This session will focus on the emerging discipline of Conservation Paleobiology that uses the data from the fossil record and sedimentary archives to inform biodiversity conservation and ecosystem management. Even though humans have altered ecosystems for millennia, direct ecological observations rarely encompass more than the last few decades. At the same time, the accelerating pace of global climate change requires better understanding of the long-term resilience and adaptive capacities of ecosystems facing multiple stressors. The youngest fossil record can offer high-resolution insights into ecosystem change on timescales well beyond the limits of ecological monitoring, enabling the reconstruction of ecological baselines and natural range of variability. Additionally, the pre-Quaternary geologic record provides a series of natural experiments allowing assessment of biotic responses to major environmental perturbations, strengthening the theoretical foundations of conservation science.
We invite presentations offering both the near-time and deep-time perspective on ecological and evolutionary processes operating during times of rapid environmental changes, ranging from the Anthropocene biodiversity crisis to Phanerozoic mass extinction events. We also welcome contributions highlighting potential biases affecting the fossil record by linking stratigraphic, taphonomic and ecological patterns. We hope to stimulate discussion on novel opportunities and limitations of using different types of geohistorical data to address some of the most urgent questions in Conservation Biology.
vPICO presentations: Thu, 29 Apr
Diel Vertical Migration (DVM) is a key feature of pelagic and mesopelagic ecosystems, mainly driven by predator-prey interactions along a time-varying vertical gradient of light. Marine organisms including meso-zooplankton and fish typically hide from visual predators at depth during daytime and migrate up at dusk to feed in productive near-surface waters during nighttime. Specific migration patterns, however, vary tremendously, for instance in terms of residency depth during day and night. In addition to environmental parameters such as light intensity and oxygen concentration, the migration pattern of each organism is intrinsically linked to the patterns of its conspecifics, its prey, and its predators through feedbacks that are hard to understand—but important to consider.
DVM not only affects trophic interactions, but also the biogeochemistry of the world’s oceans. Organisms preying at the surface and actively migrating vertically transport carbon to depth, contributing to the biological carbon pump, and directly connecting surface production with mesopelagic and demersal ecosystems.
Here, we present a method based on a game-theoretic trait-based mechanistic model that enables the optimal DVM patterns for all organisms in a food-web to be computed simultaneously. The results are used to investigate the contributions of the different food-web pathways to the active component of the biological carbon pump. We apply the method to a modern pelagic food-web (comprised of meso- and macro-zooplankton, forage fish, mesopelagic fish, large pelagic fish and gelatinous organisms), shedding light on the direct effects that different trophic levels can have on the DVM behaviours of each other. The model is run on a global scale to assess the carbon export mediated by different functional groups, through fecal pellet production, carcasses sinking and respiration.
Finally, the model output is coupled to an ocean inverse circulation model to assess the carbon sequestration potential of the different export pathways. Results indicate that the carbon sequestration mediated by fish is much more important than presently recognised in global assessments of the biological carbon pump. The work we present relates to contemporary ecosystems, but we also explain how it can be adapted to fit any pelagic food-web structure to assess the contribution of the active biological pump to the global carbon cycle in past ecosystems.
How to cite: Pinti, J., DeVries, T., Norin, T., Serra-Pompei, C., Proud, R., Siegel, D. A., Kiørboe, T., Petrik, C. M., Andersen, K. H., Brierley, A. S., and Visser, A. W.: Diel Vertical migration of marine organisms and the biological carbon pump, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-198, https://doi.org/10.5194/egusphere-egu21-198, 2021.
Introduced predators currently threaten endemic animals on Madagascar through predation, facilitation of human-led hunts, competition, and disease transmission, but the antiquity and past consequences of these introductions are poorly known. We use radiocarbon and stable carbon and nitrogen isotope data from the bone collagen of introduced dogs (Canis familiaris) and endemic fosa (Cryptoprocta spp.) in central and southern Madagascar to test for competition between introduced and endemic predators. Isotopic evidence indicates little overlap in diet between ancient dogs and fosa in these regions but leaves open the possibility that dogs competitively exclude fosa. Radiocarbon dates confirm that dogs have been present on Madagascar for at least a millennium and suggest that they briefly co-occurred with the island’s extinct megafauna, which included giant lemurs, elephant birds, and pygmy hippopotamuses. Dogs share a mutualism with pastoralists who also at least occasionally hunt, and this is reflected in deposits at several Malagasy paleontological sites that contain dog and livestock bones along with butchered bones of extinct megafauna and extant lemurs. Dogs on Madagascar have had a wide range of diets during the past millennium, but relatively high stable carbon isotope values suggest few individuals relied primarily on forest bushmeat. The absence of distinct dietary differences between dogs from archaeological and paleontological sites may reflect the absence of discrete feral populations. Our data suggest that dogs were part of a suite of animal introductions beginning over a millennium ago that coincided with widespread landscape transformation and megafaunal extinction.
How to cite: Hixon, S., Douglass, K., Godfrey, L., Eccles, L., Crowley, B., Rakotozafy, L., Clark, G., Haberle, S., Anderson, A., Wright, H., and Kennett, D.: Ecological Consequences of a Millennium of Introduced Dogs on Madagascar, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-927, https://doi.org/10.5194/egusphere-egu21-927, 2021.
