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A checklist of the northwestern Black Sea supralittoral fauna is presented. It includes 18 species: Ophelia bicornis, Namanereis pontica, Cryptorchestia cf. garbinii, Deshayesorchestia deshayesii, Orchestia montagui, Orchestia gammarellus, Orchestia montagui, Armadilloniscus ellipticus, Halophiloscia cf. couchii, Ligia italica, Tylos ponticus, Chthamalus stellatus, Microeuraphia depressa, Thalassomyia frauenfeldi, Donacilla cornea, Myosotella myosotis, Truncatella subcylindrica, and Melarhaphe neritoides. This paper provides distribution maps for this species in the northwestern Black Sea, based on field studies. The changes that occurred in species composition are discussed. The regional IUCN categories are proposed.

Concentrations of heavy metals and trace elements in marine environments have increasingly become a problem for several ocean ecosystems, due to increments in pollution. Habitats daily exposed to extreme conditions, such as the intertidal rocky platforms and pools, are more vulnerable to pollution effects. In the coast of Punta del Hidalgo (Tenerife, Spain), we have located a water-treatment plant that could be pouring periodically pollutants to the near shore. We studied coverage and survival rates of the cirriped Chthamalus stellatus inhabiting the intertidal near the sewage pipe of the water plant of ​Punta del Hidalgo and in a control area in a proximate location. Concurrently, water samples from intertidal pools were obtained from both affected and control areas in order to corroborate the presence of pollutants, analyzing the concentrations of metals and trace elements. The results obtained clarified that the area near the underwater outfall presented higher percentage of coverage and mortality of C. stellatus than the control zone. The analysis of metal content in water samples also showed higher concentrations of metals for the affected area compared to the control one. We therefore propose the use of survival rates of populations of C. stellatus in the intertidal as bioindicators of metal pollution.

On marine rocky shores, several physical, chemical and biological processes operate to maintain the benthic assemblages’ heterogeneity, but among the abiotic factors, the composition and texture of the rocky substrata have been only sporadically considered. However, biomineralogical studies have demonstrated an unsuspected ability of the benthic organisms to interact at different levels with rocky substrata. Therefore, the mineralogy of the substratum can affect the structure of benthic communities. To evaluate this hypothesis, the macrobenthic assemblages developed on two different ophiolitic rocks (serpentinites and metagabbros) in contact at a restricted stretch of the western Ligurian Riviera (western Mediterranean Sea), with identical environmental and climatic conditions, were analysed. Samplings were carried out at four bathymetric levels (+1m, 0m, -1m, and -3m respect to the mean sea level) and the analysis of the data evidenced differences in terms of species distribution and percent coverage. Algal communities growing on metagabbros were poorer in species richness and showed a much simpler structure when compared to the assemblages occurring on the serpentinites. The most widely distributed animal organism, the barnacle Chthamalus stellatus, was dominant on serpentinites, and virtually absent on metagabbros. Our results suggest a complex pattern of interactions between lithology and benthic organisms operating through processes of inhibition/facilitation related to the mineral properties of the substratum.

Two species of chthamalid barnacles are well established from the upper to the lower limit of the midlittoral zone on the rocky shores of the North Adriatic Sea: Chthamalus stellatus, Poli and Chthamalus montagui, Southward. The present study deals with the vertical distribution and abundance for each species at two localities of the Istrian peninsula coast (North Adriatic Sea). For this purpose chthamalid populations were monitored in 2015 along the Slovenian marine coast (Bay of Koper, Gulf of Trieste) and along the Croatian marine coast, near Rovinj (west Istrian coast), both on limestone. The main aim of the study was to establish if there was a relationship between the vertical distribution and abundance of these two species at different spatial scales: small (between sites, about 1 kilometer) and large (between localities, 10s of kilometers). The selected localities are slightly different in tidal range, in orientation and wave exposure. Three sites were randomly selected at each locality and two transects per tidal level (upper, middle and lower) were chosen on each site. The abundance of each chthamalids species in 1 dm2 plots was determined at three different tidal levels along each transect. The results indicated that the vertical distribution of C. montagui and C. stellatus was very similar between localities and even among sites, but their abundance varied. At both localities, C. montagui was more abundant in the upper and middle tidal levels, while C. stellatus was more abundant at the lower tidal level. It was also found that C. montagui was more abundant in sheltered conditions (Bay of Koper), while C. stellatus on the coast more exposed to the wave action (near Rovinj), at all tidal levels.

A twenty-five year (1994–2018) survey at 10 rocky sites within Lough Hyne Marine Reserve (SW Ireland) showed that, despite considerable spatial and temporal patchiness, three barnacle species (Chthamalus stellatus, Semibalanus balanoides, and Austrominius modestus) declined in overall abundance in the early 2000s, particularly at three sites. There was no clear response of A. modestus or C. stellatus to the cold winters of 2010 and 2011. In 2004, however, S. balanoides declined suddenly, but showed a slight recovery after the cold winter of 2010 to maintain sparse populations in the lough, but remained abundant outside the lough. A fourth species, Chthamalus montagui, showed a different pattern, with wide fluctuations in abundance but no overall decline. Changes in the Atlantic Multidecadal Oscillation may have influenced the overall composition of barnacle populations. Rising maximum air temperatures, resulting in high body temperatures recorded for A. modestus even during mild days, are suggested to have impacted the barnacle populations as a result of the prolonged aerial exposure times caused by the lough's asymmetric tidal pattern.

