Description: Eight strains belonging to the Oomycete genus Phytophthora were isolated from Zostera marina (seagrass) in The Netherlands over the past 25 y. Based on morphology, isozymes, temperature–growth relationships and ITS sequences, these strains were found to belong to two different Phytophthora species. Five strains, four of them isolated from rotting seeds and one isolated from decaying plants, could not be assigned to a known species and hence belong to a new species for which we propose the name Phytophthora gemini sp. nov. Three strains were isolated from decaying plants and were identified as Phytophthora inundata, thereby expanding the known habitat range of this species from fresh to brackish-saline areas. The possible role of both Phytophthora species in the decline of Z. marina in The Netherlands and the evolutionary significance of the presence of Phytophthora species in marine environments are discussed.

Description: The scleractinian cold-water corals (CWC) Lophelia pertusa and Madrepora oculata represent two major deep-sea reef-forming species that act as key ecosystem engineers over a wide temperature range, extending from the northern Atlantic (ca. 5–9 °C) to the Mediterranean Sea (ca. 11–13 °C). Recent research suggests that environmental parameters, such as food supply, settling substrate availability or aragonite saturation state may represent important precursors controlling habitat suitability for CWC. However, the effect of one principal environmental factor, temperature, on CWC key physiological processes is still unknown. In order to evaluate this effect on calcification, respiration, and dissolved organic carbon (DOC) net flux, colonies of Mediterranean L. pertusa and M. oculata were acclimated in aquaria to three temperatures (12, 9 and 6 °C), by consecutive decrements of 1 month duration. L. pertusa and M. oculata maintained at Mediterranean control conditions (i.e. 12 °C) displayed constant rates, on average respiring 4.8 and 4.0 µmol O2 cm−2 coral surface area d−1, calcifying 22.3 and 12.3 µmol CaCO3 g−1 skeletal dry weight d−1 and net releasing 2.6 and 3.1 µmol DOC cm−2 coral surface area d−1, respectively. Respiration of L. pertusa was not affected by lowered temperatures, while M. oculata respiration declined significantly (by 48%) when temperature decreased to 9 °C and 6 °C relative to controls. L. pertusa calcification at 9 °C was similar to controls, but decreased significantly (by 58%) at 6 °C. For M. oculata, calcification declined by 41% at 9 °C and by 69% at 6 °C. DOC net flux was similar throughout the experiment for both CWC. These findings reveal species-specific physiological responses by CWC within their natural temperature range. L. pertusa shows thermal acclimation in respiration and calcification, while these mechanisms appear largely absent in M. oculata. Conclusively, species-specific thermal acclimation may significantly affect the occurrence and local abundance of cosmopolitan CWC species, consequently influencing their important role in habitat engineering and ecosystem functioning in various thermal environments. Keywords

Description: Dissolved organic matter, which contains many compounds such as lipids, sugars and amino acids, is an important source of carbon and nitrogen for several symbiotic and asymbiotic tropical coral species. However, there is still no information on its possible uptake by cold-water coral species. In this study, we demonstrated that dissolved organic matter, in the form of dissolved free amino acids (DFAA), is actively absorbed by four cold-water coral species from the Mediterranean Sea. Although the uptake rates observed with 3 µM DFAA concentration were one order of magnitude lower than those observed in tropical species, they corresponded to 12–50% of the daily excreted-nitrogen, and 16–89% of the daily respired-carbon of the cold-water corals. Consequently, DFAA, even at in situ concentrations lower than those tested in this study, can supply a significant amount of carbon and nitrogen to the corals, especially during periods when particulate food is scarce.

Description: The coral species Paragorgia arborea and Primnoa resedaeformis are abundant and widely distributed gorgonians in North Atlantic waters. Both species add significant habitat complexity to the benthic environment, and support a host of invertebrate species. Mapping their distribution is an essential step in conservation and resource management, but challenging as a result of their remoteness. In this study, three predictive models — Ecological Niche Factor Analysis, Genetic Algorithm for Rule-set Production and Maximum Entropy modeling (MaxEnt) were applied to predict the distribution of species' suitable habitat across a region of Røst Reef (Norwegian margin) based on multiscale terrain variables. All three models were successful in predicting the habitat suitability for both gorgonian species across the study area, and the MaxEnt predictions were shown to outperform other predictions. All three models predicted the most suitable habitats for both species to mainly occur along the ridges and on the upper section of the large slide, suggesting both species preferentially colonize topographic highs. Jackknife tests for MaxEnt predictions highlighted the seabed aspect in relation to P. arborea distribution, and the seabed relative position (curvature) in relation to the distribution of both species. Given the vulnerability of deep-water corals to anthropogenic impacts, further comparative study over a wider study area would be particularly beneficial for the management of the species.

