Lecture 3 - Sampling Methods

Question 1

Dredges

Answer 1

Small benthic sampling devices

rock, pipe, biological, anchor

Question 2

Trawls

Answer 2

Beam
Midwater
-rectangular midwater (opening/closing)
-Tucker (opening/closing)
-MOC-10, MOCNESS (multiple net, opening/closing)
-Issacs-Kid midwater (not o/c, not very quant)
-Otter, Engel Herring, Cobb (not very quant)

Question 3

Plankton Nets

Answer 3

Conical plankton net (vertical or horizontal)
-o/c variations: bongo (SIO), MOCNESS (WHOI)

Hardy Plankton recorder - captured plankton and records horizontal distributions

Question 4

Advantages to Nets

Answer 4

Relative cheap/effective way to collect organisms
Can sample huge values
Can collect the bodies intact
Quantitative if done properly
no light needed to see organisms

Question 5

Disadvantages of Nets

Answer 5

Everything is mixed up, no horizontal distribution
No info about behavior, orientation of organism
Tend to be damaged due to contact w/ net, rocks, etc
Must be processed to be useful, sort, ID, measured, etc

Question 6

Pumps

Answer 6

Move water past orifice to filter organisms

Can produce high resolution data on vertical/horizontal distributions, but only on very small organisms

Question 7

Grabs and Cores

Answer 7

sample soft sediments and organisms in sediments

Question 8

Free vehicles

Answer 8

Go down free and bring up when acoustic transponder releases weight
-traps, cameras, respriometers

Question 9

Advantages of Manned Submersibles (HOV), ROVS, and AUVs

Answer 9

Can see organisms in environment
Horizontal distribution and orientation intact -structure remains visible
Important for fragile or hard to collect animals (gelatinous, limited locations, living in rocks)

Question 10

Disadvantages of Subs, ROVs, AUVs

Answer 10

What you see might not be reality
-organisms might be sensitive to light
-organisms might be sensitive to sound and avoid
Difficult to quantify results

Question 11

Acoustic results

Answer 11

Based on backscattering of sound by organisms

-dependent on organism size and composition

Question 12

Video

Answer 12

Towed video cameras with computer analysis of images to give real-time identification as well as distributional information

Video Plankton Recorder
-best for smaller species and lower diversity areas

Question 13

Bathysphere

Answer 13

Beebe and Barton

Down to 4050 ft, sphere with cable cord/phone line to surface

Question 14

Bathyscaph

Answer 14

TRIESTE launched in 1953
Used to survey USS Thresher wreck at 1.5 miles down (1963)
Replaced by Trieste II in 1963, which retired in 1980s

Question 15

DSV Alvin

Answer 15

Most effective of all mini subs

Question 16

Manned sub to get to the greatest depth

Answer 16

Triste