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Living coral cover is rapidly decreasing due to global climate change and local human impacts. Response to the ongoing transformation of coral reefs requires a deep understanding of the mechanisms that regulate community assembly and sustain biodiversity in these systems. The goal of this study is to test the persistence of Devonian reef communities across 70 sea-level fluctuation cycles. Abundance data were collected for in situ coral and calcareous sponge taxa found along 164 transects across two field localities within the Canning Basin, Western Australia. The Bray-Curtis dissimilarity index was used to quantify the dissimilarity in taxonomic composition among transects. Despite the notable persistence of reef communities over numerous cycles (ranging from 22 to 29 cycles) spanning hundreds of thousands of years, significant taxonomic shifts unfolded over millions of years, primarily driven by the diversity and composition of coral assemblages. This indicates that while reef communities exhibit persistence over intermediate time scales, they undergo changes in taxonomic composition over extended periods. The observed shifts in taxonomic composition likely reflect the profound changes in Earth-surface systems that occurred during the Devonian (i.e., fluctuations in global sea-surface temperatures and sea-level). Therefore, sustained abiotic processes can act to disrupt community structure over extended time scales as the threshold for community persistence is exceeded. This study helps establish baseline community composition dynamics in systems devoid of human influence and thus deepens our understanding of naturally occurring phase shifts. Understanding the factors that contribute to the persistence of community assembly across multiple scales is crucial for conserving coral reef ecosystems in the face of ongoing environmental changes. • Understanding community dynamics is shaped by the scale at which it is studied. • Reefs were studied across 70 sea-level fluctuation cycles. • Communities were persistent for up to 29 cycles before experiencing a phase shift. • Phase shifts could reflect global environmental changes during the Devonian. [ABSTRACT FROM AUTHOR]

Back-reef and lagoonal communities played an important role in the construction of global reef ecosystems and shallow water carbonate factories during the Devonian Period, but their reef-building significance is not fully understood. This study describes a previously undocumented Givetian stromatoporoid biostromal sequence, 12 m thick and comprising 7 biostromes, in the Tangjiawan Formation of Yaozhai, Guangdong Province, Southeast China. Large bulbous or columnar stromatoporoid Actinostroma and delicate dendroid stromatoporoid Amphipora are abundant, with a comparatively smaller presence of tabulate corals, rugose corals, brachiopods, gastropods, calcimicrobes, and tubeworms. The dominant Actinostroma - Amphipora assemblage, together with leperditicopid ostracods, parathuramminid foraminifers, and calcispheres, indicates a shallow, low-energy back-reef to lagoonal setting. Taphonomic analysis shows a common occurrence of overturned skeletons, and the deposit is interpreted as a parabiostrome constructed in a low-energy environment and affected by episodic high-energy events. Statistical data of similar global assemblages from the Lochkovian to the Famennian based on 153 localities show a relatively rare occurrence of back-reef and lagoonal communities from the Lochkovian to the Eifelian, peaking during the Givetian and Frasnian together with metazoan reefs then declining sharply in the Famennian after the Kellwasser Event. Although autobiostromes have rarely been documented, the densely packed reworked bulbous/domical and dendroid stromatoporoids justify the existence of low-diversity but highly abundant metazoan ecosystems in back-reef to lagoonal settings. This study thus highlights our understanding of the back-reef and lagoonal facies and the important role they played in the expansion of large-scale carbonate factories and reef ecosystems during the Middle to Late Devonian. • A Givetian biostromal sequence from Southeast China is documented for the first time. • The fauna is characterised by stromatoporoid Actinostroma – Amphipora assemblage. • Taphonomic analysis implies a parabiostromal nature with high-energy reworking. • Statistics of global data reveal the co-development of Devonian back reef and reefs. • Back-reef and lagoonal facies are essential in large-scale reef proliferation. [ABSTRACT FROM AUTHOR]

