Analysis of plankton in the southern Great Barrier Reef: abundance and roles in throphodynamics

Wet biomass of principal plankton components and whole plankton standing stock were assessed in waters of the Heron Island ring reef and surrounding deep lagoon. Biomass of phytoplankton ranged between 30 to 120 mg m−3, without its pronounced depletion over the reef shallows. Picocyanobacteria and prochlorophyte algae contributed over 70% of this biomass. Biomass of bacterioplankton varied between 75 to 340 mg m−3, with its maximum over the reef flat. Biomass of planktonic protozoa's ciliates and zooflagellates ranged between 20 to 110 mg m−3. The daytime biomass of zooplankton varied between 490 to 1590 mg m−3in the deep lagoon in the zone of intense tidal currents. Over the reef shallows, it was 10–20 mg m−3. At night, it rose there up to 800 to 4000 mg m−3as the result of emerging demersal zooplankton from the benthic substrates. The time scale of nocturnal emerging by different taxa was also documented. Biomass of whole demersal zooplankton communities hiding by the daytime in bottom substrates at the reef flat was found to be over 100 g m−2. Problems of nutrition planktivore reef fauna related to the plankton production and abundance are discussed.

Download Full-text

Water circulation around Britomart Reef, Great Barrier Reef, during July 1979

Marine and Freshwater Research ◽

10.1071/mf9800415 ◽

1980 ◽

Vol 31 (4) ◽

pp. 415 ◽

Cited By ~ 13

Author(s):

E Wolanski ◽

M Jones

Keyword(s):

Great Barrier Reef ◽

Sea Level ◽

Central Region ◽

Reef Flat ◽

Water Circulation ◽

Barrier Reef ◽

Trade Winds ◽

Sea Breezes ◽

Coral Sea ◽

Sea Level Oscillations

Weather and currents at eight sites were measured and drogue trajectories obtained in July 1979 at Britomart Reef, a middle reef located at 18�16'S.,146� 38'E. in the central region of the Great Barrier Reef province. The longest current records (3 weeks) were obtained at two sites in passes between the Coral Sea and the Great Barrier Reef Lagoon where westerly currents modulated by tides were observed. Analysis of residuals also showed the importance of wind-driven secondary circulation. Non-tidal sea-level oscillations were very small. Shorter current records (1-10 days) at six sites in the lagoon and on the reef flat showed a predominant northerly flow, also modulated by tides and wind. A residual anticlockwise water circulation existed in the lagoon where flushing was controlled more by winds than by tides. The rise in sea level over the reef flat as a result of waves breaking was negligible. Temperature differences between air and water accounted for the cooling of the water column during the expedition. Constant south-east trade winds were experienced at the reef, while on land the wind was weaker. more variable, and often dominated by land-sea breezes.

Download Full-text

Population structure and trophic composition of the free-living nematodes inhabiting carbonate sands of Davies Reef, Great Barrier Reef, Australia

Marine and Freshwater Research ◽

10.1071/mf9860609 ◽

1986 ◽

Vol 37 (5) ◽

pp. 609 ◽

Cited By ~ 27

Author(s):

DM Alongi

Keyword(s):

Population Structure ◽

Great Barrier Reef ◽

Reef Flat ◽

Detrended Correspondence Analysis ◽

Reef Crest ◽

Barrier Reef ◽

Back Wall ◽

Free Living ◽

Shallow Lagoon ◽

Reef Zones

Population structure and trophic composition of free-living nematodes from carbonate sands within different functional zones (reef crest, reef flat and lagoon) of Davies Reef in the Great Barrier Reef were examined. At the reef crest (station C) and at a shallow lagoon area unprotected by the back wall of the reef flat (station G), sediments were subjected to intense wave action and supported significantly (P < 0.05) lower mean nematode densities (<60 individuals per 10 cm2) than sands within the other reef zones (100-400 individuals per 10 cm2). Mean nematode densities and numerical species richness were highest (P < 0.05) in a shallow lagoon habitat protected from hydrodynamic- induced disturbances by the back wall of the reef flat (station H). Differences in population densities among the reef zones were not related to water depth or sediment granulometry. Species diversity was low within the reef, with only six species present in deep lagoon sands co-inhabited by actively bioturbating ghost shrimps (Callianassa spp.). Normal classification, nodal analysis and detrended correspondence analysis indicated that faunal groups were distinct among the different reefal zones. Very coarse to medium sands at the reef crest and across the reef flat were inhabited primarily by omnivorous and epistrate-feeding nematodes. Most nematodes within the very fine to fine sands of the lagoon were non-selective or selective deposit feeders. Nematode community structure from the reef crest to the shallow lagoon appears to be determined primarily by sediment granulometry as controlled by reef hydrodynamics, whereas in the deep lagoon nematode communities are negatively affected by the presence of thalassinid ghost shrimps.

