Coral Bleaching (Part 2) Flashcards
What are the 2 physical things that might cause a loss of colour in corals (2 physical changes)? What can these be measured in?
- Reduced symbiont cell numbers (zooxanthellae per cm-2)
- Reduction in symbiont pigments (chlorophyll-a (pg) per algal cell)
What is the first step when calculating symbiont cells per cm-2? What needs to be taken note of?
Extract symbionts (need to note the area of the coral tissue that was used for this extraction to standardise between different samples)
How can the area of the coral tissue that was used for this extraction be calculated?
Using Image J
What does extraction of symbiont cells from a tissue produce?
A suspension of symbiont cells from the particular area
What often happens to the suspension of extracted symbiont cells before counting occurs? What needs to be noted?
Dilution - this needs to be noted (e.g., 1/10 means 1 part sample, 9 parts seawater)
The volume of the original suspension extract also needs to be noted to allow for standardisation later.
What is often used to count symbiont cells? What does this allow?
A hemocytometer/Neubauer chamber. This means that the number of cells counted can be aligned with a volume (e.g., 0.1 micoL)
How many replicates is a good number of replicate counts of symbiont cells?
4 (from the example in lecture)
If you have four replicate counts of symbiont cells for each original sample, what would be the first step in producing a value for symbiont cells per cm^-2? What is this in terms of?
Need to first calculate an average for each sample. Likely in terms of cells per 0.1 microL
Once you have an average number of symbiont cells per 0.1 microL, what is the next useful step to produce a value for symbiont cells per cm^-2?
Multiply by 10 to get cells per microL.
Once you have the average symbiont cells per microL what is the next step to produce a value for symbiont cells in the total suspension extract?
Account for dilution factor (e.g., if a dilution 1/10, multiply by 10 to get cells without dilution).
Then multiply by the original suspension extract volume to get the total number of cells in the total extract.
Once you have the average number of symbiont cells in the total suspension extract, what is the next step to get cells per cm^2?
Divide by the tissue sample surface area.
This produces density (cells per cm^2)
How can synthetic pigment per algal cell be calculated? Why does this method work?
Using the extracted symbiont cell suspension, you can extract pigments using organic solvents (as they are lipids so soluble in this), such as acetone (90%) - this is known as organic solvent extraction.
Once extracted, you can then carry out absorption spectroscopy (chlorophyll forms different complexes that absorb at slightly different wavelengths).
Which two absorbances are measured when using absorption spectroscopy to measure chlorophyll per algal cell?
630 and 663
What is the equation to get chlorophyll-a (mg/L) from absorbance values after absorption spectroscopy?
11.43(A663) - 0.64(A630)
The above values are constants.
Once you have the value of chlorophyll-a (mg/L) for the extracted suspension of symbiont cells, what do you do to get chlorophyll-a (pg) per algal cell?
Multiply by the volume of acetone used for the extraction to upscale (e.g., 10 ml of acetone, multiply by 0.01 L). This gets you the total chlorophyll extracted (e.g., microL of chlorophyll).
Then divide by the total number of cells.
How can you tell if the difference in pigments/symbiont cells between samples is significant on a graph?
If the standard deviations don’t overlap
