Review of current state of knowledge of microcystin and its impacts on fish in Lake Victoria

Abstract

Microcystins are part of algal toxins produced intracellularly within algal cells, being in the family of hepatotoxic cyclic peptides from various species of blue‐green algae. Blue‐green algae are widely abundant in many equatorial eutrophic lakes, including Lake Victoria, with microcystin mainly from cyanobacterial blooms released into the water column, with different effects along the aquatic ecosystem trophic levels. Depending on the length of exposure and exposure route, microcystin effects on fish can include embryonic hatching perturbations, reduced survival and growth rates, changes in behavior, osmoregulation, increased liver activities and heart rates, as well as histopathological effects. While bioaccumulation is confirmed among fish, biomagnification along food webs is debatable. Lake Victoria the second largest freshwater lake in the world, and the source of livelihoods to millions reported near the gulf and shore MCs of 190 ± 51 to 543 ± 26 ng MC/g DW, respectively. Little is known, however, on the effects of microcystin on the Lake Victoria fishery and, ultimately, on the human population against the WHO recommended human microcystin intake levels of 0.04 µg/kg, thereby being the basis for this review.

Enviromental Risk Factors Associated with Primary Liver Cancer in Western Kenya: A Mini-review

“…This is in further support by Moreira et al [50], who reports the health status of communities within Kisumu area whose health could have been threatened by the consumption and use of cyanoHab contaminated Lake water. All these taken together with, Onyango et al [6] study, confirms further on the implication of microcystin on the Lake Victoria fishery and, ultimately, on the human population who depend on the Lake water as source of domestic use. Going by the above observations, the communities living around Lake Victoria who draw cyanotoxin polluted water for their domestic and animal use are exposed to high level of toxins thus the need for surveillance and determination of risk factors under current conditions [51,52,53].…”

“…However, its ranking moved to third most common malignancy in males occurring with a peak incidence rate at 40 years of age [6]. The high number of cases (5.2%) was reported in Nyanza region, with countries bordering the lake region reporting the high prevalence rate [6]. The attributable risk was congruent to the global prevalence of 4.6% within the region.…”

“…According to Burden et al, [5] in Kenya, Primary liver cancer ranked 6th in males and 5th in females as per the Nairobi cancer registry 2016. However, its ranking moved to third most common malignancy in males occurring with a peak incidence rate at 40 years of age [6]. The high number of cases (5.2%) was reported in Nyanza region, with countries bordering the lake region reporting the high prevalence rate [6].…”

Rhizobium-Linked Nutritional and Phytochemical Changes Under Multitrophic Functional Contexts in Sustainable Food Systems

“…Rhizobia symbiotically fix approximately 40 million tons of nitrogen in agroecosystems annually (Udvardi and Poole, 2013). Bio-inoculants based on symbiotic nitrogen fixing Rhizobium species could help minimize the misuse of synthetic nitrogenous fertilizers (Zahran, 1999), which have been linked to phytotoxicity (Naluyange et al, 2014;Delgado et al, 2016), soil acidification (Sha et al, 2020), and eutrophication of water bodies resulting in algal blooms and water hyacinth invasiveness (Naluyange et al, 2014;Onyango et al, 2020). Besides, the misuse of synthetic nitrogenous fertilizers is a public health concern (Wang and Lu, 2020), as the unassimilated salts in consumed plant tissues and the environment have been linked with health problems including respiratory ailments, cardiac diseases, and cancers (Townsend et al, 2003;Lu et al, 2015).…”

Microcystins Detection Methods: A Focus on Recent Advances Using Molecularly Imprinted Polymers

“…MC-contaminated water is odorless and tasteless, and these cyanotoxins are not destroyed by cooking . MCs accumulate in the body through water consumption or the food chain producing severe hepatotoxic effects. − Aware of this problem, different countries have developed regulations or guidelines for controlling MCs concentrations (expressed as total MC-LR equivalents) in drinking, irrigation, and recreational water . In 1998, the World Health Organization (WHO) established a maximum concentration of 1 μg L –1 for MC-LR in the first published provisional drinking water guideline .…”