Search

Abstract: Adult acorn barnacles are sessile suspension feeders. This study compares the feeding of three size classes of the barnacle Balanus glandula. Cirral morphology, feeding behavior at a low current speed, and leakiness of the cirri were compared between these size classes: newly-settled juveniles (small, aperture diameter 0.36mm), an intermediate size (medium, aperture diameter 3.4mm), and the largest individuals found locally (large, aperture diameter 6.5mm). Barnacles were videotaped while feeding in a flow tank at a current speed of 4cm/s. Molts were collected and several morphometric and meristic traits were measured. Large individuals spent more time actively feeding and had fewer setae per millimeter of cirrus VI than did medium or small individuals. Small individuals were observed passively feeding, which was not observed in the larger groups. Barnacles tend to passively feed in high current speeds. Juveniles are more likely to experience slower flow speeds in the field due to their tendencies to settle in locally sheltered areas such as in pits and on the sides of adults in clumps. Thus, 4cm/s flow may be near the upper limit of flow speeds encountered by juveniles. Barnacles were videotaped actively feeding while a stream of milk was aimed at their cirri. Two geometric models of leakiness were generated from the observed billows. The small barnacles had cirral fans that were much less leaky than the medium and large barnacles. These calculations and measurements were made at a relatively slow flow speed. Leakiness and Reynolds number (Re) experienced will increase in the field with increasing flow up to some maximum current speed at which the barnacles cease to feed. [Copyright &y& Elsevier]

The barnacle Balanus glandula is predominantly an open coast species in the Northeast Pacific. However, B. glandula densely inhabits estuaries where environmental conditions such as salinity and temperature drastically differ from the open coast. The increased variability of environmental conditions within an estuary can potentially affect spatial patterns of reproduction in B. glandula. I examined gonad maturity, reproductive periodicity and fecundity, and then calculated reproductive output in B. glandula populations distributed along an estuarine gradient. Results indicated that reproductive output of this intertidal barnacle decreased four times over a spatial scale of kilometers, as a transition occurred from a marine to a freshwater habitat along an estuarine gradient. Additionally, a higher proportion of the population had well-developed gonads in the oceanic end of the estuary compared to the riverine end. These results indicate how reproductive pattern can significantly vary over a spatial scale of kilometers, resulting in site-specific contributions of offspring to the larval pool. [ABSTRACT FROM AUTHOR]

A series comprising hexane, ethyl acetate, ethanol and aqueous extracts from six common Chinese herbs (Carpesium abrotanoides, Melia toosendan, Cnidium monnieri, Vitex negundo, Stemona sp. and Sophora flavescens) was investigated for antifouling (AF) activity against cypris (cyprids) larvae of the barnacle Balanus albicostatus. All extracts tested except the aqueous extract from Stemona sp. significantly inhibited the settlement of cyprids, the most potent being the ethyl acetate extract of S. flavescens (EC50 value 2.08 μg ml−1), from which an AF compound, identified as 2′-methoxykurarinone, was isolated using bioassay-guided procedures. Furthermore, the AF activity of this compound was found to be highly reversible and greater than that of the three other natural products from S. flavescens, namely matrine, oxymatrine and oxysophocarpine. These compounds have been used commercially in China for their pharmaceutical activities, but their AF activities have not previously been evaluated. Analysis of structure–activity relationships suggested that the N-1 nitrogen atom in matrine plays a crucial role in AF activity. Overall, the present findings indicate that herbal plants are a valuable source of novel AF agents. [ABSTRACT FROM PUBLISHER]

A new briarane diterpene, juncin ZII ( 1), along with three known briaranes ( 2–4), was isolated from the EtOH/CH2Cl2 extracts of the South China Sea gorgonian Junceella juncea. The structure of 1 was established by extensive spectroscopic analysis, including 1D and 2D NMR data. For compounds 1–4 and eight other briaranes ( 5–12) isolated from J. juncea previously, the antifeedant activity against second-instar larvae of Spodoptera litura and cytotoxicity against S. litura cells were investigated, and it was observed that they all exhibit medium antifeedant activity. Compounds 1, 8, 9, and 12 also showed potent antifouling activity against the larval settlement of barnacle Balanus amphitrite at nontoxic concentrations with EC50 values of 0.004, 0.005, 2.82, and 0.447 μg/mL, respectively, while all compounds did not show obvious cytotoxicity against tumor cell lines K562, A549, Hela, and Hep-2. Their structure-activity relationship was discussed. [ABSTRACT FROM AUTHOR]