Stromatoporoids in Silurian shallow marine limestones from Gotland are commonly symbiotic with syringoporid tabulates, rugose corals, shelly tubes and bioclaustrations (symbionts lacking shell walls). Syringoporid and rugosan symbionts occur almost exclusively in reefs, contrasting deeper facies where stromatoporoids have shelly tubes and bioclaustrations. In a Ludlow biostromal sequence at Kuppen, eastern Gotland, symbionts occur in stromatoporoids in both a marl unit and an overlying biostrome containing the same stromatoporoid taxa and symbionts, but in the marl, stromatoporoid growth forms appear more delicate. A minimum of 10% of a suite of 541 stromatoporoids contain symbionts: 1) two of the 16 stromatoporoid taxa (all Petridiostroma convictum and many "Stromatopora" venukovi specimens) contain abundant intergrown syringoporids; in others syringoporids are rare or absent. Rugosans occur sporadically in several taxa, commonly P. convictum. Some "S" venukovi specimens have syringoporids, rugosans and spiral shelly tubes close together; 2) symbionts mostly began growth after stromatoporoids established, rarely occurring at the base; 3) most stromatoporoid hosts and symbionts evidently had matched growth rates; 4) in some samples, symbionts terminated during stromatoporoid growth, reappearing later within the same host skeleton; and 5) at stromatoporoid growth interruption events, some coral symbionts survived and others did not. These results are interpreted to indicate that: a) symbionts discovered stromatoporoids by chance; b) in shallow locations, reasons for specific taxonomic relationships include suitable substrates for symbionts and a biological relationship; c) stromatoporoid hosts and symbionts responded differently to events; controls on growth were complex; d) there is little evidence that symbionts enhanced reef growth; e) in deeper facies, symbionts were largely overgrown by host stromatoporoids, thus appear unwelcome. In a-d, distinction between commensalism and mutualism remains unproven, but parasitism seems unlikely. The pattern found in this study may apply through stromatoporoid geological history and needs to be tested on other assemblages. • First comprehensive description of symbionts in Silurian stromatoporoid biostromes, Gotland. • Two taxa have abundant symbionts, otherwise symbionts are uncommon. • Shallow-marine settings have syringoporid & rugosan symbionts, rare in deeper facies. • Symbionts relate to stromatoporoid palaeobiology, not major reef building. [ABSTRACT FROM AUTHOR]

One of the keys to the success of modern and ancient reef ecosystems is the phenomenon of photosymbiosis. Photosymbiotic corals can thrive down to the limits of the photic zone, and the coral communities living in the lower part of the photic zone are known as mesophotic coral reef ecosystems (MCE). Recent studies have shown that MCEs were already present in the middle Palaeozoic. The reefs of that time reached the peak of their distribution during the Givetian, when they were present even as far as 50°S. One of the southernmost Givetian reefs is the Aferdou el Mrakib reef, exposed in the eastern Anti-Atlas (Morocco). At the base of this reef, numerous small carbonate bioherms are exposed. These structures formed low-relief banks that developed probably at moderate water depths of several tens of meters. In the present contribution, we analyse the paleoecology of these peculiar communities. The assemblage is dominated by platy and encrusting coenitid (Roseoporella) and alveolitid (Alveolites) tabulate corals, as well as abundant platy stromatoporoids and solitary cystyphillid rugose corals. The platy morphology of corals is widely considered as an adaptation related to photosymbiosis, and is especially common in MCEs. In combination with palaeobathymetric and sedimentological data, this characteristic suggests that the studied banks developed at the bottom of the euphotic zone. The MCEs of the Aferdou el Mrakib reef share major taxonomic and ecological similarities with the previously described MCEs from the southern shelf of Laurussia and a reef community from southern China, emphasizing a high degree of cosmopolitanism of the Middle Devonian mesophotic ecosystems. Communities studied here are also the most poleward MCEs described to date. • Mesophotic coral ecosystem (MCE) developed at the base of a Givetian reef in Gondwana. • An abundance of platy tabulate corals emphasizes the low-light environment. • Studied communities represent the most poleward known MCE. • Middle Devonian MCEs were characterized by a high degree of cosmopolitanism. [ABSTRACT FROM AUTHOR]

