AUTHOR=Seabra Maria Inês , Penteado Nélia , Cruz Teresa , Hawkins Stephen J. 

TITLE=Variability and connectivity in populations of different limpet species across rockpool-generated mosaic landscapes

JOURNAL=Frontiers in Marine Science

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1206159

DOI=10.3389/fmars.2023.1206159

ISSN=2296-7745

ABSTRACT=<p>Limpets are keystone grazers on rocky shores. We studied spatial patterns of four co-occurring patellids (<italic>Patella ulyssiponensis</italic>, <italic>Patella depressa</italic>, <italic>Patella rustica</italic>, <italic>Patella vulgata</italic>) and one siphonariid (<italic>Siphonaria pectinata</italic>) across rockpools and their surrounds. Our approach considered each rockpool as a concentric system of three micro-habitats where limpets were censused (species, counts, and size of individuals): inside rockpool, edge zone, and surrounding open-rock. The whole intertidal zone was sampled on six rocky shores with contrasting landscape variability (amount of open-rock and other micro-habitats) in Southwest Portugal. Additionally, open-rock surfaces far away (&gt;25cm) from rockpools were surveyed on the mid-shore. Three groups of predictors (“physical, habitat-composition, and connectivity variables”) were assessed for each rockpool system. Limpets of various sizes of the three most common species—<italic>P. ulyssiponensis</italic>, <italic>P. depressa</italic>, and <italic>S. pectinata</italic>—were found to coexist inside and outside rockpools on all shores, with rockpools extending their vertical distribution upwards. <italic>Patella vulgata</italic> was rare; <italic>P. rustica</italic> was absent from rockpools and their edges. Intra-specific connectivity (correlations in density of the same species between adjacent micro-habitats) showed a decreasing gradient with distance from the pool, being sharper for <italic>P. ulyssiponensis</italic> (a largely rockpool-resident) than for <italic>P. depressa</italic> and <italic>S. pectinata</italic> (suggesting their emergence from rockpools to edges and surrounding open-rock). Abundance and size structure of both <italic>P. depressa</italic> and <italic>S. pectinata</italic> were similar on mid-shore open-rock surrounding rockpools and far from rockpools. Landscape variability explained distribution of <italic>P. depressa</italic> (shores with less open-rock had more and smaller limpets). Habitat-composition (assemblages and substrata) was more important than physical predictors in explaining among-rockpool variability of each limpet species. Densities of <italic>P. ulyssiponensis</italic> and <italic>P. depressa</italic> inside rockpools were positively associated with cover of coralline algae and negatively associated with sand cover. Less explanatory power was found in predictive models of <italic>S. pectinata</italic>, suggesting a more opportunistic nature. There was limited evidence of inter- or intra-specific competition of the three species in rockpools and open-rock. Competition between <italic>P. ulyssiponensis</italic> and <italic>P. depressa</italic> was most likely in rockpool edges. Rockpool-generated mosaic landscapes are linked by intra-specific connectivity of limpet populations and modulated by interactions among different limpet species.</p>