Temporal patterns of coral cover in the offshore Pilbara, Western Australia

Ridgway, Tyrone; Inostroza, Karina; Synnot, L.; Trapon, Mélanie L.; Twomey, Luke; Westera, Mark

doi:10.1007/s00227-016-2956-1

Cited by 20 publications

(16 citation statements)

References 23 publications

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“…Historically, reefs on the northern edge of the Archipelago, furthest from the mainland, were dominated by fast-growing Acropora species susceptible to bleaching, whilst reefs within Mermaid Sound closer to the mainland consisted of more diverse assemblages including both massive and branching taxa [41,43,98]. Bleaching-induced mortality caused by anomalously high water temperatures may have contributed to spatial heterogeneity in WA coral communities [47,82,99]. Cross-shelf gradients in temperature stress in Belize, for example, have been linked to low coral cover and assemblages dominated by stress-tolerant species on inshore reefs [32].…”

Section: Discussionmentioning

confidence: 99%

“…A strong temperature-stress gradient was present in the Dampier region, although current patterns in assemblage composition do not reflect those expected following heat exposure, with both vulnerable and hardy taxa peaking in abundance on reefs closest to the mainland and the highest coral cover and diversity observed on reefs at an intermediate distance from the coast. Although the region has experienced levels of heat stress typically associated with coral bleaching and mortality [47,82], these effects may have been mediated by local factors in the Dampier Archipelago, resulting in unexpected distribution patterns. Environmental factors not investigated in this study, including substrate type, nutrient influx and hydrodynamic patterns, may have influenced the distribution of species and resilience of coral reefs in the Dampier Archipelago [100,101].…”

Section: Discussionmentioning

confidence: 99%

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Cross-shelf Heterogeneity of Coral Assemblages in Northwest Australia

Moustaka¹,

Mohring²,

Holmes

et al. 2019

Diversity

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Understanding the spatial and temporal distribution of coral assemblages and the processes structuring those patterns is fundamental to managing reef assemblages. Cross-shelf marine systems exhibit pronounced and persistent gradients in environmental conditions; however, these gradients are not always reliable predictors of coral distribution or the degree of stress that corals are experiencing. This study used information from government, industry and scientific datasets spanning 1980–2017, to explore temporal trends in coral cover in the geographically complex system of the Dampier Archipelago, northwest Australia. Coral composition at 15 sites surveyed in 2017 was also modelled against environmental and spatial variables (including turbidity, degree heat weeks, wave exposure, and distance to land/mainland/isobath) to assess their relative importance in structuring coral assemblages. High spatial and temporal heterogeneity was observed in coral cover and recovery trajectories, with reefs located an intermediate distance from the shore maintaining high cover over the past 20 years. The abundance of some prominent genera in 2017 (Acropora, Porites, and Turbinaria spp.) decreased with the distance from the mainland, suggesting that inshore processes play an important role in dictating the distribution of these genera. The atypical distributions of these key reef-building corals and spatial heterogeneity of historical recovery trajectories highlight the risks in making assumptions regarding cross-shelf patterns in geographically complex systems.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Cross-shelf Heterogeneity of Coral Assemblages in Northwest Australia

Moustaka¹,

Mohring²,

Holmes

et al. 2019

Diversity

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“…Given recent coral bleaching in the Pilbara (Ridgway et al. , Lafratta et al. ), the importance of these zones for the recovery and resilience of the overall region assumes broader importance and potentially greater urgency.…”

Section: Discussionmentioning

confidence: 99%

“…To quantify the current coral cover and the maximum sustainable coral cover for each subregion, the mean percent cover of live and recently dead (Ridgway et al. , Lafratta et al. ) coral was obtained from photo‐transects.…”

Section: Methodsmentioning

confidence: 99%

Setting priorities for conservation at the interface between ocean circulation, connectivity, and population dynamics

