This week we started doing field work for our Directed Research projects.
The project I’m working on involves counting conch along a transect. A
transect is a measured line used to survey and count the numbers of organisms
in square areas next to the line. This gives us an estimate of the number of
organisms along the transect. In our case, we are counting live conch. We are
also surveying the composition of the ocean bottom along the transect. This
task is accomplished by using a quadrat. A quadrat is a 1-meter x 1-meter
square made of plastic piping. The quadrat is placed on the bottom, and we
record whether the bottom within each square is composed of sea grass, sand,
or micro algae. Using the quadrat, our group is able to see which bottom type
is most abundant for that transect, and it helps us to analyze the preferred
habitat of conch.
The hard part about doing our transect is that we are underwater in SCUBA
gear the whole time. Little things that we take for granted on land, like being
able to ask your partner for help, take on a whole new meaning when the only
way you can communicate underwater are through hand signals and writing
something down on an underwater slate. These limitations make it important
that every member of the team know how to get their job done correctly and
quickly for every dive. This makes organization extremely important.
Faculty Essay: Underwater Research
Bruno Bautil and the Bell Sound Underwater Research Team
In order to determine the species composition and relative abundance of
aquatic organisms in Bell Sound, the directed research (DR) group decided to
try a combination of line transect and quadrat as sampling methods. A quadrat
generally refers to a square or rectangular sampling unit within which organisms
are counted or measured. They are usually constructed of iron or PVC pipes
and maybe fitted with grid squares for finer estimations. The linear intercept is
simply a tape measure stretched and secured at both ends. Both research tools
have the advantage of ease of use, ability to measure percent cover, species
diversity and relative abundance of plants and animals that live in the shallow
waters of Bell Sound. The intercept method is simpler and quicker to use than a
quadrat but may not provide accurate sampling of small and widely scattered
organisms.
Aside from sampling biological organisms, in situ environmental conditions are
also being collected at different locations. This includes water temperature
measurements with a thermometer, salinity or salt content of water using a
refractometer, water depth "sounding" with a meter stick, the type of
substratum, date and time of collection or sampling, and tidal conditions. The
position of the sampling transects can be accurately determined either by using
a portable GPS (global positioning system) receiver or by map inspection and
magnetic compass triangulation. In order to collect the necessary data, the DR
group spends most of their time snorkeling in the calm, shallow and turquoise
colored waters of Bell Sound.
After a tiring day of sampling, the DR team comes back to the Center to grab a
quick dinner before meeting again in the library to input their data into the
computer. Later in the semester, they will apply various statistical and graphic
techniques to analyze all of the information they will amass in search of natural
patterns that may be inherent in the Bell Sound ecosystem. That must be
something interesting to wait for.
Faculty Essay: Coral and Coral Reefs
Phil Davies
When you think about coral reefs, what picture comes to mind? Maybe you
imagine sun-drenched, white, sandy beaches surrounded by clear blue waters
teeming with brightly coloured fishes, turtles, and coral. But have you ever
wondered what a coral is and how it forms a reef? Well, corals are simple
animals that form large colonies with many individuals joined together. These
individuals share food and other resources, and they produce an external
chalky skeleton (called an exoskeleton), which makes up the majority of what
we usually refer to as a coral. In fact, the living animal is only present in a very
thin layer on the surface of this bulky skeleton. Over the course of many years,
the animals build up layers of exoskelton to form the reef. These animals are so
successful at building reefs that some reefs are large enough to be seen on
images of the earth taken from orbiting satellites. These huge structures also
provide many other organisms, including plants and animals, a place to live.
This fact makes coral reefs the most diverse marine ecosystem on Earth!
