Orals: Tue, 29 Apr | Room -2.93
Time-averaging is the hard limit to the resolution of the fossil record, and it is of fundamental importance to interpreting fossil assemblages, especially when comparing fossil and living assemblages. To accurately estimate time-averaging, it is essential to separate the variation in fossil ages from the uncertainties in the estimates of those individual ages. Here, I use simulations as well as ~100 previously published, dated assemblages from the Holocene of Australia to examine the effectiveness of different analytical methods used to separate dating uncertainty from the variation associated with different aged fossils (time-averaging). In the vast majority (88%) of assemblages, the variation due to time-averaging exceeds the variation associated with age-estimation error, and time-averaging estimates that correct for age-estimation error are not different from time-averaging estimates that ignore age-estimation error.
Despite their parametric roots, error-corrected IQR and Estimated Time Averaging (ETA) perform well across a wide range of simulated assemblage age distributions, and relatively modest sample sizes (N ~12) yield reasonable time-averaging estimates. When reporting time-averaging estimates, age-estimation error should be explicitly reported and corrected for if age-estimation error represents more than 40% of the total assemblage age variation. While ETA estimates are not directly comparable to most published time-averaging values, ETA is an effective method for removing the impact of dating uncertainty from time-averaging estimates. A consensus on the reporting of time-averaging estimates is overdue.
How to cite: Kosnik, M.: Quantifing time-averaging and the temporal resolution of the fossil record, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4790, https://doi.org/10.5194/egusphere-egu25-4790, 2025.
Reconstructing past biodiversity changes, and integrating these with modern biodiversity assessments, requires that fossil assemblages accurately capture key aspects of diversity (as represented by biodiversity metrics, for example). This is particularly true for the plant fossil record, where separate organs such as sporomorphs (pollen and spores) and leaves have to be used as proxies for understanding vegetation composition and diversity change through time. Although much attention has been focused on how well fossil plant assemblages capture variations in species richness, other aspects of diversity have until recently been relatively overlooked.
Here, I focus on phylogenetic diversity (PD), which represents the amount of evolutionary history contained in an assemblage of taxa. It can therefore provide a more detailed assessment of biodiversity gains and losses through time and space, and their underlying causes and consequences, relative to simple counts of the number of species present in a sample, and as such is used both as a conservation metric and as a tool to understand community assembly. To date, however, PD has been underexplored by palaeoecologists, and it is not currently known how well variations in vegetation PD across broad spatial scales are captured by sporomorph assemblage data. I compare estimates of seed plant PD from vegetation data and surface pollen samples from across North and South America. The results indicate a relatively low concordance between vegetation and pollen PD, and differing relationships with climate data, suggesting that sporomorph data cannot be used as a straightforward PD record. Other data sources (e.g. aDNA data for late Quaternary datasets, macrofossil data in deeper time settings) need to be considered for reconstructing vegetation PD through time. More generally, how well sporomorph data captures other aspects of plant biodiversity, and how successfully the plant fossil record can be used for conservation-relevant questions, ought to be critically (re-)assessed.
How to cite: Jardine, P.: How well does palynological data represent vegetation phylogenetic diversity?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5945, https://doi.org/10.5194/egusphere-egu25-5945, 2025.
Surficial accumulations of marine mollusk shells archive information about ecosystems from previous centuries and millennia and can be used not only to measure recent human impacts but also detect habitats that have remained relatively unaltered. In this case study, we applied this near-time conservation paleobiology approach to assess the status of seagrass meadows that form structured habitats along the northern Gulf coast of Florida. Previous studies suggest that seagrass habitats in the study area may have remained relatively unaltered. We tested the “pristine seagrass” hypothesis by comparing living mollusks to the surficial mollusk accumulations time-averaged over the last three millennia. Samples were collected hierarchically at six estuaries (21 sites total) and live-dead comparisons were carried out at five observational scales: (1) size fractions within quadrats, (2) quadrats within sites, (3) sites within estuaries, (4) estuaries, and (5) the entire study area. At all scales, the species rank abundances of live and dead mollusks were positively and significantly correlated suggesting concordance in faunal composition. Similarly, local species richness and species evenness were congruent when comparing live and dead samples. Non-metric Multidimensional Scaling (NMDS) ordinations and pairwise Bray-Curtis similarities indicated consistent trends in the distribution of past and present mollusk faunas along a spatial gradient in productivity. The results support the hypothesis that seagrass habitats in the study area have not been notably modified by human activities and reinforce the urgency for continued conservation of the seagrass ecosystem of the northern Gulf coast of Florida. The results also suggest that the studied seagrass system can serve as a comparative benchmark for evaluating changes in other seagrass ecosystems that have been more strongly affected by human activities.
How to cite: Kowalewski, M., Grimmelbein, L., Barry, S., Casebolt, S., Hyman, A., Cummings, K., and Frazer, T.: Shells in the seagrass: Holocene mollusks as a tool for identifying unaltered habitats, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7336, https://doi.org/10.5194/egusphere-egu25-7336, 2025.
Parasites make up a significant portion of the global biomass and are integral to the healthy functioning of modern ecosystems. Despite their importance today, past changes in parasite distribution and diversity remain largely unexplored due to their limited preservation potential in the fossil record. Using information from more than 700 archaeological and paleoparasitological studies, we compiled a comprehensive database of parasite finds from the Holocene to address this knowledge gap. Our aim was to provide high-resolution spatial and temporal data on parasite occurrences to facilitate their use beyond archaeological literature, e.g., in macroevolutionary analyses and in ecological modelling of future trends in parasite distribution. The database includes more than 3,000 occurrences, which, along with information on their locality, age, taxonomic identity of the parasite and its potential hosts within relational database framework, allows users to build comprehensive profiles of parasite diversity on different geographical scales or spanning a particular time period. The majority of parasite finds consist of resistant eggs or trace evidence of intestinal helminths, such as nematodes (particularly genera Ascaris and Trichuris) and flatworms (genera Dibothriocephalus, Taenia and Fasciola), recovered from sediment samples and coprolites associated with human settlements or burials. Most parasite finds have been identified to at least the genus level and are mostly concentrated in the late Holocene period, with a significant increase in occurrences at the start of the Middle Ages. Using various modelling approaches, we demonstrate that the presence of the most common genera of intestinal parasites in archaeological record throughout the Holocene correlate with increases in human population density and seasonality.
How to cite: De Baets, K. and Vanadzina, K.: Using paleodata to map parasite diversity throughout Holocene, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6564, https://doi.org/10.5194/egusphere-egu25-6564, 2025.
Interactions between the parasitic larvae of digenean trematodes (mainly gymnophallids) and bivalves often result in characteristic shell malformations, i.e., pit-like traces. Tracking these traces through the Holocene and modern marine death assemblages has made studying parasite-host responses to natural and anthropogenic environmental change possible (e.g., Fitzgerald et al., 2024). Despite major breakthroughs, empirical explorations of parasite-host dynamics in the geological record are primarily based on trace occurrence data, overlooking that trace spatial patterns on the host skeleton could carry ecological information and potentially document different aspects of the parasite-host interactions (e.g., infective behavior, association with specific host anatomy, spatial relationships of traces with different qualitative properties such as size class, etc.). The Spatial Point Pattern Analysis of Traces (SPPAT) (Rojas et al. 2020) has been increasingly employed to overcome similar challenges in studying predatory traces on bivalve prey. Although this approach holds considerable promise for research on trematode–host dynamics, several assumptions and caveats need to be considered (e.g., the number of traces required to capture the parasite-host dynamics accurately, the reliability of point patterns constructed from multiple host skeletons in describing parasite interactions). Here, we introduce a spatially explicit framework for extracting information from spatial patterns of trematode-induced pits on bivalve shells using SPPAT, address methodological questions involved in assembling a point pattern of traces from multiple host specimens, and discuss critical issues related to drawing inferences from pooled point data. We illustrate our approach using a case study on late Holocene samples of the commercially relevant bivalve Chamelea gallina from the northern Adriatic of Italy. This species holds high commercial value in the seafood industry and is increasingly used in climate change research. The C. gallina case study reveals that trematode-induced malformations on bivalve shells are not random; they show an aggregated pattern for metacercaria traces of the same size, while an independent pattern arises when examining metacercaria-related traces of two distinct size classes. Our case study demonstrates the value of spatial information from parasite-induced traces, enhancing our understanding of parasite-host dynamics over time.
Rojas A, Dietl GP, Kowalewski M, Portell RW, Hendy A, Blackburn JK. 2020 Spatial point pattern analysis of traces (SPPAT): An approach for visualizing and quantifying site-selectivity patterns of drilling predators. Paleobiology 46, 259–271. https://doi.org/10.1017/pab.2020.15
Fitzgerald, E., Ryan, D., Scarponi, D., and Huntley, J. W. 2024: A sea of change: Tracing parasitic dynamics through the past millennia in the northern Adriatic, Italy. Geology; 52 (8): 610–614. https://doi.org/10.1130/G52187.1
How to cite: Rojas-Briceno, A., Huntley, J. W., and Scarponi, D.: Spatial patterns of trematode-induced pits on bivalve skeletons: Challenges and prospects for research on parasite-host dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4571, https://doi.org/10.5194/egusphere-egu25-4571, 2025.
