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Projeto de investigação
Towards an ecological theory of deep diving in large pelagic fishes
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Intra- and interspecific associations in two predatory reef fishes at a shallow seamount
Publication . Gandra, Miguel; Afonso, Pedro; Fontes, Jorge
the spatial dynamics of marine populations are shaped by habitat availability, environmental variability and individual interactions, particularly when multiple species share limited habitat such as patchy offshore reefs. the yellowmouth barracuda Sphyraena viridensis and the almaco jack Seriola rivoliana are the 2 most abundant bentho-pelagic reef predators in the Azores archipelago (central North Atlantic). They aggregate at shallow offshore seamounts, and largely share diet preferences, but very little is known about how habitat and resources are shared by these predators intra- and inter-specifically. Here we use long-term (over 3 yr) passive acoustic telemetry to investigate the patterns of activity, space use and associative behaviour at an isolated, small shallow seamount. By quantifying fine-scale spatiotemporal overlaps and performing null model randomization tests, we found evidence of non-random associations, mostly between conspecifics of both species, as well as shifts in diel and seasonal patterns of space occupancy. Both species were detected more often during spring, and appear to be more active during daytime, suggesting the absence of fine-scale temporal habitat partitioning. Additionally, we found evidence of size-dependent spatial behaviour in almaco jack, with similarly sized individuals co-occurring more often and larger specimens being more infrequently detected. This study quantitatively assesses individual associations using solely presence-absence data collected through passive acoustic telemetry, showing the potential of this approach in a broader application to a significant number of past and ongoing studies, even if many were not originally designed to study this important aspect of fish ecology.
Developing productivity and susceptibility attributes towards a rapid management-risk assessment of seaweed
Publication . Milla-Figueras, David; Torres, P.; Botelho, A. Z.; Larrea, A.; Parente, M. I.; Afonso, P.
The challenge of balancing conservation with sustainable use of marine resources faced by fisheries managers is quite often constrained by limited data on key species. This has become particularly true in the case of seaweed, which provide essential habitats for a diverse range of species in marine ecosystems and have long been valued by humans as food or, more recently, for their industrial applications. The expanding seaweed industry relies heavily on harvesting but historical declines in seaweed populations raise concerns over sustainability, leveraged by a general data-poor scenario for these species. To address this, we propose adapting the Productivity and Susceptibility Analysis (PSA) method—traditionally used in fishery assessments—for seaweeds. This novel approach incorporates the unique biology of seaweeds, including growth, reproduction, and susceptibility to environmental changes and harvesting practices, to evaluate their vulnerability. We applied this adapted PSA framework to a case study of seaweed harvesting in the Azores Archipelago, mid-north Atlantic, demonstrating its applicability in future science-based seaweed fisheries management srtategies. Among the 18 species studied, we identified five of high vulnerability (Cystoseira pustulata, Fucus spiralis, Gongolaria abies-marina, Laminaria ochroleuca, and Ericaria selaginoides). Our adapted PSA framework also considers local ecological impacts, stakeholder input, and relevant environmental factors, providing targeted management recommendations. While such a PSA does not replace stock assessments, it serves as a valuable risk assessment tool, identifying species needing greater management attention despite data limitations. Ultimately, this framework supports local, national and international policy and management measures, contributing to the conservation of coastal marine ecosystems.
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Fundação para a Ciência e a Tecnologia
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Investigador FCT
Número da atribuição
IF/01640/2015/CP1299/CT0001