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1
She, Shu-sheng. "Determinants of macroinvertebrate community structure on stone surfaces in Hong Kong streams /". [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1373149X.
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Chan, King-tung. "Multivariate analysis of benthic macroinvertebrate communities of Hong Kong streams /". Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18037045.
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She, Shu-sheng, i 佘書生. "Determinants of macroinvertebrate community structure on stone surfaces in Hong Kong streams". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233879.
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Firkins, Ian. "Environmental tolerances of three species of freshwater crayfish". Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/11282/.
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The only species of crayfish native to the British Isles, i.e. Austropotamobius pallipes, is presently widely distributed throughout much of England, Wales and Ireland. The main controlling factor behind this distribution is the predominantly "bicarbonate" freshwater system of the British Isles. In geological terms, native crayfish are generally found in areas of chalk, carboniferous or magnesium limestone, or drift deposits of boulder clay. More recently, native crayfish have been affected by a general decline in the quality of Britain's freshwater system largely due to sewage effluent and agricultural. By far the majority of native crayfish records are associated with water bodies of very good or good quality, with the result that many populations of A. pallipes are isolated in small, good quality headwaters, due to the degree of pollution in the main rivers acting as "chemical barriers". The last two decades have seen a number of alien species of crayfish imported into England and Wales for aquaculture and culinary purposes. Deliberate and accidental introductions have resulted in the establishment of populations of these species in the wild, the most widespread being the North American signal crayfish Pacifastacus leniusculus and the European slender-clawed crayfish Astacus leptodactylus. An important and devastating consequence of the introduction of alien species of crayfish has been the spread of the crayfish plague fungus Aphanomyces astaci, possibly initiated by infected P. leniusculus. Both A. pallipes and A. leptodactylus are susceptible to the disease, with the result that populations of A. pallipes have been eliminated from, whole lengths of river, such as the River Kennet and the Hampshire River Avon. The nature of the disease and the ease with which it is spread means that crayfish is an ongoing problem in England and Wales, with new populations of A. pallipes regularly becoming affected. The distribution of alien species in the British Isles is an artificial one, initially determined by man, although consideration of water quality may have determined the choice of aquaculture sites. However, established populations of alien species in the wild will be subject to the same constraints as A. pallipes, which will affect their subsequent spread and distribution in the freshwater system of England and Wales. A greater tolerance of environmental factors may allow alien species to inhabit waters not currently occupied by the native species, such as polluted or estuarial waters, and possibly threaten populations of A. pallipes protected by "chemical barriers". This study investigated and compared some of the environmental tolerances of A. pallipes, A. leptodactylus and P. leniusculus and consisted of two parts: 1.) Comparison of the tolerance of A. pallipes, A. leptodactylus and P. leniusculus to four common pollutants; chloride, copper, ammonia and lindane, using lethal and sublethal toxicity tests. No species was found to have a greater overall pollution tolerance on the basis of the toxicants used in this study. Median lethal concentrations (LC50) obtained from lethal studies with stage II juveniles indicated that A. leptodactylus juveniles were most tolerant of chloride, but were very sensitive to lindane. P. leniusculus stage II juveniles were least tolerant of chloride, but of equal or greater tolerance when tested in larger juvenile stages, and were most tolerant of copper. A. pallipes juveniles were very sensitive to copper, and all three species showed a similar sensitivity to ammonia. However, episodic experiments with ammonia and copper indicated that differential short-term tolerance to toxicants, i.e. less than 24 hours, may be important in determining the outcome of episodic pollution events on crayfish populations. Salinity studies indicated high resistance to chloride, with all three species able to tolerate salinities up to 50% seawater, implying freshwater crayfish may be able to tolerate estuarine conditions. Accumulation studies with P. leniusculus inferred resistance to high levels of copper in the environment, with a substantial storage capacity for the metal and a regulatory mechanism for excretion of excess amounts. However, establishment of populations under high saline or high copper conditions would be limited by the lower tolerance of early life stages. Similarly, sublethal studies implied that sublethal toxicant effects on early life stages may be important in determining presence or absence of crayfish from a waterbody, through effects on recruitment. 2.) Comparison of the thermal relations of A. pallipes, A. leptodactylus and P. leniusculus, using tolerance, growth and respiration experiments. Results from tolerance experiments showed that P. leniusculus had a greater overall thermal tolerance, so is more resistant to changes in environmental temperature, such as in waters affected by thermal discharges or in waters affected by drought and reduced flow. In growth experiments P. leniusculus grew faster at all temperatures tested and was predicted to grow at temperatures unsuitable for the other species. Therefore, P. leniusculus would not only be able to survive and grow in conditions unsuitable for A. pallipes and A. leptodactylus, but will also grow faster where favourable conditions exist for all three species. Field experiments showed that, although P. leniusculus juveniles were smaller on release from the female, they were released earlier and their faster growth rate allowed them to maintain a distinct size advantage over A. pallipes juveniles, which was very marked by the end of the growing season. Large size is a key element in the attributes leading to competitive success in other crayfish species. Field observations on mixed populations of plague-free P. leniusculus and A. pallipes indeed show that signal crayfish are superior competitors, eventually eliminating A. pallipes. Therefore temperature effects may be important in determining the outcome of competition in mixed crayfish populations.
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Rodrigues, Andreia do Carmo Martins. "Combined effects of invasive species and insecticide exposure on freshwater invertebrates". Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22326.
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Doutoramento em BiologiaFreshwater invertebrate communities are often exposed to multiple stressors that can disrupt aquatic trophic chains and ecosystem functioning. Insecticide contamination and invasive species are two main anthropogenic stressors of concern in freshwaters. Understanding their combined effects to community structure and vital ecosystem functions present challenges for an improved ecological risk assessment. The main objective of this research was thus to investigate whether the deleterious effects of insecticide pollution may be mediated by the presence of alien invasive species. An integrative study was designed to assess the direct and indirect effects of these actual threats to freshwater benthic communities, from the individual towards the community and ecosystem levels with focus on detritus-based food webs. Chlorantraniliprole (CAP), an anthranilic diamide was selected as model compound due to its novel mode of action that confers specificity for ryanodine receptors of insects. Plus, CAP neurotoxicity can potentially disrupt individual behaviour and chemical communication among freshwater species. In a first step, CAP toxicity was assessed and compared with that from a broad-spectrum pyrethroid. Although CAP revealed less toxicity towards the selected species in comparison with the pyrethroid esfenvalerate (ESF), environmentally relevant concentrations of both insecticides disrupted the feeding behaviour of the shredder Sericostoma vittatum and impaired the development of the collector Chironomus riparius. Further, metabolic costs and sub-organismal effects due to insecticide-induced stress were also assessed with different biochemical biomarkers, revealing high energetic costs in exposed organisms. Two biotic factors of high ecological relevance, predation and resource quality, were selected and effects of two widely distributed invasive species (Procambarus clarkii and Eucalyptus globulus) were also considered. Multiple stressors exposures were then performed in microcosms systems with tri-trophic simplified detritus-based food webs to evaluate effects on leaf decomposition, C. riparius development and shredder-collector interactions. In a first trial, combined effects of CAP exposure and predation risk were tested. Shredders presence drastically increased leaf decomposition, but CAP exposure decreased this ecosystem process. CAP toxicity, predation risk and shredders presence independently lead to decreases on C. riparius growth. Additionally, in similar assays, alder and eucalypt leaf decomposition was reduced under predation risk, impairing larvae growth, being this effect exacerbated in the presence of less nutritive eucalypt leaves. In both assays, C. riparius growth was reduced in the presence of the shredders, suggesting a competition between these species, irrespective of CAP exposure or predation risk. Lastly, freshwater benthic communities were exposed to CAP and invasive species presence in mesocosms systems allowing to test the different combinations of stressors under a more complex and realistic exposure scenario. Community responses to CAP were assessed in the presence of leaf litter of different nutritional value (native A. glutinosa vs invasive E. globulus leaves) and the presence of different predators (native dragonfly Cordulegaster boltonii vs invasive crayfish P. clarkii). A path analysis using structural equation modeling (SEM), was applied to identify, quantify and discriminate between the strength of direct and indirect effects of all stressors and their combination on community structure (macroinvertebrate abundances) and ecosystem function (leaf decomposition and primary production). Environmentally relevant exposure to CAP, presence of crayfish and eucalypt leaves all contribute to changes on macroinvertebrate abundances. Crayfish presence mediated CAP toxicity to collectors and grazers. Shredders and collectors survival was reduced in treatments with eucalypt leaves which also presented lower leaf decomposition in comparison with streams with alder leaves. CAP toxicity towards collectors was magnified in the streams with Eucalyptus leaves. Density-mediated effects were observed and reductions of grazer species lead to increased primary production. In summary, this research showed that predator identity and detritus quality can mediate the effects of insecticide contamination on structural and functional endpoints in benthic freshwater communities and highlights the value of incorporating biotic stressors in ecotoxicological experiments. The present thesis is a contribution to the complex task of assessing the effects of pesticides under a more natural and complex scenario of exposure that is, nevertheless, critical for an effective risk management of freshwater ecosystems near agricultural areas.
