Living benthic foraminifera from El Ferrol Bay: A pollution critical area in northern-central Peru

The study focused on the assemblage of 'living' benthic foraminifera (stained with Rose Bengal) in the surface sediments of El Ferrol Bay (Chimbote, 9°S). Twelve sampling sites were selected at depths ranging from 4.5 to 27 meters in September 2015. Water samples were collected near the seafloor to determine dissolved oxygen (DO), pH, and nutrient (nitrate and phosphate). Sediment samples were analysed for total organic matter (TOM) and the chlorophyll-a to phaeopigment ratio (chl-a/phaeo. Our findings confirm that this bay experiences hypoxic conditions at the seafloor (~2 mL/L) in addition to high dissolved nitrate levels. The assemblage was primarily composed of hyaline calcareous species, a porcelaneous calcareous species, and a soft-shelled foraminiferal species. Densities ranged from moderate to high, with the calcareous species Bolivina costata being the dominant species and B. elegantissima co-dominant in most sites. Based on our analysis, no significant differences were observed between the assemblages of living benthic foraminifera in the inner and outer bay. However, the influence of bottom nitrates on shallow-water foraminiferal species was notable. These results provide a baseline reference for future monitoring and calibration studies.

Se estudió el ensamble de foraminíferos bentónicos 'vivos' (teñidos con Rosa de Bengala) en los sedimentos superficiales de la bahía El Ferrol (Chimbote, 9 °S). Se muestrearon 12 sitios con profundidades entre 4.5 y 27 m, en setiembre de 2015. Se colectaron muestras de agua cerca al fondo para determinar la concentración de oxígeno disuelto, pH y nutrientes (nitratos y fosfatos); muestras de sedimentos para analizar el tamaño de grano, la materia orgánica total (MOT) y la razón clorofila-a feopigmentos (cl-a/feop). Nuestros resultados confirman que esta bahía está sometida a concentraciones hipóxicas de fondo (~2 mL/L), además de un alto contenido de nitratos disueltos. El ensambe estuvo compuesto mayoritariamente por el grupo de los calcáreos hialinos, una especie de calcáreo porcelanado y una especie de foraminíferos de pared blanda. Las densidades fueron de moderadas a elevadas, la especie calcárea Bolivina costata fue la especie dominante y B. elegantissima fue la codominante en la mayoría de los sitios. En base a nuestro análisis, no se observaron diferencias entre el ensamble de foraminíferos bentónicos vivos de la bahía interior y la exterior, pero destacan la importancia de los nitratos del fondo para las especies de foraminíferos de aguas poco profundas. Nuestros resultados proporcionan una línea de base de referencia para futuros estudios con fines de seguimiento y calibración.

Ostracoda and foraminifera from Paleocene (Olinda well), Paraíba Basin, Brazilian Northeast

ABSTRACT Paleocene ostracods and planktonic foraminifera from the Maria Farinha Formation, Paraíba Basin, are herein presented. Eleven ostracod species were identified in the genera Cytherella Jones, Cytherelloidea Alexander, Eocytheropteron Alexander, Semicytherura Wagner, Paracosta Siddiqui, Buntonia Howe, Soudanella Apostolescu, Leguminocythereis Howe and, probably, Pataviella Liebau. The planktonic foraminifera are represented by the genera Guembelitria Cushman, Parvularugoglobigerina Hofker, Woodringina Loeblich and Tappan, Heterohelix Ehrenberg, Zeauvigerina Finlay, Muricohedbergella Huber and Leckie, and Praemurica Olsson, Hemleben, Berggren and Liu. The ostracods and foraminifera analyzed indicate an inner shelf paleoenvironment for the studied section. Blooms of Guembelitria spp., which indicate either shallow environments or upwelling zones, were also recorded reinforcing previous paleoenvironmental interpretations based on other fossil groups for this basin.

Planktic foraminiferal diversity: logistic growth overprinted by a varying environment / Diversidad en foraminíferos planctónicos: crecimiento logístico sobrepuesto por un ambiente variable

This study statistically assesses the relationship between the planktic foraminiferal long-term diversity pattern (~170 Ma to Recent) and four major paleobiological diversification models: (i) the 'Red Queen' (Van Valen, 1973; Raup et al., 1973), (ii) the turnover-pulse (Vrba, 1985; Brett and Baird, 1995), (iii) the diversity-equilibrium (Sepkoski, 1978; Rosenzweig, 1995), and (iv) the 'complicated logistic growth' (Alroy, 2010a). Our results suggest that the long-term standing diversity pattern and the interplay between origination and extinction rates displayed by this group do not correspond to the first three models, but can be more readily explained by the fourth scenario. Consequently, these patterns are likely controlled by a combination of planktic foraminiferal interspecific competition as well as various environmental changes such as marine global temperatures that could impacted the niches within the upper mixed layer within the oceans. Moreover, as other global long-term patterns have been interpreted as reflecting 'complicated logistic growth', this study further suggests that the interplay between abiotic and biotic factors are fundamental elements influencing the evolutionary processes over the extensive history of the biota.

