Benthic foraminiferal associations in the Northern Bay of Safaga, Red Sea, Egypt

In the shallow-water area (0–70 m) of the Northern Bay of Safaga, 73 surface samples were studied with respect to total foraminiferal fauna. The samples cover a great variety of shallow-water environments and yielded 239 foraminiferal taxa. Based on q-mode cluster analysis, and tested by canonical discriminant analysis, the samples are grouped into 13 foraminiferal associations, each characterized by several species:

(1) Quinqueloculina mosharrafai-Borelis schlumbergeri-Brizalina simpsoni Ass.,

(2) Heterostegina depressa-Amphlstegina lessonii/bicirculata Ass.,

(3) Cibicidids-Rosalina-Amphistegina lobifera-Pseudoschlumbergerina ovata Ass.,

(4) Peneroplis planatus Ass.,

(5) Peneroplis planatus-Varidentella neostriatula Ass.,

(6) Peneroplis planatus-Coscinospira hemprichii-Varidentella neostriatula Ass.,

(7) Quinqueloculina spp. Ass.,

(8) Hauerina diversa-Sorites orbiculus Ass.,

(9) Verneuilina sp.-n Articulina pacifica-Reussella simplex Ass.,

(10) Textularia agglutinans/rugulosa-Bolivina variabilis Ass.,

(11) Textularia agglutinans-Challengerella bradyi-Elphidium jenseni/simplex Ass.,

(12) Operculina ammonoides-Adelosina laevigata-Brizalina striatula/subspathulata Ass.,

(13) Bolivina variabilis—Miliolinella-Nonion fabum-Elphidium simplex Ass.

The characteristic forms of each association are linked to specific environmental parameters and modes of life. As long as taxonomic uniformitarianism can be applied, similar associations with comparable ecological demands may also be detected in the fossil record. For comparisons with taxonomically different material the 13 associations are summarized into 4 categories each reflecting a specific type of substrate. In the fossil record these categories may be recognized by general morphological characteristics of the foraminiferal tests and by sedimentological data. The 4 substrate types are: hardground, sand (with or without seagrass and/or corals), firmground, and soft bottom.     

福建漳平下二叠统的小有孔虫

福建漳平岭兜下二叠统地层发育良好,序列清楚,与ting类共生的小有孔虫化石丰富。根据化石群垂直分布特点,可分为三个小有孔虫组合,自下而上为Geintzina-Pachyphloia组合,Langella-Pseudoglandulina longa组合及Hemigordius qinglongensis-Cribrogenerina celebrata组合。这三个小有孔虫组合在福建均属首次发现。这发现为下二叠统的地层时代归属又提供一佐证。     

Environmental impacts on the benthic foraminiferal fauna in nearshore ecosystems

This review presents data on how natural and anthropogenic factors affect species composition, abundance, and test morphology of benthic foraminifera of the world oceans. Major emphasis is placed on high sensitivity of foraminifera to changes in the state of the environment, particularly in nearshore zones under anthropogenic impact. It is shown that benthic foraminifera can provide indicators of environmental conditions in marine ecosystems. The effects of mollusk and salmon aquaculture activities on the composition and distribution of foraminifera are considered. It is stressed that a distinction must be made between foraminiferal test morphology variations in response to natural and anthropogenic impacts.     

Benthic foraminiferal assemblages in the severely polluted coastal environment of Drapetsona-Keratsini,Saronikos Gulf (Greece)

Surface sediments were collected from the coastal zone of Drapetsona–Keratsini (Saronikos Gulf, Greece) in December 2012 for determining the local benthic foraminiferal community, identifying their spatial distribution patterns, and evaluating the response of foraminiferal species to geochemical composition through the hierarchical cluster analysis, principal component analysis and Spearman's rho correlation. Foraminifera can be classified into three distinct assemblages associated with the granulometry, elemental geochemistry, particulate organic carbon content and degree of sediment contamination. A relatively low-diversity assemblage, dominated by stress-tolerant taxa with Ammonia tepida Bolivina spathulata and Bulimina elongata being the prevailing species, is characteristic of the silty seabed of the main part of Drapetsona coastal zone and the Keratsini Port central basin, where organic carbon content, aliphatic and polycyclic aromatic hydrocarbons concentrations and trace metal loads are greatly elevated. On the sandy bottom of the investigated area, relatively high frequencies of miliolids prevail. An epiphytic rotaliid-dominated assemblage is recorded in the slightly-polluted sedimentary bottom of the inner and western part of the Keratsini Port.     

