Oceans, Great Lakes and Human Health
- Researchers identified genes in organisms called diatoms that are important for producing the neurotoxin domoic acid. This information will help improve toxin monitoring during harmful algal blooms in oceans.
- Scientists discovered that symbiotic bacteria are responsible for the naturally produced polybrominated diphenyl ether (PBDE) toxins found in certain marine sponges. The researchers also identified the genes involved in PBDE production, which may help scientists find and monitor other bacteria that produce PBDEs.
- Researchers found that bottlenose dolphins in an area known as the Southern California Bight accumulate hundreds of halogenated persistent organic compounds, many of which have yet to be chemically identified and are known to accumulate in marine food webs.
- Scientists answered a decades-old question about the natural origin of persistent organic pollutants that bioaccumulate in higher organisms in the marine food chain. They discovered that marine biofilm-forming bacteria synthesized polybrominated persistent organic pollutants. The most common chemicals among these naturally produced pollutants were halogenated bipyrroles that, remarkably, derive from a combination of natural bacterial biosynthetic pathways and environmental oxidative processes.
- Investigators discovered that California sea lions develop human-like epilepsy after exposure to domoic acid, a naturally occurring algal toxin.
- Using a zebrafish model, investigators have demonstrated low doses of Domoic Acid affect the developing nervous system, including windows of susceptibility to DomA exposure, structural and molecular changes in the nervous system, and the link to behavioral alterations.
- Researchers explored complex genetics involved in how some killifish have rapidly evolved to tolerate normally lethal levels of environmental contaminants. Exploring the evolutionary basis for these genetic changes may provide new information about the mechanisms of environmental chemical toxicity in both animals and humans.
- Environmental pollutants found in fish consumed by humans were shown to reduce the effectiveness of the human body’s natural system for expelling harmful contaminants. All 10 persistent organic pollutants (POPs) studied interfered with the ability of p-glycoprotein, a transporter protein that expels foreign chemicals from the body. The researchers also found that fish with the highest levels of POPs were clustered in specific geographic locations, concluding that capture location is an important consideration when assessing the risk of POP exposure through ingestion of wild fish.
- Although sediments are repositories of contaminants in estuaries, methylmercury (MeHg) from sediments was not necessarily the primary source of MeHg in water or in fish across a range of field sites.
- Greater levels of MeHg bioaccumulation in fish is seen at sites with higher levels of MeHg in water and particulates but with lower algal densities. This suggests that increased primary production of MeHg will reduce MeHg accumulation at the base of the food web.
- In examining the effects of increased organic carbon loading and increased temperature related to climate change, field studies and mesocosm (or water enclosure) experiments revealed that organic carbon found in sediment is more influential than temperature on the net formation of MeHg in sediments as well as its bioaccumulation in organisms.
- Under conditions of climate change, factors, such as increased precipitation, that increase nutrient and carbon loading to estuaries may have a diminishing effect on MeHg transfer from sediment and water to fish. Such conditions may overwhelm the effects of elevated temperatures that increase methylation and bioaccumulation.
Great Lakes Harmful Algal Blooms and Toxins
- Researchers used state-of-the-art instrumentation to confirm that cyanobacteria in western Lake Erie backscatter light out of the water. The researchers are quantifying and characterizing these optical properties so they can develop bio-optical algorithms to detect cyanobacteria, even at low levels.
- Scientists developed a new algorithm for quantitative detection of harmful algal blooms in the Great Lakes based on remote sensing imagery. They validated the algorithm using 2014 field survey data, as well as data shared with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory.
- Looking at data from the last 10 years, researchers discovered that toxic cyanobacteria blooms initiate in western Lake Erie within a two-week window in mid-July, suggesting a strong biological clock. They linked the specific timing to wind events, which will help predict when blooms initiate.
- Once blooms initiate, they continue and fluctuate with intensity. Scientists found that the size of a cyanobacteria bloom is not necessarily correlated with its toxicity, which warrants further investigation.
- Scientists developed a new in situ sensor to detect microcystin-LR, a lethal biological toxin released during harmful algal blooms.
- Environmentally relevant exposure to microcystin LR compromises ovarian follicle dominance and ovulation in mice.