Application of Potentiometric and Electrophoretic Measurements to Evaluate the Reversibility of Adsorption of Divalent Ions from a Solution on Titanium Dioxide.

The adsorption of divalent ions on metal oxides is controlled by the pH of a solution. It is commonly assumed that this is a reversible process for pH changes. However, there are reports that the sorption of ions on oxides may not be reversible. To verify this, we used potentiometric titration, ion-selective electrodes (ISEs), and electrokinetic measurements to examine the reversibility of the adsorption of hydrogen ions and three metal ions (Ca2+, Cu2+, and Fe2+) on TiO2. The ferrous ion was used as a reference because its adsorption is entirely irreversible. The surface charge determined by potentiometric titration and the adsorption edges measured using ISE indicate that the adsorption of copper ions is reversible with changes in pH. In the case of calcium ions, the results suggest a certain degree of irreversibility. There are apparent differences in the electrokinetic potential data obtained during titration with base and acid, which suggests that the adsorption is irreversible. We have explained this contradiction by considering the complex and dynamic nature of electrophoretic mobility. In our opinion, potentiometric titration may be the simplest and most reliable method for assessing the reversibility of multivalent ion adsorption.

Are We Ready to Get Rid of the Terms "Chalimus" and "Preadult" in the Caligid (Crustacea: Copepoda: Caligidae) Life Cycle Nomenclature?

In view of recent studies, we suggest that the term "preadult" should not be used in scientific reports on Copepoda parasitic on fishes as having no explicit meaning or further justification. Consequently, the term "chalimus" with its use currently restricted in the Caligidae to at most two instars in the life cycles of species of Lepeophtheirus, also becomes redundant. In our new understanding, both the chalimus and preadult stages should be referred to as the respective copepodid stages (II through V, in integrative terminology). The terminology for the caligid copepod life cycle thereby becomes consistent with that for the homologous stages of other podoplean copepods. We see no justification for keeping "chalimus" and "preadult" even as purely practical terms. To justify this reinterpretation, we comprehensively summarize and reinterpret the patterns of instar succession reported in previous studies on the ontogeny of caligid copepods, with special attention to the frontal filament. Key concepts are illustrated in diagrams. We conclude that, using the new integrative terminology, copepods of the family Caligidae have the following stages in their life cycles: nauplius I, nauplius II (both free-living), copepodid I (infective), copepodid II (chalimus 1), copepodid III (chalimus 2), copepodid IV (chalimus 3/preadult 1), copepodid V (chalimus 4/preadult 2), and adult (parasitic). With this admittedly polemical paper, we hope to spark a discussion about this terminological problem.

First step towards understanding the specific identity of fish muscle parasites of the genus Sarcotaces (Copepoda: Philichthyidae)-New species and first molecular ID in the genus.

Parasitic copepods of the genus Sarcotaces are remarkable. They occur in galls inside skeletal muscles of fishes and it is virtually impossible to overlook them, especially during fish handling and processing. The galls contain an intensively black ink-like substance that may stain fish tissue during filleting. They have a global distribution and until recently, seven nominal species had been described, each from a host representing a different fish family. Females of valid species are quite similar in their morphology, therefore the males are essential for species determination. Even though such a task may be difficult, because of the existing inadequate descriptions that additionally hinder correct identification. The aim of this study was to provide a detailed morphological and molecular characterization of the Sarcotaces specimens found in muscles of the common mora, Mora moro (Risso, 1810), most probably originating from southern Australia. The additional aim was to indicate possible mode and strategy of infection for the parasitic copepods of the genus Sarcotaces. The present paper not only describes and illustrates Sarcotaces izawai sp. nov. but also provides its molecular ID based on the COI gene. In addition to traditional light microscopy studies, Scanning Electron Microscopy (SEM) was also used. Males of Sarcotaces izawai sp. nov. differ from those of its congeners: in the host fish family, in the relative proportions of the caudal rami, and in the setal formula of the antennulae. For the first time in this genus, we described the maxillulae. We also discussed the possible mode and strategy of infection and redefined mesoparasitism.

