Sobczyk Robert, Serigstad Bjorn, Pabis Krzysztof
Department of Invertebrates Zoology and Hydrobiology, University of Lodz, Lodz, Poland.
Center for Development Cooperation in Fisheries, Institute of Marine Research, Bergen, Norway.
Sci Total Environ. 2023 Feb 10;859(Pt 1):160046. doi: 10.1016/j.scitotenv.2022.160046. Epub 2022 Nov 8.
The Tropical East Atlantic is one of the least studied areas in the world's oceans, and thus a blank spot on the map of marine studies. Shaped by dynamic currents and shifting water masses, it is a key region in discussions about marine ecology, biodiversity, and zoogeography, while facing numerous, poorly understood, and unmonitored threats associated with climate change, acidification, and pollution. Polychaete diversity was assessed along four transects along the Ghana coast, from shallow to deep bottoms and distributed along the whole upwelling marine ecoregion. Despite high sampling effort, steep species accumulation curves demonstrated the necessity of further sampling in the region. We observed zonation of fauna by depth, and a decrease in species richness from 25 m to 1000 m depth. Polychaete communities were influenced by sediment type, presence of oxygen minimum zones, and local disturbances caused by elevated barium concentrations. Similar evenness along the depth gradient reflected the importance of rare species in the community structure. Differences in phylogenetic diversity, as reflected by taxonomic distinctness, were small, which suggested high ecosystem stability. The highly variable species richness at small scale (meters) showed the importance of ecological factors giving rise to microhabitat diversity, although we also noticed intermediate scale (50-300 km) differences affecting community structure. About 44 % of the species were rare (i.e. recorded only in three or fewer samples), highlighting the level of patchiness, while one fifth was distributed on all transects, therefore along the whole upwelling ecoregion, demonstrating the influence of the regional species pool on local communities at particular stations. Our study yielded 253 species, increasing the number of polychaetes known from this region by at least 50 %. This casts doubt on previous findings regarding Atlantic bioregionalization, biodiversity estimates and endemism, which appear to have been more pronouncedly affected by sampling bias than previously thought.
热带东大西洋是世界海洋中研究最少的区域之一，因此也是海洋研究地图上的一个空白点。它受动态洋流和不断变化的水体影响，是海洋生态、生物多样性和动物地理学讨论中的关键区域，同时面临着与气候变化、酸化和污染相关的众多、了解甚少且未受监测的威胁。沿着加纳海岸的四条断面，从浅海到深海底部，并分布在整个上升流海洋生态区域，对多毛类多样性进行了评估。尽管采样力度很大，但陡峭的物种积累曲线表明该区域有必要进一步采样。我们观察到动物群按深度呈带状分布，物种丰富度从25米深度到1000米深度逐渐降低。多毛类群落受到沉积物类型、最低含氧区的存在以及钡浓度升高引起的局部干扰的影响。沿深度梯度相似的均匀度反映了稀有物种在群落结构中的重要性。分类差异所反映的系统发育多样性差异较小，这表明生态系统稳定性较高。小尺度（米）上高度可变的物种丰富度表明了导致微生境多样性的生态因素的重要性，尽管我们也注意到中尺度（50 - 300公里）差异对群落结构有影响。约44%的物种很稀有（即仅在三个或更少样本中被记录），突出了斑块性程度，而五分之一的物种分布在所有断面上，因此分布在整个上升流生态区域，这表明区域物种库对特定站点的当地群落有影响。我们的研究产生了253个物种，使该区域已知的多毛类物种数量至少增加了50%。这对先前关于大西洋生物区域划分、生物多样性估计和特有性的研究结果提出了质疑，这些结果似乎比之前认为的更受采样偏差的显著影响。
