Karenia mikimotoi

3.4.2 Effects on human health
There are no reports that K. mikimotoi has affected human health via seafood
poisoning. In reviewing the detrimental effects of G. aureolum (= K. mikimotoi) blooms
Mahoney et al. (1990) commented:
“The potential threats of G. aureolum blooms are not clear. An absence of documented
poisoning of humans associated with the species suggests that a serious public health
problem is unlikely”.
Despite the wide range of toxic effects of whole cells and isolated compounds only two
references in the literature to possible symptoms in humans caused by K. mikimotoi
have come to light. Blooms of Gyrodinium aureolum (= K. mikimotoi) occurred in New
Jersey (USA) coastal waters in the summers of 1984 and 1985 (Mahoney et al., 1990).
Cell concentrations in the bloom zones during the period of observation ranged from
1.5–36 x 10 6 cells.L -1 (geometric mean 3.4 x 10 6 cells.L -1 ). These adverse effects on
humans were noted:
“Symptoms in humans coincidental with bloom exposure to the bloom water included
nausea, sore throat, eye irritation and lung congestion (Marino, personal
communication). Complaints were primarily from individuals, such as lifeguards, who
had relatively extensive contact with the bloom water, or who were on the beaches for
long periods when it was present.”
The second reference was in the WHO guidelines (Anon., 2003) and is dealt with in
sect. 5.
An Environment Agency report from SW region, Cornwall division/area, dated 26 July
2002, recorded a relatively low density bloom at Whitsand Bay, Tregonhawke, in which
the major taxa were identified as Gyrodinium aureolum (11 x 10 3 cells.L -1 ) and
Pseudonitzschia spp. (55 x 10 3 cells.L -1 ) and noted on the report form against ‘Evidence
of toxic effect’, simply, “Yes, lifeguards falling ill.”
A protracted bloom of Karenia mikimotoi occurred in summer 2005 along the northern
half of the western Irish coastline. This bloom subsequently dissipated during the
month of July and was then succeeded by a bloom of the same
alga in the southwest in late July. The bloom was very intense and resulted in
discolouration of seawater and foaming in coastal embayments. Major mortalities of
benthic and pelagic marine organisms were observed and devastation of marine faunal
communities was reported and observed in a number locations. Deaths of
echinoderms, polychaetes and bivalve molluscs were observed in County Donegal and
Mayo, while farmed shellfish and hatchery raised juvenile bivalve spat suffered
significant mortalities along the Galway and Mayo coasts. Reports of dead fish and
crustaceans were received from Donegal, Galway, West Cork and Kerry.
The progress and effects of this exceptional bloom were observed and reported in
great detail (Silke et al., 2005). No adverse effects on humans were reported (J. Silke,
personal communication).
During the persistent and extensive bloom of K. mikimotoi that occurred in Scottish
waters in 2006, mortalities of marine fauna were attributed to the dinoflagellate, but
there were no reports of effects on human health (Davidson et al., 2007; K. Davidson,
personal communication).
16 A Literature review of the potential health effects of marine microalgae and macroalgae