Search

The Marano-Grado Lagoon (MGL) is extensively contaminated by mercury (Hg) from local sources and long-term (500 years) tidally delivered inputs from the Idrija Hg mine (Slovenia) through Isonzo River suspended loads. A multibox WASP-7 (Water Analysis Simulation Program) model was used to simulate the long-term dynamics of the mercury cycle in the MGL. Scenario simulations were used to compute changes in the system over 100 years. Present and future Hg concentrations in water, sediment, and Hg budgets were compared, including evasion and MeHg inputs to the Mediterranean Sea, based on climate changes and mercury capping in tributary rivers. Using the Ref baseline scenario, the model computes a general decrease in Hg T of 13% in the water column and of 80% in sediment and a strong MeHg increase in sediment (+73%). The net sea export of Hg T decreases by 57% to up to 48 kg/y while MeHg increases by 10% to up to 0.63 kg/y. The lagoon sediment recovery time of Hg T up to a target level of 0.3 mg/kg is computed over 570 years for surface sediments (1750 for subsurface sediments). When removing Hg from boundaries, the same target value for surface sediments is reached within 110 years. [ABSTRACT FROM AUTHOR]

The majority of Scotland's saline lagoons are located on the low-lying coastlines of the Western Isles and the northern archipelagos of Orkney and Shetland, where recorded annual relative sea level rise rates are among the highest in Scotland. The sediment-impounded lagoons of Orkney and Shetland will either lose their impoundment and become incorporated in marine coastal waters, or become increasingly saline, as relative sea levels rise. The rock-basin lagoons of the Western Isles will retain their restricted exchange with the sea but will also become more saline with rising sea level. Specialist lagoonal organisms tend to have wide salinity tolerances but may succumb to competition from marine counterparts. In all areas, there are sufficient fresh-water inland water bodies with potential to be captured as lagoons to compensate for loss of extent and number, but the specialist lagoon biota tend to have limited dispersal powers. It is thus possible that they will be unable to transfer to their analogue sites before existing lagoons become fully marine, giving conservation managers the problem of deciding on management options: leave natural processes to operate without interference, manage the saline inflow to maintain the current salinity regime, or translocate lagoon organisms perceived as threatened by rising salinities. Timing of conversion and capture is unpredictable due to local topography and complications caused by variable stratification. [ABSTRACT FROM AUTHOR]

Abstract: The relative importance of estuarine nursery areas for species of the genus Diplodus and their relations with several environmental variables was evaluated along the Portuguese coast. Nine estuarine systems were sampled with beam trawl surveys. Species of the genus Diplodus were only present in estuaries south of the Ria de Aveiro (40°38′). A latitudinal gradient of increasing species richness and abundance towards the south was found. Estuarine nurseries of Diplodus vulgaris, Diplodus sargus and Diplodus puntazzo were characterized by mud substrate, lower salinity and lower dissolved oxygen, with the exception of Ria Formosa. Diplodus bellottii was associated with estuaries with large areas and high volumes, the Tejo and the Sado. Diplodus bellottii nursery grounds were characterized by low depth. Diplodus annularis was associated with seagrass and saltmarsh habitats, certainly because it is the only species of the genus Diplodus which recruits exclusively to seagrass meadows. Diplodus annularis nursery grounds were also characterized by sand substrate, higher salinity and higher dissolved oxygen. Niche breath varied widely amongst species and location. Diplodus vulgaris generally presented the highest values of niche breath, except when D. bellottii was present. Niche overlap was not high, the highest value being that between D. vulgaris and D. sargus in the Mira estuary, with 76% spatial niche overlap. Considerations were made on these species progress towards the north in a climate warming context, taking into account the habitat associations described here. [Copyright &y& Elsevier]