Abyssal polychaete assemblages along latitudinal gradients of productivity in the equatorial Pacific and North Atlantic Oceans

• Main Author: Glover, Adrian G.
• Format: Thesis
• Language: English
• Published: 2000
• Subjects: Pacific; North Atlantic; North East Atlantic
• Online Access: https://eprints.soton.ac.uk/42090/; https://eprints.soton.ac.uk/42090/1/0000341.pdf

Patterns in polychaete abundance, body size and diversity were investigated at 12 sites between 4300 and 5000 m in the central Pacific and the north-east Atlantic. In the central Pacific, three of the sites (EqPac 0N, 2N and 5N) were observed to lie under high surface productivity regimes, and they were known to receive significant accumulations of food-rich phytodetrital material. The EqPac 9N, HOT 23N, DOMES A, ECHO 1 and PRA sites, which did not receive phytodetritus, were used as control sites with which to investigate the effect of this phytodetrital input. In the north Atlantic, one of the sites (PAP) was known to receive phytodetrital input, and one of the sites (MAP) had been subjected to a large-scale natural disturbance in the form of a turbidite emplacement. All specimens were identified to species level. Two families, the Pilargidae and Cirratulidae were selected for a more detailed alpha taxonomy assessment. New characters were developed for the identification of cirratulid thoracic fragments. Benthic polychaete abundance was correlated with surface productivity in both the Pacific and Atlantic Oceans. There was some evidence to suggest that there was a stronger benthic-pelagic link in the Pacific Ocean, where small changes in surface productivity generated larger changes in abundance than in the Atlantic Ocean. When data from previous studies are included, it is suggested that at levels of surface productivity above 200 g cm -2 yr -1 , there is an upper limit to benthic polychaete abundance. Significant differences in body size between sites were found at species level, family level and for the entire polychaete taxon. At a species level, several abundant cosmopolitan deposit feeding species showed reduced body size in the food-rich phytodetrital sites. The only species to show increased body size in the food-rich sites were two predatory species. Polychaetes inthe Atlantic Ocean responded more strongly in terms of body size reduction in phytodetritalsites than they did in the EqPac sites. Three ...