University of Florida Thesis Or Dissertation Formatting Template

DISSOLVED OXYGEN DYNAMICS IN ISOLATED BLACKWATER WETLANDS

ROBERT F. COMPTON

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING

UNIVERSITY OF FLORIDA

2014

To my loving and supportive parents, Glenn and Mary Compton

ACKNOWLEDGMENTS

This study was funded through grant money from the United States

Environmental Protection Agency and the Florida Department of Environmental

Protection. I would like to thank my advisor and principal investigator, Dr. Mark Brown, and project manager Kelly Reiss. I would also like to acknowledge my committee members Dr. Treavor Boyer and Dr. Matthew Cohen. The FDEP staff provided support for this research, particularly Nijole Wellendorf, Ashley O’Neal, Joy Jackson, and Russ

Frydenborg. Generous field assistance was provided by Sean Sharp, Jenet Dooley,

Erica Hernandez, Fabio S, Valerie Burkett, and Lucia Zarba.

TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ...... 4

LIST OF TABLES ...... 7

LIST OF FIGURES ...... 9

LIST OF ABBREVIATIONS ...... 10

ABSTRACT ...... 11

CHAPTER

1 INTRODUCTION ...... 13

Introduction and Statement of Problem ...... 13 Objectives and Plan of Study ...... 13 Regulatory Framework and Background...... 15 Low DO in Blackwater Wetlands ...... 16 Drivers of Water Column DO in Wetlands ...... 17

2 METHODS ...... 24

Site Selection ...... 24 Field Methods ...... 25 Data Analysis ...... 34

3 RESULTS AND DISCUSSION ...... 39

Dissolved Oxygen ...... 39 Diel Oxygen Curves ...... 40 Environmental Parameters ...... 44 Vertical Dissolved Oxygen Profiles ...... 48 Discussion ...... 51 Conclusions ...... 61

APPENDIX

A: INDIVIDUAL DIEL PLOTS BY WETLAND ...... 74

B: PAIRWISE LINEAR CORRELATION TABLES ...... 78

C: DIEL PLOTS AT MULTIPLE DEPTHS ...... 81

D: GENERAL SITE INFORMATION FOR ALL WETLANDS ...... 83

E: MEASURED ENVIRONMENTAL PARAMETERS BY SITE ...... 85

F: FIELD PHYSICAL/CHEMICAL SITE CHARACTERIZATION SHEET ...... 90

LIST OF REFERENCES ...... 91

BIOGRAPHICAL SKETCH ...... 96

LIST OF TABLES

Table page

2-1 Mean probe depths below water surface...... 38

2-2 Wetland depth classification for 10 FD sites ...... 38

2-3 Mean sonde deployment depths for “deep” and “shallow” wetlands ...... 38

3-1 DO summary statistics for wetland sites ...... 70

3-2 Timing of DO maximums and minimums ...... 70

3-3 Seasonal comparison of mean water quality parameters for ALHD1 ...... 70

3-4 Seasonal comparison of mean water quality parameters for ALFD1 ...... 70

3-5 Water quality by wetland type ...... 71

3-6 Mean daily range of pH and sp. conductance for FR, HR, and FD sites ...... 71

3-7 Soil parameters by depth class and wetland type ...... 71

3-8 Correlation of water quality and soil parameters for all wetlands ...... 72

B-1 Correlation of water quality and soil parameters for FR sites...... 78

B-2 Correlation of water quality and soil parameters for HR sites ...... 79

B-3 Correlation of water quality and soil parameters for FD sites ...... 80

D-1 Site details for all wetlands ...... 83

E-1 Water quality data by site for FR wetlands ...... 85

E-2 Water quality data by site for HR wetlands ...... 86

E-3 Water quality data by site for FD wetlands...... 86

E-4 Canopy cover, SAV presence, GPP, and R for FR wetlands ...... 87

E-5 Canopy cover, SAV presence, GPP, and R for HR wetlands ...... 87

E-6 Canopy cover, SAV presence, GPP, and R for FD wetlands ...... 88

E-7 Soil data for FR wetlands by site...... 88

E-8 Soil data for HR wetlands by site...... 89

E-9 Soil data for FD wetlands by site...... 89

LIST OF FIGURES

Figure page

1-1 Energy systems diagram of a blackwater swamp ...... 23

2-1 Locations of 41 wetland study sites ...... 36

2-2 Field photograph of deployed sonde ...... 36

2-3 Canopy cover photograph methodology ...... 37

2-4 Atmospheric diffusion rates at different depths ...... 37

3-1 Diel DO plots for a forested and heraceous wetland ...... 63

3-2 Mean nighttime and daytime DO of selected wetlands ...... 63

3-3 Diel DO plots for DIFB1 and SAHD1...... 64

3-4 Comparison of morning grab samples with continuous measurements ...... 64

3-5 Examples of observed wetland nighttime DO spikes ...... 65

3-6 Diel DO, water temperature, and air temperature plot ...... 65

3-7 Diel DO and temperature plot measured at SAHD2 ...... 66

3-8 Seasonal comparison of diel DO plots for ALHD1 and ALFD1 ...... 66

3-9 Diel DO and pH plots recorded at LEFD1 and SAHD1 ...... 67

3-10 PCA ordination ...... 67

3-11 Diel DO time series for a deep and shallow wetland ...... 68

3-12 Mean daily DO saturation for individual wetlands at multiple depths ...... 68

3-13 Comparison of DOm to DOwc in three wetlands ...... 69

LIST OF ABBREVIATIONS

ANOVA Analysis of Variance

Chl-a Chlorophyll-a

DO Dissolved Oxygen

DOC Dissolved Organic Carbon

FD Forested – Disturbed

FR Forested – Reference

GPP Gross Primary Production

HR Herbaceous – Reference

LDI Landscape Development Intensity

PCA Principal Component Analysis

RI Recalcitrance Index

R Respiration

Soil %OM Percent Soil Organic Matter

SOP Standard Operating Procedure

SSAC Site Specific Alternative Criteria

TKN Total Kjeldahl Nitrogen

TN Total Nitrogen

TOC Total Organic Carbon

TP Total Phosphorus

YSI Yellow Springs Instruments

Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering

DISSOLVED OXYGEN DYNAMICS IN ISOLATED BLACKWATER WETLANDS

Robert Compton

August 2014

Chair: Mark Brown Major: Environmental Engineering Sciences

Dissolved oxygen (DO) is an important component of water quality and is known to drive numerous biogeochemical and ecological process in wetlands. Isolated wetlands in Florida are characterized as having naturally low-DO due to high organic matter loading, warm temperatures, and stagnant water, though water column DO has not been extensively studied in these systems. Additional quantitative data are needed to improve monitoring techniques, inform development of water quality criteria, and better understand primary drivers of wetland DO. DO was continuously monitored in forty one isolated freshwater wetlands located throughout North and Central Florida over 3 – 7 days. Environmental parameters hypothesized to influence DO dynamics were measured for each wetland.

Mean DO levels were low and not significantly different for reference forested

(1.1 ± 1.1 mg l-1), reference herbaceous (1.2 ± 1.4 mg l-1), and disturbed forested (0.8 ±

0.7 mg l-1) wetlands. Vegetation community type, region, and level of human disturbance did not have a significant effect of DO. DO was found to be primarily driven by the presence of SAV, soil respiratory demand, and physical re-aeration. Wetlands displayed low water column productivity with diurnal behavior strongly driven by

increased nighttime atmospheric gas transfer rates. Depth also had a significant effect on DO dynamics. Results from this study suggest that DO is an inappropriate parameter to base protective numeric water quality criteria in wetlands, as both minimally disturbed and impacted isolated wetlands can display equally low DO levels.

CHAPTER 1 INTRODUCTION

Introduction and Statement of Problem

Dissolved oxygen (DO) is an important component of water quality and is essential to the health and condition of aquatic ecosystems. While the effects of DO on wetland biogeochemical processes and ecology are significant and well understood, the spatial and temporal dynamics of floodwater DO have not been extensively studied in isolated wetlands. An understanding of the patterns and significant drivers of wetland

DO is important for gaining insight into wetland ecosystem processes and for effective monitoring and regulation of these systems. State water quality standards have in the past been unrepresentative of natural background DO found in blackwater ecosystems common to Florida. Previous wetland studies throughout Florida have found that minimally disturbed isolated wetlands can exhibit naturally low DO levels (Reiss, 2005a;

Wellendorf, 2012).

Low DO levels can be the result of a combination of naturally high organic matter loading and warm temperatures as opposed to the effect of anthropogenic influences

(FDEP, 2013). Consequently, there is a need to understand the natural dynamics and primary drivers of wetland dissolved oxygen in isolated freshwater wetlands and to inform the development of protective numeric water quality criteria.

Objectives and Plan of Study

This study focused on collecting necessary background quantitative data to gain an understanding of natural wetland dissolved oxygen (DO) dynamics and to provide techniques to measure and interpret wetland DO data. In all, this study focused on addressing three objectives:

 Collect data on DO in isolated wetlands that can be used to improve monitoring methodologies and inform the development of water quality criteria.

 Characterize water column DO in isolated wetlands on both spatial and temporal scales.

 Document and analyze the effects of human disturbance, vegetation type, and water quality and soil organic matter content on wetland DO.

Study objectives were addressed through continuous monitoring of DO in wetlands located throughout North and Central Florida. Wetlands were a priori classed as reference or disturbed based on the Landscape Development Intensity index score

(Brown and Vivas 2005) of surrounding land use. Reference wetlands were studied to characterize natural background DO. Disturbed wetlands were included in the study and compared to reference wetland data with the aim of evaluating the applicability of protective numeric DO standards based on wetland condition. Study wetland sites were limited to isolated herbaceous and forested systems. Continuous monitoring of DO, pH, specific conductance, and water temperature took place over the course of up to one week. In the early stages of the study, DO was monitored at a single depth in the water column but as the study continued it was realized that monitoring at multiple depths was important to fully characterize water column DO.

Supplemental physical and biological environmental parameters including temperature, pH, nutrients, soil and water organic carbon content, vegetative shading, indicators of primary productivity, and atmospheric diffusion were measured at study wetlands. Primary drivers of wetland DO were identified through investigation of the observed effects of measured environmental parameters on DO dynamics. The effects

of seasonal cycles on wetland DO were explored at a forested and herbaceous wetland via site re-visits during the winter and growing season.

Regulatory Framework and Background

Protective water quality standards are typically based on a water’s natural background condition. In the case of DO standards, numeric criteria has in the past been unrepresentative of blackwater systems in that applicable standards can be higher than what is characteristic of an unimpaired water (FDEP, 2013). The US Environmental

Protection Agency has thus recognized that low DO concentrations can be the result of natural conditions as opposed to anthropogenic impacts:

Naturally-occurring dissolved oxygen concentrations may occasionally fall below target criteria levels due to a combination of low flow, high temperature, and natural oxygen demand. These naturally-occurring conditions represent a normal situation in which the productivity of fish or other aquatic organisms may not be the maximum possible under ideal circumstances, but which represent the maximum productivity under the particular set of natural conditions. Under these circumstances the numerical criteria should be considered unattainable, but naturally-occurring conditions which fail to meet criteria should not be interpreted as violations of criteria. Although further reductions in dissolved oxygen may be inadvisable, effects of any reductions should be compared to natural ambient conditions and not to ideal conditions (USEPA 1986).

To better reflect natural background conditions in Florida, the previous class III freshwater DO standard of “not less than 5.0 mg/l. Normal daily and seasonal fluctuations above this level shall be maintained.” was recently replaced by a regional, percent saturation-based standard that takes into account naturally low DO levels (FAC

62-302.533). Isolated wetlands are not currently subject to explicit narrative or numeric water quality standards. Though these waters are, by definition, considered class III surface waters as described in F.A.C. 62-302.400, no studies have been conducted to determine protective water quality criteria that can applied to isolated wetlands in

Florida. Should wetland DO levels be regulated by state water quality standards, additional data will be needed to understand natural DO dynamics in wetlands to inform the development of appropriate water quality criteria and relevant Site Specific

Alternative Criteria (SSAC) (FAC 62.302.800).

Low DO in Blackwater Wetlands

Freshwaters in Florida and much of the southeast are frequently characterized as

“blackwater” systems, having relatively acidic water that is high in organic matter content and color. Low DO concentrations or deviations from a DO regime characteristic of natural background conditions in these types of aquatic systems is commonly attributed to anthropogenic influences though studies have found low DO in blackwater systems frequently is not a result of human disturbance (Joyce et al., 1985;

Ice and Sugden, 2003).

In the case of wetlands, Florida Department of Environmental Protection (FDEP) characterizes swamps/drainages as systems subject to low DO resulting from natural drivers including warm temperatures, slow or stagnant water, large inputs of BOD and colored dissolved organic matter, and heavy shading (FDEP, 2013). Low DO concentrations are thus considered a result of the combination of limited photosynthetic activity and high rates of oxygen demand. Previous wetland research found minimally disturbed depressional forested wetlands (n=29) to have a mean DO of 2.9 mg/l (Reiss and Brown, 2005a), though this value was based on grab samples not indicative of daily minimum or maximum levels. Daytime DO levels measured in freshwater wetlands

(n=13) throughout Florida as part of the National Wetlands Condition Assessment

(Wellendorf et al., 2012) yielded a mean water column DO of 3.4 mg/l.

Drivers of Water Column DO in Wetlands

Figure 1-1 presents a systems diagram elucidating the primary drivers of DO in blackwater swamps. Wetland DO levels are governed by biological, physical, and chemical processes. The primary mechanisms driving dissolved oxygen concentrations are microbial respiration, photosynthetic production, and diffusion of oxygen from the atmosphere or into the sediment.

