June 2025

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Oceanography | Vol. 38, No. 2

20

directly tied to tidal cycles (Mat et al., 2020). Combined, these

findings provide compelling evidence of more direct dynami­

cal influences of the surface ocean and the planetary climate on

deep ocean hydrothermal vent ecosystems than was previously

thought. Furthermore, they highlight the importance of long-

term observations supported by the NEPTUNE observatory in

detecting faunal community changes at Endeavour in response

to upper ocean climate variability.

A second seafloor camera installed at Mothra vent field in

2020 is further contributing to our understanding of the tem­

poral dynamics of highly mobile and non-vent exclusive ben­

thic megafauna, such as zoarcid and macrourid fishes and

decapod crustaceans, by employing machine learning auto­

matic classification and counting of the most abundant taxa

(Carter, 2025; Figure 5e). NEPTUNE’s multiple video cam­

era platforms, which cover a range of vent habitat types and

incorporate embedded pipelines for automated imagery pro­

cessing, can be used to inform MPA managers of long-term

trends in faunal abundance and diversity (Aguzzi et al., 2020;

Ortenzi et al., 2024).

A recent study focused on non-vent benthic megafauna

inhabiting peripheral habitats (e.g.,  Figure 5f,g) located as

much as a few kilometers away from the main active Endeavour

vent sites. ROV video surveys conducted at Main Endeavour

and High Rise vent fields revealed diverse assemblages domi­

nated by slow growing sessile animals, such as rosselid vase

sponges, alcyonacean corals, and crinoids (Neufeld et al., 2022).

A key finding was that corals were nearly absent and rosselid

sponges were found in very low abundances within 25–50 m of

active chimneys but became progressively more abundant and

diverse moving away from the vents; they occurred predomi­

nantly at bare basalt ridges and on walls of inactive sulfide chim­

neys. Species richness measured using rarefaction curves were

significantly higher at inactive chimneys but never reached

asymptotic values, demonstrating an undersampled and incom­

plete species catalogue (Neufeld et al., 2022). These results high­

light the importance of studies that consider vent-​periphery

habitats covering a wider, landscape-scale habitat heterogene­

ity in order to uncover the true ecological “sphere of influence”

(sensu Levin et  al., 2016) and the true biodiversity conserva­

tion and MPA management value surrounding any hydrother­

mal vent system. Furthermore, parallel studies at Endeavour,

such as Georgieva et al. (2020) that investigated microbiomes of

vent-periphery sponges in the genus Spinularia, uncovered puta­

tive chemosynthetic Gammaproteobacteria (Thioglobaceae and

Methylomonaceae) directly providing nutrition to the sponges,

indicating that typical non-vent megafauna still benefit from

symbiont associations deriving from dispersed vent fluids in the

surroundings of active hydrothermal sites. Given deep-sea mas­

sive sulfide deposit mining activities being proposed for inactive

vent sites around the globe (Jamieson and Gartman, 2020), the

Endeavour Segment, which is protected under the TḥT MPA,

therefore becomes a natural study and monitoring site for fur­

ther exploration of the importance of vent-periphery habitats,

biodiversity, and resilience to human impacts.

Photogrammetric mosaics produced by repeated flyovers

using remote or autonomously operated vehicles with dedicated

camera systems (Van Audenhaege et al., 2024) allow monitoring

of ecological dynamics from vent-edifice to centimeter scales.

Motion photogrammetry has been used to generate highly accu­

rate habitat terrain models, with high predictive power for faunal

assemblage distribution (Gerdes et al., 2019). The most import­

ant community structuring variables in these habitat models

are often distances to diffuse and black fluid exits, as well as the

height of the chimney complex (Gerdes et al., 2019; Girard et al.,

2020). At Endeavour, regular maintenance visits to the obser­

vatory with a scientific ROV enabled assembly of a sequence of

3D photogrammetry models from repeat visits to the Mothra

vent field. Data are being analyzed, with preliminary results pro­

viding insights into how chimney accretion and erosion affect

spatial distribution and community succession of vent fauna

(Tom Kwasnitschka, GEOMAR Helmholtz Centre for Ocean

Research Kiel, pers. comm., October 22, 2024).

Additionally, ROV survey data (video and navigation) col­

lected during observatory maintenance expeditions can be

mined to produce kernel density “heat maps” of significant eco­

system components, indicators, and stressors (Juniper et  al.,

2019). As the observatory maintenance and operations occur

on a yearly basis, these maps are continuously updated and are

used as essential MPA spatial management tools by quantita­

tively assessing research pressure on the vents (e.g., ROV tracks

and sampling efforts), hotspots of biodiversity associated with

vents (typical chemosynthetic communities), and vent periph­

ery habitats (e.g.,  corals and sponges) (Fisheries and Oceans

Canada, 2025). An interactive map is available online with mul­

tiple geographical information system (GIS) layers of all obser­

vatory maintenance activities, spatial distribution of vent­

ing habitat structures (e.g.,  active and inactive edifices), and

associated biodiversity.

CONCLUSION

Since deployment of scientific instrumentation at the Endeavour

MPA in the fall of 2010, a total of 103 peer-reviewed papers have

been published, as well as 10 dissertations and one book chap­

ter (in The Sound of Hydrothermal Vents, Smith and Barclay,

2023). Of the 103 journal articles, 51 were based directly on sen­

sor data archived in Oceans 3.0 and/or discrete samples collected

on maintenance expeditions, while 28 articles used ONC data

along with data from other sources (e.g., earthquake, acoustics).

The remaining 24 articles were either review/overview articles

or articles supported by research enabled by ONC. The internet

access and the power offered by the deep-sea observatory pro­

moted the development of new hydrothermal vent and seafloor

monitoring technology, while the research resulted in significant

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