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Avaliação dos impactos da visitação pública no rio Formoso, Bonito, MS, Brasil: subsídios à gestão ambiental do turismo em áreas naturais; Assessment of the impacts of public visitation at Formoso river, Bonito, MS: subsidies to the environmental management of the tourism in natural areas

Medina Júnior, Paulino Barroso
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/10/2007 PT
Relevância na Pesquisa
46.62%
Visando compreender os impactos da visitação pública sobre ecossistemas aquáticos continentais, desenvolveu-se o presente estudo no rio Formoso, Planalto da Bodoquena, Mato Grosso do Sul, Brasil. Através de um estudo de caso, buscou-se caracterizar os impactos provocados pelas diferentes modalidades de uso público no rio Formoso, considerando o emprego de variáveis físicas e biológicas como indicadoras do impacto da visitação pública em um período de alta temporada, carnaval de 2006. Complementarmente, para melhor compreender a relação entre os impactos impressos no ambiente e o uso predominante na região, foram caracterizados aspectos da relação dos empreendimentos turísticos com os ecossistemas aquáticos no Planalto da Bodoquena, a estrutura dos empreendimentos turísticos abertos ao uso público ao longo do rio Formoso e o perfil e aspectos da percepção ambiental dos visitantes desses empreendimentos. Os dados foram obtidos a partir de pesquisa documental, aplicação de questionários aos visitantes do rio Formoso e coleta em campo de dados relativos às variáveis físicas e biológicas descritoras dos diferentes compartimentos do ecossistema aquático. Os seguintes resultados ficaram evidenciados: 1. Os ambientes aquáticos são os atrativos naturais mais demandados pelos empreendimentos de turismo e visitantes; 2. os balneários exibem os maiores níveis de impacto em todos os compartimentos do ecossistema aquático analisado; 3. a movimentação da água e o pisoteio do fundo são as interferências da visitação pública mais pronunciadas sobre o rio Formoso; 4. as áreas mais impactadas são aquelas que recebem os visitantes com menos exigência ambiental; 5. as variáveis transparência da água...

Ecological integrity assessment in aquatic ecosystems: A multi-scale approach towards the definition of the ecological status of Mediterranean reservoirs

Sampaio, Edna Carla Janeiro Cabecinha da Câmara
Fonte: Universidade de Trás-os-Montes e Alto Douro Publicador: Universidade de Trás-os-Montes e Alto Douro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
46.65%
Tese de Doutoramento em Ciências do Ambiente; Mundialmente os sistemas aquáticos têm sido afectados por diversas pressões a larga escala, nomeadamente a intensificação agrícola e o aumento de fontes tópicas e difusas, que se sobrepõem no espaço e no tempo e têm levado à ruptura da estrutura e do funcionamento destes sistemas. Face a esta alteração global, o declínio da qualidade ambiental dos rios e respectivas albufeiras, tem sido alvo de uma crescente preocupação. Neste contexto, tem surgido uma crescente procura de novas tecnologias para a monitorização de albufeiras que permitam estabelecer prioridades de conservação, protecção e restauração, que possibilitem alcançar o estado ecológico requerido ou um bom potencial ecológico para estas massas de água fortemente modificadas. Assim, o objectivo desta tese foi o desenvolvimento de novas ferramentas assentes em análises estatísticas multivariadas e metodologias de modelação, que possibilitam a determinação do estado ecológico de albufeiras mediterrâneas, no âmbito da Directiva Quadro da Água DQA). Este trabalho pretende desenvolver metodologias integradas que captem a complexidade inerente aos ecossistemas aquáticos através de uma abordagem multi escala...

Chemical and biochemical tools to assess pollution exposure in aquatic ecosystems

Fernandes, Denise Robina Teixeira
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Tese de Doutorado
Publicado em //2007 ENG
Relevância na Pesquisa
46.55%
Tese dout., Ciências e Tecnologias do Ambiente, Universidade do Algarve, 2007; Aquatic environments offer and sustain important habitats for many fish species, but also attract an ever-increasing level of human activities. These environments are the ultimate sink for many of the chemical contaminants released from anthropogenic activities, which can represent a great threat to organisms living in these ecosystems, as to human health. In recent years, there has been a growing awareness of the need to detect and assess the adverse effects of contaminants in organisms exposed to different levels of pollutants. Among the available techniques, the integrated use of chemical analysis and biochemical responses to pollutants is a sound procedure for detecting impact of anthropogenic contaminants in aquatic systems. Besides wild fish consumption, the aquaculture industry is an expanding activity, due to the world population demand of fish however, the intensive production and the extensive use of chemicals in current practises, has raised concerns over the quality of cultured fish in comparison to wild fish. Although, both wild and cultured fish are important components of the Atlantic and Mediterranean diet, there is little information regarding pollutant levels in farmed fish and the risks associated to consumption. In the present thesis the impact of pollutants were investigated in both wild and cultured fish from different aquatic ecosystems...

