Limited research effort in the Central Mediterranean deep sea has reported a lower species diversity in this area than in adjacent regions. With the recent advent of remotely operated underwater vehicles (ROVs), the deep sea has become more accessible to surveys, especially rocky benthic areas such as canyons and escarpments. The aim of the present study was to assess diversity, spatial and bathymetric distribution, density, habitat, and microhabitat associations of echinoderms in deep waters around the Maltese Islands. Video data were acquired through ROV surveys as part of the LIFE BaĦAR for N2K project, at depths of 216 to 1031 m. In total, 25 echinoderm taxa were recorded, including the first Central Mediterranean records of the sea stars Marginaster capreensis (Gasco, 1876) and Sclerasterias neglecta (Perrier, 1891), and the first record of the holothuroid Mesothuria intestinalis (Ascanius, 1805) from Maltese waters. Six species were observed deeper than their currently accepted depth range in the Mediterranean. The most abundant species were the crinoids Antedon mediterranea (Lamarck, 1816) and Leptometra phalangium (Müller, 1841), which formed very dense aggregations of up to 2900 individuals/1000 m² in a small area to the south of Malta. This area also supports the only known Mediterranean population of the Atlantic sea star Coronaster briareus (Verrill, 1882). Bathymetric distribution varied for each species, and the overall echinoderm diversity seemed stable across the surveyed depths. Since previous deep-sea studies in the area were based on trawling surveys, many deep-sea echinoderm species are reported in the literature as occurring on sedimentary bottoms. However, the present study revealed that several occur more often on rocky substrata, corals, or anthropogenic objects than on sediments. Our study based on video footage also provided insights into the microhabitat of many deep-sea species, yielding information that is not obtainable through remote sampling.

中文翻译：

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地中海中部深海棘皮动物的多样性，分布和生境关联

据报道，地中海中部深海的研究工作有限，该地区的物种多样性低于邻近地区。随着近来遥控水下航行器（ROV）的出现，深海变得更易于测量，尤其是岩石底栖地区，如峡谷和悬崖。本研究的目的是评估马耳他群岛周围深水域中棘皮动物的多样性，空间和测深分布，密度，生境和微生境关联。通过LIVBaĦAR的N2K项目，通过ROV勘测获取了视频数据，深度为216至1031 m。总共记录了25个棘皮动物类群，包括地中海中最早的海星Marginaster capreensis（Gasco，1876年）和Sclerasterias neglecta（佩里耶，1891年），以及holothuroid的第一条记录Mesothuria肠（阿斯卡尼俄斯，1805）从马耳他海域。在地中海，观察到六个物种比其目前公认的深度范围更深。最丰富的物种是地中海中的海百合类（Anedon mediterranea）（Lamarck，1816年）和ept骨（Leptometra phalangium）（Müller，1841年），它们在马耳他南部的一个小区域内形成了非常密集的聚集体，最多达2900人/ 1000 m ²。该地区还支持大西洋海星Coronaster briareus的唯一已知地中海种群（Verrill，1882年）。各物种的测深分布各不相同，整个棘皮动物多样性在所调查的深度上似乎稳定。由于该地区先前的深海研究是基于拖网调查的，因此文献中报道了许多深海棘皮动物物种发生在沉积底部。但是，目前的研究表明，有几种情况更常见于岩石地层，珊瑚或人为物体上，而不是沉积物上。我们基于录像的研究还提供了对许多深海物种的微生境的见解，产生了无法通过远程采样获得的信息。