The impact of habitat complexity on the structure of marine sessile communities and larvae supply

Coastal infrastructure replaces complex and heterogeneous natural habitats with flat, two-dimensional concrete walls, reducing refuges against predation, which modifies the composition and identity of the dominant species in sessile communities. This modification in the community structure can also change the reproductive propagules available in plankton, affecting the recruitment dynamics in communities from natural habitats nearby. Here, we tested the combined effects of the habitat type (simple vs. complex with holes) and predation on the diversity, larval production, and structure of sessile communities from a recreational marina. Complex substrates showed a larger biomass and a greater abundance of solitary organisms, mainly ascidians and bivalves, that benefited from refuges. Barnacles and calcified encrusting bryozoans dominated simple, flat substrates. The difference in dominance affected the pool of larvae produced by the communities. After eight months, communities growing on flat substrates produced more barnacle larvae than those from complex substrates, where larvae of ascidians were more abundant. However, this difference disappeared after 18 months of community development. The difference in the pool of larvae between simple and complex substrates did not affect the structure of the community on flat substrates nearby, which was determined by the predation regime. In the studied region, communities in artificial environments are under intense predation control, suppressing eventual recruitment differences in communities developing in flat substrates. Large interventions that modify habitat topography, creating refuges in the subtidal zone, can change the dynamic of the sessile communities in artificial habitats and, consequently, the larval supply in the vicinities. However, differences in larval supply will only translate in distinct sessile communities when the scale of intervention encompasses large areas, and other processes do not buffer the differences in recruitment.

Seeding artificial habitats with native benthic species can prevent the occurrence of exotic organisms

Seeding native species on pillars and platforms of marinas and harbors has been suggested to reduce space availability and prevent the colonization of exotic nuisance species, which are usually associated with coastal urbanization. The efficacy of seeding, however, has been tested mainly on the intertidal zone. To test how seeding native species in the subtidal zone affects the subsequent colonization and spread of exotic species and the community diversity, we deployed 10 PVC plates seeded with adults of the native sponge Mycale angulosa, 10 with the native ascidian Symplegma rubra, both covering about 6% of the available substrate, and 10 plates free of any intervention in a recreational marina from the Southwestern Atlantic Ocean. We then assessed the diversity and structure of the sessile community across treatments after eight months. Seeding the substrate with S. rubra resulted in no difference to unseeded communities, which were dominated by the exotic bryozoan Schizoporella errata (>66% of the substrate) and supported on average 16.9 ± 1.3 and 14.2 ± 2.0 morphospecies, respectively. However, seeding the substrate with M. angulosa resulted in a distinct community dominated by the seeded sponge (>97% of the substrate) and supporting only 3.2 ± 0.5 morphospecies. Besides, all 13 registered exotic species were reported from communities seeded with S. rubra, 11 from the unseeded communities, but only three were observed in those seeded with M. angulosa. While the consequences of the low diversity of the community seeded with M. angulosa must be addressed since poor communities are usually associated with low biotic resistance to invasion, seeding resulted in a high dominance of the native sponge, reducing the monopolization of resources by exotic species. These results suggest that seeding the substrate with native species should be implemented along with other interventions for managing artificial habitats in the coastal zone.

Predator control of marine communities increases with temperature across 115 degrees of latitude

Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.

Enduring regardless the conditions: Plasticity in modular growth as a strategy to cope with hydrodynamic variation by the invasive sun-coral (Tubastraea spp.)

The susceptibility of a community to invasions is not the only factor influencing the success of the introduction of non-indigenous species (NIS). Because the conditions of the invaded environment tend to be unpredictable, plastic responses should increase the success of NIS in a new environment. Sun-corals are invaders in the Atlantic Ocean that present a range of strategies and plastic responses to deal with stress and distinct environmental conditions. We experimentally tested the plastic responses of sun-corals when exposed to different predation pressures and hydrodynamics in a recreational marina where sun-corals abundance varies spatially along with the environmental conditions. We separated young sun-coral colonies in two experiments: one controlling the presence of predators and the other manipulating water motion. While predation had no effect, revealing that even small young colonies are somehow protected against predators, corals increased colony area under reduced water motion but grew more polyps under greater water motion. These results highlight that plasticity in modular growth may be important for sun-corals to successfully invade distinct regions despite the hydrodynamic conditions. Increasing the colony area implicate in monopolization of space in calmer waters whilst growing more polyps allows it to have more mouths for feeding in turbulent food-poor waters. This response is particularly interesting as it is similar to the response of another NIS in the same site-the bryozoan Schizoporella errata. Phenotypic plasticity of reproductive strategies, including asexual propagation as observed here, appears to be relevant for modular NIS by facilitating the success on the invasion process in variable habitats.

