Ningaloo Research Articles

Diurnal cycles of coral calcifying fluid aragonite saturation state

The sensitivity of corals to ocean acidification depends on the extent to which they can buffer their calcifying fluid aragonite saturation state (Ωcf) from declines in seawater pH. While the seasonal response of the coral calcifying fluid Ωcf to seawater pH has been studied previously, relatively little is known about Ωcf dynamics on shorter (daily) timescales, particularly whether it is sensitive to seawater pH. Here, we use alizarin dye to mark 4 days of skeletal growth in the corals Acropora nasuta and Pocillopora damicornis living in situ on Ningaloo Reef in Western Australia. Exploiting newly developed confocal Raman spectroscopy techniques, we imaged the alizarin stains and quantified Ωcf between them. We report the first observations of diurnal Ωcf cycles, which were found in both species. Our results are consistent with either external control of Ωcf by seawater pH or light, or alternatively that Ωcf follows an endogenous circadian rhythm.

First Insights Into the Fine-Scale Movements of the Sandbar Shark, Carcharhinus plumbeus

The expanding use of biologging tags in studies of shark movement provides an opportunity to compare fine-scale movement behaviours among species. In May 2017, we deployed high-resolution biologging tags on four mature female sandbar sharks Carcharhinus plumbeus at Ningaloo Reef for durations ranging between 13 and 25.5 hours. Pressure and tri-axial motion sensors within these tags enabled the calculation of dive geometry, swimming kinematics and path tortuosity at fine spatial scales (m-km) and concurrent validation of these behaviours from video recordings. Sandbar sharks oscillated through the water column at shallow dive angles, with gliding behaviour observed in the descent phase for all sharks. Continual V-shaped oscillatory movements were occasionally interspersed by U-shaped dives that predominately occurred around dusk. The bottom phase of these U-shaped dives likely occurred on the seabed, with dead-reckoning revealing a highly tortuous, circling track. By combining these fine-scale behavioural observations with existing ecological knowledge of sandbar habitat and diet, we argue that this circling behaviour is likely to be a strategy for hunting benthic prey. Comparing dive geometry and energetics with those of other sharks reveals common patterns in energetically efficient oscillatory swimming.

Outbreak densities of the coral predator Drupella in relation to in situ Acropora growth rates on Ningaloo Reef, Western Australia

Outbreaks of coral predators are defined as increases (often rapid) in their abundance above threshold densities that can be sustained by local coral assemblages, which in turn depends on the abundance and turnover of coral prey. To investigate the outbreak densities of the corallivorous gastropod Drupella cornus, we conducted both in situ feeding and coral growth experiments at Mandu reef within the Ningaloo Marine Park, Western Australia. Over two 10-day periods, we tagged and photographed feeding scars on colonies of the tabulate coral Acropora spicifera that harboured Drupella feeding aggregations. We calculated a mean in situ Drupella consumption rate of 1.16 ± 1.1 cm2 coral area individual−1 d−1. We also determined coral growth rates by tagging and photographing 24 colonies of Acropora spicifera at time zero and then again 1 year later. We calculated a mean linear extension rate of 7.9 ± 3.7 cm yr−1 for actively growing Acropora spicifera, which we then used to estimate A. spicifera growth rates over a range of coral cover values. This combination allowed us to determine the maximum number of Drupella that could be sustained across a range of coral cover. Our data suggest that the outbreak density of Drupella at the average level of coral cover for back reef sites at Mandu reef (17.6 ± 13.7%) is approximately 0.95 individuals m−2 reef area. At the maximum coral cover observed at Mandu reef (60%), the outbreak density of Drupella is estimated to be approximately 2.83 individuals m−2 reef area. Establishing Drupella outbreak densities assists managers in predicting possible outbreak abundances and in monitoring coral reef health.

The Influence of Temperature on Embryonic Respiration, Growth, and Sex Determination in a Western Australian Population of Green Turtles (Chelonia mydas).

