Structure et composition chimique élémentaire de quelques coquilles d'œufs de dinosaures du Jurassique et du Crétacé d'Amérique du Nord

Structure and chemical composition of some dinosaur eggshells from Jurassic and Cretaceous of North America. Microstructural analyses of some dinosaur eggshells from Jurassic and Cretaceous sites of North America show a large variability in the state of preservation. Outer and inner surfaces are often hidden by secondary deposits, and the tubercles or ridges and spherolites are not visible. Chemical analyses show that some fragments are strongly enriched in Si. There is a good correlation between the preservation of the structures and the chemical contents. Diagenetic processes are different from those described in the samples from Southern France.     

Le genre d'échinide s dans les dans les localités du Pliocène et du Pléistocène d'Emilie (Italie du Nord)

The study of well-preserved Pliocene and Pleistocene s from Emi from Emilia is used to analyze the morphological variations of Mediterranean populations, to depict the relationship between fasciole shape and other morphological characteristics and to describe previously unpublished pedicellar valves. These new data allow to be two species distinguished: s (Müller) a (Müller) and s Pomel; six s Pomel; six species closely related to s are synonymi are synonymized: s and it and s Pomel, i Pomel, i and itS. and s Checchia-R Checchia-Rispoli, x Simonelli a Simonelli and the recent species from Mediterranean, s Mortensen Mortensen. s can be disti can be distinguished from s by its hear by its heart-shaped subanal fasciole, when the s one is reni one is reniform. Moreover, the frontal groove of s is deeper, t is deeper, the primary tubercles of the interambulacra 1 and 4 are less numerous, the petals are shorter and narrower, the labrum is shorter. As far as pedicellariae are concerned, the jags of the large tridentate ones are stronger and the base of the globiferous ones is bigger. Palaeoecological observations on outcrops of the Stirone River, in Parme region, show similar environmental affinities between fossil populations and recent populations from Mediterranean. The s fossils fossils seem to be preserved within their life environment, that is to say in shore sandy substrates.

Résumé

L'étude d'un groupe de spécimens bien conservés appartenant au genre Spatangus, trouvés, dans des localités pliocènes et pléistocènes de l'Émilie, permet d'exposer l'étendue de la variation dans les populations fossiles méditerranéennes, de rechercher les relations entre la forme du fasciole sous-anal et les autres caractères morphologiques et de décrire les valves des pédicellaires, qui n'étaient pas connues jusqu'alors. Ces nouvelles données conduisent à reconnaître deux espèces différentes : s (Müller) e (Müller) et s Pomel ; six Pomel ; six espèces voisines de s doivent prob doivent probablement tomber en synonymie : s et itS et s Pomel, i Pomel, i et itS. a et s Checchia-R Checchia-Rispoli, x Simonelli e Simonelli et l'espèce vivant actuellement en Méditerranée, s Mortensen Mortensen. Des observations paléoécologiques sur un échantillon fossile récolté sur les bords de la rivière Stirone près de Parme montrent des affinités bionomiques semblables chez les populations fossiles et celles vivant en Méditerranée.     

Productivité comparée des deux étangs situés à proximité du lac Saint-Jean,au Québec

The Comparative Productivity of Two Ponds in the Vicinity of Lake St-John, Québec In 1980 and 1981, the productivity of two ponds near Lake St. John were evaluated. One, the pond of Desbiens, did not communicate with Lake St. John and the other, the pond of St-Gédéon, was connected to the lake. The aim of this study was to evaluate the contribution that a pond could make to the increase in productivity of Lake St. John which is a reservoir. The pond of Desbiens is more productive than Lake St. John but two to three times less than the pond of St-Gédéon. The pond of Desbiens shows an advanced degree of eutrophication whereas the pond of St-Gédéon is similar to the northern lakes by its physico-chemistry, zooplankton, sediments and benthic fauna. If we want to create artificial ponds, for a better productivity of reservoirs, it is important that they be connected to each other.     

Les protéines non hémoglobiniques érythrocytaires du poulet : Etude immunologique de leur évolution au cours du développement

By use of Laurell's method, the quantitative evolution of three antigenic components of chicken erythrocyte non-hemoglobin proteins has been followed during the course of development. One of the constituents has been characterized as the yellow component previously described and its evolution has been confirmed. The significance of these modifications is discussed.     

Toxicité du cuivre vis à vis de Microcystis aeruginosa Kütz. et d'Aphanizomenon flos-aquae Ralfs

We studied the toxicity of copper on Microcystis aeruginosa and Aphanizomenon flos-aquae. The toxicity phenomena can be described by the survival dose relationship which allows us to define the three parameters: threshold concentration (Cs), sensitivity (k) and a NL. 50%. The latter corresponds to the copper concentration which reduces the number of cells at the end of the exponential phase by 50%. A. flos-aquae is very clearly less tolerant than M. aeruginosa to copper. Viable cell counts based on electron transport activity showed that M. aeruginosa cultures can detoxify copper.     

