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For a century, the discovery of ferromanganese (Fe–Mn) nodules in the World Ocean was universally and indisputably credited to the Challenger circum-global oceanographic expedition of 1872–1876, during which the first manganese nodules and crusts were dredged up from the sea floor in February–March 1873. A century later, a counterclaim appeared in the literature, crediting Nordenskiöld's expedition on Sofia in 1868, five years before the Challenger findings, for the discovery of Fe–Mn nodules in the ocean. This counterclaim, widely accepted without scrutiny, was based on the Gustaf Lindström (1884) chemical analysis of a single bottom sediment sample among 14 samples from two Arctic expeditions led by Nordenskiöld: Sofia 1868 and Vega 1878–1880. The Lindström (1884) report published as an eight-page brochure in Swedish remained almost unknown to the research community until now. A close examination of this report and other historical evidence revealed that the counterclaim of discovery by the Sofia 1868 expedition to the Kara Sea is invalid based on three notable facts: (1) Sofia never sailed in the Kara Sea; (2) the single bottom sediment sample with an extremely high content of Mn (24%), was collected in the Kara Sea during the Vega Expedition across the Northeast Passage; (3) the Vega sampling was in 1878, not in 1868. Meanwhile, five and a half years prior to the Vega sampling, the first Fe–Mn nodules and crusts were dredged up from the sea floor on 18 February and March 7, 1873 during the Challenger expedition. These findings have been promptly reported and published in May 1873. Thus, the credit for the discovery of ferromanganese nodules in the World Ocean firmly belongs to the Challenger expedition. • The discovery of ferromanganese nodules in the World Ocean is revisited. • The Lindström (1884) paper with chemical analyses of sediment samples from Nordeskiöld's expeditions is examined. • The discovery of ferromanganese nodules in the World Oceanduring the Challenger 1872–1876 expedition is confirmed. [ABSTRACT FROM AUTHOR]

The reproductive aspects of all Plesionika species are relatively well known worldwide, except for the deepest species of the genus, Plesionika williamsi , for which little information is available throughout its range. The ovarian maturity, sex ratio, brood size, and size-depth distribution of the deep-sea shrimp Plesionika williamsi (Pandalidae) in the Canary Islands (eastern-central Atlantic) were analysed. Ovigerous females were observed all year round, with the highest number of ovigerous females recorded between July and October. The presence of a greater number of ovigerous females during the summer may reflect a high local availability of food or the optimal abiotic conditions, which are factors with a strong influence on reproduction. The presence of non-ovigerous mature females throughout the year indicates that their resting period in the reproductive cycle occurs asynchronously. The physiological size at first sexual maturity was 19.24 mm in carapace length (CL) and the length at first sexual maturity was estimated at 23.15 mm CL. Estimates of size at first sexual maturity based on ovigerous females describe the result of the reproduction process, whereas size at first sexual maturity based on ovarian maturity deals with physiological preparation for reproduction. The modal size class of egg production was 24–30 mm CL, which yielded 83.22% of the population egg production. Plesionika williamsi is an iteroparous species that can produce small eggs during egg extrusion. The mean number of external embryos carried by females was 3048 and can be considered a true approximation of the number of larvae released in each batch, which depend on the conditions existing in each system. The shallower individuals are associated with a depth stratum that represents the boundary between two water masses present in the Canary Islands. The increase in size with depth is related to the presence of submarine volcanic canyons, which constitutes a flow channel of surface organic matter to depth. • Ovigerous females during the summer days may reflect a high local availability of food or the optimal abiotic conditions. • The resting period in the reproductive cycle occurs asynchronously. • Plesionika williamsi is an iteroparous species that can produce small eggs during egg extrusion. • External embryos carried by females can be considered a true approximation of the number of larvae released. • The increase in size with depth is related to the presence of submarine volcanic canyons. [ABSTRACT FROM AUTHOR]

