Hermatypic Research Articles

Coral communities on artificial reefs in the Gulf of Mexico: standing vs. toppled oil platforms

Abstract Sammarco, P. W., Lirette, A., Tung, Y. F., Boland, G. S., Genazzio, M., and Sinclair, J. 2014. Coral communities on artificial reefs in the Gulf of Mexico: standing vs. toppled oil platforms. – ICES Journal of Marine Science, 71: 417–426. Thousands of oil platforms in the northern Gulf of Mexico have provided hard substrate for settlement of Caribbean corals and have facilitated their range expansion. The US Department of the Interior, Bureau of Ocean Energy Management now allows platforms to be purposely toppled to the bottom and used as artificial reefs to promote fisheries development. We compared the coral communities on standing offshore oil/gas production platforms with those on “Rigs-to-Reef” structures through Remotely Operated Vehicle reconnaissance (max. depth ∼110 m) to assess comparative population sizes of several coral species. Corals found were the zooxanthellate Madracis decactis and azooxanthellate Tubastraea coccinea, Oculina diffusa, and Phyllangia americana. There was no significant difference in total coral density between standing and toppled platforms, due to varying species-specific abundances. Madracis decactis and T. coccinea densities were significantly higher on toppled structures than on standing ones, P. americana was more abundant on standing platforms, and O. diffusa densities were not significantly different between the two sets of platforms. Corals were distributed more deeply on standing platforms than on toppled ones (particularly O. diffusa and P. americana). Madracis decactis (requiring light) and T. coccinea were concentrated at shallower depths (≤50 m). Rigs-to-Reefs structures serve as substrate for coral settlement. The probability of continued coral growth in these early stages of succession varies between species, when considering standing vs. toppled structures. We did not see overall evidence that toppling enhanced hermatypic coral populations, increased coral abundances in general, or created 3D reef-like fish habitat.

Physiological responses to oxidative stress associated with pH variations in host tissue and zooxanthellae of hermatypic coral Pocillopora capitata

To study the adaptive mechanisms of host and symbiont in a decrease in pH, coral branches of Pocillopora capitata from La Boquita reef in the Bay of Santiago, México were assigned to experimental units (n = 38 per treatment) and three pH treatments were evaluated: (a) pH 8.00–8.40 (control; Treatment C1), (b) pH 7.85–7.95 (Treatment C2) and (c) pH 7.60–7.70 (Treatment C3). Corals were collected at the beginning of the experiment (T0) and at different times: T1 (5 h), T2 (12 h), T3 (48 h) and T4 (168 h). We examined malondialdehyde (MDA), antioxidant enzyme activities (SOD and CAT), antioxidant capacity and chlorophyll a (Chl a) content. The results showed a different response to the treatment between zooxanthellae and Cnidaria tissues. Initially in zooxanthellae, we observed a SOD response for the C3 treatment; however this response did not prevent lipid degradation. In Cnidaria, the C3 resulted in a greater SOD activity from the middle to the end of the experiment. The results improve our understanding of the effects of ocean acidification, the ability of coral to respond to environmental changes and the use of biochemical indicators related to the physiological condition for the recognition of coral communities affected by a decreases in pH.

Post Bleaching Assessment of Corals in Andaman and Nicobar Islands

Reefs of Andaman and Nicobar Islands harbour 418 species of scleractinian corals spread over an area of 2,000 km2. In April to May, 2010, due to the delayed onset of the southwest monsoon the sea surface temperature of the coastal and oceanic region increased to 31.7 °C in respect to the earlier record of maximum 29.0 °C during the said period. This resulted in mass bleaching of hermatypic corals during May, 2010. Rapid under water surveys have been conducted in reefs of Andaman and Nicobar Islands to assess the health of corals between May 2010 and August 2011. It is estimated that 76.62 ± (SD) 10.83 % of coral species are bleached up to a water depth of 10–15 m. Species from the genus Acropora appeared more susceptible to bleaching than those belong to the genus Porites. During the month of June 2010 the sea surface temperature was reduced to 29 °C perhaps due to the rainfall which stimulated rebuilding of zooxanthellae population in bleached corals. Recovery of 85.54 ± (SD) 6.33 % of bleached corals was seen during the study period of 11 months after the bleaching event. Porites spp. showed a high recovery rate, while Acropora spp. had the highest mortality rate. Coral mortality can have profound ecological and socio-economical implications and highlights the need for sustained monitoring for coral reef conservation in India. Hence, steps must be taken to improve management tools to protect these resources of global significance.

