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Algae, Coralline
... Crustose coralline red algae (Sporolithales and Corallinales, Rhodophyta: CCA) are considered benthic ecosystem engineers capable of modifying the physical characteristics of their environment and producing a habitat that can support a higher diversity and abundance of marine organisms in comparison with surrounding habitats (Nelson 2009, Nelson et al. 2012. Crustose coralline algae rank among the major reef builders as they are often the most abundant marine organisms on hard substrates within the photic zone (Steneck 1986, Littler andLittler 2011). They reinforce the structure of coral reefs by filling cracks and binding together much of the sand, dead coral and debris, creating a stable substrate less prone to erosion (see Nelson 2009 for a review). ...
Here we describe in detail two crustose coralline red algal (CCA) species newly reported for the southern Atlantic: Porolithon improcerum and Mesophyllum macroblastum. Porolithon improcerum was recorded on the remote oceanic island of Martim Vaz (ca. 1,200 km off the Brazilian Coast) and M. macroblastum on the Cagarras Archipelago (ca. 5 km off the coast of Rio de Janeiro city). Within the genus Porolithon, P. improcerum is characterized by thin vegetative thallus composed mostly of two cell layers and thalli forming several applanate branches overgrowing one another. Within the genus Mesophyllum, M. macroblastum is characterized by bearing volcano-like multiporate tetrasporangial conceptacles with a raised rim and sunken central pore plate in addition to pore canals of conceptacles being lined by cells that are similar in size and shape to other roof cells. While, P. improcerum has previously been reported for the northern Atlantic Ocean, this study represents the first report of M. macroblastum for the Atlantic Ocean.
A R T I C L E I N F O Keywords: Marine kinetic energy Cruise tourism Ocean currents Coral reefs Mexican caribbean A B S T R A C T In general, ocean energy refers to renewable energy for human consumption, but less often relates to conservation and environmental protection. Within this context, this study describes and investigates energy-biotopes as a new concept, based on energy features, to use as a relevant resource for reefs conservation, marine-based tourism, and the harvesting of renewable ocean energy for Cozumel Island. Cluster analyses and linear trend models indicate an energy-tourism-economy connection with a similarity >90% and a correlation >0.976 between tourist arrivals, total revenue (US$ 161.74), and electric energy consumption (~64.62 Wh), per tourist. Moreover, field measurements of ocean current velocities (U) were conducted to assess the spatial distribution of kinetic energy density (E D) over the western coast of Cozumel Island. These results were compared with information obtained from prior studies on reef cover, benthic distribution, and tourism activities to identify the environment-energy-tourism relationship. Results indicate that marine biotopes with low and intermediate energy values (E D < 60 J/m 3 , U < 0.34 m/s) correlate with reef structures that are highly attractive for tourism and with moderate flow velocities for drift-diving, which represents the basis of tourism and the primary source of income for Cozumel Island. In contrast, high-energy biotopes (E D > 250 J/m 3 , U < 0.70 m/s) may contribute to meeting energy demands through the use of marine energy and the resulting increase in tourism and economic development in the area. However, the effects on marine organisms that are not typically attractive for tourists, but are of ecological significance, should be considered. Environmental habitats and electric energy demands are discussed regarding the local economy, which supports a floating population of 4.10 million people and where the reef environment plays an essential role both as part of the marine landscape and in the formation of globally unique energy-biotopes.
