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Registros recuperados: 21
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Cladoceran assemblage in a mesotrophic reservoir IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Cladoceran assemblage patterns were investigated in a meso-eulrophic reservoir from January 2000 till December 2002. Trends of environmental factors (water temperature, conductivity, pH, and nutrient concentrations), as well as of biotic factors (availability of potentially edible phytoplankton and densities of herbivorous and carnivorous copepods) were also assessed. Cladocera and Copepoda dominated the zooplankton community. Cluster analysis performed on the abundance data of higher abundance species (Daphnia longispina, Ceriodaphnia pulchella, Bosmina longirostris and Diaphanosoma brachyurum) helped to identify cladoceran assemblage patterns. ln winter and early spring Daphnia was dominant. ln early summer and end of autumn Ceriodaphnia and Daphnia...
Tipo: ConferenceObject
Ano: 2003 URL: http://hdl.handle.net/10198/3857
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Comunidades de macroinvertebrados a montante, no interior e a jusante de três albufeiras no NE de Portugal IPB - Escola Superior Agrária
Teixeira, Amílcar; Geraldes, Ana Maria; Boavida, Maria José.
Tipo: ConferenceObject
Ano: 2004 URL: http://hdl.handle.net/10198/3855
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Distinct age and landscape influence on two reservoirs under the same climate IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
With the purpose of finding out whether different landscape occupation could affect water quality in two reservoirs of distinct age and subjected to the same climatic influence, several factors were investigated in a study lasting from January 2000 till December 2001. Total phosphorus, orthophosphate, chlorophyll a concentrations and water colour were determined monthly in winter and biweekly in summer, in two reservoirs located in the Portuguese part of River Douro catchment. Complementarily, variables such as nitrate, ammonium ion and ammonia gas, as well as water temperature, dissolved oxygen, conductivity, and transparency were measured. Trophic state of both reservoirs was assessed by computation of Carlson’s Trophic State Index. The potential...
Tipo: Article Palavras-chave: Trophic state; Nutrient sources; Land use; Reservoir age; Water quality; Socio-economic influence.
Ano: 2003 URL: http://hdl.handle.net/10198/712
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Do distinct water chemistry, reservoir age and disturbance make any difference on phosphatase activity? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Alkaline phosphatase activity was assessed concomitantly with total phosphorus, orthophosphate and phosphomonoester concentrations in two meso-eutrophic reservoirs with distinct age and subjected to different kinds of environmental influence. Differences in conductivity, temperature and pH were found. However, during the study period alkaline phosphatase activity was similar in both reservoirs. Water colour was higher in S. Serrada Reservoir. This fact can be related to (1) reservoir age (2) high internal disturbance (3) large imputs of allochthonous detritus, resulting from the combined effect of grazing, fire and catchment slope. Despite the high water colour recorded in S. Serrada, alkaline phosphatase activity was apparently not inactivated by humic...
Tipo: Article Palavras-chave: Alkaline phosphatase; Orthophosphate regeneration; Phytoplankton; Zooplankton; Reservoirs.
Ano: 2003 URL: http://hdl.handle.net/10198/705
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Do littoral macrophytes influence crustacean zooplankton IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
In a meso-eutrophic reservoir, cladoceran and copepod assemblages were characterised in two sampling sites: One located in the pelagic zone (site 1) and the other in the shallow littoral zone (site 2), the latter colonised by emergent macrophytes. Samples were collected biweekly from June to July 2001 and from May to July 2002 at the two sites. At site 1, crustacean zooplankton samples were obtained by vertical hauls using a Wisconsin type net of 64 mm mesh size. At site 2 several random samples were obtained using a van Dorn bottle. Those samples were pooled together and the total sample was sieved through a 64 mm mesh size. Macrophyte relative abundance for each species was visually estimated. Macrophyte community was composed of Glyceria declinata,...
Tipo: Article Palavras-chave: Zooplankton; Cladocera; Copepoda; Reservoir; Macrophytes; Pelagic zone; Llittoral zone.