Lagoonal environments are highly biodiverse coastal ecosystems, extremely susceptible to multiple anthropogenic and natural stressors (eutrophication, contaminants, storms and floods, relative sea-level rise among others). Given their ecological importance, effective monitoring and restoration strategies are essential to safeguard their integrity. The quantitative assessment of the Ecological Quality Status (EcoQS) represents a fundamental step in designing action plans through an ecosystem-based approach that incorporates biological indicators, as mandated by the EU Water Framework Directive (2000) and the Marine Strategy Framework Directive (2008/56/EC).
This study aims to contextualize the EcoQS of a modern lagoon (Bellocchio Lagoon) belonging to the Po coastal plain (N Adriatic Sea), by comparing current values with pristine reference conditions from the past. To achieve this purpose, we integrated analyses of benthic foraminiferal assemblages from sediment cores and modern samples to reconstruct environmental changes and EcoQS temporal trends mainly applying the Foram-AMBI index, which is based on species sensitivity to organic-matter enrichment.
Reference conditions were reconstructed analyzing the foraminiferal assemblages encased within the well-dated sedimentary successions of a near-site humid area, whose Holocene record reflects depositional environments comparable, though on a different scale, to the Bellocchio Lagoon.
A reliable comparison of past and present environments was based on the identification of three distinct biofacies within the Bellocchio Lagoon, by means of cluster analyses based on the benthic foraminiferal thanatocoenoses. Each biofacies corresponds to a sub environment (i.e. inner lagoon, outer lagoon, and salt marsh - channels) characterized by a typifying foraminiferal content and a set of environmental parameters (i.e. sand, calcium carbonate and total organic matter content). Using the Modern Analogue Matching technique, cores assemblages were compared to the biofacies, enabling the identification of modern analogues for past depositional settings. The reconstruction of long-term ecosystems’ dynamics and the assessment of the Ecological Quality Ratio, calculated comparing the EcoQS derived from core samples with the EcoQS of modern biocoenoses, allow to evaluate the present-day ecological conditions in the context of the natural and human forcing factors that have affected lagoonal environments over time.
How to cite: Vecchi, A., Barbieri, G., Armynot du Châtelet, É., Frontalini, F., Mazzini, I., da Prato, S., Vaiani, S. C., and Rossi, V.: Tracing Holocene dynamics of lagoon’s ecological quality: a stratigraphic-based, benthic foraminiferal approach from the Po Plain (N Adriatic Sea), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19619, https://doi.org/10.5194/egusphere-egu25-19619, 2025.
The wolf (Canis lupus L. 1758) was a keystone predator throughout the Pleistocene in Europe and is a prime candidate for exploring past carnivore community and herbivore interactions, having persisted through multiple climatic cycles during the Quaternary. Wolves play a vital role in maintaining biodiversity, particularly in keeping mammalian herbivore and medium-sized carnivore numbers in check and thereby limiting over-browsing on vegetation and over-predation on small vertebrates respectively. Wolves further exert important indirect controls on ecosystem structure, riparian environments and the activities of foundation species such as beaver, as well as subduing mesocarnivore numbers, with associated benefits for birds and small mammals. The ripples from their activity can therefore be felt in diverse positive ways throughout the ecosystem but serious concerns exist as to the viability of European wolf populations under different scenarios of environmental and climate change. Although predatory behaviour is well documented in modern wolves, the short time scales (years to decades) of neoecological studies do not allow longer term patterns and any ensuing morphological responses to be captured. A continuous chronological perspective is therefore essential to progress our understanding. Our current project combines the study of diet and morphology in modern European wolves with that of British Pleistocene wolves, where a rich fossil record offers a chronologically well-resolved series of specimens spanning tens to hundreds of thousands of years. A key goal is therefore to understand how wolves have adapted to changing circumstances so that current and future conservation policy can be appropriately tailored. Here, we present variation in British fossil wolf diets to assess the impact of forcing factors such as changes in climate, environment, prey community and carnivore competition on feeding behaviour and the rates of change at which these occur. A multiproxy and multiscalar approach is adopted, combining direct measurement of wolf paleodiet through stable isotope analysis and dental microwear texture analysis. A more comprehensive understanding of carnivore community ecology and interactions in Pleistocene Britain will contribute to scientific understanding of the practicalities of re-wilding using extirpated, native large carnivores.
How to cite: Lamb, A., Pigière, F., Bista, D., Burtt, A., and Schreve, D.: Nature of the Beast? Resolving the paleoecological history of the wolf (Canis lupus L., 1758) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4215, https://doi.org/10.5194/egusphere-egu25-4215, 2025.
Archival data sources can bridge the gap between the paleoecological and ecological time-series and provide a socio-economic context for the understanding of long-term changes in populations of exploited marine species. Detailed fishery statistics from the eastern Adriatic Sea extend back to the early 1870s when the Austro-Hungarian maritime administration initiated a systematic and centralized reporting of annual landings. Here we combine these data with early naturalist accounts to track changes in the Ark shell (Arca noae) populations in that area over the last 150 years. Our results indicate that the collapse of the Ark shell fishery in the 1950s was preceded by at least 80 years of intensive exploitation. During that time A. noae fishery was one of the most important in the eastern Adriatic with the annual catch regularly exceeding 200 t and reaching as much as ~780 t in 1879. At the same time it was one of the cheapest marine products available on the market, consumed primarily by the poor. Historical testimonies indicate that by the late 19th century, fishery administrators and naturalists were well aware of the adverse effects of overexploatiation of marine populations and destructive fishing practices. However, A. noae was explicitly excluded from the regulations establishing legal size limits and no-catch periods that were introduced in the 1880s to protect the Mediterranean mussel (Mytilus galloprovincialis) and European flat oyster (Ostrea edulis), two bivalve species characterized by lower annual landings but much higher market value. Following a mass mortality event in the late 1940s, the annual catch of A. noae rapidly declined and has remained below ~30 t until today – an order of magnitude lower compared to the late 19th and early 20th century. Decades-long, intense harvesting of A. noae may be one the major drivers of the significant shift in its life history characteristics, which was previously documented by sclerochronological analyses of modern and fossil (middle to late Holocene) shells of this species.
How to cite: Nawrot, R., Peharda, M., Uvanović, H., Tomašových, A., Zemann, S., and Zuschin, M.: Collapse of a bivalve fishery documented by historical records and paleontological data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12336, https://doi.org/10.5194/egusphere-egu25-12336, 2025.
The species richness and shell size distribution of major clades and functional groups among gastropods, a key element of the Modern Evolutionary Fauna (MEF), underlines the dominant role at modern tropical latitudes of carnivorous Caenogastropoda and Heterobranchia, including small-sized ectoparasites and micrograzers. The escalation hypothesis emphasises prey-predator interactions as gastropods’ macroevolutionary drivers during the Mesozoic Marine Revolution, but overlooks the significance of the highly-diversified smaller species. The early Mesozoic roots of the Neogastropoda, active predators particularly diversified since the Cretaceous and eminent extant members of the MEF, are poorly understood. I revise the tropical fossil record of the Permian-Triassic mass extinction (PTME), the major in animal history, and the Triassic rise of the MEF. The study suggests that non-carnivorous species dominated the gastropod fauna immediately before and after the PTME; Permian micrograzers mainly fed on sponges and waned during the rise of the MEF; ectoparasites and micrograzing carnivores diversified in the second part of the Middle Triassic; larger predators are lacking throught the interval. Patterns of gastropod species richness, size and form, the fossil record of reef-builders and other benthic invertebrates, and an analysis of stem neogastropods jointly highlight a Middle Triassic revolution of small-sized gastropods triggered by the emergence of scleractinian corals and the diversification of echinoderms. Habitat heterogeneity and new food sources offered niches for the early radiation of modern gastropod clades, pointing the Triassic as a laboratory to understand macroevolutionary processes in the wake of a major biotic crisis.
How to cite: Dominici, S.: Gastropods in deep time and the early Modern Evolutionary Fauna, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14980, https://doi.org/10.5194/egusphere-egu25-14980, 2025.
Paleo-Tokyo Bay, which existed in Central Japan during MIS 9 when climate was globally warm and sea level was high, potentially provides an analogue to the contemporary global warming trends. Although a large number of well-preserved shells is available from marine deposits of Paleo-Tokyo Bay (Yabu Formation, Shimosa Group), seawater temperature in Paleo-Tokyo Bay has so far largely remained unknown. The majority of shells found in respective strata belong to the cold-water bivalve, Mercenaria stimpsoni, with a lifespan exceeding 100 years. This is interesting as the global climate during MIS 9 was warm. Recently, Miki et al. (2024) quantified past seawater temperature using fossil shells of this species, but they used only one individual of MIS 9. Hence, a detailed understanding of seawater temperature and its influence on shell growth is still missing.
