ALBERT

Description: A multiproxy study of palaeoceanographic and climatic changes in northernmost Baffin Bay shows that major environmental changes have occurred since the deglaciation of the area at about 12 500 cal. yr BP. The interpretation is based on sedimentology, benthic and planktonic foraminifera and their isotopic composition, as well as diatom assemblages in the sedimentary records at two core sites, one located in the deeper central part of northernmost Baffin Bay and one in a separate trough closer to the Greenland coast. A revised chronology for the two records is established on the basis of 15 previously published AMS 14C age determinations. A basal diamicton is overlain by laminated, fossil-free sediments. Our data from the early part of the fossiliferous record (12 300–11 300 cal. yr BP), which is also initially laminated, indicate extensive seasonal sea-ice cover and brine release. There is indication of a cooling event between 11 300 and 10 900 cal. yr BP, and maximum Atlantic Water influence occurred between 10 900 and 8200 cal. yr BP (no sediment recovery between 8200 and 7300 cal. yr BP). A gradual, but fluctuating, increase in sea-ice cover is seen after 7300 cal. yr BP. Sea-ice diatoms were particularly abundant in the central part of northernmost Baffin Bay, presumably due to the inflow of Polar waters from the Arctic Ocean, and less sea ice occurred at the near-coastal site, which was under continuous influence of the West Greenland Current. Our data from the deep, central part show a fluctuating degree of upwelling after c. 7300 cal. yr BP, culminating between 4000 and 3050 cal. yr BP. There was a gradual increase in the influence of cold bottom waters from the Arctic Ocean after about 3050 cal. yr BP, when agglutinated foraminifera became abundant. A superimposed short-term change in the sea-surface proxies is correlated with the Little Ice Age cooling.

Description: The diet composition of Emperor Penguin Aptenodytes forsteri chicks was examined at Auster and Taylor Glacier colonies, near Australia's Mawson station, Antarctica, between hatching in mid-winter and fledging in mid-summer by “water-offloading” adults. Chicks at both colonies were fed a similar suite of prey species. Crustaceans occurred in 82% of stomach samples at Auster and 87% of stomachs at Taylor Glacier and were heavily digested: their contribution to food mass could not be quantified. Fish, primarily bentho-pelagic species, accounted for 52% by number and 55% by mass of chick diet at Auster, and squid formed the remainder. At Taylor Glacier the corresponding values were 27% by number and 31% by mass of fish and 73% by number and 69% by mass of squid. Of the 33 species or taxa identified, the fish Trematomus eulepidotus and the squid Psychroteuthis glacialis and Allu-roteuthis antarcticus accounted for 64% and 74% of the diets by mass at Auster and Taylor Glacier, respectively. The sizes of fish varied temporally but not in a linear manner from winter to summer. Adult penguins captured fish ranging in length from 60 mm (Pfeura-gramma antarcticum) to 250 mm (T. eulepidotus) and squid (P. glacialis) from 19 to 280 mm in mantle length. The length-frequency distribution of P. glacialis showed seasonal variation, with the size of squid increasing from winter to summer. The energy density of chick diet mix increased significantly prior to “fledging”.

Description: The Denmark Strait Overflow (DSO) today compensates for the northward flowing Norwegian and Irminger branches of the North Atlantic Current that drive the Nordic heat pump. During the Last Glacial Maximum (LGM), ice sheets constricted the Denmark Strait aperture in addition to ice eustatic/isostatic effects which reduced its depth (today ∼630 m) by ∼130 m. These factors, combined with a reduced north-south density gradient of the water-masses, are expected to have restricted or even reversed the LGM DSO intensity. To better constrain these boundary conditions, we present a first reconstruction of the glacial DSO, using four new and four published epibenthic and planktic stable-isotope records from sites to the north and south of the Denmark Strait. The spatial and temporal distribution of epibenthic δ18O and δ13C maxima reveals a north-south density gradient at intermediate water depths from σ0∼28.7 to 28.4/28.1 and suggests that dense and highly ventilated water was convected in the Nordic Seas during the LGM. However, extremely high epibenthic δ13C values on top of the Mid-Atlantic Ridge document a further convection cell of Glacial North Atlantic Intermediate Water to the south of Iceland, which, however, was marked by much lower density (σ0∼28.1) The north-south gradient of water density possibly implied that the glacial DSO was directed to the south like today and fed Glacial North Atlantic Deep Water that has underthrusted the Glacial North Atlantic Intermediate Water in the Irminger Basin.

Description: Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmol S cm−3 d−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH2O groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23–18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments.

Description: The late stage of the North East Atlantic (NEA) spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi), particulate inorganic carbon (PIC) or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively), as well as transparent exopolymer particles (TEP). Results were compared with other studies undertaken in this area since the JGOFS NABE program. Characteristics of the spring bloom generally agreed well with the accepted scenario for the development of the autotrophic community. The NEA seasonal diatom bloom was in the late stages when we sampled the area and diatoms were constrained to the northern part of our transect, over the Icelandic Basin (IB) and Icelandic Shelf (IS). Coccolithophores dominated the phytoplankton community, with a large distribution over the Rockall-Hatton Plateau (RHP) and IB. The Porcupine Abyssal Plain (PAP) region at the southern end of our transect was the region with the lowest biomass, as demonstrated by very low Chla concentrations and a community dominated by picophytoplankton. Early depletion of dissolved silicic acid (DSi) and increased stratification of the surface layer most likely triggered the end of the diatom bloom, leading to coccolithophore dominance. The chronic Si deficiency observed in the NEA could be linked to moderate Fe limitation, which increases the efficiency of the Si pump. TEP closely mirrored the distribution of both biogenic silica at depth and prymnesiophytes in the surface layer suggesting the sedimentation of the diatom bloom in the form of aggregates, but the relative contribution of diatoms and coccolithophores to carbon export in this area still needs to be resolved.

Description: Quantitation of nucleic acids is a fundamental tool in molecular biology that requires accuracy, reliability, and the use of increasingly smaller sample volumes. This unit describes the traditional absorbance measurement at 260 nm and three more sensitive fluorescence techniques, as well as three microvolume methods that use fiber optic technology in specialized cells or instrumentation. These procedures allow quantitation of DNA solutions ranging from 1 pg/µl to 50 mg/ml.

Description: In contrast to continuum systems where localization or shear banding arises through a bifurcation in a predefined system of differential equations, shear bands emerge in numerical simulations of deforming granular systems with no prescribed mathematical relations other than simple contact forces between particles. Shear bands emerge from the self‐organization of large numbers of particles with long‐range geometrical interactions playing a dominant role; both translation and rotation of particles are important. Granular media therefore deform more like materials with non‐local constitutive relations than materials where only first‐order interactions are relevant. In this paper we adopt a thermo‐mechanical approach and explore the fluxes of energy in the evolving granular system (that has cohesion as well as friction between the particles) as it is loaded through the unstable localization regime, and track the evolution of energy dissipation. As in continua, the sign of the second‐order work defines the emergence of instability in the system. Initially, these instabilities decay into stable configurations of particles but with continued loading, force chains collapse locally to generate geometrically necessary fractures. These zones then propagate to generate localization zones. When these fractures form a continuous network, the system is at the percolation thresh‐hold for broken bonds. However, long before this stage, the second‐order work fluctuates in bursts weakly correlated with bursts in kinetic energy as damage accumulates. This behaviour suggests that any continuum constitutive description of granular media must be (i) non‐local in an anisotropic manner, (ii) micro‐polar, and (iii) involve damage evolution.

Description: We examined the physiological responses of steady-state iron (Fe)-replete and Fe-limited cultures of the biogeochemically critical marine unicellular diazotrophic cyanobacterium Crocosphaera at glacial (19 Pa; 190 ppm), current (39 Pa; 380 ppm), and projected year 2100 (76 Pa; 750 ppm) CO2 levels. Rates of N2 and CO2 fixation and growth increased in step with increasing partial pressure of CO2 (pCO2), but only under Fe-replete conditions. N2 and carbon fixation rates at 75 Pa CO2 were 1.4-1.8-fold and 1.2-2.0-fold higher, respectively, relative to those at present day and glacial pCO2 levels. In Fe-replete cultures, cellular Fe and molybdenum quotas varied threefold and were linearly related to N2 fixation rates and to external pCO2. However, N2 fixation and trace metal quotas were decoupled from pCO2 in Fe-limited Crocosphaera. Higher CO2 and Fe concentrations both resulted in increased cellular pigment contents and affected photosynthesis vs. irradiance parameters. If these results also apply to natural Crocosphaera populations, anthropogenic CO2 enrichment could substantially increase global oceanic N2 and CO2 fixation, but this effect may be tempered by Fe availability. Possible biogeochemical consequences may include elevated inputs of new nitrogen to the ocean and increased potential for Fe and/or phosphorus limitation in the future high-CO2 ocean, and feedbacks to atmospheric pCO2 in both the near future and over glacial to interglacial timescales.

Description: Rapid chemical profiling of the antitumour active crude dichloromethane extract of the marine sponge, Dactylospongia sp. was undertaken. A combination of both offline (HPLC followed by NMR and MS) and on-line (on-flow and stop-flow HPLC-NMR) chemical profiling approaches was adopted to establish the exact nature of the major constituents present in the dichloromethane extract of this sponge. On-flow HPLC-NMR analysis was employed to initially identify components present in the dichloromethane extract, while stop-flow HPLC-NMR experiments were then conducted on the major component present, resulting in the partial identification of pentaprenylated p-quinol (5). Subsequent off-line RP semi-preparative HPLC isolation of 5 followed by detailed spectroscopic analysis using NMR and MS permitted the complete structure to be established. This included the first complete carbon NMR chemical shift assignment of 5 based on the heteronuclear 2-D NMR experiments, together with the first report of its antitumour activity. This study represents one of the few reports describing the application of HPLC-NMR to chemically profile secondary metabolites from a marine organism.

Description: This first quantitative study of the diet of Emperor penguins is based on 29 stomach contents collected with a water off-loading method in Adelie Land. The Emperor is largely ichthyophagous (65% by number and 95% by weight) and feeds extensively on small nototheniids (97% of the fish are 40–125 mm in overall length). These results and data on meal size and feeding frequency of the chick suggest that Emperors are off-shore foraging birds offering little competition for food with other sea-birds or mammals.

Description: The diet of King Penguins Aptenodytes patagonicus at Macquarie Island was studied between November 1984 and November 1985 based on stomach flushed samples (obtaining 93% of the total stomach content) from ten birds each month. The mean stomach content mass of the 118 samples was 923 0 g. Percentage by number, percentage by weight and dietary coefficient analysis all showed the main prey of the penguins to be myctophid lantern fish of the species Electrona carlsbergi and Krefftichthys anderssoni. Juvenile fish of both species were eaten from December to July, and adults in August and September. Cephalopods were relatively unimportant in contrast to previous indications. The amount of food brought ashore and the composition of the diet varied over the year, with K. anderssoni the dominant food in all but the winter months when E. carlsbergi replaced it as the principal food item.

Description: In the past decade, a major trawl fishery for the squid Loligo gahi has developed in the vicinity of Beauchêne Island, an internationally important breeding site for the Black-browed Albatross Diomedea melanophris. The breeding season diet of this albatross in the Falklands and its use of discards generated by the Loligo fishery were investigated. Albatross chicks are fed extensively on commercially exploited species of squid and fish including Loligo gahi and southern blue whiting Micromesistius australis. The quantity of waste generated by the Loligo fishery amounts to c. 5% of the reported catch and just over 50% of this waste, mainly Loligo and nototheniid fish, is scavenged by adult Black-browed Albatrosses. The total quantity scavenged during the chick rearing period amounts to 1000–2000 tonnes per year. This is equivalent to 10–15% of the total food requirement of the breeding Black-browed Albatross population on Beauchene Island during the period when the fishery is operating. Although the Loligo fishery currently provides a significant quantity of food to these albatrosses, its net effect may be detrimental to them, as it is a much greater predator of Loligo stocks than the albatrosses are estimated to have been prior to the fishery's development.

