Faunal activity rhythms influencing early community succession of an implanted whale carcass offshore Sagami Bay, Japan

Abstract

Benthic community succession patterns at whale falls have been previously established by means of punctual submersible and ROV observations. The contribution of faunal activity rhythms in response to internal tides and photoperiod cues to that community succession dynamism has never been evaluated. Here, we present results from a high-frequency monitoring experiment of an implanted sperm whale carcass in the continental slope (500 m depth) offshore Sagami Bay, Japan. The benthic community succession was monitored at a high frequency in a prolonged fashion (i.e. 2-h intervals for 2.5 months) with a seafloor lander equipped with a time-lapse video camera and an acoustic Doppler profiler to concomitantly study current flow dynamics. We reported here for the first time, to the best of our knowledge, the occurrence of strong 24-h day-night driven behavioral rhythms of the most abundant species (Simenchelys parasitica; Macrocheira kaempferi, and Pterothrissus gissu). Those rhythms were detected in detriment of tidally-controlled ones. Evidence of a diel temporal niche portioning between scavengers and predators avoiding co-occurrence at the carcass, is also provided. The high-frequency photographic and oceanographic data acquisition also helped to precisely discriminate the transition timing between the successional stages previously described for whale falls’ attendant communities.

Video Image Enhancement and Machine Learning Pipeline for Underwater Animal Detection and Classification at Cabled Observatories

“…These fixed platforms are being used to acquire image material from which animals of different species can be identified and then counted in a remote fashion, at a high frequency and over consecutive years [5][6][7][8][9]. Then, extracted biological time series are used to estimate how populations and species respond to the changes in environmental conditions (also concomitantly measured) [10][11][12][13][14].…”

Ecological variables for developing a global deep-ocean monitoring and conservation strategy

“…The specific features of deep-sea ecosystems and the measurement of a (Figure 3). For example, stationary, high-frequency time-lapse imaging over a period of years from cabled observatories can quantify megafaunal species richness 60 , with rovers and crawlers expanding local data acquisition to greater distances (several tens of m 2 ) 23,94,96 . Benthic landers 97 or AUVs and gliders could expand this observation capability across even wider spatial scales (several km 2 ) 98 .…”

Integrating Diel Vertical Migrations of Bioluminescent Deep Scattering Layers Into Monitoring Programs

“…At disphotic depths (i.e., >400 m), animals receive different temporal cues substituting sunlight, and utilize them in order to time these populational movements through a synchronization of their biological clocks. For crustacean decapods and fishes, this syncing can either be a result of direct environmental signals such as periodic hydrodynamism (i.e., internal tides and inertial currents; Wagner et al, 2007;Doya et al, 2014), changes in water temperature and salinity (Matabos et al, 2014) and phytopigment and oxygen concentrations (Chatzievangelou et al, 2016), or can be indirectly induced by the intermittent presence of massive numbers of predators and prey from a vertically migrating deep scattering layer, which rhythmically come in contact with the BBL (Ochoa et al, 2013;Aguzzi et al, 2018). In the case of the latter, this behaviorally-sustained benthopelagic coupling is to date poorly studied, due to the lack of a sufficient volume of continuous, long-term and high frequency timeseries at reference locations in the deep sea.…”

“…Moreover, new knowledge has been gathered on the tight linkages between benthic ecosystems in continental margins or abyssal oceanic plains and the pelagic zone above. Such linkages are either expressed as the settling of food falls and pulses of organic matter (Davies et al, 2006;Aguzzi et al, 2012bAguzzi et al, , 2018Thomsen et al, 2017), resuspension due to wind-driven upwelling (Allen and Durrieu de Madron, 2009), or are actively mediated by animal behavior, with vertical displacements taking place throughout the water column (Steinberg et al, 2008;Schmidt et al, 2011;Drazen and Sutton, 2017;Griffiths et al, 2017). These movements, when occurring on a diel (i.e., 24-h) basis, are known as Diel Vertical Migrations (DVMs; Brierley, 2014).…”