Innovative strategies led by pharmacists to counter the escalating threat of antimicrobial resistance

Corresponding author: Celestine Nwite Nwojiji Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Evidence of traits and faunal turnover in planktonic foraminifera during extreme climate: A biological Traits Analysis approach Celestine NwiteNwojiji 1, 2, *, Fabienne Marret 1, Godwin Nwonumara Nkwuda 3 and Norbert I. Nnakenyi 4 1 Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, UK. 2 Department of Geology, Faculty of Science, Ebonyi State University, Abakaliki, Nigeria. 3 Department of Applied Biology, Faculty of Science, Ebonyi State University, Abakaliki, Nigeria. 4 Upstream Investment Management Services, Nigerian National Petroleum Company Limited, Lagos, Nigeria. World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 Publication history: Received on 09 June 2025; revised on 14 July 2025; accepted on 17July 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.27.1.2697 Abstract The Palaeocene-Eocene Thermal Maximum (PETM) is a paleoclimatic event associated with massive radiation and the extinction of planktonic foraminifera. It is still unclear which planktonic foraminiferal attribute was responsible for its enormous turnover during the PETM event. It has been hypothesized that biotic interaction with the environment is driven by biological traits rather than faunal composition. This idea stimulated this research where a combination of faunal composition and biological traits of planktonic foraminifera from Ocean Drilling Program (ODP) Site 1265 (Walvis Ridge, SE Atlantic Ocean) were used to understand the planktonic foraminiferal attribute responsible for biotic turnover during the PETM. Our results show that the studied section cut across three planktonic foraminiferal (PF) zones namely Morozovella valescoensis, Pseudohastigerina wilcoxensis, and Morozovella marginodentata dated 54.5 – 55.5 Ma. The faunal occurrence showed high variability in abundance and diversity with the last appearance (local extinction) of nineteen (19) species and the first appearance of eight (8) species including Globoturborotalita bassriverensis. Statistical analyses showed that the faunal compositions of the recovered planktonic foraminifera differed across the three sections of the PETM. Multivariate analyses of the faunal and trait compositions suggest evidence of disturbance in planktonic foraminiferal ecology during the PETM. The key foraminiferal traits that increased in abundance during the extreme climate event were triangular/trapezoid chamber arrangement, muricate wall texture, presence of accessories like lip in the aperture, umbilical and extraumblical apertures, perforations in the test wall, grazing and surface-dwelling habits. These traits are believed to characterize resilient types that enabled taxa to survive the PETM. Keywords: Extreme climate; Extinction; Paleoclimate; Planktonic foraminifera; Traits 1. Introduction With the rapid changes in global marine ecosystems resulting from anthropogenic interplay (e.g., excessive input of greenhouse gases; destruction of natural habitat; environmental pollution) and natural evolution, climate scientists have forecasted extreme climatic conditions for the next few millennia [1, 2].The imminent extreme climate could lead to global mass extinction that will permanently alter the current climate system. To understand how this extreme climate will affect the oceans in the future and in particular one of the most important producers (foraminifera) in the marine ecosystem. This study has become necessary to investigate a similar paleoclimatic event known as the Palaeocene – Eocene Thermal Maximum (PETM) which is believed to be similar in magnitude and rate of greenhouse emission as present values. The PETM is a globally recognizable event that occurred 55 – 56 million years ago. The event is reported to have been caused by a massive injection of light carbon into the Earth’s system [3] and coincided with World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1831 eccentricity maxima [4]. The event is characterized by 2 - 3‰ carbon isotopic excursion (CIE), extensive acidification of the deep ocean that led to the burn down of existing calcite deposits in the ocean and a significant rise in the lysocline and carbon compensation depth (CCD) [5, 6]. The PETM also had a significant effect on marine ecosystem faunal turnover such as the massive extinction of benthonic foraminifera, diversification and migration of planktonic foraminifera [7]. Foraminifera are unicellular marine protozoans with calcareous shells usually subdivided into chambers. They are the most important calcifying zooplankton group [8] and provide crucial ecological functions in the oceans such as primary production, nutrient cycling, carbon sequestration, and a food source to numerous organisms in