Habitat segregation and cryptic adaptation of species of Periophthalmus (Gobioidei: Gobiidae).

A study was conducted on the habitat distribution of four sympatric species of Periophthalmus (the silver-lined mudskipper Periophthalmus argentilineatus, the slender mudskipper Periophthalmus gracilis, the kalolo mudskipper Periophthalmus kalolo and the Malacca mudskipper Periophthalmus malaccensis) from northern Sulawesi. Molecular phylogenetic reconstructions based on one mtDNA marker (16S) were used to validate the morphological taxa, identifying five molecular clades. Periophthalmus argentilineatus includes two molecular species, which are named Periophthalmus argentilineatus clades F and K. Multivariate direct gradient analysis show that these species form three distinct ecological guilds, with the two molecular species occurring in different guilds. Periophthalmus clade F is ecologically eurytypic; Periophthalmus clade K and P. kalolo are prevalent in ecosystems isolated by strong oceanic currents and at shorter distances from the sea; P. gracilis plus P. malaccensis are prevalent in ecosystems connected by shallow coastal waters, in vegetated habitats at larger distances from the sea. This indicates for the first time that mudskipper species exhibit a range of adaptations to semiterrestrialism not only within genera, but even within morphospecies, delineating a much more complex adaptive scenario than previously assumed.

Spatial and seasonal variations in the water quality of the Amu Darya River (Central Asia).

Although the use of the water resources in Uzbekistan is strongly limited by their quality, it has to be noted that there is a lack of information and data within the international scientific literature with regard to the water chemical characteristics of the Amu Darya River, one of the main water resources in Central Asia. To add to such knowledge, this paper examines the spatial and temporal variation of the water quality of the Amu Darya River in order to assess its degree of degradation and the main causal factors. The functional relationships of the pollutants with respect to the flow regime are investigated. Finally an "opportune temporal window" for water withdrawal for filling the reservoirs, in relation to human consumption, will be indicated. The high salinization levels of the waters are mainly due to the presence of sulphates and chlorine. At the up-stream site salinity, although presenting elevated concentrations, does not exceed palatability levels; after the 450 km point the opportune temporal window for water withdrawal with acceptable salinity values is reduced to the period from May to September. Two main driving forces govern the temporal variation of the salinity of the Amu Darya water: a low drainage density of the area which limits the salt loads induced by the natural runoff processes, and snow and glacier melting in the upper catchment area which promotes dilution of the dissolved salts during the high-flow period. During low-flow periods salinity is strongly influenced by the return of waters used for land washing and irrigation.

Phylogeography of the threatened crayfish (genus Austropotamobius) in Italy: implications for its taxonomy and conservation.

A nucleotide sequence analysis of a portion of the mitochondrial large ribosomal subunit was performed to define the phylogeography of the threatened crayfish Austropotamobius (Decapoda; Astacidae) in Italy. We collected 61 specimens from 31 localities across the Italian peninsula. For the phylogenetic inference, we combined the 61 Austropotamobius spp sequences obtained from this study with 18 sequences deposited in GenBank and corresponding to Italian, French, Irish, Swiss, and Slovenian locations. Among the analysed sequences, 34 distinct haplotypes were detected. Our results confirmed the presence of both A. pallipes and A. italicus in the Italian peninsula and the existence within the latter species of a strong intraspecific genetic variation, due to the occurrence of four subspecies with a well-defined geographic distribution. From a conservation viewpoint, Italy, with its high haplotype variability, may be considered a 'hot spot' for the genetic diversity of the European native crayfish Austropotamobius. We suggest that re-introduction programs should be conducted with extreme caution in Italy, since not only the two Austropotamobius species but also the four A. italicus subspecies are genetically and taxonomically separate units and require independent conservation plans.

New records of alien monogeneans from Lepomis gibbosus and Silurus glanis in Italy.

The first geographical records of five alien monogeneans for Italy is reported. Four species have been detected from Lepomis gibbosus (Linnaeus, 1758): Actinocleidus recurvatus Mizelle et Donahue, 1944, Actinocleidus oculatus (Mueller, 1934), Urocleidus similis (Mueller, 1936) and Urocleidus dispar (Mueller, 1936); one species from Silurus glanis Linnaeus, 1758: Thaparocleidus vistulensis (Siwak, 1932) n. comb.