An alien parasite affects local fauna-Confirmation of Sinergasilus major (Copepoda: Ergasilidae) switching hosts and infecting native Silurus glanis (Actinopterygii: Siluridae) in Hungary.

In 2016, an intense copepod infection was recorded from a reservoir in proximity to the Danube River in Hungary from visibly emaciated wels catfish, Silurus glanis. The parasite-induced pathology was described but parasite identity was not conclusive. Additional sample collections in 2017 and 2018 allowed for identification using both light and scanning electron microscopy, alongside genetic characterisation. The copepods were confirmed to be ergasilids, Sinergasilus major, distinctly different from any previous infection on silurids in Europe. This is the first record of this parasite from Hungary and the first host record from wels catfish.

Unseeded, spontaneous nucleation of spherulitic magnesium calcite.

Most of the sedimentary carbonates deposited in the marine environments are composed of calcium carbonate minerals with varying amounts of incorporated Mg2+. However, understanding how interactions of impurities with carbonate and their incorporation affect sediments behavior remains a challenge. Here, a new insight is obtained by monitoring solution composition, morphology, and electrokinetic potential of carbonate particles formed in a spontaneous unseeded batch precipitation experiment using electrochemical and scanning electron microscopy methods. The solid composition and growth rate are extracted from changes in the bulk composition and fitted to chemical affinity rate law, revealing that the precipitation pathway consists of second-order dissolution and first-order precipitation. The molecular dynamics simulations show that the lattice strain induced by randomly substituting Ca2+ by Mg2+ stabilizes spherical nanoparticles and reduces their surface area and volume. Combining kinetics and thermodynamics insight, we conclude that variation in the carbonate bulk and interfacial energies, along with the solution supersaturation, lead to the dissolution-precipitation transformation pathway from Mg-rich to Mg-poor carbonate phase that preserves spherulitic morphology. Our findings are relevant for long-standing questions of how impurities influence diagenesis of carbonate sediments and spherulitic carbonate particles' origin.

A new species of Brachiella (Copepoda, Siphonostomatoida, Lernaeopodidae) from Peninsular Malaysia, with relegation of two genera Charopinopsis and Eobrachiella to junior synonyms of Brachiella.

Both sexes of Brachiella malayensis n. sp. are described on the basis of specimens found in the nostrils of narrow-barred Spanish mackerel Scomberomorus commerson (Lacepède) collected off Besut, Malaysia. The female of this species closely resembles those of B. magna Kabata, 1968 and B. cybii Pillai, Prabha et Balaraman, 1982 but is distinguishable mainly by the body size and the proportions of the cephalosome, posterior processes and caudal rami. While examining the male, we noticed a systematic inconsistency in some lernaeopodid genera. The genus Brachiella Cuvier, 1830, represented by its type-species Brachiella thynni Cuvier, 1830, and two monotypic genera Charopinopsis Yamaguti, 1963 and Eobrachiella Ho et Do, 1984, represented by Charopinopsis quaternia (Wilson, 1935) and Eobrachiella elegans (Richiardi, 1880), respectively, share distinct synapomorphies in the embracing (vs. pinching) elongate male maxilliped and the female trunk with a pair of long, cylindrical ventroposterior processes (in addition to a pair of modified caudal rami), both of which are involved in their unique reproductive strategy. The latter two genera are herewith relegated to junior synonyms of Brachiella.

TITLE: Une nouvelle espèce de Brachiella (Copepoda, Siphonostomatoida, Lernaeopodidae) de Malaisie péninsulaire, avec relégation des deux genres Charopinopsis et Eobrachiella en synonymes juniors de Brachiella. ABSTRACT: Les deux sexes de Brachiella malayensis n. sp. sont décrits sur la base de spécimens trouvés dans les narines du Thazard rayé Scomberomorus commerson (Lacepède) collecté au large de Besut, en Malaisie. La femelle de cette espèce ressemble étroitement à celles de B. magna Kabata, 1968 et B. cybii Pillai, Prabha et Balaraman, 1982, mais se distingue principalement par la taille du corps et les proportions du céphalosome, les processus postérieurs et les rami caudaux. En examinant le mâle, nous avons remarqué une incohérence systématique dans certains genres de Lernaeopodidae. Le genre Brachiella Cuvier, 1830, représenté par son espèce-type Brachiella thynni Cuvier, 1830, et deux genres monotypiques Charopinopsis Yamaguti, 1963 et Eobrachiella Ho et Do, 1984, représentés par Charopinopsis quaternia (Wilson, 1935) et Eobrachiella elegans (Richiardi, 1880), respectivement, partagent des synapomorphies distinctes dans le maxillipède allongé (plutôt que pincé) et le tronc féminin avec une paire de longs processus cylindro-ventro-postérieurs (en plus d'une paire de rami caudaux modifiés), tous deux impliqués dans leur stratégie de reproduction unique. Les deux derniers genres sont ici relégués comme synonymes juniors de Brachiella.

