BRUV for krill? and Appropriate coral reef use?

[Sarah Halse]

Hi all,

Our projects might be expanding soon and there are a number of things we need some advice for, all suggestions are welcome :)

1- We will be doing stereo-BRUV work in the Seychelles and will most probably be deploying systems onto the areas extensive reefs, obviously we want to do this with the upmost care and avoid damage where possible, any suggestions on coral reef deployments and how to make them safer? 

Some ideas were doing diver deployments? or using a tripod frame? Has anyone tried this? 

2- What is the smallest size fish/thing that has been measured and is it reliable and/or accurate? We are looking at possibly using stereo BRUV for measuring the size of Antarctic krill usually about 2-7cm long, is this feasible? 

Looking forward to some replies. 

[Euan Harvey]

Sarah,  We are measuring things from small 2 cm fish through to 3 m sharks with our current configurations.  However, if you want to consistently measure small objects with high accuracy then you should change the scale of your system and move the cameras closer.  Jim Seager could advise you.  We did use a  camera system to measure the inhalant siphons of shellfish that were up to 12 mm in diameter  (see Shortis, M. R., Miller, S., Harvey, E. S. and Robson, S. 2000 - An analysis of the calibration stability and measurement accuracy of an underwater stereo-video system used for shellfish surveys. Geomatics Research Australasia, 73: 1-24).  I think the article is available on Research Gate.

[Tim Langlois]

Hi Sarah

I know Tom Letessier has a paper coming out measuring krill - in a tank - he is on this group so you could contact through the member list.

And Jordan Goetze has been doing a lot of BRUV drops on high profile reefs in Fiji recently - so he might have some advice on deploying on corals - he is also on the group.

Last time I deployed a BRUV by hand a large shark swam past the minute I swam out of the field of view (I hadn't seen the shark underwater). It was only a lemon shark but looked big on the video.

Good luck

Tim

[Sarah Halse]

Hi Tim and Euan,

 

Thanks so much for the advice. Will get on it.

[Tom Letessier]

FYI

http://dx.doi.org/10.4236/ojms.2013.33016 

[Sarah Halse]

Thanks very much for this Tom, much appreciated.