Poli’s stellate barnacle, Chthamalus stellatus Poli, populates the Mediterranean Sea, the North-Eastern Atlantic coasts, and the offshore Eastern Atlantic islands. Previous studies have found apparent genetic differences between the Atlantic and the Mediterranean populations of C. stellatus, suggesting possible geological and oceanographic explanations for these differences. We have studied the genetic diversity of 14 populations spanning from the Eastern Atlantic to the Eastern Mediterranean, using two nuclear genes sequences revealing a total of 63 polymorphic sites. Both genotype-based, haplotype-based and the novel SNP distribution population-based methods have found that these populations represent a geographic cline along the west to east localities. The differences in SNP distribution among populations further separates a major western cluster into two smaller clusters, the Eastern Atlantic and the Western Mediterranean. It also separates the major eastern cluster into two smaller clusters, the Mid-Mediterranean and Eastern Mediterranean. We suggested here environmental conditions like surface currents, water salinity and temperature as probable factors that have formed the population structure. We demonstrate that C. stellatus is a suitable model organism for studying how geological events and hydrographic conditions shape the fauna in the Mediterranean Sea.

The rocky intertidal communities of Ireland contain a mix of cold- and warm-adapted species, however the spatial distribution of these communities has not been investigated in a systematic way. Based on a benthic community dataset collected in 2003 at 63 sites, several statistical analyses were combined with the aims of (i) detecting groups of similar communities and their spatial arrangement, (ii) relating these groups to environmental factors and (iii) identifying the species that drive the different community groups. Sørensen's index suggested two marine community groups, one of the east and south-east (termed ‘east’) and the other in the west, south-west and north (termed ‘west’). A second partition based on combined wave exposure and sea surface chlorophyll comprised four groups, as did a further partition based on combined sea surface and air temperatures. The spatial arrangement of wave height plus chlorophyll conditions agreed reasonably well with the binary marine community partition, but the temperature partition did not. The ‘east’ community appeared to be associated with low wave height and chlorophyll conditions. The species that were most influential to the ‘east’ community wereBalanus crenatus, Austrominius modestusandFucus vesiculosus. The ‘west’ sites were associated with high wave height/low chlorophyll (with some variation in this due to local shelter) and the speciesParacentrotus lividus, Chthamalus stellatus, Alaria esculentaandHimanthalia elongata. A longitudinal pattern rather than one associated with latitude was evident in this marine community and local drivers rather than temperature clines appeared most important for the dominant community patterns.

Sewage discharges are among the most common anthropogenic stressors on rocky shores. However, studies on benthic invertebrates’ responses to sewage pollution on insular assemblages are rare. In order to fulfil this gap, (i) the effects of sewage pollution and (ii) the recovery capacity of eulittoral insular assemblages were examined. The study was conducted on Terceira Island (Azorean Archipelago, Portugal), in four distinct areas: one impacted area (outfall in operation), one post-impacted area (decommissioned outfall) and two undisturbed reference areas. Results showed that the abundance of the dominant species changed between reference and impacted areas. More specifically, the abundance of limpets Patella candei, and barnacles Chthamalus stellatus decreased, while the abundance of littorinids Tectarius striatus and Melarhaphe neritoides increased near the sewage discharges. Seventeen months after removal of the outfall, limpet and barnacle populations had partially recovered, but littorinid populations had still not fully recovered. This study confirms the negative effects of sewage discharges on eulittoral assemblages, and provides information on the resilience of benthic species following the cessation of sewage disposal.

Barnacles are key space-occupiers in rocky shore communities on European coasts. Barnacles of the species Chthamalus stellatus (Poli, 1791) were collected between June 2014 and May 2015 from two sites, two stations per each site with varying degree of exposure to wave action and anthropogenic pressure (trampling), in the Eastern Mediterranean (Pagasitikos Gulf, Central Greece). This study addresses a knowledge gap in population characteristics of C. stellatus populations in the Eastern Mediterranean, assessing population structure and allometric relationships. Patterns of distribution and abundance (density and percentage cover) were studied both temporally (seasonally) and spatially (water level and site). Morphometric characteristics exhibited spatiotemporal variation. Population density was significantly higher at the site with higher wave exposure. The population cover exhibited high levels of similarity among shore levels, both spatially and temporally. Spatial distribution exhibited a clumped pattern of dispersion in autumn, winter, and spring, mainly in the sheltered site. Six dominant age groups were identified, with the dominant cohort in the third-year class. Significant negative allometric relationships were exhibited between all morphometric characteristics. Differences in growth patterns among populations were indicated, with a higher rate of growth at the site of lower wave exposure.

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.

Two species of chthamalid barnacles are well established from the upper to the lower limit of the midlittoral zone on the rocky shores of the North Adriatic Sea: Chthamalus stellatus, Poli and Chthamalus montagui, Southward. The present study deals with the vertical distribution and abundance for each species at two localities of the Istrian peninsula coast (North Adriatic Sea). For this purpose chthamalid populations were monitored in 2015 along the Slovenian marine coast (Bay of Koper, Gulf of Trieste) and along the Croatian marine coast, near Rovinj (west Istrian coast), both on limestone. The main aim of the study was to establish if there was a relationship between the vertical distribution and abundance of these two species at different spatial scales: small (between sites, about 1 kilometer) and large (between localities, 10s of kilometers). The selected localities are slightly different in tidal range, in orientation and wave exposure. Three sites were randomly selected at each locality and two transects per tidal level (upper, middle and lower) were chosen on each site. The abundance of each chthamalids species in 1 dm2 plots was determined at three different tidal levels along each transect. The results indicated that the vertical distribution of C. montagui and C. stellatus was very similar between localities and even among sites, but their abundance varied. At both localities, C. montagui was more abundant in the upper and middle tidal levels, while C. stellatus was more abundant at the lower tidal level. It was also found that C. montagui was more abundant in sheltered conditions (Bay of Koper), while C. stellatus on the coast more exposed to the wave action (near Rovinj), at all tidal levels., Dvije vrste ciripednih rakova vitičara dobro su razvijene od više do niže gornje granice mediolitoralne zone na stjenovitim obalama sjevernog Jadrana: rak vitičar brumbuljak (Chthamalus stellatus, Poli i Chthamalus montagui, Southward). Ova studija se bavi vertikalnom raspodjelom i brojnošću ovih vrsta na dva lokaliteta na obalama istarskog poluotoka (sjever Jadranskog mora). U tu svrhu su 2015. promatrane populacije ciripeda duž slovenske obale (Koparski zaljev, Tršćanski zaljev) te duž hrvatske obale u blizini Rovinja (zapadna obala Istre), obje na vapnencu. Glavni cilj istraživanja bio je utvrditi postoji li povezanost između vertikalne raspodjele i brojnosti ovih dvaju vrsta u različitim prostornim skalama: mala (među lokalitetima, otprilike jedan kilometar) i velika (među lokalitetima, deseci kilometara). Odabrani lokaliteti pomalo se razlikuju po rasponu plime i oseke, smještaju i izloženosti valovima. Nasumce su odabrana tri mjesta na svakome od ovih lokaliteta i dva presjeka za razinu plime i oseke (viši, srednji i niži) odabrana su na svakoj pojedinoj lokaciji. Brojnost pojedine vrste chthamalida u dijelovima od 1 dm2 određeni su trima različitim razinama duž svakog presjeka. Rezultati su upućivali da je vertikalna raspodjela C. montagui i C. stellatus vrlo slična na svim lokacijama pa čak i na svim kontrolnim mjestima dok je njihova brojnost varirala. Na obje lokacije, C. montagui je bila brojnija pri nižim razinama plime i oseke. Također smo utvrdili da je C. montagui brojnija u zaštićenijim uvjetima (Koparski zaljev), dok je C. stellatus brojniji na obalama koje su izloženije valovima (blizu Rovinja), prilikom svih razina plime i oseke.

