Depth integrated nitrogen fixation from the northern Benguela upwelling system during METEOR cruise M100/1

Nitrogen fixation data from the cruise number M100 with research vessel "Meteor" from 01.09.-01.10.2013 (1st leg from Walvis Bay to Walvis Bay) in front of Namibia. Samples taken by CTD- rosette sampler from different depths and incubated in glass bottles (270-1070 ml) at light intensities that resemble the in situ light intensities of the sampling depth after 15N2 gas was injected to the sample. After the incubation time of 24 hours, the complete bottle content was filtered onto a pre-combusted Whatman GF/F filter. Filters were frozen, transported to the institute on dry ice and measured in a mass spectrometer for Delta 15N. The principle of the method was described by Montoya et al. (1996) and calculation was done according to their spread sheet. From the data of the single depths, the nitrogen fixation per square meter within the upper 40 m of the water column was calculated. The methods are described in detail in a paper submitted by Wasmund et al. in 2014 to be printed in 2015. Some results are surprisingly below zero. This occurs if the Delta 15N of the blank is higher than the measurement after incubation. It indicates that no nitrogen fixation occurred. Due to natural variability, the variability of the nitrogen fixation data is high. In an overall estimate, also over several cruises, negative and positive values compensate more or less, suggesting that nitrogen fixation is insignificant in the waters in front of northern Namibia and southern Angola.

Depth integrated nitrogen fixation from the northern Benguela upwelling system during METEOR cruise M103/2

Nitrogen fixation data from the cruise number M103/2 with research vessel "Meteor" from 21.01.-11.02.2014 (second leg from Walvis Bay to Walvis Bay) in front of Namibia. Samples taken by CTD- rosette sampler from different depths and incubated in glass bottles (535 ml) at light intensities that resemble the in situ light intensities of the sampling depth after 15N2 gas was injected to the sample. After the incubation time of 24 hours, the complete bottle content was filtered onto a pre-combusted Whatman GF/F filter. Filters were frozen, transported to the institute on dry ice and measured in a mass spectrometer for Delta15N. The principle of the method was described by Montoya et al. (1996) and calculation was done according to their spread sheet. From the data of the single depths, the nitrogen fixation per square meter within the upper 40 m of the water column was calculated. The methods are described in detail in a paper submitted by Wasmund et al. in 2014 to be printed in 2015. Some results are surprisingly below zero. This occurs if the Delta15N of the blank is higher than the measurement after incubation. It indicates that no nitrogen fixation occurred. Due to natural variability, the variability of the nitrogen fixation data is high. In an overall estimate, also over several cruises, negative and positive values compensate more or less, suggesting that nitrogen fixation is insignificant in the waters in front of northern Namibia and southern Angola.

Ostracodes in bottom sediments of the Laptev Sea

This work is the first detailed description of the Late Pleistocene-Holocene and Recent Ostracoda of the Laptev Sea. A total of 45 species in 22 genera and 13 families have been identified. All these species are described monographically. Three different ecological assemblages of ostracodes corresponding to different combinations of environmental parameters have been established; they are restricted to three regions of the sea: western-central, eastern, and southern. The recent ostracode assemblages of the Laptev Sea have been compared with those from other Arctic areas and are most similar to those of the Beaufort and Kara seas. Data on recent Ostracoda are used for paleoenvironmental reconstructions on the eastern shelf and western continental slope of the Laptev Sea. For this purpose, ostracodes from five sections obtained from these parts of the sea have been examined. The oldest sediments, which are of Late Pleistocene age (15.8 cal. ka BP), have been recovered in a core from the western continental slope. These yielded five ostracode assemblages, which correspond to different paleoenvironments and replaced each other in the course of the rapid postglacial sea-level rise, thus showing variations in the Atlantic water inflow from the west and freshwater discharge from the subaerially exposed shelf. On the outer shelf of the eastern part of the sea, the rapid sea-level rise in the Early Holocene (lowermost dating 11.3 cal. ka BP) led to a rapid transition from assemblages of brackish-water nearshore environments to those of modernlike normal marine environments; modern environments were established about 8.2 cal. ka ago. Since core sections from the inner shelf correspond to the time when the level of the sea had already reached its modern values, changes in taxonomic composition of ostracode assemblages primarily mirror variations in river runoff.

