Browsing by Author "Abecasis, David"
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- Acoustic telemetry and accelerometers: a field comparison of different proxies for activity in the marine environmentPublication . Pereñíguez, J. M.; Venerus, L. A.; Gutiérrez-Cánovas, C.; Abecasis, David; Ciancio, J. E.; Jiménez-Montalbán, P.; García-Charton, J. A.Different proxies for activity are used in the field of acoustic telemetry, a leading technology for the study of behaviour in the aquatic environment. Acoustic telemetry poses some shortcomings that may condition data interpretation. Here, we assessed some approaches commonly used to infer activity from acoustic telemetry data using acceleration biologgers as a benchmark. Specifically, we assessed (1) the performance of internal acceleration transmitters, (2) the consequences of averaging acceleration data into increasing time bins, (3) the occurrence of sampling bias in telemetry data acquisition, and (4) the performance of the number of detections and the depth range as proxies for activity. Despite some constraints of acoustic telemetry, acceleration transmitters had a good performance. Conversely, the number of detections and the depth range did not match well the activity estimates provided by acceleration biologgers. Besides, our results pointed to some issues in models concerning the predictive power of acceleration transmitters (linear predictor) over acceleration biologgers, warned about potential sampling bias associated with data acquisition with acoustic telemetry, and highlighted the relevance of considering inter-individual differences in behavioural studies. Finally, we provided some methodological perspectives that should be considered to plan fieldwork, analyse data, and interpret results on animal activity obtained with acoustic telemetry.
- An ecological framework for the development of a national MPA networkPublication . Abecasis, David; Afonso, Pedro; Erzini, KarimIsolated marine protected areas (MPAs) may not be enough to sustain viable populations of marine species, particularly the many small coastal MPAs which resulted due to social, economic and political constraints. Properly designed MPA networks can circumvent such limitations due to their potential synergistic positive effects, but this crucial step is frequently obstructed by lack of baseline ecological information. In this paper, we use systematic conservation planning on European Nature Information System coastal habitat information available for Portugal to demonstrate how an ecologically coherent nation-wide MPA network can be designed. We used the software Marxan to obtain near optimal solutions for each of three pre-determined conservation targets (10%, 30% and 50% protection) while maintaining the cost of including conservation units as low as possible. Marxan solutions were subsequently optimized with MinPatch by keeping each MPA above a minimum size that reflects the existing information on habitat use by some key marine fishes. Results show that 10% protection for all habitats would only require a relativelly small increase in the number (from 6 to 10) and area (from 479 km(2) to 509 km(2)) of already existing MPAs in mainland Portugal whereas substantial increases would be required to achieve the 50% target. This rather simple approach offers the added benefit of allowing design improvement as more relevant ecological information becomes available, including deeper habitat mapping across the whole continental shelf, allowing a coherent, adaptive and inclusive optimal MPA network to be designed.
- An integrated approach for the design of a marine protected area network applied to mainland PortugalPublication . Timonet, Diana; Abecasis, DavidThe high degree of marine habitat degradation and the depletion of marine resources has led to numerous calls and initiatives to increase the coverage of marine protected areas (MPAs). Currently, marine reserves (no-take areas) cover approximately 2.2% of the world's oceans whilst most calls and targets suggest protection levels should be between 20% and 30% in order to achieve both conservation and resource management objectives. In this study a systematic conservation planning framework was developed using ecological and socio-economic data. This framework was used to test different protection scenarios in Portugal. The current situation in mainland Portugal is alarming, with 0.2% of the waters under national jurisdiction included in MPAs and only 0.002% being marine reserves. Moreover, ecologically important habitats, such as seagrass beds and maerl beds, have less than 10% of their area protected. The solutions provided by Marxan, and subsequently improved with MinPatch, revealed that there is a need to considerably increase the area under protection. However, adequate protection could be achieved with a number of MPAs (between 5 and 14) similar to the number of already existing MPAs (n = 8). Different stakeholders (artisanal fisheries, industrial fisheries, and other human uses such as oil and gas, and offshore aquaculture) were considered in different scenarios, with the results of the multivariate analysis indicating that there are several solutions that satisfy all stakeholders. Therefore, the results of this study are a valuable starting point for the ongoing implementation process of an MPA network in Portugal since they integrate the most important stakeholders whilst also taking in consideration the ecological aspects. This framework can be applied elsewhere and can be easily amended whenever new information is available.
