It’s no secret that the mangroves in South Sound have been sluggish to recover after Hurricane Ivan in September 2004. In pursuit of the reason for the slow growth, an International College of the Cayman Islands professor said he has discovered in the sound high levels of a common pool chemical that does not naturally occur in the marine environment.
However, local environmental and water officials say that claim is unlikely and question the methods Professor Anthony Husemann used to observe that the sound has concentrations of cyanuric acid up to 10 times as great as that found in a swimming pool.
Cyanuric acid is typically put in pool water in order to stabilise the level of chlorine, which tends to evaporate rapidly in sunlight without the added conditioner.
Mr. Husemann, director of graduate studies at the International College of the Cayman Islands, said he observed concentrations of the acid at between 30 to 500 parts per million in the sound, compared to 30 to 50 parts per million in a pool, and 100 parts per million in the seawater off Bodden Town.
He tested the water samples using a common pool testing kit.
“It does not belong out in South Sound or Pease Bay,” Mr. Huseman said of the chemical. “No-one dumped it on purpose. If it’s out there, it’s an accident.” He theorised that the acid could have come from people draining their pools into their waste-water systems, the content from which finds its way into the sea.
“I’m not sure if you can use a pool kit in marine water. There is a different chemistry completely,” said Tim Austin, assistant director of the Cayman Islands Department of Environment.
Mr. Austin said the prevailing thought as to why mangroves in the sound are regenerating very slowly, compared to the quick recovery after the sound was dredged some 40 years ago, is that the construction of South Sound Road cut off the natural seepage of nutrient-rich marsh water from the land into the sound.
“The general theory is they aren’t growing there very well because they are nutrient-limited, not that they are being poisoned,” Mr. Austin said.
Currently, much of the storm runoff from the land is discharged into the sound from a single culvert. “There will be a high volume of fresh water flushing out, almost like a river,” Mr. Austin said, adding that is “not a natural process”.
Water Authority Deputy Director Tom van Zanten also expressed doubts as to the accuracy of Mr. Husemann’s measurements, and described the idea of there being cyanuric acid contamination in the sound as “far-fetched”.
He said, “You should not use a pool-testing kit to test seawater.”
Contacted by the Caymanian Compass, scientists at the Central Caribbean Marine Institute and in California said they had never heard of someone using a pool testing kit to attempt to measure contaminants in ocean water.
One researcher noted that, according to Mr. Husemann’s findings, the pH of water in the sound was greater than 8.4, which is on the high end of what you would normally expect. Conversely, if there was a significant concentration of an acid in the water, then you would expect the pH to be relatively low.