Algae-Bacteria relationship altered by increasing stratification and UVR in oligotrophic Mediterranean lakes

CARRILLO, P.; MEDINA-SÁNCHEZ, J. M.; JIMÉNEZ-COLL, E.; DURÁN, C.; HERRERA, G.; CABRERIZO, M.; VILLAR-ARGAIZ , M.; VILLAFAÑE, V. E.; HELBLING, E.W.

Budapest

Congreso; 32nd International SIL; 2013

International Society for Limnology

In a global warming scenario a decreasing of epilimnion depth and increasing of DOC content associated with altered precipitation regimes is expected. The dual effect of increasing (by stratification) or decreasing (by DOC increase) exposure to UVR, complicates algal and bacterial responses and modified the strength of their commensalistic relationship. To determine the combined effects of UVR and stratification on metabolism of algae and bacteria, we carried out in situ experiments in two lakes with contrasting optical properties determined by DOC concentration. Our results indicate that the joint effect of UVR and stratification, accentuated UVB negative effect on PP and PB, with a stronger effect in high DOC than in low DOC lakes. Their commensalistic interaction turned into a coupled algae-bacteria relationship in low-DOC lake, but less coupled in high DOC lake. These results have several implications for carbon-flux in inland lakes of Mediterranean region.