With an increase in demand on deep-sea resources comes a need for appropriate and
effective management of this ecosystem. The establishment of a representative network
of deep-sea Marine Protected Areas offers one tool with which to address the
conservation needs of the deep sea. While a number of deep-sea habitats have been
identified as vulnerable to anthropogenic activities (e.g. cold-water coral reefs and
sponge aggregations), poor knowledge of the distribution of these habitats hinders
conservation efforts and network planning, and thus we need habitat maps. With
improvements in acoustic data resolution acquired from the deep sea, and the ability to
cover large areas rapidly, the use of acoustic techniques in mapping biological habitats
is growing. Multibeam bathymetry and its derived terrain variables can potentially
provide important information that can aid in the delineation and characterisation of
biological communities. A necessary prelude to mapping is therefore the definition of
biological assemblages for use as mapping units.
Two megahabitat features (seamount and submarine canyons) were sampled using
acoustic and ground-truthing to characterise and map the distribution of benthic
assemblages. Species were identified as distinct morpho-types and catalogued, and still
images quantitatively analysed. Standard multivariate community analysis was
undertaken to define distinct faunal assemblage that may act as mapping units. Those
clusters identified by the SIMPROF routine were taken against a set of criteria to
reject/accept as robust assemblages that may be used as mapping units. Twenty two
benthic assemblages or biotopes were defined from multivariate analysis of quantitative
species data, 11 from the SW Approaches and 11 from Anton Dohrn Seamount, and a
further one from video observations (SW Approaches). Taken against current
definitions, 11 of these were considered as Vulnerable Marine Ecosystems (VME).
Diversity was measured to compliment the comprehensive description of biotopes. The
use of multivariate diversity indices proved better for comparing diversity of biotopes as
it captures a more than one aspect of diversity of the community. Two biotopes were
common to both megahabitat features, cold-water coral reef habitats, and those from
Anton Dohrn Seamount were more diverse than from the SW Approaches.
Modelling techniques were employed to test the relationship between biotopes and
environmental and geophysical parameters, which may be used as surrogates to map
VME. Generalised Additive Models of Vulnerable Marine Ecosystems revealed
multibeam bathymetry and its derived parameters to be significant surrogate for
mapping the distribution of some assemblages, particularly those that appear to be
influenced by current regime; whilst not so well for those whose distribution is not so
strongly current driven e.g. soft sediment communities. In terms of deep-sea mapping,
the use of multibeam can prove a useful mapping tool if the resolution of the data is at
an appropriate scale that will identify meso-scale geomorphological features, such as
cliff-top mounds, that may act as proxies for occurrence of biotopes, but this
relationship is still unclear. Surrogates were used to map VME across the seamount and
submarine canyons, and full coverage maps were produced for all biotopes occurring on
these megahabitat features.
Date of Award | 2012 |
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Original language | English |
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Awarding Institution | |
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Supervisor | John Spicer (Other Supervisor) |
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- Habitat mapping
- Community analysis
- Biotopes
- Deep-sea
Mapping Deep-Sea Features in UK Waters For Use in Marine Protected Area Network Design
Davies, J. S. (Author). 2012
Student thesis: PhD