http://hdl.handle.net/10174/14287 Fri, 11 Sep 2026 14:00:42 GMT 2026-09-11T14:00:42Z http://hdl.handle.net/10174/42581 Title: Integrating benthic nematode and bacterial communities to assess spatial-temporal dynamics and ecosystem functioning in estuarine sediments Authors: Vieira, Soraia; Adão, Helena; Vicente, Cláudia Abstract: Coastal and estuarine ecosystems are important carbon reservoirs, processes such as recycling of nutrients and degradation of pollutants, occur in soft-sediment intertidal and subtidal habitats. Benthic communities dominated by microorganisms and metazoans play a central role in mediating biogeochemical processes and energy pathways being powerful bioindicators of sediment habitat condition. Strong nematode–bacteria interconnections have been documented, with nematodes stimulating microbial activity and bacteria providing adaptive responses under stressful and low-oxygen conditions. This study aimed to investigate the spatial and temporal interactions between these communities and sediment biogeochemical conditions in the Sado Estuary (Portugal). Combining morphological and molecular approaches, it was explored how biodiversity patterns reflect environmental gradients and ecosystem functioning. Distinct ecological responses between the two biological groups were obtained. Nematode assemblages showed strong spatial and temporal variability, responding rapidly to site-specific environmental changes, whereas bacterial communities were mainly structured by spatial variability directly liked with sediment biogeochemical properties. Combining different approaches bacterial and nematode communities proved to be powerful ecological indicators capable of capturing the dynamics of macrobenthic food webs of the Sado estuary. These relationships between community composition and environmental drivers highlighted that diversity patterns of benthic communities can be integrated to better understand sediment trophic conditions and the impact on energy pathways. The co-occurrence of nematode and bacterial communities can provide a powerful framework for linking biodiversity patterns with ecosystem functioning, improving the evaluation of blue carbon restoration trajectories. The predominance of specific metabolic processes may therefore indicate environmental conditions that favour carbon retention and long-term burial. Such functional insight can contribute to improving the evaluation of blue carbon ecosystems and provide a scientific basis for the development of future predictive frameworks that combine biodiversity data, metabolic pathway analyses, and advanced modelling approaches to assess carbon sequestration potential and support restoration and conservation strategies.   Coastal and estuarine ecosystems represent important carbon reservoirs where key processes such as nutrient recycling, organic matter degradation and pollutant transformation occur in soft-sediment intertidal and subtidal habitats. These environments host complex benthic communities dominated by microorganisms and meiofauna that regulate biogeochemical processes and energy pathways. Among them, benthic bacteria and nematodes are highly sensitive to habitat conditions being powerful ecological indicators of sediment status and functioning. Their interactions have been documented, nematodes stimulate microbial activity, while bacteria provide adaptive responses to nematodes under stressful and low-oxygen conditions. This study investigated the spatial and temporal relationships between nematode assemblages, bacterial communities through different sediment biogeochemical conditions in Sado Estuary (SW cost of Portugal). Combining morphological identification of nematodes assemblages with 16S rRNA metagenomic characterization of bacterial communities, was explored how environmental variations shape biodiversity patterns and ecosystem functioning across contrasting sediment habitats. Results revealed distinct and complementary ecological responses between both groups. Nematode assemblages exhibited strong spatial and temporal variability, responding rapidly to site-specific environmental changes and shifts in trophic conditions, whereas bacterial communities were mainly structured by spatial variability due to sediment properties such as organic matter, grain size and oxygen availability. Together, these communities captured key patterns in benthic ecosystem dynamics. Nematodes reflected short-term ecological responses in line with benthic food webs dynamics, while bacterial communities provided insights into the dominant metabolic pathways driving