Rocky benthic communities are common in Antarctic coastal habitats; yet little is known about their carbon turnover rates. Here, we performed a broad survey of shallow ( < 65 m depth) rocky ice-scoured habitats of South Bay (Doumer Island, Western Antarctic Peninsula), combining (i) biodiversity assessments from benthic imaging, and (ii) in situ benthic dissolved oxygen (O2) exchange rates quantified by the aquatic eddy covariance technique. The 18 study sites revealed a gradual transition from macroalgae and coralline-dominated communities at ice-impacted depths (15–25 m; zone I) to large suspension feeders (e.g., sponges, bivalves) at depth zone II (25–40 m) and extensive suspension feeders at the deepest study location (zone III; 40–65 m). Gross primary production (GPP) in zone I was up to 70 mmol O2 m−2 d−1 and dark ecosystem respiration (ER) ranged from 15 to 90 mmol m−2 d−1. Zone II exhibited reduced GPP (average 1.1 mmol m−2 d−1) and ER rates from 6 to 36 mmol m−2 d−1, whereas aphotic zone III exhibited ER between 1 and 6 mmol m−2 d−1. Benthic ER exceeded GPP at all study sites, with daily net ecosystem metabolism (NEM) ranging from − 22 mmol m−2 d−1 at the shallow sites to − 4 mmol m−2 d−1 at 60 m. Similar NEM dynamics have been observed for hard-substrate Arctic habitats at comparable depths. Despite relatively high GPP during summer, coastal rocky habitats appear net heterotrophic. This is likely due to active drawdown of organic material by suspension-feeding communities that are key for biogeochemical and ecological functioning of high-latitude coastal ecosystems.

中文翻译：

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浅层岩石栖息地的底栖初级生产和呼吸作用：来自南湾（南极半岛西部杜默岛）的案例研究

岩石底栖群落在南极沿海栖息地很常见；然而，人们对其碳周转率知之甚少。在这里，我们对南湾（南极半岛西部杜默岛）的浅层（< 65 m 深）岩石冰冲刷栖息地进行了广泛调查，结合 (i) 底栖成像的生物多样性评估，和 (ii) 原位底栖溶解由水生涡流协方差技术量化的氧气 (O2) 交换率。18 个研究地点揭示了从受冰影响深度（15-25 m；I 区）的大型藻类和珊瑚群落为主的群落逐渐过渡到深度 II 区（25-40 m）的大型悬浮饲养者（例如海绵、双壳类动物）和最深研究位置（III 区；40-65 m）的大量悬浮馈线。I 区的初级生产总值 (GPP) 高达 70 mmol O2 m-2 d-1，暗生态系统呼吸 (ER) 的范围为 15 至 90 mmol m-2 d-1。II区表现出降低的GPP（平均1.1 mmol m-2 d-1）和ER率从6到36 mmol m-2 d-1，而无光区III表现出1和6 mmol m-2 d-1之间的ER。底栖 ER 在所有研究地点都超过 GPP，每日净生态系统代谢 (NEM) 范围从浅层地点的 - 22 mmol m-2 d-1 到 60 m 的 - 4 mmol m-2 d-1。在可比深度的硬底北极栖息地中观察到了类似的 NEM 动态。尽管夏季 GPP 相对较高，但沿海岩石栖息地似乎是净异养的。这可能是由于悬浮摄食群落对有机物质的主动减少，而这些群落对高纬度沿海生态系统的生物地球化学和生态功能至关重要。