Aquatic plant invader: Algae & water resources

by Caroline Brown

Not for nuttin’ (as the local says) is Rhode Island called the Ocean State, Rhode Islanders have been blessed with an abundance of water resources. Besides a countless number of rivers, lakes, ponds, streams, we rely on the resources of Greenwich Bay and Narragansett Bay for our livelihoods and enjoyment.

But our activities have a tremendous affect on area water quality. Beach closures and fish kills caused by water pollution degrade the quality of life for people, fish, and animals. According to the U.S. Environmental Protection Agency (EPA), a major source of pollution in Narragansett Bay and Greenwich Bay is an excess of nutrients such as nitrogen.

Small amounts of nitrogen are essential for the growth of algae, but too much can cause excessive algal growth—algae on steroids, if you will. Excessive algae is one of nature’s most infamous and noticeable aquatic invaders. I don’t want to place too much blame on the plant–as with most invasives, its excess is caused by humans. But too much algae depletes oxygen levels in water, which can cause fish to suffocate. Excessive algal growth also prevents sunlight from reaching plants that live deeper underwater.

In 2001, more than 4.5 million mussels died in Narragansett Bay. And in 2003, a million menhaden—a small bait fish that primarily serves as food for other species—washed up dead in Apponaug Cove and Greenwich Cove. The R.I. Department of Environmental Management (DEM) blamed both the fish and mussel kills on excessive algal growth that led to fatally low oxygen levels. This photo (courtesy of Brown University news service), shows waves of dead mussels that washed ashore on Prudence Island in Narragansett Bay.

It’s not just sea life that suffers. Residents of the Conimicut area of Warwick are acquainted with what can only be described as a terrible smell in the summer. The problem is sea lettuce, a seaweed-like alga that is overfed by too much nitrogen. It eventually rots in the hot sun and produces a foul stench that can make the area practically uninhabitable.

What is the source of the extra nitrogen that causes algae to grow so quickly and extremely? Discharge from sewage treatment plants and substandard septic systems and cesspool, fertilizer runoff, and pet waste are the most common culprits. These problems are aggravated by heavy rains, which increase runoff.

In my next post, I’ll discuss each of these nitrogen sources in greater detail.

Parts of this article were originally published in the Kent County Daily Times. Photo of algae courtesy of the Chesapeake Bay Journal.

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One Comment to “Aquatic plant invader: Algae & water resources”

  1. This is a smelly problem indeed! We have more than our share of it, here on the Prairies. Many stagnant (green and slimey) lakes, not fun to swim in or smell either, in addition to the more serious problems this brings.

    You truly are blessed to have so many water resources to enjoy C. The ocean is like a magnet to me. In a pinch a pristine lake or river will suffice. Hope you will get to see my fav. the beautiful Kootenay Lake in BC, sometime in the future.

    BFN, G 🙂

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