoderm and propose that the trophosome of the sister clade Vestimentifera and Sclerolinum is a homologous character. Like that of juvenile vestimentiferans, the trophosome of Sclerolinum trophosome is simply organized. This study reveals that the Sclerolinum trophosome exhibits two regions that differ in the organization of host tissue and the size and shape of the symbionts. We suggest that a specific cell cycle within the symbiont-housing organ is directed along the longitudinal body axis, with a region of proliferation anteriorly and a region of degradation posteriorly. Using Raman microspectroscopy we demonstrate that the endosymbionts of S. contortum from the Gulf of Mexico contain sulfur vesicles, and we argue for a chemoautotrophic sulfur-oxidizing metabolism.     

Surveillance of Viruses in Wild Fish Populations in Areas around the Gulf of Cadiz (South Atlantic Iberian Peninsula)

This report describes a viral epidemiological study of wild fish around the Gulf of Cadiz (southwestern Iberian Peninsula) and is focused on infectious pancreatic necrosis virus (IPNV), viral hemorrhagic septicemia virus (VHSV), and viral nervous necrosis virus (VNNV). One fish species (Chelon labrosus) was sampled inside the gulf, at the mouth of the San Pedro River. Another 29 were sampled, in three oceanographic campaigns, at sites around the Bay of Cadiz. The fish were processed individually and subjected to isolation in cell culture and molecular diagnosis. VHSV was not isolated from any species. Thirteen IPNV-type isolates were obtained from barracuda (Sphyraena sphyraena), axillary seabream (Pagellus acarne), common two-banded seabream (Diplodus vulgaris), common pandora (P. erythrinus), Senegal seabream (D. bellottii), and surmullet (Mullus surmuletus). Six VNNV isolates were obtained from axillary seabream, common pandora, black seabream (Spondyliosoma cantharus), red mullet (Mullet barbatus), Lusitanian toadfish (Halobatrachus didactylus), and tub gurnard (Chelidonichtys lucerna). In the river mouth, viruses were detected only after reamplification, obtaining prevalence percentages of IPNV and VNNV (44.4 and 63.0%, respectively) much higher than those observed in the oceanographic campaigns (25.7 and 19.6%, respectively). The opposite results were obtained in the case of VHSV after reamplification: 11.1% in the river mouth and 43.6% in the oceanic locations. Analyzing the results with respect to the proximity of the sampling sites to the coast, an anthropogenic influence on wild fish is suggested and discussed. The type of viruses and the presence of natural reassortants are also discussed.     

Distribution and diversity of the Syllidae (Annelida: Polychaeta) from the Mexican Gulf of Mexico and Caribbean

The objective of this study was to contribute to the knowledge of the syllids distributed in the eastern coasts of Mexico (Gulf of Mexico and Caribbean) taking into consideration their composition, distribution and diversity. Sampling was done at 77 stations including 49 in soft bottoms (terrigenous and carbonate sediments), and 28 in hard bottoms (coralline substrates) sampled in nine reef zones included in three reef systems (Veracruz, Campeche and Cozumel). In all 2084 individuals were collected (13.5% in soft sediments and 86.4% in coralline areas). Forty-five species were identified: 31 in soft bottoms and 38 in corals, with 21 species common to both types of environments. In soft bottoms, the highest species richness and diversity were found in the Carbonate Zone, while syllids were uncommon in the Terrigenous Zone. In hard bottoms, the highest density, species richness and diversity values were found in the Veracruz Reef System, followed by the Campeche Bank and Cozumel Island Reef Systems. The dominant species in soft bottoms were Haplosyllis spongicola, Exogone lourei, Typosyllis cornuta and T. papillosus, whereas T. alosae, T. corallicola, T. cornuta and H. spongicola dominated in hard bottoms. The importance and success of the syllids in both soft bottoms and reef environments, particularly in those of the Gulf of Mexico is emphasized.     