Coralline algae are excellent archives for recording paleo-water depth, but to date few studies have used them for long-term paleo-water depth reconstruction. This study focuses on the Plio-Pleistocene section of Well CK2, which was drilled in the northern South China Sea. The section consists of 55.2 m of volcanic basement overlain by 873.55 m of carbonates. The chronological framework of Well CK2 has been well established using magnetostratigraphy and bulk sediment strontium isotope ratios. The Plio-Pleistocene section includes the uppermost 341 m (5.18 Ma). Based on observations of 201 petrologic thin sections, we identified nine coralline algae genera (nongeniculate: Mesophyllum, Spongites, Lithothamnion, Lithoporella, Lithophyllum, and Hydrolithon; articulated: Amphiroa, Jania, and Corallina), and five coralline algal assemblages (Mesophyllum assemblage, Spongites assemblage, Lithothamnion assemblage, Mesophyllum-Lithophyllum assemblage, and Lithoporella-Lithophyllum assemblage). The Mesophyllum assemblage dominates in the interval between 341 and 312 m (5.18–4.36 Ma; early Zanclean) and developed in a water depth between 15 and 25 m. The Spongites assemblage dominates in the interval between 312 and 309 m (4.36–4.28 Ma; middle Zanclean) and is characterized by subspherical rhodoliths (3 to 9 cm in diameter). This assemblage is probably related to the very shallow (0 to 5 m) water of the distal reef flat/reef crest. The Lithothamnion assemblage dominates in the interval between 309 and 200 m (4.28–2.20 Ma) and developed in a reef platform zone at a water depth of more than 25 m. The Mesophyllum-Lithophyllum assemblage dominates in the interval between 200 and 80 m (2.20–1.16 Ma) and developed in a water depth between 15 and 20 m. The Lithoporella-Lithophyllum assemblage dominates in the interval between 80 and 0 m (1.16–0 Ma) and develops in a water depth of 15 m or less. Our paleo-water depths are basically in agreement with global sea-level variations over time, indicating that paleo-water depths in the South China Sea were controlled mainly by eustatic variations. Based on the relationship between coral reef development and water depth, we further divided the Quaternary intervals into four long-term developmental stages. They consist of two catch-up stages: 1) from 5.18 to 4.28 Ma and 2) from 2.2 to 1.16 Ma; a give-up stage from 4.28 to 2.2 Ma; and a keep-up stage from 1.16 Ma to present. Our results confirm that the coralline algae in the coral reefs of the South China Sea can accurately record past water depth variations.
Spurs and grooves (SaGs) are a common and important feature of coral reef fore slopes worldwide. However, they are difficult to access and hence their morphodynamics and formation are poorly understood. We use remote sensing, with extensive ground truthing, to measure SaG morphometrics and environmental factors at 11,430 grooves across 17 reefs in the southern Great Barrier Reef, Australia. We revealed strong positive correlations between groove length, orientation and wave exposure with longer, more closely-spaced grooves oriented easterly reflecting the dominant swell regime. Wave exposure was found to be the most important factor controlling SaG distribution and morphology. Gradient of the upper reef slope was also an important limiting factor, with SaGs less likely to develop in steeply sloping (> 5°) areas. We used a subset of the morphometric data (11 reefs) to statistically define four classes of SaG. This classification scheme was tested on the remaining six reefs. SaGs in the four classes differ in morphology, groove substrate and coral cover. These differences provide insights into SaG formation mechanisms with implications to reef platform growth and evolution. We hypothesize SaG formation is dominated by coral growth processes at two classes and erosion processes at one class. A fourth class may represent relic features formed earlier in the Holocene transgression. The classes are comparable with SaGs elsewhere, suggesting the classification could be applied globally with the addition of new classes if necessary. While further research is required, we show remotely sensed SaG morphometrics can provide useful insights into reef platform evolution.
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In coastal seas, from the tropics to the poles, seaweeds supply the energy required to support diverse coastal marine life and provide habitat for invertebrates and fish. Retaining the highly successful approach and structure of the first edition, this is a synthesis of the role of seaweeds in underpinning the functioning of coastal ecosystems worldwide. It has been fully updated to cover the major developments of the past twenty years, including current research on the endosymbiotic origin of algae, molecular biology including 'omics', chemical ecology, invasive seaweeds, photobiology and stress physiology. In addition to exploring the processes by which seaweeds, as individuals and communities, interact with their biotic and abiotic environment, the book presents exciting new research on how seaweeds respond to local and global environmental change. It remains an invaluable resource for students and provides an entry into the scientific literature of a wide range of topics.
