Mapping Posidonia oceanica (Linnaeus) Meadows in the Eastern Aegean Sea Coastal Areas of Turkey: Evaluation of Habitat Maps Produced Using the Acoustic Ground- Discrimination Systems

Abstract

Coastal areas include highly complex ecosystems that encompass many different and productive resources worldwide. Althoughhaving such great importance, the lack of basic knowledge concerning the marine habitat distribution and biodiversity along theTurkish shoreline is an undeniable reality. In this study, seagrass beds in the bays along the Eastern Aegean Sea coast were locatedand mapped. Traditionally, sea-truth data used for satellite-image and other analysis are collected through direct observationsrequiring scuba divers or by aquatic video-camera observation. This study included a combination of acoustic technology, videorecording and interpretation, geomorphological, oceanographic, and sedimentological evaluation in order to make significantcontributions of current technology. The classification of the evaluated Subbottom Profiler (SBP) records exhibited their highdiscrimination capacity between different sea-bed features, making them appropriate for ground distinction. Linking of the SBP datasets to the Side Scan Sonar (SSS) records (object-based analysis) provide to full coverage, high resolution benthic habitat maps. Forthis purpose, Side Scan Sonar, 3.5/10 kHz Subbottom Profiler data were collected to a range of 50 m water depth, the data wasrecorded for a total 1600 km2 coastal area that consists of approximately a total 3000 km long and 1km wide grid system for Edremit,Çandarlı, Gülbahçe, Ildır, Güllük and Gökova Bays. In the study area, it was determined that the seagrasses are under danger wherehigh human influence is located. Dense distribution of invasive macroalgae (Caulerpa cylindracea, Stypopodium schimperi) wereseen at the southern and northern part of the study area subjected to human activities.