Gene sequences of the lichen Cetraria aculeata

Lichens are symbioses between fungi (mycobionts) and photoautotrophic green algae or cyanobacteria (photobionts). Many lichens occupy large distributional ranges covering several climatic zones. So far, little is known about the large-scale phylogeography of lichen photobionts and their role in shaping the distributional ranges of lichens. We studied south polar, temperate and north polar populations of the widely distributed fruticose lichen Cetraria aculeata. Based on the DNA sequences from three loci for each symbiont, we compared the genetic structure of mycobionts and photobionts. Phylogenetic reconstructions and Bayesian clustering methods divided the mycobiont and photobiont data sets into three groups. An AMOVA shows that the genetic variance of the photobiont is best explained by differentiation between temperate and polar regions and that of the mycobiont by an interaction of climatic and geographical factors. By partialling out the relative contribution of climate, geography and codispersal, we found that the most relevant factors shaping the genetic structure of the photobiont are climate and a history of codispersal. Mycobionts in the temperate region are consistently associated with a specific photobiont lineage. We therefore conclude that a photobiont switch in the past enabled C. aculeata to colonize temperate as well as polar habitats. Rare photobiont switches may increase the geographical range and ecological niche of lichen mycobionts by associating them with locally adapted photobionts in climatically different regions and, together with isolation by distance, may lead to genetic isolation between populations and thus drive the evolution of lichens.

Tab.1: Representative bulk-rock and trace element chemistry

High-pressure/low-temperature metabasites occupy a definite geological position within the structure of the Polar Urals and have a very important bearing on the understanding of the early history of the Ural Mountains. Recently obtained geological, petrographic, geochemical and isotope data allow some conclusions on this history. The metabasites of the Khord"yus and Dzela complexes contain relics of a Neoproterozoic (578 ±8 Ma) oceanic crust. This crust formed part of the base of the early Paleozoic (500 Ma) ensimatic island arc and experienced Ca-Al-Si±Na metasomatism and, probably, partial melting with the formation of boninite melts. However, so far no boninite volcanics have been found. The metabasites at the base of the island arc took part in the collision and as a consequence experienced glaucophane schist and greenschist facies metamorphism during the collision and obduction over the passive Baltic margin 350 ±11 Ma ago.

(Table 1) Characteristics of Klebsormidium (filamentous green algae) strains from the Antarctic, Arctic and Slovakia

The freezing and desiccation tolerance of 12 Klebsormidium strains, isolated from various habitats (aero-terrestrial, terrestrial, and hydro-terrestrial) from distinct geographical regions (Antarctic - South Shetlands, King George Island, Arctic - Ellesmere Island, Svalbard, Central Europe - Slovakia) were studied. Each strain was exposed to several freezing (-4°C, -40°C, -196°C) and desiccation (+4°C and +20°C) regimes, simulating both natural and semi-natural freeze-thaw and desiccation cycles. The level of resistance (or the survival capacity) was evaluated by chlorophyll a content, viability, and chlorophyll fluorescence evaluations. No statistical differences (Kruskal-Wallis tests) between strains originating from different regions were observed. All strains tested were highly resistant to both freezing and desiccation injuries. Freezing down to -196°C was the most harmful regime for all studied strains. Freezing at -4°C did not influence the survival of studied strains. Further, freezing down to -40°C (at a speed of 4°C/min) was not fatal for most of the strains. RDA analysis showed that certain Antarctic and Arctic strains did not survive desiccation at +4°C; however, freezing at -40°C, as well as desiccation at +20 °C was not fatal to them. On the other hand, other strains from the Antarctic, the Arctic, and Central Europe (Slovakia) survived desiccation at temperatures of +4°C, and freezing down to -40°C. It appears that species of Klebsormidium which occupy an environment where both seasonal and diurnal variations of water availability prevail, are well adapted to freezing and desiccation injuries. Freezing and desiccation tolerance is not species-specific nor is the resilience only found in polar strains as it is also a feature of temperate strains.

