Reef Development Research Articles

Effects of LED Light Illumination on the Growth, Digestive Enzymes, and Photoacclimation of Goniopora columna in Captivity.

Simple SummaryCoral aquaculture is a new industry, which is of great importance to the sustainable development of coral reefs and meeting commercial needs. Light sources are crucial for the growth of corals because zooxanthellae provide them with essential nutrients through photosynthesis. Different corals and zooxanthellae have different photoacclimation characteristics; therefore, selecting a suitable light wavelength remains the critical inhibitor of coral maintenance in marine aquariums. Accordingly, this study investigated the effects of different light wavelengths and feeding of G. columna. The results showed that blue light (440–470 nm) and purple light (400–430 nm) increased the protease and body protein in corals, and the growth and survival rate also increased. In summary, G. columna’s efficient cultivation can use 400–470 nm wavelengths as the primary source of illumination.Goniopora columna is a stony coral valued for its reef-building potential and its unique appearance. Thus, identifying the optimal culture conditions for G. columna would enable efficient cultivation and prevent the illegal exploitation of marine resources. Light sources are crucial for the growth of corals because zooxanthellae provide them with basic nutrients through photosynthesis. Different corals and zooxanthellae have different photoacclimation characteristics; therefore, selecting a suitable light wavelength remains the key inhibitor of coral maintenance in marine aquariums. Accordingly, this study investigated the effects of different light wavelengths on G. columna. It was illuminated for 6 or 12 h a day under white light, yellow light, red light (LR), green light (LG), blue light (LB), or purple light (LP) for 8 weeks. During the experiment, R(R; i.e., a formula feed that combines sodium alginate, protein and probiotics) of 5% (w/v) of G. columna tissue and skeletal dry weight was fed every day. Coral polyps were counted, zooxanthellae density, chlorophyll a concentration, specific growth rates, and survival rates were calculated; polyp stretching and contractile behaviors were observed; and body composition and digestive enzyme activity were analyzed. LB or LP (but not LG or LR) illumination for at least 6 h per day significantly promoted the growth, survival, protein content, and protease activity of the G. columna specimens. Furthermore, coral polyp extension reached 100% after 30 min of LP and LB light irradiation. Although no significant differences in the zooxanthellae density or chlorophyll a concentration were noted under various light wavelengths, significant reductions were detected in the absence of light. To achieve energy-efficient coral aquaculture with regard to G. columna cultivation, 6 h of LB or LP illumination per day can improve the growth.

Middle Oxfordian carbon cycle perturbation expressed in the Smackover Formation, Gulf of Mexico

Abstract The Middle–Late Jurassic opening of the central Atlantic and proto-Caribbean seaways connecting the Pacific with the Tethys Ocean combined with rising sea level led to a major oceanographic and climatic reorganization conducive to the development of widespread carbonate platforms and diverse reefs. The timing of this shift in carbonate production and opening of the Tethys Ocean is well-constrained from outcrops in Europe and western Asia and marked by a notable positive carbon isotope (δ13C) excursion in the middle Oxfordian Gregoryceras transversarium ammonite Zone, termed “MOxE”. However, the temporal constraints from the western arm of the circum-global seaway through the proto-Caribbean and Gulf of Mexico are not well resolved. Presented here are the first paired organic and carbonate carbon-oxygen isotope records from the Smackover Formation, Gulf of Mexico, that record a positive δ13C isotope excursion that is correlated to the middle Oxfordian transversarium Zone. These data are the first record of the MOxE in the Western Hemisphere and provide temporal constraints on the opening of the Gulf of Mexico. Furthermore, the existence of similar δ13C profiles from European basins strongly suggests a coeval response of the carbon cycle to the opening of the central Atlantic and proto-Caribbean seaways connecting the Pacific with the Tethys Ocean.

