The orientation of marine larvae is a central issue in understanding and modelling the pelagic stage of coastal organisms. The few studies tackling the sensory abilities of fish larvae involve late stage larvae and are carried out in the vicinity of coral reefs or in laboratories. Almost nothing is known about the orientation of larvae earlier in the larval phase and far from the reef.
Claire Paris at RSMAS (University of Miami) invented a concept and a device to “bring the lab in the field” and understand the orientation behaviour of larvae in their natural environment. It revolves around drifting device composed of a circular aquarium in which larvae move and a camera which records their movement.
I started collaborating to this project during my PhD, mostly for the software part. The tracks of the larvae have to be captured from the video record, variously corrected, and statistically analysed. We managed to do all this through the integration of various open-source software and the initial version of the code is described in the web page of the project.
I then contributed to the design and engineering of a second prototype of the instrument, called the Drifting In-Situ Chamber (DISC). It built on the strong points of the first one while avoiding some of its flaws: it is less conspicuous, vibrates less, captures better images etc. The code had to be adapted to these new characteristics and the development version (called DISCUS) is now hosted as a Gitorious project. During my post-doc with Claire, we deployed this new instrument on the Great Barrier Reef in Australia to study different processes and stimuli that can govern navigation in fish larvae. This work was the result of two collaborations: with Jeff Leis from the Australian Musuem of Sydney on one hand, and with Michael Kingsford (James Cook Uni), Jelle Atema (Boston Uni, Woods Hole) and Gabriele Gerlach (Oldenburg Uni) on the other hand. The field work went well, we came back with gigabytes of images and the data is currently being processed and analysed.
Current code on Gitorious
Irisson J-O, Paris CB, Guiguand C, Fisher R. Detection and quantification of marine larvae orientation in the pelagic environment. Limnology & Oceanography: Methods, Vol. 7, pp. 664-672, 2009 [PDF]
Paris CB, Guigand C, Irisson J-O, Fisher R, D’Allessandro E. Orientation with No Frame of Reference (OWNFOR): A novel system to observe and quantify orientation in reef fish larvae. Caribbean Connectivity: Implications for Marine Protected Area Management. Proceedings of a Special Symposium, 9-11 November 2006, 59th Annual Meeting of the Gulf and Caribbean Fisheries Institute, Belize City, Belize, pp. 52-62, 2008 [PDF]
Irisson, Paris, Guigand, Fisher, 2006. Orientation With No Frame of Reference (OWNFOR): An In Situ System to Detect and Measure Orientation in Pelagic Reef Fish Larvae. Poster, Ocean Science Meeting ‘06, Hawaii, USA. [Handouts, Poster]