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Datasets and R code for Bottini et al. (2022) Effects of methylmercury and food stress on migratory restlessness in song sparrows, Melospiza melodia
No full textThis folder contains all the datasets and R code needed to reproduce the analysis of manuscript from Bottini et al. 2022 “Effects of methylmercury and food stress on migratory activity in song sparrows, Melospiza melodia”, published in Hormones and Behavior journal.Link to the article is provided below.Article's Highlights: • Exposure to contaminants and/or stressors can hinder songbirds' migration. • Carry-over effects of MeHg exposure and food stress on song sparrows were assessed. • Nocturnal activity increased in MeHg-exposed birds and varied with food stress. • Treatments and time affected corticosterone and body mass, but not thyroxine. • Fecal corticosterone was positively correlated with nocturnal activity
Warming and cooling episodes across the early Aptian Oceanic Anoxic Event 1a: the role of pCO2 on climate changes
No full textThe early Aptian Oceanic Anoxic Event 1a (OAE 1a: ~120 Ma) is a global phenomenon of organic matter burial in oxygen-depleted oceans. Volcanism, associated with the emplacement of the Ontong Java Plateau (OJP), is thought to be the main triggering mechanism for global anoxia, ocean acidification and greenhouse conditions (e.g. ERBA, 1994; LARSON & ERBA, 1999; JONES & JENKYNS, 2001; MÉHAY et alii, 2009; TEJADA et alii, 2009; BOTTINI et alii., in press). Independent studies on TEX86, sporomorphs and oxygen isotopes (e.g. MENEGATTI et alii., 1998; DUMITRESCU et alii., 2006; ANDO et alii, 2008; KUHNT et alii., 2011; MILLAN et alii., 2011; KELLER et alii., 2011) provided evidence for climate instability during OAE 1a. Nevertheless, the direct/indirect role of OJP volcanism, weathering rates and pCO2 on climate changes has not been established.
We have performed a high-resolution integrated nannofossil-geochemical investigation of OAE 1a in three sites: Cismon core (Italian Southern Alps), Piobbico core (Umbria-Marche basin, Italy) and DSDP Site 463 Mid-Pacific Mountains. The existing stratigraphic framework for the three sites and available cyclochronology for the Cismon core (MALINVERNO et alii., 2010) allows high-resolution dating of biotic and environmental fluctuations.
The nannofossil Temperature Index correlated with the oxygen-isotope record has revealed systematic and synchronous changes in the three sites. A warming pulse is registered prior to the onset of OAE 1a and corresponds to a prominent volcanic phase documented in the Os-isotope records (TEJADA et alii., 2009; BOTTINI et alii., in press). During OAE 1a, in correspondence of the core of the negative carbon-isotope excursion, temperature shows a maximum. This interval coincides with the most intense volcanic phase, as suggested by biomarkers, calcareous nannofossils and Os-isotope (MÉHAY et alii, 2009; TEJADA et alii, 2009; ERBA et alii., 2010; BOTTINI et alii., in press). This correspondence is suggestive of a (super)greenhouse climate triggered by excess volcanogenic CO2. Our data indicate that the beginning of the prolonged volcanic phase during OAE 1a coincides with warmest temperatures.
The end of global anoxia is paralleled by a cooling episode which slightly postpone the end of the major OJP volcanism.
High resolution analyses allow the identification of rapid cooling and warming during OAE 1a. Warm conditions in the early part of OAE 1a are interrupted by a brief (~35 ky) cooling interlude traced either by oxygen isotopes and calcareous nannofossils. This temperature change follows a ~100 kyrs-long interval characterized by accelerated continental weathering rates (BOTTINI et alii., in press). Arguably, warming at OAE 1a onset promoted methane hydrate dissociation (also suggested by carbon isotopes and biomarkers analyses; MEHAY et alii., 2009), which was perhaps instrumental in triggering continental weathering. Subsequent CO2 draw down, possibly during OJP quiescence, might explain the brief cooling interlude annihilated by warmest temperatures coeval with the onset of OJP paroxysmal phase.
In the second part of OAE 1a two more cooling events (around segments C4 and C6 of the carbon-isotope curve) sandwich an interval of intermediate and fluctuating temperatures. Major and minor cooling episodes correlate with high TOC content, suggesting that burial of organic matter acted as storage of excess CO2, thus temporarily mitigating greenhouse conditions, although under persisting OJP activity.
The data collected combined with an improved chronology show that volcanism of OJP caused general global warming. The excess burial of organic matter acted as an additional and alternative process influencing climate change.