Gambaran sebaran kondisi terumbu karang di perairan Kecamatan Sangkulirang dan Sandaran Kabupaten Kutai Timur

Sangkulirang and Sandaran as the most northern coastal districts of East Kutai Regency with status of under developing area and yet optimize in accessibility, thus also yet optimal in environment management and observation in this term the coral reef ecosystem. In order to providing the coral reef status information in Sangkulirang and Sandaran District, and further the result could be consider as database in evaluation of future change in coral reef status due to the coastal area development, then this study were conducted in those two districts with field data collecting was held at October 12th - 17th, 2012. The coral percent cover data collecting and analysis were using method of lifeform line intercept transect according to English, et al (1994) and Keputusan Kepala Badan Pengendalian Dampak Lingkungan No.47 year 2001, while the reef condition category were determined from the life hard coral (HCL) percent cover by based on Keputusan Menteri Negara Lingkungan Hidup No.4 year 2001 that divided into four category: 1) poor/bad (HCL < 25 %), 2) fair/moderate (HCL 25% - < 50%), 3) good (HCL 50% - <75%), and excellent (HCL ≥ 75%). The data of reef distribution and area wide were obtained by direct GPS plotting in the field survey with satellite image assist, and further processed using GIS program. According to the result, the coral reef in Sangkulirang and Sandaran District both in same condition that categorize into fair/moderate condition with each coverage of HCL 48.1% and 41.4%, and the combine in average HCL 45,9% also in the same category. Overall of both districts estimated had 2,221.57 ha of coral reef area with condition vary from poor/bad till good category. 761.27 ha of coral reef was estimated in Sangkulirang District and 1,460.30 ha in Sandaran District. The coral reef area in both districts commonly forming a narrow stretch of reef develop along the edge of drop-off bathy profile. Factors of limitation and degradation toward the coral reef development in both districts are: i) non-anthropogenic (nature) factor, majority the turbidity and sediment load from river estuaries and sea current and wave, and ii) anthropogenic (human) factor in activities of destructive fishing method especially by explosive fishing.

Growth Patterns and AMS-14C Age Dates of Fossil Corals from Northwest Pacific

This study aims to evaluate the controlling factor/s of coral growth in the northwest Pacific during the Holocene. Here, we present newly acquired growth data and radiocarbon age dates of fossil Porites corals collected from Holocene uplifted marine terraces in Kikaijima, southern Japan and northwest Luzon, Philippines. Carbonate mineral identification using X-ray diffraction (XRD) and scanning electron microscope (SEM) was conducted to screen for any diagenetic alteration in the fossil corals. We used accelerator mass spectrometer (AMS) – 14C dating to determine the absolute age dates of the fossil corals. Well-preserved fossil corals yielded radiocarbon age dates of 3235 ± 20 and 5712 ± 24 cal. yr BP for Kikaijima and 6285 ± 79, 6144 ± 77, 4336 ± 21, 4277 ± 19, 4200 ± 20, and 2972 ± 70 cal. yr BP for northwest Luzon. X-ray imaging of a 5-mm thick coral slab was utilized to measure growth variables. Linear extension rate, skeletal density, and calcification rate of Kikaijima corals are 3.77–8.72 mm/ yr, 1.71–1.87 g/cm3, and 0.70–1.56 g/cm2yr, respectively. Linear extension rate, skeletal density, and calcification rate from northwest Luzon corals are 10.17–17.6 mm/yr, 0.66–1.67 g/cm3, and 0.91–2.81 g/cm2yr, respectively. Average linear extension rate from both sites was significantly and positively related to average calcification rate (r = 0.72, p = 0.019, n = 10). Skeletal density and linear extension rate measured from both sites were inversely related with each other (r = –0.56, p = 0.09, n = 10). Our data suggest that the variations in linear extension rates of fossil corals were influenced by the sea surface temperature (SST) difference between the study sites. However, data from modern corals are still needed to establish the local linear extension rate- SST relationship and to quantitatively evaluate how coral growth changes with respect to SST. Geomorphological, sedimentological, and geochronological studies of Holocene uplifted marine terraces should be conducted to provide the timing of emergence and coral reef development during Holocene.

Water column and bottom gradients on the continental shelf eastward of the Amazon River mouth and implications for mesophotic reef occurrence

