Massive cryptic microbe-sponge deposits in a Devonian fore-reef slope (Elbingerode Reef Complex, Harz Mts., Germany)

A massive occurrence of microbial carbonates, including abundant sponge remains, within the Devonian Elbingerode Reef Complex was likely deposited in a former cavity of the fore-reef slope during the early Frasnian. It is suggested that the formation of microbial carbonate was to a large part favored by the activity of heterotrophic, i.e., sulfate-reducing bacteria, in analogy to Quaternary coral reef microbialites. The Elbingerode Reef Complex is an example of an oceanic or Darwinian barrier reef system. In modern barrier reef settings, microbialite formation is commonly further facilitated by weathering products from the central volcanic islands. The Devonian microbialites of the Elbingerode Reef Complex occur in the form of reticulate and laminated frameworks. Reticulate framework is rich in hexactinellid glass sponges, the tissue decay of which led to the formation of abundant micrite as well as peloidal and stromatactis textures. Supposed calcimicrobes such as Angusticellularia (formerly Angulocellularia) and Frutexites, also known from cryptic habitats, were part of the microbial association. The microbial degradation of sponge tissue likely also contributed to the laminated framework accretion as evidenced by the occurrence of remains of so-called “keratose” demosponges. Further typical textures in the microbialite of the Elbingerode Reef Complex include zebra limestone, i.e., the more or less regular intercalation of microbial carbonate and cement. Elevated concentrations of magnesium in the microbialite as compared to the surrounding metazoan (stromatoporoid-coral) reef limestone suggests that the microbialite of the Elbingerode Reef Complex was initially rich in high-magnesium calcite, which would be yet another parallel to modern, cryptic coral reef microbial carbonates. Deposition and accretion of the microbialite largely occurred in oxygenated seawater with suboxic episodes as indicated by the trace element (REE + Y) data.

Scaling the effects of ocean acidification on coral growth and coral–coral competition on coral community recovery

Ocean acidification (OA) is negatively affecting calcification in a wide variety of marine organisms. These effects are acute for many tropical scleractinian corals under short-term experimental conditions, but it is unclear how these effects interact with ecological processes, such as competition for space, to impact coral communities over multiple years. This study sought to test the use of individual-based models (IBMs) as a tool to scale up the effects of OA recorded in short-term studies to community-scale impacts, combining data from field surveys and mesocosm experiments to parameterize an IBM of coral community recovery on the fore reef of Moorea, French Polynesia. Focusing on the dominant coral genera from the fore reef, Pocillopora, Acropora, Montipora and Porites, model efficacy first was evaluated through the comparison of simulated and empirical dynamics from 2010–2016, when the reef was recovering from sequential acute disturbances (a crown-of-thorns seastar outbreak followed by a cyclone) that reduced coral cover to ~0% by 2010. The model then was used to evaluate how the effects of OA (1,100–1,200 µatm pCO2) on coral growth and competition among corals affected recovery rates (as assessed by changes in % cover y−1) of each coral population between 2010–2016. The model indicated that recovery rates for the fore reef community was halved by OA over 7 years, with cover increasing at 11% y−1 under ambient conditions and 4.8% y−1 under OA conditions. However, when OA was implemented to affect coral growth and not competition among corals, coral community recovery increased to 7.2% y−1, highlighting mechanisms other than growth suppression (i.e., competition), through which OA can impact recovery. Our study reveals the potential for IBMs to assess the impacts of OA on coral communities at temporal and spatial scales beyond the capabilities of experimental studies, but this potential will not be realized unless empirical analyses address a wider variety of response variables representing ecological, physiological and functional domains.

Coral Reef Restorations Can Be Optimized to Reduce Coastal Flooding Hazards

Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protection value of reefs while also reducing their other ecosystem services, making them a target for restoration. Here we provide a physics-based evaluation of how coral restoration can reduce coastal flooding for various types of reefs. Wave-driven flooding reduction is greatest for broader, shallower restorations on the upper fore reef and between the middle of the reef flat and the shoreline than for deeper locations on the fore reef or at the reef crest. These results indicate that to increase the coastal hazard risk reduction potential of reef restoration, more physically robust species of coral need to be outplanted to shallower, more energetic locations than more fragile, faster-growing species primarily being grown in coral nurseries. The optimization and quantification of coral reef restoration efforts to reduce coastal flooding may open hazard risk reduction funding for conservation purposes.

