June 2025 | Oceanography
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Operated by Ocean Networks Canada (ONC), the NEPTUNE
observatory comprises an 840 km fiber-optic cable extend
ing from Vancouver Island across the North American and
Juan de Fuca tectonic plates to connect five major node sites
to power and the internet (Barnes et al., 2007). The western
most Endeavour node supports the scientific sensors in the
heavily instrumented Endeavour Hydrothermal Vents MPA
(Table 1, Figures 3 and 4). Real-time data, archived data, and
data products from sensors in the axial valley and on the flanks
of the Endeavour Segment of the Juan de Fuca Ridge have been
available since 2010 through ONC’s digital infrastructure,
Oceans 3.0 (Owens et al., 2022). Regular expeditions using ships
and remotely operated vehicles (ROVs) to maintain infrastruc
ture also collect observations and physical samples to ground
truth and complement the sensor data. Internet connectivity
from the ships allows the Canadian and international science
community to participate from shore to conduct experiments
and sampling strategies to aid in developing a more complete
understanding of the physical, geological, and biological pro
cesses of this protected environment (Table 1).
TABLE 1. Summary of major disciplines, sensor technology, and geological, physical, chemical, and biological properties monitored and their scientific
and MPA monitoring impacts. MEF = Main Endeavour Field. RCM = Regional Circulation Mooring North and South.
MONITORING
EQUIPMENT
PROPERTIES
MEASURED
VENT FIELD/
SITES
(See Figure 3)
SIGNIFICANCE
(Value in MPA management)
KEY PUBLICATIONS
DISCIPLINE: GEOPHYSICS AND GEOCHEMISTRY
1. Seismometers and
accelerometers
Seismic ground
motions and
low-frequency
hydroacoustic signals
• RCM-N
• MEF
• Mothra
• Ridge Flank
• Node
Identify periods of seismic unrest driven by
tectonic spreading events that are linked
to changes in venting and/or eruptions.
Also, detect chimney collapses and activity
from baleen whales.
• Krauss et al., 2023
• Bohnenstiehl et al., 2004
• Smith and Barclay, 2023
2. Bottom pressure
recorders (BPR)
Vertical seafloor
movements and sea
level changes
• RCM-N
• MEF
• Ridge Flank
• RCM-S
• Node
• Mothra
Inflation/deflation can indicate changes
in the underlying magma chamber that
affects the hydrothermal system and can
precede spreading events.
• Barreyre and Sohn, 2016
3. Benthic and
Resistivity Sensors
(BARS), paired with
vent fluid samples
Temperature,
resistivity, and redox
potential
• MEF
• Mothra
Changes in chemical composition of
vent fluids over time, and the influence
of chemical and heat fluxes on the
composition and diversity of benthic vent
biological communities.
• Xu et al., 2017a
4. Vent imaging sonar
3D vent plume and
heat flux mapping
• MEF
Hydrothermal heat and chemical flux
variability is a fundamental control on the
ecosystem.
• Bemis et al., 2015
• Xu et al., 2014, 2017b
5. Serial gas tight
sampler
Fluid geochemistry
• MEF
Changes in chemical composition of vent
fluids over time, and the influence of
chemical and heat fluxes on the makeup
and diversity of benthic vent biological
communities.
• Seyfried et al., 2022
• Evans et al., 2023
6. Water samplers
(RAS-PPS)
Water geochemistry
and biology
• MEF
Diffuse venting and its effects on the
benthic ecosystem.
• Lelièvre et al., 2017
7. Sediment traps
Particulates from
vent plumes
• MEF
• West Flank
• South Axial
Hydrothermal venting and its effects on
the water column.
• Coogan et al., 2017
• Mills et al., 2024
• Beaupre-Olsen et al., 2025
DISCIPLINE: PHYSICAL OCEANOGRAPHY
1. Regional Circulation
Moorings
Ocean circulation
and water properties
(temperature, salinity,
and density)
• RCM-N
• NW Mooring
• RCM-S
• SW Mooring
Proxy measurement of the overall heat flux
variability to the ocean from hydrothermal
venting. Current circulation in and above
the axial valley controlling larval and vent
plume chemistry dispersal.
• Thomson et al., 2003
• Xu et al. 2014, 2017b
2. Conductivity,
temperature, and
depth (CTD)
Temperature, salinity
and density, dissolved
oxygen
• Node
Near seafloor water properties.
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