Algal Taxa (algal + taxa)

Distribution by Scientific Domains


Selected Abstracts


163 Identification of Euglenoids That Produce Ichthyotoxin(S) (Euglenophyta)

JOURNAL OF PHYCOLOGY, Issue 2003
R. E. Triemer
Diatoms, dinoflagellates, pelagiophytes, prymnesiophytes, and cyanobacteria are the only divisions of microalgae known to produce toxins. We now report toxin production by freshwater members of the genus Euglena. Fish mortalities (sheepshead minnows, catfish, striped bass, and tilapia) have been observed following exposure in the field to Euglena blooms and in the laboratory when exposed to unialgal isolates of two species of Euglena (E. sanguinea Ehrenberg and E. granulata (Klebs) Lemm.). Three toxic fractions have been isolated from unialgal isolates of both species, and include both water soluble and lipophilic compounds having ichthyotoxic activity. The toxins are stable at ,80°C for at least 60 days and are heat stable to 30°C. Erratic swimming behavior of fish suggests a neurological toxin. This is the first report of fish kills by any freshwater algal taxa from both field and laboratory studies. [source]


BIOGEOGRAPHY OF MARINE RED ALGAE: MYTHS AND REALITIES

JOURNAL OF PHYCOLOGY, Issue 2001
Article first published online: 24 SEP 200
Hommersand, M. H. Department of Biology, Coker Hall, University of North Carolina, Chapel Hill, NC 27599-3280 USA Theories about the geographical distribution of marine algae fall roughly into two categories: (1) a concept of biogeographical regions in which algal distribution is determined primarily by growth, reproductive and lethal temperature boundaries (Setchell, van den Hoek, Breeman, Lüning) and (2) an historical perspective in which distribution is determined primarily by patterns of dispersal and the establishment of barriers to dispersal (vicariance biogeography) (Svedelius, Garbary, Lindstrom, Hommersand). Setchell proposed the 5° isotherm rule in 1920, and in 1924 Svedelius advocated a worldwide distribution for tropical and subtropical groups followed by discontinuous distribution upon closure of the connection between the Indian Ocean and Mediterranean Sea and, later, between North and South America (Wegener's theory). Transarctic dispersal routes have received special attention in recent years (Lindstrom, Lüning, van Oppen, Olsen, Stam), as have special relationships between Australasia, South Africa and South America (Hommersand). Less well understood are the climatic changes that have taken place in the Cenozoic which are strategic to an understanding vicariant biogeography. The advent of molecular methods combined with the tools of phylogenetic systematics now make it possible to identify ancestral taxa, test the consistency of tree topologies, and calculate mean branch lengths between sister lineages diverging from an interior node of a tree. With such methods it may be possible to infer ancestral areas, identify dispersal pathways, determine the chronology of isolating events, assess the impact of multiple invasions, and generally relate dispersal and vicariance models to phylogenetic hypotheses for red, brown and green algal taxa. [source]


SNOW ALGAE OF THE WINDMILL ISLANDS, CONTINENTAL ANTARCTICA: DESMOTETRA AUREOSPORA, SP.

JOURNAL OF PHYCOLOGY, Issue 1 2001

Two cryophilic Desmotetra species, D. aureospora, sp. nov., and D. antarctica (Fritsch) Ling appear to be unique to the southern hemisphere snow ecosystem, or at least to the Windmill Island region, Antarctica. They have not been encountered in previous extensive studies of the Arctic and northern alpine regions. Also unusual are the higher pH (6.8 and 7.8) and conductivities of 279 ,S·cm,1 and 426 ,S·cm,1 for habitat conditions of D. antarctica that can be attributed to the influence of penguin guano. Both species are characterized by cells enveloped in individual mucilage layers, 1,3 contractile vacuoles, and a cup-shaped chloroplast containing a diffuse pyrenoid. The cells divided in three planes to form cubical loosely aggregated green cell packages embedded in mucilage. Vegetative cells of the two species cannot be distinguished with certainty; however, their zygospores are very different. Desmotetra aureospora has spherical, smooth-walled, golden zygospores, whereas D. antarctica has pale, yellow green, aereolate zygospores. Mucilage stalk morphology of cells in stationary-phase cultures can also be used to separate the two species. Zygospores of D. antarctica have previously been identified as the snow alga Trochiscia antarctica Fritsch. Both species are currently maintained in culture at the Australian Antarctic Division. The cultures did not grow at temperatures above 15° C. The two species are compared with the soil alga D. stigmatica (Deason) Deason et Floyd, the only other species in the genus, and also with Chlorosarcina stigmatica Deason strain T105. Results show that the three Desmotetra species form a natural group and that the absence or presence of a wall on the zoospore is of dubious value in classifications of green algal taxa above the species level. [source]


Biogeographical and ecological context for managing threats to coral and rocky reef communities in the Lord Howe Island Marine Park, south-western Pacific

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010
Graham J. Edgar
Abstract 1.Quantitative subtidal surveys of fishes, macro-invertebrates and sessile organisms at 33 sites within the Lord Howe Island Marine Park revealed a rich fauna and flora, including 164 fishes, 40 mobile invertebrate taxa, 53 coral and other sessile invertebrate taxa, 32 algal taxa, and two seagrasses. The biota in this newly-zoned marine park was overwhelmingly tropical when species lists were tabulated; however, species with distributions centred on temperate coasts of eastern Australia and New Zealand occurred in disproportionately high densities compared with the tropical species. 2.Lord Howe Island reefs were generally in good condition. Virtually no bleached coral was observed (0.2% of the reef surface; 0.8% of total hard coral cover). Living scleractinian coral comprised the predominant group of organisms growing on reef surfaces, with 25.5% cover overall. Other major taxa observed were brown algae (18.8% cover) and red algae (16.9% cover). 3.Three distinctive community types were identified within the marine park,coral reefs, macroalgal beds and an offshore/open coast community. The distribution of these community types was strongly related to wave exposure, as indicated by an extremely high correlation with the first principal coordinates axis for biotic data (R2=0.80). 4.The close (<3,km) proximity of tropical coral and temperate macroalgal community types off Lord Howe Island is highly unusual, with localized patterns of nutrient enrichment suggested as the primary cause. The macroalgal community type is only known from a small area off the south-western coast that is not protected from fishing. This community is considered highly susceptible to threats because of potential impacts of global warming and the possibility of expansion of sea urchin barrens. Coral bleaching and ocean acidification associated with global climate change also threaten the coral reef community, which includes relatively high numbers of endemic and near endemic fish species. Copyright © 2009 John Wiley & Sons, Ltd. [source]