Summer seagrasses such as eel and widgeon grasses which were common 30 years ago have yet to reappear in the harbor, she said. Another sign of good health is declining algal growth. Algae levels in Solomons Harbor dipped in 1997, compared with 1996, the study found, although Wood said it is unclear why. Although things may be looking up for Solomons Harbor, researchers cautioned that the County needs to closely monitor the amount of nitrogen in the harbor. Nitrogen is one factor that causes algae to bloom in the water.
Algae blocks sunlight, making it difficult for other harbor plants to grow.
That, in turn, diminishes the oxygen supply at the bottom. That condition, known as anoxia, threatens organisms that rely on oxygen, such as shellfish. Once algae blooms and dies, it sinks to the bottom of the harbor, where microbes eat it and deplete the low oxygen supply even faster. Shellfish caught in a region where that occurs usually die quickly, Wood said. Improper disposal of sewage wastes from pleasure boats is a major source of nutrient enrichment to Solomons Harbor waters Nitrogen comes from fertilizer, forests, air, rain, rivers and human waste via septic systems and boaters.