Effects of harmful algal blooms on the physiological, immunity and resistance to environmental stress of bivalves: Special focus on paralytic shellfish poisoning and diarrhetic shellfish poisoning

Abstract

Bivalves are carriers of toxins produced by harmful algal blooms (HAB) species and were initially thought to be relatively unaffected. However, in recent years, increasing evidence has shown that bivalves are not only carriers of toxins produced by HAB species, but that HAB species and their secreted toxins can also alter the behaviour, physiology and cellular responses of bivalves, and even lead to the mortality of bivalves in severe cases. In addition, exposure of bivalves to HAB species and their secreted toxins may also negatively affect bivalve immunity and resistance to environmental changes. Despite the available of many relevant reports, the information is poorly organized and the link between HABs and bivalve robustness to environmental stressors is unclear. Therefore, understanding the potential impact of HAB species and their secreted toxins on bivalve aquaculture is critical. Here, we conduced a comprehensive scientific review of the potential effects of HAB species and their secreted toxins on the physiology and immunity of bivalves and their robustness to environmental stress. In general, scientific evidence suggests that exposure of bivalves to HAB species and their secreted toxins can hamper the immune system of bivalves, depending on the HAB and bivalve species and the natural environment of bivalves. This information helps to elucidate the current state of research and to determine topics for future studies on the effects of harmful algae blooms on bivalves.