Pedology, geochronology, palynology and macrofossils of soil profiles in the Altdarss area, german Baltic Sea coast

A new site with Lateglacial palaeosols covered by 0.8 - 2.4 m thick aeolian sands is presented. The buried soils were subjected to multidisciplinary analyses (pedology, micromorphology, geochronology, dendrology, palynology, macrofossils). The buried soil cover comprises a catena from relatively dry ('Nano'-Podzol, Arenosol) via moist (Histic Gleysol, Gleysol) to wet conditions (Histosol). Dry soils are similar to the so-called Usselo soil, as described from sites in NW Europe and central Poland. The buried soil surface covers ca. 3.4 km**2. Pollen analyses date this surface into the late Aller0d. Due to a possible contamination by younger carbon, radiocarbon dates are too young. OSL dates indicate that the covering by aeolian sands most probably occurred during the Younger Dryas. Botanical analyses enables the reconstruction of a vegetation pattern typical for the late Allerod. Large wooden remains of pine and birch were recorded.

Lagrangian back-tracing results for Kohnen station; output of time dependent numerical experiment with a 3D nested Antarctic ice sheet model

A nested ice flow model was developed for eastern Dronning Maud Land to assist with the dating and interpretation of the EDML deep ice core. The model consists of a high-resolution higher-order ice dynamic flow model that was nested into a comprehensive 3-D thermomechanical model of the whole Antarctic ice sheet. As the drill site is on a flank position the calculations specifically take into account the effects of horizontal advection as deeper ice in the core originated from higher inland. First the regional velocity field and ice sheet geometry is obtained from a forward experiment over the last 8 glacial cycles. The result is subsequently employed in a Lagrangian backtracing algorithm to provide particle paths back to their time and place of deposition. The procedure directly yields the depth-age distribution, surface conditions at particle origin, and a suite of relevant parameters such as initial annual layer thickness. This paper discusses the method and the main results of the experiment, including the ice core chronology, the non-climatic corrections needed to extract the climatic part of the signal, and the thinning function. The focus is on the upper 89% of the ice core (appr. 170 kyears) as the dating below that is increasingly less robust owing to the unknown value of the geothermal heat flux. It is found that the temperature biases resulting from variations of surface elevation are up to half of the magnitude of the climatic changes themselves.

High-resolution sedimentological and paleontological record of ODP Site 167-1019

Holocene and latest Pleistocene oceanographic conditions and the coastal climate of northern California have varied greatly, based upon high-resolution studies (ca. every 100 years) of diatoms, alkenones, pollen, CaCO3%, and total organic carbon at Ocean Drilling Program (ODP) Site 1019 (41.682°N, 124.930°W, 980 m water depth). Marine climate proxies (alkenone sea surface temperatures [SSTs] and CaCO3%) behaved remarkably like the Greenland Ice Sheet Project (GISP)-2 oxygen isotope record during the Bølling-Allerod, Younger Dryas (YD), and early part of the Holocene. During the YD, alkenone SSTs decreased by >3°C below mean Bølling-Allerod and Holocene SSTs. The early Holocene (ca. 11.6 to 8.2 ka) was a time of generally warm conditions and moderate CaCO3 content (generally >4%). The middle part of the Holocene (ca. 8.2 to 3.2 ka) was marked by alkenone SSTs that were consistently 1-2°C cooler than either the earlier or later parts of the Holocene, by greatly reduced numbers of the gyre-diatom Pseudoeunotia doliolus (<10%), and by a permanent drop in CaCO3% to <3%. Starting at ca. 5.2 ka, coastal redwood and alder began a steady rise, arguing for increasing effective moisture and the development of the north coast temperate rain forest. At ca. 3.2 ka, a permanent ca. 1°C increase in alkenone SST and a threefold increase in P. doliolus signaled a warming of fall and winter SSTs. Intensified (higher amplitude and more frequent) cycles of pine pollen alternating with increased alder and redwood pollen are evidence that rapid changes in effective moisture and seasonal temperature (enhanced El Niño-Southern Oscillation [ENSO] cycles) have characterized the Site 1019 record since about 3.5 ka.