Biogeographic change in response to climate is a ratchet-like process, with gradual long term change punctuated by advances and retreats caused by extreme events. The winter of 1962–63 was the coldest winter since 1740, and caused lasting widespread changes in intertidal populations in Europe. Against the background of several decades of gradual warming, the severely cold winter of 2009–10 provided an opportunity to test mechanistic hypotheses regarding the control of biogeographic limits, including recruitment failure and adult mortality. As a result of enhanced recruitment in cold conditions, the northern barnacle Semibalanus balanoides expanded its range in both France and Iberia at an average rate of 25 km year − 1 . The northern polychaete Arenicola marina had high recruitment in northern France, which filled in a gap in its range in the central English Channel. The southern barnacles Chthamalus montagui and Chthamalus stellatus , which are sensitive to cold winters, suffered recruitment failure but no adult mortality at their northern limit in continental Europe. The southern limpet, Patella rustica and the southern polychaete Diopatra which are sensitive to cold summers, had virtually no change in distribution, as a result of the prior warm summer. The southern mussel Mytilus galloprovincialis suffered little adult mortality at its northern limit in continental Europe. Metapopulation models of future distribution, based on these mechanisms, and validated by hindcasts of historical biogeography, indicate that a regime shift will occur in northern Europe as southern species like Diopatra are able to invade the English Channel and from there enter the North Sea. These models and the historical biogeographic record confirm the view that biogeographic change is punctuated by population responses to extreme events.

We present an electron microscopical study of peculiar structures that appear during the growth and degeneration of the penis in some thoracican barnacles. In Semibalanus balanoides, a species with only one brood per year, special elongate processes develop on the solid cuticle of the growing penis. These processes form several layers that reach their maximum number during the copulatory period and subsequent period of degeneration. This hitherto undescribed structural complexity of the cuticle combines mechanical strength with flexibility. We also detected a small triclinic crystal in the longitudinal muscles of the degenerating penis, close to the sarcoplasmic reticulum. TEM lattice-plane images, the corresponding selected-area TEM diffraction patterns, and Fourier transformation of these patterns revealed that the crystal parameters differ from those of any other biocrystal described so far. In places, its unit cells adjoin the membranes of the sarcoplasmic reticulum; therefore, we suspect that the crystal may be lipoprotein. Two types of giant mitochondria can be distinguished in the muscles of the degenerating penis. One type is multilobed, and sections of differently orientated cristae within the dense matrix indicate an origin by the fusion of several single mitochondria. The other type is rounded and paracrystalline. So far it has only been observed in Chthamalus stellatus, a species with successive broods in a year.

The aim of this study was to determine the spatial and temporal distribution of the larvae of several barnacle taxa (Elminius modestus, Balanus group, Chthamalus spp., Verruca stroemia and Pollicipes pollicipes) in the partially mixed estuary of the Ria de Arousa (Galicia, NW Spain). The study was conducted during nearly three years (1999―2001) at seven larval stations distributed along the ria. The possible larval dispersal mechanisms involved are discussed using the information of the intertidal distribution in the ria of adult E. modestus, Perforatus perforatus, Balanus crenatus, Balanus improvisus, Semibalanus balanoides, Chthamalus montagui, Chthamalus stellatus, V. stroemia and P. pollicipes. The larvae of all barnacle species, with the exception of Balanus, showed a spatial gradient of distribution along the estuary, reflecting adult distributions in the intertidal zone. E. modestus larvae were most abundant in the inner part showing marked larval retention inside the estuary. Chthamalus larvae showed highest larval abundance in the outer part of the ria to lowest in the inner part, parallel to the spatial adult distribution along the estuary, suggesting that it completes its larval development inside the estuary due to some mechanism of larval retention. The larvae of V. stroemia and P. pollicipes entered the estuary far beyond where their adult populations were established, while Balanus larvae were widely distributed along the whole ria without any gradient. Based on the barnacle larval abundance, the sampling stations grouping divide the Ria de Arousa into two main groups along the estuarine salinity gradient: the inner one was clearly dominated by E. modestus and Balanus while the central―outer one was dominated by Balanus, Chthamalus and V. stroemia. Moreover, both areas (specially the central―outer one) could be again subdivided based on the relative presence of the barnacle species more characteristic of the extremes of the estuarine gradient (E. modestus and P. pollicipes). All the larval cirripedes in the Ria de Arousa, with the exception of V. stroemia, showed the typical seasonal abundance pattern of temperate species, generally being most common in spring and summer. Balanus and E. modestus larvae were present in the ria during the whole year, with Balanus peaking mainly in spring and summer, while E. modestus did not display a seasonal pattern that was repeated among years, normally peaking in summer, although in some years the larval abundance in autumn and/or spring was much higher. In contrast, Chthamalus had the shortest period of larval occurrence (spring and summer) with strong seasonality. Larvae of the boreal barnacle V. stroemia were collected throughout the year, with the exception of November and December, although its temporal distribution differed from the other temperate barnacles found in the ria, winter and spring being the seasons of higher abundance, instead of spring-summer.

