Articulated Coralline Algae Research Articles

Articulated Coralline Algae of the Gulf of California, Mexico, I: Amphiroa Lamouroux

Articulated Coralline Algae of the Gulf of California, Mexico, I: Amphiroa Lamouroux

Articulated coralline algae of the Gulf of California, Mexico, I: Amphiroa Lamouroux

Articulated coralline algae of the Gulf of California, Mexico, I: Amphiroa Lamouroux

Ascension Island, south Atlantic: A survey of inshore benthic macroorganisms, communities and interactions

Ascension, an isolated volcanic island 07° 57′ south of the Equator, is about 145 km west of the mid-Atlantic ridge. The position and coastal configuration of the island results in a high level of wave-action throughout. Six categories of marine habitat are distinguished: (1) open littoral rocks (igneous formations; beach rocks); (2) blow-hole areas; (3) pools (tide pools; inland saline pools); (4) turtle ponds; (5) outfall channels from power stations; (6) sublittoral substrata (rocky areas; calcareous cobbles; conch shells). Except in the absence of barnacles, the characterising organisms on wave-exposed igneous rocks are distributed much as reported elsewhere along tropical Atlantic shores, i.e.: small snails define the littoral fringe; in the eulittoral are two subzones, the upper lacking characterising organisms, the lower with lithothamnia; on the sublittoral fringe exists the sea urchin Echinometra lucunter L. Luxuriant and diversified filamentous and fleshy algae develop only where the Ascension blackfish ( Melichthys niger Bloch), which are extremely abundant and widespread, can either not penetrate or not feed readily due to water movement (e.g. in inland pools; tide pools with rocky barriers; beach; rock slabs; the sublittoral in protective niches, crevices and holes). The contents of the blackfish digestive system show that algae, particularly articulated coralline algae, are widely taken by choice, necessity, or accident. Areas which are intensely grazed by fish carry prostrate or short growth forms of normally large or erect algae as a basal turf; only blue-green algae appear as unrestricted growths. Where sea urchins also are present (e.g. in the sublittoral fringe and certain tide pools) only the crustose lithothamnia persist.

Minium parvum gen. et sp. nov., a crustose member of the Rhodymeniales (Rhodophyta)

Abstract Minium parvum gen. et sp. nov. exists in all stages as a crust, a growth form previously unknown in the order to which it belongs-the Rhodymeniales. While members of this order exhibit a diversity of thallus form and anatomy, only erect or decumbent types have been described heretofore. The new crustose genus comprises plants which grow epiphytically on subtidal articulated coralline algae. The vegetative crust is extremely thin, consisting of a basal layer one cell thick which bears assurgent filaments one to several cells in length. Gametophytes and tetra-sporophytes are isomorphic. In culture they alternate with one another. Reproductive structures are produced in nemathecia which arise from limited areas of the crust and which often expand laterally over the surface. Cruciately divided tetrasporangia are borne terminally among sterile filaments. Carposporangia develop in dense lobes and no tela arachnoidea is formed. While Minium unquestionably belongs to the Rhodymeniales, its position withi...

The genus Metagoniolithon Weber-van Bosse (Corallinaceae, Rhodophyta)

The characters of the genus Metagoniolithon Weber-van Bosse, the single genus within the subfamily Metagoniolithoideae Johansen, are defined. The thalli are differentiated into basal crusts, genicula and intergenicula, with all the tissues displaying cell fusions but lacking secondary pit connections. Initial apical branching is dichotomous, but later the meristematic genicula produce false whorls of branches. The branches lack apical cover cells but have mucilaginous caps. The conceptacles, with their overlying mucilaginous caps, are initiated in the cortical tissue of the intergenicula. The plants are dioecious. In the cystocarpic conceptacle the fusion cell is continuous and the carpospore formation is restricted to the periphery of the fusion cell. The spermatangia develop only on the floor of the conceptacle. The uniporate roof of the tetrasporangial conceptacle is formed by the growth of filaments within the ring of developing marginal tetrasporangia. Spore germination is of the Amphiroa type. The three species are endemic and restricted to western and southern Australia: M. radiatum (Lamarck) comb. nov. is epilithic; M. stelliferum (Lamarck) Weber-van Bosse and M. chara (Lamarck) comb. nov. var, chara and var. dichotomum var, nov. are epiphytic, commonly on the seagrass Amphibolis C. Agardh. The basal crust of the epiphytic species is epiphytic on species of Hetevoderma Foslie growing on Amphibolis. The characters of the genus Metagoniolithon are compared with those of Amphiroa Lamouroux, and a key to the articulated coralline algae of southern Australia is given.

Studies of reproductive organs in articulated coralline algae of Japan

Abstract The present paper deals with reproductive features in the following twelve species in eight genera of articulated coralline algae in Japan: Amphiroa zonata, Bossiella cretacea, Marginisporum crassissimum, Alatocladia modesta, Calliarthron yessoense, Serraticardia maxima, Corallina kaifuensis, Corallina officinalis, Corallina pilulifera, Corallina sessilis, Corallina sp. (resembling Haliptylon squamatum in external appearance) and Jania nipponica. All types of reproductive structures were studied morphologically in each species except in Marginisporum crassissima and Jania nipponica where only sporangial plants were observed. The formation of conceptacles and the development of reproductive organs agree in most respects with previous reports on other related coralline taxa. Information on reproduction is given for the first time for Amphiroa zonata, Alatocladia modesta, Corallina kaifuensis, Corallina pilulifera, Corallina sessilis, Corallina sp. and Jania nipponica. The process of paraphysis form...

