Beatriz Lima Vieira, Letícia Rizzetto Patrocínio, Douglas Villela de Oliveira Lessa, D. F. Gomes
Scientometrics is a field of study that involves measuring and analyzing scientific literature and can be a valuable tool to assess and reveal major gaps in national scientific production. Among the major challenges for Brazilian science is the development of research in the extensive national marine realm. This paper provides a scientometric survey of papers involving foraminiferal research in Brazil. The metrics utilized were papers listed in “Capes Portal” and “Scopus” databases up to the year of 2019. A total of 324 papers were found and 177 were selected based upon criteria established. A generalized additive model (GAM) was used to establish a relationship between publications and time. Studies involving foraminifera increased in Brazil from 1952 to 2019. Most studies have been conducted in the southeast region. We identified the need for more research on foraminifera to be carried out in the Brazilian continental margin, especially in the north and northeast regions of the country.
{"title":"A Scientometric Study of Foraminiferal Research in Brazil","authors":"Beatriz Lima Vieira, Letícia Rizzetto Patrocínio, Douglas Villela de Oliveira Lessa, D. F. Gomes","doi":"10.2113/gsjfr.51.4.267","DOIUrl":"https://doi.org/10.2113/gsjfr.51.4.267","url":null,"abstract":"\u0000 Scientometrics is a field of study that involves measuring and analyzing scientific literature and can be a valuable tool to assess and reveal major gaps in national scientific production. Among the major challenges for Brazilian science is the development of research in the extensive national marine realm. This paper provides a scientometric survey of papers involving foraminiferal research in Brazil. The metrics utilized were papers listed in “Capes Portal” and “Scopus” databases up to the year of 2019. A total of 324 papers were found and 177 were selected based upon criteria established. A generalized additive model (GAM) was used to establish a relationship between publications and time. Studies involving foraminifera increased in Brazil from 1952 to 2019. Most studies have been conducted in the southeast region. We identified the need for more research on foraminifera to be carried out in the Brazilian continental margin, especially in the north and northeast regions of the country.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49651314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Index to Volume 51, 2021","authors":"","doi":"10.2113/gsjfr.51.4.335","DOIUrl":"https://doi.org/10.2113/gsjfr.51.4.335","url":null,"abstract":"","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47317900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thaise Ricardo de Freitas, Eduardo Tadeu Bacalhau, S. T. Disaró
Foraminifers are widespread, highly abundant protists and active participants in marine carbon cycling. Their biomass might represent almost half of the total meiobenthic biomass in the deep sea. Foraminiferal biomass is frequently assessed through geometric models and biovolume estimates due to its non-destructive nature, which allows estimates of individuals from palaeoecological, museum, and living samples. To increase the accuracy of foraminiferal biovolume and biomass assessment we evaluate and propose geometric models for 207 foraminiferal taxa and the species’ average cell occupancy of the test. Individual test dimensions were measured to calculate volume (µm³), and the percent of cell occupancy (PCO) of the test was measured to assess the biovolume (µm³). These data were converted into individual biomass measurements (µg Corg ind−1). Our high intra- and interspecific PCO variance suggest that a mean PCO for each species represents the natural variability of occupancy more accurately than a predetermined fixed percentage for the whole assemblage, as previously asserted in the literature. Regression equations based on the relationship between test dimensions and volumes are presented. The geometric models, the PCO adjustment, and the equations will reduce time, effort, and discrepancies in foraminiferal biovolume and biomass assessments. Therefore, these results can improve the use and reliability of foraminiferal biomass in the future, facilitating its use in (1) distinct approaches including carbon flux estimations, (2) determining the effects of climate change on the marine trophic webs, and (3) environmental monitoring programs.
