Sampling Methods Flashcards
What was the Challenger Expedition?
First true oceanographic research cruise from 1872-1876 which explored Atlantic, Pacific and part of Southern Ocean and collected physical, chemical and biological samples and studied deep currents and discovered the Marianas Trench
What are some considerations for sampling methods and design?
What is the target? Who is there? How many (abundance)? How often? What do they do?
What considerations are made for sampling organisms/species?
What type of organism? Are you studying a specific size or age-structure, or the whole community?
What do you sample when trying to find out how many or how often an organism occurs?
Numeric abundance (i/m^3), biomass, spatial and temporal trends in abundance
What are some examples of sampling for what organisms do?
Movement (vertical migration), productivity (rate of population growth)
What are some physical data sampling methods?
CTD probe + other sensors for other physical data, and other chemical and biological information
Light absorbed by chlorophyll a is either:
used in photosynthesis, dissipated as heat (~5% re-emitted as fluorescent red light)
What are some chemical and biological data sampling methods?
Water sampling (Niskin, CTD-Rosette)
What are some phytoplankton sampling methods?
Estimated by chl content, mesh nets, sediment traps (dead material), inverted light or epifluorescence microscope, flow cytometer, cell and particle counter, submersible flow cytometer, imaging particle analysis
What are some zooplankton sampling methods?
Mesh nets (one or multiple), computer-assisted counting technologies, high-frequency acoustics
What are the challenges of vertically stratified sampling?
Sampling is very time consuming, and you have many samples that need to be processed
What is vertically stratified sampling used for and how does it work?
Determines differences in depth distributions of plankton (numbers and biomass), works by subtraction when using basic nets
What are the problems with net sampling?
Nets don’t catch everything, patchiness, nets get clogged, logistics of sample processing
How does the rate of clogging of a zooplankton net change as the velocity the net is towed changes?
As time goes on the net gets more clogged and the different between the inner and outer flowmeter increases
How does the continuous zooplankton recorder work?
Towed by ‘ships of opportunity’ where water flows through filtering silk and rolled up into a storage tank filled with formalin. After, silk is retrieved and unrolled, and zooplankton identified and counted.