The fossil records of Insects is quite rich and abundant, telling a story of the group’s rise through the Paleozoic, with the subsequent conquest of sea, land, freshwater and finally, for the first time in history of animals – air. Fossil insects also can tell us about the environment they lived in. It is relatively common to use insect remnants, especially head capsules of non-biting midges (Diptera, Chironomidae) preserved in the sediments from the period including several last Ice ages the Holocene (11650 Years BC – Present) to reconstruct temperatures and the climate patterns of the past. Most of the midges in the Holocene are representatives of modern species, which allows us to extrapolate their ecology from the modern representatives of the same species. Based on our knowledge of the temperature preference of this modern species we can quite easily reconstruct and model their temperature preferences in the past.
Reconstruction of the temperature optimums of all the taxa in the community, together with analyses of the other paleoecological proxies (i.e. plant pollen profiles) enables us to assess the range of the temperatures experienced by the area in which midge samples of Chironomidae was obtained in the Holocene and latest Pleistocene. We cannot rely on such ecological extrapolation from the modern animals' ecology for the animal’s fossil records from the deep past, for example from Cretaceous or Triassic periods.
Therefore, we are proposing a more universally applicable climate proxy, independent of our knowledge of the fossil organism’s ecology. Animal size is one of the best candidates for such proxy. It is well known that the body size of the homoeothermic (“warm-blooded”) animals follows (roughly) so-called Bergman rule when size within the group of organisms is increasing from South to North ( i.e. polar bear and Amur tiger are both the northernmost and the largest representatives of their respective groups). We hypothesized that flies (Diptera) are suitable candidates for a quantitative paleoclimate proxy. Flies are very abundant in the fossil records from the mid Triassic (245 Mya) up until modern time. Their size is appears directly negatively correlated with temperature, i.e. representatives occurring further North are larger than the ones from the equatorial regions. This relationship allows us to use the relationships between the insect size and the geographic latitude at which they occur and the temperature at which these insects occur. Here we present a first results from analysis of > 2000 species of Chironomidae from around the globe, in a phylogenetic-constrained framework. First results are showing that non-biting midge’s wing and body size is growing by about 0.02 mm per one degree of geographical latitude, as one moves from the equator, mostly regardless of the phylogenetic position of the species analysed. This first results are showing that Insect size might be a promising proxy for reconstructing the palaeotemperature.
How to cite: Baranov, V., Hunter-Moffatt, B., Noori, S., Schölderle, S., and Haug, J. T.: Modern and fossil insects body size as a possible proxy to understand environments of the past, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9134, https://doi.org/10.5194/egusphere-egu21-9134, 2021.
Climate change has a great impact on boreal ecosystems including Siberian larch forests. As a consequence of warming, larch grow is possible in areas where climate used to be too cold, leading to a shift of the tree line into more arctic regions. Most plants co-exist in symbiosis with heterotrophic organisms surrounding their root system. In arctic ecosystems, mycorrhizal fungi are a prerequisite for plant establishment and survival because they support nutrient uptake from nutrient-poor soils and maintain the water supply. Until now, however, knowledge about the co-variation of vegetation and fungi is poor. Certainly, the understanding of dynamic changes in biotic interactions is important to understand adaptation mechanisms of ecosystems to climate change.
We investigated sedimentary ancient DNA from Lake Levinson Lessing, Taymyr Peninsula (Arctic Siberia, tundra), Lake Lama, Lake Kyutyunda (both northern Siberia, tundra-taiga transition zone) and Lake Bolshoe Toko (southern Siberia, forest area) covering the last about 45.000 years using ITS primers for fungi along with the chloroplast P6 loop marker for vegetation metabarcoding. We found changes in the fungal communities that are in broad agreement with vegetation turnover. To our knowledge, this is the first broad ecological study on lake sediment cores to analyze fungal biodiversity in relation to vegetation change on millennial time scales.
How to cite: von Hippel, B., Stoof-Leichsenring, K. R., Schulte, L., Seeber, P., Epp, L. S., Lenz, M., Scheidt, S., and Herzschuh, U.: Fungi and plant co-variation in Arctic Siberia inferred from sedimentary ancient DNA metabarcoding during the last 45.000 years, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14604, https://doi.org/10.5194/egusphere-egu21-14604, 2021.
Current and future climate change is a serious threat to biodiversity and ecosystem stability. With a rapid increase of global temperatures by 1.5°C since the pre-industrial period and a projected warming of 1.5-4°C by the end of this century, plant species are forced to either adapt to these changes, shift their distribution range to higher elevation, or face population decline and extinction. Today, there is an urgent need to better understand the responses of mountain vegetation to climate change in order to predict the consequences of the human-driven global change currently occurring during the Anthropocene and maintain species diversity and ecosystem services. However, most predictions are based on short-term experiments. There is, in general, an insufficient use of longer time scales in conservation biology to understand long-term processes. Palaeoecological data are a great source of information to infer past species responses to changing environmental factors, such as climate or anthropogenic disturbances.
The last climate change of a similar magnitude and rate as projected for this century was the transition between the last Ice Age and the Holocene interglacial (ca. 11,700 years ago). By analyzing subfossil plant remains such as plant macrofossils, charcoal and pollen from natural archives, we can study past responses to climate change. However, until recently it was not possible to reconstruct changes at the population level. With the development of new methods to extract ancient DNA (aDNA) from plant remains and next generation DNA-sequencing techniques, we can now infer past population dynamics by analyzing the genetic variation through time. Ancient DNA might also be able to reveal if species could adapt to climatic changes by identifying intraspecific variation of specific genes related to climatic adaptations.
