22 research outputs found
Initial impacts of Microcystis aeruginosa blooms on the aquatic food web in the San Francisco Estuary
Alpha and beta diversity of phytoplankton in two subtropical eutrophic streams in southern Brazil
Microcystins derived from lysing Microcystis cells do not cause negative effects on crustacean zooplankton in Lake Taihu, China
Accelerated eutrophication and toxicity in tropical reservoir water and sediments: an ecotoxicological approach
Analysis of mortality from diarrheic diseases in under-five children in Brazilian cities with more than 150,000 inhabitants
Assessment of microcystin distribution and biomagnification in tissues of aquatic food web compartments from a shallow lake and evaluation of potential risks to public health
The objectives of this study were: (1) to examine the distribution and bioaccumulation of microcystins in the main components of the food web (phytoplankton, zooplankton, crayfish, shrimp, mussel, snail, fish, frog) of Lake Pamvotis (NW Greece), (2) to investigate the possibility of microcystin biomagnification and (3) to evaluate the potential threat of the contaminated aquatic organisms to human health. Significant microcystin concentrations were detected in all the aquatic organisms during two different periods, with the higher concentrations observed in phytoplankton and the lower in fish species and frogs. This is the first study reporting microcystin accumulation in the body of the freshwater shrimp Atyaephyra desmsaresti, in the brain of the fish species common carp (Cyprinus carpio) and in the skin of the frog Rana epirotica. Although there was no evidence for microcystin biomagnification, the fact that microcystins were found in lake water and in the tissues of aquatic organisms, suggests that serious risks to animal and public health are possible to occur. In addition, it is likely to be unsafe to consume aquatic species harvested in Lake Pamvotis due to the high-concentrations of accumulated microcystins
Occurrence of anatoxin-a(s) during a bloom of Anabaena crassa in a water-supply reservoir in southern Brazil
Cyanobacterial blooms and the accompanying
production of cyanotoxins are a serious global problem. Toxic blooms of Anabaena species are common in lagoons and reservoirs of southern Brazil. Worldwide, species of the
genus Anabaena produce the majority of the known hepatotoxins (microcystins) and neurotoxins [anatoxin-a, anatoxin-a(s), and saxitoxins]. This report links a bloom of
Anabaena crassa in the Faxinal Reservoir, the main water supply for the city of Caxias do Sul (400,000 inhabitants) in southern Brazil, to the occurrence of anatoxin-a(s) in the water. During the bloom period, the reservoir was strongly stratified, with higher temperatures and a deep anoxic
hypolimnion. Two methods for sample concentration (direct and complete extraction) were tested, and direct extraction of samples proved to be more efficient. Water samples collected during the bloom showed 9% acetylcholinesterase
inhibition at 50 mg mL−1, corresponding to 0.61μg of anatoxin-a(s) per gram of lyophilized powder. At these concentrations, symptoms of neurotoxicity and mortality
were not observed in tests with Swiss albino mice. Although the concentrations of anatoxin-a(s) in the Faxinal Reservoir were low, these results are important because this
is the first record of the toxin for A. crassa. Furthermore, this cyanotoxin is not yet included in Brazilian legislation
for drinking-water monitoring, because of the lack of information about toxicity levels and risk calculation for oral doses. The data presented here contribute to the basis for the future inclusion of this toxin in Brazilian legislation for drinking-water quality control, and for the development of analytical methods for this toxin