Blue-green algae associated with ascidians of the Great Barrier Reef

Nature ◽  
1975 ◽  
Vol 253 (5492) ◽  
pp. 533-534 ◽  
Author(s):  
ELDON H. NEWCOMB ◽  
THOMAS D. PUGH
Keyword(s):  
Great Barrier Reef ◽  
Green Algae ◽  
Barrier Reef ◽  
Blue Green Algae

Nitrogen Fixation by Blue-green Algae of the Lizard Island Area of the Great Barrier Reef

1976 ◽  
Vol 3 (1) ◽  
pp. 41 ◽  
Author(s):  
RH Burris
Keyword(s):  
Great Barrier Reef ◽  
Green Algae ◽  
Rock Surface ◽  
Barrier Reef ◽  
Fixed Nitrogen ◽  
Blue Green Algae ◽  
Average Ratio ◽  
Island Area ◽  
Partial Pressures ◽  
Lizard Island

Reduction of acetylene and 15N2 by blue-green algae and other organisms from the Lizard Island area of the Great Barrier Reef was measured. The effects of storage of the algae, the partial pressures of acetylene and oxygen, and light intensity were studied. The average ratio of acetylene to N2 reduced was 1.9. With this factor, it was calculated that 6.8 - 30.6 kg nitrogen was fixed annually per hectare of rock surface in the intertidal zone. Fixation of nitrogen by blue-green algae can contribute a substantial portion of the fixed nitrogen required for maintaining the flora and fauna of the coral reef community.

Feeding of Holothuria atra and Stichopus chloronotus on bacteria, organic carbon and organic nitrogen in sediments of the Great Barrier Reef

1982 ◽  
Vol 33 (2) ◽  
pp. 255 ◽  
Author(s):  
DJW Moriarty
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Great Barrier Reef ◽  
Organic Nitrogen ◽  
Bacterial Biomass ◽  
Gut Contents ◽  
Barrier Reef ◽  
Muramic Acid ◽  
Blue Green Algae ◽  
Carbon And Nitrogen

Organic carbon and nitrogen and bacterial biomass were measured in the sediments and gut contents of H. atra and S. chloronotuson the Great Barrier Reef. Organic carbon averaged from 3.4 to 4.7 mg g-1, organic nitrogen from 0.20 to 0.31 mg g-1 and muramic acid from 1.4 to 3.3�g g-1 dry weight of surface sandy sediments. Bacterial biomass, determined by muramic acid measurements, averaged 3-8% of organic carbon in the sediments; blue-green algae accounted for 3-7% of muramic acid. Significantly higher values of organic carbon and nitrogen and muramic acid were found in foregut contents of the holothurians, indicating selective feeding on organically rich components of the sediment. Carbon values were 16-34% higher in the foregut than in the sediment. nitrogen values 35-111% higher and muramic acid values 33-300% higher. These values indicate that bacteria and nitrogenous components of the organic matter were selectively eaten. Values for organic carbon and nitrogen and muramic acid were generally lower in the hindgut than in the foregut, due to digestion and assimilation. Assimilation efficiencies averaged 30% for organic carbon, 40% for organic nitrogen and 30-40% for muramic acid (bacteria). Detritus (non-living matter) probably constituted 60-80% of the organic matter in the sediment and thus the food of the holothurians.

Carbonate Dehydratase in Marine Organisms of the Great Barrier Reef

1976 ◽  
Vol 3 (1) ◽  
pp. 113 ◽  
Author(s):  
D Graham ◽  
RM Smillie
Keyword(s):  
Calcium Carbonate ◽  
Great Barrier Reef ◽  
Sea Water ◽  
Carbonic Anhydrase Activity ◽  
Enzymic Activity ◽  
Barrier Reef ◽  
Pocillopora Damicornis ◽  
Blue Green Algae ◽  
Calcium Carbonate Deposition ◽  
Dehydratase Activity

Carbonate dehydratase (EC 4.2.1.1, other name 'carbonic anhydrase') activity was found in 28 of 29 species of marine algae and angiosperms and in a mixed culture of phytoplankton collected in the vicinity of Lizard Island on the Great Barrier Reef of Australia. The species included 13 member- of the Chlorophyta, 4 of the Phaeophyta, 7 of the Rhodophyta, 2 of the Cyanophyta and 3 subs merged marine angiosperms. One of the two blue-green algae showed no detectable enzymic activity. The levels of activity ranged from 100 to 4800 units per milligram chlorophyll and were generally comparable with those of terrestrial angiosperms based on chlorophyll content, but were only a small fraction when compared on the basis of fresh weight. Culture of the green alga Chlorodesmis fastigiata in 'CO2-free' sea water (1.4 mg CO2 per litre) for 4 h did not lead to an induction of carbonate dehydratase activity. Some of the species of algae producing calcium carbonate contained the highest activities recorded but others had low activities. A correlation between high carbonate dehydratase activity and calcium carbonate deposition could not be adduced. Symbiotic zooxanthellae (Gymnodinium microadriaticum) of the hard coral Pocillopora damicornis and the clam Tridacna maxima also contained carbonate dehydratase (940 and 340 units per milligram chlorophyll, respectively). The host tissues contained about five times the activity of their respective zooxanthellae.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

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