Coral microatoll reconstructions of El Niño-Southern Oscillation: New windows on seasonal and interannual processes

Porites coral microatolls show δ18O signal reproducibility and fidelity comparable to more conventional coral growth forms. Longer-lived and fossil microatolls, which grow in suitably flushed environments, contain δ18O signals that can significantly extend instrumental records of the El Nino-Southern Oscillation. Porites corals are the most commonly used genus for reconstructing El NinoSouthern Oscillation (ENSO). This hermatypic coral is found in all tropical reef environments (Veron 2000) with a variety of growth forms. Climate reconstructions of a century or more have been obtained from the most common, dome-shaped Porites growth form, whereby the colonies, beginning from the substrate, grow outward and upward towards the ocean surface (Knutson et al. 1972). Domed structures, however, are not the only Porites growth form.

Visualization of oxygen distribution patterns caused by coral and algae

Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were assessed in light and dark conditions and under varying flow regimes. The images show discrete high oxygen concentration regions above the organisms during lighted periods and low oxygen in the dark. Size and orientation of these areas were dependent on flow regime. For corals and algae in close proximity the 2D optodes show areas of extremely low oxygen concentration at the interaction interfaces under both dark (18.4 ± 7.7 µmol O2 L- 1) and daylight (97.9 ± 27.5 µmol O2 L- 1) conditions. These images present the first two-dimensional visualization of oxygen gradients generated by benthic reef algae and corals under varying flow conditions and provide a 2D depiction of previously observed hypoxic zones at coral algae interfaces. This approach allows for visualization of locally confined, distinctive alterations of oxygen concentrations facilitated by benthic organisms and provides compelling evidence for hypoxic conditions at coral-algae interaction zones.

Detecting hyperthermal stress in larvae of the hermatypic coral Porites astreoides: the suitability of using biomarkers of oxidative stress versus heat-shock protein transcriptional expression

Scleractinian coral populations are declining worldwide in response to a variety of factors including increases in sea surface temperatures. To evaluate the effects of predicted elevated seawater temperatures on coral recruitment, larvae from the coral Porites astreoides were exposed to seawater at ambient (27.3 °C) or elevated temperature (30.8 °C) conditions for 4, 24, or 48 h. Following exposure, larvae were tested for survival and settlement, oxidative stress, respiratory demand, and mRNA expression of heat-shock proteins (Hsps) 16 and 60. While elevated temperature had no effect on larval survival, settlement, or expression of Hsps, it did cause a significant increase in larval respiration, oxidative damage (lipid peroxidation), and antioxidant enzyme activity (catalase). The absence of a significant up-regulation of Hsp 16 or 60 expression in response to thermal stress suggests that the transcriptional expression of these genes is a less sensitive diagnostic tool compared to biomarkers of oxidative stress at the temperatures examined. The results of this study provide evidence that enhanced levels of oxidative stress are encountered in zooxanthellae-containing coral larvae in response to elevated temperatures and that this occurrence should be strongly considered for use as a biomarker when monitoring sub-lethal cellular responses to rising sea surface temperatures.