Here, we aimed to further substantiate seawater temperature conditions of Paleo-Tokyo Bay during MIS 9 using oxygen isotope data of five additional M. stimpsoni shells collected from two outcrops (Semata and Takakura). We also assessed how the paleoenvironmental conditions affected the growth rate of the bivalves.
Samples were cleaned with tap water and then cut along the maximum growth axis to obtain two slices of shells. One slice was polished and stained with Mutvei’s solution for growth pattern analysis. The other slice was used for isotope analysis. Shells were sampled with a computer-controlled micromilling system at low drill speed to produce CaCO3 powder for oxygen isotope analysis. Isotope analysis was performed by means of CF-IRMS (continuous flow – isotope ratio mass spectrometry; Thermo Fisher MAT 253; reaction temperature: 72 °C). The analytical precision was better than ±0.10 ‰. δ18O-derived temperature was computed using two different paleothermometry equations, i.e., expression by (i) Grossman and Ku (1986, Chem. Geol. Isot. Geosci. Sect.) with the scale correction by Gonfiantini et al. (1995, IAEA Rep.) and (ii) Kim et al. (2007, Geochim. Cosmochim. Acta). For the latter, the oxygen isotope data were adjusted for different acid fractionation factors of aragonite (shell) and calcite (reference materials) (Kim et al., 2007, Chem. Geol.). The δ18Oseawater value was assumed to be 0 ‰ in all calculations.
The seasonal changes in seawater temperature during consecutive five to seven years were reconstructed from five specimens. All shells recorded maximum seawater temperatures above 18 or 20 °C (first value using the equation by Grossman & Ku, 1986; second value Kim et al., 2007). Such temperatures were probably highly stressful for specimens of this cold-water species resulting in growth cessation and formation of dark bands. Seasonal shell growth started at a temperature of 12 to 16 °C. Those values were clearly higher than those of modern shells (approximately 10 °C). Fossil M. stimpsoni seem to have been adapted to warmer seawater than modern specimens. In conclusion, fossil shells from Paleo-Tokyo Bay (Shimosa Group) can provide snapshots of a warmer world and a key insight into its influence on the bivalves.
How to cite: Miki, S., R. Schöne, B., Chiba, T., Gey, C., Vigelius, D., and Shirai, K.: Past seawater temperature in Paleo-Tokyo Bay during MIS 9 reconstructed from oxygen isotopes of fossil shells of Mercenaria stimpsoni (Bivalvia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13458, https://doi.org/10.5194/egusphere-egu25-13458, 2025.
A long-term cooling trend from middle Lutetian onwards (~44 Ma) was briefly interrupted by a short-lived warming event in the early Bartonian (~41 Ma), known as the Middle Eocene Climatic Optimum (MECO). At this stage, the Himalayan orogenesis was ongoing, and the mountain had not yet attained its current elevation, which now plays a crucial role in shaping Asia's seasonality and monsoon patterns. The Indian Subcontinent reached tropical latitudes in Eocene during its long voyage from the southern to the northern hemisphere, after its disjunction from Gondwanaland in the Early Jurassic. Given that seasonal temperature variation is relatively small at the tropics in the modern climate, exploring seasonality and monsoon patterns in the ice-free world of the early Bartonian can teach us about the response of seasonal variability to warming.
Kutch, a pericratonic rift basin located along the western margin of the Indian subcontinent, was at 6–7°N during the early Bartonian. The Harudi and Fulra Limestone formations, two successive Bartonian stratigraphic units (corresponding to SBZ 17), preserve sedimentary deposits with a moderate diversity of bivalves. Two oyster species—Flemingostrea sp. from upper Harudi Formation, and Pycnodonte sp. from basal Fulra Limestone—have been utilised to reconstruct the Bartonian climate and seasonality.
Dorso-ventral cross-sections of the shells underwent μXRF mapping, revealing the resilifers as the most pristine regions of the shells. High-resolution (25 µm) quantitative trace element profiles, conducted on the resilifers, show low concentrations of Mn and Fe indicative of good shell preservation. Incrementally sampled stable isotope (δ¹⁸Ocarb and δ¹³Ccarb) profiles display a sinusoidal pattern indicative of seasonal fluctuations throughout the oysters' growth. Subsamples corresponding to two of the lowest and highest δ¹⁸Ocarb values from each shell were further analysed for clumped isotopes (Δ47).
Clumped isotope thermometry, combined with δ¹⁸O records indicates that tropics experienced minimal seasonal temperature fluctuations (~3°C on average) in a range of 29±3°C to 36±2.8°C (95% Cl) in the early Bartonian. The oxygen isotope composition of the prevailing water body shows evidence for increased freshwater input during colder months.
This study suggests that early Bartonian seasonality range at tropical latitudes was similar than the modern one, but at a roughly 4 degree warmer level, with eventually higher precipitation during the colder season.
How to cite: Mitra, A., Müller, I. A., de Winter, N. J., Claeys, P., Ledésert, B. A., and Halder, K.: Oyster shells reveal low seasonality with winter precipitation in Bartonian India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-234, https://doi.org/10.5194/egusphere-egu25-234, 2025.
The early to middle Eocene (56 – 41 Ma) is characterized by high atmospheric CO2 concentrations between 1,000 and 1,500 ppm, making it the warmest interval of the Cenozoic [1,2]. The future atmospheric CO2 concentration could reach similar levels around 2100, based on the high CO2 emissions scenario SSP5-8.5 [3]. By studying the Eocene climate, we gain understanding of how our climate system could operate under these extreme conditions.
An important aspect of climate is the seasonal temperature variability: the differences between summer and winter temperatures. Past seasonality can be reconstructed from sub-annually resolved climate archives such as the incremental growth bands of mollusk shells. We performed clumped isotope analysis on micro-samples of 11 fossil shells of early to middle Eocene age from shallow marine settings in northwestern Europe: 8 bivalves (species Venericor planicosta) and 3 gastropods (Haustator solanderi).
We obtained seasonal shell chronologies from the variability in the oxygen isotope records of the micro-samples, and we used the corresponding clumped isotope records to reconstruct the seasonal temperature variability of the seawater independent of its isotopic composition [4].
Our results suggest a moderate seasonal temperature variability of approximately 6 – 7 °C during both the early (56 – 48 Ma) and middle (48 – 41 Ma) Eocene. A comparison with Eocene climate model simulations suggests that models overestimate the observed seasonality due to colder winter temperatures in the model simulations compared to the reconstructions. This temperature record sheds light on the role of seasonality in mid-latitude shallow marine environments in hothouse climates and can aid our understanding of regional and seasonal scale model-data discrepancies.
[1] Rae, J. W. B., Zhang, Y. G., Liu, X. et al. (2021). Atmospheric CO2 over the past 66 million years from marine archives. Annual Review of Earth and Planetary Sciences, 49(1). https://doi.org/10.1146/annurev-earth-082420-063026
[2] The Cenozoic CO2 Proxy Integration Project Consortium (2023). Toward a Cenozoic history of atmospheric CO2. Science, 382(6675). https://doi.org/10.1126/science.adi5177
[3] Chen, D., Rojas, M., Samset, B. H. et al. (2021). Framing, context, and methods. In V. Masson-Delmotte, et al. (Eds.), Climate change 2021: The physical science basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 147–286). Cambridge University Press.
[4] de Winter, N.J., Agterhuis, T., & Ziegler, M. (2021). Optimizing sampling strategies in high-resolution paleoclimate records. Climate of the Past, 17(3). https://doi.org/10.5194/cp-17-1315-2021
How to cite: Goudsmit-Harzevoort, B., de Winter, N., Vellekoop, J., Wesselingh, F., Witbaard, R., and Ziegler, M.: Reconstructing Seasonality in Northwest Europe during the Early to Middle Eocene using Clumped Isotope Thermometry on Fossil Mollusks, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5563, https://doi.org/10.5194/egusphere-egu25-5563, 2025.
The Upper Cretaceous Coon Creek Formation (CCF) of western Tennessee is renowned for its diverse assemblage of exceptionally well-preserved shallow marine fossils, particularly shelled mollusks. Microfossils, including calcareous nannoplankton and dinoflagellates, confirm a late Campanian age for the site and indicate both warm- and cool-water taxa, suggesting shifting climatic conditions recorded within the sedimentary sequence. The formation, consisting of approximately 8 meters of glauconitic, clayey sands, was deposited in a shallow marine environment with significant terrestrial input, as evidenced by stable carbon isotope studies of arthropod fossils, fossilized wood, and abundant clay. However, the variability in the strength or influence of this terrestrial input over seasonal or longer timescales remains unclear. Recent investigations have revealed that some mollusk shells from the CCF may preserve evidence of harmful toxins, such as brevetoxin and saxitoxin, which are commonly associated with harmful algal blooms (HABs) in modern aquatic environments.