Abstract: A chemical examination of the Chinese sponge Acanthella cavernosa resulted in the isolation of three new A-ring contracted steroids, the ethyl esters of 2β-hydroxy-4,7-diketo-A-norcholest-5-en-2-oic acid (1), 24S-ethyl-2β-hydroxy-4,7-diketo-A-norcholest-5-en-2-oic acid (2), and 2β-hydroxy-4,7-diketo-24R-methyl-A-norcholest-5,22(E)-dien-2-oic acid (3), along with four other known steroids (4–7). The structures were determined on the basis of extensive spectroscopic analysis. Compounds 1–3 showed antifouling activity toward the settlement inhibition of Balanus albicostatus with the EC50 values of 8.2, 23.5, 31.6μg/mL, respectively. [Copyright &y& Elsevier]

Patterns of recruitment in marine ecosystems can reflect the distribution of adults, dispersal by ocean currents, or patterns of mortality after settlement. In turn, patterns of recruitment can play an important role in determining patterns of adult abundance and community dynamics. Here we examine the biogeographic structure of recruitment variability along the U.S. West Coast and examine its association with temperature variability. From 1997 to 2004 we monitored monthly recruitment rates of dominant intertidal invertebrates, mussels and barnacles, at 26 rocky shore sites on the West Coast of the United States, from northern Oregon to southern California, a span of 1750 km of coastline. We examined spatial variation in the dynamics of recruitment rates and their relationship to coastal oceanography using satellite-derived time series of monthly sea surface temperature (SST). Recruitment rates showed a biogeographic structure with large regions under similar dynamics delimited by abrupt transitions. The seasonal peak in recruitment rates for both mussels and barnacles changed from a late summer-early fall peak in Oregon to winter or early spring in northern California, and then .back toward summer in southern California. Recruitment rates varied greatly in magnitude across the latitudinal range. The barnacle Balanus glandula and mussels (Mytilus spp.) showed a decline of two orders of magnitude south of Oregon. In contrast, recruitment rates of barnacles of the genus Chthamalus showed a variable pattern across the region examined. The spatial distribution of associations between raw SST and recruitment rates for all species showed positive associations, indicating recruitment during warm months, for all species in Oregon, northern California, and several sites in south-central California. By considerably extending the spatial and temporal scales beyond that of previous studies on larval recruitment rates in this system, our study has identified major biogeographic breaks around Cape Blanco and Point Conception despite considerable spatial and temporal variation within each region and among species. These large differences in recruitment rates across biogeographic scales highlight the need for a better understanding of larval responses to ocean circulation patterns in the conservation and management of coastal ecosystems. [ABSTRACT FROM AUTHOR]

The date of first introduction of the North-East Pacific acorn barnacle Balanus glandula to South Africa is unknown, but it is depicted in photographic records dating back to at least 1992. Its present range and population density were determined by surveying 24 sites on the west and south coasts of South Africa. B. glandula occurred over approximately 400 km of coastline, from Elands Bay in the north-west to Misty Cliffs on the west coast of the Cape Peninsula. The abundance of B. glandula was affected by site, zone, prevalence of upwelling, and orientation of the shore. Its distribution was very patchy, both on macro- and microscales, with Bloubergstrand and Moullie Point having the highest abundances of 28 445 and 24 500 individuals m-2 respectively. B. glandula was the dominant barnacle at all West Coast sites where it was recorded, comprising 78.5% of all barnacles found. The successful invasions of B. glandula in South Africa, Argentina and Japan suggest that this species poses a potential threat to intertidal communities in cool, temperate waters. [ABSTRACT FROM AUTHOR]

We report the occurrence of the North-East Pacific intertidal barnacle Balanus glandula in the south-western African shores of the Atlantic Ocean. In addition, an attempt is made to trace the origin of the South African population by comparing the distribution of haplotype groups of two molecular markers, cytochrome oxidase subunit I (COI) and elongation factor 1 (EF1-α). The frequency of COI haplotypes in the South African specimens was most similar to that in specimens from Bodega Marine Laboratory and of Fort Bragg in Central California. Pairwise genetic distances demonstrated that the samples from Pillar Point were also similar to the Cape Town population. The frequency of EF1-α haplotype groups from Cape Town was most similar to that of Cape Blanco, Cape Meares and Westport Jetty, and, with lower p-values, to the populations of Cape Mendocino and Heceta Head. Pairwise genetic distances demonstrated that samples from Vancouver Island, Bodega Marine Laboratory and Heceta Head were also similar to the Cape Town population. Results indicate that the population of B. glandula from South Africa is most similar to the population from the northern portion of the Oregonian faunal province. It is possible that this is the origin of the South African population. As a result of this invasion, B. glandula out-competed the native African chthamalid species, Chthamalus dentatus. Thus, C. dentatus is presently very rare on the Atlantic South African shores. [ABSTRACT FROM AUTHOR]

