a year in hypoxia epibenthic community responses to severe oxygen deficit at a subsea observatory in a coastal inlet一年缺氧浅海底社区应对严重的氧赤字在沿海海底观测站入口.pdfVIP

A Year in Hypoxia: Epibenthic Community Responses to Severe Oxygen Deficit at a Subsea Observatory in a Coastal Inlet Marjolaine Matabos1,2*, Verena Tunnicliffe1,3, S. Kim Juniper1,2, Courtney Dean1 1 School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada, 2 NEPTUNE Canada, University of Victoria, Victoria, BC, Canada, 3 VENUS, University of Victoria, Victoria, BC, Canada Abstract Changes in ocean ventilation driven by climate change result in loss of oxygen in the open ocean that, in turn, affects coastal areas in upwelling zones such as the northeast Pacific. Saanich Inlet, on the west coast of Canada, is a natural seasonally hypoxic fjord where certain continental shelf species occur in extreme hypoxia. One study site on the VENUS cabled subsea network is located in the hypoxic zone at 104 m depth. Photographs of the same 5 m2 area were taken with a remotely-controlled still camera every 2/3 days between October 6th 2009 and October 18th 2010 and examined for community composition, species behaviour and microbial mat features. Instruments located on a near-by platform provided high-resolution measurements of environmental variables. We applied multivariate ordination methods and a principal coordinate analysis of neighbour matrices to determine temporal structures in our dataset. Responses to seasonal hypoxia (0.1–1.27 ml/l) and its high variability on short time-scale (hours) varied among species, and their life stages. During extreme hypoxia, microbial mats developed then disappeared as a hippolytid shrimp, Spirontocaris sica, appeared in high densities (200 m22) despite oxygen below 0.2 ml/l. The slender sole Lyopsetta exilis was abundant in severe hypoxia and diminished as oxygen increased in the summer. This planktivore may be responding to changes in the depth of t