2007 South Florida Environmental Report Appendix 12-3



# Appendix 12-3: Report on Algae Blooms in Eastern Florida Bay and Southern Biscayne Bay

NOTE : This document is provided through the permission of its authors as an appendix to the 2007 SFER – Volume I. It appears in its original format and content and ha s not been edited or reviewed by

the SFER Production Team.

App. 12-3-1_____________________________________________________________________________________________ * This report was originally published on July 28, 2006. Following peer review as part of the 2007 South Florida Environmental Report , minor changes were incorporated in this updated version. It should be noted that this version only incorporates some minor revisions and does not includ e an update of information collected after July 2006. Report on Algal Blooms in Eastern Flor ida Bay and Southern Biscayne Bay

November 20, 2006*

David Rudnick, Christopher Madden, Stephe n Kelly, Robin Bennett, and Kevin Cunniff Coastal Ecosystems Divisi on and Everglades Division South Florida Water Management District

SUMMARY

A highly unusual algal bloom has persisted in ea stern Florida Bay and s outhern Biscayne Bay (Manatee Bay, Barnes Sound, and Card Sound) since at least November 2005. Similar algal

blooms have been observed in central and western Florida Bay, but not in eastern Florida Bay. Chlorophyll a concentrations (an indicator of the amount of algae in the water column) peaked in the fall and early winter in 2005 and after decreasing in the spring, increased again in June and July 2006. These concentrations greatly exceeded values recorded during fifteen years of water quality monitoring in this regi on (SFWMD/FIU Coastal Water Qu ality Monitoring Program). A summary timeline of water quality changes in a ssociation with other events (U.S. Highway 1 construction, hurricanes, canal disc harges) is presented in Table 1.

The algal bloom has been found to be mostly co mposed of cyanobacteria (blue-green algae), which are photosynthetic bacteria. The dominant species of blue-green algae in the eastern Florida Bay / southern Biscayne Bay bloom is also the typical domina nt species in central Florida Bay blooms, which have been common since 1991.

Causes of the bloom are not certain, but may be re lated to at least two f actors: 1) disturbance

associated road construction activity along U.S. Highway 1 be tween the Florida mainland and Key Largo (Eighteen Mile Stretch), and 2) hur ricane impacts from August through October 2005 (Katrina, Rita, Wilma). Highway constructi on has entailed the cutt ing and mulching of mangrove trees and soil tilling (mixing fresh mulch into the peat soil) and soil stabilization with injection of cement since May 2005. Hurricane disturbances include d a large discharge of fresh water and phosphorus from the C-111 canal and the impact of high winds, waves, storm surge, and abrupt salinity change on plants, soils, sedi ments, and ground water. The proximity of the blooms to both sides of U.S. Highway 1 – an ar ea where blooms have not been previously recorded – points to the likelihood that the unique disturbance of road construction is involved as a cause of the bloom. A summary of hypotheses regarding the caus e of the blooms is presented

in Table 2.

Monitoring results indicate that the bloom was most likely initiated by a large increase in total phosphorus (TP) – a sharp peak in TP concentrati ons (to record high valu es) was measured in a small area (Manatee Bay) in late August immediately following Hurricane Katrina and also in the large region of eastern Florida Bay and southe rn Biscayne Bay in October. The highest P and chlorophyll a concentrations were in basins closes t to the Eighteen Mile Stretch near KeyFlorida Bay Algal Bloom Report – Page 2

Largo. However, some lower, but elevated TP concentrations were also observed at the same time in areas remote from the road. The timing of the TP peak and subsequent bloom appears

more associated with hurricane activity, with the regional TP peak occurring after Hurricane Rita. Despite major road construction activity during the late spring and through the summer, no blooms or unusually high TP was measur ed prior to Hurricane Katrina. Thus, while the spatial pattern of the bloom points toward the importan ce of road disturbance as a cause of the blooms, the timing of these blooms points toward hurricane disturbance as a cause. An interaction of these two factors (distu rbance from road construction plus hu rricanes) appears to be the likely cause of the blooms.

