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Background By comparing spatial geographical structures of host populations with that of their symbionts light can be shed on their biological interactions, and the degree of congruence between host and symbiont phylogeographies should reflect their life histories and especially dispersal mechanisms. Methods Here, we analyzed the genetic diversity and structure of a host, the blue swimming crab, Portunus pelagicus, and its symbiotic pedunculate barnacle Octolasmis angulata from six location sites representing three geographic regions (north, central and south) along the Vietnam coastline. High levels of congruence in their phylogeographic patterns were expected as they both undergo planktonic larval stages. Results Based on the COI mtDNA markers, O. angulata populations showed higher genetic diversity in comparison with their host P. pelagicus (number of haplotype/individuals, haplotype and nucleotide diversity are 119/192, 0.991 ± 0.002 and 0.02; and 89/160, 0.913 ± 0.02 and 0.015, respectively). Pairwise Fst and AMOVA analyses showed a more pronounced population structure in the symbiotic barnacle than in its crab host. The DAPC analyses identified three genetic clusters. However, both haplotype networks and scatter plots supported connectivity of the host and the symbiotic barnacle throughout their distribution range, except for low subdivision of southern population. Isolation by distance were detected only for the symbiont O. angulata (R2 = 0.332, P = 0.05), while dbMEM supported spatial structure of both partners, but only at MEM-1 (Obs. 0.2686, P < 0.01 and Obs. 0.2096, P < 0.01, respectively).

Members of the infraclass Cirripedia, commonly called barnacles, are unique among the subphylum Crustacea in that they exhibit a biphasic life cycle with a planktonic larval stage and a sessile adult stage. Understanding their unique sessile life and mechanisms of attachment are hampered by the lack of genomic resources. Here, we present a 746 Mb genome assembly of Lepas anserifera – the first sequenced stalked barnacle genome. We estimate that Cirripedia first arose ~495 million years ago (MYA) and further diversified since Mesozoic. A demographic analysis revealed remarkable population changes of the barnacle in relation to sea-level fluctuations in the last 2 MYA. Comparative genomic analyses revealed the expansion of a number of developmental related genes families in barnacle genomes, such as Br–C, PCP20 and Lola, which are potentially important for the evolution of metamorphosis, cuticle development and central nervous system. Phylogenetic analysis and tissue expression profiling showed the possible roles of gene duplication, functional diversification and co-option in shaping the genomic evolution of barnacles. Overall, our study provides not only a valuable draft genome for comparative genomic analysis of crustacean evolution, but also facilitates studies of biofouling control.

Barnacles are key marine crustaceans in several habitats, and they constitute a common practical problem by causing biofouling on man-made marine constructions and ships. Despite causing considerable ecological and economic impacts, there is a surprising void of basic genomic knowledge, and a barnacle reference genome is lacking. We here set out to characterize the genome of the bay barnacle Balanus improvisus (= Amphibalanus improvisus) based on short-read whole-genome sequencing and experimental genome size estimation. We show both experimentally (DNA staining and flow cytometry) and computationally (k-mer analysis) that B. improvisus has a haploid genome size of ~ 740 Mbp. A pilot genome assembly rendered a total assembly size of ~ 600 Mbp and was highly fragmented with an N50 of only 2.2 kbp. Further assembly-based and assembly-free analyses revealed that the very limited assembly contiguity is due to the B. improvisus genome having an extremely high nucleotide diversity (π) in coding regions (average π ≈ 5% and average π in fourfold degenerate sites ≈ 20%), and an overall high repeat content (at least 40%). We also report on high variation in the α-octopamine receptor OctA (average π = 3.6%), which might increase the risk that barnacle populations evolve resistance toward antifouling agents. The genomic features described here can help in planning for a future high-quality reference genome, which is urgently needed to properly explore and understand proteins of interest in barnacle biology and marine biotechnology and for developing better antifouling strategies. [ABSTRACT FROM AUTHOR]

Due to the adverse environmental impacts of toxic heavy metal–based antifoulants, the screening of environmentally friendly antifoulants has become important for the development of marine antifouling technology. Compared with the traditional lengthy and costly screening method, computer-aided drug design (CADD) offers a promising and efficient solution that can accelerate the screening process of green antifoulants. In this study, we selected barnacle chitin synthase (CHS, an important enzyme for barnacle settlement and development) as the target protein for docking screening. Three CHS genes were identified in the barnacle Amphibalanus amphitrite , and their encoded proteins were found to share a conserved glycosyltransferase domain. Molecular docking of 31,561 marine natural products with AaCHSs revealed that zoanthamine alkaloids had the best binding affinity (−11.8 to −12.6 kcal/mol) to AaCHSs. Considering that the low abundance of zoanthamine alkaloids in marine organisms would limit their application as antifoulants, a marine fungal–derived natural product, mycoepoxydiene (MED), which has a similar chemical structure to zoanthamine alkaloids and the potential for large-scale production by fermentation, was selected and validated for stable binding to AaCHS2L2 using molecular docking and molecular dynamics simulations. Finally, the efficacy of MED in inhibiting cyprid settlement of A. amphitrite was confirmed by a bioassay that demonstrated an EC 50 of 1.97 μg/mL, suggesting its potential as an antifoulant candidate. Our research confirmed the reliability of using AaCHSs as antifouling targets and has provided insights for the efficient discovery of green antifoulants by CADD. • CADD has the potential to accelerate the screening of eco-friendly antifoulants. • Zoanthamine alkaloids exhibit superior binding affinity to barnacle chitin synthase. • Mycoepoxydiene shows efficacy (EC 50 : 1.97 μg/mL) as an antifoulant candidate. [ABSTRACT FROM AUTHOR]

Here we present the complete mitochondrial genome of Tetraclita squamosa squamosa, which is 15,191 bp in length with 67.20% AT content. It contains 13 protein-coding genes, 2 ribosomal-RNA genes and 22 transfer-RNA genes. All PCGs except nad4l in T. squamosa squamosa start with ATN, and terminated with a complete stop codon, except nad3. Phylogenetic analysis based on mitochondrial PCGs shows that T. squamosa squamosa is clustered with T. serrata into a branch (BP = 100). Our result is consistent with previous reports that genus Tetraclita and family Tetraclitidae are not monophyletic. This study contributes to further phylogenetic analysis within Cirripedia.

