Rosalina Globularis Research Articles

A survey of the benthic microfauna (foraminifera, Ostracoda) on the Basque shelf, southern Bay of Biscay

In this work we describe by the first time the microfaunal content (foraminifers and ostracods) of the benthos of the Basque continental shelf, by studying the spatial distributions of benthic foraminifer and ostracod assemblages in relation to the environmental parameters affecting the sediments of this region of the Bay of Biscay. Most abundant benthic foraminifer species in the surface samples are Brizalina spathulata, Bulimina marginata, Cassidulina laevigata, Hyalinea balthica, Lobatula lobatula, Rosalina globularis, Textularia sagittula and Uvigerina peregrina. Most abundant and widespread ostracod species are Lindisfarnia guttata, Costa edwardsii and Pterygocythereis ceratoptera-jonesi group. Multivariate analyses (Cluster Q, R; DCA) of samples and species of these organisms have been performed to provide an accurate description of these distributions. Based on these analyses six different facies are characterised in this shelf, according to their microfaunal content as well as to the average values of environmental parameters (CaCO 3, POC, silt–clay and hypoxic biological markers). Of these facies, the eastern fringe and the mudpatch have a more pronounced hypoxic character relative to the western facies in this shelf. Results provided by benthic foraminifer and ostracod assemblages totally agree and indicate their dependence of the environmental parameters of the sediment. In the eastern area the influence of deeper waters has been detected, probably as upwelling through the canyons, evidenced by the occurrence of bathyal species of foraminifers ( Fontbotia wuellerstorfi, Hoeglundina elegans) and ostracods ( Krithe spp., Cytheropteron spp., Buntonia spp.). The noticeable oil-affection found in benthic specimens, very likely caused by the oil-spill of the “Prestige” in the benthonic environment of the Basque continental shelf, has been detected eight months after the spill. Despite the studied bathymetric range of 50 to 150 m, the depth interval of specimens affected by oil-spill is that of the outer shelf (93–150 m). Benthic microfauna evidence oil-pollution in the bottom sediments and demonstrate a wider affected area in the bottom of the Basque shelf than previously stated.

ENVIRONMENTAL CONTROLS ON FORAMINIFERA IN LAKE QARUN, EGYPT

Foraminifera were investigated in Lake Qarun, an Egyptian inland saltwater lake, to determine their spatial distribution and the most common environmental factors that influence this distribution. Forty surface sediment grab samples from the lake were found to be rich in benthic foraminifera. Their faunal density ranged from 63 to 13,400 tests g(-1) with an average of 1700 tests g(-1) (s = +/- 2480). Faunal diversity ranged from 4 to 15 species with an average 10 species per sample (s = +/- 2.3). Both faunal density and diversity decreased in areas (biotopes 1 and 3) dominated by clay and silt (grain size <63 mu m) rich in organic matter. Degradation of organic matter by aerobic and anaerobic bacteria could lead to very low dissolved oxygen in pore and bottom waters where foraminifera live. Faunal data were used to divide the lake into three ecological biotopes. Samples from biotopes; 1 and 3 are characterized by high clay-and-silt content, with Ammonia tepida and Quinqueloculina seminula characterizing biotope 1 and A. tepida, Q. seminula and Cribroelphidium excavatum dominating biotope 3. Samples from biotope 2 are characterized by bioclastic sand-dominated substrates that are rich in Q. seminula, A. tepida, Quinqueloculina poeyana, Bolivina striatula and Rosalina globularis.Ammonia tepida and Quinqueloculina seminula compose similar to 70% of the total foraminiferal assemblage in Lake Qarun. The distribution patterns of these species indicate that each is controlled by distinct environmental factors. In biotopes I and 3, A. tepida positively correlates with high clay-and-silt content and Q. seminula correlates with high total dissolved solids. Cribroelphidium excavatum correlates positively with magnetic susceptibility and negatively with total dissolved solids (TDS). In biotope 2, Quinqueloculina poeyana, Bolivina striatula and Rosalina globularis correlate positively with coarse bioclastic substrates enriched in phytal remains, a condition consistent with the presence of the epiphytic taxon R. globularis. The occurrence of these halophilic species in Lake Qarun seems to be a consequence of rising salinity that has made the lake a suitable habitat for these foraminiferal taxa.

