Harmful algal blooms crop up because of excessive amounts of “nutrients,” primarily nitrogen and phosphorus, that act as super-charged feed for naturally occurring algae. These toxic blooms are a growing threat to public and ecosystem health.
Harmful Algal Blooms Plaguing our Waters
The transition from summer to fall is upon us, which means that peak foliage and peak pumpkin spice are just weeks away. Also peaking is the unfortunate onset of harmful algal blooms (HABs) in waters around the United States. The algae growth apex is typically late-summer, early-fall and is due to the preponderance of nutrients deposited by heavy spring and summer rains that stick around and thrive in the warmer, shallower waters.
As we’ve written before, pesky algal blooms crop up because of excessive amounts of “nutrients” – often nitrogen and phosphorus – that act as super-charged feed for naturally occurring algae. These algae are eaten by bacteria, and in the process starve the water of oxygen, creating fish-killing dead zones. The blue-green algae that appear in ponds and lakes throughout the country (and world) can also produce toxic chemicals like cyanobacteria that are harmful to drink and even touch. (Note that algae varieties can range in colors from red to brown and more.) While the sources of nutrient pollution are plentiful, the major ones are runoff from urban streets and farm fields loaded with fertilizers and manure. Close behind are sources such as industrial discharge, wastewater treatment plant overflows and the burning of fossil fuels.
In the United States and globally, there is so much nitrogen and phosphorus pollution that ends up in our streams, rivers, lakes and oceans that the Earth is being pushed beyond its ability to manage them, as determined by scientists who developed the Planetary Boundaries framework. Synthetic fertilizers, while beneficial for crop cultivation, are of particular concern when total quantities overwhelm the global ecosystem’s ability to absorb them. By most accounts, climate change makes it even worse.
Harmful algae blooms are a constant water quality problem that are often plain to see (although not always). Below is a small sample of how recent HABs have afflicted our waters:
- Scientists from California to Alaska are studying the enormous red algae bloom that seems to correspond to the vast “warm blob” sitting in the Pacific Ocean – a bloom that might be the biggest ever recorded. Some Washington State fisheries have been closed for fear of elevated levels of the neurotoxin domoic acid that build up in marine creatures like oysters and finfish and can work its way up the food chain and harm birds, marine mammals and humans.
- An update to the 2014 Toledo, Ohio HAB drinking water contamination that entered the intake in Lake Erie’s western basin: the incident spurred Congress to ask the EPA to write the first-ever recommendations on toxic microcystin in drinking water. Dangerously high readings of the poisonous microcystin (a cyanobacteria), produced by the HAB, led to the three-day shutdown of the city’s drinking supply.
- There is water quality crisis in Iowa with waterways teeming with excess nutrients from fertilizers and manure. The agriculture-dominated state has so much polluted runoff that there is nitrate (a nitrogen byproduct), algae and bacterial contamination in waters throughout the state. There’s new recognition of the problem after the Des Moines Water Works sued three rural Iowa counties to clean up their water supply, the Raccoon River, which requires a complete overhaul of how many farms use land and water.
- Florida’s Indian River Lagoon is teetering on the edge of ecosystem collapse from incessant algal blooms caused by leaky sewage systems and fertilizer runoff. The seagrass that provides the foundation of the food web there has been virtually wiped out from the terrible 2011 “super-bloom,” and since then, 70 dolphins and hundreds of manatees and pelicans deaths have been linked the HABs in the lagoon. With a focus on the lagoon pollution in 2015, help is on the way with dredging, sewage and septic tank upgrades, along with green planting and shellfish bed seeding to capture runoff, among others strategies.
- On a more local scale for us in New York City, ponds and lakes in western New York have seen a rise in HABs in the summer of 2015, sadly including this author’s boyhood haunt, Chautauqua Lake. An especially warm, dry summer has seen algae growth creep up, which has hindered recreational swimming, boating and fishing.
Originally published at GRACE’s former blog Ecocentric by Kai Olson-Sawyer on 09.29.2015.
Photo: Ducks swimming in algae-covered pond. Credit: Kai Olson-Sawyer