REEF Survey and Fluorescence

Today was a very busy yet amazing day. We went on two completely different dives. The first dive was to conduct a different fish survey than the AGRRA fish survey that was explained earlier. The fish survey conducted today was a REEF survey. This is a roving diver survey allowing the diver to swim freely along the reef without setting up a transect. This made the dive feel more recreational because we got to look at all the fish and not just specific species. The purpose of this survey is to record all the different fish species observed during the dive along with an estimated abundance of each species. Since divers are encouraged to record as many species as they can, the diver gets to look throughout the whole water column as well as under ledges and in holes and crevices. There are four different abundance categories [single (1), few (2-10), many (11-100) and abundant (>100). This is not an easily repeatable method because there is a lot of observer bias. However, it does provide some information at what species can be found in an area. The coolest fish that I saw today was the peacock flounder.

Our second dive of the day was a night dive to look at fluorescence. Fluorescence is when one wavelength of light is absorbed by an object and remits light at a different wavelength. To see fluorescence, a blue light and yellow filer needs to be used. The yellow filter is placed over the mask to block the blue light that is bounced off the object allowing only the fluorescing object to be seen. We saw a ton of corals fluorescing along with anemones, fireworms, and even a fish. The fish we saw was a sand diver and I even got to touch it. Seeing the fireworms was cool because they fluoresced a green and orange color. Corals mainly fluoresced in green except of one, which was orange. I found the coral with the orange interesting. The coral was Undaria agaricites and there were just a ton of orange dots creating interesting patterns. 

Fluorescence of an anemone.
Photo Credit: Shannon Richardson (classmate)