Browsing by Author "Domingues, Rita"
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- Como é que os habitantes da Praia de Faro olham para os riscos costeiros?Publication . Domingues, Rita; Santos, Márcio C.; Jesus, Saúl; Ferreira, OscarFaro Beach is a vulnerable and heavily urbanized settlement, exposed to beach erosion, overwash and other hazards. However, residents seem to feel safe living there and have no intentions of ever leaving the beach. We developed questionnaires and went knocking on doors, asking how residents feel about their safety at the beach. We realised that fishermen and their families possess significant knowledge on coastal hazards that derive mainly from life experience. Their risk perception is not as low as we thought; however, residents believe hazards are not that dangerous and they will probably happen in the future, but not now. This optimism bias and psychological distance hinders their preparedness efforts towards hazards.
- Cyanobacteria blooms in natural waters in Southern Portugal: a water management perspectivePublication . Galvão, Helena M.; Reis, Margarida P.; Valério, Elisabete; Domingues, Rita; Costa, Cristina; Lourenço, Dulce; Condinho, S.; Miguel, Rute; Barbosa, Ana B.; Gago, Conceição; Faria, Natália; Paulino, Sérgio; Pereira, PauloThis synthesis of 3 studies from 2 regions of southern Portugal (Alentejo and Algarve) was part of a workshop focusing on cyanobacteria held at the SAME 10. The first study monitored impacts of the large Alqueva dam on the Guadiana estuary since 1996, revealing changes in sediment load, nutrient regime and phytoplankton succession. Prior to dam construction, dense cyanobacterial blooms occurred in the upper estuary during summer and fall. After dam construction, chlorophyll concentration, phytoplankton diversity and abundances of cyanobacteria decreased, contrary to predictions. Mycrocystins remained at low levels in the seston and undetectable in water samples, except during summer 2003 when the particulate fraction contained 1 μg l–1, while chlorophyll concentrations and abundances of potentially toxic cyanobacteria remained low. Algarve reservoirs studied since 2001 revealed differences in phytoplankton dynamics. In the western mesotrophic reservoirs (Bravura and Funcho), 40 to 50% of surface samples contained cyanobacterial concentrations of ≥2000 cells ml–1, while over 80% of samples from the eastern oligotrophic reservoirs (Odeleite and Beliche) exceeded this value. Spring blooms were dominated by Oscillatoriales in Odeleite and Beliche and by Chroococcales in Bravura and Funcho. Bloom composition seemed to depend on water temperature and management strategies, while toxin concentrations reflected the increased biomass of toxic species. Finally, phytoplankton communities and microcystin production in 5 Alentejo freshwater reservoirs were studied from May to December 2005 and April to July 2006. Cyanobacterial blooms occurred, with varying intensities, not only during summer but also occasionally in winter. Microcystins were detected in 23% of the samples (n = 51), but without correlation with cyanobacterial biomass. Although Microcystis aeruginosa seemed to be the major producer of microcystins, other potentially toxic species were found. In summary, the varying pattern of cyanobacterial bloom occurrence and toxicity requires a systematic approach to monitoring programs for adequate risk assessment.
- Growth and grazing mortality of microbial plankton in a shallow temperate Coastal Lagoon (Ria Formosa, SW Iberia)Publication . Santos, Yohann; Mosley, Benjamin A.; Nogueira, Patricia; Galvão, Helena; Domingues, RitaMicrozooplankton grazing is widely recognized as an important process of heterotrophic prokaryote and phytoplankton biomass removal. However, few studies have specifically addressed microbial mortality in the Ria Formosa coastal lagoon. This study aimed to assess the growth and mortality of heterotrophic prokaryotes and phytoplankton in this ecosystem using the dilution technique. The results revealed significant seasonal variations in the growth and grazing rates of both heterotrophic prokaryotes and phytoplankton, with mean grazing rates slightly exceeding the mean potential instantaneous growth rates. This indicates that microzooplankton consume a substantial proportion of both microbial groups in the lagoon. For specific phytoplankton taxa, the wide range of observed grazing rates suggests grazer selectivity, highlighting the need for future research to examine the dynamics of each phytoplankton group more closely.