Benthic foraminiferal paleoenvironmental reconstruction from the Upper Coniacian-Lower Campanian succession in north-western Tunisia

Quantitative analysis of benthic foraminifera is used to characterize the paleoenvironments of the Upper Coniacian-Lower Campanian succession in the Jbil section of north-western Tunisia. Foraminiferal parameters and benthic foraminiferal assemblages show that the studied section includes four distinct paleoenvironmental phases. From oldest to youngest, these are as follows: (1) an interval with a Praebulimina reussi assemblage with infaunal ratios as high as 96.1%. High abundances of P. reussi, reflecting an increase in organic matter flux to the seafloor (meso-to eutrophic) under oxygenated bottom-water conditions. (2) An interval characterized by a Gavelinella costulata assemblage with mixed infaunal/epifaunal foraminifera with higher Fisher's alpha values (ranging from 4 to 15.2), reflecting mesotrophic conditions in an outer shelf environment. (3) An interval with a Gaudryina laevigata assemblage indicative of a middle to outer shelf environment; there is a considerable increase in infaunal agglutinated foraminifera, as well as a relatively abundant and moderately diversified oxic/suboxic foraminifera. (4) The final interval occurs in the lower Campanian (the Globotruncana ventricosa Zone) and includes a Bolivinoides decoratus assemblage reflecting an outer shelf to upper bathyal environment. It contains a higher planktonic percentage and biodiversity with a slight increase in dysoxic species; the mixed infaunal/epifaunal content (57.6 to 73.3%) reflects mesotrophic conditions. Four well-recognized major sea-level falls are matched by the dual signatures of eustatic sea-level changes. These are coincident with the results of this study, which represent the first documentation of these events in Tunisian faunal and paleoenvironmental changes, at the following boundaries: Coniacian/Santonian, intra-Santonian, Santonian/Campanian, and intra-early Campanian.     

The frontier problem in incipient groundwater management regimes in Balochistan (Pakistan)

Using case material on the exploitation of groundwater in Balochistan Province in Pakistan, the article studies how resource management regimes evolve or fail to evolve. Incipient resource management regimes face two problems: the definition of access rights and the lack of knowledge on the limits and regenerative capacities of the resource as well as on the behavior of the co-users. These problems will usually be addressed as soon as increased exploitation makes itself first felt in declining groundwater exploitation, though this does not necessary mean that the resource is exploited at levels that are not sustainable. As exploitation will continue to increase however the point of overexploitation may be reached, beyond which it will be much more difficult for a resource management regime to evolve.     

Eocene -Oligocene paleoceanography of the deep Bay of Biscay: Benthic foraminiferal evidence