The metatrochophore of a deep-sea hydrothermal vent vestimentiferan (Polychaeta: Siboglinidae)

Vestimentiferans (Siboglinidae, Polychaeta) live as juveniles and adults in an obligate mutualistic association with thiotrophic bacteria. Since their development is aposymbiotic, metatrochophores of vestimentiferans from the East Pacific Rise colonizing deep-sea hydrothermal vents are infected with the specific symbiont, develop the trophosome, and reduce their digestive system. To gain insight into the anatomy and ultrastructure and to compare this stage with metatrochophores from other siboglinids, we serial sectioned and reconstructed three specimens using light and transmission electron microscopy. The metatrochophore was composed of a prostomium, a small peristomium, two chaetigers (or two chaetigers and one additional segment without chaetae), and a minute pygidium. A digestive system and an intraepidermal nervous system were developed. Larval organs such as the prototroch, the neurotroch, and an apical organ were present, along with juvenile/adult organs such as tentacles, uncini, pyriform glands, and the anlage of the nephridial organ. We propose that in vestimentiferans, the vestimentum is the head arising from the prostomium, peristomium, and the anterior part of the first chaetiger. In frenulates, in contrast, the head is composed on the one hand of the cephalic lobe arising from the prostomium and on the other of the forepart developing from the peristomium and the anterior part of the first chaetiger. In frenulates the muscular septum between the forepart and trunk develops later than the first two chaetigers. Since this septum has no counterpart in vestimentiferans, the forepart-trunk border of frenulates is not considered homologous with the vestimentum-trunk border in vestimentiferans. The obturacular region in vestimentiferans does not appear to be a body region but rather the head appendages arising from the first chaetiger. In contrast, the tentacles in frenulates are prostomial head appendages. In both taxa, the trunk is the posterior part of the first chaetiger, and the opisthosoma is the following chaetigers and the pygidium. Comparisons with other polychaetes suggest that two larval segments are autapomorphic for the monophyletic Siboglinidae.     

Recent benthic foraminiferal assemblages in deep high-energy environments from the Gulf of Cadiz (Spain)

The benthic environment in the Gulf of Cadiz, north-eastern Atlantic, is strongly affected by the Mediterranean outflow water undercurrent (MOW) which flows northwards along the western Iberian Margin at 500–1500 m water depth. Foraminiferal census counts of living and dead assemblages from 27 surface samples ranging from 103 to 1917 m water depth, and the examination of hard substrates reveal a close correlation of the fauna with the local hydrography and sediment facies. Four different faunal groups are separated by factor analysis of the living fauna. Assemblage 1 contains typical lower slope species and dominates samples from the lower MOW core layer and in the North Atlantic deep water below. Shelf edge foraminifera are common in assemblage 2a which shows the highest proportions in samples from 103 to 272 m. Assemblage 2b is dominated by upper slope species and suspension-feeders that are frequent in the upper MOW core layer and in distal settings between 396 and 901 m. Species from assemblage 3 prefer epibenthic habitats and are recorded with high proportions exclusively in the immediate flow paths of the upper MOW between 496 and 881 m. Colonisation structures and species composition of epibenthic assemblages from the proximal facies largely differ from those in distal settings. In general, epibenthic foraminifers only use elevated substrates under the influence of near-bottom flow. Under high current velocities, epibenthic foraminifers prefer large and heavy objects. They colonise high attachment levels where a maximum yield of advected food particles can be achieved. In distal settings at lower flow velocities, the elevation height does not exceed 20 mm above the surrounding sediment surface. This level is related to a hydrologic transition layer with high concentrations of suspended particles. The comparison of microhabitat preferences and faunal structure under high and low current velocities reveal that substrate stability may be a confining environmental variable for endobenthic and shallow epibenthic foraminifers. The observations also indicate that the preferential settling height of epibenthic foraminifera is related to the highest lateral flux rates of food particles within reach from the sea floor. A dynamic selection of elevated microhabitats is only used by 7.8% of all species recognised in the Gulf of Cadiz area.     

