As part of the XL Catlin Seaview Survey we use a camera system called Seview 2,
otherwise known as SV2. This camera system is connected to a diver
propultion vehicle (DPV), which allows the
diver to travel approximately two kilometres
per dive. In that dive we're able to take
up 1000 images a dive of the benthos and also
take 360 degree panoramic images of the coral reef. The scooter is powered by a propeller
which has a battery inside of it and that
battery [will] generally last for about an hour,
which allows us to travel that distance underwater.
Well, traditionally [a] coral reef ecosystems
are monitored either in situ by a diver -- where they will record what they see along a linear
transact -- or divers will take photographs
of the reef, which they can later analyse in
an office setting. With traditional methods,
[it] is limited by scuba diving equipment.
We only really have about an hour to do our
dives and our surveys, before our air runs
out. Whereas with a scooter, the SC2, we can travel two kilometres, taking a lot more photographs per dive,
and gathering much more information about what's
happening on the coral reef. We went to the
Maldives as part of a research expedition
in 2015 and we had the opportunity to lay
down a 50 metre transact to take approx. 30 one-by-one metre photo quadrants, which were cropped later in the office.
And then we analysed them using an online repository called CoralNet
[https://coralnet.ucsd.edu] , which uses random-
point allocation on each photograph to determine
what is under each point and therefore get
an idea of the percent cover of important
metrics on corals reefs such as coral cover,
algae cover, and other invertebrates that
we find on the bottom. The exciting thing
about the XL Catlin SeavIew Survey data is
that it's geo-referenced. And that means that
we know within a five-metre distance, exactly
where the picture was taken. And what that
means is that we have a a really good baseline
of coral reef cover at sites we've visited,
and therefore if a disturbance event happens
or an organisation in a country wants to go
to that site later on, say five years later,
but they don't quite have the technology,
they can access the global reef record (the
Catlin Global Reef Record) and know where
a transact was, and go back to that site and
take their own images using conventional methods,
feeling confident that the results they get
would have been comparable, and they could
measure either coral decline ... or increase.
