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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Effects of wastewater effluent on macrobenthic infaunal communities at Christies Beach, South Australia /

Loo, Maylene G. K. January 2001 (has links) (PDF)
Thesis (Ph.D.) -- University of Adelaide, Dept. of Environmental Biology, 2001. / Includes bibliographical references (leaves 136-154).
52

Detritos foliares em riachos subtropicais: dinâmica de matéria orgânica, processo de decomposição e macrofauna associada / Leaf litter in subtropical streams: dynamics of organic matter, decomposition process and associated macrofauna.

König, Rodrigo 08 March 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Low-order forested streams are dependent on allochthonous material input and the main energy source is obtained from leaf litter provided by the surrounding vegetation. Several gaps need to be filled to the knowledge of this process in subtropical environments and, accordingly, the thesis aimed to conduct some investigations considering the decomposition of leaf litter in streams. Four studies were conducted in subtropical streams with the following objectives: a) to verify the quantitative importance of the leaf input into streams, the main sources of input and its variation over the year; b) to analyze the influence of the leaf litter quality on decomposition and macroinvertebrate colonization; c) to evaluate the influence of the land use on the decomposition process, including the macroinvertebrate community and fungi; d) to conduct an initial investigation about the influence of insecticide application on the macroinvertebrate community that colonizes leaves in streams. Leaf litter was the main plant component to come in stream and the main route of entry allochthonous material was vertical. We observed the influence of season on this entry, with an increase mainly in the autumn and in the months with high rainfall. The chemical characteristic of leaves influenced the decomposition of leaf litter and its colonization by the macroinvertebrate community. Leaves with higher nitrogen content and lower amount of components that hinder decomposition were processed more quickly and, for these reasons, showed a higher amount of shredders. Moreover, different land uses did not significantly influence the decomposition process, just modifying some aspects of the macroinvertebrate community, especially in streams with urban influence. The results may be due to high currents found in local streams that make homogeneous its consequences for water quality, for the biological component and hence for ecological processes such as decomposition. We observed an influence of insecticide application on the macroinvertebrate community, decreasing the abundance of the target groups of the product, but generating an increase in the richness and abundance of other groups after an initial period of colonization. / Os riachos florestados de baixa ordem são dependentes da entrada de material alóctone e a principal fonte de energia é obtida de detritos foliares provenientes da vegetação de entorno. Várias lacunas precisam ser preenchidas para o conhecimento desse processo em ambientes subtropicais e, nesse sentido, esta tese teve como objetivo realizar algumas investigações considerando o processamento de detritos foliares em riachos. Foram conduzidos quatro estudos em riachos subtropicais com os seguintes objetivos: a) verificar a importância quantitativa da entrada foliar em riachos, as principais vias de entrada e sua variação ao longo do ano; b) analisar a influência da qualidade do detrito foliar sobre a decomposição e colonização por macroinvertebrados; c) avaliar a influência do uso e ocupação da terra sobre o processo de decomposição, incluindo a comunidade de macroinvertebrados e fungos; d) realizar uma investigação inicial acerca da influência da aplicação de inseticida sobre a comunidade de macroinvertebrados que coloniza folhas em riachos. Detritos foliares foram o principal componente vegetal a entrar no riacho e a principal via de entrada do material alóctone foi a lateral. Foi observada influência da época do ano sobre esta entrada, com aumento principalmente nos meses do outono e com alta pluviosidade. A característica química das folhas influenciou a decomposição de detritos foliares e sua colonização pela comunidade de macroinvertebrados. Folhas com maior teor de nitrogênio e menor quantidade de componentes que dificultam a decomposição foram processadas mais rapidamente e apresentaram maior quantidade de fragmentadores. Por outro lado, diferentes usos da terra não influenciaram significativamente o processo de decomposição, apenas modificando alguns aspectos da comunidade de macroinvertebrados, principalmente em riachos com influência urbana. Os resultados podem ter ocorrido devido às altas correntezas encontradas nos riachos da região, que tornam homogêneas suas consequências para a qualidade da água, para o componente biológico e, consequentemente, para os processos ecológicos como a decomposição. Foi observada uma influência da aplicação de inseticida sobre a comunidade de macroinvertebrados, diminuindo a abundância dos grupos-alvo do produto, mas gerando um aumento na riqueza e abundância dos demais grupos após um período inicial de colonização.
53

