June 2025

Oceanography | Vol. 38, No. 2

14

GEOLOGY AND SEAFLOOR HABITAT

The Endeavour MPA hosts hydrothermal vent ecosystems

whose formation and persistence are directly linked to the

dynamic geological and tectonic processes of the Juan de

Fuca Ridge. Understanding this interplay through continu­

ous, multidisciplinary monitoring is foundational to effective

MPA management.

The Endeavour Segment is an intermediate-rate spreading

center (full rate: ~52 mm yr–1) (DeMets et al., 2010; Krauss et al.,

2023) characterized by a 10 km long and 1 km wide axial val­

ley flanked by rift crests rising 100–150 m above the valley floor.

Extensive and vigorous hydrothermal venting occurs within the

axial valley focused at five main active vent clusters spaced about

2–3 km apart (Figure 1; Kelley et al., 2012). The Main Endeavour

(MEF) and Mothra fields have received significant scientific

attention and are currently being monitored by sensors con­

nected to the NEPTUNE observatory. The High Rise and Salty

Dawg fields (see Figure 1) are designated for minimally intru­

sive studies and outreach opportunities (Fisheries and Oceans

Canada, 2010) and have no cabled sensors.

The uniqueness of hydrothermal venting regions, with respect

to other deep-sea benthic habitats, stems from the chemical flux

and exchange of heat between the ocean and the seafloor and

the geologically rapid change of the seafloor morphology due

to local tectonic dynamics. This leads to a chemically and phys­

ically extreme environment that hosts the specialized life that

has physiologically and biologically adapted to the geologically

controlled environment. Although vent ecosystems are rare and

their global extent is small, their contribution to the understand­

ing of life and their ecosystem functions and services are sig­

nificant and are considered ideal candidates for designation as

Vulnerable Marine Ecosystems and recommended for Area-

Based Management Tools (e.g., Menini and Van Dover, 2019).

The Endeavour Segment features a combination of active and

inactive chimneys, edifices, and mounds along its axial valley.

The active structures cluster into the five major vent fields with

more than 400 inactive structures as well as the diffuse venting

sites interspersed among them. Conceptually, they are geolog­

ically connected, and the entire ridge segment can be consid­

ered a single temporally and spatially varying vent field driven

MONITORING

EQUIPMENT

PROPERTIES

MEASURED

VENT FIELD/

SITES

(See Figure 3)

SIGNIFICANCE

(Value in MPA management)

KEY PUBLICATIONS

DISCIPLINE: BIOLOGY

1. Video cameras

Video, paired with

other sensors

(i.e., temperature)

• MEF

• Mothra

Track biological community structure and

responses to venting physico-chemistry

dynamics.

• Cuvelier et al., 2014, 2017

• Lelièvre et al., 2017

• Carter, 2025

• Robert et al., 2012

• Lee et al., 2015

2. Biological samples

Whole specimens,

tissue, assemblages

and e-DNA

• High Rise

• MEF

• Mothra

Characterization of vent and vent-

periphery communities (from microbes to

megafauna).

• Perez and Juniper, 2016, 2017

• Perez et al., 2023

• Lelièvre et al., 2018

• Georgieva et al., 2020

3. Colonization

experiments

Community

recolonization/

ecological succession

• MEF

Investigate faunal colonization (from

microbes to macrobenthos) simulating

recovery from natural perturbations

(e.g., eruptions).

• Ongoing studies

4. Passive larval

trap collectors

Benthic invertebrate

larvae

• MEF

Larval ecology and genetic connectivity

among different vent, vent periphery,

and background deep-sea benthic

communities.

• Ongoing study

5. ROV video

surveys, including

photogrammetry

Habitat and benthic

community dynamics

• MEF

• Mothra

• High Rise

Track, at larger spatial scales, temporal

changes of vent community composition

and responses to natural perturbations.

• Neufeld et al., 2022

DISCIPLINE: SOUNDSCAPES

1. Cabled hydrophone

arrays

Intensity and direction

of broadband sound

• MEF

Vent activity monitoring, earthquake

detection (near and distal), marine-mammal

detection and monitoring.

• Smith and Barclay, 2023

2. Deep acoustic

lander (autonomous,

Dalhousie University)

Sound velocity,

pressure, conductivity,

temperature, salinity;

intensity and direction

of broadband sound

• MEF

Water-column properties affecting sound

propagation, vent activity monitoring.

• Smith and Barclay, 2023

TABLE 1. Continued…