New Fabriciola species (Polychaeta, Sabellidae, Fabriciinae) from the eastern Atlantic, with a description of sperm and spermathecal ultrastructure

New species in the genus Fabriciola Friedrich are described. Fabriciola is defined by a single synapomorphy, the presence of non-vascularized, ventral filamentous appendages. Otherwise the genus is variable, with differences among species in chaetae, eyes, and peristomial organization. The new species, Fabriciola flammula, F. liguronis and F. parvus , reflect this heterogeneity. Fabriciola liguronis has spermathecae in the radiolar crown of females, the first record of these structures in Fabriciola , but F. flammula and F. parvus lack spermathecae. Sperm ultrastructure in all three species share apomorphies with other fabriciins, but vary in other respects. Fabriciola may be paraphyletic, but material of the type species F. spongicola (Southern, 1921) has been unobtainable so far, and detailed study of this species is required to define the genus Fabriciola adequately.     

Sexual reproduction in three hermaphroditic deep-sea Caryophyllia species (Anthozoa: Scleractinia) from the NE Atlantic Ocean

The reproductive biology and gametogenesis of three species of Caryophyllia were examined using histological techniques. Caryophyllia ambrosia, Alcock 1898, C. cornuformis, Pourtales 1868, and C. sequenzae, Duncan 1873, were collected from the Porcupine Seabight and Rockall Trough in the NE Atlantic Ocean. These three ahermatypic solitary corals inhabit different depth ranges: C. cornuformis – 435–2000 m, C. sequenzae – 960–1900 m, and C. ambrosia – 1100–3000 m. All three species are hermaphroditic. Hermaphroditism in these species was found to be cyclical, with only one sex of gametes viable in any individual at any point in time, although gametes of both sexes were found together within a single mesentery. Once the viable gametes are spawned, the next sex of gametes continues to grow until mature, and so gametogenesis is a continuous cycle. Oocytes and spermacysts in all species increased in density towards the actinopharynx. Maximum fecundity for C. sequenzae was 940 oocytes per polyp, and for C. ambrosia 2900 oocytes per polyp. Fecundity could not be established for C. cornuformis. In all three species, individuals were asynchronous within populations, and production of gametes was quasi-continuous throughout the year. All species are hypothesised to have lecithotrophic larvae owing to their large oocyte sizes (C. cornuformis max – 350 μm; C. sequenzae max – 430 μm; C. ambrosia max – 700 μm). Both the average oocyte size and fecundity increased in species going down the depth gradient of the NE Atlantic.     

Phylogeny of the mud worm genus Marenzelleria (Polychaeta, Spionidae) inferred from mitochondrial DNA sequences

The taxonomy of the cryptic morphospecies of the mud worm genus Marenzelleria is particularly difficult and the phylogenetic relationship within the genus is unknown. Herein we reconstructed the phylogeny of all five species of this genus using sequence data of three mitochondrial genes (16SrDNA, cytochrome b, cytochrome oxidase subunit I) from 104 specimens out of 26 populations. For the three invasive species of the genus, Marenzelleria neglecta, M. viridis and M. arctia , individuals from native populations as well as from recently invaded populations were included. Nuclear 18S rDNA sequences were used to evaluate the appropriate outgroup taxon among several spionid polychaete species. The results supported the monophyly of Marenzelleria , and Malacoceros fuliginosus was found to be a suitable outgroup for the analysis of the mitochondrial gene segments. All phylogenetic reconstructions revealed a basal position of M. arctia and M. wireni , which have primarily Arctic distribution, with M. arctia obtaining the most basal position. Together with the present-day distribution of the species, this indicates an origin of the genus in the Arctic region. The relationship of the species M. neglecta , M. viridis and M. bastropi could not be resolved sufficiently due to genealogical discordance that might reflect relatively young cladogenetic events.     

Phylogenetic relationships among NE Atlantic Plocamionida Topsent (1927) (Porifera, Poecilosclerida): under-estimated diversity in reef ecosystems

Background

Small and cryptic sponges associated with cold-water coral reefs are particularly numerous and challenging to identify, but their ecological and biochemical importance is likely to compete with megabenthic specimens.

Methodology/Principal Findings

Here we use a combination of the standard M1M6 and I3M11 partitions of the COI fragment, partial rDNA 28S sequences and morphology to delineate small encrusting Plocamionida species. In total, 46 specimens were retrieved from seven shallow to deep-water coral locations, crossing 3,000 km along the European margins. Our work provides evidence that the Plocamionida ambigua f. tylotata and f. grandichelata can be considered valid species, whereas Plocamionida ambigua f. tornata corresponds to the species P. ambigua. Within the monophyletic group of Plocamionida, P. microcionides is shown as really divergent from the other taxa, and four putative new Plocamionida species are suggested.

