an update on the biological monitoring of the lake trafford...
TRANSCRIPT
An update on the biological monitoring of the Lake Trafford Restoration Project, Collier County, Florida: A case for monitoring during restoration
Restoration Goals & Monitoring A primary restoration goal is to return Lake Trafford to a meso-trophic, native macrophytedominated lake with a stable sport fishery. The following monitoring plan elements areproposed to document the post-muck removal lake conditions of Lake Trafford and trackperformance measures of restoration success:
1) seasonal diurnal zooplankton surveys;2) biweekly chlorophyll, phytoplantkton, and PhytoPam analysis;3) annual SAV surveys and Lake Vegetation Index (LVI); 4) benthic and littoral zone macroinvertebrate community assessments; 5) littoral zone fish community structure; 6) sediment surveys and sedimentation rate monitoring; 7) weather station installation and monitoring; 8) modified water quality monitoring plan; and most importantly 9) development of a Lake Management Plan in cooperation with FDEP, SFWMD,
FFWCC, USFWS, ACOE, and Collier County.
BackgroundLake Trafford is a shallow, subtropical lake that was subjected to increasing anthropogenicnutrient loading over several decades. Excessive growth of the invasive exotic aquatic plantHydrilla verticillata choked out native aquatic plants and negatively impacted sport fisheries.Herbicide treatments for Hydrilla removal were successful but the eradication led toaccumulation of a deep organic muck layer throughout the lake and since then Lake Traffordhas been a phytoplankton dominated lake with frequent algal blooms and fish kills. As adirect result of a grass roots initiative, the Big Cypress Basin of the SFWMD implemented arestoration project that involves hydraulic dredging of muck sediments from the lake. Theremoval of over 4 million cubic yards of sediments was completed in 2008. Additional de-mucking is currently underway with an expected completion date of April 2011. Naturalrecruitment of native aquatic macrophytes has been hindered by turbidity and reducedwater clarity from remaining muck being easily re-suspended in the water column fromwind generated waves. As the remaining muck is removed from Lake Trafford, exposing asand and shell/clay bottom, we expect to see dramatic shifts in water clarity,phytoplankton/zooplankton communities, and sedimentation rates.
Performance Measures
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1
13
25
37
49
61
73
85
97
10
9
12
1
13
3
14
5
15
7
16
9
18
1
19
3
20
5
21
7
22
9
24
1
25
3
26
5
27
7
28
9
30
1
31
3
32
5
33
7
34
9
36
1
37
3
38
5
39
7
40
9
42
1
43
3
44
5
45
7
46
9
48
1
49
3
50
5
51
7
52
9
54
1
55
3
56
5
57
7
58
9
60
1
61
3
62
5
63
7
64
9
66
1
67
3
68
5
69
7
70
9
72
1
EchoSounder Transect Profile “A”
Bottom
Height
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1 5 9
13
17
21
25
29
33
37
41
45
49
53
57
61
65
69
73
77
81
85
89
93
97
10
1
10
5
10
9
11
3
11
7
12
1
12
5
12
9
13
3
13
7
14
1
14
5
14
9
15
3
15
7
16
1
16
5
16
9
17
3
17
7
18
1
18
5
18
9
19
3
19
7
20
1
20
5
20
9
21
3
21
7
22
1
22
5
22
9
23
3
23
7
24
1
24
5
EchoSounder Transect Profile “B”
Bottom
Height
Methods & Preliminary Results
Field water quality parameters and phytoplankton communitieshave been sampled biweekly by boat since early March 2010 at 12 locations. Lakesamples are returned to FGCU labs for analysis using PHYTO PAM whichcalculates photosynthesis and can determine for each algal group present in thewater sample (cyanobacteria, green algae and Diatoms/dinoflagellates pooledtogether).
Zooplankton communities have been surveyed in conjunction with the
phytoplankton sampling using standard 367-micron mesh plankton net to exclude nano-plankton. Organisms collected were identified to the lowest practical taxonomic levelwith density estimates for major taxa prepared based on length of tow, diameter of thenet aperture, and Sedgewick-Rafter cell counts. Zooplankton counts were averagedfrom five sites (T-1, T-4, T-6, T-11 and T-12) for each date for this progress report.
