Spatial and interspecies variability of mercury accumulation in small cetaceans

Poster (2000, April)

Spatial and temporal (30 yr.) variations of lead geochemical signature in a macrotidal highly polluted estuary

in Geochimica et Cosmochimica Acta (2007, August), 71(15, Suppl. S), 993-993

Spatial and temporal patterns of nutrient distributions in the Ross Sea

in Faranda, Francesco; Guglielmo, Lillo; Ianora, Adriana (Eds.) Ross Sea Ecology - ITALIANTARTIDE Expeditions (1987-1995) (1999)

See pdf file in attachment

Spatial and temporal responses of marine gastropods and biofilms to urban wastewater pollution in a Mediterranean coastal area

Doctoral thesis (2012)

The increasing human pressure exerted along coastlines and the subsequent increase in the delivery of pollutants at sea is a matter of concern worldwide. Urban wastewaters contain a variety of pollutants ... [more ▼]

The increasing human pressure exerted along coastlines and the subsequent increase in the delivery of pollutants at sea is a matter of concern worldwide. Urban wastewaters contain a variety of pollutants (mainly N, P, and trace elements) which can be involved in the launching of eutrophication. This complex process is able to fundamentally alter the integrity of coastal ecosystems thereby impairing the sustainability of economic activities and involving health risks for human through the consumption of sea products. Eutrophication is considered for more than 40 years as a pervasive process and a priority issue for the preservation of the health status of coastal ecosystems. The Mediterranean Sea supports high economic pressures in relation with the continuously increasing number of inhabitants and tourists in coastal areas. The physico-chemical (e.g. oligotrophy, microtidal regime) features of waters make them sensitive to eutrophication and several heavily urbanized areas have been experiencing adverse effects of this process for decades (e.g. biodiversity losses, Harmful Algal Blooms, fishes’ kills,…etc). Nowadays, smaller localities discharging insufficiently treated or raw wastewaters at sea also begin to report eutrophication problems especially during summer months when the number of tourists considerably increases the resident populations. National monitoring programs generally focus on priority areas by using either toxicological (e.g. trace metals in molluscs) and / or structural (e.g. phytoplankton biomasses) parameters to follow the evolution of already impacted water bodies. However, if the most deleterious effects of eutrophication are well known, little information is actually available regarding the early symptoms of the process. The identification of time- and cost-efficient indicators along with analytical procedures that would deliver early warning signals of pollution is therefore required to assist local authorities in the implementation of environmental policies. This research aimed at implementing some easy-to-use and efficient tools to detect the impact of urban wastewater pollution in Mediterranean coastal areas. A new set of potential early bioindicators has been identified. The gastropods Patella caerulea and Monodonta turbinata inhabiting the Mediterranean rocky midlittoral zone and epilithic biofilms were selected as good candidates for monitoring purpose. Biofilms which are microbenthic communities mainly composed of microalgae have been used for decades in freshwater systems as early indicators of pollution. In contrast, marine biofilms have largely been neglected and little is known regarding their composition, their physiology, and the way they react to wastewater pollution. We focused our studies on the Calvi Bay (NW Mediterranean, France) which is, regarding the anthropogenic pressure exerted on its coastal fringe, representative of other moderately urbanized areas of the Mediterranean basin. The Calvi Bay area is indeed among the preferred summer destinations by tourists in Corsica and is influenced by a single point source of pollution which is secondary-treated urban wastewater. A control vs. impacted sites approach has been used to assess the responses of the selected bioindicators to wastewater pollution. Our first task was to characterize the nature and amounts of the main pollutants (nutrients, trace elements) discharged in the Calvi Bay. Since nutrient measurements are commonly used to infer into the trophic status of water bodies, we assessed whether this parameter was reliable to detect the influence of wastewater discharge in the study area. The main pollutants discharged at sea were ammonium, phosphorus and iron. Amounts considerably increased during summer months (July and August) which was related to the high frequentation of the Calvi Bay area by tourists. Measurements of nutrient concentrations in seawater samples from controls and impacted sites did not allow evidencing the influence of wastewater inputs. In contrast, the high spatial and temporal resolution achieved through a small scale sampling design conducted in a small harbour impacted by wastewater discharges showed large spatial variability in the dispersion of effluents and hourly variations in the amounts of pollutants. The extrapolation of these results at the scale of the Calvi Bay may have explained our failure to detect the pollution by using samples collected punctually in space and time. These results suggested that the use of bioindicators that integrate the variable influence of nutrient pulses was required to evidence pollution. We focused our second study on a toxicological approach to detect