Occurrence of Monogenea in Italian freshwater fish (Po river basin).

Sixteen Monogenean species were found on the skin and gills of 10 different fish species collected from north Italian water bodies. Cleidodiscus pricei from Ictalurus melas; Dactylogyrus alatus from Alburnus alburnus; D. anchoratus, D. formosus and D. vastator from Carassius carassius; D. difformis from Scardinius erythrophthalmus; D. rutili from Rutilus aula; D. tincae and Gyrodactylus gasterostei from Tinca tinca; D. ergensi from Leuciscus cephalus and Telestes muticellus; D. vistulae and Paradiplozoon rutili from Leuciscus cephalus; D. extensus and G. katharineri from Cyprinus carpio; G. lucii and Tetraonchus monenteron from Esox lucius. All species are new records for Italy with the exception of D. difformis, D. ergensi, D. vistulae and T. monenteron.

Long-term assessment of insecticides treatments in West Africa: aquatic entomofauna.

For the control of the Onchocerca volvulus vector in West Africa, up to 18,000 km of rivers from 1975 and up to 50,000 km from 1989 had been partly sprayed weekly with insecticides as part of the Onchocerciasis Control Programme (OCP). To evaluate the possible short-term and long-term effects of the application of insecticides on the non-target fauna, an aquatic monitoring programme was set up during the initial phase of the programme. By analysing the invertebrate data, which were collected using various sampling strategies from four different countries between 1977 and 1996, this paper evaluates the long-term changes of the invertebrate populations with respect to their taxonomic composition as well as their trophic structures. The discussed results of the applied numerical analysis strategy suggest that neither the taxonomic nor the trophic structures are greatly altered from the range of biological, flow-related variation that normally occurs in the studied river systems. This allows us to conclude that the biological variation found here is ecologically acceptable.

Analysis of the effects of rotational larviciding on aquatic fauna of two Guinean rivers: the case of permethrin.

Within the Onchocerciasis Control Programme about 50,000 km of west African rivers have been regularly sprayed with larvicides to control the vector of dermal filariasis caused by Onchocerca volvulus. Since the beginning of the programme invertebrates and fish data were collected to monitor adverse effects on non-target organisms. The regular series of biological and hydrological data collected in two Guinean rivers were analysed to evaluate the effects of rotational larviciding with particular attention to permethrin, as preliminary acute toxicology tests and semi-field experiments suggest it has stronger effects on non-target fauna in respect to other larvicides. Invertebrates and fish variations in biomass and species richness are seasonal and flow-related and the results presented here do not support any evidence of specific effects of permethrin application on the biological targets monitored. Larvicide applications influence community structures, putting pressure on some taxonomic groups, causing, for example, the rarefaction of some taxa. In spite of the above results, the scarcity of some invertebrate systematic units does not result in a significant reduction of total invertebrate density because of the corresponding increase in other systematic units. In nature the studied aquatic communities would rarely be in equilibrium because of frequent natural stresses, such as drought and spate events, the biological variations discussed are to be considered ecologically acceptable.

High concentrations of adrenergic antagonists prolong sciatic nerve blockade by tetrodotoxin.

BACKGROUND: Millimolar-range concentrations of some adrenergic antagonists have been shown to have local anesthetic-like properties, and to stimulate GTPase activity in vitro. In this report, we investigate whether these agents can potentiate the effect of tetrodotoxin (TTX) and bupivacaine, a conventional local anesthetic, and whether GTPase activation plays a role. METHODS: Rats received sciatic nerve blockade with tetrodotoxin or bupivacaine co-injected with adrenergic antagonists and/or agonists, or pertussis toxin. Thermal nociceptive blockade was quantified with modified hotplate testing. RESULTS: Nerve block from TTX alone lasted 153 (99-223) min (median and 25th and 75th percentiles). Co-injection with 20 mM phentolamine, propranolol, and yohimbine prolonged TTX block to 856 (765-862), 486 (444-510), and 465 (413-495) min respectively (P<0.005 in all cases, compared to TTX alone). Micromolar concentrations of adrenergic antagonists (which inhibited the prolongation of TTX block by epinephrine) did not prolong TTX block. Injection of adrenergic antagonists alone did not produce specific nerve block. They did not prolong TTX block when injected at a remote subcutaneous site. Prolongation of TTX block by phentolamine was not inhibited by co-injection with pertussis toxin. Adrenergic antagonists did not prolong bupivacaine block. CONCLUSIONS: High concentrations of adrenergic antagonists markedly prolonged TTX block, but not bupivacaine block. This locally mediated action does not appear to be adrenergic-receptor-specific, or mediated by GTPase activation.

