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projects > characterizing past and present mangrove shorelines to aid conservation of the smalltooth sawfish, Pristis pectinata, along the southwest coast of florida > proposal

Project Proposal

Characterizing Past and Present Mangrove Shorelines to Aid Conservation of the Smalltooth Sawfish, Pristis pectinata, Along the Southwest Coast of Florida

by Thomas J. Smith, III, Ph.D.1 and G. Tiling, Cert. GIS Specialist2

1U.S. Geological Survey, Florida Integrated Science Center, 600 Fourth Street, South, St. Petersburg, FL 33701 Phone: 727-803-8747, FAX: 727-803-2030, Email: Tom_J_Smith@usgs.gov

2Jacobs Technology, Inc., c/o USGS, 600 Fourth Street, South, St. Petersburg, FL 33701 Phone: 727-803-8747, FAX: 727-803-2030, Email: gtiling@usgs.gov

Background

Historically, the smalltooth sawfish (Pristis pectinata) was reported from Texas to New York. Hundreds of sightings of this fish have been documented on the east and west coasts of Florida since the late 1800s (Sietz and Poulakis 2002). Sawfish habitat is considered to be inshore, shallow sandbars, sea grass beds, and shallow muddy shorelines with adjacent mangroves (Carlson et al. 2007). Mangrove shorelines are felt to be especially important for sawfish pups, those individuals <2.0 m in length. Sawfish populations have been declining for some time. This may be the result of bycatch, habitat loss, and / or pollution (Sietz and Poulakis 2006, Carlson et al. 2007). The species has been placed on the Federal Endangered Species list (NMFS 2003). Many questions concerning the biology and ecology of this endangered species remain to be answered. One of the more important questions centers on habitat use and selectivity by juvenile sawfish.

Goals / Questions / Objectives

This pilot project has several related goals concerning a specific type of habitat thought to be important for juvenile sawfish habitat: mangrove shorelines. First, we will delineate and classify historic mangrove shorelines. Second, we will map and classify current mangrove shorelines. Third, we will determine amounts of shoreline change. Lastly, we will conduct an analysis to compare sawfish sightings and / or captures with the type of shoreline where those sightings-captures occurred. This will allow us to answer the question: Are juvenile sawfish selecting for a specific type of mangrove shoreline, and if so, what type of mangrove shoreline is it?

Methods

Study areas

Due to the vast amount of mangrove shoreline in southwest Florida, its entirety cannot be examined in this pilot project. We propose to examine three areas within southwest Florida where Pristis pectinata has been found (based on the sighting and capture data-set provided by the National Oceanic and Atmospheric Administration). From north to south along the coast these will be: the lower Caloosahatachee River and Matlacha Pass (Fig. 1); the 10,000 Islands from Goodland to Fakahatchee Bay, including the lower Faka-Union Canal (Fig. 2); and, from Lostmans River to Shark River in Everglades National Park (Fig. 3). These three areas have differing mixes of mangrove shoreline types and thus present an excellent opportunity to examine utilization of shorelines by sawfish. More importantly, they comprise a gradient of human impacts on shorelines, with greatest modification to shorelines in the Caloosahatchee and least in the Lostmans - Shark Rivers.

composite image of 2004 orthophotographs of the lower Caloosahatchee River and Matlacha Pass depicting the potential study area boundary
Figure 1. The lower Caloosahatchee River and Matlacha Pass are shown in this composite image of 2004 ortho-photographs. The yellow line depicts a potential boundary for the area to be studied. The scale is approximately 1:250,000. [larger image]


composite image of 2004 orthophotographs of 10,000 Islands from Goodland, Florida to Fakahatchee Bay depicting the potential study area boundary
Figure 2. The 10,000 Islands from Goodland, Florida (left) to Fakahatchee Bay (right) are shown in this composite image of 2004 ortho-photographs. The yellow line depicts a potential boundary for the area to be studied. The red DOQQ in the center, bottom is a 1999 color-infrared image. This small part of the study area was not flown in 2004. The scale is approximately 1:150,000. [larger image]


composite image of 2004 orthophotographs of the southwest coast of Everglades National Park from Lostmans River to Shark River depicting the potential study area boundary
Figure 3. The southwest coast of Everglades National Park from the Lostmans River to the Shark River is shown in this composite image of 2004 ortho-photographs. The yellow line depicts a potential boundary for the area to be studied. The scale is approximately 1:150,000. [larger image]

Available geo-data layers

Recent (2004) Digital Orthographic Quarter Quadrangles (DOQQs) are available from the Florida Department of Environmental Protection's Land-Boundary Information System (http://data.labins.org/2003/index.cfm) and are already in-hand at the USGS Geographic Information System lab in St. Petersburg. Photos from 1940 are available for use for parts of southwest Florida (Smith et al. 2002a). They will be obtained for other areas as needed (e.g. the lower Caloosahatchee River and Matlacha Pass). Unfortunately, the entire coast was not flown in 1940 and some areas of interest (lower Lostmans and Shark Rivers) were not covered. However, the entire coast was photographed in 1928 and the Topographic Sheets that were produced are available for use (Smith et al. 2002b) and copies of many of the original photographs are in hand. The in-hand materials from 1928 and 1940 have already been georeferenced and are ready for use.

