[INDIAN RIVER LAGOON NATIONAL ESTUARY PROGRAM]

Transcription

1 2013 The Balmoral Institute and RWParkinson [INDIAN RIVER LAGOON NATIONAL ESTUARY PROGRAM Prioritizing Total Maximumm Daily Loads (TMDLs) Using Habitat Vulnerability to Sea Level Rise M]

2 Table of Contents Executive Summary... 1 Introduction... 3 Scope of Work... 4 Task 1- Statement of Task (IRL basin model)... 4 Description of Methods... 4 Results... 4 Application towards project goal... 5 Task 2- Statement of Task (seagrass coverage)... 6 Task 2a... 6 Task 2b... 6 Description of Methods... 6 Task 2a... 6 Task 2b... 6 Task 3- Statement of Task (Sea level rise) Description of Methods Results Discussion Summary of Work and Significant Findings Concluding Remarks References Appendix and Restored Parameters i

3 Table of Figures Figure 1. Task 1 - IRL Basin Model... 5 Figure 2. Task 1 - Segments and Associated 2009 Habitat Distribution... 5 Figure 3. Lagoon Region Labels... 7 Figure 4. Task 2a - Coverage Figure 5. Task 2b - Historical Restored Figure 6. BR3-5: Gains After +6 ft SLR Figure 7. BR3-5: Lost After +6 ft SLR Figure 8. BR3-5: Net Change in After +6 ft SLR Figure 9. Ending 2009 After 6ft Sea Level Rise (Lagoon-Wide) Figure 10. Ending 2009 After 6ft Sea Level Rise (Northern Lagoon) Figure 11. Ending 2009 After 6ft Sea Level Rise (Central Lagoon) Figure Sea Level Rise Response (Northern Lagoon) Figure Sea Level Rise Response (Central Lagoon) Figure 14. Ending TMDL 1 After 6ft Sea Level Rise (Lagoon-Wide) Figure 15. Ending TMDL 1 After 6ft Sea Level Rise (Northern Lagoon) Figure 16. Ending TMDL 1 After 6ft Sea Level Rise (Central Lagoon) Figure 17. Ending TMDL 2 After 6ft Sea Level Rise (Lagoon-Wide) Figure 18. Ending TMDL 2 After 6ft Sea Level Rise (Northern Lagoon) Figure 19. Ending TMDL 2 After 6ft Sea Level Rise (Central Lagoon) Figure 20. Ending Restored After 6ft Sea Level Rise (Lagoon-Wide) Figure 21. Ending Restored After 6ft Sea Level Rise (Northern Lagoon) Figure 22. Ending Restored After 6ft Sea Level Rise (Central Lagoon) Figure 23. Restored Sea Level Rise Response (Northern Lagoon) Figure 24. Restored Sea Level Rise Response (Central Lagoon) Figure 25. Lagoon-wide Area (Change from Starting Condition to Ending Restored) Figure 26. Lagoon-wide Fragmentation Index (Change from Starting Condition to Ending Restored) List of Tables Table 1. Estimated Median Depth Limit... 7 Table 2. Starting Conditions: and Restored... 9 Table 3. Segment MDLs Used to Model Four Starting Conditions Table 4. Statistics Summarizing Segment Table 5. Lagoon-Wide: Sea Level Rise Response Table 6. Coverage After +1 ft to +6 ft SLR Table 7. TMDL 1 Coverage After +1 ft to +6 ft SLR Table 8. TMDL 2 Coverage After +1 ft to +6 ft SLR Table 9. Restored Coverage After +1 ft to +6 ft SLR ii

