Respiration rate and ammonium excretion data for the squat lobster Pleuroncodes monodon measured during METEOR cruise M93

Sampling was conducted during RV Meteor cruise M93 in austral summer 2013 in an area from 11ºS to 14ºS and approximately 120 km offshore to within 10 km of the Peruvian coast. Specimens were collected using a Hydrobios Multinet Maxi (0.5 m2 mouth opening, 330 µm mesh size, 9 nets) and a WP-2 net (Hydrobios, 0.26 m2 mouth opening, 200 µm mesh size). P. monodon were identified according to http://researchdata.museum.vic.gov.au/squatlobster/delta/deltakey.html. Specimens were transferred into filtered, well-oxygenated seawater immediately after the catch and maintained for 4 to 16 hours prior to physiological experiments. Maintenance and physiological experiments were conducted at 13°C as the temperature observed at 100 to 200 m depth in the OMZ ranged from 13.7 to 12.7°C.

Phytoplankton daily production in the Rhode River, Maryland (USA), 1990-2009

Parameters in the photosynthesis-irradiance (P-E) relationship of phytoplankton were used to calculate daily production at weekly to bi-weekly intervals for 20 years at 6 stations on the Rhode River, Maryland (USA). The objectives of this work were to determine the patterns and controls on the P-E parameters and primary production of phytoplankton in a shallow eutrophic estuary. Additional measurements that are components of calculated daily rates of primary productivity are given: the light-saturation irradiance, photoperiod, maximal noon incident irradiance, optical depth, dimensionless depth integrals, and a correction for spectral selectivity of light absorption. P-E parameters and chlorophyll a concentrations were given in a related dataset, Gallegos (2012, doi:10.1594/PANGAEA.816494).

Depth profiles of iodide and iodate during POLARSTERN cruise ANT-XXIV/3 to the Atlantic sector of the Southern Ocean

The biogeochemistry of iodine in the waters of the Atlantic sector of the Southern Ocean was investigated during the Polarstern cruise ANTXXIV-3 ZERO&DRAKE. The speciation and distribution of iodine (iodate and iodide) in seawater was examined across gradients of iron concentrations and phytoplankton abundance, ranging from an open ocean region along the Zero Meridian to the Weddell Sea and Drake Passage. Iodine cycling in high latitudes differs from that in low latitudes due to differences in the plankton community composition and the physicochemical characteristics. Iodate concentrations ranged between 400 and 450 nmol/L from the surface to the bottom. Surface concentrations of iodide (17 to over 60 nmol/L) were about an order of magnitude higher than below the pycnocline. The peak values of iodide lay nearly always within the euphotic zone and showed a weak, positive correlation with nitrite concentrations in the upper 200 m. In all vertical profiles a pronounced sub-surface maximum in iodide appears between 50 and 200 m depth indicating an iodide drawdown at the near surface. Iodide distribution in the Weddell Sea showed elevated levels in Weddell Sea Bottom Water (WSBW) indicating slow oxidation kinetics and the potential for iodide as a tracer of WSBW formation.

Photosynthetic parameters, chlorophyll concentration, and diffuse attenuation coefficients in the Rhode River, Maryland (USA), 1990-2009

Parameters in the photosynthesis-irradiance (P-E) relationship of phytoplankton were measured at weekly to bi-weekly intervals for 20 yr at 6 stations on the Rhode River, Maryland (USA). Variability in the light-saturated photosynthetic rate, PBmax, was partitioned into interannual, seasonal, and spatial components. The seasonal component of the variance was greatest, followed by interannual and then spatial. Physiological models of PBmax based on balanced growth or photoacclimation predicted the overall mean and most of the range, but not individual observations, and failed to capture important features of the seasonal and interannual variability. PBmax correlated most strongly with temperature and the concentration of dissolved inorganic carbon (IC), with lesser correlations with chlorophyll a, diffuse attenuation coefficient, and a principal component of the species composition. In statistical models, temperature and IC correlated best with the seasonal pattern, but temperature peaked in late July, out of phase with PBmax, which peaked in September, coincident with the maximum in monthly averaged IC concentration. In contrast with the seasonal pattern, temperature did not contribute to interannual variation, which instead was governed by IC and the additional lesser correlates. Spatial variation was relatively weak and uncorrelated with ancillary measurements. The results demonstrate that both the overall distribution of PBmax and its relationship with environmental correlates may vary from year to year. Coefficients in empirical statistical models became stable after including 7 to 10 yr of data. The main correlates of PBmax are amenable to automated monitoring, so that future estimates of primary production might be made without labor-intensive incubations.