Gregariousness in marine invertebrate larvae is an important regulator of benthic community structure. Previous laboratory settlement assays employing Balanus amphitrite Darwin cyprids found gregarious effects with as few as 3 larvae well-1, together with modulation of such effects by chemical cues. Here, the relationship between settlement rate and larval density was rigorously tested through a fully randomised design. Seawater conditioned with adult B.amphitrite was tested alongside unconditioned seawater to determine the effect of a conspecific cue on gregarious interactions. Gregarious effects were detected in both conditioned and unconditioned seawater at ≤4 larvae well-1. In untreated seawater, settlement rate increased linearly with larval density, levelling off at densities of ≥10 larvae well-1. In conditioned seawater, settlement induction was observed at ≤4 larvae well-1, switching to inhibition at 6, 8 and 10 larvae well-1, before asymptoting at the highest densities tested. These results advocate the use of individual larvae in laboratory assays that investigate factors stimulating barnacle settlement. [ABSTRACT FROM AUTHOR]

The mechanical properties of barnacle base plates were measured using a punch test apparatus, with the purpose of examining the effect that the base plate flexural rigidity may have on adhesion mechanics. Base plate compliance was measured for 43 Balanus amphitrite (=Amphibalanus amphitrite) barnacles. Compliance measurements were used to determine flexural rigidity (assuming a fixed-edge circular plate approximation) and composite modulus of the base plates. The barnacles were categorized by age and cement type (hard or gummy) for statistical analyses. Barnacles that were 'hard' (≥70% of the base plate thin, rigid cement) and 'gummy' (>30% of the base plate covered in compliant, tacky cement) showed statistically different composite moduli but did not show a difference in base plate flexural rigidity. The average flexural rigidity for all barnacles was 0.0020 Nm (SEM ± 0.0003). Flexural rigidity and composite modulus did not differ significantly between 3-month and 14-month-old barnacles. The relatively low flexural rigidity measured for barnacles suggests that a rigid punch approximation is not sufficient to account for the contributions to adhesion mechanics due to flexing of real barnacles during release. [ABSTRACT FROM AUTHOR]

The regulation of the settlement process in barnacles has attracted research interest due to their role as fouling organisms. The involvement of neurotransmitters in the regulation of settlement of marine invertebrate larvae has been described in several species. In this work, we reported the effects of the neurotransmitters dopamine and serotonin on the settlement of cyprids of the barnacle Balanus improvisus and described differences among cyprids of different ages. Also, we tested the effects of dopaminergic and serotonergic agonists and antagonists on settlement of cyprid larvae. We found that dopamine significantly stimulated settlement of 2- and 4-day-old cyprids, while serotonin exerted an inhibitory effect, regardless of cyprid age. The agonists and antagonists to the two neurotransmitters were not able to stimulate settlement but in general had either an inhibitory or no effect. We compared our results to those previously reported of the roles of dopamine and serotonin in the settlement of Balanus amphitrite. There appeared to be striking differences in the effects of these neurotransmitters between the two species because it has been reported that serotonin induces settlement in B. amphitrite and that dopamine inhibits it. This suggested that dopamine and serotonin play pivotal roles in settlement of barnacle but may act in different ways in the two species. [ABSTRACT FROM AUTHOR]

In the intertidal zone in the Pacific Northwest, body temperatures of sessile marine organisms can reach 35°C for an extended time during low tide, resulting in potential physiological stress. We used immunochemical assays to examine the effects of thermal stress on endogenous Hsp70 levels in the intertidal barnacle Balanus glandula. After thermal stress, endogenous Hsp70 levels did not increase above control levels in B. glandula exposed to 20 and 28°C. In a separate experiment, endogenous Hsp70 levels were higher than control levels when B. glandula was exposed to 34°C for 8.5 h. Although an induced heat-shock response was observed, levels of conjugated ubiquitin failed to indicate irreversible protein damage at temperatures up to 34°C. With metabolic labeling, we examined temperature acclimation and thermally induced heat-shock proteins in B. glandula. An induced heat-shock response of proteins in the 70-kDa region (Hsp70) occurred in B. glandula above 23°C. This heat-shock response was similar in molting and non-molting barnacles. Acclimation of B. glandula to relatively higher temperatures resulted in higher levels of protein synthesis in the 70-kDa region and lack of an upward shift in the induction temperature for heat-shock proteins. Our results suggest that B. glandula may be well adapted to life in the high intertidal zone but may lack the plasticity to acclimate to higher temperatures. [ABSTRACT FROM AUTHOR]

Stable isotopic compositions of nitrogen and carbon in barnacles Balanus perforatus from the Pirovac Bay (Central Adriatic), highly impacted by untreated municipal waste, and from unaffected sites from the southern part of the Kornati Islands were compared. The differences in δ13C and δ15N values observed in organisms from both areas suggest that this benthic invertebrate could be a potential biomonitor for sewage-derived nutrients in coastal seas. Both nitrogen and carbon were enriched in heavy isotopes in organisms collected in Pirovac Bay, as well as in those from the area around the fish farm at Vrgada Island. These point toward an increased input of 15N and 13C enriched anthropogenic and/or aquaculture derived nitrogen and carbon into the local marine ecosystem. It is suggested that benthic filter feeders, such as B. perforatus, could be useful sentinels for detecting anthropogenically-derived inputs of nutrients into the coastal marine ecosystems. However, to get a better insight into the transfer rates of anthropogenic C and N into the food web, more extended research on a larger population is needed, as well as a detailed investigation of seasonal variation of abundance and isotopic composition of particulate organic matter as their presumed food source. [ABSTRACT FROM AUTHOR]

