The Use of Zooplankton as Bioindicators for the - Southwest Florida ...

The use of zooplankton as bioindicators
for the management of freshwater inflow
in Southwest Florida
SG Tolley 1 , DC Fugate 1 , ML Parsons 1 , BA Denkert 1 ,
M Andresen 1 , JM Neurohr 1 , L Markley 1 ,
K Radabaugh 2 , SE Burghart 2 and EB Peebles 2
1 Florida Gulf Coast University, Coastal Watershed Institute
2 University of South Florida, College of Marine Science

Zooplankton as Bioindicators
● Time scale of disturbance (freshwater inflow) vs.
time scale of response (generation times of weeks to months)
● Biodiversity: 208 zooplankton species
● Target organisms are important trophic links to many commercially
and recreationally important species
● Single sampling gear for entire 47-km stretch of study area,
regardless of depth and bottom type

Sanibel Is
-3.6 rkm
Cape
Coral
2.5 rkm
-5.9 rkm
5.2 rkm
10.6 rkm
7.6 rkm
20.0 rkm
16.2 rkm
26.9 rkm
24.2 rkm
Fort
Myers
37.1 rkm
41.0 rkm
Caloosahatchee River 30.2 rkm
34.4 rkm
and Estuary Franklin Lock
& Dam
Survey Design
nighttime monthly sampling
incoming tide
14 stations (~3.6 rkm apart)
47 km reach of river and estuary
21 months of data collected
(May 2008-Apr 2010)

SeaBird 19-CTD
& OBS
LISST: particle size distribution
& settling velocity
LISST-100, Sequoia Scientific
surface sediment samplers
centric:pennate ratio
PAM fluorometer: benthic
photosynthetic efficiency
Optical O 2, pH, conductivity, temperature,
depth, water-column chlorophyll a
CDOM, red backscatter (turbidity),
phycoerythrin (cyanobacteria)
TSS

Zooplankton composition
Ichthyoplankton (including larval fishes)
● 500 μm mesh
● 5-min oblique tow
● lowest taxa practical
● developmental stage

Figure by EB Peebles
Zooplankton vs. hyperbenthos
NET SEAWARD FLOW
NUTRIENTS

Highly variable freshwater inflow
Seasonal variation in precipitation
(138 cm annually: 70% from Jun-Sep)
Tropical weather systems
Managed inflow (lock, dam & spillway)
Pulsed releases
John Cassani
WP Franklin Lock and Dam (S-79)

Depth (m)
May 2008 (Dry)
Generally well mixed
Moderate stratification upstream
Power plant signature at 30 km
-5 0 5 10 15 20 25 30 35 40
Km upstream
Depth (m)
* Triangles denote station locations
Water column nearly fresh above rkm 2
Saltwater intrusion resembles salt wedge
-5 0 5 10 15 20 25 30 35 40
Km upstream
°C
August 2008 (Wet)
°C

Low salinity zone (2 psu)
Isolated from system
during dry months
Location (rkm)
Regions of low DO
Summer months
Periods of high inflow

Acartia tonsa
Acartia tonsa
Dry
Acartia tonsa
Wet
22000
21000
20000
19000
18000
17000
16000
15000
14000
13000
12000
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Sagitta spp.
May 2008 (Dry)
Sagitta spp.
Dry
Sagitta spp.
Wet
September 2008 (Wet)
28000
26000
24000
22000
20000
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
420
400
380
360
340
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
Gobiidae preflexion
Gobiidae
preflexion larvae
Dry
Gobiidae
preflexion larvae
Wet
340
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Organism density (no. 1000 m -3 )

Americamysis spp. Edotia triloba
Americamysis spp.
Dry
Americamysis spp.
Wet
12000
11500
11000
10500
10000
9500
9000
8500
8000
7500
7000
6500
6000
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
2500
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
May 2008 (Dry)
Edotia triloba
Dry
Edotia triloba
Wet
September 2008 (Wet)
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Anchoa mitchilli
juveniles
Anchoa mitchilli
juveniles
Dry
Anchoa mitchilli
juveniles
Wet
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Organism density (no. 1000 m -3 )