Bleaching: The Driving Force of Scleractinian New Recruitment at Little Andaman Island, Andaman and Nicobar Islands

Peak bleaching of corals was seen in 2010 in the Andaman and Nicobar Islands. The results were observed as adverse impacts on the reef environment. Little Andaman Island is the southern-most part of Andaman group of Islands. The continental shelf of this island showed a limited number of scleractinian corals as new recruitment at the destroyed reef areas after the 2004 tsunami. Only 34 species of hermatypic corals were reported in 2009. Consecutive underwater survey and experimental outcome reveals that 124 species of scleractinian corals were identified from the same areas after the mass bleaching effect. The presence of species composition of the study area is near about 4 times higher than the study which was made on newly recruited corals after tsunami. Bleaching was the only giant event which occurred in between 2009 and 2012, considered as the prime regulator for the new recruitment of scleractinians. The Shannon–Weaver’s species diversity index of the study area ranges from 5.09 to 6.00, Simpson’s species density index varies from 0.94 to 0.97 whereas the Pielou’s evenness index shows the results in between 0.93 and 0.98. The present paper depicts the species composition, diversity, density and evenness at post bleaching state to signify the constructive role of bleaching towards the settlement of new scleractinian coral life on the preceding places.

Experimental artificial cultivation of corals from colony fragments

In 2010–2011, experimental commercial cultivation of 14 species of hermatypic corals was carried out using the method of donor colony fragmentation. The transplants successfully survived on experimental frame installations. The coral colonies that were recovered from the fragments became attached to the frame installations in a similar way to their attachment on natural substrata. After 1 year, the size of the trans-plants was found to have increased by 275%. The newly formed artificial coral community was colonized by the damselfish Dascyllus reticulates (Pomacentridae); the species is a common coral fish species that lives on natural reefs.

Proteomic analysis of skeletal organic matrix from the stony coral Stylophora pistillata

It has long been recognized that a suite of proteins exists in coral skeletons that is critical for the oriented precipitation of calcium carbonate crystals, yet these proteins remain poorly characterized. Using liquid chromatography-tandem mass spectrometry analysis of proteins extracted from the cell-free skeleton of the hermatypic coral, Stylophora pistillata, combined with a draft genome assembly from the cnidarian host cells of the same species, we identified 36 coral skeletal organic matrix proteins. The proteome of the coral skeleton contains an assemblage of adhesion and structural proteins as well as two highly acidic proteins that may constitute a unique coral skeletal organic matrix protein subfamily. We compared the 36 skeletal organic matrix protein sequences to genome and transcriptome data from three other corals, three additional invertebrates, one vertebrate, and three single-celled organisms. This work represents a unique extensive proteomic analysis of biomineralization-related proteins in corals from which we identify a biomineralization "toolkit," an organic scaffold upon which aragonite crystals can be deposited in specific orientations to form a phenotypically identifiable structure.

Potential habitat of Acropora spp. on Florida reefs

Elkhorn and staghorn corals (Acropora palmata, Acropora cervicornis) were listed as threatened species under the Endangered Species Act in 2005. The decline of these species beginning in the late 1970s is unprecedented given the vital role they historically played as major builders of western Atlantic and Caribbean coral reefs. The goal of this study was to create potential-habitat maps for A. palmata and A. cervicornis that would show areas in which these species currently exist, as well as areas that would be suitable for their (re)establishment, using a database of reported in situ observations and existing mapped data. Using the mapped coral reef and hardbottom classifications throughout the Florida reef tract, potential-habitat maps were generated using buffers that incorporated 95% and 99% of reported observations of colonies of Acropora spp. The potential-habitat maps were produced based on benthic substrates throughout the Florida reef tract using GIS software. Locations of 99% of A. palmata observations and 84% of A. cervicornis observations coincided with previously mapped coral reef or hardbottom habitat. These results indicate that potential habitat for A. palmata is currently well defined and that potential habitat for A. cervicornis is more variable and has a wider range than that for A. palmata. This study provides a novel method of combining datasets at various geographic spatial scales and may be used to inform the current NOAA critical habitat map. One of the most important differences between the current NOAA critical habitat map and the new potential-habitat map is observed in the southeast Florida region, where A. cervicornis appears to be thriving outside of mapped reef areas and at latitudes considered marginal for hermatypic corals. Thus, the potential habitat extends further north than the previous critical habitat - and encompasses additional habitat for A. cervicornis and potentially for A. palmata.

