scholarly journals Photosymbiosis in Late Triassic scleractinian corals from the Italian Dolomites

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11062
Author(s):  
Katarzyna Frankowiak ◽  
Ewa Roniewicz ◽  
Jarosław Stolarski
Keyword(s):  
Coefficient Of Variation ◽  
Isotope Composition ◽  
Scleractinian Corals ◽  
Regular Growth ◽  
Late Triassic ◽  
Western Tethys ◽  
Growth Increments ◽  
Algal Symbiosis ◽  
Growth Bands ◽  
Zooxanthellate Corals

During the Carnian, oligotrophic shallow-water regions of the western Tethys were occupied by small, coral-rich patch reefs. Scleractinian corals, which already contributed to the formation of the reef structure, owed their position most probably to the symbiosis with dinoflagellate algae (zooxanthellae). Using microstructural (regularity of growth increments) and geochemical (oxygen and carbon stable isotopes) criteria of zooxanthellae symbiosis, we investigated whether this partnership was widespread among Carnian scleractinians from the Italian Dolomites (locality Alpe di Specie). Although corals from this locality are renowned from excellent mineralogical preservation (aragonite), their skeletons were rigorously tested against traces of diagenesis Irrespective of their growth forms, well preserved skeletons of corals from the Dolomites, most frequently revealed regular growth bands (low values of coefficient of variation) typical of modern zooxanthellate corals. Paradoxically, some Carnian taxa (Thamnasteriomorpha frechi and Thamnasteriomorphasp.)with highly integrated thamnasterioid colonies which today are formed exclusively by zooxanthellate corals, showed irregular fine-scale growth bands (coefficient of variation of 40% and 41% respectively) that could suggest their asymbiotic status. However, similar irregular skeletal banding is known also in some modern agariciids (Leptoseris fragilis) which are symbiotic with zooxanthellae. This may point to a similar ecological adaptation of Triassic taxa with thamnasterioid colonies. Contrary to occasionally ambiguous interpretation of growth banding, all examined Carnian corals exhibited lack of distinct correlation between carbon (δ13C range between 0.81‰ and 5.81‰) and oxygen (δ18O values range between −4.21‰ and −1.06‰) isotope composition of the skeleton which is consistent with similar pattern in modern zooxanthellates. It is therefore highly likely, that Carnian scleractinian corals exhibited analogous ecological adaptations as modern symbiotic corals and that coral-algal symbiosis that spread across various clades of Scleractinia preceded the reef bloom at the end of the Triassic.

Evolution of the coral-zooxanthellae symbiosis during the Triassic: a geochemical approach

Paleobiology ◽  
1995 ◽  
Vol 21 (2) ◽  
pp. 179-199 ◽  
Author(s):  
George D. Stanley ◽  
Peter K. Swart
Keyword(s):  
Shallow Water ◽  
Isotope Analysis ◽  
Indirect Evidence ◽  
Scleractinian Corals ◽  
Late Triassic ◽  
Control Group ◽  
Algal Symbiosis ◽  
Isotope Studies ◽  
Carbonate Complexes ◽  
Geochemical Approach

Scleractinian corals first appeared during Triassic time in tropical shallow water environments. Controversy surrounds the paleoecology of scleractinian corals of the Late Triassic. Were they like their living counterparts, capable of supporting reefs, or had they not yet coevolved the important association with zooxanthellae that facilitated reef growth and construction? Indirect evidence suggests that some Upper Triassic corals from the Tethys played important constructional roles as reef builders within tropical carbonate complexes of the Tethys. To evaluate this idea, we have employed a geochemical approach based on isotope fractionation to ascertain if Late Triassic corals once possessed zooxanthellae.We have determined evidence for the ancient presence of algal symbiosis in 13 species of Triassic scleratinians from reef complexes in Turkey and northern Italy. In contrast, two higher latitude Jurassic species used as a control group for isotope analysis, lacked isotopic indications of symbiosis. These findings, together with stratigraphic and paleoecologic criteria, support the contention that Late Triassic scleractinian corals inhabiting shallow-water carbonate complexes of the Tethys were predominantly zooxanthellate, like their living counterparts from present day reefs.We view the zooxanthellate condition in calcifying reef organisms as a necessary prerequisite for constructional reef development. Our results emphasize the power of stable isotope studies in helping to answer paleobiological questions.

scholarly journals The calcareous nannofossil <i>Prinsiosphaera</i> achieved rock-forming abundances in the latest Triassic of western Tethys: consequences for the δ<sup>13</sup>C of bulk carbonate

2013 ◽  
Vol 10 (5) ◽  
pp. 7989-8025 ◽  
Author(s):  
N. Preto ◽  
C. Agnini ◽  
M. Rigo ◽  
M. Sprovieri ◽  
H. Westphal
Keyword(s):  
Global Ocean ◽  
Late Triassic ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Western Tethys ◽  
Carbonate Sedimentation ◽  
History Of ◽  
Calcareous Plankton ◽  
Inorganic Carbon Cycle