the higher trophic level of marine ecosystems. Foraminifera are divided into planktonic and benthonic taxa based on where they live in the water column. Benthonic foraminifera live either above (epifauna) or below (infauna) the sediment-water interface in water depths ranging from the intertidal zone to the deep ocean [9]. Planktonic foraminifera, which is the focus of the study, live in the euphotic zone while some live deeper down to approximately 2 km water depth in the oceans, during their lifetime [10]. The test of planktonic foraminifera are made of relatively globular chambers essential to buoyancy, which enables their distribution spatially and temporally across the water column [10]. Foraminifera are known to be very sensitive to the physio-chemical variability in the oceans. They tend to incorporate the physical and chemical signature of the seawater in which they have calcified their shells, thereby recording the prevailing environmental conditions. The chemical composition of foraminifera tests is used as a proxy for the interpretation of palaeoecological and palaeoclimatic conditions such as temperature, carbon saturation, salinity, palaeocirculation, oxygen concentration, and hydrodynamics during their lifetime [11,12, 13,14, 15, 16, 10]. The physiological makeup (traits) of foraminifera plays a huge role in the survival strategies they adopt while alive and has been demonstrated in fossil as well as modern species records to have a close relationship with environmental parameters [17]. Several palaeoecological studies have linked spatial and temporal variations in the ocean to the morphological stratification of foraminiferal ecosystems both at the pelagic and benthic zones [18, 19, 10]. In the modern oceans, the planktonic foraminifera found in the mixed layer of the surface water is dominated by rounded globular test, such as in Globigerinids with algal symbionts while the species found deeper below the thermocline are predominantly characterized by traits such as flattened discoidal, or conical forms representing Globorotalids morphologies with herbivorous feeding habits [20]. Traits are believed to have a stronger control on the organism's interaction within their ecological community than taxonomic composition. Foraminiferal traits are intrinsically linked to the ecological functions they perform in the ocean. For instance, test composition functions as a protective tool and is known to reduce biological, physical, and chemical stresses of foraminifera in their environment [21]. The test shape could also indicate ecological adaptation and preference by foraminifera. The arrangement of the test chambers and their shape could also indicate ecological stress. For instance, changes from sinistral to dextral or evolute to involute coiling in trochospiral tests have been related to changes in water temperature and bathymetry [22]. Elements of test microstructure such as the macroornamentation (e.g. spines or muricae) could also reflect the mode of living and adaptation to surrounding water conditions. Ornamentation in foraminifera plays a huge role in feeding, adaptation to extreme environmental conditions and movement as well as prey-predation relationship [23]. Pores in foraminifera are used for gas exchange, osmoregulation, intake and release of nutrients, and ecosymbiosis. Because foraminifera play significant roles in the global carbon sequestration and food supply, it is important to understand their feedback to past climatic extremes. The response of foraminifera to past climatic changes will provide useful clues to the current and future climatic changes. To achieve this aim, we have selected a suitable location in the southeastern Atlantic Ocean drilled during the ODP campaign, Leg 208 site 1265 (Figure 1). This Site is located at an upper bathyal water depth of 3,083m [24] in a broad channel at the base of the westward trending slope of the Walvis Ridge. The channel contains a thick sequence of Palaeogene to Neogene sedimentary deposits and the section analyzed is composed of foraminifer-bearing nannofossil oozes with red clay layer recording the main CIE interval. ODP Leg 208 was the first site to recover an intact and undisturbed continuous sequence of Palaeocene – Eocene (P/E) boundary in the deep-sea drilling because of the drilling strategy that adopted advanced piston corer (APC) techniques. However, there was a poor recovery of the lower part of the PETM at site 1265A [24]. World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1832 Figure 1 The site location of the study area as modified from the European Space Agency map archive The objective of this paper is to investigate changes in faunal and trait composition across the PETM at ODP site 1265A using a procedure known as the Biological trait analysis (BTA) that allows the traits of organisms to be quantified. Here we generate