Final Report to the National Park Service in response to Project Statement BISC-N-011.000 under NPS/FIU Cooperative Agreement No. CA5280-8-9038

TOTAL AMMONIA CONCENTRATIONS IN SOIL, SEDIMENTS, SURFACE WATER , AND GROUNDWATER ALONG THE WESTERN SHORELINE OF BISCAYNE BAY WITH THE FOCUS ON BLACK POINT AND A REFERENCE MANGROVE SITE

John Meeder, Ph.D. Joseph N. Boyer, Ph.D.

Southeast Environmental Research Center Florida International University Miami, FL 33199

12 February 2001

### EXECUTIVE SUMMARY

This study focused on ammonia as a potential stressor of marine benthic communities in Biscayne Bay but also included other nutrients as well. The specific tasks included in this project were: 1) Black Point Monitoring Program, 2) Black Point Monitoring Comparison, 3) Shoreline Nutrient Survey, 4) Shoreline Benthic Community Survey, and 5) Mangrove Transect Comparison. The Black Point Monitoring Program showed that nutrient concentrations (especially ammonium were elevated in the canals adjacent to the landfill. The median value of unionized ammonia at Station 12 was 122 ppb which may be toxic to some marine fish. However, the very low dissolved oxygen at the same site would also preclude much marine life from thriving in this area. The Black Point Monitoring Comparison was performed by statistical comparison of data from 1993 surveys with this study. No differences in water quality in the canals or nearshore area were found. We can clearly say that there has been no measurable improvement in water quality between surveys. The Shoreline Nutrient Survey showed that ammonium concentrations were highest in the nearshore waters off Black Point, the Cutler Channel, and the Mowry Canal area. A very different distribution was observed for nitrate where highest concentrations were found off the Cutler Channel and very low levels found in the nearshore waters between Cutler Channel and Goulds Canal. A hot spot in total phosphorus was observed off Mangrove Key in extreme south Biscayne Bay. Another interesting aspect was the correspondence between sediment and water column nutrient levels. Levels of ammonium in the sediments are approximately an order of magnitude higher than the water column and generally follow each other. This was also true for total phosphorus although the concentrations in sediment and water were different by only a factor of 3. Shoreline Benthic Community Survey resulted in the classification of 5 angiosperms and 22 algal species. Among the angiosperms, Thalassia testudinum and Halodule wrightii , were the
most common. Thalassia and Halodule did not share the same distribution or abundance patterns from north to south - small amounts of Halodule were found throughout the study area with a general increase in abundance from south to north. The inverse was true with Thalassia abundance, which generally increased in abundance in the southerly direction. A break in Thalassia distribution occurred at the Goulds Canal/Black Point Area. For several km south, no Thalassia was reported but abundant Halodule was found in its place along with unknown green species, brown algae, and other noncalcareous green species. The break in Thalassia cover may have been partly due to salinity. Salinity during the survey increased dramatically from north to south, however, highest Thalassia densities occurred in the areas experiencing hypersaline conditions. Variability in salinity may have been important to mortality of Thalassia but salinity in the area between Goulds and Military Canals is not as variable as it is off the Mowry Canal. The only other water quality variable which may have influenced Thalassia was ammonium. The nearshore area between Goulds and Military Canals has the highest concentrations of ammonium in the water column and sediments of any site in this study. Our results indicate a strong correlation between elevated ammonium concentrations with 1) decreased abundance of Thalassia , 2) increased abundance of Halodule and fast growing algae species, and 3) the increase in filamentous algal cover.The Mangrove Transect Comparison showed that the mangrove fringe was a source of total phosphorus and possibly some ammonium to the Bay, but not as much as suspected. The Bay itself was a source of nitrate to the mangrove fringe. Understanding: 1) nutrient concentration spatial and temporal distributions, 2) the relationship between ammonia concentration and the level of benthic community degradation, and 3) the relative significance of natural nutrient addition to the system from anthropogenic or additional loading is paramount to establishing pollution load reduction goals. This project focused on the first two needs listed above to begin to establish a data base for the calculation of load and sources of load to Biscayne National Park.

### Acknowledgments We thank all the field and laboratory technicians involved with this project especially Sean Gilhooly, Braxton Davis, and Amy Renshaw. We also want to thank Max Flandorfer at Biscayne National Park for boat time and field support. This project was possible due to funding by the National Park Service under NPS/FIU Cooperative Agreement No. CA5280-8-9038. Funding for other portions of the SERC Water Quality Monitoring Network was provided by the South Florida Water Management District and Everglades National Park (NPS/SERC Cooperative Agreement #5280-2-9017 and NPS/SFWMD Cooperative Agreement #C-7919). This is Technical Report #T141 of the Southeast Environmental Research Center at Florida International University.