The use of Salvinia auriculata as a bioindicator in aquatic ecosystems: biomass and structure dependent on the cadmium concentration

Wolff,G.; Pereira,GC; Castro,EM; Louzada,J; Coelho,FF
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2012 EN
Relevância na Pesquisa
56.55%
This study shows, in a multiple-level approach, the responses of Salvinia auriculata to Cd pollution in aquatic ecosystems. S. auriculata ramets were cultivated in nutrient solution and subjected to five treatments with Cd for ten days. At the end of the experiment, the number of new ramets and the dry biomass were determined. For ultrastructural observations, the leaves of S. auriculata were analyzed using a scanning electron microscope and transmission electron microscope. At the end of the experiment, the plants exposed to Cd showed damage in the leaves including necrosis and chlorosis, stomate deformations and damaged trichomes. We observed a decrease in the number of new ramets and dry biomass of S. auriculata following the increase in Cd concentration in the solution. At the ultrastructural level, leaves exposed to Cd presented chloroplast deformations and deterioration in the cell wall. All the symptoms of toxicity were directly proportionate to the concentration of Cd in the solution. The results suggests that S. auriculata shows good potential for use as a bioindicator and it can be used in the biomonitoring of aquatic ecosystems contaminated by Cd.

Diversity of phytoplankton community in different urban aquatic ecosystems in metropolitan João Pessoa, state of Paraíba, Brazil

Costa,Davi Freire da; Dantas,Ênio Wocyli
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
56.69%
AIM: The aim of the present study was to identify which environmental factors affect the seasonal phytoplankton structure in different types of tropical aquatic ecosystems. Phytoplankton sampling was performed bi-monthly from August 2009 to June 2110 at three sites in the Solon de Lucena Lake, Jaguaribe River and Águas Minerais reservoir. METHODS: The environmental variables were water temperature, transparency, depth, degree of infestation of aquatic macrophytes, air temperature, wind speed, solar radiation and precipitation. The phytoplankton community was studied in terms of richness, density, diversity and evenness. The data were treated with analysis of variance and canonical correspondence analysis. RESULTS: Spatial variations in the data only occurred between ecosystems (p < 0.05). The reservoir and river exhibited typical phytoplankton of lotic environments, with a greater richness of Bacillariophyta (52.8% and 47.8%, respectively). The lake exhibited the typical richness lentic environments, with the greatest contribution from Chlorophyta (52.8%). This ecosystem was characterized by an absence of macrophytes, a low degree of water transparency (0.3 ± 0 m) and high algal density (89,903 ± 38,542 ind. mL-1), with a dominance of Aphanocapsa nubilum. In the river environment...

Occurrence of Virulence and Antimicrobial Resistance Genes in Escherichia coli Isolates from Different Aquatic Ecosystems within the St. Clair River and Detroit River Areas▿

Hamelin, Katia; Bruant, Guillaume; El-Shaarawi, Abdel; Hill, Stephen; Edge, Thomas A.; Fairbrother, John; Harel, Josée; Maynard, Christine; Masson, Luke; Brousseau, Roland
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.61%
Although the number of Escherichia coli bacteria in surface waters can differ greatly between locations, relatively little is known about the distribution of E. coli pathotypes in surface waters used as sources for drinking or recreation. DNA microarray technology is a suitable tool for this type of study due to its ability to detect high numbers of virulence and antimicrobial resistance genes simultaneously. Pathotype, phylogenetic group, and antimicrobial resistance gene profiles were determined for 308 E. coli isolates from surface water samples collected from diverse aquatic ecosystems at six different sites in the St. Clair River and Detroit River areas. A higher frequency (48%) of E. coli isolates possessing virulence and antimicrobial resistance genes was observed in an urban site located downstream of wastewater effluent outfalls than in the other examined sites (average of 24%). Most E. coli pathotypes were extraintestinal pathogenic E. coli (ExPEC) pathotypes and belonged to phylogenetic groups B2 and D. The ExPEC pathotypes were found to occur across all aquatic ecosystems investigated, including riverine, estuarine, and offshore lake locations. The results of this environmental study using DNA microarrays highlight the widespread distribution of E. coli pathotypes in aquatic ecosystems and the potential public health threat of E. coli pathotypes originating from municipal wastewater sources.

