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would be dependent on their different feeding habits (Hansson et al. 2007,
Hansson and Hylander 2009, Rautio et al. 2009, Ma et al. 2012).
The synthesis and accumulation of MAAs in response to UV radiation
have been simultaneously studied in both phytoplankton (dinofl agellates)
and their zooplankton grazer (copepods as
A. tonsa
) (Hylander and Jephson
2010). The results showed that the MAAs content increased approximately
four times in dinofl agellates exposed to UV compared to non-UV radiation
treatment. Moreover, the elevated MAAs level in dinofl agellates was
refl ected in the copepods, which accumulated more MAAs when exposed
to UV in comparison to the non-UV radiation treatment (Hylander and
Jephson 2010). However, protective compounds, like carotenoids, were not
accumulated by these marine copepods. This last fi nding differed from other
studies which showed that several species of freshwater copepods had the
ability to synthesize those pigments (Zagarese et al. 1997, Hansson 2000,
Hansson et al. 2007, Hylander et al. 2009). High concentrations of MAAs in
Antarctic krill have also been observed after feeding on algae that had been
grown under PAR-supplemented UV radiation (Newman et al. 2000).
Other mechanisms which organisms possess to prevent DNA damage
induced by UV-B or to repair it after UV-exposure, are photo-enzymatic
repair (PER; ''light repair'') and nucleotide excision repair (NER; ''dark
repair'') (Malloy et al. 1997). DNA repair mechanisms have been studied in
both freshwater and marine zooplankton (Zagarese et al. 1997, Grad et al.
2001, Browman et al. 2003, MacFadyen et al. 2004). Moreover, several studies
have demonstrated the ability of marine and freshwater crustaceans to repair
DNA damage via PER (Malloy et al. 1997, Zagarese et al. 1997). Additionally,
it has been reported that NER is found in all taxa and is not specifi c of UV-
induced DNA damage. Conversely, PER is specifi c to UV-induced DNA
damage and it is not present in all taxa (Sinha and Häder 2002). Although
several studies have demonstrated the deleterious effects of UV-A on aquatic
organisms (Williamson et al. 1997, Alonso Rodriguez et al. 2000, Browman et
al. 2000, Ban et al. 2007), the role of UV-A radiation is not as clearly defi ned
as the UV-B, and appears to be involved in the photo-repair of UV-B-induced
damage (Sutherland 1981, Sutherland et al. 1992).
Photorepairing of UV-B-induced damage to the DNA was found in both
Daphnia menucoensis
and the copepod
Metacyclops mendocinus
, which showed
a signifi cant decrease of mortality when exposed to visible radiation, PAR in
addition to UV-B (Gonçalves et al. 2002). A study on Antarctic zooplankton
has indicated that during periods of increased UV-B, the accumulation of
CPD levels was signifi cant and the DNA damage was largely repaired by
the photoenzymatic repair system (Mallloy et al. 1997). Another study
compared the vulnerability to UV-B radiation of three copepod species
(
Boeckella brevicaudata
,
Boeckella gibbosa
, and
Boeckella gracilipes
) and showed
that the potential photoprotection (i.e., resistance to UV-B in the absence
