Balanus Improvisus Research Articles

Porous silicone substrates inhibit permanent barnacle attachment under natural conditions.

Barnacles are able to effectively adhere to most surfaces underwater. Dewetting of the corresponding surface prior to the release of their permanent adhesive plays an important role in the attachment process. Possibly, a surface that is able to interfere with this process may have exceptional fouling repellence and fouling release abilities. Therefore, open-pored foams made from polydimethylsiloxane (PDMS) were tested together with flat PDMS samples as controls in a 13-week-long field experiment in the Baltic Sea. On a weekly basis, both settlement and fouling density development of the bay barnacle Balanus (=Amphibalanus) improvisus were monitored. The overall settlement was close to zero on PDMS foams and the few attached barnacles were not able to stay on the PDMS foams longer than 1 week after initial settlement. Changes in the stiffness of the PDMS foams did not affect these results. Open-pored PDMS foam systems may be a promising tool in the development of new, innovative antifouling strategies.

Risk screening of the potential invasiveness of non-native marine crustacean decapods and barnacles in the Mediterranean Sea

Non-native marine crustaceans can exert detrimental impacts on native marine communities by altering habitat and ecosystem function. The Mediterranean Sea is particularly vulnerable to introductions of non-native crustaceans, as evidenced by their remarkably high establishment success. In this study, 20 species of non-native marine crustacean decapods and barnacles of which eleven extant and nine ‘horizon’ were screened for their potential invasiveness in the Mediterranean Sea. Using the Aquatic Species Invasiveness Screening Kit and including an additional nine native species to increase accuracy, calibrated risk thresholds of 3.5 for the BRA (Basic Risk Assessment) and 8.5 for the BRA + CCA (BRA + Climate Change Assessment) were obtained that distinguished reliably between invasive and non-invasive species. All 20 non-native species were classified as carrying a high risk of invasiveness for the Mediterranean Sea, both for the BRA and the BRA + CCA. Chinese mitten crab Eriocheir sinensis was by far the highest risk species, followed by Harris mud crab Rhithropanopeus harrisii, Asian shore crab Hemigrapsus sanguineus, bay barnacle, Amphibalanus improvisus, and lesser swimming crab Charybdis (Goniohellenus) longicollis. The findings of this study will provide management and control directions for non-native marine crustaceans in the Mediterranean Sea, with special emphasis on regulations regarding ballast waters, which represent one of the main introduction pathways for these aquatic organisms.

Control of fouling in the aquaculture of Fucus vesiculosus and Fucus serratus by regular desiccation

Fouling is a major problem in seaweed aquaculture and one of the main obstacles during the domestication process for new culture species. During first attempts to cultivate Fucus vesiculosus and Fucus serratus in the Kiel fjord (Western Baltic Sea), fouling by the epizoans Electra pilosa, Mytilus sp., and Amphibalanus improvisus rendered the production of marketable biomass impossible. This study tested (1) if regular desiccation by air exposure is effective in decreasing the abundance and size of foulers and (2) if and how regular desiccation affects the growth performance of the cultivated Fucus thalli. For this purpose, thalli of F. vesiculosus and F. serratus were cultivated freely floating in baskets directly deployed in the fjord and desiccated to defined percentages of the wet weight (ww) by air exposure. The treatments comprised controls and desiccations of different intensities (from 90 to 40% of ww) and at different frequencies (1× week−1, 3× week−1). Growth rates of both Fucus species were not or only slightly reduced by the desiccation treatments. The final harvested biomass of F. vesiculosus under frequent mild desiccations (3× week−1 to 80% of ww) was even higher than the biomass of undesiccated controls. The size of the epizoans E. pilosa and A. improvisus was significantly reduced by the desiccation treatments and the abundance of all epizoan species was drastically reduced by the desiccation regimes. Frequent mild desiccations (F. vesiculosus: 3× week−1 to 80% of ww, F. serratus: 3× week−1 to 90% of ww) proved to be most effective and decreased the epizoan ww share of the total harvest from 13.0 ± 4.8% in the control to 1.8 ± 0.2% for F. vesiculosus and from 19.1 ± 2.7 to 1.0 ± 0.1% for F. serratus. Thus, desiccation seems to be an effective measure for the production of clean Fucus biomass in culture which is necessary for further valorization. A technical solution for the implementation of this procedure in large-scale cultures remains to be developed.

