bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of dust deposition and river discharges on trace metal composition of Trichodesmium spp. in the tropical and subtropical North Atlantic Ocean
Authors: Tovar-Sanchez Antonio , Sañudo-Wilhelmy Sergio A. , Kustka Adam B. , Agustí Susana , Dachs Jordi , Hutchins David A. , Capone Douglas G. , Duarte Carlos M.
Published: July 2010

We present the elemental composition (Al, Cd, Co, Cu, Fe, Mn, Mo, Ni, V, Zn, and P) of field‐collected Trichodesmium populations. To distinguish the effects of river discharges (Amazon and Niger Rivers) and Saharan dust deposition on metal concentrations in the colonies, samples were collected both in the western (February 2001, July‐August 2001, and April‐May 2003) and eastern (May‐June 2003) basins of the North Atlantic. Metal composition (medians normalized to P) in Trichodesmium ranged from 0.011 mmol mol−1 for Co to 39 mmol mol−1 for Fe and varied over an order of magnitude among different locations. A comparison of metal ratios measured in the Trichodesmium colonies with ratios reported for the potential sources suggests that the most important sources of trace metals to the tropical and subtropical Atlantic during our sampling were the Amazon and Niger Rivers, rather than dust deposition from the Sahara.
Seasonal refugia, shoreward thermal amplification, and metapopulation dynamics of the ctenophore Mnemiopsis leidyi in Narragansett Bay, Rhode Island
Authors: Costello J. H. , Sullivan B. K. , Gifford D. J. , Van Keuren D. , Sullivan L. J.
Published: July 2010

The lobate ctenophore Mnemiopsis leidyi occurs throughout Narragansett Bay, Rhode Island, during warm summer months but is often undetectable in the central portion of the bay during winter months. During 2 yr of weekly sampling, we found that M. leidyi populations in a shallow embayment, Greenwich Cove, either overwintered or were only briefly absent during winter. The Greenwich Cove population reproduced weeks earlier and reached higher average and peak population concentrations than open‐bay populations. Shallow embayment populations such as that in Greenwich Cove probably serve as source populations that inoculate the main region of the bay by advective transport in the spring months. We propose that earlier occurrences of M. leidyi during recent years are due to amplification of pulsed spring warming events that permit early reproduction in the shallow embayments that serve as source regions for M. leidyi in Narragansett Bay. We further suggest that the source‐sink perspective we describe is relevant not only to Narragansett Bay but other temperate regions of the world persistently occupied by M. leidyi.
Amphipod herbivory on the freshwater cyanobacterium Lyngbya wollei: Chemical stimulants and morphological defenses
Authors: Camacho Frank A. , Thacker Robert W.
Published: July 2010

The freshwater cyanobacterium Lyngbya wollei forms dense mats in lentic systems throughout the southeastern United States and produces paralytic shellfish poisons (PSPs), such as saxitoxins, that could provide a chemical defense against herbivory. In addition, Lyngbya filaments are surrounded by a prominent extracellular polysaccharide sheath that might function as a structural defense against herbivory. We investigated the roles of PSPs and sheath structure in deterring consumption of Lyngbya by an omnivorous amphipod, Hyalella azteca. A series of two‐choice feeding assays paired Lyngbya with a highly palatable green alga, Rhizoclonium hieroglyphicum. These assays included comparisons of whole Lyngbya and Rhizoclonium, freeze‐dried and ground Lyngbya and Rhizoclonium, artificial food treated with Lyngbya crude extract, artificial food treated with pure saxitoxin, and artificial food containing Lyngbya sheath material, with and without Lyngbya crude extract. Hyalella preferred whole, live Rhizoclonium over fresh Lyngbya. Similarly, Hyalella preferred freeze‐dried and ground Rhizoclonium over Lyngbya. However, Hyalella preferred treated foods containing Lyngbya crude extract or pure saxitoxin over control foods. The sheath constituted over 55% of the total dry mass of Lyngbya. In assays combining sheath material and crude extract in artificial foods, Hyalella avoided foods containing sheath material. Therefore, morphological defenses play an important role in deterring consumption of Lyngbya by Hyalella, whereas PSPs stimulate feeding. Our study indicates that structural defenses can partially explain the high abundance of filamentous cyanobacteria observed in aquatic communities under grazing pressure.
Plasticity in coloration as an antipredator strategy among zooplankton
Authors: Vestheim Hege , Kaartvedt Stein
Published: July 2010

We show that marine zooplankton change their level of coloration both with depth and time of the day. The carnivorous copepod Pareuchaeta norvegica caught near the bottom in 200‐400‐m deep‐water columns were darker than specimens caught higher in the water column. A diel rhythm in coloration occurred even at several hundred meters' depth, with individuals caught during night time being more pigmented than the ones caught during the day. We hypothesize that individuals actively adjust their degree of coloration to achieve optimal camouflage at the prevailing light regime.
High‐frequency internal waves in the littoral zone of a large lake
Authors: Lorke Andreas , Peeters Frank , Bäuerle Erich
Published: July 2010