Étude des principaux facteurs influençant l‘émission d'attractifs sexuels synthétiques à partir de diffuseurs en caoutchouc et en plastique

Deux types de diffuseurs en caoutchouc (Michelin) et en plastique polystratifié (Hercon^®) sont testés en laboratoire pour étudier quelques aspects des phénomènes de diffusion. Trois composantes phéromonales, le Z9-12: Ac, le 12: Ac et le Z9-14: Ac imprégnées dans ces différents supports servent à détermineer le rôle joué par la longueur de la chaîne de la molécule et la présence de doubles liaisons sur la vitesse de diffusion. L'influence de la température, de la vitesse du vent et de l'humidité est déterminée en cellules climatisées.Parmi les facteurs relatifs à la structure chimique, l'influence de la longueur de la chaîne est prédominante par rapport à la présence d'une double liaison. Parmi les facteurs climatiques, le vent agit plus que la température sur la diffusion, alors que l'humidité paraît secondaire.     

Effet de l'enrichissement continu en nitrates sur les populations de Diatomées isolées à l'aide d'enceintes expérimentales placées dans un étang oligotrophe

The influence of nitrates (NH₄NO₃ KNO₃ and Ca(NO₃₎₂) on Diatom populations has been studied. These populations were isolated by enclosures with transparent walls, without bottom or lid, placed in an oligotrophic pond. The addition of NH₄NO₃ generally resulted in a decrease in the number of Diatoms and the disappearance of some species. The addition of KNO₃ and Ca(NO₃₎₂ was followed, during some periods, by a very important increase of Achnanthes minutissima, Fragilaria construens and Gomphonema parvulum.     

Armes de chasse dans l’Épipaléolithique du Caucase du Nord

The article is devoted to the traceological study of points and geometric microliths that are characteristic of the Epipaleolithic sites of the northwestern Caucasus and the Elbrus region. The regularities between the type of stone tools and their functional use are analyzed. Composite hunting weapons were effectively used in hunting a variety of ungulate herd animals. The composition of faunal assemblages largely depended of climatic and landscape conditions of the sites in different periods of the Late Glacial period: from the Oldest Dryas to the Pleistocene–Holocene transition. The proximity of lithic industries within a vast region in the North Caucasus, similar shapes of projectiles and lithic inserts into composite hunting weapons could be associated with active human movements, which are confirmed by the transportation of obsidian from the Elbrus region to the northwestern Caucasus and the transportation of high-quality flint from the west to the Elbrus region in the north-central Caucasus.     

Groupement et ordination appliqués à l''étude de la répartition de l''épifaune benthique de l''estuaire maritime et du Golfe du Saint-Laurent

Forty-seven navigation buoys were used to collect quantitative samples of epibenthic fauna in the Lower Estuary and Gulf of St. Lawrence. Stations, as described by their sessile species and biomass composition, were grouped using multivariate analysis. A Gower similarity index, modified to take into account the importance of each species in the ecosystem, was used to compare stations. Results obtained by cluster and principal coordinate analyses showed comparable relations between stations. North Shore and Gaspé Coast stations were separated from those of the Lower North Shore, the Mingan Island sector and the Lower Estuary. Stations from the Lower North Shore were also separated from those of the Mingan Island region and of the Lower Estuary, but at a higher level of similarity. All animal assemblages consisted of the following sessile species: Obelia longissima (Pallas), Hiatella arctica (L.), Mytilus edulis L., Balanus balanoides (L.) and B. crenatus (Bruguière). These species formed over 95% of biomass of all sessile species. Differences between the various station assemblages were mainly due to changes in the relative abundance of these species. The geographical gradient of summer surface water temperature best explains the observed clusters. In the Lower Estuary, the spatio-temporal variations of physico-chemical factors and the surface circulation may influence the number of species and their abundance. The circulation systems of the Lower Estuary and near the Mingan Islands might account for the similarity between their assemblages. The same dominant species, Obelia longissima, characterizes the fauna of these two regions.     

Variabilité à court terme des propriétés physiques,chimiques et biologiques du Saguenay,fjord subarctique du Quebec (Canada)

Tidal variability of water mass characteristics has been assessed in the upper 100 metres of the Saguenay, a subarctic fjord in Québec, Canada. Temperature and salinity show a maximum variability in the 5-15 m layer in which vertical oscillations of a very sharp pycnocline are observed. Phosphates, nitrates and chlorophyll a are highly variable above this pycnocline during a tidal cycle, but dissolved oxygen content is remarkably stable in the whole water column. It is concluded that fluctuations of many variables in the subsurface waters might be large enough to hinder high rates of primary production.