Distribution models for mountain plant species: The value of elevation

The climatic conditions of mountain habitats are greatly influenced by topography. Large differences in microclimate occur with small changes in elevation, and this complex interaction is an important determinant of mountain plant distributions. In spite of this, elevation is not often considered as a relevant predictor in species distribution models (SDMs) for mountain plants. Here, we evaluated the importance of including elevation as a predictor in SDMs for mountain plant species. We generated two sets of SDMs for each of 73 plant species that occur in the Pacific Northwest of North America; one set of models included elevation as a predictor variable and the other set did not. AUC scores indicated that omitting elevation as a predictor resulted in a negligible reduction of model performance. However, further analysis revealed that the omission of elevation resulted in large over-predictions of species' niche breadths-this effect was most pronounced for species that occupy the highest elevations. In addition, the inclusion of elevation as a predictor constrained the effects of other predictors that superficially affected the outcome of the models generated without elevation. Our results demonstrate that the inclusion of elevation as a predictor variable improves the quality of SDMs for high-elevation plant species. Because of the negligible AUC score penalty for over-predicting niche breadth, our results support the notion that AUC scores alone should not be used as a measure of model quality. More generally, our results illustrate the importance of selecting biologically relevant predictor variables when constructing SDMs.

(Table 1) Reproductive performance of brown skua pairs with and without feeding territories at Potter Peninsula/King George Island from 1998/1999 to 2000/2001

In the maritime Antarctic, brown skuas (Catharacta antarctica lonnbergi) show two foraging strategies: some pairs occupy feeding territories in penguin colonies, while others can only feed in unoccupied areas of a penguin colony without defending a feeding territory. One-third of the studied breeding skua population in the South Shetlands occupied territories of varying size (48 to >3,000 penguin nests) and monopolised 93% of all penguin nests in sub-colonies. Skuas without feeding territories foraged in only 7% of penguin sub-colonies and in part of the main colony. Females owning feeding territories were larger in body size than females without feeding territories; no differences in size were found in males. Territory holders permanently controlled their resources but defence power diminished towards the end of the reproductive season. Territory ownership guaranteed sufficient food supply and led to a 5.5 days earlier egg-laying and chick-hatching. Short distances between nest and foraging site allowed territorial pairs a higher nest-attendance rate such that their chicks survived better (71%) than chicks from skua pairs without feeding territories (45%). Due to lower hatching success in territorial pairs, no difference in breeding success of pairs with and without feeding territories was found in 3 years. We conclude that skuas owning feeding territories in penguin colonies benefit from the predictable and stable food resource by an earlier termination of the annual breeding cycle and higher offspring survivorship.

Microcharcoal concentration and elongation, and age model of sediment core MD96-2098

Although grassland and savanna occupy only a quarter of the world's vegetation, burning in these ecosystems accounts for roughly half the global carbon emissions from fire. However, the processes that govern changes in grassland burning are poorly understood, particularly on time scales beyond satellite records. We analyzed microcharcoal, sediments, and geochemistry in a high-resolution marine sediment core off Namibia to identify the processes that have controlled biomass burning in southern African grassland ecosystems under large, multimillennial-scale climate changes. Six fire cycles occurred during the past 170,000 y in southern Africa that correspond both in timing and magnitude to the precessional forcing of north-south shifts in the Intertropical Convergence Zone. Contrary to the conventional expectation that fire increases with higher temperatures and increased drought, we found that wetter and cooler climates cause increased burning in the study region, owing to a shift in rainfall amount and seasonality (and thus vegetation flammability). We also show that charcoal morphology (i.e., the particle's length-to-width ratio) can be used to reconstruct changes in fire activity as well as biome shifts over time. Our results provide essential context for understanding current and future grassland-fire dynamics and their associated carbon emissions.

