Aquatic animal pathologist Wolfgang Vogelbein held a small bottle of York River water up to the overcast sky Wednesday and gently shook it.
“Holy guacamole,” he murmured. “Take a look at this.”
“This” was all the tiny bits of microalgae floating in the sample — so many that Vogelbein didn’t even need to magnify the sample to make them out.
Vogelbein and molecular ecologist Kim Reece are studying this particular algae, called Alexandrium monilatum, as well as a second species called Cochlodinium polykrikoides that at the moment are running rampant in the York and some surrounding waterways, bursting into massive blooms known as red tides.
Red tides are a particular summer scourge because the blooms soon decay, sucking up dissolved oxygen in the water column and often creating the dreaded dead zones that are lethal to marine creatures.
So far, said Reece, there have been no reports of big fish kills associated with the algae — “But that doesn’t mean they’re not occurring.”
Vogelbein and Reece are with the Virginia Institute of Marine Science (VIMS) in Gloucester Point, and have been studying the two algae for several years now, largely because they’re the heaviest and most pronounced blooms in this region.
Alexandrium is one of the more showy algae because it’s bioluminescent, glowing bright blue when the water is disturbed by a fish, crab or boat moving through. On Tuesday night, other VIMS researchers ventured out on the water to try to photograph the light show.
But the light show also has a dark side.
Both Alexandrium and Cochlodinium contain toxins that are harmful to oyster larvae and fish larvae. And part of Vogelbein and Reece’s research is to help health officials determine whether those toxins are also harmful to adult oysters and fish — and potentially to the humans who eat them. They share their reports and updates on bloom distribution, cell counts and other data with the Virginia Department of Health.
“We know very little about the toxin,” Vogelbein said. “And whether or not there may even be human health effects.”
They’re preparing to conduct a feeding study in which they’ll “intoxicate” adult oysters, he said, then feed those oysters to fish to determine any adverse health effects or mortality.
In past years, said Reece, animals being studied in VIMS sea labs — where fish tanks are fed by York River water flowing through — have died after accidental exposure to the algae toxin.
And laboratory workers handling very high densities of algae while trying to isolate their toxins have complained of pungent odors, usually associated with Cochlodinium, as well as teary eyes and nasal irritation, she said.
Algae are found naturally in coastal waters and are an important food source for marine life. But under the right conditions — warmer temperatures, for instance, or stormwater runoff loaded with phosphorus and nitrogen — they multiply rapidly into an algal bloom.
There are hundreds of different species, many of them blooming at the same time, said Reece. Until recently, Alexandrium wasn’t very expansive, but a shift occurred in 2007 and today its blooms are much more intense and widespread.
The water samples taken every week are to secure live algae for DNA extraction to identify which species they’re dealing with, its bloom dynamics and distribution, and preserve other algae samples for future study.
And on Monday, as part of a coordinated effort to determine the extent of the algal blooms, Vogelbein flew over the region in a plane provided by the Virginia Marine Resources Commission, while another research aircraft from NASA Langley Research Center in Hampton fitted with sensors did the same.
Blooms aren’t fixed, he said, but shift back and forth in the river depending on prevailing winds and other conditions.
Last week, a vertical profile study of York River water about 24 feet deep found algae living as deep as about 18 feet.
“Much deeper than we had thought before we started doing these profiles,” Reece said.
The algae also seem to move up and down in the water column in a diurnal vertical migration, gravitating toward sunlight during the day, then dropping toward the river bottom at night.
The densest bloom Wednesday was off the north shore of Goodwin Island in the mouth of the York, the site of an oyster reef reserved for research work. That was where VIMS graduate student Sarah Pease hooked two oyster cages and hauled them aboard to cull six random adult oysters from each.
Pease said she’d check them later for signs of disease or mortality from exposure to the algae.
Dietrich can be reached by phone at 757-247-7892.
