Reef-forming Corals Research Articles

Analysis on variation trend of coral reef in Xisha

Xisha Islands, located in the northern part of South China Sea, consist of more than 20 islands and atolls. The coral reef of Xisha Islands belongs to the typical ocean distribution of world’s coral reefs, its ecosystem is the most typical in our country and hermatypic coral species are about three-quarters of the total coral species in China. It is addressed with the oldest coral reef community which of the most original and valuable in China. The previous research shows that the islands studded in South China Sea such as Xisha Islands have important influence on the formation of coral reefs along the mainland coast by multiplying and migrating from south to the north. It is supplementary sources of coastal coral larvae in Hainan and Guangdong. Therefore, carrying out the monitoring of coral reef community ecosystem is of great significance to the ecological protection. By the Manta tow and the Line Intercept Transect method, five stations (Xisha Yong xing dao, Shi dao, Xisha zhou, Zhao Shu dao and Bei dao) on Xisha ecological monitoring area were monitored continually from 2005 to 2009. We compared the index changes of Hermatypic coral’s species, coverage and recruitment, and combining with Condition Index, Succession Index, and the variation trend of hard coral in Xisha were analyzed. The results show that, from 2005 to 2009, the coverage of living hermatypic corals in ecological monitoring area is sharply reduced from 68.19% to 7.93%, while the dead coral coverage is sharply increased from 4.70% to 72.90%. Coral recruitment is reduced from 1.18 ind/100 m 2 to 0.07 ind/100 m 2, hermatypic coral species decreased from 87 to 35. In 2005, the health of coral reefs was very good, and the Condition Index was 1.097. However, the Condition Index cut down to a very low degree in 2009. It was only −0.880. The Succession Index belonged to “very low degree” from 2005 to 2009, and the numerical value was gradually reduce from −0.984 to −1.876. As a whole, hermatypic corals are serious degrade regionally and caused great change to the coral structure and biodiversity, this will lead to a continuous degradation of coral reefs.

Apoptosis and the selective survival of host animals following thermal bleaching in zooxanthellate corals

During the past several decades, numerous reports from disparate geographical areas have documented an increased frequency of "bleaching" in reef-forming corals. The phenomenon, triggered by increased sea surface temperatures, occurs when the cnidarian hosts digest and/or expel their intracellular, photosynthetic dinoflagellate symbionts ("zooxanthellae" in the genus Symbiodinium). Although coral bleaching is often followed by the death of the animal hosts, in some cases, the animal survives and can be repopulated with viable zooxanthellae. The physiological factors determining the ability of the coral to survive bleaching events are poorly understood. In this study, we experimentally established that bleaching and death of the host animal involve a caspase-mediated apoptotic cascade induced by reactive oxygen species produced primarily by the algal symbionts. In addition, we demonstrate that, although some corals naturally suppress caspase activity and significantly reduce caspase concentration under high temperatures as a mechanism to prevent colony death from apoptosis, even sensitive corals can be prevented from dying by application of exogenous inhibitors of caspases. Our results indicate that variability in response to thermal stress in corals is determined by a four-element, combinatorial genetic matrix intrinsic to the specific symbiotic association. Based on our experimental data, we present a working model in which the phenotypic expression of this symbiont/host relationship places a selective pressure on the symbiotic association. The model predicts the survival of the host animals in which the caspase-mediated apoptotic cascade is down-regulated.

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Chapter 6: Archaeological Excavations

During September and October 1996, we completed the first archaeological excavations done in the Aitape area on the Sepik coast. The ceramic finds from our excavations on hillcrests at Aitape (which are an uplifted Pliocene/Miocene coral reef formation) suggest that human occupation in this part of the coast dates back at least to the mid-first millennium AD when Sumalo Ware (Chapters 7 and 14) was being locally made. Additionally, our excavations on Tumleo Island recovered sufficient ceramic evidence in stratigraphic position to reconstruct a fairly definitive pottery sequence for this part of New Guinea covering the last 1,500–2,000 years.