ISSRs (Inter Simple Sequence Repeats) were employed to compare the genetic structure of Chthamalus stellatus and Tesseropora atlantica in the Azores. The two barnacles differ as regards life cycle: the former conducting pelagic life for about 22 days, the latter for only 24 h. Thirty individuals of each species were analysed from four locations of three Azorean islands. Five ISSR primers produced, respectively, 117 and 79 polymorphic bands in C. stellatus and T. atlantica. Estimates of among-samples genetic diversity suggested extensive connectivity in the former species and isolation in the latter. AMOVA further supported these results by attributing 2% of genetic variance to the among-islands component of C. stellatus and 30% to T. atlantica. Results are consistent with expectations based on species life history and corroborate the importance of pelagic stages in determining the degree of genetic structuring in benthic marine invertebrates.

The three chthamalids Chthamalus stellatus, C. montagui and Euraphia depressa are common inhabitants of the intertidal zone in the Eastern Atlantic, Mediterranean Sea and Black Sea. In this study, we investigated the occurrence of these barnacles in a wide range of their distribution. Population divergences of these two species have been inferred using three molecular markers — internal transcribed spacer (ITS), elongation factor 1α (EF-1α) and cytochrome oxidase subunit I (COI). ITS sequences of C. stellatus were identical throughout the species range, whereas ITS sequences of C. montagui indicated that the Black Sea and Mediterranean populations are isolated from the Atlantic population. The COI and EF-1α sequences were the most variable and informative. They indicated a high genetic divergence between Atlantic, Mediterranean and Black Sea populations for C. montagui. In addition significant genetic structure was found among the populations of C. stellatus based on EF-1α but not COI. Interestingly, our molecular dating analysis correlated the pattern of diversification in C. montagui to major geological changes that occurred in the Mediterranean during the end of the Messinian and Pleiocene periods. We suggest that palaeohistory shaped the divergences between Chthamalus populations that have probably been maintained by current hydrographic conditions. Finally, COI phylogenetic analysis placed the genus Euraphia within the Chthamalus clade, suggesting the need for a taxonomic revision of Euraphia. This study represents the most detailed phylogeographical analysis of intertidal Mediterranean species to date, and shows that geological events have strongly shaped the current diversity pattern of this fauna.

Genetic diversity in a pair of cirripede species, based on electrophoretic analysis of 25 gene loci, is higher for Chthamalus stellatus, the species with a broader biogeographical distribution, and hence, with a broader ecological niche, than that of Euraphia depressa. Comparing the genetic diversity within E. depressa we again report a higher genetic diversity among the specimens exposed to solar radiation (living in the wider ecological niche) versus the specimens confined to the sheltered dark environments in caves or under boulders. The indices of genetic diversity used in this study are polymorphism, heterozygosity, mean number of alleles per locus and gene diversity. We conclude that the niche-width variation hypothesis has been confirmed in this pair of species: genetic diversity is positively correlated with niche breadth.

The type specimen of the allegedly Late Cretaceous (Maastrichtian) Chthamalus darwini BOSQUET, 1857 from the Schneeberg, northwest of Aachen (Germany), is reevaluated and redescribed. Opinions expressed by previous authors, including BOSQUET himself (between 1860 and 1863), that this did not actually represent a latest Cretaceous fossil taxon, but an extant species which must have found its way to the Schneeberg as kitchen waste, are corroborated. In fact, we hold it to be conspecific with C. stellatus (POLI, 1791), a widely distributed species on the coasts of the Atlantic and in the English Channel, the North Sea and the Mediterranean. Thus, the genus Chthamalus, and the species C. darwini, can be struck definitively from the list of Late Cretaceous cirripede taxa occurring in the Aachen area. The only sessile cirripedes found here in situ in Upper Cretaceous strata are verrucomorphans (verrucids, proverrucids) and brachylepadomorphs (brachylepadids).

We tested the hypothesis that mean intensity and temporal variability of aerial exposure exert interactive effects on temporal variance in abundances of algae and invertebrates on rocky shores of the NW Mediterranean Sea. Transplantations of assemblages to different heights on the shore were used to manipulate the aerial exposure indirectly. Different periods of residency of assem- blages at each height were distributed over 2 yr to generate different levels of temporal variability of aerial exposure. Total durations of periods of emersion and submersion of organisms were kept com- parable across all treatments to avoid confusion between intensity and temporal variability of aerial exposure. Interactive effects between these 2 factors were observed for some response variables (fila- mentous and encrusting coralline algae, Chthamalus stellatus, Patella spp. and number of taxa), with mean intensity of aerial exposure either magnifying or dampening effects of temporal variability. Specific responses were related to the life histories of the focal organisms, in particular the ability to resist and to recover from aerial exposure. The experimental design we used can help in separating effects of shifts in mean values and temporal variances of climate variables in studies of climate change.

