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Projeto de investigação
BIVALGAE: Bioremediation capacity of integrated systems of shellfish and primary producers to mitigate global change and restore coastal ecosystems
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Recreational harvesting of the wedge clam (Donax trunculus) in southern Portugal: characterization of the activity based on harvesters’ perception and local ecological knowledge
Publication . Sordo, Laura; Vasconcelos, Paulo; Piló, David; Carvalho, André N.; Pereira, Fábio; Gaspar, Miguel
This study was the first attempt to characterize the recreational harvesting of the wedge clam (Donax trunculus). For this purpose, 403 face-to-face interviews were performed in the summers of 2018 and 2019 in southern Portugal. The majority of the harvesters frequented the selected beaches during holidays and collected wedge clams as a hobby for an appetizer. The respondents reported an inter-annual variation in their catches of wedge clam with a decreasing abundance in 2018 followed by a recovery in 2019, but with more recreational harvesters collecting undersized individuals. Although most harvesters declared to consume D. trunculus, only a few bought wedge clams being the clams' size a secondary factor in their valorization. The majority of the recreational harvesters did not know the species' minimum conservation reference size nor the legally allowed maximum daily catch. It was estimated that recreational harvesters can collect 13 tonnes of wedge clams during the summer season along the southeastern coast of Algarve. Even though manual harvesting is not an efficient fishing technique, the lack of selectivity of harvesters can eventually compromise the resilience of D. trunculus populations. Despite most respondents affirmed to get informed about marine biotoxins, most surveys were done during periods of interdiction for shellfish harvesting. The present results revealed that the population is still unaware of the health risks of consuming shellfish contaminated with biotoxins. Educational activities and awareness campaigns are required to further inform recreational harvesters about the regulations in force for this activity and the sanitary threats of marine biotoxins.
Effect of warming on European green crab (Carcinus maenas) populations from larvae to sexual maturity
Publication . Monteiro, João Nuno; Ovelheiro, Andreia; SORDO, LAURA; Palma, Jorge; Pinto, Miguel; Teodosio, Maria; Leitão, Francisco
Understanding the effects of climate change on the physiology of marine species, particularly during their early life stages (larvae and juveniles), is essential for predicting population dynamics. Carcinus maenas is a widely distributed species of significant ecological and economic importance. This experimental study investigates the effects of warming on the early life stages of the European green crab, C. maenas, through two complementary experiments: (1) larval development and survival were assessed under three temperature regimes-approximately 18.5 degrees C (representing the annual average Portuguese seawater temperature between 1980 and 2020, used as the control), and two projected climate change scenarios: RCP 4.5 (+1.5 degrees C) and RCP 8.5 (+3.5 degrees C), and (2) juvenile survival and growth were monitored in mesocosms from early settlement to sexual maturity. Results indicated that larval mortality exceeded 90 % across all treatments, with 75 % occurring within the first 8 days (95 % CI: 7-8), and that warming enhanced larval survival, with the RCP 4.5 scenario yielding the highest survival rates compared with the control. Additionally, warming also reduced the pelagic larval duration, which declined from 27 (+/- 2) days at 18.5 degrees C to 16 (+/- 1) days at 22 degrees C. Similarly, the duration of the megalopa (settlement) stage decreased from 10 to 6 days. Therefore, despite high mortality, accelerated development under warming may enhance population resilience. Juvenile mortality was also high, with 50 % of settled individuals dying within the first 50 (95 % CI: 31-46) days, and differences in growth and survival between sexes were observed: females reached sexual maturity faster than males 83 +/- 12 and 109 +/- 20 days, respectively. Moreover, only 24 % (95 % CI: 16-34) of the settled females reached sexual maturity, compared to just 9 % of males (95 % CI: 5-18). These results indicate that C. maenas reach reproductive maturity within six months. The biological data reveal a fast growth increment, high larval and juvenile mortality, and suggest that projected climate change scenarios through the end of the century will have a limited impact on the species' population dynamics and recruitment.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
CEEC IND 3ed
Número da atribuição
2020.03396.CEECIND/CP1639/CT0001