Aerobic respiration is carried out by autotrophic and heterotrophic organisms that use oxygen as a terminal electron acceptor for metabolic activity, resulting in a consumption of oxygen and production of carbon dioxide. The large quantities of decomposable organic matter contained in wetlands contribute to high oxygen demand in the water column and benthic layer. Diffusion of oxygen into the benthic layer is the primary DO sink due to the low density of oxygen consuming organisms present in the water column and sediment oxygen demand associated with highly organic soil (Reddy,

2008). Todd (2009) found the large sediment oxygen demand associated with highly organic soils to be a primary driver of DO in Georgia instream swamps and connected streams. Microbial mineralization of soil organic carbon also dominated wetland oxygen demand in freshwater wetland model simulations (Spieles and Mitsch, 2003). Benthic invertebrate communities can also play a role in floodwater oxygen flux via respiration and bioturbation, though oxygen flux rates have not been well studied for wetlands.

Warm temperatures will also significantly increase soil decomposition rate and subsequent sediment oxygen demand (Volk, 1973; Davidson et al., 1998).

The dark, tea-colored water characteristic of blackwater wetlands is a result of high dissolved organic carbon (DOC). DOC is composed of a “broad range of organic compounds including short-chain organic acids to larger-molecule fulvic and humic

acids” (Thurman, 1985). DOC levels present in wetland soil and floodwater are positively correlated with oxygen demand (D’Angelo and Reddy, 1999; Wellendorf et al.,

2012). Studies have thus also shown instream blackwater swamps to be a major BOD input to connected riverine systems (Meyer, 1990; Mulholland and Kuenzler, 1979;

Dalva and Moore, 1991).

Photosynthesis is an autotrophic, light-dependent process which consumes carbon dioxide and produces oxygen. Submerged aquatic vegetation (SAV) and algal communities can thus release oxygen directly into the water column. Light availability for aquatic primary production is governed by vegetative shading, season, and scattering from suspended solids. In more dynamic systems, such as estuaries, the presence of suspended particles can account for a sharp decrease in light intensity as water depth increases (Cloren, 1987). In an un-impacted isolated wetland with stagnant water and minimal wind exposure, suspended solids concentrations may be low and the influence of factors outside the water column, such as vegetative shading, can be a significant driver of primary productivity within the water column. Stagnant water, however, may result in decreased oxygen production as drivers of wetland aquatic productivity such nutrient loading can be influenced by hydrologic regime, as Cronk and

Mitsch (1994) documented long-term increased aquatic gross primary productivity in constructed marshes with high-flow regimes.

As natural wetlands are known to have a high capacity for nutrient loading and processing (Odum and Ewel, 1978; Nichols, 1983; Kadlec and Wallace, 2010), excess nutrient inputs can still drive ecosystem changes including reduction in species richness, increased biomass production, increased algal blooms and floating aquatic

plants, and shifting ecosystem stable states (Verhoeven 2006; Craft 2007). Nutrient- induced algal blooms in wetlands and aquatic ecosystems can lead to a net decrease in

DO resulting from light interception and increased respiration rates. The presence of floating plants in wetlands generally results in a decrease in water column DO or has no significant effect. Floating vegetation can increase shading and act as a barrier to atmospheric oxygen diffusion while providing minimal net oxygen input via root release

(Morris and Barker, 1976; Soda et al, 2007).

While SAV and phytoplankton can release oxygen directly into the water column when present, rooted emergent macrophytes are not known to be a significant source of wetland DO. Oxygen is transferred primarily to the root zone for cellular respiration.

Some radial oxygen loss occurs but is rapidly consumed in the benthic layer before reaching the floodwater (Sorrell and Armstrong, 1994; Brix, 1997). Radial oxygen loss from submerged above-ground portions of emergent wetland plants is not known to significantly contribute to the water column oxygen budget. The presence of rooted macrophytes in treatment wetlands has been shown to decrease average daily DO and dampen diurnal fluctuations, presumably by intercepting light from reaching the water surface and depositing decomposable litter (Kadlec and Wallace, 2010). Rushton et al.

(1997, 2004) found the presence of emergent and floating macrophytes to decrease DO in stormwater detention ponds and the presence of SAV to be associated with increased pond DO.

Atmospheric Oxygen Transfer

Atmospheric oxygen transfer can be a major oxygen sink or source. Oxygen flux from the air into the water column, JO2, is commonly modeled as:

J  K (C  C) O2 L sat (1-1)

Where KL is the oxygen transfer coefficient or transfer velocity, Csat is the saturated DO concentration of water, and C is the bulk DO concentration. While C can be readily measured, KL has not been extensively calculated for wetlands. KL is known to be strongly associated with wind speed, rainfall intensity, water velocity, and flow regime (USEPA, 1985). Stagnant or slow moving water, as is the case in isolated wetlands, will thus have lower re-aeration rates. Kadlec and Wallace (2010)

-1 recommend a range of 0.1 < KL < 0.4 m d for FWS wetlands.

Wetland areas with dense emergent vegetation can have reduced atmospheric oxygen transfer into the water column via reduction of wind velocity and mechanical resistance to mixing (Rose and Crumpton,1996). As such, physical oxygen transfer will play a larger role in DO dynamics for open water wetland systems. Floating aquatic vegetation can also influence re-aeration as mats of Lemna minor and Wolffia spp. were shown to significantly inhibit atmospheric gas transfer at rates dependent upon mat thickness (Morris and Barker, 1976).

Increased atmospheric oxygen flux rates into stagnant water in the absence of wind or rain can also be attributed to thermally driven mixing. Thermal mixing of the water column was shown to occur diurnally in near-stagnant water in parts of the

Everglades (Jenter and Schaffranek, 2003). Convective mixing can thus increase oxygen transfer efficiency via transition to a more turbulent flow regime and circulation of the oxygenated surface film (Schmid et al., 2005). Schladow et al. (2002) documented increased atmospheric oxygen transfer in still water caused by the periodic sinking of cooled, negatively buoyant, oxygenated plumes driven by nighttime

-1 decreases in air temperature. KL values ranged from 0.09 – 0.51 m day and were larger with increasing ΔTair-water.

Vertical DO Stratification

Spatial DO distribution within the water column is an important consideration for monitoring purposes. Current field monitoring SOPs do not take into account vertical

DO stratification in wetlands shallower than 2 feet. In the case of still or slow-moving waters with depths greater than 2 feet, DO measurements are taken at one foot from the surface, one foot from the bottom, and at mid-depth (FDEP, 2008).

Vertical DO profiles have not been well studied in isolated wetland systems.

Cronk and Mitsch (1994) documented rapidly declining DO with depth in freshwater marshes with DO decreases attributed primarily to increased heterotrophic respiration rates near the sediment as opposed to decreasing light availability for aquatic productivity. Studies conducted in physically similar ecosystems such as shallow lakes or ponds also document strong vertical gradients through the water column (Abis, 2002;

Ford et al., 2002).

Existing wetland studies document vegetation and habitat type and physical structure as a strong driver of oxygen stratification. Rose and Crumpton (1996) documented increasing DO stratification and concentration along a gradient of emergent macrophyte density. This trend is presumably due to higher organic matter loading and water surface shading combined with reduced atmospheric O2 flux characteristic of emergent macrophyte stands. This is in agreement with Chimney et al.(2006), which also found open water areas with high densities of submerged aquatic vegetation displayed the greatest degree of vertical DO stratification. Water temperature stratification, which can lead to convective mixing of the water column via

gravitational instability (Jenter and Schaffranek, 2003; Jacobs et al., 1997) has been documented in wetlands and shallow water bodies and has shown to be influenced by emergent vegetation density (Sternberg, 1994; Chimney et al., 2006).

Figure 1-1. Energy systems diagram of a blackwater swamp with focus on dissolved oxygen

CHAPTER 2 METHODS

Site Selection

Study sites (Figure 2-1) consisted of 41 isolated freshwater wetlands throughout

North and Central Florida ecological regions as delineated in Lane (2000). Wetlands were broken into categories based on vegetation type and level of human disturbance so as to allow for the analysis of relationships among environmental parameters within similar environments and to investigate the effects of vegetation and human impact on

DO. Wetlands were classified as either reference freshwater forested wetlands (n=18)

(FR) or freshwater herbaceous wetlands (n=12) (HR) as described in Florida Natural

Area Inventory Guide to Natural Communities of Florida (2010). A third set of forested wetlands located in human dominated landscapes (called disturbed forested wetlands,

FD) was also studied (n=11). The disturbed wetland sites were located in agricultural and urbanized landscapes. Due to the fact that the population of disturbed herbaceous wetlands is relatively small throughout Florida (Reiss and Brown, 2005a) they were not included in this study. Refer to Appendix D for a detailed table of all wetland study sites.

Level of human impact was quantified using the Landscape Development

Intensity (LDI) index (Brown and Vivas, 2005). The LDI index is a level I environmental assessment technique based on the areal empower intensity1 of land uses in proximity of a point or area of interest. Previous studies have related LDI index to wetland condition in Florida (Lane et al. 2003; Reiss & Brown 2005a; Reiss & Brown 2005b) with

1 Areal empower intensity measures emergy per time (empower) per unit area. The units are usually sej*m-2*yr-1 or sej*ha-1*yr-1

scores less than 2.0 representative of minimally disturbed ecological systems. LDI index scores can range from 0-42, and increases with intensity of human activity and disturbance associated with surrounding land uses. Detailed instructions for calculating

LDI index can be found in Reiss and Brown, 2010.

All LDI index calculations were computed using 2008 and 2009 land use cover data generated by the associated water management districts. LDI values were calculated for a 140, 200, and 500 meter buffer surrounding the point within each wetland where water quality was monitored. The 140m zone was selected to determine minimally disturbed reference wetland condition, since this size of the LDI index showed a nearly linear relationship to the calculations for the 100m zone outside of the 40m circular assessment area in previous studies (Reiss et al. 2012). FR and HR wetland sites had an LDI140m < 2.0, FD wetlands had LDI indexes ranging from 2.4 to 35.9.

Field Methods

Candidate sample points were located and selected by examining available aerial imagery and wetland mapping data. Sites were selected based on a priori classification of vegetation type and verified upon field reconnaissance. The presence of at least 20 cm of standing water was required for selection.

Field research spanned three growing seasons. FR and HR wetlands were sampled during the 2011 and 2012 growing seasons and FD wetlands were sampled during the 2013 growing season. Months in which monitoring occurred spanned from

April through November. Refer to the Appendix D for exact monitoring dates for each sample point.

Water Quality Monitoring

DO, pH, specific conductivity, and temperature were continuously monitored at each site for 3 – 7 days. The majority of sites had six to seven full days of data; two sites (CLFD1 and CLHD1) had only three full days of data as a result of tropical storm

Debby (June, 2012). Measurements were taken every fifteen minutes with a Yellow

Springs Instruments (YSI) 6-Series Multi-parameter Water Quality Sonde.

DO was measured using a model 6150 ROX Optical Oxygen Sensor equipped with an anti-fouling automated wiper. The relationship between the measured partial pressure of oxygen (percent saturation) and the solubility of oxygen in mg/L is temperature dependent with colder water having a higher capacity for DO. Chlorinity also has an effect on this relationship to a lesser degree. The sonde automatically carries out the conversion from percent saturation, temperature, and chlorinity (if available) readings to solubility in mg/l using empirically derived relationships (Lenore et al., 1989; YSI, 2008):

Sonde deployment location within each wetland was chosen at a point that had the requisite depth and that was most representative of the wetland system’s overall vegetative cover. Sondes were oriented horizontally and deployed at near half depth or within the upper half of the water column (Figure 2-2). Water column and sonde depths were recorded during probe deployment and retrieval. The depth assigned to a particular wetland for analysis purposes was the average of the two. Table 2-1 presents sonde deployment and water column depths of wetland study sites. Changes in water level over the monitoring period varied among sites presumably due to differing weather, infiltration rates, and ET rates. Total wetland water depth ranged from 17.5 –

73 cm, 21 – 124 cm, and 22 – 62 cm for FR, HR, and FD sites, respectively.

Sonde readings were verified for accuracy before and after each deployment according to field measurement SOP FT 1000 protocol (FDEP, 2008). Data generated from sensors that failed to meet post-deployment verification requirements were dropped.

Water grab samples were collected from wetlands according to surface water sampling SOP FS 2100 protocol (FDEP, 2008) and transported on ice overnight to an

FDEP lab for analysis. Water samples were analyzed for chlorophyll-a, phaeophytin-a, turbidity, color, total organic carbon, total phosphorus, total kjeldahl nitrogen, nitrate- nitrite, and ammonia. Nutrient and TOC water samples were preserved with sulfuric acid to a pH < 2. Analytes were chosen based on their hypothesized influence on wetland DO. FDEP physical/chemical characterization field sheet (form FD 9000-3,

Appendix F) was completed in the field for each wetland in which a water sample was taken. Water quality samples were not taken for wetlands sampled in 2012 (n=5).

Prior to the collection of water quality samples, DO, pH, and specific conductivity was measured using an YSI model 556 Multi Parameter Sensor (MPS) equipped with a membrane DO probe. Measurements were cross checked with sonde data recorded at the time of sampling when applicable. These one-time pH and specific conductance measurements were used in lieu of continuously recorded data when sensors failed verification.

Soil Organic Matter

Soil organic matter content and quality was characterized for wetlands. Three soil cores to a depth of 15 cm were taken at each site. Samples were separated into different depth classes (0-5, 5-10, 10-15cm), with the samples from each depth class being composited among the three samples. Samples were oven dried at 105 C for 48 hours. A mortar and pestle was used to break up the dried soil, after which it was

passed through a 2mm sieve, with passable material to be considered soil matter

(Todd, 2009). Soil organic matter content was determined from loss on ignition (LOI)

(Nelson and Sommers, 1996).