Colonization history meets further niche processes: how the identity of founders modulates the way predation structure fouling communities

Community assembly relies on deterministic niche-based processes (e.g., biotic interactions), and stochastic sources of unpredictable variation (e.g., colonization history), that combined will influence late-stage community structure. When community founders present distinct functional traits and a colonization-competition trade-off is not operating, initial colonization can result in late-stage assemblages of variable diversity and composed by different species sets, depending if early colonizers facilitate or inhibit subsequent colonization and survival. By experimentally manipulating the functional identity of founders and predators access during the development of fouling communities, we tested how founder traits constrain colonization history, species interactions and thereby regulate community diversity. We used as founders functionally different fouling organisms (colonial and solitary ascidians, and arborescent and flat-encrusting bryozoans) to build experimental communities that were exposed or protected against predation using a caging approach. Ascidians and bryozoans are pioneer colonizers in benthic communities and also good competitors, but the soft-body of ascidians makes them more susceptible to predators than mineralized bryozoans. When ascidians were founders, their dominance (but not richness) was reduced by predation, resulting in no effects of predators on overall diversity. Conversely, when bryozoans were founders, both space limitation and predator effects resulted in species-poor communities, with reduced number and cover of ascidian species and high overall dominance at the end of the experiment. We, thus, highlight that current species interactions and colonization contingencies related to founder identity should not be viewed as isolated drivers of community organization, but rather as strongly interacting processes underlying species distribution patterns and diversity.

Evaluation of antileishmanial activity of harzialactone a isolated from the marine-derived fungus Paecilomyces sp

Fractionation of extracts from the culture broth of the marine-derived fungus, Paecilomyces sp. 7A22, resulted in the isolation of the harzialactone A (HA), a known compound previously isolated from fungi of marine environments. The chemical structure of HA was determined by spectroscopic analyses. Upon evaluation of HA on antileishmanial assays against Leishmania amazonensis, HA exhibited significant activity against promastigotes forms with IC50 of 5.25 µg mL-1 and moderate activity against intracellular amastigotes with IC50 of 18.18 µg mL-1. This is the first report on the antileishmanial activity of HA, and the effects of HA presented in this work suggest that this class of compounds are suitable for future biological in vitro and in vivo studies for the search of natural products with activity against Leishmania spp. Furthermore, the present results corroborate marine-derived fungi as a promising source of natural products with antiparasitic activity.

Different ontogenetic trajectories of body colour, pattern and crypsis in two sympatric intertidal crab species

Animals frequently exhibit great variation in appearance, especially in heterogeneous habitats where individuals can be concealed differentially against backgrounds. Although background matching is a common anti-predator strategy, gaps exist in our understanding of within- and among-species variation. Specifically, the drivers of changes in appearance associated with habitat use and occurring through ontogeny are poorly understood. Using image analysis, we tested how individual appearance and camouflage in two intertidal crab species, the mud crab Panopeus americanus and the mottled crab Pachygrapsus transversus, relate to ontogeny and habitat use. We predicted that both species would change appearance with ontogeny, but that resident mud crabs would exhibit higher background similarity than generalist mottled crabs. Both species showed ontogenetic changes; the mud crabs became darker, whereas mottled crabs became more green. Small mud crabs were highly variable in colour and pattern, probably stemming from the use of camouflage in heterogeneous habitats during the most vulnerable life stage. Being habitat specialists, mud crabs were better concealed against all backgrounds than mottled crabs. Mottled crabs are motile and generalist, occupying macroalgae-covered rocks when adults, which explains why they are greener and why matches to specific habitats are less valuable. Differential habitat use in crabs can be associated with different coloration and camouflage strategies to avoid predation.