Analogues of insect juvenile hormones (juvenoids) have been tested for settling inhibition of cyprids from three species of barnacle, Balanus balanoides (L.), Balanus improvisus Darwin and Balanus amphitrite Darwin. Some 3-alkoxypyridine derivatives exhibited strong activity at mg litre-1 concentrations; 3,7-dimethyloctyl 2- methyl-5-pyridyl ether (8) gave an EC50 of 0.006 mg litre-1 when tested on B. balanoides. When compound 8 and similar juvenoids were incorporated into paints, test panels kept in seawater for S months were free of barnacles. [ABSTRACT FROM AUTHOR]

Cyprids are the final planktonic stage in the larval dispersal of barnacles and are responsible for surface exploration and attachment to appropriate substrata. The nanomechanical properties of barnacle ( Balanus amphitrite ) cyprid permanent cement were studied in situ using atomic force microscopy (AFM). Force curves were recorded from the cement disc continually over the course of its curing and these were subsequently analysed using custom software. Results showed a narrowing of the pull-off force distribution with time, as well as a reduction in molecular stretch length over time. In addition, there was a strong correlation between maximum pull-off force and molecular stretch length for the cement, suggesting ‘curing’ of the adhesive; some force curves also contained a ‘fingerprint’ of modular protein unfolding. This study provides the first direct experimental evidence in support of a putative ‘tanning’ mechanism in barnacle cyprid cement. [ABSTRACT FROM AUTHOR]

Shells of the blue mussel Mytilus edulis remain free of fouling organisms as long as they possess an intact periostracum, and a multiple antifouling defence that comprises a ripple-like microtopography and the production of chemical antifouling compounds has been suggested previously. This study investigates the chemical defence strategy of blue mussels for the first time. Six crude extracts of the periostracum of intact shells were made using solvents of increasing polarity. These extracts were tested against common fouling organisms in laboratory based bioassays. Non-polar and moderately polar fractions showed the highest activities: the diethyl ether fraction strongly inhibited attachment of Balanus amphitrite cyprids and the marine bacteria Cobetia marina and Marinobacter hydrocarbonoclasticus . Attachment of the benthic diatom Amphora coffeaeformis was significantly reduced by the dichloromethane extract, whereas both ethyl acetate and diethyl ether fractions slowed diatom growth. These results provide the first evidence of surface bound compounds that may moderate surface colonisation. [ABSTRACT FROM AUTHOR]

The potential driving force(s) of the vertical distribution of subtidal barnacle Balanus trigonus Darwin were investigated using both field and laboratory experiments. Early juveniles (∼24 h old) placed in intertidal [∼0.5 m above mean low water level (MLWL)] and subtidal (∼3 m below MLWL) habitats survived equally well, indicating that the intertidal absence of B. trigonus in Hong Kong waters was not determined by differential mortality. However, enhanced attachment of cyprids in subtidal habitats indicated the importance of differential larval choice in determining their vertical distribution. In the laboratory, cyprids preferred to attach in response to subtidal microbial films, which may implicate microbial films as a primary cue in driving the adult vertical distribution. Microbial films developed in these two habitats differed in their biomass (=total organic carbon), abundance of bacteria and diatoms (determined by fluorescence microscopy), and bacterial diversity (determined by DNA fingerprinting analysis). For example, 6-day films in subtidal habitat had a significantly higher biomass than in films from intertidal habitat ( P<0.05). There was no difference in the biomass of films from these two habitats in 9-day films ( P>0.05); however, bacterial abundance was greater in subtidal films than in intertidal films, irrespective of the age of the film, although there was no difference in diatom abundance in films from these two habitats. Neither the abundance of bacteria and diatoms nor the biomass correlated with the attachment preferences of cyprids. This study has not provided any data to prove the existence of inductive and inhibitive (to cyprid attachment) bacterial species in subtidal and intertidal films, respectively; however, results indicate that bacterial community provided qualitative information that might explain the preferential attachment of B. trigonus cyprids in subtidal habitat. [ABSTRACT FROM AUTHOR]