- Biologically meaningful distribution models highlight the benefits of the Paris Agreement for demersal fishing targets in the North Atlantic OceanPublication . Ramos Martins, Manuel; Assis, Jorge; Abecasis, DavidAim: With climate change challenging marine biodiversity and resource management, it is crucial to anticipate future latitudinal and depth shifts under contrasting global change scenarios to support policy-relevant biodiversity impact assessments [e.g., Intergovernmental Panel on Climate Change (IPCC)]. We aim to demonstrate the benefits of complying with the Paris Agreement (United Nations Framework Convention on Climate Change) and limiting environmental changes, by assessing future distributional shifts of 10 commercially important demersal fish species. Location: Northern Atlantic Ocean. Time period: Analyses of distributional shifts compared near present-day conditions (2000–2017) with two Representative Concentration Pathway (RCP) scenarios of future climate changes (2090–2100): one following the Paris Agreement climate forcing (RCP2.6) and another without stringent mitigation measures (RCP8.5). Major taxa studied: Demersal fish. Methods: We use machine learning distribution models coupled with biologically meaningful predictors to project future latitudinal and depth shifts. Structuring projections with information beyond temperature-based predictors allowed us to encompass the physiological limitations of species better. Results: Our models highlighted the additional roles of temperature, primary productivity and dissolved oxygen in shaping fish distributions (average relative contribution to the models of 32.12 ± 10.24, 15.6 ± 7.5 and 12.1 ± 6.1%, respectively). We anticipated a generalized trend of poleward shifts in both future scenarios, with aggravated changes in suitable area with RCP8.5 (average area loss with RCP2.6 = 13.3 ± 4.1%; RCP8.5 = 40.9 ± 13.3%). Shifts to deeper waters were also predicted to be of greater magnitude with RCP8.5 (average depth gain = 25.4 ± 21.5 m) than with RCP2.6 (average depth gain = 10.4 ± 7.9 m). Habitat losses were projected mostly in the Mediterranean, Celtic and Irish Seas, the southern areas of the North Sea and along the NE coast of North America. Main conclusions: Inclusion of biologically meaningful predictors beyond temperature in species distribution modelling can improve predictive performances. Limiting future climate changes by complying with the Paris Agreement can translate into reduced distributional shifts, supporting biodiversity conservation and resource management.
- Biophysical modelling and graph theory identify key connectivity hubs in the Mediterranean marine reserve networkPublication . Abecasis, David; Fragkopoulou, Eliza; Claro, Bruno; Assis, JorgeConnectivity plays a key role in the effectiveness of MPA networks ensuring metapopulation resilience through gene flow and recruitment effect. Yet, despite its recognized importance for proper MPA network functioning, connectivity is not often assessed and is very seldomly used in marine spatial planning. Here, we combined biophysical modelling with graph theory to identify Mediterranean marine reserves that support connectivity between different ecoregions through stepping-stone processes, thus preventing network fragmentation, and those that have an important role as propagule source areas contributing to the recruitment and rescue effects. We identified 19 reserves that play a key role towards the functioning of the network, serving either as stepping-stones or as propagule sources, yet with distinct patterns between ecological groups with contrasting propagule duration (PD). The Cote D'Azur marine reserves are important both as stepping-stones and propagule sources for several ecological groups. Also, key is the Capo Rizzuto and Plemmirio marine reserves due to their role as stepping stones between different marine ecoregions, particularly for species with longer PD (Pisces, Crustacea and Echinodermata). These results provide stakeholders and managers with crucial information for the implementation and management of an efficient marine reserve network in the Mediterranean.
