Browsing by Author "Fredericq, Suzanne"
Now showing 1 - 10 of 28
Results Per Page
Sort Options
- Alien Invasions: Quantifying the invasiveness risk of macroalgae in the AzoresPublication . Gabriel, Daniela; Martins, Beatriz; Ribeiro, Cláudia; Vilizzi, Lorenzo; Fredericq, SuzanneABSTRACT: The presence of aliens or non-indigenous species (NIS) is a known threat to biodiversity, health, and economy, so it is of high importance that their invasiveness risk be quantified. The mid-northern Atlantic archipelago of the Azores encompasses 30% of the European Union exclusive economic zone and is known to host a high proportion of marine NIS.
- Biodiversity of the Nemastomatales (Rhodophyta): new insights and future perspectivesPublication . Gabriel, Daniela; Neto, Ana I.; Fredericq, SuzanneABSTRACT: The Nemastomatales comprises two families of predominantly gelatinous representatives with heteromorphic life histories, the Nemastomataceae and Schizymeniaceae. Obscure and ephemeral events in the sexual cycle delimit genera in this order, but such phylogenetically informative features have not been confirmed for most species. Newly generated morphological data coupled with DNA sequence analysis inferred from chloroplast-encoded rbcL and nuclear LSU rDNA sequences of gelatinous red algae worldwide reveal that the external habit within select species is remarkably variable and cannot be used to distinguish species. Species reported as having a wide distribution range instead have a restricted distribution. For example, Platoma cyclocolpum (Mont.) Schmitz may be confined to the Macaronesian islands; the taxon going under this name from the Indian Ocean (Madagascar) is instead P. chrysymenioides Gavio et al., a species found throughout the Gulf of Mexico. Schizymenia dubyi (Chauvin ex Duby) J. Ag. described from Atlantic France is also present in Japan, but records of this taxon from the Azores, Namibia and Japan, should be referred to as S. apoda (J. Ag.) J. Ag., a species described from the Cape Province, South Africa. Recent deepwater collections of Predaea and Titanophora throughout the Gulf of Mexico coupled with unreported samples of Nemastomatales from the Azores and Japan are greatly expanding species diversity of the order. A firm biogeographic link between species from the Azores and the Gulf of Mexico and from Australia and the Indian Ocean is here firmly established and will be elaborated upon.
- Certified by nature: a new species of the gelatinous alga Dudresnaya (Dumontiaceae, Rhodophyta) from the AzoresPublication . Gabriel, Daniela; Neto, Ana I.; Fredericq, SuzanneABSTACT: Dudresnaya, a red algal genus belonging in the family Dumontiaceae, currently comprises 21 species of gelatinous algae from tropical to subtropical waters worldwide. Dudresnaya verticillata and D. crassa have been reported for the Azorean islands in species checklists since 1992 and 2001, respectively. The present work is the first taxonomic study of representatives of the genus in this archipelago. The Azorean specimens previously identified as Dudresnaya verticillata are here recognized as a new species based on four molecular markers (nuclear LSU, mitochondrial COI, and plastid rbcL and UPA). Genetic differences between the new taxon and its closest related species are: COI – 9,81%; rbcL – 7,35%; UPA – 3,44%; and LSU – 1,04%. The morphological and reproductive diagnostic features of the new species are described. Gametophytes are dioecious. Male plants present abundant spermatia borne on the outer cortical cells. Female plants bear 3-4 celled carpogonial branches and auxiliary cell branches borne at the base of cortical branches close to the axial filaments. Carposporophytes comprise numerous carpospores, forcing the surrounding cortical filaments to spread apart as they grow. Tetrasporophytes were not observed. Relationships among species of Dudresnaya are explored.
- Characterization of rhodolith beds in the northwestern Gulf of Mexico before and after the BP Deepwater Horizon oil spillPublication . Fredericq, Suzanne; Schmidt, William E.; Gabriel, Daniela; Sauvage, Thomas; Krayesky, DavidABSTRACT: In the northwestern Gulf of Mexico beds of rhodoliths and unconsolidated rubble are associated with unique offshore deep bank habitats, the salt domes or diapirs that are peculiar to that part of the northern Gulf. In contrast to being mainly composed of crustose corallines (or foraminifera), rhodoliths in the NW Gulf of Mexico at depths of 40-85 m are instead dominated by red algal crust-forming members of Peyssonneliaceae and Rhizophyllidaceae.
