Balanus Improvisus Research Articles

The Barnacle Balanus improvisus as a Marine Model - Culturing and Gene Expression.

Barnacles are marine crustaceans with a sessile adult and free-swimming, planktonic larvae. The barnacle Balanus (Amphibalanus) improvisus is particularly relevant as a model for the studies of osmoregulatory mechanisms because of its extreme tolerance to low salinity. It is also widely used as a model of settling biology, in particular in relation to antifouling research. However, natural seasonal spawning yields an unpredictable supply of cyprid larvae for studies. A protocol for the all-year-round culturing of B. improvisus has been developed and a detailed description of all steps in the production line is outlined (i.e., the establishment of adult cultures on panels, the collection and rearing of barnacle larvae, and the administration of feed for adults and larvae). The description also provides guidance on troubleshooting and discusses critical parameters (e.g., the removal of contamination, the production of high-quality feed, the manpower needed, and the importance of high-quality seawater). Each batch from the culturing system maximally yields roughly 12,000 nauplii and can deliver four batches in a week, so up to almost 50,000 larvae per week can be produced. The method used to culture B. improvisus is, probably, to a large extent also applicable to other marine invertebrates with free-swimminglarvae. Protocols are presented for the dissection of various tissues from adults as well as the production of high-quality RNA for studies on gene expression. It is also described how cultured adults and reared cyprids can be utilized in a wide array of experimental designs for examining gene expression in relation to external factors. The use of cultured barnacles in gene expression is illustrated with studies of possible osmoregulatory roles of Na+/K+ ATPase and aquaporins.

The Barnacle <em>Balanus improvisus</em> as a Marine Model - Culturing and Gene Expression

Barnacles are marine crustaceans with a sessile adult and free-swimming, planktonic larvae. The barnacle Balanus (Amphibalanus) improvisus is particularly relevant as a model for the studies of osmoregulatory mechanisms because of its extreme tolerance to low salinity. It is also widely used as a model of settling biology, in particular in relation to antifouling research. However, natural seasonal spawning yields an unpredictable supply of cyprid larvae for studies. A protocol for the all-year-round culturing of B. improvisus has been developed and a detailed description of all steps in the production line is outlined (i.e., the establishment of adult cultures on panels, the collection and rearing of barnacle larvae, and the administration of feed for adults and larvae). The description also provides guidance on troubleshooting and discusses critical parameters (e.g., the removal of contamination, the production of high-quality feed, the manpower needed, and the importance of high-quality seawater). Each batch from the culturing system maximally yields roughly 12,000 nauplii and can deliver four batches in a week, so up to almost 50,000 larvae per week can be produced. The method used to culture B. improvisus is, probably, to a large extent also applicable to other marine invertebrates with free-swimminglarvae. Protocols are presented for the dissection of various tissues from adults as well as the production of high-quality RNA for studies on gene expression. It is also described how cultured adults and reared cyprids can be utilized in a wide array of experimental designs for examining gene expression in relation to external factors. The use of cultured barnacles in gene expression is illustrated with studies of possible osmoregulatory roles of Na+/K+ ATPase and aquaporins.

Inhibition of biofilm bacteria and adherent fungi from marine plankton cultures using an antimicrobial combination

The presence of organic matter in plankton cultures will lead to 10- to 1000-fold increases in bacterial density in less than 24 h. The presence of bacteria and fungi can damage cultivated phytoplankton and zooplankton. These microorganisms can also inhibit experiments investigating the role of these microorganisms in the community and in biological and ecological laboratory studies. The aim of this study was thus to evaluate the effect of penicillin + streptomycin + neomycin (antibiotics) in combination with nystatin (antifungal) to select an antimicrobial combination for the inhibition of biofilm bacteria and adherent fungi that is effective and also non-toxic to marine phytoplankton and zooplankton. Acartia tonsa was exposed to different antimicrobial treatments and application routes (culture medium, culture food, both) to evaluate the survival and egg and fecal pellet production endpoints. The same treatments were also applied to measure Amphibalanus improvisus survival and settlement and Conticribra weissflogii growth endpoints. We selected the most sensitive experimental organism and exposed it to some novel antimicrobial combinations. To evaluate the inhibition potential, biofilm bacteria and adherent fungi were exposed to the treatments that were safe for the bioindicator species. A tonsa was considered the most sensitive of all tested organisms. The treatment composed of 0.025 g L−1 penicillin G potassium + 0.08 g L−1 streptomycin sulfate + 0.04 g L−1 neomycin sulfate showed the best results for A. tonsa and C. weissflogii cultures. No differences were observed for A. improvisus between the treatments. A. tonsa survival rates showed no differences from the control at nystatin concentrations up to 0.005 g L−1 in combination with the antibiotics. The biofilm bacterial density decreased up to 94% under this treatment, and fungal growth was prevented. Species of other planktonic groups should also be tested to improve our understanding of the effectiveness of the treatments proposed.

