The Scotian Shelf harbors unique aggregations of the glass sponge Vazella pourtalesii that provides an important habitat for benthic and pelagic fauna. Recent studies have shown that these sponge grounds have persisted in the face of strong inter-annual and multi-decadal variability in temperature and salinity. However, little is known of these environmental characteristics on hourly-seasonal time scales. This study presents the first hydrodynamic observations and associated (food) particle supply mechanisms for the Vazella sponge grounds, highlighting the influence of natural variability in environmental conditions on sponge growth and resilience. Near-bottom environmental conditions were characterized by high temporal resolution data collected with a benthic lander, deployed during a period of 10 months in the Sambro Bank Sponge Conservation Area. The lander was equipped with temperature and oxygen sensors, a current meter, a sediment trap and a video camera. In addition, water column profiles of temperature and salinity were collected in an array across the sponge grounds from high to lower sponge presence probability. Over the course of the lander deployment, temperature fluctuated between 8.8–12°C with an average of 10.6 ± 0.4°C. Dissolved oxygen concentration was on average 6.3 mg l–1, and near-bottom current speed was on average 0.12 m s–1, with peaks up to 0.47 m s–1. Semi-diurnal tidal currents promoted constant resuspension of particulate matter in the benthic boundary layer. Surface storm events episodically caused extremely turbid conditions on the seafloor that persisted for several days, with particles being resuspended to more than 13 m above the seabed. The carbon flux in the near-bottom sediment trap peaked during storm events and also after a spring bloom in April, when fresh phytodetritus was observed in the bottom boundary layer. While resuspension events can represent a major stressor for sponges, limiting their filtration capability and remobilizing them, episodes of strong currents and lateral particle transport likely play an important role in food supply and the replenishment of nutrients and oxygen. Our results contextualize human-induced threats such as bottom fishing and climate change by providing more knowledge of the natural environmental conditions under which sponge grounds persist.

中文翻译：

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苏格兰大陆架 Vazella Pourtalesii 玻璃海绵地面近床环境条件的季节性变化

苏格兰大陆架拥有独特的玻璃海绵 Vazella Pourtalesii 聚集地，为底栖动物和远洋动物群提供了重要的栖息地。最近的研究表明，面对温度和盐度的强烈年际和年代际变化，这些海绵地面仍然存在。然而，人们对每小时季节性时间尺度上的这些环境特征知之甚少。本研究首次展示了 Vazella 海绵地面的流体动力学观察和相关（食物）颗粒供应机制，突出了环境条件的自然变化对海绵生长和弹性的影响。近底环境条件的特​​点是使用底栖着陆器收集的高时间分辨率数据，在 Sambro 银行海绵保护区部署了 10 个月。着陆器配备了温度和氧气传感器、电流计、沉积物捕集器和摄像机。此外，从海绵存在概率从高到低，以阵列形式收集温度和盐度的水柱剖面图。在着陆器部署过程中，温度在 8.8-12°C 之间波动，平均为 10.6 ± 0.4°C。溶解氧浓度平均为 6.3 mg l-1，近底流速度平均为 0.12 ms-1，峰值高达 0.47 ms-1。半昼夜潮汐流促进了底栖边界层中颗粒物质的不断再悬浮。海面风暴事件偶发性地导致海底极度混浊，并持续了数天，颗粒被重新悬浮到海床上方 13 m 以上。近底沉积物捕集器中的碳通量在风暴事件期间达到峰值，也在 4 月春季开花后达到峰值，当时在底部边界层观察到新鲜的植物碎屑。虽然再悬浮事件可能是海绵的主要压力源，限制了它们的过滤能力并使它们重新活动，但强流和横向粒子传输的事件可能在食物供应以及营养和氧气的补充中发挥重要作用。我们的研究结果通过提供有关海绵地面持续存在的自然环境条件的更多知识，将人类引起的威胁（例如海底捕捞和气候变化）置于背景下。近底沉积物捕集器中的碳通量在风暴事件期间达到峰值，也在 4 月春季开花后达到峰值，当时在底部边界层观察到新鲜的植物碎屑。虽然再悬浮事件可能是海绵的主要压力源，限制了它们的过滤能力并使它们重新活动，但强流和横向粒子传输的事件可能在食物供应以及营养和氧气的补充中发挥重要作用。我们的研究结果通过提供有关海绵地面持续存在的自然环境条件的更多知识，将人类引起的威胁（例如海底捕捞和气候变化）置于背景下。近底沉积物捕集器中的碳通量在风暴事件期间达到峰值，也在 4 月春季开花后达到峰值，当时在底部边界层观察到新鲜的植物碎屑。虽然再悬浮事件可能是海绵的主要压力源，限制了它们的过滤能力并使它们重新活动，但强流和横向粒子传输的事件可能在食物供应以及营养和氧气的补充中发挥重要作用。我们的研究结果通过提供有关海绵地面持续存在的自然环境条件的更多知识，将人类引起的威胁（例如海底捕捞和气候变化）置于背景下。限制它们的过滤能力并重新激活它们，强流和横向粒子传输的发作可能在食物供应以及营养和氧气的补充中发挥重要作用。我们的研究结果通过提供有关海绵地面持续存在的自然环境条件的更多知识，将人类引起的威胁（例如海底捕捞和气候变化）置于背景下。限制它们的过滤能力并重新激活它们，强流和横向粒子传输的发作可能在食物供应以及营养和氧气的补充中发挥重要作用。我们的研究结果通过提供有关海绵地面持续存在的自然环境条件的更多知识，将人类引起的威胁（例如海底捕捞和气候变化）置于背景下。