982 resultados para St. Lawrence River
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High levels of hydrological connectivity during seasonal flooding provide significant opportunities for movements of fish between rivers and their floodplains, estuaries and the sea, possibly mediating food web subsidies among habitats. To determine the degree of utilisation of food sources from different habitats in a tropical river with a short floodplain inundation duration (similar to 2 months), stable isotope ratios in fishes and their available food were measured from three habitats (inundated floodplain, dry season freshwater, coastal marine) in the lower reaches of the Mitchell River, Queensland (Australia). Floodplain food sources constituted the majority of the diet of large-bodied fishes (barramundi Lates calcarifer, catfish Neoarius graeffei) captured on the floodplain in the wet season and for gonadal tissues of a common herbivorous fish (gizzard shad Nematalosa come), the latter suggesting that critical reproductive phases are fuelled by floodplain production. Floodplain food sources also subsidised barramundi from the recreational fishery in adjacent coastal and estuarine areas, and the broader fish community from a freshwater lagoon. These findings highlight the importance of the floodplain in supporting the production of large fishes in spite of the episodic nature and relatively short duration of inundation compared to large river floodplains of humid tropical regions. They also illustrate the high degree of food web connectivity mediated by mobile fish in this system in the absence of human modification, and point to the potential consequences of water resource development that may reduce or eliminate hydrological connectivity between the river and its floodplain.
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‘Demonstration reaches’ are sections of river where multiple threats to native fish are addressed through river rehabilitation and strong community participation. They are an important way of promoting the key driving actions of the Murray-Darling Basin Authority's Native Fish Strategy (NFS) by using on-ground community-driven rehabilitation. Measuring rehabilitation success against well-defined targets and using this information to adaptively mange activities is fundamental to the demonstration reach philosophy. Seven years on from the establishment of the first demonstration reach, there are now seven throughout the Murray-Darling Basin (MDB), all in differing states of maturation and but all applying a standardised framework for monitoring native fish outcomes. In this study, we reflect on the role that demonstration reaches have played within the NFS, synthesise some key findings from 32 monitoring and evaluation outputs, and highlight some of the successes and barriers to success. We make recommendations as to how to strengthen the demonstration reach model to ensure it remains a relevant approach for fish habitat rehabilitation beyond the NFS and MDB.
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The Florida manatee, Trichechus manatus latirostris, is a hindgut-fermenting herbivore. In winter, manatees migrate to warm water overwintering sites where they undergo dietary shifts and may suffer from cold-induced stress. Given these seasonally induced changes in diet, the present study aimed to examine variation in the hindgut bacterial communities of wild manatees overwintering at Crystal River, west Florida. Faeces were sampled from 36 manatees of known sex and body size in early winter when manatees were newly arrived and then in mid-winter and late winter when diet had probably changed and environmental stress may have increased. Concentrations of faecal cortisol metabolite, an indicator of a stress response, were measured by enzyme immunoassay. Using 454-pyrosequencing, 2027 bacterial operational taxonomic units were identified in manatee faeces following amplicon pyrosequencing of the 16S rRNA gene V3/V4 region. Classified sequences were assigned to eight previously described bacterial phyla; only 0.36% of sequences could not be classified to phylum level. Five core phyla were identified in all samples. The majority (96.8%) of sequences were classified as Firmicutes (77.3 ± 11.1% of total sequences) or Bacteroidetes (19.5 ± 10.6%). Alpha-diversity measures trended towards higher diversity of hindgut microbiota in manatees in mid-winter compared to early and late winter. Beta-diversity measures, analysed through permanova, also indicated significant differences in bacterial communities based on the season.
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The study deals with the irrigation planning of the Cauvery river basin in peninsular India which is extensively developed in the downstream reaches and has a high potential for development in the upper reaches. A four-reservoir system is modelled on a monthly basis by using a mathematical programming (LP) formulation to find optimum cropping patterns, subject to land, water and downstream release constraints, and applied to the Cauvery basin. Two objectives, maximizing net economic benefits and maximizing irrigated cropped area, considered in the model are analysed in the context of multiobjective planning and the trade-offs discussed.