- Depth and temperature preferences of meagre, argyrosomus regius, as revealed by satellite telemetryPublication . Winkler, Alexander; Astrid Bovim, Lily; Macena, Bruno C. L.; Gandra, Miguel; Erzini, Karim; Afonso, Pedro; Abecasis, DavidArgyrosomus regius (commonly referred to as meagre), is one of Europe's largest coastal bony fish species and supports important recreational and commercial fisheries in the Atlantic and Mediterranean coasts. Demand for this species, and more recently for their swim bladders, has led to regional population declines and growing importance as an aquaculture species. Despite intense research in captivity, little is known about the spatial ecology of A. regius's wild population, including basic information such as vertical migrations and depth/temperature preferences. Previous research based on indirect data suggests a seasonal habitat shift from shallow to deeper waters, but this has never been validated through direct high-resolution movement data. In this study, we tagged 13 adult A. regius with pop-up satellite archival tags in the South of Portugal, which successfully returned data from 11 individuals including high-resolution data from six recovered tags (mean, range: 167 days, 28-301 days). We found that adults of this population spend 95.2% of their time between 5 and 75 m depth (mean +/- SD, 30.9m +/- 18.3m) and do not venture beyond 125 m. Across seasons, A. regius move across water temperatures between 13.3 and 24.8 degrees C with a preferred thermal range between 14 and 18 degrees C where they spent 75.4% of their time. The inferential modelling using this electronic data validated previous hypotheses by showing significant differences between a shallower and warmer summer habitat vs. a deeper and cooler winter habitat. Visual investigation of the diel effects on depth preferences suggests subtle changes in depth use between day and night during the warmer months of the year. We speculate that these patterns are in response to the species' behavioural ecology and physiology, reflecting the seasonal changes in water stratification and presence of prey, as well as on the species reproduction, which results in summer spawning aggregations in shallower areas.
- Diel and seasonal changes in the spatial behaviour of a soft-sediment fish (Solea senegalensis) inside a marine reservePublication . Gandra, Miguel; Erzini, Karim; Abecasis, DavidThe protection provided by marine reserves directly depends on the short and long-term movement patterns of local organisms. Although there has been an increase in research assessing the behavioural patterns of fishes in reef-based habitats, there is still a paucity of studies addressing the benefits of marine protected areas (MPAs) for soft-sediment species. Here, we investigated both diel and seasonal shifts in spatial behaviour of the Senegalese sole, Solea senegalensis, within a recently-established marine reserve using long-term passive acoustic telemetry. Results showed variable levels of site attachment, with nearly half of the fish (n = 8) disappearing from the monitored area within 30 days, and the remaining (n = 9) being detected for periods up to 293 days and spending 95% of their time within an average area of 0.88 ± 0.46 km2. Although detection frequency was higher during daytime periods, the larger home range areas and greater movement observed during nighttime periods are consistent with a nocturnal activity regime, which might increase the vulnerability of S. senegalensis to illegal fishing. Additionally, patterns observed during the spawning season suggest the existence of shifts in habitat use linked with reproductive activity, opening the door to further research on soles' fine-scale interaction dynamics. Overall, this study provides novel insights into the ecology of a flatfish species and suggests that small no-take areas encompassing suitable soft-sediment habitats can offer adequate protection to at least part of the Senegalese sole population.
