Sites In May Research Articles

Assessment of geochemical and sedimentological characteristics of atmospheric dust in Shiraz, southwest Iran

Geogenic dust is commonly believed to be one of the most important environmental problems in the Middle East. The present study investigated the geochemical characteristics of atmospheric dust particles in Shiraz City (south of Iran). Atmospheric dust samples were collected through a dry collector method by using glass trays at 10 location sites in May 2018. Elemental composition was analysed through inductively coupled plasma optical emission spectrometry. Meteorological data showed that the dustiest days were usually in spring and summer, particularly in April. X-ray diffraction analysis of atmospheric dust samples indicated that the mineralogical composition of atmospheric dust was calcite ​+ ​dolomite (24%)>palygorskite (18%)>quartz (14%)>muscovite (13%)>albite (11%)>kaolinite (7%)>gypsum (7%)>zircon ​= ​anatase (3%). The high occurrence of palygorskite (16%–23%) could serve as a tracer of the source areas of dust storms from the desert of Iraq and Saudi Arabia to the South of Iran. Scanning electron microscopy indicated that the sizes of the collected dust varied from 50 ​μm to 0.8 ​μm, but 10 ​μm was the predominant size. The atmospheric dust collected had prismatic trigonal–rhombohedral crystals and semi-rounded irregular shapes. Moreover, diatoms were detected in several samples, suggesting that emissions from dry-bed lakes, such as Hoor Al-Azim Wetland (located in the southwest of Iran), also contributed to the dust load. Backward trajectory simulations were performed at the date of sampling by using the NOAA HYSPLIT model. Results showed that the sources of atmospheric dust in the study area were the eastern area of Iraq, eastern desert of Saudi Arabia, Kuwait and Khuzestan Province. The Ca/Al ratio of the collected samples (1.14) was different from the upper continental crust (UCC) value (UCC ​= ​0.37), whereas Mg/Al (0.29), K/Al (0.22) and Ti/Al (0.07) ratios were close to the UCC value (0.04). This condition favours desert calcisols as the main mineral dust sources. Analysis of the crustal enrichment factor (EFcrustal) revealed geogenic sources for V, Mo, Pb, Sr, Cu and Zn (<2), whereas anthropogenic sources affected As, Cd, Cr and Ni.

Termites of Agropark, Universiti Malaysia Kelantan, Jeli Campus: Diversity and Pest Composition

Termites play important roles in the ecosystem as detritivores and soil engineers. However,alterations of the forest could change the diversity and abundance of termites. The Agropark atUniversiti Malaysia Kelantan (UMK), Jeli Campus is an agricultural park that is surrounded bysecondary forest and rubber plantations. This study was conducted to determine the diversity andpest species composition of termites at Agropark, UMK. Standardized line transects 100m long ×2m wide and divided into 20 sections (5m long × 2m wide) were conducted at three differentsampling sites in May to September 2015. A total of 29 termite species from 13 genera weresuccessfully identified with relative abundance of 128 (total hits). Diversity indices show highdiversity and evenness among the termite species in the study area. The termites comprise offamily Termitidae (75.9%) and family Rhinotermitidae (24.1%). Subfamily Macrotermitinaerecorded higher a number of species (12 species, 78 hits) compared to other subfamilies recordedin this study. Wood feeders and epigeal mound builders dominated the termite assemblages. Thetotal pest termite species collected is 41.4% (12 species) while 58.6% (17 species) of termitespecies were non-pest species that provide good ecological services to Agropark, UMKKJ. Thepests are mainly from genera Coptotermes, Schedorhinotermes, Macrotermes, Microtermes andGlobitermes. The higher number of pest species shows the possibility of pest attacks to thebuildings around the Agropark. Precautions against termite attack should be taken earlier toprevent serious damage to buildings in the future.