A major change in benthic foraminiferal assemblages occurred in the deep Bay of Biscay (> 3 km water; DSDP Sites 119, and Site 400A) between early middle Eocene and earliest Oligocene. Predominant Eocene deep-sea taxa (Nuttallides truempyi, Clinapertina spp., Abyssamina spp.) and associated rarer species became extinct in this interval. These extinctions were followed by an increase in abundance of bathymetrically wide-ranging and stratigraphically long-ranging taxa: Globocassidulina subglobosa, Oridorsalis spp., Gyroidinoides spp., and the Cibicidoides ungerianus plexus. The extinctions cannot be dated precisely from the stratigraphic record recovered to date in the Bay of Biscay; however, the replacement of the N. truempyi-dominated assemblage has been noted previously in the deep South Atlantic/Caribbean as occurring near the middle/late Eocene boundary. Other than the decrease in abundance and extinction of N. truempyi, no major abundance changes are noted within the Eocene at the shallower Site 401 (～ 2 km water) in the Bay of Biscay. During the Oligocene, Nuttallides umbonifera replaced the Eocene species N. truempyi as the predominant deep-sea benthic foraminifera, reaching peak abundance in the middle Oligocene at Sites 119 and Site 400A. In the modern oceans, the abundance ot N. umbonifera is positively correlated with increased corrosiveness of bottom water, while at Site 119 the abundance of Nuttallides spp. is negatively correlated with δ ¹³C values in benthic foraminifera. As lower δ ¹³C values are often associated with older water masses, large numbers of Nuttallides spp. are thought to reflect older, and more corrosive bottom water. The faunal data and oxygen and carbon isotopic data are compared with a circulation model derived from North Atlantic seismic stratigraphic studies to show that old, warm, corrosive, and sluggish Eocene bottom water was replaced by younger, colder, less corrosive, more vigorously circulating bottom water of northern origin by the early Oligocene. Faunal and isotopic data suggest that bottom water became older and more corrosive again in the middle Oligocene, reflecting a reduction in circulation that can also be inferred from the seismic record in the nearby Rockall Plateau region.     

Paleoceanographic changes during the past 1.9 Myr at DSDP Site 238, Central Indian Ocean Basin: Benthic foraminiferal proxies

Deep-sea benthic foraminifera have been quantitatively analyzed in samples (> 125 μm size fraction) from Ocean Drilling Program (ODP) Site 238, to understand paleoceanographic changes in the Central Indian Basin over the past 1.9 Myr. Factor and cluster analyses of the 25 highest-ranked species made it possible to identify five biofacies, characterizing distinct deep-sea environmental settings. The environmental interpretation of each biofacies is based on the ecology of recent deep-sea benthic foraminifera. The benthic faunal record indicates fluctuating deep-sea conditions in environmental parameters including oxygenation, surface productivity and organic food supply. These changes appear to be linked to Indian summer monsoon variability, the main climatic feature of the Indian Ocean region. The benthic assemblages show a major shift at ∼ 0.7 to 0.6 Ma, marked by major turnovers in the relative abundances of species, coinciding with an increased amplitude of glacial cycles. These cycles appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the Central Indian Ocean Basin.     

Benthic foraminiferal morphogroups of mid to outer shelf environments of the Late Jurassic (Prebetic Zone, southern Spain): Characterization of biofacies and environmental significance

Benthic foraminiferal assemblages belonging to a mixed carbonate–siliciclastic shelf succession of the Oxfordian (Upper Jurassic) in the Prebetic, southern Spain, were analyzed. The faunal data, obtained on thin sections of strongly lithified sediments, allowed the detailed differentiation of a foraminiferal morphogroups system to be applied to the interpretation of paleoenvironmental conditions. Eleven morphogroups were differentiated according to shell composition, general morphology, number of chambers and mode of coiling. Paleoenvironmental analysis combines these features with inferred life-style (epifaunal, shallow infaunal and deep infaunal) and feeding strategy (suspension-feeder, deposit-feeder, herbivores, etc.) of the foraminifera. Analogies and differences regarding previously established morphogroup systems could be outlined accordingly.

In the Prebetic Oxfordian, distribution trends of foraminiferal morphogroups allow for a comparison of mid to outer shelf environments occupying the South-Iberian paleomargin, indicating that nutrient supply was the most important factor controlling morphogroup development. The mid shelf settings are dominated by epifaunal active herbivores–phytodetritivores, in shallow to deep substrate position of the redox boundary. The outer shelf is dominated by agglutinated and infaunal detritivore-bacterial scavenger morphogroups revealing a deep substrate position of the redox boundary. Particularly favorable trophic conditions in mid shelf environments are related with higher phytodetritus input from more proximal and shallower shelf areas.     