Efeito da contaminação da água por petróleo sobre a fauna de invertebrados aquáticos associada à Salvinia auriculata Aublet (Salvineaceae) e seu uso como bioindicadora de poluição ambiental

Oliveira, Ilton Soares 11 March 2008 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-08-24T15:30:38Z No. of bitstreams: 1 Dissertação - Ilton Soares Oliveira.pdf: 49138055 bytes, checksum: 572cc3fa364829fc6f9579e54c783929 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-26T19:58:56Z (GMT) No. of bitstreams: 1 Dissertação - Ilton Soares Oliveira.pdf: 49138055 bytes, checksum: 572cc3fa364829fc6f9579e54c783929 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-26T20:03:36Z (GMT) No. of bitstreams: 1 Dissertação - Ilton Soares Oliveira.pdf: 49138055 bytes, checksum: 572cc3fa364829fc6f9579e54c783929 (MD5) / Made available in DSpace on 2015-08-26T20:03:36Z (GMT). No. of bitstreams: 1 Dissertação - Ilton Soares Oliveira.pdf: 49138055 bytes, checksum: 572cc3fa364829fc6f9579e54c783929 (MD5) Previous issue date: 2008-03-11 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / The effect of the exposition of aquatic invertebrates of a white water lake of the Amazonian basin to petroleum was analyzed on different concentrations (control, 0.05, 0.5, 5 ml/l) and on six times of exposition (10 min, 60min, 6hs, 24hs, 3 days and 10dias). The collections occurred between the months of March and November of 2007 having contemplated the regional hydrologic cycle, to allow the detection of seasonal variations in the populations of the invertebrates. The analyses of data had shown a reduction of 39% in richness of taxa in the highest concentration of oil, but this effect was not detected in lower concentrations. The taxa that showed greater sensitivity to the oil were Diptera, Acari, Ostracoda and Cladocera of the Simocephalus genus and of the Chydoridae family. In contrast, the groups Anelida (Oligochaeta), Cladocera of the genus Diaphanosoma and Copepoda of the sub-order Cyclopoida were well represented but had not presented significant reductions in the presence of oil, indicating that they are tolerant or relatively tolerant groups to this pollutant. Both, the richness of taxa and the population density of each tax had strong seasonal variations. Due to this variation and the resistance of some groups, the effect of the oil on the aquatic communities must be established with caution so that studies with bioindicators present greater exactness. / Foram analisados os efeitos da exposição de invertebrados aquáticos de um lago de água branca da bacia amazônica a concentrações de 0,05; 0,5; 5,0 ml de petróleo ao longo de seis períodos de exposição (10 min, 60min, 6hs, 24hs, 3 dias e 10dias). As coletas ocorreram entre os meses de março e novembro de 2007 contemplando o ciclo hidrológico regional, de forma que variações sazonais nas populações dos invertebrados pudessem ser detectadas. As análises de dados mostraram que ocorreu uma redução de 39% na riqueza taxonômica na maior concentração de petróleo, mas este efeito não foi detectado em concentrações baixas. Os taxa que mostraram maior sensibilidade ao petróleo foram Diptera, Acari, Ostracoda e Cladocera do gênero Simocephalus e da família Chydoridae. Em contraste, os grupos Anelida (Oligochaeta), Cladocera do gênero Diaphanosoma e Copepoda da sub-ordem Cyclopoida foram bem amostrados mas não apresentaram reduções significativas quando na presença do petróleo, indicando que são grupos tolerantes ou relativamente tolerantes a este poluente. Tanto a riqueza quanto a densidade populacional de cada taxa sofreu fortes variações sazonais, devido a esta característica e a resistência de alguns grupos, o efeito do petróleo sobre as comunidades aquáticas deve ser estabelecido com cautela para que estudos com bioindicadores apresentem maior exatidão.
54

The presence of stygobitic macroinvertebrates in karstic aquifers: a case study in the cradle of humankind world heritage site