### INTRODUCTION

Biscayne Bay is a shallow subtropical lagoonal estuary located on the southeast coast of Florida. The Bay is situated as a topographic basin on the surface of the Miami Limestone which outcrops to the west of the western shoreline forming a coastal ridge. Biscayne Bay is separated from the Atlantic Ocean by a series of barrier islands and limestone keys cut by shallow tidal passes. Biscayne Bay originated ~6,000 ybp as sea level rose during the Holocene transgression and has increased to a maximum depth of ~4 m during that time. The N-S orientation and different coastal morphology allow the Bay to be separated into three distinct regions: North, Central and South Bay (Card Sound). North Bay is a highly urbanized system. Channel dredging, the construction of Haulover Cut, and the extensive enlargement of Government Cut has altered circulation patterns resulting in increased salinity in this zone. The western shore of Central Bay (Dinner Key to Turkey Point) was originally composed of a mangrove fringe and extensive freshwater marshes reaching to the foot of the coastal ridge several miles inland. These freshwater marshes were maintained by local rainfall and Everglades discharge via the transitional glades. After the turn of the century the transverse glades were channeled and drained directly into Biscayne Bay which resulted in saltwater encroachment. This was identified by the early 1940's and control structures and a coastal storm protection levee (L-31E) were constructed. The L-31E canal and levee system eliminated all sheet flow to Central and South Biscayne Bay. Canal water now enters the Bay as a point source and contains high levels of urban and agricultural waste creating a nutrient loading and time of delivery problems in the ecosystem. South Bay is relatively isolated from urban development, with the exception of Turkey Point Power Plant facility. Although this region has historically received less freshwater runoff than other areas of the Bay, it has also seen the greatest decline in freshwater inputs due to construction of the L-31E levee and US 1. Biscayne National Park is located adjacent to large population and agricultural centers of Miami-Dade county. Over the past 100 years of land development, Biscayne Bay circulation patterns have been highly altered by management activities. Freshwater sheet flow discharge was replaced by channelized discharge via canals which radically changed the quantity, timing, and distribution of input to the Bay (Alleman et al. 1995). Because of this management activity, the estuarine zone of Biscayne Bay has been much reduced. In conjunction with the changes in quantity, timing, and distribution of freshwater there have been changes in quality of the input. The water quality of both canal and groundwater inputs has declined as urbanization and agriculture have become more pronounced across the landscape. Numerous landfill and contaminated sites impact the groundwater that enters Biscayne Bay (Meeder et al. 1997). Nutrient loading estimates from the Mowry Canal to Biscayne Bay are very high compared to the typically low levels (oligotrophic conditions) found in other areas (Meeder et al. 1997). The addition of groundwater nutrient inputs to the model suggests that Biscayne Bay may be undergoing considerably more nutrient loading than previously thought (Meeder et al. 1997). This poses not only an environmental degradation problem but one of potential ammonia toxicity. As a consequence, the nearshore aquatic environment has displayed symptoms of decreased primary productivity and offshore migration of desirable benthic communities (Meeder et al. 1997). This study focuses on ammonia as a potential stressor of marine benthic communities. Coastal mangroves are highly productive systems that are known to export ammonia because ofmicrobial N 2 fixation associated with aerial roots (Boto and Robertson 1990) and anaerobic decomposition processes (Peligri and Twilley 1999). Ammonia production in the coastal mangrove system is limited to a fraction of the biomass turnover on an annual basis and is therefore fixed within rather narrow bounds at any site (Boto and Robertson 1990; Lara and Dittmar 1999). In addition, most mangrove swamps along the western shore of Biscayne Bay grow in carbonate marl soil, about 1 m thick, which overlies the bedrock (and groundwater). This mud layer is relatively impermeable and separate the surficial interstitial soil and tidal water from the terrestrial groundwater from the watershed. This means that ammonia derived from inner mangrove forests is separate from anthropogenic derived ammonia in groundwater until they discharge into the Bay. An exception to this may be the thin fringing mangrove zone along the waters edge which frequently are not underlain by the marl soil horizon. This is the zone of highest productivity, greatest physical export of detritus, greatest belowground biomass production (actually accretion), and soils with the best gas exchange. Groundwater nutrient levels obtained 50 m from shore along Biscayne Bay from the Dinner Key to Mowry Canal have total ammonia concentrations 30 or more times greater than those of overlying surface waters (Meeder et al. 1997). In addition, highest groundwater concentrations were found at Black Point and decreased by nearly half both northwards and southwards (Meeder et al. 1997). The location of the highest concentrations off Black Point was no surprise because the site is located close to the old and present Dade County landfills. Only limited data on Biscayne Bay ammonia concentrations is available for inshore areas. The need to understand the distribution of ammonia in Biscayne National Park is necessary to establish pollution guidelines based upon real spatial and temporal distributions and their impacts to Bay ecology. A restudy of the Black Point area will aid in the determination if remedial environmental protection activities at the landfill have succeeded in lowering the nutrient concentrations delivered to the Bay. Comparisons between the Black Point area and the mangrove reference site should also aid the Park in determining the background levels of ammonia expected from coastal mangroves in contrast to ammonia levels associated with anthropogenic activities.

The specific tasks included in this project were: Task 1 - Black Point Monitoring Program Task 2 - Black Point Monitoring Comparison Task 3 - Shoreline Nutrient Survey Task 4 - Shoreline Benthic Community Survey Task 5 - Mangrove Transect Comparison

The Black Point Monitoring Program (Task 1) was designed to produce a monthly characterization of nutrient concentrations in the receiving waters surrounding the landfill. Comparisons between previous (Jones 1994) and current nutrient levels at Black Point (Task 2) indicated if remedial activities for the protection of the Bay from excess nutrient loading have been successful. The purpose of the Shoreline Nutrient Survey (Task 3) was to produce a high resolution map of ammonia along the western BNP shoreline and to point out any hot spots within the mangroves, surface water, and marine sediments. This data was then combined with the ongoingBiscayne Bay Water Quality Monitoring Program operated by SERC and funded by SFWMD to produce a more generalized “snapshot” of nutrient levels in the Bay. The concurrent Shoreline Benthic Community Survey (Task 4) was designed to provide a high resolution map of plant community structure along the west coast. Comparisons between benthic community characteristics and ammonia levels in water and sediments were proposed to develop an impact gradient curve of the relationship between ammonia levels and degree of community degradation. Documentation of the distribution of ammonia levels and their impacts on the benthos would then be used in the development of non-degradation criteria for BNP
waters. The comparison of mangroves at Black Point and the reference site (Task 5) is designed to determine whether there is a difference between ammonia levels found in natural and impacted areas. The transect data will provide a source gradient by which we can calculate the relative magnitude of ammonia input to the system via mangrove fringe.

### METHODS

Task 1 - Black Point Monitoring Program The Black Point Monitoring Program was conducted monthly for one year at six canal surface water sample sites and two terrestrial sites (Fig 3). Most of these sites were the same as those sampled in the previous Black Point study (Jones 1994) in order to allow a direct comparison between data sets (Task 2). The purpose of this component is to determine the magnitude and extent of any ammonia source gradient from the landfill site. In addition, two soil sites were established along the east side of the landfills, on separate sides of the canal. We decided to measure other nutrient variables along with ammonium in order to ascertain if the landfill had an impact on them as well. This decision was made with best science in mind. However, because of the increased costs, we were restricted to conducting only one shoreline ammonia and benthic survey instead of the proposed two. Surface and bottom salinity (psu) and temperature (oC) were measured using a combination salinity-conductivity-temperature probe (Orion model 140). Dissolved oxygen (DO, mg l -1 ) was measured 10 cm below the surface using an oxygen electrode (Orion model 840) corrected for salinity and temperature. Water samples were collected in sample-rinsed HDPE bottles using standard SERC procedures. Interstitial water of soils and sediments for the Shoreline Nutrient Survey were collected by vacuum lysimeter. Soil and sediment were collected by coring. Duplicate, unfiltered water samples were collected using 3x sample rinsed 120 ml HDPE bottles for analysis of total constituents. Duplicate water samples for dissolved nutrients were collected using 3x sample rinsed 150 ml syringes which were then filtered by hand through 25 mm glass fiber filters (Whatman GF/F) into 3x sample rinsed 60 ml HDPE bottles. Unfiltered water samples were analyzed for total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), total silicate (Si(OH) 4 ), and turbidity. TOC was measured by direct injection onto hot platinum catalyst in a Shimadzu TOC-5000 after first acidifying to pH<2 and purging with CO 2 -free air. TN was measured using an ANTEK 7000N Nitrogen Analyzer using O 2 as carrier gas to promote complete recovery of the nitrogen in the water samples (Frankovich and Jones 1998). TP was determined using a dry ashing, acid hydrolysis technique (Solórzano and Sharp 1980). TS was measured using the molybdosilicate method (Strickland and Parsons 1972). Turbidity was measured using an HF Scientific model DRT-15C turbidimeter and reported in NTU. Filtrates were analyzed for soluble reactive phosphorus (SRP), nitrate+nitrite (NO x ), nitrite (NO 2 - ), and total ammonia (NH 4 + ) on a four channel autoanalyzer (Alpkem model RFA 300). All analyses were completed within 28 days after collection (except for NH 4 + , which was run the following day) in accordance to standard SERC laboratory quality control guidelines. Some parameters were not measured directly, but were calculated by difference. Nitrate (NO 3 -2 ) was calculated as NO X - - NO 2 - , dissolved inorganic nitrogen (DIN) as NO X + NH 4 + , and total organic nitrogen (TON) defined as TN - DIN. All concentrations are reported as ppm-N or P unless noted. All elemental ratios discussed were calculated on a molar basis.Task 2 - Black Point Monitoring Comparison Data from Jones (1994) and current programs were compiled and analyzed by station using the Mann-Whitney U test; the nonparametric version of the two group unpaired t -test. Significance was set at P<0.05.

