Effects of UV radiation on allelochemicals from filamentous algae: does it make a difference for target algae?

TROCHINE C., MODENUTTI B. & BALSEIRO E.

San Juan de Puerto Rico, PR

Congreso; ASLO Aquatic Sciences Meeting; 2011

ASLO

North Patagonian shallow lakes can be very transparent, allowing high penetration of UV- radiations besides having very low nutrient levels. In these aquatic environments allelopathy may provide a competitive advantage to primary producer’s interaction. Particularly, allelopathy is especially effective in stress situations, e.g. under nutrient limitation, yet, UVR plays an important role in altering and degrading dissolved organic molecules. We studied the effects of UVR on allelochemicals released by filamentous green algae (FGA), to establish whether UVR affects their function and to understand the fate of these compounds in aquatic ecosystems. We measured the effect of allelochemicals obtained from FGA filtrates on natural phytoplankton performing a factorial design with 4 treatments: +FGA filtrate, −FGA filtrate, and the mentioned treatments exposed to UVR (UVA340) for 2 h. We observed a decrease in phytoplanktonic Chl-a in the +FGA filtrate treatment compared to the control and we found that UVR modeled the inhibition of phytoplanktonic growth. We suggest that UVR could have a negative effect on the concentration of FGA active allelochemicals in the water, which results in a positive outcome for target phytoplankton.