Food composition of beryx-alfonsino over submarine rises near Azores

Qualitative and quantitative food composition, as well as intensity of feeding of beryx-alfonsino Beryx splendens was examined on banks near the Azores. Data are presented with respect to size groups and taking into account type of feeding of males and females. Crustaceans and fishes were constituents of their feeding ration. A tendency toward increase in the number of consumed fishes in the course of ontogenetic development of beryx-alfonsino was noted. Beryx-alfonsino was shown to occupy the trophic level of consumers of the third order performing function of a deep-water predator.

Sedimentology and gas hydrates of IODP Expedition 311 samples

Expedition 311 of the Integrated Ocean Drilling Program (IODP) to northern Cascadia recovered gas-hydrate bearing sediments along a SW-NE transect from the first ridge of the accretionary margin to the eastward limit of gas-hydrate stability. In this study we contrast the gas gas-hydrate distribution from two sites drilled ~ 8 km apart in different tectonic settings. At Site U1325, drilled on a depositional basin with nearly horizontal sedimentary sequences, the gas-hydrate distribution shows a trend of increasing saturation toward the base of gas-hydrate stability, consistent with several model simulations in the literature. Site U1326 was drilled on an uplifted ridge characterized by faulting, which has likely experienced some mass wasting events. Here the gas hydrate does not show a clear depth-distribution trend, the highest gas-hydrate saturation occurs well within the gas-hydrate stability zone at the shallow depth of ~ 49 mbsf. Sediments at both sites are characterized by abundant coarse-grained (sand) layers up to 23 cm in thickness, and are interspaced within fine-grained (clay and silty clay) detrital sediments. The gas-hydrate distribution is punctuated by localized depth intervals of high gas-hydrate saturation, which preferentially occur in the coarse-grained horizons and occupy up to 60% of the pore space at Site U1325 and > 80% at Site U1326. Detailed analyses of contiguous samples of different lithologies show that when enough methane is present, about 90% of the variance in gas-hydrate saturation can be explained by the sand (> 63 µm) content of the sediments. The variability in gas-hydrate occupancy of sandy horizons at Site U1326 reflects an insufficient methane supply to the sediment section between 190 and 245 mbsf.

Abundance patterns and isotopic signals of morphotypes of Globigerinoides ruber

The chemical composition of shells of the planktonic foraminifer Globigerinoides ruber (white) is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. Here, we investigate the occurrence through time and in space of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the central and the eastern Mediterranean Sea. In 115 samples representing two distinct time intervals (MIS 1-2 and MIS 9-12) at ODP Site 964 and the piston core GeoTü-SL96, we have defined three morphological types within this species and determined their relative abundances and stable isotopic composition. A quantitative analysis of morphological variation within G. ruber (white) in four samples revealed that the subjectively defined morphotypes occupy separate segments of a continuous and homogenous morphospace. We further show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the three morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within glacial and interglacial stages but their sign is systematically reversed between the two Sites. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1per mil, their understanding is essential for the interpretation of all G. ruber-based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary.

Potential connections (least-cost paths) between existing and potential bison habitat patches in the Carpathian Mountains

Habitat connectivity is important for the survival of species that occupy habitat patches too small to sustain an isolated population. A prominent example of such a species is the European bison (Bison bonasus), occurring only in small, isolated herds, and whose survival will depend on establishing larger, well-connected populations. Our goal here was to assess habitat connectivity of European bison in the Carpathians. We used an existing bison habitat suitability map and data on dispersal barriers to derive cost surfaces, representing the ability of bison to move across the landscape, and to delineate potential connections (as least-cost paths) between currently occupied and potential habitat patches. Graph theory tools were then employed to evaluate the connectivity of all potential habitat patches and their relative importance in the network. Our analysis showed that existing bison herds in Ukraine are isolated. However, we identified several groups of well-connected habitat patches in the Carpathians which could host a large population of European bison. Our analysis also located important dispersal corridors connecting existing herds, and several promising locations for future reintroductions (especially in the Eastern Carpathians) that should have a high priority for conservation efforts. In general, our approach indicates the most important elements within a landscape mosaic for providing and maintaining the overall connectivity of different habitat networks and thus offers a robust and powerful tool for conservation planning.

