Ahyi Vent

Latitude: 20.438^οN Longitude: 145.029^οE Summit depth: 64 m bsl

Ahyi seamount is an active submarine arc volcano located in the Northern Seamount Province (Baker et al., 2008). This seamount erupted in April-May 2014, following the eruptions in 1979 and 2001 (Smithsonian Institution Global Volcanism Program). Evidence of eruptions in the form of thick plumes of particles suggests that Ahyi is extremely hydrothermally active and that the source of the activity is located near 150 m depth (Submarine Ring of Fire, 2014). One of the unusual benthic platyctenid ctenophores was documented during Okeanos explorations at Ahyi Seamount.

Table 1: Operations history for Ahyi vent

Ship/ Platform	Operation	Year	References
R/V Revelle	CTD sensor	2014 December	Submarine Ring of Fire, 2014
RR1413 R/V Roger Revelle/ Jason	XBT, Multibeam re-survey, CTD, EM122 multibeam logging	2014	Submarine Ring of Fire 2014-Ironman
TN-153 R/V T. G. Thompson	EM300 multibeam bathymetry	2004	Submarine Ring of Fire 2004
TN-153 R/V T. G. Thompson	EM 300 multibeam; CTD vertical cast	2003 February – March	Submarine Ring of Fire 2003
EX1605/Deep Discoverer	2016 June (Leg 3)	5	Okeanos Explorer 2016 dive summary

Table 2: Vent activity and host rocks

Activity and Host Rocks		References
Activity	Active	Baker et al., 2008; Embley et al., 2004; Embley et al., 2014
Activity	Last known eruption 2014 May	Smithsonian Institution, Global Volcanism Program
Host Rocks	Basalt	Bloomer et al., 1989; Embley et al., 2007; Resing et al., 2009

Table 3: Vent fluid characteristics

Activity and Host Rocks		References
Temperature (^_οC)	Low T (<100^οC)	Embley et al., 2007
Composition	Small ³He anomaly	Resing et al., 2009
Δ³He (fM)	0.07	Resing et al., 2009

Table 4: Vent Biology

General name		Phylum	Class / Order	Family	Genus/Species	References
Eukaryota	Comb jellies	Ctenophora	Tentaculata	Platyctenida		Okeanos Explorer 2016 dive summary
	Cusk eel	Chordata				Okeanos Explorer 2016 dive summary
	Duckbill	Chordata				Okeanos Explorer 2016 dive summary
	Flatfish	Chordata				Okeanos Explorer 2016 dive summary
	Octopus	Mollusca				Okeanos Explorer 2016 dive summary
	Sand tiger shark	Chordata				Okeanos Explorer 2016 dive summary
	Sea slug	Mollusca	Gastropod			Okeanos Explorer 2016 dive summary
	Anemone	Cnidaria			Alicia ?	Okeanos Explorer 2016 dive summary
	Shrimp	Arthropoda				Okeanos Explorer 2016 dive summary
	Snake mackerel	Chordata			Rexea ?	Okeanos Explorer 2016 dive summary

Images:

Unusual benthic platyctenid ctenophores documented at Ahyi Seamount.
Unusual benthic platyctenid ctenophores
Octopus was seen on Dive 5 at Ahyi Seamount (note: search “Ahyi”)
A curious octopus

Video Links:

Ahyi Seamount.
Using a CTD to detect plumes at Ahyi (note: video at the end).
Range of sessile organisms at Ahyi.
What is that?

References:

Baker, E. T., Embley, R. W., Walker, S. L., Resing, J. A., Lupton, J. E., Nakamura, K., de Ronde, C. E. J., Massoth, G. J., 2008. Hydrothermal activity and volcano distribution along the Mariana arc: Journal of Geophysical Research 113 (B8), 1-16.
Embley, R. W., Baker, E. T., Chadwick, W. W. JR., Lupton, J. E., Resing, J. A., Massoth, G. J., Nakamura, K., 2004. Explorations of Mariana Arc. Eos 85 (4), 37-44.
Embley, R. W., Baker, E. T., Butterfield, D. A., Chadwick, W. W. Jr., Lupton, J. E., Resing, J. A., de Ronde, C. E. J., Nakamura, K., Tunnicliffe, V., Dower, J. F., Merle, S. G., 2007. Exploring the submarine ring of fire: Mariana Arc- Western Pacific, Oceanography 20, 68–79.
Embley, R., Tamura, Y., Merle, S., Sato, T., Ishizuka, O., Chadwick, W., Wiens, D., Shore, P., Stern, R., 2014. Eruption of South Sarigan Seamount, Northern Mariana Islands: Insights into Hazards from Submarine Volcanic Eruptions. Oceanography 27 (2), 24-31.
Resing, J. A., Baker, E. T., Lupton, J. E., Walker, S. L., Butterfield, D. A., Massoth, G. J., Nakamura, K., 2009. Chemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc. Geochemistry, Geophysics, Geosystems 10 (2), 1-23.

Website References:

Smithsonian Institution, National Museum of Natural History: Global Volcanism Program, http://volcano.si.edu/volcano.cfm?vn=284141 (accessed 11/22/2015)
Submarine Ring of Fire 2014 http://oceanexplorer.noaa.gov/explorations/14fire/logs/logs.html (accessed 11/20/2015)
Submarine Ring of Fire 2004 http://oceanexplorer.noaa.gov/explorations/04fire/logs/photolog/photolog.html (accessed 11/22/2015)
Submarine Ring of Fire 2003 http://oceanexplorer.noaa.gov/explorations/03fire/logs/summary/summary.html (accessed 11/22/2015)

Cruise Reports:

NOAA Okeanos Explorer 2016 https://docs.lib.noaa.gov/OEDV/Okeanos_Explorer_2016_EX1605/Leg_3/doc/dive_summaries/EX1605L3_DIVE05_20160622_ROVDiveSummary_Final.pdf (accessed 11/22/2015)
Submarine Ring of Fire 2014 –Ironman http://www.pmel.noaa.gov/eoi/marianas/SRoF-Ironman-2014-CruiseReport-withdivelogs.pdf (accessed 2/27/2017)