11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 17: Emerging Techniques in Remote Sensing and Geospatial Analysis
17-21
A Comparative Assessment Of Lidar And Multibeam Sonar To Characterize Coral
Reef Ecosystem
Timothy BATTISTA* 1 , Bryan COSTA 1,2
1 National Ocean Service, NOAA, Silver Spring, MD, 2 National Ocean Service, NOAA,
Silver Spring
A comparison of airborne LiDAR and ship-based mulitbeam sonar was conducted in
southwest Puerto Rico to evaluate the efficacy of these systems in characterizing shallowwater
coral reef environments (< 30 meters water depth). Multibeam sonar acquisition in
shallow-water environments is prohibitive due to the relationship between swath width
and water depth. The availability of comparable data products from airborne LiDAR
(i.e., bathymetry and seafloor reflectance) provides an alternative to multibeam sonar
surveys to collect seafloor characterization data. The test location, Abrir la Sierra
conservation area, is comprised of a suitable diversity of topographic relief,
geomorphological structure and biological cover types to test the utility of data derived
from the respective remote sensing platforms. An evaluation was conducted to compare
the efficiency, data integrity, and effectiveness of the LiDAR and multibeam sonar
systems to discriminate meaningful landscape patterns. This analysis was conducted to
allow resource managers and scientists to determine the most effective remote sensing
platform to characterize shallow-water tropical marine environments.
17-22
Statistical Comparison Of Single-Beam Acoustic Backscatter (38 And 418 Khz)
With Lidar-Derived Coral Reef Benthic Habitat Class And Topographic
Complexity
Greg FOSTER* 1 , Walker BRIAN 1 , Bernhard RIEGL 1
1 National Coral Reef Institute, Dania Beach, FL
Producing coral reef benthic habitat maps from acoustic backscatter has been hindered by
uncertainties in interpreting the acoustic energy parameters E1 (roughness) and E2
(hardness), typically limiting such maps to sediment classification schemes. In this study
acoustic interpretation was guided by high-resolution LADS (Laser Airborne Depth
Sounder) bathymetry. The acoustic survey was conducted in Palm Beach County, FL,
from inshore sand to outer reef slope, using a multiplexed echosounder (BioSonics DT-X
at 38 & 418 kHz). E1 and E2 values, empirically normalized to mean depth, were
compared to spatially-coincident values of a LADS-derived proxy for topographic
complexity (Reef-Volume) and eight LADS-delineated benthic habitat classes. The 38
and 418 kHz E1 parameters were positively correlated with Reef-Volume, in agreement
with the general empirical basis for bottom seabed classification. The opposite trend was
observed for the 38 and 418 kHz E2 parameters, contrary to convention, which would
predict an increasing trend of E2 from sand (soft, flat) to colonized pavement (hard, flat).
Tukey HSD testing proved all four acoustic parameters capable of distinguishing between
habitats; significant differences ranged from 25-27 of the k(k-1)/2=28 comparisons
between the eight habitat categories. An a posteriori discriminant analysis of each
frequency, pairing E1 and E2 as predictor variables, showed that the 418 kHz signal
provided superior predictive accuracy for six (consolidated from eight) habitat classes
(74.3 versus 68.2%). Consideration of all results reveals topographic complexity as the
primary factor controlling both E1 and E2. The information encoded in the two
frequencies is generally the same, with 418 kHz being better suited for discriminating
between habitats of high complexity and 38 kHz for distinguishing between sand and
sand-over-hardbottom. The LADS bathymetry proved useful for demonstrating that E1
and E2 values of single-beam echosounders can indeed produce meaningful coral reef
benthic habitat maps.
17-23
Measuring The Rough With The Smooth: Predicting Fish Species Richness Using Lidar
Derived Surface Complexity
Simon PITTMAN* 1 , Bryan COSTA 2 , Tim BATTISTA 2
1 Biogeography Branch, NOAA & University of the Virgin Islands, St Thomas, Virgin Islands
(U.S.), 2 Biogeography Branch, NOAA, Silver Spring, MD
Coral reef ecosystems exhibit complex vertical and horizontal structural heterogeneity at a
range of spatial scales. This heterogeneity plays an important ecological role in influencing the
distribution, abundance and behaviour of marine organisms. For example, more complex
structures typically support higher species richness than less complex structures. Measures of
surface complexity in the marine environment have been widely used to quantify structural
heterogeneity, yet most studies have focused at relatively fine (