There is a growing interest in the study of mesopelagic and bathypelagic species due to their implication in the active carbon flux and climate change. Underwater acoustics is one of the most efficient methods to study such widely distributed communities. However, there are several challenges among which the reduced spatial resolution with depth for vessel-mounted echosounders stands out. The increase in sampling volume with range precludes observation of fine structures within the scattering layers or the study of less-aggregated organisms far from the transducer face. Echosounders are thus increasingly being deployed in alternative platforms that get the transducer close to the layers of interest. We present here the comparison between two active acoustic platforms used to analyse mesopelagic and bathypelagic species: a vessel-mounted EK60 scientific echosounder and a 6000 m depth rated Acoustic Zooplankton Fish Profiler (AZFP) attached to a CTD rosette. Both systems depicted similar vertical distributions and scattering at 38 kHz for the main scattering layers recorded around the Canary Islands but the finer vertical resolution of the AZFP discerned a series of sub-layers within them that differed in scattering, avoidance and sparsity. The availability of high frequencies at depth also provided further insights on the frequency response of those layers. However, the horizontal orientation of the AZFP created sidelobe artefacts close to the surface and bottom that limit its use in those areas. Signal-to-noise ratio of the AZFP system in the bathypelagic zone also precludes applying echointegration analysis at those depths or outside the denser scattering layers. Finally, the visualization of horizontal or temporal patterns such as migration or mesoscale features is limited to a coarse resolution using data from closely spaced successive stations. New challenges encountered with vertically-deployed echosounders and recommendations for their use are pointed out. Although no scattering layers were detected in the bathypelagic zone, this study unveils an area never before recorded acoustically. • We present an acoustic device that can reach 6000 m of depth. • The horizontal beam orientation ensures a constant ensonified sampling volume but adds some artefacts. • Similar scattering layers are detected for coincident frequencies with respect to the vessel echosounder but distinct sublayers are revealed. • Layers' sparsity and avoidance could be potential discriminating properties. • Echointegration can only be applied within dense layers at close range. [ABSTRACT FROM AUTHOR]

The structure and composition of the deep-sea fish community living on the slope off the Canary Islands (eastern-central Atlantic) were investigated. Data were collected by means of eight research cruises (165 stations) at depths between 150 and 2050 m. A total of 4475 fish specimens belonging to 43 families and 78 species (21 Elasmobranchii, 1 Holocephali, and 56 Actinopterygii) were collected with longlines. In the number of individuals, the deep-sea demersal fish fauna was dominated by fishes of the family Synaphobranchidae, followed by Sparidae, Somniosidae, Centrophoridae, and Trichiuridae. The main abundant species were Synaphobranchus affinis , Dentex macrophthalmus , Pagellus acarne , Zameus squamulosus , Aphanopus carbo, Squalus megalops, Centroscymnus coelolepis , and Centroscymnus owstonii. Elasmobranchs, with 1519 individuals, showed a high abundance (33.94%) on the longlines, although their importance increased when the data were analysed by weight, reaching 54.07% (4588 kg), with Zameus squamulosus being the fourth most important species. • Depth was the main structuring factor of deep-sea fish assemblages. • The pattern of assemblages with depth is influenced by the different water masses. • Drastic reduction in species diversity with depth was observed. • The peak in elasmobranch biomass and abundance was observed at approximately 1000 m depth. • Deania calceus , Centroscymnus crepidater or Etmopterus princeps , show a high affinity with colder seawater. [ABSTRACT FROM AUTHOR]

Abstract: This work investigated the biology of Paromola cuvieri in the Atlantic Ocean, including reproductive patterns, sex structure, depth distribution and egg development. Females were more abundant than males, mainly at depths greater than 600m. Males were dominant in size classes larger than 110mm carapace width (CW), especially over 120mm, for which only males were observed. The mean length of both sexes decreased with depth. P. cuvieri appears to have continuous reproduction throughout the year. Large females tend to spawn mainly between summer and winter, but smaller females spawn during the summer. Four maturity categories were identified based on the ovary colour, and these categories were histologically validated. Three categories of testes were identified according to their colour and morphology. Sexual maturity was estimated at sizes between 71.6 and 74.0mm CW for females and at 91.0mm CW for males. The relative growth showed changes along the ontogeny, at 73.6mm CW (females) and 91.3–92.2mm CW (males). Egg development appears to not be completely synchronous, and two colour patterns can be observed simultaneously. Four stages of egg development were found: eggs undivided and fully filled with yolk in orange egg masses; eggs with a free region of yolk visible in orange or red egg masses; embryos with slightly pigmented, crescent-shaped eyes in brown egg masses; and embryos with visible pigmented structures, enlarged eyes, segmented appendages and abdomen in brown egg masses. The mean number of external eggs carried by females in stage I was estimated to be 315,753±19,267. Three species of barnacle were observed on the exoskeleton: Poecilasma aurantia, Poecilasma crassa and Heteralepas microstoma (Cirripedia, Thoracica). [Copyright &y& Elsevier]