- Impacts of sample storage time on estimates of phytoplankton abundance: how long is too long?Publication . Nogueira, Patricia; Barbosa, Ana; Domingues, RitaPhytoplankton play a key role in marine ecosystems, making the accurate quantification of functional groups/species, using standardized microscopy techniques, essential in many research efforts. In this study we aimed to evaluate the effects of (a) storage time on the abundance of microphytoplankton in samples fixed with acid Lugol’s solution; (b) storage time on the abundance of pico- and nanophytoplankton in frozen microscopy slides; (c) storage time on the abundance of pico- and nanophytoplankton in fixed refrigerated samples and (d) storage protocol (refrigerated versus frozen) on the abundance of pico- and nanophytoplankton. Microphytoplankton were analyzed using inverted microscopy, and pico- and nanophytoplankton using epifluorescence microscopy. Results indicate storage time negatively impacted the abundances of all phytoplankton size classes; however, effects were group-specific. For accurate abundance estimates, we suggest that samples fixed with acid Lugol’s should be analyzed within 30 and 180 days, for dinoflagellates/total microphytoplankton and diatoms, respectively. For picoeukaryotes, glutaraldehyde fixed samples should be kept refrigerated for up to 4 days, and slides should be prepared immediately before observation. It is recommended that authors specify the exact lag times between sample collection, fixation and analysis, to allow the comparability of phytoplankton datasets across different studies and/or monitoring programs.
- Place attachment, risk perception, and preparedness in a population exposed to coastal hazards: a case study in Faro Beach, southern PortugalPublication . Domingues, Rita; Jesus, Saúl; Ferreira, OscarLiving by the coast is a high-risk choice, but most people do it voluntarily. At Faro Beach, a heavily urbanized settlement located on a sandy barrier peninsula exposed to coastal hazards, houses and roads were destroyed due to storm action. However, residents feel safe living there and have no intentions of relocating. The development and implementation of coastal management plans and disaster risk reduction measures require the understanding of psychological drivers of residents’ risk perception and behaviours. Thus, the main goal of this study is to evaluate the relationships between place attachment, risk perception, and preparedness in Faro Beach. We hypothesized that place attachment and past experience with hazards would have a negative effect on risk perception, while risk perception would positively influence preparedness. We administered a self-report questionnaire to 131 residents, and analysed the data using partial least squares modelling. Results show that stronger place attachment is associated with lower risk perception, as residents tend to accept the risk as part of their environment. Experience contributed to higher risk perception in Faro Beach residents, most likely because residents have had direct and personal experience with hazards and are fully aware of the consequences. In addition, risk perception was negatively associated with preparedness; although residents’ risk perception is moderate, probably due to risk normalisation, they still make some preparations to deal with a potential disaster. This study is useful for the design and implementation of more sustainable coastal management plans, as it validates the relevance of affective variables in risk perception and preparedness.
- Short-term effects of climate change on Planktonic Heterotrophic Prokaryotes in a temperate coastal lagoon: temperature is good, ultraviolet radiation is bad, and CO2 is neutralPublication . Barbosa, Ana; Mosley, Benjamin A.; Galvão, Helena; Domingues, RitaPlanktonic heterotrophic prokaryotes (HProks) are a pivotal functional group in marine ecosystems and are highly sensitive to environmental variability and climate change. This study aimed to investigate the short-term effects of increasing carbon dioxide (CO2 ), ultraviolet radiation (UVR), and temperature on natural assemblages of HProks in the Ria Formosa coastal lagoon during winter. Two multi-stressor microcosm experiments were used to evaluate the isolated and combined effects of these environmental changes on HProk abundance, production, growth, and mortality rates. The isolated and combined effects of increased CO2 on HProks were not significant. However, HProk production, cellular activity, instantaneous growth rate, and mortality rate were negatively influenced by elevated UVR and positively influenced by warming. Stronger effects were detected on HProk mortality in relation to specific growth rate, leading to higher HProk net growth rates and abundance under elevated UVR and lower values under warming conditions.