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What causes golden algal blooms?
Like other potentially toxic algal species, under optimal environmental conditions, golden algae can bloom (large scale outgrowths) and eliminate most or all other algal species from a system. Such occurrences are known collectively as Harmful Algal Blooms. Massive algal blooms, regardless of species or whether or not they produce toxins, are not common in natural, pristine ecosystems, but typically arise as a result of anthropogenically-induced increases in plant nutrients, primarily phosphorous and nitrogen.
Massive algal blooms, regardless of species or whether or not they produce toxins, are not common in natural, pristine ecosystems, but typically arise as a result of anthropogenically-induced increases in plant nutrients, primarily phosphorous and nitrogen. Although there are natural sources of nutrients, such as leeching of phosphates from soil and rocks, dust deposition, excess nutrients are introduced to lakes from sewage, industrial effluents, and agricultural runoff. When an algal bloom is near or at its peak growth, further growth becomes nutrient (most often phosphorous) limited. At this stage any algae which can successfully overcome such nutrient-limiting conditions will have the competitive edge. The strategy of golden algae is to produce allelopathic substances (toxins to inhibit or kill other competing algae), thus increasing the amount of nutrients in the water available for itself. Such toxins also induce changes in the plankton community structure, not only by inhibiting and killing other members of the phytoplankton, but also by inhibiting potential grazers by interfering with their reproduction and life cycles. Moreover, algal toxins can be poisonous to animals higher in the food web as well. This has been well documented by numerous cases of blue-green algal poisoning in livestock and humans. In the case of golden algae, toxicity appears to be limited to gill-breathing organisms like fish and mollusks.
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