The hexactinellid sponge Asconema setubalense Kent, 1870is a large bathyal species of the North Atlantic Ocean with a funnel-like body and very large osculum. Populations of A. setubalense have a three-dimensional structure and increase the complexity and biodiversity in their habitat, and are therefore considered to be a habitat-forming species. Nevertheless, at present the information on the extension, biomass, density, population structure, and ecology of this species is scarce, and it could be susceptible to the longline fishing practices that take place in the Canary Islands. The main objectives of this study are to define a functional and accurate methodology to measure specimens of A. setubalense by comparing differences in users, techniques, and morphometric measurements; to describe the height-size relationship; to present the population size structure of the species, and to establish a relationship between the size of A. setubalense and the environmental variables that can be found at the "Banco de La Concepción" seamount (BC). The obtained results suggest that surface area is the most reliable measurement to define the size of this species, whilst also showing a clear correlation with the height of the species. The selected methodology has made it possible to measure the surface area of 1035 specimens and thus obtain the size structure of the population of A. setubalense in BC. The GAM model that was used to analyse the relationship between the size of A. setubalense and the geomorphologic variables of BC, shows areas where there is a high probability of finding large specimens of the species. The results of this study greatly enhance the knowledge of this species and its habitat, and should be considered in future conservation directives, or in the development of indicators to show the good environmental state of habitats. Additionally, the study improves analysis methodology that, with the appropriate morphometric measurements, can favour the development of future studies of this species, and indeed others with a similar morphology or growth pattern. • Asconema setubalense is one of the main habitat-forming species in the BC area. • Zenithal images are appropriate to measure size of some benthic species. • Area is the most reliable measurement to define the size of this sponge. • Area parameter presents a clear correlation with the height of the species. • The size structure of the species shows a young population and GAM model provides areas distribution size of the sponge. [ABSTRACT FROM AUTHOR]

Abstract: We compared in-situ and satellite-derived measures of the biological carbon pump efficiency at the two seemingly similar subtropical North Atlantic gyre time series sites, the Bermuda time series (BATS, Bermuda Atlantic time-series study and OFP, ocean flux program) in the western gyre and the ESTOC time series (European station for time-series in the ocean, Canary Islands) in the eastern gyre. Satellite-derived surface chlorophyll a was slightly lower at Bermuda compared to ESTOC (annual average of 0.10±0.04 vs. 0.14±0.05-mg-m−3), as was satellite-derived primary production (annual average of 380±77 vs. 440±80-mgC-m−2 d−1). However, export production normalized to primary production (export ratio) was higher at Bermuda by a factor of 2–3 when estimated using mesopelagic traps moored at 500-m depth and by a factor of 3–4 when estimated using surface-tethered drifting traps. When averaged seasonally, flux at BATS was highest in spring (March, April, May) at all depths followed by summer (June, July, August) and decreasing towards fall, but this seasonality was less visible at ESTOC. Seasonal comparison showed the fastest flux attenuation at Bermuda in winter and spring, coinciding with the highest POC flux. POC/PIC ratios derived from the moored traps were significantly higher at BATS than at ESTOC in fall and winter, but this difference was not significant in spring (p>0.05). This study shows that while the western and eastern Atlantic subtropical gyres have similar rates of primary production, the biological carbon pump differs between the two provinces. Higher new nutrient input observed at Bermuda compared to ESTOC might explain part of the difference in export ratio but alone is insufficient. Greater winter mixed-layer depths and higher mesoscale eddy activity at Bermuda resulting in pulsed production events of labile organic matter might explain both the higher export flux and export ratios found at Bermuda. [Copyright &y& Elsevier]

