The Mediterranean mid-littoral zone is inhabited by two sympatric chthamalid barnacles: Chthamalus stellatus and Euraphia depressa, C. stellatus extends from the high midtidal zone, above the algal belt, to the supra-littoral fringe, E. depressa is restricted to the uppermost intertidal levels in wave-beaten places and to cryptic habitats lower on the shore within the belt of C. stellatus. Previous studies have suggested that the reason for the fragmented distribution pattern of E. depressa is competitive displacement by the sympatric C. stellatus, following random settlement. This hypothesis is in agreement with the common model of zonation suggested by Connell that lower distribution limits are determined by biotic factors (competition and predation), while upper limits are set by physical factors. It is hard to test the validity of this model for this barnacle pair since the early ontogenetic stages of the species are morphologically indistinguishable, hindering our ability to understand distribution processes. Using 16S mtDNA as a genetic marker in a multiplex PCR system, cyprids and spats were individually identified. Settlement and recruitment rates were assessed using settlement plates, and the effect of post-settlement processes was tested with transplantation of settlers between zones. Results showed different strategies in each species: settlement of E. depressa was habitat-specific, while settlement of C. stellatus was random. Shifting individuals of C. stellatus to the high and cryptic zones resulted in high mortality; however, exposing juveniles of E. depressa that settled in artificially cryptic low shore habitat to C. stellatus presence had no effect on their survival. These finding do not agree with the formerly suggested hypothesis that zonation is mainly determined by post-settlement factors, and that the interspecies boundary is determined by interspecific competition, implying that competition model cannot be adapted to Mediterranean intertidal zonation and that other models, dominated by physical enforcement and pre-settlement recruitment-limiting factors, may prevail in this ecosystem.
|Number of pages||10|
|Journal||Journal of Experimental Marine Biology and Ecology|
|State||Published - 1 Feb 2015|
Bibliographical noteFunding Information:
The authors would like to thank Dr. Noa Simon-Blecher of Bar-Ilan University (BIU) and Dr. Yaron Tikochinsky of the Mikhmoret Maritime College for their beneficial advice on building the molecular identification system. The group of biotechnology students of Mikhmoret: Alissa Aronson, Iris Weisman, Amir Cohen, Inbal Nussbaum, and Naomie Bensoussan, assisted in the tedious work of calibrating the molecular system. We also would like to thank the members of the Marine Community Ecology lab at the Israel Oceanographic and Limnological Institute for the invaluable help in the field. This research is part of the MSc work of TGH in Bar-Ilan University under the supervision of YA and GR. The research was partly supported by a Marie Curie IRG grant (No 249147 ) to GR. [SS]
© 2014 Elsevier B.V.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science