Predators influence prey demography through consumption, but the mere presence of predators may trigger behavioural changes in prey that, if persistent or intense, may also influence prey demography. A tractable system to study such nonconsumptive effects (NCEs) of predators involves intertidal invertebrates. This mini review summarises recent research using barnacles and mussels as prey and dogwhelks as predators. The field manipulation of dogwhelk density revealed that pelagic barnacle larvae avoid benthic settlement near dogwhelks, which limits barnacle recruitment, a relevant outcome because recruitment is the only source of population replenishment for barnacles, as they are sessile. This avoidance behaviour is likely triggered by waterborne dogwhelk cues and may have evolved to limit future predation risk. Increasing densities of barnacle recruits and adults can prevent such NCEs from occurring, seemingly because benthic barnacles attract conspecific larvae through chemical cues. Barnacle recruit density increased with the abundance of coastal phytoplankton (food for barnacle larvae and recruits), so barnacle food supply seems to indirectly limit dogwhelk NCEs. By inhibiting barnacle feeding, dogwhelk cues also limited barnacle growth and reproductive output. Wave action weakens dogwhelk NCEs likely through hydrodynamic influences. Dogwhelk cues also limit mussel recruitment, as mussel larvae also exhibit predator avoidance behaviour. The NCEs on recruitment are weaker for mussels than for barnacles, possibly because mussel larvae can detach themselves after initial settlement, an ability that barnacle larvae lack. Overall, these field experiments provide evidence of predator NCEs on prey demography for coastal marine systems.

A new species of verrucid barnacle, Gibbosaverruca weijiai sp. nov., is described and illustrated based on specimens collected from a deep-sea seamount, Weijia Guyot, in the West Pacific. This is the third barnacle species reported from Weijia Guyot. The new species is distinguished from its congeners by its extremely long caudal appendage. In terms of shell morphology, G. weijiai sp. nov. is most similar to G. gibbosa and G. sulcata but differs from them by the intermediate articular ridges of its movable tergum and scutum, which are distinctly wider than the axial ridges. The COI and 16S rRNA sequences of the holotype of G. weijiai sp. nov. are presented to support future research, and a key to extant species of the genus Gibbosaverruca Young, 2002 is provided.

Although diatoms colonize a vast diversity of immersed hard-surfaced objects and organisms, many diatom species, and sometimes entire genera, show a clear preference towards a particular type of substratum. Studies of animal-associated diatoms indicate that some epizoic forms may require this specific habitat to thrive, and new diatom taxa are expected to be found on as yet unexplored animal hosts. The current study is the first to investigate the diatom flora of sea snakes. Three museum specimens of yellow-bellied sea snakes (Hydrophis platurus) collected over a period of 23 years from the south-eastern coast of South Africa were examined for their diatom flora. Diatoms were abundant on the sea snakes, but communities were composed of only a few species. A previously undescribed species of Nagumoea contributed over 99% of the total diatom assemblage on both the sea snake skin and sea-snake-associated barnacles (Octolasmis sp.). This diatom dominant is described here as Nagumoea hydrophicola sp. nov., based on detailed observations of its frustule ultrastructure using light and scanning electron microscopy. The species is most similar to N. serrata, sharing a similar valvocopula morphology with two rows of pores. However, it can be distinguished from all currently known congeners by its lanceolate central area, short distal raphe endings not reaching the valve mantle, and doubly perforated abvalvar girdle bands. Environmental preferences of the new species are discussed in the context of its host's biology. [ABSTRACT FROM AUTHOR]

The current study focuses on four species from the primarily marine diatom genus Craspedostauros that were observed growing attached to numerous sea turtles and sea turtle‐associated barnacles from Croatia and South Africa. Three of the examined taxa, C. danayanus sp. nov., C. legouvelloanus sp. nov., and C. macewanii sp. nov., are described based on morphological and, whenever possible, molecular characteristics. The new taxa exhibit characters not previously observed in other members of the genus, such as the presence of more than two rows of cribrate areolae on the girdle bands, shallow perforated septa, and a complete reduction of the stauros. The fourth species, C. alatus, itself recently described from museum sea turtle specimens, is reported for the first time from loggerhead sea turtles rescued in Europe. A 3‐gene phylogenetic analysis including DNA sequence data for three sea turtle‐associated Craspedostauros species and other marine and epizoic diatom taxa indicated that Craspedostauros is monophyletic and sister to Achnanthes. This study, being based on a large number of samples and animal specimens analyzed and using different preservation and processing methods, provides new insights into the ecology and biogeography of the genus and sheds light on the level of intimacy and permanency in the host–epibiont interaction within the epizoic Craspedostauros species. [ABSTRACT FROM AUTHOR]

The acorn barnacle (Cirripedia: Balanomorpha) is a sessile crustacean arthropod, distributing around the intertidal areas of tropical and temperate regions worldwide. Current practices for taxonomic identification are based on shell morphology and light microscopy, together with the use of scanning electron microscopy for arthropodal characters, which the latter technique requires complicated procedures. Through the recent technology of confocal light-sheet microscopy, here we demonstrate a clear description of Caudoeuraphia caudata (Pilsbry, 1916), a new record of its presence in eastern Thailand. This type of microscopy enables the high acquisition of fluorescent imaging of a whole barnacle’s body and arthropodal structures, including cirri and mouthpart imaging in three dimensions, with simple procedures for sample preparation and through harboring autofluorescence of their own barnacle structures. Hence, this technology could potentially be an alternative way for identifying acorn barnacles at the species-level and visualizing the diversity of these marine arthropods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Acorn barnacle Microeuraphia depressa (Poli, 1791) (Thecostraca: Balanomorpha: Chthamalidae) was recently found (March 2021), in the Romanian Black Sea. Compact populations were found during a rapid biofouling survey in Constanta harbour on artificial hard substrata from the waterline up to 20 cm. Some hypothesis regarding actual and historical presence in the Romanian waters are discussed. [ABSTRACT FROM AUTHOR]

