and decreased growth and survival with increasing density in Penaeus
indicus (Emmerson and Andrews, 1981).
The survival of phyllosoma was not significantly different between
densities up to and including instar 9 when an acute high ozonation
event dramatically decreased survival of phyllosoma in the LD treatment.
Such mortality from high ozonation has previously been
described in S. verreauxi phyllosoma by Jensen et al. (2011). The highly
active oxidation by-products (OBP) produced by ozonation kill bacteria
and oxidise organic and inorganic compounds. At high levels
however, some OBPs such as bromine and bromate may disrupt the
normal moulting physiology of phyllosoma, which eventually results
in death (Jensen et al., 2011; Ritar et al., 2006). In the present study,
the LD treatment may have been more affected by the high ozonation
event than HD tanks due to lower biomass in the LD tanks resulting in
increased oxidation of phyllosoma. It is possible that the high ozonation
event may have compromised remaining phyllosoma in the LD
treatment and affected their subsequent performance in culture.
However, LD phyllosoma were larger and more advanced in regard
to instar compared to HD phyllosoma after instar 9. It is therefore unlikely
that the high ozonation event would have considerably
influenced treatment effects.