Acquisition and assimilation of carbon in non-bleached and bleached corals

Reef-forming corals cycle carbon (C) between the coral host, their endosymbiotic algae, and their skeleton. At elevated sea-surface temperatures this relationship breaks down and the corals bleach by expelling their endosymbiotic algae or these algae lose their photosynthetic pigments. The effect of thermally induced bleaching on the C cycling of 2 ecologically important coral species was investigated. The acquisition and assimilation of photoautotrophically and heterotrophically acquired C was examined via pulse-chase labeling experiments in thermally bleached and non- bleached Montipora capitata and Porites compressa corals. In non-bleached corals photoautotrophic and heterotrophic C were acquired and assimilated very differently. Namely, photoautotrophically acquired C was used to meet short-term metabolic demands and calcification, whereas heterotroph- ically acquired C was retained in both the coral host and endosymbiotic algae. In bleached corals there was a dramatic reduction in the assimilation of photoautotrophically acquired C by the endosymbiotic algae, in the translocation of C from the algae to the coral host, and in the C assimi- lated in the skeleton. The level of heterotrophically acquired C assimilated into bleached corals was similar to that in non-bleached corals, and was a direct source of organic C to the endosymbiotic algae. This host-to-endosymbiotic algal supply of heterotrophic C may stimulate endosymbiotic algal recovery. These findings show the importance of both photoautotrophic and heterotrophic C to coral function and demonstrate that both play a crucial role in the recovery from bleaching.

Crustose coralline algal diseases in the U.S.-Affiliated Pacific Islands

Despite the critical role of crustose coralline algae (CCA) in coral reef formation, maintenance, and ecology, little is known about coralline algal disease abundance, distribution, etiology, or the potential implications of declining CCA flora. This paper presents the first quantitative study of CCA disease on U.S. Pacific coral reefs, based on Rapid Ecological Assessments conducted at 337 discrete sites, at 42 different U.S.-Affiliated Pacific Islands and Atolls, within 5 major geographical regions: main Hawaiian Islands, Northwestern Hawaiian Islands, American Samoa, the Pacific Remote Island Areas (PRIA), and Guam and the Commonwealth of the Northern Mariana Islands (CNMI). Five major disease categories were enumerated, and a disease occurrence index was estimated, based on case counts relative to percent CCA cover. CCA disease occurrence exhibited considerable spatial variability both between and within islands/atolls, with some regions being disproportionately affected by disease. No diseases were observed at remote Johnston and Wake Atolls, or the main Hawaiian Islands. Diseases were rare in the Northwestern Hawaiian Islands and the Northern Mariana Islands; occasional to common around the PRIA, and common to abundant in American Samoa, Guam, and the Southern Mariana Islands. Pacific-wide, disease occurrence was statistically associated with CCA percent cover and sea surface temperatures (SSTs) but not with human population density; nonetheless, disease occurrence and population density were statistically correlated for those islands containing disease. Although Pacific-wide, the occurrence of disease was low, with no active outbreaks detected in any region, hot spots of disease were detected around Guam, the southern CNMI, American Samoa, and the PRIA. The high levels of spatial and temporal variability in disease occurrence herein underscore the patchy nature and fluctuating distribution dynamics of these afflictions. Also, the widespread dispersal capabilities and extraordinary infective properties of some of these pathogens highlight the importance of better understanding CCA disease dynamics and discerning the relative threat levels on coral reef ecosystems.

