initiated
with samples from the light exposure study. Previous
studies indicated that holding toxic cell-free filtrates
under refrigeration (4+18C) in the dark for several
days did not reduce hemolytic activity (Hagstro¨m and
Grane´li, 2005) or for 28 d did not influence the magnitude
of acute aquatic toxicity to P. promelas
(Urena-Boeck, 2008). In addition, toxicity was assessed
for filtrate that was stored at 4+18C in the dark after
harvesting the cells, which hereafter is called “lab dark
control”.