As comunidades de invertebrados de água doce estão frequentemente expostas a múltiplas pressões que podem perturbar as cadeias tróficas e funções do ecossistema. A contaminação por inseticidas e a presença de espécies invasoras são duas das principais pressões antropogénicas nestes sistemas. Entender os seus efeitos combinados na estrutura e funções das comunidades é um dos atuais desafios para uma melhor avaliação de risco ecológico. O principal objetivo deste estudo foi avaliar se os efeitos deletérios da poluição por inseticidas são mediados pela presença de espécies invasoras. Para tal, foi realizado um estudo integrativo dos efeitos diretos e indiretos destas ameaças para as comunidades bentónicas de água doce, medindo respostas ao nível do indivíduo, da comunidade e ecossistema, com foco em cadeias alimentares de detritos. Chlorantraniliprole (CAP), uma diamida antranílica, foi usado como composto modelo devido ao seu modo de ação que lhe confere especificidade pelos recetores de rianodina de insetos. Além disso, a neurotoxicidade do CAP pode perturbar o normal comportamento e comunicação química entre espécies. Primeiramente, a toxicidade do CAP foi avaliada e comparada com a de um piretróide de amplo espectro. Embora o CAP se tenha revelado menos tóxico para as espécies estudadas que o esfenvalerato (ESF), concentrações ambientalmente relevantes de ambos os inseticidas inibiram a alimentação do fragmentador Sericostoma vittatum e diminuíram o desenvolvimento do coletor Chironomus riparius. Os custos metabólicos e os efeitos ao nível suborganismal foram avaliados através de diferentes biomarcadores bioquímicos, revelando elevados custos energéticos para estes invertebrados quando sob stress químico. Os efeitos de dois fatores bióticos de elevada relevância ecológica, predação e qualidade do recurso alimentar, foram estudados e avaliados alterando a sua identidade por duas espécies invasoras (Procambarus clarkii e Eucalyptus globulus) amplamente distribuídas na Europa. Exposições a múltiplos stressores foram então realizadas em sistemas de microcosmos com cadeias alimentares de detritos simplificadas para avaliar a decomposição de folhada, o crescimento de C. riparius e alterações nas interações fragmentador-coletor. Num primeiro ensaio, foram avaliados os efeitos combinados da exposição a CAP e risco de predação. A presença de fragmentadores aumentou consideravelmente as taxas de decomposição da folhada, mas a contaminação por CAP teve o efeito contrário. A toxicidade do CAP, o risco de predação e a presença de fragmentadores contribuíram para o decréscimo do crescimento de C. riparius. Em ensaios similares, a decomposição da folhada de amieiro e eucalipto foi reduzida sob risco de predação, diminuindo o crescimento das larvas, sendo este efeito exacerbado com eucalipto, de menor valor nutricional. Em ambos os ensaios, o crescimento de C. riparius foi reduzido na presença dos fragmentadores, sugerindo uma competição entre estas espécies, independentemente da exposição a CAP ou presença do predador. Por fim, comunidades bentónicas de água doce foram expostas a CAP e presença de espécies invasoras em mesocosmos, permitindo testar as diferentes combinações de stressores sob um cenário de exposição mais relevante. As respostas das comunidades ao CAP foram avaliadas na presença de folhada de diferentes valores nutricionais (da nativa Alnus glutinosa vs folhas da invasora E. globulus) e na presença de diferentes predadores (odonata nativo Cordulegaster boltonii vs lagostim invasor P. clarkii). Para identificar, quantificar e discriminar a magnitude dos diversos efeitos diretos, indiretos e combinados dos vários stressores sobre a estrutura da comunidade (abundância de macroinvertebrados) e função do ecossistema (decomposição foliar e produção primária), utilizou-se um método de análise de equações estruturais (SEM). Concentrações ambientalmente relevantes de CAP, a presença do lagostim e das folhas de eucalipto, contribuíram para alterações na abundância de macroinvertebrados. A presença do lagostim mediou os efeitos tóxicos do CAP para coletores e herbívoros. A sobrevivência dos fragmentadores e coletores foi reduzida nos tratamentos com folhada de eucalipto, que por sua vez também apresentaram menor decomposição em comparação com os rios com folhada de amieiro. A toxicidade do CAP para os coletores foi magnificada em rios com eucalipto como recurso alimentar. Efeitos mediados pela densidade foram observados através da redução de herbívoros que levou ao aumento de produção primária. Em síntese, este estudo demonstra que a identidade do predador e a qualidade dos recursos alimentares podem mediar os efeitos da contaminação por inseticidas em parâmetros estruturais e funcionais das comunidades bentónicas de água doce e destaca o valor da incorporação de stressores bióticos em testes ecotoxicológicos. A presente tese é um contributo para a complexa tarefa de avaliar os efeitos dos pesticidas considerando cenários de exposição ecologicamente relevantes que é, no entanto, crítica para uma avaliação de risco eficaz em ecossistemas de água doce perto de áreas agrícolas.
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Tan, Thomas Ching-Jen. "Telomere biology in the freshwater planarian Schmidtea mediterranea". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12308/.
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Freshwater planarian Schmidtea mediterranea is an emerging model for studying in vivo gene functions and regulation in native cell niches. The obligate asexual strain of this species reproduces by fission, in which succession of soma occurs without passing through the germline. To achieve this somatic immortality the somatic stem cells need to overcome the end replication problem. Therefore it can be hypothesised that somatic telomere maintenance in asexual S. mediterranea must possess a germ-like property, with which age-related erosions can be adequately repaired. In this PhD project, the telomere repeat unit in S. mediterranea was confirmed to be the vertebrate-like TTAGGG. Attrition of whole body telomere length was found in ageing sexual worms and also in asexual worms which had not gone through recent fission events. Opposite telomere length dynamics were observed in regenerated samples of the two strains, with erosion in the sexuals and reset in the asexuals. The telomere maintenance was found to increase during regeneration in both strains, with a higher level of increase in asexual worms. A homolog of the telomerase reverse transcriptase subunit, Smed_Tert, was identified and characterised in this organism. High level of Smed_Tert expression was seen in germ cells in mature sexual worms and adult stem cells in asexual worms. Knockdown of Smed_Tert expression by RNA interference caused progressive telomere erosion, however effects on cell proliferation and viability have not been observed in knockdown samples. Four alternate splice isoforms of Smed_Tert were identified. The enhanced telomerase activity during regeneration correlates with a proportional increase in the full-length isoform and a decrease in isoforms with a truncated TRBD domain, suggesting a dominant negative regulation of telomerase by alternative splicing. Significant increase in the expression of the full-length isoform was seen in regenerating asexual samples but not in sexual strains, which correlates with their telomere length dynamics. It is hoped that the comparative studies between the sexual and asexual strains can improve our understanding of how soma can evolve to become an effective inheritable unit.
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Ortiz, Natali Ortiz. "The effect of pond dyes on mosquitoes and other freshwater invertebrates". Thesis, University of Reading, 2018. http://centaur.reading.ac.uk/77950/.
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Freshwater habitats are important because they represent two percent of Earth’s water resources, are highly diverse in aquatic organisms and are the most productive and threatened ecosystem worldwide. Pollution, urbanization and climatic changes are responsible for drastic changes in these ecosystems. The creation of new ponds offers an opportunity to increase biodiversity, landscape connectivity and provide new habitat for organisms. However, new ponds might be a good habitat for mosquitoes to lay eggs. Mosquitoes have worldwide distribution and are responsible for most of the vector-borne diseases, affecting thousands of people and causing millions of deaths. British mosquitoes currently do not carry human diseases, but they are a biting nuisance. Their distribution, abundance, species composition and potential for mosquito disease transmission are intimately linked to the physical environment. Culex pipiens is commonly found in UK gardens and is a potential vector of viruses including the West Nile Virus. However, any environmental factors that significantly change the distribution and population of Cx. pipiens could impact future risks of disease transmission. Pond dyes are a cosmetic product for garden ponds and lakes; they inhibit algal growth and improve the overall appearance of the water body reflecting surrounding planting. The dyes block red light from entering the water, interrupting the process of photosynthesis and therefore inhibiting the growth of certain aquatic plants such as algae. Although these dyes are non-toxic to fish and invertebrates, their use in urban gardens raises questions linked to mosquito oviposition, since coloured water can be an attractant.
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Simaika, John Pascal. "Practical conservation planning from local to continental scales using freshwater invertebrates". Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/18051.