To further explore the relationship between paleoenvironmental parameters and HABs, we collected mollusk shells, sediments, and microfossils from multiple horizons within the CCF for geochemical and algal toxin analyses. SEM imaging confirmed the exceptional preservation of primary aragonite prisms and fibers in the fossilized shells. Using LA-ICP-MS, trace elements such as phosphorus, barium, magnesium, and strontium were measured along shell growth axes. Multiple transects were conducted at different points in the same shell to assess the reproducibility of trace element time series within a single specimen. Additionally, stable isotope analyses (δ¹⁸O and δ¹³C) were performed parallel to the trace element analyses to correlate these records within each shell.
The trace element and stable isotope records within CCF bivalves exhibit cyclic variations, suggesting seasonal environmental changes within this warm coastal ecosystem. Temperature estimates derived from δ¹⁸O are concordant with previous estimates and align with other regional records. Some trace elements, including barium and phosphorus, display transient spikes that may reflect episodes of increased terrestrial input and/or algal blooms, although direct evidence for these events remains limited. By investigating the chemistry of these ancient mollusks and comparing them to modern environments, this study aims to shed light on the potential occurrence of HABs during a prior greenhouse climate and evaluate the role of terrestrial runoff in influencing nutrient cycles and marine ecosystem health. These results provide valuable insights into the environmental and climatic conditions of the Cretaceous and contribute to a broader understanding of how terrestrial input may have driven nutrient dynamics and the development of algal blooms in shallow marine settings.
How to cite: Kelley, N., Oster, J., and Kovalski, A.: Trace Element and Stable Isotope Records Reveal Seasonal and Episodic Environmental Fluctuations in the Upper Cretaceous Coon Creek Formation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20254, https://doi.org/10.5194/egusphere-egu25-20254, 2025.
The late Sakmarian (Early Permian) is a key time-interval to unravel deep time climate changes at the transition from icehouse to greenhouse conditions. Very recent data (Jurikova et al., 2025) showed that the demise of the Late Palaeozoic Ice Age (LPIA) was caused by an increase in atmospheric CO2 linked to volcanic activity, peaking in the late Sakmarian. To understand how this CO2 increase impacted the climate at the seasonal scale and how it affected marine ecosystems, we performed a sclerochemical analysis on a carefully screened shell of the brachiopod Pachycyrtella omanensis from the Saiwan Fm. in Oman. This specimen thrived at ~45°S, in shallow water settings along the Gondwanan margin, in the context of the deglaciation from the LPIA and Early Permian warming.
High-resolution δ18O, δ13C and δ11B sclerochemical analyses along the shell growth axis revealed oscillating profiles, characterized by at least three main periodic cycles each. Preliminary profile analysis points towards broad coupling of main internal δ13C and δ11B cycles, showing a maximum signal amplitude of ~3‰ and 5‰, respectively, which might be representative of growth cycles punctuated with growth halts in between.
Periodicity in the δ18O profile showed a maximum signal amplitude of 3.2‰ and might correspond to seasonal variations in seawater temperature. Based on the average δ18O and signal amplitude, and assuming a δ18Osw value of –0.5‰, this specimen recorded an average temperature of 25.5°C with a temperature seasonality of 15°C. The average temperature recorded by P. omanensis is much higher than what is observed at similar latitudes and depths nowadays, as is the seasonal variation. The relatively higher average temperature could be explained by the warming and increasing CO2 conditions during the Early Permian. Elevated seasonality is not expected under these conditions, but it may have been magnified by seasonally variable δ18Osw reflecting a dynamic coastal environment, which could also explain the observed internal cyclicity in δ13C and δ11B.
This study underlines the potential of sclerochemical analyses in well-preserved fossil brachiopods for providing news insights into deep-time environmental change at annual/ seasonal scale. Our results also lend support to the hypothesis that P. omanensis might have been an opportunistic species that exploited dynamic environments subjected to seasonal stressors with oscillating but abundant food resources. These findings suggest a potential analogue scenario for future marine ecosystems under the current warming icehouse.
Jurikova H., Garbelli C., Whiteford R., Reeves T., Laker G., Liebetrau V., Gutjahr M., Eisenhauer A., Savickaite K., Leng M.J., Iurino D.A., Viaretti M., Tomašových A., Zhang Y., Wang W., Shi G.R., Shen S.Z., Rae J.W.B. & Angiolini L. (2025). Rapid rise in atmospheric CO2 ended the Late Palaeozoic Ice Age. Nature Geoscience.
How to cite: Viaretti, M., Crippa, G., Jurikova, H., Rae, J. W. B., and Angiolini, L.: Palaeoclimate and palaeoecology at the end of the Late Palaeozoic Ice Age: Insights from the Lower Permian Bioarchive of Oman, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17778, https://doi.org/10.5194/egusphere-egu25-17778, 2025.
Global environmental change threatens the persistence of coral reef systems. Long term in-situ environmental data is required to contextualize reef-scale thermal variability and future organismal resilience. These data can be derived from skeletal growth patterns of various marine calcifiers, most commonly corals, bivalves, and foraminifera. Free-living coralline algae, or rhodoliths, are largely underutilized biogenic archives which record environmental data in their growth increments. Many traditional attempts to utilize rhodoliths as (paleo-) environmental proxies have failed to produce viable reconstruction data due to difficulties in physical sectioning from nonlinear branching patterns and gaps in the resulting chronologies from unpredictable growth interruptions. Here we present a novel method of non-destructively deriving reef-scale annual mean sea temperatures using composite increment width profiles from microtomography scans of rhodoliths from the central Red Sea. Compiled profiles of rhodolith growth increment width were strongly positively coupled with mean annual temperature (R = 0.63), with a positive relationship between resemblance to corresponding temperature profiles and number of branches compiled. By circumventing inaccuracies in chronologies from unpredictable growth interruptions in rhodoliths, this novel method allows for the derivation of more accurate reconstructions of mean annual reef-scale sea temperatures using a previously inaccessible archive.
How to cite: Li, L., Bernal Tamayo, J. P., Chandra, V., Hetzinger, S., and Johnson, M. D.: Red Sea Rhodoliths as Environmental Archives: A Novel Method to Overcome Historical Challenges in Climate Reconstruction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21450, https://doi.org/10.5194/egusphere-egu25-21450, 2025.
Among the bioconstructed habitats of the Mediterranean Sea, Coralligenous is undoubtedly the most important ecosystem because of its extent, complexity and heterogeneity, which supports very high levels of biodiversity. Coralligenous is a hard-biogenic substrate mainly produced by the superposition of several generation of calcareous red algae, living in dim light conditions. Coralligenous contributes to seascape shaping through geological times, producing various morphotypes and causing geomorphological changes of the seafloor. Nevertheless, these bioconstructions are characterized by a low accretion rate and a high sensitivity to natural and anthropic impacts, including climate changes. For all these reasons, Coralligenous has since long time been the object of special interest by the UNEP RAC/SPA and considered among the priority habitats for monitoring and conservation by the EU. Recent technological advances have enhanced the study and preservation of these ecosystems. An innovative minimally invasive ROV-based coring systems have been developed under the “FISR- CRESCIBLUREEF” project and upgraded in the frame of the project “Tech4You PP2.3.1 Action 1 (CUP H23C22000370006) with integration of robotic and AI-based computer vision technologies for accurate 3D reconstruction, sampling, and mapping of these marine bioconstructions.
Using the protocol proposed by Cipriani et al. (2024), coralligenous core samples, collected from Marzamemi (Sicily, Italy) with ROV-based technologies, were compared with data obtained from coralligenous build-ups sampled in the same area by scuba-divers. Comparison between microfacies of core-samples and those of “tale quale” build-ups revealed no significant differences in term of abundance and relationship between skeletal frame-builders and non-skeletal carbonate components, despite the much smaller size of the core sample. These results allow to consider the ROV-based system as a powerful tool to obtain representative samples of bioconstructions for geobiological, environmental and paleoenvironmental studies without making invasive sampling, which would damage these fragile and delicate ecosystems.
Moreover, an integrated geochemical/geobiological approach has been utilized in order to identify possible proxies for short- and long-term environmental studies. This multidisciplinary approach showed an evident relationship between chemical composition of the carbonate minerals and the waters in which Coralligenous forms. Positive anomalies in heavy metals were found in bioconstructions and surrounding seawaters. Such enrichments could result from pollutants introduced into the marine system by human activities and recorded by the components of the bioconstructions. These data allow to consider coralligenous build-ups as environmental database that continuously record environmental disturbance, enabling temporal reconstruction of the marine environment over time.
