Reef
Flat Monitoring
In many areas
around CNMI, reef flats are the first marine environment encountered
next to dry land. Reef flats are the shallow areas between the
shoreline and the breaking waves on the reef crest. In some areas, such
as Lau Lau Bay, sediment and nutrient pollution are washing from shore
and have caused coral habitat to change to an environment dominated by
fleshy algae. In other areas, the relatively natural coastline has
allowed the growth of a coral rich environment.
Monthly monitoring
of the benthic, reef-flat community allows us to document annual cycles
in macroalgae growth. It is known that "brown" runoff washes into the
bay during storm events, providing excess nutrients to the
nearshore ecosystem, and favorable conditions for certain macroalgae to
grow and persist. The Coastal Resources Management and Division of
Environmental Quality have recently started several programs that will
help reduce the amount of runoff and "clean" the watershed. Our reef
flat monitoring data will help to evaluate and document the hopefully
positive results of their management efforts.
Above, student
volunteers help monitor reef flats on Saipan.
Marine Flat
Monitoring Program- Benthic Data
Benthic data is
the core of reef flat surveys. This type of survey scores the
diversity and abundance of the things that grow attached to the bottom.
By understanding what is growing on the bottom (or how much is not
living at all) we get an idea of how the environment is doing.
For example, if a reef flat has a constant covering of macroalgae, it
is a hint that the area probably has a nutrient pollution
problem. The most common reef flat benthic (bottom dwelling)
animal on reef flats are corals and sponges. Coralline and fleshy
algae are the dominant plants.
 Methods of Benthic Data
Collection
The reef flat
surveys are conducted using the following materials: 3-5 transects
measuring up to 20 meter per transect & the use of 3-5 quadrats
depending on the survey sites. In addition, data sheets are used
to input and record data collected from the surveys conducted.
The methods of
collecting benthic data on reef flat surveys begin with laying out each
transect. Secondly, members of the Marine Monitoring Team (MMT)
as well as volunteers are assigned to each transect equipped with a
quadrat and data sheets. Quadrats are layed every 1.5
M. Each quadrat contains 6 data points. Data is collected
by recording benthic species that are located directly in each data
point. Lastly, the method of collecting macroinvertabrate data is
counting the total amount of maro invert species in an area of 40 M^2.
Marine Flat
Monitoring Program- Macroinvertebrate Data
Macroinvertebrate
data counts numbers of free living invertebrates. These differ from the
coral and sponges (also invertebrates) scored in the previous survey
type in that they are not permanently attached to the bottom. We
find sea cucumbers and sea urchins to be the most common invertebrates
on reef flats. Others include giant clams, seastars, crabs and
snals. These animals can give us clues about water quality and fishing
pressure.
Marine Flat
Monitoring Program- Survey Sites
We are now
surveying sites on Saipan, Rota and Tinian. Surveys occur twice a month
and volunteer participants are welcome. For information on how to
participate, contact john.starmer (@) crm.gov.mp.
Click on the reef
flat drop down menu at the top of this page to view reef flat survey
results for individual sites.
Above left, Unai
Dangkulo, Tinian. Above right, Forbidden Island, Saipan
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