4 Executive Summary This report describes findings of analysis that have been performed to quantify the potential impacts of climate change on Lagoon (IRL) seagrass habitat. The study was performed specifically to evaluate how locally relevant changes in water quality targets, as established through the TMDL (Total Maximum Daily Loads) process, might be affected by projected climate change. Basin Management Action Plans, or BMAPS, have developed detailed strategies for each lagoon segment in order to achieve TMDL targets. An expectation of the BMAPs is that as lagoon water quality improves, seagrass habitat will begin expanding onto adjacent barren substrate and into deeper water. Climate change is expected to affect the growth of seagrass in each lagoon segment, which in turn is likely to affect the success of BMAP strategies.. Realistic assessment of the resources that are required to ensure timely and successful implementation of BMAPs dictates that some prioritization will be necessary. Evaluating the potential impacts of sea level rise on seagrass outcomes is one aspect of the lagoon s health that can support this prioritization. Based on Army Corps projections, up to 6ft of sea level rise is expected to impact the Indian River Lagoon. Because each lagoon segment has different bathymetric features, the impacts will vary throughoutt the lagoon system. GIS analysis was performed to assess the impacts of sea level rise at 1 foot increments, up to six feet, using a bathtub model i.e., existing lagoon shorelinee boundaries were assumed static throughout. Four scenarios were completed. The analysis was first conducted using the recent seagrass habitat maps provided by the St. Johns Water Management District (District) and based uponn 2009 aerial photos. Historic seagrass coveragee was also acquired from the District (c.f. Steward et al., 2005). These maps servee as a proxy for a fully restored lagoon condition. Finally, two interim thresholdss were assessed, (TMDL 1 and TMDL 2 ) reflecting achievement of 15% aqndd 60% of the proposed TMDL targets for water quality, respectively (c.f. Florida Department of Environmental Protection, 2013). The areaa analyzed in this study included the Northern Indian River Lagoon and Central Indian River Lagoon to segment IR 21. The analysis finds that overall seagrass habitatt coverage in the study area declines by 75% relative to recent conditions after 6 feet of sea level rise (SLR). Using assumptions of improved water quality under the TMDL 1 and TMDL 2 scenarios, a 70% reduction in seagrass habitat is forecast to accompany a SLR off +6 ft. Finally, under fully restored conditions, a SLR of +6 ft will result in a 60% decline in the coverage of seagrass habitat throughout the study area; again relative to recent conditions. However, the effect of improved water quality via TMDL reductions on IRL seagrass coverage sustainability is even more evident under lower SLRR scenarios. For example, under fully restored conditions, a +4 ft SLR yields no net loss of seagrass coverage relative to its recent coverage. The lagoon segments vary widely in their response to sea level rise, with losses varying from 34% to 100% of recent coverage. Givenn this study is based upon a bathtub Final Report 1

5 model, the resilience of IRL seagrass Coverage under conditions of rising sea level is underestimated, suggesting future research should include a dynamic shoreline and the potential for upland seagrass migration. Final Report 2

6 Introduction The successful restoration of the Indian River Lagoonn (IRL) estuarine ecosystem is strongly dependent upon: (a) the protection of existing seagrass habitat (aka recent) and (b) re growth in barren deeper areas to its ecological compensation depth (aka restored). To achieve these management goals, locally relevant water quality targets or Total Maximum Daily Loads (TMDLs) have been developed throughout the IRL basinn in association with Basin Management Action Plans (BMAPs). Each BMAP also provides a detailed strategy to achieve the TMDLs. As lagoon water quality improves, seagrass habitat will begin expanding onto adjacent barren substrate and into deeper water. Althoughh the IRL BMAPs include strategiess to achievee TMDLs in each of the sub basinss and segments therein, it is unlikely sufficient resources can be brought to bear to ensure their timely and successful implementation everywhere theyy are needed. Prioritizing the allocation of available management resources to ensure the success of TMDLs in restoring water quality and thus seagrass cover is a primary objective of this project. This report describes findings of analysis that were performed with the goal of providing a more complete basiss for management resource allocation. The following technical process was followed: A model of the IRL basin was constructed using existing shoreline, bathymetric, geographic and physiographic data; coverage was validated and modeled (a) as mapped in 2009 (aka recent habitat coverage) and (b) associated with the successful re growth to its ecological compensation depths (aka restored habitat coverage); Changes in seagrass coverage as a function of sea level rise (SLR) to the year 2100 were modeled, with and without the effects of TMDL reductionss as proposed in association with the implementationn of the IRL BMAP. This report serves as the Final Project Report. Findingss have been assessed and are described herein for use by IRL stakeholders, to facilitate the successful implementation of IRL BMAPs and related research. The geographic information system (GIS) data prepared as part of this analysis has been delivered to the IRL National Estuaryy Program, accompanied by a technical memorandum explaining its construction and use, as well as metadata, attribute tables and supporting referencee materials including literature citations. Final Report 3

