ALBERT

Description: Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity.

Description: The basement of the Vera and Huercal Overa basins (southeastem Betics) is fonned by rocks ofthe Alboran Crustal Domain; a terrain which collided with the South-Iberian and Maghrebian continentalmargins in the Lower Miocene, resulting in the fonnation of the Gibraltar Are mountain chain. The Alpuja1Tide complex which occupies an intermediate structural position within the Alboran Domain, above the Nevado-Filabride and below the Malaguide complexes, includes at least three tectonic units in the southeastern Betics. From bottom to top in the slTuctural sequence, these units are Almagro, Almanzora and Variegato. The metapelitic rocks of these units show significative differences in their tectonic fabrics and in their P-T metamorphic paths. The lower Almagro unit underwent low-P/low-T metamorphism (300 oc and 3-4 kbar) and its metapelites are slates with no differentiated metamorphic fabric, which show two sets of spaced axial-plane cleavages. The intennediate Almanzora unit has two differentiated metamorphic fabrics. The oldest foliation (S,) preserved in quartz-rich domains of a crenulation cleavage (S ce) grew during high-P/low-T metamorphism (between 300 °C/12 kbar and 350 oC/6 kbar). The Scc cleavage deyeloped after an isobaric heating to 475 oc at 5 kbar and registers an initial isothennal decompression to 475 oc at 3 kbar followed by cooling to 300 oc at 2 kbar. A brittle spaced cleavage axial plane to N-vergent asymmetric folM cuts the S ce fabtic. At the top ofthe Alpujarride tectonic pile the Variegato unit, includes up to tlu·ee imbrications formed from top to bottom by gamet schists, fine"grained schists and Triassic carbonates. The main Scc foliation in the gamet schists grew during a nearly isothennal decompression between 500 oc at 8 kbar and 525 oc at 2 kbar. In the Variegato dark schists, the spaced crenulation cleavage associated to Nvergent folds is defined by muscovite and chlorite lepidoblasts and is overprinted by the growth of andalousite porphyroblasts. This assemblage equilibrated at 450-460 oc at 2 kbar. The Variegato fine-grained schists include a high-P/low-T Mg-carpholite-bearing assemblage, within pre-Scc quartz veins equilibrated at 8-10 kbar and approximately 400 °C. Furthermore, a chlorite + phengite + quartz assemblage defining the se relic foliation in lenticular domains of the scc cleavage shows local equilibria at 11 to 9 kbar at 400 °C. The superposition ofthese units was related with N-directed compressional brittle-ductile shear zones and associated N-vergent asymmetric folds, which were active at a late stage of the metamorphic evolution after coaxial ductile flattening of the Variegato and Almanzora units. The thrust pile that resulted from this late compressional event was later thinned by two consecutive brittle extensional systems with northward and southwestward tectonic transport. Final! y, these metamorphic rocks were exhumed to the surface in the core of E-W oriented anticlinal ridges, which developed during the Upper Neogene and the Quaternary. Folding and strike-slip faulting of the Miocene Alboran basin produced the present basin and range morphology of the southeastern Betics, which is characterised by the formation of isolated sedimentary basins in the synclines.

Description: We have analysed the thermobarometric equilibrium conditions reached during local equilibria among phengite + chlorite + quartz + water ± chloritoid ± garnet assemblages found in metapelites of the Ragua unit, the structurally-lowest tectonic unit outcropping in the Betics hinterland (southern Spain). Porphyroblast- deformation relationships show that lenticular domains preserved within the main foliation in the metapelites grew during a HP/LT prograde metamorphic event with thermal conditions of 320-450 °C and 12-14 kbar pressure. Hence, the Ragua unit subducted in a continental accretionary-wedge context, undergoing a tectonic evolution parallel to the one followed by the two other overlying Nevado-Filabride units.

