Microcystins uptake by the yellow clam Mesodesma Mactroides (bivalvia, mactroidea)

Abstract

Microcystins (MCYST), common cyanobacterial hepatotoxins, have been observed in the Patos Lagoon and the estuary over the last three decades. Anthropogenic pollution associated to the environmental features has promoted the frequent occurrence of cyanobacterial blooms in this environment. The present work aimed to evaluate the MCYST uptake by the filter-feeding mollusk Mesodesma mactroides Deshayes, 1854, which occurs in the nearby coasts of the Patos Lagoon estuary, Brazil. Bioassays were carried out using the toxic strain Microcystis aeruginosa RST9501, isolated from the Patos Lagoon estuary. Clams were exposed to live cells of this toxic cyanobacterium for 12 days, taking up MCYST to a maximum of 5.27±0.23 μg MCYST.g-1 (dry hepatopancreas weight). Since several blooms reaching the Patos Lagoon estuary and the nearby areas are observed, these results indicate that the toxins from M. aeruginosa blooms can be accumulated by this filter-feeding animal, making it a potential vector to the local trophic web.