Task 3 - Shoreline Nutrient Survey During the 1998 dry season, nutrient concentrations in nearshore surface water (~50 m offshore), marine sediment pore water (~50 m offshore), mangrove soils (~25 m onshore), and mangrove surface waters (~25 m onshore) were sampled approximately every 1 km along the west shoreline for a total of 22 (Fig 2). We also sampled near canal mouths and at significant features. Data from the Shoreline Nutrient Survey were combined with data from the FIU water quality monitoring program for Biscayne Bay. All data was collected in the same month and presented as kriged contour plots (Surfer, Golden Software).

Task 4 - Shoreline Benthic Community Survey The Shoreline Benthic Community Survey was conducted in conjunction with the Shoreline Nutrient Survey. Benthic plant community structure was characterized in three plots (0.25 m 2 ) within one meter of each Shoreline Ammonia Survey sampling site. The number of shoots of marine plants was counted, measured, and weighed in subplots within each of the three plots. Plant taxa and their abundance were recorded using the Braun-Blanquet survey method (Fourqurean et al. 2000). Species presence, percent cover, and community structure along with distance from shore, water depth, soil depth and type, salinity, and other parameters was also recorded. Epiphyte percent cover was recorded on the larger plant leaves and bay bottom at each plot. Data were analyzed by standard methods employed in earlier studies (Meeder et al. 1997).

Task 5 - Mangrove Transect Comparison The Mangrove Transect Comparison was structured so as to provide information concerning nutrient inputs from mangrove forests in Biscayne Bay. The sampling area was selected based upon several criteria: 1) low range of ammonia concentration, 2) lack of known anthropogenic source of ammonia, and 3) similar type mangrove system as found at Black Point (narrow fringe with wide basin). Five sites were sampled: a upstream mostly freshwater distribution canal (DC) which was 640 m west of the coast and 300 m north of the Mowry Canal; a site east of DC in the mangrove fringe (TF); a site just offshore TF (TBB); a mangrove fringe site 500 m south of the Military Canal (CF); and a corresponding offshore site (CBB). At each site, surface water and soil or sediment were sampled and analyzed for nutrients as above on a monthly basis for one year.

### RESULTS

Task 1 - Black Point Monitoring Program Summary of results from the monthly Black Point Monitoring Program are shown in Table 1. For the period of record, salinity ranged from 0.02 – 39.7 psu; temperature from 20.9 – 31.6 o C, DO from 0.2 – 11.4 mg l -1 , pH from 6.90 – 8.78, NH 4 + from 0.004 – 26.97 ppm, and NH 3 from 0.0 – 654 ppb. Additional nutrient values also showed large ranges: NO 3 -2 from 0.002 – 0.415 ppm and TP from 0.002 – 0.94 ppm. These large ranges are indicative of terrestrial/groundwater nutrient loading to the canals and inshore areas of Biscayne Bay. Monthly maps of NH 4 + concentration plotted by station are presented in Figs. 3-14. Concentrations are on log scale because the range in data was so large. Highest NH 4 + concentrations routinely occurred at Sta #12 which is directly downstream of the landfill. Sta. #12 also had highest DOC, NO 2 - , NH 3 , SRP, and lowest DO levels. The median value of NH 3 at #12 was 122 ppb which may be toxic to some marine fish. However, the very low DO at the same site would also preclude much marine life from thriving in this area.Differences among stations were shown as box-and-whisker plots (Fig. 15 & 16). The boxand-whisker plot is a powerful statistic which displays the median, range, and the shape of thedata distribution. Water quality variable distributions are usually skewed to the right (nonnormal) so it is more appropriate to use the median as the measure of central tendency. The central, horizontal line of the box is the median of the data, the top and bottom of the box are the 25th and 75th percentiles (quartiles), the ends of the whiskers are the 10th and 90th percentiles, and any points outside (<10th and >90th percentiles) may be considered outliers (suppressed in the graphs). The box-and-whisker plot also serves as a graphical, nonparametric ANOVA. The notch in the box is the 95% confidence interval of the median. When notches among boxes do not overlap, the medians may be considered significantly different. Comparing the canal sites (#10, 11, 12, & 13) to the nearshore sites (#14 & 15) it becomes clear that the nearshore sites have higher salinity, pH, and a narrower range in nutrients. We should point out that station #14 was located in the water column above two groundwater wells in ~1 m of water. Water quality at this site may have been influenced by seepage from these wells as they had positive hydraulic pressure at all times of sampling. The shallow well had significantly higher NO 3 -2 and lower salinity than the deep well (data not shown). From this we may imply that groundwater in the shallow well was derived more from surface water than the deep well, which has been previously confirmed by Meeder et al. (1997). Both wells had significant amounts of NH 4 + present; generally an order of magnitude greater than un-impacted surface waters.

Task 2 - Black Point Monitoring Comparison Statistical comparison of data from 1993 surveys with this study resulted in no significant difference (P>0.05) in water quality variables in the canals or nearshore (Fig. 17-20). Each station was treated separately using a Mann-Whitney U test; the nonparametric version of the two group unpaired t -test. What was noticeable was that the ranges in the data of the current study were larger than found in the previous study. This was probably the result of climactic influence such as higher rainfall in 1998-99. We can clearly say that there has been no measurable improvement in water quality between surveys.Task 3 - Shoreline Nutrient Survey This survey was conducted in April 1998 which happened to occur at the end of a very dry season. Salinity in southern Biscayne Bay was elevated in both nearshore and offshore areas (Fig. 21) as a result of this. Ammonium concentrations (Fig. 22) during this period were highest in the nearshore waters off Black Point (0.035 ppm), the Cutler Channel (0.148 ppm), and the Mowry Canal area (0.013 ppm). NH 3 was also elevated in these areas (Fig. 23) being 3.6, 2.4, 3.1 ppb, respectively. A very different distribution was observed for NO 3 -2 (Fig. 24) with highest concentrations being found off the Cutler Channel (0.148 ppm) and very low levels found in the nearshore waters between Cutler Channel and Goulds Canal. A hot spot in TP (0.0519 ppm) was observed off Mangrove Key in extreme south Biscayne Bay (Fig 25). Otherwise, TP concentrations were very low (<0.015 ppm) throughout the Bay. TOC (Fig. 26) and TON (Fig. 27) showed similar high nearshore – low offshore gradients. Highest TOC (12.2 ppm) and TON (1.6 ppm) concentrations occurred off the mangroves between Cutler Channel and Goulds Canal. There was also a local increase in TON between Goulds and Military Canals. Another interesting aspect of the Shoreline Nutrient Survey was the correspondence between sediment and water column nutrient levels. Figure 28 shows the NH 4 + concentration in water and sediment along the coast from north to south. Levels of NH 4 + in the sediments are approximately an order of magnitude higher than the water column and generally follow each other. This was also true for TP (Fig. 29) although the concentrations in sediment and water were different by only a factor of 3. Interestingly, the area around Black Point which showed high NH 4 + from the landfill had a corresponding depression in TP. This may be because of increased biological demand for P from the external supplement of N.

