La genre Scinaia (Rhodophycées,Nemalionales) de la Méditerranée occidentale

Abstract

The genus Scinaia (Rhodopbyta. Nemalionales) of the western Mediterranean sea. Only 3 species of Scinaia are to be found in Western Mediterranean sea. Scinaia complanala, S. furcellata and S. turgida. Scinaia sanctaluciana Funk is considered as a juvenile thallus of Scinaia complanala. Scinaia turgida is recorded for the first time in the Tyrrhenian sea since MAZZA (1902, 1903). A new anatomical character for the distinction of the Scinaia complanala and Scinaia turgida is also given.     

Recherches sur le genre Peyssonnelia (Rhodophyceae). X. Présence de Peyssonnelia codana (Rosenvinge) Denizot en Méditerranée

Abstract

Studies on the genus Peyssonnelia (Rhodophyceae). X. Presence of Peyssonnelia codana (Rosenvinge) Denizot in the Mediterranean.—Peyssonnelia codana (Rosenvinge) Denizot, previously known only from Denmark, is recorded from the vicinity of a thermal power plant outlet (Martigues-Ponteau, Gulf of Fos, France). Mediterranean specimens are described and new details about the morphology of sporangial and sexual nemathecia are given.     

Dynamique et èvolution de l'herbier à Posidonia oceanica en Méditerranée

Abstract

The natural growth of a Posidonia oceanica meadow is the result of a long process of development (series of events), but the dynamics are often difficult to establish because of the lack of a zero state and of sufficiently long chronological series. In addition, while it is sometimes possible to observe major regressions, the phenomena of recolonisation and of small-scale fluctuations are rarely detected. Nevertheless, with the emergence of new investigatory techniques (lepidochronology, microcartography, monitoring networks, accurate dating techniques, etc.,) considerable progress has been made in this field. The development in space and time of the seagrass beds is dependant on hydrodynamic action and sedimentary deposits. This means that in sheltered bays Posidonia oceanica may form original structures such as barrier reefs or micro-atolls, while in turbulent waters one observes the formation of spectacular structures resulting from erosion (intermatte, “rivière de retour”). A disequilibrium in sedimentation may result in dramatic regression in some seagrass beds. The multiplicity of prevailing environmental conditions results in the occurrence of a range of meadow types: “herbiers de plaines”, “herbiers de collines”, “herbiers tigrés”, “herbiers en escalier”. The impact of human pressure over the past few decades has not been insignificant. Coastal development constructions that have altered the direction of currents and the sedimentation, sewage outfalls that have resulted in an increase in the turbidity of the water and the mechanical action of anchors or trawl nets which have damaged certain areas of seagrass meadow have caused extensive regression. Conversely, the rehabilitation of previously degraded areas has made it possible to monitor the process of recolonisation.     

Spectre pollinique des miels de l'abeille Apis mellifera L. (Hymenoptera,Apidae) et Zones de Végétations en Afrique Occidental Tropicale et Méditerranéenne

L'analyse pollinique de 130 échantillons de miel issus de six zones de végétation depuis le Maroc jusqu'au Golfe de Guinée, met en évidence les principals différences dans le comportement d'affouragenemt de quatre variétés d'Apis mellifera (adansonii et sahariensis à langue longue; major et intermissa à langue courte). Dans la zone tropicale humide forestière guinéo-congolaise et intermédiare guinéo-congolaise/soudanienne, les abeilles sont très sélectives dans leur choix; elles privilégient les sommets très fleuris des frondaisons proches des ruches où elles recherchent les gros fournisseurs de nectar parmi les espèces melittophiles de préférence. Quelques rares taxons anémophiles porteurs de miellat (Celtis) sont localement visités. Au sein de ces forêts, le comportement d'affouragement des abeilles varie peu quelque soit la saison. Dans les zones plus sèches soudaniennes ou semi-arides de savane et dans les régions méditerranéennes ou intermédiaires sahéliennes et méditerranéennes, les abeilles apparaissent moins sélectives et exploitent une très large proportion de la flore mélittophile ou amphiphile disponible, ainsi qu'une proportion plus élevée d'anémophiles à miellat, surtout en région méditerranéenne. En savane, le comportement de butinage varie suivant les saisons: la strate arborescente est principalement visitée au cours de la saison sèche tandis que celle herbacée en fleur est exploitée durant la saison humide. Le rythme des successions des floraisons est ainsi perceptible dans la composition pollinique des miels. En zone méditerranéenne, la strate herbacée est celle qui fournit le plus de nectar, à l'exception de certaines essences introduites, comme les Eucalyptus en fin de saison des pluies / début de saison sèche. En zone humide forestière, de nombreux arbres prèsentent de grandes fleurs colorées odoriférantes produisant de grandes quantités de nectar au cours des deux saisons. Au contraire, en zone méditerranénenne, la plupart des fleurs nectarifères portées par des herbacées sont petites et donnent peu de nectar. Dès lors, les abeilles sont obligées d'élargir leur champ de butinage. La composition floristique des miels ne reflète réellement la structure de la végétation que dans le cas des régions sèches où les abeilles exploitent l'ensemble de la végétation. En revanche dans les régions tropicales humides forestières ou de savane arborée, le spectre pollinique des miels ne correspond qu'aux formations végétales entourant les ruches parfois représentatives des grands types de végétation de la région. Seules alors les endémiques ou certaines associations spécifiques permettent une bonne typification des miels. Le degré de sélectivité des abeilles vis à vis de la flore ne paraît être influencé que par la morphologie florale, la phénologie et les facteurs climatiques les conditionnant ainsi que par la longueur de la langue.

