Leandro Vaz

Vaz, L.; Sêrodio, J., Mateus, M., Dias, J.M., and Vaz, N., 2016. Primary production of the benthic microalgae in the bottom sediments of Ria de Aveiro Lagoon. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 178–182. Coconut Creek (Florida), ISSN 0749-0208. The Ria de Aveiro is a mesotidal coastal lagoon located in the north coast of Portugal. It has a complex irregular geometry characterized by large intertidal areas and several freshwater tributaries, which are the main sources of nutrients into the lagoon. The dynamics between the tidal propagation and the landward nutrient sources modulates the primary production within the lagoon. Here, primary production may have two main contributors: the chlorophyll in the water column and the benthic microalgae in the bottom sediments. In this work, a new methodology to compute microalgae in the bottom sediments is presented, consisting in coupling a numerical module of the benthic layer to a biophysical model. To perform the study, three schematic scenarios were implemented: Scenario 1 is the reference case, where typical nutrient load values were considered; Scenario 2 doubles the nutrient load concentrations at ocean and river boundaries; Scenario 3 reduces to half the nutrient values. The results show that an increase in nutrient load (Scenario 2) causes a reduction of benthic biomass, while a decrease causes an increase of benthic biomass, impacting the lagoon's primary production. In general, an increment of nutrient concentration in the water column favors the phytoplankton growth, which increases biomass. This will lead to an attenuation of the light intensity reaching the bottom sediments, resulting in a decrease of benthic primary production. The opposite pattern is observed for Scenario 3 in response to nutrient concentration.

Den Boer, S., Azevedo, A., Vaz, L., Costa, R., Fortunato, A.B., Oliveira, A., Tomás, L.M., Dias, J.M., Rodrigues, M., 2014. Development of an oil spill hazard scenarios database for risk assessment. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 539–544, ISSN 0749-0208. The occurrence of oil spills in coastal regions may have catastrophic consequences on the environment and severe socio-economic impacts. This work presents a new methodology to evaluate the risk associated with oil spills in coastal zones and estuaries, and illustrates its application in a coastal lagoon (Ria de Aveiro, Portugal). A ranked list of the hydrodynamic scenarios under which oil spills are most likely generated through the analysis of 33 years of wave and wind data, retrieved from the ERA-INTERIM project database, and from the analysis of oil spills that occurred in the Atlantic Iberian shelf. Cons...

Vaz, L., Plecha, S., Dias, J.M., 2013. Coastal wave regime influence on Ria de Aveiro inlet dynamics. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.), Proceedings 12th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 1605–1610, ISSN 0749-0208.--> The adjacent coastal zone of Ria de Aveiro lagoon is exposed to a highly energetic wave climate, with a yearly mean significant wave height of 2–2.5 m and wave periods of 9–11 s, corresponding to WNW to NNW swell. Consequently, it should be expected that the lagoon inlet hydrodynamic be dependent on the coupled forcing of tidal wave and wave regime. Thus, the main goal of this study is to assess the influence of the coastal wave regime at the inlet channel dynamics. The modeling system MORSYS2D, comprising the hydrodynamic model ELCIRC coupled with the wave model SWAN, is used to perform this study. The methodology developed consists in forcing the numerical models with loc...

Valentim, J.M., Vaz, L., Vaz, N., Silva, H., Duarte, B., Caçador, I. and Dias, J.M., 2013. Sea level rise impact in residual circulation in Tagus estuary and Ria de Aveiro lagoon. Nowadays, there is a special concern about the possible impact of sea level rise in hydrodynamic patterns of coastal systems and its consequence in contingent ecosystems. In the present work, the effects of sea level rise in residual circulation are analyzed in two of the most important Portuguese coastal systems, Ria de Aveiro lagoon and Tagus estuary. The role of rivers inflow on residual circulation is also analyzed under different sea level scenarios. Several projections of river discharges were considered and two scenarios for sea level were adopted: actual and locally predicted sea level rise. The methodology followed comprises the exploitation of previously validated 2D hydrodynamic numerical models (MOHID) developed for both systems. Results indicate that rivers discharge effect cannot be unconsidered in the lon...