2.1 CCGS JOHN P. TULLY
2.2 Submersible DELTA
2.3 Remote operated vehicles ROV
2.4 100 kHz sidescan sonar system
2.5 Huntec Deep-Tow high resolution seismic profiling system
2.6 Multibeam swath bathymetry
2.7 Moorings
2.8 IKU-grab
2.9 Shipek grab sampler
2.10 Piston corer
2.11 AGC ice-hole camera
2.12 Niskin water bottles
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Using the Canadian Coast Guard Ships JOHN P. TULLY and VECTOR as survey ships, high-resolution geophysical surveying was accomplished using an EG&G sidescan sonar, a Simrad sidescan sonar,a hull-mounted Kongsberg-Simrad EM 1002 system and a Huntec Deep-Tow seismic system (system details see below). These acoustic instruments were towed by the research vessels while running survey lines. The multibeam system was hull-mounted. Initially surveying was done to map the distribution of the hexactinosidan sponge reefs and to define the general character of the sponge reef complexes. Acoustic observation and mapping was done normally at night when submersible diving and general afterdeck work was not possible. Two areas of seafloor in Hecate Strait were surveyed with a close line spacing to allow the construction of sidescan sonar mosaics. The mosaics were constructed using MUSE software (an ultra high sampling digital acquisition system) to form a complete map of the selected seafloor areas.
Click on the thumbnail to see the mosaic of northern Hecate Strait
The sidescan sonar produces black and white images of the seafloor, which are comparable to airphotos, showing the areal distribution of the sponge reefs. The Huntec Deep-Tow seismic system provides information about the thickness of the sponge reefs. A combination of sidescan data with Huntec Deep-Tow data gives a three dimensional, detailed picture of the size, thickness, lateral distribution and state of the sponge reefs (click here to see an example). By means of this integrated geophysical data set, representative sponge reef areas were selected and studied by direct observation with the submersible DELTA along line transects. This was the first direct examination of hexactinosidan sponge reefs anywhere in the world.
Click here for more information about CCGS JOHN P. TULLY
Click here for more information about CCGS Vector
Click on the thumbnail for pictures of CCGS JOHN P. TULLY
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18 dives were done providing us with photos (photosea external bulk loaded 35 mm camera, internal 35 mm camera, internal digital camera) continous external Hi8 video (about 30 hours) biological and sedimentological samples by means of a mechanical manouvering arm (equiped with a grab sampler and a suction sampler). The mechanical arm is used to pick up rock samples, sponges and other organisms. The samples are then placed in a collection bag.
The suction sampler (slurp gun or super sucker) is a tool to excavate sediment samples into mesh bags. There are two separate bags attached for each dive with mesh sizes ranging between 1 cm and 0,5 mm. All diving dates (latitutes, longitutes, date, time, water depth, range, water temperature, salinity, pH, oxygen content) are recorded on Hi8 mm video tape both visually and encoded. The data are taken from the tape and placed on a floppy disc for further use.
Click here for more information about DELTA
Click here for pictures of DELTA
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ROV operations, collecting video and still imagery and sponge samples, were undertaken in in June 2002 using a Phantom® HD2+2 ROV on the Fraser Ridge reefs and the Hecate Strait reefs. The ROV was linked by a GPS with the ship's telemetry, allowing accurate plotting of the transects. The ROPOS system was used in October 2003 on McCall Bank.
Click here for more information about ROPOS
Click here for pictures of the ROV
®Phantom is a registrered
trademark of Deep Ocean Engineering,
Inc.
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100 kHz sidescan sonar system with digital acquisition capability: During the cruise two different sidescan sonar systems (EG&G, Simrad) were used creating mosaic pictures of the seafloor. The mosaics were constructed MUSE software (an ultra high sampling digital acquistion system) to form a complete map of the selected seafloor area.
Click here for pictures of the Sidescan Sonar system
2.5 Huntec Deep-Tow high resolution seismic profiling system
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The Huntec Deep-Tow system is a boomer system that can be deeply towed to reduce signal spreading loss and bring the source and receiver close to the seabed for improved resolution. In addition the system is ocean heave or wave compensated to reduce artifacts from source and receiver motion. This system produces excellent seismic profiles, which are readily intrepreted at sea, showing (among other information) the thickness and relief of the sponge reefs. In concert with sidescan sonar data, it is the perfect tool to provide the required seafloor information to select diving and sampling locations.
Click here for more information about Huntec
Click here for pictures of the Huntec system
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The Canadian Hydrographic Service in cooperation with the Geological Survey of Canada used a hull-mounted Kongsberg-Simrad EM 1002 system to collect these data. This marine mapping technique has revealed the form of the reefs and their distribution and allows other observations to be geo-referenced. Multibeam swath bathymetry data allow a very accurate (10 cm vertical precision) digital elevation model of the seabed to be constructed and imaged. With this data, the sponge reefs complexes can be viewed in greater detail, providing a much better understanding of their distribution and form in various settings.
The multibeam surveys were done in Georgia Basin from 2001 to 2002, and in Queen Charlotte Basin in July and August 2003.
Multibeam imagery shows a high variability of reef forms found in Queen Charlotte Basin and in Georgia Basin. By means of precise technique, two smaller sponge reefs are previously discovered on McCall Bank and on Fraser Ridge in the Georgia Basin.
Click here for more information about multibeam swath bathymetry
Click here for Multibeam maps
2.7 Moorings
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Sites selected for moorings were within the northern reef complex in Hecate
Strait. Three moorings were deployed. The moorings were equiped with Aanderra
RCM-4 current meters and Baker sediment traps. Current meters were located
at elevations of 4.6 and 25 m above bottom. Sediment traps collected material
in 10 sample cups. A Seabird 911 + CTD outfitted with a Wet Labs transmissometer
collected temperature, salinity and transmissometry data.
Click here for more pictures
2.8 IKU-grab
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The IKU-grab was used to collect undisturbed seafloor surface sediment samples. The grab volume is 0,5 m3. By means of this grab we recovered hundreds of siliceous sponge skeletons for further investigations. In addition it was used to obtain sediment samples for a variety of analyses (clay analysis, organic carbon analysis, etc.) as well as benthic foraminifera.
Click here for pictures of the IKU-grab
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The Shipek grab sampler is an effective tool to collect small sediment samples in a very short time. This sampler was used when foul weather made deployment of the IKU grab impossible, or when samples were complete the sample grid, and provide ground truth.
Click here for pictures of the Shipek grab sampler
2.10 Piston corer
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By collecting piston cores we are able to examine the birth and growth of the hexactinosidan sponge mudmounds and the development, and cycles of these features through time. Processes concerning lithification of the sediment, and the reaction of the siliceous skeletal material (dissolution, recrystallisation) will be studied in detail.
Click here for pictures of the Piston corer
2.11 AGC ice-hole camera
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This system was used to photograph the sponge reefs remotely when the weather did not permit deployment of Delta or when additional information was required to augment the dive and geophysical information. Although there is no direct control system while the camera taking the pictures, very acceptable results were achieved. It was just such a remote system which provided the first pictures of the sponge reefs more than 10 years ago.
Click here for pictures of the AGC ice-hole camera
2.12 Niskin water bottles
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Water column samples were collected at standard oceanographic depths using Niskin bottles to obtain information concerning water properties (temperature, salinity, silicate, oxygen and nutrient concentrations).
Click here for pictures of the Niskin water bottles
last changes 22.03.2005