Observations in the littoral zone of a large lake (Lake Constance) revealed strong and periodic fluctuations of temperature and current velocity on timescales between 10 and 15 min associated with high‐frequency internal waves. The peak in the spectral energy of the current velocity fluctuations associated with high‐frequency internal waves follows the seasonal dynamics of stratification, described by the stability frequency N. A comparison between the nearshore current velocity measurements in the littoral zone with temperature measurements in the pelagic of Lake Constance revealed a strong coupling between the occurrence of high‐frequency internal waves in the littoral zone and the passage of the basin‐scale internal Kelvin wave with a period of about 4 d.
Differential effect of algal‐ and soil‐derived dissolved organic matter on alpine lake bacterial community composition and activity
Authors: Pérez María Teresa , Sommaruga Ruben
Published: July 2010

We studied the effects of algal‐ and soil‐derived dissolved organic matter (DOM) enrichments on the activity and community composition of bacterioplankton in an alpine lake. The effects of the DOM source on bacteria were tested by establishing dilution cultures amended with either an algal lysate or with a soil extract. Cultures were incubated for 6 days under close to in situ conditions, and changes in bacterial community composition and activity were tracked by micro‐autoradiography ([3H]‐L‐leucine) combined with fluorescent in situ hybridization and signal amplification by catalyzed reporter deposition. Heterotrophic bacterial production increased by 25‐ fold after the algal lysate addition. After 3 days, up to 90% of the bacteria were active in this treatment, and β‐Proteobacteria, particularly the subgroup R‐BT, represented 86% and 67% of the total bacterial counts, respectively. From day 3 onward, the percentage of active cells in this treatment decreased dramatically as did the relative abundance of subgroup R‐BT. By the end of the experiment, β‐Proteobacteria still dominated bacterial abundance (80%), but active cells were only 25% of total bacterial counts. In contrast, the addition of soil‐derived DOM led only to a two‐ to three‐fold increase in bacterial production. β‐Proteobacteria was still the dominant group (50‐60% of total bacterial counts and 50% of the cells positive for leucine incorporation), but Actinobacteria made a substantial contribution (15‐23%). This pattern contrasted with that observed in the treatment receiving the algal lysate, where the relative abundance of the latter group rapidly decreased. In the treatment amended with algal‐derived DOM, bacterial carbon production matched the observed decrease in dissolved organic carbon concentration. However, bacterial carbon produced on soil‐derived DOM accounted only for 30% of the decrease in dissolved organic carbon concentration, suggesting a more inefficient utilization of this material. The expected climate‐driven changes in DOM supply to alpine lakes will affect their bacterial community structure and activity.
Fifteen degrees of separation: Latitudinal gradients of rocky intertidal biota along the California Current
Authors: Schoch G. Carl , Menge Bruce A. , Allison Gary , Kavanaugh Maria , Thompson Sarah Ann , A. Wood Spencer
Published: July 2010

The region of the eastern North Pacific coastline dominated by the California Current was surveyed annually from 2001‐2003 to examine (1) benthic macro‐invertebrate and algal populations, (2) the magnitude and patterns of key environmental variables, and (3) how dynamic populations and communities of macroalgae and invertebrates respond to spatial differences in nearshore geomorphology, wave dynamics, and oceanography of the coastal shelf. We used a highly replicated spatially nested sampling design consisting of 144 shore segments (bedrock platforms longer than 50 m) with three replicate segments per site (~1 km), three sites per area (~10 km), and sixteen areas (>10 km) grouped into six domains (hundreds of kilometers). Results suggest that (1) low zone diversity was higher at northern latitudes when measured at segment, site, and area scales, but at domain scales there were more species at southern latitudes; (2) community structure showed high fidelity to geographic location with community similarity inversely related to separation distance, and the only regional scale biological discontinuity in community structure was centered near Pt. Conception; and (3) wave runup was the most significant physical parameter affecting overall community structure, however, tidal range, precipitation, air and water temperature, upwelling, salinity, and sand were significant mechanisms forcing differences in community structure within the region.
Unsynchronised and synchronised vertical migration of zooplankton in a high Arctic fjord
Authors: Cottier Finlo R. , Tarling Geraint A. , Wold Anette , Falk-Petersen Stig
Published: July 2010

We measured vertical migration of zooplankton in an arctic fjord at 79°N between June and September 2002 and transcending a period of continuous illumination to one of true day and night to investigate the changing influence of light cues on behavior. Observations made with a moored 300 kHz acoustic Doppler current profiler indicated that two modes of vertical migration occurred during the study period. During the weeks of continuous illumination, backscatter data indicated that there was no net vertical displacement of the population at any time during the 24‐h period, but vertical velocity showed a continuous net downward movement in the surface layers and a net upward movement at depth. We interpreted this as unsynchronized vertical migrations by individuals with upward trajectories that slowed closer to the surface and downward trajectories that were most rapid in their initial phases. Synchronized migrations, seen as an upward and downward movement of scattering layers at dusk and dawn respectively, began once true nighttime resumed toward autumn. It is likely that the relative rate of change in light was used as the proximal cue for synchronized migrations. Concurrent net samples identified Calanus finmarchicus and C. glacialis as the most likely contributors to the unsynchronized migration patterns. The high backscatter of the synchronized scattering layers suggests that they included additional taxa such as the euphausiid Thysanoessa spp., the pteropod Limacina helicina, or the hyperiid amphipod Themisto spp.
Hydrodynamic control of the underwater light climate in fluvial Lac Saint‐Pierre
Authors: Frenette Jean-Jacques , Arts Michael T. , Morin Jean , Gratton Denis , Martin Carl
Published: July 2010