有孔虫是分布广泛、数量丰富的原生生物，是海洋碳循环的积极参与者。它们的生物量可能占深海中新生宙总生物量的近一半。有孔虫生物量经常通过几何模型和生物体积估算来评估，因为它是非破坏性的，这使得可以估计来自古生态、博物馆和活样本的个体。为了提高有孔虫生物体积和生物量评估的准确性，我们评估并提出了207个有孔虫类群的几何模型和实验中各物种的平均细胞占用率。测量单个测试尺寸以计算体积(µm³)，并测量测试的细胞占用率(PCO)以评估生物体积(µm³)。这些数据被转换成单个生物量测量值(µg / d - 1)。我们的高种内和种间PCO差异表明，每个物种的平均PCO比先前文献中断言的整个组合的预定固定百分比更准确地代表了占用的自然变异性。给出了基于测试尺寸与体积关系的回归方程。几何模型、PCO调整和方程将减少有孔虫生物体积和生物量评估的时间、精力和差异。因此，这些结果可以提高有孔虫生物量在未来的使用和可靠性，促进其在以下方面的应用:(1)不同的方法，包括碳通量估算;(2)确定气候变化对海洋营养网的影响;(3)环境监测计划。
{"title":"Biovolume Method for Foraminiferal Biomass Assessment: Evaluation of Geometric Models and Incorporation of Species Mean Cell Occupancy","authors":"Thaise Ricardo de Freitas, Eduardo Tadeu Bacalhau, S. T. Disaró","doi":"10.2113/gsjfr.51.4.249","DOIUrl":"https://doi.org/10.2113/gsjfr.51.4.249","url":null,"abstract":"\u0000 Foraminifers are widespread, highly abundant protists and active participants in marine carbon cycling. Their biomass might represent almost half of the total meiobenthic biomass in the deep sea. Foraminiferal biomass is frequently assessed through geometric models and biovolume estimates due to its non-destructive nature, which allows estimates of individuals from palaeoecological, museum, and living samples. To increase the accuracy of foraminiferal biovolume and biomass assessment we evaluate and propose geometric models for 207 foraminiferal taxa and the species’ average cell occupancy of the test. Individual test dimensions were measured to calculate volume (µm³), and the percent of cell occupancy (PCO) of the test was measured to assess the biovolume (µm³). These data were converted into individual biomass measurements (µg Corg ind−1). Our high intra- and interspecific PCO variance suggest that a mean PCO for each species represents the natural variability of occupancy more accurately than a predetermined fixed percentage for the whole assemblage, as previously asserted in the literature. Regression equations based on the relationship between test dimensions and volumes are presented. The geometric models, the PCO adjustment, and the equations will reduce time, effort, and discrepancies in foraminiferal biovolume and biomass assessments. Therefore, these results can improve the use and reliability of foraminiferal biomass in the future, facilitating its use in (1) distinct approaches including carbon flux estimations, (2) determining the effects of climate change on the marine trophic webs, and (3) environmental monitoring programs.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43900067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Punniyamoorthy, P. Murugesan, G. Mahadevan, A. Sánchez
The community structure of meiofauna was assessed relative to environmental parameters in four zones (non-mangrove, Avicennia zone, mixed zone, and Rhizophora zone) of Pichavaram Mangrove Forest, which is located along the southeast coast of India. Field sampling was carried out from June 2016–May 2017. The meiofaunal data were evaluated using univariate and multivariate statistics. The highest abundance of meiofauna (434 ind/10 cm−2) was recorded in the Rhizophora zone and the lowest (270 ind/10 cm−2) in the non-mangrove zone. A total of 62 species representing four meiofaunal groups were recorded, including 38 species of foraminifera, 12 species of nematodes, seven species of ostracods, and five species of harpacticoids. Diversity (Shannon H′) mostly ranged from 3–4, and was highest (3.86±0.26) in the Avicennia zone and averaged ∼3.3 in the other three zones. The Margalef richness index was ∼6 in the Avicennia and Rhizophora zones and ∼5 in the non-mangrove and mixed zones. The BIO-ENV and CCA analyses identified sediment texture and organic matter as key variables influencing the distribution of meiofauna, while % calcium carbonate, salinity, and sediment pH were also important. Monitoring studies of meiofaunal taxa may help elucidate their roles in coastal blue-carbon cycling and will also contribute to understanding how mangrove-associated habitats influence meiofaunal distributions.
