A couple days ago we visited the Marine Research Center and looked at the clam hatchery. Charlie Waters, a specialist regarding clams, gave us a thorough explanation about the reasons for low spawning success and the purpose of his research. Charlie explained that low reproduction was due to the distance between individuals. Each species of clam are too far away from each other to spawn, those species include; genera tridacnidae maxima, tridacnidae gigas, tridacnidae derasa and the genera hippopus.
In the 20th century, many areas in the Cook Islands relied on clams as a food source, and therefore many clams were removed from the population overtime causing a decrease in the abundance of clams. Clams are significant to the reefs as they are coral reef filter feeders and food for the octopus as well as other marine life. When they are spread to thin, the cannot reproduce. This could easily offset the balance of marine environments.
With the current ciguatera research in place my assumption is that with the lack of clams, increase in tourism, the previous banana exportation, and chemical runoff the reefs and lagoons are less viable to fighting off the neurotoxin. It may also be that the potentially ciguatoxic coral is spread when large storms come through, causing unsettled ocean water and debris.