Seasonal growth bands in Famennian rugose coral Scruttonia kunthi and their environmental significance

Large colonies of rugose coral Scruttonia kunthi occurring in the upper Famennian of Sudetes (southern Poland) reveal distinct growth banding in their skeletons. They were investigated for internal structural characteristics and stable isotopic composition. The skeletal tissue consists of alternating light and dark bands which differ in thickness, density and morphology of structural elements, and in occurrence of corallite contraction and rejuvenescense. Darker parts with densely arranged thick skeletal elements are thin in comparison to lighter parts. In addition, they include frequently offsets and contraction of corallites. A couplet of dense and less dense bands is interpreted to represent most probably an annual cycle. The calculated growth rate for Scruttonia kunthi varied from 6 mm/yr to 12 mm/yr. Growth-band formation was influenced environmentally. Oxygen isotopic data provide an evidence that high-density bands were formed in the season of higher environmental stress, with relatively warmer temperatures and higher sedimentation rates. Carbon isotopic signatures are very uniform, and thus enigmatic. They indicate that at least growth rate of the skeleton and seawater temperature had no influence on the coral δ¹³C.     

Palaeoecological and sedimentological characteristics of the Lower Tortonian scleractinian reef corals of Gavdos Island,southern Greece

Early Late Miocene coral assemblages from five outcrops of Gavdos Island, Southern Greece, are investigated with respect to their palaeoecological implications. Small patch reefs with Porites assemblage are a common feature of the low-diversity coral occurrences. The determined hermatypic colonies indicate a nearshore palaeoecosystem prevailing in a tropical to subtropical coastal sea at depths ranging from 5 to 50 m with an average temperature of 22–26 °C. Microfacially, the studied Scleractinian patch reefs are represented by Coral Framestones-Floatstones. The reefal facies has been affected by syndepositional processes (boring activities-micritization), as well as by post-depositional diagenesis in the meteoric realm (dissolution, cementation and intense pedogenesis). The palaeoecological and sedimentological analysis indicates a restricted to open-marine inner platform setting of moderate to high energy, possibly of ramp-type (inner-mid ramp). Coral reef growth took place mainly during stages of accommodation (i.e., transgressive episode, cycle 3.1 of Vail curve) and of relatively low siliciclastic input.     

Competition between scleractinian corals and macroalgae: An experimental investigation of coral growth, survival and reproduction

Macroalgae are a major component of many coral reef flat communities, and are potentially major competitors with corals. The influence of macroalgae on several demographic parameters of four species of scleractinian coral by means of an algal clearance experiment was examined to determine specifically if macroalgae are affecting coral cover, growth, fecundity, fission, survivorship and recruitment. Also investigated were patterns of natural encounters between corals and algae.

Algal cover at the study site ranged from 41 to 56%, and coral cover from 8 to 10%. In total, 92 ± 4 ( )% of coral colonies were in contact with one or more species of macroalgae. Changes in coral cover were significantly affected by the presence of macroalgae, with cover of Acropora species increasing faster in areas from which algae had been cleared compared to control areas where algae had not been removed, although this pattern did not occur for Pocillopora damicornis (Linnaeus). Similarly, growth of individual colonies was faster when macroalgae were absent for three Acropora species but not for P. damicornis. There were no differences detected in rates of fission or survivorship of corals between algal clearance and control treatments, although there were high levels of variability in both of these parameters. Fecundity of Acropora palifera (Lamarck), the only species examined, was approximately double in colonies in cleared plots compared to those in control plots with macroalgae present. As no recruitment occurred throughout the 2-yr study, it remains to be determined how macroalgae effect the settlement of coral larvae. The results show that macroalgae can have a major influence on the demography of scleractinian corals.     

Local and regional scale recovery of Diadema promotes recruitment of scleractinian corals

The phase change from coral to macroalgal dominance on many Caribbean reefs was exacerbated by the mortality of the echinoid Diadema antillarum in 1983–1984, and until recently, this sea urchin has remained rare on reefs throughout the western Atlantic. By the late 1990s, Diadema started to reappear in large numbers on some Jamaican reefs, and by 2000, the high densities were correlated with significantly greater abundances of juvenile corals. Here, we show that dense populations of Diadema now occur over a multi-kilometre-wide scale at six locations scattered along a 4100 km arc across the entire Caribbean. In all cases, these dense populations are found in shallow water (< 6 m depth) on outer reef communities and are associated with reduced macroalgal cover and enhanced coral recruitment. We conclude that population recovery of Diadema is occurring at both local and regional scales, and that grazing by this echinoid is creating conditions favouring the recruitment of corals.     

