Water pollution damaging coral, report says
Analysis of pollution in Upolu’s water reveals high concentrations of elements damaging coral reefs already battling severe weather, bleaching and the worst effects of climate change.
High concentrations of the elements found in pesticides, metals from the fisheries industry and bacteria were found across 219 water samples from 29 locations around Upolu.
The findings were published in a report: 'Biosecurity of Upolu Fresh and Salt Environmental Water Resources'.
It was published jointly by New York University in New York and Abu Dhabi, the Ministry of Natural Resources and Environment (M.N.R.E.), and the National University of Samoa (N.U.S.), under a partnership facilitated by the United Nations Development Programme in Samoa.
Project leader and report co-author Dr. Gary Goldstein said the research outcomes reinforced his own conclusions about Samoa’s coral reefs from his experiences scuba-diving around the islands.
“It confirms everything I had seen scuba-diving,” he said.
“If [Samoa] can control herbicides, […] and E. coli you will see a regrowth in the lagoon."
The impact of herbicides and pesticides are among the most common problems that coral reefs around the world face. Research on the Great Barrier Reef in Queensland found 50 individual pesticide residues in the reef waterways, and that the highest concentrations were near intensive agriculture sites.
Their common elemental signatures are magnesium, bromine, and calcium, according to the report.
“Crop farming is a potential anthropogenic source because calcium is associated with herbicides and pesticides,” the report states.
“These chemicals have endocrine effects that may contribute to endemic obesity and they are also highly toxic to aquatic life.
“Mitigation efforts may include alternative pest management, such as biological controls.”
The researchers say 43 per cent of their seawater samples had above normal concentration levels of calcium, with some reaching concentration levels 20 per cent or more than normal levels.
Broadly bromine concentration showed below normal rates but that 36 per cent of samples had above normal concentration levels, with some as high as 12 per cent higher than normal.
A close look at magnesium showed 27 per cent of seawater samples had above-normal concentrations with some double the level typical in the sea.
Hotspots around Upolu for all three elements include Apia, the Siumu district, and Aleipata, with some more evenly distributed than others.
The water samples were studied with a Colilert 18 (IDEXX, US) testing kit, which is U.S. E.P.A. approved. It can detect a single pathogenic bacterial cell 100 millilitres of water.
They also took water samples of rainwater and bottled water. Using highly advanced mass spectrometry technology, they tested those samples at the Abu Dhabi and New York N.Y.U. campuses and at N.U.S.
While bromine is “essential” for some corals it has been broadly connected to damage of the ozone layer.
The researchers write that despite Samoa banning chlorofluorocarbons in the early 2000s, continued demand for products containing bromine for agriculture “requires a fresh discussion by Government.”
E. coli, a bacterial pathogen, was found in every single water sample the researchers tested and is concerning for not only human health but that of the reef, causing “stress and mortality” to certain coral organisms.
Another common element of concern was copper. In 67 per cent of samples copper registered above normal concentrations.
Around Siumu and Aleipata, samples registered double that of typical seawater levels of copper.
“In the marine environment the major anthropogenic sources of copper […] are antifouling paints used to coat ship hulls, buoys, other underwater surfaces, and from decking, pilings, and marine structures in which treated timbers are present,” the researchers write.
“Copper from antifouling paints - an apparently unavoidable feature of marine infrastructure - requires discussion by the Samoan government and the international community.
Magnesium, copper, calcium, and nickel are “ubiquitously or locally high” around the island and in high concentrations do lead to the decline of the reef.
The report had some “good news,” however.
“It is widely known that many heavy metals have no biological function and are harmful to life in even relatively moderate concentrations. Arsenic, cadmium, lead, and mercury is particularly egregious to life, and their distributions and concentrations are typically a result of industrial and human activity.
“However, these elements are in low concentrations on Upolu Island and are unlikely the cause of harm to the Samoan population or the environment. This is good news.”
The researchers recommend reducing herbicide and pesticide use through deploying alternative to biological control, and further investigating where the metal contaminations are coming from.
The wide-ranging research also found some elemental deficiencies in the seawater that could be contributing to coral reef decline.
The concentration levels of barium, strontium, and silicone were found wanting, and below normal levels typical for seawater.
While the researchers call for more research as to what could be causing the barium and strontium deficiencies, they have an idea of what could be happening to the silicon.
“Barium and strontium are essential for the growth and construction of stony corals, yet concentrations of these elements are very low around Upolu Island,” they write.
“These insufficiencies require investigation. Historically this may be investigated by sampling coral skeletons retrieved at known dates in the past […] There is no explanation for how these elements can be sequestered to such levels.
“Silicon is also essential for the construction of stony corals and for growth of important algal lineages such as diatoms; […] the contrast between high freshwater sources and low seawater concentrations suggests that excess inputs due to farming activities [and or] climate effects may be dumping silica from the rivers into the sea, which falls from surface waters to the seafloor and potentially obscuring the coral reef surface, thus decreasing the coral reefs' ability to thrive.”