Biotic links in the fouling community of Odessa Bay (Black Sea)

This paper reveals the character of the biotic links between the various organisms that compose the fouling community of Odessa Bay (Black Sea). The fouling community of solid substrates is formed by 62 species of invertebrates and 12 species of macrophytes. The edificator species of the community is the Black Sea mussel Mytilus galloprovincialis Lamarck, 1819. The environment-forming role of the mussel, which is represents the core of the corresponding consortia, was examined. The leading role of sessile organisms in the formation of a superorganismic structure that significantly modifies the properties of the environment was revealed. Together with the mussel, this structure is formed by the bivalve mollusc Mytilaster lineatus (Gmelin, 1791) and the barnacle crustacean Amphibalanus improvisus (Darwin, 1854). The proportion of sessile organisms accounts for 24.6% of the total number of species in the community. In this case, they significantly dominate in relative abundance and biomass (78.9% and 98.8%, respectively). The mussels during the process of growth form complexly organized druses, which are peculiar three-dimensional formations, consisting of mussels of different sizes, fastened together with a substrate by an entire network of strong byssus threads. These formations increase the level of heterogeneity of the substrate and increase the variety of available habitats for other animals. The aggregate of these druses is a kind of sedimentary trap in which particles of nutritive detritus accumulate. The availability of accessible habitats, convenient shelters and food reserves attracts various species of invertebrates to the community. Around the core of the consortia a cluster of organisms formed associated with edificator species. An important role is played by trophic links between different mobile organisms and the phyto-component of the community. The ability of the Black Sea mussel to condition the environment, creating favourable conditions for the development of other organisms, characterizes it as an autogenic ecosystem engineer. Trophic and mediopathic links between the organisms that compose the fouling community go beyond it and extend to the inhabitants of the pelagic environment.

Long-term exposure to acidification disrupts reproduction in a marine invertebrate.

Climate change research is advancing to more complex and more comprehensive studies that include long-term experiments, multiple life-history stages, multi-population, and multi-trait approaches. We used a population of the barnacle Balanus improvisus known to be sensitive to short-term acidification to determine its potential for long-term acclimation to acidification. We reared laboratory-bred individuals (as singles or pairs), and field-collected assemblages of barnacles, at pH 8.1 and 7.5 (≈ 400 and 1600 μatm pCO2 respectively) for up to 16 months. Acidification caused strong mortality and reduced growth rates. Acidification suppressed respiration rates and induced a higher feeding activity of barnacles after 6 months, but this suppression of respiration rate was absent after 15 months. Laboratory-bred barnacles developed mature gonads only when they were held in pairs, but nonetheless failed to produce fertilized embryos. Field-collected barnacles reared in the laboratory for 8 months at the same pH’s developed mature gonads, but only those in pH 8.1 produced viable embryos and larvae. Because survivors of long-term acidification were not capable of reproducing, this demonstrates that B. improvisus can only partially acclimate to long-term acidification. This represents a clear and significant bottleneck in the ontogeny of this barnacle population that may limit its potential to persist in a future ocean.

Таксономический состав и сезонная динамика меропланктона в районе мидийно-устричной фермы (Севастополь, Чёрное море)