Download Full-text

Stratification in a small lagoon in the Great Barrier Reef

Marine and Freshwater Research ◽

10.1071/mf9840273 ◽

1984 ◽

Vol 35 (3) ◽

pp. 273 ◽

Cited By ~ 9

Author(s):

JC Andrews ◽

WC Dunlap ◽

NF Bellamy

Keyword(s):

Great Barrier Reef ◽

Time Scales ◽

Wind Stress ◽

Thermal Stratification ◽

Bottom Water ◽

Reef Flat ◽

Low Frequency ◽

Wind Vector ◽

Barrier Reef ◽

Lunar Synchronization

Temperatures were measured in a small lagoon in the windward reef flat of Davies Reef in the central Great Barrier Reef and examined on three time scales to gain three perspectives on thermal stratification and the trapping of bottom water. Profiling for stratification and dye revealed layering where bottom water was trapped and released by the successive capping and uncapping of the lagoon by a diurnal thermocline. A 1-month monitoring array revealed a solar synchronization, with the temperature of reef-flat water exceeding temperatures of lagoon water by up to 1 5�C within 1 h of midday, and lagoon stratification lagging this by 1 h. There was also a lunar synchronization with mixing proceeding during nocturnal rising tides. Lagoon surface and bottom temperatures were also monitored for 11 months. The amplitude of the diurnal stratification showed no coherence either with the amplitude of the tide (marked spring-neap tides) or with scalar wind stress. The low frequency amplitude of the diurnal oscillation was coherent with the longshore wind vector at periods near 3 6 days and in a band approximately from 10 to 40 days. Daily stratification increased when winds were poleward and decreased when winds were equatonvard. Events of flushing were separated on average by 9 h, but the most frequently observed separation was 5 h and only 10% of separations exceeded 18 h during the 11 months.

Download Full-text

Spatial, Seasonal and Secular Patterns in the Cover of Green Algae on Heron Reef Flat, Great Barrier Reef, Australia

Botanica Marina ◽

10.1515/botm.1996.39.1-6.415 ◽

1996 ◽

Vol 39 (1-6) ◽

Cited By ~ 7

Author(s):

R. W. Rogers

Keyword(s):

Great Barrier Reef ◽

Green Algae ◽

Reef Flat ◽

Barrier Reef

Download Full-text

Plankton of the central Great Barrier Reef: abundance, production and trophodynamic roles

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315410000597 ◽

2010 ◽

Vol 90 (6) ◽

pp. 1173-1187 ◽

Cited By ~ 11

Author(s):

Yu.I. Sorokin ◽

P.Yu. Sorokin

Keyword(s):

Great Barrier Reef ◽

Phytoplankton Biomass ◽

Trophic Status ◽

Benthic Communities ◽

Barrier Reef ◽

Pelagic Ecosystem ◽

Estuarine Area ◽

Mesozooplankton Biomass ◽

Zooplankton Density ◽

Plankton Production

The abundance, composition and metabolic activity of plankton were assessed in the Tribulation zone of the central Great Barrier Reef (16°–17°S). Wet phytoplankton biomass ranged in shallow reef waters from 30 to 70 mg m−3, and from 60 to 270 mg m−3in the deep lagoon and in the estuarine areas which are dominated by pico- and nano-algae. Wet bacterioplankton biomass varied from 70 to 290 mg m−3. Wet meroplankton biomass was less than 10 mg m−3. Wet daytime mesozooplankton biomass ranged from 100 to 300 mg m−3in the deep lagoon. In the estuarine area, it reached 400 to 1300 mg m−3and in the shallow inner lagoon of the Low Isles ring reef it varied from 10 to 30 mg m−3. Zooplankton density increased at night and was 3 to 5 fold greater in the deep lagoon, for about 2 orders of magnitude greater over the reef shallows and up to 3 orders of magnitude greater in mangrove habitats, due to the emergence of demersal components from the benthos. The biomass of zooplankton hidden in the benthic substrates during the day reached 10 to 40 g m−2. Pelagic primary production in the deep lagoon varied between 0.2 and 0.5 g C m−2 d−1. A calculation of the energy balance suggests that the basic energy source for heterotrophic plankton production in the deep lagoon is the organic matter exported from surrounding reef benthic communities and from mangroves. The trophic status of coral reef pelagic ecosystem might range from mesotrophic to eutrophic.

Download Full-text

Radiocarbon ages from the northern Great Barrier Reef

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1978.0095 ◽

1978 ◽

Vol 291 (1378) ◽

pp. 139-158 ◽

Cited By ~ 15

Keyword(s):

Great Barrier Reef ◽

Sea Level ◽

Time Scale ◽

Radiocarbon Dating ◽

Barrier Reef ◽

Laboratory Methods ◽

Reef Environments ◽

History Of ◽

Reef Islands ◽

Radiometric Ages

The aims of the 1973 Great Barrier Reef Expedition’s radiocarbon dating programmes were: (i) to collect live specimens from various reef environments to serve as modern reference standards; (ii) to evaluate the suitability of materials from the drilling, geomorphic and sediment programmes for dating purposes; and (iii) to date appropriate samples related to those programmes. The radiometric ages provide a time scale for the evolution of reefs and reef islands, and the history of sea level in the area. The purpose of this paper is to report results of all ages determined to date, to describe field and laboratory methods used and to assess the reliability of the ages in terms of (i) the actual materials dated and (ii) the geomorphic, ecological or stratigraphic units from which the samples were obtained. Seventy-nine determinations based on 74 samples are reported. No interpretation of the results is attempted here.