Benthic foraminiferal assemblages between two major extinction events: the Paleocene El Kef section,Tunisia

The development of benthic foraminiferal assemblages from the Paleocene outcrops of the El Haria Formation near El Kef, Tunisia is discussed qualitatively and quantitatively. The aim of the study is to reconstruct the paleoenvironmental evolution between the K/Pg boundary interval and the late Paleocene event, and to compare this evolution with results from other sites along the southern Tethyan margin. Eighty-four samples, covering virtually the entire Paleocene, provide a dataset that allows detailed qualitative and multivariate analysis. The benthic foraminiferal faunas indicate a complex pattern of environmental changes during the Paleocene, marked by the succession of different benthic associations. Following the K/Pg boundary event, community restoration was characterized by the gradual build-up of faunal diversity. Decreasing dominance and the entry of taxa common to normal marine, outer neritic to upper bathyal environments indicate the completion of the ecosystem restoration in Zone Plb. A highly diverse benthic foraminiferal assemblage persisted throughout the remainder of the early Paleocene into the earliest late Paleocene. At the P3a-P3b zonal transition relative sea-level lowering is evidenced by the sudden disappearance or decreasing abundance of deeper-water taxa (e.g. Anomalinoides affinis, A. susanaensis, Gavelinella beccariiformis). Neritic deposition continued into Zone P4, when trophic levels at the seafloor increased as indicated by the entry and increasing dominance of species such as Anomalinoides cf. aegyptiacus, Bulimina midwayensis, and B. strobila, which we consider to be sensitive to eutrophication. The combined effect of shallowing and the subsequent eutrophication led to the establishment of assemblages similar to late Paleocene benthic foraminiferal assemblages from Egyptian sections, some of which record the latest Paleocene extinction event. These assemblages were interpreted to be indicative of a middle neritic, highly eutrophic environment. Enhanced vertical fluxes of organic matter along the southern Tethyan margin may have resulted from intensified upwelling. This eventually led to oxygen deficiency at the seafloor. It appears that oxygen-deficient, high-productivity shelves were a common feature of the southern Tethyan margin during the latest Paleocene.     

Zoogeography of the southern African ascidian fauna

Aim To describe the biogeography of the ascidian fauna of southern Africa, to compare the results obtained with those reported for other fauna and flora of the same region, and to speculate about the origin of ascidians in the region. Location Southern Africa extending over 4000 km from Mossâmedes (15° S–12° E) to Inhaca Island (26°30′ S–33° E), including Vema Seamount (31°40′ S–8 °20′ E), Amsterdam‐Saint Paul Islands (38° S–77°30′ E) and the Tristan‐Gough Islands (38° S–12°20′ W). Methods We constructed a presence/absence matrix of 168 species for 26 biogeographical divisions, 21 classical biogeographical regions described by Briggs (Marine zoogeography, McGraw‐Hill, New York, 1974) and five provinces within the southern African region. We considered the following limits and divisions into provinces for the southern African region: Namibia, Namaqua, Agulhas and Natal as proposed by Branch et al. (Two oceans. A guide to the marine life of southern Africa, David Philip Publishers, 1994), and the West Wind Drift Islands province (WWD) according to Briggs (Global biogeography, Elsevier Health Sciences, Amsterdam, 1995). To examine the biogeographical structure, species and divisions were classified using cluster analysis (based on UPGMA as the aggregation algorithm) with the Bray–Curtis index of similarity. This classification was combined with MDS ordination. Main conclusions Four main groups were obtained from the analysis of affinities among species: (1) species present in the WWD, separated by a high percentage of endemisms and a low number of species with a southern African distribution. Moreover, in the light of the species distribution and the results of further analysis, which revealed that they are completely separated and not at all related to the southern African region, it appears that there are no close relationships among the different islands and seamounts of the West Wind Drift Island province. This province was therefore removed from the remaining analyses; (2) species with a wide distribution; (3) species of colder waters present in Namaqua and Agulhas provinces, a transitional temperate area in which gradual mixing and replacement of species negate previous hypotheses on the existence of a marked distributional break at Cape of Good Hope; (4) species of warmer waters related to Natal province. The classification into biogeographical components was dominated by the endemic (47%), Indo‐Pacific (25%) and cosmopolitan (13%) components. The analysis of affinities among biogeographical areas separated Namibia from the rest of the southern African provinces and showed that it was related to some extent to the Antarctic region because of the cold‐temperate character of the province and the low sampling effort; Namaqua, Agulhas and Natal were grouped together and found to be closely related to the Indo‐West Pacific region. In general, our results were consistent with those obtained for other southern African marine invertebrates. The frequency distribution of solitary/colonial strategies among provinces confirmed the domination of colonial organisms in tropical regions and solitary organisms in colder regions. Finally, we speculate that the southern African ascidian fauna mainly comprises Indo‐Pacific, Antarctic and eastern Atlantic ascidians.     