The Influence of Material and Roughness on the Settlement and the Adhesive Strength of the Barnacle Balanus Improvisus in the Baltic Sea

Under natural conditions, barnacles, one of the most prominent marine hardfouling organisms, encounter a vast variety of heterogeneous surfaces including artificial ones, such as ship hulls on which they adhere efficiently. Despite intensive research in the last decades, it is still not clear, how material related factors influence the fouling development under natural conditions, and whether roughness at a microscale affects the release dynamics of barnacles. In order to shed light on the relationship between these substrate factors and their effect on biofouling, both settlement and fouling development of Balanus (=Amphibalanus) improvisus was evaluated on epoxy resin and polyvinylsiloxane (PVS) substrates differing in their roughness (flat, asperity sizes: 0.3µm, 1µm, 3µm, 9µm, 12µm) in a static field trial in the Baltic Sea for 17 weeks performed in 2014. All barnacles on these tested surfaces were individually tracked on a weekly basis, in order to calculate the release to settlement ratios (r/s), to evaluate the fouling- release performance and to monitor the actual attachment duration. It was demonstrated that both stiffness and surface free energy had no strong effect on initial settlement. The total fouling accumulation was nearly identical for epoxy resin and PVS, if fallen-off barnacles were included in the analysis. Roughness influenced initial settlement and fouling development. On PVS the r/s nged between 0.5-0.7 and the attachment duration was around four weeks. However, samples with a roughness of 9µm displayed a lower r/s ratio (0.35) and barnacles showed longer attachment durations (8 weeks). In a second field trial performed in 2017, attachment forces of barnacles were measured after the samples had been immersed for 10 weeks in the Baltic Sea. The shear stresses obtained were similar for substrates with different roughness with around 0.12 MPa and were independent of the barnacle’s size. These findings show that roughness even at the micro scale can impact the fouling release ability of a surface.

A systematic investigation into the effect of fibrillar microstructures on the settlement and attachment strength of the bay barnacle Balanus improvisus under natural conditions

Barnacles are one of the most prominent hardfouling organisms in the marine environment. They are able to adhere efficiently to nearly every surface underwater including artificial ones like ship hulls and maritime installations. This overgrowing can lead to huge economical costs. Previous studies have shown that specific microstructure types including micropillars can reduce the initial settlement of barnacles. However, it is not clear how adult barnacles are influenced by microstructured surfaces and whether microstructures can even decrease the resulting adhesion strength of them under natural conditions. Therefore, the aim of this study was to systematically investigate the influence of height, diameter, aspect ratio and flexibility of fibrillar microstructures made from polydimethylsiloxane (PDMS) on initial settlement of barnacles as well as the permanent attachment of adult ones. Micropillars with three different heights (50 µm, 100 µm, 200 µm) and two different diameters (25 µm, 50 µm) were exposed to the Baltic Sea for 12 weeks. On a weekly basis, all barnacles (Balanus [= Amphibalanus] improvisus) were tracked individually to calculate the release-to-settlement ratio and to capture the average attachment duration prior to detachment. The results have shown that with increasing height, both initial settlement and fouling density development were reduced. An increase of diameter showed a similar relationship but at a much smaller scale. All tested microstructures decreased the detachment rates of barnacles from the surface compared to a flat PDMS control. However, they appear to complicate the development of a strong adhesive joint in the young adult phase. Some grade of flexibility in the microstructures appeared to increase the fouling retention. The results shed light in the interaction between adult barnacle adhesion and microstructures and may help in the development of new antifouling technologies.

Disappearing Blue Mussels – Can Mesopredators Be Blamed?

