Characterization of paralytic shellfish toxins in seawater and sardines (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) during blooms of <Emphasis Type="Italic">Gymnodinium catenatum</Emphasis> |
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Authors: | Pedro Reis Costa Maria João Botelho Kathi A Lefebvre |
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Institution: | 1.IPIMAR - National Institute for Biological Resources,Lisbon,Portugal;2.NOAA Fisheries,Northwest Fisheries Science Center, Marine Biotoxins Program,Seattle,USA |
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Abstract: | The re-emergence of Gymnodinum catenatum blooms after a 10 year hiatus of absence initiated the present investigation. This study aims to evaluate the exposure of
small pelagic fishes to paralytic shellfish toxins (PST) during blooms of G. catenatum. Sardines (Sardina pilchardus) were selected as a representative fish species. In order to assess toxin availability to fish, both intracellular PSTs (toxin
retained within the algal cells) and extracellular PSTs (toxin found in seawater outside algal cells) were quantified, as
well as toxin levels within three fish tissue matrices (viscera, muscle and brain). During the study period, the highest cell
densities of G. catenatum reached 2.5 × 104 cells l−1 and intracellular PST levels ranged from 3.4 to 398 ng STXeq l−1 as detected via an enzyme linked immunosorbent assay (ELISA). Measurable extracellular PSTs were also detected in seawater
(0.2–1.1 μg STXeq l−1) for the first time in Atlantic waters. The PST profile in G. catenatum was determined via high performance liquid chromatography with fluorescence detection (HPLC-FLD) and consisted mostly of
sulfocarbamoyl (C1+2, B1) and decarbamoyl (dcSTX, dcGTX2+3, dcNEO) toxins. The observed profile was similar to that reported
previously in G. catenatum blooms in this region before the 10-year hiatus. Sardines, planktivorous fish that ingest a large number of phytoplankton
cells, were found to contain PSTs in the viscera, reaching a maximum of 531 μg STXeq kg−1. PSTs were not detected in corresponding muscle or brain tissues. The PST profile characterized in sardine samples consisted
of the same sulfocarbamoyl and decarbamoyl toxins found in the algal prey with minor differences in relative abundance of
each toxin. Overall, the data suggest that significant biotransformation of PSTs does not occur in sardines. Therefore, planktivorous
fish may be a good tracer for the occurrence of offshore G. catenatum blooms and the associated PSTs produced by these algae. |
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