LOX-induced lipid peroxidation mechanism responsible for the detrimental effect of marine diatoms on zooplankton grazers

Some marine diatoms negatively affect reproduction of dominant zooplankton grazers such as copepods thus compromising the transfer of energy through the marine food chains. In this paper, the metabolic mechanism leading to diatom-induced toxicity is investigated in three bloom-forming microalgae. We show that copepod dysfunctions can be induced by highly reactive oxygen species (hROS) and a blended mixture of diatom products, including fatty acid hydroperoxides (FAHs), which display teratogenic and pro-apoptotic properties. The process is triggered by early onset of lipoxygenase activities that elicit synthesis of species-specific products, the basic structures of which were established (1-20), and boost oxidative stress by massive lipid peroxidation. Our study may account for past laboratory and field results showing how diatoms damage zooplankton grazers even in the absence of polyunsaturated aldehydes, a class of molecules that has been formerly suggested to mediate the toxic activity of diatoms on copepods.