The Sedimentology of the Late Campanian–Maastrichtian Sequence, Southwestern Iraq

Petrography, diagenesis, and facies analyses as well as the depositional environments of the late Campanian-Maastrichtian sequence in southwestern Iraq are studied in five keyholes. The sequence incorporates parts of the Hartha, Shiranish and Tayarat Formations. The Hartha Formation comprises creamy and organodetrital dolomite, grey dolomitic marl, and evaporites. The Shiranish Formation is composed of grey marl and claystone, whereas the Tayarat Formation is composed of grey ash, along with tough and fossiliferous dolomitic limestone inter-bedded with grey mudstone layers and/or wisps. Several diagenetic processes affected the sequence, such as neomorphic replacement, dissolution, dolomitization, and sulphate development. Some of these processes obliterated the primary textures. The late Campanian-Maastrichtian sequence consists of three microfacies (Dolomitic Intraclastic Limestone, Dolomitized Biomicrite, and Biomicrosparite Microfacies) and two lithofacies (Mudrock and Sulphates-Rock Lithofacies), in addition to Fine- to Medium-Crystalline Dolomite Lithotype. The Hartha Formation is evaporitic, possibly with supratidal sabkha deposits. The overlying Tayarat and Shiranish Formations reflect deposition in a warm tropical to subtropical reefal and open marine conditions, as deduced from faunal assemblages. Some effects of deep marine condition are evident by the presence of Shiranish facies. The sequence represents deposition in the central reef- fore reef area. The absence of isolated back-reef lagoon facies suggests that the reef was patchy without isolation of water in the middle shelf region. However, at the top of the sequence, i.e. at the end of the Cretaceous Period, restricted lagoons seem to have dominated the studied succession.

FACIES DISTRIBUTION OF KAIS FORMATION IN “X” FIELD, SALAWATI BASIN, WEST PAPUA, INDONESIA

<p class="Abstract">Daerah penelitian lapangan “X” terletak di Formasi Kais, Cekungan Salawati, Papua Barat, Indonesia. Maksud dan tujuan dari penelitian ini adalah untuk menginterpretasikan fasies karbonat, beserta penyebarannya, baik secara vertikal maupun horizontal. Penelitian dimulai dengan penafsiran <em>litostratigrafi</em> menggunakan data <em>log</em> dan sayatan tipis, untuk membuat <em>type log</em>. Dilanjut dengan analisis sikuen stratigrafi dan <em>reef system</em> untuk menentukan penyebaran, dengan bantuan data seismik untuk dikorelasikan dengan sumur-sumur lainnya. Dari hasil analisis, terdapat 5 fasies pada daerah penelitian, yaitu: <em>Skeletal Debris Packstone-Wackestone, Coral Algal Grainstone – Boundstone, Skeletal Wackestone, Skeletal Packstone dan Coral Algal Packstone</em>. Terdapat pula 4 <em>reef system</em>, yaitu; <em>Back reef, reef crest, fore reef dan off reef</em>. Untuk mencapai tujuan akhir dari penelitian ini, maka dibuat peta penyebaran fasies.</p>

Influence of reef flat submergence on infra-gravity wave energy and resonance over the fringing reef

Fringing reefs which are common nearshore islands with coral reef growth have special topography of very steep slope on the fore-reef and mild slope on the wide flat. When incident waves propagate from a very deep water region (from hundreds of meters to thousands of meters of depth) to approaching the reef they abruptly commence a very shallow water (only few centimeters to several meters of depth) and create strong hydrodynamic processes on the reef flat. Due to shallow depth, waves feel the bottom and break in the area of fore-reef slope and reef crest and partial reef flat. Infra-gravity waves (IG), other name as bound long waves or surf beat, which belong to low-frequency wave type (0.002Hz ¸ 0.04Hz) are generated by the varying-breaking point mechanism on the shallow reef flat. On the flat, short wave energy is almost dissipated; low-frequency waves are strongly dominated over the surf zone till swash zone. Wave set-up causing an increase of water level on the flat combines with the run-up at the shoreline which can lead to coastal flooding. Besides, if the reef flat length is in the order of one fourth of wavelength the first oscillation resonant mode with standing wave occurs. This component is resonantly amplified at the shoreline relative to the incident infra-gravity wave energy at the reef crest.