The monsoon system modulates surface production in the South China Sea (SCS). The winter monsoon has long been recognized as the primary factor regulating surface production in the northern SCS; however, the role of monsoon remains in debate in the southern SCS. Here, we present a long record of short-chain n -fatty acids (n -FAs) in reefal carbonates from one deep well (NK1) on an isolated coral atoll (Meiji) in order to provide new insights into the change of surface production in the southern SCS since the Late Miocene (ca. 10.5 Ma). Short-chain n -FAs indicative of total marine organic matter input are rather feasible to reflect the total production associated with mixotrophic reef-building corals that feed on various marine biotas (i.e., phytoplankton, zooplankton and bacteria). By ruling out the significant influence of diagenetic and degradation processes, short-chain n -FAs can be further applied to reconstruct paleo-production in Well NK1 coral reefs. The temporal distribution of short-chain n -FAs changes similarly with many other independent paleo-production records (i.e., Ln(Ba/Ti) and opal) in Well NK1 and adjacent ODP Site 1143, demonstrating the close coupling between coral reef production and surface water production. This occurs through the common factor of nutrients in modulating production of symbiotic autotrophic coralgae and asymbiotic phytoplankton and/or the large heterotrophic dependence of corals on phytoplankton-governed food webs in surface waters. Short-chain n -FAs inferred surface production displays a progressively decreased trend from the Late Miocene to Pliocene (ca. 10.5–2.6 Ma) followed by a substantial increase since the Pleistocene on million-year timescales, which follows the variation of terrigenous supply to the coral atoll and responds almost inversely to the sea-level change. Accordingly, we propose that long-term paleo-production in the southern SCS was associated with terrestrial nutrient input which was controlled by relative sea-level change since the Late Miocene. This study highlights the feasibility of short-chain n -FAs as appropriate production recorders in shallow-water coral reefs which are widespread in tropical-subtropical oceans, providing valuable perspectives on long-term paleo-production evolution in surface waters. • A long coral reef well (NK1) in the southern SCS was studied. • OM-poor coral reef carbonates were decalcified and extracted for biomarkers. • Short-chain n -FAs reflect paleo-production in coral reefs since the Late Miocene. • Long-term production was governed by terrestrial nutrient related to sea level. [ABSTRACT FROM AUTHOR]

The Eocene Peñicas (Almería) and Harania (Málaga) stratigraphic sections from the Malaguide Complex (Betic Cordillera, South Spain) belonging to the Mesomediterranean Microplate from the westernmost Tethys (about-35°N and 0° to 5°E according to the Eocene coordinates) have been studied. The Eocene sections cover the Cuisian to middle Lutetian deposits, which show several lithofacies representing shallow marine platform realms. Based on the fossiliferous assemblage, texture and fabrics, eight microfacies related to inner to outer ramp settings were defined. In the inner ramp of the Harania section abundant colonial corals have been recognized. The Eocene deposits are arranged into a transgressive succession composed by three minor transgressive-regressive sedimentary cycles. The Eocene fossiliferous assemblage shows a mixture of photozoan (Larger Bentic Foraminifera –LBF–, green and red calcareous algae and corals) and heterotrophic (mollusks, echinoids, bryozoans, small benthic and planktic foraminifers) elements, suggesting euphotic to mesophotic conditions in oligo-mesotrophic marine warm-waters at low-middle latitudes. This assemblage indicates a transition from photozoan to heterozoan carbonates and in particular a shift towards outer marine ramp settings. During the Early Eocene, the widespread distribution of LBF leads in the Tethyan domains to disappearance or extreme reduction of coral constructions. Nevertheless, abundant corals associated to inner ramp realms have been observed in the Harania stratigraphic section indicating that corals could continue to develop in the westernmost Tethys at the transition to the Atlantic Ocean, in contrast with respect to other Tethyan sectors. Therefore, the Ypresian-Lutetian time-span is a transitional period for the global temperature during which corals locally survived only where optimal ecologic conditions occurred, preferably in marginal contexts, as it seems to have happened in the studied area. • Westernmost Tethys (about-30° N and 0°-5°W according to the Eocene coordinates) • Cuisian to Middle Lutetian deposits • Shallow marine platform realms • Photozoan elements (LBF, green and red calcareous algae and corals) • Abundant corals associated to inner ramp realms [ABSTRACT FROM AUTHOR]