Task 4 - Shoreline Benthic Community Survey Table 2 is a list of marine plant taxa reported in this study. Taxa were included only when found in more than three separate plots or if they occupied more than 2% of the area in a single plot. This criteria excluded numerous uncommon species that carry little ecological information at the community level supported by literature. Five angiosperms and 22 algal species were recorded. Filamentous algae were not further classified. Among the angiosperms, Thalassia testudinum and Halodule wrightii , were the most common, the others being found only at a few stations. Thalassia and Halodule , although abundant at most sites, did not share the same distribution or abundance patterns from north to south (Fig. 30). Minor amounts of Halodule were found throughout the study area with a general increase in abundance from south to north. The inverse was true with Thalassia abundance, which generally increased in abundance in the southerly direction. The red algae group was also more abundant in the south. Penicillus and most other calcareous green species displayed the same distributional pattern as Thalassia . Some fast growing green algae species ( Acetabularia ) did not exhibit obvious trends in distribution or abundance. Filamentous algae was not taxonomically subdivided further but was reported as percent cover as an epiphyte. Generally, either filamentous algae cover was low (less than 20% of available substrate) or significant (over 80% of available cover). Filamentous algae cover was highest in the area between Black Point and the Mowry Canal with minor hot spots located near other canal mouths. A break in Thalassia distribution occurred at the Goulds Canal/Black Point Area. For several km south, no Thalassia was reported but abundant Halodule was found in its place (Fig. 29).The break in Thalassia was also associated with changes in distribution of other marine plants. An unknown green species, brown algae, and other noncalcareous green species increased in abundance where Thalassia was not present. The break in Thalassia cover may have been partly due to salinity. Salinity during the survey increased dramatically from north to south (Fig. 31), however, highest Thalassia densities occurred in the areas experiencing hypersaline conditions. Variability in salinity may have been important to mortality of Thalassia but salinity in the area between Goulds and Military Canals is not as variable as it is off the Mowry Canal (Boyer, unpublished data). The only other water quality variable which may have influenced Thalassia was NH 4 + (Fig. 32). The nearshore area between Goulds and Military Canals has the highest concentrations of NH 4 + in the water column and sediments of any site in this study. It was more likely that chronic inputs of NH 4 + were responsible for Thalassia loss.

Task 5 - Mangrove Transect Comparison Data were analyzed using the nonparametric Mann-Whitney U Test which is comparable to an unpaired t Test. Some general trends were observed which are best visualized in Fig. 33. The distribution channel (DC) was not a source of NO 3 -2 , NH 4 + , TP, or SRP to the mangroves. However, DC was a significant source of Chl a and TOC to the mangrove fringe. The mangrove fringe itself was a source of TP, SRP, and possibly NH 4 + to the Bay. The Bay itself was a source of NO 3 -2 to the mangrove fringe. Nutrient concentrations in the mangrove fringe sites (TF and CF) were not significantly different from each other (P>0.10) so they could be pooled and treated as being representative of the mangrove fringe in Biscayne Bay. However, we did not do this as the Bay sites had some significant differences – NH 4 + and TOC were slightly higher at CBB and NO 3 -2 was lower. Most important was the finding that although NH 4 + concentrations are high in mangroves, a significant portion of that may be derived from upland drainage.

### DISCUSSION

The Black Point Monitoring Program showed that nutrient concentrations (especially ammonium were elevated in the canals adjacent to the landfill. The median value of unionized ammonia at Station 12 was 122 ppb which may be toxic to some marine fish. However, the very low dissolved oxygen at the same site would also preclude much marine life from thriving in this area. The Black Point Monitoring Comparison was performed by statistical comparison of data from 1993 surveys with this study. We found no difference in water quality in the canals or nearshore area between the two studies. From this we can clearly state that there has been no measurable, beneficial effect of remediation activities on the water quality of the Black Point