The micropaleontological data presented confirm and provide evidence for even more temperature fluctuations during OAE1a, although under persisting OJP volcanism. This observation may imply that volcanism was not the only factor influencing climate. The ocean/atmosphere system during OAE 1a was extremely dynamic and affected by a series of complex processes. In fact, positive and negative feedbacks alternated over 1.2 My and controlled climate variability
Evidence for high sea-surface temperatures during the early Aptian OAE 1a in the Boreal Realm
No full textThe early Aptian was characterized by the
widespread occurrence of anoxia in the oceans,
known as Oceanic Anoxic Event (OAE) 1a.
Intense degassing from submarine volcanic
plateaus presumably resulted in high
atmospheric CO2 concentrations, culminating
in greenhouse conditions (e.g., Hochuli et al.,
1999; Jenkyns, 2003; Erba et al., 2010). OAE
1a can, therefore, be considered as a past
“natural experiment” important to understand
the evolution of our future climate.
Paleotemperature estimates for OAE 1a are,
however, predominantly based on bulk
oxygen-isotopes, which are susceptible for
diagenetic overprinting, while TEX86
paleotemperature estimates are limited in
number or derived from stratigraphically
poorly constrained sections.
We reconstructed for the first time sea-surface
water (SST) temperatures based on the TEX86
paleothermometer from an OAE 1a section
from the middle northern latitudes (39° N
paleolatitude). We find a SST rise starting
prior to OAE 1a and reaching a maximum
during the event with SSTs around 31–34 °C,
4–9 °C higher than those of older Hauterivian -
lower Aptian sediments from the same
sedimentary basin (Mutterlose et al., 2014).
The end of OAE 1a is marked by relatively
lower SSTs around 30 °C. These observations
are supported by belemnite-based oxygen
isotope data and calcareous nannofossils. Our
integrated data set clearly indicates that ‘super
greenhouse’ conditions prevailed during OAE
1a at northern latitudes. SSTs are similar to
those estimated for coeval low latitudinal sites,
suggesting that an equable warm climate, with
reduced latitudinal gradients, characterized the
early Aptian.
References
Erba, E., Bottini, C., Weissert, J.H. & Keller, C.E.
(2010): Calcareous nannoplankton response to
surface-water acidifi cation around Oceanic
Anoxic Event 1a: Science, v. 329, p. 428–432.
Hochuli, P.A., Menegatti, A.P., Weissert, H., Riva,
A. Erba, E. & Premoli Silva, I. (1999): Episodes
of high productivity and cooling in the early
Aptian Alpine Tethys: Geology, v. 27, p. 657–
660.
Jenkyns, H.C. (2003): Evidence for rapid climate
change in the Mesozoic–Palaeogene greenhouse
world: Philosophical Transactions of the Royal
Society of London, Series A, v. 361, p. 1885–
1916.
Mutterlose, J., Bottini, C., Schouten, S. &
Sinninghe Damsté, J.S. (2014) : High sea-surface
temperatures during the early Aptian Oceanic
Anoxic Event 1a in th
Dataset and R code for Bottini et al. (2024) Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality.
No full textThis folder contains all the datasets and R code needed to reproduce the analysis of manuscript from Bottini et al. (2024) Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality, submitted in Journal of Experimental Biology.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Paleoclimate and paleoecology of the mid Cretaceous traced by calcareous nannofossils
No full textThe Aptian – early Turonian time interval was marked by major environmental changes at regional to global scale. Specifically, it was a time of super-greenhouse conditions and the climate–ocean system experienced phases of stability perturbed by transient, sometimes prolonged, anomalies of the global carbon cycle. Several regional to global episodes occurred over this time interval: the early Aptian Oceanic Anoxic Event (OAE) 1a, the early Albian OAE 1b, the latest Albian OAE 1d, the Mid-Cenomanian Event (MCE I) and the Cenomanian – Turonian OAE 2. Decades of multidisciplinary research focused on OAEs since they constitute ideal case-histories for the understanding of our planet functioning during perturbations of the C cycle. They were, in fact, characterized by
excess CO2, intense volcanism, and altered climate and oceanic chemistry. A useful tool for reconstructing the marine ecosystem dynamics of the past, is calcareous nannoplankton, since it is extremely sensitive to changes in surface waters parameters like temperature and nutrient content and interacts with the C cycle through biological processes and production of calcareous oozes.
