2 research outputs found
High-Frequency Patterns in the Abundance of Benthic Species near a Cold-Seep – An Internet Operated Vehicle Application
Three benthic megafaunal species (i.e. sablefish Anoplopoma fimbria; pacific hagfish Eptatretus
stoutii and a group of juvenile crabs) were tested for diel behavioral patterns at the
methane hydrates site of Barkley Canyon (890 m depth), off Vancouver Island (BC, Canada).
Fluctuations of animal counts in linear video-transects conducted with the Internet
Operated Deep-Sea Crawler ªWallyº in June, July and December of 2013, were used as
proxy of population activity rhythms. Count time series and environmental parameters were
analyzed under the hypothesis that the environmental conditioning of activity rhythms
depends on the life habits of particular species (i.e. movement type and trophic level). Nonlinear
least squares modeling of biological time series revealed significant diel periods for
sablefish in summer and for hagfish and crabs in December. Combined cross-correlation
and redundancy (RDA) analyses showed strong relationships among environmental fluctuations
and detected megafauna. In particular, sablefish presence during summer months
was related to flow magnitude, while the activity of pacific hagfish and juvenile crabs in
December correlated with change in chemical parameters (i.e. chlorophyll and oxygen concentrations,
respectively). Waveform analyses of animal counts and environmental variables
confirmed the phase delay during the 24 h cycle. The timing of detection of sablefish
occurred under low flow velocities, a possible behavioral adaptation to the general hypoxic
conditions. The proposed effect of chlorophyll concentrations on hagfish counts highlights
the potential role of phytodetritus as an alternative food source for this opportunistic feeder.
The juvenile crabs seemed to display a cryptic behavior, possibly to avoid predation, though
this was suppressed when oxygen levels were at a minimum. Our results highlight the
potential advantages such mobile observation platforms offer in multiparametric deep-sea
monitoring in terms of both spatial and temporal resolution and add to the vastly understudied
field of diel rhythms of deep-sea megafauna