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Dry seeding of aman rice can facilitate timely crop establishment and early harvest and thus help to alleviate the monga (hunger) period in the High Ganges Flood Plain of Bangladesh. Dry seeding also offers many other potential benefits, including reduced cost of crop establishment and improved soil structure for crops grown in rotation with rice. However, the optimum time for seeding in areas where farmers have access to water for supplementary irrigation has not been determined. We hypothesized that earlier sowing is safer, and that increasing seed rate mitigates the adverse effects of significant rain after sowing on establishment and crop performance. To test these hypotheses, we analyzed long term rainfall data, and conducted field experiments on the effects of sowing date (target dates of 25 May, 10 June, 25 June, and 10 July) and seed rate (20, 40, and 60 kg ha−1) on crop establishment, growth, and yield of dry seeded Binadhan-7 (short duration, 110–120 d) during the 2012 and 2013 rainy seasons. Wet soil as a result of untimely rainfall usually prevented sowing on the last two target dates in both years, but not on the first two dates. Rainfall analysis also suggested a high probability of being able to dry seed in late May/early June, and a low probability of being able to dry seed in late June/early July. Delaying sowing from 25 May/10 June to late June/early July usually resulted in 20–25% lower plant density and lower uniformity of the plant stand as a result of rain shortly after sowing. Delaying sowing also reduced crop duration, and tillering or biomass production when using a low seed rate. For the late June/early July sowings, there was a strong positive relationship between plant density and yield, but this was not the case for earlier sowings. Thus, increasing seed rate compensated for the adverse effect of untimely rains after sowing on plant density and the shorter growth duration of the late sown crops. The results indicate that in this region, the optimum date for sowing dry seeded rice is late May to early June with a seed rate of 40 kg ha−1. Planting can be delayed to late June/early July with no yield loss using a seed rate of 60 kg ha−1, but in many years, the soil is simply too wet to be able to dry seed at this time due to rainfall.
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This symbolic study of "St.Cyprien" concentration camp life done while Nussbaum was interned there in France. It is inscribed "Entwurf zu einem Gemälde" (Study for a painting) at lower left corner. It shows a group of men huddled around a globe or hunched in isolation against a desolate background of barren land and barbed wire. The drawing is one of the most artistically powerful and technically perfect in the collection.
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The Australian lungfish is a unique living representative of an ancient dipnoan lineage, listed as ‘vulnerable’ to extinction under Australia’s
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Tutkimuksen punaisena lankana kulkee kysymys siitä, millainen on bikerkulttuurin eetos? Miten se on syntynyt, miten sitä ylläpidetään ja miten Misfit MC:n jäsenet sitä tulkitsevat ja toteuttavat omassa elämässään? Tarkastelen eetosta kahdenlaisen aineiston valossa. i) Kenttätyöllä (vuosina 1995-1998 ja 2000-2001) kerätyn aineiston valossa tarkastelen yhtä pääkaupunkiseudulla toimivaa HD-moottoripyöräkerhoa, vuonna 1989 toimintansa aloittanutta Misfit MC:tä. Jäsenet kutsuvat kerhoaan useimmiten talliksi, joskus pajaksi, kerhoksi tai klubiksi. Puhuessaan tallista, miehet voivat viitata kerhorakennukseen ("tuut sä tallille?") mutta myös ryhmään ("meidän talli") ja sen olemassaoloon ajallisesti ja paikallisesti. Aloittaessani kenttätyön vuonna 1995 Misfit MC:n kuului kymmenen 25-30-vuotiasta miestä. ii) Kenttätyöllä kerätyn aineiston lisäksi käytän materiaalia, joka koostuu Harley-Davidson-moottoripyörän ympärille rakentuneen bikerkulttuurin historiasta ja kulttuurituotteista, kuten kertomuksista, elokuvista, musiikista, kuvataiteesta ja moottoripyörälehdistä. Aineiston avulla valotan bikerkulttuurin eetoksen syntyä, alkuvaiheita, leviämistä ja keskeisiä elementtejä. Lähdeaineiston monimuotoisuus ja runsaus palautuu kenttätyöhöni jolloin vakuutuin siitä, että tutkimusmatka bikerkulttuurin historiaan, perinteisiin ja median välittämiin (mieli)kuviin on välttämätöntä, sillä menneisyys ja Harrikkaan ajan kuluessa varastoituneet merkitykset vaikuttavat ja ovat vahvasti läsnä Misfit MC:n toiminnassa ja talliin kuuluvien miesten elämäntyylissä. Tutkimus etenee seuraavanlaisesti. Luku I on Johdanto. Luvussa II Etnografia käsittelen etnografisen tiedon luonnetta niin tutkimusasenteena kuin kenttätyön valossa. Pohdin kenttätyötä ja sen