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- Estudo da dinâmica microbiana do rio Guadiana : impacte da construção da barragem do AlquevaPublication . Caetano, Sandra; Galvão, HelenaFoi levada a cabo urna campanha de amostragem que decorreu entre Abril e Outubro, cobrindo o período de Primavera-Verão de 1999; com uma frequência de amostragem de 2 colheitas por mês em 3 estações situadas na zona de alto estuário de rio; com o objectivo de responder as seguintes questões: De que forma a produção primária afecta e bacterioplâncton? Qual a relação entre a produção primaria e a produção bacteriana? Como se reflecte na densidade e biomassa bacterianas do rio Guadiana? E ainda de que forma é controlada a comunidade bacteriana do rio? Ao longo de toda a campanha de amostragem o rio manteve-se sempre muito turvo, dificultando as recolhas e inutilizando algumas amostragens. Esta condição anormal das aguas do rio deve-se ã construção da barragem do Alqueva. 0 que nos permitiu estudar o impacte que a construção de barragens pode ter a nível da dinâmica das comunidades microbianas, as quais representam a base da cadeia alimentar em qualquer sistema. Ao longo de todo o período de amostragem a abundância bacteriana (AB) registou uma média de 3.6xl06 BT.ml`1 i0.84, a abundância de nanoflagelados heterotróficos (I-INF) uma média de Léxlüs HNF.ml" iU.?l e a abundância de nanoflagelados autotroficos (ANF) uma média de 5.9xl03 ANF.nrI" i2.48. Os valores de HNF situam-se dentro do intervalo de valores observados em sistemas semelhantes, mas a abundância bacteriana e de ANF situaram-se abaixo do registado em anos anteriores para a mesma zona. Por outro lado a produção bacteriana (PB) foi superior ao “normal” atingindo uma média de 23.96 ugC.l".h`1 ¬_'-36.91 e a biomassa bacteriana OSB) registou uma média de 50.5? pgC.l`1 il 1.37 ao longo de todo o período de amostragem. Nem a BB nem a AB parecem explicar verdadeiramente a PB observada. A produção primaria (PP), embora baixa encontra-se dentro dos valores registados em anos anteriores para a mesma zona do rio.
- Mitochondrial DNA reveals a mosaic pattern of phylogeographical structure in Atlantic and Mediterranean populations of anchovy (Engraulis encrasicolus)Publication . Magoulas, A.; Castilho, Rita; Caetano, Sandra; Marcato, S.; Patarnello, T.This study extends the geographic coverage of a previous study of mitochondrial DNA restriction fragment length polymorphism in European anchovy. Both studies together include 24 samples representing 17 localities extending from the Black Sea, through the Mediterranean Sea to the eastern Atlantic as far south as Dakar, Senegal. Eighty-eight haplotypes deWne two clades (A and B) separated by 3.2% sequence divergence. Clade A has a star-like genealogy indicative of a recent population expansion. Clade B has a more complex genealogy, consisting of several haplotypes at intermediate frequencies. The distributions of these clades consist of a mosaic with abrupt changes between some areas and gradients between other areas. Clade A predominates the Black and Aegean seas, but is present throughout the Mediterranean. Unexpectedly, new data show that clade A is also at a high frequency in the Atlantic, from Portugal to at least Senegal. Overall, the level of genetic diVerentiation among populations is high (FSTD0.148, p<0.0001), with the greatest diVerences between basins. AMOVA reveals four main geographical groups: Atlantic, central Mediterranean, Aegean Sea, and Black Sea. Mismatch distribution clearly indicates historical bottleneck and population expansion for clade A, while for clade B such evidence is equivocal. This diVerence may reXect a range expansion for both clades, but with higher gene Xow (Nm values) between demes for clade A. Both contemporary and historical processes are important in shaping the complex genetic population structure of European anchovy.
- Impacts of decommissioning and upgrading urban wastewater treatment plants on the water quality in a shellfish farming coastal lagoon (Ria Formosa, South Portugal)Publication . Jacob, J.; Correia, Cátia; Torres, Ana Flor; Xufre, Gustavo; Matos, André Filipe; Ferreira, Cristina; Reis, Margarida; Caetano, Sandra; Freitas, Carla; Barbosa, Ana B.; Cravo, AlexandraRia Formosa is a productive coastal lagoon, located on the south coast of Portugal, and represents the largest national producer of shellfish bivalves (ca. 90% production). This ecosystem is subjected to various anthropogenic pressures, including the discharge of urban wastewater treatment plants (UWWTP), which impacts the lagoon water quality. This study aimed to assess the impact of alterations in the functioning of two UWWTP on the water quality of Ria Formosa, based on chemical variables, phytoplankton composition ( including potential harmful species) and faecal contamination. During the period September 2018 - October 2019, water sampling was conducted along dominant longitudinal gradients of the effluent dispersion from the discharge point (1-2 km), for two sites: a decommissioned (OP) and a modified (FO) UWWTP. After modification, the later started receiving a higher influent volume (ca. 40%), under an innovative technology system (biological treatment in aerobic granular sludge). Based on chemical water quality variables, phytoplankton and indicators of faecal contamination, a significant improvement along the longitudinal gradient from the discharge point was observed after OP decommissioning. This improvement was fast, being detected two months after decommissioning, positively affecting areas used as shellfish farming grounds. However, distribution patterns of bacteriological indicators and regular shellfish harvesting interdictions suggested an alternative source of faecal contamination after OP decommissioning. At FO, both chemical variables and bacteriological indicators of faecal contamination revealed a slower improvement, only six-months after the UWWTP alteration. Before that, increased and highly variable ammonium, chlorophyll a concentration, phytoplankton abundances and Escherichia coli densities, revealed an unstable phase. Overall, a lower water quality at FO in respect to OP reflected not only a higher effluent volume but also more restricted water circulation for the former.
