Cyanobacteria Methods

Science Center Objects

Texas Water Science Center (TXWSC) scientists are testing different methods of detecting and quantifying cyanobacteria and cyanotoxins in Texas reservoirs. The results of these tests could be used to develop a cost-effective monitoring plan to evaluate the presence and concentration of cyanobacteria and cyanotoxins in Texas reservoirs.

Cyanobacteria (also known as blue-green algae) are a group of photosynthetic bacteria found in surface waters throughout the country. Similar to algae, cyanobacteria can rapidly multiply forming thick blooms, especially in warm, eutrophic waters. Some strains of cyanobacteria can produce toxins (cyanotoxins) in concentrations that are harmful to humans, pets, fish, and wildlife. Cyanobacterial blooms can also produce secondary compounds which can cause taste-and-odor problems in public water systems.

Common analytical techniques to quantify cyanotoxins and taste-and-odor compounds include enzyme-linked immunosorbent assays (ELISAs), gas chromatography-mass spectrometry (GC/MS), and liquid chromatography-tandem mass spectrometry (LC/MS/MS). More recently, datasonde manufacturers have improved in vivo fluorometry sensors, which can provide a relative measurement of chlorophyll and phycocyanin photopigments that are found in cyanobacteria. Each method offers advantages and disadvantages with regard to ease of use, matrix interference, interference from other compounds, level of detection, and cost.

 

Secchi disc

Using a Secchi disc to measure water transparency during an algal bloom on Lake Waco.

Detect and Analyze

In the first phase of this project, TXWSC scientists conducted a one-time sampling event on 18 Texas reservoirs representing a variety of physicochemical conditions statewide. TXWSC scientists then compared field and lab methods for the presence and concentration of cyanobacteria, cyanotoxins, and taste-and-odor compounds.

Samples are analyzed for:

  • Cyanobacteria and cyanotoxins
  • Genes that code for cyanotoxins
  • Taste-and-odor (T&O) compounds
  • Chlorophyll-a and pheophytin-a
  • Cations/anions, nutrients, TDS, and TOC
  • Phytoplankton taxonomy

Salient results

  • Green algae and cyanobacteria detected in all sampled reservoirs
  • Golden algae detected in 14 reservoirs
  • T&O compounds detected in most reservoirs
  • Microcystins detected in four reservoirs
  • Cylindrospermopsin detected in two reservoirs
  • Saxitoxin detected in one reservoir
Harmful algal bloom

Harmful algal bloom (Microcystis) at Upper Bosque River Site near Stephenville, TX.

Methods

Standard methods were used to collect the water samples.   

Cyanobacteria and other phytoplankton were analyzed for

  • Taxonomy
  • Biomass/Biovolume
  • Concentrations

Cyanotoxins were analyzed using

  • Dipstick kits
  • Enzyme-linked immunosorbent assay (ELISA)
  • Liquid chromatography–tandem mass spectrometry (LC/MS/MS)

T&O compounds were analyzed using

  • Gas chromatography–mass spectrometry (GC/MS)

 

The second phase of this project included a review of the field, analytical, and taxonomic results from Phase 1 sample collection efforts to determine if there are any correlations between the various field and laboratory methods. The results of the comparability analysis will be used to guide additional sampling in Phase 2 to further refine field procedures and analytical method selection.