Abstract Despite many theories, the recent evident decreases in blue mussel (Mytilus edulis) abundance in southern Norway and western Sweden (eastern North Sea) have not yet been explained. To test the possible role of increased predation, an ongoing mesocosm experiment exploring general effects of two mesopredators on the structure of littoral macroalgal and macrofaunal communities was used. These mesopredators were the green crab (Carcinus maenas) and the goldsinny wrasse (Ctenolabrus rupestris) which were distributed in a crossed manner to 12 large mesocosms containing diverse rocky shore communities. For the purposes of this study, boulders covered with recently recruited blue mussels and barnacles (Balanus improvisus) from a natural shore were brought in to the mesocosms during two seasons (August and October), and the coverage of the animals (just blue mussels in summer, both mussels and barnacles in autumn) was registered repeatedly over 24 hours. The mussels were rapidly consumed by crabs and wrasses, whereas high survival was recorded on boulders in the controls without predators. The barnacles were only eaten by the crabs and not before most of the mussels had been consumed. As both the green crab and the goldsinny wrasse have been reported to increase in abundance, probably related to overfishing of top predators, the resulting higher predation pressure on especially small blue mussels (recruits) may contribute to the mussel decline along these temperate rocky shores.

From swimming towards sessility in two metamorphoses – the drastic changes in structure and function of the nervous system of the bay barnacle Amphibalanus improvisus (Crustacea, Thecostraca, Cirripedia) during development

Knowledge about the development of the nervous system in cirripeds is limited, particularly with regard to the changes that take place during the two metamorphoses their larvae undergo. This study delivers the first detailed description of the development of the nervous system in a cirriped species, Amphibalanus improvisus by using immunohistochemical labeling against acetylated alpha-tubulin, and confocal laser scanning microscopy. The development of the nervous system in the naupliar stages corresponds largely to that in other crustaceans. As development progresses, the protocerebral sensory organs differentiate and the intersegmental nerves forming the complex peripheral nervous system appear, innervating the sensory structures of the cephalic shield. During metamorphosis into a cypris the lateral sides of the cephalic shield fold down into a bilateral carapace, which leads to a reorganization of the peripheral nervous system. The syncerebrum of the cypris exhibits the highest degree of complexity of all developmental stages, innervating the frontal filaments, nauplius eye, compound eyes and the antennules. During settlement, when the second metamorphosis occur, the closely associated frontal filaments and compound eyes are shed together with the cuticle of the carapace and the antennules. In adults, the syncerebral structures are reduced while the ventral nerve cord and the peripheral nervous system increase in complexity. The peripheral nervous system plays an important role in processing sensory input and also in settlement. In summary, through the larval development we observed a structural and thus also functional increase of complexity in favor of the peripheral nervous system and the ventral nerve cord.

Fouling assemblage of marine debris collected in a temperate South-western Atlantic coastal lagoon: A first report

In the South-western Atlantic, studies dealing with the impacts of debris on marine species are focused mainly on vertebrates, being scarce the studies conducted to determine the association of fouling species to marine debris. A total of 33 marine debris items with fouling specimens were collected in Mar Chiquita coastal lagoon, Argentina. Species richness varied between one and five species per debris item, and dominant species included the barnacle Amphibalanus improvisus (93.94%), followed by the bryozoan Membranipora sp. (72.73%), undetermined polychaetes (36.36%), the mollusc Ostrea sp. (15.15%), the hydrozoan Amphisbetia operculata and the mollusc Brachidontes rodriguezii (3.45%, in both cases). We concluded that marine debris constitutes a suitable settlement site for sessile species inhabiting the lagoon, where hard-substratum are absent; while buoyancy analysis suggested that the initial colonization occurred both on marine debris suspended in the water column or at the sea surface, and in those laying on the seafloor.

Macrobenthic assemblage structure and distribution at the Boojagh Marine National Park, Southern Caspian Sea, Iran.