Description: Recently acquired swath-bathymetry data and high-resolution seismic reflection profiles offshore Adra (Almería, Spain) reveal the surficial expression of a NW–SE trending 20 km-long fault, which we termed the Adra Fault. Seismic imaging across the structure depicts a sub-vertical fault reaching the seafloor surface and slightly dipping to the NE showing an along-axis structural variability. Our new data suggest normal displacement of the uppermost units with probably a lateral component. Radiocarbon dating of a gravity core located in the area indicates that seafloor sediments are of Holocene age, suggesting present-day tectonic activity. The NE Alboran Sea area is characterized by significant low-magnitude earthquakes and by historical records of moderate magnitude, such as the Mw = 6.1 1910 Adra Earthquake. The location, dimension and kinematics of the Adra Fault agree with the fault solution and magnitude of the 1910 Adra Earthquake, whose moment tensor analysis indicates normal-dextral motion. The fault seismic parameters indicate that the Adra Fault is a potential source of large magnitude (Mw ≤ 6.5) earthquakes, which represents an unreported seismic hazard for the neighbouring coastal areas.

Description: Multichannel seismic reflection images across the transition between the east Alborán and the Algero-Balearic basins show how crustal thickness decreases from about 5 s two-way traveltime (TWTT, ∼15 km thick) in the west (east Alborán basin) to ∼2 s TWTT typical of oceanic crust (∼6 km thick) in the east (Algero-Balearic basin). We have differentiated three different crustal domains in this transition, mainly on the basis of crustal thickness and seismic signature. Boundaries between the three crustal domains are transitional and lack evidence for major faults. Tilted blocks related to extension are very scarce and all sampled basement outcrops are volcanic, suggesting a strong relationship between magmatism and crustal structure. Stratigraphic correlation of lithoseismic units with sedimentary units of southeastern Betic basins indicates that sediments onlap igneous basement approximately at 12 Ma in the eastern area and at 8 Ma in the western area. Linking seismic crustal structure with magmatic geochemical evidence suggests that the three differentiated crustal domains may represent, from west to east, thin continental crust modified by arc magmatism, magmatic-arc crust, and oceanic crust. Middle to late Miocene arc and oceanic crust formation in the east Alborán and Algero-Balearic basins, respectively, occurred during westward migration of the Gibraltar accretionary wedge and shortening in the Betic-Rif foreland basins. Arc magmatism and associated backarc oceanic crust formation were related to early to middle Miocene subduction and rollback of the Flysch Trough oceanic basement. Subduction of this narrow slab beneath the Alborán basin was coeval with collision of the Alborán domain with the Iberian and African passive margins and subsequent subcontinental-lithosphere edge delamination along the Betic-Rif margins.

Description: Coastal upwelling zones are hotspots of oceanic productivity, driven by phytoplankton photosynthesis. Bacteria, in turn, grow on and are the principal remineralizers of dissolved organic matter (DOM) produced in aquatic ecosystems. However, the molecular processes that key bacterial taxa employ to regulate the turnover of phytoplankton-derived DOM are not well understood. We therefore carried out comparative time-series metatranscriptome analyses of bacterioplankton in the Northwest Iberian upwelling system, using parallel sampling of seawater and mesocosms with in situ-like conditions. The mesocosm experiment uncovered a taxon-specific progression of transcriptional responses from bloom development (characterized by a diverse set of taxa in the orders Cellvibrionales, Rhodobacterales, and Pelagibacterales), over early decay (mainly taxa in the Alteromonadales and Flavobacteriales), to senescence phases (Flavobacteriales and Saprospirales taxa). Pronounced order-specific differences in the transcription of glycoside hydrolases, peptidases, and transporters were found, supporting that functional resource partitioning is dynamically structured by temporal changes in available DOM. In addition, comparative analysis of mesocosm and field samples revealed a high degree of metabolic plasticity in the degradation and uptake of carbohydrates and nitrogen-rich compounds, suggesting these gene systems critically contribute to modulating the stoichiometry of the labile DOM pool. Our findings suggest that cascades of transcriptional responses in gene systems for the utilization of organic matter and nutrients largely shape the fate of organic matter on the time scales typical of upwelling-driven phytoplankton blooms.

Description: Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from sites with contrasting nodule coverage in four license areas. Results showed that epifaunal densities are more than two times higher at dense nodule coverage (〉25 versus ≤10 individuals per 100 m2), and that taxa such as alcyonacean and antipatharian corals are virtually absent from nodule-free areas. Furthermore, surveys conducted along tracks from trawling or experimental mining simulations up to 37 years old, suggest that the removal of epifauna is almost complete and that its full recovery is slow. By highlighting the importance of nodules for the epifaunal biodiversity of this abyssal area, we urge for cautious consideration of the criteria for determining future preservation zones.

