Percorrer por autor "Fragkopoulou, Eliza"
A mostrar 1 - 10 de 26
Resultados por página
Opções de ordenação
- Artificial intelligence convolutional neural networks map giant kelp forests from satellite imageryPublication . Marquez, L.; Fragkopoulou, Eliza; Cavanaugh, K. C.; Houskeeper, H. F.; Assis, J.Climate change is producing shifts in the distribution and abundance of marine species. Such is the case of kelp forests, important marine ecosystem-structuring species whose distributional range limits have been shifting worldwide. Synthesizing long-term time series of kelp forest observations is therefore vital for understanding the drivers shaping ecosystem dynamics and for predicting responses to ongoing and future climate changes. Traditional methods of mapping kelp from satellite imagery are time-consuming and expensive, as they require high amount of human effort for image processing and algorithm optimization. Here we propose the use of mask region-based convolutional neural networks (Mask R-CNN) to automatically assimilate data from open-source satellite imagery (Landsat Thematic Mapper) and detect kelp forest canopy cover. The analyses focused on the giant kelp Macrocystis pyrifera along the shorelines of southern California and Baja California in the northeastern Pacific. Model hyper-parameterization was tuned through cross-validation procedures testing the effect of data augmentation, and different learning rates and anchor sizes. The optimal model detected kelp forests with high performance and low levels of overprediction (Jaccard's index: 0.87 +/- 0.07; Dice index: 0.93 +/- 0.04; over prediction: 0.06) and allowed reconstructing a time series of 32 years in Baja California (Mexico), a region known for its high variability in kelp owing to El Nino events. The proposed framework based on Mask R-CNN now joins the list of cost-efficient tools for long-term marine ecological monitoring, facilitating well-informed biodiversity conservation, management and decision making.
- Bio‐ORACLE v3.0. pushing marine data layers to the CMIP6 earth system models of climate change researchPublication . Assis, Jorge; Fernández Bejarano, Salvador Jesús; Salazar, Vinícius W.; Schepers, Lennert; Gouvêa, Lidiane; Fragkopoulou, Eliza; Leclercq, Frederic; Vanhoorne, Bart; Tyberghein, Lennert; Serrao, Ester; Verbruggen, Heroen; De Clerck, OlivierMotivation: Impacts of climate change on marine biodiversity are often projected with species distribution modelling using standardized data layers representing physical, chemical and biological conditions of the global ocean. Yet, the available data layers (1) have not been updated to incorporate data of the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6), which comprise the Shared Socioeconomic Pathway (SSP) scenarios; (2) consider a limited number of Earth System Models (ESMs), and (3) miss important variables expected to influence future biodiversity distributions. These limitations might undermine biodiversity impact assessments, by failing to integrate them within the context of the most up-to-date climate change projections, raising the uncertainty in estimates and misinterpreting the exposure of biodiversity to extreme conditions. Here, we provide a significant update of Bio-ORACLE, extending biologically relevant data layers from present-day conditions to the end of the 21st century Shared Socioeconomic Pathway scenarios based on a multi-model ensemble with data from CMIP6. Alongside, we provide R and Python packages for seamless integration in modelling workflows. The data layers aim to enhance the understanding of the potential impacts of climate change on biodiversity and to support well-informed research, conservation and management. Main Types of Variable Contained: Surface and benthic layers for, chlorophyll-a, diffuse attenuation coefficient, dissolved iron, dissolved oxygen, nitrate, ocean temperature, pH, phosphate, photosynthetic active radiation, total phytoplankton, total cloud fraction, salinity, silicate, sea-water direction, sea-water velocity, topographic slope, topographic aspect, terrain ruggedness index, topographic position index and bathymetry, and surface layers for air temperature, mixed layer depth, sea-ice cover and sea-ice thickness. Spatial Location and Grain: Global at 0.05 degrees resolution. Time Period and GrainDecadal from present-day to the end of the 21st century (2000-2100). Major Taxa and Level of Measurement: Marine biodiversity associated with surface and epibenthic habitats. Software Format: A package of functions developed for Python and R software.
- 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.
