Throughout history, the ocean has played an integral role in shaping the identity of Atlantic Canadians. It was the mainstay of the first people on this land, the natives; it brought the first Viking explorers, as well as later adventurers, to our shores; it lured the first Western European settlers here with its rich bounty of fish. Even today, the people of this region use the ocean as a source of transportation, recreation, employment, and food; not to mention as a source of inspiration for our songs, stories, poems, paintings and carvings. If you go to any fishing village along our coastline you will see, hear and taste the impact this rich resource has on our lives. No other force has shaped this region's culture and people as much as the ocean.Hydrography
Hundreds of years ago, explorers charted the ocean depths by dropping lead lines from their boats to the ocean floor. While this may have been sufficient then, increasing sea-lane traffic has fueled the need for more accurate information on the depth of the water and the contour of the ocean floor. Offshore drilling activities, fishing boats, recreational crafts, cargo ships, all require the safe navigation of Canada’s waterways. With sophisticated sounding equipment, modern day hydrographers chart these physical features, faster and more accurately than ever before.
Making Charts:
When making nautical charts, great care must be taken to have accurate representations of the coastline. Researchers take detailed measurements from the shore and the water to gather data to reproduce the coastline on charts.
Typically, two main types of sensing systems are used to determine the water depth and the contours of the ocean floor. A sidescan sonar sends out acoustic pulses sideways and downward as the research vessel tows it. Different materials on the sea-floor will reflect the pulses at different speeds and different levels. The towed “fish”, as it is called, records all of this data, which can then be used to display a profile of the sea floor, and indicate its composition. The second system that is often used is the multi-beam sonar, which is usually attached directly to the research ship, instead of being towed like the sidescan sonar. This system also sends out acoustic pulses, and then measures and records the time it takes for the pulses to return. The depth of the water and the bottom’s profile can then be determined.
Bottom Composition:
The composition of the ocean floor in a given area has an impact on anchoring vessels, cable and pipeline placement, biological communities and the types of fishing methods that can be used in that area. Researchers also study the ocean floor to determine the probability of fossil fuel deposits in that area, and to determine the impact of exploring for and development of these deposits on the environment.
In Atlantic Canada, many different types of equipment are used to obtain bottom samples. With some devices, the sample is obtained blindly, meaning the researchers hoist a collector over the side of the vessel without seeing exactly where it lands. This is the case with this sediment sampler. Heavy devices are driven into the ocean bottom by its weight and gravity, to obtain a core sample of the bottom. (see pictures)
Unfortunately researchers have no way of sampling very precise areas with these two pieces of equipment. The Benthic Video-Grab was designed to overcome this obstacle. It has two video cameras, a black and white one that is used to guide the device to a spot on the ocean floor, and a high resolution colour camera that is mounted above the sampling bucket. The Benthic Video-Grab can be triggered to take a sample from the ship when the researchers are satisfied with its placement. A hydraulic ram creates a force up to 1 tonne to slowly force the sampling bucket into the sea floor. The lid then closes and the device is hoisted to the surface where the sediments can be analyzed.