One component of the hurricane effects may ha ve been associated with water management operations. A major runoff event occurred in late August 2005 in association with high rainfall

from Hurricane Katrina. This re sulted in a large loading of TP into Manatee Bay from the C-111 Canal along with a lower quantity of TP loadi ng into Florida Bay through the southeastern Everglades. After this runoff event, TP concen trations in Manatee Ba y sharply increased and then returned to near pre-storm concentrations within one week. TP in Barnes Sound and all Florida Bay waters remained low for more than on e month before peaking regionally in October. This one-month time lag, along with the absence of a concentration gradient away from Manatee Bay, indicates that the widespread October peak wa s unlikely to be caused by canal inputs. It is more likely that storm surge transported sediments, seagrasses, organic matter (perhaps including materials from the U.S. 1 worksite), and ground wate r nutrients. Furthermore, when the TP peak did occur, those areas with low salinity (associ ated with the most runoff) had lower TP than those areas with higher sa linity. Similar discharges of water and TP into Manatee Bay in the 1990s did not result in algal blooms similar to those observed between November 2005 and

March 2006.Florida Bay Algal Bloom Report – Page 3

Table 1. Timeline of Florida Bay & Biscayne Ba y algal bloom and potentially associated events.

WATER QUALITY IN

NORTHEAST FL BAY – S. BISC

BAY REGION U.S. HIGHWAY 1

ACTIVITIES TROPICAL

STORM

EVENTS C-111 CANAL

DISCHARGE

Apr

2005 N o change from historic baseline (low

chl a with median 0.4 ppb, and TP with median 6 ppb) M angrove clearing begins near Jewfish

Creek May N o change 0.6 miles cleared N of

Jewfish Creek

June N o change Clearing continues N and S of Lk Surprise S197 open, 7,000 ac-ft discharge
July N o change Clearing to Barnes; mixing of soil, mangrove mulch, and cement begins Aug A fter Katrina, rapid salinity drop, TP increase (84 ppb) in Manatee Clearing and soil mixing continues N (Barnes Sound area) H urricane Katrina (high rainfall, runoff, 47 mph wind, 2 ft surge) S197 opens 8/26(5 d; 27,000 acft; P load 0.8 metric tons)

Sept T P near baseline in region, chl a increase in Manatee and Barnes (7 to 16 ppb) Clearing and soil mixing continues N (Barnes Sound area) H urricane Rita (38 mph wind, 2 ft surge) S197 open for 3 periods (20 d; 21,000 ac-ft)

Oct H igh TP in region (60 to 100 ppb) before Wilma; chl a still low except Manatee and Barnes (6 ppb) Clearing and soil mixing continues N (Barnes Sound area) H urr. Wilma (66 mph wind, 2 to 3 ft surge) S197 opens for 2 periods (10 d; 2,000 ac-ft)

Nov R egional chl a increase (bloom in Blackwater and Barnes to 15 ppb); TP decrease (slightly > baseline) Clearing to Manatee Bay marina; soil mixing continues N

Dec B loom continues – highest in Barnes (near 10 ppb) Soil mixing S of Lk Surprise

Jan

2006 B loom increases – mapping shows highest chl a near US1 and Key Largo (peak 20 ppb), high turbidity M angroves cleared near Manatee Bay

Feb B loom continues – chl a decrease (< 12 ppb in Blackwater, Barnes, Manatee) Soil mixing near

Barnes Sound

Mar B loom continues – chl a decrease (3 to 12 ppb in Blackwater, Barnes, Manatee) Soil mixing near

Barnes Sound

Apr B loom continues - chl a less than 10 ppb in Blackwater, Barnes, Manatee Soil mixing near Manatee Bay

May

Jun July B loom dec r ease in early May (chl a < 6 ppb); increase in June–July (> 12 ppb in Blackwater, Barnes, Manatee) to be determinedFlorida Bay Algal Bloom Report – Page 4

Table 2. Hypotheses that may explai n the cause of 2005-2006 algal blooms.