Geochemistry and isotopic ratios of boninites and related rocks of the Izu-Bonin Forearc

Twenty-six samples representing the wide range of lithologies (low- and intermediate-Ca boninites and bronzite andesites, high-Ca boninites, basaltic andesites-rhyolites) drilled during Leg 125 at Sites 782 and 786 on the Izu-Bonin outer-arc high have been analyzed for Sr, Nd, and Pb isotopes. Nd-Sr isotope covariations show that most samples follow a trend parallel to a line from Pacific MORB mantle (PMM) to Pacific Volcanogenic sediment (PVS) but displaced slightly toward more radiogenic Sr. Pb isotope covariations show that all the Eocene-Oligocene samples plot along the Northern Hemisphere Reference Line, indicating little or no Pb derived from subducted pelagic sediment in their source. Two young basaltic andesite clasts within sediment do have a pelagic sediment signature but this may have been gained by alteration rather than subduction. In all isotopic projections, the samples form consistent groupings: the tholeiites from Site 782 and Hole 786A plot closest to PMM, the boninites and related rocks from Sites 786B plot closest to PVS, and the boninite lavas from Hole 786A and late boninitic dikes from Hole 786B occupy an intermediate position. Isotope-trace element covariations indicate that these isotopic variations can be explained by a three-component mixing model. One component (A) has the isotopic signature of PMM but is depleted in the more incompatible elements. It is interpreted as representing suboceanic mantle lithosphere. A second component (B) is relatively radiogenic (epsilon-Nd = ca 4-6; 206Pb/204Pb = ca 19.0-19.3; epsilon-Sr = ca -10 to -6)). Its trace element pattern has, among other characteristics, a high Zr/Sm ratio, which distinguishes it from the ìnormalî fluid components associated with subduction and hotspot activity. There are insufficient data at present to tie down its origin: probably it was either derived from subducted lithosphere or volcanogenic sediment fused in amphibolite facies; or it represents an asthenospheric melt component that has been fractionated by interaction with amphibole-bearing mantle. The third component (C) is characterized by high contents of Sr and high epsilon-Sr values and is interpreted as a subducted fluid component. The mixing line on a diagram of Zr/Sr against epsilon-Sr suggests that component C may have enriched the lithosphere (component A) before component B. These components may also be present on a regional basis but, if so, may not have had uniform compositions. Only the boninitic series from nearby Chichijima would require an additional, pelagic sediment component. In general, these results are consistent with models of subduction of ridges and young lithosphere during the change from a ridge-transform to subduction geometry at the initiation of subduction in the Western Pacific.

Archive of the PASATA (PASsive Acoustic Tracking of Antarctic marine mammals) field documentation

