Percorrer por autor "Pereira, Paulo"
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- 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.
- Inversions dominate evolution in the european sardine (sardina pilchardus) amid strong gene flowPublication . Sabatino, Stephen J.; Cabezas, M. Pilar; Pereira, Paulo; Garrido, Susana; Santos, António M.; Carneiro, Miguel; Santos, Paulo T.; Louro, Bruno; Cox, Cymon; Canario, Adelino; Veríssimo, AnaInversions can play key roles in the genetic architecture of adaptation, but the scale of their effects across different species remains poorly understood. Here, we use whole-genome sequencing and demographic modelling to investigate the influence of inversions on the population genomics of the r-selected European sardine (Sardina pilchardus). Allele frequency differences from millions of SNPs across 34 populations spanning the species' range were analysed. Genomic scans identified several extreme outlier regions overlapping large inversions (29–52Mbp), collectively representing over half the genome. Our findings suggest these inversions correlate with locally adapted life-history strategies. First, SNPs within outlier regions containing inversions exhibited striking allele frequency differences between Atlantic and Mediterranean sardines, which differ in key adaptive life-history traits. In the Atlantic, inversion allele frequencies varied latitudinally, while in the Mediterranean, they shifted longitudinally, aligning with temperature and oceanographic features that influence sardine life-history strategies. Moreover, adjacent populations in contrasting environments exhibited pronounced differences in inversion allele frequencies, accompanied by a marked reduction in migration between them. In contrast, spatial patterns at neutral loci showed widespread gene flow, isolation by distance within basins, and population structure between Atlantic and Mediterranean basins (except for the Canary Islands). These results suggest that the inversions studied are under selection and demonstrate the capacity of large inversions to shape genomewide patterns of genetic diversity and population structure in species characterized by widespread gene flow. Our work also offers crucial insights for stock delimitation and management of this commercially valuable species in the face of climate change.