Metabolism recovery of a stromatolitic biofilm after drought in a Mediterranean stream fig: 3
Romani, Anna M.; Sabater, Sergi
published: Sep 25, 1997
ArtNo. ESP141014002011, Price: 29.00 €
Organisms dwelling in Mediterranean streams need to be adapted to dry periods. La Solana stream dried out completely during summer 1994. The recovery of the biofilm was studied in a laboratory experiment by immersing it in stream water. La Solana has a thick stromatolitic biofilm composed of the cyanobacteria Rivularia sp. and Schizothrix spp. Ectoenzymatic microbial activities (ß-glucosidase, ß-xylosidase and phosphatase), H14CO3 incorporation and respiration (Electron Transport System-ETS-activity) were measured immediately after rewetting and then every hour for 5 h. Both ETS and photosynthetic activities were low at the beginning of the rewetting but increased significantly after two hours. Recovery of enzymatic activities in the biofilm was immediate, since values measured at 0 h were similar to those obtained in the stream before drought. Enzymatic activities increased markedly after three hours to higher values than those reported before drought. All activities stabilized to initial values at the end of the experiment. We suggest that the rapid recovery of the biofilm metabolism could be supported by the stromatolitic structure of La Solana biofilm acting as a reserve of organic matter, as well as the rapid rehydration provided by the cyanobacteria sheaths. This implies that the biofilm can exploit short rainfall periods in dry summers.