Barnacles, like many marine invertebrates, cause serious biofouling to marine industrial constructions and hulls of vessels as they attach themselves to such surfaces. Precise biochemical understanding of the underwater adhesion to surfaces requires a detailed characterization of the biology of the control of barnacle cement secretion and the proteins that make up the cement. In this study, we have investigated cement secretion by cyprid larvae of Balanus improvisus (D.) and the morphology of their cement glands. We studied the cement protein organization within cement granules and categorized the granules into four different types according to their size and morphology, before and after stimulation of secretion. In addition, we followed the exocytotic process of cement secretion in vivo and discovered that granules undergo a dramatic swelling during secretion. Such swelling might be due to an increased osmotic activity of granule contents, following a process of hydration. We hypothesize that this hydration is essential for exocytotic secretion and conclude that cement protein exocytosis is a more complex process than previously thought and is similar to exocytotic secretion in vertebrate systems, such as histamine secretion from mast cells and exocrine secretion in the salivary gland and the pancreas. [ABSTRACT FROM AUTHOR]

The ecological patterns of many invertebrate larvae remain an ongoing mystery, in large part owing to the difficult task of detecting them in the water column. The development of nucleic-acid–based technology has the potential to resolve this issue by direct identification and monitoring of embryonic and larval forms in situ. We report herein on the successful development and application of nucleic-acid–based sandwich hybridization assays that detect barnacles using rRNA-targeted probes with both group-(order Thoracica) and species-( Balanus glandula) specificity. Primary results include the determination of target 18S rRNA sequences and the construction of “capture” probes for detection of larvae using hybridization techniques. In addition, we modified existing protocols for whole cell hybridization of invertebrate larvae as confirmation of the sandwich hybridization results. We used both hybridization techniques successfully in the laboratory on a plankton time series collected over 3 months, as well as a week-long in situ deployment of the technique in Monterey Bay, CA. The adaptability of this technology promises to be further applicable to various organisms and could be used to enhance our understanding of larval presence in the world's oceans. [ABSTRACT FROM AUTHOR]

Post-copulatory behaviour in barnacles involves a violent rocking movement of the opercular valves, which is thought to contribute to the expulsion of oocytes through the oviduct into the mantle cavity where they are fertilised. We demonstrate in this study that the seminal vesicles/testis of the subtidal barnacle Balanus balanus produce a biologically active factor, barnacle muscle stimulatory factor (BMSF), which causes a significant increase in cirral and body muscular activity. BMSF was identified using a combination of high performance liquid chromatography and mass spectrometry as a novel eicosanoidloxylipin, 8,13-dihydroxyeicosapentaenoic acid. This is rapidly inactivated under mild acid conditions to form a complex range of triene and pentaene chromophore-containing products that have only been partially identified. Injection of purified BMSF into the mantle cavity of barnacles caused the rocking movements of the opercular valves as reported following fertilisation. In excised barnacles, it also caused muscular contractions of the whole body mass. The breakdown products of BMSF, however, were without such activities. The function of BMSF in facilitating fertilisation in barnacles is comparable to the role of other eicosanoids in human reproduction, reinforcing the view that these compounds have conserved activities in both invertebrates and vertebrates. [ABSTRACT FROM AUTHOR]

Abstract: Experiments were conducted to assess the effects of copper on larval development in the barnacle Balanus amphitrite. In the first experiment, we compared the sensitivity of three naupliar stages to copper stress. Molting inhibition occurred at copper concentrations ranging from 32μgl−1 in nauplius II to 128gl−1 in nauplius VI. EC50 for molting ranged from 97μgl−1 in nauplius II to 129gl−1 in nauplius VI. Decreased survival occurred at 128μgCul−1 in all of the naupliar stages tested, with LC50 ranging from 145 in nauplius II to 213μgl−1 in nauplius VI. In the second experiment, we examined effects of copper on the development from nauplius II to cyprid. The larvae reached cypris stage only in treatments of ⩽16μgCul−1. Our study therefore showed that molting was a more sensitive endpoint than survival, nauplius II was the most sensitive naupliar stage, and that whole larval development assay was more sensitive than assays using a particular larval stage. The results were discussed with respect to the use of this species in toxicity tests. [Copyright &y& Elsevier]

Theoretical and empirical research during the last decade suggests that increasing species richness often enhances ecosystem processes such as productivity, nutrient cycling, or resistance to disturbance. By analogous reasoning, it can be hypothesized that genetic diversity within species will have equivalent effects; however, this hypothesis has rarely been tested. We present experimental support for the positive effects of intraspecific diversity on a key trait: larval settlement in a marine invertebrate, the barnacle Balanus improvisus. Varying within-species diversity levels of an animal over nine experiments, we found increasing larval settlement with increasing diversity (one, two, or three parental broods). Possible mechanisms explaining this pattern include: (1) facilitation of gregarious response through the presence of founder genotypes, and (2) ensuring genetic complementarity to increase future reproductive potential. Our results indicate that changing intraspecific genetic diversity could have hitherto unrecognized community-scale implications for larval recruitment and space occupancy. [ABSTRACT FROM AUTHOR]

