Marine zooplankton can accumulate and retain dinoflagellate toxins and cause fish kills

Abstract

n dinoflagellate 1 Oceans, Herbivorous marine zooplankton were fed cultures of the toxic dinoflagellate Gonyaulux excauata, and the removal of Gonyaulux and the toxin content of the zooplankters were measured. The copepod Acartia clausii and barnacle nauplii (Balanus sp.) rapidly ingested G. excavata and accumulated maximum levels of its toxins within 6 h, with no apparent adverse effect. Toxins were retained in the zooplankters for at least several days past the time of gut clearance of particulate material, suggesting storage of toxins. Results, coupled with evidence from field studies and fish-kill events, indicate that there is a fairly general mechanism for the transmission of G. excavata toxins through herbivorous zooplankton to animals at a higher trophic level and that G. excavata toxins can reach sufficient levels in zooplankters to cause fish kills.

Zooplankton as a potential vector of diarrhetic shellfish poisoning toxins through the food web

“…However, a higher agreement was found in the case of the interaction between A. clausi and Alexandrium tamarense. Several studies have shown that this copepod species grazed on this toxic dinoflagellate (White 1981, Turner & Anderson 1983, Ives 1985, 1987. Turner et al (1997) suggested that the lack of co-evolutionary experience in feeding toxic cells could be the reason for the discrepancy in some experimental results.…”

“…Zooplankton might thus transmit toxins to their predators. Mass mortalities of pelagic fishes such as herring and mackerel (White 1980, 1981, Beaulieu et al 1996, Montoya et al 1996, Castonguay et al 1997) and marine mammals (Geraci et al 1991, Landsberg & Stidinger 1998 exposed to toxic dinoflagellate or diatom blooms, and accumulation of PSP toxins in anchovies (Montoya et al 1998), have been reported. In all these cases, zooplankton presumably acted as a link between toxic phytoplankton and higher trophic levels.…”

“…Field observations during blooms of dinoflagellates that produce paralytic shellfish poisoning (PSP) toxins (White 1981, Hayashi et al 1982, and laboratory experiments with cultures of Alexandrium spp., have shown that zooplankton can ingest these toxins and accumulate them in their somatic tissues (Boyer et al 1985, Turriff et al 1995, Teegarden & Cembella 1996. Zooplankton might thus transmit toxins to their predators.…”

Repression of fecundity in the neritic copepod Acartia clausi exposed to the toxic dinoflagellate Alexandrium lusitanicum:relationship between feeding and egg production

“…Therefore they could interfere with the control of enzyme secretion or active uptake of digested food compounds and consequently reduce the nutritional gain from ingested food. Alternatively, internal sequestering or detoxification of ingested toxins which may be an adaption of copepods (White 1981, Ives 1987 could cause an enhanced energy expenditure. Recovery of the physiological impairment after 3 d of incubation and the survival rates unaffected by Alexandrium lusitanicum indicate that females were able to cope with ingested toxins.…”

“…On the other hand, Teegarden & Cembella (1996) found similar high feeding rates in 2 copepod species exposed to toxic and nontoxic Alexandnum strains. Regardless of the level of feeding on toxic algae, the accumulation of saxitoxins in zooplankton upon exposure to toxic algae and the importance of transfer of toxins by zooplankton in the food web are well documented (White 1981, Turriff et al 1995, Teegarden & Cembella 1996.…”