Although coralligenous bioconstructions are present along almost all Mediterranean continental shelf, their distribution is still underestimated and has been mapped only in few areas. For this reason, a protocol for benthic habitat mapping were also proposed and tested in shallow coastal waters of Isola Capo Rizzuto Marine Protected Area (Calabria, Italy). The method has proven capable not only of identifying coralligenous bioconstructions, but also of quantitatively defining their 3D distribution in terms of covered surface, volume and thickness. Combining this mapping protocol with minimally invasive sampling systems and geobiological-geochemical characterization of marine bioconstructions, a potent instrument for monitoring, protecting and enhancing these delicate ecosystems could be obtained.
How to cite: Maruca, G., Cipriani, M., Dominici, R., Apollaro, C., Vespasiano, G., Perri, F., Imbrogno, G., Bruno, F., Lagudi, A., Bracchi, V. A., Basso, D., Rosso, A., Sanfilippo, R., and Guido, A.: Advancements in the Study and Conservation of Coralligenous Bioconstructions: Integrating ROV-Based Sampling, Geobiology and Geochemistry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8996, https://doi.org/10.5194/egusphere-egu25-8996, 2025.
Oxygen isotopes measured in the phosphate or carbonate groups of tooth enamel hydroxyapatite have been used as proxies for paleo-climate, seasonality, and migration throughout more than a half-century of research. Despite many successful applications, the fundamental relationships between enamel isotope ratios and environmental forcing factors remain relatively poorly documented and sometimes ambiguous. We revisit these relationships in the context of a new large-scale study of tooth enamel from modern humans. We reaffirm that geographic variation in the oxygen isotope ratio of environmental (drinking) water is the primary driver of variation in tooth enamel carbonate δ18O values and quantitatively predicts a large fraction (~70%) of the isotopic variance among individual USA residents. This is true regardless of whether individuals resided in a single or multiple locations during the period of tooth growth. We also highlight results from meta-analysis and new experimental work that demonstrate how inconsistencies in experimental and laboratory procedures can substantially obscure the relationship between tooth enamel and environmental δ18O. Collectively, these results suggest substantial promise for the future utility of enamel oxygen isotope data in modern and paleo- context, but emphasize that mindful sample selection and preparation are required to derive robust inferences from these data.
How to cite: Bowen, G., Verostick, K., Rivera, B., and Stantis, C.: Oxygen isotopes in tooth enamel: Strengthening the foundation of a foundational proxy method, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2932, https://doi.org/10.5194/egusphere-egu25-2932, 2025.
The Western Interior Seaway (WIS) was a major epicontinental sea that divided North America during the Late Cretaceous with a rich ecosystem that hosted a wide variety of marine life. The seaway was home to a diverse range of species, from microscopic planktonic organisms to giant reptiles and sharks. However, food web structures and trophic interactions among Late Cretaceous marine taxa remain largely ambiguous due to the challenges in reconstructing ecological interactions in the fossil record. Fossil evidence of predator-prey interactions such as preserved bite marks, stomach content or faeces is limited. For sharks, trophic interactions can be inferred from morphological comparisons of teeth with modern counterparts. Yet, none of these methods alone can decisively identify the overall diet nor can they quantify a species’ trophic position. Thanks to recent methodological advancements, an animal’s trophic position can now be reconstructed on geologic timescales by analysing geochemical proxies preserved in dental enamel(oid). Among these novel proxies are zinc isotope ratios (66Zn/64Zn), reported as δ66Zn value, a trophic-level proxy that is increasingly applied to address archaeological and palaeobiological research questions.
Here we use enamel(oid) δ66Zn values to investigate the food web structures and trophic positions among lamniform sharks within the WIS. We focus on specimen from two Upper Cretaceous localities in the U.S., the Tocito Sandstone-Mulatto Tongue of the Mancos Shale in New Mexico and the Codell Sandstone Member of the Carlile Shale in Kansas. The fossil assemblages are dated to the Turonian-Coniacian transition, just prior to the radiation of Mosasauroidea (extinct marine lizards) to becoming the dominant marine predator of the WIS. Our results demonstrate well-preserved enamel(oid) δ66Zn values in both localities, but locality-specific differences in the diagenetic modification of dentine δ66Zn values. We highlight significant resource partitioning among the 16 analysed taxa within the WIS. Archaeolamna cf. A. kopingensis, Cretodus sp. and Cretoxyrhina mantelli occupied very high trophic positions, whereas Cretalamna cf. C appendiculata was likely foraging opportunistically across several trophic levels. We expand the use of enamel(oid) δ66Zn analyses to Mesozoic fossils and demonstrate that the analyses of enameloid δ66Zn values of multiple taxa within fossil assemblages enables robust reconstructions of food web dynamics and trophic interactions, providing new avenues for palaeobiological and evolutionary research in deep time.
How to cite: McCormack, J., Griffiths, M. L., Maisch IV, H., Becker, M. A., Müller, W., Knighton, J., Eagle, R., and Shimada, K.: Dietary niche partitioning among large sharks in the Late Cretaceous Western Interior Seaway of North America documented by zinc isotopes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8510, https://doi.org/10.5194/egusphere-egu25-8510, 2025.
Posters on site: Mon, 28 Apr, 08:30–10:15 | Hall X2
Kutch, a pericratonic basin at the western margin of India, provides a unique opportunity for paleontologists to study the interaction between depositional environments and taphonomic preservation of the bivalve shells, which prevail an enigmatic story in the true sense. Kutch holds thick marine sediments of approximately 3000 meters ranging from the Middle Jurassic to the Early Cretaceous period. However, this study represents a case study showing the relationship between the change in depositional environment and taphonomic preservation at the temporal scale from spatially distant two areas of Kutch, Wagad Uplift, and Lakhapar. Bharodiya and Kakarva, two localities of eastern Wagad Uplift and Lakhapar of the Kutch Mainland, preserve two differentially preserved bivalve shells regarding the depositional environment and associated energy conditions at different temporal intervals. The Kimmeridgian rocks from the Wagad Uplift show a convex upward-oriented shell, high degree of fragmentation and disarticulation, and size sorting, and suggest a transgressive lag deposit that has been reworked and deposited in a high energy condition. The taphonomic features of the Lakhapar area display a high diversity of bivalve fauna, a low degree of disarticulation and fragmentation, and a lack of any preferred orientation, indicating a maximum flooding zone sequence with low energy sediment starved offshore depositional environment. These two changes in deposition environment from the Kimmeridgian to the Tithonian period resulted in an inverse relationship between species richness and energy condition. The high-energy environment preferred to preserve large thick shelled bivalves and the low-energy condition preserved the small-sized taxa with more diverse compositions. Hence, the paleontological signals can be disentangled with the help of the preservation potential and taphonomic signatures.
How to cite: Saha, R., Paul, S., Das, S. S., Bardhan, S., Sarkar, D., Chattopadhyay, D., Mukhopadhyay, A., Poddar, A., Char, A., Basak, R., and Mahata, A.: Interaction between depositional environment and associated taphonomic conservation of the Upper Jurassic bivalves of Kutch, Gujarat, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1076, https://doi.org/10.5194/egusphere-egu25-1076, 2025.
Geochemical paleoproxies from marine archives are typically calibrated with temperatures from satellite- or ship-based observations that are spatially averaged over large areas, or with temperature data measured at a distance to the sampling site. These observations do not necessarily reflect local conditions and averaging effects potentially reduce variability. However, this is often the only viable option as no other direct observations are available in most settings. In subarctic and arctic regions in situ observations are even rarer and the availability of subannual-resolution surface ocean climate archives is very limited as well, especially when compared to the tropics. Encrusting coralline algae are important shallow-marine calcifiers that provide high-resolution archives of past ocean and environmental variability, but only few calibration studies of algal proxies exist from the climatically important high-latitude regions. At the same time these regions have experienced the most drastic changes in recent decades, e.g. Arctic surface temperature warming is more than twice as large as the global average.
Here, we present results from calibrating subannual-resolution coralline algal proxies with four years of continuous in situ measured temperature in Disko Bay, Greenland. Sensors were deployed in summer 2019 at sites of sample collection, recording water temperature in hourly resolution, providing data from the same water depth where the corallines grow. Coralline algal samples (Clathromorphum compactum) were retrieved together with sensors in summer of 2023. Temperature cycles are matched to coralline growth increments and geochemical data analyzed by Laser Ablation ICP-MS. The four year overlap makes our record the longest continuous calibration interval for coralline algae from high-latitudes. We align element/Ca-ratios with sclerochronological results and compare temperature measurements and proxies to high-resolution satellite observations and reanalysis data. Pairing of sub-seasonal resolution element/Ca-ratio time series measured in the uppermost years of algal growth with high-resolution in situ temperature allows us to directly connect individual short-time variability and warming/cooling recorded in the algal record to real-time observations. Water temperature plays a major role in controlling underlying processes in recently observed regional and large-scale Arctic and Greenland Ice Sheet (GIS) change. Coralline algal samples resolve ultra-high-resolution Disko Bay environmental variability in close proximity to Jakobshavn Glavier, one of the largest GIS glaciers, which delivers a significant amount of freshwater to the coastal West-Greenland surface ocean. Our study is testing proxy-temperature relationships on multiple algal samples, facilitating intra- and intersample comparisons, and thus helps to improve calibration of long-term algal proxy records used for paleo-reconstructions.