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Thesis (PhD)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Dragonflies (Insecta: Odonata) are a valuable tool for assessing aquatic systems and have been used as indicators of ecological health, ecological integrity, and environmental change, including climatic change. In four separate studies I explored the usefulness of dragonflies as surrogates in biomonitoring, site prioritization and indication of global climate change. In the use of dragonflies for biomonitoring, I field-tested a freshwater ecological integrity index, the Dragonfly Biotic Index (DBI), based on dragonfly assemblages at the local scale, and compared the DBI to a standard freshwater benthic macroinvertebrate-based freshwater health index. Overall, dragonflies were more sensitive to changes in river condition than were macroinvertebrates, and the DBI site value and macroinvertebrate scores were highly significantly correlated. I conclude that dragonfly assemblages in the form of a DBI are an excellent tool for environmental assessment and monitoring freshwater biodiversity, with the potential to replace benthic macroinvertebrate-based freshwater quality assessments. In the second study, I used the DBI to prioritize sites for conservation action in South Africa. Using a selected set of top prioritized sites, I compared the DBI’s performance to that of a rarity-complementarity algorithm. Site prioritization using the DBI reveals that CFR sites protect Red Listed taxa rather well. The rarity-complementarity algorithm represents all species, but without greater emphasis on the rare and threatened species. I conclude that the DBI is of great value in selecting biodiversity hotspots, while the algorithm is useful for selecting complementarity hotspots. The third study was made possible by the recent completion of a continental assessment of freshwater biodiversity, which revealed that patterns of richness and threat of four well-studied aquatic taxa largely coincide at the continental scale. Using only dragonflies, I built a protected areas network for Africa using spatial planning software. I then compared the performance of the existing African reserve network and that of known global biodiversity hotspots against the model, and identified sites of conservation concern. Although the current reserve network covers 10.7% of the landscape, the proportional representation of species geographic distributions in reserves is only 1.1%. The reserve network is therefore inefficient, and many areas of conservation priority that are not formally protected remain. The advantage of operating at the fine scale, while covering a large geographic area is that it shifts the focus from the large-scale hotspots to smaller priority areas within and beyond hotspots. In the fourth study, I created species distribution models of dragonflies in an El Niño-prone biodiversity hotspot in South Africa, and predicted the changes in species richness, geographic range and habitat suitability, forty and eighty years from now. According to the model results of two different emissions scenarios, at least three species will be lost from the area by 2050, and four by 2080. The remaining species are predicted to persist with reduced geographical ranges, at generally higher elevations. Most species presented here thrive quite well in artificial environments, that is, engineered ponds or dams. It is therefore unlikely that loss in connectivity will play a role for these species.
AFRIKAANSE OPSOMMING: Naaldekokers (Insecta:Odonata) is waardevolle instrumente om akwatiese sisteme te assesseer, en is al gebruik as aanwysers van ekologiese gesondheid, ekologiese integriteit en omgewingsverandering, insluitend klimaatsverandering. In vier studies het ek die nut van naaldekokers as surrogate in biomonitering, area prioritisering en indikasie van globale klimaatsverandering ondersoek. In die benutting van naaldekokers in biomonitering, het ek ´n varswater ekologiese integriteits indeks, die Dragonfly Biotic Index (DBI), wat gebaseer is op naaldekokergemeenskappe op die plaaslike skaal, getoets en dit vergelyk met ´n standaard bentiese makroinvertebraat-gebaseerde varswater gesondheids index. Naaldekokers was meer sensitief vir veranderinge in riviertoestand as makroinvertebrate, en die DBI lokaliteit waarde en makroinvertebraat telling was beduidend gekorreleer. Die gevolgtrekking was dat naaldekoker gemeenskappe in die vorm van die DBI ‘n uitstekende instrument is vir omgewings assessering en die monitering van varswater biodiversiteit, met die potensiaal om bentiese makroinvertebraat-gebaseerde varswaterkwaliteit assessering te vervang. In die tweede studie, het ek die DBI gebruik om areas te prioritiseer vir bewaringsaksie in Suid Afrika. Met die gebruik van ‘n geselekteerde set top prioriteit areas, het ek die DBI se prestasie vergelyk met die van ‘n rariteit-komplemetariteit algoritme. Area prioritisering met die gebruik van die DBI het aangedui dat CFR areas taxa op die Rooi Lys goed beskerm. Die rariteit-komplementariteit algoritme verteenwoordig alle spesies, maar beklemtoon minder skaars en bedreigde spesies. Die gevolgtrekking was dat die DBI van meer waarde is in die selektering van biodiversiteits ‘hotspots‘, terwyl die algoritme nuttig is vir die selektering van komplementariteits ‘hotspots‘. Die derde studie was moontlik gemaak deur die onlangse voltooiing van ‘n kontinentale assessering van varswater biodiversiteit, wat aangedui het dat patrone van rykheid en bedreiging van vier goed-bestudeerde akwatiese taxa grootliks ooreenstem op die kontinentale skaal. Met die gebruik van naaldekokers, het ek ‘n beskermde area netwerk gebou vir Afrika met ruimtelike beplannings sagteware. Ek het die prestasie van die bestaande Afrika reservaatnetwerk en die van bekende globale biodiversiteit ‘hotspots‘ vergelyk teen die model, en het areas van bewaringsbelang geidentifiseer. Alhoewel die bestaande reservaatnetwerk 10.7% van die landskap dek, is die proporsionele verteenwoordiging van spesies se geografiese verspreiding net 1.1%. Die reservaatnetwerk is dus onvoldoende en baie areas van bewaringsbelang is nie formeel beskerm nie. Die voordeel van op die fyn skaal werk terwyl ‘n groot geografiese are gedek word, is dat dit die fokus van groot skaal ‘hotspots‘ na kleiner prioriteits areas binne en buite ‘hotspots‘ verskuif. In die vierde studie, het ek spesies verspreidingsmodelle van naaldekokers geskep in ‘n El Nino-geneigde biodiversiteits ‘hotspot’ in Suid Afrika, en het veranderinge in spesies rykheid, geografiese verspreiding en habitatsgeskiktheid voorspel, veertig en tagtig jaar van nou af. Volgens die modelresultate van twee verskillende emissie scenarios, sal ten minste drie spesies verlore gaan uit die area teen 2050, en vier teen 2080. Daar word voorspel dat die oorblywende spesies sal voortduur in verkleinde geografiese areas, by groter hoogte bo seespieël. Die meeste spesies hier verteenwoordig floreer in kunsmatige omgewings, soos mensgemaakte damme. Dit is dus onwaarskynlik dat ‘n verlies in konnektiwiteit ‘n rol sal speel vir hierdie spesies.
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Cappo, Michael. "Frogs as predators of organisms of aquatic origin in the Magela Creek system, Northern Territory /". Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09SM/09smc249.pdf.
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Elangovan, Ramalingam. "Accumulation and distribution of aluminium in two freshwater invertebrates at neutral pH". Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488074.
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O'Neill, Anne Jennie. "Biomarkers of chemical impacts in the freshwater invertebrates Asellusaquaticus and Pacifastacus leniusculus". Thesis, University of Plymouth, 2004. http://hdl.handle.net/10026.1/1687.
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The international scientific community has grown increasingly concerned that exposure to low levels of anthropogenic chemicals may disturb hormone function and/or sub lethal toxicity to other cells or organ systems in vertebrate and invertebrate species. This research programme was designed to develop, evaluate, and apply a range of biological and chemical indicators in the laboratory and/or field to assess the impact of sublethal toxicants including potential endocrine disaipting chemicals in the aquatic invertebrates, Asellus aquaticus (isopod) and Pacifasiacus leniiisciiius (decapod). Laboratory exposures of A. aquaticiis to environmentally realistic concentrations of known contaminants present within the river systems have demonstrated a link between health status and chemical exposure. Exposure to the organoiins, tributyltin and triphenyltin, and the pesticides, dichlorvos and endosulphan, demonstrated that adults were adversely affected at the biochemical (esterase activities) and physiological level (ventilation rates), as well as disrupting embryo development during in vitro investigations. Field studies demonstrated that cholinesierase and carboxyleslerase activities, ventilatory rates, growth, sex ratios, number of copulatory pairs and ovigerous females, fecundity, and embryonic growth, development and survival were all adversely affected to some extent in the isopod at sites downstream of industrial and domestic effluent discharges in comparison to control populations. Some links were established between the biological parameters measured and sediment faecal sterol content and/or water physico-chemical parameters and comparisons of multiple biomarkers did demonstrate differences between organisms collected at reference and contaminated sites which may be an indicator of environmental stress. A preliminary field investigation of P. lenittscultis collected from sites of mild sewage pollution indicated statistically significant changes in some responses at the cellular (cell viability), molecular (micronucleus formation), and physiological (heart rate) level. The significance of these changes at the population level was not determined, however, there is evidently a need to conduct laboratory exposures of P. leniusculits to sewage effiuent and its individual components to determine whether the responses observed in the field are indicative of sewage contamination. In the present study, the sublethal responses of A. aquaticits and P. len len leniusculus to a range of endocrine disrupting chemicals has been investigated in laboratory and field settings and although cause and effect could not be demonstrated conclusively, this study has gone some way in identifying possible causative agents of these adverse effects in invertebrate populations.
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Cowley, C. "The influence of road runoff on the benthic macro-invertebrates of an unpolluted chalk stream". Thesis, University of Westminster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354965.
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Cheung, Ka-wing. "Spatial and seasonal variations of freshwater macroinvertebrates, odonata and waterbirds in Luk Keng marshland, Hong Kong". Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290951.
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Hansen, Jonathan Ford. "Long-term implications of dam removal for mesohabitat and macroinvertebrate communities in Michigan and Wisconsin rivers". Diss., Connect to online resource - MSU authorized users, 2008.
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Khan, Muhammad Irfan. "A lotic microcosm for ecological and ecotoxicological studies on benthic macroinvertebrates". Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320214.
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Chan, King-tung, i 陳勁東. "Multivariate analysis of benthic macroinvertebrate communities of HongKong streams". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31213911.