We are currently investigating a palaeoecological archive from a high-altitude mountain lake, Lai da Vons (1991 m a.s.l), situated in Eastern Switzerland. We are presenting preliminary macrofossil, pollen and charcoal results to reconstruct local to regional vegetation and fire dynamics with high chronological precision and resolution. In a next step, we will use novel molecular methods, in order to track adaptive and neutral genetic diversity through the Holocene by analyzing aDNA from subfossil conifer needles. The overarching goal of this large-scale, multiproxy study is to better understand past vegetation dynamics and the impact of future climate change on plants at multiple scales; from the genetic to the community level.
How to cite: Dziomber, L., Gurtner, L., Leunda, M., and Schwörer, C.: A multiproxy reconstruction of vegetation dynamics in the Eastern Alps (Switzerland): combining paleoecological and paleogenetic approaches., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14457, https://doi.org/10.5194/egusphere-egu21-14457, 2021.
This study aims at checking the quality of the sedimentary record preserved on the deltaic seafloor by analyzing the deposits preserved in 4 shallow cores. These have been collected by scuba diving at four different depths (10m, 20m, 30m and 40m) just in correspondence of the delta of the Entella river, in the Gulf of Tigullio (Western Ligurian Sea - Italy).
The Entella river runs through several onshore sites that can have been potential source of pollution or contamination of the marine system in the past and thus potentially preserved in the sedimentary sequence. Among those sites the possible contamination sources could be caused by extensive human activities such as production and processing of thermoplastic material, vegetable oils, junkyards, several quarries (limestone and slate), landfill of solid urban waste.
The core subsampling was directly performed onboard of the support vessel immediately after underwater collection. In total four cores, with a length comprised between 26 and 44 cm, have been collected. Each core was cut into 2-cm slices, which were then further divided in half.
The first half of sediment has been placed in a plastic bag in order to perform the followed analyses: granulometry, content of organic/inorganic matter by thermogravimetric method, XRPD analyses, C14 radiometric dating and chemical component analysis.
The second half of sediment, stored into a glass jar (to prevent plastic contamination), has been used to search for both agglutinated microplastics on picked agglutinated foraminifera and further microplastics on filters. Filters have been prepared using density separation in supersalty aqueous solution and filtration. Investigations have been performed by optical microscopy and µRaman spectroscopy. Since the analysis of the whole filter is extensively time-consuming, due to the high number of items present, we have tested a statistical approach to optimize the filter investigation.
All the data obtained were processed using the statistical software R. Multivariate analyses have been performed for the granulometry dataset as well as for other data. The results seem to point to specific trends characterized by possible seasonal fluctuations registered in the sedimentary sequence. The mineralogy dataset, investigated by cluster analysis, points to a clear separation of the mineralogical composition of the shallower versus the deeper cores. Interestingly, agglutinated foraminifera (i.e., mostly textulariids) seem to agglutinate large amount of carbon grains and plastics have been not yet observed.
How to cite: Altieri, C., Briguglio, A., Carbone, C., Consani, S., Cutroneo, L., Geneselli, I., Malatesta, A., Reboa, A., and Capello, M.: What do shallow cores tell us when drilled in an anthropogenically active delta from northwest Italy?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3484, https://doi.org/10.5194/egusphere-egu21-3484, 2021.
The definition of reference conditions has a major role for the understanding of the present-day and paleoecological quality status on transitional environments. The estuarine quality paradox and the paucity of unimpacted sites make the definition of reference conditions a challenging task. In this context, the integration of biological indicators with stratigraphic data is essential, as the vertical stacking pattern of facies composing the shallow subsurface of modern coastal plains reflects changes in physical-chemical parameters which, in turn, affect (paleo-)biotic communities.
In the Po coastal plain (N Italy), the mid to late Holocene back-barrier succession of the Mezzano Lowland and the adjacent present-day Bellocchio Lagoon offer a unique example of pristine paralic system for comparing reference conditions defined in fossil and modern settings, respectively. Benthic foraminifers and ostracods from the Mezzano succession allowed us to investigate vertical (i.e., temporal) and lateral (i.e., spatial) changes in (paleo-)environmental conditions, in analogy to the lateral variations recorded at the Bellocchio Lagoon.
Both sites present subtidal channel sands almost barren in autochthonous meiofauna and fine-grained lagoon sediments with abundant benthic foraminifers and ostracods mostly represented by euryhaline taxa recording the highest diversity. Intertidal muddy deposits are also recorded, including mud flat clays with abundant oligotypic assemblages dominated by highly-confined benthic foraminifers. In the present study, we demonstrate that changes in modern benthic foraminifer assemblages diversity and composition often interpreted as perturbations of ecological conditions in response to anthropogenic pressures also occur under natural state, as confirmed by paleoenvironmental conditions recorded by ostracods. This reflects the effects of authogenic processes at short time and geographic scales.
How to cite: Barbieri, G., Rossi, V., Armynot du Châtelet, É., Da Prato, S., Mazzini, I., Vaiani, S. C., and Frontalini, F.: How can stratigraphy contribute to conservation paleobiology? Insights from a mid-Holocene to present-day transitional system of the Po coastal plain (N Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14128, https://doi.org/10.5194/egusphere-egu21-14128, 2021.