Early post-settlement mortality and the structure of coral assemblages

Events occurring early in life history can have profound effects on the structure of populations and communities. In particular, susceptibility to predation is often highest early in life, and can greatly influence community structure. To better understand these events in reef-forming coral communities, we investigated how spatial variation in recruitment and early post-settlement predation influenced the spatial structure of a coral assemblage. Over a 5 yr period, we compared recruitment of corals and abundance of juveniles and adults at a combination of 3 locations and 3 depths in French Polynesia. We then measured mortality of recruits (<3 mo old) and juveniles (about 1 to 4 yr old), and abundance of potential predators. Results demonstrate the crucial role of events occurring in the first weeks of the benthic stage. The abundance of scraping herbivorous parrotfishes explained substantial spatial variation in the mortality of recruits, but not juveniles, revealing a likely effect of incidental removal by grazing. Conversely, abundance of coral-feeding butterflyfishes explained substantial spatial variation in the mortality of juveniles. These findings underscore the importance of incidental mortality from grazing and specialized corallivory on coral populations. Moreover, these processes can play a key role in determining spatial patterns in coral assemblage structure.

Seismic detection of CO 2 leakage along monitoring wellbores

A pilot carbon dioxide (CO 2) sequestration experiment was carried out in the Michigan Basin in which ∼10,000 tonnes of supercritical CO 2 was injected into the Bass Island Dolomite (BILD) at 1050 m depth. A passive seismic monitoring (PSM) network was operated before, during and after the ∼17-day injection period. The seismic monitoring network consisted of two arrays of eight, three-component sensors, deployed in two monitoring wells at only a few hundred meters from the injection point. 225 microseismic events were detected by the arrays. Of these, only one event was clearly an injection-induced microearthquake. It occurred during injection, approximately 100 m above the BILD formation. No events, down to the magnitude −3 detection limit, occurred within the BILD formation during the injection. The observed seismic waveforms associated with the other 224 events were quite unusual in that they appear to contain dominantly compressional (P) but no (or extremely weak) shear (S) waves, indicating that they are not associated with shear slip on faults. The microseismic events were unusual in two other ways. First, almost all of the events occurred prior to the start of injection into the BILD formation. Second, hypocenters of the 94 locatable events cluster around the wells where the sensor arrays were deployed, not the injection well. While the temporal evolution of these events shows no correlation with the BILD injection, they do correlate with CO 2 injection for enhanced oil recovery (EOR) into the 1670 m deep Coral Reef formation that had been going on for ∼2.5 years prior to the pilot injection experiment into the BILD formation. We conclude that the unusual microseismic events reflect degassing processes associated with leakage up and around the monitoring wells from the EOR-related CO 2 injection into the Coral Reef formation, ∼700 m below the depth of the monitoring arrays. This conclusion is also supported by the observation that as soon as injection into the Coral Reef formation resumed at the conclusion of the BILD demonstration experiment, seismic events (essentially identical to the events associated with the Coral Reef injection prior to the BILD experiment) again started to occur close to a monitoring arrays. Taken together, these observations point to vertical migration around the casings of the monitoring wellbores. Detection of these unusual microseismic events was somewhat fortuitous in that the arrays were deployed at the depth where the CO 2 undergoes a strong volume increase during transition from a supercritical state to a gas. Given the large number of pre-existing wellbores that exist in depleted oil and gas reservoirs that might be considered for CO 2 sequestration projects, passive seismic monitoring systems could be deployed at appropriate depths to systematically detect and monitor leakage along them.

Cold seep carbonates and associated cold-water corals at the Hikurangi Margin, New Zealand: New insights into fluid pathways, growth structures and geochronology