HYPOTHESIS EVIDENCE SUPPORTING EVIDENCE REFUTING U.S. Highway 1 road

construction • No similar algal bloom known to occur in the region prior to road

construction

• Bloom spatial pattern bracketshighway (especially BlackwaterBarnes)

• Bloom sustained at least 9 months after hurricane events, while

construction continued

• Mangrove mulch decomposition and soil disturbance likely to yield large nutrient release to adjacent waters • Five months of construction activity before start of bloom

• Bloom started immediately after

Hurricane Katrina and Rita

• Bloom spatial pattern within basins adjacent to road do not show increasing chlorophyll a near road

Hurricane Katrina related discharge and P load through S-197 (C-111 Canal) • High P load event occurred and primary production known to be P

limited

• Bloom began in Manatee Bay and Barnes Sound immediately after pulse discharge and measured TP increase in Bay • Elevated TP observed in areas beyond (west of) influence of S-197 discharge

• Regional TP peak occurred one

month after TP decreased to near baseline in Manatee Bay

• TP load associated with particles – bloom does not follow gradient from canal mouth; chlorophyll a concentrations higher near Key Largo than mainland

• Similar blooms did not occur

after similar C-111 releases and TP loads (even after late 1980s – early 1990s drought) Hurricane wind, waves, surge eroded sediment & plants, stripped leaves, pulsed ground water

nutrients • P increase after Katrina and Rita; regional bloom after Wilma

• Spatial pattern of highest chlorophyll a appears parallel to Key Largo coastline, as could occur with line of storm deposits or ground water pulse • Regional TP increase occurred prior to storm with highest surge (Wilma)

• No similar blooms after previous storms (e.g. Hurricane Georges)

Hurricane disturbance: salinity drop & seagrass • Salinity drop near coast with Katrina rapid enough to kill plants • Salinity drop also occurred in

areas with little TP increase and

no bloom

Combination of road

and hurricane

disturbance • Storm energy could move nutrients from road fill - turbidity barriers next to U.S. 1 removed prior to storms

• Spatial pattern of bloom follows road for 9 months, while bloom initiation timing follows hurricanesFlorida Bay Algal Bloom Report – Page 5

TECHNICAL FINDINGS

Phytoplankton Bloom Description

Eastern Florida Bay and southern Biscayne Bay (Barnes Sound, Manatee Bay, and Card Sound) (Figure 1) typically have low phytoplankton (mic roalgae in the water co lumn) biomass and low productivity, in large part because of low phosphorus availability. The SFWMD/FIU Coastal Water Quality Monitoring program has docum ented water quality conditions since March 1991 and found that chlorophyll- a concentrations, an indicator of phytoplankton biomass, are typically (have a median value) near 0.4 μ g/l (equivalent to ppb) and rarely exceed 2 μ g/L in eastern Florida Bay and southern Biscayne Ba y. Total phosphorus (TP) concentrations are most commonly 0.006 mg/L (6 ppb) and rarely exceed 0.02 mg/L (20 ppb) in this region. In the fall of 2005, however, chlorophyll- a and TP concentrations greatly exceeded these values (Figures 2, 3), with the blooms reaching 8 μ g/L chlorophyll- a and TP reaching near 0.1 mg/L (100 ppb), as measured in the SFWMD/FIU program, and up to 20 μ g/L chlorophyll- a as measured at different sites and times by SFWMD staff and Miami-Dade DERM staff.

Initiation of the bloom occurred in Mana tee Bay and Barnes Sound in September 2005 (Figure 4). For about one month following Hu rricane Katrina, Miami-Dade DERM frequently sampled these basins to assess S-197 rele ase effects. On September 14, chlorophyll- a increased

to 16 μ g/L in Barnes Sound and 7 μ g/L in Manatee Bay. By October 5, chlorophyll- a decreased

to between 2 and 6 μ g/L in these basins (measured by DERM and FIU) and increased to 2 μ g/L in Blackwater Sound. By November, the bloom had intensified, with concentrations near

10 μ g/L in waters adjacent to the U.S. Highway 1 near Key Largo (Figure 5). Furthermore, the area of the bloom expanded away from its center in Blackwater Sound, Barnes Sound, and Manatee Bay toward eastern Florida Bay a nd Card Sound (with decreasing chlorophyll- a concentrations toward the east, west, and north ). The bloom persiste d in this region through February 2006, but decreased c onsiderably in March (Figure 5). Recent results show a resurgence of the bloom in June and July 2006 (Figure 4).

