Effects of phytoplankton community and interaction between environmental variables on nitrogen uptake and transformations in an urban river

Author(s):  
Jing Yang ◽  
Haiguang Pei ◽  
Junping Lü ◽  
Qi Liu ◽  
Fangru Nan ◽  
...  
2013 ◽  
Vol 5 (6) ◽  
pp. 1300
Author(s):  
Gustavo Melo ◽  
Manuela Morais ◽  
Maria Do Carmo Sobral ◽  
Günter Gunkel ◽  
Renata Carvalho

O objetivo do presente trabalho é avaliar as características físico-químicas e microbiológicas dos reservatórios da região do semiárido brasileiro, receptores de água do Projeto de Integração do rio São Francisco, identificando a influência de variáveis ambientais na comunidade fitoplanctônica. Foram estudados os reservatórios de Itaparica, Poço da Cruz, Boqueirão, Armando Ribeiro Gonçalves e Castanhão. Para alcançar o objetivo proposto, foram feitas análises estatísticas multivariadas com auxílio dos programas Primer e SPSS. Verificou-se que os reservatórios se diferenciam em dois grupos (Eixo Leste e Eixo Norte), observando-se a existência de uma variação temporal. As variáveis ambientais explicaram 78% da variação do fitoplâncton. Destes 22% são explicados por variáveis tipológicas (naturais) e 56% são explicados por variáveis de pressão (efeito antropogênico). Espera-se que a transferência de água possa contribuir para melhoria da qualidade da água, sendo fundamental a implementação de medidas que promovam uma gestão integrada e sustentável das respectivas bacias hidrográficas. Palavras-chave: variáveis ambientais, fitoplâncton, reservatórios, semiárido The Influence of Environmental Variables on Phytoplankton Community of the Receptors Reservoirs by the São Francisco River Integration Project ABSTRACT This study aims to evaluate the physico-chemical and microbiological characteristics of brazilian northeast reservoirs, from the São Francisco river Integration Project, to identify the influence of environmental variables on the phytoplankton community. There were studied the reservoirs of Itaparica, Poço da Cruz, Boqueirão, Armando Ribeiro Gonçalves and Castanhão. To achieve the proposed aim, multivariate statistical analyses were performed with the Primer and SPSS programs. It was observed that the reservoirs are distinguish in two groups (East and North Axis), observing the existence of a temporal variation. It was verified that the environmental variables explained 78% of the phytoplankton variation. Of these, 22% are explained by typological variables and 56% are explained by pressure variable. It is expected that the transfer of water may improve water quality (especially in reservoirs of the East Axis). It is essential to implement actions to promote an integrated and sustainable management of their watersheds. Keywords: environmental variables, phytoplankton, reservoirs, semiarid


1998 ◽  
Vol 17 (1-4) ◽  
pp. 159-177 ◽  
Author(s):  
M. Semeneh ◽  
F. Dehairs ◽  
M. Elskens ◽  
M.E.M. Baumann ◽  
E.E. Kopczynska ◽  
...  

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1057 ◽  
Author(s):  
Chen Yu ◽  
Chao Li ◽  
Tao Wang ◽  
Min Zhang ◽  
Jun Xu

Shallow lakes are highly vulnerable to damages caused by human activities and warming trends. To assess whether and how community structures of phytoplankton and nitrogen uptake respond to the combined effects of elevated temperature and eutrophication, we performed a mesocosm experiment in field by combining a 4.5 °C increase in temperature and the addition of phosphorus. Our results demonstrated that the combination of rising temperatures and phosphorus loading stimulated the maximum biomass built up by the phytoplankton community, and changed the phytoplankton community by significantly increasing the number of Chlorophyta and Cyanophyta, and decreasing that of Cryptophyta. We also examined the effects of climate warming and eutrophication on phytoplankton nitrogen uptake and dynamics using 15N tracer techniques. The addition of phosphorus slightly increased the phytoplankton nitrate uptake velocity and relative preference index, but decreased the nitrate uptake turnover time. Warming relatively increased the ammonium uptake velocity and the relative preference index, but decreased the ammonium turnover time. In kinetic studies, NH4+ exhibited a higher maximum uptake rate (Vmax) and a lower half-saturation constant (Ks) than NO3− substrates due to temperature elevation and the addition of phosphorus. Hence, warming and eutrophication increased the capacity of phytoplankton for NH4+ uptake and their affinity at low substrate concentrations. Thus, the combined effects of climate warming and phosphorus nutrient availability may increase the prevalence of Chlorophyta and Cyanophyta, and change the nitrogen cycling of aquatic ecosystems.


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