Title of article :
Preliminary observations of the effects of dredging intensity on the re-colonisation of dredged sediments off the southeast coast of England (Area 222)
Author/Authors :
S. E. Boyd، نويسنده , , D. S. Limpenny، نويسنده , , H. L. Rees، نويسنده , , K. M. Cooper، نويسنده , , S. Campbell، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2003
Abstract :
The re-colonisation of a site used for the extraction of sand and gravel for ca. 25 years off the southeast coast of the UK was
examined 4 years after the cessation of dredging. Effects of different levels of dredging intensity on the rate of macrofaunal re-colonisation
were investigated. Values of abundance and total numbers of species were significantly lower ð p < 0:05Þ in an area most
recently exposed to the highest level of dredging intensity compared with samples taken from an area of low intensity, and those
from a reference site. Differences between previously dredged sediments and the reference location were due to the reduced abundance
of a range of macrofaunal species characterising nearby sediments. Multivariate measures of community structure also indicated
that there were significant differences ð p < 0:01Þ between the macrofaunal assemblages in the areas exposed to different
dredging intensities. Sediment from the area exposed to the highest dredging intensity contained proportionally more sand than
other sampled sediments. The extent to which dredging intensity contributed to these differences was difficult to determine owing
to the absence of any baseline data. Despite this, univariate and multivariate analyses indicated a strong relationship between macrofaunal
community structure and dredging intensity at this site. Correlation analyses also demonstrated that the predominant influence
on the macrofaunal community was that of the level of dredging that took place in 1995, the last year that the licensed site
was dredged heavily.
Preliminary observations indicated that the fauna remained in a perturbed state some 4 years after cessation of dredging. Therefore,
relatively rapid recovery rates, commonly cited as 2–3 years for European coastal gravelly areas, should not be assumed to be
universally applicable. Implications for the future management and scientific study of marine aggregate extraction arising from preliminary
observations on the physical and biological status of this site are discussed together with the options for selecting a reference
site in the absence of baseline information.
Keywords :
aggregate extraction , dredging , recovery , Re-colonisation , Intensity , North Sea , macrofauna
Journal title :
Estuarine, Coastal and Shelf Science
Journal title :
Estuarine, Coastal and Shelf Science