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Holthuis, Bernadette Veronica. "Evolution between marine and freshwater habitats : a case study of the gastropod Neritopsina /". Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/5195.
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Custer, Kevin Wayne. "FACTORS CONTROLLING NICKEL BIOAVAILABILITY AND EFFECTS ON BENTHIC INVERTEBRATES IN HARDWATER FRESHWATER STREAMS". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1364295154.
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Spann, Nicole. "Freshwater bivalves as biomonitors of metal pollution". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610276.
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Wood, Diane L. "The influence of abiotic factors on lotic insect communities of submerged rootmats and temporary pools /". free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9964013.
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Leung, Sze-lun. "Scale-dependent effects of spatial and temporal variability on benthic macroinvertebrate communities in Hong Kong streams /". Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25334542.
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Driver, Patrick, i n/a. "The role of carp (Cyprinus carpio L) size in the degradation of freshwater ecosystems". University of Canberra. School of Resources, Environmental and Heritage Sciences, 2002. http://erl.canberra.edu.au./public/adt-AUC20050404.110223.
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Carp (Cyprinus carpio) are alien freshwater fish that are globally widespread and often
associated with highly degraded freshwater ecosystems. This study explored carphabitat
interactions that could contribute to the worldwide distribution of, and
consequent ecological impacts by, carp. Particular emphasis was placed on the role of
carp size in these interactions. One component of this study involved a field experiment
that was used to quantify the effects of carp biomass density and size-structure on
freshwater invertebrate communities and water quality. The treatments in this field
experiment comprised different combinations of large (2 kg) and small (0.7 kg) carp,
and low (330 kg.ha-1), intermediate (570 kg.ha-1) and high (650 kg.ha-1) biomass
densities. Carp impacts were more carp size-dependent than described in previous
studies. In particular, carp size was more important than carp biomass density in
determining the concentration of total phosphorus and algal biomass. On the other hand,
a more even mix of carp sizes increased total nitrogen. The zooplankton and
macroinvertebrate taxa that were more abundant in the presence of carp were the taxa
most able to avoid carp predation and tolerate habitat changes caused by carp
benthivory. To complement the small-spatial scale field experiment, large-scale patterns
of carp distribution, biomass density and recruitment were explored among the rivers of
New South Wales (Australia) in relation to their physical habitat. In contrast to
expectations, and although most recruitment probably occurred at lower-altitudes, the
populations with a size structure and biomass density most likely to cause ecological
degradation occurred at intermediate altitudes. Furthermore, the distribution of smaller
carp (less than or equal to 100 mm, and less than or equal to 300 mm) indicated that the
regulation of river flows does not always favour carp populations, particularly during
drought conditions. Nevertheless, it was concluded in a review of the carp literature,
which incorporated the findings of this study, that invasion by alien carp is most
successful in streams with formerly highly variable flows that are now subject to flow
regulation. Moreover, carp are likely to enhance their advantage in these waters through
habitat modification.
23
Stendera, Sonja Johnson Richard K. "Spatiotemporal variability of chemistry and biota in boreal surface waters : a multiscale analysis of patterns and processes /". Uppsala : Swedish University of Agricultural Sciences, 2005. http://diss-epsilon.slu.se/archive/00000956/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005.Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts co-authored with R.K. Johnson. Issued also electronically via World Wide Web in PDF format; online version lacks appendix.
24
JIANG, HUAN. "Ecological Risk Assessment of Salts in Swedish Freshwater Ecosystem : A preliminary assessment for invertebrates and vertebrates". Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16578.
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Widenfalk, Anneli. "Interactions between pesticides and microorganisms in freshwater sediments : toxic effects and implications for bioavailability /". Uppsala : Dept. of Environmental Assessment, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200523.pdf.
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Michael, Taylor. "Invertebrate Activities in Wetland Sediments Influence Oxygen and Nutrient Dynamics at the Sediment-water Interface". Kent State University Honors College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1525568331200468.
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Uys, Amanda Cloete. "The invertebrates of temporary rivers in the Eastern Cape, South Africa". Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1004908.
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Temporary rivers in dryland regions are subject to highly variable and unpredictable rainfall and flow, and are considered unstable systems relative to perennial rivers of temperate zones. Little is known of the ecology of South Africa's temporary rivers, despite their abundance. The research presented focusses on the aquatic invertebrates inhabiting intermittently-flowing rivers in the 'arid corridor' of the Eastern Cape, South Africa. The major aims of the work were: to investigate which invertebrates inhabit these rivers, how the fauna is affected by environmental variability at various spatial and temporal scales, whether or not a characteristic fauna can be associated with these rivers or the hydrological phases which characterise them, and to establish to what extent faunal overlap occurs between different temporary rivers and between natural and modified temporary and perennial rivers. Research results indicate that the fauna of the Eastern Cape temporary rivers shows little structure at the scales of investigation, and that communities are generally non-equilibrial in character. The major forces shaping the biota are considered to be physical rather than biological, and the most important of these are: present and antecedent hydrological conditions and their duration; time of year; and biotope character, extent and heterogeneity. Three groups of fauna were identified as inhabitants of the temporary rivers: 'residents', 'facultative taxa' and 'opportunist colonists'. Taxa were tentatively allocated to these groups. Faunal resemblance was fairly high in Eastern Cape temporary rivers at the level of family, but not at more detailed taxonomic levels. A comparison between faunas of temporary and perennial rivers in different regions of South Africa illustrated the influence of geographical location on diversity. Within regions, however, there was no indication that perennial rivers were more diverse than intermittent rivers. The relatively high diversities in temporary rivers in this study are attributed at least in part to the heterogeneity in surface water conditions over time. A conceptual framework envisioning a continuum between perennial and temporary rivers is proposed as a basis for ongoing research into these rivers. A supporting terminology for the range of river flow types in South Africa is presented.
28
Weiss, Steven P. "Bioassessment of the West Branch of the Wolf River /". Link to full text, 2007. http://epapers.uwsp.edu/thesis/2007/weiss.pdf.
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Veenstra-Quah, Anneke Alison, i mikewood@deakin edu au. "The impact of stresses imposed on macroinvertebrate communities in two urban streams". Deakin University. School of Biological and Chemical Sciences, 1999. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20050815.102219.
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The aim of the project was to determine factors which explain the distribution of macroinvertebrates in two Melbourne streams both drastically affected by urbanisation. A detailed description is given of Dandenong Creek, flowing through the south-eastern suburbs, and Darebin Creek, in the northern suburbs, emphasising stream features likely, or known, to influence the drift and benthic fauna.
Faunal sampling was carried out in Dandenong Creek from June 1992 until July 1993, and in Darebin Creek from February 1995 until March 1998. Physicochemical parameters were also recorded. The collected data, together with previously existing data, were analysed using multivariate analyses: non-metric multi-dimensional scaling (NMDS); analysis of similarities (ANOSIM); matching biotic and abiotic variables using BIOENV, and principal component analysis (PCA). Various biotic and diversity indices were calculated in an attempt to identify the major factors responsible for the failure of the fauna to recover from previously more seriously degraded water quality.
The contribution of drift to the colonisation potential in Dandenong Creek appeared to be impacted by retarding basins, underground barrel-draining and channelization. Results also indicated that increased conductivity adversely affected the fauna in the lower reaches of Dandenong Creek. It was concluded that in Darebin Creek, high nutrient levels, as well as other pollutants, had resulted in low macroinvertebrate diversity in both the drift and benthos.
If, as this study suggests, faunal diversity is a valid measure of stream health, the following factors need to be addressed for catchment-wide, stream management: lack of riparian zone vegetation (increasing bank erosion and making the benthic habitat unstable, with greater temperature variability); control of stormwater runoff (flow variability, increased conductivity, nutrient levels, sediment loads, sewage effluent, industrial discharges and heavy metals), and to modify retarding basins to increase stream continuity.
30
Bernard, David P. "Impact of stream acidification on invertebrates : drift response to in situ experiments augmenting aluminum ion concentrations". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24478.
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Recent evidence strongly suggests that aluminum toxicity is important in determining the structural and functional characteristics of freshwater communities affected by acid precipitation. To determine the effect dissolved aluminum has on lotic invertebrates previously unexposed to anthropogenic acidification, experiments were carried out in a second-order headwater stream 50 km east of Vancouver, British Columbia during August 1982. In three separate experiments, HC1 and/or A1C1₃ were added to Mayfly Creek during daylight hours, increasing acidity from pH 6.9 - 7.0 to pH 5.8 - 6.0 and total aluminum from < 0.1 mg/L to > 1.0 mg/L. Biological response was monitored by sampling invertebrate drift with 86 Mm nets.
Relative to an unmanipulated, upstream control site, drift density doubled in response to added H⁺ alone (pH 5.9). When Al₃⁺ was added (pH 5.9) drift density increased fourfold. Following 48 h continuous dosing with HC1 (pH 5.9) there was an even greater response to added Al₃⁺.