Description: Highlights • We review the knowledge on modern high-latitude planktic foraminifers. • Subpolar species currently invade higher latitudes. • Climate change affects phenology, seawater pH, and carbon turnover. • Modern planktic foraminifers are briefly discussed for their paleoceanographic significance. Abstract Planktic foraminifers can be sensitive indicators of the changing environment including both the Arctic Ocean and Southern Ocean. Due to variability in their ecology, biology, test characteristics, and fossil preservation in marine sediments, they serve as valuable archives in paleoceanography and climate geochemistry over the geologic time scale. Foraminifers are sensitive to, and can therefore provide proxy data on ambient water temperature, salinity, carbonate chemistry, and trophic conditions through shifts in assemblage (species) composition and the shell chemistry of individual specimens. Production and dissolution of the calcareous shell, as well as growth and remineralization of the cytoplasm, affect the carbonate counter pump and to a lesser extent the soft-tissue pump, at varying regional and temporal scales. Diversity of planktic foraminifers in polar waters is low in comparison to lower latitudes and is limited to three native species: Neogloboquadrina pachyderma, Turborotalita quinqueloba, and Globigerina bulloides, of which N. pachyderma is best adapted to polar conditions in the surface ocean. Neogloboquadrina pachyderma hibernates in brine channels in the lower layers of the Antarctic sea ice, a strategy that is presently undescribed in the Arctic. In open Antarctic and Arctic surface waters T. quinqueloba and G. bulloides increase in abundance at lower polar to subpolar latitudes and Globigerinita uvula, Turborotalita humilis, Globigerinita glutinata, Globorotalia inflata, and Globorotalia crassaformis complement the assemblages. Over the past two to three decades there has been a marked increase in the abundance of Orcadia riedeli and G. uvula in the subpolar and polar Indian Ocean, as well as in the northern North Atlantic. This paper presents a review of the knowledge of polar and subpolar planktic foraminifers. Particular emphasis is placed on the response of foraminifers to modern warming and ocean acidification at high latitudes and the implications for data interpretation in paleoceanography and paleoclimate research.

Description: Recent advances in seafloor and subsurface imaging allow accurately mapping and characterizing the kinematic pattern and the style of deformation of submarine faults with unprecedented detail to better assess seismic and tsunami hazards in coastal areas. The Alboran Sea is a Neogene basin generated by crustal extension associated with the subduction in the Gibraltar Arc. At present, several fault systems absorb part of the strain related to the NW-SE convergence (4-5.5 mm/yr) between the African and Eurasian plates. Consequently, the Alboran Sea shows a significant seismic activity. New high-resolution bathymetric and seismic data reveal the presence of poorly known pervasive fault systems in the central part of the Alboran Sea, the Averroes Fault (AF) and the North Averroes Faults (NAFs). These are secondary fault systems located between two large active faults, the Carboneras and Yusuf/Alboran Ridge faults, and represent a hitherto unrecognized seismogenic potential. The WNW-ESE trending AF and NAFs, which may have evolved since the Lower Pliocene (4.57 Ma), are subvertical right-lateral strike-slip active faults since: a) are offsetting the Quaternary sedimentary units and deforming the seafloor; and b) produce a right-lateral displacement of the northwestern margin of the Alboran Channel and across the Adra Ridge North. Given that the AF and NAFs have formed in a continental crust and that are located in a zone surrounded by some of the main active faults in the Alboran Sea, we postulate that these fault systems have been developed into a distributed dextral strike-slip shear zone with the local bulk shear striking approximately N90º. Considering their surface length they could generate earthquakes with magnitudes (Mw) between 6.3 and 7.2, but reaching 7.6 when AF and Yusuf Fault are linked. The high resolution bathymetry map has allowed us measuring lateral offsets produced by the AF and NAFs. Assuming that these displacements have been accumulated during the last 4.57 Ma, the calculated lateral slip rate for AF is approximately1.5 mm/yr and range between 0.2 and 0.4 mm/yr for the NAFs. Our results evidence the importance of the kinematic and seismogenic characterization of secondary fault systems to better comprehend earthquake and tsunami hazards.