Halimeda

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Heroen Verbruggen - One of the best experts on this subject based on the ideXlab platform.

  • systematics of the genus Halimeda bryopsidales chlorophyta in brazil including the description of Halimeda jolyana sp nov
    Phycologia, 2017
    Co-Authors: Caroline Feijão Ximenes, Heroen Verbruggen, Valéria Cassano, Maria Elizabeth Bandeirapedrosa, Sonia Maria Barreto Pereira, Maria De Fatima De Oliveiracarvalho, Carlos Frederico D Gurgel
    Abstract:

    Abstract: The genus Halimeda has a wide geographic distribution in tropical to subtropical regions of the world. Molecular studies have uncovered cryptic and pseudocryptic species as well as strong biogeographic signals in phylogenies. To date, the diversity of Brazilian Bryopsidales has been studied from only a morphological perspective. Here we revised the diversity of Brazilian Halimeda based on molecular data (DNA barcode assessments of the tufA marker and multigene concatenated phylogenies) as well as morphological observations. Of the seven recognized morphospecies, only three were confirmed by molecular data: Halimeda opuntia, H. simulans and H. incrassata. The remaining four species, referred to as H. aff. cuneata, H. aff. gracilis, H. aff. tuna and H. aff. discoidea, showed morphological similarities with known species, but their sequences did not group with sequences of specimens from type localities, indicating the presence of cryptic diversity. Among the four taxa, H. aff. cuneata is so far en...

  • taxonomic revision of Halimeda bryopsidales chlorophyta in south western australia
    Australian Systematic Botany, 2016
    Co-Authors: Ma Chiela M Cremen, John M Huisman, Vanessa R Marcelino, Heroen Verbruggen
    Abstract:

    Halimeda J.V.Lamour. is a green algal genus that is an important component of tropical reefs and lagoons. Although it does not generally occur outside the tropics, the range of one putatively widespread species, Halimeda cuneata Hering, in Western Australia extends southward past Cape Leeuwin to its southern extreme at Cape Howe and around to its most easterly record at Middle Island of the Recherche Archipelago. Previous molecular studies have shown that H. cuneata as recorded worldwide encompasses cryptic species diversity, with most of the cryptic entities being geographically isolated from the others. Halimeda cuneata has been the name consistently applied to specimens from the south-western coast of Australia, where it has been regarded as the only representative of its genus in the region. Using a combination of morphological features and assessment of species boundaries based on a plastid gene (tufA) and a nuclear protein-coding gene (HSP90), we have reassessed the supposed presence of H. cuneata in south-western Australia. Our results showed the existence of two species in the region, namely, H. versatilis J.Agardh, to which the name H. cuneata has been misapplied, and H. gigas W.R.Taylor, a central-Pacific species previously recorded only from tropical Australia.

  • diversity of Halimeda bryopsidales chlorophyta in new caledonia a combined morphological and molecular study
    Journal of Phycology, 2012
    Co-Authors: Laury Dijoux, Heroen Verbruggen, Lydiane Mattio, Nathalie Duong, Claude Payri
    Abstract:

    Halimeda is a genus of calcified and segmented green macroalgae in the order Bryopsidales. In New Caledonia, the genus is abundant and represents an important part of the reef flora. Previous studies recorded 19 species that were identified using morphological criteria. The aim of this work was to reassess the diversity of the genus in New Caledonia using morpho-anatomical examinations and molecular analyses of the plastid tufA and rbcL genes. Our results suggest the occurrence of 22 species. Three of these are reported for the first time from New Caledonia: Halimeda kanaloana, H. xishaensis, and an entity resembling H. stuposa. DNA analyses revealed that the species H. fragilis exhibits cryptic or pseudocryptic diversity in New Caledonia. We also show less conclusive evidence for cryptic species within H. taenicola.

