Mireille Consalvey PhD Thesis - University of St Andrews

Biof-11111
lol-Illatioll Lind dc\ clopnicill
disturbance. As the site started to recover, patches of the golden brown colour
associated with diatom biofilms were noted, these occurred throughout the site
and were not localised to the edges. 14 days after the disturbance, cells had
retumed to the top mm of the sediment and could be seen on and below the
sediment surface (Figure 3.31)). There was a visible increase in the bed height
over time at the disturbed site.
Water content
Associated with the removal of the surface layer of sediment was a
significant decrease in the water content of 42 % (FI, 4 ý 11.03, p=0.029) from
81+ 12 to 39 +4%. Subsequently the water content significantly increased over
the remaining 14 days (F4,1
0=3.96, p=0.03 5; Figure 3.4).
Chlorophyll a
After the removal of the surface sediment there was significantly less
chlorophyll a in the system (t = 9.18, n=3, p=0.012), falling from 176 + 18 to 8
3 pg chl a g-1 fdw, a decrease of 95%. The chlorophyll a content in the top I
mm of the sediment significantly increased subsequent to the disturbance event
(F6,13 ý 17.96; p