This powerpoint presentation is a photo documentary of exploring the ocean floor at the Charleston Bump.  In summary much remains to be known about deep sea life
and habitats, sampling can be a challenge at deep depths, a variety of techniques that include quantitative and non-quantitative methods must be used and visualization of the habitat and organisms using a submersible and underwater camera provides
a wealth of information

Wenner, Elizabeth L.

South Carolina State Documents Depository

Sampling the Charleston Bump: 
Finding a Needle in a Haystack
A Photo Documentary 
by
Elizabeth Wenner, Ph.D. 
Marine Resources Research 
Institute, SC Department of Natural 
Resources, Charleston, SC
Photos courtesy of E. WennerDigitized by South Carolina State Library
Research platform
A research platform intended for studying deep sea 
habitats should include the following characteristics:
• a stable platform capable of handling rough seas
• outfitted for multiple purpose sampling
• manned with a capable crew
• modern navigation technology
• provide on site sampling and video documentation
The Research Vessel
Seward Johnson, of 
the Harbor Branch 
Oceanographic 
Institution (HBOI)
Photo courtesy of HBOIDigitized by South Carolina State Library
How to Get There from Here?
• sample small scale features and animals in situ (i.e., in 
their natural habitats)
• perform in environments with complex topography
• allow for human observation of habitats and associated 
organisms
A manned submersible is able to do the following:
Photos courtesy of E. Wenner (left) and HBOI (right)
JSL-II’s mechanical 
sampling arm
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The submersible Johnson Sea-Link II is 
deployed from the R/V Seward Johnson 
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Digitized by South Carolina State Library
Choose your gear carefully
The Charleston Bump is characterized by rocky substrate 
(seafloor) with many exposed ledges.  There are limited 
choices in the types of gear that can successfully sample 
such irregular substrates.
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Photos courtesy of NOAA Ocean ExplorationDigitized by South Carolina State Library
What not to use!
Sampling gear such as trawls can’t be used on a rocky-
bottom seafloor, as they would be torn up and would 
hang-up on the rock outcrops as they are towed.
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Figure courtesy of NOAA
Trawls are intended for sandy and soft seafloor habitat areas.
Digitized by South Carolina State Library
Rugged is good!
Scientists studying the Charleston Bump must use 
relatively indestructible gear, such as dredges, that can 
withstand being dragged over rocks.
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Photo courtesy of E. Wenner
An inexpensive but nearly indestructible pipe dredge. i i  t rl  i tr ti l  i  r .
Digitized by South Carolina State Library
Sampling gear is attached 
to strong wire that is 
wound around a drum.  
Typically, the wire 
consists of many strands 
of small diameter steel 
wires that are woven 
together, making it very 
strong.
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The wire is payed-out and 
hauled-in using a winch.  
Some winches can hold 
miles of wire.
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winch with steel 
wire on a drum
Photos courtesy of E. WennerDigitized by South Carolina State Library
When deploying an instrument that needs to be 
towed, determining the amount of wire to let out 
is very important.  The amount will vary depending 
on the wire’s weight and drag, as well as the 
towing speed and water’s depth.
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Types of Sampling Gear Used at the 
Charleston Bump
Quantitative sampling 
gear allows for 
sampling of a known 
area of the sea floor, 
or a known volume of 
water.  The gear must 
be capable of being 
deployed so that 
sampling is efficient.
Non-quantitative
sampling gear is 
designed to provide 
representative 
organisms but not to 
provide valid 
abundance 
measurements for a 
particular habitat.
Digitized by South Carolina State Library
Types of Sampling Gear Used at the 
Charleston Bump
Quantitative sampling 
gear allows for 
sampling of a known 
area of the sea floor, 
or a known volume of 
water.  The gear must 
be capable of being 
deployed so that 
sampling is efficient.
Non-quantitative
sampling gear is 
designed to provide 
representative 
organisms but not to 
provide valid 
abundance 
measurements for a 
particular habitat.
Deciding what gear to use largely depends 
on the habitat being sampled.
Digitized by South Carolina State Library
Neuston nets
These types of nets are towed at the surface to sample 
plankton – small organisms that are unable to swim, but 
instead drift with the currents.  Scientists can determine the 
number of organisms per unit volume of water filtered.
Quantitative Sampling Gear Used at
the Charleston Bump
Photos by Project Oceanica (left) and E. Wenner (right)
The neuston net has a large rectangular opening.
Digitized by South Carolina State Library
Neuston nets
Quantitative Sampling Gear Used at
the Charleston Bump
The neuston net is 
towed at the surface 
for a measured 
length of time.  
Since the area of 
the net opening is 
known, the volume 
of water passing 
through the opening 
per minute can be 
determined.  
Photos by Project OceanicaDigitized by South Carolina State Library
Bongo nets
Bongo nets are deployed to sample 
plankton at mid- to near-bottom 
depths. They are also used to 
determine the number of organisms 
per unit volume of water filtered.
Photos by Project Oceanica (left) and E. Wenner (right)Digitized by South Carolina State Library
Bongo nets
Bongo nets at the surface….       
…and being lowered at greater depths. 
Often, the two nets 
have different mesh 
sizes so they 
capture different 
sized particles and 
organisms.
Photos by Project OceanicaDigitized by South Carolina State Library
Photos by Project Oceanica
When each tow is completed, 
the material caught within the 
net (either neuston or bongo) is 
washed into a cod end, then 
transferred into a bucket.  
cod end
In the lab, the water is carefully 
poured through a sieve (a wire 