Description: The genetic paradigm of cancer, focused largely on sequential molecular aberrations and associated biological impact in the neoplastic cell compartment of malignant tumors, has dominated our view of cancer pathogenesis. For the most part, this conceptualization has overlooked the dynamic and complex contributions of the surrounding microenvironment comprised of non-tumor cells (stroma) that may resist, react to, and/or foster tumor development. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease in which a prominent tumor stroma compartment is a defining characteristic. Indeed, the bulk of PDAC tumor volume consists of non-neoplastic fibroblastic, vascular, and inflammatory cells surrounded by immense quantities of extracellular matrix, far exceeding that found in most other tumor types. Remarkably, little is known about the composition and physiology of the PDAC tumor microenvironment, in particular, the role of stroma in tumor initiation and progression. This review attempts to define key challenges, opportunities and state-of-knowledge relating to the PDAC microenvironment research with an emphasis on how inflammatory processes and key cancer pathways may shape the ontogeny of the tumor stroma. Such knowledge may be used to understand the evolution and biology of this lethal cancer and may convert these insights into new points of therapeutic intervention.

Description: Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10-µm-thick microscopic cryosections of methanotrophic microbial mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di- and tetraether core lipids, together with their intact diglycoside (gentiobiosyl-) derivatives, were simultaneously identified by exact mass determination. Utilizing the imaging capability of ToF-SIMS, the spatial distributions of these biomarkers were mapped at a lateral resolution of 〈 5 µm in 500 × 500 µm2 areas on the mat sections. Using inline image cluster projectiles in the burst alignment mode, it was possible to reach a lateral resolution of 1 µm on an area of 233 × 233 µm, thus approaching the typical size of microbial cells. The mappings showed different ‘provenances’ within the sections that are distinguished by individual lipid fingerprints, namely (A) the diethers archaeol and hydroxyarchaeol co-occurring with glycerol dialkyl glycerol tetraethers (GDGT), (B) hydroxyarchaeol and dihydroxyarchaeol, and (C) GDGT and gentiobiosyl-GDGT. Because ToF-SIMS is a virtually nondestructive technique affecting only the outermost layers of the sample surface (typically 10–100 nm), it was possible to further examine the studied areas using conventional microscopy, and associate the individual lipid patterns with specific morphological traits. This showed that provenance (B) was frequently associated with irregular, methane-derived CaCO3 crystallites, whereas provenance (C) revealed a population of fluorescent, filamentous microorganisms showing the morphology of known methanotrophic ANME-1 archaea. The direct coupling of imaging mass spectrometry with microscopic techniques reveals interesting perspectives for the in-situ study of lipids in geobiology, microbial ecology, and organic geochemistry. After further developing protocols for handling different kinds of environmental samples, ToF-SIMS could be used as a tool to attack many challenging problems in these fields, such as the attribution of biological source(s) to particular biomarkers in question, or the high-resolution tracking of biogeochemical processes in modern and ancient natural environments.

Description: A major role in regulation of global methane fluxes has been attributed to the process of anaerobic oxidation of methane (AOM), which is performed by consortia of methanotrophic archaea and sulfate reducing bacteria. An important question remains how these energy limited, slow growing Microorganisms with generation times of 3–7 months respond to rapid natural variations in methane fluxes at cold seeps. We used an experimental flow-through column system filled with cold seep sediments naturally enriched in methanotrophic communities, to test their responses to short-term variations in methane and sulfate fluxes. At stable methane and sulfate concentrations of ∼2 mM and 28 mM, respectively, we measured constant rates of AOM and sulfate reduction (SR) for up to 160 days of incubation. When percolated with methane-free medium, the anaerobic methanotrophs ceased to produce sulfide. After a starvation phase of 40 days, the addition of methane restored former AOM and SR rates immediately. At methane concentrations between 0–2.3 mM we measured a linear correlation between methane availability, AOM and SR. At constant fluid flow velocities of 30 m yr−1, ca. 50% of the methane was consumed by the anaerobic methanotrophic (ANME) population at all concentrations tested. Reducing the sulfate concentration from 28 to 1 mM, a decrease in AOM and SR by 50% was observed, and 45% of the methane was consumed. Hence, the marine anaerobic methanotrophs(ANME) are capable of oxidizing substantial amounts of methane over a wide and variable range of fluxes of the reaction educts.

Description: The achievable accuracy of bathymetric mapping in the deep ocean using robotic systems is most often limited by the available guidance or navigation information used to combine the measured sonar ranges during the map making process. This paper presents an algorithm designed to mitigate the affects of poor ground referenced navigation by applying the principles of map registration and pose filtering commonly used in simultaneous localization and mapping (SLAM) algorithms. The goal of the algorithm is to produce a self-consistent point cloud representation of the bottom terrain with errors that are on a scale similar to the sonar range resolution rather than any direct positioning measurement. The presented algorithm operates causally and utilizes sensor data that are common to instrumented underwater robotic vehicles used for mapping and scientific explorations. Real world results are shown for data taken on several expeditions with the JASON remotely operated vehicle (ROV). Comparisons are made between more standard mapping approaches and the proposed method is shown to significantly improve the map quality and reveal scene information that would have otherwise been obscured due to poor direct navigation information.

Description: Chemical investigation of the fungus Trichoderma sp., isolated from the Caribbean sponge Agelas dispar led to four novel sorbicillinoid polyketide derivatives (1–4) with an unprecedented tricyclic ring system. The structures of all compounds, including the absolute configuration, were determined by interpretation of their spectroscopic data (1D and 2D NMR, CD, MS, UV and IR), and molecular modeling calculations.

Description: Sections of the lateral line organ, primary and secondary blood vessels and skin from the Atlantic cod Gadus morhua, Linnaeus 1758, were examined by light and transmission electron microscopy (TEM). The lateral line organ showed a structural analogy to the semicircular canals of the mammalian inner ear. A pericanalicular sinus (PCS), a canal of very loose connective tissue, surrounded the lateral line canal (LLC), separated by a multilayered epithelial wall. Located dorsal and ventral to the lateral line organ secondary vessels of capillary dimensions were found in association with the PCS. TEM of the wall of these dorso-ventral vessels showed single tight junction contacts between the endothelial cells, allowing paracellular fluid exchange between the secondary vascular system and the PCS, an indication supported by horseradish peroxidase (HRP) tracer experiments, which showed reaction products in the PCS within 2 h after injecting HRP into the systemic circulation. The multilayered epithelial wall of the LLC showed multiple tight junctions between cells, making this boundary permeable only through transcellular transport.

Description: Control of lacustrine phytoplankton biomass by phosphorus is one of the oldest and most stable paradigms in modern limnology. Even so, evidence from bioassays conducted by multiple investigators at numerous sites over the last three decades shows that N is at least as likely as P to be limiting to phytoplankton growth. A number of important flaws in the evidence supporting the phosphorus paradigm have contributed to an unrealistic degree of focus on phosphorus as a controlling element. These include insufficient skeptism in interpretation of: 1) the phosphorus: chlorophyll correlation in lakes, 2) the results of whole-lake fertilization experiments, and 3) stoichiometric arguments based on total N:total P ratios for inland waters. A new paradigm based on parity between N and P control of phytoplankton biomass in lakes seems more viable than the P paradigm. The new paradigm renews interest in the degree to which plankton communities are molded in composition by small differences in relative availability of N and P, the mechanisms that lead to a high frequency of N limitation in oligotrophic lakes, and the failure of aquatic N-fixers to compensate significantly for N deficiency under most conditions. A new N/P paradigm still must acknowledge that suppression of P loading often will be the most effective means of reducing phytoplankton biomass in eutrophic lakes, even if N is initially limiting.

Description: Blennolides A–G (2–8), seven unusual chromanones, were isolated together with secalonic acid B (1) from Blennoria sp., an endophytic fungus from Carpobrotus edulis. This is the first reported isolation of the blennolides 2 and 3 (hemisecalonic acids B and E), the existence of which as the monomeric units of the dimeric secalonic acids had long been postulated. A compound of the proposed structure 4 (β-diversonolic ester) will need to be revised, as its reported data do not fit those of the established structure of blennolide C (4). Other monomers, the blennolides D–F (5–7) seem to be derived from blennolides A (2) and B (3) by rearrangement of the hydroaromatic ring. The heterodimer 8, composed of the monomeric blennolide A (2) and the rearranged 11-dehydroxy derivative of blennolide E (6), extends the ergochrome family with an ergoxanthin type of skeleton. The structures of the new compounds were elucidated by detailed spectroscopic analysis and further confirmed by an X-ray diffraction study of a single crystal of 2. The absolute configurations were determined by TDDFT calculations of CD spectra, including the solid-state CD/TDDFT approach. Preliminary studies showed strong antifungal and antibacterial activities of these compounds against Microbotryum violaceum and Bacillus megaterium, respectively. They were also active against the alga Chlorella fusca and the bacterium Escherichia coli.

Description: This study examined stocking with three early life stages of brown trout, Salmo trutta L., in the context of rehabilitating a native lineage. Experimental sections in five streams were stocked successively with three stages (I: unfed fry at the end of the reabsorption phase, II: fed fry measuring 2–3 cm and III: fed fry measuring 4–5 cm) derived from a hatchery stock bred from wild spawners. The three stages were distinguished by single or multiple fluoromarking of the otoliths with alizarin redS. The index of relative stocking efficiency was greater for stage II than for stage I in all sections and equivalent or greater than that for stage III. Stage II achieved significantly larger mean length and weight in autumn than stage III stockings.

Description: Sections PDFPDF Tools Share Abstract Many trophically transmitted parasites have complex life cycles: they pass through at least one intermediate host before reproducing in their final host. Despite their economic and theoretical importance, the evolution of such cycles has rarely been investigated. Here, combining a novel modeling approach with experimental data, we show for the first time that an optimal transfer time between hosts exists for a “model parasite,” the tapeworm Schistocephalus solidus , from its first (copepod) to its second (fish) intermediate host. When transferring between hosts around this time, (1) parasite performance in the second intermediate host, (2) reproductive success in the final host, and (3) fitness in the next generation is maximized. At that time, the infected copepod's behavior changes from predation suppression to predation enhancement. The optimal time for switching manipulation results from a trade‐off between increasing establishment probability in the next host and reducing mortality in the present host. Our results show that these manipulated behavioral changes are adaptive for S. solidus , rather than an artifact, as they maximize parasite fitness.

Description: Large volcanic edifices are often shaped by the coalescence of adjacent volcanoes as well as intrusive rift zones and gravitational spreading. To better understand the structure of such volcanoes we designed analogue experiments simulating gravitational spreading of an edifice made by overlapping cones of different age, and examined the formation of rift zones. The results allow distinction of two main rift geometries. (i) Spreading edifices of similar age that partly overlap, tend to develop a rift zone approximately perpendicular to the boundary of both volcanoes. Such a rift zone causes two volcanoes to grow together and form an elongated topographic ridge. (ii) Partly overlapping volcanoes of different age are spreading at different rates and thus form a rift zone parallel to the boundary of both volcanoes. Such a rift zone causes two volcanoes to structurally separate. The results are widely applicable for large volcanoes subject to rifting and flank spreading, which we demonstrate for Réunion Island and for southern Hawaii.

Description: The relative importance of potential source and sink terms for bromoform (CHBr3) in the tropical Atlantic Ocean is investigated with a coupled physical-biogeochemical water column model. Bromoform production is either assumed to be linked to primary production or to phytoplankton losses; bromoform decay is treated as light dependent (photolysis), and in addition either vertically uniform, proportional to remineralisation or to nitrification. All experiments lead to the observed subsurface maximum of bromoform, corresponding to the subsurface phytoplankton biomass maximum. In the surface mixed layer, the concentration is set by entrainment from below, photolysis in the upper few meters and the outgassing to the atmosphere. The assumed bromoform production mechanism has only minor effects on the solution, but the various loss terms lead to significantly different bromoform concentrations below 200 m depth. The best agreement with observations is obtained when the bromoform decay is coupled to nitrification (parameterised by an inverse proportionality to the light field). Our model results reveal a pronounced seasonal cycle of bromoform outgassing, with a minimum in summer and a maximum in early winter, when the deepening surface mixed layer reaches down into the bromoform production layer

Description: Polymorphicgenesofthemajorhistocompatibilitycomplex(MHC)areregardedasessential genes for individual fitness under conditions of natural and sexual selection. To test this hypothesis, we investigated the ultimate individual fitness trait — that of reproductive success. We used three-spined sticklebacks (Gasterosteus aculeatus) in seminatural enclosures, located in natural breeding areas where the experimental fish had been caught. During their reproductive period, fish were exposed continuously to their natural sympatric parasites. By genotyping almost 4000 eggs with nine microsatellites, we determined parenthood and inferred female mating decision. We found that with reference to their own MHC profile, female sticklebacks preferred to mate with males sharing an intermediate MHC diversity. In addition, males with a specific MHC haplotype were bigger and better at fighting a common parasite (Gyrodactylus sp.). This translated directly into Darwinian fitness since fish harbouring this specific MHC haplotype were more likely to be chosen and had a higher reproductive output. We conclude that females also based their mating decision on a specific MHChaplotype conferring resistance against a common parasite. This identifies and supports ‘good genes’. We argue that such an interaction between host and parasite driving assortative mating is not only a prerequisite for negative frequency-dependent selection — a potential mechanism to explain the maintenance of MHC polymorphism, but also potentially speciation.