Regionalizing Aquatic Ecosystems Based on the River Subbasin Taxonomy Concept and Spatial Clustering Techniques

Gao, Yongnian; Gao, Junfeng; Chen, Jiongfeng; Xu, Yan; Zhao, Jiahu
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.72%
Aquatic ecoregions were increasingly used as spatial units for aquatic ecosystem management at the watershed scale. In this paper, the principle of including land area, comprehensiveness and dominance, conjugation and hierarchy were selected as regionalizing principles. Elevation and drainage density were selected as the regionalizing indicators for the delineation of level I aquatic ecoregions, and percent of construction land area, percent of cultivated land area, soil type and slope for the level II. Under the support of GIS technology, the spatial distribution maps of the two indicators for level I and the four indicators for level II aquatic ecoregion delineation were generated from the raster data based on the 1,107 subwatersheds. River subbasin taxonomy concept, two-step spatial clustering analysis approach and manual-assisted method were used to regionalize aquatic ecosystems in the Taihu Lake watershed. Then the Taihu Lake watershed was divided into two level I aquatic ecoregions, including Ecoregion I1 and Ecoregion I2, and five level II aquatic subecoregions, including Subecoregion II11, Subecoregion II12, Subecoregion II21, Subecoregion II22 and Subecoregion II23. Moreover, the characteristics of the two level I aquatic ecoregions and five level II aquatic subecoregions in the Taihu Lake watershed were summarized...

A Source of Terrestrial Organic Carbon to Investigate the Browning of Aquatic Ecosystems

Lennon, Jay T.; Hamilton, Stephen K.; Muscarella, Mario E.; Grandy, A. Stuart; Wickings, Kyle; Jones, Stuart E.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/10/2013 EN
Relevância na Pesquisa
46.8%
There is growing evidence that terrestrial ecosystems are exporting more dissolved organic carbon (DOC) to aquatic ecosystems than they did just a few decades ago. This “browning” phenomenon will alter the chemistry, physics, and biology of inland water bodies in complex and difficult-to-predict ways. Experiments provide an opportunity to elucidate how browning will affect the stability and functioning of aquatic ecosystems. However, it is challenging to obtain sources of DOC that can be used for manipulations at ecologically relevant scales. In this study, we evaluated a commercially available source of humic substances (“Super Hume”) as an analog for natural sources of terrestrial DOC. Based on chemical characterizations, comparative surveys, and whole-ecosystem manipulations, we found that the physical and chemical properties of Super Hume are similar to those of natural DOC in aquatic and terrestrial ecosystems. For example, Super Hume attenuated solar radiation in ways that will not only influence the physiology of aquatic taxa but also the metabolism of entire ecosystems. Based on its chemical properties (high lignin content, high quinone content, and low C:N and C:P ratios), Super Hume is a fairly recalcitrant, low-quality resource for aquatic consumers. Nevertheless...

Heavy Metal Pollution Characteristics of Surface Sediments in Different Aquatic Ecosystems in Eastern China: A Comprehensive Understanding

Tang, Wenzhong; Shan, Baoqing; Zhang, Wenqiang; Zhang, Hong; Wang, Lishuo; Ding, Yuekui
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/09/2014 EN
Relevância na Pesquisa
46.82%
Aquatic ecosystems in eastern China are suffering threats from heavy metal pollution because of rapid economic development and urbanization. Heavy metals in surface sediments were determined in five different aquatic ecosystems (river, reservoir, estuary, lake, and wetland ecosystems). The average Cd, Cr, Cu, Ni, Pb, and Zn concentrations were 0.716, 118, 37.3, 32.7, 56.6, and 204 mg/kg, respectively, and the higher concentrations were mainly found in sediment samples from river ecosystems. Cd was the most anthropogenically enriched pollutant, followed by Zn and Pb, indicated by enrichment factors >1.5. According to consensus-based sediment quality guidelines, potential ecological risk indices, and risk assessment codes, all five types of aquatic ecosystems were found to be polluted with heavy metals, and the most polluted ecosystems were mainly rivers. Cd was the most serious pollutant in all five aquatic ecosystems, and it was mainly found in the exchangeable fraction (about 30% of the total Cd concentration, on average). The results indicate that heavy metal contamination, especially of Cd, in aquatic ecosystems in eastern China should be taken into account in the development of management strategies for protecting the aquatic environment.