The pollen analysis presented here concern about 130 honey samples from six vegetation zones from Morocco to the Gulf of Guinea. They illustrate the principal differences in foraging behaviour between four bee races of Apis mellifera (adansonii and sahariensis with a long tongue; intermedia and major with a short tongue). In the tropical rain forest guineo-congolian and intermediate guineo-congolian/sudanian regions, the bees are very selective in their choice. They favour near the hives the richly flowering forest canopy of honey-producing entomophilous species. Some rare anemophilous taxons with honeydew (Celtis) are localy visited. In such forest, the foraging behaviour is not very different between dry or wet season. In the drier soudanian or semi-arid savannah and in the mediterrenean and intermediate sahelian and mediterranean zones the bees sem less selective and gather on a very large part of the melittophilous or other available species. They also gather on a high proportion of anemophilous species with honeydew, in particular in mediterranean regions. In savannah country the foraging varies with the seasons, the forest stratum is principaly visited during the dry season and the herbaceous stratum during the wet season. The rhythm of successive flowering is thus visible in the honey pollen spectra. In the mediterranean region the herbaceous stratum produces most of the nectar with the exception of some introduced species like Eucalyptus at the end of the wet season/beginning of the dry season. In wet forest zone many trees have large fragrant and highly coloured flowers producing abundant nectar. On the other hand, the nectariferous flowers, small and containing little nectar are found on herbaceous plants in the mediterranean region. Here the bees need to extend widely their gathering area. Consequently the pollen spectra of the honey correspond to the composition of the vegetation only in the dry regions where the bees exploit all available species. In contrast, in tropical rainforest or tree-savannah regions the pollen spectrum of the honey agrees only with the vegetation formation in the vicinity of the hives, sometimes representative of the major vegetation types of the region. Only endemics or certain species associations allow a clear identification of the honeys. The degree of selectivity of the bees is only influenced by floral morphology, phenoloay, climatic factors and the length of the tongue. It appears independant of the morphology and the race of the insects. This explains why bees adapt so well their foraging behaviour to major vegetation types as this can be seen in the America where they were introduced.     

El géneroJacquinia L. (Theophrastaceae) en Cuba

The term phyletic diversity is used here to denote the continued co-existence and evolution of separate major phyletic groups which have a similar mode of life (e.g. within the angiosperms). This work attempts to show that an understanding of the factors which determine the degree of phyletic diversity could contribute to understanding the nature and evolution of higher taxonomic categories, such as families. The opposite of phyletic diversity, phyletic uniformity (Fig. 1A—B), should result from unequal evolutionary rates of different groups and repeated adaptive radiations of the most successful groups; the following competition for essential, limiting resources should lead to the extinction of all less rapidly evolving, inferior groups. At least some plant families are shown to have specific adaptive specializations which give them competitive advantages for part of the environmental resources only. This ensures their co-existence and the maintainance of phyletic diversity. The nature of these family specializations is considered briefly. It is shown that physiological adaptations to particular conditions, symbioses which aid in obtaining nutrients and, especially, chemical defence mechanisms could be major components of these specializations and thereby the raison d'être of plant families.     