Age determination of ODP Leg 120 samples

Conventional K-Ar and 40Ar/39Ar analyses on whole-rock samples are reported for basaltic samples retrieved on the Central and Southern Kerguelen plateaus during Ocean Drilling Program Leg 120. Sites 747, 749, and 750 recovered basalts from the plateau basement, whereas Site 748 drilled a lava flow interbedded with sediments of probable Albian age. The freshest core basalts from the basement yielded dates falling in the 110-100 m.y. interval. Sample 120-749C-15R-3 (26-31 cm) gave conventional K-Ar, total fusion, and plateau 40Ar/39Ar ages that are closely concordant: 111.5 ± 3.2 m.y., 109.9 ± 1.2 m.y., and 109.6 ± 0.7 m.y., respectively. Sample 120-750B-15R-5 (54-60 cm), when taking into account the analytical uncertainties, yields conventional K-Ar and 40Ar/39Ar plateau ages that can be considered similar: 101.2 ± 7.5 and 118.2 ± 5 m.y., respectively. Inspection of the 39Ar/40Ar vs. 36Ar/40Ar diagram does not reveal the occurrence of an initial argon component of radiogenic composition in the two samples. Accordingly, our results suggest that the formation of the basement of the Central Kerguelen Plateau was closed at 110 m.y.. Furthermore, these results are in agreement with a K-Ar age of 114 ± 1 m.y. mentioned in the literature for a basalt dredged in the 77°E Graben. The still scant amount of data indicates that the outpourings of the Central Kerguelen Plateau correspond rather well with widespread continental magmatism in Gondwanaland that is believed to mark the incipient opening of the eastern Indian Ocean. This implies a huge head for the mantle plume at the source of these liquids. Nevertheless, on land and at sea the exact duration of magmatism remains unknown. Therefore, a catastrophic pattern similar to that currently invoked for the Deccan Traps at the end of the Cretaceous, though possible, is not yet required by present geochronologic data.

Microbiological investigations of the Canadian tundra

Microbial communities were analyzed at 17 sites visited during the expedition Tundra Northwest 1999 (TNW-99) by microscopic analyses (epifluorescence microscopy and image analyses). The data were used to describe the communities of bacteria, fungi and algae in detail by number, biovolume and biomass. Great variability was found, which could be related to organic matter content of soils and features of vegetation patterns. The amounts (numbers and abundance) of organisms and data on microbial biomass are discussed in relation to other polar environments of the Northern and Southern Hemispheres.

Sea surface temperature reconstruction of sediment core GeoB6518-1

Past hydrological changes in Africa have been linked to various climatic processes, depending on region and timescale. Long-term precipitation changes in the regions of northern and southern Africa influenced by the monsoons are thought to have been governed by precessional variations in summer insolation (Kutzbach and Liu, 1997, doi:10.1126/science.278.5337.440; Partridge et al., 1997, doi:10.1016/S0277-3791(97)00005-X). Conversely, short-term precipitation changes in the northern African tropics have been linked to North Atlantic sea surface temperature anomalies, affecting the northward extension of the Intertropical Convergence Zone and its associated rainbelt (Hastenrath, 1990, doi:10.1002/joc.3370100504, Street-Perrott and Perrott, 1990, doi:10.1038/343607a0). Our knowledge of large-scale hydrological changes in equatorial Africa and their forcing factors is, however, limited (Gasse, 2000, doi:10.1016/S0277-3791(99)00061-X). Here we analyse the isotopic composition of terrigenous plant lipids, extracted from a marine sediment core close to the Congo River mouth, in order to reconstruct past central African rainfall variations and compare this record to sea surface temperature changes in the South Atlantic Ocean. We find that central African precipitation during the past 20,000 years was mainly controlled by the difference in sea surface temperatures between the tropics and subtropics of the South Atlantic Ocean, whereas we find no evidence that changes in the position of the Intertropical Convergence Zone had a significant influence on the overall moisture availability in central Africa. We conclude that changes in ocean circulation, and hence sea surface temperature patterns, were important in modulating atmospheric moisture transport onto the central African continent.

