NOAA teams up with university researchers to show how warmer temperatures will increase toxic algae blooms and exposure to other waterborne pathogens
Dust blowing off the Sahara into the Atlantic is clearly visible in the NASA satellite image. Research suggests rising concentrations of iron from the dust will increase blooms of toxic algae.
By Summit Voice
SUMMIT COUNTY — At the same time that ecologists and forest health researchers discussed some of their latest global warming research at a symposium in Aspen, Colorado, scientists at the annual meeting of the American Association for the Advancement of Science unveiled studies showing how rising temperatures could result in new human health risks within the next 30 years.
“With 2010 the wettest year on record and third warmest for sea surface temperatures, NOAA and our partners are working to uncover how a changing climate can affect our health and our prosperity,” said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “These studies and others like it will better equip officials with the necessary information and tools they need to prepare for and prevent risks associated with changing oceans and coasts.”
In several studies funded by NOAA’s Oceans and Human Health Initiative, findings shed light on how complex interactions and climate change alterations in sea, land and sky make ocean and freshwater environments more susceptible to toxic algal blooms and proliferation of harmful microbes and bacteria.
Climate change could prolong toxic algal outbreaks by 2040 or sooner, said Stephanie Moore, Ph.D., with NOAA’s West Coast Center for Oceans and Human Health and her partners at the University of Washington. Using cutting-edge technologies to model future ocean and weather patterns, Moore predicted longer seasons of harmful algal bloom outbreaks in Washington State’s Puget Sound.
The team looked at blooms of Alexandrium catenella, more commonly known as “red tide,” which produces saxitoxin, a poison that can accumulate in shellfish. If consumed by humans, it can cause gastrointestinal and neurological symptoms including vomiting and muscle paralysis or even death in extreme cases.
In addition to potential health impacts, longer periods of red tide could close down the shellfish industry, valued about $108 million in Washington state.
“Changes in the harmful algal bloom season appear to be imminent and we expect a significant increase in Puget Sound and similar at-risk environments within 30 years, possibly by the next decade,” said Moore. “Our projections indicate that by the end of the 21st century, blooms may begin up to two months earlier in the year and persist for one month later compared to the present-day time period of July to October.”
Natural climate variability also plays a role in the length of the bloom season from one year to the next. Thus, in any single year, the change in bloom season could be more or less severe than implied by the long-term warming trend from climate change.
Moore and the research team said the extended lead time offered by these projections will allow managers to plan mitigation and sharpen their targets for monitoring. Knowing what to expect could help the agency open and close individual shellfish beds instead of issuing a blanket closure for a larger swath of coast. The same model can be applied to other coastal areas around the world increasingly affected by harmful algal blooms and improve protection of human health against toxic outbreaks.
Some climate change scenarios predict increasing desertification, and the resulting increase in atmospheric dust could fuel the presence of harmful bacteria in the ocean and seafood, according to University of Georgia researchers.
Desert dust in the atmosphere is considered one of the main contributors of iron in the ocean. Concentrations have already increased during the last 30 years, More iron in seawater significantly stimulates growth and persistence of Vibrios, a group of ocean bacteria that occur worldwide and can cause gastroenteritis and infectious diseases in humans.
“Within 24 hours of mixing weathered desert dust from Morocco with seawater samples, we saw a 10-1000-fold growth in Vibrios, including one strain that could cause eye, ear, and open wound infections, and another strain that could cause cholera ,” said Lipp. “Our next round of experiments will examine the response of the strains associated with seafood-related infections.”
Since 1996 Vibrio cases have jumped 85 percent in the United States based on reports that primarily track seafood-illnesses. It is possible this additional input of iron, along with rising sea surface temperatures, will affect these bacterial populations and may help to explain both current and future increases in human illnesses from exposure to contaminated seafood and seawater.
More rainfall and sub-standard sewage systems could also affect water quality in Great Lakes region, freshwater researchers with the University of Wisconsin concluded after studying climate models predicting increases in spring rains. More precipitation could cause old sewers to back up, releasing disease-causing bacteria, viruses and protozoa into drinking water and onto beaches.
In the past 10 years there have been more severe storms that trigger overflows. While there is some question whether this is due to natural variability or to climate change, these events provide another example as to how vulnerable urban areas are to climate. As little as 1.7 inches of rain in 24 hours can cause an overflow in spring and the combination of increased temperatures — changing snowfall to rainfall and increased precipitation — can act synergistically to magnify the impact.
The researchers showed that, under worst case scenarios, there could be an average 20 percent increase in volume of overflows, and they expect the overflows to last longer. In Milwaukee, infrastructure investments have reduced sewage overflows to an average of three times per year, but other cities around the Great Lakes still experience overflows up to 40 times per year.
“Hundreds of millions of dollars are spent on urban infrastructure, and these investments need to be directed to problems that have the largest impact on our water quality,” said McLellan. “Our research can shed light on this dilemma for cities with aging sewer systems throughout the Great Lakes and even around the world.”
“Understanding climate change on a local level and what it means to county beach managers or water quality safety officers has been a struggle,” said Juli Trtanj, director of NOAA’s Oceans and Human Health Initiative and co-author of the interagency report A Human Health Perspective on Climate Change. “These new studies and models enable managers to better cope and prepare for real and anticipated changes in their cities, and keep their citizens, seafood and economy safe.”