Description: The biogeochemistry of the river-sea interface was studied in the Kem' River (the largest river flowing to the White Sea from Karelian coast) estuary and adjacent area of the White Sea onboard the RV "Ekolog" in summer 2001, 2002 and 2003. The study area can be divided into 3 zones: I - the estuary itself, with water depth from 1 to 5m and low salinity in the surface layer (salinity is lower than 0.2psu in the Kem' River and varies from 15 to 20psu in outer part of this zone); II - the intermediate zone with depths from 5 to 10m and salinity at the surface from 16 to 22psu; III - the marine zone with depths from 10 to 29 m and salinity 21-24.5psu. Highest concentrations of the suspended particulate matter (SPM) were registered in the Kem' mouth (5-7mg/l). They sharply decreased to values 〈1mg/l towards the sea. At beginning of July 2001, particulate organic carbon (POC) concentration in the river mouth was 404µg/l and POC content in total SPM was 5.64%. In the marine part of the studied area the POC concentration varied from 132 to 274µg/l and the POC contents in suspended matter increased to 19-52.6%. These studies show, that the majority of riverborne suspended matter in the Kem' estuary deposits near the river mouth within the 20psu isohaline, where sedimentation of the suspended matter takes place. The role of fresh-water phytoplankton species decreases and the role of marine species increases from the river to sea and the percentage of green algae decreases and the role of diatoms increases. The organic carbon (Corg) to nitrogen (N) ratio (Corg/N) in both suspended matter and bottom sediments decreases from the river to the marine part of the mixing zone (from 8.5 to 6.1 in the suspended matter and from 14.6 to 7.5 in the bottom sediments), demonstrating that content of terrestrial-derived organic matter decreases and content of marine organic matter increases from the river mouth to the sea. The Kem' estuary exhibits a similar character of biogeochemial processes as in the large Arctic estuaries, but the scale of these processes (amount of river input of SPM, POC, area of estuaries) is different.

Description: The interaction between iron availability and the phytoplankton elemental composition was investigated during the in situ iron fertilization experiment EIFEX and in laboratory experiments with the Southern Ocean diatom species Fragilariopsis kerguelensis and Chaetoceros dichaeta. Contrary to other in situ iron fertilization experiments we observed an increase in the BSi:POC, BSi:PON, and BSi:POP ratios within the iron fertilized patch during EIFEX. This is possibly caused by a relatively stronger increase in diatom abundance compared to other phytoplankton groups and does not necessarily represent the amount of silicification of single diatom cells. In laboratory experiments with F. kerguelensis and C. dichaeta no changes in the POC:PON, PON:POP, and POC:POP ratios were found with changing iron availability in both species. BSi:POC, BSi:PON, and BSi:POP ratios were significantly lower in the high iron treatments compared to the controls. In F. kerguelensis this was caused by a decrease in cellular BSi concentrations and therefore possibly less silicification. In C. dichaeta no change in cellular BSi concentration was found. Here lower BSi:POC, BSi:PON, and BSi:POP ratios were caused by an increase in cellular C, N, and P under high iron conditions. These results indicate that iron limitation does not always increase silicification in diatoms and that changes in the BSi:POC, BSi:PON, and BSi:POP ratios under iron fertilization in the field are caused by a variety of different mechanisms. Our results therefore imply that simple cause-and-effect relationships are not always applicable for modeling of elemental ratios.

Description: The subtropical Indian Ocean along 32° S was for the first time simultaneously sampled in 2002 for inorganic carbon and transient tracers. The vertical distribution and inventory of anthropogenic carbon (CANT) from five different methods: four data-base methods (ΔC*, TrOCA, TTD and IPSL) and a simulation from the OCCAM model are compared and discussed along with the observed CFC-12 and CCl4 distributions. In the surface layer, where carbon-based methods are uncertain, TTD and OCCAM yield the same result (7±0.2 molC m−2), helping to specify the surface CANT inventory. Below the mixed-layer, the comparison suggests that CANT penetrates deeper and more uniformly into the Antarctic Intermediate Water layer limit than estimated from the much utilized ΔC* method. Significant CFC-12 and CCl4 values are detected in bottom waters, associated with Antarctic Bottom Water. In this layer, except for ΔC* and OCCAM, the other methods detect significant CANT values. Consequently, the lowest inventory is calculated using the ΔC* method (24±2 molC m−2) or OCCAM (24.4±2.8 molC m−2) while TrOCA, TTD, and IPSL lead to higher inventories (28.1±2.2, 28.9±2.3 and 30.8±2.5 molC m−2 respectively). Overall and despite the uncertainties each method is evaluated using its relationship with tracers and the knowledge about water masses in the subtropical Indian Ocean. Along 32° S our best estimate for the mean CANT specific inventory is 28±2 molC m−2. Comparison exercises for data-based CANT methods along with time-series or repeat sections analysis should help to identify strengths and caveats in the CANT methods and to better constrain model simulations.

Description: Several trench-outer rise settings in subduction zones worldwide are characterized by a high degree of alteration, fracturing and hydration. These processes are induced by bending-related faulting in the upper part of the oceanic plate prior to its subduction. Mapping of P- and S-wave velocity structures in this complex tectonic setting provides crucial information for understanding the evolution of the incoming oceanic lithosphere, and serves as a baseline for comparison with seismic measurements elsewhere. Active source seismic investigations at the outer rise off Southern Central Chile (∼43°S) were carried out in order to study the seismic structure of the oceanic Nazca Plate. Seismic wide-angle data were used to derive 2-D velocity models of two seismic profiles located seaward of the trench axis on 14.5 Ma old crust; P01a approximately parallel to the direction of spreading and P03 approximately parallel to the spreading ridge and trench axes. We determined P- and S-velocity models using 2-D traveltime tomography. We found that the Poisson's ratio in the upper crust (layer 2) ranges between ∼0.33 at the top of the crust to ∼0.28 at the layer 2/3 interface, while in the lowermost crust and uppermost mantle it reaches values of ∼0.26 and ∼0.29, respectively. These features can be explained by an oceanic crust significantly weathered, altered and fractured. Relative high Poisson's ratios in the uppermost mantle may be likely related to partially hydrated mantle and hence serpentinization. Thus, the seismic structure of the oceanic lithosphere at the Southern Central Chile outer rise exhibits notable differences from the classic ophiolite seismic model (‘normal’ oceanic crust). These differences are primarily attributed to fracturing and hydration of the entire ocean crust, which are direct consequences of strong bending-related faulting at the outer rise. On the other hand, the comparison of the uppermost mantle P-wave velocities at the crossing point between the perpendicular profiles (∼90 km oceanward from the trench axis) reveals a low degree of Pn anisotropy (〈2 per cent).

Description: A number of field-campaigns in the tropics have been conducted in recent years with two different LIDAR systems at Paramaribo (5.8° N, 55.2° W), Suriname. The lidars detect particles in the atmosphere with high vertical and temporal resolution and are capable of detecting extremely thin cloud layers which frequently occur in the tropical tropopause layer (TTL). Radiosonde as well as operational ECMWF analysis showed that equatorial Kelvin waves propagated in the TTL and greatly modulated its temperature structure. We found a clear correlation between the temperature anomalies introduced by these waves and the occurrence of thin cirrus in the TTL. In particular we found that extremely thin ice clouds form regularly where cold anomalies shift the tropopause to high altitudes. These findings suggest an influence of Kelvin wave activity on the dehydration in the TTL and thus on the global stratospheric water vapour concentration.

Description: To date no study exists that directly addresses changes in dynamics of heterotrophic bacteria in surface waters in relation to partial pressure of CO2 (pCO2). Therefore, we studied the effect of changes in pCO2 on bacterial abundance and activities by using mesocosms with different pCO2 levels (~190, ~370, and ~700 ppmV, representing past, present-day, and future atmospheric pCO2, respectively). Abundance of total bacteria did not differ with increasing pCO2 throughout the whole study period, whereas bacterial protein production (BPP) was highest at highest pCO2. This effect was even more pronounced for cell-specific production rates, especially those of attached bacteria, which were up to 25 times higher than those of free bacteria. During the breakdown of the bloom, however, the abundance of both free and attached bacteria was significantly increased with pCO2. Differences in bacterial growth rate (µ) were smaller than those of BPP, but both µ and BPP of attached bacteria were elevated under high pCO2. Averages of total protease as well as α- and α -glucosidase activities were highest at elevated pCO2 levels, but a statistically significant dependence on pCO2 was only evident for protease activity. There is a measurable but indirect effect of changes in pCO2 on bacterial activities that are mainly linked to phytoplankton and presumably particle dynamics

Description: The early life-history of Chinese rock carp Procypris rabaudi was investigated during a 56-day rearing period: 318 artificially propagated P. rabaudi larvae were reared throughout metamorphosis in a small-scale recirculation system (345 L water volume, 10 × 18 L rearing tanks, 150 L storage and filter compartment with bioballs, 20–30 larvae L−1) at the Institute of Hydrobiology, Wuhan, Hubei Province, China. The newly hatched larvae had an initial total length of 8.93 ± 0.35 mm SD (n = 10) at 3 days post-hatch and reached an average total length of 33.29 mm (±1.88 mm SD, n = 10) 56 days after hatching. Length increment averaged 0.45 mm day−1, resulting in a mean growth of 24.4 mm within the 56-day period. High mortality rates of up to 92% derived from an introduced fungus infection and subsequent treatment stress with malachite green. Our results indicate that Chinese rock carp can be raised successfully from artificially fertilized eggs. We therefore assume this species to be a candidate for commercial aquaculture.

Description: Anaerobic methane-oxidizing microbial communities in sediments at cold methane seeps are important factors in controlling methane emission to the ocean and atmosphere. Here, we investigated the distribution and carbon isotopic signature of specific biomarkers derived from anaerobic methanotrophic archaea (ANME groups) and sulphate-reducing bacteria (SRB) responsible for the anaerobic oxidation of methane (AOM) at different cold seep provinces of Hydrate Ridge, Cascadia margin. The special focus was on their relation to in situ cell abundances and methane turnover. In general, maxima in biomarker abundances and minima in carbon isotope signatures correlated with maxima in AOM and sulphate reduction as well as with consortium biomass. We found ANME-2a/DSS aggregates associated with high abundances of sn-2,3-di-O-isoprenoidal glycerol ethers (archaeol, sn-2-hydroxyarchaeol) and specific bacterial fatty acids (C16:1ω5c, cyC17:0ω5,6) as well as with high methane fluxes (Beggiatoa site). The low to medium flux site (Calyptogena field) was dominated by ANME-2c/DSS aggregates and contained less of both compound classes but more of AOM-related glycerol dialkyl glycerol tetraethers (GDGTs). ANME-1 archaea dominated deeper sediment horizons at the Calyptogena field where sn-1,2-di-O-alkyl glycerol ethers (DAGEs), archaeol, methyl-branched fatty acids (ai-C15:0, i-C16:0, ai-C17:0), and diagnostic GDGTs were prevailing. AOM-specific bacterial and archaeal biomarkers in these sediment strata generally revealed very similar δ13C-values of around −100. In ANME-2-dominated sediment sections, archaeal biomarkers were even more 13C-depleted (down to −120), whereas bacterial biomarkers were found to be likewise 13C-depleted as in ANME-1-dominated sediment layers (δ13C: −100). The zero flux site (Acharax field), containing only a few numbers of ANME-2/DSS aggregates, however, provided no specific biomarker pattern. Deeper sediment sections (below 20 cm sediment depth) from Beggiatoa covered areas which included solid layers of methane gas hydrates contained ANME-2/DSS typical biomarkers showing subsurface peaks combined with negative shifts in carbon isotopic compositions. The maxima were detected just above the hydrate layers, indicating that methane stored in the hydrates may be available for the microbial community. The observed variations in biomarker abundances and 13C-depletions are indicative of multiple environmental and physiological factors selecting for different AOM consortia (ANME-2a/DSS, ANME-2c/DSS, ANME-1) along horizontal and vertical gradients of cold seep settings.