A 1g subsample from each depth class was weighed, combusted in a muffle furnace at 350 °C for 2 hours, weighed again, then combusted at 550 °C for 2 hours and weighed a final time. The percentage of total soil weight lost after both combustion periods was the percent soil OM. The additional mass of soil weight lost from combustion at 550 °C following combustion at 350 °C divided by the total mass of soil weight lost from both combustion periods was the soil recalcitrance index (RI). Higher

RI values indicate less readily decomposable soil organic matter, as the labile portion of soil organic matter will combust at a lower temperature (350 °C for wetland soils) than the recalcitrant portion (Delesantro, 2013). Soil samples were not taken for wetlands sampled in 2012 (n=5) and for two wetlands sampled in 2013.

Canopy Cover

Canopy cover influences numerous ecological processes within forested ecosystems (Paletto and Vittorio, 2009). Cover estimates have often been used to estimate light penetration into understory (Fiala et al., 2006), which can subsequently affect lower-stratum and aquatic community productivity. In FR and FD sites, wetland canopy cover was estimated using hemispherical photography. Photographs were be taken using a Nikon Coolpix 995 digital camera equipped with a fisheye lens from approximately 1 meter above the water surface (Carstenn, 2000). Photographs were taken near dawn or dusk, when the sun was removed from the photographed area or during overcast conditions. At each sample point, five photographs were taken as shown in Figure 2-3.

PhotoScape v3.6.5 was used to convert each image to black and white pixels, with black pixels representing cover and white pixels representative of open space.

MFWorks v2.04 was used to count the number of black and white pixels in each photograph, the percentage of black pixels being the percent canopy cover. The average of the five canopy cover percentages computed for each site was taken as the percent canopy cover for the wetland. To quantify light penetration for HR sites, which lacked a canopy, a visual estimate of the percentage of vegetative shading was recorded for each marsh. This estimate took into account shading from both living and dead plant matter.

Water Column Primary Production and Respiration

Water column primary productivity and respiration was quantified using the light dark bottle technique (Gaardner and Gran, 1927). Samples were collected from FD wetlands (n = 10) and a subset of FR (n=6) and HR (n=5) wetlands. Water was collected in two identical 1 gallon glass jars and a third, smaller glass or plastic container. DO was frequently close to zero at time of sample collection. To avoid reaching anoxic conditions during sample incubation, water samples were artificially oxygenated by shaking each jar for one minute. Each sample jar was topped off with additional sample water and left to stabilize for five minutes. DO was measured in each jar using a YSI 556 MPS handheld multimeter equipped with a membrane DO probe.

Jars were sealed off from atmospheric diffusion using a plastic liner and lid then left to incubate outside for 24 hours, one jar being fully shaded from sunlight and one jar exposed to partially shaded lighting conditions, after which DO was re-measured. Due to logistical constraints, DO measurements and incubation did not take place in-situ.

The 24-hour DO difference observed in the light-exposed jar was taken as the water

column net primary productivity rate; the 24 hour difference observed in the shaded jar as the water column respiration rate. The light-dark bottle analysis for minimally disturbed systems took place during site re-visits the following year after initial sampling and thus could not be directly correlated to measured diel curves.

Atmospheric Oxygen Diffusion

Atmospheric oxygen exchange can be a significant DO source or sink in aquatic ecosystems. Atmospheric diffusion rates can be estimated from diel curves via calculation of a gas transfer constant, K (Odum, 1956).

z(qm  qe ) K  (2-1) Sm  Se

Where qm and qe are the morning and evening rate of DO change, Sm and Se are the morning and evening oxygen saturation deficit, and z is water depth. Equation 2-1 is useful if the bulk oxygen content of the water body can be calculated. In the case of a stratified water body, mid-depth measurements are not sufficient to calculate K using

Equation 2-1 as using a saturation deficit computed as the difference between 100% saturation and a mid-depth DO reading may overestimate K.

In reality the atmospheric gas flux in stagnant waters is driven by the saturation deficit of the air-water interface boundary layer. In blackwater wetlands, DO concentrations near the water surface may be drastically different than bulk water oxygen content. This is an especially important consideration when the water body is not well-mixed and high degrees of vertical oxygen stratification are observed throughout the water column. Use of Equation 2-1 2 to compute K is more applicable for waters with higher DO and a lesser degree of vertical stratification, or if multiple depth readings are available.

For comparative analysis with diel DO profiles, atmospheric oxygen flux in the absence of biological activity were measured directly in a laboratory setting. Nitrogen gas was bubbled into tanks filled with tap water to varying depths to purge out DO.

When DO was near 0.5 mg/l, gas was turned off and oxygen was monitored (Figure 2-

4). The slope of the plots can be taken as the atmospheric diffusion rate for the corresponding DO concentration and depth. Note that for the low range of DO measured (0 - 3 mg l-1), the rate of oxygen flux is constant for each depth. Tank experiments were carried out under minimal wind conditions. Though wind-driven convective mixing can drastically increase gas transfer rates, wind speeds were assumed to be negligible in study wetlands in which most wind could be assumed to be intercepted by emergent macrophytes or trees. The measured atmospheric diffusion rates were thus assumed to be applicable to isolated wetlands.

Linear interpolation was used to estimate diffusion rates and for wetlands in which the sonde was not at 6, 12, or 20 cm. Diffusion rates measured using this method can be extended to wetlands at different depths under the assumption that the spatial distribution of DO throughout the purged tank is similar for that of a low-DO wetland.

Air Temperature

To further investigate the influence of temperature on DO, air temperature and wetland DO were continuously logged over a 14 day period at one FR site (ALFD1) from 2/28/2014 to 3/14/2014. Air temperature was measured at five minute intervals using a General Tools HT10 relative humidity/air temperature data logger deployed slightly above the water column. Wetland DO and water temperature were continuously measured at over the same 14 day period at a mean depth of 20 cm.

Season Variation

Wetland biology, water quality, and biogeochemical processes can be affected by variation of external drivers inherent to seasonal cycles (Stein and Hook, 2005)

(Kadlec, 1999). Seasonal changes such as those in solar radiation intensity, canopy cover, and temperature affect drivers of wetland DO. Seasonal effects on dissolved oxygen dynamics were investigated at one FR (ALFD1) wetland and one HR (ALHD1) wetland. DO was monitored at each site over seven days during both summer and winter seasons. Monitoring took place at equal depths and wetland locations.

Temperature, specific conductivity, pH, and canopy/vegetative cover was also monitored for both deployments.

Vertical DO Stratification

DO, pH, specific conductivity, and temperature were continuously monitored at ten FD wetlands at multiple depths over 6 -7 days. Wetlands were classified based on total water depth as either “deep” (50 – 62 cm) or “shallow” (22 - 32 cm) (Table 2-2). As the objective was to capture data from the majority of the water column, sondes were placed according to relative position in the water column as opposed to being positioned at consistent depths among all sites. Two sondes were deployed at each shallow wetland: one in the upper half of the water column and one in the lower half of the water column. For “deep” wetlands, three sondes were deployed: one in the upper portion of the water column, a second at half-depth, and a third in the lower water column. Table

2-3 presents sensor orientations for deep and shallow wetlands.

DO sensor error was a frequent occurrence during this experiment. Three of the

“deep” wetlands monitored experienced probe malfunction and lacked lower-depth

readings. Two deep wetlands experienced probe malfunction during the sample period and lacked mid-depth measurements.

The uppermost sonde, referred to as “surface”, was typically positioned at approximately 10 cm deep as deploying it at any shallower of a depth would risk long term sensor exposure to air from a dropping water depth over the monitoring period. As

10 cm was relatively close to half depth for most of the shallower wetlands, it was not necessary to deploy a third sonde.

DO measurements in wetlands are typically taken for only a single depth, commonly at mid-depth of the water column. The ability of DO measurements taken at mid-depth to accurately represent average wetland DO throughout the water column was evaluated for two deep forested (COFD1, MAFD1) and one deep “herbaceous marsh”. The “herbaceous marsh” was not included in the rest of the study due to not being characterized as a FR, HR, or FD wetland. A weighted average of DO, DOwc, throughout the measured portion of the water column was calculated as:

DO  DO DO  DO (D  D ) m s  (D  D )* m b m s 2 b m 2 DOwc  (2-2) Db  Ds

Where Ds, Dm, Db refer to the depth in cm of the surface, mid-depth, and bottom measurements, respectively. DOs, DOm, and DOb refer to the DO measured at the surface, mid-depth, and bottom, respectively. Because DOwc is computed from three measurements, it can be taken as a more representative value of the mass of oxygen within the water column at a given time. The error of using only a mid-depth DO measurement, DOm, to represent wetland DO can thus be evaluated by comparing DOm to DOwc.

Data Analysis

Field data were reviewed for reliability checking for pattern and/or unusual gaps in recording periods. Diel oxygen curves were developed for each wetland point.

Continuously monitored sonde data were divided into 24-hour periods for each wetland data set, with data recorded from partial days discarded from the data set. This allowed for the calculation of summary statistics on both a daily basis and over the full monitoring period. Soil and water quality data were checked for outliers and normality in

PCOrd v6.0 (McCune and Mefford, 2011). ANOVA was used to test for differences among wetland characteristics (vegetation type, level of human impact, and region) based on mean weekly DO. Comparisons of means within individual sites (ex. mean daytime DO vs mean nighttime DO, mean daily summer DO vs mean daily winter DO) were accomplished via paired t-tests. Water quality and soil data was compared among different site classifications via Mann-Whitney U test. Significance tests comparing continuously monitored water quality parameters (DO, pH, specific conductivity, temperature) were conducted using means computed over the full monitoring period. All significance tests were run at a 95% confidence level.

Soil and water quality data were compared to mean weekly DO percent saturation to check for correlations using Pearson r. A principal components analysis

(PCA) with correlation cross-products matrix and scores was calculated for a distance- based bi-plot. The main matrix included 13 water and soil parameters. A secondary matrix with DO, latitude, longitude, and LDI index scores was compared to the resulting ordination axes using Pearson r. PCA was deemed an acceptable descriptive tool as relationships among matrix variables were assumed to be linear (McCune and Grace,

2002).

Comparison of Grab Samples and Continuous Monitoring

Previous studies documenting wetland DO (Reiss, 2005a; Wellendorf et al.,

2012) have relied on morning grab samples to characterize DO. To compare results generated from this type of monitoring methodology with results calculated from continuous measurements, morning grab sample data were “simulated”. For each wetland, a single DO measurement was selected from the 15-minute data set by randomly generating a time and day, deeming the corresponding DO measurement the

“grab sample” for that site. Randomly generated times were restricted to occurring between 8 to 11 AM as SOPs generally recommend measurements be taken in the morning so as to limit the impact of diurnal changes in the water quality due to metabolic activity of the organisms in the water. Grab sample DO was compared with continuously measured DO.

Figure 2-1. Locations of 41 wetland study sites. All sites were located in either the North or Central ecoregions as defined by Lane, 2000.

Figure 2-2. Field photograph of a deployed sonde. Photograph courtesy of Robert F. Compton. Sonde Deployed in a Forested Wetland. July 10, 2012. Clay County, Florida. Source: Photograph credit to the author.

A B

Figure 2-3. Canopy cover photography methodology. A) Canopy cover photograph locations relative to sonde. B) Hemispherical canopy cover photograph converted to black and white pixels. Photograph courtesy of Robert F. Compton. Black and White Pixel Canopy Cover Photograph. October 21, 2012. Levy County, Florida. Source: Photograph credit to the author.

6 cm 3 12 cm 20 cm

)

l 2

( 1

D 0 0 5 10 15 Hours

Figure 2-4. Atmospheric diffusion rates at different depths. Rates represent diffusion of oxygen in the absence of biological activity.

Table 2-1. Mean probe depths below water surface. Proportional depth refers to the depth of the sonde as a fraction of total water column depth. Wetland type Mean probe depth Mean wetland water Proportional depth (cm) depth (cm) FR 14 ± 6 35 ± 14 0.38 HR 18 ± 9 56 ± 36 0.35 FD 18 ± 8 46 ± 14 0.39

Table 2-2. Wetland depth classification for 10 FD sites Site code Depth class Water depth (cm) ALFD4 Shallow 24 ALFD2 Shallow 32 FLFD1 Shallow 22 DUFD1 Deep 50 COFD1 Deep 50 CIFD1 Deep 53 MAFD1 Deep 58 ALFD3 Deep 58 PAFD1 Deep 50 HIFD1 Deep 62

Table 2-3. Mean sonde deployment depths for “deep” and “shallow” wetlands Sensor orientation Mean sensor depth (cm) Sensor depth range (cm) Shallow wetlands (n=3) Surface 9.3 ± 1.8 7.5 - 11 Bottom 23.3 ± 6.0 17 – 29 Deep wetlands (n=7) Surface 10.0 ± 2.5 5 – 13 Mid-depth 25.5 ± 4.7 17.5 – 25 Bottom 37.1 ± 5.1 31 – 42.5

CHAPTER 3 RESULTS AND DISCUSSION

This section will first present a summary of basic DO statistics by site type followed by a more detailed presentation of observed diel DO curve characteristics. Next, measured environmental parameters are summarized and their relation with wetland DO are explored. Finally, the effects of depth on wetland DO are presented via analysis of vertical DO profiles.

Dissolved Oxygen

Table 3-1 shows DO summary statistics calculated by wetland vegetation, region, and level of human disturbance. ANOVA was used to test for significant differences in DO among site classifications. No significant differences in mean weekly DO were found between site classes based on region, vegetation, or level of disturbance at a 95% confidence level.

