[Coral-List] Photoquadrat

[Ron Kirby Manit]

Project Seahorse Foundation for Marine Conservation
30 June 2009

Methodological Question about Photoquadrats for “Coral List”

The benthic survey component of our coral reef long-term monitoring program
has (again) presented us with some tricky methodological issues, and were
hoping to consult with this community for advice on how to resolve them. We
are a small marine conservation NGO conducting research on marine protected
areas in the central Philippines, with a small team of marine biologists.

Some background: we piloted a photoquadrat (“PQ”) method in 2007 to replace
our older line-intercept method. At each survey site, this PQ method uses 10
haphazardly laid 25 m transects, with photos taken every 1 m along the
transect. We plan to conduct PQ once a year at these sites, all of which are
shallow (~3-4 m depth) with some turbidity.

Basically, our current digital camera (Sony DSC-P10 Cybershot, 5.0
megapixels, purchased in 2003) has been malfunctioning and we need to
replace it. We are very concerned that if we simply bought a new camera
(with new wide-angle lens etc.) that the photodata we have already gathered
using this old camera would not be comparable with the newer photodata with
whatever new camera equipment we decide to purchase. Our current wide angle
lens is the “MPK-P9 wide version 16 mm/F5.6.” We use CPCE to process the
images.

Are photoquadrat methods using this image-processing software sensitive to
the exact specifications of particular cameras? Or is the software and
analysis of this kind of data robust to all kinds of equipment? What kind of
considerations do we need to keep in mind when making this decision? Would
it be ok if just replace our camera with a new set of camera that are of
different specs on the camera that we are using?

We would appreciate any advice this community can offer. Thanks!