Description: The spatial variability in the mix of species making up Cold-water coral reef communities is not well known. In this study abundances of a selection of megafauna (Lophelia pertusa, Madrepora oculata, Paragorgia arborea, Primnoa resedaeformis, Mycale lingua, Geodia baretti, Acesta excavata and fish) were quantified throughout 9 manned submersible video transects from 3 reef complexes (Røst Reef, Sotbakken Reef and Traena Reef) on the Norwegian margin. Substrate type (coral structure, rubble, exposed hardground or soft sediment) was also recorded. Variations in the densities of these fauna (with respect to both reef complex and substrate type) were investigated, with spatial covariance between species assessed. For the majority of fauna investigated, densities varied by both reef and substrate. Spatial covariance indicated that some species may be utilising similar habitat niches, but that minor environmental differences may favour colonisation by one or other at a particular reef. Fish densities were generally higher in regions with biogenic substrate (coral structure and coral rubble substrates) than in areas of soft or hardground substrate. Further, fish were more abundant at the northerly Sotbakken Reef at time of study than elsewhere. Community structure varied by reef, and therefore management plans aimed at maintaining the biodiversity of reef ecosystems on the Norwegian margin should take this lack of homogeneity into account.

Description: Fresh volcanic glasses from the extrusive section of the Troodos Ophiolite in Akaki Canyon are tholeiitic and basaltic to dacitic in composition. Compared to normal MORB they have extremely low fractionation corrected Na8, Fe8 and Ti8 and are enriched in fluid-mobile trace elements, including U, Ba, Rb, Sr and Pb, relative to non-fluid mobile elements of similar incompatibility. Trace element compositions of Akaki lavas define an array extending between ‘back-arc lava’-like compositions, and the field defined by Troodos boninites from the upper part of the lava sequence. Troodos lavas were derived from a mantle source that underwent early melt depletion, and later enrichment by both fluids and small degree melts. These processes can explain the unusual negative correlation of Pb/Ce with Zr/Nb and Ba/Nb in Troodos extrusives. Although some Troodos lavas are similar in composition to lavas from back-arc spreading centres, the boninites from the upper parts of the lava pile do not appear to have exact compositional equivalents among lavas from fore-arcs, back-arcs or other tectonic settings where similar rocktypes have been recovered. We suggest that the geochemical evolution inferred for the mantle source of Troodos lavas, together with geological evidence is most consistent with an origin for the Troodos Ophiolite at a spreading centre close to a ridge–trench–trench, or ridge–trench–transform triple junction, where highly depleted, subduction-modified, fluid-enriched mantle wedge material was able to upwell and decompress to shallow depths in a ‘fore-arc’ location. In such a tectonic setting, arc volcanism is captured by the spreading centre, explaining the lack of evidence for subaerial arc magmatism in Troodos. Rapid lateral migration of the triple junction could account for the similar ages of other Tethyan supra-subduction zone ophiolites.

Description: A chemical study of the lichen Ramalina siliquosa complex found in Brittany was conducted. Eight chemotypes were considered and their chemical composition was elucidated for the first time by LC–MS analysis. Ten main compounds were identified: conhypoprotocetraric acid (1), salazinic acid (2), peristictic acid (3), cryptostictic acid (4), protocetraric acid (5), stictic acid (6), norstictic acid (7), hypoprotocetraric acid (8), 4-O-demethylbarbatic acid (9), (+)-usnic acid (10) and 22 minor compounds were reported. The MS/MS fragmentation patterns of each compound of R. siliquosa complex were determined and proposed.

