Pollen and diatom analysis on varved sediments in Lake Jues (Harz Mountains, Germany)

Studies combining sedimentological and biological evidence to reconstruct Holocene climate beyond the major changes, and especially seasonality, are rare in Europe, and are nearly completely absent in Germany. The present study tries to reconstruct changes of seasonality from evidence of annual algal successions within the framework of well-established pollen zonation and 14C-AMS dates from terrestrial plants. Laminated Holocene sediments in Lake Jues (10°20.70' E, 51°39.30' N, 241 m a.s.l.), located at the SW margin of the Harz Mountains, central Germany, were studied for sediment characteristics, pollen, diatoms and coccal green algae. An age model is based on 21 calibrated AMS radiocarbon dates from terrestrial plants. The sedimentary record covers the entire Holocene period. Trophic status and circulation/stagnation patterns of the lake were inferred from algal assemblages, the subannual structure of varves and the physico-chemical properties of the sediment. During the Holocene, mixing conditions alternated between di-, oligo- and meromictic depending on length and variability of spring and fall periods, and the stability of winter and summer weather. The trophic state was controlled by nutrient input, circulation patterns and the temperature-dependent rates of organic production and mineralization. Climate shifts, mainly in phase with those recorded from other European regions, are inferred from changing limnological conditions and terrestrial vegetation. Significant changes occurred at 11,600 cal. yr. BP (Preboreal warming), between 10,600 and 10,100 cal. yr. BP (Boreal cooling), and between 8,400 and 4,550 cal. yr. BP (warm and dry interval of the Atlantic). Since 4,550 cal. yr. BP the climate became gradually cooler, wetter and more oceanic. This trend was interrupted by warmer and dryer phases between 3,440 and 2,850 cal. yr. BP and, likely, between 2,500 and 2,250 cal. yr. BP.

MARECHIARA-mesozooplankton long-term time-series at the fixed coastal station in the Gulf of Naples: abundance and biomass, data for the years 1984-2006

The MARECHIARA-mesozooplankton dataset contains mesozooplankton data collected in the ongoing time-series at Sation MC (40°48.5' N, 14°15' E) in the Gulf of Naples. This dataset spans over the period 1984-2006 and contains data of mesozooplankton abundance and species composition as well as biomass (as dry weight). Mesozooplankton was regularly sampled in 1984-1990 and 1995-2006, only a few samples were collected in 1991-1992 and no samples in 1993-1994. During the first period of the series sampling frequency was fortnightly, and weekly since 1995.

Early Eocene benthic foraminifera of DSDP Hole 48-401

Within the last decade, several early Eocene hyperthermals have been detected globally. These transient warming events have mainly been characterized geochemically - using stable isotopes, carbonate content measurements or XRF core scanning - yet detailed micropaleontological records are sparse, limiting our understanding of the driving forces behind hyperthermals and of the contemporaneous paleoceanography. Here, detailed geochemical and quantitative benthic foraminiferal records are presented from lower Eocene pelagic sediments of Deep Sea Drilling Project Site 401 (Bay of Biscay, northeast Atlantic). In calcareous nannofossil zone NP11, several clay-enriched levels correspond to negative d13C and d18O bulk-rock excursions with amplitudes of up to ~0.75 per mil, suggesting that significant injections of 12C-enriched greenhouse gasses and small temperature rises took place. Coeval with several of these hyperthermal events, the benthic foraminiferal record reveals increased relative abundances of oligotrophic taxa (e.g. Nuttallides umbonifera) and a reduction in the abundance of buliminid species followed by an increase of opportunistic taxa (e.g. Globocassidulina subglobosa and Gyroidinoides spp.). These short-lived faunal perturbations are thought to be caused by reduced seasonality of productivity resulting in a decreased Corg flux to the seafloor. Moreover, the sedimentological record suggests that an enhanced influx of terrigenous material occurred during these events. Additionally, the most intense d13C decline (here called level d) gives rise to a small, yet pronounced long-term shift in the benthic foraminiferal composition at this site, possibly due to the reappraisal of upwelling and the intensification of bottom water currents. These observations imply that environmental changes during (smaller) hyperthermal events are also reflected in the composition of deep-sea benthic communities on both short (<100 kyr) and longer time scales. We conclude that the faunal patterns of the hyperthermals observed at Site 401 strongly resemble those observed in other deep-sea early Paleogene hyperthermal deposits, suggesting that similar processes have driven them.