The aim of this study is to provide combined new insights into the geochronological framework, isotope geochemical signatures and structural observations of methane related authigenic carbonate settings and associated cold-water corals from offshore New Zealand. The analysed samples are obtained from calcified sediments of three different cold seep areas at the Hikurangi Margin: Opouawe Bank, Uruti and Omakere Ridge. We focused the sub-sampling on aragonitic precipitates in vein like structures, partly still open fluid channel systems and related chemoherm structures in order to identify the timing and signature of focused marine methane emanation. The presented initial U/Th age data set indicates different generations of intensified seep activity and related carbonate precipitation between 12,400 ± 160 and 2090 ± 850 years BP. The youngest stage so far, was identified as contemporaneous cold seep activity at the southernmost (North Tower, Opouawe Bank) and northernmost (Bear's Paw, Omakere Ridge) sampling sites around 2300 years BP. Sharing the same water depth (1050 to 1100 m) these sites imply regional margin-wide tectonic or hydrological changes as controlling process. An intermediate phase of vein and channel structures within the sediment was detected for a time interval between approximately 5000 and 4000 years BP with contemporaneous settings of focused seep activity around 4300 years BP at Uruti Ridge (LM-10) and Opouawe Bank. δ 13C PDB data reflect site and carbonate type specific signatures, clustering around − 52‰ (Uruti and Omakere Ridge) and − 47‰ for the fluid pathway system and the uppermost surface at North Tower site (Opouawe Bank). Late stage precipitates in chemoherm cavities of the latter reflect significantly heavier values of about − 38‰. Porous precipitates within open fluid channel systems are characterized by decreased δ 234U ( T ) values, exceptional high Th and U concentrations and slightly lighter δ 13C PDB signatures when compared to adjacent rim-like and dense cements. This specific kind of precipitate is interpreted as indicator for phases of less vigorous fluid seepage. The observed occurrence of cold-water corals seems to be mostly depending on the abundance of authigenic carbonates as a substrate exposed to erosive bottom water currents. But, seafloor observations combined with preliminary age data indicate a significant time gap between the inferred end of cold seep activity and coral colonization. U–Th analyses of recent reef-forming coral provided an initial δ 234U (0) value of 146.3 ± 3.9‰ and 0.0013 ± 0.0002 as starting 230Th/ 234U activity ratio for coral growth in the bottom water.

Historical macrobenthic community assemblages in the Avilés Canyon, N Iberian Shelf: Baseline biodiversity information for a marine protected area

Deep-sea ecosystems are highly diverse, and European countries seek to protect these environments by identifying conservation targets. One of these is the Avilés Canyon, southern Bay of Biscay, NE Atlantic, Spain. We present the first analysis of historical benthic communities (1987–1988) of this canyon ecosystem, which is a valuable source of biodiversity baseline information. We found 810 taxa divided in five main macrobenthic assemblages, showing a highly diverse benthic community. Bathymetry was the major structuring agent of benthic community, separating shallow (assemblages I and II, 31 to 307 m depth) from deep stations (assemblages III, IV and V, 198 to 1400 m depth). Especially diverse was assemblage IV, located at the easternmost part of the continental slope (378–1100 m depth) where we found reef-forming corals Lophelia pertusa and Madrepora oculata. These and other communities (sea-pens [Order Pennatulacea, Phylum Cnidaria] and burrowing macrofauna) represent key habitats in NE Atlantic continental slopes, which are currently threatened. The present dataset has produced the most comprehensive assessment of diversity in this area to date, focusing on the taxonomic groups which may best reflect the health of the marine ecosystem and supporting previous studies which indicate that the continental slope of the southern Bay of Biscay hosts key benthic habitats.

Functionally diverse reef-fish communities ameliorate coral disease.

Coral reefs, the most diverse of marine ecosystems, currently experience unprecedented levels of degradation. Diseases are now recognized as a major cause of mortality in reef-forming corals and are complicit in phase shifts of reef ecosystems to algal-dominated states worldwide. Even so, factors contributing to disease occurrence, spread, and impact remain poorly understood. Ecosystem resilience has been linked to the conservation of functional diversity, whereas overfishing reduces functional diversity through cascading, top-down effects. Hence, we tested the hypothesis that reefs with trophically diverse reef fish communities have less coral disease than overfished reefs. We surveyed reefs across the central Philippines, including well-managed marine protected areas (MPAs), and found that disease prevalence was significantly negatively correlated with fish taxonomic diversity. Further, MPAs had significantly higher fish diversity and less disease than unprotected areas. We subsequently investigated potential links between coral disease and the trophic components of fish diversity, finding that only the density of coral-feeding chaetodontid butterflyfishes, seldom targeted by fishers, was positively associated with disease prevalence. These previously uncharacterized results are supported by a second large-scale dataset from the Great Barrier Reef. We hypothesize that members of the charismatic reef-fish family Chaetodontidae are major vectors of coral disease by virtue of their trophic specialization on hard corals and their ecological release in overfished areas, particularly outside MPAs.