A study on the mechanism of Ca2+ adsorption on TiO2 and Fe2O3 with the usage of calcium ion-selective electrode.

The paper presents the quantitative characterization of the solid/water interface applying both experimental and theoretical approaches for the system of TiO2 (mixture of anatase and rutile) and Fe2O3 (maghemite) with calcium ions in the pH function. The aim of the study was also to find a bonding mechanism between Ca2+ and metal oxides surface based on the calculations from the surface complexation modeling code (GEOSURF by Sahai and Sverjensky, 1998). In order to obtain adsorption edges, a calcium ion-selective electrode (Ca-ISE) was applied for determination of Ca2+ concentration in the suspensions. The results of both the Ca-ISE and parallel spectrophotometric determination were similar. The adsorption data showed that TiO2 exhibited stronger calcium binding than Fe2O3 at pH > 8. Using 2-pK TLM (triple-layer model) it was demonstrated that mechanism of the calcium adsorption onto the metal oxides surface involved different reactions. In the case of TiO2 it involved formation of >SO-_CaOH+ predominately on the ß-plane and at pH > 9 also on the 0-plane. In the case of Fe2O3 one could observe the existence of (>SO-)2_Ca2+ on the ß-plane in the whole studied pH range. At pH above 7 the tetranuclear complexes (>SOH)2(>SO-)2_Ca(OH)+ were found, and at pH > 9 also >SO-_CaOH+ could be observed. On the other hand, the analysis of the ζ-potential data suggested the absence of the tetra-species on the maghemite surface. The study indicated that the properly validated calcium ion-selective electrode can be an attractive instrument for monitoring Ca2+ adsorption on metal oxides in the environment.

Electrophoretic and potentiometric signatures of multistage CaCO3 nucleation.

HYPOTHESIS: Calcium carbonate nucleation is often a complex and multistep process that is difficult to follow in situ. The time-resolved electrochemical and electrophoretic methods can provide a new insight into the nucleation pathway. EXPERIMENTS: Here, we used a combination of speciation calculations with time-resolved electrophoretic and potentiometric methods to monitor calcium carbonate precipitation from a slightly supersaturated solution. FINDINGS: After an initial mixing period of three minutes in which metastable CaCO3 phases may have nucleated and subsequently dissolved due to locally-high supersaturations, bulk solution pH and Ca2+ concentrations stabilize before decreasing in tandem with the precipitation of a CaCO3 phase. After an hour, the precipitate is dominated by calcite that grows at the expense of dissolving vaterite. The time-dependent electrokinetic potential shows analogous signatures of multistage nucleation process: initial rapid changes in ζ-potential are followed by much slower equilibration starting about one hour after reagents are mixed. The changes in ζ-potential, solution pH, saturation indexes, and particle morphology are consistent with vaterite to calcite transformation via dissolution of the former and recrystallization of the latter. These findings highlight the potential use of ζ-potential measurements for monitoring polymorphic transformations of carbonate phases in-situ.

A case of persisting massive infection of Scomberomorus commerson, a commercially exploited scombrid fish, with Cybicola armatus (Copepoda: Siphonostomatoida: Pseudocycnidae).