Post-settlement mortality and growth of newly settled reef corals in a subtropical environment

There are few studies of post-settlement mortality of newly settled corals, particularly on subtropical reefs. This study examined the mortality and growth of spat of three broadcast spawning coral species at the Solitary Islands, eastern Australia (30°S). Mortality of spat was high, with only 0.2–2.8% surviving their first year of life. Growth was slow, with coral spat achieving a maximum diameter of 2 mm after 8 months. High post-settlement mortality and slow growth rates are likely to contribute to low rates of recruitment of broadcast spawning species at the Solitary Islands.     

Molecular diversity of symbiotic algae (zooxanthellae) in scleractinian corals of Kenya

In this first sequence analysis of ‘zooxanthellae’ (symbiotic algae of the genus Symbiodinium) in scleractinian corals in Africa, seven Kenyan species sampled in 2001–2002 were analysed by RFLP and sequencing of a PCR-amplified fragment of the LSU rRNA gene. Zooxanthellae of phylotypes A, C and D, all described previously in corals from other regions of the world, were detected. All sequences of phylotype D were identical, while phylotype C was variable, with 14 distinct sequences, seven of which clustered in a previously unreported subgroup of phylotype C, among the 22 samples. These data on the diversity of zooxanthellae in Kenyan corals 3–4 years after the 1998 bleaching event are of potential value for longitudinal studies of temporal changes in zooxanthella diversity in Kenyan corals, especially in relation to future large-scale bleaching episodes.     

Carbonate production by scleractinian corals at Aqaba,Gulf of Aqaba,Red Sea

Summary In a fringing reef at Aqaba at the northern end of the Gulf of Aqaba (29°26′N) growth rates, density, and the calcification rate ofPorites were investigated in order to establish calculations of gross carbonate production for the reefs in this area. Colony accretion ofPorites decreases with depth as a function of decreasing growth rates. The calcification rate ofPorites is highest in shallow water (0–5 m depth) with 0.9 g·cm⁻²·yr⁻¹ and falls down to 0.5 g·cm⁻²·yr⁻¹ below 30 m. Scleractinian coral gross production is calculated from potential productivity and coral coverage. It is mainly dependent on living coral cover and to a lesser extent on potential productivity. Total carbonate production on the reef ranged from 0 to 2.7 kg/m² per year, with a reef-wide average of 1.6 kg/m² perycar. Maximum gross carbonate production by corals at Aqaba occurs at the reef crest and in the middle fore-reef from 10 to 15 m water depth. Production is low in sandy reef parts. Below 30 m depth values still reach ca. 50% of shallow water values. Mean potential production of colonies and gross carbonate production of the whole reef community at Aqaba is lower than in tropical reefs. However, carbonate production is higher than in reef areas at the same latitude in the Pacific, indicating a northward shift of reef production in the Red Sea.     

Environmental implications of skeletal micro-density and porosity variation in two scleractinian corals

The correlations between skeletal parameters (bulk density, micro-density and porosity), coral age and sea surface temperature were assessed along a latitudinal gradient in the zooxanthellate coral Balanophyllia europaea and in the azooxanthellate coral Leptopsammia pruvoti. In both coral species, the variation of bulk density was more influenced by the variation of porosity than of micro-density. With increasing polyp age, B. europaea formed denser and less porous skeletons while L. pruvoti showed the opposite trend, becoming less dense and more porous. B. europaea skeletons were generally less porous (more dense) than those of L. pruvoti, probably as a consequence of the different habitats colonized by the two species. Increasing temperature had a negative impact on the zooxanthellate species, leading to an increase of porosity. In contrast, micro-density increased with temperature in the azooxanthellate species. It is hypothesized that the increase in porosity with increasing temperatures observed in B. europaea could depend on an attenuation of calcification due to an inhibition of the photosynthetic process at elevated temperatures, while the azooxanthellate species appears more resistant to variations of temperature, highlighting possible differences in the sensitivity/tolerance of these two coral species to temperature changes in face of global climate change.     

