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- Relatório Científico I: Avaliação dos ecossistemas de carbono azul em Portugal continental.Publication . Santos, Rui; Ito, Paula; de los Santos, Carmen B.Por ocasião da Conferência do Oceano das Nações Unidas, que decorreu em Lisboa em junho de 2022, a Fundação Calouste Gulbenkian lançou o projeto Gulbenkian Carbono Azul, em parceria com o Centro de Ciências do Mar (CCMAR) da Universidade do Algarve e a Associação Natureza Portugal em associação com a WWF – World Wide Fund for Nature (ANP|WWF), com o objetivo de investigar as informações disponíveis para mapear os ecossistemas marinhos e costeiros em Portugal continental que têm o potencial de sequestrar dióxido de carbono da atmosfera – os ecossistemas de carbono azul. Esta investigação científica, feita de norte a sul do país, caracteriza os ecossistemas (localização, áreas de distribuição, estado ambiental, reservas e taxas de sequestro de carbono, entre outras características) e propõe medidas adequadas de proteção e restauro.
- Monitoring bubble production in a seagrass meadow using a source of opportunityPublication . Felisberto, Paulo; Rodríguez, Orlando; Silva, João P.; Jesus, Sergio; Ferreira, Hugo Q.; Ferreira, Pedro P.; Cunha, Maria E.; de los Santos, Carmen B.; Olivé, Irene; Santos, RuiUnder high irradiance, the photosynthetic activity of dense seagrass meadows saturates the water forming oxygen bubbles. The diel cycle of bubble production peaks at mid-day, following light intensity pattern. It is well known that bubbles strongly affect the acoustic propagation, increasing signal attenuation and decreasing the effective water sound speed, noticeable at low frequencies. Thus, the diurnal variability of bubbles may show an interference pattern in the spectrograms of low frequency acoustic signals. In an experiment conducted in July 2016 at the Aquaculture Research Station of the Portuguese Institute for the Sea and Atmosphere in Olhão, Portugal, the spectrograms of low frequency (<20kHz) broadband noise produced by water pumps in a pond of 0.48ha covered by the seagrass Cymodocea nodosa showed interference patterns that can be ascribed to the variability of the sound speed in the water. Preliminary analysis suggests that the daily cycle of bubble concentration can be inferred from these interference patterns.
- Species-specific plastic accumulation in the sediment and canopy of coastal vegetated habitatsPublication . R Nicastro, Katy; Zardi, Gerardo I.; de los Santos, Carmen B.Plastic waste has become ubiquitous in ecosystems worldwide. Few, recent studies report evidence of coastal vegetated habitats acting as sink for plastics, yet assessments have been completed either for macro or microplastics and focussing on just one type of vegetated habitat. Here, we investigated the role of marine coastal vegetated habitats as sinks for macro (≥5 mm) and microplastics (<5 mm) through a comprehensive, multi-habitat approach. We assessed the occurrence, abundance and physical properties of macro and microplastics in the canopy and superficial sediment of two intertidal (seagrass Zostera noltei, saltmarsh Sporobolus maritimus) and two subtidal (mixed seagrass meadows of Cymodocea nodosa and Zostera marina, rhizophytic macroalga Caulerpa prolifera) habitats in the Ria Formosa lagoon (Portugal). Our results showed that coastal vegetated habitats trapped macro and microplastics in the sediment at variable degrees (1.3-17.3 macroplastics 100 m-2, and 18.2-35.2 microplastics kg-1). Macroplastics accumulated in all vegetated habitat but not in nearby unvegetated areas, yet only S. maritimus habitat presented a significant trapping effect. Microplastics occurred in the sediment of all vegetated and unvegetated areas with similar abundances and high variability. Microplastics, all of type fibre, were recorded on all canopies except for S. maritimus. Overall, the trapping capacity of microplastics in the sediment and on the canopy was higher for subtidal than for intertidal vegetated habitats. We conclude that generalizations in the trapping effect of coastal vegetated areas should be done with caution, since it may be highly variable and may depend on the plastic size, habitat and tidal position. Since these habitats support a high biodiversity, they should be included in assessments of plastic debris accumulation and impacts in coastal areas. Further research, including experimental studies, is needed to shed more light on the role of coastal vegetated habitats as plastic sinks.
