1. High-Resolution Determination of Coral Reefs using Fluorescence Imagery Laser Line Scanner (FILLS)

2. Laser Line Scanning Electro-optic imaging technique Application of lasers for mapping of benthic environment –Lasers allow for higher image resolution Superior object/organism recognition More sophisticated than traditional technologies –Trawl –Direct Observation

3. FILLS Seeks to: –map coral reef bathymetry –Evaluate degree to which organisms are present Generating high-resolution image of an entire reef

4. FILLS A towed system (behind a vessel or attached to a submersible) Emits a swath blue-green (488 nm) light Inverse relationship between width of the swath and resolution of image –Determined by altitude of instrument Limited by water clarity

5. FILLS distance limitations Laser Line Scanning (LLS) results have been of sufficient quality within five to six beam attenuation lengths –Distance over which beam intensity is reduced by a factor of 1/e, or ~63%, by absorption and scattering

6. FILLS Four sensors are equipped with a 488 nm filter to exclude reflected light Each sensor channel generates a distinct black & white image of the area Channels measure: –488 nm (reflectance) –520 nm (green) –580 nm (orange) –685 nm (red)

7. Raw FILLS Results 488 nm520 nm580 nm685 nm compositeredorangegreenreflectance

8. FILLS Each channel is mapped to display its respective color, and the four images are combined to display a composite Significant because different organisms fluoresce at different wavelengths, meaning different groups and species may have fluorescent signatures (therefore, the use of distinct sensors)

9. FILLS Coral reef organisms were able to be distinguished significantly based on fluorescence alone due to symbiotic zooxanthellae, exhibiting a maximum fluorescence at ~685 nm (red) due to Chlorophyll a Macroalgaes, Sediments, Sponges, and non- fluorescent organisms can likewise be distinguished for different reasons

10. FILLS Data is analyzed using an algorithm which defines relationships between adjacent pixels the resulting objects, in order to determine to which taxonomic group an organism belongs

11. FILLS data check Composite images are then printed on waterproof paper, and divers are able to conduct direct observations to verify the algorithm calculations With few corrections, the following image results:

12. Where: –White = corals, anemones, zooanthids –Red/brown = gorgonians –Green = sand/substrate –Blue = red algal turf –Black = shadows/fish & Calyspongia vaginalis –Purple = Xestospongia muta –Pink = Unknown Near left: image detail, with barrel sponge Xestospongia muta at bottom left, with algae growing in the center of the sponge (indicated by the red) Far Left: mottled orange are zooanthid colonies (Palythoa caribaeorum)

13. FILLS Shortcomings Small-scale data inconsistencies –Divers are either more or less accurate Cost of operations –Until direct observation becomes unnecessary, this method is cost prohibitive Common presence of Chlorophyll a –This pigment fluoresces most brightly at ~685 nm (red), and makes it difficult to distinguish organisms with similar morphology and fluorescent signal

14. FILLS Utility Coral reef diversity and organism frequency Population dynamics over time Track & observe coral bleaching on colonies and entire reefs

15. Other LLS Applications Identify aggregations of bottomfish Potential bottomfish nursery areas Various coral communities Airplane wreckage location and imaging –e.g.TSA flight 800 Still more affordable and accurate than traditional still or video photography Can map greater area in less time, with less disturbance to inhabitants of the ecosystem