Danian cool-water coral reefs in southern Scandinavia localised over seafloor highs

Danian (Paleocene) reefs formed by ahermatypic scleractinian corals in relatively deep water are known in a few localities in southern Scandinavia. Reflection and shallow seismic profiles, and samples from drilling and scuba diving in bridge pier excavations in Øresund, the strait between Denmark and Sweden, for the first time allow interpretation of the factors that controlled the localisation of the reefs. After the mass-extinction at the K/T boundary, reef-building scleractinian corals were absent in the Boreal early Danian in the Danish basin. Faunal evolution after the biotic crisis and a rise in relative sea level are interpreted to have favoured formation of deep-water coral reefs in the Øresund region in mid-Danian time. The reefs were 6–20 m high and 20–200 m long on the seafloor and have a patchy distribution within a bryozoan mound-dominated setting in an area of about 10 km 2. They are composed of the framework-building ahermatypic scleractinian coral Dendrophyllia candelabrum with minor occurrences of bryozoans, echinoderms, gastropods and bivalves. It has been suspected that the reefs were located over contemporaneous seafloor highs but this notion was only based on comparison with similar modern deep-water reefs offshore Norway. The data from Øresund indicate that the Danian reef complex was formed over a late Maastrichtian palaeo-seafloor high, the Saltholm-Malmø High, supporting this interpretation and thus adding fundamentally to the understanding of the factors controlling the formation and localisation of these deep and cool-water coral reefs. Individual reefs were initiated and grew on eroded crests and steep south-dipping flanks of bryozoan mounds and were predominantly situated on the southern part of the high and are interpreted as growing towards NW-flowing bottom currents rich in particulate nutrients.

Stable isotope constraints on Holocene carbon cycle changes from an Antarctic ice core

Reconstructions of atmospheric CO(2) concentrations based on Antarctic ice cores reveal significant changes during the Holocene epoch, but the processes responsible for these changes in CO(2) concentrations have not been unambiguously identified. Distinct characteristics in the carbon isotope signatures of the major carbon reservoirs (ocean, biosphere, sediments and atmosphere) constrain variations in the CO(2) fluxes between those reservoirs. Here we present a highly resolved atmospheric delta(13)C record for the past 11,000 years from measurements on atmospheric CO(2) trapped in an Antarctic ice core. From mass-balance inverse model calculations performed with a simplified carbon cycle model, we show that the decrease in atmospheric CO(2) of about 5 parts per million by volume (p.p.m.v.). The increase in delta(13)C of about 0.25 per thousand during the early Holocene is most probably the result of a combination of carbon uptake of about 290 gigatonnes of carbon by the land biosphere and carbon release from the ocean in response to carbonate compensation of the terrestrial uptake during the termination of the last ice age. The 20 p.p.m.v. increase of atmospheric CO(2) and the small decrease in delta(13)C of about 0.05 per thousand during the later Holocene can mostly be explained by contributions from carbonate compensation of earlier land-biosphere uptake and coral reef formation, with only a minor contribution from a small decrease of the land-biosphere carbon inventory.

Hydrology, plankton, and corals of the Maracajaú reefs (Northeastern Brazil): an ecosystem under severe thermal stress

This study provides baseline information on the hydrological conditions and on the coral and plankton communities at the Maracajaú reef ecosystem (Northeastern Brazil). Studies were performed from February to June 2000, covering the transition from dry to rainy season. In this area, there is an offshore coral reef formation, where corals were observed in loco; the water samples were collected to obtain the hydrological and plankton data. Six scleractinian species were identified. Stable isotope analysis on the carbonate fraction of Favia gravida fragments showed that these corals were under severe thermal stress. Chlorophyll-a varied from 1.1 to 9.3 mg m-3, with higher values during the rainy season. Average zooplankton wet weight biomass were 117.0 (microzooplankton) and 15.7 mg m -3(mesozooplankton). A total of 136 Phytoplankton and 61 zooplankton taxa were identified. Seasonal forcing determined the phyto-micro-and mesozooplankton community structure, rather than the coastal-offshore gradient.