The distribution of cirripede cyprids in relation to associated oceanographic conditions was obtained from a grid survey and intensive vertical sampling at a fixed station located 21 km off the northwest Portuguese coast in May 2002. Analysis of cyprid length composition allowed separation of 3 species groups. Chthamalus montagui, Pollicipes pollicipes and Balanus perforatus were largely restricted to the neuston layer and showed only low-amplitude vertical migration. Most C. stellatus cyprids only appeared in the upper 20 m at night, a migration which did not appear to be affected by physical conditions in the water column, but some differences in the vertical migration pattern between days were probably related to varying light penetration. C. montagui is the most abundant adult species found along the Portuguese coast, but C. stellatus cyprids, at densities of up to 8.7 ind. m–3, were the most common sampled in all depth strata at the fixed station. Cyprid horizontal distribution was mainly restricted to an offshore band along the inner shelf, where highest densities were 11 to 15 ind. m–3. This distribution pattern was considered to result from upwelling-favourable wind conditions, creating fronts along the shelf in which the cyprids become concentrated. Cyprid vertical migration, in association with current vertical shear and onshore movement of fronts during upwelling-relaxation periods, may be the mechanisms returning cyprids to the coast to settle. The regularity of these events in the region falls within the period of cyprid viability.

The numbers of hard coastal artificial structures is increasing worldwide and there is now cumulative evidence that they support assemblages that are less diverse than natural shores. Here we investigated patterns of distribution and demography of the native barnacle Chthamalus stellatus on hard coastal structures and on natural rocky shores. Barnacles were 35% less abundant on hard structures regardless of substratum type (concrete or basalt). On a subset of sites we found that temporal population stability, growth and mortality were similar on natural rocky shores and hard structures. In contrast, barnacles were significantly larger and recruited more onto natural rocky shores. These results emphasise the important role of recruitment in determining the abundance of a key space occupier on hard coastal structures. Experimental work building on these results may generate insights that can be used as guidelines for the management of urbanised coastal areas.

The aim of this study was to investigate when adult distribution patterns are established in the barnacles Chthamalus stellatus and C. montagui . Adult ‘zones’ were identified by analysing field counts of both species at mid and upper shore heights. Monthly collections of cyprids, C. stellatus and C. montagui in natural barnacle beds at six shores in SW Ireland. This was carried out over one year in 1996/1997, using a hierarchical sampling design. Abundance of total recruits (0–3 months old) was compared between adult zones after the main settlement season had ended. In addition, scales of variability in 0–3 month recruitment into adult zones were compared between the species at two scales: shores (1000s of metres) and sites within shores (10s of metres). Older recruits of each species, up to 11 months of age, were also compared between adult zones. The majority of settlement (measured as attached cyprids) occurred between August and October 1996. In October, there was no effect of adult zone on the abundance of total (0–3 month) recruitment up to that point in either species. Despite this homogeneity in recruitment between adult zones, significant spatial variation was found in 0–3 month recruits of both species at both of the scales examined. In C. stellatus the amount of variation associated with the larger scale (shore) was more than twice that of sites or of the residual variation (replicates within sites). 0–3 month recruitment in C. montagui was also most variable at the scale of shores but the residual variability (between replicates within site) was of similar magnitude to that of shores. Variability in 0–3 month C. montagui recruitment was relatively low at the scale of sites. There was a small but consistent input of recruits to adult zones over 9 months of the year, complicating the assessment of when adult patterns were set-up in these species. By June 1997, characteristic patterns of adult dominance had been established at all shores. Settlement had completely ceased by this time and individual barnacles were potentially 11 months old. Neither settlement nor early recruitment are significant in determining adult zonation patterns in these species. Instead, differential mortality patterns in individuals up to the age of 11 months are implicated in determining patterns of distribution of both species.

Hong Kong, lying just below the Tropic of Cancer (22°17′N, 114°09′E), experiences a strongly seasonal environment, with a cool almost temperate winter and a hot, tropical, summer. Histological sectioning of the gonads of the high-shore barnacle, Chthamalus malayensis Pilsbry, showed a seasonal trend in the development of its reproductive organs. Four stages of female gonad development were identified according to the cell types present: post-spawning, resting, growth and mature stages. The female gonad was mature from April to November, which was related to seawater temperatures, and entered a resting phase from December to March. Although the male gonad showed a seasonal developmental trend and reached maximum maturity in summer, the seminal vesicles were full of spermatozoa and functional throughout the year. The reproductive season of this species is therefore solely dependant upon the maturity of the female gonad. The estimated maximum number of broods per year was up to 10 and the maximum number of eggs produced per brood can reach 3,000 eggs. The minimum size for female gonad maturity was 6 mm rostro-carinal diameter (RCD) at which size, the barnacles were ~6-month old. Sperm production occurred at a smaller size (2 mm=2-month old). Compared with Chthamalus montagui and Chthamalus stellatus from temperate regions, C. malayensis produced a greater number of broods per year, had a longer reproductive period and faster gonad development. Chthamaloid barnacles in tropical regions may, therefore, invest more energy per year in reproduction during their life span. Contrary to the seasonal gonad developmental pattern of C. malayensis in the present study, however, C. malayensis in Singapore (which experiences only slight seasonal variation) had mature female and male gonads throughout the year, further supporting the strong role of climatic conditions effecting the reproductive biology of barnacles.

Southampton Water, an estuary on the south coast of England, has been the focus of a number of studies to determine the seasonality and productivity of its pelagic community. Although recognized as important in previous studies, the meroplankton component and, in particular, the cirripedes have been largely ignored, though they rank second to the Copepoda in abundance. In order to estimate the contribution of barnacle larvae to the pelagic community, 42 quantitative zooplankton samples were collected from a fixed station within the estuary during a period of 19 months (from 12 January 2001 until 16 July 2002). As expected, barnacles were the second most abundant group averaging 13% of the total population, and accounting for up to 60% on some occasions. Eight barnacle species were identified: Elminius modestus, Balanus improvisus, Balanus crenatus, Semibalanus balanoides, Verruca stroemia, Chthamalus stellatus, Sacculina carcini, and Peltogaster paguri. Of these E. modestus was the most abundant and frequent, dominating the Cirripedia fraction throughout the year, but being outnumbered by B. crenatus from February to May. Secondary production was calculated for E. modestus and mean daily rates of 0.077 mg C m−3 d−1 (28.08 mg C m−3 yr−1) were found.