In January, April, May, and July 2006, SFWMD scientists analyzed the fine-scale spatial pattern of the bloom, using the Dataflow multi-parame ter mapping system, which includes a chlorophyll fluorometer. The high-resolution map of chlorophyll- a distribution (Figures 6-9) derived from Dataflow transects (with a data point collected every 5 seconds from a moving boat) indicates two spatial trends. First, chlorophyll- a concentrations were higher in basins immediately east and west of U.S. Highway 1 than farther east (Card Sound) and west (into Florida Bay proper), confirming the general spatial pattern derived from the small set of fixed stations in the water quality monitoring network. After April, the bloom in eastern Florida Bay was largely limited to basins adjacent the Highway (Blackwater S ound, Little Blackwater Sound, Long Sound). Second, chlorophyll- a concentrations were higher toward Key Largo than toward the mainland during January, May, and July (April data were insufficient to detect this). Chlorophyll- a concentrations were consistently greater than 20 μ g/L in Lake Surprise.Florida Bay Algal Bloom Report – Page 6

Plankton samples were taken in January by SFWMD for analysis of the taxonomic composition of the bloom by scientists at FAU and the Florida Fish and Wildlife Resear ch Institute (FWRI). Dr. Cindy Heil at FWRI found that the samples c ontained a mixture of ta xa, dominated by very small organisms (<2 μ m), which were mostly cyanobacteria (blue-green algae). Species were primarily in genus Synechocystis and Synechococcus (several species, including elongatus ) and smaller unidentified cyanophyte species. Some smaller diatom species and flagellates were detected, but were rare. The dominance of cy anobacteria was confirmed by Dr. William Louda of FAU by pigment analysis, with 86% of sample s containing nearly all cyanobacterial pigments

that were similar to Synechococcous elongatus

.

SFWMD scientists also confirmed that the plankton composing the bloom were photosynthetically active. Changes in dissolved oxygen (DO) were measured in March 2006 to estimate productivity in a bloom area in Blackwater Sound (with about 12.5 μ g/L) and in northeastern Florida Bay near Duck Key (with about 11.9 μ g/L), and in a non-bloom area about one hundred meters beyond the edge of th e bloom near Duck Key (with about 0.6 μ g/L). Gross primary productivity in the bloo m areas was high, with about 0.15 mg O 2 L -1 h -1 (roughly 0.5 g C m -2 d -1 ) in Blackwater Sound and northeastern Fl orida Bay, and near zero (about 0.01 mg

O 2 L -1 h -1 ) in the adjacent non-bloom area. Previous measurements of net primary production in this region have found rates similar to that measured in the non-bloom area in March.

Hurricane disturbance and the bloom rel ationship with phosphorus and salinity

Three hurricanes impacted south Florida from A ugust through October 2005 – Katrina, Rita, and Wilma (Figure 10). Katrina was notable in s outh Florida for its hi gh rainfall and runoff, resulting in a rapid decrease in sa linity in south Florida estuaries, particularly close to the coast (Figure 11). Rainfall during Ka trina also caused the opening of S-197 to lower stages in the C-111 Canal, yielding the discharge of canal water and associated materials (including TP) from the C-111 Canal into Manatee Bay in late Augus t and early September (Figure 12). Wilma was notable for its strong winds and storm surge, wh ich exceeded those of any 2005 hurricane in the Florida Bay region (Figure 13).

A relationship between TP inputs from Katrina- related canal discharges and the algal bloom appears likely in Manatee Bay. One day after Hurricane Katrina, which passed through south Florida on August 26 with high rainfall, and the discharge of C-111 water through S-197,

TP concentrations in Manat ee Bay increased to 84 ppb (DER M data). By August 30, TP concentrations had dropped to a bout 12 ppb. By September 14, chlorophyll- a increased to

7 μ g /L in Manatee Bay and 16 μ g /L in Barnes Sound, far above previously recorded values.

With the exception of the late August peak in TP in Manatee Bay, TP concentrations remained low in the region until earl y October and chlorophyll- a concentrations in the region (other than in Manatee Bay and Barnes Sound) remained low until November (Figure 5).

