Distribution of prokaryotic organisms in a tropical estuary influenced by sugar cane agriculture in northeast Brazil

Abstract

In a joint Brazilian-German case study, distribution patterns of microorganisms were compared with environmental variables in the tropical coastal Manguaba lagoon in northeast Brazil, which is situated downstream of several sugar cane processing plants . 16S rDNA and 16S rRNA single strand conformation polymorphism (SSCP) gene fingerprinting were used to follow the composition and distribution of microorganisms throughout the salinity gradient of the lagoon. Potentially abundant microorganisms were identified by sequencing representative SSCP bands. It could be demonstrated that the distribution of microbes was in close relation to the physico-chemical environmental settings and followed a common scheme. In the in- and outlet areas of the lagoon rather transient microbial communities were found, whereas in the central part a stable, diverse community was encountered, that due to the long residence time of the water, had ample time for development and adaptation.

Lipids in the sedimentary record as markers of the sources and deposition of organic matter in a tropical Brazilian estuarine–lagoon system

“…It is noteworthy that the similarity in the depth-profiles percentages of bacterial and phytoplankton-derived lipids in the top layers of cores C03, C06 and C07, which suggests that the increase in the accumulation of autochthonous OM also caused an increase in the bacterial activity in the sediments. This is corroborated by recent estimates that show an overall elevated bacterial metabolism in MMELS (Wolf et al, 2010).…”

“…On the other hand, the relatively low variability in the mean values for each core is evidence that the major changes occurred before the final burial of OM in the sediment, probably at the sediment-water interface or in the water column (Wolf et al, 2010). Therefore, it may be considered that the changes in the relative accumulation of autochthonous and allochthonous OM in MMELS through time were mainly induced by anthropogenic activities, like changes in soil use and urban settlement, instead of reflecting a clear effect of OM diagenesis.…”

Fontes e distribuição de matéria orgânica sedimentar no complexo estuarino-lagunar de Mundaú-Manguaba/AL, utilizando esterois e alcoóis como indicadores

“…O CELMM enquadra-se na categoria de um sistema estuarino-lagunar do tipo "sufocado", 27 e apresenta características como troca restrita das suas águas com o mar, tempos longos de residência das massas de água, um alto potencial de reciclagem e retenção de matéria orgânica na água e nos sedimentos, e condições eutróficas mantidas por populações fitoplanctônicas mistas e florescimentos de cianobactérias. 20,22,27,28 , respectivamente.…”