Benthic foraminifera from a recent, shallow-water hydrothermal environment in the Aeolian Arc (Tyrrhenian Sea)

Benthic foraminiferal assemblages from sediments around active or recently active hydrothermal vents in the Aeolian Arc have been investigated in four areas with different hydrothermal mineralization and seafloor exhalative activity at depths between ∼60 and ∼300 m. Active hydrothermal spots were distinguished from the surrounding sediments by direct observations by a Remotely Operated Vehicle (ROV) and subsequent seafloor sampling. Samples were taken at different water depths and are characterized by a number of mineralogies reflecting the changing temperature of the hydrothermal fluids. Overall, benthic foraminifera are absent from sites with high-temperature hydrothermal emissions, and their distribution at sites of low-temperature emissions is very patchy, depending on the physical and/or chemical conditions reflecting differences in temperature and composition of the emitted fluids. In the Secca del Capo area, which is free from recent emission activity, the benthic foraminiferal population is indicative of a normal marine environment, with Globocassidulina subglobosa, Cassidulina crassa, and Gavelinopsis lobatulus. In the Basiluzzo, Secca dei Pesci, and Panarea areas, which are characterized by different degrees of hydrothermal activity, three distinct assemblages have been recognized. The first assemblage is dominated by Ammodiscus catinus, Glomospira charoides, and Glomospira gordialis and indicates hydrothermal influence. The second assemblage, with Lobatula lobatula, Asterigerinata mamilla, Rosalina globularis, and Quinqueloculina spp. as main constituents, indicates a seagrass environment influenced by diffuse emissions. The third assemblage with abundant A. catinus, Ammoglobigerina globigeriniformis, G. gordialis and Haplophragmoides canariensis suggests low pH conditions resulting from acidic hydrothermal emissions, leading to the dissolution of calcium carbonate tests.

Territorial damselfish enhances multi-species co-existence of foraminifera mediated by biotic habitat structuring

The structures of benthic foraminiferal communities inside and outside the territory of the pomacentrid damselfish Stegastes nigricans on coral rocks in a moat of Sesoko Is. (26°38′N, 127°52′E) in Okinawa, Japan were compared. Inside the territory, an algal farm, i.e., a dense stand of a filamentous rhodophyte, Womersleyella setacea, was maintained throughout the year. Outside the territory, in areas subjected to intensive and continuous grazing by various grazers, the flora was composed of mat-like cyanophytes, a prostrate turf-form Padina sp., microscopically thin filaments and scattered filamentous rhodophytes. Algal biomass was greater inside the territory than outside the territory of the damselfish. These differences were reflected by the structure of the associated foraminiferal communities. We classified foraminiferal species based on their microhabitat use around algal communities into four life types: free-living type, crawling type, sedentary type, and sessile type. The abundance of foraminifera, especially the free-living type (e.g., Peneroplis pertusus and Quinqueloculina seminulum) and sedentary type ( Rosalina globularis and Cymbaloporetta squammosa), was greater inside the territory of the damselfish than outside the territory. Species richness was also higher inside the territory, mainly due to an increase in species richness of the free-living and sedentary types. These increases in abundance and species richness were caused by habitat structuring. W. setacea is a relatively tall and complicated alga with tangled rhizoids. Its dense stand inside the territory trapped a larger amount of sediment, which provided free-living foraminifera with heterogeneous and stable habitats. In addition, the dense stand of W. setacea provided sedentary-type foraminifera with a large, complex substratum, providing refuge and food inside the territory. This assumption was confirmed by the results of plate experiments showing that foraminiferal community structures were controlled by associations between foraminifera and algae. We showed that habitat-conditioning is an important process in biotic habitat-structuring and that habitat-conditioning by territorial damselfish maintains and enhances multi-species coexistence of foraminifera on coral rocks in a coral reef.

Epibiont foraminifera of Sertella frigida (Waters) (Bryozoa, Cheilostomata) from Terranova Bay, Ross Sea, Antarctica

Several arenaceous and calcareous foraminifera epibionts of Sertella frigida (Waters) (Bryozoa, Cheilostomata), collected in Terranova Bay during the 1989–90 Italian Antarctic expedition, were studied. Arenaceous species, such as Psammosphaera fusca Schulze f. adhearescens Rhumbler, Haplophragmoides canariensis d'Orbigny, Portatrochammina antarctica (Parr), and Trochammina arctica Hedley, Hurdle and Burdett, are a conspicuous component of the epifaunal community. The calcareous foraminifers encrusting S. frigida are mostly represented by Cibicides refulgens Montfort and Rosalina globularis d'Orbigny. Foraminifera were found only in the basal part of the bryozoan colonies. The presence of many juveniles provided evidence that foraminifers were reproducing at the time of sampling. Psammosphaera fusca f. adhaerescens was found exclusively inside the zooids of S. frigida. The large number of individuals associated with the bryozoan suggest that P. fusca f. adhaerescens finds optimum conditions (shelter, food, and grains for shell building) for growth inside the zooids of S. frigida. The other species occurred most commonly adhered to the trabeculae or to the zooid orifices of S. frigida. An elevated position offers a better chance to catch food particles from the overlying water column. Foraminifers could benefit also from bryozoan feeding currents. The availability of resuspended organic material could provide a more consistent source of food in a highly seasonal oligotrophic environment.

