OCEAN CITY – The murky, almost chocolate color of Herring Creek and other coastal bays tributaries this week was caused by a natural phenomenon called brown tide and is expected at varying degrees this time of year, but its early arrival and intensity is reason for concern.
At a quick glance this week, Herring Creek in the area of Route 50 was a striking dark brown color reminiscent of the chocolate river in the Willy Wonka movies, and it was later learned the coastal bays tributary and other like it have fallen victim to an occasional phenomenon called “brown tide.” It is caused by an excessive bloom of small marine algae found naturally in the estuaries and is often triggered by natural and man-made forces.
In this case, the brown tide bloom was likely triggered by last week’s torrential rains, which caused an excessive run-off of nutrients from the land. According to Dr. Roman Jessien of the Maryland Coastal Bays Program (MCBP), much of the farmland in the area was recently fertilized, which likely contributed to the bloom, but a variety of other factors, some naturally occurring, could have added to its intensity.
“This brown tide appeared very early this year and it’s of concern to us,” he said. “It’s a concern because it has to do with increased nutrient loading in the bays. Basically, it’s a brown algae and it can use organic material in a much more efficient way to proliferate.”
While it is not unusual for brown tide to bloom in the creeks and tributaries around the coastal bays, its sudden appearance this week could indicate it might become more problematic.
“We’re seeing it early, we’re seeing more of it, and we’re seeing it last longer,” said Jessien. “It could be just another example of how things are changing in the coastal bays.”
Jessien said the MCBP has notified the Maryland Department of the Environment (MDE) and the state’s Department of Natural Resources (DNR) about the sudden appearance of brown tide in the area and has stepped up it program of taking periodic water samples from the estuaries.
While the phenomenon often occurs naturally, a wide range of man-made factors contribute to it. Maryland has recently adopted more stringent regulations on septic systems in its critical areas and other measures such as Total Maximum Daily Load (TMDL) programs are achieving desired results to some degree, but this week’s algae bloom reinforces the idea more needs to be done.
“There is a reason we try to have these programs in place and this brown tide incident illustrates the need for more monitoring of the health of our bays,” said Jessien.
Brown tides are not detrimental to humans or most finfish, but their persistence can have an adverse effect on shellfish and essential habitats, such as bay grasses, and other resources because they can block sunlight from reaching the bottom.