In the spring through early fall are the times of year that water bodies typically exhibit the most visible response to water quality problems. Algal blooms can be dramatic and are a result of excess nutrients from fertilizer, wastewater and stormwater runoff, coinciding with lots of sunlight, warm temperatures and shallow, slow-flowing water.
What is an algae bloom?
Algae are photosynthetic microorganisms that are found in most habitats. Algae vary from small, single-celled forms to complex multi-cellular forms.
An algal bloom is a rapid increase in the density of algae in an aquatic system. Algal blooms sometimes are natural phenomena, but their frequency, duration and intensity are increased by nutrient pollution. Algae can multiply quickly in waterways with an overabundance of nitrogen and phosphorus, particularly when the water is warm and the weather is calm. This proliferation causes blooms of algae that turn the water noticeably green, although other colors can occur. Some species of algae grow in clumps covered in a gelatinous coating and have the capability to float, allowing cells to stick together into large surface scums in calm weather.
Sometimes blooms are composed of cyanobacteria, also known as blue-green algae. Cyanobacteria are bacteria that, like plants, use solar energy and carbon dioxide to grow (photosynthesis). Cyanobacteria occur naturally in both freshwater and marine (salt) water bodies. Blooms also can be caused by dinoflagellates (single cell microorganisms [phytoflagellates] that include luminescent forms) in marine or estuarine water bodies.
Why do they occur?
The potential for blooms comes from nutrient pollution, an overabundance of the essential plant nutrients nitrogen and phosphorus. These elements enter waterways from point sources (such as industrial and wastewater treatment plant discharges), nonpoint sources (such as septic tanks and stormwater runoff from urban areas, farms and residential areas), and from nutrient-enriched rainfall. When the concentrations of nitrogen and phosphorus increase in a water body, the right combination of temperature, sunlight and low flow can trigger an algal bloom. Though nitrogen and phosphorus occur naturally and are essential plant nutrients, an overabundance of these nutrients can cause significant imbalances in the water body’s ecology, and blooms are one symptom.
Masses of algae often are observed in stormwater ponds during Maryland’s warmer seasons. Stormwater facilities are designed to capture polluted runoff. The ponds help remove nutrients and sediments before these pollutants can reach fragile waterways.
What can the public do?
The public plays an important role in reducing nutrient pollution. Each of us can use fertilizers wisely, such as only when lawns show nutrient deficiencies, according to manufacturer directions and avoid using fertilizers just prior to a rain. In addition, we can each use chemicals responsibly, properly maintain stormwater systems, not add to decaying organic matter in the canals by dumping clippings and leaves, and pursuing connections to a central sewer system where possible if you are a septic system owner.
Who monitors?
State staff routinely collect water and algae samples, particularly during periods when conditions are right for algal blooms. This is supplemented with monitoring by County staff and even volunteers and non-governmental organizations. When significant Hazardous Algae Blooms (HAB’s) events occur, the Maryland Departments of Health, Environment, and Natural Resources coordinate with local health and environmental departments to inform the public through media advisories, posted signs, and posting on state websites such as “Eyes on the Bay” and MDE”s Healthy Beaches website.
The Maryland phytoplankton monitoring program evaluates the algal community at 34 Chesapeake and 13 Coastal Bays stations monthly (April – Nov). Phytoplankton are a critical component of the Bay ecosystem and represent the first biological response to the Bay’s nutrient enrichment problem. It is the overgrowth of algae that has led to the Bay’s low oxygen problems. Results are used to show the success of Bay cleanup efforts, explain important linkages between water quality and living resources, and provide an early warning of potentially harmful exotic species.
Are they harmful?
Algae are a natural component of the aquatic food chain and are typically not harmful to people. If the types of algae that produce toxins reach high concentrations, then native aquatic organisms, livestock, pets, and perhaps even people who come in contact with the toxins, can be affected.
When algal blooms block vital sunlight from reaching beneficial underwater plants that provide food and a place to live and grow for fish and other animals, the ecosystem can be negatively impacted. Algae become stressed and die when they deplete the nutrient supply or move from freshwater into saltier waters. Decomposition of dying algae can reduce levels of dissolved oxygen in the water. Some fish species with little tolerance for low dissolved oxygen levels may die. In addition, some algal species can cause fish kills directly either by production of algal toxins or by clogging the gills.
Who should we call?
To report an algal bloom or fish kill contact MDE at (800-285-8195) (Days) or MEMA at (866-633-4686) (Nights/Weekends). Or you can report algal blooms on DNR’s Eyes on the Bay website.
Additional Sources:
Website – Eyes on the Bay: https://eyesonthebay.dnr.maryland.gov/eyesonthebay/habs.cfm
Website: Chesapeake Bay & Coastal Bays Monitoring https://dnr.maryland.gov/waters/bay/Pages/Algae.aspx