Bloom forming cyanobacteria in Argentina: where do we stand ?

OFARRELL, I.; POLLA, W.; DEVERCELLI, M.; FORASTIER, M.; MEICHTRY DE ZABURLÍN, N.; MOTTA, C.; OTAÑO, S.; LOMBARDO, R.

Torino

Congreso; 33rd. SIL Congress; 2016

Through a meta-analysis of the bloom-forming cyanobacteria, we aimed to synthesise the main reasons that explain thedistribution of their blooms in Argentina. We analysed in detail published academic literature, information in technicalreports and in non-published studies from 1944 till 2015 in a territory that covers a variety of climates ranging fromhumic tropical to cold temperate through approximately 3700 km (21°46´S to 66°31´W). Blooms were registered inshallow and deep lakes, rivers, streams, reservoirs, estuaries and storage facilities located along the six lake regionsdefined for Argentina: Puna, Chaco-Pampa Plain, Peri-Pampean Sierras, Andean Patagonia, Patagonia Plateau andMisiones Plateau. We defined as a quantitative indicator of a bloom a threshold abundance of 5000 cel/ml for a singlespecies in accordance to legislation available in countries located at similar latitudes (Brazil and Australia) as there areno alert levels defined for Argentina. The intensity -maximum registered abundance-, species and ecological strategyresponsible of each bloom were related to the geographic and climatologic characteristics of the corresponding locationand the type of aquatic system.We registered and geo-referenced 130 locations related to those aquatic environments affected by cyanobacterialblooms. Puna and the Andean Patagonia regions are free of blooms with the exception of a shallow lake in the latterarea. Shallow lakes and reservoirs, appear as the most prone aquatic systems to experience blooms in all regions (44and 24% of the studied sites, respectively). Deep lakes have no reports ; only at Lake Musters, in the Patagonia Plateau,there is a registered value that is close to the here considered threshold abundance. Rivers are mainly affected at theregulated reaches and the intensity of blooms generally decreases downstream the dams. There were more than 30different species responsible of the blooms as identified by Komárek?s polyphasic approach to taxonomy. Microcystisaeruginosa, Dolichospermum spiroides and Cylindrospermopsis raciborskii were the most frequent, either in mixed orsingle species blooms. Species distribution differs according the geographic location and the type of aquatic system.While Microcystis aeruginosa has a wide geographical distribution through Argentina, Cylindrospermopsis raciborskii ismainly circumscribed to the north-eastern territory. On the other hand, the limnological characteristics of the systemsare closely related to the eco-strategy of the prevailing bloom-forming species.