Magnesium in Calcite From a Coralline Alga

ABSTRACT Analyses of calcite from field-collected and laboratory cultured specimens of the articulated coralline alga Calliarthron tuberculosum indicate that temperature is not an independent factor controlling the magnesium content of the calcite. Growth rate, which appears to be a function of temperature, is probably the mechanism responsible for changes in the magnesium content. Changes in growth rate may effect changes in the magnesium content of the calcite through the interaction of factors such as the diffusion rate of magnesium through the cell wall and the construction of an organic matrix or template.

Paleoecology of the cenozoic reefal foraminifers and algae — A brief review

The paleoecology of reefal foraminifers and algae assumes a considerable importance in determining and delineating sub-environments of ancient reefs, especially those of non-coral origin. A review of the ecologic distribution of the Cenozoic larger foraminifers in different biofacies of the reef-complex environment has revealed the following: (1) a prolific growth of “ Alveolina” was possible in the back-reef region near the reef core; (2) Orbitolites and Marginopora preferred sheltered waters on the reef-flat and in the back-reef zones; (3) nummulitids and Discocyclina thrived in both fore- and back-reef shoal areas, but the species living in the former are much stouter than those living in the latter; (4) Heterostegina is and, in the geologic past, was a form, preferring quieter waters of the back-reef lagoons and reef-flat pools; (5) Pellatispira was a typical fore-reef form. Smaller foraminifers, as a whole, are dominant in back-reef lagoons. An abundance of miliolids indicates a sheltered environment prevailing in the reef-flat pools and back-reef zones, whereas reef flats, in general, are characterized by a paucity of smaller foraminifers. An increase in the number of nodosariids and globigerinids points to a fore-reef environment, the depth of which is indicated by the relative abundance of the latter group. Encrusting foraminifers are characteristic of the reef core and are important constituents of for-algal (foraminiferal + algal) reef complexes. Of the algae, the calcarous chlorophyte Halimeda is relatively more abundant in the sheltered parts of a reef-complex, especially the lagoons, where water is moderately agitated and clear; its sudden abundance in the geologic record indicates the advent of a reefal environment. An abundance of the calcareous chlorophyte Dasycladaceae indicates the shallow back-reef areas adjacent to the reef core. Articulated coralline algae are associated with reef-complexes but are varied in their adaptability and, hence, are widely distributed in different parts of the complex. Abundant crustose coralline algae almost certainly indicate a reef-core sub-environment; their skeletons are among the chief constructional units of the core. They increase in abundance towards the outer edge of the reef core and decrease away from it.

The effect of orthophosphate concentration on the growth of articulated coralline algae (Rhodophyta)

Abstract The growth of articulated coralline algae is significantly inhibited by a medium enriched with orthophosphate at a concentration normally used in culturing other groups of marine algae. A medium with one quarter or less of this phosphate concentration promotes the growth of coralline algae in culture. These results are related to the observation that phosphates are crystal inhibitors of calcification. The absence or presence of coralline algae in certain types of habitats may thus prove to be a reliable biological indicator of relative levels of man-made phosphate pollution in seawater.

THE SIGNIFICANCE OF REPRODUCTIVE AND SPORE GERMINATION CHARACTERISTICS TO THE SYSTEMATIC OF THE CORALLINACEAE: NONARTICULATED CORALLINE ALGAE12

SUMMARYThis paper deals with reproductive and spore germination characteristics to the systematics of the nonarticulated coralline algae. As can the articulated coralline algae, the nonarticulated coralline algae may also he divided into 2 groups on the basis of their yearly reproductive cycles, spore dimensions, and spore germination characteristics: the Lithophyllum group and the Lithothamnium group. These 2 groups are basically identical with the Amphiroa and Corallina groups of the articulated coralline algae, respectively, so far as these 3 characters are concerned. The grouping of these representatives of the Corallinaceae into 2 groups—Amphiroa—Lithophyllum and Corallina–Lithothamnium—coincides with a grouping based on the manner of connection between cells of adjacent filaments.

Changes and additions to the articulated coralline flora of California

The study of collections of articulated coralline algae from California and the examination of types in European herbaria have provided information on which to amplify previous descriptions and revise nomenclature. Also, several populations representing a new species, Arthrocardia silvae, have been discovered in the northern part of the state. This is the first species of Arthrocardia recorded from North America. It is represented by plants less than 2 cm high in which the pores of tetrasporangial conceptacles are eccentric.Other corallines discussed are: Chiharaea bodegensis, in which carposporophytes have broad, thin, fusion cells with carposporangial filaments arising from upper surfaces; Haliptylon gracilis, which is transferred from Corallina; two species of Jania, J. adhaerens and J. crassa, both of which occur in southern California; and Serraticardia macmillanii, in which conceptacle position is clarified.

Growth rates in the articulated coralline Calliarthron (Rhodophyta)

Specimens of the articulated coralline alga Calliarthron tuberculosum growing on an underwater reef off the coast of central California were photographed over a period of 2 years, during which time the mean increase in branch length was 1.7 mm per month. A tier of medullary cells 50–75 μ high is formed about once a day and flexible genicula develop every 1.5–2.7 months. Mean growth rates are 1.3 mm per month in summer (April–Sept.) and 2.3 mm per month in winter (Oct–March). On glass and plexiglass settling surfaces placed among the algae, basal crusts under 1 mm in diameter were visible in less than 1 month, fronds were evident after 2 months, and the fronds bore conceptacles after 11 months. Measurements of photographed and collected specimens reveal that the plants mostly branch during two different times of the year, from March to June and again from September to December.