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Dear Tim<br>
<br>
As you point out there are many situations where the AIMS/GCRMN
categories for monitoring have no hard and fast interpretation. AIMS has
recently produced a CDROM called C-Nav to support standardisation and
promote data quality using these methods. <br>
The CD looks at many examples from both exposed and sheltered reef
habitats (as the issues that come up are different) and has extensive
interactive material including the ability to store past and current
scores for categorising reef benthos according to either Reef Check or
the AIMS/GCRMN categories.<br>
<br>
The idea is that this CD can be used for both training of new observers
and standardisation of experienced observers. The code definitions
attempt to expand on what was published in English et al and to deal with
problem areas by example. The definitions are based on decision rules as
much as possible, with the focus on achieving TEMPORAL CONSISTENCY as the
primary objective.<br>
<br>
While it is ideal for everyone to be using the same definitions it is
more important to achieve temporal consistency which is optimised by
having categories clearly defined using operational definitions such as
the one you propose for Rubble<br>
<br>
Rubble - How big is a piece of unattached coral before it is classified =
<br>
>as rock, DCA etc? We set 50cm as a maximum size in any
dimension.<br>
<br>
The definition on C-Nav Rubble is used to describe fragments of
coral reef, which have been broken down into pieces between half and
fifteen centimetres in length/diameter. <br>
Silt - How deep does it have to be? Does a few cm laying on top of dead =
<br>
>or live coral count as silt or should this be ignored? We have told
our = <br>
>volunteers to record the underlying substrate and record the covering
of = <br>
>silt separately.<br>
<br>
This sounds like a good solution and is in line with the protocol used by
AIMS Reef Monitoring for video analysis. As you point out this system is
also able to deal with separating substrate and biotic cover (as for
example where turf algae is growing on Rubble). Where two substrates
occur together we recommend using visual dominance to score the point. Eg
coralline and turf algae.<br>
<br>
DCA (DEAD coral with algae)<br>
This category (or variations of it) is used in most standard protocols
and in some is extremely important in the way evaluations of status or
health are derived. As such it is important to be clear about the
boundaries of the category. The definition on C-Nav is as follows.<br>
DCA - Dead Coral with Algae. Dead coral colonised by turf algae.<br>
The skeleton is no longer white being discolored by a thin layer of
filamentous algae. The details of the skeleton are still intact and not
eroded. We recommend using this category only where the white of the dead
skeleton is still visible under a thin algal coating or for small patch
injuries in an otherwise live and intact coral. Other wise there may be
large differences in the time since mortality occurred due to variable
erosion rates and algal growth rates in different locations.<br>
This category is problematic in image data, as often the skeletal detail
cannot be seen. Use the guidelines mentioned above.<br>
This category was included in the GCRMN identification system primarily
in order to identify recent large-scale mortality events such as crown of
thorns predation.<br>
<br>
Thanks for your comments and I hope this helps. <br>
For info on ordering C-Nav see <br>
<font color="#0000FF"><u><a href="http://www.aims.gov.au/c-nav" eudora="autourl">http://www.aims.gov.au/c-</a><a href="http://www.aims.gov.au/c-nav" eudora="autourl">nav<br>
<br>
</a></u></font>C-Nav has around 1000 images that are mainly of
Indo-Pacific corals. I would be interested to hear from anyone interested
in developing a version for other regions.<br>
The standard operation procedures for video analysis are also published
on the AIMS web site and can be accessed from the address below.<br>
<br>
<br>
<br>
<div>Kate Osborne</div>
<div>Reef Monitoring</div>
<div>A.I.M.S</div>
<div>P.M.B 3, Townsville MC, 4810</div>
<div>ph 61 7 47534229</div>
<div>fax 61 7 47534288</div>
<a href="http://www.aims.gov.au/reef-monitoring" EUDORA=AUTOURL>www.aims.gov.au/reef-monitoring</a>
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