A comparison of culture-dependent and culture-independent techniques used to characterize bacterial communities on healthy and white plague-diseased corals of the Montastraea annularis species complex

Diseases of hermatypic corals pose a global threat to coral reefs, and investigations of bacterial communities associated with healthy corals and those exhibiting signs of disease are necessary for proper diagnosis. One disease, commonly called white plague (WP), is characterized by acute tissue loss. This investigation compared the bacterial communities associated with healthy coral tissue (N = 15), apparently healthy tissue on WP-diseased colonies (N = 15), and WP-diseased tissues (N = 15) from Montastraea annularis (species complex) colonies inhabiting a Bahamian reef. Aliquots of sediment (N = 15) and water (N = 15) were also obtained from the proximity of each coral colony sampled. Samples for culture-dependent analyses were inoculated onto one-half strength Marine Agar (½ MA) and Thiosulfate Citrate Bile Salts Sucrose Agar to quantify the culturable communities. Length heterogeneity PCR (LH-PCR) of the 16S rRNA gene characterized the bacterial operational taxonomic units (OTU) associated with lesions on corals exhibiting signs of a white plague-like disease as well as apparently healthy tissue from diseased and non-diseased conspecifics. Analysis of Similarity was conducted on the LH-PCR fingerprints, which indicated no significant difference in the composition of bacterial communities associated with apparently healthy and diseased corals. Comparisons of the 16S rRNA gene amplicons from cultured bacterial colonies (½ MA; N = 21) with all amplicons obtained from the whole coral-associated bacterial community indicated ≥39 % of coral-associated bacterial taxa could be cultured. Amplicons from these bacterial cultures matched amplicons from the whole coral-associated bacterial community that, when combined, accounted for >70 % total bacterial abundance. An OTU with the same amplicon length as Aurantimonascoralicida (313.1 bp), the reported etiological agent of WPII, was detected in relatively low abundance (<0.1 %) on all tissue types. These findings suggest a coral disease resembling WP may result from multiple etiologies.

Spatial differentiation of coral species related to wave energy along the Changqi coast, Hainan island, southern China

The regularities of the composition and the spatial distribution of hermatypic coral community is an essential aspect of coral reef ecosystem studies. The relationship between the structure and spatial distribution of hermatypic coral communities and hydrodynamics and wave energy, along the Changqi coast, are investigated. Differences in abundance of hermatypic coral species, at different depths, were found; these were related mainly to the varying influence of waves. Under average weather conditions, the wave energy was dissipated regularly at a depth of 2m. Here, the coral cover was the lowest of all of the depths. However, corals growing in that area is adapted to the conditions; therefore, wave damage was low. The areas at 5–6m water depth were influenced by waves primarily during episodes of extreme weather, with high wave energy resulting in severe damage of the corals. The coral cover in this depth was the highest observed, but the corals were generally smaller and had a short growth period. These findings indicate that the strong waves damaged particularly the weak corals, such as Acropora sp. and Montipora sp., during these short term events. Nevertheless, upon the return of normal conditions, coral communities can grow back and reproduce asexually in the damaged areas. As a result of this regrowth, Acropora sp. and Montipora sp. were highly abundant in areas at a depth of 5m. It appears that knowledge on the physical setting, i.e. the relationship between wave properties and the spatial distribution patterns of corals, is essential for understanding coral reef succession rules; likewise, protection and recovery mechanisms of the coral reef ecosystem.