Conclusions/Significance

This study shows that the use of molecular and morphological information in an integrative approach is a powerful tool for the identification of sponge species, and suggests that an under-estimated biodiversity of sponges occurs in cold-water coral reefs.     

A new species of Lepidasthenia (Polychaeta, Polynoidae) from Canary Islands

Lepidasthenia medanensis spn, is described from subtidal sandy bottom and beds of Cymodoceanodosa on the south west coast of Tenerife, Canary Islands.     

A new species of Streptospinigera Kudenov, 1983 (Polychaeta, Syllidae, Anoplosyllinae) from the Arctic and north-western Atlantic with a key to all species of the genus

Since 2007, the ArcticNet and CHOne programmes have allowed researchers, through oceanographic surveys on the ‘NGCC Amundsen’, to collect yearly benthic samples in the Canadian High Arctic. From the Beaufort Sea to the Bay of Baffin, more than 262 samples have been collected and analysed to provide essential data to explain patterns of biodiversity in the Canadian Arctic archipelago. Whereas common species are well known, other more rare species belonging to a few minute species groups, with debatable taxonomy, were set aside for further analyses. Focusing on Syllidae (Annelida, Polychaeta), we found and describe here Streptospinigera niuqtuut sp. nov. from muddy habitats of bathyal Arctic and continental slope beds of northern Atlantic coasts of United States between depths of 169 and 707 m. S. niuqtuut differs from congeneric species by unique dorsal simple chaetae of 1–5 chaetigers dorsally curved and distally rounded, with some sub-distal serration. This species may have frequently been reported from the region as Syllides longocirrata Ørsted 1845 but in fact are species of the genus Streptospinigera Kudenov 1983. We also transfer Streptosyllis templadoi San Martín 1984 to this genus and provide herein a key for the identification of all species of the genus.     

Oogenesis of Perinereis macropus Claparede, 1870 (Annelida, Polychaeta) in the Gulf of Gabes (Tunisia)

The polychaete Perinereis macropus (Claparède, 1870) (Nereididae) is present in the Gulf of Gabes, but its reproductive biology is unknown. An intensive study was conducted from August 2004 to July 2005 to characterize the life cycle of a population in the mouth of wadi Ferd in Gabes. The examination of sexual products allows us to describe the morphological oocytes aspects at different stages. The results show that P. macropus has an asynchronous oogenesis. Moreover, the biometric study of oocytes growth allows us to clarify the female sexual cycle. The female maturity occurs in April and the mature oocyte diameter is approximately 250+/-32.67 microm. However, spawning occurs in May, when the seawater temperature starts rising. We propose that the reproductive season stretches from March to June in the Gulf of Gabes.     

Some species of the genus Phyllodoce (Polychaeta) from Southern California

Five species of the genus Phyllodoce from Southern California are reviewed. A new subgenus (Aponaitides) is proposed and a new species, Phyllodoce cuspidata , is described. A key to the Southern California species is included.     

Three new species of Sphaerosyllis (Polychaeta, Syllidae) from mangrove habitats in Belize

Three new species of Sphaerosyllis Claparède, 1863, S. belizensis, S. longilamina , and S. parvoculata, are described from mangrove and adjacent shallow-water habitats of Twin Cays, Belize.     

Non-indigenous species (NIS) of polychaetes (Annelida: Polychaeta) from the Atlantic and Mediterranean coasts of the Iberian Peninsula: an annotated checklist

This study provides an updated catalogue of non-indigenous species (NIS) of polychaetes reported from the continental coasts of the Iberian Peninsula based on the available literature. A list of 23 introduced species were regarded as established and other 11 were reported as casual, with 11 established and nine casual NIS in the Atlantic coast of the studied area and 14 established species and seven casual ones in the Mediterranean side. The most frequent way of transport was shipping (ballast water or hull fouling), which according to literature likely accounted for the introductions of 14 established species and for the presence of another casual one. To a much lesser extent aquaculture (three established and two casual species) and bait importation (one established species) were also recorded, but for a large number of species the translocation pathway was unknown. About 25% of the reported NIS originated in the Warm Western Atlantic region, followed by the Tropical Indo West-Pacific region (18%) and the Warm Eastern Atlantic (12%). In the Mediterranean coast of the Iberian Peninsula, nearly all the reported NIS originated from warm or tropical regions, but less than half of the species recorded from the Atlantic side were native of these areas. The effects of these introductions in native marine fauna are largely unknown, except for one species (Ficopomatus enigmaticus) which was reported to cause serious environmental impacts. In other cases, the displacement of native species or economic damages are suspected.     