Although macrobenthic assemblages are considered as major players in many ecosystems around the world, the ecology of Caspian Sea macrobenthos is currently understudied. This study describes the species composition and quantitative distribution of macrobenthos in the southern Caspian Sea and relates the distribution to seasonal changes at three depths (1, 5 and 10 meters) on the Boojagh Marine National Park (BMNP) coast in the southern Caspian Sea between the summers of 2015 and 2016. To investigate the distribution of macrobenthos in BMNP, the data of 450 samples were analyzed. In this study sixteen species were identified: Cerastoderma glaucum, Mytilaster lineatus, Pyrgula grimmi, Anisus kolesnikovi, Stenogammarus carausui, Paraniphargoides motasi, Onisimus caspius, Pterocuma pectinatum, Pterocuma sowinskyi, Pseudocuma (Stenocuma) gracile, Nais sp., Hypania invalida, Manayunkia caspica, Streblospio gynobranchiata, Hediste diversicolor, Amphibalanus improvisus. Among them, the non-indigenous C. glaucum was the dominant species, accounting for 27% of the total abundance and in descending order P. grimmi with 14.4%, A. improvisus with 8.7%, M. lineatus with 7.9%, Nais sp. with 7.5%, N. carausui with 5.2%, P. motasi with 5%, S. gynobranchiata with 4.5%, H. invalida with 5%, M. Caspica with 3.1%, P. sowinskyi with 2.5%, O. caspius with 2.4%, A. kolesnikovi and H. diversicolor with 1.8%, S. gracilis with 1.6% and P. pectinatum with 1.5% were in the next rank. Significant differences in abundance across the sixteen species were observed among depths and seasons. This study highlights the potential consequences of established non-indigenous species in the southern Caspian Sea.

Preparation and evaluation of fouling-release properties of amphiphilic perfluoropolyether-zwitterion cross-linked polymer films

The biofouling of marine structures presents a problem for maritime industries, including increasing fuel and operational costs. There has been much work developing and evaluating chemically ‘ambiguous’ amphiphilic coatings based upon hydrophobic fluoropolymer and hydrophilic poly(ethylene glycol) (PEG). Many of these coatings have shown good fouling-release performance against diatoms, which present a fouling challenge to commercially-available state-of-the-art silicone-based fouling-release coatings. However, PEG is prone to oxidation, which limits its practical use in the marine environment, and thus an alternative hydrophilic material would be desirable in the future development of amphiphilic coatings. In this regard, zwitterionic materials are emerging as a promising class of hydrophilic antifouling material, which we hypothesized would be a suitable alternative to PEG within amphiphilic coatings. To test this hypothesis, cross-linked amphiphilic films consisting of commercially available perfluoropolyethers and the zwitterionic monomer sulfobetaine methacrylate were developed and studied. The difficulty in formulating these chemically incompatible species was overcome by careful choice of solvents and a series of prototype cross-linked films were prepared in which increasing quantities of zwitterion were systematically incorporated. The fouling-release performance of these films was tested against the diatom Navicula incerta, a common microfouling organism responsible for the formation of so-called ‘slime’ layers, and antifouling performance with cypris larvae of two barnacle species, Balanus amphitrite, and Balanus improvisus. To expand the scope of the study, the clinically-relevant biofilm-forming pathogen Staphylococcus aureus, which is a major culprit in the infection and failure of millions of indwelling medical devices, was also evaluated. Results indicate that the incorporation of zwitterion into perfluoropolyethers leads to significant improvements in fouling-release performance and these amphiphilic coatings display potential in fouling-release applications.

