Karenia mikimotoi

2.3.7 Other organisms associated with Phaeocystis colonies
There are reports of other organisms associated with Phaeocystis colonies and foam
and it is possible that these could give rise to irritation by dermal contact.
Verity et al. (2007) highlight the work of Sahzin et al. (2007) who enumerated
organisms associated with Phaeocystis pouchetii colonies growing in mesocosms in
Norway and in blooms of P. globosa in the English Channel.
The surface of large ( >250 µm) P. pouchetii colonies were populated with Pseudonitzschia
cf. granii var. curvata, which did not exceed 40 cells per colony, and to a
lesser extent by other phytoplankton and protists. Pseudo-nitzschia delicatissima
colonized the surface of large (>100 µm) Phaeocystis globosa colonies from the
English Channel. The abundance of these diatoms reached 130 cells per colony and
formed up to 70% of the total carbon associated with Phaeocystis cells during late
bloom stages and it was suggested that the diatoms were able to utilize the
polysaccharides in the colony matrix for growth.
Armonies (1989) found that Phaeocystis foam in the Dutch Wadden Sea contained
significant numbers of harpacticoid copepods, which are normally found as meiofauna
in the upper sediment layers. It was not clear whether they had been passively
entrapped or actively migrated. It is possible but unlikely that these could act as
allergens.
2.3.8 Effects on human health
Phaeocystis is not generally considered a hazard to health: “These blooms are not
directly detrimental to human health as are other toxic blooming algae” - a quotation
from a Belgian scientific report (Anon., 2002a). References to any symptoms caused
by Phaeocystis foam appear to be rare and anecdotal, for example, this statement from
the Friends of the Earth Marinet website: www.marinet.org.uk/glossary.html
“Children love to play in it. But beware - it can produce an irritating rash in allergic
youngsters.”
The national report for the Netherlands regarding HAB incidents in 2001, submitted to
the ICES-IOC Working Group on Harmful Algal Bloom Dynamics (Anon., 2002b)
includes this statement: “In August, swimmers at the ‘Hoek van Holland’ beach (in the
Rhine outflow) reported skin irritations. Microscopic counts of a sample collected at this
time indicated a Phaeocystis concentration of 4.0 x 10 9 cells.L -1 .”
2.4 Emiliania huxleyi
This cosmopolitan alga often forms massive blooms in many of the world’s seas and
oceans, including the waters around the UK, producing spectacular satellite images
due to the optical properties of its calcareous scales (coccoliths). It produces dimethyl
sulphide (see Malin et al., 1993) as outlined in 2.3.2.
Blooms are reported to be non-toxic (Jahnke, 1992) and the alga has been shown to
be non-toxic in the Artemia brine-shrimp lethality bioassay (Rhodes et al., 1995, cited in
Houdan et al., 2004). There appear be no reports in the scientific literature regarding
known toxicity or other deleterious effects on humans via aspiration, dermal contact or
aerosols.
10 A Literature review of the potential health effects of marine microalgae and macroalgae