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Marine fauna, including coral reefs, exist under particular oceanographic and meteorological (metocean) processes that maintain water quality within the range limits to which they have adapted over millennia. Climate‐induced changes to these metocean processes could alter ambient marine water quality to ranges beyond those limits and at rates faster than species can adapt. Extreme (or marginal) coral reefs, such as those in arid tropical regions, already exist at the limits of their ranges for water quality parameters such as temperature and turbidity. Here, we apply projected anomalies from ensemble climate models to the metocean processes that drive turbidity in the Exmouth Gulf region of north Western Australia where habitats of significant environmental value exist. We also apply projected sea surface temperature anomalies to look at how a combined effect of turbidity and temperature might impact important habitats. We find that turbidity is predicted to increase in some parts of the Gulf and decrease in others due to differing metocean drivers of turbidity throughout the region. Temperature anomalies reveal year‐round increases in temperature consistent with current summer marine heat wave events (>2.5°C above mean temperatures). Climate models used in the predictions varied between themselves underscoring the importance of model choice and of using ensembles. [ABSTRACT FROM AUTHOR]

Globally, coral reefs are under threat, with many exhibiting degradation or a shift towards algal-dominated regimes following marine heat waves, and other disturbance events. Marginal coral reefs existing under naturally extreme conditions, such as turbid water reefs, may be more resilient than their clear water counterparts as well as offer some insight into how reefs could look in the future under climate change. Here, we surveyed 27 benthic habitats across an environmental stress gradient in the Exmouth Gulf region of north Western Australia immediately following a marine heatwave event. We used multidecadal remotely sensed turbidity (from an in-situ validated dataset) and temperature, to assess how these environmental drivers influence variability in benthic communities and coral morphology. Long-term turbidity and temperature variability were associated with macroalgal colonisation when exceeding a combined threshold. Coral cover was strongly negatively associated with temperature variability, and positively associated with depth, and wave power, while coral morphology diversity was positively associated with turbidity. While moderate turbidity (long-term average ~ 2 mg/L suspended matter) appeared to raise the threshold for coral bleaching and macroalgal dominance, regions with higher temperature variability (> 3.5 °C) appeared to have already reached this threshold. The region with the least turbidity and temperature variability had the highest amount of coral bleaching from a recent heatwave event and moderate levels of both these variables may confer resilience to coral reefs. [ABSTRACT FROM AUTHOR]

Nearly a billion people depend on tropical seascapes. The need to ensure sustainable use of these vital areas is recognised, as one of 17 policy commitments made by world leaders, in Sustainable Development Goal (SDG) 14 (‘Life below Water’) of the United Nations. SDG 14 seeks to secure marine sustainability by 2030. In a time of increasing social-ecological unpredictability and risk, scientists and policymakers working towards SDG 14 in the Asia–Pacific region need to know: (1) How are seascapes changing? (2) What can global society do about these changes? and (3) How can science and society together achieve sustainable seascape futures? Through a horizon scan, we identified nine emerging research priorities that clarify potential research contributions to marine sustainability in locations with high coral reef abundance. They include research on seascape geological and biological evolution and adaptation; elucidating drivers and mechanisms of change; understanding how seascape functions and services are produced, and how people depend on them; costs, benefits, and trade-offs to people in changing seascapes; improving seascape technologies and practices; learning to govern and manage seascapes for all; sustainable use, justice, and human well-being; bridging communities and epistemologies for innovative, equitable, and scale-crossing solutions; and informing resilient seascape futures through modelling and synthesis. Researchers can contribute to the sustainability of tropical seascapes by co-developing transdisciplinary understandings of people and ecosystems, emphasising the importance of equity and justice, and improving knowledge of key cross-scale and cross-level processes, feedbacks, and thresholds. [ABSTRACT FROM AUTHOR]

Long waves play an important role in coastal inundation and shoreline and dune erosion, requiring a detailed understanding of their evolution in nearshore regions and interaction with shorelines. While their generation and dissipation mechanisms are relatively well understood, there are fewer studies describing how reflection processes govern their propagation in the nearshore. We propose a new approach, accounting for partial reflections, which leads to an analytical solution to the free wave linear shallow-water equations at the wave-group scale over general varying bathymetry. The approach, supported by numerical modeling, agrees with the classic Bessel standing solution for a plane sloping beach but extends the solution to arbitrary alongshore uniform bathymetry profiles and decomposes it into incoming and outgoing wave components, which are a combination of successively partially reflected waves lagging each other. The phase lags introduced by partial reflections modify the wave amplitude and explain why Green's law, which describes the wave growth of free waves with decreasing depth, breaks down in very shallow water. This reveals that the wave amplitude at the shoreline is highly dependent on partial reflections. Consistent with laboratory and field observations, our analytical model predicts a reflection coefficient that increases and is highly correlated with the normalized bed slope (bed slope relative to wave frequency). Our approach shows that partial reflections occurring due to depth variations in the nearshore are responsible for the relationship between the normalized bed slope and the amplitude of long waves in the nearshore, with direct implications for determining long-wave amplitudes at the shoreline and wave runup. [ABSTRACT FROM AUTHOR]

