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Notes: SUMMARY 1. A study of twenty-nine temporary pools located in a nature reserve in Central Italy was carried out for two successive years (1982–83 and 1983–84) to determine the distribution and life cycles of the cladocerans they contained.2. The pools followed a typical autumnal cycle, filling up in early autumn and drying up in late spring. They differed in morphology (size, depth, type of soil) and in the length of the wet phase.3. Nineteen cladoceran species were found. A few of these are early species, appearing at the beginning of the wet phase, whereas others appear much later in spring and these populations persist for a shorter time.4. Species distributions did not show any clear correlation with the ponds’morphological features, and the life cycles of individual species were similar in all ponds. Thus populations did not adapt life history patterns to match conditions in particular ponds.

Notes: This study presents a cytogenetic analysis of the genus Dicentrarchus, represented by two species, D. labrax and D. punctatus. The karyotypes are very similar, even after staining with different techniques. Both species show 48 subtelocentric and acrocentric chromosomes, gradually decreasing in size. One pair of small size chromosomes has heteropycnotic and heteromorphtc short arms of longer size. These short arms are C- and Ag-positive, i.e. nucleolar organizer regions, NORs, are located there. Constitutive heterochromatin is also evident as a subcentromeric band on the long arms of a large chromosome pair. CMA3-staining confirms the location and the heteromorphism of NORs. DAPI and quinacrine produce homogeneous staining of chromosomes. A review of cytogenetic studies on ‘serranid’ species is also presented.

Notes: Morphological changes in the oesophageal epithelium of Oreochromis mossambicus, O. niloticus, and O. mossambicus x O. niloticus hybrids were studied during adaptation to sea water. In fresh water, the epithelium is stratified and rich with mucous cells. In salt water, modifications occur in the oesophagus of O. mossambicus and of the hybrid: mucosa folds are more vascularized and covered with a monolayered epithelium, alternating with a multilayered one. The oesophagus of O. niloticus does not seem to be affected by salinity but this species survives only for brief periods in sea water. These observations underline the close relationship between the oesophagus morphology and salinity tolerance in tilapias.

Notes: Multivariate examination of partial warps allowed the description of shape differences characterizing each of 10 populations of Mugil cephalus. Patterns of morphometric distances (overall, uniform and non-uniform) among samples suggested that morphometry in part reflected the geographic origin of the samples. However, comparisons with allozymes and mtDNA provided no exhaustive evidence for a pure phylogenetic cause for the observed patterns of geographic Variation.

Notes: Mitochondrial (ml) DNA genotypes of grey mullet (Mugil cephalus) from ocean basins around the world were analysed to estimate the amount of genetic differentiation in this cosmopolitan but mostly coastally-restricted species. Extensive genetic diversity was observed. Among 115 specimens from nine locales, 26 different haplotypes were detected using a battery of 13 restriction endonucleases. In phenetic analyses, these haplotypes grouped into seven distinct clusters whose members were in almost perfect accord with the geographic sources of the samples. Thus contemporary gene flow between the widespread collection locales must be absent or nearly so. Results contrast with the relative uniformity in mtDNA composition previously reported for populations of some circumglobally distributed pelagic fishes, and demonstrate that certain marine fishes with cosmopolitan distributions can exhibit pronounced population genetic structure even in the face of morphological conservatism.

