Collection Process

Planning the Survey

To ensure a comprehensive survey of the weeds present in the lake and a thorough sample collection, we created a guide map highlighting areas we intended to survey. A tour was taken of Indian Lake to observe problem areas and map out the collection points. The density of collection points was directly proportional to the density of plant life and this was made by visual inspection of the areas during the tour. Finally input from local residents on areas with a problematic lakebed was taken into account and superimposed onto the survey map. The final 2013 survey map was comprised of 117 collection points distributed through 27 different transect lines. These lines used prominent shoreline features such as inlets or outcroppings as reference points. A perimeter survey of Indian Lake was also performed to determine the percent of the shoreline covered by emergent plants. As GPS data was needed to remain accurate in our collection. We tried different options including smartphone and in-car systems, but settled on a USB data logger. It was chosen over the other options due to its ability to catalog data directly to a computer, as well as having a higher degree of accuracy in 2013. With the advancement of technology, the 2015 survey was conducted using a smartphone app that was just as accurate as a USB data logger, was much cheaper, and was easily uploaded to a computer through email. In 2015 the group resurveyed the same points that were previously done in 2013 along with additional data points. A survey of Little Indian Lake was also conducted in 2015.

Weed Coverage Area

At each collection point six pieces of data were recorded: date and time, depth, percent cover, bio-volume, and the species of plant collected by the percent cover sample and by the bio-volume sample. In 2015 the bio-volume test was not recorded. A modified aluminum gravel rake was used to evaluate the area covered by a particular weed. The rake was heavily weighted and had a long rope attached to the handle. A weight was attached to ensured that the rake would drop quickly to the bottom every time, landing tines down for consistent collections. At each collection point the rake was submerged into the water, dragged slightly across the bottom, and then raised back into the boat to catalog the samples collected.

After dropping, dragging, and pulling up the rake, the density of the collected sample was catalogued using the relative abundance scale below. It was developed by the U.S. Army Corps of Engineers and modified by Cornell. This data was then recorded alongside the correct transect point, along with the other survey information.

Abundance Scale

Identification of Invasive and Non-Invasive Species

Based on the ESS survey [5] we had familiarized ourselves with the species we expected to find in the lake. We were able to identify Eurasian Watermilfoil as we brought it up, and kept samples to confirm once we were back off of the boat. Small Pond weed was initially unknown to us, but we quickly identified it as we reasearched plants that were likely to be present in this region. Plants that we were unable to be identified or were unsure of were placed in plastic bags marked with the date, time, and location. Common Reed was one of these, and was easily identified because we had brought a sample back with us.

Storm Drain Stenciling

With around 750 storm drains leading to Indian Lake, it is tough for the ILWA to monitor the stenciling of these drains. White spraypaint was used on the drains with the help of a stencil provided by the City of Worcester. Some drains were too small for the stencil, in which case we used a sticker provided by the City of Worcester on the stone of the drain. A interactive data map was used to display our information.

Developed as Part of a WPI Sponsored Project
In Affiliation with The Indian Lake Watershed Association
Worcester, MA 2013