Meeting Abstract
Deep-sea communities are linked with processes occurring at the ocean’s surface despite their relative distance apart. Time-series observations have highlighted the responses of benthic animals to episodic pulses of food and rhythmic changes in surface climate; however, in most of these cases observations have been made on mobile fauna. How and whether sessile animals on the abyssal plain can also respond behaviorally to changes in surface climate has largely been ignored. We combed through 30 years of time-lapse camera data from Station M, a long-term study site on the abyssal plain off the coast of California, to survey behaviors and activity of sponges and benthic cnidarians. The sessile fauna of the abyssal plain initially appear static but time-lapse observations yield a new, long-term perspective showing the dynamic lifestyles of these animals. Several hexactinellid sponge species rhythmically contracted and expanded back to full size, a process taking days to weeks that coincides with a reduction in filter feeding by one-third to nearly one-half. In general, cnidarian behaviors were at shorter timescales, occurring more frequently and with less time spent contracted than sponges. Zoanthids had rhythmic contraction behaviors whereas the cerianthid anemone Bathyphellia australis retracted its body into its tube with no apparent pattern or periodicity. These observations expand on the natural history of these difficult-to-observe taxa. Furthermore, the behaviors of these sponges and cnidarians may affect their role in nutrient cycling.
