The influence of the rock mineralogy on population density ofChthamalus(Crustacea: Cirripedia) in the Ligurian Sea (NW Mediterranean Sea)

Abstract

Settlement, recruitment and survival of sessile marine species are driven by many biotic and abiotic factors. Among them, substrate mineral composition is generally a neglected topic, despite it proved to be a relevant contributing variable in driving the structure of benthic communities. Thanks to their ecology, Chthamalus species are a good proxy to test the role of substrate in affecting settlement and final population density on exposed rocky shores. Differences in the number of individuals were analysed in eight localities along the Eastern Ligurian Riviera (north-western Mediterranean Sea), from Portovenere to Manara Cape. In this sector of the Ligurian littoral, the coast is constituted by different rocks characterised by variable concentrations of calcite, silicates and quartz. This situation constitutes an ideal setting to evaluate the influence of mineral composition of the rocks in structuring the epilithic macrobiota communities in energetic splash zones and under similar physical pressures. Rocks rich in calcites turned out to be more suitable for Chthamalus species than substrates containing high amounts of silicates, and of quartz in particular. Additionally, also the grain size of the main mineral component of the rocks, determining in turn the surface roughness seemed to influence barnacle densities, with a significant preference for finer-grained substrates.

Population Characteristics of the Mid-Littoral Chthamalid Barnacle C. stellatus (Poli, 1791) in Eastern Mediterranean (Central Greece)

“…According to [4], C. stellatus in the supra-and midlittoral rocky shores of the NW Mediterranean Sea forms characteristic belts that can reach densities of up to 30,000 individuals per square meter. The average C. stellatus density recorded in the present study was similar to densities recorded in the Eastern (Habonim, Israel) [20], Central (Eastern Ligurian, Italy) [37], and Western Mediterranean (Spain) [2]. However, higher population densities were recorded in the Western (France) [2] and Eastern Mediterranean (Turkey) [39].…”

“…Although a number of studies have been carried out on the biology, distribution, and ecology of C. stellatus in the Mediterranean Sea [2,6,22,37], little is known of the occurrence and population characteristics of C. stellatus in the Eastern Mediterranean, apart from fragmented information (morphometry, distribution, ecology, reproduction) occasionally collected in the framework of several ecological studies [20,[38][39][40].…”

Surface Integrity Could Limit the Potential of Concrete as a Bio-Enhanced Material in the Marine Environment

“…Substratum material influence marine assemblages, although it generally plays a secondary role in the successional patterns, composition, and diversity of benthic assemblages compared to other environmental variables, such as food and larvae abundance, hydrodynamic exposure, and substrate orientation and microtopography (Liversage et al, 2014;Coombes et al, 2015;Canessa et al, 2019Canessa et al, , 2020. Therefore, the compounding and interplay of multiple factors and environmental conditions hinder our ability to assess the role of material on marine assemblages, particularly in heterogeneous and patchy ecosystems such as rocky shores (Raffaelli and Hawkins, 2012).…”

Lithology could affect benthic communities living below boulders

“…The lithological characteristics of the substrate may influence the richness and dynamics of hard-bottom benthic assemblages (Cerrano et al ., 1999; Bavestrello et al ., 2000, 2018; Cattaneo-Vietti et al ., 2002; Faimali et al ., 2004; Johansen, 2018; Canessa et al ., 2019, 2020). In fact, under comparable edaphic conditions, several communities were found to be structurally different on substrates of different lithology, in terms of presence and abundance of some sessile species (Coombes, 2011).…”

“…The influence of different rock types was particularly evident also for the supralittoral barnacle Chthamalus spp. which, in the Ligurian Sea, appeared more abundant on limestones than on marly substrates (Canessa et al ., 2019). Also, comparing barnacle populations living on different ophiolitic rocks, differences in density arose: they were abundant on serpentinite rocks and virtually absent on metagabbros (Bavestrello et al ., 2018).…”