Continental margin sedimentation represents the terrestrial-marine geological transition. Coarser coastal sediments usually transition to fine-grained sediments across the shelf as the energy level decreases. As the distance from the continental source of terrigenous sediments increases, the mid-shelf mud belt transitions to a seaward organic/carbonatic sedimentation domain. However, this general pattern might change depending on the terrigenous sediment load. This is the case for the Amazon continental shelf, where the Amazon River empties and builds up the large Amazon River plume (ARP). The ARP promotes an inverse pattern with muddy nearshore prodelta sediments and siliciclastic sands offshore. This study investigates water and bottom characteristics to the east of the Amazon River mouth to understand the complex interplay that leads to simultaneous massive river plume spread and mesophotic reef development. Three cross-self profiles were performed, including physical-chemical water column measurements and bottom sample collection. The profiles were approximately 150 km apart, comprising a longitudinal gradient off of the ARP. The results reassure that there is enough light for mesophotic reefs to grow at the outer shelf and that at the mid-shelf, large-scale sand movement is likely to be the major limiting control on reef accretion. Also, mesophotic conditions (i.e., low light levels) occur in shallower waters, where a trend of reef expansion was identified, but high-energy levels and the lack of hard substrates hinder reef expansion.

Coralliths of tabulate corals from the Devonian of the Holy Cross Mountains (Poland)

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.

Coralline algal assemblages record Miocene sea-level changes in the South China Sea

We have previously shown that the coralline algal assemblages (CAAs) of the South China Sea may indicate post-Pliocene paleo-water depth changes; however, the pre-Pliocene coralline algal compositions and related sea-level significance remain to be elucidated. In the present study, we explore the Miocene coralline algal compositions and their role in recording the sea level, and show the distribution, classification, type, abundance, and diversity of Miocene coralline algae from 213 petrologic thin sections using a coral-reef carbonate sequence from the northern South China Sea. The diversity and abundance of coralline algae in the early and late Miocene are higher than those in the middle Miocene. Eleven genera were identified and grouped into seven CAAs, showing a water depth range from <5 m to >25 m. At 18.67–17.98 Ma, the coral reef was in a stagnation/drowning stage, with rising sea levels exceeding the development of the coral reef. At 17.98–16.78 Ma, the coral reef was in a rapid development during a rapid rise in sea level. Additionally, at 16.78–14.79 Ma, low coralline algal abundance was observed, and the corals were sporadically distributed at a relatively stable sedimentation rate, suggesting a decline in coral reef development. At 14.79–10 Ma, the coral reef development was remarkably slow or stagnant. Furthermore, at 10–5.3 Ma, the coral reefs developed slowly, indicating a gradual rise in the sea level. The sea-level changes indicated by coral reef development are consistent with the long-term global sea-level changes, indicating that the composition and assemblage of Miocene coralline algae can be used to accurately relay the sea-level history. • Eleven coralline algal genera were identified in a Miocene carbonate sequence. • Miocene coralline algae were divided into 7 coralline algal assemblages (CAAs). • Sea-level changes due to coral reef development were consistent with global values.

Effects of sea-level variation and sedimentary noise variation on the development of biogenic reefs since the Pliocene among the Xisha Islands, South China Sea

Abstract Carbonate strata are a vital and favorable reservoir for global oil and gas exploration, and carbonate sedimentary systems record ancient oceanic and paleoclimatic conditions, including paleoenvironmental variations throughout geologic periods. Carbonate platforms are widely distributed among the Xisha Islands in the South China Sea and contain large amounts of oil and gas resources. Biogenic reefs are the dominant parts of the carbonate platforms in the Xisha Islands; however, research on the factors that control and affect biogenic reef development is lacking. In this study, a core from well XK-1, which is located on Yongxing Island in the Xisha Islands, a sedimentary noise model, and time-series analyses were used to determine the effects of sea-level fluctuations from 5.3 Ma to present. The results show that coral reefs in the Xisha Islands are sensitive to eustatic fluctuations and that a decrease in sea level essentially corresponds to an increase in sedimentation rate. Indexes of the East Asian monsoon and other environmental indexes show that the Pleistocene and Holocene were suitable for coral growth; however, the trends shown by these indexes and the sea-level variation indicate that the future growth of coral reefs will be at a disadvantage. Research on the controlling factors of biogenic reefs is of significance for understanding reef growth, performing global reef comparisons, and encouraging the future protection of coral reefs.

Soft-bottom tidepools within mixed reefs of native mussels and introduced oysters – refuge for associated species and parasites?