New geographical records of parasitic nematodes from Bufo bufo in Italy.

To provide information on parasites of Bufo bufo (toad), eyes, skin, lungs, gut and urinary bladder of individuals collected near lakes Endine and Segrino (Northern Italy) from March to April 1999 were recorded in laboratory. A total of five nematode species were classified: Oswaldocruzia filiformis, Oxysomatium brevicaudatum, Cosmocerca ornata, Neyraplectana schneideri were found in the intestine and rectum and Rhabdias sphaerocephala in the lungs. Of these species, the last three are new geographical records for Italy.

Distribution of Anisakis simplex in fish caught in the Ligurian Sea.

A total of 822 individuals of 5 fish species were sampled in the western coastal area of the Mediterranean Sea and examined for the presence of Anisakis simplex larvae in the body cavity, muscle, and viscera. A. simplex mean intensity (mI) and prevalence (Pr) values were very high in the common scad (Trachurus trachurus; Pr 80-100%, mI 19.3-36.8) and the blue scad (T. picturatus; Pr 80-100%, mI 18.2-70.7), moderate in the blue whiting (Micromesistius poutassou), and low in the red mullet (Mullus barbatus) and the striped mullet (M. surmuletus). The larval burden was strongly related to host length in the common and blue scad.

Long-term quantitative ecological assessment of insecticides treatments in four African rivers: a methodological approach.

In West Africa different insecticides had been applied in selected river areas for the reduction of the blackfly populations vectors of Onchocerca volvulus, a parasite causing blindness. To evaluate the possible long term effects of the larvicides on the non target fauna an aquatic monitoring programme has been up from the initial phase of the project. Addressing the attention to the invertebrates data collected in four countries during a maximum period ranging from 1977 to 1996, this paper shows and discusses the data analysis strategy for the measure and interpretation of the biological variation. In particular the application of quantitative ecological analysis methods: Principal Component Analysis, rank abundance models and the community diversity indexes, is critically discussed and comments are given to the ecological interpretation of the results.

Heavy metals concentrations in acanthocephalans parasites compared to their fish host.

A number of authors have demonstrated that heavy metal concentrations in intestinal Helminths are higher than those found in the tissues of their final hosts. In this work, Pb and Cr concentrations in the Acanthocephalan Acanthocephalus anguillae were measured by means of electrothermal atomic absorption spectrometry. The metal concentrations measured in the whole body of Acanthocephalans were compared to those in the liver of their fish hosts (Leuciscus cephalus) sampled in the Lambro river (Northern Italy). The results show higher concentrations of Pb and Cr in the parasites, respectively approximately 200 times and approximately 60 times higher than that of the host liver. These results corroborate the usefulness of parasites in the monitoring of biologically available metal concentrations in aquatic ecosystems that are non severely polluted.

Populations of acanthocephalus anguillaePomphorhynchus laevis in rivers with different pollution levels

The distribution of two acanthocephalan species (Pomphorhynchus laevisAcanthocephalus anguillae) in the chub (Leuciscus cephalus) was studied in four river reaches characterized by different levels of pollution: the River Ticino near Abbiategrasso (unpolluted), the Naviglio Grande Canal, in Milano (slightly polluted), the River Lambro near Merone village (polluted) and the River Lambro near Monza (severely polluted).Pomphorhynchus laevis was restricted to the unpolluted and the slightly polluted sites, while the intensity of A. anguillae increased proportionally to water pollution. These differences were partially explained by the variation in abundance of their intermediate hosts (Echinogammarus stammeri for P. laevisAsellus aquaticus for A. anguillae). Data on the occurrence of P. laevis and A. anguillae showed a significant negative binomial frequency distribution, suggesting their tendency to be aggregated within the host populations of L. cephalus.