7 Scope of Work Task 1 Statement of Task (IRL basin model) In accordance with Task 1, the Balmoral Institute (TBI) constructed a model using existing shoreline, bathymetric, geographic and physiographic data. of the IRL basin Description of Methods In accordance with the Task 1 directive, The Balmoral Institute (TBI) constructed a GIS model of the IRL basin using existing shoreline, bathymetric, geographic and physiographic data. The data layers and associated maps assembled during this task weree to provide the foundation upon which the subsequent tasks for this study were to be completed. GIS technical background A model of the IRL basin District (District). The model depicts 2008 bathymetry, shoreline location, seagrass segments (after Stewart et al. 2005) and regional geographic/physiographic data. was constructed using data provided by the St. Johns River Water Management These layers and the corresponding metadata were to be altered to meet the project objectives and the requirement ts of subsequent task deliverables. The GIS processing yielded polygons for the spatial extent of various segments, as well as polygons within each for the depth (bathymetry and adjoining topography above sea level).. Challenges encountered Challenges included isolating and removing slivers smaller than 0.2 acres and assigning mean water depths to dissolved polygons. The latter requiredd affirmation by District engineers of the conversion of NAVD88 values to the MWL within the model, while ensuring that the elevations providedd balanced inflows and outflows at all inlets. The segments Mosquitoo Lagoon 1 and 2 were combined into one segment. Metadata Metadata was previously provided for all shapefiles submitted to the District. In Task 1, the shorelinee and bathymetric shapefiles were revised to model the IRL basin. Results The IRL basin model, or base map, is shown in Figure 1. The model depicts 2 shorelinee location, and regional geographic/physiographic data. These corresponding metadata were altered to meet the project objectives of deliverables bathym layers and subsequent metry, the task Final Report 4

8 Figure 1. Task 1 - IRL Basin Model Application towards project goal Maps and associated data layers assembled during this task provided the foundation which subsequent tasks were completed. In preparation for Task 2, recent 2009 and seagrass coverage was acquired from the District (Figuree 2). Figure 2. Task 1 - Segments and Associated 2009 Habitat Distribution upon 2011 Note: 2009 coverage in pink, 2011 in yellow. Final Report 5

9 Task 2 Statement of Task (seagrass coverage) ) Task 2a In accordance with Task 2a, TBI created a layer using 2009 seagrass coverage as most recently mapped. Task 2b For Task 2b, TBI layered restored seagrass coverage associated with the successful re growth to its ecological compensation depths. Description of Methods Task 2a habitat maps constructed by the District from 2011 dataa document their diminished distribution due to a reduction in water clarity. This reduction was triggered by a chlorophyll bloom that occurred after the 2009 data was acquired. As a result, the 2011 data was not used for this analysis; the 2009 data was deemed most representative off recent conditions. The 2009 data was used to map recent seagrass segments. Task 2b The restored seagrass coveragee was utilized as a proxy for effects of improved water quality conditions included by a successful TMDL reduction program as describedd in the recently published BMAPs (c.f. Florida Department of Environmental Protection, 2013). The union of historical data provided by the District ( Combined Coverage ) was used model this starting condition. Restored segments were processed and mapped in GIS. GIS technical background GIS processing included assigning the median depth limit (MDL) by segment (Steward et al 2005) to each polygon, adding region information too match the Industrial Economics 2011 report areas, and calculation of summary statistics for comparison of ecological indicators, including fragmentation indices such as edgee to interior ratios. The MDLs established by the District were compared too the values calculated from Task 2 data. Overall, the distribution of values across test segments approximately matched the District medians (Table 1). As a result, the District MDL values were applied to the recent and restored segments in GIS. Final Report 6