При организации мидийно-устричных ферм необходимо учитывать динамику численности личинок объектов культивирования и сопутствующих видов, которые могут неблагоприятно повлиять на качество и количество ожидаемой продукции марикультуры. В 2014–2017 гг. проведён мониторинг меропланктона в акватории мидийно-устричной фермы, расположенной на внешнем рейде Севастопольской бухты. Материал собирали ежемесячно сетью Джеди (диаметр входного отверстия — 36 см, размер ячеи газа — 135 мкм). Облавливали слой воды от дна до поверхности (10–0 м). Обработку проводили на живом материале путём тотального подсчёта личинок в камере Богорова под бинокуляром МБС-9. Идентифицированы личинки 62 таксонов, из них Bivalvia — 9 видов, Gastropoda — 15, Polychaeta — 19, Cirripedia — 2, Decapoda — 12, прочие — 5. Таксономический состав меропланктона зависел от сроков размножения донных беспозвоночных и изменялся по сезонам. С декабря по февраль численность меропланктона не превышала 195 экз.·м-3, число видов — 6. Увеличение количества видов и численности личинок отмечено с июня по сентябрь. Максимальная численность меропланктона зарегистрирована в августе 2014 г. Изучена сезонная динамика численности личинок мидии Mytilus galloprovincialis Lamarck, 1819 и потенциального объекта культивирования — анадары Anadara kagoshimensis (Tokunaga, 1906). Личинки M. galloprovincialis присутствовали в планктоне с середины сентября по май и отсутствовали в летние месяцы. Увеличение их численности зарегистрировано в апреле и сентябре — октябре. Зимний нерест мидий отмечен в декабре — январе при температуре воды 8,0–8,9 °C. Личинки анадары A. kagoshimensis встречались с июля по ноябрь. Их численность существенно увеличивалась в сентябре. Приведены данные по встречаемости личинок беспозвоночных, оказывающих негативное влияние на культивируемых моллюсков. Велигеры хищного брюхоногого моллюска Rapana venosa (Valenciennes, 1846) встречались с июля по октябрь. Личинки полихеты-перфоратора Polydora websteri Hartman in Loosanoff & Engle, 1943 обнаружены с июня по октябрь. Личинки полихеты Hydroides dianthus (Verrill, 1873) отмечены в октябре. Науплиусы усоногого рака Amphibalanus improvisus Darwin, 1854 присутствовали круглый год, их численность увеличивалась с марта по июнь и в октябре — ноябре. Сроки нахождения личинок в планктоне необходимо учитывать при планировании гидротехнических работ на мидийно-устричной ферме.

Multivariate analysis of attachment of biofouling organisms in response to material surface characteristics

Multivariate analyses were used to investigate the influence of selected surface properties (Owens-Wendt surface energy and its dispersive and polar components, static water contact angle, conceptual sign of the surface charge, zeta potentials) on the attachment patterns of five biofouling organisms (Amphibalanus amphitrite, Amphibalanus improvisus, Bugula neritina, Ulva linza, and Navicula incerta) to better understand what surface properties drive attachment across multiple fouling organisms. A library of ten xerogel coatings and a glass standard provided a range of values for the selected surface properties to compare to biofouling attachment patterns. Results from the surface characterization and biological assays were analyzed separately and in combination using multivariate statistical methods. Principal coordinate analysis of the surface property characterization and the biological assays resulted in different groupings of the xerogel coatings. In particular, the biofouling organisms were able to distinguish four coatings that were not distinguishable by the surface properties of this study. The authors used canonical analysis of principal coordinates (CAP) to identify surface properties governing attachment across all five biofouling species. The CAP pointed to surface energy and surface charge as important drivers of patterns in biological attachment, but also suggested that differentiation of the surfaces was influenced to a comparable or greater extent by the dispersive component of surface energy.

Projecting present and future habitat suitability of ship-mediated aquatic invasive species in the Canadian Arctic

A rise in Arctic shipping activity resulting from global warming and resource exploitation is expected to increase the likelihood of aquatic invasive species (AIS) introductions in the region. In this context, the potential threat of future AIS incursions at a Canadian Arctic regional scale was examined. Habitat suitability under current environmental conditions and future climate change scenarios was projected for a subset of eight potential invaders ranked as having a high risk of establishment in the Canadian Arctic based on dispersal pathways/donor regions, biological attributes and invasion history: (1) Amphibalanus improvisus, (2) Botrylloides violaceus, (3) Caprella mutica, (4) Carcinus maenas, (5) Littorina littorea, (6) Membranipora membranacea, (7) Mya arenaria and (8) Paralithodes camtschaticus. Habitat modelling was performed using MaxEnt based on globally known native and non-native occurrence records and environmental ranges for these species. Results showed that under current environmental conditions the habitat is suitable in certain regions of the Canadian Arctic such as the Hudson Complex and Beaufort Sea for L. littorea, M. arenaria and P. camtschaticus. Under a future climate change scenario, all species showed poleward gains in habitat suitability with at least some regions of the Canadian Arctic projected to be suitable for the complete suite of species modelled. The use of these models is helpful in understanding potential future AIS incursions as a result of climate change and shipping at large spatial scales. These approaches can aid in the identification of high risk regions and species to allow for more focused AIS monitoring and research efforts in response to climate change.

