Les diatomees dans l'upwelling de Cabo Frio (Bresil): liste d'especes et etude ecologique

The diatoms in the Cabo Frio (Brazil) upwelling: check listand ecological study. A qualitative and quantitative study onthe diatoms from the Cabo Frio area was made and a check listproduced. Sampling was carried out over one year at an anchoragestation in the upwelling zone. Data were analysed by means ofa multivariate statistical method, in order to show the mainsynecological aspects of the diatom populations. Diatoms dominatein most samples, except in the Brazil current water where dinoflagellatesare dominant, and where there is a poor population of thermophilicdiatoms. Recently upwelled water has a poor phytoplankton composedof epiphytic and benthic species; these are substituted by intenseblooms of neritic and opportunist diatoms when the temperaturerises. The annual distribution of the diatoms accompanies theoccurrence of upwelling. The vertical thermal gradient or waterstability is the most important factor affecting the specificcomposition and distribution of the diatom communities.     

Sur quelques Mesocyclops (Crustacea,Copepoda)

Resumé Après un rappel des critères morphologiques qu'il faut considérer en taxonomie des Copépodes du genre Mesocyclops, 14 espèces de ce genre sont décrites our redécrites, à savoir: M. granulatus nov.sp., M. thermocyclopoides, M. isabellae nov.sp., M. Kieferi, M. pehpeiensis, M. ogunnus, M. splendidus, M. brevisetosus, M. borneoensis nov.sp., M. tobae, M. pseudospinosus nov.sp., M. darwini nov.sp., M. notius, et M. australiensis, toutes formes des régions tropicales de l'Asie méridionale ou de l'Australasie.     

Nutrient enrichment of Cabo Frio (Brasil) sea water for phytoplankton mass production

Natural phytoplankton of Cabo Frio area was grown in 42 m-deep artificially upwelled seawater enriched with increasing concentrations of nitrogen or phosphorus. Respective values allowing maximum biomass, maximum uptake of initial reserve and maximum yield coefficient are rather conflicting. Notwithstanding, respective values of 75 μg at 1⁻¹ nitrogen and 5 μg at 1⁻¹ phosphorus, and therefore N:P = 15, appeared to be the best compromise for initial nutrient levels.     

Sur l'epharmonie et le bilan d'eau de quelques Salicornia de l'herault

Sans résuméReçu par la rédaction le 15.III.1954.     

Sur quelques traits de la biologie deHalictus calceatus Scopoli

Résumé On étudie expérimentalement dans quel ordre se déroulent les diverses activités deHalictus calceatus: creusement des cellules, approvisionnement, ponte et fermeture des cellules.On compare, à cet égard, la fondatrice deHalictus calceatus à celle deHalictus marginatus.On décrit succinctement le nid deHalictus calceatus.

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Summary The order in which the various activities of the foundress ofHalictus calceatus take place is experimentally studied.In this respect, the foundresses ofHalictus calceatus andHalictus marginatus are compared.The nest ofHalictus calceatus is briefly described.

     

Sur quelques echinodermes(Cystoides et Crinoides) de l'Ashgill d'Aragon (Espagne)

The material collected in the outcrops of Fombuenaand Luesma allows to specify the distinctive characters of the genera Corylocrinus and Caryocrinites, to describe two new species and to complete the morphology of Heliocrinites rouvillei and Proteocystites hispanica. The Crinoid association of these localities shows a very close composition with that of Coat-Carrec (Finistère). The new observations establish definitively the structure of the dorsal cup and the oral face of Mespilocystites. The occurence of the genera Stichocystis, Eucystis and Mespilocystites is recorded for the first time in Aragon. Cystoids and Crinoids confirm the existence of Ashgillian in the western part of the Armorican Massive.     

Sur la presence de lipides (phospholipides et sterides) dans les vacuoles de certaines cellules vegetales

Sans résumé     

Yearly variation in primary productivity of marine phytoplankton from Cabo Frio (RJ,Brazil) region

Light saturation curves of natural assemblages of phytoplankton at 4 stations in Cabo Frio coastal waters were examined and related to changes in environmental conditions, based on 263 experiments carried out weekly during two years. No differences in specific productivity at saturating light (Pm ^B ) between stations were detected. Global mean value of Pm ^B was 4.7 mgC mgChla ^–1 h^–1 with a range from 0.50 to 15.29. Significant seasonal variations were not observed. Correlation and regression analysis attributed most of Pm ^B variation to temperature, salinity, nutrients and the phaeopigment: chlorophyll-a ratio.     

Importance deVernonia guineensis Benth. dans l'alimentation de quelques Fourmis de savane

Résumé La ComposéeVernonia guineensis Benth., abondante dans les savanes préforestières de Côte d'Ivoire, fleurit quelques semaines après le passage des feux de brousse. Plusieurs espèces de Fourmis sont récoltées régulièrement sur la plante: ce sont surtoutCamponotus acvapimensis et unCremastogaster du genreAcroclia.Les Fourmis se nourrissent de sécrétions sucrées qui suintent au niveau des bractées des jeunes capitules, mais pratiquent également l'élevage d'Homoptères.Divers types de constructions sont décrits et, en particulier, les loges édifiées parC. acvapimensis pour abriter un Jassidæ:Selenocephalus sp.L'influence de l'environnement végétal sur la faune myrmécologique exploitantV. guineensis est mise en évidence.