Coral carpets are biostromes that form laterally continuous but low-relief (typically less than 1-metre-high) coral communities with a lack of clear internal zonation. There are few locations that allow analysis of such systems on a regional (tens of kilometre) scale in the rock record. This study describes extensive, well-exposed, coral-rich bodies (coral carpets), deposited on the Moroccan northwest Atlantic shallow-marine margin during the Cretaceous (early Hauterivian). The coral-rich sequence reaches 50 m in thickness, with individual carpets between 10 and 100 cm thick, extending over an area of more than 150 km2. Logging and regional correlation, integrated with thin-section analysis, has allowed the evaluation of facies distribution, geometries and temporal evolution. The results provide information on allogenic and/or autogenic driving processes for coral development, and allows the generation of conceptual models for their growth. The Tamanar Fm. corals reflects a shallowing up sequence and the recovery of carbonate productivity following stressed environmental conditions in the late Valanginian. Temporally, coral morphological response relates to high-frequency relative sea level changes that affected water energy and turbidity; thick-branching and massive forms grew in shallow high energy environments whilst platy/flat forms grew in poorly lit and turbid environments. However, local-scale (over hundreds of metres) lateral changes in morphology and facies can be explained by autogenic factors independent of sea level change; varying sedimentation, hydrodynamism and turbidity across the extensive open marine platform. The termination of coral deposition is marked by a hardground surface, indicating slow rates of sedimentation and a transgression, which is followed by an influx of clastic sediments onto the platform, resulting in the deterioration of carbonate platform health, as conditions became intolerable for coral growth. These coral-rich outcrops contribute to the relatively sparse documentation of Hauterivian corals globally and suggest niche palaeoecological and palaeoclimatic relationships that allowed corals to develop despite stressed platform conditions. The low diversity, low-relief coral carpets may provide a proxy for the recovery and demise of corals in response to environmental stress on modern carbonate platforms and future climate change projections. • Kilometre-scale coral-rich outcrops onshore the Moroccan Atlantic Margin. • Non-framework coral carpets show no internal zonation. • Coral morphology and abundance controlled chiefly by water energy and turbidity. • Establishment and demise of corals linked to sea level and climatic change. • Low diversity corals possible proxy for recovery/loss in response to environmental stress. [ABSTRACT FROM AUTHOR]

Tabulates, an extinct Palaeozoic group of corals, developed diverse colony morphologies during the Silurian to Devonian peak of reef development. Coralliths, or circumrotatory colonies, are passively motile coral colonies constantly overturned by wave action or currents. Such overturning allows tissue growth on all sides of the colony. They are among the most rarely reported growth forms. Recent corallith-forming scleractinian corals mostly inhabit the shallowest reef environments, but coralliths can also develop at greater depths in areas of low topographic relief, unconsolidated substratum, low coral cover and high water movement. Here, we report on Devonian (Givetian Favosites goldfussi and Frasnian Alveolites ? tenuissimus) coralla from the Holy Cross Mountains, Poland. Our analysis suggests these colonies are coralliths, although less mature than usually reported. These corals, unlike previously described growth forms of this kind, lived in relatively deep environments: probably the upper mesophotic (Givetian, Miłoszów), or deep reef fore-slope (Frasnian, Jaźwica and Kowala). Microfacies analysis of the Jaźwica site suggests unconsolidated substratum and high hydrodynamic energy. We conclude that these corals lived in deeper environments where bottom currents caused their autorotation. A good modern analogue for such a corallith-forming environment is the Wistari Channel (Southern Great Barrier Reef), where bottom tidal currents at nearly 30 m of depth are strong enough to overturn colonies of Stylocoeniella cf. guentheri reaching 15 cm in diameter. Our discovery shows that the spectrum of coral growth forms during the Devonian peak of reef development was broader than previously assumed, and that tabulate corals displayed numerous adaptive strategies to various environments. • Coralliths are unattached coral colonies passively rotated by water movement. • Recent and Palaeozoic coralliths were described from shallow-water environments. • Givetian and Frasnian tabulate coralliths are described here from deeper habitats. • The coralliths were moved by strong bottom currents, as shown by microfacies analysis. • We propose modern analogue, a corallith from ~28 m-deep channel near Heron Island. [ABSTRACT FROM AUTHOR]