- Bottom trawling threatens future climate refugia of rhodoliths globallyPublication . Fragkopoulou, Eliza; Serrao, Ester; Horta, Paulo A.; Koerich, Gabrielle; Assis, J.Climate driven range shifts are driving the redistribution of marine species and threatening the functioning and stability of marine ecosystems. For species that are the structural basis of marine ecosystems, such effects can be magnified into drastic loss of ecosystem functioning and resilience. Rhodoliths are unattached calcareous red algae that provide key complex three-dimensional habitats for highly diverse biological communities. These globally distributed biodiversity hotspots are increasingly threatened by ongoing environmental changes, mainly ocean acidification and warming, with wide negative impacts anticipated in the years to come. These are superimposed upon major local stressors caused by direct destructive impacts, such as bottom trawling, which act synergistically in the deterioration of the rhodolith ecosystem health and function. Anticipating the potential impacts of future environmental changes on the rhodolith biome may inform timely mitigation strategies integrating local effects of bottom trawling over vulnerable areas at global scales. This study aimed to identify future climate refugia, as regions where persistence is predicted under contrasting climate scenarios, and to analyze their trawling threat levels. This was approached by developing species distribution models with ecologically relevant environmental predictors, combined with the development of a global bottom trawling intensity index to identify heavily fished regions overlaying rhodoliths. Our results revealed the importance of light, thermal stress and pH driving the global distribution of rhodoliths. Future projections showed poleward expansions and contractions of suitable habitats at lower latitudes, structuring cryptic depth refugia, particularly evident under the more severe warming scenario RCP 8.5. Our results suggest that if management and conservation measures are not taken, bottom trawling may directly threaten the persistence of key rhodolith refugia. Since rhodoliths have slow growth rates, high sensitivity and ecological importance, understanding how their current and future distribution might be susceptible to bottom trawling pressure, may contribute to determine the fate of both the species and their associated communities.
- Coastal oceanographic connectivity at the global scale: a dataset of pairwise probabilities and travel times derived from biophysical modelingPublication . Assis, Jorge; Fragkopoulou, Eliza; Serrao, Ester A.; Bastos Araújo, MiguelOcean currents are fundamental drivers of marine biodiversity distribution, mediating the exchange of genetic material and individuals between populations. Their effect ranges from creating barriers that foster isolation to facilitating long-distance dispersal, which is crucial for species expansion and resilience in the face of climate change. Despite the significance of oceanographic connectivity, comprehensive global estimates remain elusive, hindering our understanding of species' dispersal ecology and limiting the development of effective conservation strategies. We present the first dataset of connectivity estimates (including probability of connectivity and travel time) along the world's coastlines. The dataset is derived from Lagrangian simulations of passive dispersal driven by 21 years of ocean current data and can be combined with species' biological traits, including seasonality and duration of planktonic dispersal stages. Alongside, we provide coastalNet, an R package designed to streamline access, analysis, and visualization of connectivity estimates. The dataset provides a new benchmark for research in oceanographic connectivity, enabling a deeper exploration of the complex dynamics of coastal marine ecosystems and informing more effective conservation strategies.
- A dataset of cold-water coral distribution recordsPublication . Balogh, Viktória; Fragkopoulou, Eliza; Serrao, Ester; Assis, JorgeSpecies distribution data are key for monitoring present and future biodiversity patterns and informing conservation and management strategies. Large biodiversity information facilities often contain spatial and taxonomic errors that reduce the quality of the provided data. Moreover, datasets are frequently shared in varying formats, inhibiting proper integration and interoperability. Here, we provide a qualitycontrolled dataset of the diversity and distribution of coldwater corals, which provide key ecosystem services and are considered vulnerable to human activities and climate change effects. We use the common term cold-water corals to refer to species of the orders Alcyonacea, Antipatharia, Pennatulacea, Scleractinia, Zoantharia of the subphylum Anthozoa, and order Anthoathecata of the class Hydrozoa. Distribution records were collated from multiple sources, standardized using the Darwin Core Standard, dereplicated, taxonomically corrected and flagged for potential vertical and geographic distribution errors based on peer-reviewed published literature and expert consulting. This resulted in 817,559 quality-controlled records of 1,170 accepted species of cold-water corals, openly available under the FAIR principle of Findability, Accessibility, Interoperability and Reusability of data. The dataset represents the most updated baseline for the global cold-water coral diversity, and it can be used by the broad scientific community to provide insights into biodiversity patterns and their drivers, identify regions of high biodiversity and endemicity, and project potential re-distribution under future climate change. It can also be used by managers and stakeholders to guide biodiversity conser-vation and prioritization actions against biodiversity loss. (c) 2023 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
- 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.