Ephemeroptera were able to detect dissolved aluminum and responded almost immediately (within 45 min). Similarly, Trichoptera and Chironomidae detected increased H⁺ concentrations and responded immediately. Response to
augmented Al₃⁺ by Trichoptera, Hydracarina, and Chironomidae was delayed 6 h. However, pre-exposing animals to 48 h HC1 resulted in enhanced aluminum sensitivity for Chironomidae and for Simulium and Plecoptera, which had not responded within 10 h to H⁺ or Al₃⁺ alone. It is proposed that rapid increases in drift density are due to behavioral escape responses, while delayed responses are probably associated with physiological impairment. Evidence was also obtained suggesting that during early stages of morphological development Ephemeroptera and Chironomidae are more sensitive to increased Al₃⁺ and H⁺ concentrations than during later developmental stages.
In laboratory experiments using artificial stream channels, Chironomidae larvae and Ephemeroptera nymphs were exposed to CI⁻ and H⁺ concentrations, equal to those during field experiments. Results showed that drift behavior in these animals is not stimulated by mildly elevated chloride concentrations.
These studies demonstrate that increased dissolved aluminum concentrations intensify biological response to acidification, and confirm acid sensitivity patterns for Ephemeroptera and Chironomidae reported by others. The observed acid
insensitivity of Plecoptera, simuliids, and Trichoptera also conforms to previously described patterns.
Experimentally manipulating this community produced results closely resembling those obtained in similar studies for areas currently affected by acid precipitation. The major difference in results between studies is that invertebrate communities previously unexposed to acidification contain more species sensitive to mild acidification. These latter animals are particularly sensitive to the presence of elevated dissolved aluminum concentrations.Science, Faculty of
Zoology, Department of
Graduate
31
Gustafsson, Pär. "Forest – stream linkages : Brown trout (Salmo trutta) responses to woody debris, terrestrial invertebrates and light". Doctoral thesis, Karlstads universitet, Avdelningen för biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-6731.
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Forests surrounding streams affect aquatic communities in numerous ways, contributing to energy fluxes between terrestrial and lotic ecosystems. The five papers in this thesis focus on woody debris, terrestrial invertebrates and light, three factors influenced by riparian zone structure, potentially affecting streams and brown trout (Salmo trutta). The individual strength of these stressors and their interactions with each other are not well studied, and their qualitative effects may differ both spatially and temporally as well as with the size-structure of specific fish populations. Using a combination of laboratory and field experiments, I examined the effects of woody debris, terrestrial invertebrates and light on prey availability and on the growth rates, diets and behavior of different size-classes of trout. My field experiments showed that addition of high densities of large wood affected trout growth in a positive way. This positive effect of large wood on trout growth may be related to prey abundance, as indicated by the high standing crop of aquatic macroinvertebrates on the wood. The positive effects on trout may also be related to decreased energy expenditures in wood habitats, as trout increased the ratio between numbers of prey captured and time spent active and that swimming activity and level of aggression decreased as wood densities were increased in a laboratory experiment. Terrestrial invertebrates are generally assumed to be a high quality prey resource for fish and my field experiments showed that reduction of terrestrial invertebrate inputs had a negative effect on trout growth. The availability of terrestrial prey in the stream was also coupled to trout diet and linked to growth, as fish with high growth rates had high proportions of terrestrial prey in their diets. Light, measured as PAR, did not have an effect on chlorophyll biomass, nor was there an effect on aquatic macroinvertebrates or trout. Hence, even if light levels were sufficient for increased photosynthesis, other factors such as low nutrient content may have limited the effects. Many of my results were dependent on fish-size. I observed, for example, that large trout had higher capture rates on surface-drifting terrestrial prey than small trout when prey densities were intermediate or high, but at low prey densities, the consumption of terrestrial prey by large and small trout were similar. Moreover, although large wood and terrestrial invertebrates affected growth of both small and large trout, the effects were generally more consistent for large trout. Although changes in riparian forests typically induce an array of interacting effects that certainly call for further research, the overall conclusion from this thesis is that many of the factors I have studied have profound effects on stream biota and trout. The positive effects from large wood also propose that adding trees to streams may partly compensate for negative effects associated with riparian deforestation.
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Mabidi, Annah. "Freshwater invertebrate assemblages of the Eastern Cape Karoo region (South Africa) earmarked for shale gas exploration". Thesis, Nelson Mandela University, 2017. http://hdl.handle.net/10948/13713.
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The Eastern Cape Karoo region is semi-arid with highly variable rainfall. This variability in rainfall sustains a mosaic of surface freshwater bodies that range from permanently to temporarily inundated. These waterbodies provide habitats for diverse invertebrate assemblages. The imminent hydraulic fracturing for shale gas has a potential to modify the water regime, with particular risk of salinisation. Accumulation of salts in freshwater wetlands results in loss of biodiversity, as invertebrate species shift from salt intolerant to salt tolerant species. This study therefore aims to expand on existing knowledge and provide new information on the distribution, diversity and structure of macroinvertebrate assemblages associated with various freshwater bodies in the region prior to shale gas exploration. Limnological and ecological aspects of thirty-three waterbodies (rivers, dams and depression wetlands) were investigated between November 2014 and March 2016. An experimental study on the effects of salinity on hatching success of branchiopod resting eggs was also included in the research. Rivers were characterised by high conductivity and depression wetlands by high turbidity, while dams had relatively higher pH than the other two waterbody types. In terms of global phosphorus interpretation guidelines, the results indicate that freshwater systems in the study region are predominantly eutrophic, indicating that agricultural run-off, particularly from livestock dung (goats, cattle and sheep), is an important source of phosphorus in the freshwater systems studied. Our results revealed new distribution records for branchiopod crustaceans in the Eastern Cape region, including the first record of Laevicaudata. Results showed that the sampled variables were unable to explain the variation in physicochemistry and invertebrate assemblage of several sites. Waterbody type, whether a depression wetland or a river, was the only factor that consistently showed an effect on the composition of both physicochemical data and invertebrate data. Depression wetlands ranged from completely bare to being extensively covered by macrophytes. Therefore, the effect of macrophyte cover in structuring macroinvertebrate assemblages was the focus of further investigation. The results indicated that the macrophyte cover gradient had little influence on the structure of the invertebrate assemblages in the depression wetlands, while only the presence/absence of vegetation significantly influenced the structure of the invertebrate assemblages in these systems. Surface area, dissolved inorganic nitrogen and pelagic chlorophyll-a were the environmental variables that best explained the variation in the macroinvertebrate assemblages among the sites. However, the differences in macroinvertebrate richness, abundance and distribution patterns among sites were only weakly influenced by local and regional environmental factors. These findings suggest that invertebrate in temporary wetland systems are adapted to the highly variable nature of temporary habitats, thus the influence of local variables is negligible. Results of the experimental study, on the effect of salinity on hatching success of branchiopod resting eggs, revealed that hatchling abundance and diversity of large branchiopods was significantly reduced at salinities of 2.5 g L−1 and above. Salt-tolerant taxa such as Copepoda and Ostracoda were the only ones to emerge in the highest salinity of 10 g L−1. Thus, should the region continue to experience increasing aridity and possible shale gas development, which all aggravate the salinisation problem, severe loss of branchiopod diversity (Anostraca, Laevicaudata, Spinicaudata and Notostraca) is likely to occur. This may lead to considerable decline in invertebrate diversity in the region, with cascading effects on food webs and ecosystem functions. The findings of this study can potentially be used in comparative studies on wetland invertebrate ecology in other semi-arid regions and in the formulation of policy and strategies for biodiversity conservation.
33
Orzetti, Leslie LuChar. "Stream community structure an analysis of riparian forest buffer restoration in the Chesapeake Bay watershed /". Full text available online (restricted access), 2004. http://images.lib.monash.edu.au/ts/theses/Orzetti.pdf.
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Rogers, Megan Bryn. "Woody debris and macroinvertebrate community structure of low-order streams in Colville National Forest, Washington". Connect to this title online, 2003. http://www.dissertations.wsu.edu/Thesis/Fall2003/m%5Frogers%5F121503.pdf.
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Cheung, Ka-wing, i 張嘉穎. "Spatial and seasonal variations of freshwater macroinvertebrates, odonata and waterbirds in Luk Keng marshland, Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290951.
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Castro, López Daniel. "Riparian forest quality, land-use dynamics and their influence on macroinvertebrate communities. An evaluation of the ecological status of Pesquería River (N.E., Mexico)". Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668280.
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Worldwide, biological diversity is declining at an unprecedented rate. Current environmental changes are causing water, ecological and biodiversity crises that, coupled with climate change, are affecting landscape patterns and sustainable development efforts. Thus, anthropogenic pressures are changing the world's landscapes in pervasive ways. Additionally, these anthropogenic pressures on the natural landscape have been associated with changes in landscape and to the ecological condition of freshwater ecosystems. Therefore, freshwater ecosystems, particularly rivers, must be examined in detail, and it is important to consider their relationship with terrestrial ecosystems, particularly the “transitional land-water” ecosystems (i.e. the riparian channel). This is particularly important for developing countries given to their ecosystems are constantly threatened by anthropogenic activities. Additionally, the lack of research, proper legislation and management hinders the restoration and conservation plans for their freshwater ecosystems. Within this context, the overarching goal of this PhD thesis is to evaluate the ecological status of the Pesquería River and assess the effects of landscape degradation along its riparian channel. Since changes in landscape composition can significantly affect a riparian channel, we aimed to evaluate how said changes can also impact biological quality and subsequently affect the ecological integrity of a river ecosystem. We focused into provide simple and reliable methods to define the ecological status and discern the effects of landscape degradation on the ecological state of the Pesquería River using a variety of tools for diagnosis and monitoring. On this PhD thesis we explored land-use cover/change dynamics (LUCCD) in the riparian channel also we describe the land use processes in the riparian zone during the period 1976-2016 in order to ascertain whether land use dynamics can provide useful information about the current ecological status of a riparian zone (Chapter 1). Additionally, we evaluated the riparian forest quality of the Pesquería River (Chapter 2) using an adaptation of the riparian forest quality index (QBR), modifying it for the specific local conditions (QBR-RNMX). Finally, we investigate how the macroinvertebrate communities in the Pesquería River are affected by different land use covers and assess their potential use as bioindicators to evaluate the ecological status of Mexican semi-arid rivers with similar conditions (Chapter 3).