suhdetta etnografian kirjoittamiseen eli miten kenttätyöllä kerätty aineisto muuntuu etnografiseksi monografiaksi. Käsittelen myös kenttätyöni reunaehtoja, kuten tyttöystävyyden ja sukupuolen merkitystä, ja tarkastelen tutussa kulttuurissa tehdyn kenttätyön ominaispiirteitä. Reunaehtojen kuvailu toimii myös johdatuksena bikerkulttuuriin sellaisena kuin se ilmenee Misfit MC:n tallielämässä ja käytänteissä. Lopuksi pohdin "tiheän kuvauksen" mahdollisuuksia ja vaateita aineistoni puitteissa. Luvussa III Bikerkulttuurin eetosta kartoittamassa, kuvailen Harley-Davidson-moottoripyörän ympärille rakentuneen elämäntavan syntyä, levittäytymistä ja keskeisiä elementtejä. Tarkastelen media- ja populaarikulttuurisia tekstejä (elokuvien kertomat tarinat, musiikkikappaleiden sanoitukset ja HD- ja bikerlehtien artikkelit) ja kuvia (elokuvien audiovisuaaliset aspektit, kuvataide ja HD- ja bikerlehtien kuvitus), jotka ovat vaikuttaneet bikerkulttuurin eetokseen. Luvun keskeisiä - aineistosta nousevia ja miessukupuoleen vahvasti sidoksissa olevia - käsitteitä ovat biker, outlaw ja chopper, jotka ovat bikerkulttuurissa säilyneet alkuperäisessä muodossa maantieteellisestä tai kielialueesta riippumatta. Luvussa IV Misfit MC ja bikerkulttuurin eetos temaattinen painopiste siirtyy Suomeen ja Misfit MC:hen. Aluksi käyn läpi suomalaisen bikerkulttuurin muotoutumista ja ominaispiirteitä. Alkukappaleiden jälkeen keskityn Misfit MC:n jäsenten elämäntyylin sävyihin ja heidän käsityksiinsä bikerkulttuurin eetoksesta. Analyysin kiintopisteitä ovat Misfit MC:n jäsenten näkemys bikeriydestä ja tallitoiminnasta, miesten elämäntyylin moraaliset ja esteettiset sävyt, tallirakennus miesyhteisöllisyyttä ja bikerkulttuurin eetosta luovana ja ylläpitävänä sosiaalisena tilana ja Misfit MC miesten yhteisönä. Luvussa V Eetoksen ytimessä: mies ja Harley-Davidson keskityn bikerkulttuurin ytimeen: miehen ja Harley-Davidson-moottoripyörän väliseen suhteeseen. Luvun alussa esittelen ruotsalaisen yhteiskuntatieteilijä Lars Lagergrenin moottoripyörään soveltamaa työkalu - leikkikalu - toteemi - välittäjä -typologiaa ja tarkastelen moottoripyörän olemusta sukupuolittavana ja sukupuolittuvana artefaktina. Johdanto-osion jälkeen siirryn kuvailemaan Misfit MC:n jäsenten suhdetta Harley-Davidson-moottoripyörään. Lähestyn miesten ja moottoripyörien suhdetta kahden toiminnan - moottoripyörän kunnostamisen ja rakentamisen sekä moottoripyörällä ajamisen - kautta. Avainsanat: aineellinen kulttuuri, arvot, biker, bikerkulttuuri, chopper, eetos, elämäntapa, etnografia, Harley-Davidson-moottoripyörä, Harley-Davidson-moottoripyöräkerho, kenttätyö, maskuliinisuus, mieskulttuuri, mieskuva, moottoripyöräily, osakulttuurit, outlaw, populaarikulttuuri, sukupuoliroolit, yhteisöt
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Uncertainty plays an important role in water quality management problems. The major sources of uncertainty in a water quality management problem are the random nature of hydrologic variables and imprecision (fuzziness) associated with goals of the dischargers and pollution control agencies (PCA). Many Waste Load Allocation (WLA)problems are solved by considering these two sources of uncertainty. Apart from randomness and fuzziness, missing data in the time series of a hydrologic variable may result in additional uncertainty due to partial ignorance. These uncertainties render the input parameters as imprecise parameters in water quality decision making. In this paper an Imprecise Fuzzy Waste Load Allocation Model (IFWLAM) is developed for water quality management of a river system subject to uncertainty arising from partial ignorance. In a WLA problem, both randomness and imprecision can be addressed simultaneously by fuzzy risk of low water quality. A methodology is developed for the computation of imprecise fuzzy risk of low water quality, when the parameters are characterized by uncertainty due to partial ignorance. A Monte-Carlo simulation is performed to evaluate the imprecise fuzzy risk of low water quality by considering the input variables as imprecise. Fuzzy multiobjective optimization is used to formulate the multiobjective model. The model developed is based on a fuzzy multiobjective optimization problem with max-min as the operator. This usually does not result in a unique solution but gives multiple solutions. Two optimization models are developed to capture all the decision alternatives or multiple solutions. The objective of the two optimization models is to obtain a range of fractional removal levels for the dischargers, such that the resultant fuzzy risk will be within acceptable limits. Specification of a range for fractional removal levels enhances flexibility in decision making. The methodology is demonstrated with a case study of the Tunga-Bhadra river system in India.