Artificial habitats induce plasticity in colonies of the marine bryozoan Schizoporella errata

Modular organization provides flexibility for colonial animals to deal with variable and unpredictable environmental conditions since each module has specific tasks within the colony, such as feeding, defending or reproducing. Depending on the selecting pressures, sessile organisms may phenotypically adjust the morphology of each module or modify their density, increasing individual fitness. Here we used the marine bryozoan Schizoporella errata (Cheilostomata, Schizoporellidae) to test how the divergent conditions between two artificial habitats, the location inside a marina (IM) and the external wall of the breakwater (BW), affect colony size and the density of the distinct modules. The density of avicularia and ovicells, modules related to defense and reproduction, respectively, did not differ between habitats. However, colonies growing in the turbulent waters of BW were, in general, larger and had higher density of feeding autozooids than those at IM. Reciprocal transplants of bryozoan clones indicated that trait variation is genotype-dependent but varies according to the environmental conditions at the assigned location. The occurrence of larger colonies with more zooids in BW is probably linked to the easier feeding opportunity offered by the small diffusive boundary layer around the colony at this location. Since in colonial polymorphic organisms each module (zooid) performs a specific function, the phenotypic response is not uniform across colonies, affecting only those modules that are susceptible to variations in the main selective pressures. Understanding the importance of colony-level plasticity is relevant to predict how modularity will contribute to organisms to deal with human-induced environmental changes in coastal habitats.

Exotic species dominate marinas between the two most populated regions in the southwestern Atlantic Ocean

Human occupation of coastal areas promotes the establishment of non-native species but information on bioinvasions is usually biased toward the Northern Hemisphere. We assessed non-native species' importance in sessile communities at six marinas along the most urbanized area of the Southwestern Atlantic coastline. We found 67 species, of which 19 are exotic. The most frequent species was the exotic polychaete Branchiomma luctuosum, while the most abundant was the exotic bryozoan Schizoporella errata that monopolized the substrata in three marinas. Along with S. errata, the exotic polychaete Hydroides elegans and ascidian Styela plicata dominated space in the three remaining marinas, while native species were in general rare. We show that communities associated with artificial substrata along this Brazilian urbanized area are dominated by exotic species and that using abundance data along with species identity can improve our understanding of the importance of exotic species for the dynamics of biological communities.

Colonial ascidians strongly preyed upon, yet dominate the substrate in a subtropical fouling community

Higher diversity and dominance at lower latitudes has been suggested for colonial species. We verified this pattern in species richness of ascidians, finding that higher colonial-to-solitary species ratios occur in the tropics and subtropics. At the latitudinal region with the highest ratio, in southeastern Brazil, we confirmed that colonial species dominate space on artificial plates in two independent studies of five fouling communities. We manipulated settlement plates to measure effects of predation and competition on growth and survivorship of colonial versus solitary ascidians. Eight species were subjected to a predation treatment, i.e. caged versus exposed to predators, and a competition treatment, i.e. leaving versus removing competitors, to assess main and interactive effects. Predation had a greater effect on growth and survivorship of colonial compared to solitary species, whereas competition did not show consistent patterns. We hypothesize that colonial ascidians dominate at this subtropical site despite being highly preyed upon because they regrow when partially consumed and can adjust in shape and space to grow into refuges. We contend that these means of avoiding mortality from predation can have large influences on diversification patterns of colonial species at low latitudes, where predation intensity is greater.

Two bifunctional desferrioxamine chelators for bioorthogonal labeling of biovectors with zirconium-89

We report two bifunctional chelators, DFO-Cys and DFO-CBT, to label biovectors with zirconium-89 according to the 2-cyanobenzothiazole/1,2-aminothiol cycloaddition. Their features are high labeling yields, rapid and efficient bioconjugation, metabolically stable luciferin-based end products, and applicability to orthogonal two-step labeling of sensitive biomolecules.