Description: Trace metals in the ocean act as both essential micro-nutrients and as toxins. There are relatively few multi-element studies of dissolved trace metals in the ocean, and none from the Gulf of Aqaba, Red Sea. This semi-enclosed basin surrounded by desert is a natural laboratory for studying the impact of atmospheric dry deposition of trace metals on the ocean surface. We have combined measurement of dissolved metals in seawater with measurements of the flux of metals associated with dry deposition. The total dissolved trace metal concentrations in Gulf of Aqaba water are generally higher (Fe, Cu, Zn, Co, Mn, Pb) or similar (Ni, Al, Cd, Mo) to those measured in the open North Atlantic Ocean. The concentrations of elements that are highly enriched in aerosols relative to Al (e.g. Cd, Pb, Zn and Cu) are not necessarily proportionally enriched in surface seawater when compared to Al, indicative of the high reactivity of these elements in seawater. Iron concentrations in the Gulf of Aqaba are high relative to Al, despite the fact that the aerosols are not more enriched in Fe relative to Al. There may be additional sources of dissolved iron to the Gulf of Aqaba, not associated with Al. Alternatively, intense photochemically-driven redox cycling may act to enhance Fe dissolution from aerosols, or may otherwise increase the lifetime of Fe in the water column, relative to Al. Copper concentrations in the Gulf of Aqaba are close to the value found to be a threshold for Cu toxicity in this region. A surface maximum in Cd:P is found in the Gulf of Aqaba, in contrast to the more typical surface minimum in this ratio observed in other locations. The surface maximum appears to be driven by atypically low uptake of Cd relative to P. A low Cd:P uptake ratio for this region is consistent with known environmental determinants of low Cd:P uptake, such as high concentrations of dissolved Zn and Fe, and a predominance of small phytoplankton including cyanobacteria. Highlights ► We measured dissolved trace metal concentrations in the Gulf of Aqaba four times. ► Iron concentrations are high relative to Al concentrations. ► Cu concentrations are close to the threshold for Cu toxicity in this region. ► A surface maximum in Cd:P is driven by unusually low uptake of Cd relative to PO4. ► This is consistent with the dominance of small phytoplankton and high Fe levels.

Description: The convergence between the Indian plate and the southern margin of the Eurasian continent created an active continental margin from Late Jurassic until about 40 Ma ago, which then evolved to form the Himalaya and the Tibetan Plateau during the continental collision stage. Post-collisional magmatism in southern Tibet, north of the Yarlung Zangbo Suture Zone (YZSZ) has been active since 45 Ma and is related to normal faulting and extensional tectonism. To date no such magmatism was reported within the YZSZ itself. This paper reports on the discovery of Miocene shoshonites within the YZSZ. They are significant because the magma traveled, at least in part, through oceanic crust, thus limiting interaction with the continental crust to the mid-crustal level and which affected the post-collisional magmatic rocks occurring in the northern part of the subduction system. In addition, xenoliths and xenocrysts of crustal origin in these rocks constrain the nature of metamorphic rocks underlying the YZSZ at mid-crustal level. The geochemical signatures of the shoshonitic rocks, including Nd and Sr isotope systematics, indicate derivation from a garnet-bearing middle continental crustal source. Crustal imprint complicates modeling of the petrogenetic processes which occurred prior to mid-crustal ponding of the magma which took place between 11 and 17 Ma at depths of 40 to 50 km. The significant role of crustal contamination raises serious concerns about models proposed for similar magmatic activity elsewhere in the Himalaya and the Tibetan Plateau.

Description: In this paper we present an in-depth analysis and synthesis of published and newly acquired data on the chemical and isotopic composition of forearc fluids, fluid fluxes, and the associated thermal regimes in well-studied, representative erosional and accretionary subduction zone (SZ) forearcs. Evidence of large-scale fluid flow, primarily focused along faults, is manifested by widespread seafloor venting, associated biological communities, extensive authigenic carbonate formation, chemical and isotopic anomalies in pore-fluid depth-profiles, and thermal anomalies. The nature of fluid venting seems to differ at the two types of SZs. At both, fluid and gas venting sites are primarily associated with faults. The décollement and coarser-grained stratigraphic horizons are the main fluid conduits at accretionary SZs, whereas at non-accreting and erosive margins, the fluids from compaction and dehydration reactions are to a great extent partitioned between the décollement and focused conduits through the prism, respectively. The measured fluid output fluxes at seeps are high, ∼15–40 times the amount that can be produced through local steady-state compaction, suggesting that in addition, other fluid sources or non-steady-state fluid flow must be involved. Recirculation of seawater must be an important component of the overall forearc output fluid flux in SZs. The most significant chemical and isotopic characteristics of the expelled fluids relative to seawater are: Cl dilution; sulfate, Ca, and Mg depletions; and enrichments in Li, B, Si, Sr, alkalinity, and hydrocarbon concentrations, often distinctive δ18O, δD, δ7Li, δ11B, and δ37Cl values, and variable Sr isotope ratios. These characteristics provide key insights on the source of the fluid and the temperature at the source. Based on the fluid chemistry, the most often reported source temperatures reported are 120–150 °C. We estimate a residence time of the global ocean in SZs of ∼100 Myr, about five times faster than the previous estimate of ∼500 Myr by Moore and Vrolijk, similar to the residence time of ∼90 Myr for fluids in the global ridge crest estimated by Elderfield and Schultz, and ∼3 times longer than the 20–36 Myr estimate by German and von Damm and Mottl. Based on this extrapolated fluid reflux to the global ocean, subduction zones are an important source and sink for several elements and isotopic ratios, in particular an important sink for seawater sulfate, Ca and Mg, and an important source of Li and B.