Микроскопические грибы бассейна Чёрного моря: направления и перспективы исследований

Проанализирован 71 литературный источник, посвящённый изучению микроскопических грибов (микромицетов) Чёрного моря, за период с 1867 по 2018 г. В 1860-е и 1930-е гг. зафиксированы эпидемии морской травы Zostera marina, вызванные грибоподобными организмами рода Labyrinthula. В конце XIX — начале XX века также выявлено несколько случаев локального микоза морской травы. В 1960–2000-е гг. зарегистрированы эпизоотии беспозвоночных животных, вызванные грибами: Hyphochytrium peniliae поражал ветвистоусого рачка Penilia avirostris и вызывал его массовую гибель; гриб Leptolegnia pontica паразитировал на яйцах усоногого рачка Balanus improvisus и существенно сократил плодовитость популяции; вселение Ostracoblabe implexa привело к уничтожению популяций устрицы Ostrea edulis. В настоящее время отмечены единичные случаи поражения грибом O. edulis культивируемой устрицы Crassostrea gigas, спат которой привозят из других стран. На створках C. gigas и Mytilus galloprovincialis выделены грибы-эпибионты. В зрелых ооцитах M. galloprovincialis найдена микроспоридия Steinhausia mytilovum. На рыбах и в их внутренних органах обнаружены гифальные грибы и внутриклеточные паразиты — микроспоридии. На покровах бутылконосых дельфинов выявлены грибы. Проведены работы по изучению микобиоты пелагиали, бентали, целлюлозосодержащих субстратов, пены, перифитона, микро- и макроводорослей, морских трав. В настоящее время в бассейне Чёрного моря известно 435 видов грибов из 212 родов, 84 семейств, 50 порядков, 19 классов, 3 царств. В морской среде зафиксировано 372 вида, в пресной — 196, в гиперсолёных водоёмах — 31. В водной толще обнаружено 230 видов микромицетов (в сероводородной зоне — 21); в донных отложениях — 202 (в сероводородной зоне — 31); на древесине — 70; в перифитоне на стёклах и искусственной каменистой супралиторали (причалы, траверсы) — 30; в морской пене — 46; на/в моллюсках — 50; на коже дельфинов — 18; на макроводорослях — 116; на микроводорослях — 2; на морских травах — 38; на/в рыбах — 69; на/в ракообразных — 14. Количество видов, обнаруженных в прибрежных водах разных районов, составило: Грузии — 8 видов; г. Геленджика (Россия) — 56; полуострова Крым — 276; северо-западной части Чёрного моря — 177; Румынии — 112; Болгарии — 44; Турции — 9; р. Дунай — 238; о-ва Змеиный — 30. В настоящем обзоре рассмотрены работы по оценке способности грибов утилизировать целлюлозу, нефть, нефтепродукты, фенол, серу и вызывать коррозию металлов; проанализированы первые результаты исследований антимикробной активности факультативно и облигатно морских грибов Чёрного моря, а также способности микромицетов к люминесценции. Определены перспективные направления морских микологических исследований.

Synthesis of Novel Sulfobetaine Polymers with Differing Dipole Orientations in Their Side Chains, and Their Effects on the Antifouling Properties.

The impact of the orientation of zwitterionic groups, with respect to the polymer backbone, on the antifouling performance of thin hydrogel films made of polyzwitterions is explored. In an extension of the recent discussion about differences in the behavior of polymeric phosphatidylcholines and choline phosphates, a quasi-isomeric set of three poly(sulfobetaine methacrylate)s is designed for this purpose. The design is based on the established monomer 3-[N-2-(methacryloyloxy)ethyl-N,N-dimethyl]ammonio-propane-1-sulfonate and two novel sulfobetaine methacrylates, in which the positions of the cationic and the ionic groups relative to the polymerizable group, and thus also to the polymer backbone, are altered. The effect of the varied segmental dipole orientation on their water solubility, wetting behavior by water, and fouling resistance is compared. As model systems, the adsorption of the model proteins bovine serum albumin (BSA), fibrinogen, and lysozyme onto films of the various polyzwitterion surfaces is studied, as well as the settlement of a diatom (Navicula perminuta) and barnacle cyprids (Balanus improvisus) as representatives of typical marine fouling communities. The results demonstrate the important role of the zwitterionic group's orientation on the polymer behavior and fouling resistance.

Antifouling Properties of Dendritic Polyglycerols against Marine Macrofouling Organisms.

