ABSTRACT
Marine biotoxins, produced as a secondary metabolite by certain phytoplankton species, can alter cellular processes of other organisms, from plankton to top predators. Phytoplankton cells, including those from harmful algal blooms (HABs) are the main nutritional source of zooplankton grazers and filter-feeding shellfish. The ability to metabolize and detoxify HAB toxins is critical to their survival, which most likely evolved to acquire resources that enable them to tolerate these toxins. Filter-feeding shellfish and zooplankton grazers, although susceptible to biotoxins, often act as potent toxin vectors in the marine ecosystem and not as victims. On the other hand, top predators at higher trophic levels that are less frequently exposed to HAB-toxins, may experience more severe effects. Accumulation, biotransformation, sequestration and transfer throughout the marine food web can affect different organisms causing a wide range of effects, from innocuous transient to sublethal or lethal effects, that in extreme cases generate events of mass mortality in higher vertebrates. Due to the global increase in frequency and intensity of HABs during the last decades, it is extremely important to understand the extent of the effects elicited by HAB toxins on marine organisms, therefore, an update on the effects of HAB toxins is needed. The present work reviews the currently available information regarding the effects of paralytic, amnesic, diarrhetic and neurotoxic shellfish toxins on marine organisms.
