| Zusammenfassung: | Barnacle settlement was monitored at 5 sites separated by 50 to 250 m at Dike Rock, La Jolla, California, USA. Chthamalus spp. and Pollicipes polymerus settlement were spatially correlated at those sites. Within sites, settlement of the 2 species were correlated These results support the hypothesis of common onshore larval transport events for all sites and both species. Other spatiotemporal patterns were contrasting: 1 peak accounted for most of P. polymerus settlement, while there were 5 peaks of similar magnitude for Chthamalus spp. At 2 sites, settlement plates were installed at 2 heights in the intertidal; Chthamalus spp. settlement was similar at the 2 heights, while P. polymerus settlement was relatively different at the sites. Such spatial patterns may have resulted from a stronger behavioral component affecting settlement in P. Polymerus. These results suggest that, at scales of 100 m, temporal variability in settlement rate may be related to larval pool and physical transport processes, while spatial variability may be associated with behavioral response and substrate availability. Chthamalus spp. settlement was higher at sites where rocks were surrounded by unsuitable sandy substrate, possibly because settlement on available substrate is intensified where total suitable settlement area is relatively scarce. To test this, plates were installed at another site where suitable substrate was also scarce; as predicted, settlement was higher at both sites. At another study site in Medio Camino, Mexico, settlement became more predictable among sites along the rocky shore after the shoreline had been partially inundated by sand, further supporting this hypothesis. The proportion of unmetamorphosed settlers of Chthamalus spp., relative to total settlement, appeared to peak on particular days of the lunar cycle and was spatially correlated at the 5 sites. The periodicity of the peaks was close to the 14.75 d spring-to-neap cycle, suggesting that these peaks may be related to periodic shortimmersion times that did not allow the attached cyprids to metamorphose. Mortality of recently metamorphosed (≤ 1 d) Chthamalus spp. spat by physical damage was spatially variable.
|
|---|