We often hear from golf courses and communities that are dealing with algae in their ponds and lakes, but a recent story from China adds a new angle. This radio program that I heard last month linked seaweed farming for sushi off the coast of China to one of the biggest algal blooms on the planet. Some Chinese restaurants have seized on this onslaught of local sea vegetation and added it to their menus. A new version of the old adage about lemons: When life gives you seaweed, make sushi?
The reporter went on to explain that fertilizers used on farms and on people’s lawns are common contributors to conditions that cause algae blooms around the world, in China and in the Gulf of Mexico. These blooms occur when temperatures, sunlight, and nutrient levels are just right to support a major increase in the number of algae in an aquatic system, and they are becoming more common. What are algae anyway? Algae are microscopic plants that do not have true leaves, roots or flowers, but perform photosynthesis and consume oxygen all the same. Their presence is a natural part of the system, but any explosion in their numbers indicates an imbalance in the water body’s ecology.
Farmers in the Chesapeake Bay region are taking steps to prevent erosion of sediments from farm fields into streams by keeping cattle off stream banks, planting nitrogen absorbing plants in fields, and using buffer strips. They hope to prevent future outbreaks that degrade the Chesapeake's important fisheries and shellfish beds.
Lawns can provide important aesthetic and environmental benefits, including filtering out pollutants from stormwater that can contribute to nutrient buildup. Maintaining a lawn thick enough to serve as a water filtration buffer may require occasional applications of fertilizer. When needed, natural fertilizers such as compost, grass clippings, or manure are often cheaper and less likely to have toxic side effects than synthetic versions. However, a delicate balance is needed to avoid over-applying nutrients, especially anywhere turfgrass is located near a water body. Ideally, homeowners can select drought-resistant blends of grasses that require little or no mowing and no fertilizer.
In its latest enewsletter, the Maryland Department of Agriculture (MDA) urged homeowners to allow established lawns to go dormant during hot dry weather in summer. Applying fertilizer to force a lawn to turn green during its dormancy period can damage the grass and contribute to nutrient pollution in streams, rivers, bays, and the ocean. Dormant lawns will green up when cooler temperatures arrive and rainfall increases.
As is often the case, a few small changes to your land management can make a huge different for the environment. And keeping our lakes, oceans, and streams free of scummy, green mats and full of fish is worth a little effort.
To learn more about algal blooms, visit this NOAA website.