Overfishing and land-derived eutrophication are major local threats to coral reefs and may affect benthic communities, moving them from coral dominated reefs to algal dominated ones. The Central Red Sea is a highly under-investigated area, where healthy coral reefs are contending against intense coastal development. This in-situ study investigated both the independent and combined effects of manipulated inorganic nutrient enrichment (simulation of eutrophication) and herbivore exclosure (simulation of overfishing) on benthic algae development. Light-exposed and shaded terracotta tiles were positioned at an offshore patch reef close to Thuwal, Saudi Arabia and sampled over a period of 4 months. Findings revealed that nutrient enrichment alone affected neither algal dry mass nor algae-derived C or N production. In contrast, herbivore exclusion significantly increased algal dry mass up to 300-fold, and in conjunction with nutrient enrichment, this total increased to 500-fold. Though the increase in dry mass led to a 7 and 8-fold increase in organic C and N content, respectively, the algal C/N ratio (18±1) was significantly lowered in the combined treatment relative to controls (26±2). Furthermore, exclusion of herbivores significantly increased the relative abundance of filamentous algae on the light-exposed tiles and reduced crustose coralline algae and non-coralline red crusts on the shaded tiles. The combination of the herbivore exclusion and nutrient enrichment treatments pronounced these effects. The results of our study suggest that herbivore reduction, particularly when coupled with nutrient enrichment, favors non-calcifying, filamentous algae growth with high biomass production, which thoroughly outcompetes the encrusting (calcifying) algae that dominates in undisturbed conditions. These results suggest that the healthy reefs of the Central Red Sea may experience rapid shifts in benthic community composition with ensuing effects for biogeochemical cycles if anthropogenic impacts, particularly overfishing, are not controlled.
Miocene carbonates in the Mediterranean are dominated by organic buildups of rhodalgal and coral-reef facies with local stromatolitic mounds, ahermatypic coral mounds and oyster banks and occur in a wide variety of tectonic settings and substrates. Regional chronostratigraphic correlation is in a state of flux, but it appears that coral reef development was extensive during the climatic optimum of the Chattian-Aquitanian, Langhian and Late Tortonian-Messinian times. The coral reef provinces of the Mediterranean reflect the transition between Early Miocene open-oceanic, humid-tropical conditions and Late Miocene land-locked, semi-arid and marginally subtropical environments. Narrow platforms with fringing reefs are predominant; lagoonal facies are poorly developed and commonly with variable amounts of terrigenous mixing. Extensive carbonate platforms with barrier reefs and lagoons occur in Oligocene-Lower Miocene carbonates but are very scarce or ephemeral in Upper Miocene platforms. Depositional sequences of different orders of magnitude display a basic stacking pattern consisting of vertical aggradation, progradation and offlaping (downstepping); faithfully reflecting inferred relative sea-level oscillations. Coral diversity decreased from Early to Late Miocene times. The largest Upper Miocene reef complexes tend to be monogeneric and show good vertical zonation in colonial morphologies. Upper Miocene coral reefs developed before, during and after the repeated deposition of basinal evaporite units and marine marls, resulting in complex wedge-on-wedge geometries of difficult correlation. Miocene carbonates have a marked cyclicity of different orders of magnitude, particularly well recorded on Upper Miocene platforms.
Rhodoliths (free-living coralline red algae) can thrive under a wide range of temperatures, reduced light, and increased nutrient levels, and often form a distinct so-called rhodalgal lithofacies that is an important component of Cenozoic shallow-water carbonates. Global distributions illustrate that from the late-early to early-late Miocene (Burdigalian early Tortonian), rhodalgal facies reached peak abundances and commonly replaced coral-reef environments, accompanied by a decline in other carbonate-producing phototrophs. We argue that the dominance of red algae over coral reefs was triggered in the Burdigalian by enhanced trophic resources associated with a global increase in productivity, as evidenced by a long-term shift toward higher carbon isotope values. Rhodalgal lithofacies expanded further in the middle Miocene when strengthened thermal gradients associated with the establishment of the East Antarctic Ice Sheet led to enhanced upwelling while climate change generated increased weathering rates, introducing land-derived nutrients into the oceans. Globally cooler temperatures following a climatic optimum in the early-middle Miocene contributed to sustain the dominance of red algae and prevented the recovery of coral reefs. The global shift in nearshore shallow-water carbonate producers to groups tolerant of higher levels of trophic resources provides further evidence for increased nutrient levels during that time interval and shows the sensitivity of shallow-water carbonate facies as indicators of past oceanographic conditions.
