Macrophyte Sampling Protocol : Madison Area Lakes
Macrophyte Sampling Schedule
1.
Macrophytes are sampled on Lakes Mendota, Monona,
Waubesa, Wingra, and Fish Lake. Follow
past years sampling order (Waubesa, Wingra, Fish, Monona, Mendota) and keep the
dates as consistent to past years as possible (see list of dates). Working around the routine LTER sampling,
schedule the macrophyte sampling well in advance in order to sign out a vehicle
and boat when necessary.
Macrophyte Sampling Preparation
1.
With a list of the plants found in past years in the
southern lakes, study the macrophytes using the available keys and the plant
presses.
2.
Collect the equipment listed on the Macrophyte
Equipment List.
3.
Remark and remeasure the line on the two-sided rake
from 2 to 6 meters in 0.1-meter increments.
4.
Remark and remeasure the pole from 1 to 3 meters in 0.5
meter increments (Note that it would be helpful to devise a 1 meter extension
so that the pole could measure to 4 meters.
The extension would have to be removable in order for the pole to fit in
the Suburban.)
5.
Test the spring balances against more accurate
electronic balances.
Macrophyte Sampling Method
1.
Using the site book and the depth measuring pole, move to the 1 meter depth mark and throw
both anchors. It seems easiest to
first throw the anchor opposite the direction the boat is moving and throw the
second anchor in the opposite direction after the line from the first anchor is
taught.
2.
From the Macrophyte Depth Table, find the distance to throw out the rake and hold that mark in one
hand. Also determine the meter mark
that the line should be drawn to. The
table is calculated to determine the starting and ending meter marks to draw in
the line to allow the rake to drag 2 meters on the lake bottom. The table assumes that the line is held
1meter above the water surface while dragging in the line.
3.
Throw the
rake horizontally out the side of the boat stopping it at the correct meter
mark on the line. Allow the rake to
sink to the bottom. Draw in the line, holding it
approximately 1 meter above the water surface.
Stop drawing in the line at the
correct meter mark.
4.
Pull the rake
quickly out of the water. In order
to retain the plants that are attached to the rake, it may be beneficial to
rotate the rake 180 degrees once the rake handle is grabbed (so that the prongs
that were dragged along the bottom are facing up). Then pivot the rake against the side of the
boat and bring it into the boat.
5.
Before removing the plant material from the rake, drape
the long strands over the rake and gently push the plant material down on the
rake.
Assign a rake rating (from 1 to 5) depending on how much the plant
material covers the rake prongs. The
rake prongs are painted in 20% increments.
If the plant material only covers the lowest 20% of the rake prongs,
assign the rake rating a 1. If the plant
material covers between 20% and 40% of the rake prongs, the rake rating is a 2,
and so on (see page on rating description).
6.
If a significant
amount of dirt has been brought up with the plants (i.e. the weight of the
dirt will add significantly to the total weight), wash the plants. Depending
on the volume of the plants, wash them either by keeping them in your hands and
dunking them in the lake or by putting them in the white bucket with the drain
holes.
7.
Separate the
filamentous algae from the rest of the plant material. Separate
and identify the individual plant species, throwing out any dead plant
material. Give the filamentous algae and each plant
species a rake rating (note that it is often necessary to visualize how
much space each species would take up on the rake prongs rather than actually
placing each species onto the rake).
If a plant species can not be identified take a sample back to the
lab by putting it in a ziplock bag with a small amount of water and temporarily
storing it in a cooler. Temporarily assign each unknown species with a common
symbol or name on the data sheet (to be changed to the correct species name
when identified). Stan Nichols at the
WGNHS can be used as a resource (263-7389).
8.
Combine all of
the plant species, keeping the filamentous algae separate, and squeeze out as
much water as possible (it may be necessary to divide up the plant material
into portions to effectively squeeze out the water). Weigh
the plant material (minus the filamentous algae) and record the total
weight. Weigh the filamentous algae and record the weight.
9.
Repeat the above
steps until 4 rake tosses have been thrown.
Normally 2 rake tosses are thrown out each side of the boat to an area
where the water depth is known to be at the desired depth.
10. Move to the next half-meter depth. Macrophytes are collected at each half-meter
water depth from 1 meter to 4 meters. In
the case of Lake Wingra, look at past year’s data to determine the deepest
sampling depth for each transect (often 3 meters). In areas of steep drop-offs, it can be
difficult to anchor the boat at the proper depth and it may be necessary to
drop the anchor upwind and drift to the desired depth.
Macrophyte Sampling Equipment List
Data Sheets
Rake with marked line
Anchors
Pole with meter marks
Depth finder
Site Map (and photos?)
Cooler with ice
Tubs
Pail with holes
Bags (zip-lock)
Seat cushions
Life jackets
Gas
Oars
Sunglasses
Hat Sunscreen
Trolling Motor
2 Scales (500g+) (for plant
weights)
Hand lens
