I am looking for not very expensive methods to determine how much CO2 could be trapped by coral reef species in the Caribbean. Also, I want to do the same thing in Coralline Algae.
Because legal terms in my country, it is most feasible to do that in the field. I must ask a legal permission to get access to biological resources if I will try this in a lab. What do you suggest?
The problem with trying to do this in the field is that you will probably need to measure the respiration rate of the coral and algae to be able to determine the rate of CO2 capture. The only other method I can think of is to measure food intake for coral, but again, this is going to be very difficult and likely prohibitively expensive given the equipment you would need. If you search through the literature on the topic, all experiments are done in the lab using samples, and this is due to the equipment needed for effective measurement of respiration and/or food intake. If I was going to do this on a low budget, I would get the necessary permissions to obtain samples and use those in the lab. Before you go any further, you should read the attached papers - especially the PNAS paper - to look for pitfalls with this proposed study.
I hope this helps a little - sorry I can't be more positive about a field-based approach.
I don't know if the following will help you in your circumstances but some years back some of my colleagues measured respiration and primary production by silica diatoms with black and transparent flux chambers. As far as I remember, the results were quite neat and the primary production of diatom sediments could be quantified quite well. But as I say, I don't know how practical it is to encapsulate a portion of coral reef into a flux chamber. I don't have access to the full paper but here is the reference: Thorbergsdottir et al. 2004 Benthic oxygen flux in the highly productive subarctic Lake Myvatn, Iceland: In situ benthic flux chamber study. Aquatic Ecology, 38, 177-189.
Post another question on Researchgate asking if anyone is doing this type of study in the near future - I'm sorry I don't know anyone who is doing this type of work right now.