Aerial shot of Passaic River Institute.

Algae Identification

The Main Points

  1. Nuisance algae is a common problem in many lakes and waterways.
  2. Knowing what types of algae are present is an important step to develop an effective management plan.
  3. Not all algaecides or control strategies can be used in all situations.

The Details

Among the most common complaints about lake water is that of nuisance algae. Soupy, green-colored water is unattractive for recreation, can be harmful to fish and wildlife, and can lead to a number of human and environmental health problems.

“Algae” is a collective term that constitutes a diverse group of single cell organisms capable of conducting photosynthesis.  Normally a healthy algae population is necessary for the ecosystem.  But most forms of algae can grow rapidly in response to excess amount of nutrients, especially phosphorous.  Some can actually produce toxins (see cyanotoxins) that pose public health risks.

Algae come in many forms; branched filamentous green algae, filamentous green algae, diatoms and blue-green algae, just to name a few.  Identification with a field guide and trained eye is adequate for most situations.  However for effective management, it is often helpful to identify specific algal species and their abundance.  This will help the lake or watershed manager select the most effective control strategy.