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Isolated populations or those at the edge of their distribution are usually more sensitive to changes in the environment, such as climate change. For the barnacleSemibalanus balanoides(L.), one possible effect of climate change is that unpredictable spring weather could lead to the mismatching of larval release with spring phytoplankton bloom, hence reducing the recruitment. In this paper, model simulations of a variable open population with space limited recruitment were used to investigate the effects of low and zero recruitment on population abundance inS. balanoides. Data for model parameters was taken from an isolated population in the Isle of Man, British Isles. Model simulations with observed frequencies of years with low recruitment showed only small changes in population dynamics. Increased frequencies of low recruitment had large effects on the variation in population growth rate and free space and on population structure. Furthermore, populations with intermediate to high frequencies of low recruitment appeared more sensitive to additional changes in recruitment. Exchanging low recruitment with zero recruitment severely increased the risk of local extinctions. Simulations with consecutive years of low recruitment showed a substantial increase in free space and an increase in the time taken to recover to normal densities. In conclusion, model simulations indicate that variable populations can be well buffered to changes in the demography caused by introduced environmental noise, but also, that intermediate to high frequencies of disturbance can lead to a swift change in population dynamics, which in turn, may affect the dynamics of whole communities. [ABSTRACT FROM AUTHOR]

We investigated the influences of oceanographic variables on recruitment patterns of the acorn barnacle Chthamalus malayensis and the rock oyster Saccostrea cuccullata, key space occupiers on tropical intertidal rocky shores. Recruitment data and nearshore environmental variables were obtained at spatial (regional and local) and temporal (monthly) scales on the west coast of Thailand. The relationship between the recruitment of each species and combinations of environmental variables was modeled. The climate of the study sites is influenced by the southwest and northeast monsoons of the Indochinese monsoon system. Observations showed that recruitment of both species and oceanographic variables exhibited differences at either local scale or monthly scale or both. Recruitment of both species was positively related to temperature, while barnacle recruitment was negatively related to salinity, but oyster recruitment was positively related to salinity. Barnacles showed a greater rate of recruitment when south-westerly onshore winds predominated during the southwest monsoon season, while the influence of wind patterns on rock oyster recruitment was not clear. Differential larval delivery regulated by monsoon-driven currents is, therefore, a potential determinant of barnacle recruitment. Our study highlights the roles of monsoon-influenced oceanographic processes as predictors of recruitment patterns of intertidal species in a tropical system. [ABSTRACT FROM AUTHOR]

The lack of effective governance is a major concern in small-scale fisheries. The implementation of governance that encompasses the three pillars of sustainability (social, economic, and ecological) is still a worldwide challenge. We examined nine stalked barnacle fisheries (Pollicipes pollicipes) across Southwest Europe to better understand the relationship between governance elements and sustainability. Our results show that nested spatial scales of management, the access structure, co-management, and fisher's participation in monitoring and surveillance promote sustainability. However, it is not the mere presence of these elements but their level of implementation that drives sustainability. Efforts should be placed in the accomplishment of a minimum combination of local scales of management, access rights through individual quotas, instructive-consultative co-management and functional participation. Surpassing this threshold in future governance structures will start to adequately promote social, economic and ecologically sustainability in small-scale fisheries. [ABSTRACT FROM AUTHOR]

An important challenge to decrease the toxic effects of the common biocides in marine environments and to achieve suitable ecofriendly natural antifouling coatings is to find effective natural antifoulants and efficient biodegradable coatings. In this study, antifouling activities of nine bioactive extracts (non-polar to polar) from different organs of the sea cucumber Stichopus herrmanni were tested against five bacterial strains, barnacle and brine shrimp larvae. The ethyl acetate extract of the body wall showed the highest in-vitro antifouling activity including high antibacterial and anti-barnacle activities and low toxicity against the brine shrimp as non-target organism. Based on these results, 10 phr of the ethyl acetate extract from S.herrmanni was added to different coatings consisting of polycaprolactone (PCL)/polylactic acid (PLA) blends containing various compositions of PLA (0, 10, and 20 wt.%). Polyvinyl chloride panels were coated with the prepared antifouling coatings and immersed in seawater for three months. Panel coated with PCL 80% /PLA 20% containing 10 phr of the antifoulant (panel-5), showed the highest resistance against fouling settlement with fouling coverage of 41.66% (P < 0.05). In addition, the lowest fouling weight was measured in panel-5 as well (81.00 ± 9.85 g) (P < 0.05). These findings indicate the antibacterial and antifouling potential of semi-polar bioactive extracts from the S. herrmanni body wall as natural antifoulants, as well as the enhanced antifouling performance of PCL/the natural antifoulant coatings by adding PLA. [ABSTRACT FROM AUTHOR]