How to cite: Hetzinger, S., Halfar, J., and Tsay, A.: Calibrating Greenland coralline algal proxies with high-resolution in situ water temperature, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3025, https://doi.org/10.5194/egusphere-egu25-3025, 2025.
Anthropogenic global change necessitates the improvement of our understanding of the dynamics of warmer climates in the past. Combining information from Earth’s climate history with numerical simulations of past climate helps us to identify gaps in our knowledge of climate mechanisms and improves projections for future climate1,2. Data assimilation is a valuable tool to reconcile information from climate reconstructions and models in a consistent statistical framework3. These data assimilation efforts have focused mostly on climate variability on geological timescales (thousands to millions of years). However, seasonal changes in climate parameters such as temperature and precipitation are a defining characteristic of climate zones and have a dominant impact on the impact of climate on nature and human society4.
This work lays the foundations for applying data assimilation techniques to compare and combine reconstructions and model information on a seasonal scale. We use seasonal-scale temperature reconstructions from incrementally grown fossil mollusc shells which record seasonality in their living environment during modern5, Pliocene4 and Cretaceous periods6. We combine these data with model outcomes from the same periods to arrive at a combined estimate of seasonal temperature variability and discuss the methodological choices that lead to this result. Using this data analysis product allows us to more easily interrogate the outcomes from climate models with various boundary conditions using proxy-based information on select climate variables. The aim is to lay the foundation for data assimilation for estimating short-term climate variability in the geological past from skeletal carbonate archives and comparing model and reconstruction outcomes.
References
- Hakim, G. J. et al. The last millennium climate reanalysis project: Framework and first results. Journal of Geophysical Research: Atmospheres 121, 6745–6764 (2016).
- Tierney, J. E. et al. Past climates inform our future. Science 370, (2020).
- Dirren, S. & Hakim, G. J. Toward the assimilation of time-averaged observations. Geophysical Research Letters 32, (2005).
- de Winter, N. J. et al. Amplified seasonality in western Europe in a warmer world. Science Advances 10, eadl6717 (2024).
- Caldarescu, D. E. et al. Clumped isotope thermometry in bivalve shells: A tool for reconstructing seasonal upwelling. Geochimica et Cosmochimica Acta 294, 174–191 (2021).
- de Winter, N. J. et al. Absolute seasonal temperature estimates from clumped isotopes in bivalve shells suggest warm and variable greenhouse climate. Commun Earth Environ 2, 1–8 (2021).
How to cite: de Winter, N., Goudsmit-Harzevoort, B., Oerlemans, B., Witbaard, R., Bakker, P., Tindall, J., Farnsworth, A., and Ziegler, M.: Using data assimilation to combine model outcomes and reconstructions of seasonality during past warm periods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4520, https://doi.org/10.5194/egusphere-egu25-4520, 2025.
Dead-shell and fossil assemblages are tantalizing sources for information on past ecosystem-response to natural and anthropogenic perturbations. However, assessing the effects of interspecific differences in preservation on species abundances time-averaged dead-shell assemblages is hampered by the lack of long-term compositional data on present-day living assemblages. Here, we compare a unique, multidecadal-scale dataset of living assemblages (N~500,000) with surficial time-averaged death assemblages (N~40,000) from the southern California shelf to estimate the compositional bias that might arise from inherent differences in skeletal durability. We show that shell thickness is, among other four traits considered (shell size, mineralogy, organic content, and mode of life), the most important trait modifying molluscan species abundances. Using this as the null benchmark for live-dead discordance that is taphonomic in origin, the remainder of mismatch, such as the greater abundance of epifaunal suspension-feeders and siphonate deposit-feeders in death assemblages owes in fact to their ecological decline in recent centuries, even though their thicker shells and other attributes make them more preservable relative to thin-shelled remains of infaunal chemosymbiotic and detritus-feeders. Applying a correction factor informed by shell thickness sharpens the ability of live-dead mismatch to detect ecosystems modulated by human stressors, crucial to management and conservation decisions.
How to cite: Tomašových, A. and Kidwell, S. M.: Correcting for durability bias in estimating the composition of death and fossil assemblages: implications for understanding past ecological changes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7812, https://doi.org/10.5194/egusphere-egu25-7812, 2025.
Marine fishes are increasingly affected by climate warming and anthropogenic stressors, particularly since the beginning of the Industrial Revolution. The widely accepted Temperature-Size Rule (TSR) predicts that aquatic ectotherms grow faster, mature earlier, but attain smaller adult sizes under warmer conditions. However, its universal applicability remains controversial, and growth responses vary among species, ontogenetic ages and ecosystems. Fossil fish remains offer a unique opportunity to understand long-term growth and body size variability, providing historical baseline data, predating significant human impacts. Otoliths, incrementally grown CaCO3 structures in the inner ear of teleost fishes, are well-preserved in the fossil record and exhibit species-specific morphologies. These biominerals preserve detailed records of growth, age, life history, and environmental conditions in the form of daily, seasonal, and annual growth bands that can be analyzed through sclerochronological analyses. Our study focuses on the black goby (Gobius niger Linnaeus, 1758), a non-commercial, resident demersal species that is highly abundant in temperate shelf regions of the Atlantic and Mediterranean Sea, today and in the geological past. We use fossil otoliths from Holocene sediment cores off the coast of Piran (Slovenia) in the northern Adriatic Sea and modern otoliths from living populations caught in the same area to test whether anthropogenic climate warming has altered the growth patterns of this species, as predicted by the TSR. To assess growth patterns over the past millennia, sclerochronological analyses, including light microscopy and backscatter electron imaging of incremental records, are combined with radiocarbon dating on the same specimens. Our first results reveal no significant differences in overall growth patterns between fossil and modern populations. However, modern otoliths exhibit greater structural complexity and stress-related features, such as vaterite formations, alongside more variable growth patterns. Our study highlights the importance of integrating fossil and modern data to examine long-term growth trends and to expand our knowledge beyond commercially important and charismatic species to inform conservation and management strategies today.
How to cite: Leonhard, I., Jarochowska, E., Nawrot, R., Lipej, L., and Zuschin, M.: Surviving the heat: Long-term growth patterns of Adriatic gobies reconsructed from otolith analysis , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11409, https://doi.org/10.5194/egusphere-egu25-11409, 2025.
Primary productivity is a critical parameter of marine ecosystems, yet in many coastal areas, it has been significantly altered by human activities. The Northern Adriatic Sea (NAS), a shallow epicontinental sea bordered by the Italian and Balkan peninsulas, exemplifies this phenomenon. In the 20th century, eutrophication caused by substantial fertilizer use, industrial discharge, and high riverine input led to frequent algal blooms, bottom hypoxia, and mucilage events. Over the past three decades, however, environmental regulations and declining river discharge have reduced nutrient input, leading to decreased eutrophication.
These shifts in primary productivity have profoundly impacted marine communities. Understanding how communities respond to such changes is essential as climate change and anthropogenic pressures continue to shape the NAS. Fortunately, the NAS provides historical analogs due to marked fluctuations in freshwater, sediment, and nutrient input during the Holocene.
This study employs nitrogen stable isotope values (δ15N) in shell-bound organic matter of bivalves as a proxy for past primary productivity. δ15N is fractionated by primary producers and reflects nutrient dynamics within an ecosystem. As low-level consumers, bivalves offer δ15N values indicative of the food web base, providing a more stable proxy than primary producers, which are highly sensitive to short-term environmental fluctuations. The robust (sub)fossil record of bivalves allows correlations between changes in primary productivity and community turnovers over time.
Our research focuses on Varicorbula gibba, an infaunal filter feeder abundant in the NAS throughout the Holocene and increasingly dominant during 20th-century eutrophication due to its opportunistic nature. The first step of this study involves calibrating δ15N values from live bivalves against water samples collected across a productivity gradient in the NAS. This calibration will assess how well shell-bound δ15N reflects variations in primary productivity along an onshore-offshore gradient.
δ15N analysis is conducted using the denitrifier method, wherein nitrogen species from bivalve and water samples are oxidized, bacterially transformed into N₂O, and analyzed via mass spectrometry. Understanding how δ15N of V. gibba relates to its environment enables us to extend this analysis to (sub)fossil specimens, reconstructing Holocene primary productivity changes and their ecological impacts.
By providing a historical baseline, this study offers valuable insights into the NAS's past ecosystem dynamics and serves as an analog for predicting future changes under ongoing environmental pressures.
How to cite: Schweigl, L., Moretti, S., and Scarponi, D.: Reconstructing Holocene primary productivity in the northern Adriatic Sea using δ15N of bivalves, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12822, https://doi.org/10.5194/egusphere-egu25-12822, 2025.