Notes: The thick lipped mullet, Chelon labrosus, was induced to spawn by the injection of human gonadotropin hormone. Eggs were fertilized naturally and larvae were reared at different conditions, in hatchery tanks and outdoor earthen ponds, in order to compare their growth and try to reduce production costs. Food consisted of rotifers and brine shrimp nauplii at first, then of minced fresh fish and commercial fish food. Larval survival reached maxima of 41.9 % at the age of 20 days and 33.4 % at the age of 58 days. The successful artificial reproduction of the thick lipped mullet could have potential for meeting the demands of fry for the Italian aquaculture and the mass propagation of fry could have wide applications in developing countries.〈section xml:id="abs1-2"〉〈title type="main"〉ZusammenfassungKünstliche Vermehrung and Larvenaufzucht der Dicklippigen Meeräsche (Chelon labrosus)Die Dicklippige Meeräsche (Chelon labrosus) wurde durch Injektion von menschlichem Gonadotropin zum Ablaicnen gebracht. Die Eier wurden natürlich befruchtet und unter verschiedenen Bedingungen in Aquarien und in Freiluftteichen aufgezogen, um Abwuchs und Produktionskosten zu vergleichen. Als Futter wurden zuerst Rotatorien und Salinekrebse, dann zerkleinerter Frischfisch und Fertigfutter verwendet. Die überlebensrate war maximal 41.9% bei 20 Tage alten bzw. 33.4% bei 58 Tage alten Larven. Die erfolgreiche künstliche Reproduktion von Dicklippigen Meeräschen ist vor allem im Hinblick auf die Nachfrage der italienischen Aquakultur von Bedeutung und könnte auch für die sich entwickelnde Aquakultur in einigen Ländern der dritten Welt wichtig werden.〈section xml:id="abs1-3"〉〈title type="main"〉RésuméReproduction artificielle et élevage d'alevins du muge (Chelon labrosus)Le muge Chelon labrosus a été traité avec des homones gonadotropiques humaines pour induire la ponte. Les oeufs ont été fécondés naturellement, et les larves élevées dans des conditions différentes, à l'intérieur de l'écloserie et dans des bassins en terre, afin de comparer leur croissance et essayer de réduire les coûts de production. L'alimentation comprenait rotifères et larves d'artémia au début, suivis de poisson frais broyé et aliment sec commercial. Le taux de survie des larves a atteint des maxima de 41.9 % a 20 jours et 33.4 % a 58 jours. Ces essais de reproduction artificielle pourraient satisfaire la demande en alevin de cette espèce de muge pour la pisciculture italienne, et leur sevrage à basse technologie avoir maintes applications dans l'aquaculture des Pays en Voie de Développement.

Notes: Abstract Allozyme electrophoresis was used to compare the genetic divergence of global populations of Mugil cephalus Linnaeus, 1758 and two congeneric [M.␣curema Cuvier & Valenciennes, 1836; M. gyrans (Jordan & Gilbert, 1885)] and two more distantly related [Liza ramada (Risso, 1826); Xenomugil thoburni (Jordan & Starks, 1896)] species on the basis of 18 enzyme loci. The amount of genetic divergence among the species examined is in agreement with their present systematic status, the differences being larger among non-congeneric species than among species of the same genus. Intraspecific genetic distances in M. cephalus (average Nei's D= 0.154), although higher than those reported for conspecific populations of fish, appear to be small when compared to the interspecific values among mugilid species (0.821 ≤ Nei's D ≤ 1.744). Phylogenetic trees obtained by genetic distance methods and discrete character parsimony analysis were of similar topology, except for the relationships within the genus Mugil and for the arrangement of M. cephalus populations.

Notes: Abstract The striped mullet, Mugil cephalus Linnaeus, 1758, is one of the few species of marine shore fish with a worldwide circumtropical distribution. Because of this distribution and the dependency of M. cephalus on coastal waters during various phases of its life cycle, as well as nearshore living habits, questions have been raised regarding levels of genetic divergence and gene flow among transoceanic populations. To cast more light on this, allozyme variation at 27 presumptive gene loci was investigated in ten globally diverse populations. The observed heterozygosity ranged from 0.018 (Hawaii) to 0.081 (Florida), averaging 0.050. The proportion of polymorphic loci showed a similar trend. Several populations were characterised by fixed allelic differences. Estimated gene diversities were very high, the allele frequency variation among populations was found to be 68%; genetic distances reached 0.242, with an average of 0.117. Estimated rates of gene flow were high among Mediterranean populations (Nm = 7.26), and between Mediterranean and East Atlantic populations (Nm= 2.86), but extremely low between non-contiguous populations within the Indian, Pacific and Atlantic Oceans, where Nm ranged from 0.03 to 0.05.