LOKI is an underwater camera system for continuous, in-situ imaging of zooplankton (developed by Isitec GmbH, Bremerhaven, Germany). It is equipped with environmental sensors (e.g. pressure, temperature, salinity, chl a) which send data every second, providing a vertical resolution of zooplankton and environmental variables of ~30-40 cm.
Schematic of LOKI and its components
If compared with other systems that are currently being used in the World’s Oceans (e.g. Video Plankton Recorder, VPR and Underwater Vision Profiler, UVP), the most important differences are probably that the LOKI a) is designed for vertical hauls, b) uses a plankton concentration net on top of the camera, c) images plankton in a small, constrained volume leading to excellent image quality, and d) is designed in a way that makes it feasible to collect the zooplankton directly after it was imaged for validation.
Deployment of LOKI on different cruises. In the right hand picture, the cod-end for collecting zooplankton after imaging is clearly visible.
The LOKI is now standard zooplankton sampling gear aboard the CCGS Amundsen and with the development of a zooplankton species identification model as part of my PhD we have started to collect a long-term series of zooplankton imaging data in the Arctic.
As part of the Green Edge ice camp (April-July 2015), the LOKI is also being deployed in Qikiqtarjuaq, Nunavut, CAN by Cyril Aubry (Professionel de recherche, laboratoire Fortier & Takuvik) and Thibaud Dezutter (M.Sc. student under the supervision of Prof. Louis Fortier).
Hirche, H.J., Barz, K., Ayon, P. & Schulz, J. (2014). High resolution vertical distribution of the copepod Calanus chilensis in relation to the shallow oxygen minimum zone off northern Peru using LOKI, a new plankton imaging system. Deep Sea Research Part I: Oceanographic Research Papers, 88, 63–73.
Schulz, J., Barz, K., Ayon, P., Ludtke, A., Zielinski, O., Mengedoht, D. & Hirche, H.-J. (2010). Imaging of plankton specimens with the lightframe on-sight keyspecies investigation (LOKI) system. Journal of the European Optical Society: Rapid Publications, 5. Retrieved November 2, 2013, from https://www.jeos.org/index.php/jeos_rp/article/view/10017s
Schulz, J., Barz, K., Mengedoht, D., Hanken, T., Lilienthal, H., Rieper, N., Hoops, J., Vogel, K. & Hirche, H.-J. (2009a). Lightframe On-sight Key species Investigation (LOKI). OCEANS 2009 – EUROPE, pp. 1–5.
Schulz, J., Barz, K., Mengedoht, D., Hanken, T., Lilienthal, H., Rieper, N., Hoops, J., Vogel, K. & Hirche, H.-J. (2009b). Lightframe On-sight Key species Investigation (LOKI) – The art of imaging tiny plankton species on-the-fly. EPIC3IEEE Oceans’09 Brementh May 2009., 11. Retrieved November 2, 2013, from http://epic.awi.de/20909/