Tasaki, Sayomi 20 June 2008 (has links)
Subterranean ecosystems are regarded as the most extensive biome on earth, comprising terrestrial and aquatic systems - the latter constituting freshwater, anchialine and marine systems. This system plays a key role in the distribution and storage of freshwater, once it contains 97% of the world’s total liquid freshwater (Chapter 1), which has been progressively explored in quality and amount. Initial observation of the subterranean environment began with speleological studies by the recognition of a typical fauna adapted to live inside caves. The first studies to provide information about aquatic subterranean fauna commenced in Slovenia, with the description of the Proteus aguinus by Laurenti in 1768. After an initial faunal classification by the Danish zoologist Schiödte (1849), the Austrian naturalist Schiner (1854) established the most commonly used classification for cave fauna and a great portion of modern research dealing with ecobilogy of aquatic subterranean fauna has mostly evolved from the European biospeleology (Chapters 1 and 3). Studies in biospeleology have made a significant contribution to the progressive knowledge in aquatic subterranean ecology, especially in those circumstances where the access of the underground through smaller voids (e.g. crevicular spaces) is not possible. Accessibility to the underground environment is in fact a negative factor that has led a large number of studies consider about subterranean fauna initially being limited to caves. Spatial constraint was (and still is) a limiting factor in accessing a diverse range of subsurface habitats, although during the last decade, modern research has been using advance technology as a tool to overcome the physical barriers to subterranean research. For a long time the classification of subterranean aquatic organisms was an unclear subject, with the classification subterranean fauna mostly related to terrestrial cave fauna (troglofauna). The classification system dealing with aquatic subterranean groups (stygofauna) is more recent. A few nomenclature schemes have been proposed to describe these relationships, based on morphological, behavioural, and ecological adaptations of animals to the underground life and their level of relationship with groundwater (Chapter 4). The prefix “stygo” is suggested as the most descriptive to refer ecologically to a group of animals related to groundwater habitats. Groundwater related fauna (stygofauna) is comprised by groups of animals encompassing aquatic surface, intermediate and subterranean habitats. They represent diverse group of animals that have different interactive relationships with the groundwater habitat. Some may transact between surface water and groundwater systems, while others spend the whole life cycle in the subterranean voids (Gibert et al., 1994). This transition zone between surface streams and groundwater is recognized as a critically important boundary or ecotone, constituted by a habitat that contains a reservoir of invertebrate fauna biodiversity. It is therefore from the study of karst systems that most information on groundwater ecobiology is resourced, once the open structure of most karsts terrains promotes a number of caves, streams, crevices, sinkholes, and springs to allow human access. Karst systems are well fractured because of the relation between the rock mass and the action of meteoric water, as well as the dissolution rate of calcium carbonate rocks that high. The latter increases with time, producing a terrain with a great drainage potential (Chapter 2). Once porosity is high and the flow of percolating water is fast, it allows good vagility for subterranean fauna and nutrients, as well as penetration of contaminants. In subterranean karsts, much water saturates some areas inside rock spaces. The saturation in the rock in turn promotes large water pockets, known as aquifers. When these groundwater aquifers are found to be interconnecting with the adjacent ecosystems, they became active eco-hydrological components, due to their key participation in the surface-groundwater continuum. Groundwater has different degrees of importance, depending on the available sources of surface water. In many countries it supplies a significant proportion of urban and rural drinking water, industrial, and agricultural. Yet, groundwater systems are “hidden”, difficult in access and to study (Chapter 4, 5 and 7), consequently the recognition of the groundwater aquifer as a natural resource that needs to be protected is largely ignored. Moreover, studies in the ecobiology and distribution of stygobitic invertebrates (Chapter 5), and the need to identify a frame of methods for quality assessment and the suitability of groundwater invertebrates as bioindicative elements, has not been developed (Chapter 6). Finally, strong management and public education programs are required to emphasize the need for a better understanding of the nature of groundwater resources, their participation and complexity (Chapter 8), with the conceptualization of the groundwater aquifer integrity as an ecosystem still receiving little attention in South Africa. / Dr. J.F. Durand Prof. G.J. Steyn
55

Assessing the effects of water and sediment quality on aquatic macro-invertebrate diversity in the Steelpoort River, Olifants River System, Limpopo Province