Vegetation affects pool size and composition of amino acids in Tibetan alpine meadow soils

Soil amino acids are of great importance for nitrogen cycling and plant nutrition, especially in the nitrogen-limited ecosystems. However, the factors that influence amino acid pools in alpine meadow soils remain unclear. The aims of this study were to answer the following questions: (1) Do soil amino acid pools under different vegetation cover show appreciable differences in their concentration and composition during the growing season? (2) Is the pool size of soil amino acids in the alpine meadow smaller or larger than those in other ecosystems? Soils were sampled from three sites dominated by three typical types of plants (Kobresia graminifolia, Polygonum viviparum and Elymus nutans) in a Tibetan alpine meadow, respectively, during the growing season. Soils were extracted with water and 2M KCl solution, respectively, and amino acids were quantitatively determined by high performance liquid chromatography. The results show that the pool size of soil exchangeable amino acids extracted by 2M KCl in this alpine meadow is comparable to those in other N-limited ecosystems. The pool size of soil amino acids across the three sites displayed temporal dynamics during the growing season, with the pool size increased from May to July and decreased in August. The P. viviparum soil had the largest amino acid pool among the three sites in May, whereas the largest pool in July and August was found in the K. graminifolia soil. The composition of the soil amino acid pools across the sites changed over the season, with acidic amino acids being abundant (63.6–84.3%) in spring, and neutral amino acids dominating (53.7–66.0%) in summer. The three sites shared five dominant amino acids (lysine, glutamic acid, leucine, alanine, and serine) through June to August; however, the other dominant amino acids (glycine, valine and threonine) varied among the sites and the months. These results suggest that the concentration and composition of amino acid pools in the Tibetan alpine meadow soils could be significantly influenced by the vegetation cover. Additionally, soil sampling time and extraction methods could also exert pronounced effect on the results. The information obtained in this study may help in understanding the influence of plant-soil feedback on soil amino acid pools, and the mechanisms of organic nitrogen uptake by alpine plants.

Mosquito (Diptera: Culicidae) Habitat Surveillance by Android Mobile Devices in Guangzhou, China.

In 2014, Guangzhou City, South China, suffered from its worst outbreak of dengue fever in decades. Larval mosquito habitat surveillance was carried out by using android mobile devices in four study sites in May 2015. The habitats with larval mosquitoes were recorded as photo waypoints in OruxMaps or in videos. The total number of potential mosquito habitats was 342, of which 166 (49%) were found to have mosquito larvae or pupae. Small containers were the most abundant potential habitats, accounting for 26% of the total number. More mosquito larvae and pupae, were found in small containers than in other objects holding water, for example, potted or hydroponic plants (p < 0.05). Mosquito larvae were collected from all plastic road barriers, used tires, and underground water. Aedes albopictus larvae were found from small and large containers, stumps, among others. The overall route index (RI) was 11.3, which was 14.2 times higher than the grade C criteria of the National Patriotic Health Campaign Committee (NPHCC), China. The higher RIs were found from the bird and flower markets, schools, and underground parking lots. The results indicated that Android mobile devices are a convenient and useful tool for surveillance of mosquito habitats, and the enhancement of source reduction may benefit the prevention and control of dengue vector mosquitoes.

Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments.

The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor habitats should consider bottom water temperature variation. Bottom temperature has important implications for estimates of seasonal and spatial benthic flux variation, benthic–pelagic coupling, and impacts of predicted ocean warming at high latitudes.

