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Browsing by Author "Ferreira, Bruno Miguel Santos"

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  • Seaweed extracts: an eco-friendly approach to mitigate amyloodinium ocellatum parasite of marine fish
    Publication . Ferreira, Bruno Miguel Santos; Modesto, Teresa; Quintã, Raquel
    The ectoparasite Amyloodinium ocellatum poses a significant threat to both brackish and marine warmwater aquaculture fishes, causing severe morbidity and mortality. Current treatments for amyloodiniosis are limited and environmentally unfriendly. Seaweed extracts, known for their antiparasitic, anti-inflammatory, and antibacterial properties, offer a promising direction for addressing this gap. This research was dedicated to investigating the effects of six aqueous extracts from seaweed species, Asparagopsis armata gametophyte, Asparagopsis sp. tetrasporophyte, Sphaerococcus coronopifolius, Gracilaria sp., Halopteris scoparia, and Ulva sp., in delaying the development and/or mortality rates of two life stages of A. ocellatum, the tomonts and the dinospores. The study utilized a controlled in vitro environment, where each seaweed extract was subjected to various dilutions (1:1, 1:5, 1:10, 1:25, 1:50, and 1:100), along with a control treatment using autoclaved seawater. The inactivation rates of tomonts were monitored over 96 hours, while dinospore mortality rates were observed over 6 hours. The results revealed that none of the extract treatments achieved complete inactivation of tomonts, instead they temporarily inhibited their activity. Notably, the extract from the red seaweed A. armata gametophyte displayed the highest effectiveness, with inactivity rates reaching 99% at 24 hours and 48% at 96 hours. Similarly, no seaweed extract consistently induced significant higher mortalities in dinospores when compared to the control group, which exhibited substantial mortality rates. Overall, this study shows the promising outcomes achieved, particularly with the A. armata gametophyte extract in tomont inactivation. Besides, optimized outcomes might be expected by utilizing an optimized approach for the methodology of the dinospores trials.
    2023-12-21Master thesis Open access Show more