Here, we gathered new quantitative nannofossil data for the Tethys Ocean (Umbria Marche Basin, Italy) to derive climatic fluctuations and changes in ocean fertility during the late Albian – early Turonian. Over this time interval, the Tethys Ocean was characterized by phases of rhythmic black shale deposition controlled by orbital forcing. The Pialli Level is the Tethyan sedimentary expression of the latest Albian OAE 1d, characterized by large-scale occurrence of black shales and a 13C positive excursion recognized in several deep-marine settings. The other prominent 13C anomaly coincides with the OAE 2 represented, in Italy, by the Bonarelli Level. Between these two main C-isotopic excursions, a double-spiked minor anomaly identifies the MCE I, lithologically represented
by a shift to black shales and black chert bands alternating with whitish limestones. The new dataset has been integrated with the nannofossil data previously collected for the Aptian – early Albian
time interval to provide a compilation of temperature and surface water variations on the long-term throughout the Aptian – early Turonian interval. The nannofossil Temperature and Nutrient Indices outline warm conditions for the OAE 1a which was followed by a cooling trend culminating soon after the N. truittii acme interval. Progressively increasing temperature characterized instead the latest phases of the Aptian and warmer conditions were reached in the Albian – Cenomanian, although interrupted by relatively cooler phases, as for example in correspondence of the MCE. Highest nannofossil-derived paleotemperatures were reached across OAE 2. Surface water fertility resulted instead to be relatively high during most of the early-middle Aptian, exception made for the N. truittii acme interval when a significant decrease occurred. The latest Aptian – early Albian interval was marked by intermediate trophism in surface waters, with intervals of higher fertility during black shales deposition. During the interval comprised between the OAE 1b and the OAE 1d, fertility was relatively high while it decreased in the Cenomanian. A distinct fertility pulse was detected prior to OAE 2
Datasets and R code for Bottini et al. (2022) Effects of methylmercury and food stress on migratory restlessness in song sparrows, Melospiza melodia
No full textThis folder contains all the datasets and R code needed to reproduce the analysis of manuscript from Bottini et al. 2022 “Effects of methylmercury and food stress on migratory activity in song sparrows, Melospiza melodia”, submitted in Hormones and Behavior journal.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Dataset and R code for Bottini et al. (2024) Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality.
No full textThis folder contains all the datasets and R code needed to reproduce the analysis of manuscript from Bottini et al. (2024) Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality, submitted in Journal of Experimental Biology.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Calcareous nannofossil paleofluxes: proxies for pCO2 fluctuations through the Aptian
No full textThe Cretaceous has been punctuated by episodes of widespread organic matter burial in oxygen-depleted oceans known as Oceanic Anoxic Events (OAEs) (Schlanger & Jenkyns, 1976). In particular, the Aptian (~121 to ~113 Ma) has been characterized by a super-greenhouse climate and profound environmental perturbations, including the early Aptian OAE 1a, thought to be related to the emplacement of the Ontong Java Plateau.
The aim of this work is to study variations in biogenic carbonate production of calcareous nannofossils through the Aptian in order to detect if and how it has been affected by high pCO2. Calcareous nannoplankton is an excellent proxy for reconstructing present and paste surface water conditions, being extremely sensitive to changes in physical and chemical conditions of the oceans (pH). Studies on living form have attested a direct response of these organisms to changes in CO2 concentrations (e.g. Krug et al. 2010). Production of dwarf/malformed coccoliths has also been documented in the geological record through OAE 1a (Erba et al. 2010).
Here we present quantitative analyses of nannofossil micrite in thin sections, reconstructing nannofossil absolute abundances and calcite paleofluxes in three drill sites: the Cismon core (Northern Italy), Piobbico core (Central Italy) and DSDP Site 463 in the mid-Pacific Mountains. In each of the three sites, nannofossil absolute abundances and paleofluxes show a progressive drastic reduction starting in the latest Barremian. This decrease is due to a worldwide decrease in the rock-forming nannoconids, “nannoconids decline”, that culminates with the “nannoconids crisis” just prior to OAE 1a (Erba, 1994; Erba & Tremolada, 2004). At the end of OAE 1a, nannofossil biocalcification increases again, but it never reaches pre-anoxia values. In the late Aptian, nannofossil paleofluxes reach high values during the Nannoconus truittii acme, followed by a final decrease through the Aptian/Albian boundary interval.
Calcite paleofluxes fluctuations reveal a drastic reduction in nannoplankton calcification interpreted as the adaptive response of these organisms to perturbed surface-water conditions that favoured small and less calcified forms and caused false extinction among heavily calcified nannoconids (Lazarus effect). We conclude that, despite metabolic processes, CO2 concentrations influence the ocean chemistry and the carbonate system. In particular, the correlation between reduced biocalcification rates and intervals of intense volcanism, suggest that mid-Cretaceous nannoplankton biocalcification and nannofossil paleofluxes were strongly controlled by excess volcanogenic CO2.
REFERENCES
Erba, E. (1994). Nannofossils and superplumes: The early Aptian “nannoconid crisis”. Paleoceanography, 9: 483-501.
Erba, E. & Tremolada, F. (2004). Nannofossil carbonate fluxes during the Early Cretaceous: phytoplankton response to nutrification episodes, atmospheric CO2 and anoxia. Paleoceanography, 19: 1008.