Description: Nutrient addition bioassay experiments were performed in the low-nutrient, low-chlorophyll oligotrophic subtropical North Atlantic Ocean to investigate the influence of nitrogen (N), phosphorus (P), and/or iron (Fe) on phytoplankton physiology and the limitation of primary productivity or picophytoplankton biomass. Additions of N alone resulted in 1.5-2 fold increases in primary productivity and chlorophyll after 48 h, with larger (~threefold) increases observed for the addition of P in combination with N (NP). Measurements of cellular chlorophyll contents permitted evaluation of the physiological response of the photosynthetic apparatus to N and P additions in three picophytoplankton groups. In both Prochlorococcus and the picoeukaryotes, cellular chlorophyll increased by similar amounts in N and NP treatments relative to all other treatments, suggesting that pigment synthesis was N limited. In contrast, the increase of cellular chlorophyll was greater in NP than in N treatments in Synechococcus, suggestive of NP co-limitation. Relative increases in cellular nucleic acid were also only observed in Synechococcus for NP treatments, indicating co-limitation of net nucleic acid synthesis. A lack of response to relief of nutrient stress for the efficiency of photosystem II photochemistry, Fv :Fm, suggests that the low nutrient supply to this region resulted in a condition of balanced nutrient limited growth, rather than starvation. N thus appears to be the proximal (i.e. direct physiological) limiting nutrient in the oligotrophic sub-tropical North Atlantic. In addition, some major picophytoplankton groups, as well as overall autotrophic community biomass, appears to be co-limited by N and P.

Description: Transmission of top-down control from fish to phytoplankton via crustacean mesozooplankton is a cornerstone of limnetic plankton ecology. Such trophic cascades are less frequently reported from the marine pelagic. In this article a case is made for consideration of scale issues and for the distinction between full (affecting entire trophic levels) and partial (affecting only some functional groups) trophic cascades. Partial cascades are more widespread while the full cascades are either ephemeral or depend on the suppression of compensatory growth of the predation-resistant size-fractions of phytoplankton. This suppression can only be achieved if there is a persistent coexistence between zooplankton feeding on different parts of the phytoplankton size spectrum. This condition is fulfilled in plankton communities where microphageous cladocerans (mainly Daphnia) and microphageous copepods coexist (many lake communities) or where krill and copepods coexist (high latitude marine communities). It is not fulfilled in many temperate and low-latitude marine communities where copepods effectively suppress filter-feeding appendicularians. Thus, the observed difference in the frequency of marine and limnetic pelagic cascades is considered real. Are all trophic cascades wet?

Description: The relation between the Agulhas Current retroflection location and the magnitude of Agulhas leakage, the transport of water from the Indian to the Atlantic Ocean, is investigated in a high-resolution numerical ocean model. Sudden eastward retreats of the Agulhas Current retroflection loop are linearly related to the shedding of Agulhas rings, where larger retreats generate larger rings. Using numerical Lagrangian floats a 37 year time series of the magnitude of Agulhas leakage in the model is constructed. The time series exhibits large amounts of variability, both on weekly and annual time scales. A linear relation is found between the magnitude of Agulhas leakage and the location of the Agulhas Current retroflection, both binned to three month averages. In the relation, a more westward location of the Agulhas Current retroflection corresponds to an increased transport from the Indian Ocean to the Atlantic Ocean. When this relation is used in a linear regression and applied to almost 20 years of altimetry data, it yields a best estimate of the mean magnitude of Agulhas leakage of 13.2 Sv. The early retroflection of 2000, when Agulhas leakage was probably halved, can be identified using the regression.

Description: It is widely accepted that climate change constrains biota. Yet, because of the lack of consistent multisite and multitaxon surveys, few studies have addressed general rules about how climate change impacts on structure and diversity of animal communities. Especially, the relative influence of nonclimatic anthropogenic disturbances on this impact is fairly unknown. Here, we present for the first time a meta-analysis assessing the effect of global warming on stream organisms. Fish communities of large rivers in France undergoing various anthropogenic pressures showed significant increase in proportions of warm-water species and of specific richness during the last 15–25 years. Conversely, the equitability decreased, indicating a gradual decrease of the number of dominant species. Finally, the total abundance increased, coupled with rejuvenation and changes in size-structure of the communities. Interestingly, most of these effects were not depressed by the strength of nonclimatic anthropogenic disturbances. Conversely, geographical location of communities and especially closeness of natural barriers to migration could influence their response to climate change. Indeed, increase in the proportion of southern species seemed hindered at sites located close to the southern limit of the European species’ geographical ranges. This work provides new evidence that climate change have deep impacts on communities which, by overtaking the effects of nonclimatic anthropogenic disturbances, could be more substantial than previously thought. Overall, our results stress the importance of considering climate change impacts in studies addressing community dynamics, even in disturbed sites.

Description: The nitrogen cycling of Lake Cadagno was investigated by using a combination of biogeochemical and molecular ecological techniques. In the upper oxic freshwater zone inorganic nitrogen concentrations were low (up to ∼3.4 μM nitrate at the base of the oxic zone), while in the lower anoxic zone there were high concentrations of ammonium (up to 40 μM). Between these zones, a narrow zone was characterized by no measurable inorganic nitrogen, but high microbial biomass (up to 4 × 107 cells ml−1). Incubation experiments with 15N-nitrite revealed nitrogen loss occurring in the chemocline through denitrification (∼3 nM N h−1). At the same depth, incubations experiments with 15N2- and 13CDIC-labelled bicarbonate, indicated substantial N2 fixation (31.7–42.1 pM h−1) and inorganic carbon assimilation (40–85 nM h−1). Catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and sequencing of 16S rRNA genes showed that the microbial community at the chemocline was dominated by the phototrophic green sulfur bacterium Chlorobium clathratiforme. Phylogenetic analyses of the nifH genes expressed as mRNA revealed a high diversity of N2 fixers, with the highest expression levels right at the chemocline. The majority of N2 fixers were related to Chlorobium tepidum/C. phaeobacteroides. By using Halogen In Situ Hybridization-Secondary Ion Mass Spectroscopy (HISH-SIMS), we could for the first time directly link Chlorobium to N2 fixation in the environment. Moreover, our results show that N2 fixation could partly compensate for the N loss and that both processes occur at the same locale at the same time as suggested for the ancient Ocean.

Description: The marine aragonite cycle has been included in the global biogeochemical model PISCES to study the role of aragonite in shallow water CaCO3 dissolution. Aragonite production is parameterized as a function of mesozooplankton biomass and aragonite saturation state of ambient waters. Observation-based estimates of marine carbonate production and dissolution are well reproduced by the model and about 60% of the combined CaCO3 water column dissolution from aragonite and calcite is simulated above 2000 m. In contrast, a calcite-only version yields a much smaller fraction. This suggests that the aragonite cycle should be included in models for a realistic representation of CaCO3 dissolution and alkalinity. For the SRES A2 CO2 scenario, production rates of aragonite are projected to notably decrease after 2050. By the end of this century, global aragonite production is reduced by 29% and total CaCO3 production by 19% relative to pre-industrial. Geographically, the effect from increasing atmospheric CO2, and the subsequent reduction in saturation state, is largest in the subpolar and polar areas where the modeled aragonite production is projected to decrease by 65% until 2100.

Description: At convergent margins, the structure of the subducting oceanic plate is one of the key factors controlling the morphology of the upper plate. We use high-resolution seafloor mapping and multichannel seismic reflection data along the accretionary Sumatra trench system to investigate the morphotectonic response of the upper plate to the subduction of lower plate fabric. Upper plate segmentation is reflected in varying modes of mass transfer. The deformation front in the southern Enggano segment is characterized by neotectonic formation of a broad and shallow fold-and-thrust belt consistent with the resumption of frontal sediment accretion in the wake of oceanic relief subduction. Conversely, surface erosion increasingly shapes the morphology of the lower slope and accretionary prism towards the north where significant oceanic relief is subducted. Subduction of the Investigator Fracture Zone and the fossil Wharton spreading centre in the Siberut segment exemplifies this. Such features also correlate with an irregularly trending deformation front suggesting active frontal erosion of the upper plate. Lower plate fabric extensively modulates upper plate morphology and the large-scale morphotectonic segmentation of the Sumatra trench system is linked to the subduction of reactivated fracture zones and aseismic ridges of the Wharton Basin. In general, increasing intensity of mass-wasting processes, from south to north, correlates with the extent of oversteepening of the lower slope (lower slope angle of 3.8 degrees in the south compared with 7.6 degrees in the north), probably in response to alternating phases of frontal accretion and sediment underthrusting. Accretionary mechanics thus pose a second-order factor in shaping upper plate morphology near the trench.

Description: Fully coupled climate carbon cycle models are sophisticated tools that are used to predict future climate change and its impact on the land and ocean carbon cycles. These models should be able to adequately represent natural variability, requiring model validation by observations. The present study focuses on the ocean carbon cycle component, in particular the spatial and temporal variability in net primary productivity (PP) and export production (EP) of particulate organic carbon (POC). Results from three coupled climate carbon cycle models (IPSL, MPIM, NCAR) are compared with observation-based estimates derived from satellite measurements of ocean colour and results from inverse modelling (data assimilation). Satellite observations of ocean colour have shown that temporal variability of PP on the global scale is largely dominated by the permanently stratified, low-latitude ocean (Behrenfeld et al., 2006) with stronger stratification (higher sea surface temperature; SST) being associated with negative PP anomalies. Results from all three coupled models confirm the role of the low-latitude, permanently stratified ocean for anomalies in globally integrated PP, but only one model (IPSL) also reproduces the inverse relationship between stratification (SST) and PP. An adequate representation of iron and macronutrient co-limitation of phytoplankton growth in the tropical ocean has shown to be the crucial mechanism determining the capability of the models to reproduce observed interactions between climate and PP.

Description: A set of experiments utilizing different implementations of the global ORCA-LIM model with horizontal resolutions of 2°, 0.5° and 0.25° is used to investigate tropical and extra-tropical influences on equatorial Pacific SST variability at interannual to decadal time scales. The model experiments use a bulk forcing methodology building on the global forcing data set for 1958 to 2000 developed by Large and Yeager (2004) that is based on a blend of atmospheric reanalysis data and satellite products. Whereas representation of the mean structure and transports of the (sub-) tropical Pacific current fields is much improved with the enhanced horizontal resolution, there is only little difference in the simulation of the interannual variability in the equatorial regime between the 0.5° and 0.25° model versions, with both solutions capturing the observed SST variability in the Niño3-region. The question of remotely forced oceanic contributions to the equatorial variability, in particular, the role of low-frequency changes in the transports of the Subtropical Cells (STCs), is addressed by a sequence of perturbation experiments using different combinations of fluxes. The solutions show the near-surface temperature variability to be governed by wind-driven changes in the Equatorial Undercurrent. The relative contributions of equatorial and off-equatorial atmospheric forcing differ between interannual and longer, (multi-) decadal timescales: for the latter there is a significant impact of changes in the equatorward transport of subtropical thermocline water associated with the lower branches of the STCs, related to variations in the off-equatorial trade winds. A conspicuous feature of the STC variability is that the equatorward transports in the interior and along the western boundary partially compensate each other at both decadal and interannual time scales, with the strongest transport extrema occurring during El Niño episodes. The behaviour is rationalized in terms of a wobbling in the poleward extents of the tropical gyres, which is manifested also in a meridional shifting of the bifurcation latitudes of the North and South Equatorial Current systems.

Description: While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment. These variables reflect a wide range of physical, chemical, and biological responses to climate. However, the efficacy of the different indicators is affected by regional response to climate change, characteristics of the catchment, and lake mixing regimes. Thus, particular indicators or combinations of indicators are more effective for different lake types and geographic regions. The extraction of climate signals can be further complicated by the influence of other environmental changes, such as eutrophication or acidification, and the equivalent reverse phenomena, in addition to other land-use influences. In many cases, however, confounding factors can be addressed through analytical tools such as detrending or filtering. Lakes are effective sentinels for climate change because they are sensitive to climate, respond rapidly to change, and integrate information about changes in the catchment.