We measured characteristics of the underwater light spectra (e.g., attenuation of ultraviolet [UV] radiation, photosynthetically active radiation) and select dissolved and particulate physicochemical properties (e.g., chromophoric dissolved organic carbon [CDOM], dissolved and particulate organic carbon, inorganic dry weights, beam attenuation coefficients, particulate absorption coefficients, and nutrients) in different water masses of fluvial Lac Saint‐Pierre (Canada). We used these variables as tracers to reveal the extent and magnitude of spatial and temporal heterogeneity in this large, shallow, fluvial lake of the St. Lawrence River. We superimposed these tracer variables over radiance data obtained from satellite images to identify spatial and temporal changes in the distribution of different water masses and their bio‐optical components. The underwater light environment showed strong horizontal (longitudinal and lateral) variability because of the strong connectivity between the terrestrial and aquatic environments in the lake’s tributaries and adjoining wetlands. Analyzing the downstream distribution of optical and chemical variables as a function of transport time rather than distance from source tributaries allowed us to demonstrate large differences in the age of the different water masses depending on the characteristics of the source tributary, in‐stream processes, and distance from its source. CDOM explained most of the UV attenuation and allowed the greatest discrimination between water masses.
Photosynthesis and light utilization in the Caribbean coral Montastraea faveolata recovering from a bleaching event
Authors: Rodríguez-Román Aimé , Hernández-Pech Xavier , E. Thome Patricia , Enríquez Susana , Iglesias-Prieto Roberto
Published: July 2010

Coral bleaching—the loss of symbiotic dinoflagellates—is initiated when corals are exposed to sea surface temperatures above the regional summer average and has been responsible for massive coral mortality episodes. The ability of symbionts to recolonize the host after bleaching may be critical in determining if a colony will recover or experience mortality. Here, following the serendipitous bleaching of specimens of Montastraea faveolata of known photosynthetic, spectroscopic, and genetic characteristics, we describe changes in photosynthesis and light utilization during the recovery process. Fully recovered M. faveolata had minimum quantum requirements (1/Θmax) that are very close to the theoretical minimum, indicating that symbiotic corals are not only one of the most efficient light collectors in nature, but also use this energy with maximum efficiency. Analyses of the photosynthetic responses of M. faveolata throughout the recovery process indicate that during the early stages, the symbiont population exhibited characteristics consistent with acclimation to higher irradiance relative to fully recovered corals. The absorption spectra of bleached samples showed contributions of chlorophyll b (Chl b) associated with a biomass increase of the endolithic algae. The propagation of endolithic algae after bleaching may provide partial protection to the surviving symbionts from excessive radiation by reducing the reflectivity of the skeleton. Changes in the relative abundances of different symbiotic algae between recovered and unbleached colonies did not result in significant variations in photosynthetic and light utilization characteristics.
Primary production in two shallow lakes with contrasting plant form dominance: A paradox of enrichment?
Authors: Blindow I. , Hargeby A. , Meyercordt J. , Schubert H.
Published: July 2010

We estimated total lake plant biomass and primary net production in two shallow Swedish lakes that differ in nutrient loading and plant form dominance. In clearwater Lake Krankesjon (10 µg chlorophyll a L‐1), submerged macrophytes contributed more than phytoplankton and epiphyton to the estimated plant biomass. Estimated net primary production during May to September was 90‐130, 1.2, and 14 g C m‐2 for phytoplankton, epiphyton, and submerged macrophytes, respectively. In turbid Lake Bö rringesjön (60‐80 mg chlorophyll a L‐1), primary production by submerged macrophytes and periphyton was negligible. Although gross primary production of phytoplankton was high close to the water surface, estimated areal net primary production during May to September was low, ‐40 to +25 g C m‐2, as a result of self‐shading and high respiration. Grazing pressure from zooplankton rarely exceeded 15% d‐1 in both lakes, indicating that phytoplankton production was not limited by grazing. Low gross epiphyton production could result from high grazing by macroinvertebrates and thus higher trophic transfer efficiency through the benthic than through the pelagic food web. Provided that conditions in Lake Börringesjön reflect previous turbid state conditions in Lake Krankesjon, our results may explain why a shift to a clearwater state was followed by increased biomass of higher trophic levels. Our results also support the paradox of enrichment hypothesis, which predicts lower productivity at high nutrient loading. Contrary to former investigations, we found lower production at a higher nutrient loading already at the trophic level of primary producers.
Community photosynthesis of aquatic macrophytes
Authors: Binzer Thomas , Sand-Jensen Kaj , Middelboe Anne-Lise
Published: July 2010