During an extensive survey of fish parasites along the Malabar coast of India we observed exceptionally high or even massive infection of the narrow-barred Spanish mackerel, Scomberomorus commerson (Scombridae), with parasitic copepods Cybicola armatus. Such infection has not hitherto been reported. The copepods occurred on the gills of its host and the infection persisted for many years (the survey lasted from January 2010 to July 2014). The overall prevalence was very high (95%); out of a total of 981 fish studied, 933 were infected, and the maximum intensity reached 42. The highest rate of infection (prevalence 99.2%) was observed in medium sized fish (36.0-79.9 cm). We found this parasite only on S. commerson even though we examined 81 fish species, including five of the family Scombridae. Interestingly, the parasite exhibits strict site specificity and microhabitat preference. A significant proportion of them was seen attached to pseudobranchs rather than to main gill arches. Significantly, the body size of the parasite was positively correlated with that of the host fish. Our SEM micrographs contributed new facts to this copepod's morphology by illustrating for the first time the ventral part of its cephalothorax, illustrating the nature of attachment, and by finding a new structure - a premaxillary pad. We demonstrated the haematophagous nature of C. armatus by finding and documenting the host's blood cells in the parasite's intestine.

Parabrachiella jarai sp. nov. (Crustacea: Copepoda: Siphonostomatoida) parasitic on Sillago sihama (Actinopterygii: Perciformes: Sillaginidae).

The presently reported study provides a detailed morphological description of the female and the male of a new species of the genus Parabrachiella-Parabrachiella jarai sp. nov. The parasites were sampled from marine fish, silver sillago, Sillago sihama (Perciformes: Sillaginidae), captured in Malaysia in 1994 and Hong Kong in 1995. The new species bears some resemblance to Parabrachiella lata (Song et Chen, 1976) but differs from it in details of second antenna, mandible, and maxilliped. The genus Parabrachiella currently covers 67 species including those recently transferred from Neobrachiella Kabata, 1979. An amended generic diagnosis is proposed for Parabrachiella and Thysanote. Some members of Parabrachiella are herewith transferred to Thysanote and some Thysanote are now placed in Parabrachiella.

Comparative description of males of two species of Achtheres von Nordmann, 1832 (Copepoda: Siphonostomatoida: Lernaeopodidae) infecting zander and European perch.

Achtheres percarum von Nordmann, 1832 and Achtheres sandrae Gadd, 1901 (Lernaeopodidae) are common parasitic copepods infecting fishes in Eurasia. The former is specific to perch, Perca fluviatilis L., while the latter, to zander, Sander lucioperca (L.). Until recently these copepods have been regarded a single species. The present study was intended to analyse details of male morphology and provide their complete descriptions with differential diagnosis. Males of A. percarum and A. sandrae were collected from perch and zander at Lake Dabie (north-western Poland). The males of A. sandrae are larger than those of A. percarum. They also differ in proportions of the first antenna, mandibular denticulation, structure of the first maxilla, and the armament of caudal ramus. The reported differences in male morphology constitute a conclusive confirmation of the separate identity of the two species.

Determination of the parameters for the 1-pK triple-layer model of ion adsorption onto oxides from known parameter values for the 2-pK TLM.

Prior knowledge of the model parameters describing the metal oxide/simple electrolyte interface is frequently crucial to successful application of surface complexation modeling. On the basis of the parameter values for the 2-pK triple-layer model recently published by Sverjensky, the parameters for the 1-pK TLM were determined. This was done by fitting (using the 1-pK model) the proton surface charge and ion adsorption isotherms generated by the 2-pK TLM. It was assumed that inner-layer capacitance was the same for both models. A strong correlation was found between ion adsorption constants of different electrolytes on the same oxide predicted by both models. Additionally, the 1-pK and 2-pK models predict different electrokinetic potentials in spite of very similar values of calculated surface charge and ion adsorption isotherms when the same value of outer-layer capacitance is assumed. Because the value of outer-layer capacitance practically does not influence surface charge and electrolyte adsorption isotherms, it can be treated as a freely adjusted parameter, the value of which can be estimated if we have measured the electrokinetic potential.

How to distinguish energetic surface heterogeneity from electrostatic interactions in the case of hydrogen ion adsorption from solution onto oxides.