Oxygen and hydrogen isotopes measured in the Northeast Atlantic

Only a few studies have examined the variation of oxygen and hydrogen isotopes of seawater in NE Atlantic water masses, and data are especially sparse for intermediate and deep-water masses. The current study greatly expands this record with 527 d18O values from 47 stations located throughout the mid- to low-latitude NE Atlantic. In addition, dD was analyzed in the 192 samples collected along the GEOTRACES North Atlantic Transect GA03 (GA03_e=KN199-4) and the 115 Iberia-Forams cruise samples from the western and southern Iberian margin. An intercomparison study between the two stable isotope measurement techniques (cavity ring-down laser spectroscopy and magnetic-sector isotope ratio mass spectrometry) used to analyze GA03_e samples reveals relatively good agreement for both hydrogen and oxygen isotope ratios. The surface (0-100 m) and central (100-500 m) water isotope data show the typical, evaporation related trend of increasing values equatorward with the exception for the zonal transect off Cape Blanc, NW Africa. Off Cape Blanc, surface water isotope signatures are modified by the upwelling of fresher Antarctic Intermediate Water (AAIW) that generally has isotopic values of 0.0 to 0.5 per mil for d18O and 0 to 2 per mil for dD. Along the Iberian margin the Mediterranean Outflow Water (MOW) is clearly distinguished by its high d18O (0.5-1.1 per mil) and dD (3-6 per mil) values that can be traced into the open Atlantic. Isotopic values in the NE Atlantic Deep Water (NEADW) are relatively low (d18O: -0.1 to 0.5 per mil; dD: -1 to 4 per mil) and show a broader range than observed previously in the northern and southern convection areas. The NEADW is best observed at GA03_e Stations 5 and 7 in the central NE Atlantic basin. Antarctic Bottom Water isotope values are relatively high indicating modification of the original Antarctic source water along the flow path. The reconstructed d18O-salinity relationship for the complete data set has a slope of 0.51, i.e., slightly steeper than the 0.46 described previously by Pierre et al. (1994, J. Mar. Syst. 5 (2), 159-170.) for the tropical to subtropical Northeast Atlantic. This slope decreases to 0.46 for the subtropical North Atlantic Central Water (NACW) and the MOW and to 0.32 for the surface waters of the upper 50 m. The dD-salinity mixing lines have estimated slopes of 3.01 for the complete data, 1.26 for the MOW, 3.47 for the NACW, and 2.63 for the surface waters. The slopes of the d18O-dD relationship are significantly lower than the one for the Global Meteoric Water Line with 5.6 for the complete data set, 2.30 for the MOW, 4.79 for the NACW, and 3.99 for the surface waters. The lower slopes in all the relationships clearly reflect the impact of the evaporation surplus in the subtropics.

Species abundance and water and sediment characteristics for three ANDEEP stations on Maud Rise and the Weddell Sea

The benthic fauna was investigated during the expedition ANT-XXIV/2 (2007/08) in relation to oceanographic features, biogeochemical properties and sediment characteristics, as well as the benthic, pelagic and air-breathing fauna. The results document that Maud Rise (MR) differs distinctly from surrounding deep-sea basins investigated during previous Southern Ocean expeditions (ANDEEP 2002, 2005). Considering all taxa, the overall similarity between MR and adjacent stations was low (~20% Bray-Curtis-Similarity), and analyses of single taxa show obvious differences in species composition, abundances and densities. The composition and diversity of bivalves of MR are characterised by extremely high abundances of three species, especially the small sized Vesicomya spp. Exceptionally high gastropod abundance at MR is due to the single species Onoba subantarctica wilkesiana, a small brooder that may prey upon abundant benthic foraminiferas. The abundance and diversity of isopods also show that one family, Haplomunnidae, occurs with a surprisingly high number of individuals at MR while this family was not found at any of the 40 bathyal and abyssal ANDEEP stations. Similarly, polychaetes, especially the tube-dwelling, suspension-feeder fraction, are represented by species not found at the comparison stations. Sponges comprise almost exclusively small specimens in relatively high numbers, especially a few species of Polymastiidae. Water-column sampling from the surface to the seafloor, including observations of top predators, indicate the existence of a prospering pelagic food web. Local concentrations of top predators and zooplankton are associated with a rich ice-edge bloom located over the northern slope of MR. There the sea ice melts, which is probably accelerated by the advection of warm water at intermediate depth. Over the southern slope, high concentrations of Antarctic krill (Euphausia superba) occur under dense sea ice and attract Antarctic Minke Whales (Balaenoptera bonaerensis) and several seabird species. These findings suggest that biological prosperity over MR is related to both oceanographic and sea-ice processes. Downward transport of the organic matter produced in the pelagic realm may be more constant than elsewhere due to low lateral drift over MR.