Barnacles are ancient arthropods that, as adults, are surrounded by a hard, mineralized, outer shell that the organism produces for protection. While extensive research has been conducted on the glue-like cement that barnacles use to adhere to surfaces, less is known about the barnacle exoskeleton, especially the process by which the barnacle exoskeleton is formed. Here, we present data exploring the changes that occur as the barnacle cyprid undergoes metamorphosis to become a sessile juvenile with a mineralized exoskeleton. Scanning electron microscope data show dramatic morphological changes in the barnacle exoskeleton following metamorphosis. Energy-dispersive X-ray spectroscopy indicates a small amount of calcium (8%) 1 h post-metamorphosis that steadily increases to 28% by 2 days following metamorphosis. Raman spectroscopy indicates calcite in the exoskeleton of a barnacle 2 days following metamorphosis and no detectable calcium carbonate in exoskeletons up to 3 h post-metamorphosis. Confocal microscopy indicates during this 2 day period, barnacle base plate area and height increases rapidly (0.001 mm2 h−1 and 0.30 µm h−1, respectively). These results provide critical information into the early life stages of the barnacle, which will be important for developing an understanding of how ocean acidification might impact the calcification process of the barnacle exoskeleton.

Dozens of samples of stalked barnacles were collected from deep-sea seamounts of the tropical western Pacific by remotely operated vehicles during two expeditions in 2017 and 2018. Integrative taxonomy indicates that they represent two new species belonging to the families Scalpellidae and Poecilasmatidae, respectively. In terms of morphology, Arcoscalpellum angularum sp. nov. is distinguished from congeneric species by the angular processes on the dorsum of its soft body and the absence of a caudal appendage, whereas Glyptelasma robustum sp. nov. differs from its congeners in its robust peduncle, semicircular concaved carina, and long filamentary appendages. The validity of the two new species is supported by genetic analyses inferred from COI gene sequences and geographic distribution. To date, very few seamounts in the oceans have been investigated for scientific purposes, and records about barnacles inhabiting seamounts are chaotic. A literature search reveals about 125 barnacle species recorded in seamounts mainly in the eastern and western regions of the Pacific Ocean. Existing data are insufficient for research on species speciation and diffusion; still more credible data on the distribution of barnacles in seamounts should be collected.

Thermal stress is an important driver of species’ distribution in the intertidal zone and, with the forecasted increasing frequency of extreme high temperatures associated with climate change, is likely to play an even greater role in the future. To better understand the scales at which thermal stress impacts organisms, we used biomimetic temperature loggers (robobarnacles) to measure latitudinal variation in estimated barnacle body temperatures (Tetraclita spp.) and evaluated the influences of large, geographic, and smaller scale, microhabitat variation on temperatures experienced. Robobarnacles were deployed at nine sites along the West Pacific and South China Sea coast (five sites in Taiwan, three in Hong Kong and one in Thailand, spanning 13–25°N) from May to September 2013. Estimated body temperatures did not follow a latitudinal gradient; instead, they revealed a mosaic of hot (e.g., NE Taiwan and Thailand) and cooler sites (e.g., two sites in Hong Kong). The hot sites were characterized by frequent occurrences of “heat stress” events (estimated body temperatures ≥40°C for ≥2 h which would result in ≥50% Tetraclita entering coma). There was a correlation between hourly air temperatures and robo-temperatures, suggesting that air temperature together with solar radiation and thermal radiation re-emitted by the rocky substrate drove the observed spatial robo-temperature variation. Air temperature mediated by solar radiation and rock thermal radiation are, therefore, important contributors affecting the body temperature of sessile intertidal species in the tropical and subtropical W Pacific and South China Sea and can be a good predictor for body temperature and thermal stress of intertidal barnacles.

Biofouling community structure was studied in a tropical monsoon-influenced Mandovi estuary in Goa, west coast of India. Monthly, seasonal and yearly observations on biofouling on polyvinyl chloride (PVC) panels immersed at subsurface water level were recorded and photographed from May 2012 to September 2013. The barnacle Balanus amphitrite was the dominant fouling organism followed by calcareous polychaetes. The settlement and recruitment of barnacles took place year-round, with the exception of July 2012 and June 2013 (monsoon months). However, their peak abundance was observed during the later months of monsoon (August and September). Polychaetes were dominant during late post-monsoon and pre-monsoon months (December 2012 to April 2013). Silt and slime were observed throughout the observation period. Comparing the fouling pressure of barnacles in the two monsoon seasons (2012 and 2013), fouling was more intense during the monsoon of 2013, indicating an inter-annual variation in the fouling community.

Larvae of intertidal species develop in the coastal ocean, and the last body of water they must cross while migrating back to shore is the surf zone. We hypothesized that the surf zone is a semipermeable barrier to this shoreward migration and that differences in water exchange across the surf zone result in temporal and spatial variation in larval delivery to the shore. We tested the hypotheses that larval delivery 1) should increase with larger waves and 2) should be higher on more dissipative beaches than on more reflective beaches. We found a significant positive correlation between the daily averaged ratio of wave height to wave period (H/. T) and daily cyprid settlement at Dike Rock, California and Bastendorff Beach, Oregon, USA. We tested the second hypothesis by comparing populations of barnacles, limpets, and benthic algae on rocks on four more dissipative and six more reflective sandy beaches in northern California and southern Oregon. Newly recruited barnacles and limpets were significantly more abundant at more dissipative than reflective beaches, and the higher abundance was most likely due to differences in settlement rather than post-settlement mortality. The density and percent cover of barnacles and the density of limpets were significantly higher at more dissipative beaches. In contrast, the density and percent cover of algae were significantly higher at more reflective beaches. The results are consistent with the hypothesis that the surf zone is a semipermeable barrier to the shoreward migration of larvae and that differences in water exchange across the surf zone as function of the beach hydrodynamics result in temporal and spatial variation in larval delivery to the shore. © 2010 Elsevier B.V.