The thermal environment of sea turtle embryos has marked effects on many aspects of their development and energetics and has consequences for posthatching stages. Here we incubated Chelonia mydas embryos from Ningaloo Reef in Western Australia at a range of temperatures (27°, 29°, 30°, 31°, 32°, and 30° ± 5°C) to determine development rates and the pivotal temperature for sex determination. We also measured embryonic growth, oxygen consumption, and carbon dioxide production throughout development at 27° and 31°C. Metabolic rates were higher at 31°C than at 27°C, but total energy expenditure was greater at 27°C, with 2,281 mL of oxygen consumed compared with 1,992 mL at 31°C. Respiration at both temperatures showed a pattern typical of sea turtle embryos, with peak rates occurring at approximately 85% of development and then declining toward hatching. Hatchlings produced at higher incubation temperatures developed faster, were smaller, and had larger residual yolk masses than hatchlings produced at lower temperatures. The pivotal temperature that produced an equal sex ratio was 29.2°C, with mixed sexes produced between 27.9° and 30.4°C. Our results showed that the Ningaloo population of C. mydas has somewhat different thermal sensitivities than other C. mydas populations and justified why is it necessary to collect population-specific data to accurately project the impacts of global warming on focal populations.

Source and supply of sediment to a shoreline salient in a fringing reef environment

AbstractReef‐associated landforms are coupled to the health of the reef ecosystem which produces the sediment that forms and maintains these landforms. However, this connection can make reef‐fronted coastlines sensitive to the impacts of climate change, given that any decline in ecosystem health (e.g. decreasing sediment supply) or changes to physical processes (e.g. sea level rise, increasing wave energy) could drive the sediment budgets of these systems into a net erosive state. Therefore, knowledge of both the sediment sources and transport mechanisms is required to predict the sensitivity of reef‐associated landforms to future climate change. Here, we examine the benthic habitat composition, sediment characteristics (composition, texture, and age), and transport mechanisms and pathways to understand the interconnections between coastal morphology and the reef system at Tantabiddi, Ningaloo Reef, Western Australia. Benthic surveys and sediment composition analysis revealed that although live coral accounts for less than 5% of the benthic cover, coral is the dominant sediment constituent (34% on average). Sediment ages (238U/230Th) were mostly found to be thousands of years old, suggesting that the primary sediment source is relic reef material (e.g. Holocene reef framework). Sediment transport across the lagoon was quantified through measurements of ripple migration rates, which were found to be shoreward migrating and responsible for feeding the large shoreline salient in the lee of the reef. The derived sediment fluxes were comparable with previously measured rates of sediment production by bioerosion. These results suggest that sediment budgets of systems dependent on old (>103 years) source materials may be more resilient to climate change as present‐day reef health and community composition (i.e. sources of ‘new’ carbonate production) have limited influence on sediment supply. Therefore, the vulnerability of reef‐associated landforms in these systems will be dictated by future changes to mechanisms of sediment generation (e.g. bioerosion) and/or physical processes. © 2018 John Wiley & Sons, Ltd.

Multiple climate impacts on seagrass dynamics: Amphibolis antarctica patches at Ningaloo Reef, Western Australia

The impacts of tropical cyclones combined with a marine heatwave are reported for a seagrass community at Ningaloo Reef, Western Australia. A community of 9.5ha of Amphibolis antarctica was lost following a combination of cyclone-induced burial and a marine heatwave. No new seedlings have been observed since the loss; recruitment of seedlings may be impeded by local ocean circulation.

Depth-related patterns in coral recruitment across a shallow to mesophotic gradient

There is currently very limited information around the spatial patterns of coral recruitment at mesophotic depths globally. This study investigated depth-related differences in coral recruitment patterns from shallow (~ 3 m) to mesophotic depths (~ 40 m) in the Indian Ocean. A new method is described for assessing coral recruitment, which allows for the improved study of recruitment patterns on deep reefs globally, as the method does not require SCUBA diving. This method allows for comparisons with other studies as there appears to be no influence on the density, composition, or settlement orientation of recruits relative to the most commonly used methods. Using this method, we investigated coral recruitment at Ningaloo Reef, Western Australia, finding the abundance of coral recruits varied significantly with depth and was highest at 25 m. The size of coral recruits changed significantly with depth, with larger recruits observed in shallower areas (3 and 8 m) than in deep areas. Distinct changes in settlement densities on tile surfaces occurred with increasing depth, with a shift to upper tile surfaces between 8 and 25 m, where the proportion of recruits increased from 10.72 to 87.69%, respectively. Overall counts of recruits were low, with minimal recruitment at the deepest sites and moderate but significant correlations between recruit numbers and hard coral cover were observed. This suggests that variations in larval supply, potentially coupled with larval behaviour and local-scale influences, limit exchange of larvae between depths and locations. This is consistent with genetic studies that show limited exchange between shallow and mesophotic reefs and points to a limited potential for mesophotic reefs to act as a source of larvae for impacted shallow reefs.

