Vm. Vasconcelos, UPTAKE AND DEPURATION OF THE HEPTAPEPTIDE TOXIN MICROCYSTIN-LR IN MYTILUS-GALLOPROVINCIALIS, Aquatic toxicology, 32(2-3), 1995, pp. 227-237
Mussels (Mytilus galloprovincialis Lamarck) were exposed to the toxic
cyanobacterium Microcystis aeruginosa Kutz. emend Elkin for 16 days in
order to study bioaccumulation of the cyclic heptapeptide toxin micro
cystin-LR. After this time period the animals were fed marine phytopla
nkton for 2 weeks and the amount of microcystin in the mussels was mon
itored again. During the exposure phase mussels attained a maximum of
10.5 mu g of toxin per g dry mussel weight at day 10. Microcystin was
detectable after the second day of exposure. The percentage of toxin t
hat was taken up relative to the total amount administered varied from
24.1% to 54.8%. When the mussels were fed marine phytoplankton there
was a 50% decrease in the amount of detectable toxin in the mussels wi
thin 2 days. This was followed by a slight increase in toxin levels ov
er 5 days with no microcystin-LR being detected at day 13. The major p
art of the toxin (96%) was found in the digestive gland + stomach whil
e the gills, muscle, foot, and other organs combined had less than 4%
of the total toxin. The results presented here show that cyanobacteria
blooms present in estuaries where bivalves are growing naturally cons
titute a health hazard in that these organisms can retain microcystins
and transfer them through the food chain.