Sensory systems provide critical filters that enable organisms to detect and recognize valuable resources. Trophic cascades, structuring populations and communities, are determined to a large degree by trait-mediated interactions that rely on sensory inputs. Certain molecules serve as chemosensory stimuli and play keystone roles in determining outcomes of predator-prey dynamics at multiple trophic levels. Here, a surface-adsorbed glycoprotein signal molecule, MULTIFUNCin, is fully identified and its role in waveswept rocky intertidal community dynamics investigated. Barnacles (Balanus glandula), are constrained to produce MULTIFUNCin for cuticle/shell formation. This compound evoked settlement by conspecifics larvae in field assays, and thus, operates as seminal cue for recruitment. Moreover, the same substances triggered predation by a numerically dominant whelk species (Acanthinucella spirata) on barnacle juveniles and adults in lab and field experiments. This glycoprotein, therefore, balances simultaneous demographic processes that enhance, and diminish, barnacle populations. As dominant competitors for space, the relative equilibrium between barnacle recruitment and predation mortality has strong, cascading direct and indirect effects on community dynamics. Hence, MULTIFUNCin plays a keystone role within rocky intertidal habitats.

Here we present the complete mitochondrial genome of Megabalanus tintinnabulum. The genome is 15,107 bp in length with a 67.35% AT content. It contains 13 protein-coding genes (PCGs), 2 rRNAs genes, and 22 tRNAs. Both rRNAs are encoded on the light strand, as in the other crustacean and barnacle mitochondrial genomes. Besides five tRNAs are encoded on the light strand (nad1, trnV, trnL1, trnC, trnQ, and trnK). Only one PCG is encoded on the light strand (nad1), whereas the other 12 PCGs are located on the heavy strand, which is consistent with M. ajax. Phylogenetic analysis based on mitochondrial PCGs shows that M. tintinnabulum is clustered with M. ajax into a branch (BP = 100), and the group with M. volcano with high support. This study contributes to further phylogenetic analysis within Cirripedia.

We analyzed patterns of aggregation and spatial distribution of the epizoic barnacle Xenobalanus globicipitis on the flukes of Mediterranean striped dolphins, Stenella coeruleoalba, assessing its potential use as an indicator of the host's hydrodynamics based on data from 55 dolphins. Barnacles occurred along the trailing edge with the cirri oriented towards the oncoming flow. Nearest neighbor analyses suggested that new recruits actively seek placement next to already settled barnacles, forming aggregations possibly to facilitate copulation. The probability of spanwise settlement strongly increased with fluke width (presumably enabling prolonged leading‐edge vorticity), and with chordwise length where pressure is predicted to be positive. Consequently, clustering tended to increase nonlinearly towards the fluke notch. Furthermore, it was three times more likely for barnacles to occur on the dorsal vs. ventral side of flukes, at an average abundance ca. 12 times higher. This difference could result from a host's asymmetric oscillation of the tail, which would alter leading‐edge vorticity, and/or an interaction between the wake produced by the dorsal fin and the flow associated with flukes. Both processes could primarily enhance cyprid contact and/or attachment on the dorsal side. This study offers a starting point for future comparison with other cetaceans. [ABSTRACT FROM AUTHOR]

Background: Barnacles are specialized marine organisms that differ from other crustaceans in possession of a calcareous shell, which is attached to submerged surfaces. Barnacles have a wide distribution, mostly in the intertidal zone and shallow waters, but a few species inhabit the deep-sea floor. It is of interest to investigate how such sessile crustaceans became adapted to extreme deep-sea environments. We sequenced the transcriptomes of a deep-sea barnacle, Glyptelasma gigas collected at a depth of 731 m from the northern area of the Zhongjiannan Basin, and a shallow-water coordinal relative, Octolasmis warwicki. The purpose of this study was to provide genetic resources for investigating adaptation mechanisms of deep-sea barnacles. Results: Totals of 62,470 and 51,585 unigenes were assembled for G. gigas and O. warwicki, respectively, and functional annotation of these unigenes was made using public databases. Comparison of the protein-coding genes between the deep- and shallow-water barnacles, and with those of four other shallow-water crustaceans, revealed 26 gene families that had experienced significant expansion in G. gigas. Functional annotation showed that these expanded genes were predominately related to DNA repair, signal transduction and carbohydrate metabolism. Base substitution analysis on the 11,611 single-copy orthologs between G. gigas and O. warwicki indicated that 25 of them were distinctly positive selected in the deep-sea barnacle, including genes related to transcription, DNA repair, ligand binding, ion channels and energy metabolism, potentially indicating their importance for survival of G. gigas in the deep-sea environment. Conclusions: The barnacle G. gigas has adopted strategies of expansion of specific gene families and of positive selection of key genes to counteract the negative effects of high hydrostatic pressure, hypoxia, low temperature and food limitation on the deep-sea floor. These expanded gene families and genes under positive selection would tend to enhance the capacities of G. gigas for signal transduction, genetic information processing and energy metabolism, and facilitate networks for perceiving and responding physiologically to the environmental conditions in deep-sea habitats. In short, our results provide genomic evidence relating to deep-sea adaptation of G. gigas, which provide a basis for further biological studies of sessile crustaceans in the deep sea. [ABSTRACT FROM AUTHOR]

Sex allocation theory predicts that the optimal sexual resource allocation of simultaneous hermaphrodites is affected by mating group size (MGS). Although the original concept assumes that the MGS does not differ between male and female functions, the MGS in the male function (MGSm; i.e., the number of sperm recipients the focal individual can deliver its sperm to plus one) and that in the female function (MGSf; the number of sperm donors plus one) do not always coincide and may differently affect the optimal sex allocation. Moreover, reproductive costs can be split into "variable" (e.g., sperm and eggs) and "fixed" (e.g., genitalia) costs, but these have been seldom distinguished in empirical studies. We examined the effects of MGSm and MGSf on the fixed and variable reproductive investments in the sessilian barnacle Balanus rostratus. The results showed that MGSm had a positive effect on sex allocation, whereas MGSf had a nearly significant negative effect. Moreover, the "fixed" cost varied with body size and both aspects of MGS. We argue that the two aspects of MGS should be distinguished for organisms with unilateral mating. [ABSTRACT FROM AUTHOR]