Oxygen levels were monitored within the mantle cavities of three barnacle species (Chthamalus stellatus, Semibalanus balanoides, Elminius modestus), using optode microsensors. Conditions were always hypoxic, even when barnacles were actively using the prosoma and cirri to pump aerated seawater into the mantle cavity. Mantle fluid oxygen concentrations were extremely variable; behaviour and oxygen concentrations were not closely coupled. Ventilation of the mantle cavity depended partially on external water flow, with higher and more stable mantle fluid oxygen concentrations being sustained when the water around barnacles was agitated. During emersion, barnacles initially pumped seawater between the mantle cavity and the cone above the opercular plates to achieve ventilation. As water was lost it was replaced by air bubbles, eventually resulting in an air-filled mantle cavity. In S. balanoides and E. modestus, once the mantle cavity was filled with air, the barnacle usually used up the oxygen within the bubble within 2–3 h and did not regain oxic conditions until the barnacle was reimmersed in seawater. In C. stellatus, the air bubble was repeatedly refreshed for many hours by pneumostome formation. In response to low environmental salinity, all three species closed the opercular plates firmly and rapidly used up oxygen within the mantle fluid.

Chthamalus stellatus and C. montagui are warm-water barnacles common on rocky shores in southwest England, Ireland, and southern Europe. They are partly sympatric, with overlapping vertical and horizontal distributions. It has been suggested that the differing horizontal distribution of the adults may be related to differences in the distribution of the larval stages. To this end, we have examined plankton samples taken during the summer breeding period at Plymouth, from inshore to 15 miles offshore. The samples also contained large numbers of other cirriped nauplii, notably Elminius modestus, Balanus perforatus, B. crenatus, and Verruca stroemia, from which the chthamalids had to be distinguished. The chthamalids can be separated from the other nauplii by use of characters that include a unilobed or trilobed labrum, the length of posterior processes and the shape and size of the cephalic shield, but the two species of Chthamalus are more difficult to distinguish. Scanning electron microscopy (S....

This study was carried out to determine the macrobenthic fauna of rocky supralittoral zone between Iskenderun and Arsuz. Samples taken at 3 stations in March 2011. As a result of the study, a total of 3 species with 99 individuals of Crustacea (Cirripedia 2, Decapoda 1) and 5 species with 58 individuals of Mollusca (Gastropoda 4, Bivalvia 1) were identified. In the study area, Chthamalus stellatus (Poli, 1795) was the most dominant species represented with 87 individuals and dominance value of 55.4%. According to frequency index, 3 species were designated as constant and 5 species as common., İskenderun-Arsuz arasında kalan bölgede kayalık supralittoral zonunun makrobentik faunası incelenmiştir. Örnekleme Mart 2011 tarihinde 3 farklı istasyonda gerçekleşmiştir. Çalışma sonucunda Krustase grubuna (Cirripedia 2, Decapoda 1) ait 3 tür ve 99 birey, Mollusca (Gastropoda 4, Bivalvia 1) grubuna ait 5 tür ve 58 birey tespit edilmiştir. İstasyonlar genelinde en dominant tür 87 bireyle ve %55,4 dominansi değeriyle Chthamalus stellatus (Poli, 1795) olduğu tespit edilmiştir. Frekans indeksine göre 3 tür devamlı ve 5 tür yaygın olarak tanımlanmıştır.

The distribution, abundance and recruitment of Chthamalus species were studied for one year at two rocky shores on the central coast of Portugal. Chthamalus montagui is the most abundant intertidal barnacle on the Portuguese mainland. Higher abundance of C. montagui was found on the lower levels of the more sheltered shore, which is closer to the influence of the Tagus estuary. Chthamalus stellatus was also present, in very low densities, and always confined to the lower level of the barnacle zone. Chthamalus stellatus was more common at the shore farther away from the estuary, in which exposure to wave action is higher. The metamorphs of C. stellatus settled at the studied shores are considered to be immigrants from other populations, where the density of adults is sufficient for cross-fertilization to occur. Chthamalus spp. recruited almost continuously throughout the year, with a peak between July and September and a gap during February and March. Variations in phytoplanktonic assemblages and temperature may be the main factors controlling the reproductive season of Chthamalus spp. Recruitment was usually stronger on the lower shore levels but extended for a longer period higher on the shore. Seasonalvariations of C. montagui abundance were greater on the lower levels of the more exposed shore. This is probably due to faster growth and higher mortality of barnacle populations occupying the lower shore levels at the more exposed habitats.

Areas which were under the influence of runoff seeping slowly from upshore rockpools were identified at two shores in Co. Cork, Ireland. Surveys of adult and 0+Chthamalus stellatus and C. montagui were carried out in these areas and compared with adjacent dry areas. A second survey on cleared quadrats examined barnacle abundance in wet and in dry areas at 1 and 5 months after the initiation of settlement. Chthamalus stellatus adults and 0+ individuals were significantly more abundant in wet areas than in dry areas, which in the context of previous laboratory findings suggest that desiccation or some other parameter associated with wetness may be an important factor in limiting the vertical distribution of this species. Chthamalus montagui adults and 0+ individuals were significantly more abundant in dry areas than in wet areas. The lower vertical limit of this species may therefore also be set by some wetness parameter. In 1 month and 5 month old stages, the differences in abundance between wet and dry conditions were apparent in both species but were only significant in both age classes of C. montagui at one of the study shores. The results are discussed in the context of vertical and geographical distribution patterns exhibited by adults of each species on European shores.

Two recently-distinguished species of Chthamalus (Cirripedia) are found on rocky shores in the north-eastern Atlantic: C. stellatus predominant on islands and headlands and C. montagui more abundant in bays. Larvae of the two species were produced in laboratory cultures to describe and compare the morphology and to allow identification in plankton samples. Nauplius larvae of C. stellatus are up to 30% larger than those of C. montagui. Differences in setation are minor. The two species are easily distinguishable from the size and shape of the cephalic shield. Chthamalus stellatus has a subcircular shield with longer body processes in later stages while C. montagui is more ovoid. The former develop more slowly in culture than the latter. Chthamalus stellatus larvae in a culture at 19 °C reached stage VI in 16 d compared to 11 d for larvae of C. montagui at the same temperature. The morphology and longer development time of C. stellatus larvae suggests adaptation to a more oceanic lifestyle and wider dispersal to reach more fragmented habitats than larvae of C. montagui.

