Identification and estimation of microcystins in freshwater mussels

Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) from a large shallow, eutrophic lake of the subtropical China

“…This is contradictory to the results for a resident snail (Sinotaia histrica) in a Japanese lake (Lake Biwa) where MC content of the hepatopancreas was only 1/6 that of intestine in October with trace or undetectable amount when MC content of intestine was between 2.59 and 4.82 mg g ÿ1 DW during July-September (Ozawa et al, 2003). On the other hand, in Lake Suwa, Watanabe et al (1997) reported a slightly higher MC content in the hepatopancreas (1.57 mg g ÿ1 ) than in the gut (1.31 mg g ÿ1 ) for a freshwater mussel (Unio douglasiae) although the measurement was conducted only for one sample. In spite of the fact that the measurement of MC in intestinal tracts may be occasionally affected by various factors (e.g., sampling procedures, degree of food digestion), the constantly lower MC content in the digestive tract of B. aeruginosa in our study lake was most likely a real reflection of their food resources on the sediment where a high sedimentation rate of sand materials probably led to a relatively low MC content in the food of the snails.…”

“…In the present study, although the target organ of MC was hepatopancreas, a substantial amount of MC accumulated in the gonad of B. aeruginosa. In Lake Suwa (Japan), a freshwater mussel (Unio douglasiae) accumulated 1.57 and 1.19 mg MC g ÿ1 DW in hepatopancreas and gonad, respectively (Watanabe et al, 1997). Our results indicate that the average ratio of MC-LR/MC-RR showed a steady increase from digestive tracts (0.44) to hepatopancreas (0.63) and to gonad (0.96), suggesting that MC-LR might be more resistant to degradation in the snail.…”

“…So far, there have been only occasional reports on the presence of microcystin contamination in wild aquatic animals, such as fish (Magalha`es et al, 2001;Zimba et al, 2001;Mohamed et al, 2003), mussels (Watanabe et al, 1997) and snails (Kotak et al, 1996;Zurawell et al, 1999;Ozawa et al, 2003). Such studies are still lacking in China where most freshwaters are at a high risk to toxic cyanobacterial blooms but freshwater fisheries are almost equally important as marine fisheries to Chinese consumption.…”

Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in two freshwater shrimps, Palaemon modestus and Macrobrachium nipponensis, from a large shallow, eutrophic lake of the subtropical China

“…There have been only occasional reports on microcystin contents in edible wild aquatic animals such as fish in a Brazil lagoon (Magalhàes et al, 2001) and an Egyptian fish farm (Mohamed et al, 2003). MC contents were also measured occasionally for mussels in Lake Suwa (Japan) (Watanabe et al, 1997;Yokoyama and Park, 2002) and snails in several Canadian lakes (Kotak et al, 1996) and Lake Biwa (Japan) (Ozawa et al, 2003) because of the concern that MCs may be transported to terrestrial food web (Prepas et al, 1997;Ozawa et al, 2003). However, so far no information is available on MC contents in shrimps, prawns or crayfish collected from natural freshwater environments.…”

Bioaccumulation of microcystins in two freshwater gastropods from a cyanobacteria-bloom plateau lake, Lake Dianchi

“…The results demonstrating high amounts of MCs accumulating in the digestive tracts of aquatic animals had been reported in previous research , which found that the concentration of MCs in digestive tracts (9.03 mg/g DW) of S. histrica was significantly higher than that in other organs (i.e., the hepatopancereas, gonads, and feet). Moreover, Watanabe et al (1997) reported that MCs content in the hepatopancreas of one freshwater mussel (Unio douglasiae) was a slightly higher than that in the digestive tracts in Lake Suwa.…”