A remarkable diversity of bone-eating worms (Osedax; Siboglinidae; Annelida)

Background

We previously showed that mice lacking the high mobility group A1 gene (Hmga1-knockout mice) developed a type 2-like diabetic phenotype, in which cell-surface insulin receptors were dramatically reduced (below 10% of those in the controls) in the major targets of insulin action, and glucose intolerance was associated with increased peripheral insulin sensitivity. This particular phenotype supports the existence of compensatory mechanisms of insulin resistance that promote glucose uptake and disposal in peripheral tissues by either insulin-dependent or insulin-independent mechanisms. We explored the role of these mechanisms in the regulation of glucose homeostasis by studying the Hmga1-knockout mouse model. Also, the hypothesis that increased insulin sensitivity in Hmga1-deficient mice could be related to the deficit of an insulin resistance factor is discussed.

Results

We first show that HMGA1 is needed for basal and cAMP-induced retinol-binding protein 4 (RBP4) gene and protein expression in living cells of both human and mouse origin. Then, by employing the Hmga1-knockout mouse model, we provide evidence for the identification of a novel biochemical pathway involving HMGA1 and the RBP4, whose activation by the cAMP-signaling pathway may play an essential role for maintaining glucose metabolism homeostasis in vivo, in certain adverse metabolic conditions in which insulin action is precluded. In comparative studies of normal and mutant mice, glucagon administration caused a considerable upregulation of HMGA1 and RBP4 expression both at the mRNA and protein level in wild-type animals. Conversely, in Hmga1-knockout mice, basal and glucagon-mediated expression of RBP4 was severely attenuated and correlated inversely with increased Glut4 mRNA and protein abundance in skeletal muscle and fat, in which the activation state of the protein kinase Akt, an important downstream mediator of the metabolic effects of insulin on Glut4 translocation and carbohydrate metabolism, was simultaneously increased.

Conclusion

These results indicate that HMGA1 is an important modulator of RBP4 gene expression in vivo. Further, they provide evidence for the identification of a novel biochemical pathway involving the cAMP-HMGA1-RBP4 system, whose activation may play a role in glucose homeostasis in both rodents and humans. Elucidating these mechanisms has importance for both fundamental biology and therapeutic implications.     

On two new species of Mesochaetopterus (Polychaeta) from the Brazilian coast

Es wurden zwei neue Arten von Mesochaetopterus (Chaetopteridae) (Polychaeta) beschrieben und mit den restlichen Arten dieser Gattung verglichen.

Der 60 cm lange Mesochaetopterus xerecus zeigt eine gewisse Ähnlichkeit mit M. tay‐lori, aber unterscheidet sich durch die Länge und Pigmentierung der Tentakel, existenz von einem Paar Augen, Anzahl der Parapodien in der vorderen Körperregion, Form der dunklen starken Borsten des 4. Segments, Anzahl der "accessory feeding organs”;, Anzahl der Zähne der Haken der Neuropodia.

Mesochaetopterus xejubus ist eine kleinere Art von ungefähr 7 cm Länge und ist in Form und Größe M. minuta am ähnlichsten. Es unterscheidet sich jedoch durch die Form und Größe des Peristomium, Farbe der Tentakeln, Anzahl der Parapodia der vorderen Körperregion, Anzahl und Form der dunklen starken Borsten des 4. Para‐podiums der vorderen Region, Anzahl der "accessory feeding organs”;, Anzahl der Segmente der mittleren Körperregion, Anzahl der Zähne der Haken der Neuropodia und schleimdrüsenreiches Epithelium der mittleren Körperregion.