sediment biogeochemistry. The predominance of specific microbial processes, including aerobic organic matter degradation or anaerobic sulfur-reduction pathways, revealed how environmental conditions regulate energy flow and nutrient cycling in estuarine sediments. The integration of both communities’ diversity provides a powerful framework for linking biodiversity patterns with ecosystem functioning. Combining taxonomic diversity, trophic traits and microbial metabolic pathways, develop integrative ecological framework capable of describing sediment condition and trophic state. Such integrated approaches can support the development of predictive frameworks that evaluate restoration trajectories in blue carbon ecosystems, and estimate the potential for carbon sequestration and long-term carbon burial in coastal sediments. Coupling biodiversity indicators with metabolic and biogeochemical information offers a robust pathway or improving the monitoring and management of estuarine ecosystems, enabling a more comprehensive evaluation of sediment ecological status and their role in long-term carbon storage. Mon, 06 Jul 2026 23:00:00 GMT http://hdl.handle.net/10174/42581 2026-07-06T23:00:00Z http://hdl.handle.net/10174/41486 Title: New Late Cretaceous and Central Atlantic Magmatic Province magmatic sources off West Iberia revealed by from high-resolution magnetic surveys on the continental shelf Authors: Terrinha, Pedro; Neres, Marta; Noiva, João; Brito, Pedro; Rosa, Marcos; Batista, Luis; Ribeiro, Carlos Abstract: This work investigates the existence and tectonic control of magmatic bodies in the continental shelf of the SW Iberia margin. Magnetic data were densely acquired for a total area of ~4400 km2 and carefully processed. Our new maps reveal a complex magnetic anomaly field, where distinct zones are defined based on the anomaly distribution. A wide number and variety of magmatic bodies are interpreted, from >10 km-scale deeply intruded plutons to small plug-like and dike-like intrusions. Interpretation of magnetic results together with bathymetry and seismic reflection data allows discussing the geometry, extension, and age of the magmatic sources and inferring the faults of fault systems related to their intrusion. The Cabo Raso complex is a densely intruded zone related to the Late Cretaceous alkaline event. The Sines complex comprises the known offshore prolongation of the on-land Sines magmatic rocks but also the newly mapped Côvo and Milfontes anomalies. Côvo is the largest magmatic intrusion recognized in West Iberia. Milfontes intrudes the non-rifted Paleozoic crust and is the first known evidence of a plutonic source of the Central Atlantic Magmatic Province (CAMP) in Iberia. The geographical distribution and geometry of the magmatic bodies are mostly controlled by the crustal tectonic fabric inherited from the Paleozoic Variscan orogeny, which was re-worked during the Mesozoic rifting and the Cenozoic Alpine collision. The magmatic bodies modify the rheological structure of the crust and may affect the strain localization during the Alpine collision and recent tectonics. This work allowed for mapping not only unknown plutons of Mesozoic age but also to define the eastern limit of the West Iberia Late Cretaceous Alkaline Province (WILCAP), which together with the Madeira-Tore Rise north of the Africa-Eurasia plate boundary cover an area equivalent to a Large Igneous Province (LIP). Fri, 31 Mar 2023 23:00:00 GMT http://hdl.handle.net/10174/41486 2023-03-31T23:00:00Z http://hdl.handle.net/10174/41420 Title: Post-rift tectono-sedimentary evolution of the deep West Iberian Margin. Authors: Simões, Maria; Roque, Cristina; Ribeiro, Carlos; Noiva, João; Terrinha, Pedro Abstract: The West Iberian Margin (WIM) is the conjugate margin of the Grand Banks of Canada and the rifting processes that originated both margins have been widely studied over the last decades. Therefore, WIM is well known as a classical example of a non-volcanic rifted margin with two main rifting phases related to the North Atlantic opening. Despite the studies carried out so far, the knowledge about the sedimentary and tectonic evolution of this margin during the post-rift stage is scarce. The main focus of this work is to characterize post-rift tectono-sedimentary sequence of the deep West Iberian Margin. The study area is bounded to the north by the Galicia Bank, to the south by the Narazé Canyon, to the west by the Iberian Abyssal Plain, and by the Iberian coast to the east, covering about 120 000 km2. The dataset includes five multichannel seismic