Sampling Marine Environments Flashcards

1
Q

What is necessary when conducting research in a marine environment?

A

Sampling and an un-biased estimate of “what is there”

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2
Q

What sampling methods are used to sample the shallow-waterter benthos (< 30m)?

advantages/disadvantages

A

SCUBA

epibenthic organisms

  • video and cameras
  • transects
  • very useful for rocky shore habitats

Hydroplanes

  • covers a large area
  • problem with position
  • qualitative data

cores/quadrats

  • size and shape of sampling unit
  • sometimes too small
  • sometimes too large -> difficult to sample, reduces number of replicates

suction samplers
good in less then 30 m depth

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3
Q

What sampling methods are used to sample the deep water benthos?

advantages/disadvantages

A
  • ROVs
  • AUVs
  • Manned submersibles

only a few facilities that can go that deep

grab samplers (box corers)

  • to take a piece of seabed
  • only small samples possible

benthic dredges

  • unprecise (overfill, bounce around, samples escape)
  • limited penetration depth
  • semi-quantitative rather than qualitative
  • take a long time (1/h)
  • expensive due to running costs of research vessels

create a lot of material that needs processing

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4
Q

What sampling methods are used to sample the pelagic environment?

advantages/disadvantages

A

MOCNESS

  • multiple opening-closing nets
  • net minders

Longhurst-Hardy plankton recorder

Trawls and seines

  • stock assessments
  • quantification
  • difficult
  • consistent methods (depth, speed, time) -> overlap of two years when new vessels are introduced to match methods
  • the patchy distribution of species makes stock assessment difficult

Sediment Traps

  • measure vertical fluxes
  • swimmers
  • high concentration of phytoplankton might attract predators that influence the sample
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5
Q

What are some values and limitations of remote sensing?

A

Acoustics

  • sound waves and frequency
  • non-destructive sampling
  • requires calibration and data processing
  • common in fish stock assessment

Towed sensors

  • optical
  • chemical

Satellites

  • synoptic view (shows chlorophyll a distribution -> to find base of food chain)
  • address large-scale variability
  • only surface sampling possible, no deep penetration
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