|Title||Zooglider: An autonomous vehicle for optical and acoustic sensing of zooplankton|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Ohman MD, Davis RE, Sherman JT, Grindley KR, Whitmore BM, Nickels CF, Ellen JS|
We present the design and preliminary results from ocean deployments of Zooglider, a new autonomous zooplankton-sensing glider. Zooglider is a modified Spray glider that includes a low-power camera (Zoocam) with telecentric lens and a custom dual frequency Zonar (200 and 1000 kHz). The Zoocam quantifies zooplankton and marine snow as they flow through a defined volume inside a sampling tunnel. Images are acquired on average every 5 cm from a maximum operating depth of ~ 400 m to the sea surface. Biofouling is mitigated using a dual approach: an ultraviolet light-emitting diode and a mechanical wiper. The Zonar permits differentiation of large and small acoustic backscatterers in larger volumes than can be sampled optically. Other sensors include a pumped conductivity, temperature, and depth unit and chlorophyll a fluorometer. Zooglider enables fully autonomous in situ measurements of mesozooplankton distributions, together with the three-dimensional orientation of organisms and marine snow in relation to other biotic and physical properties of the ocean water column. It is well suited to resolve thin layers and microscale ocean patchiness. Battery capacity supports 50 d of operations. Zooglider includes two-way communications via Iridium, permitting near-real–time transmission of data from each dive profile, as well as interactive instrument control from remote locations for adaptive sampling.
In summary, Zooglider is a new instrument to optically image mesozooplankton and marine snow in situ, while simultaneously recording acoustic backscatter at two acoustic frequencies, Chl a, temperature, and salinity in the same water parcel. The instrument operates between 0 and 400 m depth and is completely autonomous but with remote two‐way communication and directed navigation via satellite. It is an endurance vehicle, capable of 50 d missions. It provides near‐real–time data and is suited to both prescribed sampling trajectories and adaptive feature‐based sampling for a broad spectrum of studies addressing the ecological interactions of zooplankton and their importance in ocean biogeochemical cycles.