Individual wetland mean DO values ranged from 0.9 – 52.5% saturation but, as can be seen in Table 3-1, were consistently low when computed together as a mean DO of multiple wetlands across different site type categories. The highest daily mean DO measured was 67.5% saturation recorded at SUHD1 on

8/17/2012 (Appendix A). Wetlands typically experienced low minimum daily DO concentrations as mean daily minimums were close to anoxic conditions for all wetland types (Table 3-1). No significant differences between daily DO minimums or maximums were found among wetland vegetation type, level of disturbance, or region. None of the wetlands monitored met the current DO water quality criteria for class III freshwater bodies. SUHD1 and LEFD2

(Appendix A) came the closest to meeting the revised DO standard, with 14% of

daily average DO saturation measurements falling below the Peninsula region

38% DO saturation threshold.

Diel Oxygen Curves

Figure 3-1 shows representative wetland diel oxygen curves for a FR and

HR wetland. Refer to Appendix A for DO diel plots for all wetland sites. Daytime was defined as spanning the hours between sunrise and sunset. Diel plots reveal that the majority of wetlands had low or dropping daytime DO concentrations with sudden, pronounced nighttime DO “spikes” followed by decreasing DO which continued into the morning or early afternoon (Figure 3-1).

Nighttime DO spikes accounted for the majority of daily DO maximums, as maximums typically occurred during nighttime hours (Table 3-2). Only four wetlands (SAHD1, SAHD3, DIFB1, CLFD1) experienced maximum DO concentrations during daytime hours.

Wetland diel plots (Appendix A) reveal that the majority of wetlands not only showed low mean daily DO but also did not display large daily DO ranges or high daily DO maximums. Twenty four out of forty one wetlands never reached a daily maximum DO percent saturation greater than or equal to 33% and six of those wetlands never had a single DO saturation reading greater than 10% saturation throughout the field sample period. Anoxic conditions were reached at some point during the day for 69%, 68%, and 76% of sample days for FR, HR, and FI sites, respectively. Two wetlands, LAFD1 and HEHD1, were anoxic throughout the full monitoring period.

Mean nighttime DO saturation was significantly higher (p<0.05) than daytime DO for seven FR, five HR, and one FD (Figure 3-2). Nighttime and

daytime DO saturation showed no statistical difference for all remaining wetlands except a single FR wetland (DIFB1) in which daytime DO was significantly greater than nighttime DO. Wetlands in which daytime and nighttime DO were not significantly different typically experienced extended periods of anoxic conditions or were characterized by rising DO during daytime hours which peaked shortly after sundown.

Wetlands with the highest weekly mean DO were two FR sites (SUFD1 and DIFB1) and three HR sites (SAHD1, SAHD3, and SUHD1). Diel DO plots for

DIFB1 and SAHD1 are displayed in Figure 3-3. These sites displayed daytime production of oxygen which began around noon and peaked in the evening and dropped off at night. Nighttime DO spikes, though present in a minority of sample days, were not as distinguishable in these five wetlands. This follows as daytime oxygen production accounted for a significantly larger daily increase in

DO than did nighttime DO spikes. Taking this into account, it follows that these five sites had the largest mean daily DO fluctuations of all study wetlands.

Figure 3-4 presents randomly generated morning grab samples plotted against continuous measurement data for all wetlands. Morning grab samples were below the weekly median in 23 out of 41 wetlands. In 16 wetlands grab samples were below the first quartile of continuous measurements; 9 wetlands had grab samples exceeding the third quartile of continuous measurements.

Note from Figure 3-4 that wetlands with the highest DO had the largest relative discrepancy between grab samples and continuous data, with grab samples primarily at or below the first quartile of weekly data. As mentioned previously, these wetlands also tended to display the highest daytime oxygen production

which typically began around noon; grab samples were measured only between

8 and 11 am. Mean DO of grab samples for FR, FH, and FD wetlands was 0.95 ±

0.90, 0.48 ± 0.73, 0.99 ± 0.81 mg l-1.

Nighttime DO Spikes

Discernable DO increases during nighttime hours were observed in 32 wetlands (Figure 3-5). Nighttime DO spikes ranged from 0.1 – 4.1 mg l-1 and were a significant driver of diel curves, accounting for 100% of the daily DO range in 24 wetlands. Mean oxygen transfer coefficients, KL, calculated for night time spike events were 0.25 ± 0.14, 0.52 ± 0.40, and 0.46 ± 0.36 m day-1 for FR,

HR, and FD wetlands respectively. Nighttime spike KL values were significantly larger than mean KL values measured in daytime laboratory experiments (0.09 ±

0.02 m dayˉ¹) which represent the gas transfer coefficient associated with diffusion in the absence of biological activity. Spikes occurred one or multiple times per night (Figure 3-5B) at a relatively rapid rate; mean rates of DO increase over nighttime spikes was 0.60 ± 0.22, 0.95 ± 0.50, 0.74 ± 0.36 mg l-1 hr-1 for FR,

HR, and FD wetlands, respectively. Magnitudes of nighttime DO spikes were not significantly different among wetland types though KL values were significantly less in FR sites than in HR and FD wetlands. In 30 out of the 32 wetlands displaying nighttime DO spikes, the corresponding rate of DO increase was greater than the estimated rate of atmospheric oxygen diffusion in the absence of biological activity (Figure 3-5A).

Figure 3-6 presents diel DO and air and water temperature plots recorded over 14 days at ALFD1. Three distinct relationships between air and water temperature can be observed from Figure 3-7. From 2/28 through 3/3 and 3/8 –

3/11, air temperature was well-above water temperature during the day and dropped below water temperature at night. From 3/4 – 3/7, air temperature was primarily below or near water temperature though on 3/6, air temperature slightly exceeded water temperature. Thirdly, air temperature never dropped below water temperature on the night of 3/11.

Nighttime spikes can be observed from 2/28 – 3/3 and 3/8 – 3/11, with maximum DO concentrations occurring at an average of 10.0 ± 3.5 hours after sunset. In the second case, from 3/4 – 3/7, nighttime DO spikes were either non- existent or occurring during daytime hours. The timing of peak DO observed on

3/6 corresponded to a precipitation event recorded at a nearby weather station.

Finally, on the night of 3/11 when air temperature never dropped below water temperature, no discernable nighttime DO spike can be observed. Patterns in air temperature relative to water temperature thus appear to be related to diel dynamics at this wetland.

Patterns in water temperature may also have been related to DO dynamics. With regard to nighttime DO spikes, the time at which water temperature crested at night was correlated with the timing of DO spikes. The beginning of the rapid nighttime DO increase seen in most wetlands consistently corresponded to the crest of the water temperature profile (Figure 3-7A).

Additionally, the magnitude of daily water temperature fluctuations was correlated with daily DO ranges, as sites with larger temperature ranges tended to have wider DO ranges (Figure 3-7B).

Seasonal Variation

Seasonal variation in diel DO behavior is shown in Figure 3-8 for a FR

(ALFD1) and HR (ALHD1) wetland. Data were measured at equal depths in the same location during both winter and summer seasons. For both wetlands, daily mean DO was significantly greater in winter than summer (Table 3-3, 3-4). Water temperature was significantly lower in winter than summer.

As can be observed in Figure 3-8, daily DO ranges were larger in winter than in summer. Maximum DO concentrations consistently occurred later in the day during winter in ALHD1 (Figure 3-8A), peaking at a mean time of 6.1 ± 2.6 and 4.3 ± 0.7 hours after sunset for January 13’ and July 12’, respectively. This was not the case for ALFD1 (Figure 3-8B), in which case maximum DO concentrations occurred earlier in the day during winter than summer. In both cases, DO maximums were reached at night or in the early morning. Anoxic conditions were reached at least once during the monitoring period for all monitoring periods except in ALFD1 in wintertime (Figure 3-8B). Note that in

ALFD1 canopy cover was less in winter (Table 3-3) and in ALHD1 vegetative cover was less during wintertime (Table 3-4).

Environmental Parameters

A summary of measured water quality parameters by wetland type is shown in Table 3-5. Wetland vegetation and level of human disturbance did account for significant differences in some water quality parameters.

Herbaceous wetlands showed significantly higher (p<0.05) levels of TN, chlorophyll-a, and phaeophytin-a than forested systems. Chlorophyll-a levels were highly variable for all wetland types, ranging from the MDL of 0.55 µg l-1 to

as high as 120 µg l-1 (Refer to Appendix E for water quality results by wetland).

Six FR and two FD wetlands had chlorophyll-a levels at the MDL. Note that TN was predominantly in the organic form for all classifications as NO3-NO2 and NH3 were consistently low or near the minimum detection limit. Color was significantly different among FR, HR, and FD wetlands, with FR showing the highest color.

Impacted sites showed higher pH and TP values but lower TOC than minimally disturbed wetlands. Two FD wetlands, MAFD1 and ALFD2, had TP values (1.7 and 1.8 mg l-1) well above all other wetlands, the next highest TP value being 0.75 mg l-1. These sites both displayed low mean weekly DO (3.3 and 7.6 %saturation) and extended periods of anoxic conditions. These sites also did not show daytime oxygen production. MAFD1 displayed a higher than average chlorophyll-a level (47 μg/l) while ALFD2 was at the MDL.

Mean daily fluctuations of pH and specific conductivity, parameters which were continuously monitored over the sample period, is shown in Table 3-6.

Specific conductivity was relatively consistent throughout the sampling period and typically did not display distinguishable patterns with time or large diel fluctuations. Wetland pH was relatively stable in the majority of sites, as shown in Figure 3-9A. Many wetlands, however, displayed diel pH fluctuations characterized by daytime pH increases followed by nighttime pH drops. The minority of wetlands that displayed high levels of daytime oxygen production (see

Appendix A: BAHD1, DIFB1, SUFD1, SAHD1, SUHD1) were generally characterized by this pH regime (Figure 3-9B). This was less common in wetlands that did not show daytime oxygen production (Figure 3-9A).

Soil organic matter content (Table 3-7) did not show any differences among vegetation type, region, or level of impact for any depth class. Organic matter content generally decreased as sample depth increased. A subset of sites encountered a mineral horizon within the 15 cm sample depth, resulting in a more rapid decrease in %OM. RI taken from the upper 5 cm of soil was significantly lower for impacted sites, though deeper samples did not show any differences among wetland type.

Mean percent canopy cover for FR and FD wetlands was 83 ± 5% and 87 ±

3% (Appendix E), respectively, and showed little variation among sites, ranging from 75 – 90% for all forested systems. Canopy cover was not significantly different between FR and FD wetlands. Percent vegetative cover for HR wetlands (27 ± 21%) showed a wider range of variability, ranging from 5 – 90%.

More sunlight would have thus reached the water column in herbaceous wetlands. The amount of sunlight reaching the water column, based on canopy cover, would presumably not have been significantly different between FR and

FD wetlands though.

Correlation Analysis of Environmental Parameters

Pairwise linear correlation among environmental parameters for all wetlands is shown in Table 3-8. Refer to Appendix B for pairwise correlation tables by wetland type. The strongest correlation observed with regard to DO was with phaeophytin-a (Pearson r = 0.93) in FR wetlands. DO was positively correlated with daily temperature range (r = 0.78) in HR wetlands. DO was weakly negatively correlated with soil %OM in FR (r = -0.50) and HR (r = -0.55) sites. Both color and TOC showed positive correlations (r > 0.70) with total

nitrogen in forested sites. LDI140m, not shown, was positively correlated with pH

(r = 0.67) and negatively correlated with TOC and color (r = -0.50). Note that for

FD wetlands, in which TP levels were significantly higher than in FR or HR sites,

TP was not correlated with chlorophyll-a or phaeophytin-a. TN, however, was positively correlated with chlorophyll-a (r = 0.49) and phaeophytin-a (r = 0.83) across all wetland types.

PCA ordination (Figure 3-10) based on wetland water quality and soil data revealed separation of sites based on human impact. Note that DO did not contribute to the computation of the bi-plot distance space, but was instead correlated against the axis computed from other measured environmental parameters in the main matrix. Color (Pearson r = 0.8), TOC (r = 0.8), pH (r = -

0.8), and LDI at 140, 200, and 500 meters were strongly correlated with axis 1.

Note that LDI, a secondary matrix variable which also did not contribute to the distance space computation, was correlated with the observed separation of impacted sites along axis 1. DO was correlated with axis 3 (r = 0.6). Axis 3, which explained the least amount of variance, was correlated with temperature (r

= 0.7), soil %OM to 5 cm (r = -0.7) and specific conductivity (r = -0.6). Impacted sites show separation with reference sites along Axis 1. Note that DO is nearly orthogonal to the apparent gradient of human impact as seen in the PCA plot.

Measured Primary Production & Respiration

Mean water column GPP measured via light-dark bottle analysis was low for FR (0.009 ± 0.014 mg DO l-1 hr-1), HR (0.017 ± 0.019 mg DO l-1 hr-1), and

FD(0.013 ± 0.019 mg DO l-1 hr-1). Mean water column respiration rates for FR,

HR, and FD sites were 0.045 ± 0.020, 0.050 ± 0.022, and 0.079 ± 0.048 mg DO l-

1 hr-1, respectively (Appendix E). No significant differences in GPP or respiration rate were found among wetland type. Light-dark bottle measurements do not take into account GPP attributed to submerged macrophytes. Degree of submerged macrophyte presence (excluding floating vegetation) from field data sheets was characterized as “absent or rare” for 78% of sites and as “common or abundant” for 22% of sites surveyed (Appendix E). Seven of the eight wetlands characterized as having “common or abundant” submerged macrophytes were

HR sites. Of the five wetlands showing the highest mean DO concentration, four had “common or abundant” submerged macrophyte levels.

Vertical Dissolved Oxygen Profiles

Wetland DO diel curves over a 7 day period for a “deep” and “shallow” wetland are shown in Figure 3-11. Refer to Appendix C for diel DO time series for all wetlands sampled at multiple depths. Examination of diel curves reveals that nighttime DO spikes are least visible in diel plots recorded at the surface in deep wetlands and are more distinct when measured at deeper depths or at the surface in shallow sites. Also note that DO spikes are both delayed and smaller in magnitude in deeper measurements.

