Environmental Engineering Reference
In-Depth Information
G. mohua
. Eggs in both species were less sensitive to accumulated CPD and
thus resulted in less damage than hatched larvae (Brownam et al. 2003).
Evidence of the harmful effect of UV-B radiation was also observed on
early life stages of marine decapods and fi shes (Hovel and Morgan 1999,
Wübben 2000). The larval survival of three estuarine crab species (
Uca
pugnax
,
Sesarma reticulatum
and
Dyspanopeus say
) decreased by the exposure
of UV-B radiation (Hovel and Morgan 1999). Short-experiments on
Crangon
crangon
demonstrated that moderate levels of UV-B caused lethal effects
on zoea I. Long-term exposure (0-10 days) of this crab to UV-B radiation
produced no signifi cant moulting and only 10% of these larvae moulted
from zoea I to zoea II (Wübben 2000). Lethal effects of UV-B on larvae and
embryos of the fi sh species
Engraulis mordax
and
Scomber japonicus
were
also reported by Hunter et al. (1979).
In the Southern Hemisphere, studies on the effect of UV radiation and
its consequences on zooplankton were performed. Several studies have been
carried out on freshwater zooplankton reporting lethal effects and photo-
repair activity (Gonçalves et al. 2002, 2007, 2010). Nevertheless, research on
marine southern zooplankton concerning UV-B impact needs to be done.
Indirect effects of UV radiation on zooplankton
Most of the studies focus on the direct effects of UV-B radiation in
specifi c organisms. Recently, a few studies in both marine and freshwater
environments have examined the indirect effects of UV radiation and how
long exposure to low-level UV induces changes in food web interactions
(Hessen et al. 1997, Browman et al. 2000, 2003, Gonçalves et al. 2010,
Williamson et al. 2010) (Fig. 2).
Indirect effects produced by UV exposure are related to changes in
phytoplankton cell wall and size and species composition that affect the
ingestion and digestion of zooplankton (Mostajir et al. 1999, De Langer and
Lürling 2003, Grem et al. 2004). Changes on food quality as the increase
of carbohydrates and the decrease of fatty acids due to the phytoplankton
exposure to UV-B (Arts and Rai 1997, Goes et al. 1997), caused negative
effects on growth and reproduction rates of herbivorous zooplankton (De
Lange and Van Donk 1997, Scott et al. 1999). Increased mortality, decreased
growth and decreased overall fecundity were observed in an experimental
study on the cladoceran
Daphnia pulex
feeding on UV-B irradiated algae
(Scott et al. 1999).
The reduction of the total lipid content of some microalgae including
the PUFAs is another consequence of the exposure to UV-B radiation,
even at low dose rates (Goes et al. 1994, De Lange and Van Donk 1997).
Zooplankton and fi sh larvae cannot synthesize those fatty acids and they
must be obtained from their prey (Tuner and Rooker 2005). The reduction
