We’re committed to improving our ecosystems, quality of life, and communities for the better.
Our passion and commitment to the integration of innovative science and engineering drive us to exceed on behalf of every client.
From tidal estuaries and back bays to nearshore marine waters, New Jersey’s coastal environments support fisheries, recreation, wildlife, and local economies. Increasingly, however, these valuable ecosystems are vulnerable to a wide range of harmful algal blooms (HABs). While algae are a natural and essential part of aquatic ecosystems, certain environmental conditions can cause some species to grow excessively, leading to ecological damage, public health risks, and economic losses.
Understanding what HABs are, what drives them, and how nature‑based restoration strategies can prevent or mitigate blooms is essential to supporting the long‑term resilience of New Jersey’s coastal environments.
The term “algae” is ecological rather than taxonomic and encompasses a diverse group of organisms, including eukaryotic algae, such as diatoms and dinoflagellates, and prokaryotic cyanobacteria, commonly referred to as blue‑green algae. Algae are not inherently harmful. In fact, they provide critical ecosystem services, including:
Phytoplankton are microscopic, free‑floating algae found in freshwater, estuarine, and marine environments. Scientists estimate there are 20,000 to more than 100,000 phytoplankton species, but only a small fraction—roughly 100 to 300 species—are capable of forming toxin‑producing harmful algal blooms. Problems arise when these species proliferate rapidly under favorable conditions. These blooms can become harmful when they produce toxins, deplete oxygen, shade submerged vegetation, or otherwise disrupt ecosystem function.
Most toxin‑producing HABs fall into three major groups:
While most harmful algal blooms are caused by phytoplankton, large, fast‑growing macroalgae can also create serious environmental and economic challenges when conditions allow them to proliferate. A well‑known example is Sargassum, a floating seaweed that can form extensive mats across the ocean surface. During periods of rapid growth, these mats can block sunlight from reaching coral reefs and other sensitive habitats. When Sargassum washes ashore in large quantities, it can deter tourism and recreation. As the algae decomposes, it releases hydrogen sulfide gas, producing strong odors that make nearby coastal areas unpleasant to visit. While Sargassum blooms occur most summers along the coast of south Florida, the severity and extent of these events vary considerably from year to year.
HABs can form in freshwater systems, brackish estuaries, and coastal marine waters, and they are particularly dangerous with myriad when they produce toxins that affect humans, pets, livestock, fish, shellfish, and wildlife.
Below is a closer look at the dominant types of marine HABs in the region, the organisms responsible, and the environmental conditions that influence their development.
Common toxin‑producing dinoflagellates include:
Brown tides are associated with several diatom genera, such as:
These blooms are influenced by a combination of physical, chemical, and climatic factors, including:
Ulva, commonly known as sea lettuce, is a green macroalga that can form extensive blooms in shallow, nutrient‑rich estuaries. Another common bloomer, Enteromorpha, is now considered genetically equivalent to Ulva. Although Ulva blooms are non‑toxic, they can still cause serious ecological and social impacts:
Common bloom‑forming Cyanobacteria genera include:
Cyanotoxins should not be confused with taste‑and‑odor (T&O) compounds. Cyanotoxins are colorless, tasteless, and odorless whereas T&O compounds, such as geosmin and MIB, cause earthy or musty smells. Cyanobacteria can produce T&O compounds without toxins as well as toxins without noticeable odors.
This distinction can complicate detection and public perception of risk.
HABs are commonly driven by:
The impacts of marine and estuarine HABs extend far beyond discolored water.
These HABs, the region’s most common, illustrate the wide range of organisms, toxins, and ecological pathways through which algal blooms can affect coastal systems. Although they differ in form, from microscopic phytoplankton to expansive mats of macroalgae, they are often driven by a common set of environmental conditions that favor rapid growth and persistence. Climate change is intensifying many of these drivers. Rising water temperatures, altered precipitation patterns, and longer periods of stratification increasingly create conditions that favor bloom formation. At the same time, human activities continue to increase excess nutrients to coastal waters. Runoff from agricultural lands, chemicals transported by rainfall and irrigation, and discharges from wastewater treatment facilities all introduce nitrogen and phosphorus into rivers, lakes, and estuaries. These nutrients act as fertilizer for algae, accelerating bloom development.
Nutrient‑laden stormwater runoff does not remain localized, rather, it moves downstream through interconnected watersheds, ultimately reaching estuaries and coastal waters where it can contribute to marine blooms. Understanding these linkages between land use, climate, and algae growth is critical to identifying effective strategies for preventing and managing HABs in coastal environments.
A range nature-based nearshore and shoreline restoration and management strategies are increasingly used in coastal systems to help mitigate HABs:
Additional management approaches, depending on site conditions, may include:
HABs represent a complex and growing challenge in New Jersey’s freshwater, estuarine, and coastal systems. They threaten public health, ecosystems, and coastal economies, but they are not insurmountable. Nutrient control, thoughtful watershed management, and nature‑based restoration strategies are central to preventing, mitigating, and controlling HABs. If you’re interested in learning more about our work to identify, assess and mitigate HABs, click here to read about our groundbreaking research project with Friends of Hopewell Valley Open Space to monitor HABs using drone technology, advanced data modeling, and community science across a 73-mile stretch of the Delaware River and 23 associated waterbodies.
add comment
Δ
Your Full Name * Phone Number * Your Email * Organization Address Message *
By EmailBy Phone
Submit
Couldn’t find a match? Check back often as we post new positions throughout the year.
PRINCETON HYDRO
PRINCETON HYDRO