{"title":"Benthic Meiofaunal Diversity in Four Zones of Pichavaram Mangrove Forest, India","authors":"R. Punniyamoorthy, P. Murugesan, G. Mahadevan, A. Sánchez","doi":"10.2113/gsjfr.51.4.294","DOIUrl":"https://doi.org/10.2113/gsjfr.51.4.294","url":null,"abstract":"The community structure of meiofauna was assessed relative to environmental parameters in four zones (non-mangrove, Avicennia zone, mixed zone, and Rhizophora zone) of Pichavaram Mangrove Forest, which is located along the southeast coast of India. Field sampling was carried out from June 2016–May 2017. The meiofaunal data were evaluated using univariate and multivariate statistics. The highest abundance of meiofauna (434 ind/10 cm−2) was recorded in the Rhizophora zone and the lowest (270 ind/10 cm−2) in the non-mangrove zone. A total of 62 species representing four meiofaunal groups were recorded, including 38 species of foraminifera, 12 species of nematodes, seven species of ostracods, and five species of harpacticoids. Diversity (Shannon H′) mostly ranged from 3–4, and was highest (3.86±0.26) in the Avicennia zone and averaged ∼3.3 in the other three zones. The Margalef richness index was ∼6 in the Avicennia and Rhizophora zones and ∼5 in the non-mangrove and mixed zones. The BIO-ENV and CCA analyses identified sediment texture and organic matter as key variables influencing the distribution of meiofauna, while % calcium carbonate, salinity, and sediment pH were also important. Monitoring studies of meiofaunal taxa may help elucidate their roles in coastal blue-carbon cycling and will also contribute to understanding how mangrove-associated habitats influence meiofaunal distributions.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46856261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Holzmann, A. Gooday, F. Siemensma, J. Pawłowski
Foraminifera are a primarily marine taxon widespread in all oceanic habitats, from shallow, brackish-water settings to deep-seafloor and pelagic realms. Their diversity is remarkable with several thousand species described and a fossil record tracing back to the Cambrian. While foraminifera represent one of the best-studied groups of marine meiofauna, much less is known about their non-marine relatives. The first freshwater foraminifera were described in the 19th century by European and North American protozoologists, but interest in them lapsed during much of the 20th century and was not rekindled until the advent of molecular systematics provided a fresh impetus to their study. Several new species, genera, and families have been described recently based on morphological and molecular data derived from cultured specimens. In parallel, environmental genomic studies revealed that foraminifera are highly diverse and ubiquitous in freshwater and soil environments. Molecular phylogenetic analyses places non-marine foraminifera in a few clades among the large array of single-chambered (monothalamous) lineages, suggesting that several independent colonization events of freshwater and terrestrial habitats occurred. Non-marine foraminifera are turning from obscure curiosities to being recognized as an important part of soil and freshwater microbial communities, a major component of these complex environments.