Generation of patient-specific induced pluripotent stem cell lines from one patient with Jervell and Lange-Nielsen syndrome, one with type 1 long QT syndrome and two healthy relatives

Four human iPSC cell lines (one Jervell and Lange-Nielsen Syndrome, one Long QT Syndrome-type 1 and two healthy controls) were generated from peripheral blood obtained from donors belonging to the same family. CytoTune™-iPS 2.0 Sendai Reprogramming Kit (containing OCT3/4, KLF4, SOX2 and cMYC as reprogramming factors) was used to generate all cell lines. The four iPSCs have normal karyotype, express pluripotency markers as determined by RT-PCR and flow cytometry and differentiated spontaneously in vitro into cells of the three germ layers, confirming their pluripotent capacity.

Persistence and space preemption explain species-specific founder effects on the organization of marine sessile communities

Community assembly may not follow predictable successional stages, with a large fraction of the species pool constituted by potential pioneering species and successful founders defined through lottery. In such systems, priority effects may be relevant in the determination of trajectories of developing communities and hence diversity and assemblage structure at later advanced states. In order to assess how different founder species may trigger variable community trajectories and structures, we conducted an experimental study using subtidal sessile assemblages as model. We manipulated the identity of functionally different founders and initial colony size (a proxy of the time lag before the arrival of later species), and followed trajectories. We did not observe any effects of colony size on response variables, suggesting that priority effects take place even when the time lag between the establishment of pioneering species and late colonizers is very short. Late community structure at experimental panels that started either with the colonial ascidian Botrylloides nigrum, or the arborescent bryozoan Bugula neritina, was similar to control panels allowed natural assembling. In spite of high potential for fast space domination, and hence negative priority effects, B. nigrum suffered high mortality and did not persist throughout succession. Bugula neritina provided complex physical microhabitats through conspecific clustering that have enhanced larval settlement of late species arrivals, but no apparent facilitation was observed. Differently, panels founded by the encrusting bryozoan Schizoporella errata led to different and less diverse communities compared to naturally assembled panels, evidencing strong negative priority effects through higher persistence and space preemption. Schizoporella errata founder colonies inhibited further conspecific settlement, which may greatly relax intraspecific competition, allowing resource allocation to colony growth and space domination, thus reducing the chances for the establishment of other species.

Current conditions and colonization history asymmetrically shape the organization of shallow sessile communities after simulated state shifts

Historical processes affecting biological organization are rarely considered when predicting the effects of disturbance on community structure. In order to assess the relative importance of historical and post-disturbance conditions as determinants of community structure, we undertook reciprocal transplants, at different successional stages, of sessile communities developing at recreational piers that were previously observed to show contrasting fish predation pressure and settlement rate in the São Sebastião Channel, Brazil. Regardless the direction of state shift, after 15 weeks communities converged to the destination site structure, substantially drifting away from the path observed at origin, therefore revealing high susceptibility to environmental change. Although converging, transplanted communities never matched the destination standard in both transplant directions, suggesting that history still mattered, as providing some legacy that lasted, at least, for 15 weeks. The taxonomic groups resisting community drift were hard-bodied invertebrates, which could eventually provide some resilience to these communities through ecosystem engineering.

Distinct community dynamics at two artificial habitats in a recreational marina

Man-made facilities along coastlines modify water circulation and sedimentation dynamics which can affect the structure of marine benthic and pelagic communities. To test how environmental heterogeneity associated with a recreational marina affects the structure of the fouling community and the benthic-pelagic link, we conducted an experiment in which predation effects on recruitment and community structure were assessed in two artificial habitats: inside the marina, an area of calm waters and often disturbed by boating activity, and the breakwater, a more hydrodynamic area. Using visual censuses and video footages we also described the predation pressure and the identity of predators on the two areas. Inside the marina, the recruitment of ascidians and serpulids, but not of bryozoans, was restricted in some occasions, possibly due to reduced water circulation. Predation, mainly by the silver porgy fish Diplodus argenteus, reduced the survivor of didemnid ascidians on both areas, but predation intensity was 40 times higher in the breakwater than inside the marina. While the two artificial habitats did not necessarily support distinct communities, low recruitment coupled to weak predation inside the marina, a less dynamic environment, likely imply lower resilience and more susceptibility to disturbance.

