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- Variability patterns and phenology of harmful phytoplankton blooms off southern Portugal: looking for region-specific environmental drivers and predictorsPublication . Lima, M.J.; Relvas, Paulo; Barbosa, AnaHarmful algal blooms (HABs) negatively impact coastal ecosystems, fisheries, and human health, and their prediction has become imperative for effective coastal management. This study aimed to evaluate spatialtemporal variability patterns and phenology for key toxigenic phytoplankton species off southern Portugal, during a 6-year period, and identify region-specific environmental drivers and predictors. Total abundance of species responsible for amnesic shellfish poisoning (Pseudo-nitzschia spp.), diarrhetic shellfish poisoning (Dinophysis spp.), and paralytic shellfish poisoning (G. catenatum) were retrieved, from the National Bivalve Mollusk Monitoring System public database. Contemporaneous environmental variables were acquired from satellite remote sensing, model-derived data, and in situ observations, and generalized additive models (GAMs) were used to explore the functional relationships between HABs and environmental variables and identify regionspecific predictors. Pseudo-nitzschia spp. showed a bimodal annual cycle for most coastal production areas, with spring and summer maxima, reflecting the increase in light intensity during the mixed layer shoaling stage, and the later stimulatory effects of upwelling events, with a higher bloom frequency over coastal areas subjected to stronger upwelling intensity. Dinophysis spp. exhibited a unimodal annual cycle, with spring/summer maxima associated with stratified conditions, that typically promote dinoflagellates. Dinophysis spp. blooms were delayed with respect to Pseudo-nitzschia spp. spring blooms, and followed by Pseudo-nitzschia spp. summer blooms, probably reflecting upwelling-relaxation cycles. G. catenatum occurred occasionally, namely in areas more influenced by river discharges, under weaker upwelling. Statistical-empirical models (GAMs) explained 7-8%, and 21− 54% of the variability in Pseudo-nitzschia spp. and Dinophysis spp., respectively. Overall, a set of four easily accessible environmental variables, surface photosynthetically available radiation, mixed layer depth, sea surface temperature, and chlorophyll-a concentration, emerged as the most influential predictors. Additionally, over the coastal production areas along the south coast, river discharges exerted minor negative effects on both HAB groups. Despite evidence supporting the role of upwelling intensity as an environmental driver of Pseudonitzschia spp., it was not identified as a relevant model predictor. Future model developments, such as the inclusion of additional environmental variables, and the implementation of species- and period-specific, and hybrid modelling approaches, may further support HAB operational forecasting and managing over complex coastal domains.
- Water quality for bivalve molluscs and consumer safety: application of novel and adapted multimetric indices in a coastal lagoon system exposed to wastewater dischargesPublication . Cravo, Alexandra; Barbosa, Ana; Borlido Oliveira Lima, Maria João; Ferreira, Cristina; Correia, Cátia; Matos, André Filipe; Jacob, José; Caetano, SandraWater quality degradation associated with wastewater discharges compromises the production of marine living resources. Water quality indices (WQIs) are relevant tools for water quality management, but most applications are limited to the suitability of freshwater for drinking. In this study, a novel WQI was developed to assess the effects of urban wastewater treatment plant (WWTP) discharges on the water quality in Ria Formosa coastal lagoon, targeting the condition of bivalve molluscs and consumer food safety (WQIB). The application of WQIB was compared with an adapted version of the Canadian Council of Ministers of the Environment Water Quality Index, using similar parameters (CCME-WQIB). WQIB and CCME-WQIB were applied to four areas next to WWTPs, over a 2-year period. WQIB integrated seven sub-indices (salinity, unionized ammonia, dissolved oxygen, suspended solids, chlorophyll-a, Escherichia coli and toxigenic phytoplankton), using a weighted additive aggregation function. Water quality ranged from very poor to very good and generally improved with distance from the effluent discharge points, and during the cold period. Highest influence of WWTP discharges was detected in areas under weak hydrodynamics. In areas under strong hydrodynamics, poor water quality was caused by the advection of toxigenic phytoplankton from adjacent coastal waters during the warm period. Although correlated, the use of WQIB should be preferred over CCME-WQIB due its greater sensitivity, use of weighted parameters and application at the sampling event scale. Our novel index extends the limited number of WQIs applied to marine systems and can be adapted to other systems and water use purposes.
- A walk in wetlands morphology and inundation patternsPublication . Borlido Oliveira Lima, Maria João; Carrasco, Rita; Ferreira, ÓscarBalanced conservation strategies are needed to ensure the protection of wetlands in the twenty-first century. To guarantee the success of wetland restoration projects, it is essential to better understand the characteristics of these fragile sites and the driving mechanisms of change. This study characterised the morphology of wetland platforms at five backbarrier sites distributed around the world and subject to various tidal regimes (micro- to macrotidal). Wetland ecogeomorphologic units were manually mapped and classified into upper-, mid-low marsh, tidal flat and channel, using high-resolution Digital Elevation Models (DEMs). Differences in elevation, slope and hydroperiod metrics between morphological units and study sites were assessed, as well as the influence of tidal range and associated inundation patterns on wetland zonation. Upper and mid-low marshes showed steeper intra-slopes compared to channels and tidal flats, with the latter exhibiting longer hydroperiods. No significant differences in normalised elevation and hydroperiod were detected between study sites. Steeper slopes were observed in microtidal systems compared to meso- and macrotidal systems, likely due to constrained horizontal migration. These findings enhance the understanding of the regional patterns of wetland morphological succession, and highlight that tidal range is not the primary driver of spatial variability in wetland zonation. Moreover, this baseline dataset of morphological thresholds can be used to support future large-scale comparisons and inform sustainable management strategies for coastal wetlands, particularly in the context of climate change. Future studies should analyse additional landscape metrics (e.g., vegetation density, sediment accretion rates) and evaluate the cumulative effects of site-specific drivers on wetland geometry.