Dendritic polyglycerols (PGs) were synthesized and postmodified by grafting of poly(ethylene glycol) (PEG) and polypropylene glycol (PPG) diglycidyl ether groups, and their antifouling and fouling-release properties were tested. Coating characterization by spectroscopic ellipsometry, contact angle goniometry, attenuated total internal reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and atomic force microscopy showed brushlike morphologies with a high degree of microscale roughness and the ability to absorb large amounts of water within seconds. PGs with three different thicknesses were tested in laboratory assays against settlement of larvae of the barnacle Balanus improvisus and against the settlement and removal of zoospores of the alga Ulva linza. Very low coating thicknesses, e.g., 11 nm, reduced the settlement of barnacles, under static conditions, to 2% compared with 55% for an octadecyltrichlorosilane reference surface. In contrast, zoospores of U. linza settled readily but the vast majority were removed by exposure to a shear force of 52 Pa. Both PEG and PPG modification increased the antifouling properties of the PG films, providing a direct comparison of the ultralow fouling properties of all three polymers. Both, the modified and the nonmodified PGs are promising components for incorporation into amphiphilic fouling-resistant coatings.

STUDY OF ECOSYSTEM OF THE SUKHUM BAY WITH EMPHASIS ANTHROPOGENIC IMPACT, ABKHAZIAN BLACK SEA COAST

For the first time in thirty years, baseline comprehensive studies plankton and zoobenthos of the Sukhum Bay were conducted and an assessment of its current environmental status was given. The summer phytoplankton abundance of the port of Sukhum was represented mainly by coccolithophorids Emiliania huxleyi and diatoms algae, among the latter, the common species in polluted or eutrophic brackish waters were recorded. The presence of euglenic algae and cyanobacteria indicates a higher nutrient status, pollution and desalination of the sea area. The alien species Peridinium quinquecorne Abé (Dinophyceae) was recorded in the Abkhazian coastal waters for the first time. Totally, 7 species of tintinnids belonging to 3 genera Favella, Tintinnopsis, Eutintinnus were established from the Sukhum Bay. Among them, the non-indigenous species Eutintinnus tubulosus and E. apertus were noticed. Tintinnid ciliates accounted for ca. 5% of total ciliates abundance. The values of the abundance of aloricated ciliates were comparable to the values obtained from offshore of bays and ports of the northeastern Black Sea. As the pressure of predators is reduced the well-pronounced peaks of holo- and meroplankton biomass were recorded in the last summer – early autumn. A significant part of total holoplankton biomass – 66.5 % (up to 1.1 g/m3) was composed of cladocerans Penilia avirostris. The meroplankton was dominated by larvae of bivalve mollusks Mytilaster lineatus, polychaetes Polydora cornuta and cirripede barnacle Amphibalanus improvisus. The number of meroplankton in the open Sukhum port was 10–15 times lower above than a level of values obtained for ports and bays of the northeastern Black Sea. Among ichthyoplankton, the dominant species were Mullus barbatus ponticus, Diplodus annularis, Trachurus mediterraneus, Engraulis encrasicholus and Sciena umbra. Mean abundance of ichthyoplankton in vertical catches was 5–10 times lower than in offshore of Anapa and Gelendzhik of the northeastern Black Sea. And the proportion of dead eggs was 2 – 3 times higher than areas of these resort cities. The composition of macrozoobenthos was drastically depleted and resembled that of the polluted port complexes of the northeastern Black Sea. Heteromastus association dominated in mud bottom sediments. Among spionid polychaetes, the worst invaders Streblospio gynobranchiata and Polydora cornuta have been recorded in soft bottom communities. Depletion of benthic communities, loss from the structure of the trophic web of the macrophyte community and appearance of cyanobacteria and a new alien species in the planktonic and benthic communities leads inevitably to imbalance of the structure of the Sukhum port ecosystem.

Nonfreezable Water and Polymer Swelling Control the Marine Antifouling Performance of Polymers with Limited Hydrophilic Content.