Thiol-disulfide proteins of stallion epididymal spermatozoa

Thiol groups of cysteine residues represent redox centers involved in multiple biological functions. It has been postulated that changes in the redox status of mammalian epididymal spermatozoa contribute to the sperm maturation process. The present work shows the thiol-disulfide protein profile of stallion epididymal spermatozoa achieved by two-dimension electrophoresis and MALDI-TOF/TOF mass spectrometry of proteins labeled with a thiol-reactive fluorescent tag, monobromobimane. Our results have shown the formation of disulfide bonds in several sperm protein fractions during the epididymal maturation process. The majority of the oxidized thiol sperm proteins identified correspond to structural molecules of the flagellum (as the outer dense fiber-1 protein - ODF1), followed by glycolytic enzymes (as glyceraldehyde-3-phosphate dehydrogenase spermatogenic), antioxidant protectors (as glutathione S-transferase and phospholipid hydroperoxide glutathione peroxidase - PHGPx). The magnitude of the thiol oxidation differs between proteins, and was more drastic in polypeptides with molecular weights of up to 33kDa, identified as ODF1 and PHGPx. A kinase anchor protein, a voltage-dependent anion channel protein and a zona pellucida-binding protein were also found in the polypeptide samples that contained oxidized SH groups. These proteins may be modified or controlled by the mechanisms involved in the cysteine-redox changes, corroborating the belief that a correct degree of protein oxidation is required for the stabilization of sperm structure, protection against oxidative damage, induction of progressive sperm motility and fertilization.

Nuclear status of immature and mature stallion spermatozoa

'The highly packed chromatin of mature spermatozoa results from replacement of somatic-like histones by highly basic arginine- and cysteine-rich protamines during spermatogenesis, with additional conformational changes in chromatin structure during epididymal transit. The objective of the present study was to compare the nuclear characteristics of immature and mature epididymal stallion spermatozoa, using a variety of experimental approaches. Resistance to in vitro decondensation of chromatin, following exposure to SDS-DTT and alkaline thioglycolate, increased significantly in mature spermatozoa. Evaluation of the thiol-disulfide status (monobromobimane labeling) demonstrated that immature cells obtained from ductulli efferentes contained mostly thiol groups, whereas these groups were oxidized in mature cells collected from the cauda epididymidis. Based on atomic absorption spectrophotometry, maturation of stallion spermatozoa was accompanied by a 60% reduction in the Zn(2+) content of sperm cells, concomitant with increased concentrations of this ion in epididymal fluid. Furthermore, the degree of disulfide bonding was inversely correlated with susceptibility of chromatin to acid denaturation (SCSA). Collectively, these data were consistent with the hypothesis that maturation of stallion spermatozoa involves oxidation of sulphydryl groups to form intra- and intermolecular disulfide links between adjacent protamines, with loss of zinc as an integral feature. These changes endow mechanical and chemical resistance to the nucleus, ensuring efficient transmission of the paternal genome at fertilization.

A tunable diode laser system for ammonia flux measurements over multiple plots

This paper reports on the field testing of a tunable diode laser trace gas analyzer system for micrometeorological monitoring of ammonia fluxes. This system uses infrared absorption spectroscopy to measure atmospheric ammonia concentrations and the fluxgradient method to relate the measured concentration gradient to a flux of ammonia. For the field tests, we monitored ammonia fuxes over three plots receiving different manure applications. Each plot was sampled for 15 or 30 min of each hour, producing a high-temporal resolution data set. Analysis of the system response showed that ammonia adsorption to the tubing walls was greatly reduced by the system design and did not interfere with the flux measurement.

[Transparieto-hepatic cholangiography with the Chiba needle. Experience in 100 cases]

One-hundred cases submitted to percutaneous transhepatic cholangiography (PTC) with Chiba's needle were studied. Success rate was 93%, with 100% success in patients with dilated ducts and 78.8% in those with normal ducts. One false-positive result was noticed due to air injection into bile duct in the beginning of the procedure. Complications were seen in 8 cases, without fatalities ascribed to the PTC itself, nor emergency laparotomy was necessary in these cases.