Microhabitat associations in sessile invertebrates are largely determined by larval choices and early differential post-settlement mortality. Either process can have a broad community-wide impact when it regulates a cascade of foundation species, each facilitating multiple dependent taxa. On mixed sediments in shallow subtidal of Onega Bay (the White Sea, 65° N) cockles, barnacles and ascidians act as foundation species forming a multi-level facilitation cascade. Barnacles Balanus crenatus monopolize empty shells of the Greenland cockle Serripes groenlandicus, whereas ascidians (mainly Styela rustica) attach almost exclusively to barnacles and conspecifics. Field observations and experiments evidence that barnacles facilitate ascidians and suggest that individual patches shift from barnacle to ascidian dominance over time. Ascidian recruits are found on barnacles and almost never on Serripes shells, a pattern that may result either from substrate-specific larval settlement or from differential post-settlement mortality.

Here, we experimentally tested whether larval substrate preferences generate this pattern. In a laboratory experiment, fertilized Styela eggs were added to aerated seawater tanks containing Serripes shells with and without barnacles, and the distribution of ascidian juveniles was quantified after 10 days. Contrary to our hypothesis, settlement density on Serripes shells exceeded that on barnacles. This result rules out larval substrate selection as the primary mechanism and instead implicates substrate-specific post-settlement mortality of a secondary foundation species as the most likely driver of facilitation.

Morphological examination of recently collected barnacle specimens confirms the presence of Tesseropora atlantica (Cirripedia, Balanomorpha, Tetraclitidae) along the coastlines of Lanzarote and Fuerteventura, the easternmost islands of the Canary Archipelago. This constitutes the first documented occurrence of T. atlantica in the Canary Islands and establishes a new southern range limit for this relict species in the eastern Atlantic Ocean. Additionally, 16S and COI mitochondrial gene sequences were obtained for the first time for this species, allowing comparisons with related taxa. The study also explores plausible hypotheses concerning the species’ arrival in the Canary Islands.

Barnacles of the genus Conopea are obligate epibionts of gorgonians and antipatharians. The species Conopea saotomensis Carrison-Stone et al. 2013, previously only known from the islands of São Tomé and Príncipe and the coast of Gabon, is reported from the Bijagós archipelago, Guinea-Bissau, based on morphological examination and DNA barcoding of specimens. The new record extends the known range of the species about 3000 km to the northwest.

The rocky intertidal zone has a long history of ecological study with barnacles frequently serving as a model system to explore foundational theories. Parasites are often ignored in community ecology studies, and this particularly holds for true for the rocky intertidal zone. We explore the role of the isopod parasite, Hemioniscus balani, on its host, the acorn barnacle, Chthamalus fissus. We use the currencies of biomass and reproduction measured at the individual level, then applied to the population level, to evaluate the importance of this parasite to barnacle populations. We found H. balani can comprise substantial biomass in ‘apparent’ barnacle populations, sometimes even equaling barnacle biomass. Additionally, parasite reproduction sometimes matched barnacle reproduction. Thus, parasites divert substantial energy flow from the barnacle population and to near-shore communities in the form of parasite larvae. Parasites appeared to decrease barnacle reproduction per area. Potentially, this parasite may control barnacle populations, depending on the extent to which heavily infected barnacle populations contribute to barnacle populations at larger scales. These findings regarding the importance of a particular parasite for host population dynamics in this well studied ecosystem call for the integration of disease dynamics into community ecological studies of the rocky intertidal zone.