Monitoring visitor injury in protected areas - analysis of incident reporting in two Western Australian parks

A large number of visitor injuries and fatalities are recorded in protected areas around the world each year. With the goal of reducing future accidents, it is critical for managing agencies to learn from past events by identifying why and under which circumstances visitor incidents occurred. This paper presents a retrospective analysis of visitor incident data recorded in Western Australian lands and waters managed by public agencies between July 2011 and June 2017. The aim of the study was to explore trends and patterns of incident occurrence, and by so doing, to examine whether current incident reporting practices in Western Australia are adequate to comprehensively understand incident occurrence in different park contexts. Using Karijini National Park and Ningaloo Coast World Heritage Area as case examples, different ways are presented how incident data collected can be utilised in relation to different park contexts. However, our study shows that incident monitoring in Western Australia is characterised by fragmentary recording of information, leading to difficulties in clearly understanding why and under which circumstances incidents occur. For example, whilst visitor risk levels across various times during the year were quantified in Karijini, illustrating that certain months are related to a greater risk of injury per park visit, insufficient data provision on weather conditions and visitor behaviour meant that no clear conclusions could be drawn on the causes of this trend. Similarly, whilst the data pointed towards a specific visitor group at high risk of harm in Ningaloo (i.e. unguided international visitors), a comparison to overall visitor data was not possible, which prevents making inferences about the extent of the potential issue identified. Management implicationsThe study illustrates that more comprehensive incident monitoring practices can help to better understand incident occurrence in protected areas, can improve awareness of the hazard situation relative to situational visitor characteristics, and can further refine visitor risk assessment and management processes. The paper also illustrates the importance of including potential contributing factors such as prevailing environmental conditions as well as visitor behaviour in incident reports for a more meaningful incident data analysis. Whilst this study provides some recommendations on the type of information that should be included in visitor incident reports, more work is needed to further establish a standardised incident reporting and monitoring system applicable to the management of visitor risk of injury in protected areas on a larger scale.

Building trust among marine protected area managers and community members through scientific research: Insights from the Ningaloo Marine Park, Australia

The success of participatory marine governance arrangements is influenced by the levels of trust that exist between decision-makers and diverse stakeholder groups within the community. While the benefits of high levels of trust among these groups is well established, specific approaches to building trust remain largely unknown. The aim of this study is to understand the extent to which scientific research programs can enhance trust among marine protected area (MPA) managers and community members via an evaluation of the Ningaloo Research Program - a large-scale program of marine research in the Ningaloo Marine Park. Results from a survey of 125 local residents show that community members along the Ningaloo coast believe that scientific research is important for the management of the marine park, and strongly support government investment in scientific research in the region. Results also suggest that science undertaken through the Ningaloo Research Program has increased the extent to which community members trust local managers, which study participants believe has led to improved social and environmental outcomes in the region. Finally, additional opportunities are identified to maintain and further enhance trust between community members and MPA managers, via targeted communication and engagement programs that account for different personality ‘types’. In particular, the establishment of citizen science programs might further build trust. These results suggest that scientific research could be used as a means to increase trust among decision-makers and community members when coupled with an effective communication and outreach program, thus enhancing the success of participatory marine governance arrangements.

Challenges of transferring models of fish abundance between coral reefs.

Reliable abundance estimates for species are fundamental in ecology, fisheries, and conservation. Consequently, predictive models able to provide reliable estimates for un- or poorly-surveyed locations would prove a valuable tool for management. Based on commonly used environmental and physical predictors, we developed predictive models of total fish abundance and of abundance by fish family for ten representative taxonomic families for the Great Barrier Reef (GBR) using multiple temporal scenarios. We then tested if models developed for the GBR (reference system) could predict fish abundances at Ningaloo Reef (NR; target system), i.e., if these GBR models could be successfully transferred to NR. Models of abundance by fish family resulted in improved performance (e.g., 44.1% <R2 < 50.6% for Acanthuridae) compared to total fish abundance (9% <R2 < 18.6%). However, in contrast with previous transferability obtained for similar models for fish species richness from the GBR to NR, transferability for these fish abundance models was poor. When compared with observations of fish abundance collected in NR, our transferability results had low validation scores (R2 < 6%, p > 0.05). High spatio-temporal variability of patterns in fish abundance at the family and population levels in both reef systems likely affected the transferability of these models. Inclusion of additional predictors with potential direct effects on abundance, such as local fishing effort or topographic complexity, may improve transferability of fish abundance models. However, observations of these local-scale predictors are often not available, and might thereby hinder studies on model transferability and its usefulness for conservation planning and management.