A series of indole-1-carboxylic acid aryl esters was synthesized with indole and substituted phenols as raw materials. The structures of the target compounds were validated by IR and 1H-NMR spectroscopies. The inhibitory activities of the target compounds and their potencies against marine fouling organisms were investigated. The results showed that the target compounds had significant inhibitory effects on the growth of three seaweeds: Isochrysis galbana, Platymonas subcordiformis, and Navicula, and the target compounds also had excellent inhibition on the survival of barnacle larvae. The substituent structure–activity relationships revealed a significant effect on biological inhibition activity: Compounds substituted by electron-withdrawing groups had greater bioactivities than those containing electron-donating groups. Release rate of antifoulant and marine field tests indicated the final compounds had an outstanding antifouling potency against marine fouling organisms. [ABSTRACT FROM AUTHOR]

In this study, antifouling and antibacterial properties of polar, semi polar and non-polar bioactive compounds derived from the sea cucumber Holothuria leucospilota were investigated. A series comprising n-hexane, ethyl acetate and methanol extracts from four different organs of sea cucumber (body wall, gonad, digestive tract and respiratory tree) were investigated for their antibacterial and antifouling activity against two species of microalgae, larvae of barnacle Amphibalanus amphitrite and a non-target organism: larvae of Artemia salina. Results showed that the highest antibacterial activity was found in the ethyl acetate extract of body wall against Staphylococcus aureus with minimum inhibitory concentration (MIC) of 0.250 mg/mL. The MIC of ethyl acetate extract of body wall ranged between 0.062 and 0.250 mg/mL against two microalgal strains. All extracts showed moderate to low toxicity against larvae of barnacles. The most pronounced anti-barnacle activity was found in the ethyl acetate extract of body wall with median lethal concentration (LC50) value of 0.049 mg/mL. Among the twelve extracts, the ethyl acetate extracts of body wall showed the maximum antibacterial and antifouling activities. The bioactive compounds of the ethyl acetate extract of the sea cucumber body wall were determined using gas chromatography coupled with mass spectrometry. Fatty acids and terpenes were the major compounds, which may be responsible for antibacterial and antifouling activity of the ethyl acetate extract of body wall of the sea cucumber H. leucospilota. [ABSTRACT FROM AUTHOR]

The Gippsland Lakes estuary, a Ramsar listed wetland, in Victoria, Australia, is an area of potential concern for metal pollution due to influxes of human population and associated anthropogenic activities. A biomonitoring exercise was undertaken where the concentrations of 9 metals (Cr, Fe, Cu, Zn, As, Se, Ag, Cd and Hg) were analysed in the soft tissue of two common sessile invertebrates: the mussel Mytilus edulis and the barnacle Amphibalanus variegatus from 6 locations on two different occasions throughout the Gippsland Lakes estuary. A salinity gradient exists in the Lakes, from seawater at Lakes Entrance in the east, decreasing down to < 10 PSU in the west at Lake Wellington during times of rainfall, which is a major factor governing the growth and distribution of both species. Dissolved metal levels in general were low; however, Cu at most sites exceeded the 90% trigger values, while all Zn concentrations exceeded the lowest 80% trigger values of the ANZECC marine water quality guidelines for environmental health. Elevated levels of Cu and Zn were found particularly in barnacles at some sites with environmental contamination due to leaching from anti fouling paints and sacrificial zinc anodes. Elevated levels of Ag and Cd were found in mussels at the Hollands Landing site, which is immediately adjacent to a boat ramp, and Cd and Ag at this site are suspected to originate from inland anthropogenic sources. Concentrations of As in M. edulis across all 6 sites in both sampling periods had mean wet weight As concentrations exceeding the maximum level stated in the FSANZ guidelines. A. variegatus contained elevated levels of Hg especially at the North Arm site with a maximum of 13.6 μg Hg/g dry wt., while A. variegatus also showed temporal changes in Hg concentrations across sites. The maximum Hg concentration found in Mytilus edulis was 1.49 μg Hg/g dry wt. at the Hollands Landing site. Previous contaminant studies of biota in the Lakes have targeted sampling of singular predatory or migratory species, such as Black Bream (Acanthopagrus butcheri) and the Burrunan dolphin (Tursiops australis). This is the first biomonitoring study conducted on sessile organisms to assess metal contamination in the system. [ABSTRACT FROM AUTHOR]

A new species of rhizocephalan barnacle is described parasit-izing the Florida lobsterette Nephropsis aculeata Smith, 1881. This is the first record of a nephropoid as a host for any rhizocephalan and represents the first record of a rhizocephalan parasitizing any marine lobster (Achelata, Astacidea, Glypheidea, Polychelida). The new species belongs to the genus Parthenopea Kossmann, 1874, which now contains three species: Parthenopea australis Lützen, Glenner & Lörz, 2009 (on a callianassid in New Zealand), P. subterranea Kossmann, 1874 (on a callianassid and an axiid in the Skagerrak strait, Black Sea, and Mediterranean), and P. reinhardi n. sp. (on N. aculeata from Dry Tortugas, Florida, USA). The new species can be distinguished from the other two in the genus based on the shape of the seminal receptacle ducts (proximally straight in P. subterranea versus coiled in P. reinhardi n. sp.) and annuli on the stalk (present in in P. australis but absent in P. reinhardi n.sp.) and the position of the mantle opening (on the surface and close to the stalk in P. australis versus in a groove and more distant from the stalk in P. reinhardi n. sp.). We urge researchers and fisheries scientists working on marine lobsters to examine specimens for rhizocephalans, potentially leading to additional new records among lobster hosts. [ABSTRACT FROM AUTHOR]

One of the global problems in developing and the developed countries is contamination of aquatic ecosystems to heavy metals. In this study, the amounts of cadmium (Cd) in the shell of Amphibalanus improvisus (barnacle) and Mytilaster lineatus (mussel) were measured as biological monitoring marker of Cd on the central southern coast of the Caspian Sea. Samples were collected during four consecutive seasons between October 2015 and October 2016 from the coast of the Mazandaran province. The hard tissue of the samples was chemically digested and then the Cd was analyzed by atomic absorption spectrometry. The results showed that the maximum and minimum Cd concentration for barnacle (32.96 and 1.46 µg/g dry wight) was observed in spring and winter respectively, while the values for mussel have been 8.16 and 0.72 µg/g dry wight. These species can be introduced as a biological indicator due to the accumulation of Cd in their shells with concentrations higher than the water and sediment.

