The Sea of Marmara hosts part of the North Anatolian Fault as an active submarine strike-slip fault. This area has suffered numerous earthquakes and presents a major seismic risk. Although the Sea of Marmara has been studied for many years, the link between geological morphostructures, the nature of fluids and biological communities is still rarely described. During the Marsite cruise (November 2014), dives with Remotely Operated Vehicle (ROV) VICTOR 6000 focused on detailed seafloor explorations of four different areas: the Central and Western highs and the Tekirdağ and Çinarcik basins. Based on 130 h of in situ videos, high-resolution seafloor mapping of seeps was conducted, emphasizing their significant geological and biological diversity from one seeping site to another, from one basin/high to another. Gas bubbles (CH₄, CO₂), shimmering water (brine, marine and fresh water) and oil, escape from the seafloor into the water column with low to strong fluxes. Black patches of reduced sediments, authigenic carbonate crusts and chimneys compose the seep environments with various types of bacterial mats and chemosynthetic fauna. Several venting sites discovered during previous cruises are still active 7–12 years later. The seeps are mostly, but not only, focalized along the Main Marmara Fault (MMF), at the southern border of the Tekirdağ Basin and along the Western High. Fluid emission is also occurring at secondary faults and at their intersection with the MMF. Our study emphasizes the location of seeps at the foot of slopes, gully outlets and crossroads. Sedimentary features, such as mass wastings, stratigraphic discontinuities or canyons, also interact with fluid emissions. The observed fauna is dominated by Bathymodiolinae, Vesicomyidae, Lucinidae-like empty shells and tubiculous worms resembling Ampharetidae polychatea. Most of the symbiont-bearing taxa encountered and previously sampled in the Marmara Sea, are characterized by thiotrophic symbioses. Vesicomyids and Idas sp. mussels are present at gas seeps, but also in areas where crude oil escapes from the seafloor. Moreover, other taxa unusually encountered at cold seeps such as large-sized amphipod and vagile worms were observed in the Çinarcik Basin. Idas-like mussels were observed in the western part of the Sea of Marmara, in the Tekirdağ Basin and possibly on the Western High active seep sites. There, the sampled fluids had high methane content (reaching 65 μmol/l) but not as high as on the Central High (363 μmol/l) and Çinarcik Basin (228 μmol/l) where no mussels were observed in the video records. Bottom waters oxygen levels in the Sea of Marmara showed a west to east decreasing gradient (57–8.5 μmol/l). These oxygen conditions, which fall under the limit of Oxygen Minimum Zones (OMZ <20 μm/l) in the eastern part, may impact benthic fauna and explain the absence of symbiotrophic bivalves at cold seep sites of the Çinarcik Basin, whereas densely aggregated amphipods, likely more tolerant to oxygen stress were observed in the seepage area. Finally, no specific fauna was observed near the CO₂-rich seep sites. First observations suggest that seep fauna composition in the Sea of Marmara does not seem to be strongly influenced by the nature (e.g., oil, gas bubbling, brines) of fluid venting through seeps. The seep environments are highly variable and characterized by distinctive geological morphostructures. They sustain typical Mediterranean cold seep fauna, but also unusual communities likely related to the interaction of seeps with hypoxic conditions.

马尔马拉海拥有北安纳托利亚断层的一部分，是活跃的海底走滑断层。该地区遭受了多次地震，存在重大地震危险。尽管对马尔马拉海进行了多年研究，但仍很少描述地质形态结构，流体性质和生物群落之间的联系。在马斯特（Marsite）航行期间（2014年11月），潜水员使用遥控车辆（ROV）VICTOR 6000潜水，重点研究了四个不同区域的海底详细勘探：中部和西部高地以及Tekirdağ和Çinarcik盆地。基于原地130小时视频中，对高分辨率的海底渗漏进行了测绘，强调了它们从一个渗漏点到另一个渗漏点，从一个盆地/高地到另一个渗漏点的重要地质和生物多样性。气泡（CH ₄，CO ₂），波光粼粼的水（盐水，海水和淡水）和油，以低至强通量从海底逸入水柱。减少沉积物的黑色斑块，自生的碳酸盐结壳和烟囱组成了各种细菌垫和化学合成动物组成的渗流环境。在之前的航行中发现的几个通风点在7-12年后仍处于活动状态。渗漏主要集中于但不仅限于沿着主要马尔马拉断层（MMF），Tekirdağ盆地南部边界和西部高地。在次级断层及其与MMF的交汇处也发生了流体排放。我们的研究强调在斜坡，沟渠出口和十字路口脚下的渗漏位置。沉积特征，例如大量浪费，地层不连续性或峡谷，也与液体排放相互作用。观察到的动物群主要由嗜盐杆菌科，脉菌科，类Lucinidae的空壳和类似于伞形科的茶科蠕虫组成。先前在马尔马拉海遇到和采样过的大多数带有共生生物的类群都具有硫营养型共生酶。囊泡和艾达斯sp。贻贝不仅存在于天然气渗漏中，而且存在于原油从海底逸出的区域。此外，在奇纳尔西克盆地还观察到了在冷渗流中不常见的其他类群，例如大型两栖纲和易变蠕虫。艾达斯在马尔马拉海西部，Tekirdağ盆地以及西部高活跃渗漏点发现了类贻贝。在那里，采样液中的甲烷含量很高（达到65μmol/ l），但不如中高（363μmol/ l）和奇纳尔西克盆地（228μmol/ l）高，在视频记录中没有发现贻贝。马尔马拉海底水的氧气水平显示出从西向东的递减梯度（57–8.5μmol/ l）。这些处于东部最低氧区（OMZ <20μm/ l）范围内的氧气条件可能会影响底栖动物，并解释了Çinarcik盆地冷渗水点没有共生双壳类动物，而密集的两栖纲动物在渗流区观察到可能更耐氧气胁迫。最后，在CO附近没有观察到特定的动物_2-丰富的渗透场所。最初的观察结果表明，马尔马拉海的渗流动物区系似乎似乎不受渗流流体的性质（例如，石油，天然气起泡，盐水）的强烈影响。渗流环境变化很大，并具有独特的地质形态结构。它们维持典型的地中海冷渗流动物区系，但也维持不寻常的群落，这可能与渗流与低氧条件的相互作用有关。