Effects of training on observer performance in assessing benthic cover by means of the manta tow technique

1996 ◽  
Vol 47 (1) ◽  
pp. 19 ◽  
Author(s):  
IR Miller ◽  
G De'ath
Keyword(s):  
Field Experiment ◽  
Great Barrier Reef ◽  
Coral Cover ◽  
Observer Performance ◽  
Live Coral ◽  
Barrier Reef ◽  
Acanthaster Planci ◽  
Dead Coral ◽  
And Training

The manta tow technique is used to obtain broadscale information on the distribution of Acanthaster planci and corals on the Great Barrier Reef. A field experiment was used to investigate how experience and training affects visual estimates of benthic cover made by observers using the manta tow technique. For live coral and sandlrubble cover, experienced observers obtained significantly higher levels of precision in their estimates than inexperienced observers; training increased the precision of these estimates for both experienced and inexperienced observers. Dead coral cover was sparse (<5%), making it difficult to assess the performance of the manta tow technique for this form of benthic cover. For both live and dead coral, and for sandlrubble, the levels of agreement between observers exceeded that expected by chance by between 5 to 1 and 10 to 1.

Suitability of the manta tow technique for estimating relative and absolute abundances of crown-of-thorns starfish (Acanthaster planci L. ) and corals

1992 ◽  
Vol 43 (2) ◽  
pp. 357 ◽  
Author(s):  
PJ Moran ◽  
G De'ath
Keyword(s):  
Coral Cover ◽  
Cost Effective ◽  
Live Coral ◽  
Statistical Relationship ◽  
Acanthaster Planci ◽  
Dead Coral ◽  
Effective Option ◽  
Fixed Area ◽  
Large Coral ◽  
Broad Scale

The manta tow technique has been used mainly for broad-scale surveys of large coral reef systems. The present study comprised two separate investigations of the technique. One involved investigating its repeatability by comparing the performance of three observers towed together along a reef. The other compared the counts of crown-of-thorns starfish from manta tow and SCUBA swim surveys undertaken within 30 large areas on eight reefs. Overall, the technique was found to be highly repeatable, particularly for crown-of-thorns starfish and live coral cover. It was less repeatable for assessing the cover of dead coral, although this was still within acceptable limits. A strong statistical relationship (r2adj = 0.91) was found between the starfish counts obtained from manta tows and those obtained from SCUBA swim surveys. Consequently, the former can be calibrated to predict the latter. The crown-of-thorns starfish is known to be cryptic and to have an aggregated distribution. However, the present study showed that the manta tow technique is a reasonably accurate and cost-effective option for determining relative changes in the distribution and abundance of noncryptic starfish where the unit of interest is a whole reef (or a large part thereof). As a comparison, approximately 14 manta tows (each lasting 2 min) will give the same level of accuracy as 10 SCUBA swim surveys of the same fixed area. The sensitivity of the manta tow technique in detecting relative changes in abundance will depend on the number of tows that are conducted. As a guide, however, a typical manta tow survey (involving approximately 50-60 tows) is capable of detecting a 20% change in the abundance of an out-breaking population of crown-of-thorns starfish. Given these findings, the manta tow technique also may be useful for assessing relative changes in the distribution and abundance of other organisms.

scholarly journals Field measurements of a massive Porites coral at Goolboodi (Orpheus Island), Great Barrier Reef

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam Smith ◽  
Nathan Cook ◽  
Kailash Cook ◽  
Rachelle Brown ◽  
Richard Woodgett ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Growth Models ◽  
Coral Cover ◽  
Field Measurements ◽  
Science Research ◽  
Live Coral ◽  
Barrier Reef ◽  
Language And Culture ◽  
Large Coral ◽  
Massive Porites

AbstractAn exceptionally large coral Porites sp. has been identified and measured at Goolboodi (Orpheus Island), Great Barrier Reef (GBR). This coral was measured in March 2021 during citizen science research of coral reefs in the Palm Islands group. We conducted a literature review and consulted scientists to compare the size, age and health of the Porites with others in the GBR and internationally. This is the largest diameter Porites coral measured by scientists and the sixth highest coral measured in the GBR. The health of the Porites was assessed as very good with over 70% live coral cover and minor percentages of sponge, live coral rock and macroalgae. An estimated age of 421–438 years was calculated based on linear growth models. Manbarra Traditional Owners were consulted and suggested that the Porites be named Muga dhambi (big coral) to communicate traditional knowledge, language and culture to indigenous, tourists, scientists and students.

