Summary: Australia is blessed with a great diversity of unique species in its fresh waters and in the marine environment around its coast. There is evidence that human and natural events are impacting on these species. Such impacts are associated with various agricultural, industrial, and domestic practices and with natural and anthropogenically driven climate change. Among the species most affected are those living in aquatic and marine environments. Some of these, such as cyanobacteria and dinoflagellates, have the potential for toxicity. Linked to this, there is the potential benefit of harnessing the pharmacologic potential of these toxins.