Analysis of aquaporins from the euryhaline barnacle Balanus improvisus reveals differential expression in response to changes in salinity.

Barnacles are sessile macro-invertebrates, found along rocky shores in coastal areas worldwide. The euryhaline bay barnacle Balanus improvisus (Darwin, 1854) (= Amphibalanus improvisus) can tolerate a wide range of salinities, but the molecular mechanisms underlying the osmoregulatory capacity of this truly brackish species are not well understood. Aquaporins are pore-forming integral membrane proteins that facilitate transport of water, small solutes and ions through cellular membranes, and that have been shown to be important for osmoregulation in many organisms. The knowledge of the function of aquaporins in crustaceans is, however, limited and nothing is known about them in barnacles. We here present the repertoire of aquaporins from a thecostracan crustacean, the barnacle B. improvisus, based on genome and transcriptome sequencing. Our analyses reveal that B. improvisus contains eight genes for aquaporins. Phylogenetic analysis showed that they represented members of the classical water aquaporins (Aqp1, Aqp2), the aquaglyceroporins (Glp1, Glp2), the unorthodox aquaporin (Aqp12) and the arthropod-specific big brain aquaporin (Bib). Interestingly, we also found two big brain-like proteins (BibL1 and BibL2) constituting a new group of aquaporins not yet described in arthropods. In addition, we found that the two water-specific aquaporins were expressed as C-terminal splice variants. Heterologous expression of some of the aquaporins followed by functional characterization showed that Aqp1 transported water and Glp2 water and glycerol, agreeing with the predictions of substrate specificity based on 3D modeling and phylogeny. To investigate a possible role for the B. improvisus aquaporins in osmoregulation, mRNA expression changes in adult barnacles were analysed after long-term acclimation to different salinities. The most pronounced expression difference was seen for AQP1 with a substantial (>100-fold) decrease in the mantle tissue in low salinity (3 PSU) compared to high salinity (33 PSU). Our study provides a base for future mechanistic studies on the role of aquaporins in osmoregulation.

Non-native zoobenthic species at the Crimean Black Sea Coast

More than 40 non-native species have been registered in the zoobenthos of the Black Sea. Only, five alien species, the Crustacea, Rhithropanopeus harrisii (Gould, 1841) and Rhithropanopeus harrisii (Gould, 1841), and the Mollusca, Rapana venosa (Valenciennes, 1846), Mya arenaria (Linne, 1758) and Anadara kagoshimensis (Tokunaga, 1906), were recorded in the benthos on the Crimean shelf between 1999-2014. The blood-cockle A. kagoshimensis had settled on many sites of the Black Sea shelf in the past forty years. The first detection (1999) at the Crimean coast and the temporal variability of this mollusc’s population coincided with the tendency in variability of the water temperature in the area.The five alien species had spatial aggregation and their occurrence did not exceed 23 % in the boundaries of the distribution sites. An increasing trend for their abundance in the last five - seven years was observed. These years were characterized by temperature rise in the surface layer of coastal waters. Similar patterns have been observed in the interannual variability of the biomass and abundance ratio of aliens to native for all zoobenthic taxonomic groups, i.e. of dominance index of alien species.The low level of the dominance index of the introduced species is indicative of low impact on the diversity of the benthic communities of the Crimea coast, i.e. on the scale of the metacommunity. With the exception of the R. venosa, they exhibited lower biomass and abundance along the Crimean coast shelf as opposed to other areas of the Black Sea shelf. Occasionally, the dominance index for the barnacle Amphibalanus improvisus (Darwin, 1854) could be high, a fact attributed to the low biomass and abundance of other benthic species.

