Using a Laser Sighted Level
A basic level with a laser pointer affixed onto it can be used to project a point onto a surface indicating the extension of a perfectly level line.
During the first trip to Nahant, a measurement was made to determine the height of the Ascophyllum nodosum canopy. At low tide, a 3 meter stick was stood up at the water mark and a laser sighted level was held against the 2 meter mark. When leveled, the laser cast a beam straight into the intertidal. The point it projected indicated the level of the intertidal which was 2 m above low tide. This process was repeated at this 2 m mark to determine that the Ascophyllum canopy began approximately 3 m above the low tide mark. (The measurement was split into 2 measurements due to the experimenters inability to reach and accurately read a level 3 m high.)
The point at 3 m above the low tide was used as the beginning of each transect
line used in this study. To measure .5 m lower in the intertidal (the 2.5
m mark), the meter stick was stood up and the laser level was held against the
.5 m mark. The stick was then moved along the transect line until the
point projected by the laser fell upon the starting point. This method was
used to move down the transect .5 m at a time until sampling ended.
Example:
In this
examples, the red bar is the measuring stick (placed at the low tide mark), the blue box is the laser sighted
level, the white line is the transect line and the orange X is the starting
point of the transect. By first conducting the above measurement, one can
determine where to start a transect at a 1.5 m height above low tide by observing where the
laser pointer hits the substrate (the orange X).