- Biomechanical response of two fast-growing tropical seagrass species subjected to in situ shading and sediment fertilizationPublication . La Nafie, Yayu A.; de los Santos, Carmen B.; Brun, Fernando G.; Mashoreng, Supriadi; van Katwijk, Marieke M.; Bouma, Tjeerd J.Although seagrasses experience strong hydrodynamic forces, little is known about their biomechanical response in spite of the potential importance for their ecological success. We investigated how light reduction and sediment-nutrient enrichment affect biomechanical and morphological properties of two short-lived tropical seagrass species: Halophila ovalis and Halodule uninervis. A 50-day manipulative field experiment of shading and sediment-nutrient enrichment versus a natural population (control) showed that both shading and nutrient enrichment made the leaves of Halophila ovalis weaker (lower FTS) and more elastic (lower ET). As the absolute breakability of leaves (FMAX) was not affected by either of the treatments, this implies that these changes in strength and stiffness resulted from the increase in leaf dimensions under nutrient enrichment (i.e., longer, wider and thicker leaves) and shading conditions (i.e., thicker leaves). In contrast, the biomechanical properties of H. uninervis leaves were less responsive and only became more extensible under shading while their biomechanics did not change under sediment nutrient enrichment. This limited response of H. uninervis might be due to the lack of morphological response in this species since leaves only became longer under nutrient enrichment. When comparing both species across treatments under shading (after normalizing them with their controls), H. ovalis became significantly weaker compared to H. uninervis, and the latter became more extensible. Under nutrient enrichment, H. ovalis became significantly more elastic compared H. uninervis. Overall we found that (i) biomechanical properties can be affected by environmental conditions, (ii) the responses were species specific, and (iii) seagrass morphology (leaf thickness and width) affected by environmental conditions will influence seagrass biomechanical properties. Further experimental studies on seagrass biomechanics are needed as present understandings of the acclimation of these properties and the consequences for species functioning are only starting to emerge.
- New aspect in seagrass acclimation: leaf mechanical properties vary spatially and seasonally in the temperate species Cymodocea nodosa Ucria (Ascherson)Publication . de los Santos, Carmen B.; Brun, Fernando G.; Vergara, Juan J.; Pérez-Lloréns, J. LucasSeagrasses may acclimate to environmental heterogeneity through phenotypic plasticity. In contrast to leaf morphology, which has been a central point in seagrass acclimation studies, plasticity in leaf biomechanics and fibre content is poorly understood, despite being crucial in plant ecological performance, especially regarding physical forces. We hypothesised that mechanical traits (e.g. breaking force, strength, toughness, and stiffness) and fibre content of seagrass leaves vary as morphology does under differential environments. Cymodocea nodosa was seasonally monitored at three locations around Ca´diz Bay (southern Spain) with hydrodynamic regime as the most noticeable difference between them. Leaves showed plasticity in both morphology and mechanical traits, with wave-exposed individuals presenting short but extensible and tough leaves. Leaf fibre content was invariant along the year and with little spatial variability. Cross-sectional area rather than material properties or fibre content differentiates leaf mechanical resistance. Seagrass capacity to thrive under a range of mechanical forces may be dictated by their plasticity in morpho-biomechanical traits, a key element for the hydrodynamical performance and, hence, for species colonisation and distribution.