  • macroecology meets macroevolution evolutionary niche dynamics in the seaweed Halimeda
    Global Ecology and Biogeography, 2009
    Co-Authors: Heroen Verbruggen, Wiebe H C F Kooistra, L Tyberghein, Klaas Pauly, Caroline Vlaeminck, Katrien Van Nieuwenhuyze, Frederik Leliaert, Olivier De Clerck
    Abstract:

    Aim  Because of their broad distribution in geographical and ecological dimensions, seaweeds (marine macroalgae) offer great potential as models for marine biogeographical inquiry and exploration of the interface between macroecology and macroevolution. This study aims to characterize evolutionary niche dynamics in the common green seaweed genus Halimeda, use the observed insights to gain understanding of the biogeographical history of the genus and predict habitats that can be targeted for the discovery of species of special biogeographical interest. Location  Tropical and subtropical coastal waters. Methods  The evolutionary history of the genus is characterized using molecular phylogenetics and relaxed molecular clock analysis. Niche modelling is carried out with maximum entropy techniques and uses macroecological data derived from global satellite imagery. Evolutionary niche dynamics are inferred through application of ancestral character state estimation. Results  A nearly comprehensive molecular phylogeny of the genus was inferred from a six-locus dataset. Macroecological niche models showed that species distribution ranges are considerably smaller than their potential ranges. We show strong phylogenetic signal in various macroecological niche features. Main conclusions  The evolution of Halimeda is characterized by conservatism for tropical, nutrient-depleted habitats, yet one section of the genus managed to invade colder habitats multiple times independently. Niche models indicate that the restricted geographical ranges of Halimeda species are not due to habitat unsuitability, strengthening the case for dispersal limitation. Niche models identified hotspots of habitat suitability of Caribbean species in the eastern Pacific Ocean. We propose that these hotspots be targeted for discovery of new species separated from their Caribbean siblings since the Pliocene rise of the Central American Isthmus.

  • Halimeda pygmaea and Halimeda pumila bryopsidales chlorophyta two new dwarf species from fore reef slopes in fiji and the bahamas
    Phycologia, 2007
    Co-Authors: Heroen Verbruggen, Diane S Littler, Mark M Littler
    Abstract:

    H. VERBRUGGEN, D.S. LITTLER AND M.M. LITTLER. 2007. Halimeda pygmaea and Halimeda pumila (Bryopsidales, Chlorophyta): two new dwarf species from fore reef slopes in Fiji and the Bahamas. Phycologia 46: 513–520. DOI: 10.2216/07-01.1 Halimeda pygmaea and Halimeda pumila, two diminutive calcified green algal species, are described from material collected on Fijian and Bahamian reef slopes, respectively. The species resemble Halimeda cryptica in having a single siphon traversing the nodes between subsequent calcified segments and living in sheltered fore-reef slope habitats. They differ from H. cryptica by their diminutive size and various anatomical features. Molecular sequence data (tufA) underpin the identity of H. pygmaea and reveal its phylogenetic position as a sister taxon to H. cryptica in the Halimeda section Micronesicae.

Hildegard Westphal - One of the best experts on this subject based on the ideXlab platform.

  • ocean acidification alters the calcareous microstructure of the green macro alga Halimeda opuntia
    Coral Reefs, 2015
    Co-Authors: Andre Wizemann, Friedrich W Meyer, Hildegard Westphal, Christian Wild, Laurie C Hofmann
    Abstract:

    Decreases in seawater pH and carbonate saturation state (Ω) following the continuous increase in atmospheric CO2 represent a process termed ocean acidification, which is predicted to become a main threat to marine calcifiers in the near future. Segmented, tropical, marine green macro-algae of the genus Halimeda form a calcareous skeleton that involves biotically initiated and induced calcification processes influenced by cell physiology. As Halimeda is an important habitat provider and major carbonate sediment producer in tropical shallow areas, alterations of these processes due to ocean acidification may cause changes in the skeletal microstructure that have major consequences for the alga and its environment, but related knowledge is scarce. This study used scanning electron microscopy to examine changes of the CaCO3 segment microstructure of Halimeda opuntia specimens that had been exposed to artificially elevated seawater pCO2 of ~650 µatm for 45 d. In spite of elevated seawater pCO2, the calcification of needles, located at the former utricle walls, was not reduced as frequent initiation of new needle-shaped crystals was observed. Abundance of the needles was ~22 % µm−2 higher and needle crystal dimensions ~14 % longer. However, those needles were ~42 % thinner compared with the control treatment. Moreover, lifetime cementation of the segments decreased under elevated seawater pCO2 due to a loss in micro-anhedral carbonate as indicated by significantly thinner calcified rims of central utricles (35–173 % compared with the control treatment). Decreased micro-anhedral carbonate suggests that seawater within the inter-utricular space becomes CaCO3 undersaturated (Ω < 1) during nighttime under conditions of elevated seawater pCO2, thereby favoring CaCO3 dissolution over micro-anhedral carbonate accretion. Less-cemented segments of H. opuntia may impair the environmental success of the alga, its carbonate sediment contribution, and the temporal storage of atmospheric CO2 within Halimeda-derived sediments.