{"title":"Review: Freshwater and Soil Foraminifera – A Story of Long-Forgotten Relatives","authors":"M. Holzmann, A. Gooday, F. Siemensma, J. Pawłowski","doi":"10.2113/gsjfr.51.4.318","DOIUrl":"https://doi.org/10.2113/gsjfr.51.4.318","url":null,"abstract":"\u0000 Foraminifera are a primarily marine taxon widespread in all oceanic habitats, from shallow, brackish-water settings to deep-seafloor and pelagic realms. Their diversity is remarkable with several thousand species described and a fossil record tracing back to the Cambrian. While foraminifera represent one of the best-studied groups of marine meiofauna, much less is known about their non-marine relatives. The first freshwater foraminifera were described in the 19th century by European and North American protozoologists, but interest in them lapsed during much of the 20th century and was not rekindled until the advent of molecular systematics provided a fresh impetus to their study. Several new species, genera, and families have been described recently based on morphological and molecular data derived from cultured specimens. In parallel, environmental genomic studies revealed that foraminifera are highly diverse and ubiquitous in freshwater and soil environments. Molecular phylogenetic analyses places non-marine foraminifera in a few clades among the large array of single-chambered (monothalamous) lineages, suggesting that several independent colonization events of freshwater and terrestrial habitats occurred. Non-marine foraminifera are turning from obscure curiosities to being recognized as an important part of soil and freshwater microbial communities, a major component of these complex environments.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48406253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Dey, Amit K. Ghosh, A. K. Bhaumik, A. Chakraborty, S. Saxena, L. Roy
Thirty-two planktonic foraminiferal taxa have been identified based on Bright Field microscopic study as well as Scanning Electron Microscopy on the samples collected from the outcrop adjacent to the type section of Neill West Coast Formation at Neil Island of Ritchie's Archipelago, northern Indian Ocean. The planktonic foraminiferal taxa belong to ten genera viz., Dentoglobigerina, Globigerina, Globigerinoides, Globoconella, Globorotalia, Globorotaloides, Globoturborotalita, Neogloboquadrina, Orbulina, and Trilobatus. A number of statistical analyses have been done in addition to taxonomic study to interpret the palaeocenographic scenario. We performed PCA analysis on the foraminiferal content of the samples to test the relatedness. Two biozones have been established by Stratigraphically Constrained Cluster Analysis (CONISS). We used SHEBI (SHE analysis for biozone identification) analysis to precisely demarcate seven biozones. Attempts have been made to decipher the Plio–Pleistocene boundary in the Neill West Coast Formation based on specific zonal markers. The presence of some taxa (e.g., Globoconella inflata, Globigerina bulloides, and Neogloboquadrina pachyderma) indicates the initiation of a cooling event from late Pliocene onwards. An event of ocean upwelling also has been identified based on the presence of Globigerina bulloides, Neogloboquadrina pachyderma, and N. dutertrei from the late Pliocene to early Pleistocene of the northern Indian Ocean that also correlates with palaeoceanographic records known from other upwelling regions.
{"title":"Late Pliocene to Early Pleistocene Planktonic Foraminifera from Northern Indian Ocean (Andaman and Nicobar Islands): Interpretation on Cooling Event and Ocean Upwelling","authors":"R. Dey, Amit K. Ghosh, A. K. Bhaumik, A. Chakraborty, S. Saxena, L. Roy","doi":"10.2113/gsjfr.51.3.115","DOIUrl":"https://doi.org/10.2113/gsjfr.51.3.115","url":null,"abstract":"\u0000 Thirty-two planktonic foraminiferal taxa have been identified based on Bright Field microscopic study as well as Scanning Electron Microscopy on the samples collected from the outcrop adjacent to the type section of Neill West Coast Formation at Neil Island of Ritchie's Archipelago, northern Indian Ocean. The planktonic foraminiferal taxa belong to ten genera viz., Dentoglobigerina, Globigerina, Globigerinoides, Globoconella, Globorotalia, Globorotaloides, Globoturborotalita, Neogloboquadrina, Orbulina, and Trilobatus. A number of statistical analyses have been done in addition to taxonomic study to interpret the palaeocenographic scenario. We performed PCA analysis on the foraminiferal content of the samples to test the relatedness. Two biozones have been established by Stratigraphically Constrained Cluster Analysis (CONISS). We used SHEBI (SHE analysis for biozone identification) analysis to precisely demarcate seven biozones. Attempts have been made to decipher the Plio–Pleistocene boundary in the Neill West Coast Formation based on specific zonal markers. The presence of some taxa (e.g., Globoconella inflata, Globigerina bulloides, and Neogloboquadrina pachyderma) indicates the initiation of a cooling event from late Pliocene onwards. An event of ocean upwelling also has been identified based on the presence of Globigerina bulloides, Neogloboquadrina pachyderma, and N. dutertrei from the late Pliocene to early Pleistocene of the northern Indian Ocean that also correlates with palaeoceanographic records known from other upwelling regions.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47802660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Naidu, M. Ford, P. Kench, P. Hallock, R. Prasad
