Part 2 – EMP surveys and science diving

A large part of my work here was to help conduct ecosystem surveys around the local area - to provide baseline data as part of a long-term monitoring program. This data will then be fed into a Environmental Management Plan (EMP). And they were super happy that I was there - as due to the many factors we wanted to analyse, a 3-diver team was exceedingly useful! The initial plan was a survey design method using line transects, as the data collection is continuous (there was no “point sampling” using quadrats that only gathers data in a few set areas). It also helps provide a snapshot of the ecosystem over time.

Baseline study - an analysis of the current situation to identify the starting points for a project. For marine biologists, it shows us what the ecosystem is like in a certain location, in order to see the trends and changes over the years - and hence we can use this information to spot problems and act on them!

Environmental management plan - a document which analyses baseline data and the current trajectory of long-term trends, to reduce adverse environmental impacts to acceptable levels via the mitigation of stressors and implementation of protected areas (for example).

Line Transects - a continuous line between 2 points that one uses as a guide to measure the abundance / biodiversity / other ecosystems parameters along a defined path.

WHAT WE WERE THINKING OF DOING:

For this, we had a 100m measuring line that we would place down in 3 directions from the same point (going north west, south west and south east). When we dropped, we would lay the line as a team - with one person on SMB, one person running the measuring tape and one person making sure that the navigation was on point (compass). At the start, James would make sure that the start and end points of the 100m tape were always in the same place (the data collection was from the same location and thus reproducible over time). 

We would make sure that the tape was tight and lying on the reef so much that it didn’t fall inside the crevices and dips in the reefs rugosity (as then it would be less than 100m length!). After that, we would wait for 5 minutes to allow for any animals (that we distributed via running the tape measure), to come back into the area. The tape would also be at the same depth - to control for this variable. We want to make sure that the species composition or biodiversity would only change based on time (future measurements) or substrate (along the length of the tape in the current time).

The data collection would take place in 4 x 20m sections, with a 5 minute interval between each section, to again allow for the reef to settle and to bring back creatures into the area, that would have been there in the first place, but which were disturbed by us. This is also because we would sample 2.5m in each direction out from the line itself - ie we would be looking for fish / inverts that traversed the line and in the immediate vicinity. All in all, this would allow us to sample a 500m2 area of reef, and hence why we sampled along the line transect in 20m intervals (with a 5m gap) - to avoid overlap from the 2.5m sampling range. Thus, the sections we would collect data from were 1-20m, 25-45m, 50-75m, and 80-95m.

Diver 1 would reel the line back in and also take a video of the reef at the same time - to gather information regarding coral species, bleaching and substrate health. Diver 2 would have an SMB inflated, to make boats aware of that we are doing, and they also had a camera to capture fish footage. Diver 3 - would conduct invert surveys - by peeking under and around the reef, trying to spot the little creatures that were so important in the reef ecosystem. They would also have a slate to record species if time. 

Sounds great?? A well thought out plan to collect lots of data simultaneously… but then…