Physicochemical parameters of water sample the four coastal lagoons at the Peninsula of Yucatan

Study sites. Samples of surface water were taken from 4 coastal lagoons on the Yucatan Peninsula in Mexico: Celestun (20° 45' N - 90° 22' W), Chelem (21° 15' N - 89° 45' W), Rosada Lagoon (21º 19' N - 89º 19' W), and Sabancuy Estuary (18° 58' N - 91° 12' W). The sampling was performed from august to October of 2011 (Chelem 08/24; Laguna Rosada 09/06; Celestún 09/28; Sabancuy 10/25). The sampling was random without replacement and 10 samples of surface water were collected along a transect parallel to the coastal axis. Samples were deposited in sterile plastic bottles and conserved in refrigeration at 4°C. All samples were processed within 24 hours after sampling. According to the Mexican laws and regulations no permissions are required to obtain water and sediment samples from open public areas. Analysis of environmental and physicochemical parameters. Determinations of the environmental parameters were performed with a Hach 5465000 model 156 multi-parameter measuring instrument. The Lorenzen method was used to determine chlorophyll-a (21) with 90% acetone and the concentration was calculated according to the formula: Chla= 27.63 (OD665o - OD665a)(VA)/VM x L Where, OD665o: absorbance at 665 nm before acidification; OD665a: absorbance at 665 nm after acidification; VA: volume (ml) of acetone for extraction; VM: volume (ml) of filtered water; L: length (cm) of the photometric cell. Determinations of the physicochemical parameters (silicates, phosphates, nitrates, nitrites and ammonia) were performed using the spectrophotometric techniques described and modified by Strickland and Parsons (1972).

A compilation of global bio-optical in situ data for ocean-colour satellite applications

A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately.

Simultaneous high-resolution pH and spectrophotometric recordings of oxygen binding in native blood microvolumes, link to supplementary material

Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad range fibre optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along PO2 and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 µl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing PO2 from 0-21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single set up.

Mineralogy and age determination of sediment core D11957P

The Tore Seamount is a circular, volcano-like feature 100 km in diameter with its summit at 2200 m water depth and a small, 5000 m deep basin in its interior. It is situated approximately 300 km west of Lisbon and is surrounded by deep abyssal plains. This site with a standard pelagic stratigraphy is the southernmost point where the so-called Heinrich events have so far been recorded. A succession of alternating interglacial/glacial periods reveals a stratigraphic record back to the beginning of isotopic stage 7 (225 kyr). Climatic changes are identifiable by coherent variations in colour, carbonate content and distribution of ice-rafted detritus in the carbonate-free fraction. Inputs of ice-rafted quartz are well defined. Characteristics in common with other sites showing Heinrich layers include a high terrigenous to biogenic ratio, a dramatic decrease in the accumulation rate of foraminifera shells, an increase in dolomite abundance and the occurrence of polar foraminiferal species indicating southwards penetration of cold waters which lead us to consider a wider southeastern extent of the North Atlantic ice-rafted detritus belt than hitherto. If the presently accepted position of the Polar Front is maintained, icebergs must have been swept southwards from the southern boundary of the pack ice in a current merging into the ancestral Canary Current, bringing ice-rafted material to the Tore Seamount. The coincidence of reddish-feldspar, probably derived from the northern Appalachian Triassic red facies, with the transparent quartz suggests at least a partial Labrador source for all the Heinrich layers here, including HL 3. In comparison to other sites in the entire North Atlantic, two exceptions stand out: the absence of HL 5 and the low detritus to biogenics ratio for HL 3. The simultaneous occurrence of these two types of ice-rafted minerals is a new piece in the puzzle of the origin of Heinrich layers.

Age determination of sediment cores from the western Svalbard margin

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden, is discussed based on sub-bottom seismic records and sediment cores. The sea floor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjorden up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the 'normal' Holocene marine sediments. We conclude that the Barents Sea Ice Sheet terminated along the shelf break during the Late Weichselian glacial maximum. Radiocarbon dates from the glaciomarine sediments above the till indicate a stepwise deglaciation. Apparently the ice front retreated from the outermost shelf around 14.8 ka. A dramatic increase in the flux of line-grained glaciomarine sediments around 13 ka is assumed to reflect increased melting and/or current activity due to a climatic warming. This second stage of deglaciation was interrupted by a glacial readvance culminating on the mid-shelf area shortly after 12.4 ka. The glacial readvance, which is correlated with a simultaneous readvance of the Fennoscandian ice sheet along the western coast of Norway, is attributed to the so-called 'Older Dryas' cooling event in the North Atlantic region. Following this glacial readvance the outer part of Isfjorden became rapidly deglaciated around 12.3 ka. During the Younger Dryas the inner fjord branches were occupied by large outlet glaciers and possibly the ice front terminated far out in the main fjord. The remnants of the Barents Sea Ice Sheet melted quickly away as a response to the Holocene warming around 10 ka.