The shells of large benthic foraminifers (LBF) are key contributors to the development and maintenance of coastal landforms in the Pacific as well as to Paleogene and Miocene carbonates deposited along the Neotethys Seaway and tropical Pacific islands. The current study assessed growth and fecundity of two species, Marginopora vertebralis and Amphistegina lobifera, collected from sites in Viti Levu, Fiji, based on shell diameter, shell weight, fecundity, and survival. Specimens were cultured without supplemental nutrients or food for 15 months under controlled laboratory conditions. Physicochemical parameters, including salinity, alkalinity, pH, and temperature, varied by <5% throughout the experiment. Asexual reproduction by M. vertebralis produced ∼270 offspring per brood, while A. lobifera produced ∼500 offspring per brood. The minimum size at reproduction for M. vertebralis was 15 mm, and A. lobifera reproduction occurred at diameters ≥0.9 mm. These observations were consistent with those of previous studies that predicted asexual fecundity related to parent size. Four non-linear mathematical functions (exponential, Gompertz, logistic, and von Bertalanffy) were compared to describe the age-weight relationship for each species. Results revealed that the logistic model best fits M. vertebralis growth, and von Bertalanffy model best fits A. lobifera growth. The growth model for A. lobifera predicted trends in juvenile growth and maximum size consistent with a previously published von Bertalanffy model based on cultures in which the foraminifers were provided nutrient sources and grew much faster than those observed in this study. These observations support published hypotheses that many LBF are exceptionally well-adapted to extreme oligotrophy, a characteristic that accounted for their dominance as carbonate producers in the Paleogene and Miocene of the Neotethys and Pacific islands.
{"title":"Growth and Fecundity of Marginopora Vertebralis and Amphistegina Lobifera in Laboratory Culture","authors":"R. Naidu, M. Ford, P. Kench, P. Hallock, R. Prasad","doi":"10.2113/gsjfr.51.3.210","DOIUrl":"https://doi.org/10.2113/gsjfr.51.3.210","url":null,"abstract":"\u0000 The shells of large benthic foraminifers (LBF) are key contributors to the development and maintenance of coastal landforms in the Pacific as well as to Paleogene and Miocene carbonates deposited along the Neotethys Seaway and tropical Pacific islands. The current study assessed growth and fecundity of two species, Marginopora vertebralis and Amphistegina lobifera, collected from sites in Viti Levu, Fiji, based on shell diameter, shell weight, fecundity, and survival. Specimens were cultured without supplemental nutrients or food for 15 months under controlled laboratory conditions. Physicochemical parameters, including salinity, alkalinity, pH, and temperature, varied by <5% throughout the experiment. Asexual reproduction by M. vertebralis produced ∼270 offspring per brood, while A. lobifera produced ∼500 offspring per brood. The minimum size at reproduction for M. vertebralis was 15 mm, and A. lobifera reproduction occurred at diameters ≥0.9 mm. These observations were consistent with those of previous studies that predicted asexual fecundity related to parent size. Four non-linear mathematical functions (exponential, Gompertz, logistic, and von Bertalanffy) were compared to describe the age-weight relationship for each species. Results revealed that the logistic model best fits M. vertebralis growth, and von Bertalanffy model best fits A. lobifera growth. The growth model for A. lobifera predicted trends in juvenile growth and maximum size consistent with a previously published von Bertalanffy model based on cultures in which the foraminifers were provided nutrient sources and grew much faster than those observed in this study. These observations support published hypotheses that many LBF are exceptionally well-adapted to extreme oligotrophy, a characteristic that accounted for their dominance as carbonate producers in the Paleogene and Miocene of the Neotethys and Pacific islands.