- Environmental representativity in marine protected area networks over large and partly unexplored seascapesPublication . Stratoudakis, Yorgos; Hilário, Ana; Ribeiro, Cláudia; Abecasis, David; Gonçalves, Emanuel J.; Andrade, Francisco; Carreira, Gilberto P.; Gonçalves, Jorge Manuel Santos; Freitas, Luis; Pinheiro, Luis Menezes; Batista, Marisa I.; Henriques, Miguel; Oliveira, Paulo B.; Oliveira, Paulo; Afonso, Pedro; Arriegas, Pedro Ivo; Henriques, SofiaConverting assemblages of marine protected areas (MPAs) into functional MPA networks requires political will, multidisciplinary information, coordinated action and time. We developed a new framework to assist planning environmental representativity in a network across the marine space of Portugal, responding to a political commitment to protect 14% of its area by 2020. An aggregate conservation value was estimated for each of the 27 habitats identified, from intertidal waters to the deep sea. This value was based on expert-judgment scoring for environmental properties and features relevant for conservation, chosen to reflect the strategic objectives of the network, thus providing an objective link between conservation commitments and habitat representativity in space. Additionally, habitats' vulnerability to existing anthropogenic pressures and sensitivity to climate change were also scored. The area coverage of each habitat in Portugal and within existing MPAs (regionally and nationally) was assigned to a scale of five orders of magnitude (from < 0.01% to >10%) to assess rarity and existing representation. Aggregate conservation value per habitat was negatively correlated with area coverage, positively correlated with vulnerability and was not correlated with sensitivity. The proposed framework offers a multi-dimensional support tool for MPA network development, in particular regarding the prioritization of new habitats to protect, when the goal is to achieve specific targets while ensuring representativity across large areas and complex habitat mosaics. It requires less information and computation effort in comparison to more quantitative approaches, while still providing an objective instrument to scrutinize progress on the implementation of politically set conservation targets.
- Facultative cleaning behaviour of juvenile Diplodus sargus (Sparidae) and its ecological role in marine temperate watersPublication . Neto, J.; Vieira, D.; Abecasis, David; Marques, J.; Gordo, L.; Robalo, J. I.; Bispo, R.; Araújo, M.; Almada, F.The diversity and abundance of cleaner species have been frequently associated with ectoparasite load and ecological wealth of tropical fish communities. Cleaning behaviour in temperate regions has received less attention, with few labrid species being described as cleaners. The context and frequency of cleaning behaviour by juvenile white seabream Diplodus sargus are described. Surface observations from pontoons in yachting marinas were carried out based on a method used in a recent first report of cleaning behaviour by this northeastern Atlantic and Mediterranean sparid. A total of 51 h of observations revealed that these juveniles (<10 cm total length [TL]) display similar or higher cleaning rates (13.1 cleaning events per hour) compared to other temperate cleaners. The high cleaning rates, high abundance of young D. sargus on rocky shores along their distribution area and preferential targeting of adults by coastal fisheries highlight the ecological importance of D. sargus. The most common client species include grey mullets (Mugilidae), which represent 93.5% of total cleaning events registered. Regarding TL, clients were 4.6 to 6.6 times larger than cleaners. Environmental factors such as water temperature (14.0-24.0°C), wave exposure (6.0-17.0 s) and wind speed (2.0-8.0 m s-1) influence white seabream cleaning rates. Thus, a combination of factors may affect the health of temperate client fish communities. On a different perspective, these results also highlight the potential of juvenile D. sargus in integrated multitrophic aquaculture. In conclusion, white seabream cleaning behaviour plays an important role in temperate fish communities and its relevance in different habitats should be further assessed.
- A fine-tuned global distribution dataset of marine forestsPublication . Assis, J.; Fragkopoulou, Eliza; Frade, Duarte; Neiva, J.; Oliveira, André; Abecasis, David; Faugeron, Sylvain; Serrao, EsterSpecies distribution records are a prerequisite to follow climate-induced range shifts across space and time. However, synthesizing information from various sources such as peer-reviewed literature, herbaria, digital repositories and citizen science initiatives is not only costly and time consuming, but also challenging, as data may contain thematic and taxonomic errors and generally lack standardized formats. We address this gap for important marine ecosystem-structuring species of large brown algae and seagrasses. We gathered distribution records from various sources and provide a fine-tuned dataset with ~2.8 million dereplicated records, taxonomically standardized for 682 species, and considering important physiological and biogeographical traits. Specifically, a flagging system was implemented to signal potentially incorrect records reported on land, in regions with limiting light conditions for photosynthesis, and outside the known distribution of species, as inferred from the most recent published literature. We document the procedure and provide a dataset in tabular format based on Darwin Core Standard (DwC), alongside with a set of functions in R language for data management and visualization.