Pamlico and tributaries an algae paradise

Published 7:01 pm Wednesday, August 17, 2016

The Pamlico and its creeks are under siege by an algae that’s turning water an unusual shade.

From Chocowinity Bay and east of Washington Park, down to Swan Point, including Broad and Goose creeks, algal blooms are thriving and turning the Pamlico River and its tributaries a pea green, according to Heather Jacobs Deck, Pamlico-Tar riverkeeper.

“The Olympic diving pools in Rio have nothing on the Pamlico right now — just to put it into context,” Deck said.

According to Jill Paxson, environmental senior specialist with Division of Water Resources, the continued hot weather, as well as above-average rainfall through the winter, spring and summer, are some of the leading factors in the proliferation of filamentous blue green algae, a species more likely to be found in freshwater lakes in the central part of the state, not in the usually brackish Pamlico. Another factor is that blue green algae thrives on phosphorous and nitrogen — polluted runoff from cropland, urban and suburban areas.

Paxson said the current algal blooms are the same thing she’s been seeing all summer long.

“It’s still green. We’re seeing some coagulation on the surface. It’s still the same species assemblages. It’s kind of good thing and nothing’s really changed. …

They are definitely blooming, and they are so happy, they keep blooming,” Paxson said.

Paxson said she’s received an increased number of calls this week from those concerned with water quality and swimming in the river. She said she has the same advice for Deck, who spent Wednesday on the water, said she’s seeing oxygen saturation levels — a byproduct of blooms’ photosynthesis — like she’s never seen before.

“I tell you, I’ve seen numbers on my water quality meter that I don’t think I’ve seen in my 13 years here,” Deck said.

A sample of measurements in Chocowinity Bay prove the point: 300-percent oxygen saturation; a pH of 10, its rise also caused the removal of carbon dioxide from the water during photosynthesis, making the water more alkaline. Usually, the Pamlico and its tributaries have around 110-percent oxygen saturation and a pH between 7 and 8, Deck said.

“I’ve never seen that before. It’s a pretty unique situation,” Deck said. “It’s just testament that we have a lot of work to do to reduce nutrient pollution.”

While the high pH can be a threat to local aquatic life, another byproduct of the excess rain has been the return of sea grass, which is beneficial to native aquatic species.

Paxson said the heavy precipitation in the spring was instrumental in sea grass germination — a good thing, since sea grass uses nutrients in the soil and keeps sediment from getting loose in the water column, in the same way as marsh grass does in the sound.

“I’m excited about it; 2005, 2006, was the last time I saw it so lush,” Paxson said.

“It’s almost like a natural erosion control, and it’s a really good habitat for juvenile fish and other species.”

As for people, and animals, swimming, Deck said to use common sense: if the water doesn’t look right or smell right, don’t get into to it.

“The other messages is these things can change daily or hourly,” Deck said.

Paxson said that while this species of algae can be toxic, there have been no reports in the state that it has produced toxins in local waterways. However, people should still be sensible, she said.

“If you have to get in there to cool off or anything, just be mindful of any cuts and sores you have. It’s an irritant,” Paxson said.