The spatial pattern of TP concen tration in October 2005 (Figure 14) was similar to that of the phytoplankton bloom (Figure 5), w ith highest concentrations in Barnes Sound and Blackwater Sound and decreasing concentrations toward the east, west, and north. These TP concentrationsFlorida Bay Algal Bloom Report – Page 7

were far higher than previously measured in th is region (Figures 2, 3), with concentrations as high as 60 ppb at Duck Key. Changes in TP spa tial pattern through the fall and winter showed a rapid decrease in conc entration throughout the region after October and a slight shift in the gradient, with more uniform concentrations in a north-south direction. Concentrations remained above historic values, with thes e elevated values bracketing U. S. Highway 1. An exception to this pattern occurred in January, when the cente r of the high TP concentration area was further west in Florida Bay.

The temporal relationship of chlorophyll- a , TP, and salinity at three sites within the bloom area is shown in Figure 15. These figures clearly sh ow that the TP peak in October 2005 preceded the sharp increase in chlorophyll- a at all stations and that chlorophyll- a remained low through the spring and summer months, a period during whic h considerable road construction occurred along U.S. Highway 1 between Blackwater Sound and Barnes Sound. The magnitude of the phytoplankton bloom at a given site in Nove mber 2005 was strongly correlated with TP

concentrations at the site in Oc tober (Figure 16). This finding is consistent with the expectation that primary producers in this region are str ongly limited by P availability. P concentrations dropped after the formation of the strong bloom , but chlorophyll and TP remained tightly correlated (Figure 16).

Figure 15 also shows the drop in salinity associated with Hurrican e Katrina in August 2005, which is most evident at the Barnes Sound site, occurred without a concurrent increase in TP. The TP peak occurred about one month after the freshwater pu lse. Salinity and peak TP concentrations were not strongl y correlated in October 2005 (Fi gure 17) and the slight positive slope of this relationship shows that TP was not higher in areas with lower salinity, which received more P inputs from the C-111 Canal and th e Everglades than areas with higher salinity.

Causes of Phytoplankton Blooms

The results presented here are correlative and do not prove cause-and- effect relationships. However, these results do point toward the pote ntial importance of U.S. Highway 1 construction

and hurricane disturbance as fact ors stimulating the phytoplankton bl oom. Inputs of TP from the C-111 Canal following Hurricane Katrina also may have contributed to the bloom.

Highway construction

. The spatial distribution of the bloom and extremely high TP con centrations corresponded with the vicinity of the highway, with elevated chlorophyll and TP on both sides of the highway (Figures 5-9, 14). Based on these spatial patterns and the chronology of bloom events (Figure 15), it appears that the proximate cause of the bloom was elevated TP. Highway construction potentially released P (along with ot her nutrients) via two mechanisms: 1) extensive cutting and mulching of mangrove trees along the Highway, and 2) soil disturbance, perhaps including the use of materials a dded to the soil to stabilize the roadway. The process of mixing fresh organic matter (mangrove mulch) into the peat soil likely resulted in a short-term release of porewater nutrients and a long-term release of decomposition products, including inorganic and organic nutrients. While turb idity barriers were employed duri ng construction, this would not stop the loss of soluble decomposition products (leachates) from mulched organic matter, whichFlorida Bay Algal Bloom Report – Page 8

commonly constitutes about 30% of organic matter loss from mangrove leaves. Furthermore, these barriers were removed in preparation for hurricane onslaught and an unknown amount of material was lost from the site during Hurricanes Katrina, Rita, and Wilma. No major erosion was noted at the site (personal communications with John Palenchar [from FDOT] and Heather Carman [from SFWMD]).

However, the timing of the TP peak and bloom ar e not consistent with the hypothesis that road construction alone caused the phyt oplankton bloom. Mangrove cl earing began in April 2005 and proceeded throughout the remainder of the spri ng and summer months (personal communication J. Palenchar). Soil stabilization, with extensiv e soil disturbance, began in June 2005. Based on observations of H. Carman, the rate of tree and soil disturbance appeared to be fairly even through these months. The absence of elevated P or chlorophyll from May through September indicates that nutrient inputs from the construction area were not su fficient to stimulate blooms. It should be noted that a study of mangrove le af decomposition in northeastern Florida Bay (Davis et al. 2003) found initial P loss via leaching during the fi rst three weeks of decomposition, but strong P retention over the next year. If mangrove mulch remained at the construction site, P retention would also be expected.

