Community ecology of hydrothermal vents at Axial Volcano, Juan de Fuca Ridge, northeast Pacific
Date
2018-11-20
Authors
Marcus, Jean
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Abstract
Hydrothermal vents are deep-sea hot springs. Vents are home to luxuriant
assemblages of animals that colonize the warm venting fluids. High biomass is fed by
microbes that use hydrogen sulphide and other reduced chemicals in the vent fluid as an
energy source to fix inorganic carbon. Individual vents may persist for a few years to
several decades. The specialized animals must find new vents, cope with changing fluid
conditions and foster their offspring.
The composition and structure of vent communities vary in space and time. My
research at Axial Volcano, a seamount on the Juan de Fuca Ridge (JdFR) in the northeast
Pacific, aims to find pattern in this variation and to propose viable hypotheses of the
mechanisms driving the patterns. Axial is an ideal location as it supports mature vent
fields (venting for over 15 years) and young, developing vents initiated by a volcanic
eruption in 1998. Thus, I was able to study both temporal and spatial variation in vent
communities at the same site and relate patterns of developing assemblages to patterns
observed at longer-lived vents.
Pattern detection is the first critical step in any community ecology study as it
justifies and focuses the search for process. I have refined existing statistical methods
and developed novel techniques to test for pattern in vent species distributions and
abundances. I modified an existing null model approach and showed that species
distributions among sixteen vents differ from random in a long-lived (>15 years) vent
field. I also developed a novel null model to confirm that initial patterns of community
assembly seven months following the Axial eruption differ from random recruitment of
species and individuals to new vents.
My description of the community response to the Axial eruption is the first
quantitative report of patterns of vent colonization and succession. My work documents
that new vents are colonized quickly (within months) and that initial assemblages are
variable. However, rapid community transitions and species replacements within the first
few years cause new assemblages to resemble mature vents by 2.5 years post-eruption.
Three habitat factors correlate with the development of nascent vent assemblages: the
recruitment timing of the tubeworm Ridgeia piscesae post-eruption, vent age and vent
fluid hydrogen sulphide content. I also describe a new polynoid polychaete discovered
colonizing the new vents in high densities.
My major contribution to vent community ecology is revealing species patterns
through extensive sampling and rigorous statistical methods. These patterns are a
necessary step towards understanding the processes that structure vent communities:
they direct future research effort towards the key species and generate hypotheses to be
experimentally tested. My work also elucidates how vent species respond to habitat
destruction and creation, which is critical information for effectively managing Canada's
only hydrothermal vent Marine Protected Area on the JdFR.
Description
Keywords
Hydrothermal vent ecology, Juan de Fuca Ridge, Hydrothermal vents