Organ distribution and bioaccumulation of microcystins in freshwater fish at different trophic levels from the eutrophic Lake Chaohu, China

Abstract

This article reports the organ distribution and bioaccumulation of hepatotoxic microcystins (MCs) in freshwater fishes at different trophic levels from the large, shallow, eutrophic Lake Chaohu in September 2003, when there were heavy surface blooms of toxic cyanobacteria. Among all fish, intestines and blood had the highest average content of MC-RR + MC-LR (22.0 and 14.5 microg g(-1) DW, respectively), followed by liver, bile, and kidney (7.77, 6.32, and 5.81 microg g(-1) DW, respectively), whereas muscle had the least (1.81 microg g(-1) DW). MC content in muscle was highest in carnivorous fish (Culter ilishaeformis, 2.22 microg g(-1) DW) and omnivorous fish (Carassius auratus, 1.96 microg g(-1) DW) and was lowest in phytoplanktivorous fish (Hypophthalmichthys molitrix, 1.65 microg g(-1) DW) and herbivorous fish (Parabramis pekinensis 0.660 microg g(-1) DW). However, the amount of MC in the gut of H. molitrix (137 microg g(-1) DW) was more than 20 times that in the other fish (<6.50 microg g(-1) DW). The MCs showed a tendency to accumulate up the food chain, and piscivorous fish at the top of the food chain were at high risk of exposure to MCs in Lake Chaohu. Our study is the first to report MC concentrations in the bile and blood of wild fish. One hundred grams of fish muscle would contain 2.64-49.7 microg of MC-LR equivalent, or about 1.3-25 times the recommended tolerable daily intake of MC-LR by humans, indicating that fish are already severely contaminated by MCs and that the local authorities should warn the public of the risk of poisoning by eating the contaminated fish.

Bioaccumulation of microcystins (MCs) in four fish species from Lake Taihu, China: Assessment of risks to humans

“…This result is consistent with previous studies (Chen et al, 2006;Zhang et al, 2009), which indicate that accumulation in the intestinal wall can inhibit further transport of MCs into internal organs. The MC concentrations in the livers of the four fish species studied here were all relatively low, which contradicts the results of previous studies (Kankaanpää et al, 2005;Li et al, 2004;Malbrouck et al, 2003;Xie et al, 2005). The liver is an important detoxification organ, and bile plays an important role in the elimination and recirculation of excess MCs from the fish liver (Tencalla and Dietrich, 1997).…”

“…However, other authors found MC concentrations in phytoplanktivorous fishes (Zhang et al, 2009) higher than those reported by Xie et al (2005). No significant difference was observed for the MC concentrations between phytoplanktivorous and omnivorous fishes (p N 0.05) in the present Table 3 Correlations between MCs in variety organs of study.…”

“…However, few studies have simultaneously evaluated multiple fish organs, such as the gut, kidney and heart, which may also accumulate MCs and affect the health of aquatic animals. MCs accumulate in the phytoplanktivorous silver carp (Hypophthalmichthys molitrix), herbivorous white bream (Parabramis pekinensis), omnivorous common carp (Cyprinus carpio),crucian carp (Carassius auratus) and carnivorous species, including the predatory carps (Culter ilishaeformisand Culter erythropterus), the yellow catfish (Pseudobagrus fulvidraco), Osbeck's grenadier anchovy (Coilia ectenes) and the salangid icefish (Neosalanx taihuensis); however, it is not currently known which fish species accumulate the highest amounts of MCs in their tissues (Gkelis et al, 2006;Xie et al, 2005;Zhang et al, 2009).…”

Hepatic Histopathological Characteristics and Antioxidant Response of Phytoplanktivorous Silver Carp Intraperitoneally Injected with Extracted Microcystins

“…Little information is available on the toxic effects of MCs in phytoplanktivorous fishes that are more frequently exposed to cyanobacterial toxins under natural conditions because of habitat and feeding mode. It has been reported that silver carp (Hypophthalmichthys molitrix) accumulates MCs in intestine, blood, liver, kidney and muscle like other freshwater fish [10] , at levels above the tolerable daily intake (TDI) of 0.04 μg/kg body weight (BW) per day proposed by WHO as a provisional guideline value [11] . This is of great concern for public health because chronic ingestion of trace amounts of MCs (MC-LR in particular) in food and drinking water has a considerable potential to promote cancer [2] .…”

Quantitative liquid chromatography–tandem mass spectrometry method for determination of microcystin-RR and its glutathione and cysteine conjugates in fish plasma and bile

“…To date, more than 80 structural analogs of MCs have been identified, and microcystin-RR (MC-RR) is one of the dominant variants in cyanobacterial blooms in lakes of China [3,4]. MCs primarily act as hepatotoxins because the liver is the target organ in various animals.…”