foraminiferal population and trait data across the late Palaeocene-early Eocene section at ODP Site 1265A to examine the planktonic foraminiferal assemblages and trait composition across the hyperthermal event in the site. Use the data to understand foraminiferal sensitivity to extreme climatic conditions and integrate the planktonic faunal assemblage and trait compositions to interpret the ecological functioning of foraminifera in the SE Atlantic Ocean during the PETM. The key focus of this research is to investigate the changes in trait and faunal composition of planktonic foraminifera during the Paleocene-Eocene Thermal Maximum (PETM) at ODP Site 1265 using the biological trait analysis (BTA); a technique that allows traits of organisms to be measured and quantified. The sediments used for this study were sampled from Hole 1265A of ODP Leg 208 at the Walvis Ridge in the South Atlantic Ocean. The BTA was initially designed to study the impact of ecological disturbance in the terrestrial [25, 26, 27] and marine macrobenthic ecosystem [28, 29, 30, 31, 32, 33]. The technique tends to be good in detecting the impact of anthropogenic disturbance in these ecosystems. Biological trait analysis has also been applied in investigating the impact of extreme ecological conditions on the functioning of fossil macrobenthos in deep time. For instance, [34] applied the method in the study of the impact of hypoxia (low oxygen) in the ecological functioning of fossil macro benthos (bivalve, mollusks, gastropods, brachiopods, and echinoderms) from the late Jurassic Kimmeridge Clay Formation in the Wessex Basin, United Kingdom. The results from this study showed that extreme climatic conditions could lead to a collapse of ecologic function in marine niches. With results from previous studies using the BTA method, the authors deployed it in investigating the impact of the extreme PETM conditions on the traits and faunal composition of foraminifera (microfossil). The current method (BTA) has not been previously used in planktonic foraminiferal studies, also the taxonomic composition of Planktonic foraminifera during the PETM at Hole 1265A has not been previously studied, and this work documents this and investigates the impact of the hyperthermal event on their traits. The trait analysis is important because foraminifera interactions with other organisms in their community are driven by biological traits instead of faunal composition [35, 36]. 2. Methodology Thirty-five sediment samples from core depths 266.31 mbsf – 276.66 mbsf were selected at 510 cm intervals and analyzed for foraminiferal abundance and distribution across the PETM section. World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1833 2.1. Foraminiferal Preparation Foraminiferal sample preparation followed conventional protocols. Deep sea sediment samples from IODP were weighed using a weighing balance and were transferred into the 250ml glass beaker with sterilized water and soaked overnight in a fume cupboard. This is for the sediment to disaggregate and for the clays to be dissolved. The disaggregated sediments were washed with Endecotts stainless steel 63µ sieve under running tap water. The recovered residues were transferred to a labelled filter paper placed in a funnel and dried in the laboratory oven. The dried residue was stored in vials for identification and counting. 2.1.1. Foraminiferal counting and identification The recovered microfossils were sieved into three fractions,> 63µm (fine),>125µm (medium), and >250 µm (coarse). Each size fraction was counted separately to prevent the larger microfossils from obstructing the smaller ones. Counting was done by sparingly spraying the microfossil on the observation tray. The observation tray is divided into forty –two equal-sized squares and 1-2 portions of microfossil-filled trays were counted for each sample by following systematically along a particular transect. Because the number of planktonic foraminifera in the sediment was large, over 1000specimens were counted in one fraction. Counting the fine fraction (>63-125µ) was useful because many species of Chiloguembellina and Globanomalina, which were scarce in the larger fraction were abundant in the fine fraction. Most of the taxa were identified at the species level using the systematic description and micrographs from [37, 38, 39, 40, 41] and other peer reviewed-publications cited herein. 