162 
Mar Ecol Prog Ser 338: 159-168, 2007 
Fig. 3. Time series for year 2003. (a) Colonisation of traps by Carcinus maenas 
megalopae; (b) wind direction; (c) predicted residual currents. Bar along top 
abscissa shows times of spring tides (arrows), and new (•) and full (O) moons 
variable (e.g. current component) whereby correlation 
at a negative lag = X indicates that the response vari 
able at Time iwas predicted by the predictor variable at 
Time t-X. 
RESULTS 
Temporal patterns 
The settlement season extended from the 
end of June to the end of August. Colonisa 
tion varied within and among years; in 
some cases there were peaks followed by 
periods of low or no colonisation. In 2003, 
there were 2 main periods of colonisation 
(Fig. 3a) separated by a period with very 
few larvae (density <5 d" 1 ): the first coloni 
sation period occurred between Days 184 
and 203, with moderate to high rates of 
colonisation (5 to 40 ind. d' 1 ) and was char 
acterised by 2 peaks. The second period 
(Days 214 to 224) showed moderate coloni 
sation rates (5 to 15 ind. d" 1 ). Winds from 
the NW dominated the first colonisation 
period (Fig. 3b), with wind shifting to the 
SE and then to the SW 2 to 3 d before the 
end of this period and remaining in that 
quadrant until the end of July. In August, 
wind was variable, although it was chiefly 
from the NE, Residual currents towards the 
NW or SW were predicted for the first 
colonisation period (Fig. 3c), but they 
shifted towards the NE as wind directions 
rotated; during the next 11 to 12 d pre 
dicted currents were towards the NE, In 
August, currents shifted again towards the 
NW a few days before the second period of 
larval colonisation. Spectral analysis of the 
2003 data (Fig. 4a) revealed a major peak 
every 26 d and smaller peaks every 4 to 5 d 
and 16 d. 
In 2004 (Fig. 5a), colonisation rate was initially low 
(5 to 6 ind. d" 1 : Days 173 to 190), but increased to mod 
erate levels thereafter. Due to technical problems it was 
not possible to continue the time series during August. 
Fig. 4. Carcinus maenas. Spectral analysis of time series of colonisation rate by megalopae in 3 consecutive years