During larval development of the intertidal barnacle Fistulobalanus albicostatus, larvae in the naupliar stages I and II (NI&II) possess a single naupliar eye, and later develop additional pair of compound eyes in the naupliar VI (NVI) and cyprid stages. These eyes showed light wavelength-dependent absorbances; where the highest absorbance was within 550 to 600 nm. The phototaxis of each stage was determined under light irradiation at six wavelengths (375, 470, 515, 525, 660, and 735 nm) and at three intensities (5, 15, and 25 W/m2), except for the 735 nm treatment which was irradiated at 25, 50, and 100 lx. NI&II larvae showed no clear pattern of phototaxis under the assessed light conditions. NVI and cyprids exhibited strong positive phototaxis under the assessed light conditions, except under 375 nm at 5 and 15 W/m2 where negative phototaxis was detected. Furthermore, the settlement behavior of cyprids was examined under 375 nm at the three intensities, and under the other five wavelengths at 25 W/m2 or 100 lx. The highest and lowest rates of settlement occurred at 470 and 375 nm, respectively. The results provide a valuable insight into the light-response mechanisms that potentially determine the distribution of barnacle larvae. [ABSTRACT FROM AUTHOR]

In 1846, burdened by insecurity and self-doubt, and having been convinced that he needed to study some group of organisms closely, Darwin embarked on an eight-year odyssey in the protean and perplexing world of barnacles. At the time, he was searching for evidence in support of his theory of evolution by natural selection. In the course of his long study of barnacles, however, he was not just validating his preexisting theoretical system, but was also modifying his views on such fundamental aspects as the universality of individual variation, which is the focus of this paper. According to this notion, the members of any population of living things are expected to exhibit sufficient differences from one another for natural selection to operate. By emphasizing the theoretical value of the barnacle project, my analysis contributes to the historiographic tradition which highlights the significance of the period between the first comprehensive formulation of the theory of evolution by natural selection in 1844 and its urgent publication in the late 1850s. In the course of these years, Darwin's theory was not just accumulating empirical laurels, but was also expected to adapt to a changing conceptual landscape. [ABSTRACT FROM AUTHOR]

The scallop Chlamys hastata frequently carries epibionts such as sponges and barnacles on its shells. Although the scallop-sponge relationship has been characterized as a mutualism, little is known about the scallop-barnacle relationship. This study investigated the effects of sponge and barnacle encrustation on the ability of C. hastata to avoid predation by the sea star Pycnopodia helianthoides. In feeding trials, P. helianthoides caught and consumed significantly more barnacle-encrusted scallops (7.7 ± 0.8 out of 20 scallops) than scallops encrusted by either of the sponges Myxilla incrustans (4.1 ± 0.9) or Mycale adhaerens (3.0 ± 0.5). Epibiont-free scallops (5.7 ± 0.5) formed an intermediate treatment between barnacle-encrusted and sponge-encrusted scallops. Possible mechanisms by which the sponges protected the scallops were investigated in two ways: two feeding trials were videotaped to allow qualitative analysis of sea star and scallop behavior and sea star feeding responses to scallop and sponge homogenates were determined to investigate if sea stars accept scallops and sponges as prey. Sea stars displayed positive feeding responses to scallop puree 97.5% ± 1.6 of the time while only displaying positive responses to Mycale adhaerens homogenate 4.4% ± 2.0 of the time and to Myxilla incrustans homogenate 4.4% ± 2.9 of the time. The videotaped feeding trials indicated that interference with tube feet adhesion by the sponge deterred predation. Observations of both sea stars that were videotaped showed that neither avoided trying to capture sponge-encrusted scallops, and at no time was a captured scallop willingly released by the sea stars. Thus, it appears that sponges provide tactile-mechanical protection and possibly chemical or tactile camouflage in this predator/prey relationship. Finally, the effects of sponge encrustation on barnacle settlement were determined. Field experiments showed that barnacle larvae settled more frequently on epibiont-free scallops than on those with either of the two sponges, potentially protecting the scallops from an epibiont that increases the scallop’s susceptibility to predation. [ABSTRACT FROM AUTHOR]