Shoreline classification scheme

Shorelines will be classified using a hierarchical scheme, much like those used for vegetation classifications (e.g. Rutchey et. al. 2006). In such a scheme, the highest level represents the broadest class, for example, forest versus grassland. The next lower level might be oak versus pine, and the next lower level might be density, with pine savannah (low) versus pine forest High). For this work, we will use natural versus impacted as the highest level of classification (Fig. 4). The second level will be vegetated versus un-vegetated, and the third level will be depth (shallow vs deep) (Fig. 4). The first level differentiates all natural shorelines from created shorelines, be they dredged channels, dredge spoil islands, or hard-walled canals. The second level is primarily intended to separate mangroves from beaches. The third level gets at an additional factor that sawfish may be selecting for: depth. The classification scheme can be easily modified after the PIs receive input from the Sawfish Recovery Team.

Classifier Examples
Level 1: Natural - Impacted Undisturbed - Dredge Spoil
Level 2: Vegetated - Non Vegetated Mangrove - Sand
Level 3: Shallow - Deep Mangroves adjacent to mudflats vs mangroves adjacent to a channel
Figure 4. A potential hierarchical classification scheme for shorelines is shown.

Past and present shorelines and shoreline change

The frequency distribution of shoreline types will be determined using the following method. Random points within the three study areas will be generated using ArcGIS. The nearest shoreline to each point will be located and then classified using the scheme above. The location of each classified shoreline point will be recorded and a shape-file of classified points will be developed. This procedure will be repeated three times for each study area and for each year (1940 and 2004). The number of random points will be from 50 to 100.

By replicating the sampling we will be able to estimate a mean and standard deviation for the percentages. We will use contingency table analysis (Fienberg 1977) to test for significant differences in shorelines between areas and years using the S-Plus statistical package (Insightful 2001).

All geographic analyses and maps will be completed using the ArcGIS software package. (Note: use of trade and/or product names does not constitute endorsement by the USGS.)

Example shoreline classifications and changes

The Faka-Union Canal was dug in the late 1960s as part of the drainage plan for the southern Golden Gate Estates. The canal discharges into Faka-Union Bay (Fig. 2). In 1940 this part of the 10,000 Islands was comprised of an intricate network of long, linear mangrove islands (Fig. 5a). In 2004, dredge spoil islands are clearly visible and they have a fringe of mangroves (Fig. 5b). These would be classed as “Impacted-Mangrove-Shallow” shorelines. The 10,000 Islands are laced with numerous deep tidal channels and support many shallow bays (Fig. 6A, B). Most of these are fringed by mangrove forests. Mangroves have expanded into some small bays completely filling them in (Fig 6 A,B).

aerial photo of Faka-Union Bay from 1940 showing areas where dredge spoil was deposited
aerial photo of Faka-Union Bay from 2004 showing areas where dredge spoil was deposited
Figure 5. Two aerial photographs of Faka-Union Bay: one from 1940 (A) and one from 2004 (B). The red arrows point to areas where dredge spoil was deposited during the construction of the Faka-Union Canal. These mangrove shorelines would be classed as “Impacted-Mangrove-Shallow.” The photos are at a scale of 1:12,000. [click on the images above to view larger versions]


aerial photo from 1940 of the area west of Faka-Hatchee Key showing different mangrove classifications and change
aerial photo from 2004 of the area west of Faka-Hatchee Key showing different mangrove classifications and change
Figure 6. A 1940 (A) and 2004 (B) aerial photo of the area west of Faka-Hatchee Key in the 10,000 Islands. The red arrows indicate a region where mangroves have filled in a small embayment. The yellow arrows indicate a mangrove shoreline that would be classed as Natural-Mangrove-Deep (e.g. along a distinct tidal channel). The green arrows show a shoreline that would be classed as Natural-Mangrove-Shallow. The photos are at a scale of 1:12,000. [click on the images above to view larger versions]

Sawfish utilization of shorelines

After historic and current shoreline type/habitats have been documented, randomly selected occurrences of P. pectinata will be chosen for each study area. If some study areas are found to have a low number of sightings, we will use all of the sightings in the data set for that area. The frequency of occurrence of sawfish for each shoreline class will be determined for each study area. The P. pectinata shoreline use frequencies will be compared to the averaged shoreline class frequency for each area to assess if this species is selecting for or against a specific shoreline-type/habitat (Fienberg 1977). This type of analysis has been used to determine habitat selectivity in number of studies (e.g. Arthur et al. 1996, Jones 2001).

