Leaf Ultrastructure and δ13C Values of Three Seagrasses from the Great Barrier Reef

1976 ◽  
Vol 3 (1) ◽  
pp. 9 ◽  
Author(s):  
ME Doohan ◽  
EH Newcomb
Keyword(s):  
Great Barrier Reef ◽  
Leaf Anatomy ◽  
Co2 Assimilation ◽  
Land Plants ◽  
Vascular Bundles ◽  
Barrier Reef ◽  
Thalassia Hemprichii ◽  
Mesophyll Cells ◽  
Δ13c Values ◽  
Abundant Cytoplasm

Leaf anatomy, ultrastructure and 13C/12C ratios were studied in three species of seagrasses collected on the Great Barrier Reef: Cymodocea rotundata Ehrenb. & Hempr., C. serrulata (R. Br.) Aschers. & Magnus, and Thalassia hemprichii (Ehrenb.) Aschers. Although they belong to two different mono- cotyledonous families, the three species are quite similar in the characteristics studied. Cells of the epidermal layer of the leaves are extremely thick-walled and have abundant cytoplasm with large chloroplasts and numerous mitochondria. The chloroplast-microbody profile ratio is c. 4-5 : 1 and the mitochondrion-microbody ratio 10-15 : 1. The epidermal cells resemble transfer cells in having a pronounced development of ingrowths on the radial walls. The mesophyll cells have thin walls, a large central vacuole and a thin layer of cytoplasm with relatively few organelles. There is no specialization of mesophyll cells around the vascular bundles. The δ13C values for the three sea- grasses range from -6.90, to - 12.40, and thus are characteristic of C4 land plants, although the seagrasses do not conform to the C4 syndrome in leaf anatomy or ultrastructure. It is not possible to place the seagrasses in either the C3, C4 or crassulacean acid metabolism category of land plants, but whether they constitute yet a fourth group with respect to characteristics related to CO2 assimilation is not clear.

δ13C Values in Marine Organisms from the Great Barrier Reef

1976 ◽  
Vol 3 (1) ◽  
pp. 25 ◽  
Author(s):  
CC Black ◽  
MM Bender
Keyword(s):  
Great Barrier Reef ◽  
Sea Water ◽  
Isotope Composition ◽  
Marine Ecosystem ◽  
Carbon Assimilation ◽  
Marine Organisms ◽  
Barrier Reef ◽  
Terrestrial Plants ◽  
Δ13c Values ◽  
Photosynthetic Organisms

The carbon isotope composition of marine organisms collected on the Great Barrier Reef near Lizard Island, Australia, was determined. Emphasis was placed on photosynthetic organisms including algae, zooxanthellae, angiosperms and symbiotic systems. The photosynthetic organisms had δ13C values ranging from -5.1 to -32.40,. Symbiotic systems and non-photosynthetic organisms had δ13C values within this range. CO2 released by acid treatment from coral, shell and cone carbonates had δ13C values between + 3.9 and - 2.70,. The results with photosynthetic tissue generally are interpreted in comparison to terrestrial plants as showing a major assimilation of CO2 into organic compounds via ribulosebisphosphate carboxylase in the marine ecosystem. However, a few photosynthetic organisms exhibited δ13C values between - 5.10, and - 110, and could be assimilating CO2 via phosphoenolpyruvate carboxylase. A unified scheme is presented for the pathway of carbon assimilation in the reef from the sea water through both autotrophic and heterotrophic metabolism, and finally to calcification.

Management of Water Quality in the Great Barrier Reef Marine Park

1989 ◽  
Vol 21 (2) ◽  
pp. 31-38 ◽  
Author(s):  
Simon Woodley
Keyword(s):  
Water Quality ◽  
Coral Reef ◽  
Great Barrier Reef ◽  
Barrier Reef ◽  
Management Issue ◽  
Reef System ◽  
Marine Park ◽  
World Heritage List ◽  
The World ◽  
Coral Reef System

The Great Barrier Reef is the largest coral reef system in the world. It is recognised and appreciated worldwide as a unique environment and for this reason has been inscribed on the World Heritage List. The Reef is economically-important to Queensland and Australia, supporting substantial tourism and fishing industries. Management of the Great Barrier Reef to ensure conservation of its natural qualities in perpetuity is achieved through the establishment of the Great Barrier Reef Marine Park. The maintenance of water quality to protect the reef and the industries which depend on it is becoming an increasingly important management issue requiring better knowledge and possibly new standards of treatment and discharge.

Circulation and water mass characteristics of the southern Great Barrier Reef

1994 ◽  
Vol 45 (1) ◽  
pp. 1 ◽  
Author(s):  
JH Middleton ◽  
P Coutis ◽  
DA Griffin ◽  
A Macks ◽  
A McTaggart ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Heat Loss ◽  
Barrier Reef ◽  
Low Oxygen ◽  
Geostrophic Balance ◽  
Shelf Slope ◽  
High Nutrient ◽  
Slope Currents ◽  
North And South ◽  
Upper Slope

Data acquired during a winter (May) cruise of the RV Franklin to the southern Great Barrier Reef indicate that the dynamics of the shelf/slope region are governed by the tides, the poleward-flowing East Australian Current (EAC), and the complex topography. Over the Marion Plateau in water deeper than - 100 m, the EAC appears to drive a slow clockwise circulation. Tides appear to be primarily responsible for shelf/slope currents in the upper layers, with evidence of nutrient uplift from the upper slope to the outer shelf proper in the Capricorn Channel. Elsewhere, the bottom Ekrnan flux of the strongly poleward-flowing EAC enhances the sloping isotherms associated with the longshore geostrophic balance, pumping nutrient-rich waters from depth to the upper continental slope. Generally, shelf waters are cooler than oceanic waters as a consequence of surface heat loss by radiation. A combination of heat loss and evaporation from waters flowing in the shallows of the Great Sandy Strait appears to result in denser 'winter mangrove waters' exporting low-oxygen, high-nutrient waters onto the shelf both north and south of Fraser Island; these subsequently mix with shelf waters and finally flow offshore at - 100 m depth, just above the salinity-maximum layer, causing anomalous nutrient values in the region of Fraser Island.

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