It was shown that the adsorption of uncharged particles onto energetically heterogeneous surfaces with Gaussian-like distribution of adsorption energy can be described by the same adsorption isotherm as the adsorption of hydrogen ions from solution onto homogeneous oxide surfaces with surface potentials given by a quasi-Nernst formula. It exemplifies that the separation of electrostatic from energetic factors in the case of ion adsorption onto heterogeneous oxide surfaces is very difficult. Nevertheless, application of calorimetric data for proton adsorption makes it possible to estimate both factors.

Application of the statistical rate theory of interfacial transport to interpret the relaxation time of proton adsorption from solution onto oxides.

A new way to analyze the rate of hydrogen ion adsorption from solution onto oxides was described. The statistical rate theory of interfacial transport (SRT) was applied to interpret relaxation time of ion adsorption. The new procedure for determination of rate constants of surface reaction was compared with the classical theory of activated adsorption and desorption (TAAD). It was found that for adsorption of uncharged species, both models give the same result, but for ion adsorption, their predictions differ considerably. Influence of surface potential and total concentration of adsorption sites on calculated rate constants was also discussed.

Factors affecting the susceptibility of sea lice infection in Atlantic salmon.

Parasitic copepods of the family Caligidae, otherwise known as sea lice (Lepeophtheirus salmonis and Caligus elongatus), are responsible for serious disease problems in salmon aquaculture. This mini-review examines the host factors that are affecting the susceptibility of sea lice infection in salmon; in particular, host species, environment, host stress levels, and host immunocompetency. In order to develop more effective methods to control sea lice infection, these factors should be taken into account, along with other factors such as sea lice life cycle and fecundity as well as salmon husbandry methods.

A comparative study on the parasite fauna of perch, Perca fluviatilis L., collected from a freshwater coastal lake, brackish-water Baltic Sea, and the interconnecting canal.

BACKGROUND: Parasitological surveys of freshwater fishes rarely include comparisons between two ecologically different bodies of water. Such studies might help to understand processes of establishment of parasite faunas in estuary areas. The results obtained could also provide useful tools for discriminating various fish populations based on the composition of their parasite faunas. The present authors attempted to study such data from Resko Lake-a freshwater coastal lagoon (6 km2 surface area), and the adjacent areas of the Baltic Sea. Resko Lake, located 12 km west of the city of Kolobrzeg, is shallow (1.5 m) and is connected to the sea through a small canal (1.3 km long, 30 m wide). MATERIAL AND METHODS: The material was collected from April 1969 and July 1970. A total of 159 perch were collected, in this number 104 fish from the lake, 43 from the sea, and 12 from the canal. RESULTS: A total of 32 parasite species were recovered from the fish necropsied. The parasites represented 7 higher taxa: Protozoa (3 species), Cestoda (4), Digenea (13), Nematoda (5), Acanthocephala (3), Mollusca (1), and Crustacea (3). The parasite fauna of perch from the sea was definitely more abundant (31 species) compared to that of the lake (21), and the canal (12 species). Infection parameters of 13 parasite species demonstrated significant differences between the locations studied. The infection level of 6 parasite species was significantly higher in perch from the sea: Bothriocephalus scorpii, Ligula sp., Brachyphallus crenatus, Camallanus truncatus, Hysterothylacium aduncum, and Echinorhynchus gadi. On the other hand, infection levels of 7 other species were higher at the lake: Triaenophorus nodulosus, Bucephalus polymorphus, Azygia lucii, Tylodelphys clavata, Camallanus lacustris, Acanthocephalus lucii, and Achtheres percarum. The infection parameters of the fish from canal were similar to those from the lake. Interesting observations were made on the seasonality of certain parasites of both lake- and Baltic perch. The presently observed differences between parasite faunas of the fish from ecologically different adjacent estuarine locations are certainly caused by diversified environmental conditions that affected the processes of formation of the parasite communities there. Among important factors that could affect compositions of the parasite faunas could have been: availability of the intermediate hosts, exchange of waters (Baltic water influxes to the lake), fish migrations (spawning), and finally the separate identity of the two fish stocks studied.

The identity of Limnoncaea diuncata Kokubo, 1914 (Copepoda: Poecilostomatoida) from Hokkaido, Japan, with the relegation of Diergasilus Do, 1981 to a junior synonym of Thersitina Norman, 1905.

