Ecosystem services provided by estuaries: Phosphorus retention capacity attending to phosphorus speciation pools

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Last Updated September 12, 2018, 10:32 (Europe/Berlin)
Created July 18, 2018, 18:16 (Europe/Berlin)
Language Eng
Title in original language Serviços dos ecossistemas prestados pelos estuários : especiação e capacidade de retenção do fósforo
Original language Portuguese
Abstract Thesis: In salt marshes the nutritional factor is not only important for the inhabiting organisms, but has also, to a larger scale, an ecological importance. This can be exemplified with the plants capacity to retain the phosphorus (P), enabling them to uptake the P bioavailable fraction to comply their basic survival mechanisms. These plants rhizosediment is an important source of nutrients essential to guarantee the delivery of all the services provided by the environment (regulating, provisioning, cultural). The loss of salt marsh areas in Ria de Aveiro coastal lagoon was the main reason for the development of this thesis. The concern about the impact caused by the loss of the salt marshes associated services might become enhanced in the future in case the hydrological changes (natural or anthropogenic) get more pronounced. This thesis takes the commitment to draw attention to the issue and to investigate the mechanisms of this important nutrient cycle that is essential for sustaining life on our planet. For this study 3 species of halophytes, representative of the salt marsh were chosen, specifically: Bolbochenous maritimus, Spartina maritima and Juncus maritimus. The raised questions seek to understand the role of P in the processes occurring in the halophytes rhizosediment, in three different contexts: (i) the P content in the biomass of the most representative salt marshes in Ria de Aveiro (comparing Spartina maritima and Juncus maritimus marshes); (ii) the P availability in the presence of inorganic pollutants in Largo do Laranjo, which corresponds to an area historically contaminated by metals (Juncus maritimus and Bolbochenous maritimus rhizosediment) and (iii) the effect of surface salt water intrusion (the study is focused on the assessment of the loss of P near the roots of the halophytes that inhabit the outer zone of the Baixo Vouga Lagunar (BVL) dike, which is located near the confluence of Rio Vouga with the Ria de Aveiro). By analysing the rhizosediment and biomass of the most representative halophytes it was possible to see that, relatively to the P nutrient load, from North Channel (San Jacinto / Ovar) to the South Channel (Mira) of the Ria de Aveiro, the elevation of the marsh is more important than the species spatial distribution within the system. This information is vital to the assertiveness of future management measures and rehabilitation of areas of salt marsh in the Ria de Aveiro. Studies in the impacted areas (Largo do Laranjo and BVL) were centred on analysing the rhizosediment vertical profile of the medium-high marsh halophytes. These studies revealed that the rhizosediment of these halophytes have peculiar characteristics that define the dynamics of the phosphorus cycle in a very characteristic way For the same species, the rhizosediment of the halophytes present in the Laranjo Largo have equivalent content of bioavailable P compared to those closer to the point source of contamination. In an optimistic view, the results reveal that both marshes, Largo Laranjo and Cais do Bico, have comparable conditions for the perpetuation of the services generated by them, therefore they become even more valuable because of the guarantee for phytostabilization of contaminants (preventing contaminants to reach the water column and the food chain). The spatial analysis of the salt marsh in BVL in the area outside the dike revealed the loss of species diversity and increased of the mud-flat area, and consequently the loss of P concentrations associated with rhizosediment. The coastal squeeze effect is more pronounced in the halophytes with higher exposure to the effects of the natural and anthropogenic drivers to which Ria is subject. In general, the degradation of the salt marsh area due to the phenomena of siltation or erosion can not be separated from sedimentary processes in the surrounding area, especially in the case of the Ria de Aveiro which has undergone constant change to meet the human activities needs. This trend is unlikely to change in the near future. Consequently, the evolution of the lagoon will be mainly dependent on the direct result of human actions that should always find ways to offset the damage caused within the lagoon system towards rehabilitation interventions. The recreation of salt marsh areas can take place as a mitigation measure in the context of interventions for the rehabilitation of degraded areas and may also serve as a form to capture P to be use in natural fertilizers programs (a desirable component in modern agriculture which is particularly important in regions heavily dependent on the external market). Thus, it is recommended that the recovery of salt marsh areas is encompassed within broader interventions of recovery of estuarine and lagoon systems.
Resource type
Spatial representation type
License Creative Commons Attribution-NonCommercial (CC BY-NC 4.0)
Classification Environment
Publication date 2024-01-23
INSPIRE theme Hydrography
Free keywords CS5, Aveiro, Natura 2000, Ria de Aveiro, Baixo Vouga Lagunar, Vouga Basin, Portugal, lagoon, thesis
Vocabulary date type
Responsible party Organisation: Universidade de Aveiro
Role: Author
Spatial extent - North 40.87
Spatial extent - South 40.48
Spatial extent - East -8.45
Spatial extent - West -8.86

Dataset extent

Political boundaries: GAUL 2015, © FAO Statistics Division.