Researchers found that common 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, when they discovered that marine biofilm-forming bacteria synthesized polybrominated persistent organic pollutants, including polybrominated diphenyl ethers (PBDEs). They found that natural contaminant loads were dominated by 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.
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 biodilute MeHg 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 and may overwhelm the effects of elevated temperatures that increase methylation and bioaccumulation.
Great Lakes Harmful Algal Blooms and Toxins
Investigators collected measurements from state-of-the-art instrumentation confirming 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 the presence of cyanobacteria, even at low levels.
Scientists developed a new algorithm for quantitative detection of harmful algal blooms (HABs) in the Great Lakes based on remote sensing imagery. They validated the algorithm using newly collected data from a 2014 field survey, as well as data that the scientists share with the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory.
Looking at data from the last 7 to 10 years, researchers have discovered that toxic cyanobacteria blooms initiate in western Lake Erie within a 2-week window in mid-July, suggesting a strong biological clock mechanism. 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 are finding 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 HABs.
Researchers correlated various observing parameters for monitoring HABs in the Great Lakes to understand better HABs and toxin releases.