Bivalve mollusc shells have proven to be promising recorders of environmental variability on short time-scales: incremental growth over their lifetimes (~ 1 – 100 years) allows for high resolution temporal sampling in their carbonate shells1. Seasonal and even daily environmental variability have successfully been reconstructed using fossil shells, e.g. 2–4.
However, these shells are not made up of pure carbonates but also contain organic matter and internal fluids5. Understanding the formation pathways and associated isotopic and trace elemental fractionation of these components of the shell carbonate system is important to deconvolute the bulk carbonate chemical signal. Furthermore, measurements of oxygen isotopes (δ¹⁸O) of internal fluids and carbonate coupled with clumped isotope (Δ₄₇, Δ₄₈) measurements of the carbonate can constrain disequilibrium precipitation and diagenetic alteration processes6,7. Accounting for these processes allows for improved δ¹⁸O-based temperature reconstructions. As it is yet not well-constrained where internal fluids are present in biogenic carbonates, their significance for shell formation and as an environmental indicator is currently largely unknown8.
Utilizing bivalve molluscs cultivated under closely monitored environmental conditions, we develop a method to quantify the different components of the shell carbonate system, analyse their respective isotopic and elemental signatures and correlate these with conditions experienced during growth. Modern bivalve shells collected from a wide range of present-day climate zones allow us to assess the performance of mollusc shells as archives for environmental conditions. This approach aims to provide a robust framework for improved future mollusc-based climate reconstructions and more accurate interpretation of chemical and isotope proxies in carbonate archives from past climates and environments.
1. Ivany, L. C. Reconstructing paleoseasonality from accretionary skeletal carbonates - challenges and opportunities. Paleontol. Soc. Pap. 18, (2012).
2. de Winter, N. J. et al. Amplified seasonality in western Europe in a warmer world. Sci. Adv. 10, eadl6717 (2024).
3. Kniest, J. F. et al. Dual clumped isotopes from Mid-Eocene bivalve shell reveal a hot and summer wet climate of the Paris Basin. Commun. Earth Environ. 5, 1–10 (2024).
4. Arndt, I. et al. 20,000 days in the life of a giant clam reveal late Miocene tropical climate variability. Palaeogeogr. Palaeoclimatol. Palaeoecol. 112711 (2025) doi:10.1016/j.palaeo.2024.112711.
5. Lécuyer, C. & O’Neil, J. R. Stable isotope compositions of fluid inclusions in biogenic carbonates. Geochim. Cosmochim. Acta 58, 353–363 (1994).
6. Nooitgedacht, C. W., van der Lubbe, H. J. L., Ziegler, M. & Staudigel, P. T. Internal water facilitates thermal resetting of clumped isotopes in biogenic aragonite. Geochem. Geophys. Geosystems 22, e2021GC009730 (2021).
7. Staudigel, P. et al. Fingerprinting kinetic isotope effects and diagenetic exchange reactions using fluid inclusion and dual-clumped isotope analysis. Geochem. Geophys. Geosystems 24, e2022GC010766 (2023).
8. de Graaf, S. et al. Analytical artefacts preclude reliable isotope ratio measurement of internal water in coral skeletons. Geostand. Geoanalytical Res. 46, 563–577 (2022).
How to cite: Oerlemans, B., Goudsmit-Harzevoort, B., van der Lubbe, J. H. J. L., Witbaard, R., van Gils, J., Vroon, P. Z., Peharda, M., Roche, D. M., and de Winter, N. J.: Can we improve the accuracy of climate reconstructions from fossil shells by measuring internal water in their carbonate?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13199, https://doi.org/10.5194/egusphere-egu25-13199, 2025.
Museums worldwide have organized collections of hundreds of corals, yet most studies of coral museum records in the United States focus on DNA for symbiosis and taxonomic investigations. Few researchers have explored processing these collections for insights into ecological resilience, particularly for marine species in and near the Caribbean. This study utilizes two large coral reef databases from natural history museums to track the presence and absence of Floridian coral reef genera and their traits from 1887 to 2024 in response to acute and chronic disturbances. The aim is to identify coral genera and their characteristic traits to better understand the influence of sea surface temperature anomalies and hurricane exposure. These findings are then compared to available in-situ studies to assess whether coral museum records can reliably inform future modeling and enhance understanding of species retention or loss on regional and paleoecological scales. This research serves as a case study for applying similar approaches to other regions in the Caribbean and global reef locations.
How to cite: Griffith, A.: Tracking Reef Resilience Through Museum Collections: Presence-Absence Analysis of Floridian Coral Traits Over Time, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14048, https://doi.org/10.5194/egusphere-egu25-14048, 2025.
The present study provides a long-due taxonomic evaluation of the brachiopods of the Ariyalur sub-basin, Cauvery Basin, India. After the seminal works of Stoliczka (1872), this is the first study on the Late Cretaceous Trichinopoly Group brachiopods. 1507 specimens were collected from the medium-sized sandstone units of the Anaipadi Member and Kulakkanattam Member of the Garudamangalam Formation. Based on their morphology, six rhynchonellid and two terebratulid species are identified. The terebratulids, Sahnithyris andurensis, and Carneithyris carnea are distinctly differentiated based on their body size, shape, and plication. The rhynchonellids, Sillakkudirhynchia plicatiloides, Protegulorhynchia cranifera, Tegulorhynchia squamosa, Orbirhynchia nutans, Orbirhynchia multicostata, Orbirhynchia arrialoorensis are mainly distinguished by the ornamentation pattern, pedicle opening, convexity of both valves and sulcus patterns . Small rhynchonellids dominate our collected samples, and bigger terebratulids represent only 3% of the brachiopod assemblage. Among rhynchonellids, Sillakkudirhynchia plicatiloides, Protegulorhynchia cranifera, Tegulorhynchia squamosa are dominant species. Sillakkudirhynchia plicatiloides shows a right-skewed, Protegulorhynchia cranifera shows a left-skewed, Tegulorhynchia squamosa shows a bell-shaped size distribution due to their difference in mortality rate, recruitment. This study reports the first brachiopod drilling predation from Coniacian. A drilling frequency of 4.3% was observed with predators showing valve selectivity, taxon selectivity, and size (8-17mm) selectivity of prey. A biogeographic study is carried out with the help of six genera and thirteen locations incorporated into four biogeographic regions. India shows its closest similarity (Jaccard = 0.84, Dice = 0.90) with Antarctica and its association with the Austral region. Based on the brachiopod genera distribution, cluster analysis depicts the Austral region’s biogeographic connections with the Central European Region. This indicates probable active seaways through Eastern Tethys to the South Atlantic Ocean during the Late Cretaceous.
How to cite: Mahata, A., Poddar, A., Paul, S., Mukherjee, D., Mukhopadhyay, A., and Chattopadhyay, D.: A long-due taxonomic re-evaluation of the Late Cretaceous (Coniacian-Santonian) brachiopods of Ariyalur, India, and their implications., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17130, https://doi.org/10.5194/egusphere-egu25-17130, 2025.
This study investigates the extent of evolutionary pressure by predatory birds on small mammals. Using neontological datasets of predatory bird and small mammal body masses, diets and activity patterns, we show that small mammals are significantly more likely to be nocturnal than the larger-sized species. We apply allometric scaling laws and estimate potential prey body size distributions of vertebrate-feeding hypercarnivorous birds. Using species-level mammal and bird phylogenetic trees we investigate the timelines of temporal niche change in mammals and compare them with the diversification histories of diurnal predatory birds. Our preliminary results suggest that bird predation pressure has been restricting a significant fraction of small mammals to the nocturnal niche, giving support to the nocturnal bottleneck hypothesis.
This study was supported by the grant S-MIP-24-62 BretEvoGeneralized.
How to cite: Bekeraitė, S., Juchnevičiūtė, I., and Spiridonov, A.: Still in the shadow of the dinosaurs: evidence for avian predation driving nocturnality in small mammals, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18178, https://doi.org/10.5194/egusphere-egu25-18178, 2025.
Commercial whaling peaked between the 1700s and 1800s, leading to declines in whale populations worldwide. While it is well constrained that baleen whales have shrunk in body size over the past centuries - likely due to whaling pressure and climate change – smaller toothed whale species, which were not the primary targets during the whaling era, have been largely understudied in this regard.
However, one of the major challenges in the face of global change and increasing anthropogenic influence is predicting population declines in order to establish suitable conservation strategies before a collapse can take place. Tracking declines in body sizes over large temporal scales has proven to be a reliable indicator preceding such population declines and collapses.
In this study we investigate body sizes of the harbour porpoise (Phocoena phocoena), which is one of the smallest toothed cetacean species and a common inhabitant of European waters. We use skull sizes as proxies for estimating body sizes of individuals collected from Scotland, England and the Netherlands, with collection dates spanning from the 17th century to the present. The aim of this study is to assess whether a decline in harbour porpoise body sizes over time and additionally, if possible morphospecies from different regions of the North Sea, can be identified.
