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BIO262 - oceanography > research cruises and sampling > Flashcards

research cruises and sampling Flashcards

1
Q

what is very useful in Measuring physical parameters

A

electricity

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2
Q

5 main physical parameters we measure

A
  • light
  • temperature
  • turbidity
  • salinity
  • transparency
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3
Q

how do we measure water temp that’s directly infront of you + deeper water that can’t be accessed

A
  • thermometer
  • thermocouple
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4
Q

4 things that are Effected by temp of water

A
  • Biochemical reactions e.g. respiration, photosynthesis, degradation, …
  • Oxygen concentration: warmer water holds less oxygen
  • Biological functions e.g. spawning and migration, reproduction success and growth pattern
  • Long-term population declines of fisheries and other organism
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5
Q

2 things that increase water temp

A
  • Power stations
  • Climate change
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6
Q

what is salinity and its formula

A
  • amount of inorganic ions dissolved in certain amount of water (unitless)
  • Salinity = 1.80655 x Chlorinity
  • chlorinity = grams of chloride ions precipitated from 1 kg seawater by Ag+
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7
Q

4 ways to measure salinity

A
  • Can dry everything out from water sample and weigh the salt left behind and divide by the volume
  • Can stick silver ions into water to react with the chlorine – that will precipitate out – weigh precipitation and multiply by 1.8 to get the salinity
  • Refractometer: salt content affects refractivity of water
  • Electrical conductivity sensor (e.g., in CTD): salt content affects how well water conducts electricity
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8
Q

why would we want to measure the amount of light in water

A

indicate how capable plankton are to photosynthesise aka primary production rates

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9
Q

2 ways to measure the amount of light in water

A
  • calibrate the change in resistance to give indication of light intensity at that point e.g., a light meter - consists of two main parts: (i) data logger that stores and displays the light readings (ii) light sensor that’s connected to the data logger via a cable
  • use Light meter attached to FRRf, light profiler
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10
Q

way to measure Water transparency

A
  • Secchi disk— a white or B&W disk; lowered vertically until the disk disappears from sight; the corresponding depth is the Secchi depth (Zs)
  • very clear water, Zs > 50 m
  • coastal waters, 2 m < Zs < 10 m
  • some estuaries, Zs < 1 m
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11
Q

how can we use Secchi disk to calculate water transparency

A
  • By one rule of thumb, the Secchi disk disappears at 16% of the surface irradiance - one can calculate the attenuation coefficient based on the Secchi depth
  • k = ln (Iz / I0)
    —————–
    zs
  • Iz = Light intensity at particular depth
  • I0 = Light intensity at surface
  • -z = water depth
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12
Q

what is Turbidity and its units

A
  • Amount of suspended matter (living or inert) - particles in the water - penetration of light
  • FNU (Formazin Nephelometric Unit), FTU (Formazin Turbidity Unit), NTU (Nephelometer Turbidity Unit)
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13
Q

method for measuring turbidity

A
  • Nephelometer or turbidity probe (light beam into the water - light will be scattered by any suspended particles - detect the amount of light detected back)
  • Base on a calibration using a Formazin standard (forms small size particles)
  • The more light is detected the more particle are in the water
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14
Q

Non-electrical way for measuring turbidity

A
  • filtration of water sample on pre-ashed filter – drying - take the weight
  • Can take further by sticking the dried material in oven at 550°C for 6hrs - Determine content of organic matter
  • ## Unit: mg/l
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15
Q

what does CTD rosette do

A
  • Vertically profiles water column
  • Takes discrete water samples at known depths
  • Gives real time ancillary data
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16
Q

what do Sediment traps and Submersible pumps do

A
  • Collect particulates as they fall through the water column
  • Allows quantification of exports
  • SAPS used to quantify low concentration elements
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17
Q

what do Buoys, moorings and AUVs do

A
  • Collect data without human involvement
  • Can be deployed for long periods
  • May be stationary (buoys), drifter drogues (Argo buoys) or undergo active movement (AUVs)
  • e.g. buoys will measure in real time the size and direction of waves based on how it moves the buoy
  • e.g. argo buoys get left in water to log temp and salinity throughout water collum
  • e.g. AUVs drive around and collect surface conditions
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18
Q

what do UAVs, Gliders, UORs do

A
  • Provide 2D and 3D maps of parameters
  • Generally large enough to carry a suite of instruments for multiple measurements
  • May be towed (UOR), guided (Autosub) or autonomous (gliders)
  • Data may be transmitted through wires, via radio, via satellite or logged on board for later recover
19
Q

what do Drogues, Dyes, Bacterial spore do

A

Allows the following of the flow of water

20
Q

5 ways to collect water data

A

1.CTD rosette
2. Sediment traps and Submersible pumps
3.Buoys, moorings and AUVs
4.UAVs, Gliders, UORs
5.Drogues, Dyes, Bacterial spore

21
Q

main way to measure chemical parameters of the water

A

CTD rosette (More difficult to use electricity)
- Used to collect water body samples + map what’s going on in the water collum
- Samples taken to the lab to test

