The effects of HSs in exposed organisms are by no means
unequivocal, since specific building blocks (mainly phenolic
and polyphenolic) ones, are suspected to be responsible for adverse
effects on the freshwater mollusks and are, on the other
hand, shown to have beneficial effects on the nematode Caenorhabditis
elegans Maupas. This organism actively migrated into
HS-rich environments, although these were clearly linked to
chemical stress (Menzel et al., 2005), yet with the benefit of lifespan
extension (Steinberg et al., 2007). These and subsequent
papers have shown that mild chemical stress induced by HSs
or their building blocks may ultimately not only extend lifespans,
but also increase resistance to multiple stressors, including
netting, high temperatures, or oxidative environments