The Mediterranean striped venus (Chamelea gallina) is a valuable economic species in the Mediterranean Sea. In the last decades the over-exploitation of this fishing resource and the occurrence of several mass mortality events, lead to a strong quantitative decline in clam population density in the Adriatic Sea. Studying the effects of climate-driven changes of environmental factors on C. gallina, therefore, is of increasing interest both from an academic and economic point of view.
Previous studies have mainly focused on population dynamics, shell growth and structure of this species in the present-day Mediterranean Sea. In contrast, there is no information about shell variations in relation to climate-driven environmental change along temporal gradients.
This ongoing study investigates and contrasts variations in shell microstructure and shell growth parameters of C. gallina assemblages from Holocene sedimentary archives of the Northern Adriatic (Italy). Four shoreface-related C. gallina horizons are being evaluated: two from the present-day Adriatic setting and two from the Middle Holocene sedimentary succession of the Adriatic-Po system, when regional sea surface temperatures were higher than today, thus representing a possible analogue for the near-future global warming. Specifically we aim to: 1) determine the life span of selected specimen using three independent ageing methods (shell surface growth rings, shell internal bands and stable isotope composition); 2) determine shell growth parameters and functions concerning linear extension and net calcification rates for each assemblage investigated.
This approach should give access to an archive of ecological responses to past climate transitions and enabling reconstruction of the C. gallina natural range of variability on time-scale well beyond the ecological monitoring or small-scale experiments. Additionally, the young (sub)fossil record should offer insights on the adaptive capacities of C. gallina facing near-future anthropogenic warming and may allow implementation of a more effective management of this economically important bivalve species in the near-future.
How to cite: Cheli, A., Mancuso, A., Prada, F., Baseotto, A., Falini, G., Goffredo, S., and Scarponi, D.: Climate change influence on calcification of the bivalve Chamelea gallina in the Adriatic Sea: exploring a temporal gradient from the Holocene to modern days, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15750, https://doi.org/10.5194/egusphere-egu21-15750, 2021.
The Northern Adriatic Sea is one of the most impacted ecosystems worldwide with a long history of anthropogenic impacts, ranging from overfishing and bottom trawling to eutrophication, deoxygenation and pollution. The impact of these multiple pressures on populations of economically important species is often difficult to evaluate due to paucity of long-term monitoring data. The edible bivalve Noah’s Ark shell (Arca noae L.) was intensively harvested in the eastern Adriatic Sea until 1949-1950 when it suffered a catastrophic population collapse due to unknown agents. The assessment of its subsequent recovery is hindered by the lack of data on the population size structure prior to that event. To reconstruct the natural baseline state of populations of A. noae before the onset of extensive harvesting, we studied fossil assemblages from two 1.5-m-long sediment cores collected in the southern Gulf of Trieste (off Piran, Slovenia), both recording the last ~9,500 years.
The abundance and shell length of A. noae remained low in the lower part of the cores but increased strongly within the oyster-Arca shell bed corresponding to maximum flooding and early highstand sea-level phases (6,500-1,000 years ago). In contrasts, the top 8 cm of the core (the late highstand phase), marked by high concentration of pollutants and organic enrichment, contained only few and small (< 10 mm) A. noae shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of A. noae, persisting there for several thousand years, were locally extirpated in the 20th century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of fossil A. noae from the shell bed interval to the previously published data on living populations of this species sampled along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar median size, modal size class and proportion of specimens > 50 mm (minimal legal landing size). These results suggest that within few decades after the 1949-1950 mass mortality event the size structure of populations of A. noae have largely returned to their earlier, natural state. The recovery was spatially variable, however, as attested by the decline of A. noae populations due to loss of suitable shell-bed habitats in the two studied stations off Piran.
How to cite: Macharia, S., Nawrot, R., Berensmeier, M., Gallmetzer, I., Haselmair, A., Tomašových, A., and Zuschin, M.: Reconstructing the baseline population structure of the exploited bivalve Arca noae in the Northern Adriatic Sea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7694, https://doi.org/10.5194/egusphere-egu21-7694, 2021.
Benthic communities in the Northern Adriatic Sea experienced major environmental and ecological changes during the late Holocene, particularly in the late 20th century due to anthropogenic induced stressors such as hypoxic events. These events lead to mass mortalities and changes in benthic communities. Here, we assess stratigraphic changes in bulk sediment geochemistry and sedimentological attributes to quantify the magnitude and timing of environmental changes and to correlate them to ecological changes. We focus on the reconstruction of the micro- to macrobenthic community composition (foraminifera, ostracods, bivalves and gastropods) prior and after major anthropogenic impacts. We investigate the differences in responses of these taxonomic groups to environmental changes and account for the impact of time-averaging.