AbstractThe introduction of Pacific oysters to the sedimentary south-eastern North Sea coast and their establishment on intertidal native blue mussel beds has caused the development of mixed reefs of mussels and oysters with extensive tidepools. Tidepools have been intensively studied at rocky shores where they show community structures, which usually differ from that of the surrounding emerging substrates. Tidepools at sedimentary coasts, however, have received less attention. We compared the community structure and species interactions inside and outside tidepools in oyster reefs by determining densities of snails, barnacles and amphipods. Snail densities were similar in and outside tidepools. Barnacle coverage on bivalve shells, however, was lower inside tidepools, which may be caused by higher predation pressure and increased snail grazing under permanently submerged conditions, as was revealed by field and laboratory experiments. Additionally, we studied the occurrence of copepod and trematode parasites in blue mussels inside and outside tidepools. Prevalence and intensity of parasitic copepods was higher in mussels inside tidepools. Trematode parasites, by contrast, showed a lower intensity in mussels inside tidepools. This can be explained by high amphipod densities found inside tidepools because trematode larvae represent a food source of amphipods. Our study suggests that the community structure of oyster reefs within tidepools is not a submerged equivalent to that of intertidal reefs. As their counterparts at rocky shores, they show their own species distribution patterns with particular species interactions and only provide refuge for specific species such as parasitic copepods.

Devonian reef development and strata-bound ore deposits in South China

This study focuses on the close association between Devonian reefs and the strata-bound ore deposits in South China. For the first time, the development of Devonian reefs was subdivided into three stages, respectively as the initial, succeeding and peak stages, and its evolution model is proposed. In Dachang, Nandan county, Guangxi Zhuang Autonomous Region (Guangxi for short), a large-scale strata-bound ore deposit formed in a Devonian reef, which was affected by marine volcanic activities and Mesozoic magmatic intrusions. The reef-building reached its peak stage at the Givetian, indicating a large-scale build-up of reef and inter-reef depression. In central–eastern Hunan Province, the strata-bound ore deposits belong to low-temperature ore-types without later magmatic intrusions or volcanic activities. In Hunan Province as well as many other localities in South China, the Givetian reefs played important roles in mobilizing ore-forming materials from the surrounding pre-Devonian rocks, providing spaces and passages for transporting hydrothermal fluid, and progressing mineralization and accumulation of ore-forming materials.

Magnetic Properties and Initiation of Biogenic Reefs in Xisha Islands, South China Sea, at the Oligo–Miocene Boundary

Biogenic reefs and carbonate platforms are valuable natural resources, playing an important role in modulating the global climate and in carbon cycles through biological processes. Biogenic reefs in the Xisha (Paracel) Islands began in the late Oligocene and covaried with the deep-sea basin of the South China Sea and with the aeolian deposit in the Chinese Loess Plateau. Core XK-1 was drilled into the Xisha Islands to their granitic base and well dated by magnetostratigraphy, offering an opportunity to reveal the details of how the Xisha reefs initiated. In this report, the lower section of the biogenic reefs (23.0–24.5 Ma) was sampled for studying magnetic properties. The main results are as follows: (1) magnetic minerals in the XK-1 biogenic reefs are dominated by low-coercivity and relatively coarse-grained magnetite; (2) the variabilities of magnetic parameters can be clustered into two sections around 23.6 Ma, and the differences between the two units are evident both in the amplitudes and the means; and (3) changes in the concentration-dependent magnetic parameters can be well correlated with the records of global deep-sea oxygen and carbon isotopes, and the sea level during the Oligo–Miocene boundary. Based on these results, a close link was inferred between biogenic reef evolution in the Xisha Islands and global climate change. This link likely highlights the covariation or the dominant role of the Asian monsoon in biogenic reefs and involves different responses to global temperature, CO2, and sea-level changes on various timescales. Therefore, we proposed that the origin of biogenic reefs in the Xisha Islands was likely paced by orbital obliquity from a long-term perspective.

Low calcification rate, structural complexity, and calcium carbonate production of Pocillopora corals in a biosphere reserve of the central Mexican Pacific