Matlou, Katlego Shirley January 2017 (has links)
Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2017 / In this study data was collected to establish if the water and sediment quality of the Steelpoort River has any effects on macro-invertebrate species. The Steelpoort River is a tributary of the Olifants River system but not much data about the water quality is available. The Steelpoort River is a perennial river (Ashton et al. 2001) situated west of Burgersfort and from there it flows in a north- easterly direction and converges with the Olifants River in the Drakensberg near Kromellenboog. High silt levels in the river, increases the risk of flooding and leads to the smothering of in-stream habitats resulting in loss of some invertebrate and fish species. Sampling of the water, sediment and macroinvertebrates was conducted quarterly at the Steelpoort River at five sites. One site was above the impoundment (De Hoop Dam) and the rest were below the impoundment. A handheld YSI 556™ Multi Probe System (MPS instrument and a Mettler Toledo SevenGo™ conductivity meter were used to measure the physico-chemical characteristics at the sites. The macroinvertebrates were sampled using the SASS 5 bio-assessment protocol (Goodyear & McNeill 1999, Dickens & Graham 2002). Macro-invertebrate samples were collected using a 400 mm x 400 mm SASS net with a 250 μm mesh size. The substrate was disturbed for a period of two minutes to free macro-invertebrates from the substrate. The SASS score for each site was evaluated in the field for three of the five samples. The macro-invertebrate samples were preserved in 70% ethanol and sorted to family level in the University of Limpopo’s Biodiversity laboratory. For the majority of the physico-chemical parameters the most elevated were detected downstream and lowest concentrations were detected upstream. Analysis of variance (ANOVA) indicated that there were no significant differences for electrical conductivity, salinity, and TDS, between the sites (p>0.05). There were however significant differences in the temperature, dissolved oxygen, turbidity, and pH concentrations (p<0.05). The majority of the metals and metalloids in the water (Fe, Mn, V, Co, Zn, Ba, and Cu) were highest at Tiershoek (Site1) and lowest at Steelpoort (Site 4) and Burgersfort Bridge (Site 5).The mean metal concentrations collected showed elevated levels for chromium, copper and zinc, which were above the CCME sediment guidelines. The most abundant macroinvertebrates were from the family Ephemeroptera which are pollution sensitive and good indicators of pollution in aquatic ecosystems. When using the interpretation of the SASS 5 results from Chutter 1995, the mean Average Score Per Taxa (ASPT) scores show that the water quality for Tiershoek (Site 1) and Polopark (Site 3) is natural but the habitat diversity has been reduced. For De Hoop (Site 2) and Steelpoort (Site 4), the mean ASPT score shows that there is some deterioration in the water quality. Finally, for Burgersfort Bridge (Site 5), the mean ASPT score indicates that there is major deterioration in the water quality. Primer statistical analysis indicated that the average dissimilarity between sites showed that the highest dissimilarity was between Tiershoek (Site 1) and Burgersfort Bridge (Site 5) which was conclusive with the results from the macro-invertebrate count and SASS, indicating that there is diverse difference from upstream to downstream. CCA indicated positive correlations between nutrients detected at Steelpoort with Athericidae, Tabanidae, Gomphidae, Baetidae, Elmidae, Planaria, Psephenidae, and Libellulidae which was indicated that water chemistry characteristics exert influence on macroinvertebrates. The results showed that there is degradation of the water quality in river from upstream to downstream with more pollution tolerant species being abundant at Steelpoort (Site 4) and Burgersfort Bridge (Site 5). The most favourable season was autumn and the least summer/spring and this may be attributed to the life cycle of the macro-invertebrate communities / NRF VLIR
56

Selenium and trace metal accumulation in detrital-benthic food webs of lotic and lentic wetlands, Utah, USA

Hillwalker, Wendy E. 24 May 2004 (has links)
Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction with selected physicochemical data, from representative wetland types at a mining site within Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands managed by a copper mining industry. These fishless wetlands are located in a geographic region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling study demonstrated the extent of variation in total Se concentration within the wetlands. With the exception of the sediment compartment, Se concentration did not differ significantly along the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se concentrations between the Creek East and West segments characterize lower Lee Creek as having two segments distinguished by unique processes that influence the sediment Se accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000 to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic invertebrates was more clearly associated with sediment/detritus Se concentrations than with surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera), generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated 1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent of trace metal type (essential or non-essential) or wetland occupation. Organism-specific factors, such as habitat selection and preferential feeding habits, were proposed to influence benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets, trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific processes impacted Se accumulating efficiency, with trace metal concentrations from 4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital organic carbon as dietary sources for the benthic food web. Sediment organic content was not significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological risk assessments based on sound understanding of metal chemistry and the interactions between the sediment matrix and benthic organisms are necessary to provide tools for environmental management. / Graduation date: 2005
57

