Measurement of changes in marine benthic ecosystem function following physical disturbance by dredging
Abstract
Measuring the impact of physical disturbance on macrofaunal communities and
sediment composition is important given the increased demand for the exploitation and
disturbance of marine ecosystems. The aim of the present investigation was to
provide a comprehensive study about the extent to which the disturbance (especially
aggregate dredging) may affect benthic ecosystem function.
The first part of the thesis concerns a field investigation of the impacts of dredging on
the benthic community and related ecosystem function which was measured by
different approaches including traditional methods based on benthic community
structure and a more novel approach based on the functional traits of benthic
organisms. The assessment was done by comparing dredged sites (Area 222,
southeast England) with nearby undisturbed reference sites from the years 2001 to
2004 and in 2007. In general, low dredging intensity did not appear to impose great
impacts on the benthic community and related ecosystem function compared to the
higher intensity activity. Most of the analyses suggested that the community at the
high dredging intensity site had yet to recover at the end of this study period. Among
many factors related to the recovery of the benthic community was sediment
composition where gravel deposits appeared to support a faster biological recovery.
Meanwhile, the recovery of species with specific traits, such as tube-building and filter
feeding also indicate a faster recovery for the whole community.
The experimental work to determine different impacts of Hediste diversicolor on its
surrounding depending on its relative size is discussed in Appendix 1.
Type
Thesis, PhD Doctor of Philosophy
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