10 Table 1. Estimated Median Depth Limit Segment ID MDLL (MWL MDL Adjusted) Mosquitoo Lagoon ML1 ML3 4 Banana River Lagoon BR1 2 BR7 Northern Indian River Lagoon IR1 3 IR9 11 Central Indian River Lagoon IR12 13A IR Source: SJRWMD (MDL), TBI (MDL adjusted) Note: MDL is median depth limit, MWL is mean water level MDL Restored MDL (MWL Adjusted) Each segment was also manually assigned regional labels based on the Industrial Economics (2011) categories. The analysis regions (lagoon name) and sub regions (designated letter) are shown in Figure 3. After preliminary calculations, digital slivers were determined to be the cause of inconsistent fragmentation values. To remedy this, a decision rule was employed based on the total area of seagrass bed. If the bed was less than 0.2 acres, it was determined to be a sliver, and was removed from the dataset. The restored seagrass coverage data, which spanned five decades, also required a similar treatment Summary statistics were calculated for the recent and restored data by segment after clean up. Challenges encountered Some seagrass bed polygons in the 2009 data did not have segment labels. In order to assign the missing labels, the recent seagrass was overlaid with the restored data. Labels were then manually assigned by location. Figure 3. Lagoon Region Labels Final Report 7

11 Metadata Metadata for all shapefiles was submitted to the District. In Task 2a and 2b, two new shapefiles were created to model recent and restored seagrass distribution. Results Descriptive statistics for area, perimeter, and fragmentation indicess were calculated recent and seagrass distribution (Table 2). Final Report 8

12 Table 2. Starting Conditions: and Restored Segment All Segments Northern Indiann River Lagoon Mosquito Lagoon ML1 ML2 ML3 4 Banana River Lagoon BR1 2 BR3 5 BR6 BR7 Indian River Lagoon IR1 3 IR4 IR5 IR6 7 IR8 Central Indian River Lagoon IR9 11 IR12 13A IR13B IR14 15 IR16 20 IR21 Total Patch Area (ha) 33,953 28,268 8, ,385 6,445 9,549 4,932 3,255 1, ,169 4, ,431 2, ,685 1, , Restored Mean Fragmentation Index Total Patch Area (ha) 28,761 24,702 6, ,694 4,958 9,635 4,975 4, ,444 3, ,218 1, , , Mean Fragmentation Index Final Report 9

13 (2009) The Task 2a deliverable map (Figure 4) shows recent seagrass coverage as mapped in 2009 by the District. Figure 4. Task 2a - Coveragee 10

14 Restored Task 2b deliverable (Figure 5) shows seagrass coverage associated with the successful re growth to its restored ecological compensation depth ass mapped by the District. Figure 5. Task 2b - Historical Restored 11

15 Task 3 Statement of Task (Sea level rise) Quantify changes in recent and restored seagrass coverage as a function of SLR to the year Description of Methods The recent seagrass data was further processed in GIS to calculate the effects of SLR. coveragee for 2009 as mapped in Task 2a, along with thee existing shoreline and bathymetric data from Task 1 were used. GIS technical background GIS processing was used to iteratively adjust bathymetry contourss for one foot increments in SLR. The methodology addressed additional area gainedd due to increases in the water depth of very shallow areas; and areas of loss in deeper areas where indcreaswing water depth created conditions in which seagrass was no longer likely to survive. The parameters used to complete the analysis were based on the MDL for each lagoon segment. habitat was considered viable if these depths were within 1 standard deviation of the segmend MDL (i.e., MDL+ +1SD; Steward, 2005); conversely, consistent with the bathtub model assumption, the minimum depth, or shoreline, was held at zero. coverage outside of these limits were deemed unlikely in that segment, and were removed. and restored lagoon segments with a difference in MDL of less than 1 foot weree not modeledd using the two TMDL scenarios; as the net effects of a 15% and 60% MDL increase were found to be immaterial. Table 3 shows the starting conditions for TMDL 1 and TMDL 2 at 15% and 60% of the difference between the restored and recent seagrass, respectively. Sliver clean up was employed to limit measurement error. Statistical analysis was completed to assess changes resulting from the processing. Among other items, apparent errors in the bathymetric data and linear patches that appeared to be remnants of historical dredging activities were managed by removing areas less thann 0.2 acres. The latter tended to occur where clear anthropogenic influences were present. 12

