Chlorophyll a - the green photosynthetic pigment contained in all living algae that can be directly measured and used as the primary indicator of algal biomass.

Chlorophyll b - an accessory pigment found in some algae that can effect the accuracy of chlorophyll a determinations

Chlorophyll c - an accessory pigment found in some algae that can effect the accuracy of chlorophyll a determinations.

Cyanobacteria - bacteria that contain photosynthetic pigments, some species are toxic.

Discrete sampling - the term used to describe samples collected and measured in test tubes

Extraction - the process of using a solvent to remove the chlorophyll from the algal cells.

Eutrophic - term used to describe a nutrient-rich body of water.

Flow-through - the term used to describe the pumping of water through a fluorometer for continuous measurement and monitoring

Fluorescence - the phenomena of some compounds to absorb specific wavelengths of light and instantaneously emit longer wavelengths of light energy.

Fluorometer - instrument used to measure fluorescent materials.

In vivo - Term used for measuring chlorophyll that is contained naturally within the algal cells

In-Situ - Term synonymous with in vivo

In-vitro - Term used when measuring chlorophyll that is extracted from the algal cells

Oligotrophic - term used to describe a nutrient-poor body of water.

Pheophytin - term for degraded chlorophyll that occurs naturally or as a result of acidification.

Phytoplankton - the photosynthesizing constituent of plankton, mainly unicellular algae

Phycocyanin - the accessory pigment found primarily in fresh water cyanobacteria species such as Anabaena, Microcystis, and Spirulina.

Phycoerythrin - the accessory pigment found primarily in marine cyanobacteria species such as Synechococcus spp

Primary Standard - a sample of the exact same material being measured, and ideally at a known concentration level.

Quenching - term refers to factors that reduce, or quench, fluorescence.

Secondary Standard - a sample material that can be used as a secondary measure for calibration, and provides a stable reference fluorescence that is repeatable.