Photosynthetic performance associated with phosphorus availability in mats of Didymosphenia geminata (Bacillariophyceae) from Patagonia (Argentina and Chile)

BEAMUD SG; BAFFICO G; REID B; TORRES R; GONZALEZ-POLO M; PEDROZO, F.L.; DIAZ M

PHYCOLOGIA

INT PHYCOLOGICAL SOC

Lugar: Lawrence; Año: 2016 vol. 55 p. 118 - 125

0031-8884

Recentlyreported blooms of Didymosphenia geminatafrom rivers in Argentinean and Chilean Patagonia, together with non-typicalblooms reported from lake systems, have the potential to alter community andecosystem dynamics of aquatic environments in the region. In an effort toquantify key aspects of ecosystem function of D. geminata mats in Patagonia, we describe for the first timephotosynthesis-irradiance (P-E) curves of this species,associated P-E parameters (R, Pmax and α),and their relationship to other functional (APA enzyme activity and chlorophylla) and environmental variables(soluble reactive and organic phosphorous, electrical conductivity). Mats of D. geminata from lakes and riversrepresenting east and west sides of the Andes from 40-46° S (i.e. much ofcurrent known distribution) varied mostly in the α and Pmaxparameters of P-E curves. Southern systems showed a higher αand lower Pmax parameters than more northern sites on the eastslope of the cordillera. None of the P-E curves showed photoinhibition. P-Eparameters for the two lakes fell within the range of values for riverine mats,although soluble reactive P was notably higher in the lakes. We used twodifferent statistical approaches to evaluate associations across environmental,functional or P-E parameters, finding a strong relation between APA and Pmaxand a weak one between SRP, pH, DOP and functional parameters. Our results donot contradict previous observations on the importance of P availability in DGcommunities, although the variability in response across P-E parameters suggests amore complex mechanism of regulation than implied in the existing literature.