Final project: The sediment trap

Origin of the project

I was contacted by a marine biology researcher whose studying "the ecological factors that influence tropical shallow-water black coral diversity by focusing on the functional link between their habitat and diversity."

One of these factors is the sedimentation occurring in the coral reef.

They need a device that will be put on a coral reef to catch the sediments over 1 year: a sediment trap.
The sediment will be catch in a cylindrical container. The sediments will form different layers allowing to study how their density and composition change across time.
If possible, markers should be dropped each month in the container as timestamps.

Existing devices

Hydro-bios sediment trap

Requirements

• the device must survive one year in the ocean at a depth of 30 m to 50 m
• Sediment storage will be a plexiglass tube
• Sediment input will be a grid with 1 cm square holes. It will be 3 cm high.
  Its purpose is to create calm spaces where the water will be still and the sediment wil be able to fall down in the trap (it will be installed in a coral reef with strong water flow).
• The grid will be a circle with a 20 cm diameter.
• A disk will be dropped in the sediment storage every 30 days to act as timestamps.
• The trap will be attached to the bottom of the sea.
• The sediment storage must be easily removed from the trap while underwater (to be sealed).

Conceptual sketches

Col

Col

The sediment trap can be divided in three parts:

• a funnel, in black. Its top is a grid. This grid's purpose is to create a calm space catching the sediments and allowing them to fall in the funnel.
• A sediment collector tube, in red. Its goal is to obviously to collect the sediments. It must be removable and is contained in another tube which is the body of the trap.
• A disk dispenser, in blue. It will drop a disk in the sediment collector tube each month. these disks will serve as timestamp markers creating sediment layers.