Este estudio evalúa estadísticamente la relación entre el patrón de diversidad global de los foraminíferos planctónicos en el largo plazo (~170 Ma al Reciente) y los cuatro modelos de diversificación propuestos desde la rama de la paleobiología: (i) "Reina Roja" (Van Valen, 1973; Raup et al., 1973), (ii) remplazo pausado (Vrba, 1985; Brett y Baird, 1995), (iii) diversidad en equilibrio (Sepkoski, 1978; Rosenzweig, 1995), y (iv) el "crecimiento logístico complicado" (Alroy, 2010a). Nuestros resultados sugieren que la forma de este patrón global de diversidad y la inter-relación entre las tasas de extinción y originación de este grupo no corresponden con los primeros tres modelos anteriormente citados. Sin embargo, estos pueden ser explicados bajo el cuarto escenario. Consecuentemente, las dinámicas de diversidad (i.e. patrón de diversidad y tasas de extinción y originación) de este grupo posiblemente son controladas por la combinación de la competencia interespecífica de los foraminíferos planctónicos y varios cambios ambientales tales como temperaturas globales marinas que pudieron impactar el número de nichos dentro de la capa superior de los océanos. Además, otros patrones globales de diversidad en el largo plazo han sido interpretados como el reflejo del modelo de crecimiento logístico complicado, lo que sugiere que la relación entre factores abióticos y bióticos tiene un carácter fundamental en los procesos evolutivos que han sucedido a lo largo de la historia de la vida.

Comparative study on foraminifera of east and west coast of India.

The oceanographic conditions of west and east coasts of India provide variations in ecological conditions. Hence, the present study was undertaken to assess the geographic distribution and diversity of foraminifera (Protista) of west and east Coasts of India to gain insights in to ecological conditions that effect their distribution. The intertidal sediment samples, collected for a period of two years from October 2004 to September 2006 were analysed for foraminiferal diversity and sediment characteristics by standard methods. Relatively high densities (west coast -156 to 19,400 g-1, east coast – 37-214 g-1) and diversities were observed at all the sites of the West (74 species) compared to the east coast (57 species). Thirty three species were common to both the coasts. Forty one and 24 species were found to be unique to west and east coast, respectively. Foraminifera of west and east coasts form distinct clusters as revealed by Bray-Curtis cluster analysis, indicating distinctly different foraminiferal assemblages. The geographical and oceanographic conditions thus seem to influence a differential diversity of forams.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages / Registro do gradiente latitudinal, de descargas de rios e de massas de água ao longo da costa subtropical da América do Sul, utilizando-se associações de foraminíferos bentônicos

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Mais de 30% de dominância de Buccella peruviana, Globocassidulina crassa porrecta, Cibicides mackannai e C. refulgens indica a presença de água fria da Corrente Subantártica de plataforma no inverno entre 33,5-38,3º S, principalmente no setor sul da area estudada. No verão, no entanto, nas estações mais profundas do que 100 m, a abundância dessa associação diminui para menos de 15% em torno de 37,5-38,9º S, onde duas espécies (Globocassidulina subglobosa e Uvigerina peregrina) dominam. G. subglobosa, U. peregrina e Hanzawaia boueana são encontradas principalmente em menos de 55 m de profundidade na parte norte da área (27-33º S), tanto no inverno como no verão, e estão relacionadas com águas mais quentes de Plataforma Subtropical e de Água Tropical. Em quatro áreas da plataforma continental, foi observada a influência de aporte continental com alta concentração de silicato no sedimento. Essa influência é detectada pela presença de Pseudononion atlanticum, Bolivina striatula, Buliminella elegantissima, Bulimina elongata, Elphidium excavatum, E. poeyanum, Ammobaculites exiguus, Arenoparrella mexicana, Gaudryina exillis, Textularia earlandi e tecamebas. A presença de Bulimina marginata entre 34,1-32,8º S no inverno e 34,2-32,7º S no verão indica que a influência da Frente Subtropical Plataforma sobre os sedimentos não muda sazonalmente; mas, por outro lado, a presença de Angulogerina angulosa no inverno, apenas na estação mais profunda de Mar del Plata (38,9º S), mostra que as correntes das Malvinas não estão influenciando o sedimento dessa região no verão.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Mais de 30% de dominância de Buccella peruviana, Globocassidulina crassa porrecta, Cibicides mackannai e C. refulgens indica a presença de água fria da Corrente Subantártica de plataforma no inverno entre 33,5-38,3º S, principalmente no setor sul da area estudada. No verão, no entanto, nas estações mais profundas do que 100 m, a abundância dessa associação diminui para menos de 15% em torno de 37,5-38,9º S, onde duas espécies (Globocassidulina subglobosa e Uvigerina peregrina) dominam. G. subglobosa, U. peregrina e Hanzawaia boueana são encontradas principalmente em menos de 55 m de profundidade na parte norte da área (27-33º S), tanto no inverno como no verão, e estão relacionadas com águas mais quentes de Plataforma Subtropical e de Água Tropical. Em quatro áreas da plataforma continental, foi observada a influência de aporte continental com alta concentração de silicato no sedimento. Essa influência é detectada pela presença de Pseudononion atlanticum, Bolivina striatula, Buliminella elegantissima, Bulimina elongata, Elphidium excavatum, E. poeyanum, Ammobaculites exiguus, Arenoparrella mexicana, Gaudryina exillis, Textularia earlandi e tecamebas. A presença de Bulimina marginata entre 34,1-32,8º S no inverno e 34,2-32,7º S no verão indica que a influência da Frente Subtropical Plataforma sobre os sedimentos não muda sazonalmente; mas, por outro lado, a presença de Angulogerina angulosa no inverno, apenas na estação mais profunda de Mar del Plata (38,9º S), mostra que as correntes das Malvinas não estão influenciando o sedimento dessa região no verão.