The GEF-6 Biodiversity Strategy

Global Environment Facility
Fonte: World Bank Group, Washington, DC Publicador: World Bank Group, Washington, DC
EN_US
Relevância na Pesquisa
46.58%
The Convention on Biological Diversity (CBD) defines biodiversity as the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems. The Millennium Ecosystem Assessment and TEEB (The Economics of Ecosystems and Biodiversity) demonstrated that biodiversity underpins ecosystem goods and services that are required for the survival of human societies and for the future of all life on the planet. In addition, biodiversity generates considerable economic value through the provision of goods such as food, water, and materials, and services such as climate regulation, pollination, disaster protection, and nutrient cycling. Governments, civil society organizations, the private sector, indigenous people and local communities, and others have made some progress in sustainably managing biodiversity and ecosystems at local and national levels...

Environmental Dynamics of Dissolved Black Carbon in Aquatic Ecosystems

Ding, Yan
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
56.46%
Black carbon (BC), the incomplete combustion product from biomass and fossil fuel burning, is ubiquitously found in soils, sediments, ice, water and atmosphere. Because of its polyaromatic molecular characteristic, BC is believed to contribute significantly to the global carbon budget as a slow-cycling, refractory carbon pool. However, the mass balance between global BC generation and accumulation does not match, suggesting a removal mechanism of BC to the active carbon pool, most probable in a dissolved form. The presence of BC in waters as part of the dissolved organic matter (DOM) pool was recently confirmed via ultrahigh resolution mass spectrometry, and dissolved black carbon (DBC), a degradation product of charcoal, was found in marine and coastal environments. However, information on the loadings of DBC in freshwater environments and its global riverine flux from terrestrial systems to the oceans remained unclear. The main objectives of this study were to quantify DBC in diverse aquatic ecosystems and to determine its environmental dynamics. Surface water samples were collected from aquatic environments with a spatially significant global distribution, and DBC concentrations were determined by a chemical oxidation method coupled with HPLC detection. While it was clear that biomass burning was the main sources of BC...

Environmental Flows in Water Resources Policies, Plans, and Projects - Part 1: Findings and Recommendations and Part 2: Case Studies

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Brief; Publications & Research
ENGLISH
Relevância na Pesquisa
46.61%
Environmental flows are central to equitable distribution of and access to water and services provided by aquatic ecosystems. They refer to the quality, quantity, and timing of water flows required maintaining the components, functions, processes and resilience of aquatic ecosystems that provide goods and services to people. They are fundamental for sustainable water resources development, benefits sharing, and poverty alleviation. Nonetheless, water resources development planners have often overlooked environmental flows or addressed them inadequately. This two-part report, based on the Bank's economic sector analysis, shows their central importance for Integrated Water Resource Management (IWRM) and presents data, findings, and recommendations, based on in-depth case study analysis, to help make environmental water allocation an integral part of IWRM.

Occurrence, fate and effects of azoxystrobin in aquatic ecosystems: a review

Rodrigues, E. T.; Lopes, I.; Pardal, M. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.64%
The use of pesticides for crop protection may result in the presence of toxic residues in environmental matrices. In the aquatic environment, pesticides might freely dissolve in the water or bind to suspended matter and to the sediments, and might be transferred to the organisms' tissues during bioaccumulation processes, resulting in adverse consequences to non-target species. One such group of synthetic organic pesticides widely used worldwide to combat pathogenic fungi affecting plants is the strobilurin chemical group. Whereas they are designed to control fungal pathogens, their general modes of action are not specific to fungi. Consequently, they can be potentially toxic to a wide range of non-target organisms. The present work had the intent to conduct an extensive literature review to find relevant research on the occurrence, fate and effects of azoxystrobin, the first patent of the strobilurin compounds, in aquatic ecosystems in order to identify strengths and gaps in the scientific database. Analytical procedures and existing legislation and regulations were also assessed. Data gathered in the present review revealed that analytical reference standards for the most relevant environmental metabolites of azoxystrobin are needed. Validated confirmatory methods for complex matrices...

