Figure 1.
Map showing the location of the study site at Viana do Castelo, Portugal, and detailed view of the shore indicating the positions of the sampling sites A and B.
Figure 2.
Monthly egg settlement from Fucus spiralis and Fucus guiryi (a) and Fucus vesiculosus (b) in site A (dark bars) and site B (grey bars) between February 2002 and July 2003.
Periods when sampling was not carried out are represented by n.d. (no data). Insets show the data plotted on a Logarithmic scale.
Figure 3.
Total number of oogonia (closed symbols) and number of mature oogonia (open symbols) per conceptacle (n = 5 receptacles, ± SE) from Fucus spiralis (plot a), Fucus guiryi (plot b), and Fucus vesiculosus (plots c and d) between February 2002 and July 2003.
Figure 4.
Daily egg settlement from Fucus spiralis (panels c and d), Fucus guiryi (panels e and f) and Fucus vesiculosus (panels g–j), between 1 April and 31 September 2002 (left hand panels) and 1 April and 31 July, 2003 (right hand panels).
Values are means ± SE from n = 10 (Site A) or n = 15 (site B) sampling disks. Tidal amplitude (black line) and lunar phase for the sampling period are shown in a) and b); grey shading indicates the timing and duration of major settlement events from both species/sites.
Figure 5.
Relationship between tidal amplitude and time after sunrise on days with peak gamete release from a) Fucus vesiculosus, and b) Fucus ceranoides.
Data are from Pemaquid, Maine, USA (Oct 8 and Nov 8, 1999; from Berndt et al. [9]), Viana do Castelo, Portugal (Jun 23, Jul 22, 2003; this study), and Port Erin, Isle of Man (Jul 17, Aug 1–3, 1989, and Jul 22, Aug 4, 1990; from Brawley [10]).
Figure 6.
Relationship between the timing of high tide and egg settlement (shown as a percentage of the maximum) in a) Fucus guiryi, and b) Fucus vesiculosus at site A and B.
Data are daily samples taken between February 2002 and July 2003 (n = 10 and 15 disks at site A and B, respectively, ± SE).
Figure 7.
Egg release during 2 h sampling intervals (n = 5 ± SE) by a) Fucus spiralis, b), Fucus guiryi, and c) Fucus vesiculosus at two replicate sites/species (open and closed symbols) during four neap tide periods in June and July 2009.
Grey lines are tidal amplitude and grey bars the dark periods during the daily cycle.
Figure 8.
Pareto double Log10 plot of cumulative rank distribution of egg release.
Data were collected during 2 h sampling intervals over four neap tide periods in June and July 2009 (see text and Fig. 7). Summary results of the regressions are 1) Fucus spiralis: Log(y) = 2.853−0.476*Log(x), R2 = 0.981; 2) Fucus guiryi: Log(y) = 2.767−0.488*Log(x), R2 = 0.970, and 3) Fucus vesiculosus: Log(y) = 2.812−0.345*Log(x), R2 = 0.987.