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. Although having such great importance, the lack of basic knowledge concerning the marine habitat distribution and biodiversity along the Turkish shoreline is an undeniable reality. In this study, seagrass beds in the bays along the Eastern Aegean Sea coast were located and mapped. Traditionally, sea-truth data used for satellite-image and other analysis are collected through direct observations requiring scuba divers or by aquatic video-camera observation. This study included a combination of acoustic technology, video recording and interpretation, geomorphological, oceanographic, and sedimentological evaluation in order to make significant contributions of current technology. The classification of the evaluated Subbottom Profiler (SBP) records exhibited their high discrimination capacity between different sea-bed features, making them appropriate for ground distinction. Linking of the SBP data sets to the Side Scan Sonar (SSS) records (object-based analysis) provide to full coverage, high resolution benthic habitat maps. For this purpose, Side Scan Sonar, 3.5/10 kHz Subbottom Profiler data were collected to a range of 50 m water depth, the data was recorded for a total 1600 km 2 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 where high human influence is located. Dense distribution of invasive macroalgae (Caulerpa cylindracea, Stypopodium schimperi) were seen at the southern and northern part of the study area subjected to human activities.

Antalya Körfezi’ndeki Posidonia oceanica Deniz Çayırının Yaprak Boyu ve Biyokütle Miktarının Akustiksel Tahminleri

“…The detection of vegetation cover and distribution is particularly important, but previous studies have only employed standard methods (observations, sampling or marking with SCUBA, photography with the quadrat technique, satellite) (Pergent-Martini et al, 2005b;Yücel-Gier et al, 2020). Recently, acoustic devices (i.e., side-scan sonar, multi-beam echo sounder) and remote-controlled vehicles have been used for highly effective seabed mapping and characterization (Bonacorsi et al, 2013;Montefalcone et al, 2013;Buchet, 2015;Duman et al, 2019). Acoustic methods are more advantageous than standard methods because they are easier to apply and can be employed quickly over large areas without involving a large team.…”

Contribution of Posidonia oceanica meadows in the context of climate change mitigation in the Mediterranean Sea

“…The surface area covered by P. oceanica meadows in the Mediterranean Sea has been the subject of several estimates (Pasqualini et al, 1998, UNEP-MAP-RAC/SPA, 2009Giakoumi et al, 2013;Telesca et al, 2015). The scarcity of data for the eastern basin detracts from the accuracy of these estimates, although recent mapping works of Topouzelis et al (2018) and Traganos et al (2018), for the Greek coastline (32% of the Mediterranean coastline), Akçali et al (2019) and Duman et al (2019) for 3 000 km of Turkish Mediterranean coastline, have made it possible to improve the accuracy of the previous estimates.…”

Determination of potential aquaculture fields by evaluation of morphometric, hydrodynamic and environmental parameters in Çandarlı Bay, Eastern Aegean Sea

“…Due to its significant ecological and economic role (Borum & Greve, 2004; Boudouresque et al., 2012), this species is protected by EU legislation (Holon et al., 2015). Çandarlı Bay seagrass areas are spread over a total area of 17.6 km 2 and up to a maximum of 30 m water depth and cover about 10% of the bay floor (Duman et al., 2019).…”