AbstractThe capacity of coral reefs to provide ecosystem services is widely recognized, but this ability depends on continued carbonate production within the coral community. The Islas Marías archipelago (21° 29.5′ N–106° 15′ W) is subject to minimal anthropic pressures. This archipelago serves as a model to study the influence of environmental variables [e.g., sea surface temperature (SST), upwelling periods, El Niño‐Southern Oscillation (ENSO) events, and pH] on the structure of the coral community. The aim of this study was to evaluate the growth parameters, ecological volume, and CaCO3 production of Pocillopora corals, which comprise the dominant genus in the Eastern Tropical Pacific (ETP). During an annual period (2016–2017), 10 colonies were stained with alizarin red and height, major diameter, and minor diameter measurements were recorded. Live coral cover, the annual extension rate (cm/year), skeletal density (g/cm3), the calcification rate (g/cm2 year−1), ecological volume (cm−3), and carbonate production (kg m−2 year−1) were also calculated. The average extension rate (± SD), skeletal density, and the calcification rate were 1.86 ± 0.31 cm/year, 2.28 ± 0.34 g CaCO3 cm−3, and 4.34 ± 1.28 g CaCO3 cm−2 year−1, respectively. The average live coral coverage was 3.19 ± 3.17%, and the relative cover of Pocillopora corals was 65%. Ecological volume increased 140.6 ± 84.28% with respect to the initial volume, and the average production of CaCO3 was 0.46 ± 0.41 kg CaCO3 m−2 year−1. This study shows evidence of low growth rates, low generation of three‐dimensionality, and low CaCO3 production in the study area when compared to other sites in the ETP. These results are relevant because they indicate compromised long‐term maintenance and reef development in Islas Marías, which may result in low reef functionality and compromise the stability of reef‐associated biodiversity and ecosystem services.

Holocene coral reef development in Chenhang Island, Northern South China Sea, and its record of sea level changes

Holocene coral reef development is valuable to understanding the behavior and impacts of paleoclimate and sea level changes. This study focuses on the Holocene carbonate sequences of a drill core extracted from Well CK2 in the northern South China Sea (SCS). This drill core consists of an 873.55 m thick carbonate layer overlying 55.20 m of volcanic basement. High precision U-series dating of 22 coral samples suggests that the Holocene coral reef, which has a thickness of 16.7 m, initiated at ~7800 yr BP (years before 1950 CE) and stopped vertical accretion at 3900 yr BP. The mean vertical accretion rate in the Holocene in Well CK2 was 3.48 m kyr−1, varying from 6.44 m kyr−1 during 7800–6000 yr BP to 0.87 m kyr−1 during 6000–3900 yr BP. After 3900 yr BP, the vertical development of the reef ceased, indicating that the reef development likely involved lateral accretion. The Holocene section mostly consists of unconsolidated coarse sediments, mainly including corals, coralline algae, large benthic foraminifera, and mollusks. Based on the relationship between coral reef development and sea level, together with the age profile, we determined that the relative sea level near Chenhang Island rose rapidly between 7800 and 6000 yr BP, slowed at ~6000 yr BP, and reached a position of about 2 m above the present-day mean sea level by 3900 yr BP. After 3900 yr BP, the sea level was stable or fell, resulting in a cessation in the reef's upward development.

Environmental controls on holocene reef development along the eastern brazilian margin

Environmental controls on holocene reef development along the eastern brazilian margin

Biodegradable Material for Oyster Reef Restoration: First-Year Performance and Biogeochemical Considerations in a Coastal Lagoon

Oyster reef restoration efforts increasingly consider not only oyster recruitment, but also the recovery of ecological functions and the prevention of deploying harmful plastics. This study investigated the efficacy of a biodegradable plastic-alternative, BESE-elements®, in supporting oyster reef restoration in east-central Florida (USA) with consideration for how this material also influences biogeochemistry. Four experiments (two laboratory, two field-based) were conducted to evaluate the ability of BESE to serve as a microbial substrate, release nutrients, support oyster recruitment and the development of sediment biogeochemical properties on restored reefs, and degrade under field conditions. The results indicated BESE is as successful as traditional plastic in supporting initial reef development. In the lab, BESE accelerated short-term (10-day) sediment respiration rates 14-fold and released dissolved organic carbon, soluble reactive phosphorus, and nitrate to the surface water (71,156, 1980, and 87% increase, respectively) relative to without BESE, but these effects did not translate into measurable changes in reef sediment nutrient pools under field conditions. BESE lost 7–12% mass in the first year, resulting in a half-life of 4.4–6.7 years. Restoration practitioners should evaluate the biogeochemical properties of biodegradable materials prior to large-scale deployment and consider the fate of the restoration effort once the material degrades.