area. The Shoreline Nutrient Survey showed that ammonium concentrations were highest in the nearshore waters off Black Point, the Cutler Channel, and the Mowry Canal area. A very different distribution was observed for nitrate where highest concentrations were found off the Cutler Channel and very low levels found in the nearshore waters between Cutler Channel and Goulds Canal. A hot spot in total phosphorus was observed off Mangrove Key in extreme south Biscayne Bay. Another interesting aspect was the correspondence between sediment and water column nutrient levels. Levels of ammonium in the sediments are approximately an order of magnitude higher than the water column and generally follow each other. This was also true for total phosphorus although the concentrations in sediment and water were different by only a factor of 3. Submerged aquatic plant communities respond to nutrient loading by the replacement of slow growing with faster growing species and finally by phytoplankton (Duarte 1995). In many South Florida water bodies heavy epiphytic algae growth replaces phytoplankton, with the same end result. In many cases, the indirect effect of faster growing species dominance is additional stress on the slower growing species by shading or light exclusion (Orth and Moore 1983). Thalassia is replaced by Halodule in seagrass areas with increases nutrient loading (Powell et al 1991; Fourquerean et al 1995). In other studies Zostera marina and Ruppia were replaced by faster growing green algae species The distribution of Thalassia and other aquatic vegetation have been linked to groundwater discharge in Biscayne Bay (Kohout and Kolipinski 1967; Meeder et al 1996) and other regions such as Yucatan, Mexico (Herrera-Silveira 1994) and Australia (Johannes 1980). Meeder et al (1997) found that Thalassia was not abundant in areas receiving groundwater discharge. This area was from the shoreline to 400 m offshore in the area between the Military and Mowry Canals. Benthic community distribution influenced by groundwater discharge usually form bands parallel to the shoreline and the effects of groundwater discharge usually decrease exponentially with distance offshore. However, the major source of western Biscayne Bay nutrient loading is canal discharge. Canal discharge varies more in both nutrient concentration levels and discharge volumes seasonally than does groundwater. Because most canal discharge occurs during the rainy season with prevailing southerly or southeasterly winds canal waters most frequently pile up along the western shore of Biscayne Bay. Therefore low salinity, nutrient rich canal water is held along the shoreline. The effects of this pattern of freshwater canal discharge is hard to separate from the groundwater discharge pattern in terms of nearshore benthic community structure andproductivity (Meeder et al 1997). The nutrient loading of both canal and ground water is significant. Although ammonia toxicity or increased nutrient concentration may be responsible for the lack of Thalassia and slower growing algae species in the vicinity of Black Point our data does not unequivocally support this relationship. Our data does support a more than causal relationship between high NH 4 + concentration with the lack of Thalassia , however, the nutrient levels may be a surrogate of other causes. For example, both high NH 4 + and nutrient concentrations are related to freshwater delivery to the bay via canal and groundwater, which may carry other agents acting alone or synergistically with NH 4 + and nutrients to cause toxic or unfavorable conditions for Thalassia and other slow growing plants. In addition, salinity characteristics may also play a role in Thalassia competition. Thalassia responds best to normal marine salinities. Salinities too high or too low or a rapidly changing salinity regime produce stress to Thalassia that frequently favors other species. Historically the northern portion of Biscayne Bay was much more estuarine in nature but has maintained near marine salinities since the opening of Haulover Cut and dredging of Miami River-Government Cut Channels which permit rapid freshwater discharge mixing and export. Northern Biscayne Bay also has more frequent high turbidity periods which affects light availability, especially in deeper portions of the Bay (Harlem 1979). The southern part of the Bay is less well flushed, perhaps, but has much less freshwater discharge. This is especially true south of North Canal. In this region salinities are always near marine conditions and can become slightly hypersaline during extended dry periods such as during our April sampling period. Normally Thalassia abundance increases from north-to-south because of more continuous near marine salinity and low turbidity levels in Southern Biscayne Bay. This trend is apparent when plotting salinity vs Thalassia abundance (Fig. 30). The break in the trend is obviously not soley the result of salinity. The major purpose of the funding for this project was to determine if NH 4 + levels were elevated enough in the waters and soils of nearshore Biscayne Bay to produce toxic affects on Thalassia . Previously the relationship between Thalassia distribution and salinity and nutrient concentrations were discussed with the conclusion that the competitive advantage of fast growing species over slow growing species and the resulting light competition can adequately explain the lack of Thalassia along the North-to-south study gradient. However, a close examination of the relationship between NH 4 + concentration and Thalassia abundance indicates that in areas of NH 4 + concentrations greater than 0.015 ppm excludes Thalassia . However, in these areas other nutrients except TP are also quite elevated and therefore NH 4 + alone cannot be.implicated. The Mangrove Transect Comparison showed that the mangrove fringe was a source of total phosphorus and possibly some ammonium to the Bay, but not as much as suspected. The Bay itself was a source of nitrate to the mangrove fringe. NH 4 + levels in nearshore Biscayne Bay and in the coastal mangrove soils are often quiet high for normal surface waters but probably do not in themselves produce toxicity. One reason for the high concentrations may be groundwater inputs. Anaerobic groundwater contains high levels of NH 4 + especially the shallow groundwater around the Black Point landfill. High discharge rates of 1-3 l hr -1 m -2 (Meeder et al. 1997) may supply a significant and unrecognized N load to the Bay.

### CONCLUSIONS Freshwaters reaching nearshore Biscayne Bay contains numerous nutrients, metals, hydrocarbons, pesticides, and herbicides from anthropogenic sources. We have quantified nutrients with particular attention to NH 4 + . Our results indicate a strong correlation between elevated ammonium concentrations with 1) decreased abundance of Thalassia , 2) increased abundance of Halodule and fast growing algae species, and 3) the increase in filamentous algal

cover. The high salinities encountered during this study are associated with a very dry winter. Therefore, the effects of canal inputs on ambient nutrient concentrations are minimal during this period. The elevated nutrient levels observed should be considered a chronic condition. Conclusions can not be made that ammonia toxicity is solely responsible for the loss of Thalassia and other slower growing algae.

### REFERENCES

Alleman, R. W., et al. 1995. Biscayne Bay surface water improvement and management. Technical supporting document. South Florida Water Management District.

Boto, K. G., and Robertson, A. I., 1990. The relationship between nitrogen fixation and tidal exports of nitrogen in a tropical mangrove system. Estuar., Coast. Shelf Sci. 31: 531-540.

Duarte, C. M., 1995. Submerged Aquatic Vegetation in Relation to Different Nutrient Regimes: Ophelia 41: 87-112.

Fourqurean, J. W.; Durako, M. J.; Zieman, J. C., 1999. Seagrass monitoring in the Florida Keys National Marine Sanctuary, Annual Report, FY 1999: FKNMS.

Fourqurean, J. W.; Powell, G. V. N.; Kenworthy, W. J.; Zieman, J. C., 1995. The effects of long-term manipulation of nutrient supply on competition between the seagrasses Thalassia testudinum and Halodule wrightii in Florida Bay: Oikos 72: 349-358.

Frankovich, T. A., and Jones, R. D., 1998. A rapid, precise, and sensitive method for the determination of total nitrogen in natural waters. Marine Chemistry 60: 227-234.

Harlem 1979. Aerial photographic interpretation of the historical changes in northern Biscayne Bay, Florida; 1952-1976. University of Miami, Coral Gables, FL.

Harlin, M. M., Thorne-Miller, B., 1981. Nutrient enrichment of seagrass beds in a Rhode Island coastal lagoon: Marine Biology 65: 221-229.

Herrera-Silveira, J. A., 1994. Nutrients from underground water discharges in a coastal lagoon (Celestun, Yucatan, Mexico): Verh. Internat. Verein. Limnol. 25: 1398-1401.

Johannes, R. E., 1989. The ecological significance of the submarine discharge of groundwater: Marine Ecology Progress Series 3: 365-373.

Jones, R. D., 1994. Biscayne Bay Ammonium Monitoring. Final Report to Biscayne National Park under NPS/SERP Cooperative Agreement CA-5280-8-8007.

Kohout, F. A., and Kolpinski, M. C., 1967. Biological zonation related to groundwater discharge along the shore of Biscayne Bay, Miami, Florida: , Estuaries: Ecologies and Populations, 18, pp. 488-499.

Lara, R. J., and Dittmar, T., 1999. Nutrient dynamics in a mangrove creek (North Brazil) during the dry season. Mangroves and Salt Marshes 3: 185-195.

Littler, D. S.; Littler, M. M.; Bucher, K. E.; and Norris, J. N., 1989. Marine Plants of the Caribbean: Smithsonian Inst. Press, Wash. D. C., 263p.Meeder, J. F.; Alvord, J.; Byrns, M.; Ross, M. S.; Renshaw, A., 1997. Distribution of benthic nearshore communities and their relationship to groundwater nutrient loading: Final Report to Biscayne National Park, SERP, FIU, 41p. plus figures.

