487 research outputs found

    Leidraad beheersing eikenprocessierups

    Get PDF
    De beheersing van de eikenprocessierups is geen eenvoudige opgave. Het blijkt in de praktijk niet eenvoudig een juiste mix te vinden tussen het voorkómen van gezondheidsklachten, het vermijden van ongewenste ecologische effecten en het opzetten van een adequate monitoring en bestrijding van deze plaag. Met deze leidraad worden voor de professionele beheerders bouwstenen aangereikt om goede beheerkeuzen te maken. De huidige versie van de Leidraad is in voorjaar 2008 door een afvaardiging van de Expertgroep Eikenprocessierups geactualiseerd op basis van nieuwe inzichten en praktijkervaringe

    Compositional data analysis as a potential tool to study the (paleo)ecology of calcareous nannoplankton from the central portuguese submarine canyons (W off Portugal)

    Get PDF
    Submarine canyons are deep and steep incisions on the continental margins. The physical forcing mechanisms linked with these marine systems, such as the enhancement of upwelling and bottom sediment resuspension, are expected to provide a nutrient source that will increase phytoplankton density (Hickey, 1995, Kampf,2006). Coccolithophores are the predominant phytoplanktonic group within the calcareous nannoplankton and their sensitivity to a variety of surface water environmental parameters makes them important markers of oceanographic processes and proxies of sea surface water masses and temperatures, productivity and past climate changes (e.g. Ziveri et al., 2004; Silva et al., 2008). In the present work we propose to test compositional analysis (Buccianti & Esposito, 2004; Pawlowsky-Glahn & Egozcue, 2006) as a tool to: a) achieve a clearer distinction between opportunistic coastal-neritic species (r-strategists) and typical oceanic species (k-strategists) in the central Portuguese margin, and b) to identify a coccolith assemblage that might reflect favorable environmental conditions found in the vicinity of the canyon that promotes the productivity of calcareous nannoplankton. Our main difficulty will be in distinguishing the ecological signal from the effects of other environmental factors mentioned before (i.e. advection, dissolution, bottom resuspension). One way to infer the species’ ecological inter-relationships is by determining species relative percentages. The main concern is how the closure problem and the inconsistency of percentage determinations will affect our results. Compositional analysis was designed to provide more reliable and thus representative results, since the inference made on the coccolith assemblage features from which the data are drawn is correctly performed from a theoretical point of view (Buccianti & Esposito, 2004). Here, we present the first insights from applying compositional data analysis to coccolith assemblages from 85 surface sediment samples collected from the central Portuguese margin

    Fetal Urine Production in Late Pregnancy

    Get PDF
    Objective. Hourly fetal urine production rate (HFUPR) was studied in relation to both gestational age and the onset of spontaneous labor in normal term human pregnancies. Methods. Serial volume measurements were obtained from longitudinal ultrasound images of the fetal bladder at 1–5-minute intervals, and HFUPR was subsequently calculated. A total of 178 adequate bladder-filling cycles were recorded in 112 women, and the amniotic fluid index (AFI) was assessed. Results. HFUPR did not change significantly between 37 and 42 weeks' gestation. However, HFUPR decreased during the last 14 days prior to the onset of spontaneous labor (P < 0.005). No significant correlation was found between HFUPR and AFI, neither when measured at the same time nor when HFUPR and AFI were measured at various intervals in time. Conclusion. HFUPR falls before and in relation to the time of onset of labor rather than in relation to gestational age

    Structure and development of carbonate mounds along the NE Atlantic margin

    Get PDF
    Giant carbonate mounds between 500-1200 m water depth along both the SE and SW margins of Rockall Trough rise 5 to 300 m above the surrounding seafloor and have diameters at their basis of up to 5 km. Buried mounds, at relatively shallow depth below the seafloor are also found. Both individual and complex clusters of mounds can be recognized. Smaller and individual, sometimes buried mounds are found at the upper slope. On the SW Rockall Trough margin, higher, steeper and individual mounds are found deeper downslope (900-1100 m). At the middle slope the mounds merge into a complex structure and form complex clusters with a very irregular upper surface and an apparent lack of internal reflectors (600-1000 m depth). These clusters are oriented perpendicular and slightly oblique to the prevailing bathymetry, and show on TOBI profiles as linear ridges. Further results of the TOBI survey in summer 2002 show that the distribution of mounds along the flanks of SW Rockall Trough is considerably more widespread than previously considered, and also that the mounds appear to form constructional elements on a large plateau. Erosional channels between mounds identify the strong interaction between mound shape and strong bottom currents along the slopes of mounds. On the upper flank the mounds are delineated by a field of large gravelly sediment waves of 500m wavelength oriented parallel to the margin in the central part and more curved to the north. On their lower flank slide scars do locally occur

    Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust

    Get PDF
    Coccolithophores are calcifying phytoplankton and major contributors to both the organic and inorganic oceanic carbon pumps. Their export fluxes, species composition, and seasonal patterns were determined in two sediment trap moorings (M4 at 12 degrees N, 49 degrees W and M2 at 14 degrees N, 37 degrees W) collecting settling particles synchronously from October 2012 to November 2013 at 1200 m of water depth in the open equatorial North Atlantic. The two trap locations showed a similar seasonal pattern in total coccolith export fluxes and a predominantly tropical coccolithophore settling assemblage. Species fluxes were dominated throughout the year by lower photic zone (LPZ) taxa (Florisphaera profunda, Gladiolithus flabellatus) but also included upper photic zone (UPZ) taxa (Umbellosphaera spp., Rhabdosphaera spp., Umbilicosphaera spp., Helicosphaera spp.). The LPZ flora was most abundant during fall 2012, whereas the UPZ flora was more important during summer. In spite of these similarities, the western part of the study area produced persistently higher fluxes, averaging 241 x 10(7) +/- 76 x 10(7) coccoliths m(-2) d(-1) at station M4 compared to only 66 x 10(7) +/- 31 x 10(7) coccoliths m(-2) d(-1) at station M2. Higher fluxes at M4 were mainly produced by the LPZ species, favoured by the westward deepening of the thermocline and nutricline. Still, most UPZ species also contributed to higher fluxes, reflecting enhanced productivity in the western equatorial North Atlantic. Such was the case of two marked flux peaks of the more opportunistic species Gephyrocapsa muellerae and Emiliania huxleyi in January and April 2013 at M4, indicating a fast response to the nutrient enrichment of the UPZ, probably by wind-forced mixing. Later, increased fluxes of G. oceanica and E. huxleyi in October-November 2013 coincided with the occurrence of Amazon-River-affected surface waters. Since the spring and fall events of 2013 were also accompanied by two dust flux peaks, we propose a scenario in which atmospheric dust also provided fertilizing nutrients to this area. Enhanced surface buoyancy associated with the river plume indicates that the Amazon acted not only as a nutrient source, but also as a surface density retainer for nutrients supplied from the atmosphere. Nevertheless, lower total coccolith fluxes during these events compared to the maxima recorded in November 2012 and July 2013 indicate that transient productivity by opportunistic species was less important than "background" tropical productivity in the equatorial North Atlantic. This study illustrates how two apparently similar sites in the tropical open ocean actually differ greatly in ecological and oceanographic terms. The results presented here provide valuable insights into the processes governing the ecological dynamics and the downward export of coccolithophores in the tropical North Atlantic.Netherlands Organization for Scientific Research (NWO) [822.01.008]; European Research Council (ERC) [311152]; University of Bremen; European Union [600411]info:eu-repo/semantics/publishedVersio

    Seasonal carbon cycling in a Greenlandic fjord: an integrated pelagic and benthic study

    Get PDF
    Climate change is expected to have a pronounced effect on biogeochemical cycling in Arctic fjords, but current insight on the biogeochemical functioning of these systems is limited. Here, we present seasonal data on primary production, export of particulate organic carbon (POC), and the coupling to benthic biogeochemistry in Kobbefjord (SW Greenland). Primary production and associated POC export from the photic zone showed marked seasonality, with annual integrated values of 7.2 and 19.9 mol C m-2 yr-1, respectively. This discrepancy, the isotopic signature, and C:N ratio of the sedimentating material suggested substantial import of marine POC from outside the fjord. At least 52% of the POC export reached the sediment, but the seasonality in pelagic productivity was not reflected in the sediment biogeochemistry, showing only moderate variation. Benthic mineralization and burial of organic carbon amounted to 3.2 and 5.3 mol C m-2 yr-1, respectively. Sulfate reduction was the most prominent mineralization pathway, accounting for 69% of the benthic mineralization, while denitrification accounted for 2%. Overall, the carbon mineralization and burial in Kobbefjord were significantly higher than previously observed in other more northerly Arctic fjords. Data compilation from Arctic fjords suggests proportional increases in surface production, POC export, benthic mineralization and burial of organic material with increasing duration of the ice-free period. Thus, the projected decline in ice coverage in higher Arctic Greenlandic fjords will, as a first approximation, entail proportional increases in productivity, mineralization, and burial of organic carbon in the fjords, which will thus become similar to present-day southerly systems

