Publication Abstract

Vertical migration of macrofauna following sediment placement on intertidal mudflats : an in situ experiment

S.G. Bolam, M. Schratzberger and P. Whomersley

The intertidal placement of fine-grained dredged material to create or improve mudflats and saltmarshes (or ‘beneficial use schemes’) is currently been viewed as a sustainable approach to coastal sediment management. However, our limited of understanding of the recovery of macrofauna following placement is a key factor which presently limits this practice in the UK to small-scale, field trials. We conducted a field experiment to investigate the vertical migratory capability of temperate mudflat species following intertidal sediment placement. We explicitly examined how vertical migration was affected by sediment characteristics (organic content and particle size) and placement depth (6 and 16 cm).

Four main taxa were sufficiently abundant for statistical analysis. While Tharyx sp.A. and Streblospio shrubsolii showed poor vertical recovery with only 6 cm of sediment overburden, Tubificoides benedii showed some recovery while Hydrobia ulvae exhibited good recovery, even with 16 cm of sediment overburden. We also showed that while increases in the sand content of dredged material from 16 % to 38 % had no noticeable effect on recovery, increased sediment organic content from 0.8 % to 3.4 % had detrimental effects on vertical migratory activity. We discuss the relevance of these findings with respect to management options for beneficial use schemes.

Reference:

S.G. Bolam, M. Schratzberger and P. Whomersley. 2003. Vertical migration of macrofauna following sediment placement on intertidal mudflats : an in situ experiment. pp 49-60 In: CEDA Dredging Days 2003, Amsterdam, Netherlands.