Spatio-temporal variability in surface Chlorophyll distribution in the Central Great Barrier Reef as derived from CZCS imagery

1990 ◽  
Vol 41 (3) ◽  
pp. 313 ◽  
Author(s):  
AJ Gabric ◽  
P Hoffenberg ◽  
W Boughton
Keyword(s):  
Great Barrier Reef ◽  
Temporal Variability ◽  
Large Scale ◽  
Nutrient Loads ◽  
Barrier Reef ◽  
Phytoplankton Abundance ◽  
Wet Season ◽  
Chlorophyll Distribution ◽  
Consistent Feature ◽  
Spatio Temporal

A series of Coastal Zone Colour Scanner (CZCS) images has been used to compare the surface phytoplankton variation in the central Great Barrier Reef waters over the period 1979-81. Near- concurrent field data have been obtained for all the scenes so that approximate chlorophyll concentrations have been applied in the image classification. A consistent feature in the dry-season chlorophyll distribution is a cross shelf gradient with high chlorophyll levels inshore and lower levels in the mid-lagoonal waters increasing to higher concentrations in the reef matrix. The effects of higher nutrient loads in the wet season are also evident, although correlation between riverine discharge and phytoplankton abundance in the lagoon is problematic. In fact, a large scale 'bloom' event occurs before the start of the 1980-81 wet season and may be related to wind resuspension of sedimentary nutrients.

scholarly journals High spatio-temporal variability in Acroporidae settlement to inshore reefs of the Great Barrier Reef

PLoS ONE ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. e0209771 ◽  
Author(s):  
Johnston Davidson ◽  
Angus Thompson ◽  
Murray Logan ◽  
Britta Schaffelke
Keyword(s):  
Great Barrier Reef ◽  
Temporal Variability ◽  
Barrier Reef ◽  
Spatio Temporal

scholarly journals Spatio-temporal patterns in the postglacial flooding of the Great Barrier Reef shelf, Australia

2019 ◽  
Vol 173 ◽  
pp. 13-26 ◽  
Author(s):  
Gustavo Hinestrosa ◽  
Jody M. Webster ◽  
Robin J. Beaman
Keyword(s):  
Great Barrier Reef ◽  
Temporal Patterns ◽  
Barrier Reef ◽  
Spatio Temporal

Dynamics of Aeolian Sand Streamers and Airflow Turbulence over a Beach Surface

2021 ◽  
Author(s):  
Andreas Baas
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Temporal Variability ◽  
Large Scale ◽  
Sonic Anemometer ◽  
Dynamic Structure ◽  
Sand Transport ◽  
Video Imagery ◽  
Spatio Temporal ◽  
The Impact

<p>Sand transport by wind over granular beds displays dynamic structure and organisation in the form of streamers (aka ‘sand snakes’) that appear, meander and intertwine, and then dissipate as they are advected downwind. These patterns of saltating grain populations are thought to be initiated and controlled by coherent flow structures in the turbulent boundary layer wind that scrape over the bed surface raking up sand into entrainment. Streamer behaviour is thus fundamental to understanding sand transport dynamics, in particular its strong spatio-temporal variability, and is equally relevant to granular transport in other geophysical flows (fluvial, submarine).</p><p>This paper presents findings on streamer dynamics and associated wind turbulence observed in a field experiment on a beach, with measurements from 30Hz video-imagery using Large-Scale Particle Image Velocimetry (LS-PIV), combined with 50Hz wind measurements from 3D sonic anemometry and co-located sand transport rate monitoring using an array of laser particle counters (‘Wenglors’), all taking place over an area of ~10 m<sup>2</sup> and over periods of several minutes. The video imagery was used to identify when and where streamers advected past the sonic anemometer and laser sensors so that relationships could be detected between the passage of turbulence structures in the airflow and the length- and time-scales, propagation speeds, and sand transport intensities of associated streamers. The findings form the basis for a phenomenological model of streamer dynamics under turbulent boundary layer flows that predicts the impact of spatio-temporal variability on local measurement of sand transport.</p>