Benthic marine algae of the coral reefs of Brazil: a literature review

In Brazil, algae in coral reef environments can be found from Maranhao to Bahia State and there are today around 700 taxa, of which 78% are found on reef formations. The Rhodophyta are among the most common taxa found. Corallinales are the least studied group, in spite of their role in the formation and maintenance of Brazilian coral reefs. The species richness of algae on coral reefs is low in comparison with other coastal habitats, but there is an abundance of turf and fleshy macroalgae on certain parts of the coastal reefs. Halimeda spp., Dictyota spp., Dictyopteris spp., Hypnea spp., Gracilaria spp., Gelidium spp. and Sargassum spp. are some of the most conspicuous algae, while Caulerpa and Udotea and seagrasses are frequently found on unconsolidated sandy bottoms. Benthic marine algae are important components of shallow coral-reef communities in the Atlantic and they can be regarded as major competitors to corals. Over the last two decades, numerous cases of phase shifts from coral to algal predominance over coral reefs were reported worldwide. These reports coincide with the increasing concern with reef degradation, mainly attributed to anthropogenic nutrient enrichment and overfishing. In Brazil the effects of nutrification over coral reef dynamics are only recently being assessed, and crucial basic information is still lacking. The exploitation of marine algae, mainly of Gracilaria, is also recent in Brazil. Macroalgae growth in some disturbed Brazilian reefs were associated with grazing reduction caused by overfishing or nutrification. Rapid assessments of coral reef flora are needed in order to generate reliable information for environmental

Functional diversity in coral-dinoflagellate symbiosis.

Symbioses are widespread in nature and occur along a continuum from parasitism to mutualism. Coral-dinoflagellate symbioses are defined as mutualistic because both partners receive benefit from the association via the exchange of nutrients. This successful interaction underpins the growth and formation of coral reefs. The symbiotic dinoflagellate genus Symbiodinium is genetically diverse containing eight divergent lineages (clades A-H). Corals predominantly associate with clade C Symbiodinium and to a lesser extent with clades A, B, D, F, and G. Variation in the function and interactive physiology of different coral-dinoflagellate assemblages is virtually unexplored but is an important consideration when developing the contextual framework of factors that contribute to coral reef resilience. In this study, we present evidence that clade A Symbiodinium are functionally less beneficial to corals than the dominant clade C Symbiodinium and may represent parasitic rather than mutualistic symbionts. Our hypothesis is supported by (i) a significant correlation between the presence of Symbiodinium clade A and health-compromised coral; (ii) a phylogeny and genetic diversity within Symbiodinium that suggests a different evolutionary trajectory for clade A compared with the other dominant Symbiodinium lineages; and (iii) a significantly lower amount of carbon fixed and released by clade A in the presence of a coral synthetic host factor as compared with the dominant coral symbiont lineage, clade C. Collectively, these data suggest that along the symbiotic continuum the interaction between clade A Symbiodinium and corals may be closer to parasitism than mutualism.

A geochemical model for coral reef formation

The conspicuous growth of a reef crest and the resulting differentiation of reef topography into a moat (shallow lagoon), crest and slope have long attracted the interest of scientists studying coral reefs. A geochemical model is here proposed for reef formation, taking into account diffusion-limited and light-enhanced calcification. First, to obtain data on net photosynthesis and calcification rates in the field, a typical coral community was cultured in situ on a reef flat. Using these data, equations including parameters for calcification were then developed and applied in computer simulations to model the development over time of reef profiles and the diffusion of carbon species. The reef topography simulated by the model was in general agreement with reef topography observed in nature. The process of reef growth as shown by the modeling was as follows. Increases in the shore-to-offshore gradients of the concentrations of carbonate species result from calcification by reef biota, giving a lower rate of growth on near-shore parts of the reef than on those further offshore. As a result, original topography is diversified into moat and reef crest for the first time. Reef growth on the reef crest is more rapid than in the inshore moat area, because more light is available at the crest. Reef growth on the near-shore side of the reef is further inhibited by damming of carbon-rich seawater on the seaward side of the reef by the reef crest. Over time, the topographic expression of the reef crest and moat becomes progressively more clearly defined by these geochemical processes.

