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- Role of microbes in the Ria Formosa lagoonPublication . Galvão, Helena M.; Mendes, Pedro; Caetano, Sandra; Icely, John; Newton, AliceWith the development of epifluorescence microscopy and sensitive radioisotope techniques, high abundance and activity of microorganisms was observed in marine waters since 1970s and 1980s. These observations resulted in a new concept of rapid turn-over and recycling of organic matter through a ‘microbial loop’ (Azam et al., 1983; Azam, 1998). Figure 5.1 illustrates fluxes of material through the marine microbial loop. Main processes are C fixation by photosynthetic microorganisms (prokaryotic and eukaryotic) with exudation losses of Dissolved Organic Matter (DOM), which is incorporated by heterotrophic bacteria. Phagotrophic protists in turn graze both autotrophs and bacteria producing ‘sloppy feeding’ loss of DOM, which returns to the loop. DOM is remineralized by all microorganisms into Dissolved Inorganic Nutrients (DIN), which are taken up by autotrophic and heterotrophic microorganisms.
- Cyanobacteria blooms and cyanotoxin occurrence in the Guadiana (SE - Portugal): preliminary resultsPublication . Caetano, Sandra; Miguel, Rute; Mendes, Pedro; Galvão, Helena M.; Barbosa, Ana B.Cyanobacteria are a recognised public health hazard, because the majority of species is able to produce toxins. The monitoring is usually restricted to freshwater environments, like lakes or dams used for water supply. Cyanobacteria blooms have been regularly reported in the Guadiana River and high estuary and most of the observed cyanobacteria were toxin producers.
- Ecological tools for the management of cyanobacteria blooms in the Guadiana River watershed, Southwest IberiaPublication . Galvão, Helena M.; Reis, Margarida P.; Domingues, Rita B.; Caetano, Sandra; Mesquita, Sandra; Barbosa, Ana B.; Costa, Cristina; Vilchez, Carlos; Ribau Teixeira, MargaridaStrong water demand for irrigation, energy and drinking water production is responsible for an increasingly regulation of freshwater flow patterns and watersheds. In this context, the construction of dams allows water storage but seriously restricts freshwater flow downstream. Due to scarcity of freshwater resources, reservoir water management often promotes high hydraulic residence. This may cause strong impacts on biological components of aquatic ecosystems, influencing the development of cyanobacteria blooms and aggravating their harmful impacts.