Year One Products / Deliverables

  • “Kick-off” meeting. The purpose of this meeting is for the PIs and NMFS staff to finalize, as best as is possible, such items as exact study area boundaries, scales of measurement, and minimum mapping area. A 1-2 page letter report from the PIs will summarize the decisions of the meeting.
  • Three short (3-4 pages) quarterly progress reports and / or briefings to NMFS Endangered Species Branch and Sawfish Recovery Team members.
  • Annual report with detailed write-up of all analyses, findings, and conclusions.
  • Electronic copies of all GIS data-layers, shape-files, images, and maps (to be included with the annual report).
  • Draft article for submission to a peer-reviewed scientific journal.

Activity and Timelines (assumes a June 2008 start)

Q1 Q2 Q3 Q4
1) “Kick-off” meeting *
2) Hire and train student ass't ***
3) Acquire images for Caloosahatchee *****
4) Develop shoreline classification scheme *****
5) Assemble 1940 and 2004 datalayers *****
6) Ground-truthing as needed
7) Analyze 1940 and 2004 shorelines and quantify changes ************
8) Conduct analysis of sawfish and their use of shorelines *******
9) Quarterly reports * * *
10) First Annual report ***
11) Article for journal *

Information Security:

The C&A requirements of clause 73 do not apply and a Security Accreditation Package is not required.

References

Arthur, S.M., B.F.J. Manly, L.L. McDonald and G.W. Garner. 1996. Assessing habitat selection when availability changes. Ecology 77: 215-227.

Carlson, J. K., J. Osborne & T. W. Schmidt. 2007. Monitoring recovery of smalltooth sawfish, Pristis pectinata, using standardized relative indices of abundance. Biological Conservation 136: 195-202.

Fienberg, S.E. 1977. The Analysis of Cross-Classified Categorical Data. The MIT Press, Cambridge, Ma.

Insightful. 2001. S-Plus 6 for Windows, Volume 1. Insightful Corporation, Seattle, Wa.

Jones, J. Habitat selection studies in avian ecology: A critical review. The Auk 118: 557-562.

NMFS, National Marine Fisheries Service. Endangered and threatened species: Final endangerment status of a distinct population segment of smalltooth sawfish (Pristis pectinata) in the United States. Federal Register 68: 15674-15680.

Rutchey, K., T.N. Schall, R.F. Doren, A. Atkinson, M.S. Ross, D.T. Jones, M. Madden, L. Vilchek, K.A. Bradley, J.R. Snyder, J.N. Burch, T. Pernas, B. Witcher, M. Pyne, R. White, T.J. Smith III, J. Sadle, C.S. Smith, M.E. Patterson, and G.D. Gann. 2006. Vegetation Classification for South Florida Natural Areas. USGS, OFR 2006-1240. (http://sofia.usgs.gov/publications/ofr/2006-1240/index.html)

Seitz, J. C. & G. R. Poulakis. 2006. Anthropogenic effects on the smalltooth sawfish (Pristis pectinata) in the United States. Marine Pollution Bulletin 52: 1533-1540.

Seitz, J. C. & G. R. Poulakis. 2002. Recent occurrence of sawfishes (Elasmobranchiomorphi: Pristidae) along the southwest coast of Florida (USA). Florida Scientist 65: 256-266.

Smith, T.J., III, A.M. Foster, P.R. Briere, A.W. Coffin, J. W. Jones, C. R. van Arsdall & L.J. Frye. 2002a. Historical aerial photography for the greater Everglades of south Florida: The 1940, 1:40,000 photoset. U.S. Geological Survey, Open File Report 02-327. Online at: http://sofia.usgs.gov/publications/ofr/02-327/

Smith, T.J., III, A.M. Foster, P.R. Briere, J. W. Jones & C. R. van Arsdall. 2002b. Conversion of Historical Topographic Sheets (T-Sheets) to Digital Form: Florida Everglades and Vicinity. U.S. Geological Survey, Open File Report 02-204. Online at: http://sofia.usgs.gov/publications/ofr/02-204/



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