Orth, R. J., and Moore, K. A., 1983. Chesapeake Bay: An unprecedented decline in submerged aquatic vegetation. Science 222: 51-53.

Peligri, S. P., and Twilley, R. R., 1999. Heterotrophic nitrogen fixation (acetylene reduction) during leaf litter decomposition of two mangrove species in South Florida, USA. Marine Biology 131: 53-61.

Powell, G. V. N., Fourqurean, J. W., Kenworthy, W. J., Zieman, J. C., 1991. Bird colonies cause seagrass enrichment in a subtropical estuary: Observational and experimental evidence: Estuarine, Coastal and Shelf Science 32: 567-579.

Solorzano, L., and Sharp, J. H., 1980. Determination of total dissolved phosphorus and particulate phosphorus in natural waters. Limnology and Oceanography 25: 754-758.

Strickland, J. D. H., and Parsons, T. R., 1972. A practical handbook of seawater analysis. Bulletin of the Fisheries Research Board of Canada 167: 107-112.

Taylor, W. R., 1972. Marine Algae of the Eastern Tropical and Subtropical Coasts of the Americas: Univ. Mich. Press, Ann Arbor, 870p.

Thorhaug, A., 1976. The vascular plants of Biscayne Bay: in Biscayne Bay: Past/ Present/ Future; Univ. Miami Sea Grant Spec. Rpt. No. 5, pp. 95-102.

Woelkerling, W. J., 1976. South Florida Benthic Marine Algae: Sedimenta V, Comp. Sed. Lab, Univ. Miami, 148p.Table 1. Water quality variable statistics.

VARIABLE STA MEDIAN MIN. MAX. n Surface 10 0.20 0.02 1.00 12 Salinity 11 12.00 2.20 27.10 12

(psu) 12 11.91 1.40 29.10 12 13 7.80 0.20 26.10 12 14 22.40 5.30 37.50 8 15 26.45 19.20 39.70 12 16 5.00 0.70 23.40 3 17 3.30 3.30 3.30 1 Bottom 10 Salinity 11 20.10 12.40 37.20 11

(psu) 12 16.40 4.00 33.70 10 13 19.90 4.80 36.70 12 14 23.60 11.80 38.00 7 15 26.75 19.30 39.70 12 16 17 Surface 10 25.95 23.30 29.60 12 Temperature 11 25.90 21.40 30.40 12 ( o C) 12 24.80 23.40 31.60 11

13 25.95 21.90 30.40 12 14 25.45 21.40 30.70 8 15 25.35 20.90 31.50 12 16 22.05 22.00 22.10 2 17 21.80 21.70 21.90 2 Bottom 10 Temperature 11 24.10 20.90 29.80 10 ( o C) 12 25.05 22.90 28.50 10

13 25.25 23.30 31.20 12 14 23.80 21.40 30.70 7 15 25.35 21.00 31.50 12 16 17 Surface 10 5.70 1.10 8.10 12 Dissolved 11 4.75 1.10 6.80 12

Oxygen 12 3.80 0.40 5.90 11 (mg l -1 ) 13 4.95 1.00 7.30 12 14 5.30 2.70 11.20 8 15 6.90 3.80 8.10 12 16 3.50 1.90 5.10 2 17 3.35 2.30 4.40 2VARIABLE STA MEDIAN MIN. MAX. n Bottom 10 Dissolved 11 5.00 2.10 8.70 10

Oxygen 12 2.50 0.20 6.60 10 (mg l -1 ) 13 4.55 1.20 6.80 12 14 5.70 2.70 11.40 7 15 7.15 4.80 11.20 12 16 17 pH 10 7.815 7.397 8.229 11

11 7.860 7.109 8.370 11 12 7.800 6.900 8.590 11 13 7.870 7.100 8.350 11 14 8.120 7.300 8.463 7 15 8.370 6.971 8.780 9 16 7.985 7.500 8.303 4 17 8.074 7.854 8.500 4 Total 10 4.040 3.141 13.250 12 Organic 11 6.137 3.717 17.010 12 Carbon 12 8.663 4.797 26.358 12 (ppm) 13 6.540 3.813 9.611 12 14 6.512 4.974 10.102 9 15 4.990 3.626 7.947 11 16 11.471 5.274 16.337 4 17 18.503 6.899 27.450 3 NO 2 - 10 0.0070 0.0010 0.0290 12 (ppm) 11 0.0100 0.0020 0.0300 12 12 0.0280 0.0080 0.1030 12 13 0.0110 0.0020 0.0320 12 14 0.0040 0.0020 0.0280 9 15 0.0100 0.0010 0.0510 12 16 0.0050 0.0030 0.0350 4 17 0.0060 0.0040 0.0180 3 NO 3 -2 10 0.2020 0.0190 0.4120 12 (ppm) 11 0.1090 0.0090 0.4150 12 12 0.1230 0.0040 0.3870 12 13 0.1290 0.0140 0.3690 12 14 0.0950 0.0020 0.1950 9 15 0.0620 0.0000 0.3380 12 16 0.0410 0.0340 0.0820 4 17 0.0300 0.0020 0.0310 3VARIABLE STA MEDIAN MIN. MAX. n NH 4 + 10 0.0550 0.0170 0.3530 12 (ppm) 11 0.2190 0.0970 0.6720 12 12 3.2650 0.2220 26.9730 12 13 0.1760 0.1030 0.7520 12 14 0.2110 0.0110 0.5150 9 15 0.0420 0.0040 0.1350 12 16 0.1130 0.0790 0.4810 4 17 0.0470 0.0370 0.0480 3 NH 3 10 0.00 0.00 0.02 12 (ppb) 11 0.01 0.00 0.04 12 12 0.11 0.00 0.65 12 13 0.01 0.00 0.04 12 14 0.01 0.00 0.03 9 15 0.00 0.00 0.01 12 16 0.00 0.00 0.04 4 17 0.00 0.00 0.00 2 Soluble 10 0.0040 0.0010 0.3060 12 Reactive 11 0.0030 0.0000 0.0280 12 Phosphorus 12 0.0040 0.0010 0.1120 12 (ppm) 13 0.0030 0.0000 0.0190 12 14 0.0030 0.0000 0.0340 9 15 0.0020 0.0000 0.1370 12 16 0.0020 0.0002 0.0620 4 17 0.0030 0.0004 0.0060 3 Total 10 0.0110 0.0040 0.3230 11 Phosphorus 11 0.0100 0.0030 0.0420 11 (ppm) 12 0.0110 0.0020 0.0300 11 13 0.0080 0.0020 0.0150 10 14 0.0080 0.0040 0.0200 8 15 0.0050 0.0020 0.0170 11 16 0.0240 0.0060 0.9400 4 17 0.0120 0.0060 0.0140 3 Total 10 0.2970 0.2060 0.7020 12 Organic 11 0.3910 0.0860 0.6080 12 Nitrogen 12 0.0370 0.0240 0.8570 12

(ppm) 13 0.3180 0.1420 0.5890 12 14 0.3560 0.1320 1.2040 9 15 0.3270 0.1790 0.5370 12 16 0.5660 0.2790 1.4580 4 17 0.8470 0.3310 1.9860 3VARIABLE STA MEDIAN MIN. MAX. n Si(OH) 4 10 1.1840 1.1840 1.1840 2

(ppm) 11 0.6540 0.6540 0.6540 2 12 0.3370 0.3370 0.3370 2 13 0.7390 0.7390 0.7390 2 14 15 0.0780 0.0780 0.0780 2 16 17Table 2. List of benthic plant taxa.

