Figure 1.
Location of the E2 and E9 hydrothermal vent fields on the East Scotia Ridge (ESR) back-arc basin, Southern Ocean.
Figure 2.
The E9 hydrothermal vent field.
(Top-right) Ship acquired swath bathymetry of the ‘Devils Punchbowl’ collapsed caldera. Black outline denotes the E9 vent field and area of ROV-based swath. (Main bathymetric map) High-resolution ROV-acquired mulitbeam bathymetry of the E9 vent field. Waypoints denote areas of interest (A) Flat sheet lavas, typical background substrate of the E9 vent field (B) Most northern point of low-lying hydrothermal activity (C) “Twin Peaks” (D) “Black and White” (E) “Carwash” (F) “Temple” (G) “Marshland” (H) “Marsh Towers”; (I) “Ivory Towers” chimney complex (J) “Pagoda” chimney complex (K) “Launch Pad” chimney complex (L) “Needle” (M) “Windsor Castle”.
Figure 3.
Vertical mosaic images created using sequential image captures from the 1080i video footage (A) “Black & White” 9.7m edifice (−60°02.568, −29°58.905).
Dive 140, 2400 m depth, ROV heading 090° (B) “Carwash” 9.7 m edifice (−60°02.572, −29°58.904). Dive 140, 2401 m depth, ROV heading 128° (C) “Ivory Towers” 6.7 m edifice (−60°02.809, 29°58.708). Dive 142, 2395 m depth, ROV heading 090°.
Figure 4.
Horizontal mosaic of an area of low-lying diffuse flow around “Twin Peaks”.
Dive 139, 2401 m depth. ROV heading 358°. Area mosaiced ∼280 m2. Laser scale = 10 cm (A) unidentified Octopod (B) cluster of stichasterid seastars (C) pycnogonid genus Colessendeis sp. predating on actinostolid (D) small area of diffuse flow (E) barnacles on ‘y’ – shaped fracture (F) “Kiwa assemblage B” and “gastropod assemblage” (G) “Kiwa assemblage A” associated with peak ROV mounted CTD temperature measurement (6.03°C) (H) small area of diffuse flow in collapsed basalt.
Figure 5.
Images captured from high-definition video footage of the key fauna from the E9 vent field.
Unless stated otherwise, laser scale or scale bar = 10 cm (A) Anhydrite assemblage adjacent to Kiwa assemblage A (B) Kiwa assemblage B (C) gastropod assemblage (D) barnacle assemblage (E) anemone assemblage (F) Actinostolid observed egesting a Kiwa n. sp. carapace (indicated by white arrow) (G) Un-described seven-armed stichasterid seastar (H) Predatory seastar observed preying on a Kiwa n. sp. (I) On-board still image of Lepetodrilus n. sp. on carapace of large individual of Kiwa n. sp. 62 individuals counted, Scale = 5 cm (J) Lepetodrilus n. sp in association with the gastropod assemblage (5900–6200 individuals m−2).
Table 1.
Faunal composition of the seven identified assemblages from the E9 vent field, Southern Ocean.
Figure 6.
(A) Barnacle assemblage with associated Lepetodrilus n. sp. 20,172–56,904 individuals m−2. (B) Line plot indicates the total number of limpets in each 5 cm increment towards an area of rising hydrothermal effluent. Bar plot indicates average number of limpets per capitula. Error bars are standard deviation.
Figure 7.
Minimum and maximum distance of assemblages from varying fluid exits.
(A) Assemblage distances from the vertical high-temperature black smoker exit on the “Black & White” edifice (B) Assemblage distances from the vertical diffuse flow exits on the “Carwash” edifice. (C) Assemblage distances from the horizontal diffuse flow exit indicated by ROV CTD peak temperature measurement on the “Twin Peaks” mosaic (see Figure 4 & Figure 8). (D) Image illustrating transition from assemblage to assemblage.
Figure 8.
Temperature and positional data acquired from the “Twin Peaks” horizontal mosaic survey (A) Dotted line indicates the ROV position, offset to represent the 3-chip camera location.
Temperature plot is an interpolation using data acquired from the ROV mounted CTD. (B) Digitised faunal assemblages of the “Twin Peaks” low-lying diffuse flow area. Assemblage types are colour coded and presented in the legend. Peripheral fauna are indicated using the following symbols (+) Kiwa n. sp. (○) unidentified Octopod (•) un-described Stichasterid seastar (x) Colessendeis sp. pycnogonid.
Figure 9.
Quantitative 2D analyses for each assemblage type were performed on a comparable vertical face of each upstanding hydrothermal structure.
(A) “Ivory Towers” (B) “Black & White” (C) “Carwash” (D) Comparative bar chart of percentage surface coverage of defined faunal assemblages associated with each edifice.
Table 2.
Surface area coverage of assemblages for each mosaiced chimney structure, including minimum abundances calculations for the dominant taxa of each assemblage type based on a monolayer distribution.
Figure 10.
Idealised schematic of the spatial distribution of the E9 vent field faunal assemblages with increasing distance from a vent fluid exit.
This spatial pattern of zonation radiates in both (A) horizontal and (B) vertical directions.