Temporal dynamics in the deep sea : time-series at food falls, seasonality in condition of grenadiers, and tides as time signals

The deep demersal community of the bathyal Porcupine Seabight is subject to environmental forcing on diel, seasonal and annual scales, in addition to the stochastic and transient influence of nutritional windfalls from the photic zone. The current regime at bathyal depth in the Porcupine Seabight is characterised by oscillations in current flow with periods of 12.4h and 14.8d. Increased current velocity and particle suspension in summer months synchronises well with the seasonal input of phytoplankton to the seafloor. These physical characteristics may constitute time signals in the deep ocean environment. Consumption and succession processes at bathyal food falls in the North Atlantic are suggestive of a fundamental difference in the community response between the North Atlantic and North Pacific oceans. The sinking of small cetacean carcasses constitutes a transient environmental impact on the local community structure which is not limited to the scavenging fauna. There is limited evidence of a response to the seasonal increase in available organic carbon in the white muscle of North Atlantic macrourids. This is in accordance with results from Pacific macrourids and suggests that the seasonal food pulse, experienced by the deep benthos under productive surface waters, is not greatly manifested at higher trophic levels. The successful adaptation of existing baited camera technology to incorporate an autonomous periodic bait-release system has enabled long-term high frequency time-series observations of deep-sea scavenging demersal fish and crustaceans to be made for the first time. An understanding of temporal environmental cues, and of the resultant interactions between organisms and their environment, effectively pervades the study of any aspect of organismal or population ecology.EThOS - Electronic Theses Online ServiceGBUnited Kingdo