A Gis-based system for assessing marine water quality around offshore platforms

In this study, a GIS-based system (MWQ-FES) is developed for marine water quality assessment around offshore oil platforms. The developed method consists of a fuzzy risk assessment model, a eutrophication assessment module, a heavy metal assessment module, a dynamic database, the ArcGIS Engine, and a graphical user interface (GUI). The developed GIS-based GUI system integrates the fuzzy risk calculation, eutrophication risk assessment and heavy metal risk evaluation and both spatially and visually presents the results in the form of contour maps and color-coded maps that indicate the risk levels. The assessment modules analyze a large amount of data with both spatial and temporal distributions; these data are managed by the developed system. An application of the developed MWQ-FES to a real case study in China is presented in this study. The MWQ-FES produces risk maps that depict the spatial distribution of the integrated water quality index values, the eutrophication risk level and the heavy metal risk level in the study area. The primary factors that affect the water quality are subsequently examined using the visualized results. The results of the fuzzy risk assessment model show that the general water quality status in the study area was good in Oct. 2005, May 2006, and Sept. 2007, while fair water quality occurred in May 2007. For Oct. 2005, May 2006, and Sept. 2007, the eutrophication risk levels were oligotrophic, slightly eutrophic and mesotrophic, respectively. However, the eutrophication risk level at most of the sites in May 2007 was highly eutrophic. These findings agreed with previously reported water quality variations in the study area. The heavy metal risk level in the study area exhibited a slight risk during all four investigations. As for the ecological risk in the mariculture zone near the study area, the heavy metal risk exhibited a slight risk; the eutrophication risk level ranged from eutrophic to slightly mesotrophic. A comparison with previous environmental assessment results for the same study area confirms that the developed MWQ-FES can provide a better understanding of the distribution of the water quality status and ecological risk levels. Moreover, MWQ-FES can be a useful decision-support tool for marine water quality management.

Implementing a national flexible sigmoidoscopy screening program: results of the English early pilot.

Following the results of a major UK study showing that once-only flexible sigmoidoscopy (FSIG) screening significantly reduced colorectal cancer (CRC) incidence and mortality, an FSIG screening program in England was announced in late 2010. Three "early pilot" sites were selected in 2011 in Derby, South of Tyne, and Tees to assess the practicalities of the delivery of FSIG screening. Eligible people aged 55 from selected practices in the three early pilot areas received postal invitations to participate. The South of Tyne and Derby sites employed interactive models of screening invitation, while Tees used a simple invitation. Data were collected to assess uptake, process, and outcome. A self-completion participant satisfaction questionnaire was sent to all participants 1 month after attendance. A total of 4023 55-year-olds were invited to participate. Uptake was 29 %, with 1151 people screened over a 3-month period. Screening uptake differed by method of invitation: a simple approach was significantly more successful than an interactive one (32 % vs. 27 %, P = 0.0015). Uptake decreased significantly with increasing deprivation. Adenomas were found in 111 (9.8 %) of those screened and cancer in two. The procedure was rated "very" or "fairly" acceptable by 97 % of participants. Over 90 % of respondents said they would participate in future cancer screening and a similar proportion would recommend doing so to others. Delivery of an FSIG screening program to prevent CRC is feasible and should be implemented using a simple invitation system. The national Bowel Scope program subsequently commenced at pilot sites in May 2013, with full implementation planned by 2016.

Performance of invasive alien fountain grass (Pennisetum setaceum) along a climatic gradient through three South African biomes

The knowledge of relative performance of plants across environmental gradients is critical for their effective management and for understanding future range expansion. Pennisetum setaceum is an invasive perennial grass found along roadsides and other disturbed sites in South Africa. The performance of this grass in response to competition, habitat characteristics and resources was experimentally tested in three biomes (Karoo, Fynbos and Savanna) of South Africa. A total of 846 young P. setaceum seedlings were translocated to study sites in May 2007. The seedlings were grown in 94 plots along random transects, of which alternate halves were cleared of vegetation. Despite a variety of environmental hazards at these sites, over 30% of the transplanted seedlings survived over 15months. Competition from resident vegetation was a major factor limiting the establishment of seedlings. However, under adequate rainfall and historical disturbance (mine dump), competition effects were overridden. Survival of seedlings was greatest in the Karoo National Park, possibly because of summer rainfall that occurred shortly after translocation. Despite differences in the survival and growth rates, seedlings remained alive at all sites, especially if they survived the first six months after translocation. P. setaceum is capable of persisting across a broad range of environmental conditions. Management efforts should aim to reduce seed production and establishment along roadsides that act as conduits into protected sites. This could be best achieved by maintaining as much indigenous cover along road verges as possible, as seeds survive best where competition is low.