Astronomically modulated Neogene sediment records of ODP Site 184-1148

General global cooling over the Neogene has been modulated by changes in Earth's orbital parameters. Investigations of deep-sea sediment sequences show that various orbital cycles can dominate climate records for different latitudes or for different time intervals. However, a comprehensive understanding of astronomical imprints over the entire Neogene has been elusive because of the general absence of long, continuous records extending beyond the Pliocene. We present benthic foraminiferal d18O and d13C records over the past 23 Ma at Ocean Drilling Program Site 1148 in the northern South China Sea and construct an astronomically tuned timescale (TJ08) for these records based on natural gamma radiation and color reflectance data at this site. Our results show that a 41 ka cycle has dominated sediment records at this location over the Neogene, displaying a linear response to orbital forcing. A 100 ka cycle has also been significant. However, it is correlated nonlinearly with Earth's orbital variations at the 100 ka band. The sediment records also display a prominent 405 ka cycle. Although this cycle was coherent with orbital forcing during the Oligocene and the early Miocene, it was not coherent with Earth's orbital variations at the 405 ka band over the whole Neogene. Amplification of Northern Hemisphere and Southern Hemisphere glaciation since the middle Miocene may be responsible for this change in sedimentary response. Our benthic foraminifera d18O and d13C records further exhibit amplitude variations with longer periods of 600, 1000, 1200, and 2400 ka. Apparently, these cycles are nonlinear responses to insolation forcing.

Compilation of d18O data, living planktic foraminifera

Most of the isotopic paleotemperature equations used for paleoceanographic reconstructions have been derived from culture experiments or inorganic precipitates of calcium carbonate. To test these equations in the modern ocean, we measured the oxygen isotope composition of planktonic foraminifera (Globigerinoides ruber, Globigerinoides sacculifer, Globigerina bulloides and Neogloboquadrina pachyderma) collected from Atlantic and Southern Ocean surface waters, and added published plankton tow data from the Pacific, Indian and Arctic Oceans. The resulting species-specific regression equations of the temperature:d18O relationships for G. ruber, G. sacculifer and G. bulloides are statistically indistinguishable. The equations derived for G. sacculifer and G. bulloides agree with relationships obtained from laboratory experiments, in which these species were cultured at pH values close to modern surface waters. The equation derived from N. pachyderma has a significantly lower slope and offset than the other three species but produces a regression equation that is nearly identical to the one for the epifaunal benthic foraminifer Cibicides sp. Our work on plankton tow and pumped samples indicates that culture-derived equations appear to be more appropriate for predicting the absolute d18O of the species examined compared to equations derived from inorganic precipitates. However, over the oceanic temperature range, the slopes of the equations we derive for living species agree with the slopes obtained from inorganic precipitates.

Lithostatigraphy of the CESAR cores

Sixteen piston cores and twelve gravity cores were successfully recovered from northern and southern crests of the eastern Alpha Ridge andfrom the Alpha Ridge graben. All but one core contain late Cenozoic muds with variable amounts of sand- to pebble-sized clastic material that probably reflects transport by ice during the past 4-5 Ma. Sixteen Cenozoic-Holocene lithostratigraphic units have been delimited on the basis of sediment texture, structure, colour, detrital carbonate and authigenicferromanganese content. The composition of the upper 13 units in the CESAR cores is similar to the Fletcher's Ice Island cores; hence most units can be broadly correlated over most of the Central Arctic Ocean. Three new lithostratigraphic units (A1-A3) occur at the base of CESAR cores from the northern Alpha Ridge crest. Paleomagnetic and palynological data indicate a Late Miocene-Early Pliocene age for unit A3, which confirms previous reports of a slow sedimentation rate during the Cenozoic. CESAR core 6 was obtained from an erosional surface on top of a fault block at the north edge of the Alpha Ridge graben. This core contains ca. 2m of laminated diatom ooze of Campanian-Maastrichtian age and two ?Paleogene volcanic ash units below a brown mud unit which probably corresponds to units A2 and A3. The biosiliceous ooze contains no foraminifera or silicoflagellates and only few dinoflagellates. There is little difference in biogenic or clastic sediment content between light and dark laminae and the rhythmites do not appear to be annual varves produced in an upwelling environment. The microstructure and fluctuating mineral composition of the laminae most closely resemble those of lami- nated chert beds in the Triassic forearc basins of Japan.

