Interpretation of Spectral LiDAR Backscattering off the Florida Coast

A multispectral backscattering LiDAR (Light detection and range) system (hereafter Oculus) was integrated into a wave glider and used to estimate the scattering order (i.e., single vs multiple collisions) of LIDAR backscattering, the water inherent optical properties (IOPs), the biogeo-chemical characteristics of particulate scatterers (i.e., relative size, composition) and their motion) on shelf waters of South East Florida. Oculus has a dual-wavelength configuration (473 and 532 nm) and two detection geometries (off- and on-axis). Characteristics of scatterers were investigated based on two complementary LiDAR-derived proxies (the Structural Dissimilarity Index and the spectral slope of LiDAR backscattering). In March 2017, field measurements showed a covariation between direct and diffuse backscattering contributions during morning hours and away from shore. LiDAR attenuation coefficients explained up to 57% of IOPs variability. The analysis of LiDAR-derived proxies suggested higher turbidity and larger particulates near the coas

Mechanisms That Generate Resource Pulses in a Fluctuating Wetland.

Animals living in patchy environments may depend on resource pulses to meet the high energetic demands of breeding. We developed two primary a priori hypotheses to examine relationships between three categories of wading bird prey biomass and covariates hypothesized to affect the concentration of aquatic fauna, a pulsed resource for breeding wading bird populations during the dry season. The fish concentration hypothesis proposed that local-scale processes concentrate wet-season fish biomass into patches in the dry season, whereas the fish production hypothesis states that the amount of dry-season fish biomass reflects fish biomass production during the preceding wet season. We sampled prey in drying pools at 405 sites throughout the Florida Everglades between December and May from 2006-2010 to test these hypotheses. The models that explained variation in dry-season fish biomass included water-level recession rate, wet-season biomass, microtopography, submerged vegetation, and the interaction between wet-season biomass and recession rate. Crayfish (Procambarus spp.) biomass was positively associated with wet-season crayfish biomass, moderate water depth, dense submerged aquatic vegetation, thin flocculent layer and a short interval of time since the last dry-down. Grass shrimp (Palaemonetes paludosus) biomass increased with increasing rates of water level recession, supporting our impression that shrimp, like fish, form seasonal concentrations. Strong support for wet-season fish and crayfish biomass in the top models confirmed the importance of wet-season standing stock to concentrations of fish and crayfish the following dry season. Additionally, the importance of recession rate and microtopography showed that local scale abiotic factors transformed fish production into the high quality foraging patches on which apex predators depended

The Everglades of southern Florida and the set of landscape units from which we drew samples.

<p>Small squares indicate randomly located primary sampling units 500 m x 500 m in size. The bounding coordinates of the study site are: North 26.69, South 24.97, East -80.06, and West -81.53.</p

Mean habitat variables and wet season prey biomass from 2006–2010.

<p>Mean habitat variables and wet season prey biomass from 2006–2010.</p

Conceptual model outlining hypotheses for factors effecting dry-season wading bird prey concentration in the Florida Everglades.

<p>Hypotheses are delineated by solid or dashed grey and black lines.</p

Model-averaged parameters of factors affecting the concentration of fish, crayfish, and grass shrimp biomass.

<p>Model-averaged parameters of factors affecting the concentration of fish, crayfish, and grass shrimp biomass.</p

The relationship between predicted dry-season fish biomass (y-axis) and recession rate (x-axis).

<p>Low (circles), medium (triangle) and high (cross) levels of wet season biomass.</p

Results of generalized linear mixed-effects models of factors affecting fish, crayfish and grass shrimp biomass in the Florida Everglades, USA.

<p>Results of generalized linear mixed-effects models of factors affecting fish, crayfish and grass shrimp biomass in the Florida Everglades, USA.</p

Mean water depth and rainfall for each day throughout the Florida Everglades from June 2006 to July 2010.

<p>Depth values represent the mean of 42,415 EDEN grid cells throughout most of the freshwater portion of the Everglades. Rainfall represents the mean of 18 rainfall gauges (NE4, NP202, NP203, P33, CR2, A13, NP206, NP62, P36, P34, TMC, NP205, BCA18, BCA19, BCA20, MDTS, S174, S20). Light grey, white, and dark grey bars represent fish, crayfish, and grass shrimp biomass (g m^-2), respectively for 2006 to 2010 dry seasons.</p

Species are presented in descending order of cumulative frequency representing 99% of individuals captured in throw-traps during 2006–2010 dry seasons.

<p>Species are presented in descending order of cumulative frequency representing 99% of individuals captured in throw-traps during 2006–2010 dry seasons.</p