Rapid Northward Spread of a Zooxanthellate Coral Enhanced by Artificial Structures and Sea Warming in the Western Mediterranean

The hermatypic coral Oculina patagonica can drive a compositional shift in shallow water benthic marine communities in the northwestern Mediterranean. Here, we analyze a long-term, large-scale observational dataset to characterize the dynamics of the species' recent northward range shift along the coast of Catalonia and examine the main factors that could have influenced this spread. The variation in the distributional range of Oculina patagonica was examined by monitoring 223 locations including natural and artificial habitats along >400 km of coastline over the last 19 years (1992–2010). Abundance of the species increased from being present in one location in 1992 to occur on 19% of the locations in 2010, and exhibited an acceleration of its spreading over time driven by the join action of neighborhood and long-distance dispersal. However, the pattern of spread diverged between artificial and natural habitats. A short lag phase and a high slope on the exponential phase characterized the temporal pattern of spread on artificial habitats in contrast to that observed on natural ones. Northward expansion has occurred at the fastest rate (22 km year−1) reported for a coral species thus far, which is sufficiently fast to cope with certain climate warming predictions. The pattern of spread suggests that this process is mediated by the interplay of (i) the availability of open space provided by artificial habitats, (ii) the seawater temperature increase with the subsequent extension of the growth period, and (iii) the particular biological features of O. patagonica (current high growth rates, early reproduction, and survival to low temperature and in polluted areas). These results are indicative of an ongoing fundamental modification of temperate shallow water assemblages, which is consistent with the predictions indicating that the Mediterranean Sea is one of the most sensitive regions to global change.

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community structure. We collected exudates from the dominant hermatypic coral holobiont Porites spp. and three dominant macroalgae (one each Ochrophyta, Rhodophyta and Chlorophyta) from reefs of Mo'orea, French Polynesia. We characterized exudates by measuring dissolved organic carbon (DOC) and fractional dissolved combined neutral sugars (DCNSs) and subsequently tracked bacterioplankton responses to each exudate over 48 h, assessing cellular growth, DOC/DCNS utilization and changes in taxonomic composition (via 16S rRNA amplicon pyrosequencing). Fleshy macroalgal exudates were enriched in the DCNS components fucose (Ochrophyta) and galactose (Rhodophyta); coral and calcareous algal exudates were enriched in total DCNS but in the same component proportions as ambient seawater. Rates of bacterioplankton growth and DOC utilization were significantly higher in algal exudate treatments than in coral exudate and control incubations with each community selectively removing different DCNS components. Coral exudates engendered the smallest shift in overall bacterioplankton community structure, maintained high diversity and enriched taxa from Alphaproteobacteria lineages containing cultured representatives with relatively few virulence factors (VFs) (Hyphomonadaceae and Erythrobacteraceae). In contrast, macroalgal exudates selected for less diverse communities heavily enriched in copiotrophic Gammaproteobacteria lineages containing cultured pathogens with increased VFs (Vibrionaceae and Pseudoalteromonadaceae). Our results demonstrate that algal exudates are enriched in DCNS components, foster rapid growth of bacterioplankton and select for bacterial populations with more potential VFs than coral exudates.

Auto- and heterotrophic responses of the coralPorites luteato large amplitude internal waves

Large amplitude internal waves (LAIW) cause frequent and severe changes in the physico-chemical environment of Andaman Sea coral reefs and are a potentially important source of disturbance for corals. To explore the coral response to LAIW, prey capture disposition and photosynthesis were investigated in relation to changes in seawater temperature, pH, flow speed and food availability in LAIW simulation studies under controlled laboratory conditions, using Porites lutea as a model organism. Although food presence stimulated polyp expansion, we found an overriding effect of low temperature (19°C) causing retraction of the coral polyps into their calices, particularly when pH was altered concomitantly. Decreases in pH alone, however, caused the expansion of the polyps. The exposure history of the colonies played a crucial role in coral responses: prior field exposure to LAIW yielded lower retraction levels than in LAIW-inexperienced corals, suggesting acclimatization. Low temperature (19°C) exposure did not seem to influence the photosynthetic performance, but LAIW-experienced corals showed higher values of maximum dark-adapted quantum yield (Fv/Fm) of photosystem II than LAIW-inexperienced controls. Collectively, these data suggest that P. lutea, the dominant hermatypic coral in the Andaman Sea, can acclimatize to extreme changes in its abiotic environment by modulating its mixotrophic nutrition, through polyp expansion and potential feeding, as well as its photosynthetic efficiency.