Abstract. The onset of pelagic biomineralization marked a milestone in the history of the long term inorganic carbon cycle: as soon as calcareous nannofossils became major limestone producers, the pH and supersaturation state of the global ocean were stabilized (the so-called Mid Mesozoic Revolution). But although it is known that calcareous nannofossils were abundant already by the end of the Triassic, no estimates exist on their contribution to hemipelagic carbonate sedimentation. With this work, we estimate the volume proportion of Prinsiosphaera, the dominant Late Triassic calcareous nannofossil, in hemipelagic and pelagic carbonates of western Tethys. The investigated Upper Triassic lime mudstones are composed essentially of microspar and tests of calcareous nannofossils, plus minor bioclasts. Prinsiosphaera became a significant component of lime mudstones since the late Norian, and was contributing up to ca. 60% of the carbonate by the late Rhaetian in periplatform environments with hemipelagic sedimentation. The increasing proportion of Prinsiosphaera in upper Rhaetian hemipelagic lime mudstones is paralleled by a increase of the δ13C of bulk carbonate. We interpreted this isotopic trend as related to the diagenesis of microspar, which incorporated respired organic carbon with a low δ13C when it formed during shallow burial. As the proportion of nannofossil tests increased, the contribution of microspar with low δ13C diminished, determining the isotopic trend. We suggest that a similar diagenetic effect may be observed in many Mesozoic limestones with a significant, but not yet dominant, proportion of calcareous plankton.

scholarly journals The calcareous nannofossil <i>Prinsiosphaera</i> achieved rock-forming abundances in the latest Triassic of western Tethys: consequences for the <i>δ</i><sup>13</sup>C of bulk carbonate

2013 ◽  
Vol 10 (9) ◽  
pp. 6053-6068 ◽  
Author(s):  
N. Preto ◽  
C. Agnini ◽  
M. Rigo ◽  
M. Sprovieri ◽  
H. Westphal
Keyword(s):  
Global Ocean ◽  
Late Triassic ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Western Tethys ◽  
Carbonate Sedimentation ◽  
History Of ◽  
Calcareous Plankton ◽  
Inorganic Carbon Cycle

Abstract. The onset of pelagic biomineralization was a milestone in the history of the long-term inorganic carbon cycle: as soon as calcareous nannofossils became major limestone producers, the pH and supersaturation state of the global ocean were stabilized (the so-called mid-Mesozoic revolution). But although it is known that calcareous nannofossils were abundant already by the end of the Triassic, no estimates exist on their contribution to hemipelagic carbonate sedimentation. With this work, we estimate the volume proportion of Prinsiosphaera, the dominant late Triassic calcareous nannofossil, in hemipelagic and pelagic carbonates of western Tethys. The investigated Upper Triassic lime mudstones are composed essentially of microspar and tests of calcareous nannofossils, plus minor bioclasts. Prinsiosphaera had become a significant component of lime mudstones since the late Norian, and was contributing up to ca. 60% of the carbonate by the late Rhaetian in periplatform environments with hemipelagic sedimentation. The increasing proportion of Prinsiosphaera in upper Rhaetian hemipelagic lime mudstones is paralleled by an increase of the δ13C of bulk carbonate. We interpreted this isotopic trend as related to the diagenesis of microspar, which incorporated respired organic carbon with a low δ13C when it formed during shallow burial. As the proportion of nannofossil tests increased, the contribution of microspar with low δ13C diminished, determining the isotopic trend. We suggest that a similar diagenetic effect may be observed in many Mesozoic limestones with a significant, but not yet dominant, proportion of calcareous plankton.

Dorsal-fin spine growth of Heterodontus portusjacksoni: a general model that applies to dorsal-fin spines of chondrichthyans?

2008 ◽  
Vol 65 (1) ◽  
pp. 74-82 ◽  
Author(s):  
Javier Tovar-Ávila ◽  
Christopher Izzo ◽  
Terence I Walker ◽  
J Matias Braccini ◽  
Robert W Day
Keyword(s):  
Growth Zone ◽  
Layer Growth ◽  
Spine Length ◽  
External Edge ◽  
Dorsal Fin ◽  
Growth Increments ◽  
Second Growth ◽  
Growth Bands ◽  
Growth Zones ◽  
Prospective Model

A prospective model of dorsal-fin spine growth in chondrichthyans is devised by studying the growth of spines from captive and wild Heterodontus portusjacksoni injected with several fluorochromes. Evidence was found for only two dentine layers in the spine trunk of H. portusjacksoni, contrasting with conjectures about the presence of a third middle dentine layer in some squalids. The spines have three simultaneous growth zones. The first growth zone is along the internal edge of the inner trunk dentine layer, where growth bands are deposited towards the centre (centripetally), increasing spine length and width by pressure against the cartilage rod. The second growth zone is along the external edge of the outer trunk dentine layer at the spine base, where growth bands are deposited in an opposite direction to the centre (centrifugally), increasing spine width. A third growth zone at the base of the cap enables downward expansion over the trunk. The model of concentric cones describes correctly the inner dentine layer growth pattern, whereas the outer dentine layer growth increments appear to be related to the external bands on the surface of the trunk. Growth increments from the three growth zones of the spine are all potentially useful for age estimation.

Paleolatitudes of Late Triassic radiolarian cherts from Argolis, Greece: Insights on the paleogeography of the western Tethys

2015 ◽  
Vol 417 ◽  
pp. 476-490 ◽  
Author(s):  
Giovanni Muttoni ◽  
Paola Tartarotti ◽  
Marco Chiari ◽  
Chiara Marieni ◽  
Daniel Rodelli ◽  
...  
Keyword(s):  
Late Triassic ◽  
Western Tethys

Diagenesis of growth bands in fossil scleractinian corals: identification and modes of preservation

Facies ◽  
2005 ◽  
Vol 51 (1-4) ◽  
pp. 146-159 ◽  
Author(s):  
Markus Reuter ◽  
Thomas C. Brachert ◽  
Karsten F. Kroeger
Keyword(s):  
Scleractinian Corals ◽  
Growth Bands
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