Differential susceptibility to oxidative stress of two scleractinian corals: antioxidant functioning of mycosporine-glycine

This study examined the importance of mycosporine-glycine (Myc-Gly) as a functional antioxidant in the thermal-stress susceptibility of two scleractinian corals, Platygyra ryukyuensis and Stylophora pistillata. Photochemical efficiency of PSII (F_v/F_m), activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and composition and abundance of mycosporine-like amino acids (MAAs) in the coral tissue and in symbiotic zooxanthellae were analyzed during 12-h exposure to high temperature (33 °C). After 6- and 12-h exposures at 33 °C, S. pistillata showed a significantly more pronounced decline in F_v/F_m compared to P. ryukyuensis. A 6-h exposure at 33 °C induced a significant increase in the activities of SOD and CAT in both host and zooxanthellae components of S. pistillata while in P. ryukyuensis a significant increase was observed only in the CAT activity of zooxanthellae. After 12-h exposure, the SOD activity of P. ryukyuensis was unaffected in the coral tissue but slightly increased in zooxanthellae, whereas the CAT activity in the coral tissue showed a 2.5-fold increase. The total activity of antioxidant enzymes was significantly higher in S. pistillata than in P. ryukyuensis, suggesting that P. ryukyuensis is less sensitive to oxidative stress than S. pistillata. This differential susceptibility of the corals is consistent with a 20-fold higher initial concentration of Myc-Gly in P. ryukyuensis compared to S. pistillata. In the coral tissue and zooxanthellae of both species investigated, the first 6 h of exposure to thermal stress induced a pronounced reduction in the abundance of Myc-Gly but not in other MAAs. When exposure was prolonged to 12 h, the Myc-Gly pool continued to decrease in P. ryukyuensis and was completely depleted in S. pistillata. The delay in the onset of oxidative stress in P. ryukyuensis and the dramatic increase in the activities of the antioxidant enzymes in S. pistillata, which contains low concentrations of Myc-Gly suggest that Myc-Gly provides rapid protection against oxidative stress before the antioxidant enzymes are induced. These findings strongly suggest that Myc-Gly is functioning as a biological antioxidant in the coral tissue and zooxanthellae and demonstrate its importance in the survival of reef-building corals under thermal stress.     

The effect of sub-lethal increases in temperature on the growth and population trajectories of three scleractinian corals on the southern Great Barrier Reef

To date, coral death has been the most conspicuous outcome of warming tropical seas, but as temperatures stabilize at higher values, the consequences for the corals remaining will be mediated by their demographic responses to the sub-lethal effects of temperature. To gain insight into the nature of these responses, here I develop a model to test the effect of increased temperature on populations of three pocilloporid corals at One Tree Island, near the southern extreme of the Great Barrier Reef (GBR). Using Seriatopora hystrix, S. caliendrum and Pocillopora damicornis as study species, the effects of temperature on growth were determined empirically, and the dynamics of their populations determined under natural temperatures over a 6-month period between 1999 and 2000 [defined as the study year (SY)]. The two data sets were combined in a demographic test of the possibility that the thermal regime projected for the southern GBR in the next 55–83 years—warmer by 3°C than the study year (the SY+3 regime), which is equivalent to 1.4°C warmer than the recent warm year of 1998—would alter coral population trajectories through the effects on coral growth alone; the analyses first were completed by species, then by family after pooling among species. Laboratory experiments showed that growth rates (i.e., calcification) varied significantly among species and temperatures, and displayed curvilinear thermal responses with growth maxima at ∼27.1°C. Based on these temperature-growth responses, the SY+3 regime is projected to: (1) increase annualized growth rates of all taxa by 24–39%, and defer the timing of peak growth from the summer to the autumn and spring, (2) alter the intrinsic rate of population growth (λ) for S. hystrix (λ decreases 26%) and S. caliendrum (λ increases 5%), but not for P. damicornis, and (3) have a minor effect on λ (a 0.3% increase) for the Pocilloporidae, largely because λ varies more among species than it does between temperatures. Ten-year population projections suggest that the effects of a sub-lethal increase in temperature (i.e., the SY+3 regime) are relatively small compared to the interspecific differences in population dynamics, but nevertheless will alter the population size and increase the relative abundance of large colonies at the expense of smaller colonies for all three species, as well as the Pocilloporidae. These effects may play an important role in determining the nuances of coral population structure as seawater warms, and their significance may intensity if the coral species pool is depleted of thermally sensitive species by bleaching.     