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Summary Vernonia guineensis Benth. (Compositæ). common in the forest-savanna mosaic of Ivory Coast, blooms a few weeks after the fires. Several species of Ants are collected then on the forb; especiallyCamponotus acvapimensis and a species ofCremastogaster (Acroclia).These ants feed on seepings from the young flower heads, and search for exsudates of Homopterans.Various buildings are described, particularly shelters made byC. acvapimensis for the leaf—hopperSelenocephalus sp.Influence of botanical environment on the ants exploitingV. guineensis is shown.

     

Upwelling and downwelling at Cabo Frio (Brazil): comparison of biomass and primary production responses

Based on a comparative study of the different phases of upwellingand downwelling, a comprehensive model of average biologicalfeatures at Cabo Frio region was established. For identicalupwelling conditions, biological responses of equal range occur,allowing the establishment of some regional patterns. Thesepatterns are represented by chlorophyll values that range from0.5 to 6.0 mg m^–3, and primary production ranging from2 to 14 mg C m^–3 h^–1. During winter, in the absenceof upwelling, organic detritus constitutes the main energy sourcemaintaining the higher levels of the food web.     

Spatial structure of the zooplankton community in the Cabo Frio region (Brazil) influenced by coastal upwelling

Cabo Frio area (Central-southern Brazilian littoral) is characterized by a coastal upwelling due to prevailing E-NE winds, mainly during the spring-summer season. The geographic distribution of the zooplankton was described in order to separate ecological areas in terms of specific communities. Cluster analysis by weighted pair-group method (WPGA) and principal component (PC) analysis was performed on the most important hydrological parameters and zooplankton taxa. The first PC, explaining 38% of the total zooplankton variability, represented the influence of the nearshore-offshore gradient. Zooplankton communities and ecological areas were defined as follows:

1. nearshore neritic: the richest region with more than 5 000 org. m-3. In this very narrow nearshore region we observed 3 groups of taxa deliminated by upwelling effects and trophic conditions: a) Ctenocalanus vanus, Penilia avirostris, Calanoides carinatus and Copepod larva, all herbivorous species associated with the phytoplankton blooms in the upwelling zone; b) Creseis acicula and Temora stylifera; c) Siphonophora, Chaetognaths and a high diversity of Copepoda dominated by Coryceus amazonicus, C. giesbrechti, Eucalanus pileatus, Clausocalanus acuicornis, all carnivorous or omnivorous feeders representing a high degree of complexity of the ecosystem.
2. offshore neritic: characterized by appendicularians, this region constitutes an intermediate zone between coastal and oceanic waters.
3. oceanic: occupied by the Brazil Current where zooplankton is poor, but diversified, with typical copepods from tropical warm water: Clausocalanus furcatus, Mecynocera clausi, Corycella gracilis, Oithona setigera, Coryceus typicus, Oncea conifera, Undinula vulgaris, Calocalanus pavo, Haloptilus longicornis, Lucicutia flavicornis.

     

Modeling competition between Laurencia obtusa (Ceramiales,Rhodophyta) and Hypnea spinella (Gigartinales,Rhodophyta) at Cabo Frio Island,Rio de Janeiro,Brazil

The Lotka-Volterra competition model was used to represent the interaction between Laurencia obtusa and Hypnea spinella. A new model that considers effects of competition on algal carrying capacity is suggested. To test the models, data from field experiments conducted in an intertidal region at Cabo Frio Island, Rio de Janeiro, Brazil, were used. Both models showed that Hypnea was a stronger competitor than Laurencia. The model of interaction through the carrying capacity showed a stable coexistence between the algal populations and better represented the experimental data.     

Sur les plantes vasculaires dans le devonien de Libye

Study of the vegetation in Libya during the Devonian period has been made in different works concerning macrofossils (psilophytes, rhyniophytes, trimerophytes and lycophytes of the Murzuk Basin) and microrests and spores of the Rhadamès Basin.A comparison between the spores found in the sediments and those of fossil plants already known in other areas of the world, during the Devonian allowed us to confirm the hypothesis suggested by the study of microrests. Thus, one may suppose that during the Devonian period in Libya, as well as the four groups mentioned above, there may also have lived some plants such as sphenophytes (?) (one spore genus), filicophytes (?) (stomates and spores of five species), progymnosperms (?) (tracheids and spores of two species) and paleophyllales (?) (spore of one species).     

Histologie de quelques Sphinctozoaires (poriferes) triasiques

The microscopic study and mineralogic determination of two triassic Sphinctozoa show that the spherolitic sclerodermites are exclusively build by fibro-cristalline aragonite. It is suggested that these structures have a significant systematic character.It is also shown, in the second part of the paper, that other organisms present preciseanalogies with typical Sphinctozoa regarding histology and mineralogy.     

Conditions de digestion et activité de quelques polysaccharidases dans le tube digestif de l'oursin Paracentrotus lividus (Echinodermata)

The pH level of the gut fluid of the echinoid P. lividus is slightly acidic and its oxygen content is low (from 5 to 8%). An amylase and a cellulase-like enzyme are secreted by the echinoid stomach. Amylolytic activities have been detected also in food pellets from the stomach and from the posterior part of the intestine. This activity of intestinal pellets could be of microbial origin.     

Sur la decouverte dans le Cretace de Laveiras (Portugal) du plus ancien zeiforme connu

The discovery of a zeiform fish belonging to the family Zeidae of the Cretaceous from Laveiras (Portugal) lowersthe appearance of this family and of this order from the Paleocene to the Cenomanian.     

Sur la nutrition azotée de quelques espèces de bactéries propioniques

Sans résumé