Percorrer por autor "Cereja, Rui"
A mostrar 1 - 3 de 3
Resultados por página
Opções de ordenação
- Do toxic epiphytic microalgae compromise the consumption of edible macroalgae?Publication . Chainho, Tomás; Cereja, Rui; Barbosa, Miguel; Xavier, Maria João; Pereira, Alícia; Oliveira, Inês; Caria Mendes, Madalena; Marques, António; Reis Costa, PedroThe growing global demand for farmed macroalgae highlights the need to better understand potential contaminant loads, including toxins from harmful algal blooms, and their implications to human health. In this study, the green macroalga Ulva rigida was co-cultivated with the epiphytic dinoflagellate Prorocentrum lima to determine whether toxins produced by the toxic dinoflagellate accumulate in the macroalgae and assess the efficacy of post-harvest processing techniques to reduce or eliminate the risk of toxins contamination. Ulva rigida (60 g wet weight) was maintained under controlled laboratory conditions in sterile F/2 medium and in co-culture with P. lima. Macroalgae were divided into two treatments: a) no processing; b) processing. Samples were analysed by LC-MSMS to detect okadaic acid (OA) and dinophysistoxin-1 (DTX1). High toxins levels were detected after 7 days of exposure to P. lima. Contrastingly, the post-harvesting process of washing and scrubbing was efficient in reducing toxins loads, indicating that lipophilic toxins were surface bound and can be easily eliminated using efficient post-harvest processes. The results indicate that epiphytic toxic microalgae may jeopardize the consumption of macroalgae, particularly if appropriate post-harvest processes are not applied to ensure the safety of farmed macroalgae for consumers.
- Farmed and wild macroalgae as a safe source of macro and trace elementsPublication . Chainho, Tomás; Cereja, Rui; Pereira, Alícia; Marques, Vera; Silva, João C.; Pessanha, Sofia; Reis Costa, Pedro; Marques, AntónioThe increasing popularity of macroalgae products highlights their potential as a safe source of essential macro and microelements for consumers. This study characterized wild and farmed macroalgae elemental composition and assessed the presence of biotoxins to identify potential health risks. Wild and farmed macroalgae samples were collected throughout 2024–2025, from three aquaculture production sites along the Portuguese coast (Ria de Aveiro, Matosinhos, and Olhão). Samples were freeze-dried, compressed and using a microXRF spectrometer, elemental composition was assessed. Macroalgae species factor was the strongest driver of elemental composition, explaining over 80% variation in macro and trace elements. Origin did not showcase statistical significance for elemental composition. Seasonal differences, though relatively small in extent, significantly impacted redox-sensitive elements in macroalgae, namely copper and manganese. All elements stayed below 30% of the recommended dietary recommendations, except iron (ranging from 0.5% to 111.8% of UL%) and Mn (ranging from 0.1% to 101% of UL%). All samples revealed the absence of regulated marine toxins. Only traces of the non-regulated cyclic-imine toxin SPX1 were detected in samples of Fucus vesiculosus. All quantified elements do not represent any risk for human health, strengthening the safety of macroalgae from the Portuguese coast.
- Unknown facts of the biology of Polybius henslowii - Effect of gender on claw morphology and dietPublication . Cereja, Rui; Vinagre, Catarina; Silva, AnaPolybius henslowii is known for both its unusual swimming behaviour and for forming large shoals during its pelagic phase. Although being a common species, many aspects of its biology remain unknown. In this work, P. henslowif s sexual dimorphism was examined in both dietary composition and morphologies of carapace and claw. Males were generally larger than females both on carapace and claw sizes. Claw morphology differed between males and females. Diet was similar between genders. Hence, we suggest that the sexual dimorphism in claw morphology results from gender-specific behaviours instead of diet. The most common dietary items were sand (51.2%), squid (34.1%) and crustaceans (26.8%). The same items were also the most important in volume, but with squids being more important than sand. The diet composition of P. henslowii was consistent with previous studies but also presenting sediment as an important item.