Population Explosions ofAcanthaster planciand Associated Destruction of the Hard-coral Cover of Reefs of the Great Barrier Reef, Australia

1975 ◽  
Vol 2 (4) ◽  
pp. 247-256 ◽  
Author(s):  
Robert Endean ◽  
William Stablum
Keyword(s):  
Great Barrier Reef ◽  
Coral Cover ◽  
Pacific Region ◽  
Barrier Reef ◽  
Hard Coral ◽  
Acanthaster Planci ◽  
West Pacific ◽  
Significant Percentage ◽  
Hard Coral Cover ◽  
Principal Region

Population explosions of the Crown-of-thorns Starfish,Acanthaster planci, first reported on reefs of the Great Barrier Reef in the Cairns region near lat. 17° S during the early 1960s, have since spread to numerous other reefs. The spread has been predominantly southwards, the principal region of infestation currently lying between lat. 19° S and lat. 19°20' S. South of this region, scattered infestations of reefs have recently been reported. Available data indicate that most reefs in the middle third of the Great Barrier Reef were infested during the last decade, and it is postulated that most reefs in the southernmost third will be infested during the next decade.The bulk of the hard-coral cover of most of the inner platform reefs infested, and a lower but significant percentage of the hard-coral cover of the outer platform reefs affected by the infestations, have been devastated. Recovery of devastated reefs is in progress but is slow.TheA. planciinfestations appear to the authors to be man-induced, and it is suggested that international action be taken to assess the magnitude of theA. planciproblem and to coordinate possible control activities in the Indo-West Pacific region.

scholarly journals Acute drivers influence recent inshore Great Barrier Reef dynamics

2018 ◽  
Vol 285 (1890) ◽  
pp. 20182063 ◽  
Author(s):  
Vivian Y. Y. Lam ◽  
Milani Chaloupka ◽  
Angus Thompson ◽  
Christopher Doropoulos ◽  
Peter J. Mumby
Keyword(s):  
Coral Reef ◽  
Great Barrier Reef ◽  
Coral Cover ◽  
Temporal Trends ◽  
Live Coral ◽  
Barrier Reef ◽  
Natural Ecosystems ◽  
Juvenile Coral ◽  
Acute Disturbance ◽  
Key Drivers

Understanding the dynamics of habitat-forming organisms is fundamental to managing natural ecosystems. Most studies of coral reef dynamics have focused on clear-water systems though corals inhabit many turbid regions. Here, we illustrate the key drivers of an inshore coral reef ecosystem using 10 years of biological, environmental, and disturbance data. Tropical cyclones, crown-of-thorns starfish, and coral bleaching are recognized as the major drivers of coral loss at mid- and offshore reefs along the Great Barrier Reef (GBR). In comparison, little is known about what drives temporal trends at inshore reefs closer to major anthropogenic stress. We assessed coral cover dynamics using state-space models within six major inshore GBR catchments. An overall decline was detected in nearly half (46%) of the 15 reefs at two depths (30 sites), while the rest exhibited fluctuating (23%), static (17%), or positive (13%) trends. Inshore reefs responded similarly to their offshore counterparts, where contemporary trends were predominantly influenced by acute disturbance events. Storms emerged as the major driver affecting the inshore GBR, with the effects of other drivers such as disease, juvenile coral density, and macroalgal and turf per cent cover varying from one catchment to another. Flooding was also associated with negative trends in live coral cover in two southern catchments, but the mechanism remains unclear as it is not reflected in available metrics of water quality and may act through indirect pathways.

