Distribution of Living Larger Foraminifera NW of Sesoko-Jima, Okinawa, Japan

Abstract. Living, symbiont-bearing, larger foraminiferids restricted to the photic zone incorporate mechanisms blocking solar radiation and water current transportation. They can be divided in two groups according to their wall structure: 1, Families with opaque test walls, reducing light penetration: Peneroplids inhabit shallow-water environments from the intertidal ( Peneroplis in large numbers) down to 40 m ( Dendritina , preferring sandy substrates). Soritids are restricted to subtidal environments with less water turbulence and range from the reef moat down to 60 m. Amphisorus and Marginopora are common down to 30 m, whereas Parasorites is restricted to deeper parts of the reef slope. Alveolinella can be found in the upper 40 m of the reef slope. 2. Families with hyaline test walls, adjusted for light penetration: amphisteginids inhabit the whole photic zone, demonstrating a correlation of test flattening with increasing depth. Calcarinids cling with their spines to firm substrates such as algal thalli or macroids. Baculogypsina is restricted to high energetic regions on the reef flat. Calcarina inhabits similar environments, extending its distribution range within fore reefs down to 80 m. Baculogypsinoides is a dominant calcarinid genus from 30 to 70 m depth. Within nummulitids, Heterostegina prefers hard substrates on the reef slope, while Assilina (= Operculina ) is frequent in deeper parts and is independent of substrates. Sandy bottoms from 30 to 60 m are inhabited by the last living representative of the genus Nummulites, N. venosus . The giant foraminifer Cycloclypeus , with test sizes up to 7 cm, is restricted to fore reef areas below 50 m down to the base of the photic zone.     

Nucleotide sequence of β-tubulin gene from the soft coralscleronephthya gracillimum (kükenthal)

We cloned the complete cDNA of the β-tubulin from the soft coral,Scleronephthya gracillimum (Kükenthal) (Alcyonacea, Octocorallia, Anthozoa, Cnidaria), via the random sequencing of a cDNA library and the 5′-rapid amplification of cDNA end (RACE) technique. The full-length cDNA of theS. gracillimum β-tubulin comprised 1541 bp, not including the poly (A)⁺ stretch, also contained a complete open reading frame, which codes for a total of 445 amino acids. The amino acid residues 16-402 appeared to be in a state of conservation in a variety of animals. Northern blot analysis clearly demonstrated that the sequence we have obtained is, indeed, the full-length cDNA of the β-tubulin gene inS. gracillimum.     

The research on the remote sensing''s information tree model of the Nansha coral islets and reef''s spatial structure

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南沙群岛永暑礁钻井珊瑚礁和珊瑚碎屑的磁学分析

通过南沙群岛永暑礁南永1、2井珊瑚礁和南永3井潟湖珊瑚碎屑的磁性测试与研究发现,它们的磁化率以负值(χ<0)为主,具抗磁性特性,但有稳定的剩余磁化强度,又具有铁磁性特性,即具有抗磁性与铁磁性共存的磁学性质。珊瑚礁和珊瑚碎屑的磁性主要来源于珊瑚骨骼及死亡后古生物和富铁细菌等壳体中变价的铁离子,这些变价铁离子在不同年代、不同环境下组成新的铁氧体,具有似单畴(PSD)的磁性特征。这个磁性不但在井深103m和254m处记录了布容/松山和松山/高斯地球磁场极性转换界限(年龄分别为0.78MaB.P.和2.58MaB.P.),而且记录了布容正极性期和松山反极性期内的琵琶湖I、II、贾拉米洛、奥都维、留尼汪Ⅰ、II地球磁场漂移,并提供了磁化率的变化可能与气候冷暖变换有关的信息。当χ<0时表示冷期,当χ>0时表示暖期。     

Ecological energetics of the tropical sea urchin Diadema antillarum Philippi in Barbados, West Indies

The common tropical sea urchin Diadema antillarum Philippi is the dominant herbivore on fringing coral reefs in Barbados, West Indies. The biological importance of Diadema as an agent of energy transfer was evaluated from energy budgets constructed for the population and for individuals of 10 size groups. Monthly energy budgets for urchins of various size groups balance within 1 kcal except for urchins of the largest size group examined. Approximately 20% of the monthly net benthic primary production of the fringing coral reef is consumed by Diadema. This percentage is considerably larger than the 7% reported for the consumption of benthic algal production by a population of the temperate water sea urchin, Strongylocentrotus droebachiensis, feeding in kelp beds but is lower than the 47% reported for the consumption of sea grass by the tropical urchin Lytechinus variegatus. Higher rates of secondary production of Diadema compared to that of Strongylocentrotus may be in part due to higher net and gross growth efficiencies exhibited by Diadema. It is apparent that Diadema is more efficient at converting its algal food resources into urchin biomass than is Strongylocentrotus of similar size. In comparison to Strongylocentrotus and Lytechinus, Diadema releases as much energy to the benthos in the form of fecal pellet detritus as do the other two species. The production of fecal pellet detritus is the most important pathway of energy transfer on the fringing coral reef. Fecal pellet detritus contributes approximately 26 kcal m⁻² month⁻¹ to the benthic community. This amount is equivalent to 7·4% of the monthly net primary production of the benthic algae or approximately 37% of the caloric intake of the urchin population. In addition fecal pellet detritus produced by Diadema contains about 10 times the caloric content of surface sediments found to the north and south of the fringing reef and approximately 1·7 times the caloric content of sediments within the reef. The utilization of this energy-rich fecal pellet detritus by other reef organisms is discussed briefly.     