Composition of bottom sediments and rocks from the Philippine Trough

New data on bottom sediments and igneous rocks of the Philippine Trench are under consideration. They show differences in geological structures of the island slope and the ocean slope of the trench. The island slope is comparable to the accretionary prism formations on the Philippines; there processes of gravitational re-deposition of sediments occur. The ocean slope is an edge of the Philippine Plate sinking into the trough, where basalts of the oceanic crust are exposed.

Geochemistry and K-Ar dates of the Mazagan granodiorite at V30-225, VA79-96KD and DSDP Hole 79-544A, off Moroccan coast

Gneissic granodiorite was recovered by drilling at the base of the Mazagan escarpment, 100 km west of the Casablanca, Morocco, at 4000 m water depth. Coarse, predeformative muscovite yielded dates of -515 Ma, fine-grained muscovite of -455 Ma, biotite -360 and 335 Ma, and feldspar -315 Ma. These dates are tentatively correlated with the microscopic results. We assume a minimum age of middle Cambrian for the granodiorite, an Ordovician deformation and mylonitization, and a Late Carboniferous overprint under upper greenschist facies conditions.

Stable oxygen isotope composition of the sea water in the Mediterranean Sea

During the cruises No 17 and 22 of the German research vessel "Meteor", 45 water samples were taken at 4 stations in the central part of the Mediterranean Sea. Mass spectrometrical analyses showed that systematic, but time variable changes of the oxygen isotope ratios occur. Deep water samples (T> 500 m) have a ± constant isotopic composition of d18O = +1.79? (SMOW) and a Chlorinity of 21.399?. These data are discussed with respect to paleotemperature determinations.

Oxygen consumption in Arctic sediments

Total sediment oxygen consumption rates (TSOC or Jtot), measured during sediment-water incubations, and sediment oxygen microdistributions were studied at 16 stations in the Arctic Ocean (Svalbard area). The oxygen consumption rates ranged between 1.85 and 11.2 mmol m**-2 d**-1, and oxygen penetrated from 5.0 to >59 mm into the investigated sediments. Measured TSOC exceeded the calculated diffusive oxygen fluxes (Jdiff) by 1.1-4.8 times. Diffusive fluxes across the sediment-water interface were calculated using the whole measured microprofiles, rather than the linear oxygen gradient in the top sediment layer. The lack of a significant correlation between found abundances of bioirrigating meiofauna and high Jtot/Jdiff ratios as well as minor discrepancies in measured TSOC between replicate sediment cores, suggest molecular diffusion, not bioirrigation, to be the most important transport mechanism for oxygen across the sediment-water interface and within these sediments. The high ratios of Jtot/Jdiff obtained for some stations were therefore suggested to be caused by topographic factors, i.e. underestimation of the actual sediment surface area when one-dimensional diffusive fluxes were calculated, or sampling artifacts during core recovery from great water depths. Measured TSOC correlated to water depth raised to the -0.4 to -0.5 power (TSOC = water depth**-0.4 to -0.5) for all investigated stations, but they could be divided into two groups representing different geographical areas with different sediment oxygen consumption characteristics. The differences in TSOC between the two areas were suggested to reflect hydrographic factors (such as ice coverage and import/production of reactive particulate organic material) related to the dominating water mass (Atlantic or polar) in each of the two areas. The good correlation between TSOC and water depth**-0.4 to -0.5 rules out any of the stations investigated to be topographic depressions with pronounced enhanced sediment oxygen consumption.

Concentrations of urea nitrogen in water of the northwestern Indian Ocean and Red Sea

Distribution of urea in different water layers of the northwestern Indian Ocean is described. It was found to be non-uniformly distributed. High concentration was found in waters close to the bottom. Urea may serve as an indicator of state of the water environment.