Ano: 2004 URL: http://hdl.handle.net/10198/708
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Efeitos da intensidade do uso da água e das práticas de gestão na limnologia de três albufeiras localizadas na bacia do Douro, NE Portugal IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: Other
Ano: 2006 URL: http://hdl.handle.net/10198/878
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Efeitos da variação da precipitação na limnologia da albufeira do Azibo (Bacia do Douro NE Portugal) IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: ConferenceObject Palavras-chave: Precipitação; Limnologia; Albufeira do Azibo.
Ano: 2006 URL: http://hdl.handle.net/10198/3971
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Efeitos das flutuações do nível da água na limnologia da Albufeira da Serra Serrada (NE Portugal) IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: ConferenceObject Palavras-chave: Limnologia; Flutuações no nível da água.
Ano: 2004 URL: http://hdl.handle.net/10198/3970
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Land use water level fluctuation and water quality in two reservoirs subjected to semi-arid climate (Trás-os-Montes, Portugal) IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Serra Serrada and Azibo reservoirs are located in River Douro watershed. The cLimate is continental, with warm, dry summers and long, cold winters. Precipitation occurs mainly in Autumn and Winter, although in a very irregular regime with wet winters to followed by drought ones.
Tipo: ConferenceObject
Ano: 2002 URL: http://hdl.handle.net/10198/3856
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Limnologia de três albufeiras da bacia do Rio Douro em Portugal IPB - Escola Superior Agrária
Geraldes, Ana Maria; Paulo, B.; Teixeira, Amílcar; Boavida, Maria José; Ribeiro, A.; Pinto, D..
Tipo: Other
Ano: 2000 URL: http://hdl.handle.net/10198/3853
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Limnological comparison of a new reservoir with one almost 40 years old which had been totally emptied and refilled IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
In the present study, several limnological characteristics of a reservoir filled for the first time are compared with those of another reservoir totally emptied after being full for almost 40 years and then refilled. Three phases were considered during the study, determined by the filling and emptying in the oldest reservoir: (i) filling phase, from August to October 1994; (ii) regular water-level phase, from December 1994 to April 1995; and (iii) emptying phase, from May to July 1995. Several forms of phosphorus, phosphatase, chlorophyll a, and phytoplankton and zooplankton composition were determined. Trophic states of the two reservoirs were compared. Major limnological differences were not found between these two artificial lakes. In fact, physical...
Tipo: Article Palavras-chave: Emptying reservoir; New reservoir; Old reservoir phosphorus.
Ano: 1999 URL: http://hdl.handle.net/10198/2933
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Limnological variations of a reservoir during two successive years: one wet, another dry IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Changes in environmental variables, as well as in planktonic algae and in crustacean zooplankton abundance, were investigated in a meso-eutrophic reservoir during two successive years: one wet, another dry. In the wet winter, both total phosphorus and soluble reactive phosphorus reached their maxima, whereas water transparency achieved the minimum during the same period. The obtained data suggest that total phosphorus and soluble reactive phosphorus peaks were related to the increase in nutrient loading as a consequence of the intense rainfall which occurred during this period. Phytoplankton composition was dominated by Cyclotella spp., except during the dry winter when Anabaena became dominant. The dominance of this alga seemed to be related to nitrate...
Tipo: Article Palavras-chave: Crustacean zooplankton; Dry years; Nutrients; Phytoplankton; Reservoir; Wet years.
Ano: 2004 URL: http://hdl.handle.net/10198/710
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Modificação dos picos de abundância das populações de Cladocera e de Copepoda: resposta às variações inter-anuais da precipitação e da temperatura? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: ConferenceObject
Ano: 2008 URL: http://hdl.handle.net/10198/3845
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Modificação dos picos de abundância das populações de Cladocera e de Copepoda: resposta às variações inter-anuais da precipitação e da temperatura? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: Other
Ano: 2008 URL: http://hdl.handle.net/10198/881
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Reservoirs: mirrors of the surrounding landscape? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
To assess in what extent the environmental quality of aquatic systems reflect landscape features several water quality parameters were determined in two reservoirs. Concomitantly, the surrounding landscape was characterized and the existing potential sources of phosphorous and nitrogen runoff were identified and when possible estimated.