Adult barnacles of Chthamalus stellatus and Chthamalus montagui were collected in August 1998, from Garrettstown Co. Cork and Kilkee Co. Glare, in southwest and west Ireland, respectively. Attached cypris larvae were collected during the settlement season of C. stellatus and C. montagui, on 2 shores in Co. Cork and 1 shore on Glare Island, Co. Mayo in west Ireland. Cyprid collections were made during either August or September, in 1992, 1994 and 1998 and all cyprids were measured along their carapace length. Size-frequency histograms were produced for each sampling occasion. Total DNA was extracted and the COI-COII mitochondrial genes were PCR amplified, both from selected adults and cyprids of each species collected in 1998. Composite haplotypes, produced by digesting PCR products with the restriction endonucleases TaqI and RsaI, showed clear identification between the 2 species as adults and larvae. Of the 68 cyprids examined, those measuring 525 mu m and under were found to have RFLP profiles corresponding with C. moniagui adults, while those of 550 mu m and larger were found to match C. stellatus adults. The findings verify previous length-frequency analysis. Carapace length is an important character in the identification of C. stellatus and C. montagui cyprids. The PCR primers developed during this study will also amplify DNA from 4 other species of acorn barnacle.

Galician populations of the marine snail Littorina saxatilis have two main morphs on exposed rocky shores. The ridged and banded morph inhabits the barnacle (Chthamalus stellatus) dominated upper shore, while the smooth and unbanded morph is mainly found in the lower-shore zone of blue mussels (Mytilus galloprovincialis). The distribution of the two morphs overlaps in the mid shore where hybrids are also present. The mid-shore habitat is a mixture of barnacle and mussel patches. We hypothesised that the different architectural complexity of barnacles and mussels would affect the distribution of the two morphs. Fractal dimensions were used to describe the substratum complexity of 96 small patches from three sites with different proportions of barnacles and mussels. Increased proportions of mussels in a patch increased the fractal dimension, and thus surface complexity. Snail abundance decreased with increased substratum complexity in the smooth and unbanded morph and in the hybrids but not in the ...

Protein electrophoresis on starch gels was used to investigate population genetic structure of the barnacles Chthamalus montagui Southward and C. stellatus (Poli) over their north-east Atlantic and Mediterranean ranges. In each species, a single locus exhibited marked differentiation of allele frequencies between Atlantic and Mediterranean localities; in C. stellatus, genetic differentiation between the two basins had not previously been noted. In both species, mean heterozygosity per locus appeared higher in the Mediterranean samples than in the Atlantic, and Mediterranean populations had more alleles at the loci studied. Possible explanations for the differentiation between the Atlantic and the Mediterranean populations are discussed.

The reproductive cycles of two intertidal barnacles, Chthamalus stellatus (Poli) and C. montagui Southward, were studied at Lough Hyne Marine Reserve, Cork, Ireland, over 28 months. In both species there were seasonal trends in development of the male and female reproductive organs with, for example, the ovaries regenerating while eggs were being brooded. Breeding occurred mainly during June–August but also at other times. The sizes of the ova and eggs of the two species were compared and the timing of the cycles relative to other areas considered.

At Lough Hyne Marine Nature Reserve, western Cork, Ireland, the intertidal barnacles Chthamalus stellatus (Poli) and Chthamalus montagui Southward were shown to be capable of breeding in their first year after settlement. In C. montagui, zero, one or two broods and in C. stellatus, zero, one, two or in a single case three broods were produced in the first summer. Whether or not barnacles brood in their first year is probably due to a combination of the time since settlement and size attained. In their second year after settlement, both species are multiple brooders, producing two broods during the summer season.

Reproduction in Chthamalus montagui Southward and Chthamalus stellatus (Poli) has been compared along gradients of wave exposure and tidal height. The proportion of barnacles carrying egg masses was greatest at low shore levels in both species, although the difference between levels was more pronounced in C. stellatus. Both species were found to breed between the beginning of May and the end of September. The mean number of broods released per season in both species ranged from 1.0 to 2.1 at high shore levels, from 2.2 to 3.2 at mid shore levels, and from 2.6 to 4.4 at low shore levels. C. stellatus predominated low on the shore at an intermediately exposed site and on the mid and low shore at the most exposed site. At these places it produced more broods per year than C. montagui. Development of the embryos of the two species was complete after 3 wk in vivo at 15°C. Eggs containing embryos of C. stellatus were larger than those of C. montagui, and within each species, larger barnacles produced larger eggs. Egg masses of C. stellanus included more eggs than those of C. montagui. Brood size in both species was greatest in shelter and least in exposure. Egg production was, however, similar in the two species when adjusted for differences in body mass. Egg production per unit body mass was greatest at an intermediately exposed site.

The biochemical changes during the development of fertilized eggs ofChthamlus stellatus (Poli) and ofEuraphia depressa (Poli) from the eastern Mediterranean were investigated. The egg volume increased by 20% in the former and by 35.8% in the latter. The dry-weight losses were 31.5 and 35.5%, respectively. Proteins and lipids contributed most of the energy used during development, the amount of carbohydrates was very low. Most of the energy was utilized at the final stage of the development. InChthamalus stellatus there was a loss of ≈38% and inEuraphia depressa a loss of 42%. The specific energy contents of the final stage of development were similar in both species. The high values of specific energy in these two warm-water species were related to the nutrient-poor water of the eastern Mediterranean. Major changes in DNA values were detected at the initial stages of the development.