scholarly journals Potential for rapid genetic adaptation to warming in a Great Barrier Reef coral

2017 ◽  
Author(s):  
Mikhail V. Matz ◽  
Eric A. Treml ◽  
Galina V. Aglyamova ◽  
Madeleine J. H. van Oppen ◽  
Line K. Bay
Keyword(s):  
Genetic Variation ◽  
Great Barrier Reef ◽  
Coral Cover ◽  
Reef Coral ◽  
Biophysical Model ◽  
Detectable Effect ◽  
Genetic Adaptation ◽  
Barrier Reef ◽  
Biophysical Modeling ◽  
Adaptive Genetic Variation

AbstractCan genetic adaptation in reef-building corals keep pace with the current rate of sea surface warming? Here we combine population genomic, biophysical modeling, and evolutionary simulations to predict future adaptation of the common coralAcropora milleporaon the Great Barrier Reef. Loss of coral cover in recent decades did not yet have detectable effect on genetic diversity in our species. Genomic analysis of migration patterns closely matched the biophysical model of larval dispersal in favoring the spread of existing heat-tolerant alleles from lower to higher latitudes. Given these conditions we find that standing genetic variation could be sufficient to fuel rapid adaptation ofA. milleporato warming for the next 100-200 years, although random thermal anomalies would drive increasingly severe mortality episodes. However, this adaptation will inevitably cease unless the warming is slowed down, since no realistic mutation rate could replenish adaptive genetic variation fast enough.

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 Cross-Shelf Variation Among Juvenile and Adult Coral Assemblages on Australia’s Great Barrier Reef

Diversity ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 85 ◽  
Author(s):  
Michelle J. Jonker ◽  
Angus A. Thompson ◽  
Patricia Menéndez ◽  
Kate Osborne
Keyword(s):  
Great Barrier Reef ◽  
Coral Cover ◽  
Synergistic Effects ◽  
Outer Shelf ◽  
Lower Latitude ◽  
Barrier Reef ◽  
Hard Coral ◽  
Coral Abundance ◽  
The Status ◽  
Community Types

Coral reefs are under increasing pressure from a variety of stressors, highlighting the need for information about the status of coral reef communities including the distribution, abundance and composition of juvenile and adult coral assemblages. This information is currently limited for the Great Barrier Reef (GBR) and is necessary for understanding the impacts of disturbances and the system’s potential for recovery. This study reports juvenile and adult hard coral abundance and composition from 122 reefs on the GBR during a period of limited acute disturbance. The data represent baseline observations for juvenile hard coral assemblages spanning the longitudinal cross-shelf gradient of the GBR and 12 degrees of latitude and augment reported distribution of adult coral assemblages over the same scale with inclusion of additional reefs. Juvenile and adult coral assemblages reflected broad differences imposed by the gradient of environmental conditions across the GBR. The mean density of juvenile hard corals was lower in the inshore reefs (5.51 m2) than at either the mid-shelf (11.8 m2) or outer shelf reefs (11.2 m2). The composition of juvenile and adult coral assemblages covaried overall, although there were different relationships between these two life stages across the continental shelf and among community types. Dissimilarity between juvenile and adult coral assemblages was greater on inshore and outer shelf reefs than on reefs in the mid-shelf, although, there were differences in community types both within these shelf positions and those that spanned mid- and outer shelf reefs. Dissimilarity was greatest for Inshore branching Acropora and high for Southern Acropora communities, although very high coral cover and very low juvenile densities at these reefs precluded interpretation beyond the clear competitive dominance of Acropora on those reefs. Dissimilarity was also high between juvenile and adult coral assemblages of Turbid inshore communities suggesting water quality pressures, along with synergistic effects of other stressors, pose ongoing selective pressures beyond the juvenile stage. Conversely, relatively low dissimilarity between juvenile and adult coral assemblages on mid-shelf and lower latitude outer shelf reefs suggests pressures beyond those influencing settlement and early post-settlement survival were having less influence on the composition of adult coral assemblages.

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