SOUTH CAUCASUS PALAEOGEOGRAPHY AND PROSPECTIVITY: ELEMENTS OF PETROLEUM SYSTEMS FROM THE BLACK SEA TO THE CASPIAN

Nine Mesozoic and Cenozoic palaeogeographic maps are presented to illustrate the petroleum prospectivity of the South Caucasus from a fresh perspective and as part of the wider Caucasus region. Previously, elements of petroleum systems – reservoir, source and sealing lithologies, and the timing of their formation – have mostly been examined within individual sub‐basins or licence blocks, and regional understanding has been limited. Emphasis is placed here on the onshore prospectivity of Georgia and Azerbaijan; the well‐known Pliocene Productive Series of eastern Azerbaijan and the southern Caspian is not considered.The Great Caucasus Basin (GCB) formed in the Early Jurassic following closure of PalaeoTethys, and remained a significant feature, despite structural modifications, until end‐Eocene underthrusting and uplift converted the basin into the Greater Caucasus mountains. By the Toarcian a major delta system had developed along its northeastern margin, while the Transcaucasus block to the south was mostly covered by a shallow sea with limited sediment supply. Bajocian volcanism across the South Caucasus was accompanied by modification of the structure of the Great Caucasus Basin with the intrusion of tholeiitic dykes, possibly associated with onset of northward NeoTethyan subduction. Rising sea levels led to the abandonment of the GCB delta system. Relative uplift of the South Caucasus in the Bathonian created lowlands surrounded by marginal settings in which paralic deposits and coals were laid down. Jurassic hydrocarbon source rocks include deep‐marine shales deposited within the Great Caucasus Basin together with coals; their potential is confirmed by numerous seeps within both Georgia and Azerbaijan. Various Middle Jurassic sandstones are potential reservoirs.Carbonates dominated by the late Callovian, with widespread development of Oxfordian reefs and of Late Jurassic evaporite basins in the North Caucasus. Bedded anhydrites in Georgia comprise potential seals. Shallow‐marine clastics again became widespread across the Caucasus in the Cretaceous, later replaced by carbonates including chalk‐like limestones. Deeper‐marine conditions persisted in the Great Caucasus Basin, which became less well‐defined and split into separate depocentres. Fractured chalks are known reservoirs in the North Caucasus and prospective reservoirs in the South Caucasus.Uplift of the southern South Caucasus during the Paleogene led to northward transport of sediment into evolving E‐W to ESE‐WSW basins in eastern Georgia and western Azerbaijan. Marine deposits within these basins form reservoirs, including thick fractured volcanogenic turbidites in eastern Georgia. Reduced sediment supply here at the start of the Late Eocene allowed organic‐rich restricted‐marine source rocks to accumulate.Rapid uplift of the GCB associated with underthrusting at the end of the Eocene led to emergence of the Greater Caucasus mountains. The prolific Maikopian source rocks were deposited in restricted‐marine conditions during the Oligocene and Early Miocene over the North Caucasus, parts of Azerbaijan and western Georgia, but they are diluted by coarser clastics in eastern Georgia where the Late Eocene source is more significant. Later Miocene uplift of the entire Caucasus region resulted in progressive marine regression, and the formation of potential reservoirs in alluvial and shallow‐marine sands.

The Microbiome Associated with the Reef Builder Neogoniolithon sp. in the Eastern Mediterranean.

The development of coastal vermetid reefs and rocky shores depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon sp. To initiate studies on the interaction between Neogoniolithon sp. and its associated bacteria, and their impact on the algae physiological performance, we characterized the bacterial community by 16S rRNA gene sequencing. These were extracted from the algal tissue and adjacent waters along two sampling campaigns (during winter and spring), in three study regions along a reef in the east Mediterranean Israeli coast and from laboratory-grown algae. The analysis revealed that aquaria and field communities differ substantially, suggesting that future research on Neogoniolithon sp. interaction with its microbiome must rest on aquaria that closely simulate coastal conditions. Some prokaryote classes found associated with the alga tissue were hardly detected or absent from surrounding water. Further, bacterial populations differed between sampling campaigns. One example is the presence of anaerobic bacteria and archaea families in one of the campaigns, correlating with the weaker turbulence in the spring season, probably leading to the development of local anoxic conditions. A better understanding of reef-building activity of CCA and their associated bacteria is necessary for assessment of their resilience to climate change and may support coastal preservation efforts.