The 3-m-long gravity core was collected at 31 m water depth, off the Po prodelta in the western part of the northern Adriatic Sea. The upper 60 cm of the core represent a condensed record determined by sediment bypassing and winnowing during the early and late sea level highstand. In total, 50 shells of the common bivalve Corbula gibba were dated by 14C-calibrated amino acid racemization (AAR) from the upper 30 cm and plant remains were dated by 14C from deeper parts. These analyses show that median shell ages of Corbula decline downcore, from ~50 years in the top 2.5 cm to 1,400 years in the 5-7.5 cm increment, 2,900 years in the 10-12.5 cm increment, and 4,500 years in the 17.5-20 cm increment. Median age in the 28-33 cm increment is again 3,600 years, indicating effects of mixing. The youngest shell corresponds to 24 years BP in the top 2.5 cm and the oldest shell to to 7800 years BP at the base at 30 cm. The 60 cm-long highstand record can be divided in 4 major intervals:
(1) Early-highstand sediments cover the development of a baseline community. Total abundances of micro-and macrobenthic species increase upwards (2) In the late-highstand sediments (around 12.5-15 cm), micro-and macrobenthic absolute species abundance are highest. Increase in eutrophication and heavy metal pollution is indicated by rising N levels and Pb content in bulk sediments. (3) At 5 cm depth, a major anthropogenic environmental shift indicated by strong pollution (Pb and Hg) and eutrophication (TOC) coincides with a strong decline in micro-and macrobenthic abundance and diversity (4) The surface-mixed layer yields a slight increase in micro-to macrobenthic abundances, next to a slight decrease of heavy metal pollution and eutrophication.
14C-calibrated AAR shell ages indicate a relatively limited, centennial time averaging (measured by interquartile age ranges) of Corbula in the uppermost increment but then show a millennial-scale time-averaging below the uppermost surface-mixed layer. This can be linked to a decrease in bioturbation in the 20th century and to a slight increase in sedimentation rate. Although the record is affected by time-averaging, the micro-and macrobenthic community abundances show a distinct pattern that can be related to environmental changes from geochemical sediment proxies. Benthic foraminifers, ostracods and mollusks abundance show similar responses to sedimentological and geochemical tracers in these condensed sediments.
How to cite: Berensmeier, M., Tomašových, A., and Zuschin, M.: Micro- and macrofaunal responses to major environmental changes in Holocene highstand sediments from the Northern Adriatic Sea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15320, https://doi.org/10.5194/egusphere-egu21-15320, 2021.
Over the last century, the northern Adriatic Sea has faced multiple ecological threats such as hypoxic events, eutrophication, pollution by heavy metals and plastics, and bottom trawling. These impacts were associated with major changes in the composition of benthic communities, particularly a decline in the abundance of Turritellinella tricarinata (= Turritella communis), the dominant gastropod species in the previously widespread Turritella-biocenosis of the northern Adriatic muddy bottoms. In this study, we reconstruct changes in abundance and size structure of T. tricarinata populations over the last 6000 years to better understand the drivers responsible for its recent decline and to provide a historical baseline for assessing potential recovery.
We studied sediment cores from two locations in the western Northern Adriatic Sea: (1) distal zones of Po prodelta based on a 3-meter-long gravity core collected at 31 m water depth comprising a condensed record of the last ~9,100 years, (2) proximal zones of Po prodelta based on five 1.5-meter-long piston cores taken at 21 m water depth in the Po prodelta, which capture the last 100-150 years. Core chronologies are based on radiocarbon-calibrated amino-acid racemization analyses of bivalve shells.
We analysed changes in the abundance and shell height of T. tricarinata in each increment of the cores. In total, 600 specimens have been measured. All stations show a similar pattern in shell abundance: a climax in the early 20th century and a strong decrease in the late 20th century.
The proximal records of Po prodelta show a negative correlation between abundance and median shell size, with larger size and lower abundance in the late the 20th century, a period characterized by recurrent severe hypoxic events. The 3-meter-long offshore core contains on average smaller specimens, but reflects a similar pattern: the number of larger specimens (>10 mm) and median shell sizes increase slightly towards the core top while total abundance declines. This trend towards larger shell size and lower abundance may reflect the complex effect of nutrient enrichment in a highly disturbed environment. During the last century Turritella communis might experience higher growth rates and lower predation but simultaneously reduced recruitment due to hypoxia and pollution.
How to cite: Scheidl, A., Berensmeier, M., Nawrot, R., Albano, P. G., Tomašových, A., and Zuschin, M.: Stratigraphic changes in shell size of a turritellid gastropod in the Holocene fossil record of the Po prodelta (Northern Adriatic Sea), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9604, https://doi.org/10.5194/egusphere-egu21-9604, 2021.
Differences in the taxonomic or functional composition of living and death assemblages is a key means of identifying the magnitude and drivers of past ecological changes in conservation paleobiology, especially when assessing the effects of anthropogenic impacts. However, such live-dead differences in species abundances can arise not only from ecological (stochastic or deterministic) changes in abundance over the duration of time averaging but also from interspecific differences in the postmortem durability of skeletal remains or from the lifespan of the individuals. Here, we attempt to directly incorporate the effects of durability on species abundances in death assemblages by modeling dead abundance as a function of species’ durability traits and using abundances in living assemblages as a prior. Species inferred to be negatively affected by anthropogenic impacts should be over-represented in death assemblages relative to their abundance in death assemblages predicted by the durability model (rather than just relative to their abundance in living assemblages). Using species-level durability trait data for bivalves (shell size, thickness, mineralogy, shell organic content, and life habit) from the southern California shelf, we find that, among these traits, valve thickness correlates consistently positively and at multiple spatial scales with the log of the dead:live ratio of species abundances, and accounts for ~20-30% of live-dead mismatch. Using this benchmark for the discordance that might be taphonomic in origin, we confirm that the over-representation of epifaunal suspension-feeders and siphonate deposit-feeders in death assemblages of the southern California shelf owes in fact to their ecological decline in recent centuries, even when accounting for their greater durability.