17Beta-hydroxysteroid dehydrogenase (17beta-HSD) in scleractinian corals and zooxanthellae

Steroid metabolism studies have yielded evidence of 17β-hydroxysteroid dehydrogenase (17β-HSD) activity in corals. This project was undertaken to clarify whether there are multiple isoforms of 17β-HSD, whether activity levels vary seasonally, and if zooxanthellae contribute to activity. 17β-HSD activity was characterized in zooxanthellate and azooxanthellate coral fragments collected in summer and winter and in zooxanthellae cultured from Montipora capitata. More specifically, 17β-HSD activity was characterized with regard to steroid substrate and inhibitor specificity, coenzyme specificity, and Michaelis constants for estradiol (E₂) and NADP⁺. Six samples each of M. capitata and Tubastrea coccinea (three summers, three winters) were assayed with E₂ and NADP⁺. Specific activity levels (pmol/mg protein) varied 10-fold among M. capitata samples and 6-fold among T. coccinea samples. There was overlap of activity levels between summer and winter samples. NADP⁺ / NAD⁺ activity ratios varied from 1.6 to 22.2 for M. capatita, 2.3 to 3.8 for T. coccinea and 0.7 to 1.1 for zooxanthellae. Coumestrol was the most inhibitory of the steroids and phytoestrogens tested. Our data confirm that corals and zooxanthellae contain 17β-HSD and are consistent with the presence of more than one isoform of the enzyme.     

Studies of fossil hyaenids: the genera Ictitherium Roth & Wagner and Sinictitherium Kretzoi and a new species of Ictitherium

Samples of the Miocene hyaenid Ictitherium from China and Pikermi, Greece, are analysed statistically. Ictitherium viverrinum Roth & Wagner, 1854 and Ictitherium gaudryi Zdansky, 1924, are found to be conspecific. Ictitherium sinense Zdansky, 1924 is also reduced to synonymy with Ictitherium viverrinum. Ictitherium kurteni sp. nov. differs from 1. viverrinum particularly in its large C^s and large and broad P³.     

Musteloids and feloids (Mammalia, Carnivora) from the late Miocene locality of Pikermi (Attica, Greece)

Some relatively rare carnivore remains from Pikermi are studied. The present specimens include Simocyon primigenius(ROTH and WAGNER, 1854), Promeles palaeatticus(WEITHOFER, 1888), Martes woodwardiPILGRIM, 1931, Felis atticaWAGNER, 1857 and Machairodus giganteus(WAGNER, 1848), as well as some postcranial remains that resemble Enhydriodon? latipesPILGRIM, 1931 and are assigned to Mustelidae gen. et spec. indet. Some of these species were not known until now but from their holotypes as M. woodwardi and E.? latipes. Other species such as F. attica and M. giganteus are better known but from relatively scant material. Since the material of the earlier mentioned species comes from Pikermi, their type locality, it is of especial importance and improves our knowledge for the Pikermi carnivores and their relationships to other species. In some cases where the material comes from ossiferous blocks, the accompanying faunal context is discussed.     

Earliest diagenesis in scleractinian coral skeletons: implications for palaeoclimate-sensitive geochemical archives

Live-collected samples of four common reef-building coral genera (Acropora, Pocillopora, Goniastrea, Porites) from subtidal and intertidal settings of Heron Reef, Great Barrier Reef, show extensive early marine diagenesis where parts of the coralla less than 3 years old contain abundant macro- and microborings and aragonite, high-Mg calcite, low-Mg calcite, and brucite cements. Many types of cement are associated directly with microendoliths and endobionts that inhabit parts of the corallum recently abandoned by coral polyps. The occurrence of cements that generally do not precipitate in normal shallow seawater (e.g., brucite, low-Mg calcite) highlights the importance of microenvironments in coral diagenesis. Cements precipitated in microenvironments may not reflect ambient seawater chemistry. Hence, geochemical sampling of these cements will contaminate trace-element and stable-isotope inventories used for palaeoclimate and dating analysis. Thus, great care must be taken in vetting samples for both bulk and microanalysis of geochemistry. Visual inspection using scanning electron microscopy may be required for vetting in many cases.     

Small-scale variability in the size structure of scleractinian corals around Moorea, French Polynesia: patterns across depths and locations

The size structure of coral populations is influenced by biotic and physical factors, as well as species-specific demographic rates (recruitment, colony growth, mortality). Coral reefs surrounding Moorea Island are characterized by strong environmental gradients at small spatial scales, and therefore, we expected that the size structure of coral populations would vary greatly at this scale. This study aimed at determining the degree of spatial heterogeneity in the population size structure of two coral taxa, Pocillopora meandrina and massive Porites spp., among depths (6, 12, and 18 m) and among locations (Vaipahu, Tiahura and Haapiti) representing different exposure to hydrodynamic forces. Our results clearly underlined the strong heterogeneity in the size structure of both P. meandrina and massive Porites spp., with marked variation among depths and among locations. However, the lack of any consistent and regular trends in the size structure along depths or among locations, and the lack of correlation between size structure and mean recruitment rates may suggest that other factors (e.g., stochastic life history processes, biotic interactions, and disturbances) further modify the structure of coral populations. We found that the size structure of P. meandrina was fundamentally different to that of massive Porites spp., reflecting the importance of life history characteristics in population dynamics. Handling editor: I. Nagelkerken     