Abstract: We report, from remote sensing and in situ observations, a new type of permanent structure in the eastern subtropical Atlantic Ocean, that we call the “Canary Eddy Corridor”. The phenomenon, is a zonal long-lived (>3 months) mesoscale eddy corridor, whose source is the flow perturbation of the Canary Current and the Trade Winds at the Canary Islands. The latitudinal range of the corridor spans 22°N–29°N and extends from the Canaries to at least 32ºW, near the mid-Atlantic. This is the main region of long-lived westward-propagating eddies in the subtropical northeast Atlantic. From a age-distribution study we observe that at least 10% of mesoscale eddies in this region are long-lived, with a dominance of anticyclones over cyclones. Another four westward-propagating eddy corridors were also detected: two small corridors north and south of the Azores Front; a small zonal corridor located near 31ºN, south of the island of Madeira; and a small corridor located near the Cape Blanc giant filament. The existence of these corridors may change, at least for the northeastern subtropical Atlantic, the general idea that mesoscale eddies are disorganized, ubiquitous structures in the ocean. The Canary Eddy Corridor constitutes a direct zonal pathway that conveys water mass- and biogeochemical properties offshore from the Canary Island/Northwest Africa upwelling system, and may be seen as a recurrent offshore pump of organic matter and carbon to the oligotrophic ocean interior. Estimates of volume and mass transport indicate that Canary Eddy Corridor westward transport is more than one-fourth of the southward transport of the Canary Current. The westward transport of kinetic energy by the eddies of the Canary Corridor is as important as the southward transport by the Canary Current. The total primary production related to the Corridor may be as high as the total primary production of the northwest Africa upwelling system for the same latitude range. [Copyright &y& Elsevier]

Abstract: Seasonal depth stratified plankton tows, sediment traps and core tops taken from the same stations along a transect at 29°N off NW Africa are used to describe the seasonal succession, the depth habitats and the oxygen isotope ratios (δ18Oshell) of five planktic foraminiferal species. Both the δ18Oshell and shell concentration profiles show variations in seasonal depth habitats of individual species. None of the species maintain a specific habitat depth exclusively within the surface mixed layer (SML), within the thermocline, or beneath the thermocline. Globigerinoides ruber (white) and (pink) occur with moderate abundance throughout the year along the transect, with highest abundances in the winter and summer/fall season, respectively. The average δ18Oshell of G. ruber (w) from surface sediments is similar to the δ18Oshell values measured from the sediment-trap samples during winter. However, the δ18Oshell of G. ruber (w) underestimates sea surface temperature (SST) by 2°C in winter and by 4°C during summer/fall indicating an extension of the calcification/depth habitat into colder thermocline waters. Globigerinoides ruber (p) continues to calcify below the SML as well, particularly in summer/fall when the chlorophyll maximum is found within the thermocline. Its vertical distribution results in δ18Oshell values that underestimate SST by 2°C. Shell fluxes of Globigerina bulloides are highest in summer/fall, where it lives and calcifies in association with the deep chlorophyll maximum found within the thermocline. Pulleniatina obliquiloculata and Globorotalia truncatulinoides, dwelling and calcifying a part of their lives in the winter SML, record winter thermocline (∼180m) and deep surface water (∼350m) temperatures, respectively. Our observations define the seasonal and vertical distribution of multiple species of foraminifera and the acquisition of their δ18Oshell. [Copyright &y& Elsevier]

Abstract: The vertical distribution (0–900m) of zooplankton biomass and indices of feeding (gut fluorescence, GF) and metabolism (electron transfer system, ETS) were studied across an anticyclonic eddy south of Gran Canaria Island (Canary Islands). Two dense layers of organisms were clearly observed during the day, one above 200m and the other at about 500m, coincident with the deep scattering layer (DSL). The biomass displacement due to interzonal migrants in the euphotic zone was more than 2-fold higher than that previously reported for the southern area of this archipelago. The gut flux estimated (0.14–0.44mgCm-2d-1) was similar to the values previously found in the Canaries. The respiratory flux outside the eddy (1.85mgCm-2d-1) was in the lower range of values reported for this area. Inside the eddy, migrant biomass and respiration rates were 2- and 4- fold higher than in the surrounding waters. Active flux mediated by diel vertical migrants inside the eddy (8.28mgCm-2d-1) was up to 53% of the passive carbon flux to the mesopelagic zone (15.8mgCm-2d-1). It is, therefore, suggested that the anticyclonic eddy enhanced both migration from deep waters and active flux. [Copyright &y& Elsevier]