We compared 190 photosynthesis‐irradiance (P‐E) experiments with single‐ and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P‐E relation in all communities and no sign of photosaturation or photoinhibition of photosynthesis at the highest irradiances of about 2,000 µmol m‐2 s‐1. Macrophyte communities displayed much higher maximum gross production (GPmax), respiration, and light compensation point than separate phytoelements because of the multilayered structure and extensive self‐shading in the communities, whereas light use efficiency at low irradiance (a) was the same. Although GPmax and a varied extensively among the 190 communities, their upper limits increased linearly and predictably with community absorption reaching 26.3 µmol m‐2 s‐1 O2 and 0.090 mol mol‐1 photon at 100% absorption. The upper limit of a is close to a realistic limit of O2 of 0.10 mol mol‐1 photon. The upper limit of GPmax, however, is markedly below the theoretically attainable 180 mol m‐2 s‐1 O2, reflecting a suboptimal three‐dimensional structure and light distribution. Indirect measures supported this explanation as GPmax increased fourfold from communities with a very uneven to a more even light distribution. Photosynthetic characteristics of communities are strongly influenced by plant density, absorption, and distribution of light and cannot be interpreted from the photosynthetic behavior of phytoelements. Thus, many examples of carbon and nutrient limitation in experiments with separate phytoelements may not withstand at the relevant ecological scale of communities where light almost always constrains photosynthetic production.
Twenty years of spatially coherent deepwater warming in lakes across Europe related to the North Atlantic Oscillation
Authors: Dokulil Martin T. , Jagsch Albert , George Glen D. , Anneville Orlane , Jankowski Thomas , Wahl Bernd , Lenhart Brigitte , Blenckner Thorsten , Teubner Katrin
Published: July 2010

Twenty to fifty years of annual mean deepwater (hypolimnetic) temperature data from twelve deep lakes spaced across Europe (2°95'W to 14°0'E, 46°27' to 59°00'N) show a high degree of coherence among lakes, particularly within geographic regions. Hypolimnetic temperatures vary between years but increased consistently in all lakes by about 0.1–0.2°C per decade. The observed increase was related to the weather generated by largescale climatic processes over the Atlantic. To be effective, the climatic signal from the North Atlantic Oscillation (NAO) must affect deep lakes in spring before the onset of thermal stratification. The most consistent predictor of hypolimnetic temperature is the mean NAO index for January–May (NAOJ–M), which explains 22–63% of the interannual variation in deepwater temperature in 10 of the 12 lakes. The two exceptions are remote, less wind‐exposed alpine valley lakes. In four of the deepest lakes, the climate signal fades with depth. The projected hypolimnetic temperature increase of approximately 1°C in 100 yr, obtained using a conservative approach, seems small. Effects on mixing conditions, thermal stability, or the replenishment of oxygen to deep waters result in accumulation of nutrients, which in turn will affect the trophic status and the food web.
Experimental d13C evidence for a contribution of methane to pelagic food webs in lakes
Authors: Kankaala Paula , Taipale Sami , Grey Jonathan , Sonninen Eloni , Arvola Lauri , Jones Roger I.
Published: July 2010

We tested the hypothesis that low stable carbon isotope (δ13C) values commonly observed for zooplankton in humic lakes are due to their feeding on isotopically light methane‐oxidizing microbes, and thus that methane‐derived carbon is important in the food webs of these lakes. In replicate laboratory cultures, Daphnia longispina, a common crustacean zooplankter in humic lakes, were fed microbial suspensions with or without enrichment by biogenic methane. The δ13C values of Daphnia indicated consumption of 13C‐depleted methanotrophic bacteria, while growth rates, survival, and reproduction of Daphnia in cultures enriched with methane were equal to or greater than those in nonenriched cultures. Results from lake enclosures during the autumn overturn period revealed a decrease in δ13C of adult Daphnia from ‐40.5% to ‐50.3%, reflecting extensive consumption of 13C‐depleted methanotrophic bacteria. Methane‐derived carbon is a more important contribution to carbon flux through lake pelagic food webs than has previously been suspected.
The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 2: Model sensitivity to the biomass burning inventories
Authors: Longo K. M. , Freitas S. R. , Andreae M. O. , Setzer A. , Prins E. , Artaxo P.
Published: July 2010

