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Presence of Alexandrium catenella and paralytic shellfish toxins in finfish, shellfish and rock crabs in Monterey Bay, California, USA.

ABSTRACT: The central California coast is a highly productive, biodiverse region that is frequently affected by the toxin-producing dinoflagellate Alexandrium catenella. Despite the consistent presence of A. catenella along our coast, very little is known about the movement of its toxins through local marine food webs. In the present study, we investigated 13 species of commercial finfish and rock crabs harvested in Monterey Bay, California for the presence of paralytic shellfish toxins (PSTs) and compared them to the presence of A. catenella and PSTs in sentinel shellfish over a 3-year period. Between 2003 and 2005, A. catenella was noted in 55% of surface water samples (n = 307) and reached a maximum concentration of 17,387 cells L^-1 at our nearshore site in Monterey Bay. Peak cell densities occurred in the month of July and were associated with elevated shellfish toxicity in the summers of 2004 and 2005. When A. catenella was present, particulate PSTs were detected 71% of the time and reached a maximum concentration of 962 ng STXeq L^-1. Of the 13 species tested, we frequently detected PSTs in Pacific sardines (Sardinops sagax; maximum 250 μg STXeq 100 g^-1), northern anchovies (Engraulis mordax; maximum 23.2 μg STXeq 100 g^-1), brown rock crabs (Cancer antennarius; maximum 49.3 μg STXeq 100 g^-1) and red rock crabs (C. productus; 23.8 μg STXeq 100 g^-1). PSTs were also present in one sample of Pacific herring (Clupea pallas; 13.3 μg STXeq 100 g^-1) and one sample of English sole (Pleuronectes vetulus; 4.5 μg STXeq 100 g^-1), and not detected in seven other species of flatfish tested. The presence of PSTs in several of these organisms reveals that toxins produced by A. catenella are more prevalent in California food webs than previously thought and also indicates potential routes of toxin transfer to higher trophic levels.

SUBMITTER: Jester RJ

PROVIDER: S-EPMC7477862 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:In late February 2016, a harmful algal bloom (HAB) of Alexandrium catenella was detected in southern Chiloé, leading to the banning of shellfish harvesting in an extended geographical area (~500 km). On April 24, 2016, this bloom produced a massive beaching (an accumulation on the beach surface of dead or impaired organisms which were drifted ashore) of surf clams Mesodesma donacium in Cucao Bay, Chiloé. To determine the effect of paralytic shellfish poisoning (PSP) toxins in M. donacium, samples were taken from Cucao during the third massive beaching detected on May 3, 2016. Whole tissue toxicity evidence a high interindividual variability with values which ranged from 1008 to 8763 μg STX eq 100 g-1 and with a toxin profile dominated by GTX3, GTX1, GTX2, GTX4, and neoSTX. Individuals were dissected into digestive gland (DG), foot (FT), adductor muscle (MU), and other body fractions (OBF), and histopathological and toxin analyses were carried out on the obtained fractions. Some pathological conditions were observed in gill and digestive gland of 40⁻50% of the individuals that correspond to hemocyte aggregation and haemocytic infiltration, respectively. The most toxic tissue was DG (2221 μg STX eq 100 g-1), followed by OBF (710 μg STX eq 100 g-1), FT (297 μg STX eq 100 g-1), and MU (314 μg STX eq 100 g-1). The observed surf clam mortality seems to have been mainly due to the desiccation caused by the incapability of the clams to burrow. Considering the available information of the monitoring program and taking into account that this episode was the first detected along the open coast of the Pacific Ocean in southern Chiloé, it is very likely that the M. donacium population from Cucao Bay has not had a recurrent exposition to A. catenella and, consequently, that it has not been subjected to high selective pressure for PSP resistance. However, more research is needed to determine the effects of PSP toxins on behavioral and physiological responses, nerve sensitivity, and genetic/molecular basis for the resistance or sensitivity of M. donacium.

Project description:Species of the dinophyte genus Alexandrium are widely distributed and are notorious bloom formers and producers of various potent phycotoxins. The species Alexandrium taylorii is known to form recurrent and dense blooms in the Mediterranean, but its toxin production potential is poorly studied. Here we investigated toxin production potential of a Mediterranean A. taylorii clonal strain by combining state-of-the-art screening for various toxins known to be produced within Alexandrium with a sound morphological and molecular designation of the studied strain. As shown by a detailed thecal plate analysis, morphology of the A. taylorii strain AY7T from the Adriatic Sea conformed with the original species description. Moreover, newly obtained Large Subunit (LSU) and Internal Transcribed Spacers (ITS) rDNA sequences perfectly matched with the majority of other Mediterranean A. taylorii strains from the databases. Based on both ion pair chromatography coupled to post-column derivatization and fluorescence detection (LC-FLD) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis it is shown that A. taylorii AY7T does not produce paralytic shellfish toxins (PST) above a detection limit of ca. 1 fg cell-1, and also lacks any traces of spirolides and gymnodimines. The strain caused cell lysis of protistan species due to poorly characterized lytic compounds, with a density of 185 cells mL-1 causing 50% cell lysis of cryptophyte bioassay target cells (EC50). As shown here for the first time A. taylorii AY7T produced goniodomin A (GDA) at a cellular level of 11.7 pg cell-1. This first report of goniodomin (GD) production of A. taylorii supports the close evolutionary relationship of A. taylorii to other identified GD-producing Alexandrium species. As GD have been causatively linked to fish kills, future studies of Mediterranean A. taylorii blooms should include analysis of GD and should draw attention to potential links to fish kills or other environmental damage.

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Presence of Alexandrium catenella and paralytic shellfish toxins in finfish, shellfish and rock crabs in Monterey Bay, California, USA.

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