Pollen record and age determination of a sediment profile from Lake Teletskoye, Russia

A high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.

Age determination, planktic foraminifera and stable istopes of sediment core MSM05/5_712-2

A sediment core from the West Spitsbergen continental margin was studied to reconstruct climate and paleoceanographic variability during the last ~9 ka in the eastern Fram Strait. Our multiproxy evidence suggests that the establishment of the modern oceanographic configuration in the eastern Fram Strait occurred stepwise, in response to the postglacial sea-level rise and the related onset of modern sea-ice production on the shallow Siberian shelves. The late Early and Mid Holocene interval (9 to 5 ka) was generally characterized by relatively unstable conditions. High abundance of the subpolar planktic foraminifer species Turborotalita quinqueloba implies strong intensity of Atlantic Water (AW) inflow with high productivity and/or high AW temperatures, resulting in a strong heat flux to the Arctic. A series of short-lived cooling events (8.2, 6.9. and 6.1 ka) occurred superimposed on the warm late Early and Mid Holocene conditions. Our proxy data imply that simultaneous to the complete postglacial flooding of Arctic shallow shelves and the initiation of modern sea-ice production, strong advance of polar waters initiated modern oceanographic conditions in the eastern Fram Strait at ~5.2 ka. The Late Holocene was marked by the dominance of the polar planktic foraminifer species Neogloboquadrina pachyderma, a significant expansion of sea ice/icebergs, and strong stratification of the water column. Although planktic foraminiferal assemblages as well as sea surface and subsurface temperatures suggest a return of slightly strengthened advection of subsurface Atlantic Water after 3 ka, a relatively stable cold-water layer prevailed at the sea surface and the study site was probably located within the seasonally fluctuating marginal ice zone during the Neoglacial period.

Radiocarbon age determination of 16 sites

The thermal diffusion enrichment apparatus in use in Amsterdam before 1967, has been rebuilt in the Groningen Radiocarbon Dating Laboratory. It has been shown to operate reliably and reproducibly. A reasonable agreement exists between the theoretical calculations and the experimental results. The 14C enrichment of a CO sample is deduced from the simultaneous mass 30 enrichment, which is measured with a mass spectrometer. The relation between both enrichments follows from a series of calibration measurements. The over-all accuracy in the enrichment is a few percent, equivalent to a few hundred years in age. The main problem in dating very old samples is their possible contamination with recent carbon. Generally, careful sample selection and rigorous pretreatment reduce sample contamination to an acceptable value. Also, it has been established that laboratory contamination, due to a memory effect in the combustion system and to impurities in the oxygen and nitrogen gas used for combustion, can be eliminated. A detailed analysis shows that the counter background in our set-up is almost exclusively caused by cosmic ray muons. The measurement of 28 early glacial samples, mostly from North-west Europe, has yielded a consistent set of ages. These indicate the existence of three early glacial interstadials; using the Weichselian definitions: Amersfoort starting at 68 200 ± 1100, Brørup at 64 400 ± 800 and Odderade at 60 500 ± 600 years BP. This 14C chronology shows good agreement with the Camp Century chronology and the dated palaeo sea levels. The discrepancy in the age of the early part of the Last Glacial on the 14C time scale and on that adopted for the deep-sea d18 record, must probably be attributed to the use of a generalized d18 curve and a wrong interpretation of this curve in terms of three Barbados terraces.

Land based mesocosm experiment studying the simultaneous impact of warming and acidification on the planktonic food web of the Eastern Mediterranean

A land based mesocosm experiment focusing on the study of the simultaneous impact of warming and acidification on the planktonic food web of the Eastern Mediterranean took place in August-September 2013 at the mesocosm facilities of HCMR in Crete (CRETACOSMOS). Two different pCO2 (present day and predicted for year 2100) were applied in triplicate mesocosms of 3 m**3. This was tested in two different temperatures (ambient seawater T and ambient T plus 3°C). Twelve mesocosms in total were incubated in two large concrete tanks. Temperature was controlled by sophisticated, automated systems. A large variety of chemical, biological and biochemical variables were studied, including salinity, temperature, light and alkalinity measurements, inorganic and organic, particulate and dissolved, nutrient analyses, biological stock (Chla concentration, enumeration and community composition of microbial, phyto- and zooplankton organisms) and rate (primary, bacterial, viral production, copepod egg production, zooplankton grazing, N2 fixation, P uptake) measurements, bacterial DNA extraction and phytoplankton transcriptomics, calcifiers analyses. Twenty three scientists from 6 Institutes and 5 countries participated in this experiment.