Ammonia and phosphate excretion by zooplankton from the inshore waters of the Great Barrier Reef. II. Their in situ contributions to nutrient regeneration

1982 ◽  
Vol 33 (4) ◽  
pp. 683 ◽  
Author(s):  
T Ikeda ◽  
JH Carleton ◽  
AW Mitchell ◽  
P Dixon
Keyword(s):  
Great Barrier Reef ◽  
Laboratory Data ◽  
Ammonia Excretion ◽  
Barrier Reef ◽  
Nutrient Regeneration ◽  
Bottom Community ◽  
Phosphate Excretion ◽  
Inshore Waters ◽  
Zooplankton Excretion ◽  
Excretion Rates

Zooplankton excretion was estimated by combining biomass data with experimental laboratory data on excretion rates at three stations, characterized by low nutrient levels, in the inshore waters of the Great Barrier Reef. Hourly ammonia excretion (as nitrogen) by net zooplankton (>205 �) was calculated to range from 11.9 to 22.6 � m-3 or from 1.6 to 5.0 g m-2 per year, and hourly phosphate excretion (as phosphorus) from 1.4 to 2.8 � m-3 or from 0.16 to 0.63 g m-2 per year. Hourly excretion of ammonia by microzooplankton ( < 205 �) was calculated to be 2.6 � m-3 (as nitrogen) and of phosphate 0.55 � m-3 (as phosphorus), values that were 15 and 27% of the excretion by net zooplankton, respectively. Combined excretion rates by net zooplankton and microzooplankton could supply only 9.0-29.2% of the nitrogen and 6.6-25.6% of the phosphorus for an assumed yearly primary production of carbon of 100 g m-2 (= 17.6 g m-2 of nitrogen and 2.5 g m-2 of phosphorus). Calculations from an empirical equation relating temperature to oxygen consumption by a bottom community indicated a high potential for benthic nutrient regeneration in reef inshore waters (27.1 g m-2 per year, as nitrogen). The bottom community therefore appears to be the most important source of nutrient regeneration within the area studied.

Ammonia and Inorganic phosphate excretion by zooplankton from inshore waters of the Great Barrier Reef, Queensland. I. Relationship between excretion rates and body size

1982 ◽  
Vol 33 (1) ◽  
pp. 55 ◽  
Author(s):  
T Ikeda ◽  
E Hing Fay ◽  
SA Hutchinson ◽  
GM Boto
Keyword(s):  
Great Barrier Reef ◽  
Warm Season ◽  
Ammonia Excretion ◽  
Dry Weight ◽  
Cold Season ◽  
Barrier Reef ◽  
Experimental Conditions ◽  
Phosphate Excretion ◽  
Inshore Waters ◽  
Excretion Rates

Ammonia and phosphate excretion rates were measured on various copepods and some ctenophores, siphonophores, decapod larvae, mollusc larvae, polychaete larvae, chaetognaths and appendicularians from inshore waters of the Great Barrier Reef during warm and cold seasons. Regression analyses showed high correlations between the excretion rate and body weight of zooplankton: in the warm season, log yn = 0.518 + 0.525 log x (n = 348. r = 0.612) log yp = -0.174 + 0.429 log x (n=117, r=0.570), and in the cold season, log yn = 0.186 + 0.518 log x (n = 268, r = 0,777) log yp = -1.002 + 0.740 log x (n = 255, r = 0.694), where yn is ammonia excretion (nanograms N per animal per hour), yp is phosphate excretion (nanograms P per animal per hour), x is body dry weight (micrograms per animal); n is the number of measurements, and r is the correlation coefficient. Since the two regression lines for ammonia excretion were parallel a Q10 value of 2.53 was calculated from the results of warm and cold seasons. This calculation was not possible for the phosphate excretion because the regression lines between the seasons were not parallel. The mean ratio of ammonia excretion to phosphate excretion (N:P ratio, by atoms) was 28.56 in the warm season and 24.48 in the cold season. The present results were compared with those of other workers who used zooplankton from different seas, and the effects of experimental conditions, such as injury of specimens, container size, incubation time and feeding on the excretion rates are discussed.

Spatial and temporal patterns of near-surface chlorophyll a in the Great Barrier Reef lagoon

2007 ◽  
Vol 58 (4) ◽  
pp. 342 ◽  
Author(s):  
J. Brodie ◽  
G. De'ath ◽  
M. Devlin ◽  
M. Furnas ◽  
M. Wright
Keyword(s):  
Great Barrier Reef ◽  
Chlorophyll A ◽  
Agricultural Development ◽  
Monitoring Program ◽  
Barrier Reef ◽  
Spatial And Temporal Patterns ◽  
Wet Season ◽  
Near Surface ◽  
Nutrient Delivery ◽  
Inshore Waters

Surface chlorophyll a concentrations in the Great Barrier Reef (GBR) lagoon were monitored at individual stations for periods of 6 to 12 years. The monitoring program was established to detect spatial and temporal changes in water quality resulting from increased loads of nutrients exported from the catchments adjoining the GBR. Sampling occurred monthly at up to 86 sites that were located in transects across the width of the continental shelf. In the central and southern GBR (16–21°S), there was a persistent cross-shelf chlorophyll a gradient, with higher concentrations near the coast. No cross-shelf gradient was observed in the far northern GBR (12–15°S). Mean chlorophyll a concentrations in the far northern GBR (0.23 µg L–1) were less than half those in the south and central GBR (0.54 µg L–1). Chlorophyll a varied seasonally within regions, with mean summer-wet season (December–April) concentrations ~50% greater than those in the winter-dry season (May–November). Sub-annual, inter-annual and event-related variations in chlorophyll a concentrations were observed in several zones. Multi-year patterns in concentrations suggest that relatively short (5–8 years) time series may give spurious estimates of secular trends. Higher chlorophyll a concentrations in inshore waters south of 16°S were most likely related to the levels of river nutrient delivery associated with agricultural development on adjacent catchments.

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.

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