BENTHIC PLANT SPECIES

ANGIOSPERMS Halodule wrightii Halophila engelmannii Ruppia maritma Syringodium filiforme Thalassia testudinum

CHLOROPHYTA Acetabularia crenulata Anadyomene stellata Avrainvillea nigricans Batophora oerstedia Caulerpa mexicana Caulerpa racemosa Caulerpa vertcillata Halimeda incrassata Halimeda opuntia Halimeda simulans Penicillus capitatus Rhipocephalus phoenix Udotea flabellum Ulva lactuca

PHAEOPHYTA Dictyota cf crenulata Rosenvingea sanctae-crusis Sargassum filipendula

RHODOPHYTA Acanthophora specifera Chondria littoralis Hypnea cornuta Hypoglossum involvens Laurencia intricataFigure 1. Map of Black Point Monitoring Program sampling sites in relation to FIU Biscayne Bay water quality monitoring program ( 

### + ) and South Florida ecosystem. -80.5 -80.4 -80.3 -80.2 -80.1 25.2 25.3 25.4 25.5 25.6 25.7 25.8 25.9 26.0

-82.0 -81.5 -81.0 -80.5 -80.0 25.0 25.5 26.0 26.5 27.0

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 2 5 .5 2 25.53 25.54 25.55

South Dade Sewage Treatment Facility
Control Gate

1 0

11 12 13

14 15

16

17 Black Point Goulds CanalFigure 2. Locations of Shoreline Ammonia Survey sites in relation to FIU Biscayne Bay water quality monitoring program and major canals. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75

Goulds Canal

Mowry Canal Military Canal Cutler ChannelFigure 3. Map of NH 4 + concentrations at landfill sites in Oct. 1998.

Figure 4. Map of NH 4 + concentrations at landfill sites in Nov. 1998.

Figure 5. Map of NH 4 + concentrations at landfill sites in Dec. 1998. -80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15 South Dade Sewage Treatment Facility
Control Gate

Oct. 1998 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13 15 South Dade Sewage Treatment Facility
Control Gate

Nov. 1998 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13 15 South Dade Sewage Treatment Facility
Control Gate

Dec. 1998 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00Figure 6. Map of NH 4 + concentrations at landfill sites in Jan. 1999.

Figure 7. Map of NH 4 + concentrations at landfill sites in Mar. 1999.

Figure 8. Map of NH 4 + concentrations at landfill sites in Apr. 1999. -80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15 South Dade Sewage Treatment Facility
Control Gate

Jan. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15

16 17 South Dade Sewage Treatment Facility
Control Gate

Mar. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 13

14 15 South Dade Sewage Treatment Facility
Control Gate

Apr. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00Figure 9. Map of NH 4 + concentrations at landfill sites in May 1999.

Figure 10. Map of NH 4 + concentrations at landfill sites in Jun. 1999.

Figure 11. Map of NH 4 + concentrations at landfill sites in Aug. 1999. -80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15 South Dade Sewage Treatment Facility
Control Gate

Jun. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00 -80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15

16 17 South Dade Sewage Treatment Facility
Control Gate

May 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15 South Dade Sewage Treatment Facility
Control Gate

Aug. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00Figure 12. Map of NH 4 + concentrations at landfill sites in Sep. 1999.

Figure 13. Map of NH 4 + concentrations at landfill sites in Oct. 1999.

Figure 14. Map of NH 4 + concentrations at landfill sites in Dec. 1999. -80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15

16 South Dade Sewage Treatment Facility
Control Gate

Sep. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13

14 15

16 17 South Dade Sewage Treatment Facility
Control Gate

Oct. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00

-80.35 -80.34 -80.33 -80.32 -80.31 -80.30 -80.29 25.52 25.53 25.54 25.55

10

11 12 13 15 South Dade Sewage Treatment Facility
Control Gate

Dec. 1999 NH4 (ppm)

0.00 to 0.01 0.01 to 0.10 0.10 to 1.00 1.00 to 10.00Figure 15. Box-and-whisker plots of water quality variables by station in the landfill canals. 0 5 10 15 20 25 30 35 40psu

10 11 12 13 14 15 0 5 10 15 20 25 30 35 40psu

10 11 12 13 14 15

21 22 23 24 25 26 27 28 29 30 31oC

10 11 12 13 14 15 21 22 23 24 25 26 27 28 29 30 31oC

10 11 12 13 14 15

0 2 4 6 8 10 12ppm

10 11 12 13 14 15 0 2 4 6 8 10 12ppm

10 11 12 13 14 15

6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00

10 11 12 13 14 15 0 2 4 6 8 10 12 14 16 18 20ppm

10 11 12 13 14 15 Surface Salinity

Surface Temp.

Surface DO

pH

Station Station DOC Bottom DO Bottom Temp. Bottom SalinityFigure 16. Box-and-whisker plots of water quality variables by station in the landfill canals. 0.0 1.0 2.0 3.0 4.0 5.0 6.0ppm

10 11 12 13 14 15 0.00 0.05 0.10 0.15 0.20 0.25 0.30ppb

10 11 12 13 14 15 NH 4 NH 3

0.00 0.02 0.04 0.06 0.08 0.10ppm

10 11 12 13 14 15 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40ppm

10 11 12 13 14 15

0.00 0.01 0.02 0.03ppm

10 11 12 13 14 15 0.00 0.01 0.02 0.03ppm

10 11 12 13 14 15

0.0 0.2 0.4 0.6 0.8 1.0ppm

10 11 12 13 14 15 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4ppm

10 11 12 13 14 15 NO 2 NO 3

SRP TP

TON Si(OH) 4

Station Station

# Station 11

Figure 17. Comparison of landfill water quality variables from 1994 and current study. 0 4 8 12 16 20 24 28PSU

