Turbidites and Benthic Faunal Succession in the Deep Sea: An Ecological Paradox.

摘要

Characteristics of benthic faunal succession following turbidity flows in the deep sea will vary according to the composition of turbidite materials, the spatial scales of deposition, the structure of initial benthic communities, and the frequency of depositional events. Despite a number of uncertainties regarding these effects, we make several generalizations in order to stimulate research on successional responses of benthic fauna to such episodic events. We find no support for a hypothesis formulated on the speculation by Heezen et al. (1955) that there should be, '... a high POSITIVE correlation between nutrient-rich turbidity current areas and a high standing crop of abyssal animals'. There is no definitive evidence for the extensive mining' of deeply deposited sediments reported by Jumars and Gallagher (1982) as being a foraging strategy for deposit-feeding benthos in turbidite sediments. The time for complete recovery of the benthic fauna following an episodic deposition of material on the scale of a turbidity flow is postulated to be hundreds to thousands of years. If viewed as a matrix of dynamic events, the effects of turbidity flows on abyssal fauna are on larger spatial and longer temporal scales than most other deep-sea disturbances and therefore provide the biological framework upon which many of the smaller and shorter term effects are superimposed. In interpreting and reconstructing causes for distributions of deep-sea organisms, benthic ecologists should incorporate a similarly holistic view (i.e., the turbidity current paradigm) as sedimentologists in order to better understand how the abyssal benthic fauna has adapted to episodic disturbances over geologic time.