Effects of external nutrient sources and extreme weather events on the nutrient budget of a Southern European coastal lagoon

The seasonal and annual nitrogen (N), phosphorus (P), and carbon (C) budgets of the mesotidal Ria Formosa lagoon, southern Portugal, were estimated to reveal the main inputs and outputs, the seasonal patterns, and how they may influence the ecological functioning of the system. The effects of extreme weather events such as long-lasting strong winds causing upwelling and strong rainfall were assessed. External nutrient inputs were quantified; ocean exchange was assessed in 24-h sampling campaigns, and final calculations were made using a hydrodynamic model of the lagoon. Rain and stream inputs were the main freshwater sources to the lagoon. However, wastewater treatment plant and groundwater discharges dominated nutrient input, together accounting for 98, 96, and 88 % of total C, N, and P input, respectively. Organic matter and nutrients were continuously exported to the ocean. This pattern was reversed following extreme events, such as strong winds in early summer that caused upwelling and after a period of heavy rainfall in late autumn. A principal component analysis (PCA) revealed that ammonium and organic N and C exchange were positively associated with temperature as opposed to pH and nitrate. These variables reflected mostly the benthic lagoon metabolism, whereas particulate P exchange was correlated to Chl a, indicating that this was more related to phytoplankton dynamics. The increase of stochastic events, as expected in climate change scenarios, may have strong effects on the ecological functioning of coastal lagoons, altering the C and nutrient budgets.Portuguese Science and Technology Foundation (FCT) [POCI/MAR/58427/2004, PPCDT/MAR/58427/2004]; Portuguese Science and Technology Foundation (FCT

The role of EMODnet Chemistry in the European challenge for Good Environmental Status

The European Union set the ambitious objective to reach within 2020 the goal of Good Environmental Status. The European Commission (2008) represents the legislative framework that drives member state efforts to reach it. The Integrated Maritime Policy supported the need to provide a European knowledge base able to drive sustainable development by launching in 2009 a new European Marine Observation and Data Network (EMODnet). Through a stepwise approach, EMODnet Chemistry aims to provide high-quality marine environmental data and related products at the scale of regions and sub-regions defined by the Marine Strategy Framework Directive. The chemistry lot takes advantage and further develops the SeaDataNet pan-European infrastructure and the distributed approach, linking together a network of more than 100 National Oceanographic Data Centres providing data from more than 500 data originators. The close interaction with EEA, RSCs, ICES and EMODnet–MSFD coordination group facilitated the identification of the most appropriate set of information required for the MSFD process. EMODnet Chemistry provides aggregated and validated regional data collections for nutrients, dissolved gasses, chlorophyll, and contaminants, properly visualized with OGC WMS and WPS viewing services. Concentration maps with 10-year moving window from 1960 to 2014, by season and for selected vertical layers, are computed and made available

Nutrient depletions in the Ross Sea and their relation with pigment stocks

The present article depicts a first attempt to relate the governing nutrient uptake regime and phytopigment signature of the Ross Sea. Based on nutrient and phytopigment data obtained during two cruises in the Ross Sea, two distinct groups were recognised. The first one was characterised by moderate nutrient nitrate and silicic acid depletions in combination with relatively high diatom and Phaeocystis abundance. The second group showed very low nutrient depletions and very poor diatom abundance. Average depth specific nitrate depletions were 8.1 and 1.1 μM and average silicic acid depletions were 21.5 and 1.3 μM, respectively. The nutrient consumption patterns did not match the conditions of silicic acid excess (SEA) or nitrate excess areas (NEA), a clear trend being probably obscured by very poor seasonal maturity of several sampling stations. The contrast between both groups is largely explained by small differences in nitrogen uptake regime of the major phytoplankters. During early season, the diatoms meet the majority of their nitrogen requirements by nitrate uptake, with few exceptions where ammonium is the most important nitrogenous substrate. On average, their nitrate uptake capacity is lower than that of Phaeocystis (average specific nitrate uptake rates were 0.021 and 0.036 day y-1 for diatoms and Phaeocystis, respectively). The latter phytoplankton always shows predominance of nitrate uptake. Both groups are subject to inhibition of nitrate uptake when ammonium availability increases, and it is likely that the diatoms are more sensitive to the inhibitory effect of ammonium

Human impact and the historical transformation of saltmarshes in the Marano and Grado Lagoon, northern Adriatic Sea

Historical transformations of the saltmarshes in the six sub-basins of the Marano and Grado Lagoon (northern Adriatic Sea) were analyzed using aerial photographs (1954, 1990, 2006) and the support of historical maps and topographic surveys in case studies. Analysis of the 2006 set of aerial photographs enabled the definition of the present extent and distribution of the saltmarshes inside the lagoon (760 ha), with a total reduction in saltmarsh area of 16% (144 ha) compared to 1954. Direct human actions played a significant role in the budget, resulting in a negative balance between saltmarsh gains and losses; the total loss due to land reclamation and dredging during this period amounted to 126 ha. After excluding the total loss due to direct human interventions, different erosional and depositional marsh types were recognized and associated with different forcing factors, based on morphological and geographical evidence. Over the 52-year period marshes were lost due to: a) drowning \u2013 the combined effects of eustatism, regional subsidence and autocompaction (102 ha); b) edge-retreat by wind wave attack (34 ha); c) erosion by vessel-generated waves (37 ha); and d) coastal dynamics and inlet migration (5.7 ha). Conversely, marshes gained in area due to: a) fluvial input (63 ha); b) tidal input (27 ha); c) paralagoonal deposition (45 ha); d) the re-opening of abandoned fish farms (18 ha); and e) the dumping of dredged material (8 ha). The relative importance of erosional versus depositional forcing factors, as well as the different rates of marsh gain and loss recorded in each lagoon basin, demonstrate that local and short-term forcing factors can obliterate or compensate the long-term ones, especially the relative sea-level rise. A test of the integrated sediment budget carried out on one third of the total lagoon (Lignano and S. Andrea basins) through a bathymetric comparison between datasets from 1964 and 2009, provided a better understanding of the relationship between the evolution of the saltmarshes and the submerged part of the lagoon. Conservation or slight expansion of the marshes inside these basins were found to be linked to an overall positive sediment budget of 61,000 m3/y. Nevertheless, significant morphological changes occurred in the submerged basin, which is affected by sustained deposition along the inner margins due to sediment supplies, by an overall erosion of tidal and subtidal flats far from the tributaries, and by an important infilling of the channels. The analyzed data, along with information available for the Venice Lagoon, highlights how the fate of open-water lagoons is to flatten whilst submerging because of the strong influence of wind waves, which tend to transform the lagoon into a marine embayment. This transgressive condition reduces, if not negates, the compensative effect of the sedimentation rate on wind-wave-induced shear stress excess, since supplies seem to contribute primarily to the morphological accommodation