Circum-Tethyan carbonate platform evolution during the Palaeogene: the Prebetic platform as a test for climatically controlled facies shifts

The distribution of selected shallow-benthic biota at circum-Tethyan carbonate platforms demonstrates an excellent proxy for the impact of latitudinally controlled cooling and variations in the trophic resources during the Palaeogene. In this study, we link and compare the spatial distribution and abundance of larger benthic foraminifera and hermatypic corals of Tethyan carbonate successions with new records from the Prebetic platform in SE Spain. The succession of the Prebetic platform is dominated by larger benthic foraminifera and coralline red algae throughout the Eocene, whereas corals were not recorded until the Late Eocene. Similar biotic trends were reported from 10 selected circum-Tethyan carbonate platforms. High-resolution carbon isotopes indicate a decoupling from the global carbon cycle during the latest Eocene and Early Oligocene. Thus, a possible scenario is demonstrated by the increasing restriction of the Prebetic shelf due to the continuing convergence of the Betic domain towards Iberia during the Early Oligocene. Based on previous studies, we refined earlier established Palaeogene platform stages, which reflect the evolution of shallow-benthic communities during the transition from global greenhouse to icehouse conditions. Global cooling led to the recovery of coral communities in the northern Tethyan realm during the Bartonian (stage IV). A prominent cooling event at the Bartonian-Priabonian boundary, associated with the demise of many symbiont-bearing larger foraminifera, caused the proliferation of coral reefs in the northern Tethys and the recovery of corals in the southern Tethys (stage V). The massive temperature drop related to the Oi-1 glaciation represented the base of platform stage VI (Early Oligocene-?). After a transient platform crisis during the lowermost Oligocene, coral reefs spread throughout the Tethys and proliferated with newly emerged larger benthic foraminifera.

Coral growth-rate insensitive Sr/Ca as a robust temperature recorder at the extreme latitudinal limits of Porites

Oxygen isotope values of low-growth coral (<5 mm/yr) skeletons may reflect kinetic effects, which is problematic for sea surface temperature (SST) reconstruction. Here, we report a Sr/Ca-based SST reconstruction for a temperate Porites coral collected from Kyushu, Japan, near the northern latitudinal extent of hermatypic corals. Results indicate that Sr/Ca variations in a low-growth coral remain independent from growth rate, in contrast to the oxygen isotope ratios of the same coral.

MỘT SỐ ĐẶC ĐIỂM SINH HỌC CỦA SAN HÔ TRONG ĐIỀU KIỆN TỰ NHIÊN VÀ NUÔI GIỮ

Based on the reef building ability relying on symbiotic zooxanthellae, corals can be classified into reef building hermatypic corals and non reef building ahermatypic corals. Based on the presence or absence of outer skeleton, corals can be divided into stony corals and soft corals. For the purpose of feeding, the corals can be classified into large/long polyp stony (LPS) and small/short polyp stony (SPS) corals. All soft corals have eight tentacles on the polyps so called “Octocorallia”. Almost all the hermatypic corals are colonial, with individual polyps. The autotrophic mode of feeding is majority mode in the hermatypic corals with 50 - 95% of the energy budget from photosynthesis depending on species. However, the corals possess the ability of three hetrotrophic modes of feeding: predatory prey capture by the polyps; Sedimentary filter feeding using mucus nets and consume dissolved organic matter through cell membranes. In culture condition, the common food for corals is nauplii of Artemia salina. Besides, corals can consume processed seafood with suitable sizes. Most corals are hermaphroditic, some corals are gonochorism.Sexual and asexual reproduction is observed in corals. Competitive and defensive mechanisms of corals include rapid growth, aggressive structures, sweeper tentacles and toxic compounds. Suitable environmental parameters for corals in the wild and culture conditions: light intensity from 30 - 80% photosynthesis available ratio (PAR0), temperature 23 - 270C; pH 8 - 8.45; alkalinity 2.5 - 4meq/L (7 - 11dkH); salinity 35‰; concentrations of the mineral nutrition are similar to natural marine water (NH+4: 3.8µM/L; NO3--: 3.8µM/L; PO4--: 0.56µM/L); calcium 350 - 450ppm; strontium 8 - 10ppm; the presense of water flow providing oxygen and food transfer for corals, concurrently, sedimentation prevention and anti-fouling on surface of the corals.