Description: The distribution of egg masses of the freshwater snails Lymnaea stagnalis and Planorbarius corneus on the undersides of water lily leaves (e.g. Nuphar lutea) is related to the prevalence of the leaf-mining beetle Galerucella nymphaeae. When given the choice, Planorbarius significantly avoids leaves that were infested by the mining beetle. Conversely, Lymnaea did not discriminate against mined leaves. Intact Nuphar leaves block over 95% of incident ultraviolet radiation. Yet, ultraviolet transmission reaches almost 100% under beetle mining scars. These are several times wider than snail embryos. When exposed to natural sunlight, Lymnaea embryos proved to be resistant to ambient ultraviolet, while Planorbarius embryos were rapidly killed. Thus, one selective advantage of Planorbarius discrimination against mined leaves when depositing its eggs could be the avoidance of ultraviolet radiation passing through mining scars. Other mining-related modifications of the leaves, reduced area, decreased longevity, altered aufwuchs (i.e. biofilm and epibionts) are discussed but seem less relevant for the oviposition preference of Planorbarius. The discriminatory behaviour of this snail species was triggered by water-borne cues emitted by the damaged leaf, not by the eggs or larvae of the beetle. This study illustrates how environmental stress on a given species, ultraviolet radiation in this case, can be ecologically buffered (shading by Nuphar) or enhanced (reduction of Nuphar shading through beetle mining) by associated species. It highlights how the impact of a given stress depends on the identity of the target species as well as on the identity and role of other species in the community.

Description: The calcium isotopic composition of NIST SRM 915b and 1486 provided by the National Institute of Standards and Technology was analysed. The δ44/40Ca values of the two reference materials relative to NIST SRM 915a were: NIST SRM 915b =+0.72 ± 0.04‰ and NIST SRM 1486 =−1.01 ± 0.02‰. NIST SRM 1486 did not require any chemical separation prior to measurement. La composition isotopique du calcium de NIST SRM 915b et 1486, fournis par l'Institut National des Standards et de la Technologie (NIST), a été analysée. Les valeurs du δ44/40Ca obtenues sur ces deux matériaux de référence, relativement au NIST SRM 915a sont: NIST SRM 915b =+0.72 ± 0.04‰ et NIST SRM 1486 =−1.01 ± 0.02‰. Le NIST SRM 1486 n'a nécessité aucune séparation chimique avant analyse.

Description: The first three Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Campaigns at Eureka (80° N, 86° W) were during two extremes of Arctic winter variability: Stratospheric sudden warmings (SSWs) in 2004 and 2006 were among the strongest, most prolonged on record; 2005 was a record cold winter. New satellite measurements from ACE-Fourier Transform Spectrometer (ACE-FTS), Sounding of the Atmosphere using Broadband Emission Radiometry, and Aura Microwave Limb Sounder (MLS), with meteorological analyses and Eureka lidar and radiosonde temperatures, are used to detail the meteorology in these winters, to demonstrate its influence on transport and chemistry, and to provide a context for interpretation of campaign observations. During the 2004 and 2006 SSWs, the vortex broke down throughout the stratosphere, reformed quickly in the upper stratosphere, and remained weak in the middle and lower stratosphere. The stratopause reformed at very high altitude, above where it could be accurately represented in the meteorological analyses. The 2004 and 2006 Eureka campaigns were during the recovery from the SSWs, with the redeveloping vortex over Eureka. 2005 was the coldest winter on record in the lower stratosphere, but with an early final warming in mid-March. The vortex was over Eureka at the start of the 2005 campaign, but moved away as it broke up. Disparate temperature profile structure and vortex evolution resulted in much lower (higher) temperatures in the upper (lower) stratosphere in 2004 and 2006 than in 2005. Satellite temperatures agree well with Eureka radiosondes, and with lidar data up to 50–60 km. Consistent with a strong, cold upper stratospheric vortex and enhanced radiative cooling after the SSWs, MLS and ACE-FTS trace gas measurements show strongly enhanced descent in the upper stratospheric vortex during the 2004 and 2006 Eureka campaigns compared to that in 2005.

Description: Otolith increment width and larval fish data (length and weight) were used to develop an individual-based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over-determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age-dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.

Description: The accurate reconstruction of sea surface temperature (SST) history in climate-sensitive regions (e.g. tropical and polar oceans) became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major high latitude proxy carrier Neogloboquadrina pachyderma (sin.) highlight an urgent need to explore complementary SST proxies for these cool-water regions. Here we incorporate the genetic component into a calibration study of a new SST proxy for the high latitudes. We found that the calcium isotopic composition (δ44/40Ca) of calcite from genotyped net catches and core-top samples of the planktonic foraminifera Neogloboquadrina pachyderma (sin.) is related to temperature and unaffected by genetic variations. The temperature sensitivity has been found to be 0.17 (±0.02)‰ per 1°C, highlighting its potential for downcore applications in open marine cool-water environments. Our results further indicate that in extreme polar environments, below a critical threshold temperature of 2.0 (±0.5)°C associated with salinities below 33.0 (±0.5)‰, a prominent shift in biomineralization affects the δ44/40Ca of genotyped and core-top N. pachyderma (sin.), becoming insensitive to temperature. These findings highlight the need of more systematic calibration studies on single planktonic foraminiferal species in order to unravel species-specific factors influencing the temperature sensitivity of Ca isotope fractionation and to validate the proxies' applicability.

Description: 10.1111/j.1439-0426.2009.01215.x

Description: During the European Iron Fertilisation Experiment (EIFEX), performed in the Southern Ocean, we investigated the reactions of different phytoplankton size classes to iron fertilization, applying measurements of size fractionated pigments, particulate organic matter, microscopy, and flow cytometry. Chlorophyll a (Chl a) concentrations at 20-m depth increased more than fivefold following fertilization through day 26, while concentrations of particulate organic carbon (POC), nitrogen (PON), and phosphorus (POP) roughly doubled through day 29. Concentrations of Chl a and particulate organic matter decreased toward the end of the experiment, indicating the demise of the iron-induced phytoplankton bloom. Despite a decrease in total diatom biomass at the end of the experiment, biogenic particulate silicate (bPSi) concentrations increased steadily due to a relative increase of heavily silicified diatoms. Although diatoms 〉 20 mu m were the main beneficiaries of iron fertilization, the growth of small diatoms (2-8 mu m) was also enhanced, leading to a shift from a haptophyte- to a diatom-dominated community in this size fraction. The total biomass had lower than Redfield C : N, N : P, and C : P ratios but did not show significant trends after iron fertilization. This concealed various alterations in the elemental composition of the different size fractions. The microplankton 20 mu m) showed decreasing C : N and increasing N : P and C : P ratios, possibly caused by increased N uptake and the consumption of cellular P pools. The nanoplankton (2-20 mu m) showed almost constant C : N and decreasing N : P and C : P ratios. Our results suggest that the latter is caused by a shift in composition of taxonomic groups.

Description: The soxB gene encodes the SoxB component of the periplasmic thiosulfate-oxidizing Sox enzyme complex, which has been proposed to be widespread among the various phylogenetic groups of sulfur-oxidizing bacteria (SOB) that convert thiosulfate to sulfate with and without the formation of sulfur globules as intermediate. Indeed, the comprehensive genetic and genomic analyses presented in the present study identified the soxB gene in 121 phylogenetically and physiologically divergent SOB, including several species for which thiosulfate utilization has not been reported yet. In first support of the previously postulated general involvement of components of the Sox enzyme complex in the thiosulfate oxidation process of sulfur-storing SOB, the soxB gene was detected in all investigated photo- and chemotrophic species that form sulfur globules during thiosulfate oxidation (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, Thiothrix, Beggiatoa, Thiobacillus, invertebrate symbionts and free-living relatives). The SoxB phylogeny reflected the major 16S rRNA gene-based phylogenetic lineages of the investigated SOB, although topological discrepancies indicated several events of lateral soxB gene transfer among the SOB, e.g. its independent acquisition by the anaerobic anoxygenic phototrophic lineages from different chemotrophic donor lineages. A putative scenario for the proteobacterial origin and evolution of the Sox enzyme system in SOB is presented considering the phylogenetic, genomic (sox gene cluster composition) and geochemical data.

Description: The `plate tectonic mirror image' to the region of the Cocos and Nazca plates, which are currently being subducted beneath Central America, is preserved in the Central Pacific around 120°W just south of the equator. Cruise SO-180 investigated this remote area during project CENTRAL and acquired new magnetic and bathymetric data. A plate tectonic model for the ‘mirror image’ is presented based on the newly acquired as well as reprocessed existing data. Discordant magnetic anomaly patterns and bathymetric structures indicate at least two major reorganization events (19.5 and 14.7 Myr), which can be detected both in the Cocos-Nazca spreading system and in the East Pacific Rise. Irregularities in the anomaly pattern and curvilinear structures on the sea floor of the survey area are interpreted in terms of a fossil overlapping spreading centre at the location where the Farallon break-up originated.

Description: Rates of dinitrogen (N2) fixation and primary production were measured during two 9 day transect cruises in the Baltic proper in June–July of 1998 and 1999. Assuming that the early phase of the bloom of cyanobacteria lasted a month, total rates of N2 fixation contributed 15 mmol N m−2 (1998) and 33 mmol N m−2 (1999) to new production (sensu Dugdale and Goering, 1967). This constitutes 12–26% more new N than other annual estimates (mid July–mid October) from the same region. The between-station variability observed in both total N2 fixation and primary productivity greatly emphasizes the need for multiple stations and seasonal sampling strategies in biogeochemical studies of the Baltic Sea. The majority of new N from N2 fixation was contributed by filamentous cyanobacteria. On average, cyanobacterial cells 〉20 µm were able to supply a major part of their N requirements for growth by N2 fixation in both 1998 (73%) and 1999 (81%). The between-station variability was high however, and ranged from 28–150% of N needed to meet the rate of C incorporation by primary production. The molar C:N rate incorporation ratio (C:NRATE) in filamentous cyanobacterial cells was variable (range 7–28) and the average almost twice as high as the Redfield ratio (6.6) in both years. Since the molar C:N mass ratio (C:NMASS) in filamentous cyanobacterial cells was generally lower than C:NRATE at a number of stations, we suggest that the diazotrophs incorporated excess C on a short term basis (carbohydrate ballasting and buoyancy regulation), released nitrogen or utilized other regenerated sources of N nutrients. Measured rates of total N2 fixation contributed only a minor fraction of 13% (range 4–24) in 1998 and 18% (range 2–45) in 1999 to the amount of N needed for the community primary production. An average of 9 and 15% of total N2 fixation was found in cells 〈5 µm. Since cells 〈5 µm did not show any detectable rates of N2 fixation, the 15N-enrichment could be attributed to regenerated incorporation of dissolved organic N (DON) and ammonium generated from larger diazotroph cyanobacteria. Therefore, N excretion from filamentous cyanobacteria may significantly contribute to the pool of regenerated nutrients used by the non-diazotroph community in summer. Higher average concentrations of regenerated N (ammonium) coincided with higher rates of N2 fixation found during the 1999 transect and a higher level of 15N-enrichment in cells 〈5 µm. A variable but significant fraction of total N2 fixation (1–10%) could be attributed to diazotrophy in cells between 5–20 µm.

Description: Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS), the Atlantic (ATL) and the Southern Ocean (SO). With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas include the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least ±0.005.

Description: The prevalence of antigrazing defense induction and the cues triggering induction in marine macroalgae are generally not well understood. We examined the capacity of defense and the mechanisms of regulation in five common perennial macroalgal species from the Baltic Sea, Furcellaria lumbricalis (Huds.) J. V. Lamour., Delesseria sanguinea (Huds.) J. V. Lamour., Phyllophora pseudoceranoides (S. G. Gmel.) Newroth et A. R. A. Taylor, Fucus serratus L., and Fucus evanescens C. Agardh. Specifically, we investigated whether direct feeding and/or waterborne cues from feeding on neighboring conspecifics decreased the palatability of the tested algae. Direct feeding by the local isopod Idotea baltica triggered the induction of chemical defense in Fur. lumbricalis, D. sanguinea, P. pseudoceranoides, F. serratus, and F. evanescens. Conversely, we did not find any evidence for waterborne cues associated with feeding to trigger defense induction in neighboring conspecifics.

Description: Permafrost environments in the Arctic are characterized by extreme environmental conditions that demand a specific resistance from microorganisms to enable them to survive. In order to understand the carbon dynamics in the climate-sensitive Arctic permafrost environments, the activity and diversity of methanogenic communities were studied in three different permafrost soils of the Siberian Laptev Sea coast. The effect of temperature and the availability of methanogenic substrates on CH4 production was analysed. In addition, the diversity of methanogens was analysed by PCR with specific methanogenic primers and by denaturing gradient gel electrophoresis (DGGE) followed by sequencing of DGGE bands reamplified from the gel. Our results demonstrated methanogenesis with a distinct vertical profile in each investigated permafrost soil. The soils on Samoylov Island showed at least two optima of CH4 production activity, which indicated a shift in the methanogenic community from mesophilic to psychrotolerant methanogens with increasing soil depth. Furthermore, it was shown that CH4 production in permafrost soils is substrate-limited, although these soils are characterized by the accumulation of organic matter. Sequence analyses revealed a distinct diversity of methanogenic archaea affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae. However, a relationship between the activity and diversity of methanogens in permafrost soils could not be shown.