Boschetti

Babcock

Doropoulos

et al. 2019

Ecological Applications

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Population persistence in the marine environment is driven by patterns of ocean circulation, larval dispersal, ecological interactions, and demographic rates. For habitat‐forming organisms in particular, understanding the relationship between larval connectivity and meta‐population dynamics aids in planning for marine spatial management. Here, we estimate networks of connectivity between fringing coral reefs in the northwest shelf of Australia by combining a particle tracking model based on shelf circulation with models of subpopulation dynamics of individual reefs. Coral cover data were used as a proxy for overall habitat quality, which can change as a result of natural processes, human‐driven impacts, and management initiatives. We obtain three major results of conservation significance. First, the dynamics of the ecological network result from the interplay between network connectivity and ecological processes on individual reefs. The maximum coral cover a zone can sustain imposes a significant nonlinearity on the role an individual reef plays within the dynamics of the network, and thus on the impact of conservation interventions on specific reefs. Second, the role of an individual reef within these network dynamics changes considerably depending on the overall state of the system: a reef's role in sustaining the system's state can be different from the same reef's role in helping the system recover following major disturbance. Third, patterns of network connectivity change significantly as a function of yearly shelf circulation trends, and nonlinearity in network dynamics make mean connectivity a poor representation of yearly variations. From a management perspective, the priority list of reefs that are targets for management interventions depends crucially on what type of stressors (system‐wide vs. localized) need addressing. This choice also depends not only on the ultimate purpose of management, but also on future oceanographic, climate change, and development scenarios that will determine the network connectivity and habitat quality.

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“…For example, sudden temperature changes, both hot (Hoegh-Guldberg et al 2007) and cold (Hoegh-Guldberg and Fine 2004), can result in coral bleaching. However, whether a coral colony bleaches is determined by both the intensity and the duration of the temperature anomaly (Ridgway et al 2016): small to moderate changes in temperature cause bleaching only when the temperature anomaly persists for an extended period of time (Glynn and D'Croz 1990;Winter et al 1998;Saxby et al 2003). Consequently, coral reef conservation efforts incorporated duration into monitoring of coral bleaching worldwide by calculating the number of Degree-Heating Weeks (DHW) (NOAA Coral Reef Watch 2013) to identify areas at risk.…”

Section: Discussionmentioning

confidence: 99%

Predation on oysters is inhibited by intense or chronically mild, low salinity events

Pusack

Kimbro

White

et al. 2018

Limnology & Oceanography

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Environmental stress gradients can affect species distributions and interspecific interactions. Because environmental stress depends on both intensity and duration, understanding the consequences of stress requires experiments that simultaneously manipulate both dimensions. In Apalachicola Bay, Florida (U.S.A.) the southern oyster drill (Stramonita haemastoma) is a major predator of the eastern oyster (Crassostrea virginica). Drill predation appears to be salinity‐dependent: in a recent field study, predation rates were positively correlated with salinity. Salinity in the bay is typically high (> 20) during the dry summer months, conditions that favor both oysters and the drill. However, periodic freshets can dramatically reduce salinity, which inhibits (or kills) drills, but not oysters. In this study, we used field measurements of salinity and drill densities to inform mesocosm experiments. We investigated the specific combinations of intensity and duration of low‐salinity stress that inhibit drill predation. In these experiments, more intense salinity reductions reduced feeding both during and after the low‐salinity stress event. During the event, longer durations (15 d) were necessary for mild salinity reductions (−5) to reduce the feeding rate by the same amount as a short (5 d) exposure of more intense (−10 or −15) salinity reduction. Both conditions may create a predation refuge for oysters, consistent with field observations. Given that the recent collapse of the Apalachicola Bay oyster population was preceded by several years without low‐salinity events to inhibit predation, our results provide a mechanism by which a predator may have contributed to the loss of a historically productive and sustainable fishery.

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Temporal patterns of coral cover in the offshore Pilbara, Western Australia

Cited by 20 publications

References 23 publications

Cross-shelf Heterogeneity of Coral Assemblages in Northwest Australia

Cross-shelf Heterogeneity of Coral Assemblages in Northwest Australia

Setting priorities for conservation at the interface between ocean circulation, connectivity, and population dynamics

Predation on oysters is inhibited by intense or chronically mild, low salinity events

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