Abstract. We describe an estimation technique for biomass burning emissions in South America based on a combination of remote-sensing fire products and field observations, the Brazilian Biomass Burning Emission Model (3BEM). For each fire pixel detected by remote sensing, the mass of the emitted tracer is calculated based on field observations of fire properties related to the type of vegetation burning. The burnt area is estimated from the instantaneous fire size retrieved by remote sensing, when available, or from statistical properties of the burn scars. The sources are then spatially and temporally distributed and assimilated daily by the Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) in order to perform the prognosis of related tracer concentrations. Three other biomass burning inventories, including GFEDv2 and EDGAR, are simultaneously used to compare the emission strength in terms of the resultant tracer distribution. We also assess the effect of using the daily time resolution of fire emissions by including runs with monthly-averaged emissions. We evaluate the performance of the model using the different emission estimation techniques by comparing the model results with direct measurements of carbon monoxide both near-surface and airborne, as well as remote sensing derived products. The model results obtained using the 3BEM methodology of estimation introduced in this paper show relatively good agreement with the direct measurements and MOPITT data product, suggesting the reliability of the model at local to regional scales.
Chemistry of hydrogen oxide radicals (HOx) in the Arctic troposphere in spring
Authors: Mao J. , Jacob D. J. , Evans M. J. , Olson J. R. , Ren X. , Brune W. H. , Clair J. M. St. , Crounse J. D. , Spencer K. M. , Beaver M. R. , Wennberg P. O. , Cubison M. J. , Jimenez J. L. , Fried A. , Weibring P. , Walega J. G. , Hall S. R. , Weinheimer A. J. , Cohen R. C. , Chen G. , Crawford J. H. , McNaughton C. , Clarke A. D. , Jaeglé L. , Fisher J. A. , Yantosca R. M. , Le Sager P. , Carouge C.
Published: July 2010

Abstract. We use observations from the April 2008 NASA ARCTAS aircraft campaign to the North American Arctic, interpreted with a global 3-D chemical transport model (GEOS-Chem), to better understand the sources and cycling of hydrogen oxide radicals (HOx≡H+OH+peroxy radicals) and their reservoirs (HOy≡HOx+peroxides) in the springtime Arctic atmosphere. We find that a standard gas-phase chemical mechanism overestimates the observed HO2 and H2O2 concentrations. Computation of HOx and HOy gas-phase chemical budgets on the basis of the aircraft observations also indicates a large missing sink for both. We hypothesize that this could reflect HO2 uptake by aerosols, favored by low temperatures and relatively high aerosol loadings, through a mechanism that does not produce H2O2. We implemented such an uptake of HO2 by aerosol in the model using a standard reactive uptake coefficient parameterization with γ(HO2) values ranging from 0.02 at 275 K to 0.5 at 220 K. This successfully reproduces the concentrations and vertical distributions of the different HOx species and HOy reservoirs. HO2 uptake by aerosol is then a major HOx and HOy sink, decreasing mean OH and HO2 concentrations in the Arctic troposphere by 32% and 31% respectively. Better rate and product data for HO2 uptake by aerosol are needed to understand this role of aerosols in limiting the oxidizing power of the Arctic atmosphere.
A very high-resolution global fossil fuel CO2 emission inventory derived using a point source database and satellite observations of nighttime lights, 1980–2007
Authors: Oda T. , Maksyutov S.
Published: July 2010

Abstract. Emissions of CO2 from fossil fuel combustion are a critical quantity that must be accurately given in established flux inversion frameworks. Work with emerging satellite-based inversions requires spatiotemporally-detailed inventories that permit analysis of regional sources and sinks. Conventional approaches for disaggregating national emissions beyond the country and city levels based on population distribution have certain difficulties in their application. We developed a global 1 km×1 km fossil fuel CO2 emission inventory for the years 1980–2007 by combining a worldwide point source database and satellite observations of the global nightlight distribution. In addition to estimating the national emissions using global energy consumption statistics, emissions from point sources were estimated separately and were spatially allocated to exact locations indicated by the point source database. Emissions from other sources were distributed using a special nightlight dataset that had fewer saturated pixels compared with regular nightlight datasets. The resulting spatial distributions differed in several ways from those derived using conventional population-based approaches. Because of the inherent characteristics of the nightlight distribution, source regions corresponding to human settlements and land transportation were well articulated. Our distributions showed good agreement with a high-resolution inventory across the US at spatial resolutions that were adequate for regional flux inversions. The inventory will be incorporated into models for operational flux inversions that use observational data from the Japanese Greenhouse Gases Observing SATellite (GOSAT).
Effect of ocean acidification on the early life stages of the blue mussel Mytilus edulis
Authors: Gazeau F. , Gattuso J.-P. , Dawber C. , Pronker A. E. , Peene F. , Peene J. , Heip C. H. R. , Middelburg J. J.
Published: July 2010

Abstract. Several experiments have shown a decrease of growth and calcification of organisms at decreased pH levels. There is a growing interest to focus on early life stages that are believed to be more sensitive to environmental disturbances such as hypercapnia. Here, we present experimental data, acquired in a commercial hatchery, demonstrating that the growth of planktonic mussel (Mytilus edulis) larvae is significantly affected by a decrease of pH to a level expected for the end of the century. Even though there was no significant effect of a 0.25–0.34 pH unit decrease on hatching and mortality rates during the first 2 days of development nor during the following 13-day period prior to settlement, final shells were respectively 4.5±1.3 and 6.0±2.3% smaller at pHNBS~7.8 (pCO2~1100–1200 μatm) than at a control pHNBS of ~8.1 (pCO2~460–640 μatm). Moreover, a decrease of 12.0±5.4% of shell thickness was observed after 15d of development. More severe impacts were found with a decrease of ~0.5 pHNBS unit during the first 2 days of development which could be attributed to a decrease of calcification due to a slight undersaturation of seawater with respect to aragonite. Indeed, important effects on both hatching and D-veliger shell growth were found. Hatching rates were 24±4% lower while D-veliger shells were 12.7±0.9% smaller at pHNBS~7.6 (pCO2~1900 μatm) than at a control pHNBS of ~8.1 (pCO2~540 μatm). Although these results show that blue mussel larvae are still able to develop a shell in seawater undersaturated with respect to aragonite, the observed decreases of hatching rates and shell growth could lead to a significant decrease of the settlement success. As the environmental conditions considered in this study do not necessarily reflect the natural conditions experienced by this species at the time of spawning, future studies will need to consider the whole larval cycle (from fertilization to settlement) under environmentally relevant conditions in order to investigate the potential ecological and economical losses of a decrease of this species fitness in the field.
The most oligotrophic subtropical zones of the global ocean: similarities and differences in terms of chlorophyll and yellow substance
Authors: Morel A. , Claustre H. , Gentili B.
Published: July 2010