Mean DO percent saturation at different depths for all wetlands sampled

(10 FD sites sampled at multiple depths) is shown in Figure 3-12. DO concentrations were higher at shallow depths for the majority of the week.

Deeper measurements were more frequently at or near 0% saturation. The majority of sites showed significant differences in mean daily DO concentrations among depths. Increasing measurement depth from the water surface either reduced or, for two wetlands, had no effect on mean daily DO concentrations.

One shallow wetland, ALFD4, and one deep wetland, MAFD1, did not show a significant difference (p>0.05) between surface and bottom mean daily DO concentrations. This same deep wetland did not show a significant difference between surface and mid-depth mean daily DO. None of the deep wetlands monitored displayed differences between mid-depth and bottom mean daily DO concentrations.

Note that for deep wetlands in which three sondes were placed, the magnitude of the DO difference between the surface and mid-depth was greater than that of the difference between the mid-depth and bottom (Figure 3-12:

COFD1 and MAFD1). This follows as DO concentrations were near 0% saturation more frequently as depth from the surface increased. Proximity of the benthic layer may have had a negative influence on DO as mean surface DO concentrations for “shallow” wetlands (0.61 ± 0.23 mg l-1), was significantly less than mean surface DO for “deep” wetlands (1.50 ± 0.61 mg l-1).

Magnitude of DO stratification was standardized to difference per vertical centimeter so as to account for different vertical distances between sensors among study sites. DO decreased at a mean rate of 0.04 ± 0.03 mg l -1 cm -1 for shallow wetlands. For deep wetlands DO decreased at a mean rate of 0.05 ±

0.02 mg l -1 cm -1 throughout the water column. The most stratified wetland sampled (DUFD1) had a mean DO difference of 1.7 ± 0.8 mg l-1 over 24 cm. The magnitude of DO stratification was not found to be strongly correlated with any of the complimentary water, soil, or canopy cover parameters measured.

Maximum DO stratification typically occurred at night, coinciding with the beginning of peak surface DO concentrations (Table 3-9). DO was the least

stratified in the early morning as this was typically when the falling limbs of the

DO plots following the night time spike overlapped. Also, diel plots revealed that all or most of water column frequently approached anoxic conditions during the early morning to early afternoon. Breakdown of DO stratification occurred at least once for most days as 79% of the sample days experienced a period of minimal

DO stratification throughout the full water column (difference less than 0.2 mg/l throughout the measured water column). Diel curves also showed that timing of

DO maximums was sensitive to depth. In shallow wetlands, maximum daily DO concentrations at the bottom of the water column occurred an average of 2.2 hours later than those at the surface. In deep wetlands, maximum daily DO concentrations in the lower water column occurred an average of 4.6 hours earlier than those at the surface.

Accuracy of Mid-Depth DO Measurements

Figure 3-13 shows DO measured at mid-depth (DOm,) overlaid against the weighted average of wetland DO over three depths (DOwc,). Diel curves at three depths for COFD1, MAFD1, and the “herbaceous marsh” can be found in

Appendix C. DOwc was significantly higher than DOm for COFD1 and the herbaceous marsh. Mean error of individual measurements of DOm relative to

DOwc, computed as the difference between DOm and DOwc divided by DOwc, was

50% (0.25 mg l-1), 21% (0.10 mg l-1), and 54% (0.60 mg l-1) for COFD1, MAFD1, and the herbaceous marsh, respectively. Error was significantly less for MAFD1 as the full water column was anoxic or close to anoxic for much of the week and

-1 DOs, DOm, and DOb were thus frequently all close to 0 mg l . This was not the case for COFD1 and the herbaceous marsh as surface measurements taken at

these wetlands displayed daytime DO production while mid-depth and bottom readings showed low DO during the daytime with nighttime peaks. Discrepancies between DOwc and DOm of the herbaceous marsh were largest during daytime hours but did not show any time-dependent pattern for COFD1 and MAFD1.

Discussion

Results from this study can provide insight into understanding wetland DO dynamics while informing DO monitoring methodologies and the development of appropriate water quality criteria as applied to wetland systems. Wetland DO values, when measured continuously, were uniformly low regardless of site characteristics as vegetation type and level of human disturbance were not shown to have a significant effect on wetland DO. Additionally, zero of all forty one wetlands monitored met the current state numeric DO criteria for class III waters. The lack of a significant difference in DO between reference and disturbed sites suggest that the development of a threshold-based protective numeric water quality standard for DO in isolated wetlands may be inappropriate.

The majority of isolated wetlands in this study exhibited diel DO behavior markedly different than the characteristic oscillating DO levels that peak in the late afternoon and reach a minimum at dawn (Odum, 1956) generally observed in aquatic ecosystems. Finally, depth from water surface had an effect on both mean DO concentrations and diel behavior as deeper measurements showed significantly lower mean DO concentrations and drastically different timing of maximum DO levels.

Drivers of Wetland DO

Mean DO values, when computed from continuous data, were low for all site types, as no wetlands met the current state numeric DO criteria for class III waters. Additionally, the majority of wetlands showed near-anoxic daily minimums, even in wetlands with relatively high mean DO. Wetland vegetation type (herbaceous or forested) and degree of human disturbance were not shown to have a significant effect on DO. This was not consistent with Rose and

Crumpton (1996) in which the density of rooted emergent macrophytes was negatively associated with wetland DO. With regard to vegetation, the abundance of SAV was somewhat positively associated with wetland DO as four of the five wetlands with the highest recorded DO had “common” or “abundant” levels of submerged macrophytes. These same wetlands displayed high levels of daytime oxygen production, a characteristic not observed in the majority of diel curves. Light-dark bottle experiments yielded low water column GPP values indicating that observed daytime oxygen production was most likely not attributed to phytoplanktonic communities. This is further supported by the observation that, aside from the strong positive correlation of DO and phaeophytin-a in FR wetlands, DO was generally not positively associated with photosynthetic pigment concentrations.

Measured water quality parameters were not shown to have a significant relationship with wetland DO. Though a number of water quality parameters showed separation between reference and disturbed sites (TP, pH, color), as characterized by LDI, these parameters were not shown to influence wetland DO as the DO gradient observed in the PCA as it was nearly orthogonal to LDI.

Organic carbon content of the water column also did not have a strong influence on DO as negative correlations between DO and TOC or color were not observed. This not in agreement with Wellendorf (2014) in which DO was shown to be negatively correlated with floodwater organic carbon content in freshwater wetlands.

Results indicate soil %OM was somewhat influential to DO levels as pairwise linear correlation and PCA yielded weak negative correlations between

DO and soil %OM. Also, surface DO measurements in wetlands classified as

“shallow” were significantly lower than surface DO measurements in wetlands classified as “deep” as proximity to the benthic layer presumably swayed the balance between atmospheric re-aeration and diffusion into the sediment. This is in agreement with previous studies as sediment oxygen demand is recognized as the primary water column DO sink in wetlands (Todd, 2009; Reddy, 2008).

Temporal Dynamics

The majority of isolated wetlands in this study exhibited diel DO behavior markedly different than the characteristic oscillating DO levels that peak in the late afternoon and reach a minimum at dawn (Odum, 1956) generally observed in aquatic ecosystems. Peak DO generally occurred well after sunset, with little to no oxygen production during daytime hours. Low DO during daytime hours can most likely be attributed to high oxygen demand and minimal sources of

GPP in the water column, as quantified by light-dark bottle results and the generally rare occurrence of SAV observed in study wetlands. Compared to productive aquatic systems, daily DO ranges observed in wetlands were relatively small.

Diel curve behavior was highly influenced by nighttime DO spikes which accounted for all or most of the daily DO range in many wetlands. Nighttime DO spikes were most likely a physical process driven by increased atmospheric oxygen flux at night. Increases in DO associated with nighttime spikes occurred at a more rapid rate than the estimated daytime atmospheric oxygen diffusion rate measured in the absence of biological activity (Figure 3-5). This comparison suggests that the observed DO spikes could not have been a consequence of decreased nighttime respiratory oxygen demand. Thus, the increasing concentrations can only be attributed to either nighttime oxygen production within the water column or increased gas transfer rates. Increased nighttime biological or chemical oxygen production within the water column is an unlikely explanation as no known mechanism that could account for the DO increases observed exists.

One likely mechanism that can account for observed increases is cooler nighttime air temperatures driving the formation of a gravitationally unstable surface layer that sinks through the water column as a plume of dense oxygenated water, as observed in laboratory studies (Schladow et al., 2002). KL values computed for the observed nighttime spikes were within the range of KL values recorded in lab experiments. Though air temperature was only recorded at one study wetland (Figure 3-6), measurements from this wetland show that air temperature patterns relative to water temperature can drive the timing and occurrence of nighttime DO spikes. When daily air temperatures did not range above and below water temperature, the occurrence of nighttime spikes was disrupted. This is consistent with the proposed mechanism as this pattern would

not result in the formation of the unstable surface layer. Attributing DO spikes to this mechanism is further supported by the observation that daily DO ranges were positively correlated with daily water temperature ranges. Plumes were shown to occur periodically following the initial sinking event in lab studies. This periodic sinking dynamic is partially in agreement with the observed multiple nighttime peaks seen in a subset of diel plots. One discrepancy with this model, however, was elucidated in vertical DO profiles in which the onset of nighttime spikes occurred significantly later as depth increased whereas lab experiments documented a rapid sinking of plumes throughout the entirety of the water column.

The combination of low water column GPP and increased nighttime oxygen transfer rates can thus explain the pattern of low daytime DO and higher nighttime DO i.e. an inversion of the diel pattern common to productive aquatic systems. Daytime productivity, exhibited in a small subset of study wetlands, had daily DO ranges significantly larger than in wetlands in which nighttime spikes accounted for the majority of daily DO ranges. Nighttime DO spikes explained by thermal convective mixing are thus muted and possibly overlooked in diel curves measured in productive aquatic systems. Increased nighttime gas transfer rates should be taken into account when estimating respiration rates from diel curves based on the rate of DO decrease during nighttime hours as KL values may be drastically between nighttime and daytime due to alternate gas transfer mechanisms. The use of Equation 1-1 to model atmospheric oxygen transfer at night can thus lead to an underestimation of respiratory oxygen demand and introduce error into ecosystem metabolism calculations.

Vertical Profiles

Depth from water surface had an effect on both mean DO concentrations and diel behavior as deeper measurements showed significantly lower mean DO concentrations and different timing of maximum DO levels. The sharp DO decreases with depth observed were most likely a result of high oxygen demand near the sediment layer, as was observed by Cronk and Mitsch (1994). As these systems generally had low GPP within the water column, the drop off in DO with depth was likely not a result of decreased light attenuation. Increasing depth also resulted in a dampened nighttime DO spikes, though it was not clear why this was the case.

This may be an important consideration for monitoring purposes, as current SOPs do not require measurements taken at multiple depths for surface waters that are two feet (approximate depth of the deepest wetland monitored) or shallower (FDEP, 2008). Some error is introduced when DO is only measured at mid-depth. As wetlands are low-DO systems, it follows that while the relative error of single-depth measurements in representing DO in the water column may be large (21-54% for this study), mean absolute error of measurement was low

(0.1 – 0.6 mg l-1). Error may be larger for more oxygenated systems, particularly if there is productivity near the water surface, as was observed in the

“herbaceous marsh”. Daytime grab samples would be particularly problematic for this wetland as maximum error occurred during daytime hours. Nonetheless it is important to accurately record the measurement depth as measurements taken with depth differences as small as 8 cm were shown to have statistically different DO concentrations.

Studies involving the comparison of DO measurements among multiple wetlands should be wary of comparing DO among wetlands with drastically different water depths, as the depth of sample and proximity to the benthic layer can influence DO levels. Performing statistical inference with DO measurements, which vary spatially and temporally, and water quality and soil parameters, which are generally constant, can thus be problematic.

Wetland DO in Context of Water Quality Criteria

Results from this study suggest that the development of a threshold-based protective numeric water quality standard for DO in isolated wetlands may be inappropriate. Threshold-based protective numeric DO criteria is suitable for regulating productive aquatic systems as deviations below a threshold value may represent impaired conditions. Current state water quality criteria addresses low

DO attributed to natural background conditions by specifying the applicable standard as 0.1 mg/l below the natural DO saturation of the associated water.

Results from this study suggest that low DO in isolated wetlands is not necessarily a consequence of human impact, as minimally disturbed wetland DO was not statistically different from DO measured in impacted systems, thus a threshold-based standard would be illogical in gauging the impairment of such a water. Also, many of the minimally disturbed systems monitored were anoxic or near-anoxic for the majority of the monitoring period. A numeric DO criteria set even slightly above 0% saturation would incorrectly classify these systems as impaired waters.

DO in violation of water quality standards is commonly attributed to nutrient impairment. Increased nutrient concentrations, as FD sites had

statistically higher levels of TP than minimally disturbed sites, did not account for lowered mean or daily minimum DO concentrations in this study. It is important to point out, however, that as wetlands inherently have a high capacity for nutrients, loading rates into FD sites may not have been high enough to have a significant effect on wetland water quality and ecosystem processes. FD sites, including MAFD1 and ALFD2 which showed significantly higher TP concentrations, did not display higher levels of daytime oxygen production in diel curves or significantly larger GPP in light-dark bottle experiments indicating that nutrient loading was most likely not significant enough to drive wetland eutrophication..

DO data alone may not be capable of detecting ecosystem impairment..

Low water column productivity and high sediment oxygen demand result in wetland DO concentrations frequently close to or at 0% saturation during daytime hours in both impacted and non-impacted systems. An excess respiratory oxygen demand resulting from a nutrient input may not be capable of driving DO levels lower than what is characteristic of natural conditions.

Increased respiratory rates in an impacted wetland could potentially dampen the physically-driven nighttime oxygen subsidy, as DO would presumably be consumed at a quicker rate. Increased floating aquatic plant density, another potential consequence of nutrient impairment, could also interfere with oxygen diffusion rates (Morris and Barker, 1977). Neither of these effects, however, were directly observed in this study as the magnitude of nighttime DO spikes was not significantly less in IF wetlands. More continuously

monitored DO data in isolated wetlands subject to nutrient impairment are needed.

Study Considerations and Caveats

Monitoring DO in wetlands over the course of 5-7 days during a single growing season, as was the case for this study, may have been insufficient to sufficiently characterize DO dynamics. Study wetlands yielded significantly lower mean DO than similar wetlands sampled in Wellendorf et al. (2012) (3.4 mg l-1) and Reiss (2005a) (2.9 and 1.8 mg l-1 for reference and disturbed wetlands).

Both studies monitored DO via morning grab sampling. Results from this study

(Figure 3-4), however, indicate that grab samples generally will not result in higher DO values as compared to continuous monitoring.

This disagreement may in fact speak to the validity of conclusions drawn from wetland DO data measured for only a single season. Isolated wetlands are ephemeral systems, with hydroperiods partially a function of climate. Wetlands may be subjected to extended dry periods, depending on the amount of rainfall which varies from season to season. Hydroperiod is known to effect aquatic plant colonization, abundance, community structure, and productivity (Bornette et al., 2007; Lacoul et al., 2006; Casanova and Brock, 2000) with long term water level history having a large effect on plant community response (Tabacchi, 1995).

As the presence and density of SAV was found to be a driver of DO in this study, wetland DO could vary considerably among seasons with differing climate regimes and hydrologic history. Data collection for this study followed drought conditions in which many of the sample wetlands were previously without

standing water for long periods of time. Low DO concentrations may be partially attributed to insufficient time for aquatic plants to recolonize.

This disagreement could also be partially attributed to different instrument- specific measurement protocols. Handheld membrane DO sensors, as are used for daytime grab samples, were shown during this study to be less accurate than optical DO sensors, having a higher rate of instrumentation verification failure.

Sensors were particularly inaccurate for measuring near-anoxic waters and frequently showed disagreement with optical DO probe measurements. Mixing of the stratified water column from the turbulence associated with grab sample measurement may have artificially inflated DO measurements.

It is important to note that much of the study analysis is partially confounded by the sample design in which the depth of measurement, which was shown to effect both DO concentration and nighttime DO flux, was not held constant from wetland to wetland even though mean sample depths and sensor orientation within the water column, however, were similar among FR, HR, and

FD sites. It is also important to point out that a wetland was deemed “impacted” or “minimally disturbed” based only on LDI values. While LDI has been shown to be correlated with wetland ecological condition, verification of impaired conditions via more intensive assessment techniques would give more credence to study results.

As mentioned previously, mean DO levels failed to show strong correlations with the measured water quality and soil parameters. While this could have been attributed to inadequate choice of parameters or testing correlations from DO data in which depth was not held constant, the lack of

strong relationships may be partially attributed to the frequent anoxic or near- anoxic conditions observed as relationships between environmental drivers and

DO may become increasingly non-linear as DO nears its lower measureable limit of 0 mg/l. For example, soil organic matter content may be negatively correlated with DO, but if DO levels are near 0 mg/l, increased soil %OM will not cause a measureable response in DO levels.

Conclusions

Isolated wetlands are naturally low-DO systems, with low DO being primarily driven by high soil respiratory demand and low primary productivity within the water column. Results from this study also indicate that increased nighttime rates of atmospheric re-aeration have a significant effect on diurnal DO patterns in these systems which, in combination with low water column productivity, can result in higher nighttime DO than what is observed during daytime hours. Wetland monitoring and data interpretation should take both the vertical DO stratification and peak nighttime DO concentrations into account.

Additional research is needed to quantify the effects of long-term hydrologic history on wetland DO as these parameters, not measured in this study, may influence the primary DO drivers documented.

DO levels alone may not be an effective metric to gauge and monitor an impairment in isolated wetlands as disturbed wetlands did not display significantly different DO than reference wetlands. Additionally, many reference wetlands showed near anoxic conditions over the monitoring period. DO dynamics inherent to these systems thus suggest that a numeric threshold-based water quality standard, as is the case for class III freshwaters in Florida, may not

be an appropriate approach to regulation, even with natural background conditions being taken into account.

Figure 3-1. Diel DO plots for two selected wetlands with shading to indicate nighttime and daytime hours. A) Diel DO plot for a forested site (LEDF2). B) Diel DO plot for a herbaceous wetland (SUHB1).

Figure 3-2. Mean DO of wetlands that showed a significant difference between daytime and nighttime oxygen levels.

A B

Figure 3-3. Diel DO plots for two wetlands. A) Diel DO plot for DIFB1. B) Diel DO plot for SAHD1.

Figure 3-4. Comparison of morning grab samples against continuous measurements for all wetlands with FR, HR, and FD sites positioned from left to right. Lines extending from weekly medians extend to the first and third quartiles.

A B

Figure 3-5. Examples of observed wetland nighttime DO spikes. A) Oxygen diffusion rate in the absence of biological activity overlaid with nighttime DO spike measured at LEFD1. B) Multiple nighttime DO spikes clustered together recorded at SUHB1.

Figure 3-6. Diel DO, water temperature, and air temperature plot measured at ALFD1.

A B

Figure 3-7. Relation of nighttime DO spikes and water temperature. A) Diel DO and temperature plots for SAHD2. Vertical dotted lines show water temperature crests coinciding with beginning of nighttime DO spikes. B) Daily DO range vs daily water temperature range for all wetlands.

A B

Figure 3-8. Seasonal comparison of diel DO plots for two wetlands measured during both summer and winter. All measurements were taken at approximately 20 cm depth at identical locations. A) Diel DO plots measured at ALHD1. B) Diel DO plots for ALFD1.

A B

Figure 3-9. Example diel DO and pH plots for two wetlands. A) Diel DO and pH plots measured at LEFD1. B) Diel DO and pH plots measured at SAHD1.

Figure 3-10. Ordination of sites based on water and soil parameters with Principal Components Analysis (PCA). LDI index score vectors are shown together at the 140m, 200m and 500m scales. Axis 2, not shown, explained 21.3% of the variance.

A B

Figure 3-11. Diel DO time series for a deep and shallow wetland study site. Sensor locations are given as the depth from water surface. A) Diel DO plot for COFD1 (deep). B) Diel DO plot measured at FLFD1 (shallow).

Figure 3-12. Mean daily DO saturation for individual wetlands. ALFD4, ALFD2, and FLFD1 are classified as shallow, the remaining seven classified as deep. Standard error bars are shown for each depth. Note that only two deep wetlands have measurements shown for all three depths due to probe malfunction or failure to meet verification requirements.

Figure 3-13. Comparison of mid-depth diel DO measurements, DOm, to average water column DO, DOwc for three wetlands. A) DO measurement comparison for COFD1. B) DO measurement comparison for MAFD1. C) DO measurement comparison for herbaceous marsh.

Table 3-1. DO summary statistics for wetland sites by type. “Min.” and ‘Max.” refer to the mean of the daily minimum and maximum DO. Standard deviations shown in parenthesis.

Sample Mean Min. Max. days (mg/L) (%) (mg/L) (%) (mg/L) (%) Statewide 243 1.0 (1.1) 11.6 (13.5) 0.4 (0.5) 4.3 (6.4) 2.1 (0.5) 25.1 (13.5) North 133 0.9 (0.9) 9.8 (10.3) 0.3 (0.5) 3.8 (5.6) 1.9 (1.4) 22.5 (16.5) Central 110 1.1 (1.3) 13.3 (16.7) 0.4 (0.6) 4.8 (7.3) 2.2 (2.2) 27.1 (29.8) FR 103 1.0 (1.1) 11.1 (12.6) 0.4 (0.7) 4.2 (6.8) 1.9 (1.5) 22.0 (18.7) HR 72 1.2 (1.4) 14.5 (18.4) 0.4 (0.6) 4.6 (7.4) 2.6 (2.6) 32.8 (34.6) FD 68 0.8 (0.7) 8.8 (8.9) 0.3 (0.4) 3.9 (5.2) 1.8 (1.1) 20.3 (13.4) FR - North 62 0.9 (1.0) 10.3 (10.6) 0.4 (0.6) 3.9 (6.5) 1.9 (1.3) 22.4 (15.3) FR – Central 41 1.0 (1.3) 12.1 (15.8) 0.4 (0.6) 4.6 (7.5) 1.9 (1.9) 21.4 (23.7) HR – North 22 0.7 (1.0) 7.5 (11.3) 0.1 (0.1) 1.5 (1.5) 1.8 (2.2) 20.8 (25.0) HR – Central 50 1.4 (1.6) 17.4 (20.2) 0.5 (0.7) 6.3 (8.4) 2.8 (2.8) 36.8 (38.7) FD – North 49 0.9 (0.9) 10.1 (10.3) 0.4 (0.4) 4.8 (5.8) 2.0 (1.3) 23.3 (15.3) FD - Central 19 0.5 (0.3) 5.2 (3.9) 0.2 (0.1) 1.7 (1.2) 1.2 (0.9) 13.6 (10.5)

Table 3-2. Timing of DO maximums and minimums Type Mean timing of DO maximum Mean timing of DO minimum (hours after sunset) (hours after sunrise) FR 4.5 ± 3.9 6.8 ± 3.9 HR 2.5 ± 3.0 1.2 ± 2.9 FD 6.4 ± 3.1 4.2 ± 3.9

Table 3-3. Seasonal comparison of mean water quality parameters for ALHD1. Standard deviations are shown in parenthesis DO DO Temp. Sp. Cond. pH Vegetative (mg/l) (% sat) (°C) (µs/cm) cover July ‘12 0.09 (0.06) 1.1 (0.8) 26.4 (0.2) 52 (1) 4.2 (0.1) 35% Jan ‘13 0.32 (0.2) 3.1 (1.9) 14.1 (0.2) 65 (2) 5.5 (0.4) 80%

Table 3-4. Seasonal comparison of mean water quality parameters for ALFD1. Standard deviation shown in parenthesis. DO DO Temp. Sp. Cond. pH Canopy (mg/l) (% sat) (°C) (µs/cm) cover Set ‘12 0.44 (0.60) 5.1 (7.0) 23.0 (0.3) 85 (1) 4.0 (0.0) 86% Feb/Mar ‘13 2.2 (0.81) 20.8 (7.1) 13.2 (1.3) 70 (4) 4.1 (0.1) 71%

Table 3-5. Water quality by wetland type. Standard deviation shown in parenthesis Water temp. Sp. cond. Turbidity Color TOC Type (°C) pH (ms/cm) (NTU) (PCU) (mg-C/l) State 22.3 (3.8) 4.6 (1.2) 0.11 (0.07) 2.4 (1.8) 550 (317) 51.3 (25.3) FR 22.2 (4.1) 4.1 (1.0) 0.11 (0.08) 1.5 (0.5) 760 (360) 64.9 (26.4) HR 24.2 (3.4) 4.4 (0.9) 0.08 (0.04) 2.9 (2.0) 567 (217) 52.7 (21.7) FD 20.4 (3.1) 5.8 (1.2) 0.14 (0.08) 2.9 (2.3) 285 (104) 33.7 (17.6)

Table 3-5. Continued TP TN TKN NH3 Chl-a Type (mg-P/l) (mg-N/l) (mg-N/l) (mg-N/l) (µg/l) State 0.19 (0.41) 1.9 (1.2) 1.9 (1.2) 0.04 (0.04) 18.4 (31.0) FR 0.03 (0.02) 1.6 (0.4) 1.6 (0.4) 0.05 (0.04) 3.5 (7.1) HR 0.12 (0.14) 2.6 (1.9) 2.6 (1.9) 0.04 (0.05) 38.3 (45.5) FD 0.44 (0.68) 1.5 (0.6) 1.5 (0.6) 0.02 (0.02) 14.3 (15.7)

Table 3-6. Mean daily range of pH and specific conductance for FR, HR, and FD wetlands. Standard deviation shown in parenthesis. Wetland pH Sp. conductance Type (units day-1) (ms cm-1 day-1) FR 0.2 (0.1) 0.014 (0.028) HR 0.3 (0.2) 0.008 (0.006) FD 0.2 (0.3) 0.011 (0.008)

Table 3-7. Soil parameters by depth class and wetland type. Standard deviation is shown in parenthesis. State FR HR FD %OM 0-5 cm 44 (26) 47 (25) 45 (28) 40 (26) 5-10 cm 35 (29) 34 (30) 43 (33) 29 (24) 10-15 cm 32 (29) 33 (31) 40 (33) 20 (19) RI 0-5 cm 20 (8) 23 (9) 22 (6) 16 (5) 5-10 cm 25 (9) 29 (10) 23 (8) 22 (6) 10-15 cm 25 (8) 28 (7) 25 (5) 22 (13)

Table 3-8. Correlation of water quality and soil parameters for all wetlands. Values represent Pearson r.

itrogen

Water temperature pH Specific conductance Chlorophyll Phaeophytin Turbidity Color OrganicTotal Carbon Total Phosphorus Total Nitrogen Total Kjeldahl N Ammonia OM% Soil RI

DO %Saturation 0.37 0.11 0.06 0.05 0.18 -0.24 -0.21 -0.30 -0.13 0.00 0.00 -0.23 -0.39 -0.11 Water temperature -0.14 -0.55 -0.20 -0.11 -0.26 0.21 -0.02 -0.15 -0.12 -0.12 -0.03 -0.22 0.12 pH 0.44 0.00 -0.19 0.08 -0.59 -0.65 0.19 -0.24 -0.24 -0.12 -0.20 -0.47 Specific conductance -0.12 -0.14 0.00 -0.35 -0.26 -0.01 -0.19 -0.19 -0.09 0.06 -0.18 Chlorophyll-a 0.75 0.31 -0.20 -0.14 0.17 0.49 0.49 -0.08 -0.05 0.10 Phaeophytin-a 0.27 0.00 0.09 0.09 0.83 0.83 -0.07 -0.16 0.21 Turbidity -0.17 0.07 0.19 0.39 0.39 -0.16 0.33 -0.13 Color 0.90 -0.21 0.21 0.21 0.33 0.02 0.22 Total Organic Carbon -0.21 0.31 0.30 0.27 0.19 0.27 Total Phosphorus 0.23 0.23 -0.08 -0.29 -0.07 Total Nitrogen 1.00 0.07 -0.10 0.17 Total Kjeldahl Nitrogen 0.07 -0.10 0.18 Ammonia-N 0.37 0.19 % Soil OM 0.14

Table 3-9. Timing and magnitudes of minimum and maximum DO stratification. Standard deviation shown in parenthesis. Deep (upper) referrers to the upper half of the water column for deep wetlands. Deep (full) refers to the entire water column for deep wetlands in which three sondes were deployed. Time of max DO Magnitude of Time of min DO Magnitude of stratification max. DO stratification min. DO N (hours after stratification (hours before stratification, Depth class (days) sunset) (mg/l/cm) sunrise) (mg/l/cm) Shallow 18 5.1 (3.1) 0.15 (0.08) 1.0 (6.8) 0.00 (0.00) Deep (upper) 29 5.5 (4.0) 0.13 (0.06) 1.3 (7.6) 0.01 (0.01) Deep (full) 21 3.4 (3.4) 0.10 (0.04) -1.5 (5.8) 0.01 (0.01)

APPENDIX A INDIVIDUAL DIEL PLOTS BY WETLAND

Diel DO plots for FR wetlands

Diel DO plots for HR wetlands

Diel DO plots for FD wetlands

APPENDIX B PAIRWISE LINEAR CORRELATION TABLES

Table B-1. Correlation of water quality and soil parameters for FR sites. Values represent Pearson r.

ve Cover

Water temperature pH Specific conductance Chlorophyll Phaeophytin Turbidity Color OrganicTotal Carbon Total Phosphorus Total Nitrogen Total Kjeldahl Nitrogen Ammonia OM% Soil RI Vegetati

DO %Saturation 0.15 0.50 0.66 0.30 0.93 0.51 -0.36 -0.38 -0.30 -0.34 -0.34 -0.38 -0.50 -0.31 -0.51 Water temperature -0.08 -0.54 -0.21 0.23 0.49 -0.08 -0.16 0.36 -0.18 -0.18 -0.02 -0.25 0.00 -0.55 pH 0.63 -0.17 0.18 0.29 -0.22 -0.29 0.09 0.00 0.00 -0.22 -0.68 -0.29 0.13 Specific conductance -0.47 -0.59 0.01 0.43 0.44 0.03 0.21 0.21 0.41 0.12 0.40 0.68 Chlorophyll-a 0.38 0.14 -0.43 -0.45 -0.13 -0.52 -0.51 -0.28 0.30 -0.08 -0.51 Phaeophytin-a 0.42 -0.36 -0.40 -0.21 -0.38 -0.38 -0.31 -0.39 -0.17 -0.53 Turbidity -0.30 -0.25 -0.06 -0.23 -0.22 -0.45 -0.30 0.17 -0.25 Color 0.95 0.27 0.73 0.72 0.33 -0.10 -0.16 0.31 Total Organic Carbon 0.12 0.81 0.80 0.23 -0.06 -0.07 0.45 Total Phosphorus 0.33 0.33 0.21 -0.30 -0.17 -0.44 Total Nitrogen 1.00 0.20 -0.30 -0.09 0.34 Total Kjeldahl Nitrogen 0.19 -0.30 -0.09 0.34 Ammonia-N 0.55 0.49 0.09 % Soil OM 0.65 0.11 Lability index 0.11

Table B-2. Correlation of water quality and soil parameters for HR sites. Values represent Pearson r.

nia

Water temperature pH Specific conductance Chlorophyll Phaeophytin Turbidity Color OrganicTotal Carbon Total Phosphorus Total Nitrogen Total Kjeldahl Nitrogen Ammo OM% Soil RI Vegetative Cover

DO %Saturation 0.57 -0.20 -0.19 0.02 0.12 -0.41 -0.37 -0.45 -0.15 0.01 0.01 -0.42 -0.55 -0.05 -0.05 Water temperature 0.02 -0.37 -0.44 -0.43 -0.25 -0.23 -0.50 -0.24 -0.34 -0.34 -0.63 -0.25 -0.31 -0.23 pH 0.40 -0.05 -0.34 0.09 -0.34 -0.50 -0.22 -0.19 -0.19 0.37 0.18 -0.63 -0.53 Specific conductance -0.31 -0.19 -0.07 -0.22 -0.03 -0.27 -0.14 -0.14 0.44 0.41 -0.18 -0.12 Chlorophyll-a 0.73 0.23 -0.32 -0.11 0.51 0.43 0.43 -0.01 -0.17 0.30 -0.01 Phaeophytin-a 0.32 0.03 0.22 0.81 0.87 0.86 -0.16 -0.30 0.50 0.25 Turbidity 0.07 0.32 0.69 0.47 0.47 0.22 0.55 -0.33 0.04 Color 0.85 0.06 0.17 0.17 0.14 -0.08 0.33 0.65 Total Organic Carbon 0.25 0.28 0.28 0.24 0.18 0.42 0.76 Total Phosphorus 0.82 0.82 -0.27 -0.04 0.25 0.18 Total Nitrogen 1.00 0.02 -0.17 0.28 0.13 Total Kjeldahl Nitrogen 0.02 -0.17 0.28 0.13 Ammonia-N 0.52 -0.38 -0.16 % Soil OM -0.47 -0.30 RI 0.61

Table B-3. Correlation of water quality and soil parameters for FD sites. Values represent Pearson r.

trogen

Water temperature pH Specific conductance Chlorophyll Phaeophytin Turbidity Color OrganicTotal Carbon Total Phosphorus Total Nitrogen Total Kjeldahl Ni Ammonia OM% Soil RI Vegetative Cover

DO %Saturation 0.52 0.38 -0.50 -0.50 -0.07 -0.49 -0.15 -0.26 -0.24 -0.37 -0.37 0.78 -0.02 -0.18 0.04 Water temperature 0.43 -0.53 -0.20 -0.01 -0.28 -0.33 -0.59 0.26 -0.28 -0.28 0.46 -0.52 -0.10 0.46 pH 0.09 0.10 -0.38 -0.41 -0.78 -0.80 -0.21 -0.78 -0.78 0.03 -0.12 -0.10 0.21 Specific conductance -0.03 -0.11 -0.18 -0.41 -0.11 -0.30 -0.29 -0.29 -0.38 0.07 0.05 -0.66 Chlorophyll-a 0.20 0.31 0.17 -0.04 0.38 0.20 0.20 -0.53 0.05 -0.01 0.47 Phaeophytin-a -0.05 0.36 0.12 -0.09 0.03 0.03 -0.06 -0.20 -0.40 -0.05 Turbidity 0.27 0.61 0.00 0.45 0.44 -0.61 0.47 0.11 0.37 Color 0.75 0.29 0.82 0.82 0.07 0.17 0.13 -0.01 Total Organic Carbon -0.07 0.74 0.73 -0.19 0.51 0.11 -0.26 Total Phosphorus 0.61 0.62 0.21 -0.49 0.24 0.37 Total Nitrogen 1.00 0.01 0.04 0.34 0.04 Total Kjeldahl Nitrogen 0.02 0.04 0.34 0.04 Ammonia-N -0.28 0.05 -0.07 % Soil OM -0.29 0.02 RI -0.06

APPENDIX C DIEL PLOTS AT MULTIPLE DEPTHS

Diel DO plots for shallow wetlands

Diel DO plots for deep wetlands

APPENDIX D GENERAL SITE INFORMATION FOR ALL WETLANDS

Table D-1. Site details for all wetlands Site County Region Latitude Longitude Type Sample Dates LDI 140m LDI 200m LDI 500m ALFD1 Alachua North 29.66095 -82.27519 FR 9/12 - 9/18/2012 0.0 0.0 7.6 CLFD1 Clay North 29.948889 -81.6325 FR 6/20 - 6/23/2012 0.0 0.0 0.3 CLFD2 Clay North 30.0167 -82.0184 FR 7/3 - 7/10/2012 0.0 0.0 0.0 CLFD3 Clay North 30.03196 -81.98682 FR 7/3 - 7/10/2012 0.0 0.6 0.6 CLFD4 Clay North 30.1358 -81.9679 FR 8/7 - 8/14/2012 0.0 0.0 0.0 CLFD5 Clay North 30.13363 -81.9786 FR 8/7 - 8/14/2012 0.0 0.8 0.5 LAFD1 Lake Central 29.1181 -81.5738 FR 9/21 - 9/27/2012 0.0 0.0 0.0 LAFD2 Lake Central 29.12833 -81.59122 FR 9/21 - 9/27/2012 0.5 0.5 0.4 LEFD1 Levy North 29.2049 -82.63078 FR 8/30 - 9/6/2012 0.0 0.7 0.8 LEFD2 Levy North 29.13109 -82.62289 FR 8/30 - 9/6/2012 0.0 0.0 0.3 SUFD1 Sumter Central 28.3945 -81.9709 FR 8/16 - 8/23/2012 0.0 0.0 0.2 SUFD2 Sumter Central 28.46295 -82.01923 FR 9/11 - 9/18/2012 0.0 0.0 0.0 BAFB1 Baker North 30.28802 -82.36384 FR 10/9 - 10/16/2012 0.0 0.0 0.0 DIFB1 Dixie North 29.44516 -83.18278 FR 10/12 - 10/19/2011 0.2 0.2 0.4 DUFB1 Duval North 30.485668 -81.80458 FR 10/24 - 10/31/2011 0.0 0.0 0.1 VOFB1 Volusia Central 29.08537 -81.17609 FR 11/9 - 11/16/2011 0.3 0.3 0.7 VOFB2 Volusia Central 29.12142 -81.16559 FR 11/9 - 11/16/2011 0.0 0.0 17.9 VOFB3 Volusia Central 29.10567 -81.16894 FR 11/9 - 11/16/2011 0.1 0.2 0.2 ALHD1 Alachua North 29.60208 -82.27556 HR 7/3 - 7/10/2012 0.0 0.1 0.2 BAHD1 Baker North 30.396 -82.4385 HR 10/9 - 10/16/2012 0.0 0.0 0.4 BAHD2 Baker North 30.3132 -82.4215 HR 10/9 - 10/16/2012 0.0 0.8 0.4 CLHD1 Clay North 29.961111 -81.615 HR 6/20 - 6/23/2012 0.6 0.7 0.3 HEHD1 Hernando Central 28.50809 -82.09089 HR 10/23 - 10/30/2012 0.0 0.9 0.8 HEHD2 Hernando Central 28.52984 -82.12621 HR 10/23 - 10/30/2012 0.0 0.3 0.3 LAHD1 Lake Central 29.12539 -81.59081 HR 9/21 - 9/27/2012 0.2 0.5 0.4 SAHD1 Sarasota Central 27.18784 -82.27556 HR 7/11 - 7/18/2012 0.5 0.7 0.7 SAHD2 Sarasota Central 27.27166 -82.25654 HR 7/11 - 7/18/2012 0.4 1.3 6.5

Table D-1. Continued Site County Region Latitude Longitude Type Sample Dates LDI 140m LDI 200m LDI 500m SAHD3 Sarasota Central 27.23684 -82.33043 HR 7/11 - 7/18/2012 0.7 1.1 1.2 SUHD1 Sumter Central 28.3545 -82.0175 HR 8/16 - 8/23/2012 0.9 0.5 0.2 SUHB1 Sumter Central 28.4882 -82.02304 HR 10/23 - 10/30/2012 0.0 0.0 0.0 ALFD2 Alachua North 29.74675 -82.26424 FD 5/16 - 5/23/2013 3.2 16.8 25.0 ALFD3 Alachua North 29.751181 -82.27348 FD 11/6 - 11/13/2013 4.4 7.2 12.6 ALFD4 Alachua North 29.799678 -82.414529 FD 4/18 - 4/25/2013 14.1 14.3 12.4 COFD1 Columbia North 30.210028 -82.648085 FD 5/9 - 5/16/2013 35.9 35.9 34.8 DUFD1 Duval North 30.20305 -81.7635 FD 4/12 - 4/18/2013 29.2 28.2 25.8 CIFD1 Citrus North 28.738819 -82.540361 FD 8/28 - 9/4/2013 28.8 30.7 32.3 SJFD1 St. Johns North 30.111157 -81.624297 FD 10/13 - 10/20/2013 24.1 24.2 30.8 FLFD1 Flagler Central 29.476221 -81.267544 FD 9/9 - 9/16/2013 29.2 28.8 29.9 MAFD1 Marion North 29.333565 -82.304072 FD 9/24 - 10/1/2013 2.7 3.5 3.2 HIFD1 Hillsborough Central 28.107331 -82.383927 FD 11/17 - 11/24/2013 34.2 35.3 32.0 PAFD1 Pasco Central 28.173126 -82.351274 FD 11/24 - 12/2/2013 2.4 23.7 36.2

