A Year in Hypoxia: Epibenthic Community Responses to Severe Oxygen Deficit at a Subsea Observatory in a Coastal Inlet
Date
2012
Authors
Matabos, M.
Tunnicliffe, Verena
Juniper, S. Kim
Dean, C.
Journal Title
Journal ISSN
Volume Title
Publisher
PLOS ONE
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 the diurnal migration of
zooplankton. While the squat lobster Munida quadrispina was common at all times, juveniles disappeared in fluctuating
conditions. Despite low oxygen conditions, animal densities were high indicating that the risk from hypoxia is balanced by
factors such as food availability and escape from less tolerant predators. As hypoxia increases on the continental shelf, we
expect benthic communities to become dominated by low diversity, hypoxia-tolerant species of low commercial
significance.
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Citation
Matabos, M., Tunnicliffe, V., Juniper, S.K., & Dean, C. (2012). A Year in Hypoxia: Epibenthic Community Responses to Severe Oxygen Deficit at a Subsea Observatory in a Coastal Inlet. PLos ONE, 7(9). https://doi.org/10.1371/journal.pone.0045626