Cloud immersion: an important water source for spruce and fir saplings in the southern Appalachian Mountains

Cloud immersion can provide a potentially important moisture subsidy to plants in areas of frequent fog including the threatened spruce-fir communities of the southern Appalachian Mountains (USA). These mountaintop communities grow only above ~1,500 m elevation, harbor the endemic Abies fraseri, and have been proposed to exist because of frequent cloud immersion. While several studies have demonstrated the importance of cloud immersion to plant water balance, no study has evaluated the proportion of plant water derived from cloud moisture in this ecosystem. Using the isotopic mixing model, IsoSource, we analyzed the isotopic composition of hydrogen and oxygen for water extracted from ground water, deep soil, shallow soil, fog, and plant xylem at the upper and lower elevational limits both in May (beginning of the growing season) and October (end of the growing season). Cloud-immersion water contributed up to 31% of plant water at the upper elevation sites in May. High-elevation plants of both species also experienced greater cloud immersion and had greater cloud water absorption (14-31%) compared to low-elevation plants (4-17%). Greater cloud water uptake occurred in May compared to October, despite similar rainfall and cloud-immersion frequencies. These results demonstrate the important water subsidy that cloud-immersion water can provide. With a warming climate leading potentially to increases in the ceiling of the cloud base and, thus, less frequent cloud immersion, persistence of these relic mountaintop forests may depend on the magnitude of these changes and the compensating capabilities of other water sources.

Zooplankton distribution patterns at two seamounts in the subtropical and tropical NE Atlantic

AbstractSpatial distribution patterns of zooplankton biomass in relation to local and large‐scale hydrographical and biological driving forces were studied at Ampère and Senghor, two shallow seamounts in the subtropical and tropical NE Atlantic, respectively. The study includes a first assessment of the taxonomic composition and an estimation of the respiratory carbon demand of the zooplankton community. Zooplankton was sampled during three cruises at the seamount and open ocean reference sites in May and October 2009 and in December 2010. Zooplankton standing stocks and the corresponding respiratory carbon demand were about six times higher at Senghor than at Ampère, with mean stocks of 24.7 and 4.6 g·m−2, respectively, in the upper 1000 m. Mean respiratory carbon demand in the epipelagic zone was calculated as 61.4 mg·C·m−2·day−1 for Senghor and 9.6 mg·C·m−2·day−1 for Ampère. At neither site were differences between seamount and open ocean sites significant. However, horizontal surveys across Ampère Seamount show clear differences between day and night distributions and a reduced biomass above the summit. Across Senghor, zooplankton biomass increased from the SW to the NE flank, with the highest concentrations in the subsurface layer of the chlorophyll maximum and just above a strong oxycline. The zooplankton community at Ampère Seamount reflects the oligotrophic character of the NE Atlantic subtropical gyre, whereas the nutrient‐rich waters of the cyclonic tropical gyre at Senghor support a higher biomass. This difference in the zooplankton biomass between the two seamounts can be attributed to the large‐scale hydrographical features governing the productivity regimes rather than to regional seamount effects.

Use of pacemaker programmers for disaster victim identification

Disaster victim identification (DVI) presents a number of physical and legal challenges, involving the degeneration of human remains and legal obstacles to forensic examinations. One non-invasive method for positive identification may be the use of a pacemaker programmer to detect and obtain data from pacemakers recovered from unidentified remains. To test the usefulness of this method, this investigation examined the efficiency and utility of 5 different pacemaker programmers in the positive identification of victims of the March 2011 tsunami in Japan at 8 disaster sites in May 2011. On scanning 148 sets of remains, data were successfully obtained from 1 implant in 1 set of remains, allowing for the rapid positive identification of the individual. Scanning pacemakers with pacemaker programmers can be a non-invasive method of positive identification that meets Japanese legal and institutional requirements, but this method is ineffective without a preceding whole-body X-ray scan.

