[Coral-List] Best practice for LIT surveys

[David Fisk]

With all the talk about LIT deployment and practical considerations, seems
like it might be a good time to add a few more comments into the discussion
before it disappears off the scene. I am aware of at least 2 MSc theses
looking at the accuracy and precision of the LIT method. One was done by
Craig Mundy from James Cook Uni in Townsville and another by a post grad in
Canada (I am sorry I can't remember the name of the person right now). Both
did these studies back in the 1980-90's.

Both bascially found problems with the precision of the method, so much so
that a tape that is strung out for 20m and tied every 5m with plastic coated
wire to stakes hammered into the substrate, still came up with an average
20% difference in repeated cover estimates. And this held true for a
situation where the same recorder read the intercepts for a number of
repeated times - further more the benthic surface where the tests were done
had very low relief and there was neglible water movement and therefore tape
movement. So despite its widespread adoption as a monitoring tool, it has
limitations like all methods that should be kept in mind when interpreting
the data.

LIT is of course known to be inaccurate in estimating the true number of
small colonies in a population. All monitoring methods have their pros and
cons, and personally I find the LIT very time consuming and of limited
application with the above precision problems and inaccuracies wrt the under
estimation of smaller colonies, not to mention the deployment issues already
discussed. For an approximate estimation of coral cover, there are probably
better methods available that require less field time and number crunching
time, but a combination of rapid recording methods that include a permanent
pictorial record is ideal.