Long-term dynamics of the state of the fouling community in the Odessa Bay (Black Sea)

This article examines the long-term dynamics of the qualitative and quantitative characteristics of the coastal fouling community of OdessaBay(Black Sea) for the last 40 years. It compares the data on this community obtained by different researchers in 1976, 1994 and 2016 . The number of species included in the fouling community decreased from 103 (1976) to 43 (1994) and then rose to 62 by 2016. As a possible reason for this reduction in the species composition of the community the influence of large-scale anthropogenic eutrophication, which was already strongly evident in the north-western part of the Black Seain the 1970s, is proposed. This phenomenon was accompanied by periodic outbreaks of mass abundance of planktonic algae, secondary water pollution, the development of hypoxia and a frequent suffocation effect on the benthos, which caused the disappearance from the community of 41 species of invertebrates. The reduction in the number of species affected representatives of the following taxons: Polychaeta, Amphipoda, Gastropoda and Bivalvia. Currently, the core of the community includes the same species of invertebrates as in the past. It is based on Bivalvia mussels Mytilus galloprovincialis. Among the attached forms , Mytilaster lineatus (Bivalvia) and Amphibalanus improvisus (Cirripedia) play a leading role, and among mobile – representatives of Polychaeta, Isopoda, Amphipoda and Gastropoda. It is shown that 10 of the 25 species, recorded the first time for this community in the 1970s, have become abundant in modern conditions. The primacy in the relative density in the composition of the community at the present time has passed from the amphipod crustaceans to bivalve molluscs. The highest relative biomass, both in the past and in the present-day conditions was observed in representatives of Bivalvia. The structure of the resistance of the fouling community to the effects of unstable environmental factors specific to the coastal zone is discussed. Overall, it was found that those species which have been preserved in the community are habitat generalist invertebrates, which are well adapted to sharp fluctuations in temperature and salinity of sea water, as well as to periodic storm impact.

СОСТОЯНИЕ КОРМОВОЙ БАЗЫ БЕНТОСОЯДНЫХ РЫБ В ДЕЛЬТЕ РЕКИ УРАЛ И СЕВЕРНОМ КАСПИИ

The paper presents the results of the research held in spring-autumn, 2014. In the course of the research there were used complex field observations. There was determined qualitative composition of zoobenthos of the lower reaches and the delta of the Ural (13 taxons) and the North part of the Caspian Sea (33 taxons, main groups: crustaceans, molluscas and worms), quantity and biomass of main species and groups of zoobenthos. In the lower reaches of the Ural Oligochaeta worms made the largest group, Chironomidae larvae made a smoller group. In August average biomass of zoobenthos in the delta of the Ural made 16.66 g/m2. In the North part of the Caspian Sea maximum domination index belonged to Oligochaeta - 12.5; Hypanis vitrea vitrea had 7.1; Chironomidae larvae - 6.4. Corophiidae were numerous , with domination index 6.3; Balanus improvisus had 6.2; Hediste diversicolor - 4.7. Domination index of other bottom organisms didn’t exceed 3.8. Average biomass of bottom organizms in the North Part of the Caspian Sea made: in June - July 20.48 g/m2, in September 9.212 g/m2. Stern zoobenthos took (without taking into account large molluscas and barnacles) 8.14 and 3.8 g/m2, respectively. The data obtained can be used for determining methods of saving and stable use of fish resources in the Ural-Caspian Sea basin.

Probing the Structure-Activity Relationship of the Natural Antifouling Agent Polygodial against both Micro- and Macrofoulers by Semisynthetic Modification.

The current study represents the first comprehensive investigation into the general antifouling activities of the natural drimane sesquiterpene polygodial. Previous studies have highlighted a high antifouling effect toward macrofoulers, such as ascidians, tubeworms, and mussels, but no reports about the general antifouling effect of polygodial have been communicated before. To probe the structural and chemical basis for antifouling activity, a library of 11 polygodial analogues was prepared by semisynthesis. The library was designed to yield derivatives with ranging polarities and the ability to engage in both covalent and noncovalent interactions, while still remaining within the drimane sesquiterpene scaffold. The prepared compounds were screened against 14 relevant marine micro- and macrofouling species. Several of the polygodial analogues displayed inhibitory activities at sub-microgram/mL concentrations. These antifouling effects were most pronounced against the macrofouling ascidian Ciona savignyi and the barnacle Balanus improvisus, with inhibitory activities observed for selected compounds comparable or superior to several commercial antifouling products. The inhibitory activity against the microfouling bacteria and microalgae was reversible and significantly less pronounced than for the macrofoulers. This study illustrates that the macro- and microfoulers are targeted by the compounds via different mechanisms.