Space is one of the primary limiting resources for organisms on the intertidal rocky shore. This paper examined the effect of reduced density on key traits (mortality and growth) on the intertidal barnacles, Chthamalus montagui and Semibalanus balanoides, on the mid-shore in Plymouth, UK. Intra- and interspecific treatments comprising of C. montagui and S. balanoides were manipulated to reduce densities at two similar sites. Changes in mortality and operculum growth were assessed over an 8-week period using digital photography. Covariates of growth included nearest neighbour distance, competition between closest pairs and initial size. Conflicting patterns were observed when comparing growth rates between treatments and sites. At Site 1, interspecific treatments had a lower growth rate than intraspecific treatments, whereas at Site 2, interspecific growth rates were higher. ANCOVA showed that nearest neighbour distance had no significant effect on growth, but when comparing differences in growth of closest neighbouring pairs, C. montagui treatment showed evidence of competition whereas S. balanoides did not. ANCOVA analysis indicated no difference in growth between each outcome of pair competition, suggesting winners are initially bigger than losers. Comparisons of mortality between treatments indicated mortality over time with no significant differences observed between treatments, but response surface methodology (RSM) revealed no effects of competition on mortality of S. balanoides, but negative effects of both intra- and interspecific competition on C. montagui survivorship. Examination of natural populations of barnacles in the mid-shore indicated there was strong spatial variation in growth rates, perhaps driven by small-scale differences within sites.

This study presents for the first time the factors governing the recruitment in a rocky intertidal community of the Beagle Channel, Tierra del Fuego (54°51′S 68°29′W), Argentina. The aim of this study was to examine the effect of grazers and predators, free substrate availability and crustose coralline algae on the recruitment of the main sessile components of the intertidal: Notochthamalus scabrosus, Notobalanus flosculus, Mytilus chilensis, Perumytilus purpuratus and Aulacomya atra at three intertidal levels. For barnacles, the probability of recruitment was higher with grazers, while the contrary was observed for bivalves. The number of N. flosculus recruits was higher with increased substrate availability, while N. scabrosus recruited more with reduced free substrate in the first sampling. Mussel recruitment was higher with reduced free substrate. The highest probability of recruitment of N. scabrosus was observed at the upper level. Notably, this probability and the recruits per plot were higher at the mid level under uncaged-ORP treatment than expected for the mid level. The probability of bivalve and N. flosculus recruitment was higher at upper and lower levels, respectively. At the lower level, barnacle recruitment was higher on bare rock than on crustose coralline algae. Our results suggest that grazers increase the probability of barnacle recruitment, while the presence of sessile organisms enhances the density of mussel recruits. Almost no recruitment of bivalves was observed in ORPs over one year, showing that the secondary succession is slow in this environment.

We describe pathologies and post-mortem damage observed in specimens of the late Maastrichtian marine cheloniid turtle Allopleuron hofmanni. Shallow circular lesions on carapace bones are common and possibly illustrate barnacle attachment/embedment. Deep, pit-like marks are confined to the neural rim and the inner surface of peripheral elements; these may have been caused either by barnacle attachment or disease. A number of linear marks found on outer carapace surfaces are identified as tooth marks of scavengers, others as possible domichnia of boring bivalves. A fragmentary scapula and prescapular process displays radular traces of molluscs (gastropods and/or polyplacophorans; ichnogenus Radulichnus). These diverse types of bone damage suggest both live and dead marine turtles to have been commonly utilised by predators, scavengers and encrusters in the type Maastrichtian marine ecosystem.

Studies on the settlement and the subsequent recruitment of intertidal organisms are crucial steps in understanding their population structure in a particular bioregion. However, studying the recruitment of intertidal organisms such as barnacles, with two-phase life cycle, and understanding the determinants of recruitment is a complex problem. Many processes which operate during the pelagic pre-settlement phase and benthic post-settlement phase at different spatial and temporal scales can determine the fate of barnacle populations. In this study, observations were carried out on settlement and recruitment of the intertidal barnacle Balanus amphitrite from a tropical environment influenced by monsoons at spatial and temporal scales. Settlement and recruitment both showed significant temporal variations. In general, settlement and recruitment was lower during the monsoon season except during monsoon breaks. Consistency in settlement and recruitment was mostly observed during the pre-monsoon season, and it coincided with peaks in larval abundance observed during the same season. In general, settlement remained more or less similar on different types of substrata, whereas recruitment differed significantly. Temporal variations observed in settlement and recruitment of barnacles could be due to the influence of monsoons in this region, which leads to seasonal fluctuations in physical factors such as local hydrodynamics, that influence the retention and dispersal of larvae in the adult habitats, and could also be due to variations in the availability of food for the larvae and the settled populations.

