title: Evidence of freshwater algal toxins in marine shellfish: Implications for human and aquatic health.
abstract: The occurrence of freshwater harmful algal bloom toxins impacting the coastal ocean is an emerging threat, and the potential for invertebrate prey items to concentrate toxin and cause harm to human and wildlife consumers is not yet fully recognized. We examined toxin uptake and release in marine mussels for both particulate and dissolved phases of the hepatotoxin microcystin, produced by the freshwater cyanobacterial genus Microcystis. We also extended our experimental investigation of particulate toxin to include oysters (Crassostrea sp.) grown commercially for aquaculture. California mussels (Mytilus californianus) and oysters were exposed to Microcystis and microcystin toxin for 24h at varying concentrations, and then were placed in constantly flowing seawater and sampled through time simulating riverine flushing events to the coastal ocean. Mussels exposed to particulate microcystin purged the toxin slowly, with toxin detectable for at least 8 weeks post-exposure and maximum toxin of 39.11ng/g after exposure to 26.65μg/L microcystins. Dissolved toxin was also taken up by California mussels, with maximum concentrations of 20.74ng/g after exposure to 7.74μg/L microcystin, but was purged more rapidly. Oysters also took up particulate toxin but purged it more quickly than mussels. Additionally, naturally occurring marine mussels collected from San Francisco Bay tested positive for high levels of microcystin toxin. These results suggest that ephemeral discharge of Microcystis or microcystin to estuaries and the coastal ocean accumulate in higher trophic levels for weeks to months following exposure.
authors.affiliation: Ocean Sciences Department, 1156 High Street, University of California, Santa Cruz, CA 95064, USA. Electronic address: cgibble@ucsc.edu.
authors.forename: Corinne M
authors.initials: CM
authors.lastname: Gibble
authors.affiliation: Ocean Sciences Department, 1156 High Street, University of California, Santa Cruz, CA 95064, USA; San Francisco Estuary Institute, 4911 Central Avenue, Richmond Ca 94804, USA; Native Environmental Science, Northwest Indian College, 2522 Kwina Rd, Bellingham, Wa, 98226, USA. Electronic address: mpeacock@nwic.edu.
authors.forename: Melissa B
authors.initials: MB
authors.lastname: Peacock
authors.affiliation: Ocean Sciences Department, 1156 High Street, University of California, Santa Cruz, CA 95064, USA. Electronic address: kudela@ucsc.edu.
authors.forename: Raphael M
authors.initials: RM
authors.lastname: Kudela
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000737:chemistry / Q000378:metabolism*; D005618:Fresh Water; D057097:Harmful Algal Bloom; D006801:Humans; D052998:Microcystins / Q000032:analysis / Q000378:metabolism*; D046931:Microcystis / Q000737:chemistry / Q000378:metabolism*; D010125:Ostreidae / Q000737:chemistry / Q000378:metabolism*; D012495:San Francisco; D057096:Shellfish Poisoning
chemical_list: D052998:Microcystins
keywords: Aquaculture; Microcystin; Microcystis aeruginosa; Mytilus californianus; Mytilus galloprovincialis; Mytilus trossulus