Identification of a Male-Produced Aggregation Pheromone for &lt;I&gt;Monochamus scutellatus scutellatus&lt;/I&gt; and an Attractant for the Congener &lt;I&gt;Monochamus notatus&lt;/I&gt; (Coleoptera: Cerambycidae)

We report identification and field testing of 2-(undecyloxy)-ethanol (monochamol) as a sex-specific, aggregation pheromone component produced by males of Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae), a longhorned beetle native to North America. A congener, Monochamus notatus (Drury), which uses the same hosts as M. s. scutellatus, also was attracted to this compound in field trials, suggesting it may be a pheromone component for this species as well. Panel traps were deployed along transects at each of five field sites in May 2010 to test attraction of native beetle species to a suite of cerambycid pheromone components, including monochamol, 3-hydroxyhexan-2-one, (2R*,3R*)- and (2R*, 3S*)-2,3-hexanediol, racemic (E/Z)-fuscumol, and (E/Z)-fuscumol acetate. In total, 209 adult M. s. scutellatus (136 females, 73 males) and 20 M. notatus (16 females, four males) were captured, of which 86 and 70%, respectively, were captured in traps baited with monochamol (means significantly different). Analysis of headspace volatiles from adult M. s. scutellatus by coupled gas chromatography-mass spectrometry and gas chromatography-electroantennogram detection confirmed that monochamol was produced only by males. Monochamol was not found in headspace extracts from adult M. notatus. This study provides further evidence that monochamol is a pheromone component common to several species in the genus Monochamus. The pheromone component should prove useful for monitoring native species for management purposes or conservation efforts, and for quarantine monitoring for exotic species.

Human Beach Use Affects Abundance and Identity of Fungi Present in Sand

Abstract Stevens, J.L.; Evans, G.E., and Aguirre, K.M., 2012. Human beach use affects abundance and identity of fungi present in sand. To determine whether abundance and diversity of fungal species differed among very low use, residential, and commercial beaches and whether human use had a measurable effect on sand fungi, samples were collected for two consecutive years from South Carolina beaches along a continuum of human use. For both years, more fungi (colony-forming units [CFUs] per gram dry weight sand) were isolated from high-use beach sand samples than low-use beach sand samples (analysis of variance, p < 0.05), but there was no evidence of accumulation of fungi over a tourist season or from year to year. In fact, fungal abundance was greatest for all three sites in May and July and significantly decreased in September. A positive correlation was found between census of beach-goers and fungal CFUs. Potential pathogens (fungi which grew at 37°C) were selected, and DNA-based sequence identifications...

남해연안 전복양식장 퇴적물의 황산염 환원과 철 환원에 의한 유기물 분해 특성

We investigated geochemical properties, and microbial sulfate- and iron(Ⅲ) reduction in sediment influenced by the aquaculture of abalone in the Nohwa-do, southern coastal sea in Korea. Concentrations of ammonium, phosphate, and sulfide in the pore-water were higher at farm sites than at control sites. The differences between the 2 types of sites were most apparent in terms of the weights of abalone and the temperature increase during September. Accordingly, the rates of sulfate reduction at the farm sites during September (61 m㏖ S m?²d?¹) were 3-fold higher than the sulfate reduction during May (20 m㏖ S m?²d?¹1). In contrast, Fe(Ⅲ) reduction rates were highest at the control sites in May, but its significance was relatively decreased at farm sites during September when sulfate reduction rates were highest. During September, benthic ammonium flux was 3-fold greater at the farm sites (35 m㏖ N m?²d?¹) than at the control sites (12 m㏖ N m?²d?¹), and phosphate flux was 8-fold higher at the farm sites (0.018 m㏖ P m?²d?¹) than at control sites (0.003 m㏖ P m?²d?¹). Overall results indicated that the inappropriate operation of a large-scale aquaculture farm may result in excess input of biodeposits and high nutrient fluxes from the sediment, thereby decreasing diversity of the benthic ecosystem and deepening eutrophication in coastal waters.

Latitudinal gradient in the ovary weight of bluegill Lepomis macrochirus in Lake Biwa, Japan

The local difference in the ovary weight of bluegill Lepomis macrochirus was investigated in Lake Biwa, Japan. Fish samples were collected from four sites in May 2010 before the onset of spawning. Analytical results indicated that the ovary weights decreased significantly with latitude. The ratios of ovary weight to the body weight of fish collected at the lowest-latitude site frequently exceeded 10%, whereas those at the highest-latitude site were always below 5.79%. A latitudinal decrease in the ovary weight was obviously responsible for the higher body weights of fish in the south basin of the lake than those in the north basin, since the ovary-removed body weights of fish tended to increase with latitude. As the water temperature of Lake Biwa normally starts to increase in spring from lower latitudes, the latitudinal gradient in the ovary weight of bluegill appeared to be owing to the difference in the local temperature. Results of this study suggest that bluegill can adjust their reproductive activity by sensitively responding to the local temperature condition. This attribute can be regarded as one of the strategies of the bluegill to optimise the adaptive success to various environments, probably contributing to the rapid expansion of the fish after introduction to the lake.