Abstract. The cores of the subtropical anticyclonic gyres are characterized by their oligotrophic status and minimal chlorophyll concentration, compared to that of the whole ocean. These zones are unambiguously detected by space borne ocean color sensors thanks to their typical spectral reflectance, which is that of extremely clear and deep blue waters. Not only the low chlorophyll (denoted [Chl]) level, but also a reduced amount of colored dissolved organic matter (CDOM or "yellow substance") account for this clarity. The oligotrophic waters of the North and South Pacific gyres, the North and South Atlantic gyres, and the South Indian gyre have been comparatively studied with respect to both [Chl] and CDOM contents, by using 10-year data (1998–2007) of the Sea-viewing Wide field-of-view Sensor (SeaWiFS, NASA). Albeit similar these oligotrophic zones are not identical regarding their [Chl] and CDOM contents, as well as their seasonal cycles. According to the zone, the averaged [Chl] value varies from 0.026 to 0.059 mg m−3, whereas the ay(443) average (the absorption coefficient due to CDOM at 443 nm) is comprised between 0.0033 and 0.0072 m−1. The CDOM-to-[Chl] relative proportions also differ between the zones. The clearest waters, corresponding to the lowest [Chl] and CDOM concentrations, are found near Easter Island and near Mariana Islands in the western part of the North Pacific Ocean. In spite of its low [Chl], the Sargasso Sea presents the highest CDOM content amongst the six zones studied. Except in the North Pacific gyre (near Mariana and south of Hawaii islands), a conspicuous seasonality appears to be the rule in the other 4 gyres and affects both [Chl] and CDOM; both quantities vary in a ratio of about 2 (maximum-to-minimum). Coinciding [Chl] and CDOM peaks occur just after the local winter solstice, which is also the period of the maximal mixed layer depth in these latitudes. It is hypothesized that the vertical transport of unbleached CDOM from the subthermocline layers is the main process enhancing the CDOM concentration within the upper layer in winter. In summer, the CDOM experiences its minimum which is delayed with respect to the [Chl] minimum; apparently, the solar photo-bleaching of CDOM is a slower process than the post-bloom algal Chl decay. Where they exist, the seasonal cycles are repeated without notable change from year to year; long term (10 years) trends have not been detected in these zones. These oligotrophic gyres can conveniently be used for in-flight calibration and comparison of ocean color sensors, provided that their marked seasonal variations are accounted for.
Long-term atmospheric nutrient inputs to the Eastern Mediterranean: sources, solubility and comparison with riverine inputs
Authors: Koçak M. , Kubilay N. , Tuğrul S. , Mihalopoulos N.
Published: July 2010

Abstract. Aerosol and rain samples were collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas) draining into the Northeastern Levantine Basin (NLB) between March 2002 and July 2007. Samples were analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43−, Sidiss, NO3− and NH4+). Phosphate and silicate in aerosol and rainwater showed higher and larger variation during the transitional period (March–May, September) when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material were found to be the main reason of the acidic rain events whilst high pH values (>7) were associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater were associated with air flow from the Mediterranean Sea. Unlike NO3− and NH4+ (Dissolved Inorganic Nitrogen, DIN), there were statistical differences for PO43− and Sidiss solubilities in sea-water and pure-water. Solubilities of PO43− and Sidiss were found to be related with air mass back trajectories and pH. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43− fluxes to NLB were dominated by atmosphere (~90% and ~60% respectively) whereas the input of Si was mainly derived from riverine runoff (~90%). N/P ratios (atmosphere ~233; riverine ~28) revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Molar Si/N ratios (atmosphere + riverine) suggested Si limitation which might cause a switch from diatom dominated phytoplankton communities to non-siliceous populations in NLB.
The role of climatic and terrain attributes in estimating baseflow recession in tropical catchments
Authors: Peña-Arancibia J. L. , van Dijk A. I. J. M. , Mulligan M. , Bruijnzeel L. A.
Published: July 2010

