Mireille Consalvey PhD Thesis - University of St Andrews

IIa lit ei--"
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light). Cores (n = 7) were randomly placed in each of 7 tanks with the conditions
outlined in Table 4.3.
Table 4.3. Experimental Conditions. Normal low tide taken as light on and water
off (representing in situ conditions)
Conditions as low tide Question:
period begins What stimulates upwards migration?
Lights on
Water (tide) on
Does light stimulate upwards migration?
Lights on
Is upwards migration stimulated by a
Water (tide) off combination of water & light?
Lights off
Water (tide) off
Lights off
Water (tide) on
Does water stimulate upwards migration?
Is upwards migration a response to an
internal cue?
Conditions as "non-nal" Question:
low tide period ends
Lights go off
Water (tide) stays off
What stimulates downwards rrýgration?
Does light stimulate downwards
migration?
Lights go off
Is downwards migration stimulated by a
Water (tide) goes on combination of water & light?
Lights stay on
Water (tide) goes on
Lights stay on
lWater (tide) stays off
4.3. Results
4.3.1. Tay Estuary (June 1999)
Does water stimulate downwards
migration?
Is downwards migration a response to an
linternal cue?
Chlorophyll a and water content (Tay Estuary 1999)
The mean chlorophyll a content at the end of the experiment was 26.07
2.47 ýLg chl a g-1 fdw or 0.035 + 0.0012 [tg chl a mm 2. The mean water content
was 54 +I%.
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