the bioavailability of anthropogenically-derived nutrients in the midlittoral zone of the Calvi Bay and of the Marseille harbour. Multi-spatial scales and seasonal dual C and N stable isotope analyses were performed on the limpet Patella caerulea, the snail Monodonta turbinata, epilithic biofilms, and the macroalga Rissoella verruculosa. All bioindicators exhibited strongly elevated δ15N values at impacted sites compared to pristine ones, which revealed the influence of wastewater pollution in the midlittoral zone and the biological availability of anthropogenically-derived nitrogen at the base of the food web. Gastropods provided a time-integrated response reflecting the control vs. impacted status of sites. Results indicated that one sampling campaign per year should be sufficient to evidence wastewater pollution likely because of the slow turnover rate of gastropods’ muscles. Macroalgae showed a reliable but less consistent signal of wastewater pollution compared to other indicators. Only epilithic biofilms tended to show the occurrence of nutrient pulses during the tourist season which suggested that wastewater discharges may have influenced the composition and / or the physiology of communities. However the sampling of biofilms developed on natural rocky substrates was destructive and did not allow investigating the fine biological structure of communities and thus to fully understand the output of community scale parameters such as stable isotopes. We therefore recommended using biofilms grown on artificial substrates to circumvent this problem. We then allowed biofilms to develop on glass slides which are the most currently used artificial substrates in freshwater systems. Our task was to find out the most suitable technique to isolate and identify benthic diatoms which are common colonizers on newly available substrates. The species-specific tolerance to pollution of diatoms has been used for decades in the assessment of the health status of freshwater bodies. However, little is known on their marine counterparts and on their ability to evidence wastewater pollution. A specific and time-cost-efficient technique was implemented for the processing of lightly silicified benthic marine diatoms from Mediterranean oligotrophic areas. This was achieved through the multiple comparisons of existing protocols used either in sea- or fresh-waters. We finally investigated, by means of mesocosm deployed in situ and field experiments, the responses of biofilms developed on glass slides to a range of urban wastewater exposures. Colonization experiments lasted for 24 days in summer conditions. A multi-parametric assessment was conducted using a combination of toxicological and structural approaches applied to different biological scales. Toxicological parameters such as C-N stable isotopes, C:N:P ratios, and Trace Elements were measured at the community scale while the structural parameters were considered at the community (standing crops), assemblage (densities of the main autotroph and heterotroph organisms), and the genus (diatoms) scales. The mesocosm experiments were highly efficient to demonstrate the good potential of biofilms as early indicators of wastewater pollution. The impact of wastewater pollution was mainly identified at the community and the genus (diatoms) scales. Standing crops and the C-N stable isotopes were the most useful parameters showing respectively a stimulation of microalgal biomasses (i.e. eutrophication) and the bioavailability of wastewater-derived nitrogen even at low pollution levels. At the genus scale, the composition of diatoms’ assemblages changed markedly especially in the most polluted mesocosms. Results notably highlighted the proliferation of the small-sized individuals of Entomoneis which was thought to outcompete the larger diatoms belonging to the genus Mastogloia for nutrient uptake. The responses of biofilms to pollution largely differed between mesocosm and field experiments. Nevertheless, standing crop parameters corroborated results obtained in mesocosms allowing to assume an influence of wastewater pollution in the Calvi Bay. Field samples were generally characterized by the presence of well developed hydrozoan colonies which were only seldom reported at mesocosm sites. The presumably impacted site also exhibited the highest densities in other heterotrophic eukaryote groups (e.g. nematodes, polychaetes, foraminifers) and primary producers. We interpreted these results either as a top-down effect or as an increase in habitat complexity. The genus scale determination of diatoms’ assemblages showed a decrease in the relative abundances of Mastogloia at the impacted site which was in accordance with results from the mesocosm experiments. The highest density values were also observed for Cylindrotheca at impacted site. The last part of this research gathers the multiple spatial and temporal responses provided by the selected bioindicators to urban wastewater pollution in order to validate their future routine use in the context of monitoring programs. The occurrence of potential confusion sources in the interpretation of data was critically reviewed. The time-cost-efficiency of the tested parameters was then evaluated in order to assist environmental managers in their choices of biofilm-based techniques for detecting wastewater pollution. Finally since biofilms exhibited some strong accumulations of toxic elements, ecological hypotheses dealing with the trophic role of biofilms and the transfer of pollutants through the food webs are provided. [less ▲]