Planktonic larvae encounter variability in the marine environment as they develop, and rates of larval development are affected by changes in certain environmental variables. We examine the effects of variation in environmental parameters on the duration of the naupliar period of Balanus glandula larvae. Naupliar development rate is modeled as a function of temperature and food concentration. Simulations of the time course of development were driven by time series of temperature and food concentration collected at two locations on the US west coast. Predicted naupliar durations are reasonable in comparison to previous observations. Simulations of larval development and dispersal were driven by output of a three-dimensional physical circulation model and remotely sensed chlorophyll. These simulations demonstrate the impact of spatial variation in current velocity, temperature and chlorophyll on the duration of the larval period, the dispersal trajectory of these organisms and ultimately on recruitment success. Our naupliar development model coupled with a physical circulation model is a useful tool for addressing questions of intertidal population ecology. [ABSTRACT FROM AUTHOR]

Abstract: Two three-month sampling programs measuring Cd in the environment and a biomonitor (Balanus amphitrite) were undertaken in the austral winter of 2002 and summer of 2004 in Ross Creek, North Queensland, Australia. The objective was to test whether the burden of Cd in the biomonitor responded to any variation in the dissolved and particulate phase Cd concentrations in Ross Creek, caused by rainfall variation. The barnacles from the most Cd contaminated site were exposed to a total Cd concentration twice that in winter (93.6ngL−1) than in summer (45.6ngL−1). However, no significant variation was identified for the Cd concentration in the biomonitor between winter (8.4mgkg−1) and summer (7.4mgkg−1). A budget analysis based on a bioenergetic kinetic model indicated that Cd flux from food contributes >80% to the Cd concentration in B. amphitrite. A sensitivity analysis showed that physiological characteristics of the biomonitor are the key parameters controlling Cd accumulation in B. amphitrite, rather than the metal concentration in the dissolved or particulate phases. These two model''s outcomes suggest that a tight coupling between Cd in the biomonitor and its availability in the environment does not occur. [Copyright &y& Elsevier]

A C-type lectin (BRA-2) isolated from the acorn barnacle Megabalanus rosa, which was a glycoprotein having an N-linked sugar chain, was deglycosylated by N-glycopeptidase F. The structure of the released sugar chains was determined by a 2-D mapping method after derivatization with a fluorescent reagent, 2-aminopyridine, to be Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc and Manα1-6(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc. The structures were confirmed by matrix-assisted laser desorption ionization mass spectrometry and a comparison with authentic sugar chains by high-pressure liquid chromatography. Various properties of BRA-2 were examined before and after deglycosylation. The susceptibility of BRA-2 to protease digestion was increased by deglycosylation. However, the inhibitory activity toward calcium carbonate crystallization as well as the hemagglutinating activity of deglycosylated BRA-2 was significantly decreased. These results suggest that the sugar chains of BRA-2 are important to both its structural stability and its function. [ABSTRACT FROM AUTHOR]

A deep genetic cline between southern populations of the barnacle Balanus glandula (from about Monterey Bay southward) and northern populations (from northern California through Alaska) has recently been described. If this pattern is due to historical isolation and genetic drift, we expect it to have formed recently and represent a transient, nonequilibrium state. However, this cline appears to have formed well before the last glacial maximum. Our assays of sequence diversity at a region of mitochondrial cytochrome oxidase I, combined with coalescent estimators of the time of separation for these two regions, suggest that a late Pleistocene event more than 100 thousand years ago may be responsible for the initial separation. This suggests that either strong oceanographic mechanisms or natural selection have maintained the cline, because there has clearly been adequate time for this cline or polymorphism to resolve itself by genetic drift and migration. However, reliance on only a single mitochondrial marker for which the substitution rate has been estimated still limits the resolution of our analysis. [ABSTRACT FROM AUTHOR]

The article presents information on the use of biological indicators to monitor heavy metal contamination in the marine environment. The results indicate that gastropod species Balanus sp. and Patella caerulea are very efficient heavy metal accumulators. Zinc showed the highest levels among the accumulated heavy metals in both Balanus sp and Patella caerulea. The very high Cadmium obtained for the species of the genus Patella are remarkable as these species are consumed as seafood in many Mediterranean countries.

Fouling species produce adhesive polymers during the settlement, adhesion and colonization of new surfaces in the marine environment. The present paper tests the hypothesis that enzymes of the appropriate specificity may prevent biofouling by hydrolysing these adhesive polymers. Seventeen commercially available enzyme preparations designed originally for bulk use in a range of end-use applications were tested for their effects on the settlement and/or adhesion of three major fouling species, viz. the green alga Ulva linza , the diatom Navicula perminuta and the barnacle Balanus amphitrite . The serine-proteases were found to have the broadest antifouling potential reducing the adhesion strength of spores and sporelings of U. linza , cells of N. perminuta and inhibiting settlement of cypris larvae of B. amphitrite . Mode-of-action studies on the serine-protease, Alcalase, indicated that this enzyme reduced adhesion of U. linza in a concentration-dependent manner, that spores of the species could recover their adhesive strength if the enzyme was removed and that the adhesive of U. linza and juvenile cement of B. amphitrite became progressively less sensitive to hydrolysis as they cured. [ABSTRACT FROM AUTHOR]

