Posts Tagged 'algae blooms'

Thoughtful Thursdays: Algae Bloom in the Bay

Have you noticed a murky tint to Baltimore’s Harbor lately? A “mahogany tide” of reddish-brown algae (Prorocentrum minimum) has invaded our local waters.

Reddish-brown water just outside the National Aquarium

“What we’re seeing here appears to be what’s called a mahogany tide,” says National Aquarium specialist Susan Bitter. “Unfortunately, it isn’t exotic and it isn’t as interesting and tasty as it sounds.”

Watch Susan explain about the mahogany tide on WJZ:

Algae blooms can be very damaging to life in the Bay. The algae live for only a short time, but when they die, the bacteria that eat the algae suck much-needed oxygen out of the water, creating “dead zones.” The lack of oxygen in the water makes it hard for the aquatic plants and animals that live there to survive, potentially causing large-scale fish kills.

Algae blooms occur each spring in the Chesapeake Bay at varying intensities. We had a mild winter, and record-high water temperatures are being recorded all over the Chesapeake. The warm water not only encourages the algae growth, but also makes the bacteria that feed on them more active, drawing more oxygen out of the water.

Excess nutrients in the water are the primary cause of harmful algae blooms. We can all play a part in reducing the nutrients that are introduced into our local streams.

The Aquarium recently participated in the launch of floating wetlands into the Harbor, which help absorb nutrients from the water.

Everyone can help by adopting bay-friendly lawn care practices: plant native plants that don’t need fertilizer; don’t fertilize in the spring, only in the fall, and only with the nutrients that are needed for your lawn (spring rains wash fertilizers off land and into the waterways). Take your car to the automatic carwash and let it do your dirty work. When you wash your car in your driveway, those chemicals run down into the storm drains, which feed directly into the Bay. Most sewer systems and wastewater treatment plants do not remove poisonous cleaners, and yard and car-wash chemicals make their way into local waterways. And finally, pick up after your pet, and if you’re on a septic system, make sure it’s functioning well.

Why does the harbor water smell?

The water in Baltimore’s Inner Harbor is giving off a very fishy odor. Wondering why? If nutrient levels are high enough, warming waters can sustain increased numbers of microscopic plants or algae.  Nutrient runoff from our recent spring rains fueled a brown algae bloom in the inner harbor giving the water a mahogany color last week. Algae has a short life span, and as it dies oxygen is consumed and is no longer available for other organisms in the water column.  At this point, fish and other animals that cannot escape the low oxygen zones die.  These are commonly referred to as “dead zones” which cause fish kills, and the bad smell over the weekend. The bacteria then devours the dead fish killed by oxygen depletion, fueling more bad odors.

Some animals, like jellies require very little oxygen and manage to live through these dead zone events. This is part of the reason jellies populations are thriving in bodies of water around the world.

These excess nutrients that cause the algae blooms can come from a variety of sources including fertilizer, storm fort-mchenry-cleanup-webwater runoff, and even atmospheric deposition.  So what can be done about it?  The National Aquarium is actively working to improve the water quality of the Bay by restoring vital habitats like tidal wetlands.  These habitats remove excess nutrients, help prevent flooding and provide important habitat to the animals that live there.  You can volunteer – check it out!


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