93-94 98-99 22 23 24 25 26 27 28 29 30 31 32oC

93-94 98-99

1 2 3 4 5 6 7 8mg/l

93-94 98-99 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4pH

93-94 98-99

0.0 0.2 0.4 0.6 0.8 1.0ppm

93-94 98-99 0 5 10 15 20 25 30 35 40ppb

93-94 98-99

0.0 0.1 0.2 0.3 0.4 0.5ppm

93-94 98-99 0.000 0.010 0.020 0.030 0.040 0.050ppm

93-94 98-99 Salinity

Dissolved Oxygen Temperature

pH

Ammonium

Nitrate Ammonia (NH3)

Soluble Reactive Phosphorus

# Station 12

Figure 18. Comparison of landfill water quality variables from 1994 and current study. 0 4 8 12 16 20 24 28PSU

93-94 98-99 22 23 24 25 26 27 28 29 30 31 32oC

93-94 98-99

0 1 2 3 4 5 6mg/l

93-94 98-99 6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4

93-94 98-99

0 5 10 15 20 25 30 35ppm

93-94 98-99 0 100 200 300 400 500ppb

93-94 98-99

0.0 0.1 0.2 0.3 0.4 0.5ppm

93-94 98-99 0.00 0.01 0.02 0.03 0.04 0.05ppm

93-94 98-99 Salinity

Dissolved Oxygen Temperature

pH

Ammonium

Nitrate Ammonia (NH3)

Soluble Reactive Phosphorus

# Station 13

Figure 19. Comparison of landfill water quality variables from 1994 and current study. 0 2 4 6 8 10 12 14 16 18 20 22 24 26PSU

93-94 98-99 22 23 24 25 26 27 28 29 30 31 32oC

93-94 98-99

1 2 3 4 5 6 7 8mg/l

93-94 98-99 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4pH

93-94 98-99

0.0 0.2 0.4 0.6 0.8 1.0ppm

93-94 98-99 0 5 10 15 20 25 30 35 40ppb

93-94 98-99

0.0 0.1 0.2 0.3 0.4 0.5ppm

93-94 98-99 0.000 0.010 0.020 0.030 0.040 0.050ppm

93-94 98-99 Salinity

Dissolved Oxygen Temperature

pH

Ammonium

Nitrate Ammonia (NH3)

Soluble Reactive Phosphorus

# Station 15

18 20 22 24 26 28 30 32 34 36PSU

93-94 98-99 20 21 22 23 24 25 26 27 28 29 30 31 32oC

93-94 98-99

4.0 5.0 6.0 7.0 8.0 9.0mg/l

93-94 98-99 7.0 7.5 8.0 8.5 9.0pH

93-94 98-99

0.0 0.1 0.2 0.3 0.4 0.5ppm

93-94 98-99 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0ppb

93-94 98-99

0.0 0.1 0.2 0.3 0.4 0.5ppm

93-94 98-99 0.000 0.010 0.020 0.030 0.040 0.050ppm

93-94 98-99 Salinity

Dissolved Oxygen Temperature

pH

Ammonium

Nitrate Ammonia (NH3)

Soluble Reactive Phosphorus

Figure 20. Comparison of landfill water quality variables from 1994 and current study.Figure 21. Salinity data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note hypersaline conditions in the south below Military Canal. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



# 36 37 38 39 40 41 42 

# Salinity (ppt)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 22. Ammonium data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note strong source in and around the Goulds Canal/Black Point area. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



## 0.000 0.004 0.008 0.012 0.016 0.020 0.024 

# Ammonium (ppm)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 23. Unionized ammonia data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note slightly higher concentrations around the Cutler Canal, Goulds Canal/Black Point area, and Fender Point. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



# 0.0 1.0 2.0 3.0 4.0 5.0 

# Ammonia (NH3-ppb)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 24. Nitrate data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note strong source from the Cutler Canal. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



## 0.000 0.002 0.004 0.006 0.008 0.010 

# Nitrate (ppm)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 25. Total Phosphorus data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note elevated concentrations around Mangrove Key. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



## 0.000 0.010 0.020 0.030 0.040 0.050 

# Total Phosphorus (ppm)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 26. Total organic carbon data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note elevated inshore concentrations occurring from Cutler Canal to Mowry Canal. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



## 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 

# Total Organic Carbon (ppm)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 27. Total organic nitrogen data from combined Shoreline Ammonia Survey and April 1999 FIU Biscayne Bay water quality monitoring program. Note highest concentrations were found inshore between Goulds and Military Canals. 

### -80.40 -80.35 -80.30 -80.25 -80.20 -80.15 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75



## 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 

# Total Organic Nitrogen (ppm)

Goulds Canal

Mowry Canal Military Canal Cutler Channel 

## April 1999Figure 28. Plot of NH 4 + in water and sediments along Shoreline Nutrient Survey sites.

Figure 29. Plot of TP in water and sediments along Shoreline Nutrient Survey sites. 

### Ammonium

0.001 0.010 0.100 1.000

25.35 25.40 25.45 25.50 25.55 25.60 25.65 Latitude (N to S)ppm

water column sediment Cutler Goulds Military Mowry



### Total Phosphorus

0.000 0.001 0.010 0.100 1.000

25.35 25.40 25.45 25.50 25.55 25.60 25.65 Latitude (N to S)ppm

water column sediment Cutler Goulds Military MowryFigure 30. Plot of plant species distribution along Shoreline Benthic Survey sites.

Figure 31. Plot of Thalassia vs salinity along Shoreline Benthic Survey sites. 0 1 2 3 4 5 6

25.35 25.40 25.45 25.50 25.55 25.60 25.65 Latitude (N to S)Density

34 36 38 40 42 44 46psu Thalassia Salinity Cutler Goulds Military Mowry Species Density

0 1 2 3 4 5 6 7 8 9 10Thalassia Latitude (N to S)Braun-Blanquet Unknown Brown Algae
Acetabularia
Other Greens

Halodule Red Algae

Penicillus
Thalassia Cutler Goulds Military MowryFigure 32. Plot of Thalassia vs NH 4 + along Shoreline Benthic Survey sites. 0 1 2 3 4 5 6

25.35 25.40 25.45 25.50 25.55 25.60 25.65 Latitude (N to S)Density

0.00 0.01 0.02 0.03 0.04ppm Thalassia NH4 Cutler Goulds Military MowryFigure 33. Plots of water quality variables from the Mangrove Transect Surveys. Sites are distribution canal (DC) near Military Canal, adjacent mangrove fringe (CF), offshore CF (CBB), mangrove fringe near Mowry (TF), and offshore TF (TBB). 0.0 0.2 0.4 0.6 0.8 1.0 1.2ppm

CBB CF DC TBB TF 0.0 0.2 0.4 0.6 0.8 1.0 1.2ppm

CBB CF DC TBB TF

0.00 0.05 0.10 0.15 0.20ppm

CBB CF DC TBB TF 0.00 0.02 0.04 0.06 0.08 0.10ppm

CBB CF DC TBB TF

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0μg/l

CBB CF DC TBB TF 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0ppm

CBB CF DC TBB TF NO 2 +NO 3 NH 4

SRP TP

Chl a TOC

Station Station