In this field investigation the two cyclopeptides, isolated from the marine sponge Geodia barretti Bowerbank (Geodiidae, Astrophorida), are shown to be very efficient in preventing recruitment of the barnacle Balanus improvisus (Cirripedia, Crustacea) and the blue mussel Mytilis edulis (Protobranchia, Lamellibranchia) when included in different marine paints. These brominated cyclopeptides, named barettin and 8,9-dihydrobarettin were incorporated in different non-toxic coatings. The substances were used in the concentrations 0.1 and 0.01% in all treatments. The most efficient paint was a SPC polymer. This paint, in combination with barettin and 8,9-dihydrobarettin, reduced the recruitment of B. improvisus by 89% (barettin, 0.1%) and by 67% (8,9-dihydrobarettin, 0.1%) as compared to control panels. For M. edulis , the reduction of recruitment was 81% with barettin (0.1%) and 72% with 8,9-dihydrobarettin (0.1%) included in the SPC paint. This indicates that the two compounds from G. barretti could provide non-toxic alternatives as additives in antifouling paints, since the heavy metal-based marine paints are to be replaced. [ABSTRACT FROM AUTHOR]

Dispersal of propagules may have far-reaching con sequences for the local dynamics of open populations. In aquatic environments the dispersal and supply of larvae is strongly influenced by coastal-scale hydrodynamics. The role of local flow on settlement and recruitment is, however, poorly understood. In a test of the effect of local hydrodynamics on recruitment dynamics we studied the relationships between local flow speed and larval supply, contact rate, settlement, and recruitment rates for the barnacle Balanus improvisus. Planktonic cyprid larvae were sampled with pumps while suspended panels were used to measure initial contact (grease-coated panels), settlement (5-d immersion), and recruitment (30-d immersion). Larval supply varied with coastal-scale upwelling but was uncorrelated to local flow speed. Settlement rate was highly correlated to contact rate, and the proportion of settling larvae increased with established recruit density. In contrast to model predictions, contact rate was negatively correlated with local flow speed, which explained 33% of total variation. This correlation was maintained through settlement and recruitment suggesting that flow-mediated initial contact is an important link between larval supply and recruitment. No evidence from field studies indicated behavioral responses by larvae to flow although observations in a laboratory flume suggested active rejection of potential settlement sites at increasing flow speeds. It is suggested that initial adhesion is limited by flow speed through drag and lift forces acting on larvae. A conceptual model of mechanisms controlling the transfer of planktonic larvae to recruited benthic individuals is proposed. [ABSTRACT FROM AUTHOR]

Effects of two presumably dominant competitors, the blue mussel Mytilus edulis and the barnacle Balanus improvisus on recruitment, population dynamics and community structure on hard substrata were experimentally investigated in the subtidal Kiel Fjord, Western Baltic. The hypothesis that blue mussels and/or barnacles are local dominants and strongly influence succession and community structure was tested by monitoring succession in the presence and absence of simulated predation on either or both species. Manipulations included blue mussel removal, barnacle removal, combined blue mussel and barnacle removal, as well as a control treatment for natural (non-manipulated) succession. In the second part of the experiment, recovery from the treatments was monitored over 1 year.During the manipulative phase of the experiment, blue mussels had a negative effect on recruitment of species, whereas barnacles had no significant effect. Even so, a negative synergistic effect of blue mussels and barnacles was detected. Calculation of species richness and diversity H′ (Shannon Index) showed a negative synergistic effect of blue mussels and barnacles on community structure. Additionally, diversity H′ was negatively affected by the dominant competitor M. edulis. These effects were also detectable in the ANOSIM-Analysis. The non-manipulative phase of the experiment brought about a drastic loss of diversity and species richness. Blue mussels dominated all four communities. Barnacles were the only other species still being able to coexist with mussels. Effects of simulated predation disappeared fast.Thus, in the absence of predation on blue mussels, M. edulis within a few months dominates available space, and diversity of the benthic community is low. In contrast, when mussel dominance is controlled by specific predators, more species may persist and diversity remains high. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

The barnacle Balanus improvisus and the mussel Mytilus trossulus have been used as biomonitors of the trace metals Cu, Zn, Cd, Fe, Pb, Mn and Ni at five sublittoral sites in the Gulf of Gdansk (Baltic Sea) between February 2000 and September 2001. The study has established a benchmark against which future biomonitoring programmes will be able to establish changes in local metal pollution, particularly if metal loadings in the river Vistula (draining into the Gulf) alter in the future. The study highlighted differences in trace metal bioavailabilities to both barnacles and mussels, geographically and over time. Accumulated metal concentrations of Cu, Zn, Fe, Pb and Ni, but not Cd or Mn, were correlated in the barnacles and mussels, suggesting that the bioavailabilities of the former metals to the two biomonitors were similar. The barnacles showed greater discriminatory power than the mussels as trace metal biomonitors. Concentrations of trace metals in surficial sediments (<63 μm) did not correlate significantly with accumulated metal concentrations in either barnacles or mussels, indicating that sediment metal concentrations are not necessarily good proxy measures of ambient trace metal bioavailabilities to the local coastal filter feeders. [ABSTRACT FROM AUTHOR]

