Ecological controls on density, diversity and community structure of Polar Megabenthos
Polar deep water environments are poorly studied. This thesis investigates fundamental questions as to the nature of controlling factors on megabenthic communities as well as the diversity, densities and distributions of organisms present. The deep (1000-1660m) Faroe-Shetland Channel harbours an Arc...
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| Format: | Thesis |
| Language: | English |
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2005
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| Online Access: | https://eprints.soton.ac.uk/25131/ https://eprints.soton.ac.uk/25131/1/Jones_D_2005_PhD%2520%25281%2529.pdf |
| Summary: | Polar deep water environments are poorly studied. This thesis investigates fundamental questions as to the nature of controlling factors on megabenthic communities as well as the diversity, densities and distributions of organisms present. The deep (1000-1660m) Faroe-Shetland Channel harbours an Arctic fauna owing to cold deepwater intrusions from the Norwegian Sea. Despite the relatively low species richness of the megabenthos, variation in faunal composition with depth is apparent. Two distinct communities were identified in the north and south of the channel. Epibenthic megafauna in the south are dominantly filter feeders and in the north deposit feeders. Megabenthic diversity and density decreased to the northeast of the channel. Lebensspuren number and area increase northwards in the Channel. The increase in bioturbation and deposit feeder abundance is concurrent with an increase in fine sediment quantity. The response of a deep, Arctic benthic community to physical disturbance was investigated in the Faroe-Shetland Channel. High levels of physical disturbance, characterised by smothering of the seabed resulted in significant but variable reductions in megafaunal abundance (up to 92.3%). Reductions in diversity, particularly in species richness, were apparent between disturbed (ES(500) = 12.9) and undisturbed areas (ES(500) = 20.6). The implications of selective removal of taxa on ecosystem function and recovery are discussed. Low level disturbance had comparatively little effect on the communities. The effects varied in nature depending on motility and functional group (e.g. motile scavenger abundances were maximal at intermediate distances from disturbance). Effects of physical factors on the megabenthos of Kangerdlugssuaq Fjord mouth in Arctic Greenland were investigated. Large reductions in faunal density (1881 to 60,132 individuals ha-1) and increases in diversity (H´ = 0.93-2.54), through increases in richness (ES(220) = 7.6-18.8) and reductions in dominance (Berger-Parker Index = 0.77-0.38), were ... |
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