Spatial and temporal variation of bacterioplankton in a sub-Antarctic coastal area (Kerguelen Archipelago)

in Journal of Marine Systems (2007), 68(3-4), 366-380

Bacterial abundance and production were measured monthly for one year along cross-shore transects in 3 sub-Antarctic fjords of the Kerguelen Archipelago (seven stations each). Mean values of the 3 most ... [more ▼]

Bacterial abundance and production were measured monthly for one year along cross-shore transects in 3 sub-Antarctic fjords of the Kerguelen Archipelago (seven stations each). Mean values of the 3 most coastal (inside) and most offshore (outside) stations were used to describe the relationship between temperature, phytoplankton biomass, bacterial abundance and bacterial production over a one year annual cycle. The entire sampling protocol was repeated twice during each cruise: once at noon and once at midnight. Over the whole sampling period, the temperature ranged from 2.1 to 7.4 degrees C, while chlorophyll a concentrations varied by a factor of 10, and bacterial abundance and production varied by factors of 12 and 30, respectively. Within one day, all of these parameters sometimes varied by a factor of 4 between noon and midnight. A clear seasonality was observed for all of the parameters. However, while variations of phytoplankton and bacterial production paralleled those of temperature, bacterial abundance was low in midsummer and maximum in autumn. While no general pattern could be observed from the total data set, spatial gradients could interfere strongly with temporal changes. (C) 2007 Elsevier B.V All rights reserved. [less ▲]

Spatial and temporal variations in the occurrence of cocaine and benzoylecgonine in waste- and surface water from Belgium and removal during wastewater treatment

in Water Research (2009), 43

Spatial and/or visual short-term memory deficit in unilateral neglect

in 1st Joint Meeting of the Belgian Association for Psychological Science and Sociedad Espanola de Psicologia Experimental. (2012, May 11)

Patients suffering from left unilateral neglect fail to perceive or respond to stimuli presented within the contralesional space. Neglect is generally considered as involving an attentional bias towards ... [more ▼]

Patients suffering from left unilateral neglect fail to perceive or respond to stimuli presented within the contralesional space. Neglect is generally considered as involving an attentional bias towards the ipsilateral side. Recently, it has been suggested that revisiting and perseveration behaviors in visual search tasks shown in parietal neglect could be related to impairment in visuo-spatial working memory (Husain et al., 2001; Wojciulik et al., 2001). The aim of the present study was to investigate which aspect of visuo-spatial working memory is involved in unilateral neglect. Indeed, different source of evidence support the idea that visuo-spatial working memory involves at least two separate cognitive subsystems: the visual cache and the inner scribe (Logie, 1995; Pickering et al., 2001). We assessed thirteen right-damaged patients suffering from left neglect on two experimental task involving either spatial (Corsi test) or visual (Span test) working memory. Results show that visual and/or spatial working memory can be impaired in spatial neglect. This double dissociation provides neuropsychological support for the separation of visuo-spatial working memory into two subcomponents. The clinical and anatomical implications of this finding are discussed. [less ▲]

Spatial avoidance of invading pastoral cattle by wild ungulates: insights from using point process statistics

in Biodiversity & Conservation (2010)

Traditional rangelands in many developing countries are currently being encroached by cultivation, driving some herders to illegally use protected areas for grazing their cattle. Since cattle are an ... [more ▼]

