Beginning in 2011, BioBase brought the 3rd dimension of habitat in the aquatic world. BioBase’s EcoSound™ maps not only the mere presence of vegetation, but also the canopy height and creates aquatic plant ABUNDANCE maps of unprecedented detail (Figure 1).
We’ve spent thousands of words in these pages and presentations on the road extolling the importance of measuring and monitoring aquatic plant abundance to further the goals of aquatic habitat conservation. We place emphasis on the word “abundance” because it drives habitat; it drives water quality dynamics. But simply existing carries great importance as well. So while abundance is critical to know for population viability and ecosystem models, knowing whether a species is simply occupying a space regardless of its abundance is also tremendously important.
Mapping the sparse or rare? Make it POP!
Now, BioBase has a Processing Preference that allows users to create aquatic vegetation presence/absence or cover maps instead of full vegetation biovolume heat maps (Figure 2). To do this, BioBase simply reclassifies all biovolume values greater than the user-specified minimum threshold (default = 5% of the water depth) to a value equal to one (present) and areas where there was no vegetation remains equal to zero (absent). The interpolated results produce areas that are monochromatic green (e.g., high likelihood of plant occurrence) and transparent (e.g., high likelihood of plant absence). Figures 3 and 4 show a couple great real-life examples.
Understand your local environment and what could impact detection accuracy
BioBase’s EcoSound uses the properties of sound waves to make inferences on whether something on bottom is “aquatic vegetation.” The technology does not do any kind of further chemical or biological testing to know whether something on bottom is a live green herbaceous plant or a decaying stick. As such, we deliberately set our biovolume or presence/absence detection threshold to a conservative 5%. Pushing this down can indeed increase the ability to map very sparsely growing plants, but it also increases the chances of false detections of things on bottom that aren’t plants. Therefore, the more ancillary information you as a practitioner know about the environment you are managing, the better informed you can be about the appropriate BioBase settings.
Sometimes simple wins
In our drive to create something that’s hard to do, like map aquatic vegetation abundance, we can sometimes overlook the easy, like simply mapping whether vegetation is there or not. We’ll take an easy feature any day…better late than never!