Zwitterionic chemical groups have well-documented resistance to marine fouling species when presented as homogeneous polymer brushes. These model formulations are not, however, suitable for practical fouling-control applications. It is presently unknown if a uniform film of zwitterions is required to elicit nonfouling character via the binding of interfacial water or if the incorporation of zwitterionic functionality into a more practical bulk polymer system will suffice. Here, copolymers of n-butyl methacrylate were synthesized with low incorporation levels (up to 20 mol %) of hydrophilic functionality, including zwitterionic moieties. Their antifouling (AF) properties were evaluated using barnacle cyprids (Balanus improvisus), diatom cells (Navicula incerta), and a multispecies biofilm. The laboratory assays revealed higher resistance of ionic copolymers toward cyprid settlement, which was attributed to their swelling and the presence of nonfreezable water molecules bound tightly to the polymer chains. Additionally, cells of N. incerta and the multispecies biofilm were removed more effectively on polymers containing sulfobetaine methacrylate and sulfopropyl methacrylate moieties. The results indicate that the presence of tightly bound interfacial water is not limited to model systems of pure hydrophilic homopolymers, but that this mechanism can also reduce the settlement and adhesion of fouling species via bulk copolymer systems with limited hydrophilic content. The swelling of polymers with hydrophilic content may also contribute to their AF efficacy, and such materials may therefore represent a route to translation of the well-documented nonfouling character of zwitterions into practical, industrially relevant coating formulations.

Sensory receptor repertoire in cyprid antennules of the barnacle Balanus improvisus.

Barnacle settlement involves sensing of a variety of exogenous cues. A pair of antennules is the main sensory organ that the cyprid larva uses to explore the surface. Antennules are equipped with a number of setae that have both chemo- and mechanosensing function. The current study explores the repertoire of sensory receptors in Balanus improvisus cyprid antennules with the goal to better understand sensory systems involved in the settling behavior of this species. We carried out transcriptome sequencing of dissected B. improvisus cyprid antennules. The generated transcriptome assembly was used to search for sensory receptors using HMM models. Among potential chemosensory genes, we identified the ionotropic receptors IR25a, IR8a and IR93a, and several divergent IR candidates to be expressed in the cyprid antennules. We found one gustatory-like receptor but no odorant receptors, chemosensory or odorant-binding proteins. Apart from chemosensory receptors, we also identified 13 potential mechanosensory genes represented by several transient receptor potential channels (TRP) subfamilies. Furthermore, we analyzed changes in expression profiles of IRs and TRPs during the B. improvisus settling process. Several of the sensory genes were differentially expressed during the course of larval settlement. This study gives expanded knowledge about the sensory systems present in barnacles, a taxonomic group for which only limited information about receptors is currently available. It furthermore serves as a starting point for more in depth studies of how sensory signaling affects settling behavior in barnacles with implications for preventing biofouling.

The complex barnacle perfume: identification of waterborne pheromone homologues in Balanus improvisus and their differential expression during settlement

A key question in barnacle biology is the nature of cues that induce gregarious settlement. One of the characterised cues is the waterborne settlement pheromone (WSP). This study aimed to identify WSP homologues in Balanus improvisus and to investigate their expression during settlement. Six WSP homologues were identified, all containing an N-terminal signal peptide, a conserved core region, and a variable C-terminus comprising several -GR- and -HDDH- motifs. The B. improvisus WSP homologues were expressed in all settlement stages but showed different expression patterns. The homologue most similar to the B. amphitrite WSP was the most abundant and was constantly expressed during settlement. In contrast, several of the other WSP homologues showed the greatest expression in the juvenile stage. The presence of several WSP homologues suggests the existence of a pheromone mix, where con-specificity might be determined by a combination of sequence characteristics and the concentration of the individual components.