Bryozoaires cheilostomes nouveaux du Miocène supérieur du Bassin d'Alboran (Méditerranée occidentale)

Three new species and one new subspecies, Tremogasterinacookae, Cribrilina messiniensis, Emballotheca mediterranea and Herentia thalassae alboransis (Bryozoa, Cheilostomata) are described from various Messinian deposits (Uppermost Miocene) of the Mediterranean province of Alboran: Algeria, Morocco, Spain.     

Gelidiaceae (Rhodophyta) in Bahía de Banderas,Western Pacific,México

We present the results of a floristic study of intertidal species of Gelidiaceae collected in ten localities in the Bahía de Banderas region. The study area is within an extensive overlapping transitional zone between the tropical and subtropical regions of the Mexican Pacific coast. Species of the genera Gelidium and Pterocladia were found, G. microdentatum and G. pusillum being the most abundant and widely distributed in the Bay. The local and Mexican Pacific distribution for each species is given. The number of species found in this study is compared with the numbers reported in the literature for the Mexican Pacific.     

Analyses sédimentologiques,géochimiques et malacologiques d'une carotte prélevée dans le Golfe du Lion (Méditerranée Française)

The analysis of this core taken from the French continental shelf makes it possible to trace the sedimentological evolution of the area from Würmian times to the present day. Apart from relatively coarse deposits laid down in shallow water, with intercalations of sandy beds and a cold water Arctica islandica fauna, there is a progressive change, in post-glacial and Recent times, to more and more fine-grained sediments. Immigrant Atlantic species disappear in the higher beds of the core. This change is also reflected in an increase in salinity of the interstitial water in the higher beds. The indigenous molluscan assemblage remains the same throughout.     

Etude in situ de la réinstallation d'un peuplement sciaphile de mode battu après sa destruction expérimentale,en Méditerranée

Resume 1. La destruction expérimentale d'un peuplement rapporté à la biocoenose de la roche sciaphile en mode battu (RSB), dans la région de Marseille, et l'étude des phases de sa réinstallation (fraction algale), selon la méthode phytosociologique deBraun-Blanquet (1964), a apporté les résultats suivants.2. Quatre mois après sa dénudation, la roche est déjà couverte par l'algue encroûtanteDermatolithon hapalidioides; ultérieurement (6 mois), de nombreuses algues dressées s'installent surDermatolithon hapalidioides, principalementPseudochlorodesmis furcellata, Petroglossum nicaeense etMyriogramme minuta. Au bout d'un an, toute la place disponible est occupée parPetroglossum nicaeense, Plocamium vulgare etValonia utricularis, tandis queDermatolithon hapalidioides régresse an sous-strate. Ensuite,Petroglossum nicaeense etPlocamium vulgare deviennent codominantes.3. Chacune de ces phases correspond à l'un des éléments structuraux du peuplement de référence. D'où l'hypothèse: le peuplement étudié évolue naturellement vers une phase àPetroglossum nicaeense etPlocamium vulgare assez vulnérable à l'hydrodynamisme; des touffes d'algues seraient arrachées par les vagues; l'assemblage en mosaïque d'éléments, au niveau de peuplement initial, serait donc dû à la présence simultanée, à quelques cm de distance, de stades de régénération d'âge variable.4. La réinstallation du peuplement après sa destruction est excessivement rapide, et ceci pour un très grand nombre de paramètres envisagés.

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In situ studies on the reconstruction of a shady and wave-lashed marine population after experimental destruction in the Mediterranean

The structure (internal organization) of the biocoenosis of the shady and wave-lashed bottoms in the western Mediterranean Sea is very heterogeneous. Little is known concerning the causes of this heterogeneity. For analyzing the composition of the vegetation, the survey method ofBraun-Blanquet (1964) was used. Reconstruction of the biocoenosis on cleaned rocky surfaces follows a definite pattern as a function of time. After 4 months, the rocky surface is covered with the crustaceous algaDermatolithon hapalidioides. After 6 months, various dendristic and fruticose algae settle onD. hapalidioides, mainlyPseudochlorodesmis furcellata, Petroglossum nicaeense andMyriogramme minuta. After 1 year, the whole area is occupied byP. nicaeense, Plocamium vulgare andValonia utricularis; the undergrowth consists ofD. hapalidioides which becomes slowly superseded by fruticose algae. This sociological progression shows that: (1) The phases during reconstruction of the settlement are equivalent to the structural elements of the initial settlement; (2) perhaps the structural organization results from a chronological sequence of different phases; (3) reconstruction of the initial settlement after experimental destruction is very rapid.