Analysis ofNear-Bottom Photos forBenthic Habitat Studies

Thispaperreports onamethodology developed for theanalysis ofnear-bottom photographs collected forfisheries habitat studies. Thesetools provide aframework forconducting minimally invasive in-situ investigations ofbenthic organism abundance, diversity, anddistribution usinghigh-resolution optical datasets integrated withhighprecision navigational data. Utilizing these techniques withnear-bottom photos collected with a precision navigated surveyplatform greatly increases the efficiency ofimageanalysis andprovides newinsight aboutthe relationships betweenbenthic organisms andthehabitats in whichtheyarefound. Basicrequirements fortheanalysis ofnear-bottom seafloor imagesinclude cameracalibration andquantification ofthe height ofthelensabovetheseafloor throughout thesurvey. Corrections arerequired tocompensate forimagedistortion due tolighting limitations andthevariable micro-topography ofthe seafloor. Theseparameters canbeconstrained byutilizing precisely navigated surveyplatforms suchasAutonomous Underwater Vehicles (AUVs)orRemoteOperated Vehicles (ROVs). The methodology we present was developed withdata collected bytheSeaBEDAUV offthecoastofWashington, Oregon andCalifornia 111. A digital database containing benthic organism identifications, measurements, and locations was generated foreachimageusing aGraphical UserInterface (GlUI) created inMatlabTM 11,21. Thismethodology hasdemonstrated a significant increase intheefficiency ofimageanalysis for benthic habitat studies, andprovides theopportunity toassess smallscalespatial distribution oforganisms intheir natural habitats. Collecting overlapping images permits thecreation of photomosaics 131andthequantification oforganism abundance perunit areaoftheseafloor.