How to cite: Rahman, S. N., Sabin, R., Langeveld, B., IJsseldijk, L., and Jarochowska, E.: Porpoise pasts: A journey through skull size variation in European waters, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18559, https://doi.org/10.5194/egusphere-egu25-18559, 2025.
Conodonts were an extinct group of marine chordates and a crucial part of past ecosystems for approximately 300 million years. They were the earliest vertebrates that developed mineralized tissues in the form of an oral apparatus composed of conodont elements. Those dental parts currently find utility in biostratigraphy, paleoclimatology, and evolutionary biology. Their remains have profoundly influenced disciplines such as stratigraphy, paleoclimatology, and evolutionary biology. However, the understanding of the paleoecology of conodonts and their role in ancient ecosystems is far from being fully resolved. Herein, we adopted a new method of electron scanning microscope and three-dimensional topography to describe transformation of conodont elements during ontogeny. Our findings reveal significant morphological differences between juvenile and adult specimens, with two out of three dental topographic metrics showing notable variation across ontogenetic stages.
How to cite: Świś, P., Bącal, P., Szczygielski, T., and López-Torres, S.: Resolving the conodont trophic enigma with the photogrammetry and dental topography analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19989, https://doi.org/10.5194/egusphere-egu25-19989, 2025.
Chamelea gallina, found in both late Holocene and recent shoreface environments of the Adriatic Sea in Italy, reveals a significant reduction (by an order of magnitude) in parasite-host intensity and abundance before and after notable human impacts. This reduction parallels the increasing human influence on the Adriatic, which has transitioned into an urban sea (Fitzgerald et al. 2024). Despite these findings, empirical studies of parasite-host dynamics often overlook the spatial information inherent in trace locations. Quantifying these spatial patterns in antagonistic interactions provides valuable insights into the relationships between parasites and hosts, helping us understand whether these interactions have remained stable over time or whether they indicate substantial disruptions in ecological functions due to environmental changes.
We employ Spatial Point Pattern Analysis of Traces (SPPAT) to assess variations in the spatial distribution of trematode-induced pits in C. gallina-rich assemblages from shoreface settings of the Po-Adriatic system (northern Italy) across three different geological time periods: the Holocene Climatic Optimum (~7.5ka B.P.), Late Holocene (~2.5ka B.P.), and modern settings. Preliminary results indicate that these traces are significantly clustered in all analyzed geological intervals (as per the DCLF test of Complete Spatial Randomness: HCO: u = 0.006761147, rank = 1, p-value = 0.001; Late Holocene: u = 0.011823097, rank = 1, p-value = 0.001; modern: u = 0.006127347, rank = 1, p-value = 0.001). Additionally, all Holocene spatial patterns exhibit marginally significant segregation at larger distances due to the clustering of pits near the shell edge. However, distance-based statistics and Kernel Density Mapping reveal some variations in the patterns, characterized by the aggregation of pits at medium to short distances, along with some differences in the maximum clustering distance (HCO: 0.58; Late Holocene: 0.39; modern: 0.47).
Although our results are preliminary and subject to the limitations of the data, we demonstrate how the spatial information inherent in parasite-induced traces can complement previous studies on parasite-host dynamics across changing environments and aid in reconstructing the persistence of this critical ecological interaction through time amidst significant anthropogenic changes.
Fitzgerald, E., Ryan, D., Scarponi, D., and Huntley, J. W. 2024: A sea of change: Tracing parasitic dynamics through the past millennia in the northern Adriatic, Italy. Geology; 52 (8): 610–614. https://doi.org/10.1130/G52187.1
Rojas A, Dietl GP, Kowalewski M, Portell RW, Hendy A, and Blackburn JK. 2020: Spatial point pattern analysis of traces (SPPAT): An approach for visualizing and quantifying site-selectivity patterns of drilling predators. Paleobiology; 46(2):259-271. doi:10.1017/pab.2020.15
How to cite: Rojas-Briceno, A., Huntley, J. W., Schweigl, L., and Scarponi, D.: Late Quaternary to modern patterns in the distribution of trematode-induced pits in Chamelea gallina (Po-Adriatic system, northern Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21661, https://doi.org/10.5194/egusphere-egu25-21661, 2025.
Posters virtual: Mon, 28 Apr, 14:00–15:45 | vPoster spot 2
EGU25-16446 | Posters virtual | VPS25
The Venus nux association during the Early Pleistocene of the Adriatic Sea: a comparative analysis with its Pliocene and Recent distributionMon, 28 Apr, 14:00–15:45 (CEST) | vP2.3
Interplay between environmental drivers and antagonistic biotic interactions shape the niche of species. Understanding the extent to which species retain parameters of their ecological niches amid long-term environmental changes is crucial for numerous palaeoecological inferences applicable to conservation efforts, sequence stratigraphic reconstructions, and macroevolutionary theory.
The Venus nux association of the Arda and Stirone River sections (Early Pleistocene, western Emilia, northern Italy) has been here analyzed from a systematic and a paleoecological point of view, resulting in the identification of 23 mollusc taxa. As the majority of the retrieved taxa is represented by living species, a comparison between their fossil and present-day environment has been carried out, focusing also on the Venus nux association during the Pliocene of the same region. This research aimed to assess whether the overall bathymetric range and dominance of the bivalve Venus nux have changed over the last 5 million years in the Adriatic basin. Preliminary results indicate a shift in the ecological niche of this common species during a time marked by increasingly pronounced climatic oscillations.
Indeed, currently, V. nux is rarely retrieved in the Adriatic basin, but it is common in the Alboran Sea and the Ibero-Moroccan Gulf (southern Spain), where it thrives in muddy to muddy-sandy substrates at depths between 30 and 350 meters (Salas, 1996), but typically is abundant within 60 and 120 m depth ranges. Conversely, during the Pliocene and Pleistocene geological intervals, V. nux was common in the sedimentary successions of the Adriatic Basin, though it exhibited dominance at different depths and a potentially different bathymetric range. Specimens of V. nux from the Lower Pleistocene Arda and Stirone River sections reveal a shallower bathymetric distribution (20-40 meters of water depth), as evidenced by the co-occurrence in the mollusc association of shallow-water species, like Mytilus edulis and Ostrea edulis. During the warm Pliocene (Zanclean-Piacenzian transition), its bathymetric distribution was slightly deeper than in the cold Early Pleistocene, possibly mirroring current conditions. Although further detailed studies are necessary, it seems that over the past few million years, this species has changed its niche parameters, possibly due to climate shifts.
Salas, C. 1996. Marine bivalves from off the southern Iberian Peninsula collected by the Balgim and Fauna 1 expeditions. Haliotis 25: 33–100.
How to cite: Crippa, G., Chiari, A., Lombardi, M., and Scarponi, D.: The Venus nux association during the Early Pleistocene of the Adriatic Sea: a comparative analysis with its Pliocene and Recent distribution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16446, https://doi.org/10.5194/egusphere-egu25-16446, 2025.
EGU25-21258 | ECS | Posters virtual | VPS25
Biodiversity loss and the simplification of trophic webs: Lessons from cephalopods in deep timeMon, 28 Apr, 14:00–15:45 (CEST) | vP2.4
Anthropogenic global change and environmental degradation lead to not only declines in biodiversity but also the simplification of trophic webs and fundamental changes in biotic interactions as taxa are removed from ecosystems. These changes are currently playing out over time scales of decades and centuries. Still, it would be instructional to understand the relationships between biotic interactions, diversity, and environmental change through deep time. Here, focusing on cephalopods, we quantify the relationships between antagonistic interactions and estimates of diversity, origination rates, and extinction rates. We have compiled a database of antagonistic biotic interactions preserved on fossil cephalopods composed of 279 species occurrences and 148,846 specimens ranging in age from Silurian to Quaternary. Predation occurrences were sparse in the Paleozoic, with peaks in the Jurassic and Cretaceous. We constructed a Generalized Linear Model comparing predation frequency and parasitism prevalence (for samples whose n ≥ 10) to mean standing genus diversity and three-timer origination and extinction rates using data from the Paleobiology Database and the Shareholder Quorum Subsampling methodology available on the FossilWorks website. A significant positive relationship exists between the frequency/prevalence of antagonistic interactions and mean standing diversity. Origination and extinction rates both have significant negative relationships with antagonistic interactions with much higher coefficients than mean standing diversity. We interpret this to mean that the intensity of antagonistic biotic interactions is higher when diversity is elevated but, more importantly, stable. We think this reflects that many of these interactions are obligate and taxon-specific. Ongoing work will include proxy data for temperature and CO2 concentration. As with modern ecosystems, we see evidence for links between diversity loss and the simplification of trophic webs in deep time.
How to cite: Burman, Z., De Baets, K., and Huntley, J. W.: Biodiversity loss and the simplification of trophic webs: Lessons from cephalopods in deep time, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21258, https://doi.org/10.5194/egusphere-egu25-21258, 2025.
