[Coral-List] Questions - Measuring Acropora

[andrew ross]

Valeria,As Sebastian has suggested, CPCe is a nice way to start.Version 3.6 has an "accumulated lengths" feature. It's very good (and quicker/easier) for branching thickets, though it won't give you % cover. A hollow PVC graduated scale-pole should be light enough to not break branches, but will be a headache in rough weather. If you can stay very still in taking pictures, wait for a bright, clear day and have at least 7-Megapixels in your camera, you should be able to take >1.5mx1m photos (over the scale-pole) and see branches and some detail of disease, predation etc... Figuring out the genets might be more difficult, but different genets will often look a little different, particularly if side-by-side for comparison. That can at least be a start.
A
--- On Thu, 5/28/09, Sebastian Striewski <sebastian.striewski at rub.de> wrote:

From: Sebastian Striewski <sebastian.striewski at rub.de>
Subject: Re: [Coral-List] Questions - Measuring Acropora
To: "Valeria Pizarro" <valepizarro at yahoo.com>, "coral list" <coral-list at coral.aoml.noaa.gov>
Date: Thursday, May 28, 2009, 9:26 PM

Dear V. Pizarro,

an easy way to calculate a planar area might be done with a modified 
point intersept transect taking pictures and analysing them using the 
software CPCe from Kohler et al 2006,     
http://www.nova.edu/ocean/cpce/   using thefunction "planar area analysis".
This very helpfull software allows to calibrate images taken during a 
transect and analysing areas computer based.
We used this method in the Red Sea just recently. A simple plastic 1m2 
frame was positioned along a linetransect every 5meter and detailed 
pictures taken from the area underlying the frame. Back in the 
laboratory those pictures were than easily analysed with the mentioned 
software and data exported towards Excel from Windows.
Besides very good to hear from recovering Acropora palmata!

Greetings, Striewski


Valeria Pizarro schrieb:
> Dear coral-listers,My colleagues and I are starting a project on Acropora palmata and A. cervicornis in the Caribbean coast of Colombia. We are sampling the area of the Tayrona National Marine Park. We are mapping the location of the Acropora spp patches, measuring these areas and finding the abundance within each area. With the latest we had had problems because it has been hard to tell apart one colony from another, especially when the colonies are big or patches dense. The other problem is to set the transects without damaging any of the colonies.I anyone can help us with an easy method to measure Acroporids abundance we will be more than grateful.The good news are that apparently at least for this area we are sampling Acropora palmata seems to be recovering. One can see juvenile colonies growing over dead Acropora colonies.thanks,Valeria
> ________________________________________Valeria PizarroAssociate LecturerMarine Biology ProgramUniversidad Jorge Tadeo LozanoSanta Marta, Colombia
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