2.2. Trait classification and analytical procedures Biological trait analysis[BTA; 6, 34]) is the novel method used in this work. It uses multivariate ordination such as nonmetric multi-dimensional scaling (nmMDS) and Similarity percentage analysis (SIMPER)to examine the patterns of biological trait composition across taxa assemblages(i.e. the types of trait present in assemblages and the relative frequency with which they occur).The approach was used to understand the dominant traits that sustained the planktonic foraminiferal species' existence or extinction in the Atlantic Ocean during the Palaeocene-Eocene thermal maximum. The planktonic foraminiferal traits such as composition, morphology, and life strategy were classified into thirteen biological characteristics based on ecological functions/ responses,and the availability of data on the traits. These foraminiferal traits were further classified into categories and referred to as modalities (Table 1). After categorizing the traits into modalities, the Fuzzy coding [42] technique was used in expressing the affinity of various species to the trait modalities using a scale of 0.0 – 1.0. The absence or no affinity of a particular trait in a species is denoted with 0 while 1 is used for a species that exhibited dominant/ high affinity to a trait (see supplementary data). This coding technique allows each species that exhibited more than one modality to be categorized according to their affinity to the trait under consideration, however, all the categories shall sum up to unity [34, 43]. The information on the biological traits was sourced from the biological database such as Mikrotax https://www.mikrotax.org/pforams/, WORMS – World Register of Marine Species: http://www.marinespecies.org, The Palaeobiology http://palaeodb.org; Fossilworkshttp://fossilworks.org/ and published literature. The extensive review of these data sources as well as personal communications with experts in a range of taxa informed the choice of traits selected for this analysis. Table 1 Foraminiferal traits and modalities used in Fuzzy coding Traits Modalities A. Test Shape A1. Spiral; A2. Elongate; A3. Globose; A4. Subquadrate; A5. Others B. Test Composition B1. Microgranular; B2. Hyaline calcite; B3. Hyaline aragonite; B4. Porcellanous; B5. Other C. Chamber arrangement C1. Uniserial; C2. Bi/Tri-serial; C3. Planispiral; C4. Trochospiral; C5. Other D. Chamber shape D1. Spherical/Oval; D2. Tubular; D3. Triangular or trapezoidal; D4. Semi-circular; D5. Others E.Wall texture E1. Depressed sutures; E2. Raised sutures; E3. Cancellate; E4. Muricate; E5. Spinose; E6 Smooth F. Test micro-ornamentation F1. No ornament; F2. Reticulate; F3. Limbate; F4. Striate; F5. Costae G. Aperture form G1. Oval/reniform; G2. Arcuate; G3. Radiate; G4. Slit-like World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1834 H. Aperture accessory structures H1. Lips; H2. Bifid teeth; H3. Umbilical teeth; H4. Neck; H5. None I. primary aperture position I1. Terminal; I2. Basal interiomarginal; I3. Umbilical; I4. Extra-umbilical; I5. Areal J. Test perforation J1. Microperforation; J2. Fine perforation; J3. Macro-perforation; J4. No perforation K. Life habit K1. Surface dweller; K2. Intermediate dwellers; K3. Deep water dwellers; K4. Others L. Feeding habit L1. Grazer, L2; Suspension feeder; L3. Detrital feeder; L4. Symbiotic M. Mobility M1. Swimming; M2. Clinging; M3. Drifting; M4. Free-living The frequency of each trait modality in the dataset was calculated by multiplying the category scores with the relative abundance of each species exhibiting those modalities. This was achieved by a simple matrix multiplication method [43, 44]. The result of this data treatment showed the relative abundance of all the biological traits recorded in all the species across the whole samples [6, 45]. Statistical analyses of both the species composition and biological trait datasets were performed with the software PRIMER ver. 6. [46]. All the counted foraminiferal taxa/traits were grouped into three PETM communities (Pre-CIE, CIE, and Recovery) according to their position in the sample relative to the hyperthermal based on δ13C from [47]. The relative abundance of foraminiferal and trait similarities across the PETM was calculated using the Bray-Curtis index resemblance matrix. The resemblance data were transformed with Log (x+1). A Log (x+1) modified the relative abundance/traits of the species to reduce the influence of the dominant species on the data [46]. The taxa abundance data were standardized before any transformation (following the BTA procedure; [46]; however, trait data were not subjected to this procedure because it had been standardized during the fuzzy coding process [6, 34]. The transformed data were plotted with non-metric multidimensional scaling ordination (nmMDS) based on the Bray – Curtis similarity matrices [46]. The nmMDS is based on the rank similarities of samples and produced an ordination plot showing relative differences/ resemblance in biological trait or faunal composition across the PETM (see Figures 3 & 4). To test for significant differences between various traits and faunal composition across the three PETM sections, analysis of similarity (ANOSIM) tests were performed on the data set. The similarity of percentages (SIMPER) analysis was also applied to the species abundance