Climate and the latitudinal limits of subtropical reef development

Climate plays a central role in coral-reef development, especially in marginal environments. The high-latitude reefs of southeast Florida are currently non-accreting, relict systems with low coral cover. This region also did not support the extensive Late Pleistocene reef development observed in many other locations around the world; however, there is evidence of significant reef building in southeast Florida during the Holocene. Using 146 radiometric ages from reefs extending ~ 120 km along Florida’s southeast coast, we test the hypothesis that the latitudinal extent of Holocene reef development in this region was modulated by climatic variability. We demonstrate that although sea-level changes impacted rates of reef accretion and allowed reefs to backstep inshore as new habitats were flooded, sea level was not the ultimate cause of reef demise. Instead, we conclude that climate was the primary driver of the expansion and contraction of Florida’s reefs during the Holocene. Reefs grew to 26.7° N in southeast Florida during the relatively warm, stable climate at the beginning of the Holocene Thermal Maximum (HTM) ~ 10,000 years ago, but subsequent cooling and increased frequency of winter cold fronts were associated with the equatorward contraction of reef building. By ~ 7800 years ago, actively accreting reefs only extended to 26.1° N. Reefs further contracted to 25.8° N after 5800 years ago, and by 3000 years ago reef development had terminated throughout southern Florida (24.5–26.7° N). Modern warming is unlikely to simply reverse this trend, however, because the climate of the Anthropocene will be fundamentally different from the HTM. By increasing the frequency and intensity of both warm and cold extreme-weather events, contemporary climate change will instead amplify conditions inimical to reef development in marginal reef environments such as southern Florida, making them more likely to continue to deteriorate than to resume accretion in the future.

Physiological Differences in Bleaching Response of the Coral Porites astreoides Along the Florida Keys Reef Tract During High-Temperature Stress

The Florida Keys reef tract (FKRT) has a unique geological history wherein Holocene sea-level rise and bathymetry interacted, resulting in a reef-building system with notable spatial differences in reef development. Overprinted on this geologic history, recent global and local stressors have led to degraded reefs dominated by fleshy algae, soft corals, and sponges. Here, we assessed how coral physiology (calcification rate, tissue thickness, reproduction, symbiosis, and bleaching) varies seasonally (winter vs. summer) and geographically using 40 colonies of the mustard hill coral Porites astreoides from four sites across 350 km along the FKRT from 2015 to 2017. The study coincided with a high-temperature event in late summer 2015 that caused heterogeneous levels of coral bleaching across sites. Bleaching severity differed by site, with bleaching response more aligned with heat stress retroactively calculated from local degree heating weeks than those predicted by satellites. Despite differences in temperature profiles and bleaching severity, all colonies hosted Symbiodiniaceae of the same genus (formerly Clade A and subtypes). Overall, P. astreoides at Dry Tortugas National Park, the consistently coolest site, had the highest calcification rates, symbiont cell densities, and reproductive potential (all colonies were reproductive, with most planula larvae per polyp). Corals at Dry Tortugas and Fowey Rocks Light demonstrated strong seasonality in net calcification (higher in summer) and did not express visual or partial-mortality responses from the bleaching event; in contrast, colonies in the middle and southern part of the upper keys, Sombrero Key and Crocker Reef, demonstrated similar reduced fitness from bleaching, but differential recovery trajectories following the heat stress. Identifying reefs, such as Dry Tortugas and possibly Fowey Rocks Light that may serve as heat-stress refugia, is important in selecting candidate sites for adaptive reef-management strategies, such as selective propagation and assisted gene flow, to increase coral-species adaptation to ocean warming.

Online-coupling of widely-ranged timescales to model coral reef development

The increasing pressure on Earth's ecosystems due to climate change is becoming more and more evident and the impacts of climate change are especially visible on coral reefs. Understanding how climate change interacts with the physical environment of reefs to impact coral growth and reef development is critically important to predicting the persistence of reefs into the future. In this study, a biophysical model was developed including four environmental factors in a feedback loop with the coral's biology: (1) light; (2) hydrodynamics; (3) temperature; and (4) pH. The submodels are online coupled, i.e. regularly exchanging information and feedbacks while the model runs. This ensures computational efficiency despite the widely-ranged timescales. The composed biophysical model provides a significant step forward in understanding the processes that modulate the evolution of coral reefs, as it is the first construction of a model in which the hydrodynamics are included in the feedback loop.