  • Ocean acidification alters the calcareous microstructure of the green macro-alga Halimeda opuntia
    Coral Reefs, 2015
    Co-Authors: Andre Wizemann, Friedrich W Meyer, Christian Wild, Laurie C Hofmann, Hildegard Westphal
    Abstract:

    Decreases in seawater pH and carbonate saturation state (Ω) following the continuous increase in atmospheric CO2 represent a process termed ocean acidification, which is predicted to become a main threat to marine calcifiers in the near future. Segmented, tropical, marine green macro-algae of the genus Halimeda form a calcareous skeleton that involves biotically initiated and induced calcification processes influenced by cell physiology. As Halimeda is an important habitat provider and major carbonate sediment producer in tropical shallow areas, alterations of these processes due to ocean acidification may cause changes in the skeletal microstructure that have major consequences for the alga and its environment, but related knowledge is scarce. This study used scanning electron microscopy to examine changes of the CaCO3 segment microstructure of Halimeda opuntia specimens that had been exposed to artificially elevated seawater pCO2 of ~650 µatm for 45 d. In spite of elevated seawater pCO2, the calcification of needles, located at the former utricle walls, was not reduced as frequent initiation of new needle-shaped crystals was observed. Abundance of the needles was ~22 % µm−2 higher and needle crystal dimensions ~14 % longer. However, those needles were ~42 % thinner compared with the control treatment. Moreover, lifetime cementation of the segments decreased under elevated seawater pCO2 due to a loss in micro-anhedral carbonate as indicated by significantly thinner calcified rims of central utricles (35–173 % compared with the control treatment). Decreased micro-anhedral carbonate suggests that seawater within the inter-utricular space becomes CaCO3 undersaturated (Ω 

  • microstructural analyses of sedimentary Halimeda segments from the spermonde archipelago sw sulawesi indonesia a new indicator for sediment transport in tropical reef islands
    Facies, 2015
    Co-Authors: Andre Wizemann, Hildegard Westphal, Thomas Mann, Andre Klicpera
    Abstract:

    Understanding the origin of sediments and the direction of sediment transport is a prerequisite for accurate reconstruction of reef island evolution. In tropical settings, island development depends on the accumulation of sediments on the reef flat, which are produced by calcifying organisms such as corals, foraminifera, and green macro-algae of the genus Halimeda. In certain areas of tropical regions, calcareous segments from these algae might account for more than 50 wt% of the coarser sediment fraction. Halimeda-rich sediments typically contain complete segments that become widely distributed to a range of sedimentary settings. However, the exact sedimentary pathway is either mostly unknown or was neglected. Here we show that the alteration of Halimeda segments from the Spermonde Archipelago (SW Sulawesi, Indonesia) is related to processes during transport and deposition. Using field observations and scanning electron microscopy we observed that Halimeda segments, sampled from the reef flat to the shore on four uninhabited islands, without exception belong to the grain-size class of pebble gravel (1.6 > 0.4 cm; medium-to-fine pebbles) and reveal characteristic patterns of external and internal microstructural alteration with respect to sampling area. Furthermore, Halimeda species, from which most of these segments originate, preferably inhabit hard substrates in the reef, on the reef crest, and the outer reef flat. Thus, the observed distinct microstructural alteration of the segments allows drawing conclusions on sediment transport and deposition. Particularly, rapid secondary cementation may preserve the segments as a sedimentary component for the development and maintenance of reef islands and coastlines in tropical shallow seas.