A coral reef represents the net accumulation of CaCO3 produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of next century, increased CO2 concentration will decrease aragonite saturation state in the tropics by 30%, and biogenic aragonite precipitation by 14–30%. Coral reefs are particularly threatened, since reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.
In addition to salinity and temperature, nutrient concentrations in surface waters are known to have a significant impact on distribution of carbonate-producing biota, but have never been quantitatively evaluated against different temperatures along a latitudinal transect. The western coast of the Gulf of California, Mexico, presents a natural laboratory for investigating the influence of oceanographic parameters such as salinity, temperature, and chlorophyll a, a proxy for nutrients, on the composition of a range of modern heterozoan and photozoan carbonate environments along a north-south latitudinal gradient spanning the entire warm-temperate realm (29degreesN-23degreesN). Chlorophyll a, measured in situ at half-hour resolution, is highly variable throughout the year due to short-term upwelling, and increases significantly from the southern to northern Gulf of California. Salinity, in contrast, fluctuates little and remains at an average of 35%. From south to north, carbonate production ranges from oligotrophic-mesotrophic, coral reefdominated shallow-water areas (minimum temperature 18.6 degreesC) through mesotrophic-eutrophic, red algal-dominated, inner-shelf carbonate production in the central gulf (minimum temperature 16 degreesC), and to molluscan-bryozoan, eutrophic inner- to outer-shelf environments (minimum temperature 13.7 degreesC). The Gulf of California data, supplemented with oceanographic and compositional information from a database compiled from a spectrum of modern carbonate systems worldwide, demonstrates the significance of nutrient control in the formation of heterozoan, photozoan, and transitional heterozoan-photozoan carbonate systems and serves as a basis for more accurately interpreting fossil carbonates.
The intimate association between a selective herbivore (the chiton Choneplax lata) and its primary prey (the crustose coralline alga Porolithon pachydermum) results in increased biomass and accretion of the alga. This process, over ecological and geological time scales, comprises a major component of Caribbean reef-building systems. Manipulative experiments showed that as the chiton grazes the alga it stimulates new meristematic activity and removes sporlings of the competitively superior frondose and filamentous algae, thereby increasing the survival rate of P. pachydermum on the intertidal reef crest. Furthermore, in the absence of C. lata, overgrowths of frondose and filamentous epiphytes provide an attractive food source for parrotfishes (Scaridae), which accelerates bioerosion of the coralline reef-crest structure due to the deep rasping action of feeding activity. Algal removal experiments suggest that the role of P. pachydermum is to provide a predictable food source and refuge substratum, which increases survivorship of the burrowing chiton by minimizing expenditure of energy during foraging and risk of predation. The chiton/coralline alga association is abundant throughout tropical western Atlantic islands and augments reef-building processes on the shallow algal crest portion of Caribbean reefs. Cover of the Choneplax/Porolithon association in the Belize Barrier Reef crest averages 13% (maximum to 70%) with a mean chiton density of 664 individuals/m^2 within the association. On average, the extensive networks of interconnected chiton burrows extend between 6 and 10 cm deep and contain one C. lata for every six openings, with the majority of animals (66%) ranging from 16 to 30 mm in length. Gut contents of the chiton consist predominantly of P. pachydermum (51%), followed by bacterial detritus (30%), Cyanophyta (13%), Bacillariophyta (3%), and fleshy microalgae (3%). The close SEM (scanning electron microscope) match between radular morphology of C, lata and grazing scars on the thallus surface of P. pachydermum shows how the chiton regularly feeds on the coralline alga without causing mortality. Virtually all P. pachydermum in the vicinity of C. lata burrows contain radular tract scars of @?10 @mm in depth, whereas the photosynthetic meristematic, and reproductive tissues of coralline lie below 20 @mm. P. pachydermum under intense chiton grazing is photosynthetically competent with 0.1 mg C fixed@?g^-^1 organic dry mass@?^-^1, which is not significantly different from ungrazed material and within the range of rates for other crustoe coralline algae. The result is continuous net accretion at a mean rate of 2.3 mm/yr.