How to cite: Tomašových, A. and Kidwell, S. M.: Testing the effects of durability (shell thickness) on species over-representation in death assemblages, a taphonomic baseline for conservation paleobiology, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13291, https://doi.org/10.5194/egusphere-egu21-13291, 2021.
Fish otoliths are incrementally growing aragonitic elements found in the inner ear of most fishes. They have species-specific morphology that enable species level identification and they are excellent high-resolution recorders of ambient water conditions, enabling the reconstruction of past fish faunas and their environment. Although they have been studied as fossils for almost 150 years, and they are very useful tools for tracking lifestyle and population changes in modern fishes, otolith death assemblages recovered from sea bottom sediments have been studied only much more recently. Still, these fish remains can provide valuable insight into past fish faunas before most anthropogenic impacts, such as climate warming, habitat modification and biological invasions. Here, we present an overview of research done until now on otolith death assemblages highlighting their applications for marine conservation.
How to cite: Agiadi, K. and Albano, P. G.: Addressing challenges in biodiversity conservation with fish otolith death assemblages: the state-of-the-art, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-879, https://doi.org/10.5194/egusphere-egu21-879, 2021.
The Lessepsian invasion – the largest marine biological invasion – followed the opening of the Suez Canal in 1869 (81 years BP). Shortly afterwards, tropical species also distributed in the Red Sea appeared on Mediterranean shores: it was the dawn of what would become the invasion of several hundred tropical species. The time of the Suez Canal opening coincided with an acceleration in natural history exploration and description, but the eastern sectors of the Mediterranean Sea lagged behind and were thoroughly explored only in the second half of the 20th century. Many parts are still insufficiently studied today. Baseline information on pre-Lessepsian ecosystem states is thus scarce. This knowledge gap has rarely been considered by invasion scientists: every new finding of species belonging to tropical clades has been assumed to be a Lessepsian invader.
We here question this assumption by radiocarbon dating seven individual tests of miliolids – imperforated calcareous foraminifera – belonging to five alleged non-indigenous species. Tests were found in two sediment cores collected at 30 and 40 m depth off Ashqelon, on the Mediterranean Israeli shelf. We dated one Cribromiliolinella milletti (core at 40 m, 20 cm sediment depth), three Nodophthalmidium antillarum (core at 40 m, 35 cm sediment depth), one Miliolinella cf. fichteliana (core at 30 m, 110 cm sediment depth), one Articulina alticostata (core at 40 m, 35 cm sediment depth) and one Spiroloculina antillarum (core at 30 m, 110 cm sediment depth). All foraminiferal tests proved to be of Holocene age, with a median calibrated age spanning between 749 and 8285 years BP. Only one test of N. antillarum showed a 2-sigma error overlapping the time of the opening of the Suez Canal, but with a median age of 1123 years BP. Additionally, a thorough literature search resulted in a further record of S. antillarum in a core interval dated 1820–2064 years BP in Turkey.
Therefore, these foraminiferal species are not introduced, but native species. They are all circumtropical or Indo-Pacific and in the Mediterranean distributed mostly in the eastern sectors (only S. antillarum occurs also in the Adriatic Sea). Two hypotheses can explain our results: these species are Tethyan relicts that survived the Messinian salinity crisis (5.97–5.33 Ma) and the glacial periods of the Pleistocene in the Eastern Mediterranean, which may have never desiccated completely during the Messinian crisis and which may have worked as a warm-water refugium in the Pleistocene; or they entered the Mediterranean Sea from the Red Sea more recently but before the opening of the Suez Canal, for example during the Last Interglacial (MIS5e) high-stand (125,000 years BP) when the flooded Isthmus of Suez enabled exchanges between the Mediterranean and the Indo-Pacific fauna. The recognition that some alleged Lessepsian invaders are in fact native species influences our understanding of the invasion process, its rates and environmental correlates.
How to cite: Albano, P. G., Sabbatini, A., Lattanzio, J., Steger, J., Szidat, S., Hua, Q., Kaufman, D., Zuschin, M., and Negri, A.: Radiocarbon dating of individual foram tests show that alleged Lessepsian species are of Holocene age, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6206, https://doi.org/10.5194/egusphere-egu21-6206, 2021.
The distribution of modern benthic foraminifera is studied from offshore reefs of Brunei Darussalam located in northwest Borneo with enhanced siliclastic influence, and from Louisa Reef, an atoll in the Southern Spratly Islands under fully carbonatic environment. The main families of larger benthic foraminifera found from offshore reefs of Brunei are the Calcarinidae, Amphisteginidae and the Operculinidae, while at the Louisa Reef are the Calcarinidae, Amphisteginidae and the Soritidae. Larger benthic foraminifera are mainly concentrated in the tropical regions and in shallow waters, and their distribution depends on important environmental factors such as water depth, sunlight and type of sediment. Migration of LBF has been recorded since the Paleogene from the Americas to Africa and the Mediterranean Sea, and later to the Indo-Pacific where the modern biodiversity hotspot occurs. Hence looking into any possible migration throughout certain groups of LBF could help in understanding their biogeographic distribution through time within the Indo-Pacific region. Along the atolls in South China Sea the marine environments meet their living preferences, hence tracing their presence, distributions, and abundances could shed further light on their regional migration pattern.