Experimental analysis of recruitment patterns of coral reef fishes in seagrass beds: Effects of substrate type, shape, and rigidity

Habitat choice of reef fish larvae at settlement is one of the mechanisms proposed to explain spatial patterns in the distribution of fishes and the corresponding spatial structure of communities. Field experiments using Pomacentridae were conducted at Iriomote Island, southern Japan, in order to determine if rare recruitment of coral reef fishes in seagrass beds is due to larval settlement preference. When three types of natural patch treatments (branching coral patch, seagrass patch, and control without patches) were established in cleared seagrass squares in the center of a seagrass bed, four pomacentrid species, Amblyglyphidodon curacao, Dischistodus prosopotaenia, Cheiloprion labiatus, and Dascyllus aruanus, recruited exclusively onto the coral patches, indicating that larvae distributed in the seagrass bed may have preferred a coral rather than seagrass substrate as a settlement habitat. The effects of differences in physical shape (grid structure for branching coral vs. vertical structure for seagrass leaves) and rigidity (rigid substrate for coral vs. flexible substrate for seagrass) between coral and seagrass substrates on such recruitment patterns were investigated using artificial coral and seagrass units. When artificial habitat units with predator exclusion cages were established in the cleared seagrass squares as above, high densities of A. curacao and D. prosopotaenia recruits were observed on the rigid rather than flexible habitat units (both unit types having similar shape), whereas differences in recruit numbers of the two species were unclear in differently shaped units. These results demonstrated that even though pomacentrid larvae are distributed in the seagrass bed, they do not settle on the seagrass substrate owing to their habitat choice being partially based on a preference for substrate rigidity. Moreover, non-recruitment of C. labiatus and D. aruanus on artificial habitat units suggested that the presence of living coral substrates rather than physical shape/rigidity of substrates are an important cue for habitat choice of these fishes.     

Stable isotope and chemical composition of pearls: Biomineralization in cultured pearl oysters in ago bay, Japan

The δ¹⁸O, δ¹³C and trace element composition of pearls collected from Ago Bay, Japan, were investigated in order to evaluate biomineralization in the cultured pearl oyster (Pinctada fucata martensii). The oxygen isotopic data suggest that the pearls were produced around 23–24°C, mainly in June to early July, which is consistent with their occurrence in the field. Therefore the pearls were produced under or close to isotopic equilibrium conditions, although they showed high calcification rates (higher than 0.2–1.0 g cm^{− 2}yr⁻¹) under which, for example, coral skeletons (calcification rate ∼0.28 g cm^{− 2}yr⁻¹) often show non-equilibrium isotope partitioning. The δ¹³C values were ∼− 2.9‰ lower than those calculated for offshore waters under equilibrium conditions. This may be due to low-δ¹³C bottom waters resulting from the degradation of organic matter (OM) or to a contribution of low-δ ¹³C food. In the latter case, a simple mass balance calculation gives a respiration component of 14%. Twelve trace elements of bulk pearl samples were classified into four groups on the basis of their enrichment/depletion patterns relative to seawater and inter-element relationships: group 1, Co, Cr, Pb; group 2, Ba, Cs, U; group 3, Cu, Sn, V, and group 4, Mn, Rb, Mo. Comparison with coral skeletons suggests that Ba and Mn (groups 2 and 4) were definitely much enriched in proteinaceous OM relative to aragonite crystals in pearls and that V (group 3) in pearls showed only slight enrichment in the organicrich layer. By contrast, the other elements showed small differences between both layers (enrichment factor of <3), suggesting that these elements occur largely in aragonite crystals.     

The Structure of Coral Communities at Hurghada in the Northern Red Sea

Abstract. The community structure of hard and soft corals, with an emphasis on hard corals, was determined by means of line-transects on 9 on-and off-shore reefs of different type and different wave exposure in the Northern Red Sea near Hurghada in Egypt. Coral communities were found to differentiate along a horizontal wind- and wave-exposure gradient. Exposed communities were dominated by Acropora species, sheltered communities by Porites species, and semi-exposed communities by Millepora species. Also, vertical within-reef zonations following a depth gradient were observed; these were unique for each exposure-determined community type. Average transect diversity was highest on semi-exposed reefs, lowest on sheltered reefs. Reef slopes were more diverse than other reef zones. The observed community structure was compared with data from the literature, and widely distributed, roughly comparable hard and soft coral communities were identified.     

Substrate Effects on the Bioeroding Demosponge Cliona orientalis.1. Bioerosion Rates

Abstract. Bioeroding sponges are highly specialised to live in and to erode various natural and man-made calcareous substrates. They encounter very different substrate features. Previous field observations suggest that damage caused by sponge bioerosion may vary with substrate density and architecture. This study aims to experimentally investigate influences of structurally different calcareous substrates on bioerosion activities of Cliona orientalis Thiele, 1900 , an important eroder of inshore Great Barrier Reef calcium carbonate. Blocks were made of the corals Goniopora tenuidens , massive Porites sp., Astreopora listeri, Favites halicora, Favia pallida, Goniastrea retiformis and Cyphastrea serailia , and of the clam Tridacna squamosa . They were grafted with C. orientalis tissue and re-examined after 9 months. Block weight loss, increase of pore volume and differences in breaking stability were measured as indicators of sponge erosion.Erosion caused by C. orientalis differed between substrates and was significantly more pronounced in denser materials with lower pore volume and in coral blocks with more structural barriers. Coral substrates with imperforate thecae and thicker dissepiment walls were more strongly eroded than those with perforate thecae and thinner dissepiments. At similar growth rates, more material has to be removed in denser material with more barriers compared to more porous substrates. Existing pores will be occupied, resulting in lower erosion rates. Erosion capabilities of the sponge could best be detected by the blocks' loss in dry weight, but the sponges also significantly reduced block breaking stability. Change in pore volume was not found to be a reliable parameter to investigate sponge erosion.