Sampling Marine Environments Flashcards
What is necessary when conducting research in a marine environment?
Sampling and an un-biased estimate of “what is there”
What sampling methods are used to sample the shallow-waterter benthos (< 30m)?
advantages/disadvantages
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
What sampling methods are used to sample the deep water benthos?
advantages/disadvantages
- 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
What sampling methods are used to sample the pelagic environment?
advantages/disadvantages
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
What are some values and limitations of remote sensing?
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