Bacterial diversity, composition and temporal-spatial variation in the sediment of Jiaozhou Bay, China

Studies on the diversity and distribution of bacterial populations will improve the overall understanding of the global patterns of marine bacteria and help to comprehend local biochemical processes and environments. We evaluated the composition and the dynamics of bacterial communities in the sediment of Jiaozhou Bay (China) using PCR-denaturing gradient gel electrophoresis (DGGE). Sediment samples were collected from 10 different sites in May, August, and November 2008 and in February 2009. There was significant temporal variation in bacterial community composition at all sites. However, the spatial variation was very small. The DGGE analyses of bacterial communities were used to divide the 10 stations into three types. Canonical correspondence analysis (CCA) revealed that the changes in bacterial communities were driven by sediment properties. Sequence analysis of DGGE band-derived 16S rRNA gene fragments revealed that the dominant bacterial groups in the sediment were of the classes γ-proteobacteria and δ-proteobacteria and phyla Bacteroidetes and Nitrospirae. Our results provide considerable insight into the bacterial community structure in Jiaozhou Bay, China.

Current status of Korean streams and exploring areas with high necessity for stream structure restoration

Stream restoration is an important process affecting the ecological health of stream ecosystems. There have been numerous cases of restoration, dealing with either structural or biological changes. In Korea, most restoration projects have merely dealt with improving hydrological characteristics or water quality; however, in recent years the improvement of ecological characteristics has been an increasing focus for restoration projects. In this study, we utilized data collected from 5675 stream sites in May 2007 to discover general patterns of anthropogenic modification in Korean streams. The survey results after application of the stream modification index (SMI; presence or absence type; high scores indicate more disturbed) provided a general distribution of disturbed/undisturbed streams or rivers in the watershed. We then compared the level of modification with the socio-geographical patterns (population, land coverage, elevation, and slope) for the watershed. The results show that streams in highly populated areas suffered from human modification compared with other well-preserved stream sites. In metropolitan cities, urbanized areas had positive relationship as identified by a high SMI. On the other hand, agricultural land cover identified an SMI increase for lowland river area. In general, mountainous streams possessed a better status in stream morphology due to different land-cover patterns (i.e., mainly forested area); however, some mountainous areas were impacted by concentrated summer rainfall. We could distinguish the forcing variables (i.e., land use pattern) for the disturbed streams through a comparison between the SMI and geographical information; the SMI application was able to identify areas of high necessity for restoration.

Landscape indicators and thresholds of stream ecological impairment in an intensively mined Appalachian watershed

AbstractCoal-mine development is occurring at a rapid rate in the central Appalachians, but few tools exist to assess the consequences of cumulative effects of mining to downstream aquatic resources. We constructed and applied an index of mining intensity (MI) to the Lower Cheat River basin, northern West Virginia. Our objectives were to: 1) determine if the MI could be used to predict stream-water quality and biological conditions, 2) quantify the extent to which geology and the geographic position of mines modulate the effects of mining on in-stream conditions, and 3) identify thresholds of MI that produce quantifiable changes to benthic macroinvertebrate communities. We quantified water chemistry, habitat quality, and benthic macroinvertebrate communities from May 2002 to May 2003 in 39 stream segments randomly distributed across a range of MI, coal geology, elevation, and watershed area. We sampled benthic macroinvertebrates at an additional 41 validation sites in May 2002. The MI was positively corre...