Correlative assays of barnacle cyprid behaviour for the laboratory evaluation of antifouling coatings: a study of surface energy components

Laboratory evaluation of antifouling coatings is underpinned by settlement studies with specific fouling organisms. Established methods provide insight into the likelihood of failure of a particular coating system, but can neglect the process of surface selection that often precedes attachment. The present approach for quantifying the exploratory behaviour of barnacle cypris larvae suggested that inspection behaviour can be a rapid and predictive proxy for settlement. Two series of xerogels with comparable total surface energy, but different dispersive and polar components, were evaluated. Settlement assays with three-day-old cyprids of Balanus improvisus demonstrated that while attachment was not linked directly to dispersive free energy, the composition of the xerogel was nevertheless significant. Behavioural analysis provided insight into the mechanism of surface rejection. In the case of a 50:50 PH/TEOS (phenyltriethoxysilane-based) xerogel vs a 50:50 TFP/TEOS (3,3,3-trifluoropropyltrimethoxysilane-based) xerogel, wide-searching behaviour was absent on the former.

Консорты брюхоногого моллюска Rapana venosa (Valenciennes, 1846) в северной части Чёрного моря. Часть IV: Arthropoda

Статья посвящена изучению таксоцена Arthropoda и является продолжением цикла по описанию состава консорции брюхоногого моллюска — вселенца Rapana venosa (Valenciennes, 1846). Консорция R. venosa остаётся неучтённой компонентой в структуре биоценозов шельфа Чёрного моря. Использованный материал и методы исследования детально рассмотрены в предыдущих работах цикла. Цель данной статьи ― описание комплекса эпибионтных организмов и составление аннотированного списка таксонов Arthropoda консорции R. venosa. Найденные в консорции рапаны 27 видов типа Arthropoda относятся к двум подтипам ― Chelicerata (класс Arachnida) и Crustacea (классы Malacostraca и Hexanauplia). Единственный представитель класса паукообразных (Arachnida; Acari) ― клещ Rhombognathus notops (Gosse, 1855) ― обнаружен лишь дважды (по одному экземпляру в сборах 2016 и 2017 гг.). Rapana venosa служит субстратом для развития разнообразных водорослей ― благоприятного местообитания для эпифитона, что обуславливает высокую численность и разнообразие ракообразных в этом биотопе. Наибольшее таксономическое разнообразие отмечено для класса Malacostraca ― 25 видов, относящихся к 22 родам 19 семейств. Членистоногие представлены двумя основными экологическими группами (седентарные и подвижные эпибионты). Наибольшее видовое разнообразие Arthropoda присуще свободноживущим подвижным формам (23 вида). Седентарные формы, явно уступая по количеству видов (4), доминируют по численности (86 %) и биомассе (94 %). Единственный представитель Cirripedia ― Amphibalanus improvisus (Darwin, 1854) ― является самым распространённым (53 % общей численности) и массовым ракообразным и вносит наиболее существенный вклад в биомассу (91,8 %) в консорции Arthropoda. Более 50 % видов Arthropoda в консорции рапаны — полифаги; фитофаги составляют 21 %, а детритофаги ― 29 % общего числа видов членистоногих. Единственный взрослый экземпляр эктопаразита рыб ― изоподы Elaphognathia bacescoi (Kussakin, 1969) ― найден в консорции песчаной рапаны на глубине 8 м в бухте Голубая (г. Севастополь). Все обнаруженные 27 видов Arthropoda присутствуют в консорции песчаной экоморфы R. venosa, и только 3 вида отмечены на скальной рапане. Различия в составе консорции двух экоморф R. venosa можно объяснить преимущественно большим развитием эпифитов и пониженной динамикой водных масс в зонах обитания песчаной рапаны в районе Севастополя. Благодаря своему таксономическому разнообразию, численности и биомассе Arthropoda являются важным элементом донного биоценоза, ассоциированного пространственно и трофически с особями самой крупной гастроподы Чёрного моря ― R. venosa.

Effect of antimicrobials, salinity, and contamination by air on bacterial and fungal growth in cyprid cultures of Amphibalanus improvisus

Effect of antimicrobials, salinity, and contamination by air on bacterial and fungal growth in cyprid cultures of <i>Amphibalanus improvisus</i>