The effects of ocean acidification (OA) and warming on the physiological processes of many marine species have been well documented. However, far less is known about the impacts of these global variables on chemical communication. In this study, we identified the barnacle waterborne settlement pheromone (BWSP) of Balanus albicostatus as adenosine (Ado). Our results showed that neither elevated temperature (30 °C vs. ambient 26 °C) nor elevated pCO 2 (1000 μatm vs. ambient 400 μatm) significantly affected the release of Ado from B. albicostatus adults. Exposure to elevated temperature and OA did not impair larval cue perception for settlement in B. albicostatus ; however, OA inhibited settlement under elevated temperature in the absence/presence of BWSP, and elevated temperature induced larval settlement only in the presence of BWSP under ambient pCO 2 condition. These results provided important insights into barnacle aggregation behavior in changing oceans and may help to predict the consequences of climate change on barnacle populations. [Display omitted] • Barnacle waterborne settlement pheromone (BWSP) was identified as adenosine. • Ocean acidification (OA) inhibited barnacle settlement under elevated temperature. • Elevated temperature induced settlement under BWSP and ambient pCO 2. • Elevated temperature and OA did not affect adult release of adenosine in barnacles. [ABSTRACT FROM AUTHOR]

Until recently, the common wisdom among scientists was that larvae are passive drifters, tossed at the whim of powerful waves and currents. Where they settled was believed to be a matter of random chance. This theory had holes ,however, since field observations consistently showed that settlement rates are higher on preferred reef materials.

The intertidal population of the barnacles Semibalanus balanoides has been explored in the estuarine zone of the Tuloma River at the end of the Kola Bay for the first time. Barnacles S. balanoides are typical species for the littoral zone of the northern seas, they populate both the high and low salinity areas along the coast of the Barents Sea. The ecology and distribution of barnacle population in estuarine intertidal zones of the Barents Sea are not studied previously, and under the critical salinity conditions of any estuary, in particular. The investigation have been carried out on the littoral of the western (left) shore of the southern tribe of the Kola Bay – the estuary section from the Tuloma bridge to the Cape Elovy. The studied site is a sandy-boulder beach with stony bars, its length is about 1 150 m, the area is about 126 500 m2. Counting the number of S. balanoides in clusters has been performed on site (without removal of the copepods from the population) by the standard method for intertidal sampling. Simultaneously with the defining the number of barnacles for the period 2003–2014, the measurements of salinity and temperature of water and air have been made. The peculiarity of the estuarine barnacle population is their complete absence in the upper horizon of the littoral, and in the middle and the lower horizons they are found only within the channels of the littoral streams (3–20 specimens in the sample). For the first time the abundance and biomass of barnacles S. balanoides in this estuarine population has been determined, and the causes of their narrow-local distribution on the estuary littoral of the Tuloma River have been revealed. The main ecological factors determining the abundance and specific distribution of barnacles under the conditions of estuarine littoral have been established. The regular increase in the density of adult S. balanoides settlements along the gradient of water salinity from the Tuloma River to the sea has been shown. The long-term fluctuations in the abundance of barnacle S. balanoides have been found, associated, obviously, with climate changes.

Colonization of the benthic environment requires planktonic larvae to settle from the water column and metamorphose to a juvenile stage. For many species, planktonic larvae can discriminate between settlement sites; the larvae not only choose consistently between substrates in the laboratory, but cluster on preferred substrates in the field. Chemical properties of benthic environments are known to provide essential cues for larvae actively colonizing habitat sites. The requirements for chemical inducers to trigger settlement and metamorphosis can be exploited for ecological management and commercial benefits.

The morphology and ultrastructure of the shells of two balanid species have been examined, paying special attention to the three types of boundaries between plates: (i) radii-parietes, (ii) alae-sheaths, and (iii) parietes-basal plate. At the carinal surfaces of the radii and at the rostral surfaces of the alae, there are series of crenulations with dendritic edges. The crenulations of the radius margins interlock with less prominent features of the opposing paries margins, whereas the surfaces of the longitudinal abutments opposing the ala margins are particularly smooth. The primary septa of the parietes also develop dendritic edges, which abut the internal surfaces of the primary tubes of the base plates. In all cases, there are chitino-proteinaceous organic membranes between the abutting structures. Our observations indicate that the very edges of the crenulations and the primary septa are permanently in contact with the organic membranes. We conclude that, when a new growth increment is going to be produced, the edges of both the crenulations and the primary septa pull the viscoelastic organic membranes locally, with the consequent formation of viscous fingers. For the abutting edges to grow, calcium carbonate must diffuse across the organic membranes, but it is not clear how growth of the organic membranes themselves is accomplished, in the absence of any cellular tissue.

Presence of high amount of polysaccharide and polyphenolic compounds in barnacles restricts the isolation of high molecular weight good quality DNA. CTAB, which is a detergent used to isolate DNA from high polysaccharide containing plants, is used in this study to extract quality DNA from ship barnacle. This modified CTAB method is simple, efficient and quick enough to be carried out within 2 h. Taking DNAzol ® isolated DNA as a reference, restriction digestion and PCR was performed to prove the absence of any enzyme inhibitory substances in the isolate. Traditional phenol-chloroform and salting out method failed to even isolate the DNA from barnacle sample. The molecular weight of the modified CTAB extracted DNA was higher than that of DNAzol ® extracted DNA which makes it better candidate for analyses like whole genome sequencing.

Benthic–pelagic coupling refers to the ecological relationships between benthic and pelagic environments. Studying such links is particularly useful to understand biological variation in intertidal organisms along marine coasts. Filter-feeding invertebrates are ecologically important on marine rocky shores, so they have often been used to investigate benthic–pelagic coupling. Most studies, however, have been conducted on eastern ocean boundaries. To evaluate benthic–pelagic coupling on a western ocean boundary, we conducted a 5-year study spanning 415 km of the Atlantic coast of Nova Scotia (Canada). We hypothesized that the summer size of intertidal barnacles (Semibalanus balanoides) recruited in the preceding spring would be positively related to the nearshore abundance (biomass) of phytoplankton, as phytoplankton constitutes food for the nauplius larvae and benthic stages of barnacles. Every year between 2014 and 2018, we measured summer barnacle size in clearings created before spring recruitment on the rocky substrate at eight wave-exposed locations along this coast. We then examined the annual relationships between barnacle size and chlorophyll-a concentration (Chl-a), a proxy for phytoplankton biomass. For every year and location, we used satellite data to calculate Chl-a averages for a period ranging from the early spring (when most barnacle larvae were in the water) to the summer (when barnacle size was measured after weeks of growth following spring benthic recruitment). The relationships were always positive, Chl-a explaining nearly half, or more, of the variation in barnacle size in four of the five studied years. These are remarkable results because they were based on a relatively limited number of locations (which often curtails statistical power) and point to the relevance of pelagic food supply to explain variation in intertidal barnacle size along this western ocean boundary coast.