Hurricane disturbance The timing of the P peak points toward the possib ility that Hurricanes Katrina and Rita played a role in the incidence of elevated P and phytopl ankton blooms. Hurricane Katrina impacted the area on August 26 with winds up to about 45 mph (recorded at the SFWMD weather station in Joe Bay) and Hurricane Rita impacted the area on September 20 with winds up to about 37 mph at this station (Figure 10). Hurricane Wilma impacted the area on October 24 with higher winds – 64 mph at Joe Bay. The direct effect of wind ma y have been secondary to that of fresh water runoff (especially during Katrina) and storm su rge (especially during Wilma) (Figure 13).

The October 2005 peak in TP was observed in samples collected on October 6, between Hurricanes Rita and Wilma. The high TP values cannot be attributed to suspended sediments or low DO at monitoring stations at the time of TP sampling; both turbid ity and DO were near typical values at the time of sampling. Howe ver, sediments, porewater, ground water under the Florida Bay and Biscayne Bay and the Keys, and seagrass beds that were disturbed during the weeks between sampling times (September 6 to Octobe r 6) may have been sources of elevated P. It should be noted that although the highest TP values were found near U.S. Highway 1, lower peaks (that were nevertheless near or above record levels) occurred on October 6 throughout eastern Florida Bay and southern Biscayne Bay, ev en at sites such as Li ttle Madeira Bay, which is more than 10 miles away from the highw ay. Rapid salinity changes during and after Hurricane Katrina (Figure 11) in coastal embaymen ts such as Joe Bay and in coastal wetlands, including rapid salinity increases from stor m surge and a rapid salinity drops from the subsequent runoff event, may have killed plants a nd resulted in a time-lagged nutrient release.

An interactive effect of highway and hurricane disturbance? Despite the widespread disturbance of the re gion by hurricane events, perhaps indicated by elevated P throughout the eastern Florida Bay and southern Biscayne Bay, elevated chlorophyll- a levels in this region persisted (through July 2006) only in wa ters adjacent to U.S. Highway 1. This finding, combined with the timing of P and chlorophyll increases,Florida Bay Algal Bloom Report – Page 9

indicates that the bloom may have been caused by a combination of both Highway and hurricane disturbance. It is possible that soil and mangrove mulch and associated nutrients along the Highway were mobilized by storm surge and local r unoff, concentrating nutrients in portions of basins and coves near the Highway.

Fresh water discharge One major attribute of Hurricane Katrina in s outh Florida was high rain fall and fresh water runoff. This runoff not only affects salinity cond itions in coastal waters, but also can be a

mechanism for increased nutrien t loading. In August 2005, approximately 0.8 metric tons of P was released into Manatee Bay from the C-111 Ca nal through structure S-197 in association with hurricane runoff (Fig. 12). The calculation of this relatively high P load (the highest monthly value at this site) in August 2005 was mostly a ttributable to a single TP grab sample (with a concentration of 116 ppb) at S-197 on August 27. Much of this P may have been associated with sediment particles; total suspended solids in the C-111 Canal at S-197 we re extremely high (15 mg/L) in the August 27 grab sample.

The fate of P that entered Manatee Bay through S-197 is unknown. While TP concentrations in Manatee Bay were very high for two days fo llowing Hurricane Katrina, they were 12 ppb by September 1. It is likely that much of the P i nput to Manatee Bay during Katrina was associated with particles that settled to the bottom of the Ba y and thus was not measured in water samples. It is highly unlikely that the regional peak in TP in Oct ober could be explained by the

distribution of TP derived from the Katrina discharge. If this were the case, concentrations would most likely have had a grad ient from being high at the sour ce (near Manatee Bay) to being lower with distance from the source; this clearl y was not the case, with higher concentrations toward Key Largo. The greater than one-month la g between Katrina and the regional TP peak in October also argues against the C-111 canal being the main source of this TP.

It should be noted that seven pulse water and nutrient releases from C-111, similar to what

occurred with Hurricane Katrin a, also occurred between 1991 (when the SFWMD/FIU water quality monitoring program began) and 2000 (Figure 12). None of these earlier releases resulted in large phytoplankton blooms similar to thos e observed from November 2005 to March 2006.