Center of abundance (rkm)
Center of abundance (rkm)
Center of abundance (rkm)
45
40
35
30
25
20
15
10
5
0
-5
-10
Inflow (m
45
40
35
0 1000 2000 3000 4000 5000 6000
Freshwater inflow (cfs)
30
25
20
15
10
5
0
-5
-10
0 1000 2000 3000 4000 5000 6000
Freshwater inflow (cfs)
3s-1 45
40
35
30
25
20
15
10
5
0
-5
-10
r
0 1000 2000 3000 4000 5000 6000
Freshwater inflow ) 21-d (cfs) lag
2 Microgobius spp. (post)
55-d inflow
= 70%
p = 0.0002
45
r
40
35
30
25
20
15
10
5
0
-5
-10
0 1000 2000 3000 4000 5000 6000
Freshwater inflow (cfs)
2 r
= 83% Anchoa spp. (pre)
p

Total abundance (x 10 9 )
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
marine/coastal copepod
Responses of marine and
freshwater species to inflow
Total abundance (x 10 8 )
2.0
1.5
1.0
0.5
0
Predicting total organism
abundance (estuary-wide)
based on inflow
freshwater copepod

Center of abundance (rkm)
>1,000 individuals/tow
Freshwater inflow (cfs)
Gelatinous predators
- prey on larval fishes
- compete with larval fishes for food
~7,000 individuals/tow
Clytia sp.
(50-d lag)

S-79
Location of 90 th percentile (rkm)
41
37
33
29
25
21
17
Location of 90 th abundance percentile (no. m -3 )
Anchoa mitchilli juveniles
Americamysis almyra
0 3000 6000 9000 12000 15000
Freshwater inflow (cfs) 3-d lag
Impingement and habitat compression

Management Implications
1. Dissolved oxygen
Issue
Positioning of hyperbenthic prey in regions of low DO could result in
substantial loss of important food resources for fishes and invertebrates
Mitigation
● Releases of 1,000−1,200 cfs at S-79 during dry months would
result in relocation of these prey species downstream and away
from region prone to low DO

Management Implications
2. Impingement
Issue
Juvenile bay anchovy and Americamysis almyra appear to be blocked
by lock and dam from moving farther upstream during dry months.
Impingement prevents organisms from expanding their range upstream,
concentrating them in confined portion of estuary.
Mitigation
● Releases on the order of 1,000 cfs should be sufficient to
release these organisms from impingement caused by S-79

Management Implications
3. Habitat Compression
Issue
Many species (e.g., fishes, mysids, commercial shrimps, isopods) move
upstream into narrow portion of river in response to reduced inflow:
potential for loss of habitat volume due to funnel shape of tidal rivers.
Habitat compression: increases competition and predator-prey
encounters in same habitat.
Mitigation
● Releases of 800−1,000 cfs would relocate a number of these
species downstream of the restricted portion of River.

Management Implications
4. Maximizing Prey Abundance
Issue
System-wide abundances of a number of taxa were reduced at higher
levels of inflow.
Mitigation
● For many of these taxa, greatest abundances would be
maintained at inflows

Management Implications
5. Gelatinous Predator Blooms
Issue
Gelatinous predators impact fish populations by feeding on developing
eggs and larvae, or by competing with larvae for prey. The hydromedusa
Clytia sp. and the ctenophore Mnemiopsis leidyi were concentrated in
upper, restricted portion of river during periods of reduced inflow.
Mitigation
● Releases of 1,000 cfs or less should result in substantial
movement downstream, relocating these gelatinous predators
away from areas in upper river where potential zooplankton prey
(including larval fishes) are concentrated.

South Florida Water Management District
Peter Doering
University of South Florida
Ralph Kitzmiller
ACKNOWLEDGMENTS
Florida Gulf Coast University
Graduate Students
Holly Abeels Greg Ellis
James Evans Rachel Harris
Brian Hoye Jennifer Nelson
Marijke Noens Bob Wasno
Undergraduate Interns
Travis Brindise Rheannon Ketover
Sarah Larsen
Coastal Watershed Institute
Lesli Haynes
Christal Niemeyer
Lacey Smith
Project funding: SFWMD grants 4500020141 and 4500035194
Congressional Grant P116Z080279, U.S, Department of Education