Both sexes of an ergasilid copepod, Limnoncaea diuncata Kokubo, 1914, are redescribed based on planktonic specimens collected from the type-locality in Hokkaido, Japan. Comparison of this species with Thersitina gasterostei (Pagenstecher, 1861) revealed that they are conspecific. Another ergasilid genus with two claws on the antenna, Diergasilus Do, 1981, is relegated to synonymy with Thersitina Norman, 1905. The diagnosis of Thersitina is amended.

Redescription of the fish parasite Lernanthropus polynemi Richiardi, 1881 (Copepoda: Siphonostomatoida) and relegation of two congeners to synonymy.

Lernanthropus polynemi Richiardi, 1881 is described, for the first time since its original discovery, based on the type-material found in the Museum für Naturkunde in Berlin, Germany. Morphological features of this parasite, which infects the commercially-caught fish Eleutheronema tetradactylum (Shaw), are described and illustrated, including those of the male, which is described for the first time. The types of another species from the same host, L. lappaceus Wilson, 1912, and deposited in the National Museum of Natural History in Washington DC, are also examined based on the type-specimens. The types of a third congener, L. trifoliatus Basset-Smith, 1898, also from the same host, are not available, but the original illustrations are studied. It is considered that the three nominal species described from E. tetradactylum represent a single taxon, and that L. lappaceus and L. trifoliatus be relegated to synonymy with L. polynemi.

1pK and 2pK protonation models in the theoretical description of simple ion adsorption at the oxide/electrolyte interface: the analysis of temperature dependence of potentiometric titration curves.

Two models of oxide surface charging (1pK and 2pK) were used to describe the potentiometric titration curves measured by Blesa et al. (J. Colloid Interface Sci.101, 410 (1984)) at three temperatures and at three concentrations of electrolyte. Rudzinski et al. (Langmuir13, 483 (1997)) have applied the 2pK Triple Layer Model to analyze the above system earlier. Two calculation procedures based on the 1pK Basic Stern Model were developed to described Blesa's data. Since the experimental curves have the CIP (common intersection point) it was assumed that heat of electrolyte ion adsorption was equal to zero. We assumed two different values of the double layer innermost capacitance on both sides of PZC (point of zero charge), which was followed from asymmetry of surface charge curves relative to PZC. Moreover, it was necessary to take into consideration the dependence of capacitance on ionic strength and temperature. The quality of fit given by two models was comparable. Since the 1pK BSM is simpler than the 2pK TLM and includes not so many best-fit parameters it seems to be a better choice in this case. Discussion of the results obtained by other authors concerning the subject under consideration is also presented.

Parasite fauna of selected fish species of Lake Miedwie.

A total of 136 fishes, representing 9 species (perch, Perca fluviatilis L.; pike, Esox lucius L.; European eel, Anguilla anguilla (L.); common bream, Abramis brama (L.); roach, Rutilus rutilus (L.); tench Tinca tinca (L.); European whitefish, Coregonus lavaretus (L.); vendace, Coregonus albula (L.); and zander, Sander lucioperca (L.)), from Lake Miedwie were studied within 1997-1999. The necropsies yielded 41 parasite species (taxa). The most diversified were parasite faunas of pike (19 parasite species) and perch (16 species). The parasites found represented 13 higher taxa: Monera, Fungi, Protista, Myxozoa, Monogenea, Cestoda, Digenea, Nematoda, Acanthocephala, Branchiura, Copepoda, Mollusca, and Acarina. The parasites affecting fishes of Lake Miedwie exhibited diversified host-specificity. The most fish species were infected by metacercariae of Diplostomum spp. (8 fish species) and Tylodelphys clavata (7). Three fish species harboured: Ichthyocotylurus platycephalus, Ergasilus sieboldi, and glochidia Unionidae gen. sp. while Dermocystidium sp., Trichodinella epizootica, Henneguya psorospermica, Triaenophorus nodulosus, Posthodiplostomum cuticula, and Camallanus lacustris parasitised two host species. The remaining parasites were found in single fish species.