The abundant-centre hypothesis (ACH) predicts that the density of a species should peak at its distribution centre and decrease similarly towards distribution margins. The ACH has been deduced from a theory that postulates that environmental conditions should be most favourable for a species at the centre of its distribution. This idealised density pattern, however, has been supported by limited field studies, as natural patterns are often more complex. It is thus of interest to examine under what conditions compliance with the ACH could be favoured. Such conditions could be smooth environmental gradients with limited habitat patchiness throughout the distribution range of a species. Thus, we tested the ACH by measuring the density of an intertidal barnacle (Semibalanus balanoides) across its full vertical distribution range (from low to high elevations) on a rocky shore with similar substrate properties across elevations. To do a reliable test, we surveyed eight elevation zones applying an equal sampling effort in each zone. Average barnacle density conformed to the ACH, as it peaked at the middle of the vertical distribution range of this species. The same underlying theory predicts a similar unimodal pattern for maximum body size, but this trait was decoupled from density, as maximum barnacle size increased from low to high elevations. Overall, although the ACH is not a universal predictive tool as once envisioned, it may predict some cases well, as shown by this study. Therefore, the ACH should not be discarded completely, and its domain of application should be further evaluated.

Background Abundance of the commercially and ecologically important Eastern oyster, Crassostrea virginica, has declined across the US Eastern and Gulf coasts in recent decades, spurring substantial efforts to restore oyster reefs. These efforts are widely constrained by the availability, cost, and suitability of substrates to support oyster settlement and reef establishment. In particular, oyster shell is often the preferred substrate but is relatively scarce and increasingly expensive. Thus, there is a need for alternative oyster restoration materials that are cost-effective, abundant, and durable. Methods We tested the viability of two low-cost substrates—concrete and recycled blue crab (Callinectes sapidus) traps—in facilitating oyster recovery in a replicated 22-month field experiment at historically productive but now degraded intertidal oyster grounds on northwestern Florida’s Nature Coast. Throughout the trial, we monitored areal oyster cover on each substrate; at the end of the trial, we measured the densities of oysters by size class (spat, juvenile, and market-size) and the biomass and volume of each reef. Results Oysters colonized the concrete structures more quickly than the crab traps, as evidenced by significantly higher oyster cover during the first year of the experiment. By the end of the experiment, the concrete structures hosted higher densities of spat and juveniles, while the density of market-size oysters was relatively low and similar between treatments. The open structure of the crab traps led to the development of larger-volume reefs, while oyster biomass per unit area was similar between treatments. In addition, substrates positioned at lower elevations (relative to mean sea level) supported higher oyster abundance, size, and biomass than those less frequently inundated at higher elevations. Discussion Together, these findings indicate that both concrete and crab traps are viable substrates for oyster reef restoration, especially when placed at lower intertidal elevations conducive to oyster settlement and reef development.

The diatom genus Proschkinia is a common element of biofilms covering diverse substrata in saline inland or shallow coastal environments. It can be distinguished from other naviculoid taxa by its lanceolate valves with a fistula located within the central area and numerous open girdle bands with a U-shaped cross-section and a single row of perforations on the internal side of the fold. Despite this distinct morphology, frustules of Proschkinia are typically weakly silicified and often overlooked when cleaned diatom material is analysed. The current paper describes six new species of Proschkinia: P. browderiana sp. nov., P. lacrimula sp. nov., P. maluszekiana sp. nov., P. sulcata sp. nov., P. torquata sp. nov. and P. vergostriata sp. nov., found in numerous samples of marine organisms, such as sea turtles (including sea turtle museum specimens), sea turtle-associated barnacles and seagrass from across the three oceans. Some of the newly described taxa were found on multiple individuals belonging to different sea turtle species, whereas others were in samples collected from different continents. Molecular phylogenetic analysis indicated that examined Proschkinia strains formed a monophyletic clade, sister to Fistulifera. [ABSTRACT FROM AUTHOR]

Adhesive proteins of barnacle cement have potential as environmentally friendly adhesives owing to their ability to adhere to various substrates in aqueous environments. By understanding the taxonomic breath of barnacles with different lifestyles, we may uncover commonalities in adhesives produced by these specialized organisms. The 19 kDa cement protein (cp19k) of the stalked barnacle Pollicipes pollicipes was expressed in Escherichia coli BL21 to investigate its adhesive properties. Initial expression of hexahistidine-tagged protein (rPpolcp19k-his) yielded low levels of insoluble protein. Co-overproduction of E. coli molecular chaperones GroEL-GroES and trigger factor (TF) increased soluble protein yields, although TF co-purified with the target protein (TF-rPpolcp19k-his). Surface coat analysis revealed high levels of adsorption of the TF-rPpolcp19k-his complex and of purified E. coli TF on both hydrophobic and hydrophilic surfaces, while low levels of adsorption were observed for rPpolcp19k-his. Tag-free rPpolcp19k protein also exhibited low adsorption compared to fibrinogen and Cell-Tak controls on hydrophobic, neutral hydrophilic and charged self-assembled monolayers under surface plasmon resonance assay conditions designed to mimic the barnacle cement gland or seawater. Because rPpolcp19k protein displays low adhesive capability, this protein is suggested to confer the ability to self-assemble into a plaque within the barnacle cement complex. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'. [ABSTRACT FROM AUTHOR]