  • a new model for the calcification of the green macro alga Halimeda opuntia lamouroux
    Coral Reefs, 2014
    Co-Authors: Andre Wizemann, Friedrich W Meyer, Hildegard Westphal
    Abstract:

    Halimeda opuntia is a cosmopolitan marine calcifying green alga in shallow tropical marine environments. Besides Halimeda’s contribution to a diverse habitat, the alga is an important sediment producer. Fallen calcareous segments of Halimeda spp. are a major component of carbonate sediments in many tropical settings and play an important role in reef framework development and carbonate platform buildup. Consequently the calcification of H. opuntia accounts for large portions of the carbonate budget in tropical shallow marine ecosystems. Earlier studies investigating the calcification processes of Halimeda spp. have tended to focus on the microstructure or the physiology of the alga, thus overlooking the interaction of physiological and abiotic processes behind the formation of the skeleton. By analyzing microstructural skeletal features of Halimeda segments with the aid of scanning electron microscopy and relating their occurrence to known physiological processes, we have been able to identify the initiation of calcification within an organic matrix and demonstrate that biologically induced cementation is an important process in calcification. For the first time, we propose a model for the calcification of Halimeda spp. that considers both the alga’s physiology and the carbon chemistry of the seawater with respect to the development of different skeletal features. The presence of an organic matrix and earlier detected external carbonic anhydrase activity suggest that Halimeda spp. exhibit biotic precipitation of calcium carbonate, as many other species of marine organisms do. On the other hand, it is the formation of micro-anhedral carbonate through the alga’s metabolism that leads to a cementation of living segments. Precisely, this process allows H. opuntia to contribute substantial amounts of carbonate sediments to tropical shallow seas.

Anchana Prathep - One of the best experts on this subject based on the ideXlab platform.

  • Diversity of Halimeda (Chlorophyta) from the Thai–Malay Peninsula
    Phycologia, 2020
    Co-Authors: Supattra Pongparadon, Giuseppe C Zuccarello, Siewmoi Phang, Hiroshi Kawai, Takeaki Hanyuda, Anchana Prathep
    Abstract:

    Abstract: The Thai–Malay Peninsula separates the Andaman Sea from the Gulf of Thailand. This barrier is known to affect species distribution and genetic diversity of marine organisms. Biodiversity studies need a correct species taxonomy to interpret their biogeography; this is especially relevant in marine algae where morphological characters are few or cryptic. We address species distributions of the important macroalgal genus Halimeda. The combination of morphological data and chloroplast tufA gene sequences were used to identify species, and to reveal the variation among Halimeda species around the Thai–Malay Peninsula. The morpho-anatomical and molecular analysis showed eight species of Halimeda in Thai and Malaysian waters: Halimeda borneensis, H. discoidea, H. gigas, H. macroloba, H. micronesica, H. minima, H. opuntia, H. renschii, and two undescribed species. Three species, H. minima, H. renschii and H. micronesica, were reported for the first time from the area. Species variation was much greater ...

  • diversity of Halimeda chlorophyta from the thai malay peninsula
    Phycologia, 2015
    Co-Authors: Supattra Pongparadon, Giuseppe C Zuccarello, Siewmoi Phang, Hiroshi Kawai, Takeaki Hanyuda, Anchana Prathep
    Abstract:

    Abstract: The Thai–Malay Peninsula separates the Andaman Sea from the Gulf of Thailand. This barrier is known to affect species distribution and genetic diversity of marine organisms. Biodiversity studies need a correct species taxonomy to interpret their biogeography; this is especially relevant in marine algae where morphological characters are few or cryptic. We address species distributions of the important macroalgal genus Halimeda. The combination of morphological data and chloroplast tufA gene sequences were used to identify species, and to reveal the variation among Halimeda species around the Thai–Malay Peninsula. The morpho-anatomical and molecular analysis showed eight species of Halimeda in Thai and Malaysian waters: Halimeda borneensis, H. discoidea, H. gigas, H. macroloba, H. micronesica, H. minima, H. opuntia, H. renschii, and two undescribed species. Three species, H. minima, H. renschii and H. micronesica, were reported for the first time from the area. Species variation was much greater ...