Cyprus is one of the few areas of the Mediterranean where lower and upper Miocene coral-reefs occur in close proximity and is thus well suited to investigate how environmental and geological changes affected the reefs and their associated shallow-marine facies. The prevailing environmental conditions of the lower Miocene Terra Member and of the upper Miocene Koronia Member are reconstructed here, using detailed microfacies comparisons of the skeletal, foraminiferal and calcareous algal assemblages. The lower Miocene reefs are characterised by a higher biodiversity of coralline algae, large benthic foraminifera and corals, and mainly developed in slightly deeper water (20–40 m, lower euphotic zone) than the upper Miocene reefs (< 15 m; upper euphotic zone). The reduced late Miocene biodiversity was probably caused by changes in the Mediterranean marine environment (e.g. increased seasonality), possibly in response to global cooling, increased latitudinal gradients and progressive isolation of the basin. The observed shift of the reef environment towards the upper euphotic zone could be explained as a response to late Miocene physical oceanographic setting, notably temperature changes, which could have made the upper euphotic zone more favourable for certain hermatypic corals. Similarities between the Miocene carbonate facies of Cyprus and the Eratosthenes Seamount directly to the south, and elsewhere in the Mediterranean region (e.g., Corsica; Italy; Spain), suggest that the environmental changes inferred for the Miocene of Cyprus operated on a Mediterranean or even wider scale. • The skeletal assemblages of Miocene neritic carbonates of Cyprus are analysed. • Lower Miocene coral-reefs are highly biodiverse and developed between 20 and 40 m of water depth. • Upper Miocene coral-reefs display a low biodiversity and developed <15 m of water-depth. • Biodiversity decreased in response to less favorable conditions in the late Miocene. [ABSTRACT FROM AUTHOR]

The Western Australian margin is a unique coral reef province, with modern coral reef development occurring at latitudes as far south as 29°S. The genesis of this coral reef province may go back to the Oligo-Miocene, since geological features ~30 million-year-old and younger interpreted as coral reefs are known from offshore seismic surveys. The nature of these seismic reefs is, however, uncertain, as they are only sparsely sampled, and as time-equivalent outcrops are only present in a few remote and understudied locations. This study investigates middle Miocene shallow-water limestones with tropical fauna formed along the North West Shelf (NWS) between ~13 Ma and ~15 Ma, when the southward extension of the seismic reefs was at its maximum. The outcrops and cores investigated are dominantly composed of peloidal packstones and micritic floatstones containing larger benthic foraminifera, Halimeda sp. and scleractinian corals, including reef-building genera, that accumulated in a protected and oligotrophic, warm-water lagoonal environment. Climate was therefore warm during the middle Miocene acme of seismic reefs development, despite the NWS being located ~7° further south than its present position at that time. Results of this investigation also support the existence of a strong southward flowing Leeuwin-current-style oceanic circulation during the middle Miocene, which could have transported fauna from south-east Asia along the Western Australian margin. Development of the lagoon and seismic reefs may have also been promoted by middle Miocene aridification of the coast bordering the NWS, and by repeated eustatic-driven exposures of the NWS. [Display omitted] • Lagoon 15–13 Ma with taxa characteristic of tropical oligotrophic reef environments • Facies with micrite, scleractinian corals, Halimeda and larger benthic foraminifera • Outcrops time-equivalent to offshore Middle Miocene Western "Great Barrier Reef" • Time-equivalent to Miocene Climatic Transition, post-date Miocene Climatic Optimum • Climatic, paleoceanographic (proto-Leeuwin current), eustatic or tectonic controls [ABSTRACT FROM AUTHOR]