Abstract. The understanding of low flows in rivers is paramount more than ever as demand for water increases on a global scale. At the same time, limited streamflow data to investigate this phenomenon, particularly in the tropics, makes the provision of accurate estimations in ungauged areas an ongoing research need. This paper analysed the potential of climatic and terrain attributes of 167 tropical and sub-tropical unregulated catchments to predict baseflow recession rates. Climatic attributes included annual and seasonal indicators of rainfall and potential evapotranspiration. Terrain attributes included indicators of catchment shape, morphology, land cover, soils and geology. Stepwise regression was used to identify the best predictors for baseflow recession coefficients (kbf). Mean annual rainfall (MAR) and aridity index (AI) were found to explain 49% of the spatial variation of kbf. The rest of climatic indices plus average catchment slope (SLO) and tree cover were also good predictors, but co-correlated with MAR. Catchment elongation (CE), a measure of catchment shape, was also found to be statistically significant, although weakly correlated. An analysis of clusters of catchments of smaller size, showed that in these areas, presumably with some similarity of soils and geology due to proximity, residuals of the regression could be explained by SLO and CE. The approach used provides a~potential alternative for kbf parameterisation in ungauged areas.
Anthropogenic carbon dynamics in the changing ocean
Authors: Tjiputra J. F. , Assmann K. , Heinze C.
Published: July 2010

Abstract. The long-term response of CO2 fluxes to climate change at the ocean surface and within the ocean interior is investigated using a coupled climate-carbon cycle model. This study also presents the first attempt to quantify the evolution of lateral transport of anthropogenic carbon under future climate change. Additionally, its impact on regional carbon storage and uptake is also evaluated. For the 1850–2099 period, our climate change simulation predicts oceanic uptake of anthropogenic carbon of about 538±23 Pg C. Another simulation indicates that changes in physical climate and its associated biogeochemical feedbacks result in a release of natural carbon of about 22±30 Pg C. The natural carbon outgassing is attributed to the reduction in solubility and change in wind pattern in the Southern Hemisphere. After the anthropogenic carbon passes through the air-sea interface, it is predominantly transported along the large scale overturning circulation below the surface layer. The spatial variations in the transport patterns in turn influence the evolution of future regional carbon uptake. In the North Atlantic, a slow down in the Atlantic Meridional Overturning Circulation weakens the penetration strength of anthropogenic carbon into the deeper ocean, which leads to a reduced uptake rate in this region. In contrast, more than half of the anthropogenic carbon taken up in the high latitude Southern Ocean region (south of 58° S) is efficiently and continuously exported northward, predominantly into intermediate waters. This transport mechanism allows continuous increase in future carbon uptake in the high latitude Southern Ocean, where the annual uptake strength could reach 39.3±0.9 g C m−2 yr−1, more than twice the global mean of 16.0±0.3 g C m−2 yr−1 by the end of the 21st century. Our study further underlines the key role of the Southern Ocean in controlling long-term future carbon uptake.
Technical Note: A low cost unmanned aerial vehicle for ship based science missions
Authors: Waugh E. , Mowlem M.
Published: July 2010

Abstract. A low-cost Unmanned Aerial Vehicle is compared with those already available and the motivation for its development is established. It is targeted at ship-based science missions and potential applications are described including a specific science case to measure white capping in the deep ocean. The current vehicle includes a range of more than 1000 Km, carrying a payload of 2 Kg and it can be launched and recovered from a coastal research vessel. The vehicle has flown successfully in Force 4 gusting Force 6–7 wind conditions, an important requirement for operation at sea. Data analysis is performed on images captured by the vehicle to provide a measurement of wave period and white capping fraction. The next stage of the project is to develop a suitable payload and perform a demonstration science mission.
Synthesis and characterization of PNIPAM/PS core/shell particles
Authors: Zhang Li , Daniels Eric S. , Dimonie Victoria L. , Klein Andrew
Published: June 2010

Crosslinked, monodisperse PNIPAM particles were synthesized by precipitation polymerization. The particle size was measured by dynamic light scattering (DLS), capillary hydrodynamic fractionation (CHDF), and transmission electron microscopy (TEM). Two different polymerization methods were used to prepare PNIPAM/PS core/shell particles, both above and below the volume phase transition temperature (VPPT) using either a semibatch or seeded semibatch polymerization process. In both processes, uniform “raspberry” structures were obtained in which polystyrene formed small domains on the surface of the PNIPAM particles. The resulting core and shell structure was confirmed by temperature‐dependent particle size and density gradient experiments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Flocculation performance of modified chitosan in an aqueous suspension
Authors: Ali Sk Akbar , Pal Sagar , Singh Ram Prakash
Published: June 2010

