Benthic community composition influences within-habitat variation in macroalgal browsing on the Great Barrier Reef

2010 ◽  
Vol 61 (9) ◽  
pp. 999 ◽  
Author(s):  
C. Cvitanovic ◽  
A. S. Hoey
Keyword(s):  
Coral Reefs ◽  
Great Barrier Reef ◽  
Benthic Community ◽  
Spatial Scales ◽  
Structural Complexity ◽  
Barrier Reef ◽  
Removal Rates ◽  
Ecological Processes ◽  
Habitat Variation ◽  
Benthic Composition

The removal of macroalgae by herbivores is fundamental to the long-term persistence of coral reefs. Variation in macroalgal browsing has been documented across a range of spatial scales on coral reefs; however, few studies have examined the factors that influence within-habitat rates of herbivory. The aim of the present study was to quantify herbivory on two species of Sargassum across three bays on an inshore island in the central Great Barrier Reef (GBR), and to determine whether these removal rates were related to the benthic composition or herbivorous fish communities. Removal rates of Sargassum differed significantly among bays, with removal rates in the southern bay (66.9–83.0% per 3 h) being approximately double that of the two other bays (29.2–38.5% per 3 h). The removal rates displayed a direct relationship with the benthic community structure, in particular the cover of macroalgae and live plate corals. Although it is difficult to determine whether these relationships are related to the availability of food resources or the structural complexity of the substratum, they highlight the potential influence of benthic composition on ecological processes. Quantifying and understanding the drivers of herbivory across a range of spatial scales is essential to the future management of coral reefs.

scholarly journals Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef

2020 ◽  
Vol 287 (1936) ◽  
pp. 20201432
Author(s):  
Andreas Dietzel ◽  
Michael Bode ◽  
Sean R. Connolly ◽  
Terry P. Hughes
Keyword(s):  
Great Barrier Reef ◽  
Colony Size ◽  
Size Structure ◽  
Coral Cover ◽  
Spatial Scales ◽  
Reproductive Capacity ◽  
Barrier Reef ◽  
Size Frequency Distribution ◽  
Coral Colony ◽  
Recovery Potential

The age or size structure of a population has a marked influence on its demography and reproductive capacity. While declines in coral cover are well documented, concomitant shifts in the size-frequency distribution of coral colonies are rarely measured at large spatial scales. Here, we document major shifts in the colony size structure of coral populations along the 2300 km length of the Great Barrier Reef relative to historical baselines (1995/1996). Coral colony abundances on reef crests and slopes have declined sharply across all colony size classes and in all coral taxa compared to historical baselines. Declines were particularly pronounced in the northern and central regions of the Great Barrier Reef, following mass coral bleaching in 2016 and 2017. The relative abundances of large colonies remained relatively stable, but this apparent stability masks steep declines in absolute abundance. The potential for recovery of older fecund corals is uncertain given the increasing frequency and intensity of disturbance events. The systematic decline in smaller colonies across regions, habitats and taxa, suggests that a decline in recruitment has further eroded the recovery potential and resilience of coral populations.

scholarly journals Progressive seawater acidification on the Great Barrier Reef continental shelf

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Katharina E. Fabricius ◽  
Craig Neill ◽  
Erik Van Ooijen ◽  
Joy N. Smith ◽  
Bronte Tilbrook
Keyword(s):  
Coral Reefs ◽  
Continental Shelf ◽  
Great Barrier Reef ◽  
Ocean Acidification ◽  
Seawater Temperature ◽  
Barrier Reef ◽  
Saturation State ◽  
Seawater Acidification ◽  
Seawater Ph ◽  
Seawater Samples

Abstract Coral reefs are highly sensitive to ocean acidification due to rising atmospheric CO2 concentrations. We present 10 years of data (2009–2019) on the long-term trends and sources of variation in the carbon chemistry from two fixed stations in the Australian Great Barrier Reef. Data from the subtropical mid-shelf GBRWIS comprised 3-h instrument records, and those from the tropical coastal NRSYON were monthly seawater samples. Both stations recorded significant variation in seawater CO2 fugacity (fCO2), attributable to seasonal, daytime, temperature and salinity fluctuations. Superimposed over this variation, fCO2 progressively increased by > 2.0 ± 0.3 µatm year−1 at both stations. Seawater temperature and salinity also increased throughout the decade, whereas seawater pH and the saturation state of aragonite declined. The decadal upward fCO2 trend remained significant in temperature- and salinity-normalised data. Indeed, annual fCO2 minima are now higher than estimated fCO2 maxima in the early 1960s, with mean fCO2 now ~ 28% higher than 60 years ago. Our data indicate that carbonate dissolution from the seafloor is currently unable to buffer the Great Barrier Reef against ocean acidification. This is of great concern for the thousands of coral reefs and other diverse marine ecosystems located in this vast continental shelf system.

scholarly journals Socio-Ecological Controversies in the News as Trigger of a Model-Based Inquiry Instructional Sequence about the Effect of Global Warming on the Great Barrier Reef

2020 ◽  
Vol 12 (11) ◽  
pp. 4676
Author(s):  
M. Rut Jiménez-Liso ◽  
Manuela González-Herrera ◽  
Isabel Banos-González
Keyword(s):  
Global Warming ◽  
Secondary School ◽  
Coral Reefs ◽  
Great Barrier Reef ◽  
Ecological System ◽  
Alternative Conceptions ◽  
Instructional Sequence ◽  
Barrier Reef ◽  
School Students ◽  
Model Based

The use of socio-ecological controversies, such as global warming, in classrooms has been suggested to increase students’ awareness about complex issues, although detailed analysis of their implementation in classrooms are still scarce. This research shows a model-based inquiry approach (MBI) instructional sequence, using scientific news as a trigger, aimed at addressing a global problem on a real socio-ecological system: the effect of global warming on the Great Barrier Reef. Its implementation in a lower secondary school classroom allowed the assessment of the effectiveness of the instructional sequence designed, based on students’ perception of what secondary school students have learned and felt. Results show that the MBI instructional sequence seems to have favored the mobilization of students’ alternative conceptions about global warming, coral reefs, and symbiotic relationships. In addition, it contributed to increasing the students’ awareness of the problem of global warming and its effects on an essential socio-ecological system, such as coral reefs.

scholarly journals Optimising cool-water injections to reduce thermal stress on coral reefs of the Great Barrier Reef

PLoS ONE ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. e0239978
Author(s):  
Mark Edward Baird ◽  
Rebecca Green ◽  
Ryan Lowe ◽  
Mathieu Mongin ◽  
Elodie Bougeot
Keyword(s):  
Thermal Stress ◽  
Coral Reefs ◽  
Great Barrier Reef ◽  
Barrier Reef ◽  
Cool Water
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