Description: CORONA images have been used for the mapping of periglacial features on the Bykovsky Peninsula and adjacent Khorogor Valley in northeast Siberia. Features, mapped and analysed within a geographical information system, include thermokarst depressions, thermo-erosional valleys, thermo-erosional cirques, thermokarst lakes, thermokarst lagoons and pingos. More than 50% of the area is strongly influenced by thermally-induced subsidence. Thermokarst in the area is probably less active today than in the early-middle Holocene.

Description: The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21°C. Deep active layer zones that are constantly exposed to temperatures below 2°C showed a maximum potential to oxidize methane at 4°C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.

Description: Permafrost environments within the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon dynamics in high latitudes, we studied the methane concentration, the quantity and quality of organic matter, and the activity and biomass of the methanogenic community in permafrost deposits. For these investigations a permafrost core of Holocene age was drilled in the Lena Delta (72°22′N, 126°28′E). The organic carbon of the permafrost sediments varied between 0.6% and 4.9% and was characterized by an increasing humification index with permafrost depth. A high CH4 concentration was found in the upper 4 m of the deposits, which correlates well with the methanogenic activity and archaeal biomass (expressed as PLEL concentration). Even the incubation of core material at −3 and −6°C with and without substrates showed a significant CH4 production (range: 0.04–0.78 nmol CH4 h−1 g−1). The results indicated that the methane in Holocene permafrost deposits of the Lena Delta originated from modern methanogenesis by cold-adapted methanogenic archaea. Microbial generated methane in permafrost sediments is so far an underestimated factor for the future climate development.

Description: Advances in detector technology enable a new generation of infrared limb sounders to measure 2-D images of the atmosphere. A proposed limb cloud imager (LCI) mode will detect clouds with a spatial resolution unprecedented for limb sounding. For the inference of temperature and trace gas distributions, detector pixels of the LCI have to be combined into super-pixels which provide the required signal-to-noise and information content for the retrievals. This study examines the extent to which tropospheric coverage can be improved in comparison to limb sounding using a fixed field of view with the size of the super-pixels, as in conventional limb sounders. The study is based on cloud topographies derived from (a) IR brightness temperatures (BT) of geostationary weather satellites in conjunction with ECMWF temperature profiles and (b) ice and liquid water content data of the Consortium for Small-scale Modeling-Europe (COSMO-EU) of the German Weather Service. Limb cloud images are simulated by matching the cloud topography with the limb sounding line of sight (LOS). The analysis of the BT data shows that the reduction of the spatial sampling along the track has hardly any effect on the gain in information. The comparison between BT and COSMO-EU data identifies the strength of both data sets, which are the representation of the horizontal cloud extent for the BT data and the reproduction of the cloud amount for the COSMO-EU data. The results of the analysis of both data sets show the great advantage of the cloud imager. However, because both cloud data sets do not present the complete fine structure of the real cloud fields in the atmosphere it is assumed that the results tend to underestimate the increase in information. In conclusion, real measurements by such an instrument may result in an even higher benefit for tropospheric limb retrievals.

Description: Sea ice brines were collected from a single floe composed of different ice types in the western Weddell Sea in December 2004. The chemical composition of the brines (temperature: 23.4°C to 22.1°C; salinity: 40–63) was examined on seven occasions over 25 days with measurements of dissolved oxygen, dissolved inorganic macronutrients (nitrate plus nitrite, ammonium, phosphorus [DIP], and silicic acid), pH, total alkalinity (AT), dissolved organic carbon (DOC) and nitrogen (DON), total dissolved inorganic carbon (CT), and the stable isotopic composition of CT (δ13CT). The in situ pH ranged from 8.41-8.82 on the seawater scale, dissolved oxygen from 212-604 µmol kg−1, nitrate from 0.1-3.1 µmol kg−1, ammonium 0.1-2.4 µmol kg−1, DIP 0.4- 2.0 µmol kg−1, silicic acid 4-80 µmol kg−1, AT 2,690-4,620 µeq kg−1, DOC 115-359 µmol kg−1, DON 8-26 µmol kg−1, CT 2,090-3,550 µmol kg−1, and δ13CT +2.9‰ - +6.4‰. Compared with the chemical composition of surface oceanic water (salinity of 34), the brines had elevated pH, reduced concentrations of dissolved inorganic macronutrients (including carbon), especially dissolved inorganic nitrogen, and were mostly supersaturated with dissolved oxygen with respect to equilibrium with air, whereas the CT was considerably enriched in 13C. The chemical composition of the brines was consistent with internal biological productivity, but there was a lack of a distinctive and uniform relationship among the major dissolved inorganic nutrients typically used for describing biological activity. This was interpreted as the result of varying stoichiometry of biological activity within a very small spatial scale. Modification by abiotic processes was a potential contributing factor, such as degassing acting on the dissolved oxygen concentration. Carbonate mineral formation, acting on AT and CT, was not evident in brines from first-year ice but was apparent in brine from second-year ice.

Description: In early May 2006 a record high air pollution event was observed at Ny-Ålesund, Spitsbergen. An atypical weather pattern established a pathway for the rapid transport of biomass burning aerosols from agricultural fires in Eastern Europe to the Arctic. Atmospheric stability was such that the smoke was constrained to low levels, within 2 km of the surface during the transport. A description of this smoke event in terms of transport and main aerosol characteristics can be found in Stohl et al. (2007). This study puts emphasis on the radiative effect of the smoke. The aerosol number size distribution was characterised by lognormal parameters as having an accumulation mode centered around 165–185 nm and almost 1.6 for geometric standard deviation of the mode. Nucleation and small Aitken mode particles were almost completely suppressed within the smoke plume measured at Ny-Ålesund. Chemical and microphysical aerosol information obtained at Mt. Zeppelin (474 m a.s.l) was used to derive input parameters for a one-dimensional radiation transfer model to explore the radiative effects of the smoke. The daily mean heating rate calculated on 2 May 2006 for the average size distribution and measured chemical composition reached 0.55 K day−1 at 0.5 km altitude for the assumed external mixture of the aerosols but showing much higher heating rates for an internal mixture (1.7 K day−1). In comparison a case study for March 2000 showed that the local climatic effects due to Arctic haze, using a regional climate model, HIRHAM, amounts to a maximum of 0.3 K day−1 of heating at 2 km altitude (Treffeisen et al., 2005).

Description: Cryolithological, ground ice and fossil bioindicator (pollen, diatoms, plant macrofossils, rhizopods, insects, mammal bones) records from Bol'shoy Lyakhovsky Island permafrost sequences (73°20′N, 141°30′E) document the environmental history in the region for the past c. 115 kyr. Vegetation similar to modern subarctic tundra communities prevailed during the Eemian/Early Weichselian transition with a climate warmer than the present. Sparse tundra-like vegetation and harsher climate conditions were predominant during the Early Weichselian. The Middle Weichselian deposits contain peat and peaty soil horizons with bioindicators documenting climate amelioration. Although dwarf willows grew in more protected places, tundra and steppe vegetation prevailed. Climate conditions became colder and drier c. 30 kyr BP. No sediments dated between c. 28.5 and 12.05 14C kyr BP were found, which may reflect active erosion during that time. Herb and shrubby vegetation were predominant 11.6–11.3 14C kyr BP. Summer temperatures were c. 4 °C higher than today. Typical arctic environments prevailed around 10.5 14C kyr BP. Shrub alder and dwarf birch tundra were predominant between c. 9 and 7.6 kyr BP. Reconstructed summer temperatures were at least 4 °C higher than present. However, insect remains reflect that steppe-like habitats existed until c. 8 kyr BP. After 7.6 kyr BP, shrubs gradually disappeared and the vegetation cover became similar to that of modern tundra. Pollen and beetles indicate a severe arctic environment c. 3.7 kyr BP. However, Betula nana, absent on the island today, was still present. Together with our previous study on Bol'shoy Lyakhovsky Island covering the period between about 200 and 115 kyr, a comprehensive terrestrial palaeoenvironmental data set from this area in western Beringia is now available for the past two glacial–interglacial cycles.

Description: Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.

Description: The novel candidate phylum Poribacteria is specifically associated with several marine demosponge genera. Because no representatives of Poribacteria have been cultivated, an environmental genomic approach was used to gain insights into genomic properties and possibly physiological/functional features of this elusive candidate division. In a large-insert library harbouring an estimated 1.1 Gb of microbial community DNA from Aplysina aerophoba, a Poribacteria-positive 16S rRNA gene locus was identified. Sequencing and sequence annotation of the 39 kb size insert revealed 27 open reading frames (ORFs) and two genes for stable RNAs. The fragment exhibited an overall G+C content of 50.5% and a coding density of 86.1%. The 16S rRNA gene was unlinked from a conventional rrn operon. Its flanking regions did not show any synteny to other 16S rRNA encoding loci from microorganisms with unlinked rrn operons. Two of the predicted hypothetical proteins were highly similar to homologues from Rhodopirellula baltica. Furthermore, a novel kind of molybdenum containing oxidoreductase was predicted as well as a series of eight ORFs encoding for unusual transporters, channel or pore forming proteins. This environmental genomics approach provides, for the first time, genomic and, by inference, functional information on the so far uncultivated, sponge-associated candidate division Poribacteria.

Description: Patiria miniata, a broadcast-spawning sea star species with high dispersal potential, has a geographic range in the intertidal zone of the northeast Pacific Ocean from Alaska to California that is characterized by a large range gap in Washington and Oregon. We analyzed spatial genetic variation across the P. miniata range using multilocus sequence data (mtDNA, nuclear introns) and multilocus genotype data (microsatellites). We found a strong phylogeographic break at Queen Charlotte Sound in British Columbia that was not in the location predicted by the geographical distribution of the populations. However, this population genetic discontinuity does correspond to previously described phylogeographic breaks in other species. Northern populations from Alaska and Haida Gwaii were strongly differentiated from all southern populations from Vancouver Island and California. Populations from Vancouver Island and California were undifferentiated with evidence of high gene flow or very recent separation across the range disjunction between them. The surprising and discordant spatial distribution of populations and alleles suggests that historical vicariance (possibly caused by glaciations) and contemporary dispersal barriers (possibly caused by oceanographic conditions) both shape population genetic structure in this species.

Description: Samples from three hot springs (Alla, Seya and Garga) located in the northeastern part of Baikal rift zone (Buryat Republic, Russia) were screened for the presence of thermophilic nitrifying bacteria. Enrichment cultures were obtained solely from the Garga spring characterized by slightly alkaline water (pH 7.9) and an outlet temperature of 75°C. The enrichment cultures of the ammonia- and nitrite oxidizers grew at temperature ranges of 27–55 and 40–60°C, respectively. The temperature optimum was approximately 50°C for both groups and thus they can be designated as moderate thermophiles. Ammonia oxidizers were identified with classical and immunological techniques. Representatives of the genus Nitrosomonas and Nitrosospira-like bacteria with characteristic vibroid morphology were detected. The latter were characterized by an enlarged periplasmic space, which has not been previously observed in ammonia oxidizers. Electron microscopy, denaturing gradient gel electrophoresis analyses and partial 16S rRNA gene sequencing provided evidence that the nitrite oxidizers were members of the genus Nitrospira.

Description: The Siberian Laptev Sea shelf contains submarine permafrost, which was formed by flooding of terrestrial permafrost with ocean water during the Holocene sea level rise. This flooding resulted in a warming of the permafrost to temperatures close below 0°C. The impact of these environmental changes on methanogenic communities and carbon dynamics in the permafrost was studied in a submarine permafrost core of the Siberian Laptev Sea shelf. Total organic carbon (TOC) content varied between 0.03% and 8.7% with highest values between 53 and 62 m depth below sea floor. In the same depth, maximum methane concentrations (284 nmol CH4 g−1) and lowest carbon isotope values of methane (−72.2‰ VPDB) were measured, latter indicating microbial formation of methane under in situ conditions. The archaeal community structure was assessed by a nested polymerase chain reaction (PCR) amplification for DGGE, followed by sequencing of reamplified bands. Submarine permafrost samples showed a different archaeal community than the nearby terrestrial permafrost. Samples with high methane concentrations were dominated by sequences affiliated rather to the methylotrophic genera Methanosarcina and Methanococcoides as well as to uncultured archaea. The presented results give the first insights into the archaeal community in submarine permafrost and the first evidence for their activity at in situ conditions.

