Algal blooms and toxins in Oceania
Mark Skinner
It should be of great concern that as Oceania countries consider different forms of mining (e.g. deep sea mining) and the Australian mining industry expands, ports are built in vulnerable ecosystems.
A large number of ships travelling from Asia will change their boat ballast and cause harmful algal blooms (HABs) to spread, impacting habitats that may have no natural predators to these toxic bio-invasives. For example Pyrodinium, a microalgae which produces paralytic shellfish toxin, has killed over 150 people in the Philippines and is responsible for marine fauna kills in the Solomon Islands.
The most well-known of the HABs are red tides. One example was recently witnessed on Sydney's beaches − Noctulica, impacting sea life biodiversity with high concentrations of ammonia. On the east coast of Tasmania, and in Botany Bay, Alexandrium, which produces the shellfish poisoning toxin saitotoxin, has closed the shellfish beds. There are also HABs related to seafood poisonings of humans, including many types of shellfish poisoning, and ciguatera fish poisoning.
The impact of toxic HABs on marine tropical ecosystem health remains understudied. There have been marine fauna (including fish, turtles, seabirds, seals, cetaceans) kills from the temperate coasts of North America to lagoons of the tropical Solomon Islands, which have been directly and indirectly attributed to HABs.
A danger overlooked by the coral reef scientists are benthic toxic microalgae which cause fish to be poisonous, known as ciguatera [1]. For example Gambierdiscus produces Ciguatoxin, a very potent biotoxin that has produced an epidemic in the Pacific Island nations. Some of these microalgae are already upon the Great Barrier Reef − for example Ostreopsis produces a palytoxin, possibly responsible for killing sea turtles.
Seventeen nations of the Pacific have reported being impacted with ciguatera fish poisoning, due to coral reef degradation and consequential benthic HABs, including toxic cyanobacteria, to the extent that one in four islanders have been poisoned in recent times (approx. 500,000 in 30 years) and also capable of travelling in the ballast water from their points of origin. The sub-lethal ciguatera impacts upon humans, due to the benthic HAB toxins, includes oxadaic acid − a tumor promoter that has barely been studied.
Even the dredging of estuaries can provide more habitats capable of supporting HABs, through suspension of bacteria, minerals and nutrients. The impact of exotic HABs arriving in boat ballast and their ability to move further afield, spreading via currents and storms alongside coastlines, should be seen as an unforeseen danger which could lead to the ruination of our natural marine biota heritage, not accustomed to such HABs.
Of major concern in this scenario, the Boat Ballast Convention of 2004 as created by the International Maritime Organisation has not been ratified; so what safeguards are in place to prevent toxic HABs travelling between oceans in the boat ballast of mining cargo vessels? The use of proven safeguards to stop HABs surviving in boat ballast and the ratification of the 2004 Boat Ballast Convention also needs to be addressed. An eco-catastrophe of the tropical coral reef environment, due to HABs, is on the verge of occurring, with ciguatera as a bio-indicator.
[1] See Mark P. Skinner et al., 2011, 'Ciguatera Fish Poisoning in the Pacific Islands (1998 to 2008)', PLoS Negl Trop Dis, 5(12)
www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0001416
Dr Mark Skinner has been studying ciguatera since 1993 and after completing a M.Sc.(Hons) in Ecotoxicology from UTS, has completed his PhD in this field at the UQ.