In this study, we tested the significance of environmental influences on non-marine ostracod communities at high taxonomic levels across Patagonia, Argentina. We used a dataset compiled from 243 Patagonian freshwater bodies, representing an area of ~ 900,000 km2 and covering the main local and climatic gradients. We applied generalized linear models to test the effects of hydroperiod, local and climatic variables on the occurrence and abundance of Ostracoda, and the occurrence of the most frequent families (i.e., Cyprididae, Ilyocyprididae and Limnocytheridae). We found ostracods in 77% of the total sampled sites, driven mainly by dissolved oxygen levels and water temperature (local variables) as well as precipitation and air temperature (climatic variables). Specifically, warmer winters and dryer climates favored ostracod occurrences, which covered wide ecological ranges, such as peat bogs or high-altitude wetlands. For the Ilyocyprididae and Limnocytheridae families, precipitation and pH were important predictors of their occurrence. Furthermore, wind speed, nutrient levels and water depth had positive effects on ostracod abundance. This updated Patagonian freshwater dataset contributes towards filling those knowledge gaps related to the habitat suitability of ostracods communities in this vast region. Our findings could help us understand the past and future responses of ostracods to environmental changes. [ABSTRACT FROM AUTHOR]

A serious consequence of marine biofouling on metallic structures is the insidious localized corrosion at the attachment sites of fouling organisms, such as barnacles. Albeit known, this phenomenon is poorly understood and currently mitigated using cost- and labor-intensive methods. In this work, we study the contribution to biofouling corrosion by a protein contained in the adhesive cement that barnacles secrete to attach to immersed substrates. We synthesize a specific cement protein of 20 kDa (CP20) from the barnacle Megabalanus rosa and study its corrosion behavior independently of the animal. Our results show that CP20 accelerates the corrosion rate of a marine-grade, mild steel from 0.7 to 1.6 mm year−1. Through chemical analysis of the corrosion products, protein adsorption studies on the metal surface, and cyclic voltammetry, we elucidate an intricate corrosion mechanism that relies on the strong adhesive properties of CP20 and its electrochemically active disulfide groups. Our results have far-reaching implications on the prediction and mitigation of biocorrosion in marine applications. Moreover, the protein-induced corrosion mechanism unveiled in our study may be extended to other scenarios to understand the degradation of metal alloys used in food storage and biomedical implants. [ABSTRACT FROM AUTHOR]

Barnacles are the only sessile crustaceans, and their larva, the cyprid, is supremely adapted for attachment to surfaces. Barnacles have a universal requirement for strong adhesion at the point of larval attachment. Selective pressure on the cyprid adhesive has been intense and led to evolution of a tenacious and versatile natural glue. Here we provide evidence that carbohydrate polymers in the form of chitin provide stability to the cyprid adhesive of Balanus amphitrite. Chitin was identified surrounding lipid-rich vesicles in the cyprid cement glands. The functional role of chitin was demonstrated via removal of freshly attached cyprids from surfaces using a chitinase. Proteomic analysis identified a single cement gland-specific protein via its association with chitin and localized this protein to the same vesicles. The role of chitin in cyprid adhesion raises intriguing questions about the evolution of barnacle adhesion, as well as providing a new target for antifouling technologies. Nick Aldred et al. show that chitin provides stability in the cyprid adhesive of the barnacle Balanus amphitrite. They show that a single cement gland-specific protein associates with chitin, and that freshly attached cyprids can be removed from surfaces using chitinase. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPSs) are the hydrated gelatinous matrix produced by microorganisms for attachment in a biofilm environment. In this study, the compositional variation between EPSs of three marine biofilm bacteria (Pseudoalteromonas shioyasakiensis, Vibrio harveyi and Planomicrobium sp.) were analysed by GC-MS, 1H NMR, FT-IR and XRD and SEM. The ecological significance of exopolymers was assessed in vivo using marine model organism barnacle larvae for their settlement-inducing activity. Chemical analysis revealed the presence of glycan fucosylated oligosaccharides, tetraose, trisaccharides, iso-B-Pentasaccharides, sialyllactose, oligomannose, galacto-N-biose, difucosyl-para-lacto-N-neohexaose, 3′-sialyl N-acetyllactosamine and isoglobotriaose-β-N(Acetyl)-Propargyl in all extracted EPSs. Bioassay results indicated that treatment of the barnacle larvae with EPSs from three bacterial strains enhanced settlement on substrates. In conclusion, this study highlighted the role of water-soluble EPSs in the invertebrate larval settlement on artificial materials. [ABSTRACT FROM AUTHOR]