Recordings from the PerenniAL Acoustic Observatory in the Antarctic ocean (PALAOA) show seasonal acoustic presence of 4 Antarctic ice-breeding seal species (Ross seal, Ommatophoca rossii, Weddell seal, Leptonychotes weddellii, crabeater, Lobodon carcinophaga, and leopard seal, Hydrurga leptonyx). Apart from Weddell seals, inhabiting the fast-ice in Atka Bay, the other three (pack-ice) species however have to date never (Ross and leopard seal) or only very rarely (crabeater seals) been sighted in the Atka Bay region. The aim of the PASATA project is twofold: the large passive acoustic hydrophone array (hereafter referred to as large array) aims to localize calling pack-ice pinniped species to obtain information on their location and hence the ice habitat they occupy. This large array consists of four autonomous passive acoustic recorders with a hydrophone sensor deployed through a drilled hole in the sea ice. The PASATA recordings are time-stamped and can therefore be coupled to the PALAOA recordings so that the hydrophone array spans the bay almost entirely from east to west. The second, smaller hydrophone array (hereafter referred to as small array), also consists of four autonomous passive acoustic recorders with hydrophone sensors deployed through drilled holes in the sea ice. The smaller array was deployed within a Weddell seal breeding colony, located further south in the bay, just off the ice shelf. Male Weddell seals are thought to defend underwater territories around or near tide cracks and breathing holes used by females. Vocal activity increases strongly during the breeding season and vocalizations are thought to be used underwater by males for the purpose of territorial defense and advertisement. With the smaller hydrophone array we aim to investigate underwater behaviour of vocalizing male and female Weddell seals to provide further information on underwater movement patterns in relation to the location of tide cracks and breathing holes. As a pilot project, one on-ice and three underwater camera systems have been deployed near breathing holes to obtain additional visual information on Weddell seal behavioural activity. Upon each visit in the breeding colony, a census of colony composition on the ice (number of animals, sex, presence of dependent pups, presence and severity of injuries-indicative of competition intensity) as well as GPS readings of breathing holes and positions of hauled out Weddell seals are taken.

(Table 2) AMS radiocarbon dates from sediment cores obtained during James Clark Ross cruise JR142, Kvitøya Trough

High-resolution geophysical and sediment core data are used to investigate the pattern and dynamics of former ice flow in Kvitøya Trough, northwestern Barents Sea. A new swath-bathymetric dataset identifies three types of submarine landform in the study area (streamlined landforms, meltwater channels and cavities, iceberg scours). Subglacially produced streamlined landforms provide a record of ice flow through Kvitøya Trough during the last glaciation. Flow directions are inferred from the orientations of streamlined landforms (drumlins, crag-and-tail features). Ice flowed northward for at least 135 km from an ice divide at the southern end of Kvitøya Trough. A large channel-cavity system incised into bedrock in the southern trough indicates that subglacial meltwater was present at the former ice-sheet base. Modest landform elongation ratios and a lack of mega-scale glacial lineations suggest that, although ice in Kvitøya Trough was melting at the bed and flowed faster than the likely thin and cold-based ice on adjacent banks, a major ice stream probably did not occupy the trough. Retreat was relatively rapid after 14-13.5 14C kyr B.P. and probably progressed via ice sheet-bed decoupling in response to rising sea level. There is little evidence for still stands during ice retreat or of ice-proximal deglacial sediments. Relict iceberg scours in present-day water depths of more than 350 m in the northern trough indicate that calving was an important mass loss mechanism during retreat.

Description and composition iron-manganese concretions from the Pacific

One the most interesting features of ocean sedimentation is the manganese formations on the surface of the ocean floor in some areas. These are especially widespread in the Pacific Ocean as concretions, grains, and crusts on rock fragments and bedrock outcrops. Iron-manganese concretions are the most abundant as they completely cover about 10% of the bottom of the Pacific Ocean where there are ore concentrations. The concretions occupy from 20-50% of the bottom and up to 80-90% on separate submarine rises. Such concretions are found in different types of bottom deposits, from abyssal red clays to terrigenous muds, but they occur most widely in red clays and quite often in carbonate muds. Their shape and their dimensions are very diverse and change from place to place, from station to station, varying from 0.5-20 cm. They may be oval, globular, reniform, or slaggy and often they are fiat or isometric concretions of an indefinite shape. The concretions generally have nuclei of pumice, basalt fragments, clayey and tuffaceous material, sharks' teeth, whale ossicles, and fossil sponges. Most concretions have concentric layers, combined with dendritic ramifications of iron and manganese oxides.

Seawater carbonate chemistry and hatch rates of Antarctic krill

Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators-whales, seals and penguins. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700-1,000 m, where the carbon dioxide partial pressure (pCO2) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO2, and present a circumpolar risk map of krill hatching success under projected pCO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO2 emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem.