Abstracts

Photoprotective Benefits of CDOM in Inshore Environments

Lore Ayoub, Paula Coble and Pamela Hallock-Muller

University of South Florida, College of Marine Science

140 7th Ave S

St Petersburg, FL 33704

(727) 553-1615

layoub@marine.usf.edu

CDOM high absorptivity in the UV range (280 - 400) and low blue wavelengths protects benthic organisms from DNA damage, photo-oxidative stress, and lower immune and reproductive health. While seagrasses produce CDOM, CDOM can block photosynthetically available radiation (PAR) that is needed for photosynthesis. Supraoptimal levels of PAR can also cause photoinhibition. While other studies have shown that shade and habitat complexity attract juvenile reef fish to mangroves, coastal wetlands, mangroves, and seagrasses are important sources of CDOM for inshore coral reefs. In recent years, offshore reefs in the Florida Keys National Marine Sanctuary have not recovered from declines in coral cover, while coral cover at inshore reefs has increased after an initial decline. Offshore reefs have higher rates of coral bleaching than inshore reefs. An onshore - offshore transect of CDOM absorption shows that CDOM absorption decreases going from a seagrass bed within John Pennekamp Park, to inshore reefs, to blue offshore waters. Our recent comparisons of inshore reefs adjacent to intact shoreline which receive high CDOM water from adjacent wetlands with the daily tides (Algae Reef, near John Pennekamp Park) versus inshore reefs near developed shoreline (Three Sisters Reef, near Key Largo) show that inshore reefs near intact shorelines recover more quickly from stressors such as lesions, anthropogenic runoff and environmental stresses. Also, populations of benthic foraminifera are greater at reefs near intact shorelines. Previous studies of middle and lower Florida Keys reefs have shown that bleaching of foraminifera is less prevalent at reefs that receive daily tidally flushed CDOM from Florida Bay.

Management practices for CDOM in seagrass beds could include monitoring distribution of CDOM-rich water out of the seagrass bed areas to areas that will eventually flow over coastal environments, such as coral reefs, that benefit from the photoprotective effects of CDOM. Methods for monitoring CDOM can include in lab and in situ absorption spectroscopy and fluorometry. Above water reflectance measurements over seagrass beds can be used to monitor the quality of light and productivity of the seagrass beds. These tools can be applied to monthly monitoring protocols from the source water regions to the seagrass beds and further offshore. Intact shorelines are intrinsic to healthy seagrass beds, by providing CDOM as a UV photoprotection and leaching out excessive nutrients. Holistic management practices can be used to maintain and foster healthy seagrass productivity, balancing PAR penetration and UV protection.

Tools for observation of synoptic distribution of CDOM—Satellite Images, a case study in Tampa Bay estuary

Zhiqiang Chen, Frank Muller-Karger, and Chuanmin Hu

140 7^th Avenue South

College of Marine Science, University of South Florida

Saint Petersburg, FL 33701

Understanding the magnitude and variability of colored dissolved organic matter (CDOM, or traditionally monitored as color) is increasingly recognized as useful for coastal and estuarine managements. However, CDOM is not a frequently monitored parameter for most estuaries. In this presentation, we explore the potential for monitoring CDOM in estuaries by satellite imaging, namely the Moderate Resolution Imaging Spectroradiometer Sensor (MODIS), using Tampa Bay as a case study. Results show that ratios of remote sensing reflectance (Rrs) between 488nm (Rrs(488)) and 551 nm (Rrs(551)) from MODIS/Aqua were strongly correlated with in situ color measurements obtained from the Environmental Protection Commission of Hillsborough County's Tampa Bay water quality monitoring program (color = 30.517×e^{-2.931*(Rrs(488)/Rrs(551)}, R² = 0.40, n=68). The relationship was applicable to the Middle and Lower Tampa Bay over all the seasons, and was thus applied to all the MODIS images collected from June 2002 to December 2006. The images clearly show the seasonal variability in CDOM, which is related to river discharge. The feasibility of extending the method to the Charlotte Harbor estuary to monitor CDOM or color was also tested and some preliminary results will be described.

Causes of Light Attenuation with Respect to Seagrasses in Upper and Lower Charlotte Harbor

L. Kellie Dixon^1*, Gary J. Kirkpatrick¹, and Emily R. Hall¹

¹ Mote Marine Laboratory

1600 Ken Thompson Parkway

Sarasota, FL 34236

(941) 388-4441

^* Author for correspondence: lkdixon@mote.org,

In order to evaluate the susceptibility of seagrasses in Charlotte Harbor to impacts from potential changes in nutrients and/or water clarity, SWFWMD-SWIM and CHNEP funded a study in Charlotte Harbor to 1) determine the light present at the deep edge of existing seagrass meadows, 2) determine light reduction associated with epiphyte coverage of seagrass blades, and 3) develop a spectrally sensitive optical model of water clarity to determine the relative contributions of various light attenuators, including CDOM. Attenuation of photosynthetically active radiation (PAR) was continuously monitored for one year at the deep edges of seagrass beds from the upper to lower Harbor. Discrete measurements were made weekly at these and other stations and monthly measurements of water color, turbidity, phytoplankton (as chlorophyll) and epiphytic attenuation were made at all stations. The morphological responses of the deep edges were determined in situ bimonthly.

The optical model performed well against field measurements of water column attenuation and the specific attenuation coefficients determined remain appropriate to use with more recent monitoring data. The model also incorporated seagrass action spectra to examine attenuation weighted for the wavelength ranges where seagrass photosynthesis is most efficient. The model demonstrated that color would continue to dominate water column attenuation during the study period, even should chlorophyll concentrations double. Average contributions of color, turbidity and chlorophyll to water column attenuation throughout Charlotte Harbor were 65%, 31%, 4%, respectively with expected spatial variations following CDOM/salinity distributions within the Harbor. Combined attenuators resulted in annual values of 13-30% of incident PAR reaching the bottom of the water column. Epiphytic attenuation reduced water column PAR by 21% to 44%. The water column light targets determined for seagrass, however, will only be accurate if epiphytic attenuations remain unchanged. Levels of PAR available to the plant are more biologically meaningful targets, but require that epiphytic attenuation be monitored in addition to water column parameters.

Flow, Source and Color in the Caloosahatchee River and Estuary

Peter H. Doering

South Florida Water Management District

Mail Stop 4420, 3301 Gun Club Road

West Palm Beach, Fl 33406

(561) 682-2772

pdoering@sfwmd.gov.

The Caloosahatchee River (C-43) is the major freshwater inflow to the Caloosahatchee Estuary. The River has been artificially connected to Lake Okeechobee. When water levels in the Lake get too high, the river carries regulatory discharges from the Lake to the estuary. Long term records of Color (1981-2006), measured at the Franklin Lock and Dam (S-79), which separates the river from the estuary, were analyzed for temporal trends and dependence on discharge. No long term increasing or decreasing trend was detected. The concentration of color increased with increasing discharge, but the source of discharge was also important. When most of the discharge at S-79 was from the C-43 basin, the slope of the relationship between color and discharge was steeper than when most of the discharge was from Lake Okeechobee. At higher flow rates, greater than about 450 cfs, the concentration of color at S-79 is higher when most of the discharge is coming from the C-43 basin, than when most is coming from Lake Okeechobee. Color concentrations at a station in the downstream estuary exhibited similar relationships to discharge and source of discharge at S-79.

The apparent mixing behavior of Color in the Caloosahatchee Estuary and San Carlos Bay was also investigated. The deviation from conservative mixing was dependent on the rate of discharge at S-79. At low discharge, apparent mixing behavior suggested addition of color, while at high discharge apparent removal occurred.

Land Use, CDOM, and Light Attenuation along the River-Estuary-Ocean Interface

E.C Milbrandt¹, A.D. Shapiro², J. Siwicke¹, A.J. Martignette¹ and R.S. Alberte³

¹Marine Laboratory, Sanibel-Captiva Conservation Foundation,

PO Box 839

900-A Tarpon Bay Rd

Sanibel, FL

(239) 395-4617

emilbran@sccf.org, jsiwicke@sccf.org and amartignette@sccf.org

²College of Arts and Sciences

Florida Gulf Coast University

Fort Myers, FL

ashapiro@sccf.org

³HerbalScience

Naples, FL

rsalbertehs@aol.com

The sources of freshwater discharges and their effects on estuarine habitats are central to any discussion about water quality and stormwater management. Given that land uses dictate both the quantity and quality of chromophoric dissolved organic matter (CDOM) in freshwater runoff, it follows that improved management practices could be derived by a complete characterization of CDOM. Discrete sampling and subsequent fluorometry and mass spectrometric analysis of the main stem of the tidal Caloosahatchee and C-43 canals demonstrated both spatial and temporal patterns in dissolved organic matter (DOM). The highest concentrations of terrestrial derived DOM, as measured by Em430 nm when excited by UV (Ex250 nm), were found in waters with low residence times (Franklin Lock), while low concentrations of terrestrial DOM were found in waters of high residence time (Cape Coral canals, Gulf of Mexico). The cumulative downstream effect of CDOM on seagrass habitats was to reduce the available light at the deep edge. Greater than 95% of the variation in blue light attenuation (433-453 nm) could be explained by CDOM, total suspended solids (TSS), and chl a concentrations. Of those optical constituents, CDOM contributed 60%, chl a contributed 10% and TSS, 5 %. Advanced in situ optical instrumentation can now detect the timing, duration and effects of stormwater or other discharges on estuarine ecosystems. New optical approaches are being developed to distinguish CDOM quality by UV absorption characteristics in coordination with a highly temporally resolved dataset of water column optical constituents (CDOM, turbidity, chl a). These tools will lead to the prioritization of tributaries and sources of freshwater discharge for restoration in order to minimize further seagrass losses.

Changes in Land Use in the Peace River Watershed and CDOM in the Lower Peace River Watershed and Upper Charlotte Harbor

Ralph Montgomery¹ and Sam Stone²

¹PBS&J

5300 West Cypress Street, Suite 300

Tampa, FL 33607

(941) 627-0901

estuary@comcast.net

²Peace River/Manasota Regional Water Supply Authority

8998 SW County Road 769

Arcadia, FL 34266

(863) 993-4565

sspeariv@hughes.net

The Peace River watershed has undergone widespread, large scale changes in land use since the 1940s. However, many of the most extensive changes in both native upland and wetland habitats in the watershed predate the availability of consistent, reliable water quality information. The figures below show long-term monthly water color data over the period 1976-2006 from the Peace River Hydrobiological Monitoring Program (HBMP) for both the predominantly freshwater reach of the lower Peace River upstream of the Peace River Regional Water Supply Facility (River Kilometer 30.4), as well as from the upper region of the harbor below the river’s mouth (River Kilometer -2.4).

The presentation evaluates historic water quality data from the lower Peace River, it’s major tributaries, and upper Charlotte Harbor collected as part of USGS, SWFWMD, and both Peace River and Shell Creek HBMP long-term monitoring programs. Color levels within the lower Peace River / upper Charlotte Harbor estuarine system are evaluated relative to both changes in land use and natural variability in rainfall and runoff. Differences are also discussed relative to methodologies that have been commonly used in measuring color levels both among sampling programs, as well as within individual monitoring programs over time.

A number of recent studies of historic rainfall and stream flow in the Peace River watershed have found patterns of natural variability generally consistent with the long-term intervals proposed for the Atlantic Multidecadal Oscillation (AMO). Annual watershed rainfall was generally above average from the early 1920s through approximately the early 1960s and then below average until the early/mid-1990s. Average annual rainfall in the watershed prior to the 1960s was about 54 inches per year, compared with about 50 inches per year from the 1960s to the early/mid-1990s. Since 1994, annual average rainfall has averaged approximately 53 inches per year. Analyses have indicated that these decadal differences primarily are the result of higher (four to five inches) wet season rainfall during warmer AMO intervals.

Posters

Coastal Charlotte Harbor Shoreline Mapping: Combining photo-interpretation technology with volunteer efforts

Jaime Boswell

Charlotte Harbor National Estuary Program

1926 Victoria Ave.

Fort Myers, FL33901

(239) 338-2556 x 230

jboswell@swfrpc.org

The Charlotte Harbor National Estuary Program (CHNEP) has created a list of environmental indicators to aid in assessing the relative condition of the estuary, and surrounding environment. One of the indicators is shoreline condition, for example presence of mangroves, hardened shoreline or exotic vegetation. The type of shoreline can indicate the level of protection against major storms and pollution, and the amount and quality of habitat available for fish, other aquatic organisms, and birds. A complete shoreline condition map can be used in multiple capacities including; scientific modeling, coastal planning, environmental management, and recreational interests. Two methods are being used to create a detailed shoreline map of the coastal Charlotte Harbor study area. Photo-interpreters will use recent high resolution photography to delineate the shoreline, assigning shoreline type classifications to unique segments along the coast. Shoreline types will include mangrove, exotic vegetation, rip rap, seawall, beach, other vegetation and other hardened features. Groundtruthing and accuracy assessments will be completed in the field to ensure a high quality product. Additionally, volunteer boaters are collecting data in Charlotte and Lee County, using similar methods as an existing Sarasota County project. The volunteer data collection includes quality of habitat assessments (e.g. presence of mangroves, height, hurricane damage, trimming, exotic vegetation) on the parcel level in developed areas of the study area, excluding man-made canal systems. Pairing the volunteer data with existing parcel GIS files and with the photo-interpreted shoreline GIS files will allow for detailed spatial analysis of shoreline features. Spatial analyses will determine “hotspots” of exotic vegetation, key restoration locations, and could estimate biomass of mangroves lost. Analyses in conjunction with other large region wide datasets, e.g. FWRI fisheries independent monitoring, and the Charlotte Harbor Regional Water Quality Monitoring Network, could be done to answer important questions about the role of the land-water interface in providing habitat and protecting water quality. The CHNEP anticipates completion of the project in Summer 2008, and encourages local researchers, managers, and outreach specialists to consider use of this valuable data in future work.

Numeric Water Quality Targets for Lemon Bay, Charlotte Harbor and Estero Bay, Florida using Seagrass Light Requirements

Catherine A. Corbett

Charlotte Harbor National Estuary Program (CHNEP)

1926 Victoria Avenue, Fort Myers, FL 33901

(239) 338-2556 x 241

ccorbett@swfrpc.org

In Lemon Bay, Charlotte Harbor and Estero Bay, seagrass areal coverage is non-trending since regular mapping began in 1988, and pollutant loads have not been documented as a threat to seagrass extent. Dissolved and suspended matter rather than chlorophyll a largely limit light availability, and inter-annual seagrass coverage changes are resultant from freshwater inflow changes from Charlotte Harbor’s tributaries. However, in the early 1990s, the FDNR reported that the Caloosahatchee River had reached its nutrient loading limits, indicated by elevated chlorophyll a and depressed dissolved oxygen levels, and water quality data collected in the tidal Peace River demonstrate that chlorophyll a levels exceeding 60-80 µg/L have occurred seasonally since monitoring began in 1976. A 2003 CHNEP analysis determined increasing trends in total suspended solids throughout the coastal Charlotte Harbor region and increasing trends in turbidity, nutrients and others in the Lower Charlotte Harbor region. The creation of numeric water quality targets to serve as the basis for water quality restoration and maintenance activities can serve as a tool to stop these declining trends.

We used an optical model to establish water quality targets for CDOM, turbidity and chlorophyll a by Charlotte Harbor basin. First we estimated percent-light-at-depth targets required to achieve seagrass maximum depth distribution in each basin. Next we applied an optical model which describes total light attenuation as the sum of three partial light attenuation components: CDOM, chlorophyll and non-algal suspended solids. By setting 2 components to zero, we calculated the maximum contribution of the 3^rd component to total light attenuation in terms of concentration intercepts (e.g. µg/L chlorophyll). Seasonal water quality data by basin were plotted on 3-D graphs with these concentration intercepts overlaid, producing a plane of constant attenuation given our percent-light-at-depth goal. This plane allows the concentration for each component to assume any concentration between zero and its intercept; its value dependent on the concentrations of the other 2 components. This objective is in contrast to many water quality targets that set a discrete maximum for each specific analyte without regard to concentrations of other relevant constituents affecting the targeted outcome. Water quality data points located outside of this plane identify times and locations when water quality did not meet the numeric targets for that basin. These targets should be modified in the future to reflect the importance of the quality in addition to quantity of light reaching seagrass beds. The optical model can be modified to reflect the importance of the blue region of the visible spectrum for seagrass photosynthesis in lieu of our current 25% subsurface light target that consists of all wavelengths between 400-700 nm.

In implementing these targets the CHNEP hopes to manage for anthropogenically-derived chlorophyll a and turbidity and better understand color. By hosting a CDOM workshop, the CHNEP hopes to initiate a dialogue and research to allow resource managers to better understand the role that landuse changes play with dissolved organic matter and concentrations in receiving water bodies. The program and its partners should design research and monitoring projects to address this issue.

Absorbance of the ultra violet and visible spectrum by colored dissolved organic matter in natural Southwest Florida waters

Keith A. Kibbey

Lee County Division of Natural Resources

Environmental Laboratory

60 Danley Drive Unit 2

Fort Myers, Florida 33907

(239) 278-7070

KIBBEYKA@leegov.com

The color in surface waters is primarily caused from the presence of natural organic matter, particularly humic and fulvic acids. Both cause a yellow-brown color, and in the presence of iron intensify the color through the formation of soluble ferric humates. Light attenuation models of Southwest Florida estuaries have shown that color plays the predominate role in light absorption. Color in water is usually measured by the visual comparison method or by relating the absorbance at a single wavelength (usually between 400 and 465 nm) to a platinum-cobalt standard. This study compares the entire UV/VIS spectra from several Southwest Florida estuaries and freshwaters to see if the absorption spectra are similar, and looks at the effect of minor pH changes in color.

A New System for Collecting High Resolution Spatial and Temporal Water Quality Data in lower Charlotte Harbor, FL

A.J.Martignette and Milbrandt, E.C.,

Marine Laboratory, Sanibel-Captiva Conservation Foundation

PO Box 839

900-A Tarpon Bay Rd

Sanibel, FL

(239) 395-4617

amartignette@sccf.org

emilbran@sccf.org

In highly dynamic and urbanize estuaries, traditional water quality sampling using discrete sample methods provide a snapshot view and often completely misses short lived events such as algae blooms and other features of poorly managed stormwater runoff. Commercially available instruments such as Satlantic’s Land/Ocean Biogeochemical Observatory (LOBO) are capable of providing real-time, high resolution, autonomous water quality data. LOBO is capable of measuring nitrate, chlorophyll, colored dissolved organic matter (CDOM), turbidity, salinity, temperature, dissolved oxygen, and depth. The LOBOViz software package provides researchers the ability to publish live and archived data on the internet in near real time. The LOBO is controlled by an onboard controller and a Linux server. Data from the sensors is transmitted to a server via a GSM modem. Changes to the sampling and data transmission schedules can be modified through the server. We have designed a multi-node sensing array to collect water quality data simultaneously from disparate locations. Data from these sensors will be imported to a GIS layer to provide an overview of the area. Water samples will be taken monthly and analyzed to Florida Department of Environmental Protection standards to calibrate the sensors. The flexible design of the LOBO allows multiply deployment options. Two moored models are available, one configured for protected bays, the other for shallow rivers. Removing the buoy from the river configuration exposes the LOBO’s main support rib, allowing for user customized mounting. We designed a custom mounting system to deploy the LOBO using existing structures in lower Charlotte Harbor without any modifications to the LOBO’s housing. Permission was received from the United States Coast Guard to attach our LOBO’s to channel marker pilings. The ability to mount the LOBO inconspicuously underwater lessens the chances of vandalism, or damage from negligent boaters that could occur with surface mounted instruments. In addition to standard field deployment we have designed a flow-though system to allow mobile assessments of the previously mentioned parameters. A 53 gallon tank with an approximate turnover rate of two minutes was built to be transported in a small research vessel. When connected to a notebook computer, which is connected to a GPS receiver, the coordinates of the sample location are stored along side the water quality data. The mobile LOBO will be deployed to prioritize hotspots and tributaries for stormwater management and restoration.

Assessing Validity and Reliability of Optical Model Predictions of Light Attenuation in Charlotte Harbor, Florida

Mike Wessel ¹

Janicki Environmental, Inc.

1155 Eden Isle Drive

St. Petersburg, FL 33704

(727) 895-7722

mwessel@janickienvironmental.com

Catherine Corbett ²

Charlotte Harbor National Estuary Program

1926 Victoria Avenue, Fort Myers, FL 33901

(239) 338-2556 x 241

ccorbett@swfrpc.org

The water quality targets developed by the CHNEP are an important contribution to identifying thresholds in water quality that may affect the health and productivity of valued natural resources in the Charlotte Harbor Estuary. At the time the targets were developed, there was insufficient data to validate the optical model against observed data. This poster describes an exercise to validate the optical model predictions against observed data now that more data on empirical light attenuation have become available. Predicted light attenuation was compared to observed light attenuation and residual plots were constructed to examine prediction errors as a function of the water quality indicators used to the develop the model as well as other factors not included in the model. Prediction bias was assessed using the average of the residuals and reliability of the model was assessed using the mean square error (MSE), an estimate of variability of the predicted light attenuation against that observed at concurrent measurements. Agreement between the predicted target exceedances based on the stratum specific light attenuation targets and the exceedance frequency using the observed data were tested using McNemars’s test for matched pairs. The optical model performed well for most strata within the estuarine portions of Charlotte Harbor though substantial variability existed between observed and modeled data in some cases. In Upper Charlotte Harbor, the East and West Wall strata exhibited significant disagreement between observed and predicted light attenuation with the optical model exhibiting significant over-prediction bias. For the other strata, agreement was within the expected agreement based on the sample size. In strata where over- prediction occurred, the model appeared to over-estimate the effects of chlorophyll a on light attenuation. A simulation exercise was conducted by adjusting the optical model coefficient for chlorophyll while holding the other coefficients in the model as constant and assessing the bias and MSE at each iteration. It was shown that bias and MSE could be reduced by reducing the chlorophyll coefficient in these cases and that a reduced exceedance frequency would result. Two strata in Lower Charlotte Harbor, Pine Island Sound and Matlacha Pass, also exhibited some prediction bias as a function of Chlorophyll; however, the effects on over prediction were less clear perhaps to due increased variability in the observed data. While this exercise assumed observed light attenuation to be measured without error, it is likely that measurement error existed in the empirical measurement of light attenuation. However, given the available data it appears that the optical model is estimating the light attenuation without significant bias in most strata. Strata that exhibited prediction bias appeared to be more open estuary strata susceptible to the greatest mixing of gulf waters and fresh water inflows from the Peace, Myakka and Caloosahatchee Rivers.