Microfacies and biostratigraphy of an Upper Triassic Dachstein limestone fore-reef block in the Jurassic Sirogojno carbonate-clastic Mélange (Zlatibor Mt., SW Serbia)

In the late Middle to early Late Jurassic carbonate-clastic Sirogojno M?lange in the Zlatibor Mountain there is one roughly 35 m thick overturned block with an intact Late Triassic fore-reefal Dachstein Limestone succession that was studied here for its biostratigraphic age, faunal content and microfacies characteristics. The succession starts with coarse-grained rudstones followed by meter-sized reefal blocks intercalated in partly layered resedimented grainstones and packstones with abundant reef-building organisms like calcareous sponges, corals and encrusting organisms. Inside this part of the succession open-marine influenced layers are rare. The succession continues with a partly turbiditic sequence and chaotic rudstones, densely packed with reef-derived material like broken reef-building organisms and shallow-water material like gastropods, bivalves and foraminifers. Grainstones with clear open-marine influence (e.g., thin-shelled bivalves, crinoids, conodonts) appear in between those rudstones, in cases lumachelle layers consisting of halobiids were deposited. To the end of the succession some layers show turbiditic bedding with mixed shallow- water and deep-marine grains and organisms, i.e. filaments and crinoids. On base of conodonts, foraminifers, calcareous algae, holothurians and halobiids throughout the whole studied succession, a Middle Norian (Alaunian) to Rhaetian 1, most probably a Late Norian (Sevatian) age can be assigned to this forereefal Dachstein Limestone succession, with a similar sedimentation pattern like Late Triassic Dachstein fore-reef limestone facies, e.g., in the Northern Calcareous Alps or the eastern Southern Alps. The study of this block in the Sirogojno M?lange closes an important gap in knowledge about the extent, facies and stratigraphy of the Dachstein Carbonate Platform evolution in the Dinarides.

Ecological and Infrastructure Assessment of Kanton (Abariringa) Island, Phoenix Island Protected Area, Kiribati

The remote Kanton (Abariringa) Atoll, in the South Pacific Phoenix Islands Protected Area, was assessed using rapid techniques to describe the infrastructure, fish, coral, birds, vegetation, sharks, turtles, and marine mammals. Median live coral cover was 28% (8%–93%) with 11 coral genera, the most abundant being tabular <i>Acropora</i> spp. A total of 130 species of fish (9365 individuals) showed highest abundance in the fore reef habitat. The most abundant bird was the Brown noddy (<i>Anous stolidus</i>) with 3600 individuals counted. Nine species of plants were identified, with Beach saltbush (<i>Scaevola sericea</i>) being the most abundant. Assessment of the aesthetics of dive sites identified two excellent sites: the shipwreck of <i>President Taylor</i> and the Cascades, with very high abundances of coral and reef fish.

Ecological and Infrastructure Assessment of Kanton (Abariringa) Island, Phoenix Island Protected Area, Kiribati

The remote Kanton (Abariringa) Atoll, in the South Pacific Phoenix Islands Protected Area, was assessed using rapid techniques to describe the infrastructure, fish, coral, birds, vegetation, sharks, turtles, and marine mammals. Median live coral cover was 28% (8%–93%) with 11 coral genera, the most abundant being tabular <i>Acropora</i> spp. A total of 130 species of fish (9365 individuals) showed highest abundance in the fore reef habitat. The most abundant bird was the Brown noddy (<i>Anous stolidus</i>) with 3600 individuals counted. Nine species of plants were identified, with Beach saltbush (<i>Scaevola sericea</i>) being the most abundant. Assessment of the aesthetics of dive sites identified two excellent sites: the shipwreck of <i>President Taylor</i> and the Cascades, with very high abundances of coral and reef fish.