Depuration time and sublethal effects of microcystins in a freshwater fish from water supply reservoir

Abstract

Microcystins (MCs) are hepatotoxins that have been considered to be a worldwide problem due the effects that they can cause to environmental and human health systems. The Iraí Reservoir, located in the South of Brazil, is used as a water supply and MCs concentrations have been reported in this ecosystem. This study aimed to determine the MCs concentrations in the Iraí Reservoir and to evaluate the MCs depuration time and the health of Geophagus brasiliensis using biomarkers. Water and fish samples were collected in the Iraí Reservoir from August 2015 to May 2016. Phytoplankton and chemical analyses were conducted using water samples and the fish were divided into two groups; the Immediate Group (IMM) and the Depuration Group (DEP). In the IMM group, the blood, liver, muscle, brain and gills were collected, in order to evaluate the genotoxic, biochemical and chemical biomarkers. The DEP group was used in the depuration experiment for 90 days, and after this period the fish were submitted to the same procedure as the IMM group. Our results suggested that fish accumulated MCs and it may have caused oxidative stress, neurotoxicity and molecular damage. Furthermore, MCs concentrations increased during the depuration time and it resulted in molecular damage over the first 30 days. After 90 days, the recovery of the antioxidant system occurred. The depuration started on the 15th day, however, the toxins were still present in the samples. Therefore, the effects and the persistence of MCs are a risk to environmental systems and human health.

Cyanotoxins and Food Contamination in Developing Countries: Review of Their Types, Toxicity, Analysis, Occurrence and Mitigation Strategies

“…The same authors studied the depuration of MCs in G. brasiliensis after 7, 15, 30, and 90 days of MCs exposure. The results showed that MCs can still be detected in muscles even after a period of three months [162]. Sliver carp (Hypophthalmichthys molitrix) consumers (Brasilia-FD, Brazil) would be exposed to a high level of MCs, especially in the dry season of winter, which is 240 times more than the recommended provisional TDI [163].…”

Hepatic oxidative stress and neurotoxicity in Pelophylax kl. esculentus frogs: Influence of long-term exposure to a cyanobacterial bloom

“…The phenomenon of a cyanobacterial bloom in aquatic ecosystems has become a widespread and progressive environmental stressor in a eutrophication-laden world (Ţegura et al, 2011). Previous laboratory and field studies showed that chronic exposure to environmentally relevant/low concentrations of cyanotoxins presents a serious risk to organism and ecosystem health (Calado et al, 2018;Chen et al, 2017;Pavagadhi et al, 2012;Zhang et al, 2009). Results…”

“…Even though we did not measure the bioaccumulation of MCs by frogs, there is evidence that adult frogs accumulate MCs in tissues at a higher level than fish (Papadimitriou et al, 2012). Recent studies showed that long-term exposure of aquatic organisms to cyanobacterial blooms results in the bioaccumulation of MCs, even in case of a low concentration of toxins in water (Zhang et al, 2009;Calado et al, 2018).…”

A network meta‐analysis of threats to South American fish biodiversity

“…The increasing foraging on the bottom by generalist-non-native fish such as tilapia may also favour the prevalence of bloom-forming Cyanobacteria (Lazzaro et al, 2003;Reissig, Trochine, Queimaliños, Balseiro, & Modenutti, 2006; Salazar Torres, Silva, Rangel, Attayde, & Huszar, 2016;Starling, Lazzaro, Cavalcanti, & Moreira, 2002), which grow faster in high eutrophic waters (O'Neil, Davis, Burford, & Gobler, 2012;Paerl & Paul, 2012). Such invaders can tolerate oxygen deficiency and the accumulation of ammonia in the environment that causes mass fish mortality to native fish (Calado et al, 2018) and physiological and molecular damage to native fish and human consumers (Calado et al, 2018;Paerl & Paul, 2012).…”

“…Micro-pollutants can bioaccumulate in fish tissues and can lead to fish (Valdés, Amé, Bistoni, & Wunderlin, 2014) and human (Calado et al, 2018) death as well as local extinctions of fish species (Kidd et al, 2007). Pollution affects the traits and behaviours of fish populations, such as parental care and predator avoidance (e.g., Scott & Sloman, 2004), also decreasing the reproductive fitness (Jones & Reynolds, 1997) and leading to mass mortality under extreme conditions (Jones & Reynolds, 1997;Kidd et al, 2007).…”