16 Table 3. Segment MDLs Used to Model Four Starting Conditions Segment ID Mosquito Lagoon ML1 ML2 ML3 4 Banana River Lagoon BR1 2 BR3 5 BR6 BR7 Northern Indian River Lagoon IR1 3 IR4 IR5 IR6 7 IR8 IR9 11 Central Indian River Lagoon IR12 13A IR13B IR14 15 IR16 20 IR Starting Condition MDL TMDL 1 15% Increase in Depth TMDL 2 60% Increase in Depth Restored (100%) Challenges encountered Several challenges were identified during processing. During processing, bathymetryy was determined to be missing in some areas covered by seagrass polygons. Because bathymetry contours were used for the one foot increment processing, some small slivers of actual seagrass were omitted. Unavoidable minor losses due to bathymetryy measurement errors are embedded in the results. In three segments (BR6, BR7 8, and IR6 7), bathymetry covered developed land. Manual correction to limit bathymetry to outside the shoreline was performed. Finally, some segments were realigned by the Districtt between the mapping of the restored data and the recent data. The area of some segments was reassigned to other segments; this 13

17 change was most dramatic in BR3 5 and IR21. In BR3 5, about three quarters of the area historically considered BR6 was reassigned to BR3 5. This resulted in BR3 5 having a largerr area in the recent seagrass when compared to the restoredd data. The modification in IR21 didd not drastically change the amount of area, but the reassignment is still worth nothing as it shifted the segment south. Maps detailing the restored andd recent seagrass are provided in the appendix. Metadata In Task 3, six new shapefiles were created to model a one to six foot incremental rise in sea level. Metadata and associated shapefiles were submitted to the district. Results and restored seagrass as mapped in Task 2 were used to complete Task 3, Figures 6 8 show the gains, losses and net change of example segment BR3 5 after recent coverage is subject to a +1 ft to +6 ft SLR. habitat area was gained along the shallow water boundary if the adjusted bathymetry reflected, after each one foot increment, the creation of new habitat suitable for grass colonization (Figure 6). was lost when the bathymetry along a deep water edge exceeded the segment MDL+ +1SD (Figuree 7). Figure 8 shows the net change after a +6 ft SLR. gains and losses were combined so that final summary statistics could be calculated. Table 4 includes the recent and restored, SLR statistics for example segment BR3 5. The process was repeated at the imputed depths for TMDL reductions at 15% and 60%. Summary statistics for each of these scenarios are provided in Table 4. Maps displaying changes in seagrass coveragee are shown in Figures Detailed SLR results for all IRL segments are providedd in the Discussion section. Figure 25 shows the total seagrass habitatt area after a 6 ft SLR associated each of the four initial (or starting) conditions. Figure 26 shows the corresponding change in seagrass habitat fragmentation. 14