- Genetic diversity increases with depth in red gorgonian populations of the Mediterranean Sea and the Atlantic OceanPublication . Pilczynska, Joanna; Cocito, Silvia; Boavida, Joana; Serrao, Ester; Assis, J.; Fragkopoulou, Eliza; Queiroga, HenriqueIn the ocean, the variability of environmental conditions found along depth gradients exposes populations to contrasting levels of perturbation, which can be reflected in the overall patterns of species genetic diversity. At shallow sites, resource availability may structure large, persistent and well-connected populations with higher levels of diversity. In contrast, the more extreme conditions, such as thermal stress during heat waves, can lead to population bottlenecks and genetic erosion, inverting the natural expectation. Here we examine how genetic diversity varies along depth for a long-lived, important ecosystem-structuring species, the red gorgonian, Paramuricea clavata.
- A global assessment of the effectiveness of different protection levels in marine protected areas of tropical waters, following a new categorizationPublication . Fragkopoulou, Eliza; Erzini, Karim; Costa, Barbara Horta eMarine Protected Areas (MPAs) are a common tool for conserving and managing marine and coastal ecosystems. MPAs encompass a range of protection levels, from fully protected areas (FPAs) to partially protected areas (PPAs), with restriction of particular activities, gear types or user groups. There is a growing body of scientific evidence supporting the ecological benefits of FPAs, but it is very difficult to generalize about the effects of partial protection, due to their high variability. However, it is critical to determine whether PPAs and FPAs provide similar ecological benefits, since the establishment of FPAs is in some situations a less popular strategy, due to the loss of fishing grounds and local sociopolitical antagonism. For the purpose of conducting a meta-analysis, we synthesized peer-reviewed studies comparing biological measures (biomass and density) of commercially targeted fish species in PPAs relative to FPAs and open access areas (OAs) across the tropical seas, resulting in a database of 33 PPAs. A new categorization scheme was used to group the different types of PPAs according to the extractive activities permitted within their boundaries, into three categories: highly regulated PPAs, moderately regulated PPAs, and weakly and very weakly regulated PPAs. The response to protection was examined in relation to PPA category, age and size. The present synthesis indicates that, overall, tropical PPAs generate greater biological responses in the biomass of targeted fish compared to OAs and demonstrate no significant differences when compared to FPAs. Grouping the PPAs according to uses allowed revealed that areas with highly regulated extraction exhibit greater biomass of targeted fish relative to areas with weakly regulated categories. The density of the targeted fish species did not demonstrate a response to the different protection regimes as strong as the biomass did. Although there was a high degree of variability in the magnitude of responses to protection, the age and size of the PPAs explained some of this variability. Overall, PPAs with limited and well regulated extraction activities may confer benefits and be a valuable conservation management option, especially, in areas where FPAs are not a viable option or in multi-zoning MPAs.
- Global biodiversity patterns of marine forests of brown macroalgaePublication . Fragkopoulou, Eliza; Serrao, Ester; De Clerck, Olivier; Costello, Mark J.; Araújo, Miguel B.; Duarte, Carlos M.; Krause‐Jensen, Dorte; Assis, JorgeAim Marine forests of brown macroalgae create essential habitats for coastal species and support invaluable ecological services. Here, we provide the first global analysis of species richness and endemicity of both the kelp and fucoid biomes. Location Global. Time period Contemporary. Major taxa studied Marine forests of brown macroalgae, formed by kelp (here defined as orders Laminariales, Tilopteridales and Desmarestiales) and fucoid (order Fucales), inhabiting subtidal and intertidal environments. Methods We coupled a large dataset of macroalgal observations (420 species, 1.01 million records) with a high-resolution dataset of relevant environmental predictors (i.e., light, temperature, salinity, nitrate, wave energy and ice coverage) to develop stacked species distribution models (stacked SDMs) and yield estimates of global species richness and endemicity. Results Temperature and light were the main predictors shaping the distribution of subtidal species, whereas wave energy, temperature and salinity were the main predictors of intertidal species. The highest regional species richness for kelp was found in the north-east Pacific (maximum 32 species) and for fucoids in south-east Australia (maximum 53 species), supporting the hypothesis that these regions were the evolutionary sources of global colonization by brown macroalgae. Locations with low species richness coincided between kelp and fucoid, occurring mainly at higher latitudes (e.g., Siberia) and the Baltic Sea, where extensive ice coverage and low-salinity regimes prevail. Regions of high endemism for both groups were identified in the Galapagos Islands, Antarctica, South Africa and East Russia. Main conclusions We estimated the main environmental drivers and limits shaping the distribution of marine forests of brown macroalgae and mapped biogeographical centres of species richness and endemicity, which largely coincided with the expectation from previous evolutionary hypotheses. The mapped biodiversity patterns can serve as new baselines for planning and prioritizing locations for conservation, management and climate change mitigation strategies, flagging threatened marine forest regions under different climate change scenarios.
- «
- 1 (current)
- 2
- 3
- »