Description: The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma) ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the “stilt-legged” horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true) horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

Description: The potential for nitrification in the Mediterranean sponge Aplysina aerophoba was assessed using a combined physiological and molecular approach. Nitrate excretion rates in whole sponges reached values of up to 344 nmol g(-1) dry weight (wt) h(-1) (unstimulated) and 1325 nmol g(-1) dry wt h(-1) (stimulated). Addition of nitrapyrin, a nitrification-specific inhibitor, effectively inhibited nitrate excretion. Ammonium was taken up by sponges in spring and excreted in fall, the sponges thus serving as either an ammonium sink or ammonium source. Nitrosospira cluster 1 and Crenarchaeota group I.1A 16S rRNA and amoA genes were recovered from A. aerophoba and other sponges from different world's oceans. The archaeal 16S rRNA genes formed a sponge-specific subcluster, indicating that their representatives are members of the stable microbial community of sponges. On the other hand, clustering was not evident for Nitrosospira rRNA genes which is consistent with their presence in sediment and seawater samples. The presence of both Nitrosospira cluster 1 and crenarchaeal group 1 phylotypes in sponge tissue was confirmed using fluorescently labelled 16S rRNA gene probes. This study contributes to an ongoing effort to link microbial diversity with metabolic functions in the phylogenetically diverse, elusive and so far uncultivated microbial communities of marine sponges.

Description: 1. To study the influence of chironomids on the distribution of pore-water concentrations of phosphate, iron and ammonium, we conducted a laboratory experiment using mesocosms equipped with two-dimensional pore-water samplers, filled with lake sediment and populated with different densities of Chironomus plumosus. 2. Specially designed mesocosms were used in the study. A 6-mm deep space between the front plate and the pore-water sampler at the back plate was just thick enough to allow the chironomids to live undisturbed, yet thin enough to force all the burrows into a two-dimensional plane. 3. The courses of the burrows were observed during the experiment as oxidised zones surrounding them, as well as being identified with an X-ray image taken at the end of the experiment. 4. We investigated the relationship between C. plumosus burrows and spatial patterns of pore-water composition. Concentrations of the three ions were significantly less around ventilated burrows (54% to 24%), as bioirrigation caused a convective exchange of pore-water enriched with dissolved species compared with the overlying water, and also because oxygen imported into the sediment resulting in nitrification of ammonium, oxidation of iron(II) and a co-precipitation of phosphate with Fe(III) oxyhydroxides. 5. In mesocosms with chironomids, new (redox) interfaces occurred with diffusive pore-water gradients perpendicular to the course of burrows and the site of major phosphate, ammonium and iron(II) release shifted from the sediment surface to the burrow walls.

Description: Samples from the bottom of the sea were used in the exact determination of the crystals structures of naturally occurring hydrocarbon hydrates. The hydrates of methane, ethane, and propane had a cubic structure II with hexakaidecahedral and pentagonal dodecahedral cages occupied by the guest molecules.

Description: The Baltic and Black Seas are both brackish, that is to say both have salinities intermediate between freshwater and seawater. The coccolithophore Emiliania huxleyi is abundant in one, the Black Sea, but absent from the other, the Baltic Sea. Here we present summertime coccolithophore measurements confirming this difference, as well as data on the calcium carbonate saturation state of the Baltic Sea. We find that the Baltic Sea becomes undersaturated (or nearly so) in winter, with respect to both the aragonite and calcite mineral forms of CaCO3. Data for the Black Sea are more limited, but it appears to remain strongly supersaturated year-round. The absence of E. huxleyi from the Baltic Sea could therefore potentially be explained by dissolution of their coccoliths in winter, suggesting that minimum annual (wintertime) saturation states could be most important in determining future ocean acidification impacts. In addition to this potential importance of winter saturation state, alternative explanations are also possible, either related to differences in salinity or else to differences in silicate concentrations.

Description: The utility of cuticular autofluorescence for the visualization of copepod morphology by means of confocal laser scanning microscopy (CLSM) was examined. Resulting maximum intensity projections give very accurate information on morphology and show even diminutive structures such as small setae in detail. Furthermore, CLSM enables recognition of internal structures and differences in material composition. Optical sections in all layers and along all axes of the specimens can be obtained by CLSM. The facile and rapid preparation method bears no risk of artefacts or damage occurring to the preparations and the visualized specimens can be used for later analyses allowing for the investigation of irreplaceable type specimens or parts of them. These features make CLSM a very effective tool for both taxonomical and ecological studies in small crustaceans; however, the maximum thickness of the specimens is limited to a few hundred micrometers. Three-dimensional models based on CLSM image stacks allow observation of the preparations from all angles and can permit, improve and speed up studies on functional morphology. The visualization method described has a strong potential to become a future standard technique in aquatic biology due to its advantages over conventional light microscopy and scanning electron microscopy.

Description: Artificial Neural Networks (ANN) are efficient tools to derive solar UV radiation from measured meteorological parameters such as global radiation, aerosol optical depths and atmospheric column ozone. The ANN model has been tested with different combinations of data from the two sites Potsdam and Lindenberg, and used to reconstruct solar UV radiation at eight European sites by more than 100 years into the past. Special emphasis will be given to the discussion of small-scale characteristics of input data to the ANN model. Annual totals of UV radiation derived from reconstructed daily UV values reflect interannual variations and long-term patterns that are compatible with variabilities and changes of measured input data, in particular global dimming by about 1980/1990, subsequent global brightening, volcanic eruption effects such as that of Mt. Pinatubo, and the long-term ozone decline since the 1970s. Patterns of annual erythemal UV radiation are very similar at sites located at latitudes close to each other, but different patterns occur between UV radiation at sites in different latitude regions.

Description: The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35° N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

Description: Large-scale, spatially explicit models of adaptive radiation suggest that the spatial genetic structure within a species sampled early in the evolutionary history of an adaptive radiation might be higher than the genetic differentiation between different species formed during the same radiation over all locations. Here we test this hypothesis with a spatial population genetic analysis of Hypoplectrus coral reef fishes (Serranidae), one of the few potential cases of a recent adaptive radiation documented in the marine realm. Microsatellite analyses of Hypoplectrus puella (barred hamlet) and Hypoplectrus nigricans (black hamlet) from Belize, Panama and Barbados validate the population genetic predictions at the regional scale for H. nigricans despite the potential for high levels of gene flow between populations resulting from the 3-week planktonic larval phase of Hypoplectrus. The results are different for H. puella, which is characterized by significantly lower levels of spatial genetic structure than H. nigricans. An extensive field survey of Hypoplectrus population densities complemented by individual-based simulations shows that the higher abundance and more continuous distribution of H. puella could account for the reduced spatial genetic structure within this species. The genetic and demographic data are also consistent with the hypothesis that H. puella might represent the ancestral form of the Hypoplectrus radiation, and that H. nigricans might have evolved repeatedly from H. puella through ecological speciation. Altogether, spatial genetic analysis within and between Hypoplectrus species indicate that local processes can operate at a regional scale within recent marine adaptive radiations

Description: We present a new three-dimensional (3-D) P-wave velocity model for the upper-crustal structure beneath the Strait of Georgia, southwestern British Columbia based on non-linear tomographic inversion of wide-angle seismic refraction data. Our study, part of the Georgia Basin Geohazards Initiative (GBGI) is primarily aimed at mapping the depth of the Cenozoic sedimentary basin and delineating the near-surface crustal faults associated with recent seismic activities (e.g. M = 4.6 in 1997 and M = 5.0 in 1975) in the region. Joint inversion of first-arrival traveltimes from the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) and the 2002 Georgia Basin experiment provides a high-resolution velocity model of the subsurface to a depth of ???7 km. In the southcentral Georgia Basin, sedimentary rocks of the Cretaceous Nanaimo Group and early Tertiary rocks have seismic velocities between 3.0 and 5.5 km s-1. The basin thickness increases from north to south with a maximum thickness of 7 (??1) km (depth to velocities of 5.5 km s-1) at the southeast end of the strait. The underlying basement rocks, probably representing the Wrangellia terrane, have velocities of 5.5-6.5 km-1 with considerable lateral variation. Our tomographic model reveals that the Strait of Georgia is underlain by a fault-bounded block within the central Georgia Basin. It also shows a correlation between microearthquakes and areas of rapid change in basin thickness. The 1997/1975 earthquakes are located near a northeast-trending hinge line where the thicknesses of sedimentary rocks increase rapidly to the southeast. Given its association with instrumentally recorded, moderate sized earthquakes, we infer that the hinge region is cored by an active fault that we informally name the Gabriola Island fault. A northwest-trending, southwest dipping velocity discontinuity along the eastern side of Vancouver Island correlates spatially with the surface expression of the Outer Island fault. The Outer Island fault as mapped in our seismic tomography model is a thrust fault that projects directly into the Lummi Island fault, suggesting that they are related structures forming a fault system that is continuous for nearly 90 km. Together, these inferred thrust faults may account for at least a portion of the basement uplift at the San Juan Islands. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Description: Late Quaternary sediments in a permafrost environment recovered from the Elgygytgyn Impact Crater were studied to determine regional palaeoenvironmental variability and infer past water-level changes of the crater lake. Stratigraphic analysis of a 5 m long permafrost core is based on various lithological (grain size, total organic carbon, magnetic susceptibility) and hydrochemical (oxygen isotope composition, major cation content) properties and pore ice content. The results show that alluvial sediments accumulated on top of cryogenically weathered volcanic rock. Changes in the hydrochemical properties reflect different stages of cryogenic weathering. The lithological characteristics mark the transition from an erosive site to a site with accumulation. This environmental change is linked to a relative lake level highstand at 〉13 000 yr BP, when a shoreline bar was formed leading to slope sedimentation. Lake level dropped by 4 m during the Holocene.

Description: Previously uncultured nitrite-oxidizing bacteria affiliated to the genus Nitrospira have for the first time been successfully enriched from activated sludge from a municipal wastewater treatment plant. During the enrichment procedure, the abundance of the Nitrospira-like bacteria increased to approximately 86% of the total bacterial population. This high degree of purification was achieved by a novel enrichment protocol, which exploits physiological features of Nitrospira-like bacteria and includes the selective repression of coexisting Nitrobacter cells and heterotrophic contaminants by application of ampicillin in a final concentration of 50 µg ml−1. The enrichment process was monitored by electron microscopy, fluorescence in situ hybridization (FISH) with rRNA-targeted probes and fatty acid profiling. Phylogenetic analysis of 16S rRNA gene sequences revealed that the enriched bacteria represent a novel Nitrospira species closely related to uncultured Nitrospira-like bacteria previously found in wastewater treatment plants and nitrifying bioreactors. The enriched strain is provisionally classified as ‘Candidatus Nitrospira defluvii’.

Description: For the understanding and assessment of recent and future carbon dynamics of arctic permafrost soils the processes of CH4 production and oxidation, the community structure and the quality of dissolved organic matter (DOM) were studied in two soils of a polygonal tundra. Activities of methanogens and methanotrophs differed significantly in their rates and distribution patterns among the two investigated profiles. Community structure analysis showed similarities between both soils for ester-linked phospholipid fatty acids (PLFAs) and differences in the fraction of unsaponifiable PLFAs and phospholipid ether lipids. Furthermore, a shift of the overall composition of the microbiota with depth at both sites was indicated by an increasing portion of iso- and anteiso-branched fatty acids related to the amount of straight-chain fatty acids. Although permafrost soils represent a large carbon pool, it was shown that the reduced quality of organic matter leads to a substrate limitation of the microbial metabolism. It can be concluded from our and previous findings first that microbial communities in the active layer of an Arctic polygon tundra are composed by members of all three domains of life, with a total biomass comparable to temperate soil ecosystems, and second that these microorganisms are well adapted to the extreme temperature gradient of their environment.

Description: Induced breeding of climbing perch, Anabas testudineus was conducted by synthetic hormone Wova-FH in the intensity level of 0.1, 0.2 and 0.3 mL kg−1 of body weight respectively. The brooders were injected one time and left to spawn in the spawning hapa in the sex ratio between male and female as 2:1. It was found that at all the intensity level hormone Wova-FH could enhance the fishes to breed and lay eggs whereas no breeding was observed in control set. The spawning time, quantity of the brooder spawn, fertilization rate, hatching rate and survival rate were quantified in each set of experiment. The egg output/female was significantly higher in 0.3 mL in comparison with 0.1 and 0.2 mL kg−1 of body weight. The statistical analysis showed significant (P≤0.05) effect between hormone dose on fertilization rate, egg output and hatching rate. The present experiment suggests that Wova-FH at the dose of 0.3 mL kg−1 body weight of fish is more effective which might be considered for raising captive population.