Barnacle shell (BSh)-associated bacteria, their culture supernatants (CS), and biofilm exopolymers (BE) are known to induce cyprid metamorphosis of Balanus amphitrite. Besides bacteria, the BSh also harbors diatoms. However, the roles of their CS and BE on cyprid metamorphosis were not known, and the same was evaluated using two epibiotic diatoms, Achnanthes longipes and Melosira nummuloides, isolated from the BSh. The CS of M. nummuloides, a waterborne cue, promoted cyprid metamorphosis only when isolated in the presence of BSh, whereas that of A. longipes inhibited the same. The high-performance liquid chromatography (HPLC) of CS of both the diatoms indicated the dominance of arabinose, an inhibitory sugar. However, thiols were additionally present in the CS of M. nummuloides as indicated by fourier-transform infrared spectroscopy (FTIR) and are probably responsible for their promotory effect. The BE, a surface-bound cue, of both the diatoms facilitated metamorphosis only when isolated in the presence of BSh and were rich in N-acetyl-D-glucosamine (NAG). Thus, the interaction of NAG with the shell proteins probably provides a set of cues that facilitate cyprid metamorphosis of B. amphitrite. [ABSTRACT FROM AUTHOR]

Barnacles are widespread and abundant inhabitants of rock surfaces in the intertidal zone, providing considerable contributions to the formation of carbonate sediments. The main goal of this study was to test two hypotheses: (1) the chemical composition of the Balanus balanus shell is mostly controlled biologically, and environmental factors have only minor influences, and (2) the chemical composition of B. balanus shells does not vary with size. To test these hypotheses, samples were collected in two fjords from two depths. This study revealed site-related differences in shell chemistry, although no variability in shell chemical compositions was detected between the depths and among the size categories. Barnacle shell plates had different accumulation patterns for different trace elements (Mg, S, Sr), with the operculum as the most distinctive shell plate. As those plates are precipitated under the same environmental conditions, the different accumulation patterns may indicate biological control of element uptake in cirripedes. We suggest that the specific chemical composition of the operculum may be related to the required mechanical properties of this shell part, and thus, it is likely that this organism regulates accumulation patterns within its shell, because such regulation increases its adaptive properties. Our results supported both presented hypotheses. [ABSTRACT FROM AUTHOR]

The increasing spread of invasive species in the Mediterranean Sea determines several alterations in local food webs, changing the feeding habits of native organisms. The whelk Stramonita haemastoma is a widespread Mediterranean gastropod that consumes bivalves, barnacles and limpets. Previous studies showed a shift in its diet from the bivalve Mytilaster minimus to the invasive mussel Brachidontes pharaonis, presumably due to a higher energy gain. Here we tested whelks' preference among natives and a novel prey, calculating the profitability ratio, and integrating those results with biochemical analysis on prey tissues and the routine metabolism of the whelks. Further, we used the scaled functional response as a theoretical tool to describe whelk ability to obtain energy from their environment by using four different prey species: B. pharaonis, Mytilus galloprovincialis, M. minimus and Patella caerulea. Whelks evidenced a Type II functional response for all prey, while Brachidontes displayed a lower attack rate and a higher handling time. Stramonita showed a greater preference for Brachidontes, that resulted as the prey with the higher energetic content, and the second most profitable after Patella. This suggests that the higher energy gain is behind the change in the predator's diet, with possible effects on its energy budget. [ABSTRACT FROM AUTHOR]

Barnacles are able to establish stable surface contacts and adhere underwater. While the composition of adult barnacle cement has been intensively studied, far less is known about the composition of the cement of the settlement-stage cypris larva. The main challenge in studying the adhesives used by these larvae is the small quantity of material available for analysis, being on the order of nanograms. In this work, we applied, for the first time, synchrotron radiation-based μ-X-ray fluorescence analysis (SR-μ-XRF) for in vivo and in situ analysis of young barnacles and barnacle cyprids. To obtain biologically relevant information relating to the body tissues, adhesives, and shell of the organisms, an in situ sample environment was developed to allow direct microprobe investigation of hydrated specimens without pretreatment of the samples. In 8-day-old juvenile barnacles ( Balanus improvisus), the junctions between the six plates forming the shell wall showed elevated concentrations of calcium, potassium, bromine, strontium, and manganese. Confocal measurements allowed elemental characterization of the adhesive interface of recently attached cyprids ( Balanus amphitrite), and substantiated the accumulation of bromine both at the point of initial attachment as well as within the cyprid carapace. In situ measurements of the cyprid cement established the presence of bromine, chlorine, iodine, sulfur, copper, iron, zinc, selenium, and nickel for both species. The previously unrecognized presence of bromine, iron, and selenium in the cyprid permanent adhesive will hopefully inspire further biochemical investigations of the function of these substances. [ABSTRACT FROM AUTHOR]