18 Figure 6. BR3-5: Gains After +1 ft to +6 ft SLR 6 15

19 Figure 7. BR3-5: Lost After +1ft to +6 ft SLR 7 16

20 Figure 8. BR3-5: Net Change in After +6 ft SLR 8 17

21 Table 4. Statistics Summarizing Segment BR3-5: Response to +1 ft too +6 ft SLR Segment: BR3 5 Condition: Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentation Index (Edge to Interior Ratio) Segment: BR3 5 Condition: TMDL 1 Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentation Index (Edge to Interior Ratio) Segment: BR3 5 Condition: TMDL 2 Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentation Index (Edge to Interior Ratio) Segment: BR3 5 Condition: Restored Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentation Index (Edge to Interior Ratio) , , , , , , , , , , TMDL , , , , , , , , , , TMDL , , , , , , , , , , , Restored +1ft TMDL 1 +1ft TMDL 2 +1ft Restored +1ft +2ft TMDL 1 +2ft TMDL 2 +2ft Restoredd +2ft +3ft TMDL 1 +3ft TMDL 2 +3ft Restored +3ft +4ft TMDL 1 +4ft TMDL 2 +4ft Restored +4ft +5ft TMDL 1 +5ft TMDL 2 +5ft Restored +5ft +6ft TMDL 1 +6ft TMDL 2 +6ft Restored +6ft , , , , , , , , ,

22 Figure 9. Ending 2009 After 6ft Sea Level Rise (Lagoon-Wide) 9 19

23 Figure 10. Ending 2009 After 6ft Sea Level Rise (Northern Lagoon) 10 20

24 Figure 11. Ending 2009 After 6ft Sea Level Rise (Central Lagoon) 11 21

25 Figure Sea Level Rise Response (Northern Lagoon) 12 22

26 Figure Sea Level Rise Response (Central Lagoon) 13 23

27 Figure 14. Ending TMDL 1 After 6ft Sea Level Rise (Lagoon-Wide) 14 24

28 Figure 15. Ending TMDL 1 s After 6ft Sea Level Rise (Northern Lagoon) 15 25

29 Figure 16. Ending TMDL 1 After 6ft Sea Level Rise (Central Lagoon) 16 26

30 Figure 17. Ending TMDL 2 After 6ft Sea Level Rise (Lagoon-Wide) 17 27

31 Figure 18. Ending TMDL 2 s After 6ft Sea Level Rise (Northern Lagoon) 18 28

32 Figure 19. Ending TMDL 2 After 6ft Sea Level Rise (Central Lagoon) 19 29

33 Figure 20. Ending Restored After 6ft Sea Level Rise (Lagoon-Wide) 20 30

34 Figure 21. Ending Restored After 6ft Sea Level Rise (Northern Lagoon) 21 31

35 Figure 22. Ending Restored After 6ft Sea Level Rise (Central Lagoon) 22 32

36 Figure 23. Restored Sea Level Rise Response (Northern Lagoon) 23 33

37 Figure 24. Restored Sea Level Rise Response (Central Lagoon) 24 34

38 Table 5. Lagoon-Wide: Sea Level Rise Response Segment: Lagoon Wide t t t Condition: +1ft +2ft +3ft +4ft +5ft +6ft Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) 2.4 4, , , , , , , , , , , , , , Segment: Lagoon Wide TMDL 1 TMDL 1 TMDL 1 TMDL 1 TMDL 1 TMDL 1 TMDL 1 Condition: TMDL 1 +1ft +2ft +3ft +4ft +5ft +6ft Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , , , , , , , , , , , , , , Segment: Lagoon Wide TMDL 2 TMDL 2 TMDL 2 TMDL 2 TMDL 2 TMDL 2 TMDL 2 Condition: TMDL 2 +1ft +2ft +3ft +4ft +5ft +6ft Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: Lagoon Wide Condition: Restored 7, , , , , , , , , , , , , , Restored Restored Restored Restored Restored +1ft +2ft +3ft +4ft Restored Restored +5ft +6ft Mean Bed Perimeter (km) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , , , , , , , , , , , , , ,

39 Figure 25. Lagoon-wide Area (Change from Starting Condition to Ending Restored) Figure 26. Lagoon-wide Fragmentation Index (Change from Starting Condition to Ending Restored) 36