It has been proposed that seaweed secondary metabolites, e.g. brown algal phlorotannins, may have an ecologically important function as a chemical defence against epiphytes, by acting against colonisation of epiphytic organisms. We tested whether the low epiphytic abundance on the invasive brown seaweed Fucus evanescens, compared to the congeneric F. vesiculosus, is due to a more effective chemical defence against epiphyte colonisation. A field survey of the distribution of the common fouling organism Balanus improvisus (Cirripedia) showed that the abundance was consistently lower on F. evanescens than on F. vesiculosus. However, contrary to expectations, results from experimental studies indicated that F. vesiculosus has a more effective anti-settlement defence than F. evanescens. In settlement experiments with intact fronds of the two Fucus species, both species deterred settlement by barnacle larvae, but settlement was lower on F. vesiculosus both in choice and no-choice experiments. Phlorotannins from F. vesiculosus also had a stronger negative effect on larval settlement and were active at a lower concentration than those from F. evanescens. The results show that Fucus phlorotannins have the potential to inhibit settlement of invertebrate larvae, but that settlement inhibition cannot explain the lower abundance of the barnacle Balanus improvisus on F. evanescens compared to F. vesiculosus. Assessment of barnacle survival in the laboratory and in the field showed that this pattern could instead be attributed to a higher mortality of newly settled barnacles. Observation suggests that the increased mortality was due to detachment of young barnacles from the seaweed surface. This shows that the antifouling mechanism of F. evanescens acts on post-settlement stages of B. improvisus. [ABSTRACT FROM AUTHOR]

Barnacle adhesion strength was used to screen seventy-seven polydimethylsiloxane elastomeric coatings for fouling-release properties. The test coatings were designed to investigate the effect on barnacle adhesion strength of silicone fluid additive type, additive location, additive molecular weight, additive loading level, mixtures of additives, coating matrix type and coating fillers. The type of silicone fluid additive was the primary controlling factor in barnacle fouling-release. The type of silicone matrix in which the fluid resided was found to alter the effect on fouling-release. Two PDMS fluids, DMSC15 and DBE224, significantly reduced the adhesion strength of barnacles compared to unmodified elastomers. Optimum fouling-release performance was dependent on the interaction of fluid type and elastomeric matrix. [ABSTRACT FROM AUTHOR]

Hoplonemertines are carnivorous marine worms, which prey upon crustaceans and annelids. They paralyze their prey by injecting alkaloids with a stylet-bearing proboscis. The dermis of these animals also secretes alkaloids to repel predators. Besides affecting central and peripheral nervous system nicotinic receptors, some pyridyl alkaloids also activate certain chemoreceptor neurons in crustacean walking legs, which sense environmental chemicals. Anabaseine (2-[3-pyridyl]-3,4,5,6-tetrahydropyridyl) and 2,3′-bipyridyl (2,3′-BP) are two nemertine alkaloids, which potently paralyze crustaceans. Anabaseine is an agonist of vertebrate as well as invertebrate nicotinic receptors. While 2,3′-BP is non-toxic to mice, it is toxic to crustaceans. We tested a variety of nemertine pyridyl alkaloids for inhibition of barnacle (Balanus amphitrite) larval settlement and for crustacean toxicity in order to determine whether toxicity could be dissociated from inhibition of larval settlement. We prepared eight C-methylated 2,3′-BP isomers to determine where substitution is permitted without loss of activity. Anti-settlement and toxicity activities were not always related. For instance, 4′-methyl-2,3′-BP displayed only 3% of the crayfish paralytic activity of 2,3′-BP, but inhibited settlement almost 2-fold more effectively. Two other isomers displaying exceptional anti-settlement activity were the 4- and 5-methyl-2,3′-BPs; these also displayed high crustacean toxicity. Nemertelline inhibited barnacle settlement at concentrations similar to 2,3′-BP but was 136-fold less toxic when injected into crayfish. Thus, certain bipyridyls and tetrapyridyls may be useful anti-fouling additives. [Copyright &y& Elsevier]

Presents a study which described the relationship between uninterrupted emersion time and the zonation patterns of the mussel Mytilus californianus and the barnacle Balanus glandula using effective shore level (ESL). Methods used; Temporal patterns in wave height, ESL, and mussel temperature; Local-scale patterns of mussels and barnacles; Description of zonation shifts in response to wave action.