Fig 1.
Overview map of the cold-seep site in Barkley Canyon (northeast Pacific, Canada).
(A) The cabled observatory network, The Barkley Canyon node, site of Wally I crawler deployment is highlighted by a black dot. (B) High-resolution bathymetric map showing the region of Barkley Canyon investigated in the current study. The black dots within the canyon axis represent the crawler node with the nearby mid-canyon POD4 platform and other deeper nodes. (C) Image demonstrating the crawler Field Of View (FOV) as used to acquire the faunal data. (D) Map showing position of navigation waypoints arranged around the hydrate outcrop, the crawler (near waypoint no. 12 in this schematic) and the route from waypoint no. 10 to 14, representing the survey transect analysis area. The cold seep community was distributed on a soft bottom zone with no apparent emerging rocks. At the end of the transect analysis area, a 5 m depth cliff (dashed grey line) separated our study area from a from the gas-hydrate mound (E) The crawler in operation.
Fig 2.
Visual counts time series (i.e. from 14th February 2013 to 14th April 2014) for the 7 most abundant megafaunal species and the particular case of the grooved tanner crab, as reported by crawler video-imaging.
Average values (the grey dots) have been reported in order to better highlight the occurrence of seasonal trends. From left to right and from top to bottom taxonomic units are: Rockfish (i.e. Sebastidae); Sablefish (Anoplopoma fimbria); Hagfish (Eptatretus stoutii); Buccinid (Neptunidae); Small crab; Grooved tanner crab (Chionnecetes tanneri); Ctenophore (Bolinopsis infundibulum); and finally, Scyphomedusa (Poralia rufescens). Horizontal blue dashed lines correspond to the Midline Estimated Statistic of Rhythm (MESOR) and horizontal blue lines identify significant seasonal increases visual counts increases. Blue asterisks correspond to a month with no data due technical problems.
Fig 3.
Oceanographic parameters time series (i.e. from 14th February 2013 to 14th April 2014), as recorded by crawler and the nearby POD4 platform within the Barkley Canyon.
Average values (the grey dots) have been reported in order to better highlight the occurrence of seasonal trends. Gaps in data acquisition were due to instrument malfunctioning or downtime for the cabled infrastructure. These parameters are: (A) Velocity; (B) Water Density; (C) Temperature; (D) Turbidity; (E) Bakun Index; and finally, (F) Oxygen. We used up-looking and down-looking arrows to highlight upwelling and downwelling periods respectively.
Table 1.
Kruskal-Wallis test among the 14 months of the study for the 8 most abundant species with 13 degrees of freedom.
Fig 4.
Results of fitting environmental variables onto species ordination.
The increasing gradient of the environmental variable is indicated by the vector direction. The vector length is proportional to the correlation between the variable and the ordination pattern of the species. Species abbreviations are (taxonomical order; see S1 Table): Eel (Eelpout, Licenchelys spp.); Dov (Dover sole, Microstomus pacificus); Dee (Deep sea sole, Embassichthys bathybius); Pac (Pacific halibut, Hippoglossus stenolepis); Rat (Rattail, Coryphaenoides spp.); Roc (Rockfish, i.e. Sebastidae); Bac (Blackfin poacher, Bathyagonus nigripinnis); Sab (Sablefish, Anoplopoma fimbria); Hag (Hagfish Eptatretus stoutii); Sal (Salp, Salpidae); Dum (Dumbo octopus, Grimpoteuthis sp.); Squ (Squid Gonapus sp.); Buc (Buccinids, Neptunidae); Bri (Brittle star, Ophiuroidea); Sf1 (Starfish, Asteroidea); Sf2 (Starfish, Zoroasteridae); St3 (Hippasteria sp.); Hol (Holoturian, Holoturoidea); Her (Hermit crab, Diogenidae); Sca (Scarlet king crab, Lithodes couesi); Gro (Grooved tanner crab, Chionnecetes tanneri); Sma (Small crabs); Cte (Ctenophore, Bolinopsis infundibulum); Scy (Scyphomedusa, Poralia rufescens); Din (Dinner plate jelly, Solmissus sp.); Tra (Traquimedusa, Voragonema pedunculata).
Fig 5.
Biodiversity, richness and megafaunal species visual counts (i.e. from 14th February 2013 to 14th April 2014) time series, as reported by crawler video-imaging.
Biodiversity have been reported as mean per month Shannon Index (C) and Simpson Index (A). Similarly, we reported the species richness (D). Abundance (B) was normalized for the maximum transects of the study period (i.e. 48). Horizontal dashed lines correspond to the Midline Estimated Statistic of Rhythm (MESOR).