On this PhD thesis we demonstrated that LUCCD analysis at riparian channel level should be viewed as a key tool for the improvement of conservation policies targeting freshwater ecosystems in Mexico. We remark the importance of consider the riparian buffer width as an ecosystem, not as a federal area, in order to protect the freshwater ecosystems in Mexico. We corroborated the efficiency of the adaptation of the QBR-RNMX also we recommend the application of the index annually to evaluate the riparian forest’s quality, and to assess its ecological status. This may be used for the establishment of restoration plans in high-impact zones and contingency plans to eliminate invasive species along the Pesquería River. This PhD thesis has provided eleven biological metrics and thirty-two representative taxa that can be used as bioindicators in future research. However, more studies, and especially the relationship of this index with the river pressures are necessary to establish an index for the Pesquería River in the future. Furthermore, in the general discussion we propose a macroinvertebrate-based index (BMWP-system) as a first step for the evaluation of the ecological status of the river.
Finally, this thesis highlights the lack of research and the bad current ecological status of the Pesquería River. Our findings suggest the creation of a Mexican framework similar to the European Water Framework Directive, where the ecological quality of the river should be the main objective of riparian ecosystems recovery.A nivel mundial, la diversidad biológica está disminuyendo a un ritmo sin precedentes. Los cambios ambientales actuales están causando crisis hídricas, ecológicas y de biodiversidad que, junto con el cambio climático, están afectando los patrones del paisaje y los esfuerzos de desarrollo sostenible. Por lo tanto, las presiones antropogénicas están cambiando los paisajes del mundo de manera generalizada. Además, estas presiones antropogénicas en el paisaje natural se han asociado con cambios en el paisaje y en las condiciones ecológicas de los ecosistemas de agua dulce. Esto es importante para los países en desarrollo, dado que sus ecosistemas están amenazados por actividades antropogénicas. Además, la falta de investigación, legislación y gestión dificultan los planes de restauración y conservación de sus ecosistemas de agua dulce. En este contexto, el objetivo general de esta tesis doctoral es evaluar el estado ecológico del río Pesquería y evaluar los efectos de la degradación del paisaje a lo largo de su canal ribereño. En esta tesis doctoral demostramos que el análisis de dinámicas de uso de suelo a nivel de los canales ribereños debe verse como una herramienta para la mejora de los ecosistemas acuáticos en México. Observamos la importancia de considerar el ancho del amortiguador ribereño como un ecosistema, no como un área federal, para proteger los ecosistemas acuáticos de México. Corroboramos la eficiencia de la adaptación del QBR-RNMX para usarse en el establecimiento de planes de restauración y contingencia para eliminar especies invasoras del río Pesquería. Esta tesis doctoral proporcionó once métricas biológicas y treinta y dos taxones representativos que pueden usarse como bioindicadores en futuras investigaciones. Sin embargo, se necesitan más estudios, y especialmente la relación de este índice con las presiones del río para establecer un índice para el río Pesquería en el futuro. Además, en la discusión general, proponemos un índice basado en macroinvertebrados como un primer paso para la evaluación del estado ecológico del río. Finalmente, nuestros hallazgos sugieren la creación de un marco mexicano similar a la Directiva Marco del Agua Europea, donde la calidad ecológica del río debería ser el objetivo principal de la recuperación de los ecosistemas ribereños.
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Engel, Sarah Rose. "The effectiveness of using volunteers for biological monitoring of streams". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31060.
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An increase in public environmental awareness and a decrease in resources within government regulatory agencies have led to a larger interest in volunteer biomonitoring programs. Government agencies are currently using volunteer data for official purposes with increasing frequency, but questions have been raised about the validity of the data collected by volunteers who have only limited training and experience. Therefore, we conducted a detailed study to assess, modify, and validate the Virginia Save-Our-Streams (SOS) program, which is a volunteer organization collecting macroinvertebrate data. Sites were sampled using professional methods concurrently with volunteers who utilized the SOS protocol. The volunteer samples were retained for further laboratory analysis. In addition, numerous sites previously sampled by volunteers were re-sampled using professional methods. The data were statistically analyzed to determine if the results of volunteers and professional aquatic biologists were correlated and if they arrived at the same conclusions about ecological condition. It was determined that the Virginia SOS method, and probably other similar volunteer methods, consistently overrate ecological condition. This means that streams impaired by pollution could go unreported, if they are monitored exclusively by volunteers. The cause of this overestimation was determined to be the overly simplistic SOS metric, which is based solely on the presence or absence of taxa. The SOS protocol for data analysis was made more quantitative by developing a multimetric index that is appropriate for use by volunteers. The SOS sampling protocol was modified slightly to obtain actual counts of the different kinds of macroinvertebrates, which allowed for calculation of metrics. Sorting effort and taxonomic level of identification were not changed so that currently participating volunteers would not be excluded because of the need for expensive equipment or advanced technical training. The modified SOS protocol was evaluated by a different set of concurrent samples taken by volunteers and professionals, but using the same statistical techniques. The modified SOS protocol proved to be feasible for volunteers. The new SOS multimetric index correlated well with a professional multimetric index. The conclusions about ecological condition derived from the volunteer multimetric index agreed very closely with those made by professional aquatic biologists. This study demonstrated that volunteer biomonitoring programs can provide reliable data, but every volunteer program needs to be thoroughly validated by statistical comparisons to the professional methods being used in that area.Master of Science
38
Mazzini, Flávia. "Efeitos da resolução taxonômica de invertebrados bentônicos no diagnóstico da qualidade de ecossistemas lóticos". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-22102007-111107/.