We tested whether the patchiness of barnacle settlement was determined by spatial (local) differences in settling and mortality rates. During the period of 2004-2011, annual photo-registration of a barnacles Semibalanus balanoides population was conducted on six flat rocks in the White Sea intertidal zone (Arctic). The average adult population density was 48 ind dm, and the average barnacle age was 3-4 years. According to age structure, during the first year, the number of recruits dropped by three to fourfold; while in the following 2 years, the population density remained nearly the same. The effect of ice friction influence was not recorded, although the rocks were covered with ice in winter. Settling peaks were recorded in 2005, 2007, and 2009. No correlation was observed between the recruit and adult distribution during 2 years of intense settlement. The death rate was uneven on different quadrates along the transects but did not correlate with population density. Because high settling rates and mortality are not linked to specific sites, this suggests that population patchiness is not spatially stable. [ABSTRACT FROM AUTHOR]

Balanus glandula is a native barnacle of the rocky shores in the west coast of North America. Forty years after its introduction in Argentina, this species is the only barnacle dominating the high intertidal of local rocky shores and more interesting, it was also reported successfully colonizing soft-bottom salt marshes. In this study, we identified and characterized the substrata most successfully colonized by B. glandula in Patagonian salt marshes through descriptive and experimental means. We surveyed and compared two Patagonian salt marshes and the substrata colonized by B. glandula. Our results show that barnacles utilize more than 10 types of different substrata. Mussel valves were the most frequent type of substrata utilized in Riacho marsh, whereas the dominant halophyte Sarcocornia perennis was the substratum most utilized in Fracasso marsh where mussels were mostly absent. When the five most utilized substrata were experimentally offered, the halophyte shrub Limonium brasiliense was the most densely colonized of the experimental substrata, with the largest sizes and the lowest proportion of dead barnacles. Density and size of the barnacles recruited on plants were similar to that observed in nearby invaded rocky shores. Our study strongly suggests that soft-bottom environments, where hard substrata are available, have to be seriously considered when designing early detection plans targeting B. glandula and other similar rocky shore invasive species. [ABSTRACT FROM AUTHOR]

Ecosystem engineering is an important process in a variety of ecosystems. However, the relationship between engineer density and engineering impact remains poorly understood. We used experiments and a mathematical model to examine the role of engineer density in a rocky intertidal community in northern California. In this system, the whelk Nucella ostrina preys on barnacles ( Balanus glandula and Chthamalus dalli), leaving empty barnacle tests as a resource (favorable microhabitat) for other species. Field experiments demonstrated that N. ostrina predation increased the availability of empty tests of both barnacle species, reduced the density of the competitively dominant B. glandula, and indirectly increased the density of the competitively inferior C. dalli. Empty barnacle tests altered microhabitat humidity, but not temperature, and presumably provided a refuge from wave action. The herbivorous snail Littorina plena was positively associated with empty test availability in both observational comparisons and experimental manipulations of empty test availability, and L. plena density was elevated in areas with foraging N. ostrina. To explore the effects of variation in N. ostrina predation, we constructed a demographic matrix model for barnacles in which we varied predation intensity. The model predicted that number of available empty tests increases with predation intensity to a point, but declines when predation pressure was strong enough to severely reduce adult barnacle densities. The modeled number of available empty tests therefore peaked at an intermediate level of N. ostrina predation. Non-linear relationships between engineer density and engineer impact may be a generally important attribute of systems in which engineers influence the population dynamics of the species that they manipulate. [ABSTRACT FROM AUTHOR]

Presents letters to the editor discussing nuclear magnetic resonance assignments for mouse and barnacle cement protein Mrcp-20k. Discussion on S100A13 protein; Structure of S100A13; Features of Mrcp-20k; Role of "Megabalanus rosa."