reflection profiles acquired in the scope of the Portuguese Project of Extension of the Continental Shelf by EMEPC (Task Group for the Extension of the Continental Shelf) and the EMODnet (European Marine Observation and Data Network) bathymetry in the study area. The seismic survey was carried out onboard R/V Akademik Shatskiy using a source of 5720 cu in bolt gun array, cable length of 7950 m and shot interval of 50.00 m. Four of the multichannel seismic lines are oriented W-E, and one N-S, three of them with about 200 km length and two approximately 100 km length located, at about 5300 m water depth. Lithostratigraphic information from the Ocean Drilling Program (ODP) drills was used for the characterization of seismic units and the chronological constraint. The multibeam bathymetry used is from an EMODNet digital terrain model (DTM) with tiles of approximately 115m * 115m (1/16 * 1/16 arc minutes) of grid resolution, resulting from the combination of bathymetric survey datasets, DTMs, satellite derived bathymetry (SDB) data, and GEBCO 2020 (General Bathymetric Chart of the Oceans 2020) data to fill in the gaps (www.emodnet-bathymetry.eu). The seismic lines and the bathymetric data were loaded into Landmark software for sismostratigraphic interpretation. The geomorphological analysis was made using ArcMap and Geocap software, in order to identify and characterize the main seafloor reliefs. . The sismostratigraphic interpretation allowed the identification of a pos-rift sequence formed by six seismic units of different ages calibrated with ODP drilling sites. The oldest seismic unit is of Late Cretaceous age and the youngest of Quaternary age. The sedimentary sequence is cut by several normal faults and few reverse faults; sealed fluid scape structures are also present. The joint analysis of the seismic reflection profiles and multibeam bathymetric analysis allowed to recognize that the main sedimentary processes and their interaction responsible for the build-up of the post-rift sedimentary sequence are: i) depositional related to bottom-current circulation, which deposited contourite difts and sediment waves; ii) gravitational responsible for mass transport deposits (MTD) and turbidites; iii) erosive that incised moats and channels; and iv) tectonic processes responsible for structural highs that controlled locally the sedimentary processes. The present-day complexity of the seabed morphology reflects the interaction between the main tectonic episodes like Mesozoic rifting, Cenozoic compression and uplift, and the sedimentary processes. Tue, 30 Apr 2024 23:00:00 GMT http://hdl.handle.net/10174/41420 2024-04-30T23:00:00Z http://hdl.handle.net/10174/41020 Title: Fluid Dynamics of the São Jorge Channel, Azores Plateau First results of RV Meteor expedition M186 Authors: Schmidt, C; Zitoun, R.; et al. Abstract: Young oceanic plateaus are important for fluid exchange between the lithosphere and the ocean. Increased heat fluxes can lead to a large-scale upwelling of fluids that play a role in global elemental cycles. In addition, variations in fluid chemistries can potentially influence the biomass and species compositions of microbial and benthic communities in sediments exposed to subsurface fluid flow. Yet, the present understanding of these young oceanic plateaus in terms of their fluid dynamics and their biogeochemical local and global impacts is limited. The goal of RV Meteor Expedition M186 in December 2022 was to investigate how subsurface fluids on the young Azores Plateau, Central North Atlantic, vary with respect to their flow rates, chemical compositions, and the prevalent on microbial and benthic communities at and below the seafloor. First data from the São Jorge Channel (Azores Plateau) show that fluid dynamics here are diffuse rather than focused, and that fluid chemical compositions nonetheless show strong local variations, over a small spatial scale of 65 km2, that could be related to differences in fluid origins and fluid flow paths. However, the connection of fluid conduits, heat flow data and biogeochemical data as well as their relation to faults visible in seismic data are rather complex. Our first results thus indicate that diffuse fluid flow on young oceanic plateaus is highly heterogeneous despite occurring over large sediment-covered areas. Thus, the role of fluids at young oceanic plateaus as an important intermediate between the lithosphere and the ocean cannot be generalized over large spatial and possibly temporal scales. Fri, 31 Mar 2023 23:00:00 GMT http://hdl.handle.net/10174/41020 2023-03-31T23:00:00Z