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Nas últimas décadas, tem-se observado uma expressiva queda da qualidade ambiental e perda de biodiversidade nos ecossistemas aquáticos em função de múltiplos impactos advindos de atividades antrópicas. Dessa forma, considerando-se que a estrutura das comunidades pode ser alterada por tais perturbações, diversos métodos têm sido propostos para avaliações da qualidade nesses ecossistemas, destacando-se, entre eles, o uso dos macroinvertebrados bentônicos. Alguns estudos empregando estes indicadores defendem a sua identificação ao nível genérico por fornecer maior número de informações, resultar em classificações ambientais mais confiáveis e apresentar melhor capacidade de distinção entre os pontos, quando comparado aos níveis de resolução mais abrangentes. Entretanto, na maioria dos trabalhos a identificação desse grupo restringe-se ao nível de família, principalmente em função da economia nos recursos despendidos durante a identificação o que não se justifica caso este nível não retenha informações suficientes para que os objetivos sejam alcançados. Neste trabalho, esse conflito foi avaliado através da comparação de avaliações biológicas decorrentes da aplicação de índices estruturais baseados na identificação de Chironomidae, ao nível genérico com o de sub-família/tribo. Foram utilizadas amostras de organismos bentônicos, bem como os dados físicos, químicos e microbiológicos coletados em sete pontos de amostragem que fizeram parte de vários projetos da CETESB (Companhia de Tecnologia de Saneamento Ambiental), conduzidos ao longo de diferentes anos e classificados, de acordo com o ICBRIO (Índice da Comunidade Bentônica para rios) em ambientes de qualidade péssima, ruim, regular, boa e ótima. As coletas foram padronizadas em relação ao período (inverno) e ao tipo de hábitat amostrado (margem deposicional). As amostras foram obtidas em triplicata com o auxílio de pegadores (Ponar e Petersen modificado) e o material selecionado em rede com abertura de malha 0,5 mm. A contagem e identificação dos organismos foram feitas com o auxílio de estereomicroscópio, microscópio óptico e bibliografia especializada. Para definir o gradiente de qualidade, as variáveis ambientais foram submetidas a uma Análise de Agrupamento pelo método de Ward, empregando-se a Distância Euclidiana Simples. Já os valores de densidade foram reunidos em uma matriz de distância de Bray-Curtis agrupada pelo método de média de grupo não ponderada a fim de verificar o grau de similaridade entre os pontos e se o nível de identificação taxonômica interfere nas associações formadas. Com o intuito de verificar a sensibilidade do nível taxonômico do dado ao gradiente de qualidade ambiental, bem como testar a possível influência do refinamento taxonômico na sensibilidade do ICBRIO foram empregadas as métricas Riqueza, Diversidade de Shannon-Wiener, Índice de Comparação Seqüencial, Dominância de Grupos Tolerantes e Riqueza de Táxons Sensíveis. Tendo por objetivo o diagnóstico das condições ambientais, com redução de custos e tempo de manipulação das amostras, mas com informações relevantes que subsidiem os tomadores de decisão, o presente trabalho vem descartar o emprego do nível de resolução genérico na identificação das larvas de Chironomidae. Os resultados expostos confirmaram a aplicabilidade do ICBRIO com a identificação deste grupo aos níveis de sub-família/tribo na avaliação da qualidade ambiental, demonstrando não serem necessárias eventuais alterações nos seus moldes.In the last decades, it has been observed an expressive deterioration of the environmental quality and biodiversity loss in the aquatic ecosystems as function of anthropogenic activities. Considering that communities' structure can be altered by such disturbances, several methods have been proposed for quality assessment in those ecosystems, standing out, among them, the use of the benthic macroinvertebrates. Some studies using these indicators defend the generic level identification as they supply more information, result in more reliable environmental classifications and present better distinction capacity among sites, when compared to broader levels. However, in most of the works the identification of this group is limited to the family level, mainly due to resources saving during the identification, which is not justified in the case this level misses information to classification aims. In this work, comparison of current biological evaluations through Chironomidae identification structural indexes at the generic level with the one at sub-family/tribe was evaluated. Benthic organisms samples, as well as physical, chemical and microbiological data were collected in seven sampling sites, from several projects taken along different years by CETESB (Company of Technology of Environmental Sanitation), which classified the environment as, according to ICBRIO (Benthic Community Index for rivers), worst, bad, regular, good and excellent quality. The collections were standardized to winter period and to type of sample habitat (depositional river margin). Triplicates were obtained with modified Ponar and Petersen grabs on retained material by 0.5mm-mesh sieve. Counting and identification based on specialized literature were done with the stereomicroscope, and optical microscope. To define the quality gradient, the environmental variables were submitted to a Cluster Analysis by the Ward method, using the simple Euclidean Distance. Density values were lumped on a Bray-Curtis distance matrix by the Unweighted Pair Group method in order to verify the similarity degree among the points and the interferences of taxonomic identification level on the formed associations. Aiming to check the sensibility of the data taxonomic level to the environmental quality gradient, as well as to test the possible influence of taxonomic refinement in the ICBRIO's sensibility, several metrics (Richness, Shannon-Wiener Diversity Index, Sequential Comparison Index, Dominance of Tolerant Groups and Richness of Sensitive Taxa) were used. Seeking the diagnosis of the environmental conditions, reducing costs and manipulation time of the samples, but keeping relevant information to subsidize the policy managers, the present work discards the need of the generic resolution level in the Chironomidae larvae identification. The exposed results confirmed the applicability of ICBRIO with the identification of this group at sub-family/tribe levels on the environmental quality assessment, demonstrating no need of eventual modification in the method.
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Villamagna, Amy Marie. "Ecological effects of water hyacinth (Eichhornia crassipes) on Lake Chapala, Mexico". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26854.
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Water hyacinth (Eichhornia crassipes) is a floating non-native plant that has been reoccurring in Lake Chapala, Jalisco, Mexico for more than 100 years. In this research, I explore the effects of water hyacinth on freshwater ecosystems worldwide and specifically on Lake Chapala.
In chapter 1, I reviewed studies conducted on water hyacinth worldwide and found that the effects of water hyacinth on water quality are similar but the magnitude of effects is dependent on the percent cover and potentially the spatial configuration of water hyacinth mats. Water hyacinth's effect on aquatic invertebrates, fish, and waterbirds is less predictable and dependent on conditions prior to invasion. In chapter 2, I tested for relationships between percent water hyacinth cover and waterbird abundance, species diversity, community composition, and habitat use. In general, I found a weak positive relationship or no relationship between these variables. In Chapter 3, I monitored habitat use by American Coots (Fulica americana) in a variety of habitats around Lake Chapala. I found that the time spent in water hyacinth positively corresponded to the percent water hyacinth cover and that the time foraging in water hyacinth was positively related to the time spent in water hyacinth.
In Chapter 4, I compared invertebrate assemblages in open water to those within and at the edge of water hyacinth mats, emergent vegetation, and submerged trees. I also examined invertebrate assemblages within the roots of water hyacinth plants and compared assemblages between patch and shoreline water hyacinth plants. I found that density and taxonomic richness of water column invertebrates were generally higher in association with water hyacinth, but that mean percent cover of water hyacinth affected the magnitude of differences among habitats and vegetation types. I did not find significant differences in root invertebrate density and taxonomic richness between patch and shoreline water hyacinth plants. In chapter 5, I discuss how water hyacinth affected dissolved oxygen and water transparency on a small, localized scale, but was not the driving factor for seasonal differences. The overall results suggest that water hyacinth had a minimal ecological effect on Lake Chapala during this study.Ph. D.
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Seymour, Karen. "The influence of salmon presence on benthic communities in three Puyallup-White River tributaries". Online pdf file accessible through the World Wide Web, 2007. http://archives.evergreen.edu/masterstheses/Accession86-10MES/Seymour_K%20MESThesis.pdf.
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Untersteiner, Hubert. "Aquatic invertebrates as indicators to pollution-induced stress validation of the locomotory behaviour of freshwater and marine crustaceans as response to sublethal heavy metal stress". Saarbrücken Suedwestdeutscher Verlag fuer Hochschulschriften, 2009. http://www.svh-verlag.de.
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Carini, Giovannella, i n/a. "Effects of Contemporary and Historical Processes on Population Genetic Structure of Two Freshwater Species in Dryland River Systems (Western Queensland, Australia)". Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050113.081250.
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Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.
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Carini, Giovannella. "Effects of Contemporary and Historical Processes on Population Genetic Structure of Two Freshwater Species in Dryland River Systems (Western Queensland, Australia)". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367070.
Pełny tekst źródłaStreszczenie:
Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text
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Johansson, June. "Sediment chemistry and the potential toxicity to benthic invertebrates in sediments affected by acid sulfate soils : A study on freshwater and marine sediments in Västerbotten, Sweden". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-172323.
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The leakages of metals from acid sulfate soils and their potential toxicity to benthic invertebrates were studied in the sediment profiles of Lillkvasjön and Lövselefjärden - a lake and an estuary known to be affected by acid sulfate soils - in Västerbotten, northern Sweden. The concentrations of 25 different elements were analyzed throughout both sediment profiles through X-Ray Fluorescence (XRF) Spectrometer analysis. Organic matter was measured through loss-on-ignition (LOI). By performing correlation analysis and normalizations to LOI on all sediment variables, Cu, Fe, Ni, Pb, S and Zn were found to be leached from acid sulfate soils to both sites, while Mg and Mn were related to leakages from acid sulfate soils in Lövselefjärden. The concentrations of Cu (195 mg kg-1), Ni (55 mg kg-1), Pb (90 mg kg-1) and Zn (398 mg kg-1) in the surface sediment of Lövselefjärden were classified as potentially toxic to benthic invertebrates. In Lillkvasjön, Cu (210 mg kg-1) and Ni (87 mg kg-1) were classified to have an increased risk of negative impacts on benthic invertebrates, while the concentrations of Pb (121 mg kg-1) and Zn (329 mg kg-1) were likely to low to have any negative effects. These results strengthen previous finds of impacts from acid sulfate soils in the two catchment areas and elucidate the importance of further studies on the impact of acid sulfate soils on benthic invertebrates.
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Muir, William Douglas. "Macroinvertebrate drift abundance below Bonneville Dam and its relation to juvenile salmonid food habits". PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/4108.
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There is a paucity of information concerning the invertebrate food resources available to juvenile salmonids in the Columbia River as they migrate seaward. Construction of mainstream dams has altered the temperature cycle, flow regime, and substrate which indigenous invertebrates were adapted to. Studies on how the macroinvertebrate community has adapted to these alterations have been neglected. This study was undertaken to help fill this void.
Macroinvertebrate drift samples were collected over a three year period in the Columbia . River downstream from Bonneville Dam. Samples were collected with a D-ring plankton net fished on the bottom for one-half hour. Two sites were sampled; Ives Island (RKM 230), from 1987 through 1989, and Lady Island (RKM 193), in 1988 and 1989.
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Browne, Samantha. "The role of acute toxicity data for South African freshwater macroinvertebrates in the derivation of water quality guidelines for salinity". Thesis, Rhodes University, 2005. http://eprints.ru.ac.za/174/.
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Perfect, Charles. "From engineered channel to functioning stream ecosystem : rates, patterns and mechanisms of development in a realigned river channel". Thesis, University of Stirling, 2010. http://hdl.handle.net/1893/2431.