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Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants with adverse impacts on aquatic biota, wildlife and human health even at low concentrations. However, conventional methods for their determination in river sediments are resource intensive. This paper presents an approach that is rapid and also reliable for the detection of OCPs. Accelerated Solvent Extraction (ASE) with in-cell silica gel clean-up followed by Triple Quadrupole Gas Chromatograph Mass Spectrometry (GCMS/MS) was used to recover OCPs from sediment samples. Variables such as temperature, solvent ratio, adsorbent mass and extraction cycle were evaluated and optimised for the extraction. With the exception of Aldrin, which was unaffected by any of the variables evaluated, the recovery of OCPs from sediment samples was largely influenced by solvent ratio and adsorbent mass and, to some extent, the number of cycles and temperature. The optimised conditions for OCPs extraction in sediment with good recoveries were determined to be 4 cycles, 4.5 g of silica gel, 105 ᴼC, and 4:3 v/v DCM: hexane mixture. With the exception of two compounds (α-BHC and Aldrin) whose recoveries were low (59.73 and 47.66 % respectively), the recovery of the other pesticides were in the range 85.35 – 117.97% with precision < 10 % RSD. The method developed significantly reduces sample preparation time, the amount of solvent used, matrix interference, and is highly sensitive and selective.
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Long-term monitoring data collected from wild smolts of Atlantic salmon (Salmo salar) in the Simojoki river, northern Finland, were used in studying the relationships between the smolt size and age, smolt and postsmolt migration, environmental conditions and postsmolt survival. The onset of the smolt run was significantly dependent on the rising water temperature and decreasing discharge of the river in the spring. The mean length of smolts migrating early in the season was commonly higher and the mean age always older than among smolts migrating later. Many of the smolts migrating early in the season and almost all smolts migrating later had started their new growth in spring in the river before their sea entry. Among postsmolts, the time required for emigration from the estuary was dependent on the sea surface temperature (SST) off the river, being significantly shorter in years with warm than cold sea temperatures. After leaving the estuary, the postsmolts migrated southwards along the eastern coast of the northern Gulf of Bothnia, the geographical distribution of the tag recoveries coinciding with the warm thermal zone in spring in the coastal area. After arriving in the southern Gulf of Bothnia in late summer the postsmolts mostly migrated near the western coast, reaching the Baltic Main Basin in late autumn. Until the early 1990s there was only a weak positive association between smolt length and postsmolt survival. However, following a subsequent decrease in the mean smolt size, a significant positive dependence was observed between smolt size and the reported recapture rate of tagged salmon. The differences in recapture rates between smolts tagged during the first and second half of the annual migration season were insignificant, indicating that the seasonal variation in smolt size and age seem to be too small to affect survival. Among the climatic factors examined, the summer SST in the Gulf of Bothnia was most clearly related to the survival of the wild postsmolts. Postsmolt survival appeared to be highest in years when the SST in June in the Bothnian Bay varied between 9 and 12 ºC. In addition, the survival of wild postsmolts showed a significant positive dependence on the SST in July in the Bothnian Sea, but not on the abundance of the prey fish (0+ herring, Clupea harengus and sprat, Sprattus sprattus) in the Bothnian Sea and in the Baltic Main Basin. The results suggest, that if the incidence of extreme weather conditions were to increase due to climatic changes, it would probably reduce the postsmolt survival of wild salmon populations. For improving the performance of hatchery-reared smolts, it could be useful to examine opportunities to produce smolts that are in their smolt traits and abilities more similar to the wild smolts described in this thesis.