Adhesives of aquatic organisms are of high scientific interest with a view to biomimicry. The visualization of their fine-structure, however, is difficult due to the fragility of the extracellular matrix (ECM). Care must be taken in its preparation for high-resolution SEM. Relating matrix structures to substrate properties demands a high throughput of samples for reliable comparisons. In order to acquaint ourselves with a suitable method we found an easy way to manage the critical steps of preparation for SEM. We show that thin layers of proteinaceous matrix can be satisfactorily prepared by combining freeze-drying and sputtering in a conventional sputter coater after one-step fixation (2.5% glutaraldehyde). The results were superior to CPD. [ABSTRACT FROM AUTHOR]

The level of fluctuating asymmetry (FA), which is defined as random deviations from perfect bilateral symmetry in the morphological traits of an organism, increases with increasing developmental instability, and it may be used as an indicator of environmental and/or genetic stresses. This study attempted to relate FA levels in the opercular plates of the barnacle Amphibalanus ( Balanus) amphitrite with shore height and body trace metal concentrations. Barnacles were collected from both low and mid shores at six coastal locations with various degrees of marine pollution in Hong Kong. Four opercular traits, namely scutum length, tergum length, scutum width, tergum width were measured in the specimen while concentrations of five common trace metals (Cd, Cu, Cr, Mn and Zn) were determined in their body tissues using inductively coupled plasma-atomic emission spectrophotometry. Among the four traits, only tergum length and scutum width fulfilled the assumption of FA while their measurement errors were low. Across all sites, mid-shore A. amphitrite consistently exhibited a significantly higher FA level in scutum width than that in low-shore barnacles, but FA levels in tergum length were similar between the two shore heights. These results suggested that FA was trait-dependent, and mid-shore barnacles were possibly under high physical stress, such as desiccation and high temperature, leading to high developmental instability. Although no positive association was observed between FA and metal contamination in low-shore A. amphitrite, FA level in tergum length significantly increased with decreasing body concentration of manganese (Mn) in these barnacles. Such a negative relationship may be explained by the mechanism of bioaccumulation and physiological role of Mn in A. amphitrite with respect to the formation of barnacle shell plates. [ABSTRACT FROM AUTHOR]

Barnacle fouling has shown to impede gas exchange ability of mangroves. Fouled mangrove plants may therefore obtain less carbon dioxide and water for photosynthesis, resulting in reduced food and chloroplasts production, but such hypothesis remains untested. The objective of the present study compared the stomata density (essential for obtaining carbon dioxide and water molecules) and leaf chlorophyll concentration (essential for photosynthesis) of fouled and non-fouled (control) of seedlings, juveniles and adults of the mangroves Kandelia obovata, in Hong Kong and Taiwan. The seedlings and juveniles of the dominant mangrove plant species, Kandelia obovata, in Hong Kong and Taiwan had a higher density of stomata but a lower chlorophyll concentration in the leaves, when the trunks and twigs were fouled by the barnacle Fistulobalanus albicostatus. Fouled K. obovata appears to develop more stomata in the leaves to compensate the blocking effect of the lenticel from barnacle fouling. As fouling impacts the gaseous exchange ability of mangroves, fouled plants could obtain less carbon dioxide and water for photosynthesis, resulting in reduced food and chloroplasts production. Fouled adult plants, however, had variable responses in leaf chlorophyll concentrations among the study sites, suggesting adults were more tolerant of barnacle fouling. The present study reveals seedling and juvenile mangrove plants are very susceptible to barnacle fouling, which impedes the gaseous exchange mechanism and food production, which can subsequently result in reduced growth, fitness and survival. [ABSTRACT FROM AUTHOR]

The strength by which species interact can vary throughout their ontogeny, as environments vary in space and time, and with the density of their populations. Characterizing strengths of interaction in situ for even a small number of species is logistically difficult and may apply only to those conditions under which the estimates were derived. We sought to combine data from field experiments estimating interaction strength of life stages of the barnacle, Semibalanus balanoides, on germlings of Ascophyllum nodosum, with a model that explored the consequences of variability at per capita and per population levels to the abundance of year-old algal recruits. We further simulated how this interaction affected fucoid germling abundance as the timing of their respective settlements varied relative to one another, as occurs regionally across the Gulf of Maine, USA. Juvenile S. balanoides have a weak estimated per capita effect on germlings. Germling populations are sensitive to variation in per capita effects of juvenile barnacles because of the typically large population sizes of the latter. However, high mortality of juvenile barnacles weakens the population interaction strength over time. Adult barnacles probably weakly facilitate fucoid germlings, but greater survival of adults sustains the strength of that interaction at the population level. Germling abundance is positively associated with densities of adult barnacles and negatively associated with that of juvenile barnacles. Metamorphosing cyprid larvae have the strongest per capita effect on germling abundance, but the interaction between the two stages is so short-lived that germling abundance is altered little. Variation in the timing of barnacle and A. nodosum settlement relative to one another had very little influence on the abundance of yearling germlings. Interactions between barnacles and germlings may influence the demographic structure of A. nodosum populations and the persistence of fucoid-dominated communities on sheltered rocky shores in New England. [ABSTRACT FROM AUTHOR]