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46000664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite the extensive use of the benthic foraminiferal oxygen isotope composition (δ18O) as a proxy for paleoclimatic reconstructions, uncertainties remain regarding the consistency of interspecies offsets and the environmental factors controlling 18O fractionation. We investigated δ18O offsets of some frequently used Uvigerina, Bulimina, and Cibicidoides species in core top samples from different hydrographic and sedimentary regimes in the South China Sea, Makassar Strait, and Timor Strait/Eastern Indian Ocean. The δ18O values of the epifaunal taxa Cibicidoides mundulus and Cibicidoides wuellerstorfi showed no significant offset in all investigated regions, whereas shallow infaunal Cibicidoides species exhibited higher variability and were less reliable. We found no offsets between species of Uvigerina and Bulimina and assume that these genera can be measured together and/or substituted. Our results show that epifaunal taxa are close to equilibrium with ambient seawater and thus provide more reliable records of past ice volume and/or bottom water temperature variations than infaunal taxa. Offsets among equilibrium calcite, epifaunal taxa, and infaunal taxa are not constant “vital effects” but are influenced by changing gradients in bottom to pore water pH and carbonate ion concentrations that depend on deep-water ventilation and export flux of particulate carbonate and organic carbon. Offsets between epifaunal and infaunal taxa varied between 0.58 and 0.73‰, depending on regional bottom and pore water conditions. Our findings highlight the importance of regional and temporal variations in organic carbon flux/degradation and dissolution of calcite that may lead to slight under- or overestimates of the amplitude of δ18O fluctuations, especially during times of rapidly changing calcite-saturation of bottom and pore water.
{"title":"Oxygen Isotope Offsets in Deep-Water Benthic Foraminifera","authors":"Janika Jöhnck, A. Holbourn, W. Kuhnt, N. Andersen","doi":"10.2113/gsjfr.51.3.225","DOIUrl":"https://doi.org/10.2113/gsjfr.51.3.225","url":null,"abstract":"\u0000 Despite the extensive use of the benthic foraminiferal oxygen isotope composition (δ18O) as a proxy for paleoclimatic reconstructions, uncertainties remain regarding the consistency of interspecies offsets and the environmental factors controlling 18O fractionation. We investigated δ18O offsets of some frequently used Uvigerina, Bulimina, and Cibicidoides species in core top samples from different hydrographic and sedimentary regimes in the South China Sea, Makassar Strait, and Timor Strait/Eastern Indian Ocean. The δ18O values of the epifaunal taxa Cibicidoides mundulus and Cibicidoides wuellerstorfi showed no significant offset in all investigated regions, whereas shallow infaunal Cibicidoides species exhibited higher variability and were less reliable. We found no offsets between species of Uvigerina and Bulimina and assume that these genera can be measured together and/or substituted. Our results show that epifaunal taxa are close to equilibrium with ambient seawater and thus provide more reliable records of past ice volume and/or bottom water temperature variations than infaunal taxa. Offsets among equilibrium calcite, epifaunal taxa, and infaunal taxa are not constant “vital effects” but are influenced by changing gradients in bottom to pore water pH and carbonate ion concentrations that depend on deep-water ventilation and export flux of particulate carbonate and organic carbon. Offsets between epifaunal and infaunal taxa varied between 0.58 and 0.73‰, depending on regional bottom and pore water conditions. Our findings highlight the importance of regional and temporal variations in organic carbon flux/degradation and dissolution of calcite that may lead to slight under- or overestimates of the amplitude of δ18O fluctuations, especially during times of rapidly changing calcite-saturation of bottom and pore water.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44218516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Oligocene (33.9–23.0 Ma) has historically proven to be a difficult interval to examine with respect to planktic foraminifera; the tendency for many of the taxa to be basically globigerine in shape, with 4 or 5 chambers in the final whorl means differences between species are limited. Recently, an international working group has attempted to clarify the Oligocene planktic foraminiferal taxonomy, with the goal of establishing phylogenetically-consistent generic and species concepts. A relatively expanded and continuous Oligocene section recovered at Ocean Drilling Program Site 803 in the western equatorial Pacific was previously studied by Leckie et al. (1993) using fairly conservative species concepts. Since 1993, foraminiferal biostratigraphic datum age calibrations have changed, and so revised sedimentation rates for the 220-m thick Oligocene sequence are actually more constant than previously thought. As a part of the recent taxonomic revision, this site was reevaluated and numerous additional taxa are recorded at this location. Macroevolutionary rates are calculated from the occurrences, and increased extinction is found within the late Oligocene, counter to the expectations laid out in broader-scale macroevolutionary studies. An effort is made here to describe the diagnostic features, which can be used to distinguish all taxa under a standard binocular microscope. Finally, several figures of scanning electron microscope photomicrographs (from Site 803 and tropical Atlantic Ocean ODP Site 628) depict features used to describe and differentiate important, but difficult or homeomorphic taxa, with the hope that these figures can be used by other workers at the microscope attempting to do Oligocene taxonomy-based studies.