Chemical warfare on coral reefs: Sponge metabolites differentially affect coral symbiosis in situ

Coral reef ecosystems are characterized by high species diversity and intense levels of biotic interaction, particularly competition for space among sessile benthic invertebrates. Using in situ pulse amplitude modulated fluorometry, we demonstrate that secondary metabolites present in the tissues of some Caribbean sponge species have rapid allelopathic effects on the symbiotic algae (zooxanthellae) that live in coral tissues and provide the energy for coral growth and reef formation. When incorporated into stable gels at natural concentrations and placed in contact with brain coral heads on shallow reefs for ~18 h, secondary metabolites of some sponge species caused a decrease in the photosynthetic potential of the symbiotic algae and bleaching of the coral tissue, whereas those of others interfered with algal photosynthesis without causing bleaching. Some sponges produce metabolites with different modes of action for competing with reef corals.

First Mesozoic record of the scleractinian Madrepora from the Maastrichtian siliceous limestones of Poland

The objective of the present article is to document the first stratigraphic occurrence of the colonial oculinid Madrepora, known from the modern seas as an azooxanthellate taxon that contributes to the formation of deep-water coral reefs. The Upper Cretaceous specimens of Madrepora sp. reported herein from Poland were recovered from Upper Maastrichtian (Nasilow and Bochotnica localities) and Lower Maastrichtian (Blizow locality) siliceous limestones. The corals are preserved as imprints of the branch fragments and molds of the calices. Despite their moldic preservation, the coral remains exhibit key generic features of the genus Madrepora; including (1) sympodial colony growth form with calices arranged in opposite and alternating rows in one plane of the branch, and (2) imprints of the granular coenosteum texture, occasionally showing peculiar reticulate patterns. Some features of the Cretaceous Madrepora sp., such as the reticulate coenosteum texture, the range of the corallite diameter (2.8–4 mm), and the arrangement of the septa in three regular cycles resemble the skeletal features of the modern, typically constructional, species M. oculata (type species). The lack of any evidence of coral buildups and related debris in the whole Upper Cretaceous/Paleogene sequences from Poland and the sparse occurrence of colony fragments, suggests that the Cretaceous Madrepora sp. formed small, isolated colonies.

Quenching of superoxide radicals by green fluorescent protein

Green fluorescent proteins (GFP) are widely used in vivo molecular markers. These proteins are particularly resistant, and maintain function, under a variety of cellular conditions such as pH extremes and elevated temperatures. Green fluorescent proteins are also abundant in several groups of marine invertebrates including reef-forming corals. While molecular oxygen is required for the post-translational maturation of the protein, mature GFPs are found in corals where hyperoxia and reactive oxygen species (ROS) occur due to the photosynthetic activity of algal symbionts. In vitro spin trapping electron paramagnetic resonance and spectrophotometric assays of superoxide dismutase (SOD)-like enzyme activity show that wild type GFP from the hydromedusa, Aequorea victoria, quenches superoxide radicals (O 2 − ) and exhibits SOD-like activity by competing with cytochrome c for reaction with O 2 − . When exposed to high amounts of O 2 − the SOD-like activity and protein structure of GFP are altered without significant changes to the fluorescent properties of the protein. Because of the distribution of fluorescent proteins in both the epithelial and gastrodermal cells of reef-forming corals we propose that GFP, and possibly other fluorescent proteins, can provide supplementary antioxidant protection.