Download Full-text

Dynamics of seawater carbonate chemistry, production, and calcification of a coral reef flat, central Great Barrier Reef

Biogeosciences ◽

10.5194/bg-10-6747-2013 ◽

2013 ◽

Vol 10 (10) ◽

pp. 6747-6758 ◽

Cited By ~ 83

Author(s):

R. Albright ◽

C. Langdon ◽

K. R. N. Anthony

Keyword(s):

Coral Reef ◽

Coral Reefs ◽

Great Barrier Reef ◽

Reef Flat ◽

Global Scale ◽

Barrier Reef ◽

Carbonate Chemistry ◽

Saturation State ◽

Diel Cycles ◽

Seawater Carbonate Chemistry

Abstract. Ocean acidification is projected to shift coral reefs from a state of net accretion to one of net dissolution this century. Presently, our ability to predict global-scale changes to coral reef calcification is limited by insufficient data relating seawater carbonate chemistry parameters to in situ rates of reef calcification. Here, we investigate diel and seasonal trends in carbonate chemistry of the Davies Reef flat in the central Great Barrier Reef and relate these trends to benthic carbon fluxes by quantifying net ecosystem calcification (nec) and net community production (ncp). Results show that seawater carbonate chemistry of the Davies Reef flat is highly variable over both diel and seasonal cycles. pH (total scale) ranged from 7.92 to 8.17, pCO2 ranged from 272 to 542 μatm, and aragonite saturation state (Ωarag) ranged from 2.9 to 4.1. Diel cycles in carbonate chemistry were primarily driven by ncp, and warming explained 35% and 47% of the seasonal shifts in pCO2 and pH, respectively. Daytime ncp averaged 37 ± 19 mmol C m−2 h−1 in summer and 33 ± 13 mmol C m−2 h−1 in winter; nighttime ncp averaged −30 ± 25 and −7 ± 6 mmol C m−2 h−1 in summer and winter, respectively. Daytime nec averaged 11 ± 4 mmol CaCO3 m−2 h−1 in summer and 8 ± 3 mmol CaCO3 m−2 h−1 in winter, whereas nighttime nec averaged 2 ± 4 mmol and −1 ± 3 mmol CaCO3 m−2 h−1 in summer and winter, respectively. Net ecosystem calcification was highly sensitive to changes in Ωarag for both seasons, indicating that relatively small shifts in Ωarag may drive measurable shifts in calcification rates, and hence carbon budgets, of coral reefs throughout the year.

Download Full-text

Influence of hydrodynamic energy on Holocene reef flat accretion, Great Barrier Reef

Quaternary Research ◽

10.1016/j.yqres.2015.11.002 ◽

2016 ◽

Vol 85 (1) ◽

pp. 44-53 ◽

Cited By ~ 14

Author(s):

Belinda Dechnik ◽

Jody M. Webster ◽

Luke Nothdurft ◽

Gregory E. Webb ◽

Jian-xin Zhao ◽

...

Keyword(s):

Great Barrier Reef ◽

Reef Flat ◽

Wind Wave ◽

Great Variability ◽

Barrier Reef ◽

The Past ◽

Accretion Rates ◽

Main Driver ◽

Reef Zones ◽

Hydrodynamic Energy

AbstractThe response of platform reefs to sea-level stabilization over the past 6 ka is well established for the Great Barrier Reef (GBR), with reefs typically accreting laterally from windward to leeward. However, these observations are based on few cores spread across reef zones and may not accurately reflect a reef's true accretional response to the Holocene stillstand. We present a new record of reef accretion based on 49 U/Th ages from Heron and One Tree reefs in conjunction with re-analyzed data from 14 reefs across the GBR. We demonstrate that hydrodynamic energy is the main driver of accretional direction; exposed reefs accreted primarily lagoon-ward while protected reefs accreted seawards, contrary to the traditional growth model in the GBR. Lateral accretion rates varied from 86.3 m/ka–42.4 m/ka on the exposed One Tree windward reef and 68.35 m/ka–15.7 m/ka on the protected leeward Heron reef, suggesting that wind/wave energy is not a dominant control on lateral accretion rates. This represents the most comprehensive statement of lateral accretion direction and rates from the mid-outer platform reefs of the GBR, confirming great variability in reef flat growth both within and between reef margins over the last 6 ka, and highlighting the need for closely-spaced transects.

Download Full-text