- Acclimation of seagrass Zostera noltii to co-occurring hydrodynamic and light stressesPublication . de los Santos, Carmen B.; Brun, Fernando G.; Bouma, Tjeerd J.; Vergara, Juan J.; Pérez-Lloréns, J. LucasSeagrasses may frequently experience a combination of velocity and light stresses, as elevated hydrodynamics often enhances turbidity and the subsequent light reduction. The objective of this study was to investigate the effects that these stressors induce on morphometric and dynamic seagrass features depending on the initial biomass partitioning. For this purpose, a factorial mesocosm experiment was conducted on plants of Zostera noltii subjected to combinations of 2 contrasting light levels (2.5 ± 0.6 and 15.6 ± 2.5 mol photons m–2 d–1) and 3 unidirectional flow velocities (0.35, 0.10 and 0.01 m s–1). No interactive effects between the 2 variables were recorded, except on plant survival and leaf length, and generally, light effects prevailed over hydrodynamic ones. Plants responded to light reduction regardless of the flow velocity treatments, showing low survival rates (which improved at high velocity), high aboveground/belowground biomass ratios (AG/BG) and a poorly developed root-rhizome system compared to plants under saturating light conditions. Plant morphometry only responded to hydrodynamic stress under saturating light: at high current velocity, plants preferentially allocated biomass into BG structures, bearing short leaves and displaying high internode and root appearance rates. Overall, light reduction promoted similar responses in plants with different AG/BG biomass ratios, but dissimilarities were recorded for current velocity. Thus, it can be concluded that, under simultaneous light and hydrodynamic stresses, light effects prevailed over hydrodynamic ones in Z. noltii, while acclimation to hydrodynamics only occurred under saturating light
- Ocean literacy to mainstream ecosystem services concept in formal and informal education: the example of coastal ecosystems of Southern PortugalPublication . Barracosa, Helena; de los Santos, Carmen B.; Martins, Márcio; Freitas, Cátia; Santos, RuiThe concept of ecosystem services (ES) emerges as strategic to explain the influences that the ocean, and in particular coastal ecosystems, have on us and how we influence them back. Despite being a term coined several decades ago and being already widespread in the scientific community and among policy-makers, the ES concept still lacks recognition among citizens and educators. There is therefore a need to mainstream this concept in formal education and through Ocean Literacy resources. Although important developments in OL were done in the United States, particularly through the National Marine Educators Association (NMEA), this concept was only recently introduced in Europe. In Portugal, several informal OL education programs were developed in the last years, yet formal education on OL and, in particular, on ES is still very deficient. To address this limitation, the "Environmental Education Network for Ecosystem Services" (REASE), founded in 2017 in the Algarve region by a consortium of educational, environmental and scientific institutions, aims to increase OL through the dissemination of the perspective of how ES provided by coastal vegetation may contribute to the human well-being. The projects and activities implemented by REASE focus mostly on formal-education of school children and include: (1) capacity building for K-12 teachers, (2) educational programs to support and develop ES projects in schools, including a citizen science project to evaluate blue carbon stocks in the Algarve, (3) the publication of a children's book about the ES provided by the local Ria Formosa coastal lagoon, with a community-based participatory design (illustrations made by schoolchildren) and (4) a diverse array of informal education activities to raise awareness on the importance of coastal ecosystems on human well-being. REASE challenges are being successfully addressed by identifying threats to local coastal ecosystems that people worry about, and highlighting solutions to improve and maintain their health.
- Hypocholesterolaemic pharmaceutical simvastatin disrupts reproduction and population growth of the amphipod Gammarus locusta at the ng/L rangePublication . Neuparth, Teresa; Martins, Carla; de los Santos, Carmen B.; Costa, Maria H.; Martins, Irene; Costa, Pedro M.; Santos, Miguel M.Simvastatin (SIM), a hypocholesterolaemic drug, is among the most widely used pharmaceuticals worldwide and is therefore of emerging environmental concern. Despite the ubiquitous nature of SIM in the aquatic ecosystems, significant uncertainties exist about sublethal effects of the drug in aquatic organisms. Therefore, here we aimed at investigating a multi-level biological response in the model amphipod Gammarus locusta, following chronic exposures to low levels of SIM (64 ng/L to 8 mg/L). The work integrated a battery of key endpoints at individual-level (survival, growth and reproduction) with histopathological biomarkers in hepatopancreas and gonads. Additionally, an individual-based population modelling was used to project the ecological costs associated with long-term exposure to SIM at the population level. SIM severely impacted growth, reproduction and gonad maturation of G. locusta, concomitantly to changes at the histological level. Among all analysed endpoints, reproduction was particularly sensitive to SIM with significant impact at 320 ng/L. These findings have important implications for environmental risk assessment and disclose new concerns about the effects of SIM in aquatic ecosystems.
