Palytoxin (PLTX) may be a complex marine toxin synthesized by the soft coral Palythoa toxica and by species of the benthic dinoflagellate Ostreopsis spp. The toxin binds to the active Na, K-ATPase pump within the cellular membrane. This interaction changes the protein conformation and produces a non-specific cation channel. The cultures were grown under different conditions to study the optimal parameters to grow and to produce toxins. Serious difficulties were found to quantify the number of cells at the end of the exponential phase. In order to avoid any toxin loss, the load of the pellet obtained after careful filtration was used as reliable parameter to calculate the expansion of the cultures. Also, this parameter was used to refer the results of toxin concentration. In addition, the toxicity of the cultures was measured by mouse bioassay. In this context, the results from the spring season add mechanistic information to the general understanding of the seasonal variability of global climate change effects. They suggest that the relative importance of the underlying direct and indirect effective pathways of warming and therefore the overall effect on the balance between production and consumption are influenced by the trophic state of the system, which in temperate regions is related to season.