Glossary

CTD – stands for Conductivity-Temperature-Depth and refers to the electronic instrument deployed into the ocean to measure these and other parameters. Electronic sensors measure different aspects of the ocean while the CTD is lowered to a terminal depth (on CalCOFI ~500m, depth permitting).  These data are transmitted up the conductive cable and display on the CTD computer screen real-time.  The screen plots created during the downcast are used to determine the upcast optimal bottle closure depths/spacing.  After being lowered to the terminal depth without stopping, the rosette (array of 24 bottles mounted on the frame that surrounds the CTD electronics) bottles are sequentially closed at specific target depths as the CTD is raised.  Although the terms CTD or rosette may be used interchangeably when referring to the complete package, the CTD is the electronic portion; the rosette and carousel (central hub that controls the bottle closure) are the bottle array.  The CTD electronics may be deployed independent of the rosette. 

rosette – metal frame and bottle array that surrounds the CTD electronics.  CalCOFI uses 24 ten liter bottles; other programs may use 6, 12, 24, or 36 bottles of various volumes.  The carousel (or pylon) holds the bottle lanyards until the CTD data aquisition programs sends a command to close a specific bottle.  CalCOFI’s bottle closure sequence is bottle #1 at terminal depth (usually ~500m) ending with bottle #20 at surface (~2m).  The 4 extra bottles are for discretionary use (except the Santa BarbaraBasin station where all 24 are closed).

Carousel (or pylon) – electronic hub centered on the rosette that holds the bottles open until it receives the release command.  Bottle closure is usually sequential but the software can be program to close the bottle in any order.

Lanyard – nautical term used to describe a short line or rope that secures or rigs something.  In reference to the CTD/rosette, the nylon rigging used to keep the bottle top & bottom caps open

HPLC-  High-pressure liquid chromatography; high-performance liquid chromatography.

Fluorometer -instrument used to measure fluorescent materials; for Chl-a, it emits a excitation wavelength of light ~460nm and detects the emission return at ~685nm. 

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

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

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

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

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

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

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 that is repeatable.