March 2017.

Coastal environments pose numerous challenges for monitoring. They are often very heterogeneous and for ecologists, are made up of a patchwork of different habitats and biotopes. Water, light and nutrient conditions change continuously and rapidly. Animals move through these environments at widely varying rates and numbers. Even organisms and plants that aren't mobile, permanently alter the substrates they live on, or in.

This makes deciding where to make measurements quite complex if we wish to establish the impact of a particular activity. That's one of the reasons why new survey techniques favour collecting imagery, over point measurements.

This month we've had the opportunity to see what some of this new instrumentation can do in the Bay of Brest. Gravity Marine is trying out their new Biosonics MX sonar designed to detect and map seagrass beds and macroalgae at high spatial resolution. This acoustic technique aims to provide not just the presence of vegetation, but also should give us an indication of plant height.

Thanks to the help of the scientific divers at IUEM, we got back some great preliminary results. These results will be discussed in the PhD projects of Shawn Hinz and Jeff Wilson (anticipated date of completion, 2018).

Image: Installation of an ADCP in the Bay of Brest, near where the seagrass surveys were done. Erwan Amice (CNRS).

Seagrass in the Bay of Brest, March 2017. Erwan Amice (CNRS).