Researchers have found that Washington D.C.’s Potomac River has an increase in the diversity and amount of underwater plants. Underwater plants provide oxygen, food and habitat for fish crabs and other invertebrates. They also provide food for aquatic birds.
The area of native underwater plants has increased ten-fold. Also the number of native plants relative to the number of exotics has increased. In 1971, there were no underwater plants of significance in the upper Potomac, according to a USGS (United States Geological Survey) timeline.
River plants have increased presumably due to the recent efforts to restore water quality. A reduction in nitrogen from the wastewater treatment plant has allowed plants to grow again. Also sediment and nutrient reductions have increased water clarity, which benefits plants.
“Our results suggest that widespread recovery of submerged vegetation abundance and diversity can be achievable if restoration efforts are enhanced across the bay,” says Henry Ruhl from the National Oceanography Center. (Source: USGS)
Examples of the underwater plants which have increased are stargrass and wild celery.
- Native SAV (submerged aquatic vegetation) cover increased tenfold from 288 to 3081 acres.
- The overall area covered by SAV in the Potomac more than doubled since 1990, increasing from 4207 to 8441 acres.
- The diversity of SAV has increased. In 1990 the exotic hydrilla was 10 times more abundant than any other species. In 2007 the abundance of the 7 most frequently occurring species are more evenly matched.
New plant growth is very significant because plants have been known to improve and maintain water quality. USGS research has “demonstrated that beds of SAV were capable of altering the ambient water quality in the tidal river, increasing oxygen and pH during the daylight hours and maintaining clear water.”
Image Credit: USGS