The CO2 Balance of Unproductive Aquatic Ecosystems

Duarte, Carlos M.; Agustí, Susana
Fonte: American Association for the Advancement of Science Publicador: American Association for the Advancement of Science
Tipo: Artículo Formato: 918459 bytes; application/pdf
ENG
Relevância na Pesquisa
66.78%
3 pages, 3 figures.-- PMID: 9657712 [PubMed].; Community respiration (R) rates are scaled as the two-thirds power of the gross primary production (P) rates of aquatic ecosystems, indicating that the role of aquatic biota as carbon dioxide sources or sinks depends on its productivity. Unproductive aquatic ecosystems support a disproportionately higher respiration rate than that of productive aquatic ecosystems, tend to be heterotrophic (R > P), and act as carbon dioxide sources. The average P required for aquatic ecosystems to become autotrophic (P > R) is over an order of magnitude greater for marshes than for the open sea. Although four-fifths of the upper ocean is expected to be net heterotrophic, this carbon demand can be balanced by the excess production over the remaining one-fifth of the ocean.; This research was funded by grants from the Spanish Interministerial Commission of Science and Technology (CICYT).; Peer reviewed

Sources and Biogeochemical Transformation of Mercury in Aquatic Ecosystems

Deonarine, Amrika
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
Relevância na Pesquisa
46.73%

Mercury contamination in aquatic ecosystems is a concern as anaerobic aquatic sediments are the primary regions of methylmercury production in freshwater and coastal regions. Methlymercury is a bioaccumulative neurotoxin, and human exposure to methylmercury can result in impaired functioning of the central nervous system and developmental disabilities in children. To minimize the risk of human exposure to methylmercury, it is important to be knowledgeable of the various sources which can supply mercury to aquatic ecosystems as well as have a complete understanding of the biogeochemical processes which are involved in methylmercury production in aquatic systems. In this dissertation work, both mercury biogeochemical speciation in anaerobic aquatic sediments and sources of mercury to aquatic systems were addressed.

The biogeochemical speciation of mercury is a critical factor which influences the fate and transformation of mercury in aquatic environments. In anaerobic sediments, mercury chemical speciation is controlled by reduced sulfur groups, such as inorganic sulfide and reduced sulfur moieties in dissolved organic matter (DOM). The formation of mercury sulfide nanoparticles through stabilization by dissolved organic matter (DOM) was investigated in precipitation studies using dynamic light scattering. Mercury sulfide nanoparticles (particle diameter < 100 nm) were stabilized through precipitation reactions that were kinetically hindered by DOM. To further investigate the interaction between DOM and metal sulfides...

Bioindicators of climate and trophic state in lowland and highland aquatic ecosystems of the Northern Neotropics

Pérez,Liseth; Lorenschat,Julia; Massaferro,Julieta; Pailles,Christine; Sylvestre,Florence; Hollwedel,Werner; Brandorff,Gerd-Oltmann; Brenner,Mark; Gerald,Islebe; Lozano,María del Socorro; Scharf,Burkhard; Schwalb,Antje
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
Relevância na Pesquisa
66.5%
Chironomids, diatoms and microcrustaceans that inhabit aquatic ecosystems of the Northern Neotropics are abundant and diverse. Some species are highly sensitive to changes in water chemical composition and trophic state. This study was undertaken as a first step in developing transfer functions to infer past environmental conditions in the Northern lowland Neotropics. Bioindicator species abundances were related to multiple environmental variables to exploit their use as environmental and paleoenvironmental indicators. We collected and analyzed water and surface sediment samples from 63 waterbodies located along a broad trophic state gradient and steep gradients of altitude (~0-1 560m.a.s.l.) and precipitation (~400-3 200mm/y), from NW Yucatán Peninsula (Mexico) to southern Guatemala. We related 14 limnological variables to relative abundances of 282 diatom species, 66 chironomid morphospecies, 51 species of cladocerans, 29 non-marine ostracode species and six freshwater calanoid copepods. Multivariate statistics indicated that bicarbonate is the strongest driver of chironomid and copepod distribution. Trophic state is the second most important factor that determines chironomid distribution. Conductivity, which is related to the precipitation gradient and marine influence on the Yucatán Peninsula...