40 Discussion Summary of Work and Significant Findings The findings suggest that SLR will have a significant effect on the IRL seagrass coverage. The impacts vary significantly by lagoon segment due to differences in bathymetry. Generally speaking, compared to recent conditions, most segments experience net gains in seagrass coverage in shallow water areas during the early stages of SLR. However, these gains are negated beyond a +2 ft SLR. Exceptions include Segments BR-1-2 and BR-6, wherein bathymetryy allowed for slight gains even after +4 ft SLR as both have substantial areas of shallow bathymetry and relatively deep MDLs. At +6 ft SLR, all segments experience substantial loss of seagrass coverage. Segment ML-1 loses 100% of its seagrass habitat; ML 3-4 losess the most in absolute area: 4,948 hectares. Both are among the shallowest in the lagoon system, as measured their initial MDL; thee effects of increased depth quickly drown out any temporary gains in viable habitatt area. However, the effect of improved water quality viaa TMDL reductions on IRL seagrass habitat sustainabil lity is evident under lower SLR scenarios. For example, under fully restored conditions, a +4 ft SLR yields no net loss of seagrass habitat relative to its recent coverage. 37

41 Table 6. Coverage After +1 ft to +6 ft SLR Segment BR1 2 BR3 5 BR6 BR7 IR1 3 IR12 13A IR13B IR14 15 IR16 20 IR21 IR4 IR5 IR6 7 IR8 IR9 11 ML1 ML2 ML3 4 4,975 4, ,462 A , ,218 1, ,694 4,958 +1ft 7,125 6, ,571 1, ,788 1,944 1, ,803 3, , ,732 5,599 +2ft 6,830 5, ,416 1, ,109 1, ,701 2, ,646 4,859 Bed Area (ha) t +3ft +4ft +5ft +6ft 6,117 5,331 4,183 3,255 3,901 2,995 1, ,415 3,4644 1, , , ,286 1,932 1, ,945 1, ,514 2,290 1, ,918 1, Table 7. TMDL 1 Coverage After +1 ft to +6 ft SLR Segment BR3 5 IR1 3 IR4 IR9 11 ML1 ML3 4 TMDL 1 7,500 8, ,314 1,038 6,326 TMDL 1 +1ft 6,504 8, ,047 1,003 5,783 Total Bed Area (ha) TMDL 1 +2ft 5,393 5, ,157 TMDL 1 +3ft 4,191 4, ,607 TMDL 1 +4ft 3,347 3, ,786 TMDL 1 +5ft 2,140 2, TMDL 1 +6ft 912 1,

42 Table 8. TMDL 2 Coverage After +1 ft to +6 ft SLR Segment BR3 5 IR1 3 IR4 IR9 11 ML1 ML3 4 TMDL 2 7,787 8, ,070 4,958 TMDL 2 +1ft 6,872 8, ,581 1,051 6,632 Total Bed Area (ha) TMDL 2 +2ft 5,786 6, ,135 1,028 5,978 TMDL 2 +3ft 4,574 4, ,402 TMDL 2 +4ft 3,640 3, ,397 TMDL 2 +5ft 2,613 2, ,283 TMDL 2 +6ft 1,183 1, Table 9. Restored Coverage After +1 ft to +6 ft SLR Segment BR1 2 BR3 5 BR6 BR7 IR1 3 IR12 13A IR13B IR14 15 IR16 20 IR21 IR4 IR5 IR6 7 IR8 IR9 11 ML1 ML2 ML3 4 Restored 4,932 3,255 1, ,924 A , ,431 2, , ,385 6,445 Restored +1ft 7,146 5,655 1, ,533 1, ,305 1, ,307 3, ,406 1,400 2,024 7,255 Total Bed Area (ha)) Restored +2ft 6,965 4,635 1, , ,542 1, ,380 2, ,061 1,359 1,971 6,641 Restored +3ft 6,407 3,668 1, , , ,668 1, ,313 1,913 5,975 Restored +4ft 5,5755 2, , , ,280 1, ,2411 1,849 4,349 Restored +5ft 4,741 2, , , ,164 1,774 1,937 Restored +6ft 3,894 1, , , ,