渐新世（33.9–23.0 Ma）在历史上被证明是一个很难对浮游有孔虫进行检查的时期；许多分类群的形状基本上是球形的，最后轮生有4或5个室，这意味着物种之间的差异是有限的。最近，一个国际工作组试图澄清渐新世浮游有孔虫的分类学，目的是建立系统发育上一致的属和种概念。Leckie et al。（1993）使用相当保守的物种概念。自1993年以来，有孔虫生物地层基准年龄校准发生了变化，因此220米厚渐新世层序的修正沉积速率实际上比以前认为的更恒定。作为最近分类学修订的一部分，对该地点进行了重新评估，并在该地点记录了许多额外的分类群。宏观进化率是根据这些事件计算出来的，在渐新世晚期发现了灭绝的增加，这与更大规模的宏观进化研究中提出的预期相反。本文致力于描述诊断特征，可用于在标准双目显微镜下区分所有分类群。最后，几张扫描电子显微镜显微照片（来自803号地点和热带大西洋ODP 628号地点）描绘了用于描述和区分重要但困难或同源分类群的特征，希望这些照片可以被显微镜下试图进行渐新世分类学研究的其他工作人员使用。
{"title":"Oligocene Planktic Foraminiferal Taxonomy and Evolution: An Illustrated Revision of Ocean Drilling Program Site 803","authors":"A. Fraass, R. Leckie","doi":"10.2113/gsjfr.51.3.139","DOIUrl":"https://doi.org/10.2113/gsjfr.51.3.139","url":null,"abstract":"\u0000 The Oligocene (33.9–23.0 Ma) has historically proven to be a difficult interval to examine with respect to planktic foraminifera; the tendency for many of the taxa to be basically globigerine in shape, with 4 or 5 chambers in the final whorl means differences between species are limited. Recently, an international working group has attempted to clarify the Oligocene planktic foraminiferal taxonomy, with the goal of establishing phylogenetically-consistent generic and species concepts. A relatively expanded and continuous Oligocene section recovered at Ocean Drilling Program Site 803 in the western equatorial Pacific was previously studied by Leckie et al. (1993) using fairly conservative species concepts. Since 1993, foraminiferal biostratigraphic datum age calibrations have changed, and so revised sedimentation rates for the 220-m thick Oligocene sequence are actually more constant than previously thought. As a part of the recent taxonomic revision, this site was reevaluated and numerous additional taxa are recorded at this location. Macroevolutionary rates are calculated from the occurrences, and increased extinction is found within the late Oligocene, counter to the expectations laid out in broader-scale macroevolutionary studies. An effort is made here to describe the diagnostic features, which can be used to distinguish all taxa under a standard binocular microscope. Finally, several figures of scanning electron microscope photomicrographs (from Site 803 and tropical Atlantic Ocean ODP Site 628) depict features used to describe and differentiate important, but difficult or homeomorphic taxa, with the hope that these figures can be used by other workers at the microscope attempting to do Oligocene taxonomy-based studies.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45487273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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