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1. Realigning rivers is becoming common as a solution to conflicting needs of land development and ecosystem preservation. Although an increasing number of projects are monitored, exactly how these channels develop as functional stream ecosystems is still poorly understood. Mining in the upper catchment of the River Nith (Scotland) required the realignment of 3km (approx.) of river. The engineered channel was designed around sound geomorphological principles of sediment transport and supply with a sinuous planform and pool-riffle sequences along the installed gravel-bed. 2. A comprehensive survey covering biotic and abiotic development was devised and implemented to test models and hypotheses relating to the development riverine habitats over the first three years. 2. Physical habitat development at the reach scale was investigated using fixed-point photography and differential GPS surveys of the thalweg and of cross-sectional form every 100m. This revealed the development of a relatively diverse streambed habitat in response to both the channel slope and planform. However, other than at meander bends where asymmetry developed over several years, little change was observed to the form of the engineered riverbanks. 3. Kick-net surveys of benthic invertebrate communities at 10 sites showed a negative relationship between specific measures of diversity and downstream distance during the early stages of development. (e.g. Richness with chainage at the 6 month stage) but the relationship degrades rapidly and is likely in part to appear as a result of low population densities. 4. Survey of transects through the riparian zone perpendicular to the river indicated that colonisation by vegetation is also related to distance along the realignment but physical habitat and geographical factors play a more dominant role over development (Canonical correspondence analysis of vegetation data in 2007) 5. Many of the indices of diversity for both biotic and abiotic elements of the ecosystem proved ineffective at detecting development at the reach scale. This may be because significant changes occur at a smaller scale than was detected by the surveys. It is likely that greater resolution is required to detect more ecologically meaningful relationships and patterns. 6. Overall study shows constructed realignments can rapidly develop a diverse streambed community within 24 months. Riparian communities are slower to develop because of the slow development of riverbank habitat diversity. Other ecosystem properties such as resilience and connectivity may take much longer.
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Schwarz, Simon [Verfasser]. "Effects of the anti-inflammatory drug diclofenac and the beta-blocker metoprolol in brown trout Salmo trutta f. fario and freshwater invertebrates at different levels of biological organization / Simon Schwarz". Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1228814902/34.
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Nebra, Costas Alfonso. "Ecology and bioindicator potential of benthic macroinvertebrates in a Mediterranean salt wedge estuary: the Ebro River case". Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/385277.
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The Ebro Delta-Estuary complex is one of the largest wetland areas in the western Mediterranean, and it is considered one of the most important estuarine zones in Europe. In 2013, the Ebro watershed, including its deltaic plain, was declared World Biosphere Reserve by the UNESCO. Due to its singularity, a total of 7.736 ha of Delta are protected under the Spanish Natural Park figure (including coastal lagoons, freshwater springs, bays and adjacent coastline) which stands out by its faunal (mainly, ornithological and ichthyological) and halophilic floral composition. The Ebro River flows into the Mediterranean Sea and forms a salt wedge or highly stratified estuary, a unique estuary type only found in microtidal coasts worldwide. Diverse human activities occur in this area such as tourism, shooting, commercial fishing and agriculture, as a consequence the entire Delta-Estuary complex is under permanent anthropogenic pressures threatening its ecological integrity; therefore, its conservation should be a priority task.
The main objective of the present PhD thesis was to analyze the ecology of the benthic macroinvertebrate community from the Ebro Estuary, in order to evaluate its potential use as biological indicator of highly stratified Mediterranean estuaries. To achieve this goal the study of the macroinvertebrate community was carried out at a high level of taxonomic resolution and its spatiotemporal dynamics in relation with the estuarine environmental gradients was assessed. An exhaustive environmental description of benthic condition of the Ebro Estuary was done, including water physico-chemistry, grain size characterization and total organic estimation in sediments. Furthermore, due to the relevance of river discharge on salt wedge dynamics and therefore on estuarine benthic ecology, a comparison between current salt wedge dynamics and past near natural conditions was done using historical data available at the Ebro basin authority database. Finally, the bioindicator potential of macroinvertebrates to assess the ES according to the WFD criteria was examined throughout the analysis of the response of macrozoobenthos based metrics to the main human pressures in the Ebro estuary, nutrient enrichment and altered flow regime.El objetivo general de la presente tesis fue describir la ecología de la comunidad de macroinvertebrados bentónicos del estuario del Río Ebro, un estuario de cuña salina o altamente estratificado. En concreto esta tesis exploró a un alto nivel de resolución taxonómica la dinámica espacio-temporal de la comunidad de macroinvertebrados en relación con los gradientes ambientales de un estuario de este tipo, con el propósito de evaluar su uso potencial como indicadores biológicos en otros estuarios mediterráneos altamente estratificados. La condición bentónica actual del estuario del río Ebro fue descrita de manera exhaustiva, incluyendo la caracterización físico-química del agua (concentración de nutrientes, contenido de sólidos en suspensión, oxígeno disuelto, pH, temperatura y salinidad) así como un análisis granulométrico del sedimento y la estimación del contenido en materia orgánica. Los datos físico-químicos fueron utilizados para la estimación de un gradiente de contaminación orgánica mediante la técnica de PCA. Además, debido a la relevancia del caudal del río en la dinámica de la cuña salina (avance, retirada y permanencia) y por lo tanto en la ecología bentónica del estuario, se comparó la dinámica actual de la cuña salina, gravemente alterada por la regulación del caudal, con la dinámica natural de la cuña salina que se obtuvo a partir de datos históricos disponibles en la página web de la Confederación Hidrológica del Ebro. Finalmente, el potencial bioindicador de los macroinvertebrados, con el fin de determinar el Estado Ecológico de acuerdo con los criterios de la DMA, fue evaluado mediante el análisis de la respuesta de varios índices bióticos basados en macroinvertebrados en relación con las principales presiones antrópicas que afectan al estuario del Ebro, contaminación orgánica y la alteración hidrológica. Los resultados obtenidos evidencian la relevancia de los macroinvertebrados en el funcionamiento ecológico del estuario así como su idoneidad como indicadores biológicos en relación con la contaminación orgánica Las principales conclusiones obtenidas en esta tesis son: 1. La comunidad actual de macroinvertebrados del estuario del Ebro difiere en gran medida a la encontrada en la década de los 90 cuando la condición de anoxia, debida a un exceso de materia orgánica de origen eutrófico, impedían el establecimiento de comunidades biológicas. La comunidad actual de macroinvertebrados mostró valores excepcionalmente altos de riqueza (213 taxones) comparado con otros estuarios templados; los moluscos, poliquetos y crustáceos fueron los grupos dominantes en términos de riqueza y de abundancia. 2. Como consecuencia de la regulación hidrológica a la que está sometido el tramo bajo del río Ebro, la dinámica de la cuña salina está gravemente alterada causando largos períodos de presencia de cuña salina y de estratificación de la columna de agua. La presencia de cuña salina divide al estuario del Ebro en dos tramos opuestos en función de sus características limnológicas; aguas arriba de la cuña, un tramo con características fluviales y una comunidad de macroinvertebrados dulceacuícola (alto estuario) y aguas abajo un tramo estuarino con agua con salinidades prácticamente marinas debido a la escasa mezcla con el agua del río y una comunidad de macroinvertebrados de origen marino (bajo estuario). 3. El cambio brusco de salinidad fue el principal factor que determinó la estructura de la comunidad de macroinvertebrados del estuario del Ebro. Debido a la práctica inexistencia de agentes de mezcla entre la capa de agua dulce y la marina, el intercambio de materiales y de organismos es muy limitado, como consecuencia la distribución de la comunidad a lo largo del estuario encaja con un patrón de turnover o sustitución total. Este patrón junto con las características homogéneas de ambos ambientes (alto y bajo estuario) sugieren que el estuario del Ebro está funcionando en términos de fronteras ecológicas como un ecotono. 4. La estaciones de muestreo cercanas al punto nulo o nodal (punto donde contactan ambas capas de agua y con valores de velocidad cercanos a cero) mostraron los valores más bajos de riqueza y abundancia debido a que esta zona de mayor estrés dentro del estuario. 5. Durante la última década el estado químico del estuario del Ebro ha mejorado debido a la disminución de los aportes de nutrientes, en especial de fósforo, en toda la cuenca. Esto llevó a la mitigación del proceso de eutrofización y a una oligotrofización del estuario que actualmente recibe menos aportes de materia orgánica atenuando su impacto y reduciendo los eventos de anoxia e hipoxia. Como resultado de esta mejora, la comunidad de macroinvertebrados ha sido capaz de recolonizar el estuario alcanzando un alto grado de complejidad. 6. La comunidad de macroinvertebrados demostró su capacidad de respuesta frente a las principales presiones que afectan al estuario del Ebro. Los parámetros de la comunidad disminuyeron hacía el punto nodal en respuesta al incremento de factores de estrés hidrológico y al incremento de la contaminación en el punto nodal debido a la circulación convergente. 7. La alteración hidrológica de la dinámica de la cuña salina creó una estabilidad artificial en las condiciones ambientales, este hecho favoreció a la comunidad de macroinvertebrados. Como consecuencia tras la aplicación de varios índices biológicos se identificó una respuesta paradójica a esta presión, a mayor grado de alteración hidrológica mayor complejidad en la comunidad y por lo tanto mejor estado ecológico. Este resultado evidencia que es necesaria una aproximación diferente para la determinación del estado ecológico en cuencas mediterráneas donde los aspectos hidrológicos están ganando en relevancia en comparación con la calidad del agua y del sedimento.
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梁士倫 i Sze-lun Leung. "Scale-dependent effects of spatial and temporal variability on benthicmacroinvertebrate communities in Hong Kong streams". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243319.
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