Benthic foraminiferal ecomarker species of the terminal Cretaceous (late Maastrichtian) deep-sea Tethys

Benthic foraminiferal distribution patterns throughout the late Maastrichtian Tethyan deep sea are analyzed. Many species are ubiquitously distributed throughout this region and therefore it is hard to assess their ecological preferences. However, five species show distribution patterns, which suggest that they may have distinctive paleoenvironmental preferences. These preferences are interpreted from hypothesized surface circulation and upwelling patterns. Additional information comes from Recent benthic foraminiferal ecology and from responses to the Cretaceous/Paleogene (K/Pg) boundary event. This enables us to assess the ecological preferences of these late Maastrichtian taxa, and establish them as ecological-marker (ecomarker) species for paleoenvironmental interpretation of the late Maastrichtian bathyal-abyssal Tethyan realm.(1) Eouvigerina subsculptura is suggested to be indicative of reasonably oxygenated upper-middle bathyal environments, though with high abundance of utilizable organic matter. (2) Sliteria varsoviensis is linked to areas of late Maastrichtian upwelling and seems to have been an epibenthic species with an opportunistic life mode. (3) Gavelinella beccariiformis and (4) Nuttallides truempyi are considered to be indicative of oligotrophic conditions unless they occur with a large proportion of endobenthic morphotypes. (5) Gavelinella pertusa is proposed to indicate neritic-middle bathyal environments of the ‘boreal’ realm, which might be influenced by more seasonal food-fluxes and by higher oxygen levels than similar settings in the (sub)tropics.Finally, the anomalous high abundances of the buliminid species Sitella cf. plana in deep open ocean environments is discussed in terms of possible mechanisms permitting such a (morphologically) opportunistic species to thrive in such an assumedly oligotrophic environment.     

Benthic foraminiferal responses to absence of fresh phytodetritus: A two-year experiment

Sediment and bottom water from 320 m water depth in the Skagerrak basin (NE North Sea) was maintained in the laboratory and kept unfed in the dark, at ambient temperature, for two years. Although the relative abundance of agglutinated taxa in the sediments increased at the expense of allogromiids and calcareous forms, the deprivation of fresh phytodetritus caused only a moderate change of the faunal composition of the bathyal, benthic foraminiferal assemblage (six of the seven most abundant species were the same before and after the treatment; overall similarity was 58%). Among the most common species, the halt in supply of fresh organic material promoted population growth in some (e.g., Textularia earlandi, Leptohalysis gracilis, Melonis barleeanum), some maintained their populations (e.g., Globobulimina auriculata, Liebusella goësi, Eggerelloides medius), while others (e.g., Nonionella iridea, Cassidulina laevigata, and some allogromiids, particularly Micrometula hyalostriata) nearly disappeared. The different responses probably reflect the species' relative dependence on fresh phytodetritus. Those species which could utilize food stored or produced in the sediments (e.g., bacteria and degradation products) increased or maintained their populations, whereas those dependent on fresh phytodetritus and/or associated early-decomposition products declined. In spite of these changes, the species diversity showed only a minor reduction. The overall moderate response to lack of fresh phytodetritus was probably due to the fact that the assemblage already was adapted to an environment dominated by poor quality food particles. The study illustrates that the quality of organic material has an important impact on the composition and maintenance of some benthic foraminiferal communities, that the faunal response to reduction, or even a halt, in the supply of fresh phytodetritus, is not necessarily immediate or dramatic, and that the response depends on the trophic conditions prevailing in the area when the halt occurs.     

Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes

Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7–6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7–6.4, 4.0–3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge.The second change recorded by benthic foraminiferal faunas occurs at 3.4 Ma in the Caribbean and 4.0-3.2 Ma in the Pacific. At this time the Caribbean is flooded with cold AABW, which is either gradually warmed or is replaced by Glacial Bottom Water (GBW) at 2.0 Ma and by NADW at 1.1 Ma. These changes are related to global climatic events and to the depth of the sill between the Caribbean and Atlantic rather than the rising Isthmus of Panama. Benthic foraminiferal faunas at East Pacific Site 503 indicate a gradual change from cold PDW to warmer PDW between 4.0 and 3.2 Ma. The PDW is replaced by the warmer, poorly oxygenated PIW at 2.1 Ma. Although the PDW affects the faunas during colder intervals between 1.4 and 0.7 Ma, the PIW remains the principal bottom-water mass in the Guatemala Basin of the East Pacific.     

Benthic foraminiferal evidence of sediment supply changes and fluvial drainage reorganization in Holocene deposits of the Po Delta,Italy

Detailed benthic foraminiferal analyses performed on the Holocene subsurface deposits of modern Po Delta evidenced a complex palaeogeographic evolution. Hierarchical R- and Q-mode cluster analyses allowed to distinguish four assemblages indicative of different marine environments and sub-environments. Temporal and spatial distribution patterns of benthic foraminifers reflect changes in Po River discharge during delta evolution. The capability of foraminiferal assemblages to track nutrients and sediment supply oscillations permitted to recognize four main evolutionary phases (A–D), which took place after the maximum marine transgression (ca. 5500 cal yr BP).     

Benthic fauna species diversity in six central Florida lakes in summer

The summer macroinvertebrate fauna was studied in six central Florida monomictic lakes during July, 1973. No direct relationships were found between physiochemical conditions and species diversity. Of the 22 species of benthic organisms recorded, only four species were found in all the lakes. Mean species diversity (d) values for the lakes ranged from 0.735 to 1.731.     

Benthic microalgae in coral reef sediments of the southern Great Barrier Reef,Australia

The abundance and productivity of benthic microalgae in coral reef sediments are poorly known compared with other, more conspicuous (e.g. coral zooxanthellae, macroalgae) primary producers of coral reef habitats. A survey of the distribution, biomass, and productivity of benthic microalgae on a platform reef flat and in a cross-shelf transect in the southern Great Barrier Reef indicated that benthic microalgae are ubiquitous, abundant (up to 995.0 mg chlorophyll (chl) a m^–2), and productive (up to 110 mg O₂ m^–2 h^–1) components of the reef ecosystem. Concentrations of benthic microalgae, expressed as chlorophyll a per surface area, were approximately 100-fold greater than the integrated water column concentrations of microalgae throughout the region. Benthic microalgal biomass was greater on the shallow water platform reef than in the deeper waters of the cross-shelf transect. In both areas the benthic microalgal communities had a similar composition, dominated by pennate diatoms, dinoflagellates, and cyanobacteria. Benthic microalgal populations were potentially nutrient-limited, based on responses to nitrogen and phosphorus enrichments in short-term (7-day) microcosm experiments. Benthic microalgal productivity, measured by O₂ evolution, indicated productive communities responsive to light and nutrient availability. The benthic microalgal concentrations observed (92–995 mg chl a m^–2) were high relative to other reports, particularly compared with temperate regions. This abundance of productive plants in both reef and shelf sediments in the southern Great Barrier Reef suggests that benthic microalgae are key components of coral reef ecosystems.Communicated by Environmental Editor, B.C. Hatcher