Spatial patterns of larval supply and recruitment of the intertidal barnacle Chthamalus montagui in Sines region, SW Portugal
Mijatovic, M. (2011). Spatial patterns of larval supply and recruitment of the intertidal barnacle Chthamalus montagui in Sines region, SW Portugal. MSc Thesis. University of Evora. Laboratory of Marine Science: Evora. 33 pp.
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| Available in | Author |
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Document type: Dissertation
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| Keywords |
Developmental stages > Larvae
Population functions > Recruitment
Spatial variations
Chthamalus montagui Southward, 1976 [WoRMS]
ANE, Portugal [Marine Regions]
Marine/Coastal |
| Abstract |
Spatial patterns of larval supply and recruitment of Chthamalus montagui were studied in Sines region, SW Portugal, during summer 2010. Understanding processes influencing larval supply and recruitment, as well as their connection, is very important to understand barnacle population dynamic and structure Barnacles are key space-occupiers in rocky shore communities on European coasts and C. montagui is the most abundant barnacle species in SW Portugal. Recruitment was defined as the mean number of new settled individuals (cyprids and juveniles) per 25cm2 that have settled in different temporal scales (daily, bi-daily, three days and weekly), while larval supply was defined as number of cyprids per m3 close to recruitment sites. A spatial pattern of recruitment was observed among four shores: Cape of Sines, Marina, Oliveirinha and Porto Covo. Irrespective of the different temporal scale of recruitment measurement, recruitment was always higher in embayed (Marina and Oliveirinha) than in exposed shores (Cape of Sines and Porto Covo), which supports the hypothesis of a higher recruitment in the shores located immediately south of Cape of Sines. The hypothesis of a lower recruitment in Cape of Sines than in shores located south of this cape was not supported. Larval supply was about 10 times higher in Marina than in Porto Covo , which together with observed recruitment patterns favors the theory of a larval retention zone in the lee of Cape of Sines (major headland in this coast). Positive correlation between larval supply and recruitment was observed in Marina but not in Porto Covo. In Porto Covo, the two dates with a higher larval supply did not correspond to dates with a higher recruitment. A possible explanation for this decoupling could be the hydrodynamic characteristics of this shore where more wave inducted flows might have a negative influence on settlement. Another reason might be the patchiness of larval distribution. Further research on larval supply and behavior, and on recruitment are required in the nearshore of headlands, such as Cape of Sines. As a similar spatial pattern of larval supply and recruitment was observed ( higher in embayed shores located in the lee of the cape), it is possible to suggest that spatial patterns of recruitment of C. montagui in this region were mainly driven by larval processes instead of post-settlement processes. |
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