Aquatechnex deployed a new hydro-acoustic scientific echosounder with software to collect aquatic plant percent cover and plant height on Union Bay in Lake Washington this week. Union Bay will be treated with Sonar Aquatic Herbicide to target extensive stands of Eurasian Milfoil and Brazilian Elodea that have plagued the residents of this area for years. The Save Union Bay Association received a grant from the Washington Department of Ecology to fund this operation and the treatments will begin in approximately two weeks.
Aquatic plant surveys are always challenging. There are a number of different techniques that can be used and each has advantages and limitations. The Point Intercept system for example does and excellent job of documenting aquatic plant species occurance and density at the point surveyed and over time returning to that point will show changes that can result from management efforts. The spaces between points however are unknown and that can lead to issues.
This technology allows the operator to rapidly collect an extensive data set. This site is approximately 250 acres in size and these 40 transects were collected in about 4 hours. Each transect is sampled at one second intervals and the software outputs bathymetry, sediment or substrate type, aquatic plant percent cover and aquatic plant height. These transects can be repeated post treatment and compared to document exact change in the aquatic plant communities.
We look forward to using this technology on a number of other projects this summer to gain a better understanding of aquatic plant beds and the results of management efforts.