A Scientometric Study of Foraminiferal Research in Brazil

ABSTRACT 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.

Benthic Meiofaunal Diversity in Four Zones of Pichavaram Mangrove Forest, India

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.

Review: Freshwater and Soil Foraminifera – A Story of Long-Forgotten Relatives

ABSTRACT 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.

Biovolume Method for Foraminiferal Biomass Assessment: Evaluation of Geometric Models and Incorporation of Species Mean Cell Occupancy

ABSTRACT 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.

Quantifying Late Pennsylvanian Multivariate Morphological Change in the Fusulinid Genus Triticites from the Central and Southwestern United States

ABSTRACT Fusulinid Foraminifera are important for biostratigraphic correlation of strata in the Upper Paleozoic of the central and southwestern United States due to their high abundance and diversity in shallow marine carbonates. These correlations rely on consistent species-level identifications as well as geographically consistent morphological variation within species. However, many taxonomically important characters are described qualitatively, which can lead to conflicting identifications among taxonomists and cause biostratigraphic disagreements. Quantitative morphometric comparisons among species can increase the consistency of identifications among workers and capture temporal and geographic morphological gradients. Here, we used 14 linear measurements to describe the morphology of 18 biostratigraphically important species within the genus Triticites. Canonical variates analysis (CVA) showed that whereas specimens of a given species occupy similar areas of morphospace, species overlap considerably and, thus, these linear measurements poorly differentiate among species. However, species morphology covaried with geological age and multivariate analyses focused on age differences reveal an increase in the size of the initial chamber (proloculus) and a relative decrease in test expansion along the long axes over time. These morphological changes are consistent with an adaptation to shallow water conditions following the fall in relative sea-level across the Virgilian-Newwellian/Bursumian transition. Given the consistency of the morphological shift among North American basins, these morphological changes may be more useful for the recognition of the Virgilian-Newwellian/Bursumian transition than species-level biozones because they do not depend on consistent species identification.

Growth and Fecundity of Marginopora Vertebralis and Amphistegina Lobifera in Laboratory Culture

ABSTRACT 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.

Oligocene Planktic Foraminiferal Taxonomy and Evolution: An Illustrated Revision of Ocean Drilling Program Site 803

ABSTRACT 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.