Nutrient removal by biomass accumulation on artificial substrata in the northern Baltic Sea

We studied the potential of utilizing non-seeded artificial substrata in growing macrofauna and macroalgae to remove excess nutrients from seawater in the northern Baltic Sea. Succession, species composition, and biomass on two different substratum types were studied. Organic carbon (C), nitrogen (N), and phosphorus (P) as well as heavy metal (As, Cd, Cu, Pb, and Zn) contents were measured from the algal species and the invertebrate fraction. The invertebrate fraction formed more than 94% of the total biomass and consisted of blue mussels (Mytilus trossulus), bay barnacles (Amphibalanus improvisus), and hydroids (Cordylophora caspia and Gonothyraea loveni). Major algal species consisted of green algae Ulva spp. and Cladophora glomerata, red algae Ceramium tenuicorne and Polysiphonia fibrillosa, and filamentous brown algae Pylaiella littoralis and Ectocarpus siliculosus. The highest biomasses were measured at the end of the experiment, after 14.5 months of exposure in the sea, when the total biomass was on average 2.4 kg dry weight (DW) m−2 substratum, containing approximately 50 g N and 5 g P. The heavy metal concentrations were site and species dependent and on average lower in the invertebrate fraction compared with the macroalgal fraction. In some cases especially, Cd may limit biomass use as fertilizers. According to these results, annual N and P emissions from small-sized point sources could be reduced by using artificial substrata to remove sessile organisms, but this would require extensive cultivations. Furthermore, the utilization of the marine macroalgal and invertebrate biomass in biogas production requires adding more carbon-rich feedstock to obtain optimal results.

PDMS-based films containing surface-active amphiphilic block copolymers to combat fouling from barnacles B. amphitrite and B. improvisus

Surface-active amphiphilic diblock copolymers, Si-EFS14 and Si-EFS71, consisting of a poly(dimethyl siloxane) block (degree of polymerisation 11) and a poly(4-(triethyleneglycol monomethyl ether)-2,3,5,6-tetrafluorostyrene) block (average degree of polymerisation 14 and 71) were synthesised by ATRP. Films were prepared by incorporating each copolymer (4 wt%) into a PDMS matrix, which was then condensation cured. Bioassays were performed on the films using two barnacle species, Balanus amphitrite and Balanus improvisus, at different stages of their life cycles. The cyprids of B. improvisus settled on all test surfaces in higher numbers than those of B. amphitrite. However, the juveniles of B. improvisus were more easily removed from the films containing the copolymer Si-EFS14 than from those containing the copolymer Si-EFS71. An XPS analysis revealed that the near-surface region of copolymer Si-EFS71 was enriched in oxyethylenic chains and became even more populated by these hydrophilic chains after the films were immersed in water.

Factors affecting the recruitment of Amphibalanus improvisus and Dreissena polymorpha in a highly eutrophic brackish bay

Species invasions are modifying ecosystems worldwide. Coexistence of invasive species of no common evolutionary history in their new ranges enables the study of ecological rules shaping novel communities at their initial stages. In oligohaline parts of the Baltic Sea, the most dominant and widespread epifaunal suspension feeders are invasive mussels Dreissena polymorpha and cirripeds Amphibalanus improvisus. This study experimentally evaluated recruitment and microhabitat use in response to environmental forcing in these two species in a eutrophic bay. Recruitment was structured by different microhabitat exploitation patterns coupled with both individual and interactive effects of several environmental gradients. Despite functional similarity, the importance of environmental gradients differed between these species: mussel recruitment was best explained by temperature while barnacle recruitment was best explained by wave exposure. Zebra mussels were more fastidious about surface orientation than barnacles. The preferred orientations also differed between species, as mussels strongly preferred horizontal surfaces, while barnacles were more abundant on vertical surfaces. Increase in one species also predicted well the abundance of the other, especially for barnacles, as mussel abundance was the best predictor of barnacle abundance over all the other factors. The extent of microhabitat segregation correlated weakly over the studied range of the most important environmental gradients. The study shows that coexistence of functionally similar non-native D. polymorpha and A. improvisus in their sympatric range is likely determined by complex interactions between these species, their different microhabitat exploitation patterns, environmental limitations and optima.

