Brackish Coastal Lagoon Research Articles

Phototrophic sulfur bacteria and sulfate-reducing bacteria causing red waters in a shallow brackish coastal lagoon (Prévost Lagoon, France)

In the shallow lagoon of Prevost (43°30′N, 3°54′E; French Mediterranean coast), red waters occurring periodically during warm summers are a consequence of a succession of ecological events beginning in the early spring with a bloom of algae ( Ulva lactuca ). In summer 1977, a red water was analyzed; in the early summer, the water turned anoxic and became rich in sulfide which originated from sulfate reduction in the first 10 cm of the sediment. Numbers of both phototrophic and sulfate-reducing bacteria (SRB) increased during spring and summer, and the genera in the prevailing populations did not change: Thiocapsa (80%) among the phototrophic bacteria and Desulfovibrio and Desulfobacter among the SRB. They were also dominant during the period of red waters. A few Chromatium and Thiocystis species were also identified. During red water periods, these bacteria grew very actively, removing all the sulfide produced by SRB, and accumulated in the whole water column. Consequently, the sulfate level increased to 5 mmol·1−1 higher than the theoretical sulfate level calculated from salinity, showing the active oxidation of sulfide by phototrophic bacteria. After the dystrophic crisis, oxic conditions were reestablished and the phototrophic bacterial biomass was partly grazed by zoobenthos organisms which densely populated the sediment surface.

Phototrophic sulfur bacteria and sulfate-reducing bacteria causing red waters in a shallow brackish coastal lagoon (Prévost Lagoon, France)

In the shallow lagoon of Prévost (43°30′N, 3°54′E; French Mediterranean coast), red waters occurring periodically during warm summers are a consequence of a succession of ecological events beginning in the early spring with a bloom of algae ( Ulva lactuca). In summer 1977, a red water was analyzed; in the early summer, the water turned anoxic and became rich in sulfide which originated from sulfate reduction in the first 10 cm of the sediment. Numbers of both phototrophic and sulfate-reducing bacteria (SRB) increased during spring and summer, and the genera in the prevailing populations did not change: Thiocapsa (80%) among the phototrophic bacteria and Desulfovibrio and Desulfobacter among the SRB. They were also dominant during the period of red waters. A few Chromatium and Thiocystis species were also identified. During red water periods, these bacteria grew very actively, removing all the sulfide produced by SRB, and accumulated in the whole water column. Consequently, the sulfate level increased to 5 mmol·1 −1 higher than the theoretical sulfate level calculated from salinity, showing the active oxidation of sulfide by phototrophic bacteria. After the dystrophic crisis, oxic conditions were reestablished and the phototrophic bacterial biomass was partly grazed by zoobenthos organisms which densely populated the sediment surface.

Distributión de avifauna en los distintos ‘Habitats’ del Estuario Andalién, Bahia de Conceptión, Conception, Chile

In a first survey a total of 70 species of birds was found in the area of the Andalien river estuary in Chile during the years 1979 to 1981. There are four major types of habitat: the marine coastal zone, the vegetation covered coastal plain, the brackish coastal lagoons, and the mud flats aiong the river. The distribution of adaptive types of birds across these different kinds of habitat is shown qualitatively in the figs. 2 to 5. Twelve of the 70 species are migrants from North America and distant regions of South America, the remaining 58 are residents of Central Chile.