Algae Monitoring

Papers from UC Berkeley on Eel River Algae

The Eel River Recovery Project, in cooperation with the University of California, has been monitoring cyanobacteria and cyanotoxins since 2013 at strategic locations throughout the Eel River basin. Keith Bouma-Gregson approached ERRP at our annual retreat in October 2012 and asked for our cooperation in monitoring cyanotoxins, and we have been collecting data every summer since then. ERRP is about to publish a summary analysis of findings from 2013-2017 and Keith has published his doctoral dissertation and been awarded his degree from UC Berkeley

The Ecology of Benthic Toxigenic Anabaena and Phormidium (Cyanobacteria) in the Eel River, California. By Keith Bouma-Gregson A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Integrative Biology in the Graduate Division of the University of California.

Rise and fall of toxic benthic freshwater cyanobacteria (Anabaena spp.) in the Eel river: Buoyancy and dispersal. Keith Bouma-Gregson, Mary E. Power, Myriam Bormans.

Microbial diversity and metabolic potential in cyanotoxin producing cyanobacterial mats throughout a river network. Keith Bouma-Gregson, Matthew R. Olm, Alexander J. Probst, Karthik Anantharaman, Mary E. Power, Jillian F. Banfield.

Widespread Anatoxin-a detection in benthic cyanobacterial mats throughout a river system.  Keith Bouma-Gregson , Raphael M. Kudela, Mary E. Power.

The Thirsty Eel:  Summer and Winter Flow Thresholds that Tilt the Eel River of Northwestern California from Salmon-Supporting to Cyanobacterially-Degraded States.  For Special Volume, Copeia: Fish out of Water Symposium.


Toxic Algae Factsheet

Sampling Methods

Solid phase adsorptive toxin tracking (SPATT) samplers placed at various Eel River locations catch cyanotoxin molecules. The concentrations of cyanotoxins allow comparison between sites and years, but do not provide quantitative data that can be compared to public health thresholds. In 2013 and 2014 SPATTs were rotated weekly. In 2015, they were placed for monthly intervals at an expanded number of locations. Automated water temperature probes are also deployed with SPATTs to test for associations between elevated temperatures and algae blooms. UC Santa Cruz is helping by processing the SPATTs.

UCB is Helping the Eel River Community

ERRP is grateful for the continued support of UC Berkeley, which goes beyond the needs of Bouma-Gregsonā€™s doctoral studies.  For instance, UCB assisted the Humboldt County Sheriffs Department in July 2015 by teaching them to identify potentially toxic algae to ensure the safety of cadaver sniffing dogs that searched the river.

Funding for UCB research is being provided in part by a U.S. EPA STAR Fellowship and the National Science Foundation Critical Zone Observatory grant.

Types of Eel River Toxic Cyanobacteria

Anabaena in algae mats

This is the edge water at Phillipsville where dog mortality occurred in 2009.  Floating algae mats likely contain decaying fragments of toxic Anabaena. This cyanobacteria likes warm stream margins and tends to colonize decaying green algae beds as flows drop. Not all cyanobacteria cells produce toxins, and toxins may not be normally released from cells. However, as cells break down or when cells are broken open, toxins may be released.

Anabaena in algae spires

Darker colored Anabaena spires colonize decaying green algae at Phillipsville on the South Fork Eel River. It forms gelatinous masses around the decaying algae that trap oxygen during diurnal photosynthesis and create pencil like spires that are dark green or even blue-green in color. Segments of the spires may slough off and create mats that pose major risk to dogs and children.


Phormidium forms durable mats on cobble, boulders or bedrock in rapids or riffles that range from tan to dark brown in color and may have a velvety or feathery appearance. These mats are capable of producing anatoxin-a, but they present less health risk to pets and people because they grow submerged in riffles. Lack of visible Anabaena mats in the reach of the South Fork Eel at Leggett suggests that Phormidium may be a contributor to elevated levels of cyanotoxins there.


This cyanobacteria species forms brown, beige or blue-green durable gelatinous balls that grow most often in riffles, but sometimes also in shallow pools. Shape of Nostoc may vary to include ear-shaped and blade forms of growth. UCB sampling within patches of Nostoc found some cyanotoxins, but lesser levels than in Anabaena and Phormidium. Similar to the latter, Nostoc tends not to slough off and form mats.

Listen to an interview with biologist and Berkeley professor, Dr. Mary Power.  She talks about how reduced flow causes the river to produce more potentially toxic blue-green algae.