Erba, E., Bottini, C., Weissert, H.J., Keller, C.E. (2010). Calcareous Nannoplankton response to surface-water acidification around Oceanic Anoxic Event 1a. Science 329: 428–432.
Krug, S.A., Schulz, K.G., Riebesell, U. (2010). Effects of CO2-induced changes in seawater carbonate chemistry speciation on Coccolithus braarudii: a conceptual model of coccolithophorid sensitivities. Biogeosciences Discuss., 7: 8763–8778.
Schlanger, S.O. & Jenkyns, H.C. (1976). Cretaceous oceanic anoxic events: causes and consequences. Geol. Mijnb., 55: 179–184
Mid-Cretaceous paleoenvironmental changes in the western Tethys
No full textWe present a continuous record of surface water temperature and fertility variations through the latest Barremian-Cenomanian interval (ca. 27 Myr) based on calcareous nannofossil abundances from the western Tethys. The nannofossil temperature index, calibrated with TEX86 sea surface temperatures, suggests that warmest (34-36 °C) conditions were reached during oceanic anoxic event (OAE) 1a onset, the Aptian-Albian boundary interval hyperthermals (113, Kilian level and Urbino level OAE 1b) and during a ca. 4 Myr long phase in the middle Albian. Coolest temperatures (29 °C) correspond instead to the late Aptian. Generally warm conditions characterized the Albian followed by a progressive cooling trend that started in the latest Albian (at the Marne a Fucoidi-Scaglia Bianca Formation transition). Temperate conditions occurred in the Cenomanian with frequent short-term variations highlighted by abundance peaks of the cold-water nannofossil species E. floralis and R. parvidentatum. Mid-Cretaceous surface water fertility was rather fluctuating and mostly independent from climatic conditions as well as from black shales intervals. Intense warming and fertility spikes were systematically associated only with black shales of OAE 1a and of the Aptian-Albian boundary hyperthermals. The Albian-Cenomanian rhythmic black shales are, in fact, associated with varying long-term climatic and fertility conditions. The similarity of western Tethys climatic and fertility fluctuations during OAE 1a, OAE 1b, the middle Albian and OAE 1d with nannofossil-based records from other basins indicated that these paleoenvironmental conditions were affecting the oceans at supra-regional to global scale
Mid-Cretaceous climatic fluctuations traced by calcareous nannofossils
No full textSeveral regional to global episodes, known as Oceanic Anoxic Events (OAE)s occurred over the Aptian – early Turonian time interval and were characterized by excess CO2, intense volcanism, perturbed climate and altered oceanic chemistry. In order to either understand the dynamics leading to these “extreme” conditions and the ocean-atmosphere system recovery after the OAE, it is important to focus on a longer-term record thus to include the sequence of intervals of perturbation and the phases of stable conditions. For this purpose, calcareous nannoplankton is a useful tool, since it is extremely sensitive to changes in surface waters parameters like temperature and nutrient content and interacts with the C cycle through biological processes and production of calcareous oozes. We gathered new quantitative nannofossil data for the Tethys Ocean (Umbria Marche Basin, Italy) to derive climatic fluctuations and changes in ocean fertility during the late Albian – early Turonian. The new dataset was integrated with the nannofossil data collected for the Aptian – early Albian time interval to provide a compilation of temperature and surface water nutrient variations on the long-term through the Aptian – early Turonian interval in the western Tethys. The nannofossil Temperature Index (TI) outlines warm conditions for OAE 1a, followed by a cooling trend culminating soon after the N. truittii acme interval. Progressively increasing temperature (T) characterized instead the latest phases of the Aptian and warmer conditions were reached in the Albian – Cenomanian, although interrupted by relatively cooler phases, as for example in correspondence of the MCE. The highest paleo-T were reached across OAE 2. Surface water fertility (F) resulted instead to be relatively high during most of the early-middle Aptian, exception made for the N. truittii acme interval when a significant decrease occurred. The latest Aptian – early Albian interval was marked by intermediate trophism in surface waters, with intervals of higher F during black shales deposition. During the interval comprised between the OAE 1b and the OAE 1d, F was relatively high while it decreased in the Cenomanian. A distinct F pulse was detected prior to OAE 2. We correlated the TI with available paleo-T proxies: a good correlation exists with the ð18O records through the Aptian - upper Albian but it is not possible to provide a comparison for the lower-middle Albian since there are no ð18O data available. During the Cenomanian, the trends of the two paleo-T records are instead the opposite, with the TI shifted towards cooler T and displaying oscillations not evidenced by the ð18O. Further paleo-T reconstructions are available across the upper Aptian - lower Albian from TEX86 data from the proto-North Atlantic Ocean and show very good correspondence with the TI. We therefore calibrated the TI (which does not provide absolute T values) on the basis of TEX86 paleo-T and estimated the extent of T-variations
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