Återanslutning av s.k. korvsjöar till den ursprungliga flodfåran som en restaureringsåtgärd för ökad biodiversitet : -En litteraturstudie

Johansson, Andreas January 2017 (has links)
The aim with this review was to investigate whether a reconnection of an oxbow lake can contribute to higher biodiversity. However, oxbow lakes can be divided in three categories: Lentic- (connected with both ends to the river bed), semi-lentic- (connected with one end) and lotic oxbow lakes (Isolated from the riverbed). Aquatic organisms such as fish, aquatic invertebrates, amphibians and macrophytes has been studied. The result showed that hydrological connectivity determines both biodiversity and water quality in oxbow lakes. Lotic oxbow lakes consisted low biodiversity and it’s dominated by amphibians. Semi-lentic oxbow lakes contributes with highest biodiversity of macrophytes, fish and aquatic invertebrates. Lentic oxbow lakes consisted less biodiversity and was dominated by fish. In conclusion, reconnection of an oxbow lake can be used as a restoration project to improve biodiversity.
58

Methane flux in the Doñana wetlands : Waterbird guano addition and benthicinvertebrate effects / Metangasflöden i Doñanas våtmarker : Effekter av vattenlevande fåglars guano och bottenlevande evertebrater

Ratia, Noa January 2019 (has links)
Wetlands are globally important biogeochemical hotspots, and their roles as either significant sources of greenhouse gas or carbon sinks are strongly controlled by environmental drivers such as carbon, nitrogen, and phosphorus availability, which can stimulate emission of three greenhouse gases: nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4). Mounting evidence suggests that aquatic invertebrate activity can enhance wetland greenhouse gas flux, through bioturbation and bioirrigation of surrounding sediments. However, waterbirds reduce the density of aquatic invertebrates, which could potentially reduce greenhouse gas flux. Alternatively, the nutrient contents of waterbird guano may stimulate microbial activity responsible for these gas fluxes. The research project FLAMMINGGOS (Functional Links in Avian, Microbial, Macrophyte, and INvertebrate Greenhouse Gas Output Stimulation) aims to test the relative strength of top-down and bottom-up effects of predatory waterbirds on wetland greenhouse gas fluxes. This study is a part of the FLAMMINGGOS project and studied the bottom-up stimuli effects of methane flux, through addition of waterbird guano to sediment cores sampled from three sites in Doñana, Spain. Guano did not enhance methane flux; on the contrary, the overall flux rates decreased after guano addition for one site. There was also a positive correlation between methane flux and the presence of benthic invertebrates. This suggests that the top-down gas-stimuli effects of waterbirds may be stronger than the bottom-up; benthivorous waterbirds, such as flamingos, may lessen the emissions of CH4 through predation on benthic invertebrates. Further research is however required to fully understand these interactions and gas flux stimuli effects. / FLAMMINGGOS
59

Avaliação do risco ambiental da fluoxetina em sedimentos marinhos para invertebrados aquáticos / Environmental risk assessment of fluoxetine in marine sediments to aquatic invertebrates