How to cite: Goeting, S., Briguglio, A., Kocsis, L., and Roslim, A.: Tracing migration of larger benthic foraminifera across atolls in the South China Sea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7479, https://doi.org/10.5194/egusphere-egu21-7479, 2021.
Coral reefs throughout the world are well known for the dominance of scleractinian corals. However, one group of hydrozoan corals can be very common in modern tropical coral reefs as well: Millepora, the fire coral. The modern Red Sea is particularly well known for its high abundances of Millepora, where the fire coral is dominant on current-exposed reefs. Yet, this hydrozoan has been described as rare in the fossil record throughout the world and the documented abundances in fossil reefs do not match the numbers from modern reefs. The main interpretation to explain this phenomenon so far has been a lower preservation potential of milleporids compared to scleractinians due to differences in skeletal structure.
During an investigation of six Eemian Egyptian reef sites (29 line intercept transects, typically of 20 m length) we found Millepora in 69% of the fossil reef transects. The abundances were comparable to the adjacent modern reefs (65.13% to 0.26%). Preservation of fossil Millepora was good to excellent and in some cases well-preserved pore characters allowed for identification to species level. Our findings seem to be in stark contrast to results and interpretations of earlier studies, which suggest that Millepora is very rare in the fossil record globally. To understand the reason for this mismatch, we compared the associated scleractinian fauna between fossil reefs with and without Millepora presence. Furthermore, as a differentiation between shallower habitats close to the reef edge and deeper habitats along the reef slope was possible, we were able to investigate habitat preferences. Porites abundances were higher in fossil reefs without Millepora. Based on a comparison with modern communities, this suggests that the exposure to water energy might be a decisive factor for Millepora presence in the fossil reef. Therefore, preservation and consecutive investigation of appropriate fire coral-habitats is a pre-requisite for valid comparisons.
Another factor for the mismatch between our results and earlier studies might be a difference in diagenetic conditions that allow preservation of hydrozoan skeletons in the fossil record. Preservation of the investigated Egyptian sites is favored by their young geological age and their geographic location in a desert climate, reducing dissolution by aggressive meteoric waters. Furthermore, the extremely high abundance of Millepora in modern Red Sea coral reefs may in part mitigate the lower preservation potential of the hydrozoan skeleton in comparison with that of scleractinian corals.
How to cite: Ivkić, A., Kroh, A., Mansour, A., and Zuschin, M.: Unexpected abundance: Millepora corals in Late Pleistocene reefs of Egypt, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10057, https://doi.org/10.5194/egusphere-egu21-10057, 2021.
Many studies focus on modern coral reefs and their associated invertebrate fauna, but not much is known about the paleoecology and diversity of molluscs of Late Pleistocene coral reefs, which were formed during the last interglacial MIS5e. This study is investigating the molluscan assemblage of a Late Pleistocene coral reef in southern Egypt, at the locality Sharm El Luli, in the area of Marsa Alam. The locality is characterized by a variety of reef- and reef associated habitats, including a reef flat, reef slope, a patch reef, and soft bottoms of a lagoon and in the backreef area. We quantitatively and qualitatively sampled 10 sites with a total of 79 samples and collected 2126 shells, which belong to 177 taxa, mostly identified to the species level. Most taxa were found with the qualitative sampling approach. The most abundant bivalves taxon was the epifaunal, encrusting Chama spp., the most abundant gastropod species was the cerithiid Rhinoclavis vertagus. Regarding the life habitats most bivalve species are infaunal filter feeders, while most gastropods are epifaunal carnivores. Alpha diversity is highest in the coral patch and in the upper reef region, which implies the reef slope, the reef flat as well as the transition between reef slope and the lagoon. Preliminary statistical results suggest a division in coral-patch, lagoon and backreef as well as a cluster of upper-reef habitats. From these two broad environments can be distinguished: hard bottoms associated to reefs and reef-associated soft bottom environments. The former are best characterized by encrusting taxa such as Chama spp. and Spondylus spp., and by Tridacna maxima and Perigylypta spp., which are well-known reef associates. Gastropods in this environment are predatory conids and cypraeids. All of these species live on - or occur cryptically in - structured hard bottoms. Reef associated-soft bottom environments are best characterized by infauna, such as the tellinid Quidinipagus palatam and the lucinids Anodontia kora and Pillucina vietnamica. Furthermore, many soft bottom gastropod species such as the strombid Gibberulus gibberulus albus, the cerithiid Rhinoclavis vertagus, both with an herbivorous diet, and the nassariid Nassarius fenistratus, a scavenger, can be found here. A comparison with modern datasets from the Red Sea indicates strong similarities in faunal composition and habitat diversity between fossil and recent reefs. Furthermore, our preliminary results suggest that Late Pleistocene molluscan assemblages can aid in reconstruction of associated fossil reef habitats.
How to cite: Haider, A., Ivkić, A., Kroh, A., Mansour, A., and Zuschin, M.: Fossil molluscan fauna reflects zonation of a Late Pleistocene reef of the Red Sea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16060, https://doi.org/10.5194/egusphere-egu21-16060, 2021.
Taphonomic effects complicate the assessment of variations in biodiversity over time. Most pre-Cenozoic fossil assemblages have been altered through taphonomic effects, such as lithification and aragonite dissolution. Several studies have found alpha (local) and gamma (global) diversity in marine ecosystems to be low in the early Mesozoic and then increase throughout the Mesozoic, reaching a maximum in the Cenozoic.