43 Concluding Remarks As noted, the bathtub model used in this analysis constrains the shorelinee at the existing boundary. Adjacent land may be available that would accommodate migration of seagrass beds inland. Future modeling efforts that take into accountt areas of undeveloped or natural lands will provide more realistic results on which to base management decisions. Data used for this project required reliance on shapefiles for bathymetry contours and seagrass bed polygons. Measurement error is inherent in the bathymetry contours. For future modeling, integration of digital elevation models may improve thee accuracy and precision of seagrasss bed polygons, and in turn the statistics generated therefrom. Finally, large algal blooms since 2009 have caused dramatic loss off seagrass habitat in the IRL. At the time of project commencement, the 2011 algal bloom was considered a one time event. Given recent events, other conditions in addition to recent habitat area may warrant additional modeling. 40

44 References Florida Department of Environmental Protection Basin Management Action Plan for the Implementation of Total Maximum Daily Loads for Nutrients in the Indian River Lagoon Basin/North Indian River Lagoon. Industrial Economics, Inc. March The Impacts of sea level rise to the Indian River Lagoon Estuary (Florida): an application of ecologic and economic models. Final Report. Steward, J., Virnstein, R., Morris, L., and Lowe, E Setting seagrass depth, coverage, and light targets for the Indian River Lagoon System, Florida. Estuaries, 28(6):

45 Appendix and Restored Parameters Segment: ML1 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: ML2 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: ML3 4 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , , , Restored Restored , , Restored , , Change Change Change , , % Change 206% 185% 1874% 155% 511% 2224% 343% 1256% 25% % Change 52% 201% 154% 49% 551% 131% 70% 18% 22% % Change 85% 155% 14% 390% 379% 30% 755% 30% 18% 42

46 Segment: IR1 3 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR4 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR5 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , , Restored , , Restored 6 Change , , Change , , Restored , , Change % Change 84% 119% 33% 175% 232% 135% 815% 42% 12% % Change 25% 45% 74% 57% 54% 87% 111% 58% 17% % Change 61% 33% 58% 12% 194% 12% 178% 10% 46% 43

47 Segment: BR1 2 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: BR3 5 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR6 7 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , , Restored , , Change , , Restored , Change , Restored Change , , % Change 18% 23% 6% 24% 101% 6% 21% 1% 47% % Change 40% 64% 44% 16% 110% 54% 21% 27% 28% % Change 3% 3% 7% 5% 35% 61% 26% 30% 7% 44

48 Segment: IR8 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: BR6 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: BR7 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Restored Change Restored , , Change , , Restored Change % Change 0% 0% 99% 16% 0% 121% 10% 10% 1% % Change 40% 3% 680% 370% 40% 2431% 2026% 1175% 1% % Change 63% 1% 6% 3% 27% 20% 13% 84% 0% 45

49 Segment: IR9 11 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR12 13A Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR13B Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Restored Change , Restored Restored Change Change % Change 29% 38% 352% 33% 34% 508% 143% 213% 42% % Change 21% 47% 8% 7% 74% 61% 10% 13% 59% % Change 15% 1% 140% 21% 32% 195% 52% 29% 22% 46

50 Segment: IR14 15 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Segment: IR16 20 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) , Restored , Restored Change Change % Change 44% 89% 44% 69% 240% 50% 145% 38% 8% % Change 46% 125% 132% 69% 336% 98% 87% 2% 7% Segment: IR21 Number of Beds (Count) Minimumm Bed Perimeter (km) Maximum Bed Perimeter (km) Mean Bed Perimeter (km) Minimumm Bed Area ( ha) Maximum Bed Area (ha) Mean Bed Area (ha) Total Bed Area (ha) Mean Fragmentationn Index (Edge to Interior Ratio) Restored Change % Change 26% 18% 19% 11% 31% 19% 36% 1% 30% 47