A cationic moiety, N‐(3‐chloro‐2‐hydroxypropyl)trimethyl ammonium chloride (CHPTAC), was incorporated onto chitosan in an aqueous alkaline solution. Thus, modified chitosan was prepared. A series of modified chitosans with different molecular weights and charge densities were synthesized through the alteration of the molar ratio of CHPTAC to chitosan in the reaction mixture. The synthesized modified chitosans were thereafter characterized by a variety of physicochemical characterization techniques to confirm that modification did take place. Furthermore, the feasibility of applying modified chitosans as flocculants was assessed, and they were compared with the native chitosan in model colloidal suspensions of kaolin and iron‐ore powder. The results indicated that the unmodified chitosan itself was a good flocculating agent. The flocculation performance of the chitosan could be altered by the incorporation of the CHPTAC moiety. Studies showed that not all the modified chitosans had superior flocculation performance versus the native chitosan. Among the different grades, the modified chitosan with a moderate molecular weight and a moderate charge density showed the best flocculation performance in both model suspensions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Conservation genetics of the endangered depressed river mussel, Pseudanodonta complanata, using amplified fragment length polymorphism (AFLP) markers
Authors: Skidmore Richard , Leach Christopher , Hoffman Joe , Amos William , Aldridge David
Published: June 2010

Genetic analysis is increasingly recognized as a key tool for understanding demography, and is particularly useful for describing patterns of gene flow between putative populations. Most effort has been directed towards vertebrate systems, where any one study often benefits from marker development in related species. The greater diversity of invertebrate taxa presents a challenge, but amplified fragment length polymorphism (AFLP) markers offer a solution, yielding high levels of polymorphism and no prior knowledge of a species' genome.

AFLP markers have been used to analyse an unusual metapopulation of an invertebrate, the endangered freshwater mussel, Pseudanodonta complanata, sampled from river systems across the UK. This was done to assess the extent to which individual river systems were genetically isolated from one another.

The results show patterns of weak genetic differentiation across the UK, with one hydrologically isolated population in the south west showing clear genetic differentiation from the rest of the country. However, the UK population as a whole exhibits significant isolation by distance, particularly when one population subject to fish stocking is removed, this population probably being seeded with mussel glochidia larvae which use fish as vectors. Genetic estimates of inbreeding reveal a complicated pattern in which inbreeding peaks at intermediate densities. High‐density populations may be genetically diverse due to their size, while the lowest density populations may represent transient groups of emigrants from other, larger populations.

The findings show that limited gene flow does exist between some but not all river systems. The isolation of the south‐west population indicates that dispersal is variable and should not be assumed to be present. Waterways that remain hydrologically isolated may require special attention in conservation programmes as they can harbour genetically distinct populations. The balance between river management activities and conservation priorities therefore needs careful consideration. Copyright © 2010 John Wiley & Sons, Ltd.
Design and use of peptide‐based antibodies decreasing superoxide production by mitochondrial complex I and complex II
Authors: Kang Patrick T. , Yun June , Kaumaya Pravin P. T. , Chen Yeong‐Renn
Published: June 2010

Mitochondria are the major source of reactive oxygen species. Both complex I and complex II mediate O production in mitochondria and host reactive protein thiols. To explore the functions of the specific domains involved in the redox modifications of complexes I and II, various peptide‐based antibodies were generated against these complexes, and their inhibitory effects were subsequently measured. The redox domains involved in S‐glutathionylation and nitration, as well as the binding motif of the iron–sulfur cluster (N1a) of the complexes I and II were utilized to design B‐cell epitopes for generating antibodies. The effect of antibody binding on enzyme‐mediated O generation was measured by EPR spin trapping. Binding of either antibody AbGSCA206 or AbGSCB367 against glutathione (GS)‐binding domain to complex I inhibit its O generation, but does not affect electron transfer efficiency. Binding of antibody (Ab24N1a) against the binding motif of N1a to complex I modestly suppresses both O generation and electron transfer efficiency. Binding of either antibody Ab75 or Ab24 against nonredox domain decreases electron leakage for O production. In complex II, binding of antibody AbGSC90 against GS‐binding domain to complex II marginally decreases both O generation and electron transfer activity. Binding of antibody AbY142 to complex II against the nitrated domain modestly inhibits electron leakage, but does not affect the electron transfer activity of complex II. In conclusion, mediation of O generation by complexes I and II can be regulated by specific redox and nonredox domains. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 207–221, 2011.
Preparation of connexin43‐integrated giant Liposomes by a baculovirus expression–liposome fusion method
Authors: Kamiya Koki , Tsumoto Kanta , Arakawa Satoko , Shimizu Shigeomi , Morita Ikuo , Yoshimura Tetsuro , Akiyoshi Kazunari
Published: June 2010

Connexin‐43 (Cx43) containing giant liposomes (GL) were prepared by a baculovirus expression–liposome fusion method. Recombinant budded viruses expressing Cx43 were prepared and then fused with GLs containing DOPG/DOPC at pH 4.5. Connexon formation on the GL membrane was observed by transmission electron microscope. Hydrophilic fluorescent dye transfers were observed through a Cx43‐mediated pathway not only between Sf9 (Spodoptera frugiperda) cells with Cx43 but also from giant Cx43 liposomes to Cx43‐expressing U2OS cells (human osteosarcoma cell). The functional connexin‐containing liposome is expected to be useful for cellular cytosolic delivery systems. The original orientation and function of Cx43 was maintained after integration into the liposomes. The liposome fusion method will create new opportunities as a tool for analysis of channel membrane proteins. Biotechnol. Bioeng. 2010;107: 836–843. © 2010 Wiley Periodicals, Inc.