Comunidade fitoplanctônica em ambientes lóticos no estado de Santa Catarina: aspectos taxonômicos e ecológicos

Abstract

Ecological works with the phytoplankton community as a basis for monitoring aquatic environments are frequent and of great importance, especially in environments that have undergone anthropogenic actions, such as impoundments, which modify the chemical, physical and ecological attributes of aquatic environments. On the other hand, there is also a concern to know the biodiversity of the various aquatic environments, for which, floristic surveys are of extreme importance throughout Brazil, especially in the state of Santa Catarina, where they are scarce. For that, the environmental variables and the phytoplankton community were evaluated, with focus on Reynolds functional groups (RFGs) in the area of influence of a subtropical small hydropower (SHP) plant in the state of Santa Catarina. The collections were carried out in two phases: pre and post-impoundment, from 2007 to 2013. Statistical analyzes were performed in order to resize the data and to correlate the abiotic and biotic variables. 449 taxa were recorded, distributed in 11 taxonomic groups and 14 RGFs. RGF C, represented by centric diatoms, was dominant in the pre-damming phase. In the post-damming phase, besides RGF C, co-dominance of RGF P (Aulacoseira granulata var. Granulata), RGF N (dehmids), RGF J (chlorophytes) and RGF H1 (cyanobacteria heteocytes) occurred. Low phytoplankton biological volume values were recorded for the Santa Laura SHP in general, however, the highest among the phases was after damming, in the lacustrine region of the reservoir. Also in the state of Santa Catarina, a taxonomic survey of the genus Eunotia Eherenberg in the river Hercílio municipality of Ibirama was carried out. The samples were collected quarterly (April, July and October/2009), in four sampling stations, totaling 12 samples. The study resulted in the identification of 30 taxa of the genus Eunotia, of which four were determined at the generic level. Of the species identified, nine are new citations for the state of Santa Catarina and five for Brazil.