Estuaries often show clearly recognizable changes in the distribution of organisms along environmental gradients from riverine to fully marine conditions. Surveys performed along the horizontal axis of the Plym and the Yealm Estuaries identified patterns of distribution and abundance of intertidal barnacles and provided a new assessment on the dominance exhibited by the non-native species Elminius modestus in these estuaries. Elminius modestus occurred furthest up in estuaries and was dominant along most of their length, with the exception of few sites closest to the sea; Chthamalus montagui had the most restricted degree of penetration up-estuary; and Semibalanus balanoides occurred at low abundances, with limits of penetration located between those of C. montagui and E. modestus. At many sites, E. modestus was the only barnacle species found. There were changes in the relative abundances of these three species in several particular locations within the Plym and the Yealm in comparison to previous accounts made in the last decades, which, in most cases led to increased dominance of E. modestus. This was mainly due to reductions in the abundances of S. balanoides. Physico-chemical conditions experienced after settlement, especially deposition of silt, exposure and salinity regime contribute to the patterns described here.

Predation has long been recognized as an important biological force driving community patterns in intertidal rocky shores throughout the world. Little is known, however, about the role of predation by mobile marine predators in shaping intertidal prey populations in Portuguese rocky shores. The abundance and population structure of crabs were assessed during nocturnal low-tides on two rocky shores to characterize potential predator species. To assess the effect of predation on intertidal species including limpets, barnacles and mussels, predator exclusion experiments using full cage, partial cage and no cage treatments, were set up for two months on two shores on the central Portuguese coast. Pachygrapsus marmoratus (Fabricius) and Eriphia verrucosa (Forsskål) were the most abundant crabs. Results from predator exclusion experiments suggested that predators do not exert a significant control on abundance of limpets, mussels or barnacles on the midshore during the experimental period. Despite the fact that these crabs are known to feed on the analysed prey, several factors may account for the observed absence of impact on prey abundance and these are discussed.

Barnacles are the common fouling organisms encountered in coastal waters around the world. In the present study, breeding biology of the intertidal barnacle Amphibalanus amphitrite (=Balanus amphitrite) was studied for a period of two years (July 2003 to June 2005) in the Kudankulam coastal waters. Results showed that A. amphitrite breeds throughout the year in the study area. A high percentage of individuals with free nauplii in the mantle cavity was observed during March 2004 (47.6%) and May 2004 (41.7%). Barnacles with fertilized eggs in the ovary were high during November 2004 (56%), March 2005 (46.7%) and April 2005 (42.8%). Overall, a peak breeding activity was observed during the March–May period. The breeding activity showed a significant positive correlation with surface water temperature and phytoplankton abundance.

The vertical distribution of fouling communities in Kudankulam coastal waters was studied for a period of one year (January to December 2005) by suspending wooden test panels at 1 m, 4 m and 7 m depths. Panels were submerged on short-term duration (15 days) and long-term basis (cumulative). The fouling organisms observed were barnacles, mussels, ascidians, polychaetes, amphipods and seaweeds. Recruitment was observed on the panels throughout the year with a considerable variation in relation to time and depth. On the short-term series, the fouling biomass varied from 0.218 to 1.23 g.dm−2 (dry wt) at 1 m, 0.23 to 4.72 g.dm−2 (dry wt) at 4 m and 0.241 to 5.66 g.dm−2 (dry wt) at 7 m depths. The biomass of the fouling community that colonized on the long-term panels ranged between 0.79 and 35 g.dm−2 (dry wt) at 1 m, 3.72 and 58.2 g.dm−2 (dry wt) at 4 m and 0.241 and 55.9 g.dm−2 (dry wt) at 7 m depths. At 1 m depth, macro-algae, ascidians (Botryllus tuberatus and Diplosoma sp.) and amphipods were the dominant species. Barnacles, tube worms and ascidians (Didemnum spp.) were abundant on the 4 m and 7 m depth panels. In general, the fouling community recruitment was higher at 4 m than 1 m and 7 m depths.