Pigment, carbohydrate and protein content of microbial mats from northern Victoria Land lake sediments

The composition of algal pigments and extracellular polymeric substances (EPS) was determined in microbial mats from two lakes in Victoria Land (Continental Antarctica) with different lithology and environmental features. The aim was to expand knowledge of benthic autotrophic communities in Antarctic lacustrine ecosystems, providing reference data for future assessment of possible changes in environmental conditions and freshwater communities. The results of chemical analyses were supported by microscopy observations. Pigment profiles showed that filamentous cyanobacteria are dominant in both lakes. Samples from the water body at Edmonson Point had greater biodiversity, fewer pigments and lower EPS ratios than those from the lake at Kar Plateau. Differences in mat composition and in pigment and EPS profile between the two lakes are discussed in terms of local environmental conditions such as lithology, ice-cover and UV radiation. The present study suggests that a chemical approach could be useful in the study of benthic communities in Antarctic lakes and their variations in space and time.

Travel time and speed of gray whales and amphipod abundance along Chukotka Peninsula in 2006

The purpose of this study was to evaluate summer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instrumented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales travelled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements offshore. The average daily travel speeds were 23 km/day (range 9-53 km/day). Four of the whales had daily average travel speeds <1 km/day suggesting strong fidelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km**2 (range 7,097-15,896 km**2). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average ~54 g wet wt/m**2 in 2006. It is likely that the abundant benthic biomass is more than sufficient forage to support the current gray whale population. The use of satellite telemetry in this study quantifies space use and movement patterns of gray whales along the Chukotka coast and identifies key feeding areas.

Palynology, source vegetation, environment and age of ODP Site 188-1166 sediments

Twenty-three core catcher samples from Site 1166 (Hole 1166A) in Prydz Bay were analyzed for their palynomorph content, with the aims of determining the ages of the sequence penetrated, providing information on the vegetation of the Antarctic continent at this time, and determining the environments under which deposition occurred. Dinocysts, pollen and spores, and foraminiferal test linings were recovered from most samples in the interval from 142.5 to 362.03 meters below seafloor (mbsf). The interval from 142.5 to 258.72 mbsf yielded palynomorphs indicative of a middle-late Eocene age, equivalent to the lower-middle Nothofagidites asperus Zone of the Gippsland Basin of southeastern Australia. The Prydz Bay sequence represents the first well-dated section of this age from East Antarctica. Dinocysts belonging to the widespread "Transantarctic Flora" give a more confident late Eocene age for the interval 142.5-220.5 mbsf. The uppermost two cores within this interval, namely, those from 142.5 and 148.36 mbsf, show significantly higher frequencies of dinocysts than the cores below and suggest that an open marine environment prevailed at the time of deposition. The spore and pollen component may reflect a vegetation akin to the modern rainforest scrubs of Tasmania and New Zealand. Below 267 mbsf, sparse microfloras, mainly of spores and pollen, are equated with the Phyllocladidites mawsonii Zone of southeastern Australia, which is of Turonian to possibly Santonian age. Fluvial to marginal marine environments of deposition are suggested. The parent vegetation from this interval is here described as "Austral Conifer Woodland." The same Late Cretaceous microflora occurs in two of the cores above the postulated unconformity at 267 mbsf. In the core at 249.42 mbsf, the Late Cretaceous spores and pollen are uncontaminated by any Tertiary forms, suggesting that a clast of this older material has been sampled; such a clast may reflect transport by ice during the Eocene. At 258.72 mbsf, Late Cretaceous spores and pollen appear to have been recycled into the Eocene sediments.