APPENDIX E MEASURED ENVIRONMENTAL PARAMETERS BY SITE

Table E-1. Water quality data by site for FR wetlands. Continuously monitored parameters include temperature, specific conductance, and pH and are given as mean values computed over the sampling period with standard deviation shown in parenthesis. Temperature, pH, and specific conductance values without standard deviation values indicate sonde sensor failure in which case a single grab sample value was used. Mean temp Mean sp. Chl-a Phaeophytin-a Turbidity Color TOC TP TN TKN NO2-NO3-N Ammonia-N Site name (°C) cond. (ms/cm) Mean pH (µg/l) (µg/l) (NTU) (PCU) (mg-C/l) (mg-P/l) (mg-N/l) (mg-N/l) (mg N/l) (mg-N/l) CLFD2 28.0 (0.7) 0.045 (0.003) 3.8 0.55 0.62 1.4 530 43 0.055 1.5 1.5 0.004 0.023 CLFD3 25.7 (1.1) 0.091 3.3 2.2 0.5 2.4 1003 92 0.048 2.0 2 0.004 0.04 CLFD4 24.7 (0.7) 0.073 (0.012) 3.5 (0.06) 0.55 0.4 1.1 440 51 0.023 1.4 1.4 0.008 0.05 CLFD5 24.8 (0.6) 0.067 (0.004) 3.3 (0.04) 0.55 0.4 1.1 1100 91 0.03 2.1 2.1 0.024 0.15 LEFD1 25.1 (0.5) 0.074 (0.002) 3.6 (0.03) 0.62 0.45 1.8 1003 88 0.021 1.6 1.6 0.02 0.021 LEFD2 25.6 (0.4) 0.054 (0.003) 3.8 (0.06) 0.55 0.4 1.8 860 66 0.023 1.4 1.4 0.02 0.03 SUFD2 24.1 (0.5) 0.067 (0.003) 5.9 (0.07) 1.5 0.59 2.3 410 43 0.026 1.6 1.6 0.004 0.013 ALFD1 23.0 (0.3) 0.084 (0.002) 4.0 (0.05) 0.77 0.4 0.85 1600 120 0.038 2.1 2.1 0.02 0.043 LAFD1 23.5 (0.4) 0.093 (0.002) 3.5 (0.06) 0.55 0.4 1.3 590 53 0.007 1.0 1 0.004 0.085 LAFD2 22.4 (0.8) 0.044 (0.004) 3.3 25 0.67 1.4 370 35 0.028 1.0 1 0.004 0.025 BAFB1 20.0 (0.8) 0.084 4.0 1.2 0.4 0.85 740 75 0.021 2.1 2.1 0.004 0.021 SUFD1 25.7 (1.0) - 4.3 (0.03) 11 4.1 2.2 390 34 0.019 1.1 1.1 0.004 0.01 CLFD1 24.1 (0.5) 0.089 (0.002) 4.6 (0.10) 0.55 0.4 1.1 850 53 0.06 1.5 1.5 0.004 0.12 DIFB1 20.4 (2.1) 0.345 (0.154) 6.9 (0.30) ------DUFB1 16.3 (1.2) 0.190 (0.009) 4.7 (0.06) ------VOFB1 16.9 (2.5) 0.146 (0.004) 3.0 (0.20) ------VOFB2 14.0 (1.5) 0.143 (0.002) ------VOFB3 15.8 (1.1) 0.152 (0.003) 3.5 (0.05) ------

Table E-2. Water quality data by site for HR wetlands. See Table E-1 for and explanation of data presented in this table. Mean sp. Mean temp conductance Chl-a Phaeophytin-a Turbidity Color TOC TP TN TKN NO2-NO3-N Ammonia-N Site name (°C) (ms/cm) Mean pH (µg/l) (µg/l) (NTU) (PCU) (mg-C/l) (mg-P/l) (mg-N/l) (mg-N/l) (mg N/l) (mg-N/l) ALHD1 26.4 (0.7) 0.052 (0.001) 4.2 (0.1) 41 14 7.9 580 64 0.34 3.1 3.1 0.004 0.009 SAHD1 29.0 (2.0) 0.073 (0.002) 4.6 (0.1) 33 4.9 1.4 400 38 0.017 2.1 2.1 0.004 0.015 SAHD3 28.9 (1.8) 0.059 (0.003) 5.3 5.4 1.5 1.6 680 37 0.028 1.5 1.5 0.004 0.016 SAHD2 26.0 (0.5) 0.060 (0.011) 4.9 (0.15) 3.3 0.4 1.9 650 40 0.097 2.7 2.7 0.004 0.035 SUHD1 27.5 (1.5) - 3.4 36 7 1 230 24 0.008 1.0 0.96 0.004 0.010 LAHD1 24.5 (0.6) 0.078 (0.002) 3.4 (0.4) 11 4.4 1.1 690 59 0.048 1.5 1.5 0.004 0.021 BAHD1 21.3 (1.1) 0.067 (0.002) 3.6 (0.13) 110 62 4.2 580 61 0.46 8.1 8.1 0.004 0.011 BAHD2 20.5 (0.9) 0.099 (0.001) 3.3 (0.07) 26 15 1.7 980 99 0.074 1.8 1.8 0.02 0.04 SUHB1 20.6 (1.5) 0.079 (0.002) 4.3 (0.06) 24 7.8 4.7 810 80 0.052 3.7 3.7 0.004 0.17 HEHD1 20.3 (1.0) 0.043 (0.003) 5.0 (0.22) 150 21 2.9 340 35 0.13 1.8 1.8 0.004 0.067 HEHD2 20.7 (1.2) 0.206 (0.007) 6.0 17 3.4 3.4 320 37 0.055 2.0 2 0.004 0.11 CLHD1 24.9 (0.7) 0.077 (0.002) 4.2 (0.05) 3.2 1 2.9 540 58 0.13 1.8 1.8 0.004 0.025

Table E-3. Water quality data by site for FD wetlands. See Table E-1 for and explanation of data presented in this table. Mean sp. Mean temp conductance Chl-a Phaeophytin-a Turbidity Color TOC TP TN TKN NO2-NO3-N Ammonia-N Site name (°C) (ms/cm) Mean pH (µg/l) (µg/l) (NTU) (PCU) (mg-C/l) (mg-P/l) (mg-N/l) (mg-N/l) (mg N/l) (mg-N/l) ALFD2 21.6 (1.2) 0.107 (0.014) 4.3 0.55 0.6 1.4 400 39 1.8 2.6 2.6 0.004 0.063 ALFD3 16.3 (0.6) 0.124 (0.011) 3.8 (0.04) 7.4 1.5 8.3 390 78 0.059 2.4 2.4 0.04 0.004 ALFD4 17.1 (2.7) 0.150 (0.005) 3.8 32 1.3 3.1 260 25 0.75 1.4 1.4 0.004 0.005 COFD1 18.8 (0.8) 0.163 (0.005) 6.1 31 1 4.6 300 32 0.1 1.4 1.4 0.004 0.005 DUFD1 20.3 (1.1) 0.075 (0.001) 5.8 5.7 2.1 0.85 350 37 0.056 1.5 1.5 0.004 0.058 CIFD1 25.1 (0.6) 0.041 (0.003) 7.3 (0.8) 0.55 0.4 1.0 180 17 0.22 0.8 0.8 0.012 0.065 SJFD1 21.1 (0.8) 0.133 (0.001) 4.8 (0.04) 14 5.5 1.6 360 34 0.051 1.3 1.3 0.004 0.021 FLFD1 24.3 (0.7) 0.078 (0.010) 6.5 (0.10) 1.2 0.4 4.2 210 23 0.08 1.1 1.1 0.004 0.004 MAFD1 23.2 (0.6) 0.075 (0.001) 6.2 (0.06) 47 2 4.5 310 29 1.7 2.1 2.1 0.020 0.008 HIFD1 20.2 (0.5) 0.330 (0.008) 6.7 (.06) 3 0.8 1.2 54 12 0.052 0.7 0.65 0.012 0.019 PAFD1 16.3 (2.0) 0.240 (0.002) 6.1 (0.09) 15 0.4 1.2 330 45 0.028 1.6 1.6 0.004 0.007

Table E-4. Canopy cover, SAV presence, GPP, and R by site for FR wetlands. SAV does not include floating plants. Note that many GPP is zero for many sites. A subset of sites displayed slightly negative GPP values which were taken to be zero.

GPP R Site Canopy cover SAV presence (mg O2 l ˉ¹ hrˉ¹) (mg O2 l ˉ¹ hrˉ¹) CLFD2 75% Rare - - CLFD3 83% Rare - - CLFD4 87% Absent 0.000 0.013 CLFD5 81% Absent 0.038 0.038 LEFD1 87% Absent 0.000 0.042 LEFD2 82% Absent - - SUFD2 86% Absent 0.009 0.052 ALFD1 86% Absent 0.000 0.074 LAFD1 87% Absent - - LAFD2 78% Rare - - BAFB1 88% Absent 0.005 0.051 SUFD1 76% Abundant - - CLFD1 - Rare - -

Table E-5. Canopy cover, SAV presence, GPP, and R by site for HR wetlands. Refer to Table E-4 for an explanation of data presented in this table.

Vegetative GPP R Site cover SAV presence (mg O2 l ˉ¹ hrˉ¹) (mg O2 l ˉ¹ hrˉ¹) ALHD1 35% Absent 0.000 0.014 SAHD1 25% Common - - SAHD3 20% Absent - - SAHD2 23% Absent - - SUHD1 20% Common - - LAHD1 12% Absent - - BAHD1 35% Common 0.000 0.074 BAHD2 90% Common - - SUHB1 25% Common 0.011 0.055 HEHD1 15% Rare 0.041 0.050 HEHD2 5% Common 0.033 0.045 CLHD1 25% Abundant - -

Table E-6. Canopy cover, SAV presence, GPP, and R by site for FD wetlands. Refer to Table E-4 for an explanation of data presented in this table. GPP R Site Canopy cover SAV presence (mg O2 l ˉ¹ hrˉ¹) (mg O2 l ˉ¹ hrˉ¹) ALFD2 87% Absent 0.013 0.153 ALFD3 86% Absent 0.000 0.030 ALFD4 89% Rare 0.000 0.096 COFD1 90% Absent 0.048 0.128 DUFD1 85% Rare 0.000 0.044 CIFD1 89% Absent - - SJFD1 86% Absent 0.000 0.064 FLFD1 89% Absent 0.000 0.074 MAFD1 90% Absent 0.042 0.142 HIFD1 84% Absent 0.000 0.023 PAFD1 82% Rare 0.027 0.038

Table E-7. Soil data for FR wetlands by site. Soil %OM Soil RI 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm ALFD1 0.22 0.12 0.11 0.07 0.14 0.20 BAFB1 0.39 0.18 0.32 0.23 0.30 0.30 CLFD2 0.30 0.12 0.10 0.21 0.31 0.29 CLFD3 0.51 0.31 0.30 0.35 0.42 0.35 CLFD4 0.53 0.38 0.37 0.17 0.31 0.31 CLFD5 0.69 0.72 0.68 0.32 0.22 0.15 LAFD1 0.91 0.91 0.94 0.42 0.47 0.35 LAFD2 0.86 0.79 0.82 0.22 0.29 0.25 LEFD1 0.50 0.13 0.09 0.24 - 0.26 LEFD2 0.36 0.27 0.11 0.14 0.17 0.20 SUFD1 0.15 0.07 0.06 0.18 0.26 0.29 SUFD2 0.16 0.08 0.05 0.22 0.28 0.38

Table E-8. Soil data for HR wetlands by site. Soil %OM Soil RI 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm ALHD1 0.86 0.83 0.82 0.17 0.18 0.25 BAHD1 0.13 0.12 0.09 0.29 0.18 0.28 BAHD2 0.26 0.22 0.21 0.32 0.43 0.31 HEHD1 0.42 0.62 0.53 0.23 0.26 0.30 HEHD2 0.84 0.81 0.78 0.16 0.16 0.16 LAHD1 0.69 0.49 0.37 0.26 0.31 0.34 SAHD1 0.37 0.45 0.40 0.23 0.16 0.22 SAHD2 0.19 0.06 0.06 0.23 0.25 0.23 SAHD3 0.15 0.06 0.06 0.15 0.25 0.24 SUHB1 0.78 0.94 0.93 0.16 0.16 0.20 SUHD1 0.30 0.13 0.10 0.20 0.24 0.25

Table E-9. Soil data for FD wetlands by site. Soil %OM Soil RI 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm ALFD2 0.14 0.14 - 0.21 0.19 - ALFD3 0.83 0.66 - 0.16 0.19 - ALFD4 0.41 0.51 0.57 0.14 0.14 0.13 CIFD1 0.59 0.67 0.28 0.08 0.15 0.08 COFD1 0.79 - - 0.19 - - DUFD1 0.22 0.19 - 0.24 0.26 - FLFD1 0.22 0.03 0.02 0.19 0.22 0.31 HIFD1 0.19 0.16 0.17 0.18 0.2 0.16 MAFD1 0.12 0.02 0.03 0.18 0.33 0.46 PAFD1 0.61 0.33 0.2 0.15 0.23 0.15 SJFD1 0.29 0.14 0.16 0.07 0.3 0.22

APPENDIX F FIELD PHYSICAL/CHEMICAL SITE CHARACTERIZATION SHEET

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BIOGRAPHICAL SKETCH

Robert Compton received his Bachelor of Science in environmental engineering sciences from University of Florida in 2011. He earned a Master of Engineering in environmental engineering sciences from University of Florida in 2014. Robert’s research focuses on wetland science, water quality, and environmental regulations. As a graduate student, Robert taught four semesters of Environmental Biology Lab through

UF’s Engineering School of Sustainable Infrastructure & Environment and participated in wetland data collection efforts for the USEPA and FDEP. Robert holds an

Engineering Intern license in the State of Florida.