22
Q

what is the process in the lab after using CTD rosette to collect water samples

A
  1. filtering : Filters things out of the water using different size membranes - look at low concentration of everything
  2. nutrients : use equipped equipment to measure concentration (of usually N, P and Si) through change in colour down to nano-molar concentrations
  3. Gas chromatography and Mass spectrometry : Allow identification (of molecules + of radioactive and stable isotopes) and quantification of chemicals in water through changes in carrier materials - Commonly used for C:N measurements and dissolved gas quantification
  4. HPLC : Measures pigment concentrations of plankton by using system similar to ink chromatorgraphy – can get an idea of the taxonomy present - Light absorption of pigments is diagnostic of plankton groups
23
Q

main thing we focus on whilst Measuring biological parameters

A

sampling plankton

24
Q

4 ways we collect plankton whilst Measuring biological parameters

A
  1. Simple plankton net
  2. continuous plankton recorder (CPR)
  3. Longhurst Hardy Plankton Recorder (LHPR)
  4. MOCNESS and MultiNet
25
Q

how can we use Simple plankton net to collect plankton

A
  • Horizontal / vertical / oblique tows
  • Replication
  • Quantify
26
Q

how can we use continuous plankton recorder (CPR) to collect plankton

A
  • Towed behind “platforms of opportunity”
  • Traps plankton on continuous band of silk mesh + stored in preservative
  • Abundance estimated by colorimetry and subsampling
  • Developed by Sir Alister Hardy in 1925
27
Q

what is LHPR – Longhurst Hardy Plankton Recorder

A

Incorporates CTD with net, allowing targeted plankton collection

28
Q

what is MOCNESS and MultiNet

A
  • More structured collection of samples
  • Nets can be opened and closed to allow collection of samples from discrete depths
29
Q

4 ways we can calculate the abundance of plankton collected

A
  1. microscopy
  2. Coulter counters
  3. Flow cytometer
  4. Flowcam
30
Q

what is abundance

A

Organisms per unit area or volume E.g. 100 cells L-1

31
Q

what is microscopy and its disadvantages

A

Count based system
- Human error, miss smaller cells
- Very labour intensive
- Slow

32
Q

what is Coulter counters

A
  • Movement of a sample between two reservoirs of water
  • Particles in the sample flow through a narrow channel, changing the electrical resistance across the channel
  • This change is registered as a ‘count; of a particle
33
Q

what is Flow cytometer

A
  • Measures different types of picoplankton (>2mm) - can get info on amount and size
  • Even in the most nutrient poor waters cell counts >100,000 cells/ml
34
Q

what is Flowcam

A

Use data analysis to identify zooplankton at different taxa

35
Q

4 ways to calculate biomass of collected plankton

A
  1. Fluorometer
  2. Remote Sensing
  3. Cell counts
  4. Measure Primary production
36
Q

what is biomass

A

Organism C per unit area or volume E.g. 100 mg C L-1 OR Chlorophyll a E.g. mg chl a m-3 or mg chl a L-

37
Q

what is Fluorometer

A
  • Measures chlorophyll (usually from a ship)
  • Give indications of concentration, not numbers
  • High resolution
  • Can be used to profile or from water supply along transect
38
Q

what is Remote Sensing and its disadvantages

A
  • Use sensors mounted on satellites: translate ocean colour of water leaving irradiance
  • Light entering water = downwelling irradiance
  • Light redirected back to surface = upwelling irradiance
  • Phytoplankton absorb blue & red wavelengths, Reflect in green
  • problems:
  • Only detect surface chl a
  • Reflectivity of sediments and non-phyto particles can be high: estuaries
  • Not so great at night (visible spectrum)
39
Q

problems associated with using Chl a to calculate biomass of plankton

A
  • biomass varies depending on:
    Species
    Light
    Nutritional status
  • Chl a and biomass do not always correlate
40
Q

what is cell counts and its disadvantages

A
  • Cell dimensions, geometric shape: biovolume
  • Literature carbon:volume conversion figure
  • Time consuming, many errors
  • Still used for microzooplankton
41
Q

what’s the Measure of Primary production and 2 ways we can do it to calculate plankton biomass

A
  • C fixation = more accurate and descriptive term
  • Radiant energy -> chemical energy
    1. 14C method
    2. Active Fluorescence
42
Q

how can we use 14C method to calculate plankton biomass

A
  • Look at how quickly phyto take up carbon by measuring radioactive bicarbonate H14CO3-
  • Bottle 1 -> light -> photo & resp
  • Bottle 2 -> dark resp
  • Amount of 14C in phyto measured: scint. counter E.g. units: mg C m-3 h-1
43
Q

how can we use Active Fluorescence method to calculate plankton biomass

A
  • In situ measurement of activity in photosystem 2
  • Measures rate of and quantity of light absorption by the cell’s photosynthetic apparatus
  • Measurement of the process rather than the effect
  • Combination of these parameters along with measured photo synthetically available radiation allow a calculation of gross photosynthesis
44
Q

3 ways we can correlate ocean parameter data with

A
  • Sea surface temps
  • Nutrient supplies etc.
  • Produce predictive models for future…

BIO262 - oceanography (13 decks)

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