http://surfspots-gps.com

Measuring changes to sea turtle nesting beaches and their effects on nesting success using LiDAR data

Kristina Yamamoto, PhD

Current Knowledge/Limitations

• Green turtles – like vegetation • Leatherbacks and loggerheads – do not like

vegetation • Multiple beaches – rarity • Beach as a whole – rarity • Morphological features – rare • Studies over time - rare

LiDAR Background

• Laser signals sent as pulses from typically in the ultraviolet (UV), visible, and near infrared (NIR)

z y

x

z y

x

pitch roll

yaw

LiDAR Cloud

http://www.pobonline.com/POB/Home/Images/pob1009_woolpert03_LiDAR_Point.jpg

Study Species: Loggerhead

• Caretta caretta • Big head

http://www.supergreenme.com/data/images/27/500x333_Loggerhead_Sea_Turtle-Georgia-Aquarium.jpg /

Study Species: Green

• Chelonia mydas • Soup turtle

http://greatescapetravel.com/

Study Species: Leatherback

• Dermochelys coriacea

• Half the size of a VW beetle

http://fwie.fw.vt.edu/VHS/reptiles/turtles/leatherback-sea-turtle/leatherback-seaturtle2.jpg/

Study Area

One of the largest loggerhead rookeries in the world, one of the largest green turtle nesting areas in the Atlantic ,and the only continuously used nesting area in the continental United States for leatherbacks

Study Data

Name Dates

LiDAR topo: Airborne Topographic Mapper (ATM) II

1999

LIDAR topo/bathy: Joint Airborne LiDAR Bathymetry Technical Center of Expertise (JALBTX) using the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system

2004, 2006

Florida Fish and Wildlife Conservation Commission nesting data

1999-2008

Current Knowledge/Limitations

• Green turtles – like vegetation • Leatherbacks and loggerheads – do not like

vegetation • Multiple beaches – rarity • Beach as a whole – rarity • Morphological features – rare • Studies over time - rare

• 1999, 2004, and 2006 LiDAR data compared • How do sea turtle nesting beaches change

over time? • How does this affect sea turtle nesting

success?

Methods

1999 2004 2006

Methods

Variables to be Compared Between Beaches

Volume

Elevation

Slope

Beach length, width, area

Orientation

Aspect Surface roughness Pixel position

Change to Beach Variables

1999 2004 2006

• How does the volume of beaches change over time?

• Is there a geographic or morphologic pattern?

Results: Changes to Beach Variables

• No geographic pattern or orientation correlation with beach change in volume

Beach 1999

Volume 2004

Volume 2006

Volume Boca Raton Beaches 0.656 0.813 0.881 Deerfield/Hillsboro Beaches 0.654 0.660 0.035 Delray Beach 0.607 0.615 0.708 Ft Lauderdale Beach 0.988 1.193 1.006 Golden Beach 0.143 0.170 0.146 Gulfstream 0.101 0.099 0.136 Gulfstream Park 0.005 0.006 0.006 Hollywood/Hallandale Beach 0.626 0.743 0.411 John U. Lloyd Beach State Park 0.268 0.275 0.284 Kreusler Park 0.040 0.035 0.025 Lake Worth Municipal Beach 0.022 0.022 0.021 Lantana 0.009 0.010 0.007 Macarthur State Park 0.134 0.199 0.265 Ocean Inlet Park 0.025 0.035 0.038 Ocean Reef Park 0.001 0.001 0.011 Pompano/Lauderdale-by-the-Sea 1.418 1.934 1.916 Singer Island 0.102 0.108 0.213 Sloan's Curve 0.040 0.053 0.079

Change to Beach Variables

2: Beach Change over Time

1999 2004 2006

Is the difference in the amount of sand present in a beach related to change in other beach characteristics?

Results: Changes to Beach Variables

• Weak correlations to change in volume with change in other variables

2: Beach Change over Time

Variable R2 Variable coefficient Change in minimum elevation 0.31 -88940.26 Change in maximum elevation 0.18 44982.07 Change in maximum slope 0.21 8490.37 Change in average slope 0.13 33350.83 Change in minimum TPI 0.22 -113775.60 Change in maximum TPI 0.20 55026.90 Change in standard deviation of TPI 0.15 183321.30 Change in standard deviation of rugosity 0.16 3058584.90

Results: Changes to Beach Variables

• For minimum elevation, 90% of the beaches decreased their minimum elevation between 1999 and 2004

• 83% gained between 2004 and 2005 • Similar trends seen for standard deviation of

elevation, maximum slope, and minimum and standard deviation of TPI

2: Beach Change over Time

Change to Beach Variables

2: Beach Change over Time

1999 2004 2006

How do changes to beach morphology affect nesting success?

Results: Change in nesting success

Variable R2 Variable coefficient Change in minimum elevation 0.184 7.435 Change in maximum slope 0.158 -0.809 Change in minimum TPI 0.113 8.919 Change in maximum TPI 0.229 6.400

2: Beach Change over Time

Variable R2 Variable coefficient

Change in mean TPI 0.210 645.121

Caretta caretta

Chelonia mydas

Conclusion

• Broad generalizations about the effects of beach volume changes to a beach’s morphology cannot be made for this study area – beaches act as individuals

• Nesting success for Chelonia mydas and Caretta caretta were not wholly affected by the observed changes to their nesting beaches

2: Beach Change over Time