Avian species identity and predation success in tropical cacao agroforestry of the Napu Valley in Central Sulawesi, Indonesia

Avian ecosystem services such as the suppression of pests are considered being of high ecological and economic importance in a range of ecosystems, especially in tropical agroforestry. But how bird predation success is related to the diversity and composition of the bird community, as well as local and landscape factors, is poorly understood. The author quantified arthropod predation in relation to the identity and diversity of insectivorous birds, using experimental exposure of artificial, caterpillar-like prey on smallholder cacao agroforestry systems, differing in local shade management and distance to primary forest. The bird community was assessed using both mist netting (targeting on active understory insectivores) and point count (higher completeness of species inventories) sampling. The study was conducted in a land use dominated area in Central Sulawesi, Indonesia, adjacent to the Lore Lindu National Park. We selected 15 smallholder cacao plantations as sites for bird and bat exclosure experiments in March 2010. Until July 2011, we recorded several data in this study area, including the bird community data, cacao tree data and bird predation experiments that are presented here. We found that avian predation success can be driven by single and abundant insectivorous species, rather than by overall bird species richness. Forest proximity was important for enhancing the density of this key species, but did also promote bird species richness. The availability of local shade trees had no effects on the local bird community or avian predation success. Our findings are both of economical as well as ecological interest because the conservation of nearby forest remnants will likely benefit human needs and biodiversity conservation alike.

Pollen analysis of surface sediment off northwest Africa

Over 100 samples of recent surface sediments from the bottomn of the Atlantic Ocean offshore NW Africa between 34° and 6° N have been analysed palynologically. The objective of this study was to reveal the relation between source areas, transport systems, and resulting distribution patterns of pollen and spores in marine sediments off NW Africa, in order to lay a sound foundation for the interpretation of pollen records of marine cores from this area. The clear zonation of the NW-African vegetation (due to the distinct climatic gradient) is helpful in determining main source areas, and the presence of some major wind belts facilitates the registration of the average course of wind trajectories. The present circulation pattern is driven by the intertropical front (ITCZ) which shifts over the continent between c. 22° N (summer position) and c. 4° N (winter position) in the course of the year. Determination of the period of main pollen release and the average atmospheric circulation pattern effective at that time of the years is of prime importance. The distribution patterns in recent marine sediments of pollen of a series of genera and families appear to record climatological/ecological variables, such as the trajectory of the NE trade, January trades, African Easterly Jet (Saharan Air Layer), the northernmost and southernmost position of the intertropical convergence zone, and the extent and latitudinal situation of the NW-African vegetation belt. Pollen analysis of a series of dated deep-sea cores taken between c. 35° and the equator off NW African enable the construction of paleo-distribution maps for time slices of the past, forming a register of paleoclimatological/paleoecological information.

Ba distribution in surface sediments of the Southern Ocean

We present excess Ba (Baxs) data (i.e., total Ba corrected for lithogenic Ba) for surface sediments from a north-south transect between the Polar Front Zone and the northern Weddell Gyre in the Atlantic sector and between the Polar Front Zone and the Antarctic continent in the Indian sector. Focus is on two different processes that affect excess Ba accumulation in the sediments: sediment redistribution and excess Ba dissolution. The effect of these processes needs to be corrected for in order to convert accumulation rate into vertical rain rate, the flux component that can be linked to export production. In the Southern Ocean a major process affecting Ba accumulation rate is sediment focusing, which is corrected for using excess 230Th. This correction, however, may not always be straightforward because of boundary scavenging effects. A further major process affecting excess Ba accumulation is barite dissolution during exposure at the sediment-water column interface. Export production estimates derived from excess 230Th and barite dissolution corrected Baxs accumulation rates (i.e., excess Ba vertical rain rates) are of the same magnitude but generally larger than export production estimates based on water column proxies (234Th-deficit in the upper water column; particulate excess Ba enrichment in the mesopelagic water column). We believe export production values based on excess Ba vertical rain rate might be overestimated due to inaccurate assessment of the Baxs preservation rate. Barite dissolution has, in general, been taken into account by relating it to exposure time before burial depending on the rate of sediment accumulation. However, the observed decrease of excess Ba content with increasing water column depth (or increasing hydrostatic pressure) illustrates the dependence of barite preservation on degree of saturation in the deep water column in accordance with available thermodynamic data. Therefore correction for barite dissolution would not be appropriate by considering only exposure time of the barite to some uniformly undersaturated deep water but requires also that regional differences in degree of undersatuation be taken into account.