(Appendix A) Relative abundance of Emiliania huxleyi in sediment cores of the North Atlantic

The coccolithophore species Emiliania huxleyi is characterized by a wide range of sizes, which can be easily distinguished in the light microscope. In this study we have quantified the abundance of large (coccoliths > 4 µm in maximum length) E. huxleyi specimens during the last 25 kyr in sedimentary records from eleven cores and drill sites in the NE Atlantic and W Mediterranean Sea, to prove its usefulness in the reconstruction of water mass dynamics and biostratigraphic potential. During the Last Glacial Maximum this large form, a cold-water indicator, was common in the NE Atlantic and Mediterranean, and its regional variation in abundance indicates a displacement of the climatic zones southwards in agreement with the development of ice sheets and sea ice in the Northern Hemisphere during this period. On the other hand, the gradient between northern and southern surface water masses in the Subtropical Gyre appears to have been more pronounced than at present, while the Portugal and Canary Currents were more intense. In the western Mediterranean basin temperatures were cooler than in the adjacent Atlantic, provoking a quasi-endemism of these specimens until the end of Heinrich Event 1. This may have been due to a restriction in the communication between the Atlantic and Mediterranean through the Strait of Gibraltar, the arrival of cold surface water and the amplification of cooling after the development of ice sheets in the Northern Hemisphere. During the deglaciation, large E. huxleyi specimens decreased in abundance at medium and low latitudes, but were still numerous close to the Subarctic region during the Holocene. In transitional waters this decrease to present day abundances occurred after Termination Ib. The abrupt change in abundance of this large E. huxleyi form is proposed as a new biostratigraphic event to characterize the Holocene in mid- to low-latitude water masses in the North Atlantic, although this horizon seems to be diachronous by 5 kyr from tropical to subarctic regions, in agreement with the gradual onset of warm conditions.

Paleotemperature reconstructions on sediment core GIK161603-3

Different proxies for sea surface temperature (SST) often exhibit divergent trends for deglacial warming in tropical regions, hampering our understanding of the phase relationship between tropical SSTs and continental ice volume at glacial terminations. To reconcile divergent SST trends, we report reconstructions of two commonly used paleothermometers (the foraminifera G. ruber Mg/Ca and the alkenone unsaturation index) from a marine sediment core collected in the southwestern tropical Indian Ocean encompassing the last 37,000 years. Our results show that SSTs derived from the alkenone unsaturation index (UK'37) are consistently warmer than those derived from Mg/Ca by ~2-3°C except for the Heinrich Event 1. In addition, the initial timing for the deglacial warming of alkenone SST started at ~15.6 ka, which lags behind that of Mg/Ca temperatures by 2.5 kyr. We argue that the discrepancy between the two SST proxies reflects seasonal differences between summer and winter rather than post-depositional processes or sedimentary biases. The UK'37 SST record clearly mimics the deglacial SST trend recorded in the North Atlantic region for the earlier part of the termination, indicating the early deglacial warming trend attributed to local summer temperatures was likely mediated by changes in the Atlantic Meridional Overturning Circulation at the onset of the deglaciation, In contrast, the glacial to interglacial SST pattern recorded by G. ruber Mg/Ca probably reflects cold season SSTs. This indicates that the cold season SSTs was likely mediated by climate changes in the southern hemisphere, as it closely tracks the Antarctic timing of deglaciation. Therefore our study reveals that the tropical southwestern Indian Ocean seasonal SST was closely linked to climate changes occurring in both hemispheres. The austral summer and winter recorded by each proxy is further supported with seasonal SST trends modeled by AOGCMs for our core site. Our interpretation that the alkenone and Mg/Ca SSTs are seasonally biased may also explain similar proxy mismatches observed in other tropical regions at the onset of the last termination.