Traditional rangelands in many developing countries are currently being encroached by cultivation, driving some herders to illegally use protected areas for grazing their cattle. Since cattle are an exotic species in these ecosystems, they might have an impact on the local wild herbivore communities, notably through competition. We used point pattern statistics to characterise the spatial relationships between wild ungulate species and cattle herds within a protected area in west Africa undergoing seasonal intrusions by cattle. We predicted that the wild ungulate species that are ecologically and morphologically similar to cattle, in terms of body mass and diet, would be more sensitive to grass depletion by cattle and would be separated from cattle to a larger extent. The spatial distribution of browsing and mixed-feeding antelopes did not seem to be affected much by cattle presence, whereas most grazing species showed spatial separation from cattle. Interestingly, elephants also showed significant separation from cattle herds. We discuss the likely processes that may have contributed to the observed spatial patterns. Thespatial displacement of certain wild species, including megaherbivores, affects the whole community structure and, thus, other components of the ecosystem. [less ▲]

Spatial correlation of OH Meinel and O2 Infrared Atmospheric nightglow emissions observed with VIRTIS-M on board Venus Express

in Icarus (2012)

We present the two-dimensional distribution of the O2 a1∆-X3Σ (0-0) band at 1.27 µm and the OH ∆v=1 Meinel airglow measured simultaneously with the Visible and Infrared Thermal Imaging Spectrometer ... [more ▼]

We present the two-dimensional distribution of the O2 a1∆-X3Σ (0-0) band at 1.27 µm and the OH ∆v=1 Meinel airglow measured simultaneously with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express. We show that the two emissions present very similar spatial structures. A cross-correlation analysis indicates that the highest level of correlation is reached with only very small relative shifts of the pairs of images. In spite of the strong spatial correlation between the morphology of the bright spots in the two emissions, we also show that their relative intensity is not constant, in agreement with earlier statistical studies of their limb profiles. We conclude that the two emissions have a common precursor that controls the production of both excited species. We argue that atomic oxygen, which produces O2(1∆) molecules by three-body recombination and is the precursor of ozone formation, also governs to a large extent the OH airglow morphology through the H + O3 → OH* + O2 reaction. [less ▲]

Spatial decomposition of on-nucleus spectra of quasar host galaxies

in Monthly Notices of the Royal Astronomical Society (2007), 378(1), 23-40

In order to study the host galaxies of type 1 (broad-line) quasars, we present a semi-analytic modelling method to decompose the on-nucleus spectra of quasars into nuclear and host galaxy channels. The ... [more ▼]

In order to study the host galaxies of type 1 (broad-line) quasars, we present a semi-analytic modelling method to decompose the on-nucleus spectra of quasars into nuclear and host galaxy channels. The method uses the spatial information contained in long-slit or slitlet spectra. A routine determines the best-fitting combination of the spatial distribution of the point like nucleus and extended host galaxy. This is fully complementary to a numerical spatial deconvolution technique that we applied to the same data in a previous analysis, which allows a cross-calibration of the two methods. Inputs are a simultaneously observed point spread function, and external constraints on galaxy morphology from imaging. We demonstrate the capabilities of the method to two samples of a total of 18 quasars observed with EFOSC at the ESO 3.6-m telescope and FORS1 at the ESO VLT. similar to 50 per cent of the host galaxies with successful decomposition show distortions in their rotation curves or peculiar gas velocities above normal maximum velocities for discs. This is consistent with the fraction from optical imaging. All host galaxies have quite young stellar populations, typically 1-2 Gyr. For the disc dominated hosts these are consistent with their inactive counterparts, the luminosity-weighted stellar ages are much younger for the bulge dominated hosts, compared to inactive early-type galaxies. While this presents further evidence for a connection of galaxy interaction and active galactic nucleus (AGN) activity for half of the sample, this is not clear for the other half. These are often undistorted disc dominated host galaxies, and interaction on a smaller level might be detected in deeper high-resolution images or deeper spectroscopic data. The velocity information does not show obvious signs for large scale outflows triggered by AGN feedback - the data are consistent with velocity fields created by galaxy interaction. [less ▲]