Pliocene foraminifera and environments, Limon Basin of Costa Rica

The sandstone facies of the Pliocene Rio Banano Formation of eastern Costa Rica contains benthic foraminifera indicative of an open marine, current-swept, neritic depositional environment. These sandstones and associated siltstones are placed in Zone N18 on the basis of overlapping ranges of planktonic foraminifera, particularly Globigerinoides obliquus extremus and G. ruber, and a short-ranging ostracode species, Radimella ovata. One hundred and eight species of benthic foraminifera have been identified from the formation. A multiple-group-component factor analysis of abundance distributions of several dominant or common species (Amphistegina gibbosa, Articulina mayori, Cassidulina laevigata, C. subglobosa, Cibicidoides floridanus, Elphidium discoidale, Hanzawaia concentrica, Pararotalia sarmientoi, Pseudononion basispinata, Quinqueloculina lamarckiana, Rosalina globularis, and Trifarina angulosa) in the type section aided in the recognition of three benthic foraminiferal assemblages related to environmental parameters. An open marine, shallow, sandy continental shelf environment is suggested by the first assemblage. This is considered the typical depositional environment of the unit. The second and the third assemblages, suggesting an inner littoral environment and the proximity to a reef, respectively, also indicate introduction of significant amount of transported material into the thanatotopes.

Les Foraminifères des carottages holocènes de la plate-forme continentale sarde

The object of this work is to present the foraminifera associations found in seven cores of holocoenic period from the continental shelf of southern Sardinia. The percentage of benthos is always definitely greater than 82,5 % . The benthic species are very numerous. There are no extinct species or species which present a paleoclimatic interest. The top-core samples collected from the infralittoral zone present two different associations based on its granulometry (sand and silt). The species most commonly found in sand are : Cibicides lobatulus, Ammonia beccarii, Rosalina globularis, Asterigerinata mamilla, Gavelinopsis praegeri, Buccella frigida granulata, Eponides répandus, Quinqueloculina aspera, etc. The species most commoly found in silt are Rosalina globularis, R. obtusa, Cibicides lobatulus. The presence of Posidonia oceanica may lead to a greater peercentage of some species (i.e. Nubecularia lucifuga, Rosalina bradyï). They may be referred respectively to the biocenose of well calibrated fine sands ("SFBC" of Peres &amp; Picard, 1964) and to the biocenose of the "herbier" of Posidonie ("HP" of Peres &amp; Picard, 1964). The species most commoly found in the top-core samples of the circalittoral zone are Asterigerinata mamilla, Cibicides pseudoungerianus, C. lobatulus, Neoconorbina terquemi, Ammonia beccarii, Spiroplectammina wrighti, etc. The planktonic foraminifera are mostly represented by Globorotalia truncatulinoides, Globigerina bulloides, Globorotalia inflata, Neogloboquadrina pachyderma, Globigerinoides trilobus. The association may be attributed, with great probability, to the biocenose of the coastal detritus ("DC" of Peres &amp; Picard, 1964). Along the cores, the associations present characteristics similar to those of the surface samples.

Distribution of Antarctic benthic foraminifers settling on the pecten Adamussium colbecki

Some benthic foraminifers in Explorers Cove, Antarctica, occur both in the sediment and on hard objects such as rocks and invertebrates. The abundances of four of these foraminiferal species have been measured from sediment samples and from the upper valve of the pecten Adamussium colbecki. The two calcareous species, Cibicides refulgens and Rosalina globularis were more abundant on the pecten shells than the sediment: the agglutinated species, Trochammina ochracea and T. malovensis were more abundant in the sediment. A zone of low foraminiferal density was observed around the outer margin of each shell, but no evidence of an influence of pecten feeding currents on the foraminiferal distributions was found. The size of the pecten shell influenced the density of epizoic foraminifers colonizing it; large shells (area >43 cm2) supported much higher densities than smaller ones.

The mechanism and adaptive significance of attachment and substrate pitting in the foraminiferan Rosalina globularis d'Orbigny

Attaches to any firm substrate by organic membrane, may cause pits to form on substrate, provides protection from turbulent shallow waters, Pleistocene, Holocene, California

Laboratory Experiments on the Life Cycle and Ecologic Controls of Rosalina globularis d'Orbigny

SYNOPSIS. The life cycle of R. globularis is shown to include a Tretomphalus stage identified as T. bnlloides. The life cycle is further complicated by successive asexual division producing typica1 agamonts. A brief synonymy is given for the genus. Basic experiments with light and substrate variation have shown no direct response.