and biological traits to determine which species/traits accounted for the significant dissimilarities identified by the ANOSIM test. 3. Results 3.1. Planktonic foraminiferal distribution and changes through time A total of 79,706 planktonic foraminifera specimens were counted from the core in Hole 1265A, across the PETM. These represent fifty-nine (59) species with Acarininidae, Morozovellidae, Subbotinidae, Chiloguembellinidae, and Globanomalinidae being the dominant taxa. 3.1.1. Planktonic foraminifera taxa across the Pre-CIE section The faunal composition showed that the pre-CIE interval (276.66 - 275.19 mbsf; latest Palaeocene) was marked by the restricted occurrences of Acarinina nitida, Acarinina strabocella, Chiloguembellina morsei, C. wilcoxensis, Globanomalina australiformis, G. compressa, G. pseudomenardii, Globanomalina planoconica, Morozovella pasionensis, M. velascoensis, M. angulata, Parasubbotina pseudobulloides, Parasubbotina varianta, Subbotina cancellata, Subbotina triangularis, S. triloculinoides and S. trivalis (see Figure 3). The pre-CIE interval was characterized by high abundances of all the major taxa with relatively good preservation. The genera Acarinina, was the most abundant taxa in this interval; followed by Subbotina and Globanomalina, while Morozovella was the least abundant (Figure 3). World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1835 Table 2 Mean abundance of taxa dissimilarity between recovery and CIE (data was limited to 50% cumulative similarity) Species Foraminiferal mean abundance Contribution to dissimilarity (%) REC CIE Morozovella spp. 5.15 26.02 17.78 Acarinina Spp 1.28 12.27 8.50 Chiloguembelina trinitatensis 11.98 2.78 7.48 Subbotina patagonica 10.95 3.89 6.17 Morozovella subbotinae 10.58 5.09 6.10 Globoturborotalita bassriverensis 9.75 2.14 6.03 Table 3 Mean abundance of taxa dissimilarity between Recovery and Pre-CIE from Simper analysis. Species Foraminiferal mean abundance Contribution to dissimilarity (%) REC Pre CIE Chiloguembelina trinitatensis 11.98 2.93 7.72 Globoturborotalita bassriverensis 9.75 0.00 7.36 Morozovellas ubbotinae 10.58 2.78 6.18 Subbotina Spp 1.70 8.51 5.76 Subbotina patagonica 10.95 6.11 5.38 Acarinina Spp 1.28 7.71 5.13 Acarininainterposita 7.33 3.37 5.02 Morozovella aequa 0.00 6.25 4.72 Chiloguembelina crinita 6.10 3.73 3.97 Table 4 Mean abundance of taxa dissimilarity between pre-CIE and CIE from simper analysis. Species Foraminiferal mean abundance Contribution to dissimilarity (%) CIE Pre CIE Morozovella spp. 26.02 5.76 17.79 Acarinina spp 12.27 7.71 7.27 Acarinina Soldadoensis 14.58 6.71 6.46 Subbotina Spp 1.50 8.51 5.48 Subbotina patagonica 3.89 6.11 4.61 Acarinina coalingensis 2.86 6.84 4.34 Acarinina nitida 5.25 5.03 4.30 World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1836 3.1.2. Planktonic foraminifera taxa across the CIE section The CIE interval was marked by a significant reduction in the abundance and preservational quality of all the species present. The subbotinidae family (which included taxa like Parasubbotina and Globoturborotalita) decreased from 500,000 at the Pre-CIE to less than 100 at the CIE interval (foraminiferal abundance). Nineteen (19) planktonic foraminiferal species including A. nitida, M. aequa, S. trivalis, G. chapmani, G. pseudomenardii, S. triangularis, S. cancellata, P. pseudobulloides, G. planoconica, M. occlusa, C. morsei, W. claytonensis, S. valescoensis, M. passionensis, S. triloculinoides, M. acuta, M. acutispira and A. strabocella became locally extinct at Site 1265A (Figure 2). The First appearance of eight (8) taxa was recorded within the CIE interval (Figure 2). The interval was characterised by high abundances of Morozovella acutispira, Morozovella aequa, Morozovella gracilis, Morozovella spp., Acarinina spp., and Subbotina spp. No excursion taxa were recorded in the interval of main carbon isotopic excursion in this section as reported in the Pacific, Tethys, and continental seas[48, 49,12]. However, Globoturborotalita bassriverensis which has been reported as an excursion species in the PETM section of Bass River [51) made its first appearance at 275.19 mbsf. Acarinina sibaiyaensis widely reported as excursion taxon was found in the later part of the Recovery interval (Figure 2). 