Influence of seawater temperature on growth bands, mineralogy and carbonate production in a bioconstructional bryozoan

The cheilostome bryozoan Pentapora, an important benthic carbonate producer on non-tropical continental shelves, displays seasonal variations in deposition of the calcareous skeleton reflected by ‘winter’ and ‘summer’ growth bands. Studies on colonies from Atlantic and Mediterranean localities show that the ratio of the heights of these growth bands correlates significantly with mean annual range of temperature (MART) and mean annual temperature (MAT). The locality with the lowest MART and MAT showed the greatest wt% of calcite in the winter growth band. The opposite was true for the locality with the highest MART and MAT. Carbonate standing stock and carbonate production estimated for Atlantic localities were an order of magnitude lower than those measured at Mediterranean localities. Variability in skeletal carbonate depositional pattern and mineralogy suggests that fossil and historical collections of Pentapora may be useful indicators of past thermal conditions.     

Prostrepsiceros and Protragelaphus (Artiodactyla,Mammalia) from the Late Miocene locality of Chomateri (Attica,Greece)

The Late Miocene fossiliferous locality of Chomateri is located close to the classic locality of Pikermi, but unfortunately its faunal context is not sufficiently known. Some fossil remains of spiral-horned antelopes from Chomateri are assigned to Prostrepsiceros rotundicornis and Protragelaphus skouzesi. The co-existence of P. rotundicornis and P. skouzesi is relatively rare in the Late Miocene, but well-documented in Pikermi. Comparisons of the Chomateri material support a middle Turolian age for the Chomateri locality and suggest a close chronological relation to the Pikermi fauna.     

Sediment‐encased maturation: a novel method for simulating diagenesis in organic fossil preservation

Exceptional fossils can preserve diagenetically‐altered biomolecules. Understanding the pathways that lead to such preservation is vital to utilizing fossil information in evolutionary and palaeoecological studies. Experimental taphonomy explores the stability of tissues during microbial/autolytic decay or their molecular stability through maturation under high pressure and temperature. Maturation experiments often take place inside sealed containers, preventing the loss of labile, mobile or volatile molecules. However, wrapping tissues inside aluminium foil, for example, can create too open a system, leading to loss of both labile and recalcitrant materials. We present a novel experimental procedure for maturing tissues under elevated pressure/temperature inside compacted sediment. In this procedure, porous sediment allows maturation breakdown products to escape into the sediment and maturation chamber, while recalcitrant, immobile components are contained, more closely mimicking the natural conditions of fossilization. To test the efficacy of this procedure in simulating fossil diagenesis, we investigate the differential survival of melanosomes relative to proteinaceous tissues through maturation of fresh lizard body parts and feathers. Macro‐ and ultrastructures are then compared to fossils. Similar to many carbonaceous exceptional fossils, the resulting organic components are thin, dark films composed mainly of exposed melanosomes resting on the sediment in association with darkened bones. Keratinous, muscle, collagenous and adipose tissues appear to be lost. Such results are consistent with predictions derived from non‐sediment‐encased maturation experiments and our understanding of biomolecular stability. These experiments also suggest that organic preservation is largely driven by the original molecular composition of the tissue and the diagenetic stability of those molecules, rather than the tissue's decay resistance alone; this should be experimentally explored in the future.     

A well‐preserved isopod from the Middle Jurassic of southern Germany and implications for the isopod fossil record

A new isopod species, Eonatatolana geisingensis gen. et sp. nov., is described from Middle Jurassic shallow‐water sediments of southern Germany. It shows not only the almost completely preserved dorsal morphology but, in addition, details of the cephalic appendages, the pereiopods, pleopods and uropods. The presence of ambulatory pereiopods I–VII of a wide tridentate mandibular incisor with prominently developed posteriormost tooth and a narrow frontal lamina indicates that the new species belongs to the subfamily Conilerinae of family Cirolanidae within the suborder Cymothoida. It is closer to the species of the modern genus NatatolanaBruce than to any fossil isopod hitherto described. The isopod fossil record as well as current practices of isopod taxonomy in palaeontology are discussed, and the facies distribution and fossilization of isopods is reviewed with examples from the Jurassic.