Determination of diet in Manila clams by spatial analysis of stable isotopes

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 387:167-177 (2009) - DOI: https://doi.org/10.3354/meps08100 Determination of diet in Manila clams by spatial analysis of stable isotopes C. Dang1,2,*, P. G. Sauriau3, N. Savoye1,2, N. Caill-Milly4, P. Martinez5,6, C. Millaret1,2, J. Haure7, X. de Montaudouin1,2 1Université de Bordeaux and 2CNRS, UMR 5805, Station Marine d’Arcachon, 2 rue du Pr Jolyet, 33120 Arcachon, France 3LIENSs, Université de La Rochelle, CNRS, 2 rue Olympe de Gouge, 17000 La Rochelle, France 4IFREMER, Laboratoire Ressources Halieutiques Aquitaine, 1, allée du parc Montaury, 64600 Anglet, France 5Université de Bordeaux and 6CNRS, UMR 5805, Avenue des Facultés, 33405 Talence, France 7IFREMER, Laboratoire Génétique et Pathologie, Polder des Champs, 85230 Bouin, France *Email: c.dang@epoc.u-bordeaux1.fr ABSTRACT: Spatial changes in the dietary regime of Ruditapes philippinarum from intertidal sediments of Arcachon Bay were depicted by analyzing stable isotope ratios in both its adductor muscles and potential trophic sources. Manila clams were collected from 50 sites in May to June 2006. Dietary reconstruction was based on the IsoSource mixing model, considering trophic enrichments of 3.5‰ for carbon and 3.0‰ for nitrogen, which were determined experimentally. δ13C and δ15N values, respectively, averaged –28.2 and 5.2‰ for riverine particulate organic matter (POM), –20.6 and 4.7‰ for inner bay phytoplankton, –21.0 and 5.6‰ for outer bay phytoplankton, –16.8 and 4.8‰ for microphytobenthos, –18.4 and 3.9‰ for sedimentary organic matter (SOM) and 11.8 and 4.0‰ for Zostera noltii. Clam muscle δ13C and δ15N values ranged from –20.5 to –16.4‰, and from 7.6 to 9.3‰, respectively. δ15N significantly decreased from southern to northern parts of the bay, while δ13C values increased with tidal elevation. Outer bay phytoplankton was the major diet component of clams. Clams from the southeast mainly incorporated outer bay phytoplankton despite the proximity of the Leyre River, whereas clams from the northwest incorporated approximately equal parts of inner and outer bay phytoplankton, riverine POM, microphytobenthos and SOM. These patterns were consistent with spatial gradients driven by the dominant role of tidal hydrodynamics within the bay and land-use characteristics of the catchment. KEY WORDS: Ruditapes philippinarum · Muscle · C and N stable isotopes · Trophic sources · Mixing model · Spatial variability · Arcachon Bay · SW France Full text in pdf format PreviousNextCite this article as: Dang C, Sauriau PG, Savoye N, Caill-Milly N and others (2009) Determination of diet in Manila clams by spatial analysis of stable isotopes. Mar Ecol Prog Ser 387:167-177. https://doi.org/10.3354/meps08100 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 387. Online publication date: July 28, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Seed availability and gap size influence seedling emergence of dandelion (Taraxacum officinale) in grasslands

AbstractDandelion (Taraxacum officinale agg.) seedlings colonize gaps in agricultural grassland and give rise to weedy pastures. It was investigated how this colonization is affected by seed availability and gap size. Flowering, seed production and spontaneous seedling emergence in artificial gaps were recorded at seven grassland sites. Fifteen to 126 flowers m−2 (2·2–18·6 thousands of seeds m−2) were produced at particular sites in May 2005. Seed availability explained 0·91 of the between‐site variation in seedling abundance. Seedling populations represented c. 0·03 of the seed produced at these sites. Shading, pH, soil nutrients and soil texture did not affect seedling emergence. In 2006, seed was sown at one site in small (33 cm2) and large (400 cm2) gaps on eight occassions during the growing season. Time to germination was on average 10 d shorter and 0·20 more of the seed germinated in small than large gaps, and both varied significantly with date of sowing. Germination was not limited by low temperature. Predation of seeds may have decreased the density of established seedlings. Patches of dandelions in sparse or weakly disturbed grassland are unlikely to disappear spontaneously and repeated cutting during spring flowering is recommended as an effective means of management.