On NW Atlantic rocky shores, the main basal organisms in intertidal communities are seaweeds ( Ascophyllum nodosum, Fucus spp. and Chondrus crispus) and filter feeders (barnacles, Semibalanus balanoides, and mussels, Mytilus spp.). Their ecology has been extensively studied in New England (United States), but knowledge gaps exist for northern shores, which are subjected to stronger environmental stress. Therefore, we studied the above organisms on Canadian shores. We quantified the summer abundance of these seaweeds and filter feeders across full vertical (intertidal elevation) and horizontal (wave exposure and winter ice scour) environmental gradients on the Gulf of St. Lawrence and open Atlantic coasts of Nova Scotia. At the regional scale along the open Atlantic coast, seaweeds showed similar abundances in Nova Scotia than values reported for New England. However, both filter feeders were considerably less abundant in Nova Scotia. At the local scale in Nova Scotia, intense winter ice scour (which only occurs on the Gulf of St. Lawrence coast) was associated with a very low abundance of all species except barnacles. Spatial trends in Nova Scotia were similar to patterns known for certain species elsewhere, such as A. nodosum being almost restricted to sheltered habitats, regardless of elevation, and C. crispus being almost restricted to low elevations, regardless of exposure. Other trends were, however, characteristic of Nova Scotia, such as C. crispus being frequent at low elevations in exposed habitats, unlike in New England, where mussels often predominate there because of competitive advantages. In Nova Scotia, mussels were always restricted to cracks and crevices, unlike in New England, where they form extensive intertidal beds on exposed shores. The direct effects of increased environmental stress and indirect effects through altered interspecific interactions might explain the regional differences in local species distribution, which will require experimental validation. [ABSTRACT FROM AUTHOR]

This study was carried out on the “Faro/Ancão” artificial reef (AR), located off Faro, deployed in May 2003. We aimed to characterise early macrobenthic community colonisation of two concrete AR groups located at different depths (16 m and 20 m depth) and to test the effect of reef structure on these communities. The non-colonial organisms were counted; barnacles and colonial species were quantified using biomass. Multivariate analyses indicated that early macrobenthic communities (6 months of immersion) were affected by depth, and that barnacles and colonial species were also affected by reef structure. Univariate analyses showed that the biomass of barnacles and colonial species was significantly different among reefs and layers of modules. Both AR groups were characterised by the species Balanus amphitrite, Gregariella subclavata, Musculus cf. Subpictus, Paleanotus cf. Bellis and Syllidia armata. Jassa marmorata and Bugula neritina were characteristic species at 16 m depth, particularly on the AR Upper layer of modules, whereas Anomia ephippium was particularly common at 20 m, especially on the Lower layer of modules. [ABSTRACT FROM AUTHOR]

The composition of the early stages of intertidal and subtidal fouling assemblages in Comodoro Rivadavia harbour (Argentina, 45°52′ S, 67°28′ W) and the influence of shore level and season on their structure were analysed. At the beginning of each season, stones were glued to the substratum with epoxy putty and distributed along 4 vertical transects at intervals of 20 m, at 3 levels: upper intertidal, middle intertidal, and subtidal. Substrata remained in the field for 84–100 days. A total of 48 samples (4 seasons × 3 levels × 4 replicates) were analysed. Species richness increased with depth, with 6 taxa in the upper intertidal, 23 in the middle intertidal and 31 in the subtidal. Seasonal differences in richness were less distinct. Green, red and brown algae were the dominant groups. Invertebrates were mainly represented by filter-feeding, sessile organisms, such as cheilostome bryozoans, spirorbid polychaetes and acorn barnacles. The barnacle Balanus glandula and the bryozoan Cryptosula pallasiana were the only non-indigenous species found in this study. Highly significant differences in structure among shore levels and seasons were evidenced by a two-way ANOSIM test. The upper intertidal is characterized by the filamentous green algae Urospora penicilliformis and Ulothrix flacca. The barnacle Balanus glandula is the most abundant species in the middle intertidal. The subtidal is defined mainly by the presence of the spirorbid polychaetes Paralaeospira levinseni and Romanchella perrieri, and the keyhole limpet Fissurella radiosa. Ordination of samples by season was less clear than by shore level. [ABSTRACT FROM AUTHOR]