Transect profiles of the Lake bottom and survey for submerged aquatic
vegetation (SAV) were completed on 27 May 2010 using a Biosonics Echosounder ™.General depth profiles of the Lake bottom were graphed along with signatures of a soft-bottom or unconsolidated flocculent organic material. Transects were ground-truthedat selected intervals using petite Ponar dredge and PVC pipe. No SAV were detectedfrom the transects or grab samples. Hydrilla verticillata was found in three canals on4/27/10 when touring the Lake with FWC Biologists. Locations of Hydrilla were GPSmapped and sent to FWC and SFWMD for herbicidal treatment for control.
Lake Vegetation Index (LVI) sampling was conducted by FDEP and FGCU
biologists in September 2008. Standard Operating Procedures for MacrophyteSampling (FS7300) and Lake Vegetation Index (LVI) Sampling (FS-7310). No submergedaquatic vegetation (SAV) were found in the four transects in 2008.
Restoration of native emergent (bulrush) and submergent (tapegrass) plant communities are critical components of the restoration plan by the
Florida Fish and Wildlife Commission. A tape grass restoration feasibility study wasinitiated by FGCU in June 2008 during a period of extreme low water levels and highwater clarity. High water levels and decrease water clarity following Tropical Storm Fayein September 2008 likely caused Vallisneria (tape grass) plantings to fail but tubers maypersist. Bulrush planting at one location by FWC was completed in June 2009 withadditional plantings on hold until the completion of the de-mucking project in March2011.
0
20
40
60
80
100
120
140
160
180
200
19-March 16-April 30-April 14-May
Mean zooplankton density per liter Spring 2010
Cladocerans Copepods
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
450.0
500.0
1 2 3 4 5 6 7
Tota
l ch
loro
ph
yll (
µg/
L)
Events
Average concentration of algae in subsurfaceBacillariophycea + Dinoflagellae
Chlorophyceae
Cyanophyceae
0.00
2.00
4.00
6.00
8.00
10.00
12.00
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
1/2
/20
10
1/2
2/2
01
0
2/1
1/2
01
0
3/3
/20
10
3/2
3/2
01
0
4/1
2/2
01
0
5/2
/20
10
5/2
2/2
01
0
oxy
gen
(m
g/L)
Tem
pe
ratu
re (
ċC)
Date
Average water column Temperatureand oxygen at station T6 (central station)
Temperature
oxygen
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1/2
/20
10
1/2
2/2
01
0
2/1
1/2
01
0
3/3
/20
10
3/2
3/2
01
0
4/1
2/2
01
0
5/2
/20
10
5/2
2/2
01
0
Ligh
t e
xtin
ctio
n c
oe
ffic
ien
t (m
-1)
Secc
hi d
isc
de
pth
(m
)
Date
Secchi disc for all stations and and light extinction coefficient
at station T6 (central station)
Secchi disc
Light coefficient extinction
David W. Ceilley, Edwin M. Everham III, Serge Thomas, John A. Morris, and Kory M. Ross, Inland Ecology Research Group at Florida Gulf Coast University
Preliminary Conclusions Lake Trafford abiotic gradients – turbidity, temperature,and light (PAR) attenuation are problematic and the Lakeremains phytoplankton dominated. Water clarity shouldbecome a performance measure to allow SAV recovery.
Native SAV communities are absent based on recenttransects and grab samples, but Hydrilla has been observedin un-dredged canals feeding into the Lake.
Post-dredging restoration activities – SAV plantings andfish stocking – will be influenced by the legacy of thedredging activity, water quality, and control of exotics.
Tracking abiotic and biotic factors will be necessary tounderstanding the current lake system dynamics towardguiding the post-dredging restoration efforts andmanagement activities.
Acknowledgements: We would to thank the Big Cypress Basin Board of the South Florida Water Management District for funding the research and monitoring program at FGCU. Thanks also to the Florida Fish and Wildlife Conservation Commission, Collier County, Florida Department of Environmental Protection, and the Lake Trafford Restoration Task Force. A very special thanks to Ed “Ski” Oleski and Airboats and Alligators staff for all their assistance with the research, monitoring, and tape grass planting. Special thanks to Nicole Packard for design of the Inland Ecology Research Group logo.