Revision of the Siriella brevicaudata species group (Crustacea: Mysida: Mysidae) from the West Indo-Pacific

The Siriella brevicaudata species group from the West Indo-Pacific, defined and designated by Murano &amp; Fukuoka (2008), previously contained five nominal species. In this study we describe five new species in the brevicaudata group: S. bassi sp. nov. from the Bass Strait, southern Australia, S. occulta sp. nov. from the Arabian Gulf, S. muranoi sp. nov. from the coast of Northern Territory, Australia, S. tabaniocula sp. nov. from Ningaloo Reef of Western Australia and Lodestone Reef off Queensland, and S. talbotae sp. nov. from Lizard Island, Queensland, Australia. Furthermore, Siriella hanseni W.M. Tattersall, 1922 from India and S. vincenti W.M. Tattersall, 1927 from South Australia are redescribed based on re-examination of their type material. A re-examination of specimens subsequently attributed to these two species from other geographical regions showed that these were misidentifications, partly representing three of the new species described herein. Siriella gibbosa (Ledoyer, 1970), which was previously synonymized with S. brevicaudata Paulson, 1875 by Bačescu, is revalidated and included within the brevicaudata group. Siriella lacertilis Talbot, 2009, from Lizard Island, is placed within the brevicaudata group. Diagnostic features for all the members of the group and the group itself are updated. As a result of the present study, the brevicaudata group now comprises 12 valid species.

Response of a fringing reef coastline to the direct impact of a tropical cyclone

AbstractTropical cyclones generate extreme hazards along coastlines, often leading to losses of life and property. Although coral reefs exist in cyclone‐prone regions globally, few studies have measured the hydrodynamic conditions and morphological responses of reef‐fringed coastlines to tropical cyclones. Here, we examine the impact of Tropical Cyclone Olwyn on a section of Australia's largest fringing reef (Ningaloo Reef) using in situ wave and water level observations, topographic surveys, and numerical modeling. Despite forereef significant wave heights reaching 6 m and local winds of 140 km h−1, average beach volume change was only −3 m3 m−1. The results indicate that this erosion was due to locally generated wind waves within the lagoon rather than the offshore waves that were dissipated on the reef crest. A comparison of these volume changes to observations of tropical cyclone impacts along exposed sandy beaches quantitatively demonstrates the substantial coastal protection reefs can provide against extreme storms.

Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia

In 2015/16, a marine heatwave associated with a record El Niño led to the third global mass bleaching event documented to date. This event impacted coral reefs around the world, including in Western Australia (WA), although WA reefs had largely escaped bleaching during previous strong El Niño years. Coral health surveys were conducted during the austral summer of 2016 in four bioregions along the WA coast (~17 degrees of latitude), ranging from tropical to temperate locations. Here we report the first El Niño-related regional-scale mass bleaching event in WA. The heatwave primarily affected the macrotidal Kimberley region in northwest WA (~16°S), where 4.5–9.3 degree heating weeks (DHW) resulted in 56.6–80.6% bleaching, demonstrating that even heat-tolerant corals from naturally extreme, thermally variable reef environments are threatened by heatwaves. Some heat stress (2.4 DHW) and bleaching (<30%) also occurred at Rottnest Island (32°01’S), whereas coral communities at Ningaloo Reef (23°9’S) and Bremer Bay (34°25’S) were not impacted. The only other major mass bleaching in WA occurred during a strong La Niña event in 2010/11 and primarily affected reefs along the central-to-southern coast. This suggests that WA reefs are now at risk of severe bleaching during both El Niño and La Niña years.