Regional-scale risk assessment methodology using the Relative Risk Model (RRM) for surface freshwater aquatic ecosystems in South Africa

O'Brien,GC; Wepener,V
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
66.74%
To maximise the long-term use of limited ecosystem services in South Africa, managers continually require approaches to optimise the establishment of balances between the use and protection of ecosystems to ensure sustainability. Surface freshwater aquatic ecosystems are dynamic and difficult to manage effectively. Sound management protocols that can identify and rank threats to these ecosystems are urgently required. The Regional-Scale Risk Assessment approach is carried out on a spatial scale and allows for the consideration of multiple sources of multiple stressors affecting multiple endpoints, with the inclusion of local ecosystem dynamics and the characteristics of the landscape that may affect the risk estimate. This paper presents an integrated approach to carry out regional-scale ecological risk assessments using a Relative Risk Model (RRM) adapted for South African conditions. The RRM consists of 10 procedural steps that are relatively easily applied. The use and application of the RRM within South Africa has the potential to provide resource users, resource conservators and regulators of surface aquatic ecosystems with a range of benefits. These benefits include the establishment of a validated, structured methodology that is sensitive to the dynamics of individual case studies...

Water temperature and riverine ecosystems: An overview of knowledge and approaches for assessing biotic responses, with special reference to South Africa

Dallas,Helen
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
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46.87%
Available information pertaining to water temperature in riverine ecosystems is examined and consolidated into an overview that describes the spatial and temporal variation in water temperature, the importance of water temperature in lotic ecosystems, the measurement and modelling of water temperature, anthropogenic factors that modify water temperature, the effects of temperature changes on the physical and chemical characteristics of water; and on aquatic organisms and ecosystems. Methods for assessing the effects of temperature changes on aquatic organisms are discussed and current water temperature guidelines for the protection of aquatic ecosystems are outlined. This paper highlights the complexity of water temperature in the aquatic environment and the importance of understanding the spatio-temporal variability in water temperature and the variable responses of aquatic organisms to thermal stress. Anthropogenic modifiers of the thermal regime, which include heated discharges, flow modifications, riparian vegetation removal and global climate change; present ongoing threats to aquatic ecosystems. Whilst Northern Hemisphere information on water temperature is plentiful, this overview has identified the huge gap that exists in temperature-related data in South Africa. Without baseline data on water temperature and the thermal requirements of aquatic organisms...

The development of a classification system for inland aquatic ecosystems in South Africa

Ollis,DJ; Ewart-Smith,JL; Day,JA; Job,NM; Macfarlane,DM; Snaddon,CD; Sieben,EJJ; Dini,JA; Mbona,N
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2015 EN
Relevância na Pesquisa
56.69%
A classification system is described that was developed for inland aquatic ecosystems in South Africa, including wetlands. The six-tiered classification system is based on a top-down, hierarchical classification of aquatic ecosystems, following the functionally-oriented hydrogeomorphic (HGM) approach to classification but incorporating structural attributes at the lower levels of the hierarchy. At Level 1, a distinction is made between inland, estuarine and shallow marine systems using the degree of connectivity to the open ocean as the key discriminator. Inland systems are characterised by the complete absence of marine exchange and/or tidal influence. At Level 2, inland systems are grouped according to the most appropriate spatial framework for the particular application. At Level 3, four primary Landscape Units are distinguished (Valley floor, Slope, Plain, Bench) on the basis of the topographic position within which a particular inland aquatic ecosystem is situated, in recognition of the influence that the landscape setting has over hydrological and hydrodynamic processes acting within an aquatic ecosystem. Level 4 identifies HGM Units, defined primarily according to landform, hydrological characteristics and hydrodynamics. The following primary HGM Units (or HGM Types)...

Groundwater discharges to aquatic ecosystems associated with the Table Mountain Group (TMG) aquifer: A conceptual model

Roets,W; Xu,Y; Raitt,L; Brendonck,L
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
46.61%
This paper reports on a conceptual model that was developed to describe the different groundwater discharge 'types' from the Table Mountain Group (TMG) aquifer, that contributes to the different components of the flow regime in each of the recognised river reaches for streams and rivers associated with the TMG. This model integrates hydrogeological, ecological and geomorphological understandings into an ecohydrological perspective linking ground- and surface water systems. Through geospatial intersections of existing GIS layers a GIS model was also developed to highlight the quaternary catchments containing sensitive aquatic ecosystems that could be vulnerable to groundwater use from the TMG. The conceptual model demonstrates the intimate link between groundwater from the TMG aquifer and aquatic ecosystems in the mountain and foothill reaches of streams and rivers in the Cape Folded Mountains in particular. It also identifies two primary zones of interaction between groundwater and surface water in the TMG, namely, the 'TMG aquifer daylight-domain', located in the recharge zone, and the 'TMG aquifer surface water interface-domain', located at the discharge end of the aquifer. The conceptual model clearly indicates the difference between real groundwater...