An overview of nongeniculate "corallinaceae" collection, preservation and examination of material taxonomic literature on nongeniculate "corallinaceae" historical analysis features diagnostic of subfamilies and genera the identification of Holocene subfamilies and genera accounts of Holocene subfamilies and genera Holocene genera requiring further evaluation, genera of uncertain status and excluded genera. Appendices: 1 - the terms primigenous and postigenous B - nomenclatural change C - list of herbarium abbreviations.
This study was initiated to reexamine phylogenetic relationships among coralline algae having secondary pit connections and lacking cell fusions. Nuclear small-subunit ribosomal RNA (18S rRNA) gene sequences were determined for the nongeniculate species Lithophyllum incrustans Philippi and Titanoderma pustulatum (Lamouroux) Nageli and aligned with 18S rRNA sequences for 35 other coralline species. Parsimony and maximum likelihood analyses of these data yielded congruent trees in which four major lineages were resolved. In these trees, geniculate and nongeniculate species having secondary pit connections and lacking cell fusions formed a well-supported clade within the Corallinaceae. Within this clade, the geniculate genera Amphiroa and Lithothrix do not form a monophyletic group. Results suggest that the genicula of Amphiroa and Lithothrix are probably not homologous; these genera are more closely related to nongeniculate species than they are to one another. A close relationship inferred between Amphiroa and Titanoderma was robustly supported in all analyses performed. The molecular data imply that Titanoderma and Lithophyllum are phylogenetically distinct and should be maintained as separate genera. Based on these and other data, a revised classification of the Lithophylloideae is presented and the subfamily is emended. Possible phylogenetic relationships among the Lithophylloideae and other coralline subfamilies are discussed and an overview of genicular evolution within the Corallinales is presented.
Articulated and non-articulated coralline algae were brought together in the family Corallinaceae in essentially its present-day circumscription by Decaisne in 1842. Since that time, this family has been perceived as one of the most distinctive assemblages of Rhodophyceae. Alignment of families of red algae into orders based on criteria that today are considered to reflect natural relationships extends back only as far as 1892, when Schmitz presented a scheme founded largely on details of the female reproductive system and gonimoblast development. In that scheme, the Corallinaceae occupied an anomalous position in the Cryptonemiales. While attempts have been made to modify the definition of the Cryptonemiales to accommodate the Corallinaceae more comfortably, an ongoing accumulation of information supports the segregation of that family into its own order. At least three previous authors have adopted the taxonomic concept of the Corallinales, but the name has not yet been validated. In the present paper a Latin diagnosis is provided. Diagnostic characters of the Corallinales include the following: (1) walls of most vegetative cells are impregnated with calcite; (2) meristems are often intercalary and covered by a layer of cells; (3) plugs of primary pit-connections have two-layered, dome-shaped caps; (4) reproductive structures are produced in roofed conceptacles in all genera but one; (5) tetrasporocytes usually undergo simultaneous zonate division; (6) post-fertilization events involve a cluster of procarpial filament systems.
Data from a comprehensive literature survey for the first time provide stage-level resolution of Early Cretaceous through Pleistocene species diversity for nongeniculate coralline algae. Distributions of a total of 655 species in 23 genera were compiled from 222 publications. These represent three family-subfamily groupings each with distinctive present-day distributions: (1) Sporolithaceae, low latitude, mainly deep water; (2) Melobesioid corallinaceans, high latitude, shallow water, to low latitude, deep water; (3) Lithophylloid/mastophoroid corallinaceans, mid- to low latitude, shallow water. Raw data show overall Early Cretaceous–early Miocene increase to 245 species in the Aquitanian, followed by collapse to only 43 species in the late Pliocene. Rarefaction analysis confirms the pattern of increase but suggests that scarcity of publications exaggerates Neogene decline, which was actually relatively slight. Throughout the history of coralline species, species richness broadly correlates with published global paleotemperatures based on benthic foraminifer δ18O values. The warm-water Sporolithaceae were most species-abundant during the Cretaceous, but they declined and were rapidly overtaken by the Corallinaceae as Cenozoic temperatures declined. Trends within the Corallinaceae during the Cenozoic appear to reflect environmental change and disturbance. Cool- and deep-water melobesioids rapidly expanded during the latest Cretaceous and Paleocene. Warmer-water lithophylloid/mastophoroid species increased slowly during the same period but more quickly in the early Oligocene, possibly reflecting habitat partitioning as climatic belts differentiated and scleractinian reef development expanded near the Eocene/Oligocene boundary. Melobesioids abruptly declined in the late Pliocene–Pleistocene, while lithophylloid/mastophoroids increased again. Possibly, onset of glaciation in the Northern Hemisphere (∼2.4 Ma) sustained or accentuated latitudinal differentiation and global climatic deterioration, disrupting high-latitude melobesioid habitats. Simultaneously, this could have caused moderate environmental disturbance in mid- to low-latitude ecosystems, promoting diversification of lithophylloids/mastophoroids through the “fission effect.” Extinction events that eliminated >20% of coralline species were most severe (58–67% of species) during the Late Cretaceous and late Miocene–Pliocene. Each extinction was followed by substantial episodes of origination, particularly in the Danian and Pleistocene.
