Grid System for Mussel Location and Movement

We decided that a method was needed to measure and document the movement of the James River spinymussel (JRSM). The concept behind this grid was so that we can get a better understanding of how much a mussel moves over time.

Designing the Grid

The grid we used to mark the location and movement of the JRSM was determined through the engineering design process. First, we generally brainstormed ideas and developed a list of constraints. The grid needed to accurately identify the location of a Spinymussel using either coordinates or a grid system. Our class split into three groups, who each developed their own idea on marking the mussels location.

The first idea was to make a five meter by five meter grid using pvc pipe. String was attached to either side of the PVC square in 1 inch increments in order to form the grid which is designed to give an accurate assessment of mussel movement. Each square in the grid was given a number and a letter to mark the mussel’s location.
The second idea used two stakes with a string across the river and measure along the string and up to the mussel.
The third idea was to put stakes on the river bank, 5 meters apart, and then measure the distance from the stake to the mussel and the compass heading from the closest stakes upstream and downstream of the mussel.

Before these ideas were implemented in a river scenario, they were tested on a makeshift river built out of string placed on grass. Our second iteration involved a trip to a nearby river to test each method. After seeing prototype in the field, we discussed the advantages and disadvantages of each process, and we voted. We decided that the third idea was the most feasible.

Setting Up and Using the Grid

We took two trips to the Rocky Creek Research Site in order to set up our method. We used 20 pieces of 2 foot rebar and staked them out 5 meters apart from each other on the river bank. We measured the distance between them and the compass direction, starting from the first stake down river. We sprayed the stakes with orange spray paint to make them more visible and used black Sharpie to make dashes on the stakes so we can determine the number of the stake.

Now, when we find a mussel, we measure both the angle and distance from the upstream and downstream posts to the mussel, allowing us to triangulate the exact location of the mussel and, therefore, track it’s movement