Percorrer por autor "Baeta, Alexandra"
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- Feeding ecology of the cephalopod Octopus vulgaris illustrated by a stable-isotope approachPublication . Seixas, Sónia; Baeta, Alexandra; Marques, João CarlosCephalopods play a key role in the marine environment, but studies of their feeding ecology are still limited. Stomach content analysis have been the main method used for studying the diet of cephalopods, but despite being time-consuming, the prey is often difficult to determine. This technique allows the determination of species eaten, using hard parts that tend to resist digestion and remain in the stomach for longer period of time or hard parts which resist digestion, such as crustacean exoskeletons, cephalopod beaks, fish otoliths, and bones. A stable isotope study was carried out seasonally to investigate the feeding ecology of the cephalopod Octopus vulgaris, and its potential prey species were identified according to the species that appeared in pots collected by fisherman. The food items identified were the fan mussel (Atrina fragilis), Algarve volute (Cymbium olla), Henslow's swimming crab (Polybius henslowii), and the red-band fish (Cepola macrophthalma). The stable isotope mixing model SIAR indicated that O. vulgaris is predating mainly on the bivalve A. fragilis (mean value: 70%). P. henslowii could have a contribution of 18% to the cephalopod diet, whereas the gastropod C. olla and the fish C. macrophthalma were much less important to the consumer diet (7 and 5%, respectively).
- Integrating prey monitoring and stable isotope analysis to assess the diet of Octopus vulgaris in Portuguese coastal waterPublication . Seixas, Sónia; Baeta, Alexandra; Marques, João CarlosThis study explores the feeding ecology of Octopus vulgaris in the Cascais region through a combined approach of long-term prey monitoring and stable isotope analysis. Over several months, we worked with local fishermen to observe and record prey items found in octopus pots and those carried by octopuses at the time of capture. These field observations enabled the identification of key prey species, which were subsequently analysed isotopically to estimate their contribution to the octopus diet. The results show that Atrina fragilis is the main prey, making up about 70 %, followed by Polybius henslowii (18 %), with Cymbium olla and Cepola macrophthalma contributing smaller amounts. Our findings highlight the limitations of traditional stomach content analysis, which often underestimates soft-bodied or highly digested prey, and emphasise the importance of isotopic methods to provide a more comprehensive and long-term view of trophic interactions. This integrated approach enhances our understanding of O. vulgaris feeding strategies and has significant implications for ecological research and the sustainable management of fisheries in the region.