Habitat recognition and selective settlement by dispersive propagules greatly increases the post-settlement survival chances of sessile organisms. To better understand the key role some species can play in the structure of highly complex coral reef ecosystems, we compare the role of two independent, but sequential, processes: settlement choice and post-settlement survival. This study describes the chemical and physical recognition and ranking of specific settlement substrata by coral larvae. Several species of crustose coralline algae (CCA) are known to induce coral settlement; however they also employ physical and biological anti-settlement defense strategies that vary greatly in effectiveness. We examine the interactions between settling larvae of two common reef building coral species (Ac-ropora tenuis and A. millepora) and five species of CCA (Neogoniolithon fosliei, Porolithon onkodes, Hydrolithon reinboldii, Titanoderma prototypum, and Lithoporella melobesioides) that co-occur on reef crests and slopes of the Great Barrier Reef, Australia. Distinct set-tlement patterns were observed when coral larvae were provided with a choice of settlement substrata. Settlement on the most preferred substratum, the CCA species T. prototypum, was 15 times higher than on N. fosliei, the least preferred substratum. The rates of post-settlement survival of the corals also varied between CCA species in response to their anti-settlement strategies (shedding of surface cell layers, overgrowth, and potential chemical deterrents). Rates of larval settlement, post-settlement survival, and the sensitivity of larvae to chemical extracts of CCA were all positively correlated across the five species of CCA. Nonliving settlement substrata on coral reefs is sparse; consequently the fact that only a few CCA species (notably T. prototypum) facilitate coral recruitment, has important im-plications for structuring the reef ecosystem.
Rapid assessment protocols for determining and monitoring the status of any given coral reef are provided and include measuring: (a) standing stocks of functional indicator groups, (b) herbivore populations, (c) water‐column nutrient levels, (d) tissue C:N:P ratios, (e) algal physiological‐response assays, and (f) herbivory assays. These measurements can reveal quantitative tipping‐point levels beyond which resilience to undesirable phase shifts begins to become critically reduced. Universal tipping‐point approximations are reviewed for inorganic nutrients, and posited for the first time for herbivory.
The relative roles of top‐down and bottom‐up controls in determining benthic community structure and the health of coral reefs are especially important management concerns. This paper specifically addresses the top‐down effects of herbivory and bottom‐up effects of nutrient enrichment on critical indicator groups, i.e. reef‐building corals, crustose coralline algae, dense turf algae and frondose macroalgae.
A predominance of (a) massive corals and calcareous coralline algae relative to frondose macroalgae and algal turfs indicates a healthy spatially heterogeneous condition reflecting low nutrients and high herbivory. An abundance of (b) frondose macroalgae illustrates the least desirable condition of elevated nutrient levels and reduced herbivory, possibly reflecting pollution in concert with destructive herbivore fishing practices. High coverage of (c) coralline algae suggests healthy high herbivory levels, but problems with elevated nutrients that are inhibitory to some corals. Domination by (d) dense turf algae indicates desirably low nutrient levels, but an inadequate herbivory component.
The fast growth and turnover rates of fleshy algae compared to other reef organisms highlight their value as early warning indicators of reef degradation.
From a management perspective, levels of herbivory and nutrients rank among the most useful quantitative indicators of coral reef resilience; whereas, the degree of degradation and mortality are inferred from the above functional indicator groups of benthic primary producers.
