LTER Macrophyte Sampling  -  Trout Lake

 

This component of the LTER project consists of 2 parts, line transect information and biomass harvesting. This paper describes the locations and techniques used for obtaining the macrophyte data. A species list can be viewed in appendix B.

 

I  Site Locations

 

Sites are designated according to the LTER numbering scheme established for the shoreline of the south basin of Trout Lake and its islands (see fig. 1). The four sites used by the macrophyte component are also used in the LTER fish and crayfish sampling and the descriptions that follow make reference to the shore stakes set for the fish sampling crews. Appendix A details their placement. In addition, photos have been included to identify the landmarks used. Each site establishes a transect line from a proximal shore landmark to a distal shore landmark on a specified compass heading.

 

Site 7 Rocky Reef Bay:

 

Landmarks: Proximal - Large birch with a spike nailed one foot above the base. Also at fish sampling stake D.

Distal - The Rocky Reef Resort main building located in line with the north end of Rocky Reef Island.

Compass Heading: 280°

Map: Figure 2.

 

Site 31 Channel Mouth Island:

 

Landmarks: Proximal - White Birch at fish sampling stake B

Distal - A distant pine (approx. 1 mi.) standing above the canopy in the skyline facing east. Pine is at peak where the landscape shows a rise.

Compass Heading: 83°

Map: Figure 3.

 

Site 50 - Southwest Bay of South Trout:

 

Landmarks: Proximal - Large White Pine in clearing between fish sampling stake C and D. About 9 meters east of stake D.

Distal - The west tip of Haunted Island.

Compass Heading: 13°

Map: Figure 4.

 

Site 56 - Mouth of Mann Creek:

 

Landmarks: Proximal - Large White Cedar with spike nailed 1 foot above base.

Distal - The west tip of Millers Island.

Compass Heading: 41°

Map: Figure 5.

 

II  Line Transects

 

The site descriptions specify a transect line along which presence/absence data is recorded for all macrophyte species. A 0.25 M2 ring placed at 1 meter intervals (except site 7 - 0.5 to 1 M depth where the ring is placed at 2 meter intervals) along transect designates the sampling quadrat. Using SCUBA, species data are recorded along with the total number of quadrats encountered between the following depth intervals: 0.5-1 M, 1-2 M, 2-3 M and 3-5 M. These depth intervals have been permanently established with markers consisting of a commercial 'Earth Anchor' set in the lake bottom with 2 floats secured to it near the bottom. Large boat bumpers are used on the anchors at 3 and 5 meters. The other floats are small polybottles.

 

Between 28 and 52 quadrats are examined within each depth interval at each site. The paths over which the quadrats are laid are shown on the site maps (Figs. 2-5). A species list is given in appendix B.

 

III  Biomass Harvesting.

 

Five replicate quadrats (0.25 M2) are harvested for all above ground biomass at each site at each of three nominal depths: 1.5 M, 2.5 M and 4 M. Samples are removed along a line parallel to shore - located midway between each of the 1, 2, 3 and 5 M anchors. Figures 2-5 show the distribution of the replicates. Four sites with 3 depths and 5 replicates yields 60 samples. A sample may be empty.

 

In the lab, samples are separated by species, placed in labeled paper bags (LABEL: Species/Site/Depth/Rep#), oven dried, and weights recorded. Paper bags used for drying should be purchased in groups to allow the plant weights to be determined by difference using an average tare for a group of bags. Paper bags for determining average tare should be wetted and oven dried in the same manor as the bags containing plant samples.

 

IV  Additional Comments.

 

A. Pre-1987 Data.

In 1987, permanent line transects were established at each of the sites. Biomass samples and line transects observed before 1987 were set by more general descriptions at the site and were not identical year to year.

 

B. Biomass Weights.

Starting in 1989, biomass weights were determined by weighing dried plants in paper bags and using an average tare for the bags. Consequently, values in the data base can be negative and should be considered as present in very small amounts.

 

Appendix A. Fish Sampling Stake Placement

 

Selected sampling sites have been marked with a set of four wooden stakes pounded into the ground. The stakes stand about one foot high and are spaced at intervals of 33.3 meters along the shore. Stakes are labeled A through D with A being the left-most when facing the shore. The distance from A to D is 100 meters.

 

Site 7:            A - On exposed bank with dead log jutting out cannot see

Millers Island. 5 meters south of tiny point.

B - non-descript.

C - Near clump of 3 birch.

D - 5 meters north of upturned birch tree.

 

Site 31:          A - 3 meters north of tall dead birch under cedar tree.

B - At live overhanging birch tree.

C - Little clearing near rotting birch log.

D - At north tip of Island just south of tiny Island.

 

Site 50:          A - Approx. 50 meters west of curve in bay 2 inches left exposed

on stake at log pointing out at lake.

B - At base of alder, just west of overhanging alder.

C - Under big clump of overhanging alder.

D - 5 meters west of little clearing with 2 large pines.

 

Site 56:          No stakes

 

Appendix B. Species List.

 

Ceratophyllum demersum

Chara sp.

Eleocharis sp.

Elodea canadensis

Gratiola aurea

Heteranthera dubia

Isoetes sp.

Juncus sp.

Littorella sp.

Lobelia dortmanna

Megalodonta beckii

Myriophyllum alterniflorum

M. tenellum

M. verticillatum

Najas flexilis

Potamogeton alpinus

P. amplifolius

P. berchtoldii

P. crispus

P. gramineus

P. pectinatus

P. praelongus

P. pusillus

P. richardsonii

P. robbinsii

P. zosteriformis

Ranunculus flammula var. reptans

R. trichophyllus

Sagittaria sp.

Vallisneria americana