Dissolved saxitoxin causes transient inhibition of sensorimotor function in larval Pacific herring (<Emphasis Type="Italic">Clupea harengus pallasi</Emphasis>) |
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Authors: | Email author" target="_blank">Kathi?A?LefebvreEmail author Nancy?E?Elder Paul?K?Hershberger Vera?L?Trainer Carla?M?Stehr Nathaniel?L?Scholz |
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Institution: | (1) Environmental Conservation Division, Northwest Fisheries Science Center, NOAA-Fisheries, 2725 Montlake Blvd. East, Seattle, WA 98112, USA;(2) Marrowstone Marine Station, USGS, Biological Resources Discipline, 616 Marrowstone Point Road, Nordland, WA 98358, USA |
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Abstract: | Herring (Clupea harengus pallasi) spawning sites in Puget Sound, Washington overlap spatially and temporally with blooms of Alexandrium catenella, a toxic dinoflagellate species responsible for paralytic shellfish poisoning. Consequently, newly hatched herring larvae
may be regularly exposed to the suite of dissolved paralytic shellfish toxins that are released into the water column from
toxic cells during blooms. To date, virtually nothing is known about the impacts of these neurotoxins on early developmental
stages of marine fish. In the present study, herring larvae at three ages, 0 days post hatch (dph), 4 dph, and 11 dph, were
exposed to dissolved saxitoxin (STX) in 24-h and multi-day exposures. All larvae were examined for sensorimotor function (i.e.
spontaneous swimming behavior and touch response). Significant reductions in spontaneous and touch-activated swimming behavior
occurred within 1 h of exposure. EC50s at 1 h of exposure were 1,500, 840, and 700 μg STX equiv. l−1 for larvae introduced to STX at 0, 4, and 11 dph, respectively. This progressive age-specific increase in STX-induced paralysis
suggests that older larvae were more sensitive to the toxin than younger larvae. Interestingly, herring larvae at all ages
exhibited a significant degree of neurobehavioral recovery within 4–24 h of continuous exposure relative to the 1-h time point.
This recovery of normal motor behaviors was not observed in previous studies with freshwater zebrafish (Danio rerio) larvae under the same continuous exposure conditions, suggesting that an adaptive detoxification or toxin sequestration
mechanism may have evolved in some species of marine fish larvae. Our data reveal that (1) dissolved STX is bioavailable to
marine finfish larvae, (2) the toxin is a paralytic agent with potencies that differ between developmental stages, and (3)
STX-induced sensorimotor inhibition occurs rapidly but is transient in marine larvae. Collectively, these results suggest
that dissolved algal toxins may have important sublethal effects on marine fish populations. |
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