- The correct identification of the species going under the name Scizymenia dubyi (Schizymeniaceae, Rhodophyta) in the Azores, based on molecular and morphological evidences.Publication . Gabriel, Daniela; Schils, Tom; Neto, Ana I.; Fredericq, Suzanne
- The crustose red algal genus Peyssonnelia (Peyssonneliales, Rhodophyta) in the Azores : from five to one speciesPublication . Gabriel, Daniela; Schmidt, W. E.; Krayesky, D. M.; Harris, D. J.; Fredericq, SuzanneThe family Peyssonneliaceae comprises a worldwide group of non-calcified to calcified, crust-forming red algae of great ecological significance. Of the genera currently recognized in the family, Peyssonnelia has been widely considered to contain the largest number of species, with five members reported for the Azores. Using rbcL as a molecular marker, we here report on the taxonomic identity of recent collections of Peyssonneliaceae from the Azorean islands of São Miguel, Graciosa and Pico, and compare those specimens in a worldwide context. Only a single Peyssonnelia species, P. squamaria, is confirmed for the Azorean archipelago, with three different haplotypes. Although the populations in the Azores are genetically different from those occurring in the Mediterranean, this separation appears to be relatively recent.
- CRYPTO Project - What we found so farPublication . Gabriel, Daniela; Fredericq, Suzanne; Teixeira, Carlos E. P.; Calado, HelenaABSTRACT: The presence of non-indigenous species (NIS) is one of the greatest threats to marine biodiversity, presenting potential impacts not only on biodiversity, but also on the economy and public health. When a species is not evidently native or introduced, it is referred to as cryptogenic, an occurrence with consequences for understanding biological invasions. The subregion Azores, with 30% of the EU exclusive economic zone, has 26 species of macroalgae or 6% of its marine flora identified as NIS. This number may increase once the origin of 40 other species that are classified as cryptogenic is clarified. Since many potentially invasive species are currently categorized as cryptogenic, resolving their status is imperative to evaluate their ecological impact and to develop management plans. The CRYPTO Project targets on assessing the origin, distribution and risk of potentially invasive algae, coupled with the application of DNA barcoding, phylogenetic reconstructions, haplotype networks and phylogeographic analyses, coupled with historical assessment and ocean modeling. This project shall contribute to address the EU Horizon 2020’s societal challenge “Climate action, environment, resource efficiency and raw materials”, aiming at the protection of the environment and the conservation of unique Azorean ecosystems. Preliminary results will be presented.
- Genetic diversity of Gibsmithia hawaiiensis complex (Dumontiaceae, Rhodophyta)Publication . Gabriel, Daniela; Draisma, Stefano; Schmidt, William E.; Schils, Tom; Sauvage, Thomas; Maridakis, Clio; Gurgel, Carlos Frederico Deluqui; Lim, Phaik Eem; Harris, D. J.; Fredericq, SuzanneABSTRACT: The genus Gibsmithia was erected to accommodate a species with the peculiar combination of gelatinous lobes rising from cartilaginous stalks. Based on G. hawaiiensis from Hawaii, it remained monotypic for over 20 years, when three additional species were described from Australia. G. hawaiensis is unique for its furry appearance due to cortical filaments beyond the surface. Gibsmithia have been reported from the Indian Ocean and central and western Pacific, with G. hawaiensis having the widest distribution. Genetic studies based on COI, rbcL and UPA, reveal that G. hawaiiensis is monophyletic with nine distinct species sharing a similar habit. G. hawaiiensis complex exhibits high genetic diversity in Indomalaysia region, with different species presenting genetically variable populations. Species restricted to isolated region as Hawaii or the Red Sea comprises genetically conserved populations. Four of those cryptic species can be distinguished based on characters previously regarded as morphological plasticity: the generitype and the new species G. eilatensis, G. indomalayensis and G. lata distributa. Because specimens of the other species are only available dried onto herbarium paper or in silica-gel, their reproductive characters can not be characterized. New reports of the complex are given to Madagascar, Europa Island, the Red Sea and Guam, and also to new regions of Malaysia, Indonesia, the Philippines and the French Polynesia.