Observations from a four-year current meter mooring at 28°44′N, 13°28′W in the Lanzarote passage are used to describe the transport variability of the Eastern Boundary Current of the North Atlantic Subtropical Gyre. Three different water masses are found in the passage: North Atlantic Central Water in the upper levels (roughly 0–600 m), Antarctic Intermediate Water (roughly 600–1100 m) and Mediterranean Water in the layer above the bottom at 1300 m. The mean southward transport of NACW is −0.8±1.1 Sv (1 Sv=109 kg s−1) which is the transport of the easternmost branch of the Canary Current. Fluctuations of NACW transport are large, ranging from −3.4 Sv southward to 1.7 Sv northward. Every autumn a consistent northward transport is observed, which may be related with the eastern boundary upwelling dynamics. The mean transports of AAIW and MW are 0.1±0.4 Sv northward and −0.05±0.09 Sv southward, respectively. Fluctuations of transport of AAIW and MW are large, from 1.0 to −1.0 Sv and from −0.32 to 0.23 Sv, respectively. Thus, the mass transports for each water mass show a high standard deviation of comparable magnitude to the mean. This highlights the importance of the temporal variability of the currents in this passage. A remarkable feature of our observations is that the mean transports of NACW and AAIW during an El Nin˜o event are significantly different. [Copyright &y& Elsevier]

Discusses the vertical distribution of zooplankton in Canary Island waters and its implications for export flux. Environmental conditions; Biomass; Gut fluorescence; Electron transfer activity.

Presents information on the CANIGO project, an EU multidisciplinary research program to improve understanding of the oceanic flows and fluxes in the region of the North Atlantic between the Canary Islands, the Azores and the Gibraltar outflow. Description of the CANIGO regional model; Spreading of Mediterranean water; Variability around Madeira and the Azores.

Presents information on a research which examined 20 time-series sediment traps deployed at different water depths in the Canary Island region. Correlation of organic carbon and lithogenic fluxes; Determination of the impact of trade wind-driven versus high-altitude related transport of dust and input to the ocean.

Presents a study on the ESTOC's (Eastern Station for Time-series in the Ocean, Canary Islands's) 3 year record of deep water particle flux. Methodology used to carry out the study; Results of the study; Discussion on the study.

The near-bottom zooplankton over three seamounts of the eastern Canary Islands (Amanay, El Banquete and Concepción) was analyzed, identifying the environmental variables that explain biomass distributions over them. Zooplankton composition changed between adjacent water masses, except for the two deepest assemblages associated with Atlantic Antarctic Intermediate Water (AAIW) and Mediterranean Water (MW). The highest biomass of total zooplankton and of main taxa (e.g. copepods, chaetognaths, siphonophores) were recorded at the seamount summits, i.e., over Amanay-El Banquete (summit depths of 23–24 m) associated with Surface Water (SF) and over Concepción (150 m) in upper levels of the North Atlantic Central Water (NACW). Biomass minima at the three banks were found at ca. 250–650 m, in the deepest levels of NACW. At ca. 700–1000 m (the level occupied by AAIW) and below 1000 m (MW level) biomass increased again. Near-bottom fluorometry (f 5mab , 5 m above bottom) and dissolved oxygen (O 2 5mab) were the main variables explaining changes of total zooplankton/main taxa biomass. Biomass minima (250–650 m) coincided with decreases of O 2 5mab (3.30–3.99 ml/l at 400–700 m) at deepest depths occupied by NACW. Other variables not included in our models like turbidity (resuspension of particles) may have locally enhanced zooplankton aggregation, as they may locally occur alongside Concepcion at the NACW-AAIW confluence (at ca. 700 m), probably from the effects of internal waves. Our results suggest that observations regarding the attraction of organisms to the stationary substrates of seamounts could be related to elevated chlorophyll fluorescence and O 2 5mab concentration. Peaks in those variables apparently enhance zooplankton aggregation. • In the east Canary Islands seamounts region, the highest zooplankton biomass of all taxa was found over seamount summits. • Biomass minima occurred at 700–1000 m, at levels occupied by Atlantic Antarctic intermediate waters. • No apparent long-term changes were recorded in deep zooplankton composition. • Zooplankton aggregation over seamont summits, were related to increases in Chl a and O 2. • Biomass minima coincided with decrease of near bottom O 2 in the depth range of AAIW. [ABSTRACT FROM AUTHOR]