Benthic foraminifera extinctions in the Cenozoic record

In the late Pliocene-middle Pleistocene a group of 95 species of elongate, cylindrical, deep-sea (lower bathyal-abyssal) benthic foraminifera became extinct. This Extinction Group (Ext. Gp), belonging to three families (all the Stilostomellidae and Pleurostomellidae, some of the Nodosariidae), was a major component (20-70%) of deep-sea foraminiferal assemblages in the middle Cenozoic and subsequently declined in abundance and species richness before finally disappearing almost completely during the mid-Pleistocene Climatic Transition (MPT). So what caused these declines and extinction? In this study 127 Ext. Gp species are identified from eight Cenozoic bathyal and abyssal sequences in the North Atlantic and equatorial Pacific Oceans. Most species are long-ranging with 80% originating in the Eocene or earlier. The greatest abundance and diversity of the Ext. Gp was in the warm oceanic conditions of the middle Eocene-early Oligocene. The group was subjected to significant changes in the composition of the faunal dominants and slightly enhanced species turnover during and soon after the rapid Eocene-Oligocene cooling event. Declines in the relative abundance and flux of the Ext. Gp, together with enhanced species loss, occurred during middle-late Miocene cooling, particularly at abyssal sites. The overall number of Ext. Gp species present began declining earlier at mid abyssal depths (in middle Miocene) than at upper abyssal (in late Pliocene-early Pleistocene) and then lower bathyal depths (in MPT). By far the most significant Ext. Gp declines in abundance and species loss occurred during the more severe glacial stages of the late Pliocene-middle Pleistocene. Clearly, the decline and extinction of this group of deep-sea foraminifera was related to the function of their specialized apertures and the stepwise cooling of global climate and deep water. We infer that the apertural modifications may be related to the method of food collection or processing, and that the extinctions may have resulted from the decline or loss of their specific phytoplankton or prokaryote food source, that was more directly impacted than the foraminifera by the cooling temperatures.

Abundance of mesozooplankton from nine cruises in Northern Adriatic Sea during NA64

The NA64-Mesozooplankton dataset contains biogeochemistry and mesozooplankton data collected in a series of 9 cruises in the Northern Adriatic completed from January 1965 to September 1965 monthly, and December 1965. Biogeochemistry sampling was undertaken using 5L Nansen bottles fired at 0m, 5m, 10m, 20m, 30m and/or bottom depths. The dataset includes 709 samples analysed for nitrate, phosphate, temperature, salinity and density. Mesozooplankton sampling was undertaken at the same locations as for biogeochemistry, using two different net (Hensen non-closing and Appstein closing net). The dataset includes 146 samples analysed for mesozooplankton composition (at higher taxonomic level), abundance and volume settlement. After sedimentation and volume measurement, the fish larva and fish eggs were extracted from samples (egss of Engraulis encrasicholus were determined). Chaetognaths were partly isolated. Identification at higher taxonomic level of zooplankters was completed. Taxonomic identification was done at Smithonian Mediterranean Centre in Salambo. After sedimentation and volume measurement, the fish larva and fish eggs were extracted from samples (egss of Engraulis encrasicholus were determined). Chaetognaths were partly isolated. Identification at higher taxonomic level of zooplankters was completed. Taxonomic identification was done at Smithonian Mediterranean Centre in Salambo.

Abundance of mesozooplankton collected in October and November 1991 at 20 stations in the South Aegean Sea during O91

The O91- Mesozooplankton dataset is based on samples collected in mid October-mid November 1991 at 20 stations in the South Aegean, the SE.Ionian Sea and in NW Levantine. Samples were collected at discrete layers (from the surface till 300m. These data are published. Sampling volume was estimated by multiplying the mouth area with the wire length. The entire sample (for deep layers) or aliquot of Taxon-specific mesozooplankton abundance (1/4) (for the upper layer) was analyzed under the binocular microscope. Copepod and cladoceran species were identified and enumerated; the other zooplankters were identified and enumerated at higher taxonomic level (commonly named as zooplankton groups). Taxonomic identification was done by I.Siokou-Frangou, E.Christou, and N.Fragopoulu, using the relevant taxonomic literature. The entire sample (for deep layers) or aliquot of Mesozooplankton total abundance (1/4) (for the upper layer) was analyzed under the binocular microscope. All zooplankters were enumerated.

Occurence of foraminifera and other microfossils in sediment core CRP-2/2A (Table 1)

Sparse to moderately abundant foraminiferal assemblages from Oligocene and Lower Miocene sediments in the CRP-2/2A drillhole contain C.27 genera and 42 species of calcareous benthic foraminifera. No planktic or agglutinated taxa were observed. On the basis of their faunal characteristics, four Foraminiferal Units are defined in drillhole succession: Foraminiferal Unit I (26.91-193.95 mbsf), mostly sparse assemblages with Elphidium magellanicum and Cribroelphidium sp.; Foraminiferal Unit II (193.95-342.42 mbsf), mostly moderately abundant assemblages with Cassidulinoides aequilatera and Eponides bradyi; Foraminiferal Unit III (342.42-486.19 mbsf), moderately abundant to sparse assemblages characterised by Cassidulinoides chapmani and Stainforthia sp.; and Foraminiferal Unit IV, Improverished (486.19-624.15, total depth, mbsf), with mostly barren residues, but with large Milioliidae recorded in situ at various horizons in the drill core. Foraminiferal Units I-IV lack taxa allowing correlation to standard zonal schemes. Inspection of faunal records from CIROS-1 and DSDP 270 indicates that, although the faunas show an overall similarity, CRP-2/2A Foraminiferal Units I-IV are not identifiable at these sites. The units are therefore most likely to reflect local environmental changes, and probably will prove useful for local correlation, but their lateral extent is undetermined. All four assemblages apparently represent various glacially-influenced shelf environments, and appear to reflect a long term deepening trend from Units IV to II, from perhaps inner to mid or outer-shelf depths, followed by a return to shallower, inner shelf, conditios for Unit I.