Turbidity in the northern Great Barrier Reef lagoon in the wet season, March 1989

1994 ◽  
Vol 45 (4) ◽  
pp. 585 ◽  
Author(s):  
LJ Hamilton
Keyword(s):  
Great Barrier Reef ◽  
Attenuation Coefficient ◽  
Quantitative Relation ◽  
Barrier Reef ◽  
Wet Season ◽  
Secchi Disc ◽  
Reef Lagoon ◽  
Secchi Disc Depth ◽  
Beam Attenuation ◽  
Beam Attenuation Coefficient

In 1989, a typical wet season was experienced in northern Queensland, with low winds and long calm periods. Turbidity in upper waters of the Great Barrier Reef lagoon broadly had a simple distribution that could be modelled from bottom depth contour values alone, without introducing wind speed or bottom type. In the absence of major storm and cyclone events, this result appears to be general, based on the similarity between March 1989 survey data and Secchi disc climatology. The simple distribution arises because the main turbidity sources are riverine discharges, with little entrainment of bottom sediment into the upper column, except in shallower waters. Fresh, highly turbid riverine influxes are generally confined close inshore, with salinity and Secchi contours parallel to shore, forming cross-shelf gradients. A semi-quantitative relation was found between sea surface colour and Secchi disc depth. Examination of nephelometric turbidity stratification showed that satellite and Secchi data should be more useful for subsurface turbidity inference between Cooktown and Innisfail than in Princess Charlotte Bay, with horizontal and vertical stratifications, respectively, observed in those areas. Highest nephelometric turbidity was seen from Cooktown to Innisfail. Beam attenuation coefficient in oceanic waters outside the reef appeared to be dominated by absorption, with lagoon waters influenced by scattering. A method is suggested to enable approximate transfer of beam attenuation coefficient measured by a transmissometer operating at a single wavelength to beam attenuation coefficient at other wavelengths, using coincident measurements of Secchi disc depths made with filters.

Larval dispersal simulations: correlation with the crown-of-thorns starfish outbreaks database

1992 ◽  
Vol 43 (3) ◽  
pp. 569 ◽  
Author(s):  
MK James ◽  
JP Scandol
Keyword(s):  
Great Barrier Reef ◽  
Larval Dispersal ◽  
Large Scale ◽  
Numerical Models ◽  
Temporal Distribution ◽  
Research Programme ◽  
Strong Positive Correlation ◽  
Barrier Reef ◽  
Central Hypothesis ◽  
Scale Population

The work reported in this paper is a further development of results from a research programme whose principal objective is to achieve an understanding of the large-scale population dynamics of Acanthaster planci. The research is based on the development and use of numerical models of hydrodynamics and resulting larval dispersal throughout a large portion of the Great Barrier Reef. It is chiefly concerned with the large-scale statistical patterns of larval dispersal, the central hypothesis being that passive hydrodynamic dispersal plays an important role in the recruitment process. The present aim is to examine more closely than has been done before the consistencies between the modelling results and the database of recorded observations of crown-of-thorns starfish outbreaks. Reefs in the Cairns and Central Sections of the Great Barrier Reef Marine Park that were recorded as carrying active outbreaks during the period 1979-89 were used as sources in a programme of intensive simulations of Acanthaster larval dispersal under forcing by the wind, tidal action and the East Australian Current. The resulting broad-scale patterns of larval dispersal were found to be in strong qualitative agreement with the observed spatial and temporal distribution of adult Acanthaster populations. Statistical analysis of the results revealed a strong positive correlation between potential recruitment on surveyed reefs, as estimated by the dispersal simulations, and the observed presence of outbreak populations on those reefs. The correlation was particularly strong when different cross-shelf zones were considered separately.

Sign in / Sign up

Export Citation Format

Share Document