Published in 2006 by John Wiley & Sons, Ltd.
This study provides the first quantitative measures of deep-water (i.e., below scuba depths) rhodolith development, distribution, abundance, and primary productivity at sites of both active formation and breakdown. The 1.27-km² upper platform surface of San Salvador Seamount, Bahamas, ranges in depth from 67 to 91 m and averages 95.8% cover of rhodoliths that contribute an estimated 391 t organic C·yr⁻¹ to deep-sea productivity. The predominant nongeniculate coralline alga of the slope environment has an extremely narrow PI curve (photosynthesis vs. irradiance) of net primary production (0.005) to slightly beyond 0.24 μmol·m⁻²·⁻¹ PAR) suggesting that some deep-water benthic algae may be acclimated to restricted light ranges. Platform areas contain up to fice-deep accumulations (≈45 cm thick) of rhodoliths with their visible, planar (2-D), crustose algal cover (68.5%) composed of 41% Lithophyllum sp., 14.9% average nongeniculate corallines, and 12.6% Peyssonnelia sp. Platform rhodoliths also contain ≈25% average planar cover of the foraminiferan Gypsina sp. overlying the rock-penetrating chlorophyte Ostreobium sp.
When surfaces of boulders covered with Phymatolithon Foslie were compared with boulders of bare granite in a grazer removal experiment, the biomass of recruited fleshy algae was significantly lower on the Phymatolithon, being on average less than half that on the granite. This inhibitory effect was not species specific; the species composition and species diversity on the two substrata were similar. S.E.M. studies indicated that the surface of Phymatolithon is unstable in that epithallial cells slough off frequently. There are also numerous chalky white scales on the crust surface, up to ≈ 1 mm diameter and 10–15 cells thick, that are easily dislodged. We suggest that, although the possibility of chemical inhibition cannot be ruled out, the instability of the surface crust contributes significantly to inhibition of algal settlement on Phymatolithon. There was no evidence of dieback of Phymatolithon crusts during the 16 months of the experiment.
Measurements of cover, relative density, and frequency are given for the major reefbuilders on the Waikiki fringing reef. Crustose coralline algae cover 39% of the reef surface and exceed all other organisms as the major builders and consolidators of reef materials. An unidentified coralline (melobesioid C) covers the greatest area (17 %), but Hydrollthon reinboldii (Weber-van Bosse & Foslie) Foslie (11 % cover) because of its thicker thalli and higher relative density (45 %) and frequency (68 %) values is the primary limestone former. Melobesioid C ranks second and Sporolithon erythraeum (Rothpletz) Kylin (6 % cover) third in relative importance. Porolithon onkodes (Heydrich) Foslie (3 % cover), although shown by its low density (4 %) and frequency (6 %) to have a comparatively restricted distribution, is more important than P. gardineri (Foslie) Foslie (2 % cover). P. onkodes maintains and provides the surf-resistant reef edge and is, therefore, of great ecological importance. Coelenterate corals cover less than 1 % of the total area and are relatively unimportant on the fringing reef. The hypothesis is developed that the high ratio (200 : 1) of crustose corallines to corals at Waikiki may be partly due to increases in eutrophication.Experimental evidence shows that P. onkodes can withstand intense illumination and is thereby unique among Hawaiian crustose Corallinaceae. Sporolithon erythraeum is more typical of other crustose corallines since it is physiologically adapted to low-light habitats.
Coralline porous ceramics are biocompatible and osteoconductive implants. They have proven to be effective as bone graft substitutes in large animal models and in humans. Bone and supporting soft tissue grow into and throughout their porosity if the implant is placed in direct apposition to viable bone and the interfaces are stabilized. The bone within the implant remodels in response to Wolff's law. Both the implant properties (chemistry and porosity) and the biologic environment modulate the rate of implant resorption. Composite technology with resorbable polymers can improve the mechanical properties of these ceramics.
Notice sur les polypiers de la Grèce
- J B Bory De Saint-Vincent
Calcium carbonate production and carbon dioxide flux on a coral reef, Okinawa
- S Ohde
A Voyage to the Islands
- H Sloane