Cyanobacteria bloom variations and atmospheric variables, an environmental health contribution

Abstract

Urbanization in river basins contributes to the anthropogenic eutrophication of their water bodies, leading to the proliferation of toxic algae such as cyanobacteria. There is a characteristic pattern of seasonality in algal blooms and cyanobacterial communities, although these algae may be present or even dominant for most of the year, causing practical problems associated with high cyanobacterial biomass and potential health threats. The increased concentration of toxins originating from these algae, cyanotoxins, in water-supply reservoirs puts the population at serious risk, since they are not removed by conventional treatment and filtration. This study analyzed possible associations between climate elements and cyanobacteria biomass in the Guarapiranga dam reservoir, located in the metropolitan region of São Paulo, Brazil. Meteorological variables were studied exclusively in relation to the cyanobacteria biomass, in order to perceive the influence of weather and climate in this complex system and to provide data for modeling future climate change scenarios. For this purpose, cyanobacteria count data were used for the period from 2010 to 2016, grouped by month, in addition to the atmospheric variables. The strongest correlation with the blooms was with Irradiation and Total Rainfall, explaining 30% of cases of the occurrence of cyanobacteria proliferation at the point of collection GU 101. Despite the notable influence of climatic seasonality on the algae blooms, this difference varies and is not homogeneous, depending on the location and the species studied.

Ecological indexes and phytoplankton structure of urban reservoirs supplied by estuarine waters and under the effects of seasonality (Belém, Pará, Brazil)

“…The classes Cryptophyceae (33%), mainly with the species Rhodomonas minuta (Skuja), and Euglenophyceae (34%), with the species Trachelomonas volvocina (Ehrengerg) Ehrengerg, dominated in July and October, respectively (Figure 3a). In this period, the classes in evidence are represented by the presence of two species that inhabit clear mesotrophic environments [15], mainly at AP1 station of the Água Preta reservoir, combined with the environmental characteristics of this portion of the reservoir, which is more lentic and transparent, these months represent the dry period where higher values of transparency and lower turbidity occur, factors that directly influence the entry of light into the water column and this condition is limiting to phytoplanktonic development [57].…”