Coastal vegetated ecosystems are major organic carbon (OC) and total nitrogen (TN) sinks, but the mechanisms that regulate their spatial variability need to be better understood. Here we assessed how superficial sedimentary OC and TN within intertidal vegetated assemblages (saltmarsh and seagrass) vary along a flow gradient, which is a major driver of sediment grain size, and thus of organic matter (OM) content. A significant relationship between flow current velocity and OC and TN stocks in the seagrass was found, but not in the saltmarsh. OC and TN stocks of the saltmarsh were larger than the seagrass, even though that habitat experiences shorter hydroperiods. Mixing models revealed that OM sources also varied along the flow gradient within the seagrass, but not in the saltmarsh, showing increasing contributions of microphytobenthos (17–32%) and decreasing contributions of POM (45–35%). As well, OM sources varied vertically as microphytobenthos contribution was highest at the higher intertidal saltmarsh (48%), but not POM (39%). Macroalgae, seagrass and saltmarsh showed low contributions. Local trade-offs between flow current velocities, hydroperiod and structural complexity of vegetation must be considered, at both horizontal and vertical (elevation) spatial dimensions, for better estimates of blue carbon and nitrogen in coastal ecosystems.

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The 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.

Coastal vegetated ecosystems such as saltmarshes and seagrasses are important sinks of organic carbon (OC) and total nitrogen (TN), with large global and local variability, driven by the confluence of many physical and ecological factors. Here we show that sedimentary OC and TN stocks of intertidal saltmarsh (Sporobolus maritimus) and seagrass (Zostera noltei) habitats increased between two-and fourfold along a decreasing flow velocity gradient in Ria Formosa lagoon (south Portugal). A similar twofold increase was also observed for OC and TN burial rates of S. maritimus and of almost one order of magnitude for Z. noltei. Stable isotope mixing models identify allochthonous particulate organic matter as the main source to the sedimentary pools in both habitats (39-68%). This is the second estimate of OC stocks and the first of OC burial rates in Z. noltei, a small, fast-growing species that is widely distributed in Europe (41,000 ha) and which area is presently expanding (8600 ha in 2000s). Its wide range of OC stocks (29-99 Mg ha -1 ) and burial rates (15-122 g m 2 y -1 ) observed in Ria Formosa highlight the importance of investigating the drivers of such variability to develop global blue carbon models. The TN stocks (7-11 Mg ha -1 ) and burial rates (2-4 g m -2 y -1 ) of Z. noltei were generally higher than seagrasses elsewhere. The OC and TN stocks (29-101 and 3-11 Mg ha -1 , respectively) and burial rates (19-39 and 3-5 g m -2 y -1 ) in S. maritimus saltmarshes are generally lower than those located in estuaries subjected to larger accumulation of terrestrial organic matter.

Water quality is critical for fish health in aquaculture production. In flow-through systems, the inflowing water normally requires quality controls and treatments for being supplied from coastal water bodies that can be polluted by nutrients, suspended solids, and microorganisms. Here we assess how seagrass meadows benefit aquaculture systems through the provision of ecosystem services (water filtration, biological control, and regulation of dissolved gasses) in the water reservoir that supplies earthen ponds in an aquaculture system in southern Portugal. In the 1.45-ha reservoir, seagrasses retained daily an estimate of 0.8-1.8 kg d-1 of nitrogen, 0.04-0.07 kg d-1 of phosphorus in their biomass, and 0.7-1.1 kg dw d-1 of suspended total particulate matter, bringing benefits in terms of nutrient and particle removal from the water column. Diel and spatial variation in faecal coliforms levels (Escherichia coli) in the reservoir suggested that seagrasses, in combination with light exposure, may reduce the levels of this pathogen. Furthermore, the seagrassdominated system oxygenated the water through photosynthesis at a faster rate than the respiratory oxygen consumption, maintaining the system above the aquaculture minimum oxygen. This study demonstrates that seagrasses can be used as a nature-based solution to overcome water quality challenges in flow-through aquaculture ponds.

With this work we develop a methodology able to ensure the economic evaluation of soil tillage technologies, in a risky environment, and to capture the influence of farmer behaviour on his technological choice.The model has short term activities, that change with the type of year and long term activities, in which the sets of traction investment activities are included. Although these activities do not change with the type of year, they lead to different availability of resources each type of year, since the same tractor has different available days to work in the field in different weather conditions.We prove that the model is sensible to the grater income variability resulting from the use of alternative technologies and to the balance between income and risk, accounting to the probability of occurrence of each state of nature and giving an investment solution that considers each year the best production plan.

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