  • seasonal variation in density growth rate and calcium carbonate accumulation of Halimeda macroloba decaisne at tangkhen bay phuket province thailand
    Malaysian journal of science, 2008
    Co-Authors: Sutinee Sinutok, Supattra Pongparadon, Anchana Prathep
    Abstract:

    Seasonal variations in density, growth rate and calcium carbonate accumulation of Halimeda macroloba Decaisne, a dominant green alga at Tangkhen Bay on Cape Palma at Phuket province, Southern Thailand, were investigated. There was difference in density of H. macroloba between seasons, 18.72 + 1.68 in the summer and 5.02 + 0.66 thalli.m -2 in the rainy seasons. The higher density of H. macroloba in summer is likely to be the result of delayed effect of asexual propagation by vegetative. fragmentation. Growth rate of H. macroloba at Tangkhen bay, Phuket in summer season was slightly higher than in rainy season. Light availability and photoperiod were higher in the summer season that might increase growth rate by increasing photosynthesis rate in Halimeda plants. There was difference in percentage of calcium carbonate accumulation in H. macroloba between rainy and summer seasons (P <0.05). This might be a result of high light availability in summer season which might increase photosynthesis and growth rate in Halimeda plant. Moreover, high phosphate concentration in rainy season might inhibit calcium carbonate precipitation.

L. Hillis - One of the best experts on this subject based on the ideXlab platform.

  • Leeward bank margin Halimeda meadows and draperies and their sedimentary importance on the western Great Bahama Bank slope
    Coral Reefs, 1995
    Co-Authors: D. Freile, J. D. Milliman, L. Hillis
    Abstract:

    Bryopsidalean algal meadows in water depths of 20–40 m on the leeward side of western Great Bahama Bank (WGBB) lie between non-skeletal-dominated sand flats on the bank top to the east and a cemented steep escarpment to the west. The meadows contain dense populations of rhipsalian Halimeda species, as well as Udotea and Rhipocephalus. Extensive populations of other Halimeda species (opuntioids) occur at greater depths on the cemented rocky escarpment, growing as drapes or vines rather than as upright thalli. These meadows and draperies are important sources of coarse-grained carbonate sediments. This is shown by (1) deeper bank-edge sediments (30–60 m) containing considerably more Halimeda fragments than do the bank top, non-skeletal sands, and (2) the coarser fraction of slope sediments (down to 200 m) dominated by Halimeda plates, partly or extensively altered and internally cemented by magnesian calcite and aragonite. A transect across the bank margin from bank top (

  • leeward bank margin Halimeda meadows and draperies and their sedimentary importance on the western great bahama bank slope
    Coral Reefs, 1995
    Co-Authors: D. Freile, J. D. Milliman, L. Hillis
    Abstract:

    Bryopsidalean algal meadows in water depths of 20–40 m on the leeward side of western Great Bahama Bank (WGBB) lie between non-skeletal-dominated sand flats on the bank top to the east and a cemented steep escarpment to the west. The meadows contain dense populations of rhipsalian Halimeda species, as well as Udotea and Rhipocephalus. Extensive populations of other Halimeda species (opuntioids) occur at greater depths on the cemented rocky escarpment, growing as drapes or vines rather than as upright thalli. These meadows and draperies are important sources of coarse-grained carbonate sediments. This is shown by (1) deeper bank-edge sediments (30–60 m) containing considerably more Halimeda fragments than do the bank top, non-skeletal sands, and (2) the coarser fraction of slope sediments (down to 200 m) dominated by Halimeda plates, partly or extensively altered and internally cemented by magnesian calcite and aragonite. A transect across the bank margin from bank top (<10 m) to lower slope (300 m) provides a useful comparison for the locus of sediment production and accumulation. The production of Halimeda in these bank-edge habitats approximates that in the Great Barrier Reef or off Indonesia and Nicaragua in similar water depths. The apparent lack of thick sediment accumulation in WGBB compared to that seen elsewhere may reflect the high rates of downslope transport off Great Bahama Bank.

Cherie A Motti - One of the best experts on this subject based on the ideXlab platform.

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