screen) to separate the plankton.
Digitized by South Carolina State Library
Video and Still Camera
A large amount of data collected for studies of the Charleston 
Bump are in the form of visual images.  Both video- and still 
cameras that are mounted on the submersible are used to 
examine and record the seafloor habitats.  
Video camera system 
mounted on the JSL-II 
submersible.
Photos courtesy of HBOI (left) and by Project Oceanica (right)Digitized by South Carolina State Library
Video and Still Camera
Video transects are made during the dive.  A video transect is 
a timed segment of video recorded as the sub moves along a 
straight path at a constant speed.  These transects allow for 
the determination of numbers of organisms per unit area 
along the sampling line.  This type of sampling is dependent 
on having accurate start and end positions.
The tapes are analyzed on board the ship.  
Organisms and other habitat features 
encountered during transects are recorded.
Photos courtesy of NOAA Ocean Exploration (left) and by Project Oceanica (right)Digitized by South Carolina State Library
Non-Quantitative Sampling Gear
As described earlier,
non-quantitative sampling 
gear is designed to 
provide representative 
organisms but not to 
provide valid abundance 
measurements for a 
particular habitat.
These types of sampling 
gear were used in early 
voyages by deep sea 
explorers.
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Illustration courtesy of 
http://life.bio.sunysb.edu/marinebio/challenger.html
Digitized by South Carolina State Library
Non-Quantitative Sampling Gear
Non-quantitative 
types of gear may not 
be “high tech” but 
they are effective for 
collecting organisms.
Different gear are 
designed for different 
habitat types.
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Illustrations courtesy of 
http://life.bio.sunysb.edu/marinebio/challenger.html
Digitized by South Carolina State Library
The pipe dredge is an example of a 
non-quantitative type of gear.  It is 
designed to drag along the bottom and 
scrape up sediment, rocks and 
attached organisms.  It weighs about 
450 lbs and is attached to a wire by a 
swivel that allows the device to turn 
without twisting the wire. 
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swivel
Non-Quantitative Sampling Gear 
Used at the Charleston Bump
The pipe dredge 
may be low tech 
and unglamorous, 
but it is effective!
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Photos by Project OceanicaDigitized by South Carolina State Library
The pipe dredge includes a weak link 
that is designed to break should the 
dredge get snagged on a rock.  A 
safety line is attached at the base 
that would then upend the dredge 
and flip it over to free it from a hang 
and allow it to be retrieved.  
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At the base of the pipe, holes have 
been drilled into the iron, and a mesh 
screen is secured inside.  These 
perforations allow water to pass 
through during the dredge process.
drilled holesrill  l
safety line
Photos by Project OceanicaDigitized by South Carolina State Library
Does it Work?
Our first haul at the 
Charleston Bump was 
disappointing, because we 
didn’t “catch” anything. 
Not enough wire had been 
payed out to allow the 
dredge to effectively stay 
on the seafloor. 
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Empty!
Photos by Project Oceanica
The pipe dredge is deployed from the ship’s stern.
Digitized by South Carolina State Library
Does it Work?
On our second attempt, 
we used an amount of 
wire equal to two times 
the water depth.  With 
this strategy, the dredge 
worked well! 
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It was retrieved with corals, hydroids, 
sponges, rocks and sediment.
Photos by Project Oceanica
Full!
Digitized by South Carolina State Library
Some of the material that was 
collected in the dredge 
Tree coral l
Colonial corall i l l
Octocorals
Small rockll 
Photos by Project Oceanica and SERTC (upper right)Digitized by South Carolina State Library
Passive Gear
Scientists also use passive gear – or gear that is stationary 
– such as baited traps to collect motile organisms.  Below is 
a carrion trap used at the Charleston Bump.
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Photo courtesy of E. WennerDigitized by South Carolina State Library
Basically, a carrion trap is a bucket 
filled with rotting oysters!  It is 
placed on the seafloor by the 
submersible and is allowed to stay 
on the seafloor for at least 24 
hours.
While it’s on the seafloor, 
organisms are attracted to the 
new food source and climb in!
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Photo courtesy of E. Wenner
What on earth is a carrion trap?
Digitized by South Carolina State Library
What on earth is a carrion trap?
When it is retrieved, 
the oysters are 
washed onto a sieve 
and the organisms 
are saved.
This devise is 
designed to attract 
motile organisms 
that are often 
dispersed on the 
seabed.
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Photo courtesy of E. WennerDigitized by South Carolina State Library
Some of the organisms that were 
collected in the carrion trap
Eugonatonotus crassus Plesionika sp.
Bathynectes longispina
Lysianassid
amphipod
Photos courtesy of SERTC and J. McLelland (lower right)Digitized by South Carolina State Library
Summary
• Much remains to be known about deep sea life 
and habitats
• Sampling can be a challenge at deep depths
• A variety of techniques that include quantitative 
and non-quantitative methods must be used
• Visualization of the habitat and organisms using 
a submersible and underwater camera provides 
a wealth of information 
Digitized by South Carolina State Library
SERTC would like to thank:
NOAA/Ocean Explorer 
Project Oceanica/Dr. Leslie Sautter
Harbor Branch Oceanographic Institute
Jerry McLelland/Gulf Coast Marine Laboratory
For their photographic contributions
Digitized by South Carolina State Library


Sampling the Charleston Bump: finding a needle in a haystack

https://dc.statelibrary.sc.gov/bitstream/10827/11318/1/DNR_Sampling_the_Charleston_Bump_2005.pdf

Sampling the Charleston Bump: finding a needle in a haystack

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