- Genetic diversity of Gibsmithia hawaiiensis complex (Dumontiaceae, Rhodophyta): Molecular phylogeny, taxonomic characterization, and the proposal of new speciesPublication . Gabriel, Daniela; Draisma, Stefano; Sauvage, Thomas; Schmidt, William; Fredericq, SuzanneABSTRACT: The genus Gibsmithia was erected on the basis of G. hawaiiensis Doty 1963 from the Hawaiian archipelago to accommodate a species of red algae in the Dumontiaceae consisting of clusters of gelatinous lobes growing from a cartilaginous stalk. Three additional species were subsequently described from Australia, i.e. G. dotyi Kraft & R.W. Ricker 1984, G. larkumii Kraft 1986 and G. womersleyi Kraft & Ricker ex Kraft 1986. Records of Gibsmithia have been reported from different localities throughout the Indian Ocean and the central and western Pacific, with G. hawaiiensis acknowledged as having the widest geographic distribution. Gibsmithia hawaiiensis can be easily distinguished from the other species in the genus by the presence of abundantcortical filaments extending the frond's surface giving the specimens a furry appearance. Based on new subtidal collections and existing herbarium specimens, a study was conducted on the genetic diversity of specimens identified as G. hawaiiensis. The three genetic markers employed (COI, rbcL and UPA) revealed the existence of a species-complex comprising two major lineages, with genetically distinct species. The Gibsmithia hawaiiensis complex exhibits high genetic diversity in the Indo-Malay region, with one lineage distributed throughout the E Indian Ocean and the W Pacific, and a widespread second lineage collected from East Africa to French Polynesia. In contrast, low genetic diversity characterizes members from isolated regions as the Hawaiian archipelago and the semi-closed Red Sea. The high divergence associated with poor resolution observed in geographically widespread lineages obscures species boundaries. The generitype and two new species forming the Gibsmithia hawaiiensis complex can be distinguished on the basis of anatomical characters that were previously regarded as morphological plasticity within G. hawaiiensis. Additional studies are underway to assess the large-scale phylogenetic and biogeographic patterns in Gibsmithia.
- Got Talent: Peyssonnelia globally showcases its skillsPublication . Gabriel, Daniela; Krayesky, David; Norris, James N.; Schmidt, William E.; Schils, Tom; Fredericq, SuzanneABSTRACT: The crust forming genus Peyssonnelia Decaisne is a taxon of great ecological importance, with some species involved in the establishment of rhodoliths. Comparative morphological and molecular analyses demonstrate a greater diversity of peyssonnelioid species than was previously reported. In chloroplast-encoded rbcL-based trees, species referred to as Peyssonnelia in the literature do not group together, but are scattered among other genera that were not currently placed in the Peyssonneliaceae. Two recently reported genera for the Gulf of Mexico, “ Polystrata” and Metapeyssonnelia, were excluded from the family, and together with a third clade are nested inside the Rhizophyllidaceae of the Dumontiaceae-complex. The Rhizophyllidaceae is newly reported for the Gulf of Mexico, with six species. The number of distinct species of Peyssonneliaceae now present in the Gulf of Mexico has increased from 6 to 21. On the other hand, the number of Peyssonnelia reported for the Azores was reduced from five to one species. Some species placed in Cruoriella and Cruoriopsis actually belong in the Peyssonneliaceae. New combinations are being proposed to accommodate known and new species in Cruoriella, and in two formerly monotypic genera, Sonderophycus and Riquetophycus. The Peyssonneliaceae forms a monophyletic assemblage that could not be maintained in the Gigartinales and thus a new order was constituted, Peyssonneliales, unrelated to the cluster of families centred around the Halymeniaceae of the Halymeniales, or the Gigartinaceae of the Gigartinales.
- «
- 1 (current)
- 2
- 3
- »