Samples of macrophyte algae were collected from an ecotope of Kandalaksha Gulf, the White Sea. These algae were selected from substrates, storm wracks and after long-term storage in the soil, and they were assessed by indirect competitive enzyme immunoassay for the presence of low-molecular-weight metabolites of micromycetes (mycotoxins). In Fucus distichus, F. serratus, F. vesiculosus, and Ascophyllum nodosum, the concentrations of all analyzed toxic substances from storm wracks were uniformly reduced compared to those in living thalli. For Laminaria digitata, Saccharina latissima, and Ahnfeltia plicata, in living individuals of which mycotoxins were not found or were extremely rare, cases of contamination with citrinin, mycophenolic acid, emodin and sterigmatocystin were found in storm wracks. After 12 months of burial in soil F. distichus samples had only 9 components out of 16 analyzed. In F. serratus, F. vesiculosus, A. nodosum, and Pelvetia canaliculata, only emodin, mycophenolic acid, alternariol, and ergot alkaloids were determined.