Outreach & Extension: Nutrients & Algae

Extension specialist Dr. Dan Terlizzi's laboratory conducts experiments on the ability of the macroalga, Ulva, to uptake ammonia (NH3) -- a product of fish waste.

As fundamental building blocks of life, nutrients like nitrogen and phosphorus are essential to a healthy and productive Chesapeake Bay. In excess, however, these same key nutrients can mean big problems for the Bay’s water quality. Overenrichment (eutrophication) has contributed to much of the Bay’s degradation over the last century including increased turbidity, oxygen depletion, loss of submerged vegetation, and changes in food web dynamics. Runoff from agricultural activities contributes a significant percentage of the nutrients entering the Bay (almost half the nitrogen and phosphorus), but it is not the only culprit. Fossil fuel combustion, sewage treatment waste, and runoff from cities also contribute to increased nutrient loads in the Chesapeake.

A recent report by the National Oceanic and Atmospheric Administration finds that the Mid-Atlantic region, including Chesapeake Bay, suffers from overnutrification more than any other coastal area in the nation, and that conditions may worsen. For efforts to restore the Chesapeake to succeed, it is critical that we address the input of nutrients that can lead to eutrophication and an overabundance of harmful algae. For more, read the report, Effects of Nutrient Enrichment in the Nation’s Estuaries: A Decade of Change.

Plants as Solutions

Nutrient inputs to the Bay vary depending on land characteristics -- topography, vegetation cover, and geology can all affect water chemistry and groundwater transport. Areas where land meets water (referred to as riparian zones) can play an important buffering role when covered with trees and vegetation that absorb nitrogen and phosphorus, reducing the loads that ultimately reach the Chesapeake.

Sea Grant Extension water quality specialist Dr. Dan Terlizzi capitalizes on the ability of plants to trap and keep nutrients in his work on phytoremediation. He is researching the ability of different species of macroalgae to act as “biofilters” in the water -- taking up potentially harmful ammonia (NH₃) from fish waste and converting it into nitrate (NO₃), a compound the algae can use. This work has important implications for the aquaculture industry as it may highlight a way to mitigate inputs of nitrogen-rich waste from farm-raised fish and bivalves to an already overenriched Chesapeake Bay.

Ponds and aquaculture impoundments also have the potential to have far-reaching effects on the area’s water quality. Those effects can be positive, as ponds help to slow surface flow, but effluent from ponds and aquaculture facilities can also enter the Bay and its connected waterways, bringing excess nutrients that may lead to algal blooms. Plants can also be used in novel ways to help control algal growth in aquaculture ponds.

Spreading the Word

Maryland Sea Grant Extension Program experts work to better understand the relationship between algal growth and eutrophication. A key to managing problems associated with algae is relaying this information to the general public and involving them in solutions.

The Water Quality Focus Team seeks to increase awareness about sources of nutrients in the Bay and their impact. Through presentations, telephone conversations, and email contacts, specialists conduct educational programming on topics such as algae identification, reducing herbicide use, and the interactions between living resources and water quality. Aquatic management articles written by Maryland Sea Grant Extension water quality expert, Dr. Dan Terlizzi, appear in “Ag Today,” a monthly column in the Carroll County Times. These activities are part of the Team’s efforts to build a public understanding of the role that algae play in the ecology of the Chesapeake, and to improve public perception of the costs and benefits of water quality improvements.