- Toxicity risks linked to cyanobacteria blooms in southern Portugal reservoirsPublication . Caetano, Sandra; Reis, Margarida P.Cyanobacteria massive proliferation in freshwater ecosystems has become a relevant public health concern. The main objective of this study was to assess the toxicity risks linked to the proliferation of cyanobacteria in southern Portugal reservoirs, while alerting to the need to widen and strengthen the connection between environment and human health. This work also contributes to highlight the role of phytoplankton dynamics in the development of Cyanobacteria Hazard Algal Blooms (CyanoHABs). All addressed reservoirs revealed dominance of cyanobacteria in terms of abundance, exhibiting blooms, especially during the dry season. Following a global trend, these reservoirs exhibited CyanoHABs increase, with constant presence of toxigenic species which constitutes a threat to public health and often limits water use. From the perspective of future climate change, with expected worsening of the torrential hydrologic regime, increase in CyanoHABs occurrence is expected. Biogeographical expansion of exotic toxigenic cyanobacteria has begun in these reservoirs, also presenting public health risks, since their toxins are not regularly screened. This study includes the first notification of Cylindrospermopsis raciborskii in Alqueva reservoir, in similar abundances to those already detected by other authors in Southern Portugal reservoirs. Confirming invasive toxigenic species success in these waters. Even in oligotrophic reservoirs (Beliche), cyanobacteria prevail, indicating bottom-up factors are not always as important as assumed, whereby top-down factors must be further investigated. The development of ecological indices based on phytoplankton data should allow inderect inference about potential public health risks. Given its simplicity, the dominance index of potentially toxic cyanobacteria (PTCD) may constitute an option, when calibrated through its application to more systems. This work contributes to: (i) the understanding of cyanobacteria dynamics within phytoplankton, (ii) the acknowledgement of the hazards linked to their presence and (iii) constitutes a b
- A importância do mundo invisível dos micróbios na Ria FormosaPublication . Mendes, Pedro; Galvão, Helena; Caetano, Sandra; Icely, John; Newton, AliceCom o desenvolvimento da microscopia de epifluorescência e técnicas sensíveis de radioisótopos na década de 1970, a abundância e atividade de microrganismos pôde ser observada e estudada em águas marinhas. Estas observações resultaram num novo conceito de rápida transferência e reciclagem de matéria orgânica através de um ciclo microbiano, o “microbial loop”.
- 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.
- Unravelling the effects of treated wastewater discharges on the water quality in a coastal lagoon system (Ria Formosa, South Portugal): Relevance of hydrodynamic conditionsPublication . Cravo, Alexandra; Barbosa, A.B.; Correia, C.; Matos, A.; Caetano, S.; Lima, M.J.; Jacob, J.This study aimed to assess the influence of treated wastewater disposal on Ria Formosa coastal lagoon (South Portugal), the largest national producer of bivalve mollusks. Water quality was evaluated at two areas under different wastewater loads and hydrodynamic conditions, using physico-chemical variables, bacterial indicators of contamination, chlorophyll-a concentration, phytoplankton abundance and composition. Samples were collected monthly, between October 2018 and September 2019. Minor influence of effluent discharge was detected at the eastern Olhao ˜ area, exposed to stronger hydrodynamics and higher wastewater load than the northwestern Faro area (ca. 2–4-fold total nitrogen and phosphorus). The lower load weakly flushed area showed a poorer water quality, up to 500 m from the discharge point, more marked during the spring-summer period. The intensity, persistence, and spatial extent of the wastewater footprint, lower for the highest-loading area, reflected the role of local hydrodynamic conditions, modulating the influence of wastewater discharge on lagoonal water quality.
- Differential population structuring of two closely related fish species, the mackerel (Scomber scombrus) and the chub mackerel (Scomber japonicus), in the Mediterranean SeaPublication . Zardoya, R.; Castilho, Rita; Grande, Cristina; Favre-Krey, L.; Caetano, Sandra; Marcato, S.; Krey, G.; Patarnello, T.Population genetic structures of the mackerel (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied in the Mediterranean Sea. Fragments of 272 bp (S. scomber) and 387 bp (S. japonicus) of the 5′ -end of the mitochondrial control region were sequenced from spawning individuals collected off the coasts of Greece, Italy, Spain, and Portugal. High levels of mitochondrial control region haplotypic diversity (> 0.98) were found for both Scomber species. Nucleotide diversity was higher in the mackerel (0.022) than in the chub mackerel (0.017). Global F ST values were also higher and significant in the mackerel (0.024, P < 0.0001) as opposed to the chub mackerel (0.003, P > 0.05). Molecular variance analyses showed differential genetic structuring for these two closely related species. There is extensive gene flow between Mediterranean Sea and Atlantic Ocean populations of chub mackerel, which are organized into a larger panmictic unit. In contrast, Mediterranean Sea populations of mackerel show some degree of genetic differentiation and are structured along an east–west axis. The analysed eastern Mediterranean Sea mackerel populations (Greece, Italy) are clearly separated from that of the western Mediterranean Sea (Barcelona), which forms a panmictic unit with eastern Atlantic Ocean populations. The genetic structures of both species showed asymmetric migration patterns and indicated population expansion.
- 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.