Depth integrated nitrogen fixation from the northern Benguela upwelling system during Maria S. Merain cruise MSM18/4

Nitrogen fixation data from the cruise number MSM18/4 with research vessel "Maria S. Merian" from 24.07.-20.08.2011 (from Libreville to Walvis Bay) in front of Angola and northern Namibia. Samples taken by CTD- rosette sampler from different depths and incubated in glass bottles (535 ml) at light intensities that resemble the in situ light intensities of the sampling depth after Delta 15 N2 gas was injected to the sample. After the incubation time of 6 hours, the complete bottle content was filtered onto a pre-combusted Whatman GF/F filter. Filters were frozen, transported to the institute on dry ice and measured in a mass spectrometer for Delta15N. The principle of the method was described by Montoya et al. (1996) and calculation was done according to their spread sheet. From the data of the single depths, the nitrogen fixation per square meter within the upper 40 m of the water column was calculated. The methods are described in detail in a paper submitted by Wasmund et al. in 2014 to be printed in 2015. Some results are surprisingly below zero. This occurs if the Delta15N of the blank is higher than the measurement after incubation. It indicates that no nitrogen fixation occurred. Due to natural variability, the variability of the nitrogen fixation data is high. In an overall estimate, also over several cruises, negative and positive values compensate more or less, suggesting that nitrogen fixation is insignificant in the waters in front of northern Namibia and southern Angola.

(Appendix table DR1) Foraminiferal distribution data for ODP Hole 178-1098B

Benthic foraminiferal data from Ocean Drilling Program Site 1098 indicate significant changes in deep-water conditions of the Palmer Deep, western Antarctic Peninsula margin, throughout the Holocene (13 ka to present). The earliest Holocene represents a period of transition from the Last Glacial Maximum (LGM). Cold bottom waters, similar to saline shelf water (SSW), dominated the middle Holocene. The late Holocene in the Palmer Deep has been characterized by alternating dominance of circumpolar deep water (CDW) and saline shelf water. These changes have global oceanographic and climatic implications. We suggest that the middle Holocene bottom-water record, in the absence of circumpolar deep water on the western Antarctic Peninsula shelf, indicates high saline shelf water production and/or weakened circumpolar deep water production during the middle Holocene climatic optimum. The late Holocene benthic foraminiferal record indicates rapidly fluctuating sea-ice conditions and may indicate a teleconnection between the South Pacific and Southern Ocean, thus having implications related to the Southern Oscillation Index.

Table 2 Overview of the established BIOTA Observatories in Africa & Appendix

The international, interdisciplinary biodiversity research project BIOTA AFRICA initiated a standardized biodiversity monitoring network along climatic gradients across the African continent. Due to an identified lack of adequate monitoring designs, BIOTA AFRICA developed and implemented the standardized BIOTA Biodiversity Observatories, that meet the following criteria (a) enable long-term monitoring of biodiversity, potential driving factors, and relevant indicators with adequate spatial and temporal resolution, (b) facilitate comparability of data generated within different ecosystems, (c) allow integration of many disciplines, (d) allow spatial up-scaling, and (e) be applicable within a network approach. A BIOTA Observatory encompasses an area of 1 km2 and is subdivided into 100 1-ha plots. For meeting the needs of sampling of different organism groups, the hectare plot is again subdivided into standardized subplots, whose sizes follow a geometric series. To allow for different sampling intensities but at the same time to characterize the whole square kilometer, the number of hectare plots to be sampled depends on the requirements of the respective discipline. A hierarchical ranking of the hectare plots ensures that all disciplines monitor as many hectare plots jointly as possible. The BIOTA Observatory design assures repeated, multidisciplinary standardized inventories of biodiversity and its environmental drivers, including options for spatial up- and downscaling and different sampling intensities. BIOTA Observatories have been installed along climatic and landscape gradients in Morocco, West Africa, and southern Africa. In regions with varying land use, several BIOTA Observatories are situated close to each other to analyze management effects.