Population and life-stage specific sensitivities to temperature and salinity stress in barnacles

Temperature and salinity shape the distribution and genetic structure of marine communities. Future warming and freshening will exert an additional stress to coastal marine systems. The extent to which organisms respond to these shifts will, however, be mediated by the tolerances of all life-stages and populations of species and their potential to adapt. We investigated nauplius and cypris larvae of the barnacle Balanus (Amphibalanus) improvisus from the Swedish west coast with respect to temperature (12, 20, and 28 °C) and salinity (5, 15, and 30) tolerances. Warming accelerated larval development and increased overall survival and subsequent settlement success. Nauplii developed and metamorphosed best at intermediate salinity. This was also observed in cypris larvae when the preceding nauplii stages had been reared at a salinity of 30. Direct comparisons of the present findings with those on a population from the more brackish Baltic Sea demonstrate contrasting patterns. We conclude that i) B. improvisus larvae within the Baltic region will be favoured by near-future seawater warming and freshening, that ii) salinity tolerances of larvae from the two different populations reflect salinities in their native habitats, but are nonetheless suboptimal and that iii) this species is generally highly plastic with regard to salinity.

Epibiontes en juveniles de tortugas carey Eretmochelys imbricata varadas en la costa del Departamento de Rocha, Uruguay

The hawksbill turtle (Eretmochelys imbricata) is the most threatened sea turtle species in the world. An important aspect of the biology of sea turtles is the study of colonizing fauna, i.e., their epibiota. The aim of this study is a taxonomic determination on the epibiota found on 4 hawksbills turtles stranded in 2009 and 2011 on the coast of Rocha Department, Uruguay. The epibiota was composed by algae from the class Phaeophyceae (Sphacelaria sp. and Hincksia mitchelliae) and invertebrates from the classes Cirripedia (Platylepas hexastylos, Chelonibia testudinaria and Amphibalanus improvisus) and Hirudinea (Ozobranchus margoi), with greater predominance of P. hexastylos cirripeds (n= 365), a result that is consistent with other similar studies. Hincksia mitchelliae and A. improvisus are new reports as hawksbill turtles' epibiota.

Artificial hard substrate as a habitat for hard bottom benthic assemblages in the southern part of the Baltic Sea – a preliminary study

Abstract Benthic species associated with hard substrate are known to form communities characterized by high abundance and biomass. Although the bottom of the Southern Baltic Sea is dominated by soft sediments, such communities find favorable conditions to thrive on artificial substrates of offshore constructions. The aim of this research was to characterize both short-term and long-term benthic communities associated with artificial hard bottom provided by man-made structures in the Southern Baltic Sea. Species composition as well as the abundance and biomass were examined at various sites. An inactive World War II torpedo testing facility in the Gulf of Gdansk served as a site for sampling long-term communities while short-term communities were sampled using settlement panels and PVC cylinders. Panels were deployed at the torpedo testing facility for 127 days. PVC cylinders were deployed for 141-190 days in the Polish Exclusive Economic Zone. Twenty six macrofaunal taxa, including 12 crustaceans, were identified during the research. Mytilus edulis and Amphibalanus improvisus were the most abundant invertebrates at sampled surfaces. Six non-indigenous species were found. For the first time adult individuals of Mytilopsis leucophaeata were found in the Polish Marine Areas indicating that it is possible for this non-indigenous species to reproduce in this region.

The Story of a Hitchhiker: Population Genetic Patterns in the Invasive Barnacle Balanus(Amphibalanus) improvisus Darwin 1854.

Understanding the ecological and evolutionary forces that determine the genetic structure and spread of invasive species is a key component of invasion biology. The bay barnacle, Balanus improvisus (= Amphibalanus improvisus), is one of the most successful aquatic invaders worldwide, and is characterised by broad environmental tolerance. Although the species can spread through natural larval dispersal, human-mediated transport through (primarily) shipping has almost certainly contributed to the current global distribution of this species. Despite its worldwide distribution, little is known about the phylogeography of this species. Here, we characterize the population genetic structure and model dispersal dynamics of the barnacle B. improvisus, and describe how human-mediated spreading via shipping as well as natural larval dispersal may have contributed to observed genetic variation. We used both mitochondrial DNA (cytochrome c oxidase subunit I: COI) and nuclear microsatellites to characterize the genetic structure in 14 populations of B. improvisus on a global and regional scale (Baltic Sea). Genetic diversity was high in most populations, and many haplotypes were shared among populations on a global scale, indicating that long-distance dispersal (presumably through shipping and other anthropogenic activities) has played an important role in shaping the population genetic structure of this cosmopolitan species. We could not clearly confirm prior claims that B. improvisus originates from the western margins of the Atlantic coasts; although there were indications that Argentina could be part of a native region. In addition to dispersal via shipping, we show that natural larval dispersal may play an important role for further colonisation following initial introduction.