Visual versus video methods for estimating reef fish biomass

Estimates of fish biomass collated at the community level are reliable indicators of fish and ecosystem health. Data to calculate fish biomass is routinely collected using either underwater visual census (UVC) or stereo diver operated video (DOV), although the compatibility of UVC and DOV based estimates are yet to be assessed. Accordingly, we calculated and compared community level measures of coral reef fish biomass at Ningaloo reef (Western Australia) using both UVC and DOV. The UVC based biomass estimates were 788kg/Ha, which was ∼50% greater than those from DOV (500kg/Ha). Differences between the methods were primarily due to DOV measuring the length of only ∼40% of fish detected by video, preventing fish specific weight calculations for all fish encountered. When the size of unmeasured fish was assumed to be the median value of fish measured by DOV, revised DOV+ estimates of community biomass (778kg/Ha) were similar to those from UVC. However, even when unmeasured fish were included in DOV calculations, biomass of some families (serranids) were still higher when using UVC. Conversely, DOV adjusted estimates of pomacentrid biomass were higher than those from UVC, due to DOV measuring fewer small bodied fish (<3cm), thus having a larger median size for the high number of unmeasured pomacentrids compared to UVC. Our results suggest that community measures of fish biomass from DOV and UVC are broadly comparable once weights of unmeasured fish are incorporated into DOV estimates. This may increase the spatial and temporal scales at which fish biomass can be monitored, although compatibility of data will depend on the composition and size distribution of the fish assemblages.

Do they stay or do they go? Acoustic monitoring of whale sharks at Ningaloo Marine Park, Western Australia.

Whale sharks Rhincodon typus were monitored via acoustic transmitters at the northern end of Western Australia's Ningaloo Marine Park to establish the extent to which the species inhabits the region beyond the whale-shark ecotourism industry season, which usually extends from March to August in each year. Despite the vast majority (c. 98%) of photographic submissions of R. typus from Ningaloo Reef being between March and August, acoustic detections from the tagged R. typus at Ningaloo were recorded in all months of the year, but do not preclude the occurrence of extended absences. It is concluded that as a species, R. typus occurs year round at Ningaloo, where it generally remains in close proximity to the reef edge, but that some individuals move outside of the detection range of the array for extended periods.

The trophic role of a large marine predator, the tiger shark Galeocerdo cuvier

Tiger sharks were sampled off the western (Ningaloo Reef, Shark Bay) and eastern (the Great Barrier Reef; GBR, Queensland and New South Wales; NSW) coastlines of Australia. Multiple tissues were collected from each shark to investigate the effects of location, size and sex of sharks on δ13C and δ15N stable isotopes among these locations. Isotopic composition of sharks sampled in reef and seagrass habitats (Shark Bay, GBR) reflected seagrass-based food-webs, whereas at Ningaloo Reef analysis revealed a dietary transition between pelagic and seagrass food-webs. In temperate habitats off southern Queensland and NSW coasts, shark diets relied on pelagic food-webs. Tiger sharks occupied roles at the top of food-webs at Shark Bay and on the GBR, but not at Ningaloo Reef or off the coast of NSW. Composition of δ13C in tissues was influenced by body size and sex of sharks, in addition to residency and diet stability. This variability in stable isotopic composition of tissues is likely to be a result of adaptive foraging strategies that allow these sharks to exploit multiple shelf and offshore habitats. The trophic role of tiger sharks is therefore both context- and habitat-dependent, consistent with a generalist, opportunistic diet at the population level.

The economic value of shark-diving tourism in Australia

Shark-diving is part of a rapidly growing industry focused on marine wildlife tourism. Our study aimed to provide an estimate of the economic value of shark-diving tourism across Australia by comprehensively surveying the whale shark (Rhincodon typus), white shark (Carcharodon carcharias), grey nurse shark (Carcharias taurus), and reef shark (mostly Carcharhinus amblyrhynchos and Triaenodon obesus) diving industries using a standardised approach. A socio-economic survey targeted tourist divers between March 2013 and June 2014 and collected information on expenditures related to diving, accommodation, transport, living costs, and other related activities during divers’ trips. A total of 711 tourist surveys were completed across the four industries, with the total annual direct expenditure by shark divers in Australia estimated conservatively at $25.5 M. Additional expenditure provided by the white-shark and whale-shark-diving industries totalled $8.1 and $12.5 M for the Port Lincoln and Ningaloo Reef regions respectively. International tourists diving with white sharks also expended another $0.9 M in airfares and other activities while in Australia. These additional revenues show that the economic value of this type of tourism do not flow solely to the industry, but are also spread across the region where it is hosted. This highlights the need to ensure a sustainable dive-tourism industry through adequate management of both shark-diver interactions and biological management of the species on which it is based. Our study also provides standardised estimates which allow for future comparison of the scale of other wildlife tourism industries (not limited to sharks) within or among countries.