This study describes the distribution and abundance patterns of the associate fauna on the living surface of the corals Siderastrea stellata Verril, 1868 and Mussismilia hispida (Verril 1902) using a non-destructive method, on the northern coast of Rio de Janeiro State. For each coral species, infestation density and proportions of infested colonies, colonies attached and unattached to the substrate were estimated. A total of 474 colonies of S. stellata and 452 colonies of M. hispida were examined. The barnacle Ceratoconcha floridana (Pilsbry, 1931) was the dominant coral associate found, followed by gall-crabs of the family Cryptochiridae Paulson, 1875 and the bivalve Lithophaga bisulcata (d’Orbigny, 1842). Both coral species presented similar patterns of infestation dominance. S. stellata colonies were more commonly infested and showed a greater mean infestation density of 0.62 ind/cm2 at Armação dos Búzios, whereas M. hispida colonies had infestation densities of only 0.20 ind/cm2. Infestation density does not appear to impact negatively on corals of Armação dos Búzios. A clear negative relationship between the number of associates in the coral colony and coral size was found. Evidently abundance and frequency of occurrence of associated fauna is highly related to coral community structure and composition and the results highlight the importance of local scale studies. [ABSTRACT FROM AUTHOR]

Background: Thoracic outlet syndrome (TOS) is the most confusing and controversial subject; its treatment continues to be a dilemma. The symptoms are due to the neurovascular compression at the thoracic outlet. Aims: The objective of the study was to review our experience with this problem with particular reference to its presentation and management. Settings and Design: A retrospective analysis. Materials and Methods: Seventy-two patients (age range 15-55 years), treated for neurovascular complications of TOS from 1991 to 2005. Evaluation included clinical and radiological examinations comprising of radiograph, color duplex and angiogram with positional maneuvers. Result: Nineteen patients had features of neurogenic TOS, whereas 52 patients presented with arterial TOS. One case was found to have venous TOS. The diagnosis was based on the characteristic history and positive provocative tests. Cervical ribs were seen in 58 cases. Angiogram was performed in all arterial TOS. Conservative treatment offered 74% (14) good results in neurogenic cases. Scalenectomy with cervical rib excision via supraclavicular approach, with or without vascular reconstruction, was done in 46 cases. There was no major complication and 90% (42) cases showed good results. Conclusion: TOS is not an uncommon disorder and often goes undiagnosed. Conservative treatment plays a vital role in neurogenic TOS. In our experience, scalenectomy with cervical rib excision via supraclavicular approach gives good and lasting results with an acceptable outcome and minimum morbidity. [ABSTRACT FROM AUTHOR]

Examines the dynamics of metazooplankton population at the Salton Sea, California. Occurrence of severe crashes of metazooplankton population each year in the mid-lake during August and September; Demonstration of a lower densities of barnacle and polychaete larvae in the fall; Presence of the larvae of polychaete worm in the late winter and spring.

Nitrogen is the major growth-limiting nutrient for marine algae. One potential source of nitrogen for marine algae is ammonium released by invertebrates. Many mid-intertidal reefs in northeastern New Zealand are dominated by a close association between the honeycomb barnacle Chamaesipho columna and an encusting brown alga Pseudolithoderma sp. Growth of Pseudolithoderma was enhanced in the presence of live C. columna, which released ammonium at a greater rate than the maximum rate of ammonium uptake by Pseudolithoderma. Algal tissue on barnacle tests had a lower C:N ratio than tissue located more than 2 cm from the nearest barnacle, suggesting the barnacle is an important source of nitrogen for the alga. The role of nutrient exchange in determining ecological patterns of species in marine communities is discussed. [ABSTRACT FROM AUTHOR]

Focuses on a project studying hydrodynamic consequences of substratum colonization by barnacle. Equipments used for the project; Analysis of boundary layers and their interrelationships with mean flow velocity and population density; Effect of the size and magnitude of the magnitude of the boundary layer.

Identifies physical and biological factors which affect the probability of barnacle larvae settling on hard substrata. Reasons for fastidiousness of barnacle larvae in the choice of settlement sites; Reasons for search behavior carried out by larvae; Types of settlements provided by scientists to study settlement behavior of larvae in the Clyde Sea, in Great Britain.

The article focuses on the study by En-Tang Kang and colleagues which shows that coating a stainless steel with cement harvested from barnacles of Amphibalanus amphitrite prevents the formation of bacterial biofilms.