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Sampling Methods for Eurasian Watermilfoil on the Chippewa Flowage |
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Plants
will be sampled using the point intercept method (Madsen, 1999; Havens,
et al. 2002), which estimates plant cover, but does not quantify plant
density or biomass. The
Chippewa Flowage will be mapped by using a GIS and then overlaid with a
grid of points (spaced 100
meters apart) to be surveyed. Points
from the grid will be located in the field with a GPS unit with 5-10
meter accuracy. At each
point; water depth will be recorded, a two-sided macrophyte rake will be
tossed in two times to collect plant samples, and substrate type will be
recorded. Water transparency
will be recorded using a secchi disk at locations determined by research
team. After
locating the site (using the GPS unit) anchor the boat securely at the
front. Immediately read and
record the UTM coordinates and accuracy of the site.
The following information on the Eurasian
Watermilfoil Data Sheet will be filled in at this time: Initials
of Surveyors, Date, an Time and any other information that would be useful in the Notes
box. Water depth will
then be recorded using the calibrated rake off the starboard or right
side of boat. Record
the water depth (in feet) in the Water
Depth box. Before
removing the rake from the water “feel” the substrate with the rake
head to determine whether the substrate is muck, peat, sand, gravel, or
cobble/rubble. Record this
in the Substrate: box. Next,
(on the right side of the boat) extend the rake so that the rake head is
roughly 3.0 feet from the gunwale of the boat and is on the bottom.
The rake will be pulled toward the boat until the head of the
rake is resting on the bottom and the handle is roughly perpendicular to
the waters surface. The rake
head should travel approximately 2.5 feet along the substrate.
The rake will then be pulled to the surface and into the boat.
Once in the boat use appendix one (Abundance
Rating Guide) to take an overall aquatic plant abundance rating (Overall Abundance) and an eurasian watermilfoil abundance rating (EWM
Abundance). Plant samples on the rake will be identified and recorded in letter code under the Species Present boxes. and take a voucher sample. If the plant is a native plant or a plant fragment with to few structures to be identified release it back into the water. If there is any question as to the identification of the plant, mark it using the unknown letter code (UNKN) and take a voucher sample for identification by an aquatic plant expert. When taking a voucher sample first fill in the unknown letter code in the Species Information boxes. Second, write down the Voucher # under the Voucher # column. (Voucher #’s go in order; 1,2,3,4…14,15,16…). Next, take the plant and insert it into a moist Ziploc bag. On the Ziploc bag write the Date, Voucher #, Initials of Surveyor, and the Intercept #. Write the same information in the Plant Voucher Record Book (A write-in-the-rain field notebook). All exotic species not vouchered will be put into a bucket to be composted on shore later. |
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