The Middle to Late Triassic Cassian Formation, exposed in the Dolomites, Southern Alps, northern Italy, comprises tropical reef basin and transported platform assemblages characterized by high diversity and commonly excellent preservation of fossils. The Cassian Formation yields high alpha (mean species richness per locality: 96), beta (mean Jaccard dissimilarity: 0.95), and gamma (1421 invertebrate species) diversity. The high primary diversity is probably due to the tropical reef-associated setting, and its reduced taphonomic alteration caused 4.5 times higher biodiversity to be preserved than in comparable pre-Cenozoic settings. High beta diversity can be explained by the presence of various habitat types and may also have been driven by priority effects. The Cassian fauna, like most comparable modern ecosystems, features a large number of gastropods (39% of all invertebrates, 58% of mollusks are gastropods). Especially small species in the millimeter size range contribute to the large number of gastropod species in the Cassian Formation. Our results support the assumption that the Modern Evolutionary Fauna was already established early in the Mesozoic and that the scarcity of small gastropods in many fossil assemblages is a taphonomic phenomenon. This contradicts the view that the major radiation of gastropods and the generally very strong increase in biodiversity largely took place in the Cenozoic. We suggest that highly complex, gastropod-dominant marine benthic ecosystems are as old as Middle/Late Triassic, pointing to an earlier establishment of the Modern Evolutionary Fauna than previously assumed. An improved eco-space utilization by infaunalization and increased biotic interactions such as a predator/prey escalation may have contributed to the high biodiversity and may reflect early aspects of the Marine Mesozoic Revolution.
How to cite: Roden, V. J., Nützel, A., and Kiessling, W.: The effect of preservation on diversity in a Triassic reef basin assemblage, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10632, https://doi.org/10.5194/egusphere-egu21-10632, 2021.
In order to reveal the response of benthic foraminifera to Cretaceous-Paleogene (K/Pg) boundary event, a high-resolution benthic foraminiferal study was carried out from a land-based Haymana section which is biostratigraphically complete, and once located in the northern branch of the Tethyan Ocean. To this end, 25 samples collected from deep marine succession of the Haymana Basin were quantitatively assessed along with the utilization of quantification of species, morphogroup analysis and diversity indices to establish remarkable changes in biofacies which resulted from the boundary event.
Depositional environment is inferred as upper bathyal (200-600 m) throughout the studied section based on foraminiferal associations. Bathymetric marker species include mainly bi- to triserial forms in Maastrichtian, which favor this interval. Calcareous taxa including Bolivinoides draco, Eouvigerina subsculptura, Nonionellina sp. 1, Pseudouvigerina plummerae, Pyramidina minuta, as well as species belonging to Gyroidinoides, Laevidentalina, Lagena, Lenticulina, Pullenia, and Sitella are together forming 30% of the whole assemblage in this study, which are also attributed as Shallow Bathyal Assemblage of Widmark and Speijer (1997b) from the upper bathyal environment. Accompanied agglutinated taxa are consisting of Clavuinoides trilatera, Arenobulimina sp., as well as species of Dorothia, Gaudryina, Verneuilina, and Heterostomella, which are reported from low and mid-latitude Slope Deep Water biofacies of Kuhnt et al. (1989). There was probably no paleobathymetric change in the Danian, as it is concluded from the structure of the faunal assemblage. Besides, calcareous taxa are found to be more abundant with respect to agglutinated taxa within the whole section, offering deposition over Carbonate Compensation Depth (CCD) level.
With this study, Eouvigerina subsculptura Acme Zone is newly offered for the uppermost Maastrichtian, and also aligned with Bolivinoides draco Zone, since it is existing as very abundant in all samples. Besides, Angulogavelinella avnimelechi-Anomalinoides rubiginosus Interval Zone (BB1) is assigned for the lowermost Danian section based on marker Paleocene species.
Based on this benthic foraminiferal record, a highly diverse foraminiferal assemblage is observed in the Maastrichtian, then it is replaced with a poor to moderate diversity assemblage in the Danian. This finding is presented by diversity indices (Fisher alpha, Shannon H and Berger Parker). Presence of diverse morphogroups together in the upper Maastrichtian section along with taxa preferring high nutrient levels including E. Subsculptura (11-23%), Sliteria varsoviensis (0-6%), Praebulimina reussi (2-9%), Heterostomella spp. (4-11%) and Sitella spp. (1-13%) suggests meso- to eutrophic conditions in this section. A sudden change in the faunal composition right after the K/Pg boundary offers depleted food flux into the bottom of the basin. Infaunal morpogroups decline after the boundary in the Danian section, whereas epifaunal morphogroups including mostly opportunistic Cibicidoides spp. (17%), increased in number in this section. The timing of this record is coinciding with the worldwide primary productivity collapse and planktonic foraminiferal mass extinction during the K/Pg boundary event.
Keywords: K/Pg boundary, deep sea benthic foraminifera, quantitative assessment, paleoenvironment, Haymana Basin
How to cite: Vardar, E. and Özkan-Altıner, S.: Deep sea benthic foraminiferal record from the Haymana Basin (Turkey): changes in abundance patterns and diversity across Cretaceous-Paleogene boundary, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15764, https://doi.org/10.5194/egusphere-egu21-15764, 2021.
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