    Influence of diagenetic processes and terrestrial/anthropogenic sources in the REE contents of the Cascais submarine canyon (Iberian western coast)

    Get PDF
    ABSTRACT: Temporal variations of rare earth elements (REE) and their fractionation patterns, major elements, Pb and Hg were determined in two multicores collected at 445 and 2100 m water depth (mwd) in the Cascais submarine canyon (CSC). The PAAS-normalized REE patterns suggest mixing of Tagus estuarine and marine sediments, marked by MREE (Nd‐Dy series) enrichment and by positive Eu-anomaly, with marine sediments. The positive Eu/Eu* implies incorporation of detrital feldspar minerals derived from the estuary. Ce/Ce*, (La/Yb)PAAS and (Nd/Yb)PAAS show differences between the two cores. Core 252-35 from the shallower site is enriched in HREE (Ho‐Lu series) over LREE (La‐Pr series), a pattern also found in the Tagus estuary in the vicinity of an abandoned chemical complex, where the environment is affected by the legacy of massive-sulfide ores processing. There seems to be only limited down-canyon sediment transport to the deeper reaches where core 252-32 was collected. This deeper site shows Ce/Ce* peaks coinciding with low (La/Yb)PAAS values suggesting preferential diagenetic remobilization of LREE relative to HREE. Upcore Pb/Al and Hg/Corg trends observed in both cores indicate dispersion of the anthropogenic component from the estuary through the CSC, which is less obvious from the ∑REE/Al trends particularly in the deeper site. This may suggest the influence of diagenetic processes in the REE signal, associated with relatively low sediment accumulation rates.info:eu-repo/semantics/publishedVersio

    Detecting host-parasitoid interactions in an invasive Lepidopteran using nested tagging DNA metabarcoding

    Get PDF
    Determining the host-parasitoid interactions and parasitism rates for invasive species entering novel environments is an important first step in assessing potential routes for biocontrol and integrated pest management. Conventional insect rearing techniques followed by taxonomic identification are widely used to obtain such data, but this can be time consuming and prone to biases. Here we present a Next Generation Sequencing approach for use in ecological studies which allows for individual level metadata tracking of large numbers of invertebrate samples through the use of hierarchically organised molecular identification tags. We demonstrate its utility using a sample data set examining both species identity and levels of parasitism in late larval stages of the Oak Processionary Moth (Thaumetopoea processionea - Linn. 1758), an invasive species recently established in the UK. Overall we find that there are two main species exploiting the late larval stages of Oak Processionary Moth in the UK with the main parasitoid (Carcelia iliaca - Ratzeburg, 1840) parasitising 45.7% of caterpillars, while a rare secondary parasitoid (Compsilura conccinata - Meigen, 1824) was also detected in 0.4% of caterpillars. Using this approach on all life stages of the Oak Processionary Moth may demonstrate additional parasitoid diversity. We discuss the wider potential of nested tagging DNA-metabarcoding for constructing large, highly-resolved species interaction networks

    Foraminiferal biodiversity associated with cold-water coral carbonate mounds and open slope of SE Rockall Bank (Irish continental margin-NE Atlantic)

    Get PDF
    Cold-water coral (CWC) ecosystems are hotspots of macro- and microfaunal biodiversity and provide refuge for a wide variety of deep-sea species. We investigated how the abundance and biodiversity of 'live' (Rose Bengal stained) foraminifera varies with, and is related to, the occurrence of CWC on the Rockall Bank (NE Atlantic). Qualitative and quantitative analyses were performed on 21 replicate samples from 8 deep-sea stations, including 4 stations on CWC-covered carbonate mounds at depths of 567-657 m, and 4 stations on the adjacent slope at depths of 469-1958 m where CWC were absent. This sampling strategy enabled us to demonstrate that sediments surrounding the living CWC were characterised by higher foraminiferal abundance and biodiversity than open-slope sediments from the same area. A total of 163 foraminiferal species was identified. The dominant species in CWC sediments were: Spirillina vivipara, Allogromiid sp. 1. Globocassidulina subglobosa, Adercotryma wrighti, Eponides pusillus, Ehrenbergina carinata, Planulina ariminensis, Trochammina inflate and Paratrochammina challenged. Foraminifera were nearly absent in adjacent open slope areas subject to strong tidal currents and characterised by coarse grained deposits. We suggest that CWC create a heterogeneous three-dimensional substrate offering microhabitats to a diverse benthic foraminiferal community
    corecore