Tipo: Other
Ano: 2010 URL: http://hdl.handle.net/10198/2959
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Reservoirs: mirrors of the surrounding landscape? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
To assess in what extent the environmental quality of aquatic systems reflect landscape features several water quality parameters were determined in two reservoirs. Concomitantly, the surrounding landscape was characterized and the existing potential sources of phosphorous and nitrogen runoff were identified and when possible estimated. Located in a mountainous area with negligible direct human influence, it was expected to find lower amounts of suspended organic matter and nutrients in Serra Serrada Reservoir. Water level fluctuations caused by intensive human water use, grazing and frequent land fires in the surrounding landscape can explain the unexpected high values of the mentioned parameters. In Azibo Reservoir the factors with greatest influence on...
Tipo: ConferenceObject Palavras-chave: Landscape; Water quality land use; Phosphorous and Nitrogen sources.
Ano: 2010 URL: http://hdl.handle.net/10198/2922
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Seasonal water level fluctuations: Implications for reservoir limnology and management IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
With the purpose of finding out whether seasonal water level fluctuations could affect water quality in a reservoir subjected to those changes, trends in environmental variables and in phytoplankton and zooplankton assemblages were analysed. The reservoir’s hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid-June to the beginning of September and the minimum level phase lasted from mid-September to the beginning of the first autumn/winter rain events. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, water colour and chlorophyll a were found during the minimum level phase. The phytoplankton assemblage was dominated by...
Tipo: Article Palavras-chave: Nutrients; Phytoplankton and zooplankton assemblages; Reservoir management; Reservoirs; Water level fluctuation.
Ano: 2005 URL: http://hdl.handle.net/10198/711
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Variação de alguns parâmetros indicadores da qualidade da água em duas albufeiras da Serra da Estrela IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
Tipo: Article
Ano: 1998 URL: http://hdl.handle.net/10198/899
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What factors affect the pelagic cladocerans of the meso-eutrophic Azibo Reservoir? IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
The assemblage patterns of pelagic Cladocera species were investigated in a meso-eutrophic reservoir from January 2000 to December 2002. Trends of environmental factors (water temperature, conductivity, pH, and nutrient concentrations), as well as of biotic factors (availability of potentially edible phytoplankton and densities of herbivorous and carnivorous copepods) were assessed. Zooplankton community was dominated by Cladocera and Copepoda. Assemblage patterns for Cladocera were identified by performing a cluster analysis on abundance data of the dominant species: Daphnia longispina, Ceriodaphnia pulchella, Bosmina longirostris and Diaphanosoma brachyurum. In winter and spring, Daphnia was dominant. In early summer and end of autumn, Ceriodaphnia and...
Tipo: Article Palavras-chave: Zooplankton; Cladocera; Copepoda; Environmental factors; Phytoplankton availability.
Ano: 2004 URL: http://hdl.handle.net/10198/707
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Zooplankton assemblages in two reservoirs: one subjected to accentuated water level fluctuations, the other with more stable water levels IPB - Escola Superior Agrária
Geraldes, Ana Maria; Boavida, Maria José.
The abundance, composition and dynamics of zooplankton were followed in two reservoirs of the River Douro catchment. The Serra Serrada Reservoir is subject to marked fluctuations in water levels. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, water colour and chlorophyll a were found during the minimum level phase. Rotifera was dominant except in late summer and autumn when the cladoceran Ceriodaphnia quadrangula or the copepod Tropocyclops prasinus replaced them as the dominant zooplankton. Among the rotifers the most common taxa were Keratella cochlearis, Conochilus sp. and Asplanchna priodonta. Maximum rotifer density was about 80,000 ind m–3 in 2000, 200,000 ind m–3 in 2001 and 100,000 ind m–3 in 2002. Among the...
Tipo: Article Palavras-chave: Reservoirs; Water level fluctuations; Zooplankton assemblage structure; Water stored volume.
Ano: 2007 URL: http://hdl.handle.net/10198/715
Registros recuperados: 21
Primeira ... 12 ... Última
 

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