Effects of sample treatment on the analysis of stable isotopes of carbon and nitrogen in zooplankton, micronekton and a filter-feeding shark

Stable isotope analysis is often used to investigate the trophic ecology of marine systems. However, a lack of standardization of the treatment of samples prior to analysis, hampers comparisons of results within and among studies. This study examined the effects of lipid extraction (LE), acidification for the removal of inorganic carbonate (RIC) and rinsing with deionized water (DIW) on δ13C and δ15N values and C:N ratios in sub-dermal tissue of whale sharks (Rhincodon typus), zooplankton (>200–1000 μm) and a wide range of micronekton (>1000 μm) taxa collected in 2013 and 2014 at Ningaloo Reef (Western Australia). For whale shark tissue, lipid extraction (LE and LE + DIW) increased values of δ13C, whereas LE, LE + DIW and DIW treatments increased values of δ5N and C:N ratios. These results confirm the need to remove lipids and 15N-depleted nitrogenous waste from elasmobranch tissues. The LE + DIW treatment was the most efficient at achieving this goal. For zooplankton and micronekton, LE and RIC treatments had consistent effects on δ13C values, however, effects on δ15N values were more unpredictable. Therefore, zooplankton and micronekton samples should be split into two portions, one subjected to LE or LE + RIC treatments to standardize δ13C values, and a second untreated portion used for analysis of δ15N values. For these taxa, the RIC + DIW treatment resulted in the greatest change in δ15N values, which may confound results. Mathematical normalization models used to predict outcomes of treatments on values of δ13C and δ15N were not found to be suitable for all the taxa in this study.

Differential response of corals to regional mass‐warming events as evident from skeletal Sr/Ca and Mg/Ca ratios

AbstractDuring the summer of 2010/2011, a regional marine heat wave resulted in coral bleaching of variable severity along much of the western coastline of Australia. At Ningaloo Reef, a 300 km long fringing reef system and World Heritage site, highly contrasting coral bleaching was observed between two morphologically distinct nearshore reef communities located on either side of the Ningaloo Peninsula: Tantabiddi (∼20% bleaching) and Bundegi (∼90% bleaching). For this study, we collected coral cores (Porites sp.) from Tantabiddi and Bundegi reef sites to assess the response of the Sr/Ca temperature proxy and Mg/Ca ratios to the variable levels of thermal stress imposed at these two sites during the 2010/2011 warming event. We found that there was an anomalous increase in Sr/Ca and decrease in Mg/Ca ratios in the Bundegi record that was coincident with the timing of severe coral bleaching at the site, while no significant changes were observed in the Tantabiddi record. We show that the change in the relationship of Sr/Ca and Mg/Ca ratios with temperature at Bundegi during the 2010/2011 event reflects changes in related coral “vital” processes during periods of environmental stress. These changes were found to be consistent with a reduction in active transport of Ca2+ to the site of calcification leading to a reduction in calcification rates and reduced Rayleigh fractionation of incorporated trace elements.

Limited effects of an extreme flood event on corals at Ningaloo Reef

In late April 2014 Ningaloo Reef was exposed to significant freshwater and sediment outflow following an extreme rainfall event (>200 mm in 48 h). It produced a plume of brown water of 9.63 km2 that was present two days after the rainfall event. The extent of the plume decreased by 55.9% within ten days. Benthic surveys were conducted at eight sites at Ningaloo (three of them within the plume and five outside the plume) using 25 m line transects to assess the percentage cover of all major benthic organisms, including hard corals, soft corals, algae and turf algae. Results from a survey done in May 2014 (approximately one month after the flooding) were compared with one done in March 2014 (before the extreme rainfall event). Corals from the genus Acropora were the dominant species in the coral assemblages surveyed. Our results indicate that percentage cover of Acropora did not vary significantly between sites inside and outside of the plume, but percentage cover of non-Acropora coral varied significantly among plume and non-plume sites. Both patterns were present before the flood. The results show that the flood-induced plumes caused limited damage to the coral along this part of Ningaloo Reef.