Description: The model marine crenarchaeote 'Cenarchaeum symbiosum' is until now the only ammonia-oxidizing archaeon known from a marine sponge. Here, phylogenetic analyses based on the 16S rRNA and ammonia monooxygenase subunit A (amoA) genes revealed the presence of putative ammonia-oxidizing archaea (AOA) in a diverse range of sponges from the western Pacific, Caribbean and Mediterranean. amoA diversity was limited even between different oceans, with many of the obtained sequences (75.9%; n(total) = 83) forming a monophyletic, apparently sponge- (and coral-) specific lineage, analogous to those previously inferred from comparative 16S rRNA gene studies of sponge-associated microbes. The presence of AOA in sponge larvae, as detected by 16S rRNA and amoA PCR assays as well as by fluorescence in situ hybridization, suggests they are vertically transmitted and thus might be of importance for ammonia detoxification within the sponge.

Description: The discovery of phylogenetically complex, yet highly sponge-specific microbial communities in marine sponges, including novel lineages and even candidate phyla, came as a surprise. At the same time, unique research opportunities opened up, because the microorganisms of sponges are in many ways more accessible than those of seawater. Accordingly, we consider sponges as microbial fermenters that provide exciting new avenues in marine microbiology and biotechnology. This review covers recent findings regarding diversity, biogeography and population dynamics of sponge-associated microbiota, and the data are discussed within the larger context of the microbiology of the ocean.

Description: This paper updates the analysis by Osborn et al. of trends in the contribution of heavy events to precipitation in the UK. We spatially extended the previous analysis of 110 rain gauges to a set of 689 rain gauges covering almost the whole UK, and updated the results to November 2006. For each station and season, we calculated ten time series of the contribution of ten precipitation amount categories to the total seasonal precipitation. A principal component analysis of post-1961 trends of all categories and stations is consistent with earlier results, namely, widespread shifts towards greater contribution from heavier precipitation categories during winter, and towards light and moderate categories during summer. Regional and UK average time series of the contribution from the category consisting of the heaviest events indicate that the increased winter intensity was sustained during the most recent ten years, but the trend did not continue at the rate reported previously for 1961–1995. For summer, the decreasing contribution from the heaviest rainfall category reported for 1961–1995 underwent a reversal during the most recent decade, returning towards the 1961–1995 reference level of intensity. Confidence intervals for these regional and UK average time series were estimated by a bootstrap approach and indicate that the sparser observations from the first half of the 20th century are still sufficient to estimate UK average change. These longer records support the existence of a long-term increase in winter precipitation intensity, and similar trends have now also become evident in spring and (to a lesser extent) autumn. The summer rainfall intensity has exhibited changes that are more consistent with inter-decadal variability than any overall trend. Copyright © 2008 Royal Meteorological Society

Description: Sinking particles, once caught in sediment trap jars, release dissolved elements into the surrounding medium through leaching from their pore fluids, chemical dissolution and the activity of free exoenzymes. This results in an increase in dissolved elements in the trap jar supernatant. Elemental fluxes as traditionally measured by sediment traps underestimate total export when this particle-associated dissolved flux is not considered. The errors introduced are variable and alter both the absolute levels of flux as well as the stoichiometry of export. These errors have been quantified and corrections applied for samples from sediment traps in the North Atlantic based on measurements of excess dissolved carbon, nitrogen, phosphorus, silica and calcium in the supernatant of the collection cups. At the base of the winter mixed layer, on average 90±6% of phosphorus fluxes are found as excess phosphate whereas for carbon and nitrogen dissolved concentrations account for 30 (±8)% and 47(±11)% of total fluxes respectively. Excess dissolved silica is on average 61 (±17)% of total biogenic silica flux. Little (〈10%) of calcium is solubilized. The proportion of dissolved to total flux decreases with trap deployment depth. Calculations of the C:N:P ratios for particles only are well above the Redfield ratios of 106:16:1 (Redfield et al., 1963), although the mid-water dissolved N:P and N:Si values as well as the C:N:P ratios of remineralisation along isopycnals conform to the Redfield ratios at this site. Accounting for dissolved fluxes of all these elements brings the stoichiometry of export in agreement with the Redfield Ratio and with other geochemical estimates of winter mixed layer export. A factor of 3 to 4 higher ratios of organic: inorganic carbon export also implies that the net atmospheric CO2 sequestration by the biological pump is about 50% higher at this site when the dissolved elemental fluxes are considered. Solubilization is thus a process that should be accounted for in protocols used to measure vertical fluxes with sediment traps.

Description: Life history responses are expected to accompany climate warming, yet little is known how long-term effects of climate and environmental change affect the seasonal dynamics of planktonic organisms. We used an historical data set from Lake Washington (U.S.A.) to quantify population responses of a calanoid copepod (Leptodiaptomus ashlandi) to long-term changes in temperature and resource availability and explore potential mechanisms for the responses. Increasing water temperatures (annual mean increase of 1.5 degrees C in the upper 10-m water volume) and longer stratification periods (about 4 weeks) were observed between 1962 and 2005, coincident with a pronounced decline in Leptodiaptomus densities. However, production was maintained because of an increase in the production to biomass ratio and a life cycle shift in Leptodiaptomus from an annual to a 6-month cycle. Cross-wavelet analyses demonstrated that the annual thermal forcing of copepod recruitment observed during the first two decades of the study weakened substantially, leading to more stochastic population dynamics during the past two decades. This shift from one to two generations per year was most likely produced by a longer and warmer growing period combined with changing fluctuations in resource (phytoplankton) availability. Climate change can lead to higher-frequency voltinism in ectothermic organisms and to temporal reorganization of their population dynamics.

Description: We present a study of Saharan dust export towards the tropical North Atlantic using the regional dust emission, transport and deposition model LM-MUSCAT. Horizontal and vertical distribution of dust optical thickness, concentration, and dry and wet deposition rates are used to describe seasonality of dust export and deposition towards the eastern Atlantic for three typical months in different seasons. Deposition rates strongly depend on the vertical dust distribution, which differs with seasons. Furthermore the contribution of dust originating from the Bodélé Depression to Saharan dust over the Atlantic is investigated. A maximum contribution of Bodélé dust transported towards the Cape Verde Islands is evident in winter when the Bodélé source area is most active and dominant with regard to activation frequency and dust emission. Limitations of using satellite retrievals to estimate dust deposition are highlighted.

Description: Coastal upwelling regions have been identified as sites of enhanced CH4 emissions to the atmosphere. The coastal upwelling area off Mauritania (NW Africa) is one of the most biologically productive regions of the world's ocean but its CH4 emissions have not been quantified so far. More than 1000 measurements of atmospheric and dissolved CH4 in the surface layer in the upwelling area off Mauritania were performed as part of the German SOPRAN (Surface Ocean Processes in the Anthropocene) study during two cruises in March/April 2005 (P320/1) and February 2007 (P348). During P348 enhanced CH4 saturations of up to 200% were found close to the coast and were associated with upwelling of South Atlantic Central Water. An area-weighted, seasonally adjusted estimate yielded overall annual CH4 emissions in the range from 1.6 to 2.9 Gg CH4. Thus the upwelling area off Mauritania represents a regional hot spot of CH4 emissions but seems to be of minor importance for the global oceanic CH4 emissions.

Description: We investigated potential connections between climate and the population size of gelatinous carnivores in the northwestern Mediterranean. The interannual variability of large- and meso-scale climate factors was related to gelatinous carnivore dynamics by means of a multivariate regression model. Gelatinous carnivore population dynamics integrate the climate-related changes in the northwestern Mediterranean with close correlations between climate and the population size of the Calycophoran siphonophores Chelophyes appendiculata and Abylopsis tetragona and the Hydromedusae Rhopalonema velatum and Solmundella bitentaculata. We show that the sensitivity of particular gelatinous carnivore species to environmental forcing relates to their seasonal appearance and peak of abundance. Our results advocate the occurrence of short time windows, during which gelatinous carnivores appear more sensitive to environmental conditions, and favorable conditions may therefore substantially enhance their annual peaks. Furthermore, there were threshold values from which climate effects on gelatinous carnivores become noticeable, indicating that the climate-gelatinous carnivore relationship intensifies according to the strength of climate forcing. The possibility of using the North Atlantic climate variability for assessing and predicting interannual abundance changes of these organisms in the northwestern Mediterranean is considered.

Description: Detailed studies of the behavior and location of free-ranging animals can be considerably enhanced with the use of animal-mounted devices. A few devices, such as data loggers, have to be recovered to access the data, whereas satellite tags or radiocollars often are left on the animal after the study period. Recovery of devices, which usually necessitates animal recapture, can be problematic, especially in larger species. This paper presents a new, non-electronic release mechanism, requiring no power source on the animal, that was successfully tested on South American sea lions (Otaria flavescens) in Argentina during the 2003–2004 austral summer. The system has potential for many larger terrestrial or aquatic animals.

Description: A common elemental analyzer system connected to a temperature-controlled gas chromatography (GC) column and coupled to an isotope ratio mass spectrometer was improved to decrease the determination limit for a simultaneous stable isotope ratio measurement of nitrogen and carbon dioxide. The additional use of a special ashtray system to collect the combustion residuals permitted more time-efficient work. These modifications to the elemental analyzer allowed precise measurements to be made down to 1.5 µg nitrogen and 10 µg carbon for stable isotope analysis. Low system background values and an acceptable signal-to-noise ratio have made an additional blank correction for these low sample measurements unnecessary. We provide a precision of this stable isotope analysis for lowest amounts of 1.2–2 µg nitrogen with a standard deviation of ±0.496‰ (n = 27) and for 8.2–15 µg carbon with a standard deviation of ±0.257‰ (n = 31) across different sample runs under stipulated conditions. This application can be established in an automatic mode without cryofocusing procedures.

Description: The great cormorant Phalacrocorax carbo is thought to have a wettable plumage, providing low body insulation during foraging. Great cormorants should thus be constrained by water temperatures, and show high energy requirements. Surprisingly, this species has one of the widest breeding distributions of all diving birds, and does not require more food than these other species. We explored this apparent paradox by comparing the insulative properties of body plumage in four subspecies of great cormorants ranging from tropical to polar regions. We found that all subspecies retained an insulating air layer in their plumage, which was, however, much thinner than for other species of diving birds. Detailed examination of the plumage showed that each cormorant body feather has a loose, instantaneously wet, outer section and a highly waterproof central portion. This indicates that the plumage of great cormorants is only partly wettable, and that birds maintain a thin layer of air in their plumage. Our findings suggest an unusual morphological-functional adaptation to diving which balances the antagonist constraints of thermoregulation and buoyancy.

Description: Development of a mechanistic understanding and predictions of patterns of biodiversity is a central theme in ecology. One of the most influential theories, the intermediate disturbance hypothesis (IDH), predicts maximum diversity at intermediate levels of disturbance frequency. The dynamic equilibrium model (DEM), an extension of the IDH, predicts that the level of productivity determines at what frequency of disturbance maximum diversity occurs. To test, and contrast, the predictions of these two models, a field experiment on marine hard-substratum assemblages was conducted with seven levels of disturbance frequency and three levels of nutrient availability. Consistent with the IDH, maximum diversity, measured as species richness, was observed at an intermediate frequency of disturbance. Despite documented effects on productivity, the relationship between disturbance and diversity was not altered by the nutrient treatments. Thus, in this system the DEM did not improve the understanding of patterns of diversity compared to the IDH. Furthermore, it is suggested that careful consideration of measurements and practical definitions of productivity in natural assemblages is necessary for a rigorous test of the DEM.

Description: A wide range of bicarbonate concentrations was used to monitor the kinetics of bicarbonate (HCO3−) use in both photosynthesis and calcification in two reef‐building corals, Porites porites and Acropora sp. Experiments carried out close to the P. porites collection site in Barbados showed that additions of NaHCO3 to synthetic seawater proportionally increased the calcification rate of this coral until the concentration exceeded three times that of seawater (6 mM). Photosynthetic rates were also stimulated by HCO3− addition, but these became saturated at a lower concentration (4 mM). Similar experiments on aquarium‐acclimated colonies of Indo‐Pacific Acropora sp. showed that calcification and photosynthesis in this coral were enhanced to an even greater extent than P. porites, with calcification continuing to increase above 8 mM HCO3−, and photosynthesis saturating at 6 mM. Calcification rates of Acropora sp. were also monitored in the dark, and, although these were lower than in the light for a given HCO3− concentration, they still increased dramatically with HCO3− addition, showing that calcification in this coral is light stimulated but not light dependent.