The abundance of the common intertidal barnacles, Chthamalus montagui, Chthamalus stellatus, Semibalanus balanoides and Elminius modestus has been monitored since 1951 at a site near Cellar Beach, River Yealm, south Devon. Counts are made at 12 levels on a transect between high tide and low tide. The two chthamalids are of warm-water distribution while S. balanoides is a boreo-arctic species; changes in the abundance of these species are linked to environmental temperature. Maximum fluctuations occur in the lowermost third of the intertidal zone. The proportion of Chthamalus adults is correlated with annual mean inshore sea temperature two years earlier, while the proportion of S. balanoides adults is negatively so correlated. This relationship accounts for over 40% of the variance. A smaller part of the variance (E. modestus, is an Australasian immigrant that arrived in England during World War II and reached south Devon in 1948. It increased during the 1950s on the transect but has since stabilized at a low level of abundance that shows large interannual variations not directly related to temperature. Between 1951 and 1975, coinciding with a secular decline in sea temperature, there was a long-term trend towards reduction of Chthamalus and increase in S. balanoides; this trend has reversed since. Removal of the long-term trend reveals a short-term fluctuation of approximately 10-y frequency that correlates with a cycle in sea temperature two years earlier. These cycles are close to the 10–11 y solar (sunspot) cycle between 1951 and 1975.

Attached cypris larvae and less than one month old metamorphs of Chthamalus stellatus and C. montagui (Crustacea: Cirripedia) were sampled from random quadrats on two shores in County Cork, Ireland, from July 1996 to June 1997. Cyprids of C. stellatus were much more abundant than those of C. montagui, but the relative abundance of metamorphs of the two species did not differ significantly. Cyprid abundance predicted metamorph recruitment intensity during peak settlement in C. stellatus but not in C. montagui.

Seasonal changes in the dry body weight and in the biochemical components of Chthamalus stellatus (Poli) and Euraphia depressa (Poli) from the Mediterranean coast of Israel were recorded. The relationship of these changes to breeding was determined. The body weight increased gradually from October to December–January, remaining steady until July. During October–May, total lipids, total carbohydrates and total proteins increase. The main breeding season of both species is restricted to July–August. Following fertilization in July, there is a decline in the values of the above-mentioned components. Maximal DNA values were detected during the fertilization period after which a decline was noted.

Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui and Chthamalus stellatus was examined over an European scale. The study was carried out using standardised protocols at a series of locations. The five locations chosen (SW Ireland, NW Spain, SW Portugal and NW and NE Italy) span a large part of the range of these species in Europe. The spatial scales were location (hundreds of kilometres) and shore (thousands of metres). Estimates of total cumulative recruitment (cyprids and metamorphs) summed over the year (April 1997 to March 1998) showed substantial variation between locations which was dependent on the species. Recruitment was highest in SW Portugal for C. montagui and in SW Ireland and NW Spain for C. stellatus. Overall recruitment of C. montagui was higher than that of C. stellatus at all locations except SW Ireland, where recruitment of the two species was not significantly different. There were significant differences among shores in each location. The recruitment period of both species varied with location, with recruitment beginning earlier further south. In general, recruitment of C. montagui and C. stellatus was recorded in 8 months in NW Spain and NE Italy, while only in 7 months in SW Ireland. Recruitment of C. montagui occurred in 10 months in SW Portugal, but no recruits of C. stellatus were found. In all locations there was at least one distinct peak of recruitment. In SW Ireland both species showed only one peak of recruitment, a month after initiation. At the more southerly Atlantic locations, as well as in the Mediterranean, two unequal peaks of recruitment were generally seen. During recruit census, the number of cyprids, in comparison to metamorphs, found at any location was very low. In SW Ireland and NW Spain cyprids of both species were found, while in SW Portugal and in the Mediterranean, only cyprids of C. montagui were found.

As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996-1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their Carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 mum, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shape and length, the remaining cyprids in the collections were identified as one of three chthamalid species, Chthamalus montagui, Chthamalus stellatus or Euraphia depressa. Bimodal length distributions of chthamalid cyprids were seen on some shores, while others had a single small-sized modal group (representing C. montagui on Atlantic shores and/or E. depressa in the Mediterranean) separated from a few distinctly larger cyprids (C. stellatus). Metamorphs collected simultaneously with cyprid collections were identified as C. stellatus or C. montagui, except at Roscoff, where E. modestus were also found. In southern Portugal, where all metamorphs collected were C. montagui and adult C. montagui were the dominant barnacles, most cyprids measured between 350 and 550 mum long and this size distribution coincides with the distribution expected for C. montagui. Cyprids collected on these four more southerly Portuguese shores had the same modal length class (475 mum) and this remained constant between successive years at Luz and Albufeira, Algarve. The smallest (350 mum long) wild chthamalid cyprids found were from southern Portugal and Italy. In Spain, France and Ireland the smallest chthamalid cyprid was 425 mum long. The results from the present study support the hypothesis that on Atlantic shores cyprids of C. montagui can be separated from those of C. stellatus based on size, although there is some variation in cyprid length with latitude as well as temporal variation at selected localities.

Two co-occurring chthamalid barnacle species occur on the rocky shores of continental Portugal: Chthamalus stellatus (Poli) and Chthamalus montagui Southward. In the present study, patterns of distribution and abundance (density and percentage cover), both vertically (tidal level) and horizontally (wave action), were studied for each species on headlands (more wave action) and not on headlands (less wave action) and at two spatial scales (shore and site) and three tidal levels (low, mid and upper). Chthamalus montagui was significantly more abundant than C. stellatus in both degrees of wave action and at all tidal levels. Despite this great difference in abundance and considering each species individually, C. montagui was more abundant at mid tide-level, while C. stellatus was more abundant at the low tide-level, and C. montagui was less abundant on headlands, while C. stellatus was more abundant on headlands. Small-scale variability (between sites, tens of meters) of abundance of each species was detected, while differences on a larger scale (between shores, tens of kilometres) were not significant.