- Seagrass ecosystem services: assessment and scale of benefitsPublication . de los Santos, Carmen B.; Scott, Abbi; Arias-Ortiz, Ariane; Jones, Benjamin; Kennedy, Hilary; Mazarrasa, Inés; McKenzie, Len; Nordlund, Lina Mtwana; de la Torre-Castro, Maricela de la T; Unsworth, Richard K.F.; Ambo-Rappe, Rohani; Potouroglou, M; Grimsditch, G; Weatherdon, L; Lutz, SSeagrass ecosystems provide a wide variety of services that support human well-being around the world (Barbier et al. 2011). It is estimated that more than 1 billion people live within 100 km of a coast with seagrass meadows, thus potentially benefiting from their provisioning, regulating and cultural services. Seagrasses play a significant global role in supporting food security, mitigating climate change, enriching biodiversity, purifying water, protecting the coastline and controlling diseases (Figure 2). The integrity and provision of services by seagrass meadows are enhanced by their proximity and connectivity to other coastal ecosystems such as tidal marshes, coral reefs, mangrove and kelp forests, and oyster and mussel beds. The maintenance and regulation of these services is therefore essential to support human well-being and promote development in the future.
- Sedimentary organic carbon and nitrogen sequestration across a vertical gradient on a temperate wetland seascape Including salt marshes, seagrass meadows and rhizophytic macroalgae bedsPublication . Barrena de los Santos, Carmen; Egea, Luis G.; Martins, Márcio; Santos, Rui; Masqué, Pere; Peralta, Gloria; Brun, Fernando G.; Jiménez-Ramos, RocíoCoastal wetlands are key in regulating coastal carbon and nitrogen dynamics and contribute significantly to climate change mitigation and anthropogenic nutrient reduction. We investigated organic carbon (OC) and total nitrogen (TN) stocks and burial rates at four adjacent vegetated coastal habitats across the seascape elevation gradient of Cádiz Bay (South Spain), including one species of salt marsh, two of seagrasses, and a macroalgae. OC and TN stocks in the upper 1 m sediment layer were higher at the subtidal seagrass Cymodocea nodosa (72.3 Mg OC ha−1, 8.6 Mg TN ha−1) followed by the upper intertidal salt marsh Sporobolus maritimus (66.5 Mg OC ha−1, 5.9 Mg TN ha−1), the subtidal rhizophytic macroalgae Caulerpa prolifera (62.2 Mg OC ha−1, 7.2 Mg TN ha−1), and the lower intertidal seagrass Zostera noltei (52.8 Mg OC ha−1, 5.2 Mg TN ha−1). The sedimentation rates increased from lower to higher elevation, from the intertidal salt marsh (0.24 g cm−2 y−1) to the subtidal macroalgae (0.12 g cm−2 y−1). The organic carbon burial rate was highest at the intertidal salt marsh (91 ± 31 g OC m−2 y−1), followed by the intertidal seagrass, (44 ± 15 g OC m−2 y−1), the subtidal seagrass (39 ± 6 g OC m−2 y−1), and the subtidal macroalgae (28 ± 4 g OC m−2 y−1). Total nitrogen burial rates were similar among the three lower vegetation types, ranging from 5 ± 2 to 3 ± 1 g TN m−2 y−1, and peaked at S. maritimus salt marsh with 7 ± 1 g TN m−2 y−1. The contribution of allochthonous sources to the sedimentary organic matter decreased with elevation, from 72% in C. prolifera to 33% at S. maritimus. Our results highlight the need of using habitat-specific OC and TN stocks and burial rates to improve our ability to predict OC and TN sequestration capacity of vegetated coastal habitats at the seascape level. We also demonstrated that the stocks and burial rates in C. prolifera habitats were within the range of well-accepted blue carbon ecosystems such as seagrass meadows and salt marshes.