Phosphorus may also have been transported ove r the banks of the C-111 canal toward Florida Bay through the southeastern Everglades by stor m runoff. While TP concentrations in the

wetland south of the canal never rose above 18 ppb and almost all values remained below 8 ppb (SFWMD/FIU data), USGS has estimated that about 0.2 MT of TP was loaded into Long Sound from West Highway Creek during Sept ember 2005. While inputs were much higher from the C-111 canal, inputs from natural creeks along the northeast Florida Bay and southern Biscayne Bay coast may also have contributed to the bloom. Creek inputs, however, had a low TP concentration (< 6 ppb) and cannot expl ain much higher concentrations in the bay.

This evidence, combined with the absence of a negative relationship be tween salinity and TP concentration (Figure 10) indicates that P a ssociated with fresh water discharges during Hurricane Katrina was not a likely source for the P peak that was observed in the entire region (including Florida Bay), especially when the limited hydrodynamic connection of the Biscayne Bay and Florida Bay systems is considered.Florida Bay Algal Bloom Report – Page 10

Acknowledgements We thank the many scientists and managers wh o contributed information and ideas to the original draft of this re port, as well as review and contribu tions to this revised draft. In particular, we thank Joe Boyer (Florida Intern ational University), Steve Blair (Miami-Dade DERM), Susan Markley (Miami-Dade DERM), Chris Kelble (NOAA-AOML), Mark Zucker (USGS), Jeff Woods (USGS), Cindy He il (FFWCC-FWRI), Bill Louda (Florida Atlantic University), Doug Morrison (NPS - Everglades National Park), Sarah Bellmund (NPS – Biscayne Bay National Park), Teresa Coley (SFWMD), John Palenchar (FDOT), Jay Marshall (SFWMD), and Heather Carman (SFWMD).

References

Davis, S.E., C. Coronado-Molina, D.L. Childers, and J.W. Day. 2003. Temporally dependent C, N, and P dynamics associated with the decay of Rhizophora mangle L. leaf litter in oligotrophic mangrove wetlands of the southern Everglades. Aquatic Botany 75:199-215.Florida Bay Algal Bloom Report – Page 11Florida Bay Algal Bloom Report – Page 12Florida Bay Algal Bloom Report – Page 13Florida Bay Algal Bloom Report – Page 14Florida Bay Algal Bloom Report – Page 15Florida Bay Algal Bloom Report – Page 16

Figure 6. High resolution map of chlorophyll fluo rescence (preliminary estimate) in eastern Florida Bay and southern Biscayne Bay, January 24-26, 2006. Map from high density Dataflow boat tracks (black lin e) throughout the mapped region.



## January 2006 – Chlorophyll- a ( μ g /L)

Provisional data (c madden@sfwmd.gov)Florida Bay Algal Bloom Report – Page 17

Figure 7. High resolution map of chlorophyll fluo rescence (preliminary estimate) in eastern Florida Bay and southern Biscayne Bay, April 11, 2006. Map from high-density Dataflow boat tracks (black line) throughout the mapped re gion, except for north of

southern Barnes Sound and Blackwater Sound, where rough conditions prevented analysis. Strong easterly winds existed during this survey.



## April 2006 – Chlorophyll- a ( μ g /L)

Provisional data (c madden@sfwmd.gov)Florida Bay Algal Bloom Report – Page 18

Figure 8. High resolution map of chlorophyll fluo rescence (preliminary estimate) in eastern Florida Bay and southern Biscayne Bay, May 25-26, 2006. Map from high-density Dataflow boat tracks (black lin e) throughout the mapped region.



## May 2006 – Chlorophyll- a ( μ g /L)

Provisional data (c madden@sfwmd.gov)Florida Bay Algal Bloom Report – Page 19

Figure 9. High resolution map of chlorophyll fluo rescence (preliminary estimate) in eastern Florida Bay and southern Biscayne Bay, July 19-20, 2006. Map from high-density Dataflow boat tracks (black lin e) throughout the mapped region.



## July 2006 – Chlorophyll- a ( μ g /L)

Provisional data (c madden@sfwmd.gov)Florida Bay Algal Bloom Report – Page 20Florida Bay Algal Bloom Report – Page 21Florida Bay Algal Bloom Report – Page 22Florida Bay Algal Bloom Report – Page 23Florida Bay Algal Bloom Report – Page 24Florida Bay Algal Bloom Report – Page 25Florida Bay Algal Bloom Report – Page 26Florida Bay Algal Bloom Report – Page 27