Santos, Dymes Rafael Alves dos 06 February 2019 (has links)
O uso acentuado de fármacos e produtos de cuidado pessoal (FPCP) por grande parcela da população, associado ao aumento do número de habitantes, principalmente, em regiões costeiras, gera uma consequente e contínua entrada destas substâncias no ambiente. Com isso há uma necessidade crescente de se investigar a presença e o comportamento desta classe de contaminantes, principalmente em sedimentos, uma vez que estes são capazes de acumular e apresentar concentrações relativamente perigosas a organismos não-alvos. Assim, este estudo teve como objetivo avaliar o risco ambiental do fármaco fluoxetina (FLU) presente em sedimentos marinhos da região de Santos/SP, Brasil, por meio de ensaios ecotoxicológicos integrados à análises químicas para quantificação deste fármaco no ambiente marinho. Para tanto foram utilizados invertebrados marinhos, espécie Mytella charruana para a caracterização de citotoxicidade e atividade de biomarcadores, e as espécies Perna perna e Echinometra lucunter em ensaios de desenvolvimento embriolarval. Todos os orgismos-teste foram expostos à sedimentos marinhos previamente marcados com FLU. Por meio de técnicas de HPLC-ESI-MS/MS, foram identificadas e quantificadas concentrações da ordem de 10,4 ng.g-1 em sedimentos coletados no entorno do emissário submarino de esgoto de Santos (Baía de Santos, São Paulo - Brasil). A FLU apresentou efeitos sobre o desenvolvimento embriolarval de E. lucunter e P. perna e efeitos cito-genotóxicos para a espécie M. charruana, em concentrações ambientalmente relevantes. Segundo o método utilizado para avaliação de risco ambiental, a fluoxetina pode ser considerada como substância potencialmente perigosa para invertebrados aquáticos. / The high consumption of pharmaceutical and personal care products (PPCP) by a significant part of the human population, associated with the increase in the number of inhabitants, mainly in coastal regions, causes a continuous entry of these substances into the environment. Thus, there is a growing need to investigate the presence and behavior of this class of contaminants, especially in sediments, since they can accumulate and create relatively hazardous concentrations to non-target organisms. Therefore, the objective of this study was to evaluate the environmental risk of fluoxetine (FLU) present in marine sediments from the region of Santos/SP, Brazil, using ecotoxicological assays with chemical analyses so the amount of this pharmaceutical drug in the marine environment could be quantified. For this purpose, the marine invertebrates Mytella charruana species were used for the characterization of citotoxicity and endpoints using biomarkers, and the species Perna perna and Echinometra lucunter in embryo larval tests. All organisms used in the experiments were exposed to marine sediments previously spiked with known concentrations of FLU. Using LC-ESI-MS/MS, the environmental levels of FLU were quantified in marine sediments from the vicinities of the Santos submarine sewage outfall (Bay of Santos, São Paulo, Brazil) at 10.4ng.g-1. The fluoxetine has presented effects over the embryo larval development of E. lucunter and P. perna as such genotoxic and citotoxic effects for the M. charruana species at environmentally relevant concentrations. According to the employed ERA method, fluoxetine can be considered as a pontencially dangerous substance for acquatic invertebrates.
60

An environmental assessment of Bermuda's caves

Gibbons, Darcy Ann 17 February 2005 (has links)
The current environmental status of the majority of Bermuda’s one hundred sixty-six known caves was investigated. This survey replicated a historical cave study performed in 1983, wherein each was analyzed for positive and negative features. Statistical analysis of the data showed a significant difference between the historical and current survey ratings, with an overall decrease in environmental status. A water quality study was performed on twenty different caves with sea level pools in various locations around the island. Nitrate, nitrite, ammonia, and phosphate levels were measured from varying depths in these caves. Fifteen of these caves were also tested for the presence of fecal bacterial contamination. High nitrate levels were discovered in some of the caves, particularly in surface samples. Additionally, bacterial contamination was detected in some caves. No obvious relationship between cave size or location and contamination existed for any of the pollutants sampled. Three separate caves from this group were dived and analyzed using a Hydrolab Sonde 3 Multiprobe Logger to acquire in situ water column data including depth, temperature, pH, salinity, and dissolved oxygen. Each cave studied had its own unique trends in hydrology at varying depths in the water column. A later water sampling study with a randomized experimental design was created and caves were divided into four classes based on size and location. Surface and subsurface samples were gathered from twelve randomly selected caves, three from each class. Each sample was analyzed for nitrate, nitrite, and ammonia concentrations. The results were analyzed using multiple analysis of variance statistics. A significant difference between the nitrate concentrations in the surface and subsurface water samples was discovered. None of the other comparisons were statistically significant. To represent the data visually, a Bermuda Cave and Karst Information System (BeCKIS) was created using the environmental survey data and water quality information. Some of the maps generated highlighted regions where negative environmental impacts on caves were concentrated geographically, thus demonstrating how this geographic information system could be used as a conservation tool.

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