Despite the fact that magnetic iron oxide nanoparticles (Fe 3 O 4 -MNPs) considered as the most promising nanoparticles (NPs) in biomedicine and environmental biotechnology, their safety and ecotoxicological impacts of biogenic and chemogenic routes of Fe 3 O 4 -MNPs in the marine aquatic system is scarcely studied. In this work, we report the optimized and suitable phyco-synthesis route for nano-Fe 3 O 4 based on the six selected species of the Persian Gulf seaweeds: Ulva prolifera , U. flexuosa , U. linza , U. intestinalis , U. clathrata , and Sargassum boveanum. Moreover, antibacterial activities and acute zooplanktonic responses in Artemia salina and acorn barnacle Amphibalanus amphitrite to chemogenic and biogenic Fe 3 O 4 -MNPs, were evaluated. Although all the seaweeds extract showed reducing potential for Fe 3 O 4 -MNPs green synthesis - mainly on the basis of characterization results- the algal route selectivity has been demonstrated to be important for the biosynthesis of magnetite NPs. Herein, the cubo-spherical and polydisperse U. prolifera -derived Fe 3 O 4 -MNPs with particles sizes of 9.59 nm were the best ones. The comparative zooplanktonic cytotoxicity of chemo- and bio-route of Fe 3 O 4 -MNPs exhibited no acute toxicity in nauplii and adults of A. salina (96-h EC 50 ≥ 1000 mg/L) and the potential of toxicity in A. amphitrite nauplii (48-h EC 50 = 466.5 and 842.3 mg/L for chemo- and bio-route of Fe 3 O 4 -MNPs, respectively). The in vitro antimicrobial activity of both chemo- and bio-route of magnetite NPs to selective human pathogenic bacteria and fungi (i.e. n = 11) showed strong antagonistic activity against Staphylococcus epidermidis , Bacillus subtilis , B. pumulis , and Saccharomyces cerevisiae. In conclusion, these findings demonstrate the optimized phyco-fabrication of Fe 3 O 4 -MNPs as promising nontoxic approach in ecobiotechnology, the new insight about the potential adverse effects of chemosynthesized Fe 3 O 4 -MNPs to crustacean zoo-organisms after their possible entrance into the marine environments, and bio/chemo-route Fe 3 O 4 -MNPs as pivotal agent for nanoantimicrobials. • Optimization for cost-effective phyco-fabrication of nano-Fe 3 O 4 by using six marine macroalgae. • Observation algal route selectivity in biosynthesis of magnetite nanoparticles. • Ulva prolifera -derived Fe 3 O 4 -MNPs and Chemogenic Fe 3 O 4 -MNPs showed no acute toxicity in Artemia salina and toxic potential in Amphibalanus amphitrite. • Bio/chemo-route Fe 3 O 4 -MNPs as pivotal agent for nanoantimicrobials. [ABSTRACT FROM AUTHOR]

Summary: Several aquatic living resources are overexploited. An example of this is a barnacle fishery, which is a commercial species that commands high prices in the market. We feel that not enough is known about the management of this species. In particular, not enough is known about its growth pattern. Thus, we model the length–weight relationship of this resource for each harvest site. We use regression models with factor‐by‐curve interactions. Specifically, a global test to compare regression curves and their derivatives between levels and a local test to draw inferences about critical points are provided. [ABSTRACT FROM AUTHOR]

• Barnacle density increases with increasing distance from the sediment (≥30 cm). • Shipworm damage is concentrated from 0 to 20 cm from the sediment. • Tree species with lower wood densities are more vulnerable to shipworm damage. • Drought can have strong interannual effects mediating shipworm damage in the SE US. • Copper-based paint and duct tape can effectively prevent shipworm burrowing. Annually, shipworms and other biofouling species cause millions of dollars in damage to wooden marine infrastructure across the world. Given their abundant larval supply and high dispersal potential, bioeroders and biofoulers are ubiquitous threats that shorten the lifespan of wooden docks, piers, boats and shoreline stabilization structures in coastal environments. Despite these impacts, there are no treatments that completely protect wood against shipworms and biofouling. To explore potential approaches for extending the lifespan of wooden shoreline stabilization structures, we conducted two field experiments to evaluate the resistance to shipworms and biofouling of small and large diameter branches of four trees – laurel oak (Quercus hemisphaerica) , sweetgum (Liquidambar styraciflua), crepe myrtle (Lagerstroemia spp.), and black mangrove (Avicennia germinans) – positioned at varying distances from the sediment surface in southeastern US estuaries. We discovered that the wood volume lost to shipworm burrows was concentrated near the sediment surface, more prevalent in tree species with lower wood densities, and varied markedly between years. Barnacle fouling was far higher on branches > 30 cm from the surface and on laurel oak and sweetgum branches. In a third field experiment, we tested two chemical and two non-chemical wood treatments and found chemical treatments to be more effective at deterring barnacle fouling and shipworm burrowing of wooden posts, especially beneath the sediment surface. By identifying desirable characteristics of the wood employed and elevations at which the impacts of shipworms and biofouling are especially prevalent, this experimental study informs the design of more durable wooden stabilization structures in coastal environments. [ABSTRACT FROM AUTHOR]

Biofouling by marine organisms can result in a variety of negative environmental and economic consequences, with decontamination procedures remaining problematic, costly and labour-intensive. Here, we examined the efficacy of direct steam exposure to induce mortality of selected biofouling species: Mytilus edulis ; Magallana gigas ; Semibalanus balanoides ; Fucus vesiculosus ; and an Ulva sp. Total mortality occurred at 60-sec of steam exposure for M. edulis and juvenile M. gigas , at 30-sec for S. balanoides , while 300-sec was required for adult M. gigas. Application of steam reduced the biomass of F. vesiculosus and significantly reduced Ulva sp. biomass, with complete degradation being observed for Ulva sp. following 120-sec of exposure. Accordingly, it appears that steam exposure can cause mortality of biofouling organisms through thermal shock. Although preliminary, our novel and promising results suggest that steam applications could potentially be used to decontaminate niche areas and equipment. • Steam exposure can cause mortality and biodegradation through thermal shock. • Direct exposure to steam caused total mortality of biofouling bivalve species. • Complete mortality can be achieved with short exposure times of ≤60 sec. • Larger-bodied bivalves, e.g. adult Magallana gigas , required longer exposure times. • Steam significantly reduced the biomass of Ulva sp. [ABSTRACT FROM AUTHOR]