MỘT SỐ ĐẶC ĐIỂM SINH HỌC CỦA SAN HÔ TRONG ĐIỀU KIỆN TỰ NHIÊN VÀ NUÔI GIỮ

Based on the reef building ability relying on symbiotic zooxanthellae, corals can be classified into reef building hermatypic corals and non reef building ahermatypic corals. Based on the presence or absence of outer skeleton, corals can be divided into stony corals and soft corals. For the purpose of feeding, the corals can be classified into large/long polyp stony (LPS) and small/short polyp stony (SPS) corals. All soft corals have eight tentacles on the polyps so called “Octocorallia”. Almost all the hermatypic corals are colonial, with individual polyps. The autotrophic mode of feeding is majority mode in the hermatypic corals with 50 - 95% of the energy budget from photosynthesis depending on species. However, the corals possess the ability of three hetrotrophic modes of feeding: predatory prey capture by the polyps; Sedimentary filter feeding using mucus nets and consume dissolved organic matter through cell membranes. In culture condition, the common food for corals is nauplii of Artemia salina. Besides, corals can consume processed seafood with suitable sizes. Most corals are hermaphroditic, some corals are gonochorism.Sexual and asexual reproduction is observed in corals. Competitive and defensive mechanisms of corals include rapid growth, aggressive structures, sweeper tentacles and toxic compounds. Suitable environmental parameters for corals in the wild and culture conditions: light intensity from 30 - 80% photosynthesis available ratio (PAR0), temperature 23 - 270C; pH 8 - 8.45; alkalinity 2.5 - 4meq/L (7 - 11dkH); salinity 35‰; concentrations of the mineral nutrition are similar to natural marine water (NH+4: 3.8µM/L; NO3--: 3.8µM/L; PO4--: 0.56µM/L); calcium 350 - 450ppm; strontium 8 - 10ppm; the presense of water flow providing oxygen and food transfer for corals, concurrently, sedimentation prevention and anti-fouling on surface of the corals.

Carbonate clumped isotope variability in shallow water corals: Temperature dependence and growth-related vital effects

Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (Δ47) is a novel paleotemperature proxy based on the temperature dependent “clumping” of 13C–18O bonds. Similar Δ47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures from expected values in the winter growth of a hermatypic coral provided early evidence for possible Δ47 vital effects. Here, we present the first systematic survey of Δ47 in shallow water corals. Sub-annual Red Sea Δ47 in two Porites corals shows a temperature dependence similar to inorganic precipitation experiments, but with a systematic offset toward higher Δ47 values that consistently underestimate temperature by ∼8°C. Additional analyses of Porites, Siderastrea, Astrangia and Caryophyllia corals argue against a number of potential mechanisms as the leading cause for this apparent Δ47 vital effect including: salinity, organic matter contamination, alteration during sampling, the presence or absence of symbionts, and interlaboratory differences in analytical protocols. However, intra- and inter-coral comparisons suggest that the deviation from expected Δ47 increases with calcification rate. Theoretical calculations suggest this apparent link with calcification rate is inconsistent with pH-dependent changes in dissolved inorganic carbon speciation and with kinetic effects associated with CO2 diffusion into the calcifying space. However, the link with calcification rate may be related to fractionation during the hydration/hydroxylation of CO2 within the calcifying space. Although the vital effects we describe will complicate the interpretation of Δ47 as a paleothermometer in shallow water corals, it may still be a valuable paleoclimate proxy, particularly when applied as part of a multi-proxy approach.