3.1.3. Foraminiferal Assemblages in the Recovery section The Recovery interval occurs between 274.5–266.6 mbsf and is characterized by a remarkable increase in abundance of most species that survived the local extinction, e.g. Acarinina soldadoensis, A. coalingensis, A. interposita, Chiloguembelina crinita, Chiloguembelina trinitatensis, Subbotina patagonica, Subbotina hornibrooki, Globoturborotalita bassriverensis, and Zeauvigerina spp. (Figure 2). There is a significant increase in the abundance of Morozovella during the recovery stage of the PETM in this study, making it the most abundant taxon. The abundance of Subbotina and Acarinina species was relatively similar, while the genus Chiloguembelina replaced Globanomalina as the fourth most abundant taxon. Figure 2 The distribution of planktonic foraminiferal species from core 29H and 30H (PETM interval) of Site 1265A. A - species that went extinct during or shortly after the CIE. B - Species that appeared during or after the CIE. C - Cosmopolitan species The abundance and diversity of all the species were significantly affected by carbonate dissolution within the CIE interval. The bulk carbon isotope record and lithology were plotted with supplementary data from Zachos et al. [2005, 47]. 3.1.4. Multivariate analyses Based on the result from the ANOSIM, planktonic foraminiferal assemblage at Hole 1265A significantly differed between the Pre-CIE, CIE, and Recovery interval (global R = 0.673,p<0.01), and the pairwise tests showed that all the three World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1837 intervals significantly differed from each other in terms of composition with p<0.01. The result also showed that each interval insignificantly differed from each other as follows: Recovery and CIE, R= 0.632 (p< 0.01); Recovery and PreCIE, R= 0.918, (p< 0.02); CIE and Pre-CIE (R= 0.335) (p< 0.01). The sample ordination during the pre-CIE was distinct and the Recovery samples were tightly grouped. However, the CIE was clearly different, because the grouping was more or less longitudinal, forming a transect between the Pre-CIE and the Recovery groups (Figure 3). The high dissimilarity (R= 0.335; p< 0.01) of planktonic foraminifera composition during the CIE suggests evidence of environmental disturbance (Figure 3) while the greater similarity (R= 0.918,p< 0.01) of the pre-CIE and the recovery imply a more stable ecosystem (Figure 3). Figure 3 Non-Metric Multidimensional Scaling ordination of planktonic foraminiferal taxonomic composition (transformed with log x+1) of Bray-Curtis similarity from Site 1265A Similarity percentage routine (SIMPER) results showed that six(6) taxa contributed to 50% of the dissimilarity between the CIE and the recovery intervals, notably Morozovella spp. contributed about 17.78% of the dissimilarity being fivefold more abundant during the CIE. The high abundance of this taxon during the CIE was attributed to its increase during the PETM [52, 12]. Nevertheless, Chiloguembelina trinitatensis, Subbotina patagonica, Morozovella subbotinae, and Globoturborotalita bassriverensis were more in abundance (Table 2) during the Recovery interval than in the CIE interval. Subbotina spp., Acarinina spp., and Morozovella Spp were more abundant during the CIE interval than in the Recovery interval. The high abundance of Subbotinaspp and Acarininaspp during the CIE period (Tables 2 and 3) was due to the high level of dissolution witnessed within the interval. This made the identifications to species level difficult. Chiloguembelina trinitatensis, C. Crinita, S. patagonica, M. subbotinae, G. bassriverensis, and A. interposita maintained higher abundance during the recovery compared with during the CIE. G. bassriverensis appeared during the CIE. The absence of M. aqua at the same interval showed that the species went extinct before the Recovery period. The dissimilarity between the CIE and pre-CIE indicated that Morozovella spp., Acarinina spp., Acarinina soldadoensis, and Acarinina nitida were more abundant during the CIE than during the Pre-CIE period. However, Subbotina spp., Subbotina patagonica, and Acarinina coalingensis abundance were higher before the CIE event than in the main CIE World Journal of Advanced Research and Reviews, 2025, 27(01), 1830-1846 1838 event. The abundance of Subbotina spp at the Pre-CIE interval indicated that the taxa test dissolution started before the CIE making the identification of the specimen to species level very difficult. 3.2. Planktonic foraminiferal trait composition and changes through time Figure 4 Mean abundance of planktonic foraminiferal traits driving the main differences in distribution across the PETM interval at Site 1265A (Data cut off 50%) The result of statistical analysis indicated that taxa with smooth, trochospiral test and semi-circular chamber shape were higher at the Pre-CIE interval than at the main CIE and Recovery intervals (Figure 5). Taxa with muricae structures, triangular/trapezoidal chambers, microand macro-perforations, extra-umbilical apertures, surface-dwelling, and grazing habits were more abundant during the CIE than at the Pre-CIE and Recovery intervals. Whereas taxa with fine perforation, depressed sutures, elongate test, bi/triserial chambers, terminal aperture, no apertural accessories, deepdwelling, and suspension feeding habit were more abundant during the Recovery than at the CIE and Pre-CIE intervals (Figure 4). 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