Nearshore rocky reefs with scales of order 10–100 m are common along the world's coastline and often shape wave‐driven hydrodynamics and shoreline morphology in their lee. The interaction of waves with these reefs generally results in either two or four‐cell mean circulation systems (2CC and 4CC, respectively), with diverging flows behind the reefs and at the shoreline in the 2CC case and flows that diverge in the lee and converge at the shoreline in the 4CC case. By applying a phase‐resolving wave‐flow model to conduct a detailed analysis of mean momentum balances for waves interacting with nearshore reefs, we develop an understanding of the drivers of 2CC and 4CC flow dynamics and how they vary for different reef geometries and wave and water level conditions. The 2CC or 4CC patterns were primarily driven by alongshore pressure gradients toward the exposed (nonreef fronted) or reef‐fronted beach. These alongshore pressure gradients were dependent on the cross‐shore setup dynamics governed by the balance between pressure (i.e., related to the setup) and radiation stress gradients, and mean bottom stresses exerted on the water column. If shoreline wave setup in the lee of the reef was less than the exposed beach, a 4CC pattern developed with convergent flow at the shoreline in the lee of the reef; otherwise, a 2CC emerged with divergent flow at the shoreline. Across the parameter space investigated, reef roughness, distance to the shoreline, and beach slope were the three parameters most likely to change the flow patterns between 2CC and 4CC. Plain Language Summary: Small‐scale nearshore rocky reefs are found worldwide along a variety of sandy and rocky coastlines. Wave breaking over small reefs drives mean alongshore circulation patterns in their lee that may cause shoreline accretion or erosion. In this study, we apply a wave‐flow model to investigate the physical drivers of the mean currents in the lee of small reefs. The alongshore circulation was primarily driven by the differences of the mean water levels between the lee and the adjacent nonreef fronted beaches. Mean water levels increased by wave breaking; however, the onshore‐directed mean flows over the reef created offshore‐directed bottom stresses that reduced the mean water levels in the reef lee. If the shoreline mean water levels in the lee were less than the adjacent beach, alongshore currents that converged from the adjacent beaches toward the reefs were developed. If the shoreline mean water levels in the lee of the reef exceeded the adjacent beach, alongshore currents that diverged from the reef toward the adjacent beach occurred. The improved understanding of the circulation drivers developed in this study enhances our ability to characterize and predict wave‐driven flows in small‐scale nearshore reef systems. Key Points: Phase‐resolved model simulations were used to understand circulation patterns that occur in the lee of small‐scale reefsTwo‐cell and four‐cell circulation patterns were primarily driven by alongshore pressure gradients, which depend on the setup dynamicsA four‐cell pattern generally developed if the shoreline wave setup in the lee of the reef was less than the adjacent nonreef fronted beach [ABSTRACT FROM AUTHOR]

Wave breaking on the steep fore‐reef slopes of shallow fringing reefs can be effective at dissipating incident sea‐swell waves prior to reaching reef shorelines. However, wave setup and free infragravity waves generated during the sea‐swell breaking process are often the largest contributors to wave‐driven water levels (wave runup) at the shoreline. Laboratory flume experiments and a two‐dimensional vertical phase‐resolving nonhydrostatic wave‐flow model, which includes a canopy model to predict drag forces generated by roughness elements, were used to investigate wave‐driven water levels for along‐shore uniform fringing reefs. In contrast to many previous studies, both the laboratory experiment and the numerical model account for the effects of large bottom roughness. The numerical model reproduced the observations of the wave transformation and runup over both smooth and rough reef profiles. The numerical model was then extended to quantify the influence of reef geometry and compared to simulations of plane beaches lacking a reef. For a fixed offshore forcing condition, the fore‐reef slope controlled wave runup on reef‐fronted beaches, whereas the beach slope controlled wave runup on plane beaches. As a result, the coastal protection utility of reefs is dependent on these slopes. For our examples, with a fore‐reef slope of 1/5 and a 500 m prototype reef flat length, a beach slope of ∼1/30 marked the transition between the reef providing runup reduction for steeper beach slopes and enhancing wave runup for milder slopes. Roughness coverage, spacing, dimensions, and drag coefficient were investigated, with results indicating the greatest runup reductions were due to tall roughness elements on the reef flat. Plain Language Summary: Wave breaking and bottom friction are effective at reducing incident sea‐swell waves before they can reach the shoreline of reef‐fronted coastlines. However, globally, mass mortality of coral reef‐building organisms is causing coral reefs to become structurally flatter, a process that may lower wave dissipation. Laboratory flume experiments and a multilayer phase‐resolving wave‐flow model that includes drag forces generated by roughness elements (representing coral reef forms) were used to investigate wave‐driven water levels in the lee of fringing reefs and assess the influence of reef geometry and roughness characteristics. The numerical model was able to reproduce laboratory observations of waves and water levels over both smooth and rough reef profiles. Wave runup, the vertical extent of wave uprush on a beach, was sensitive to the presence and characteristics of roughness. Roughness coverage, spacing, and dimensions were investigated with results indicating the greatest runup reductions were due to tall roughness elements on the reef flat. Key Points: SWASH reproduced laboratory observations of waves and runup over both smooth and rough fringing reefsFore‐reef slope controls wave runup on reef‐fringed coasts as opposed to beach slope on plane open coast beachesWave runup was sensitive to bottom roughness with tall roughness elements on the reef flat generating the greatest runup reduction [ABSTRACT FROM AUTHOR]

An accurate representation of physical and biological processes is crucial to resolve larval dispersal pathways and characterize connectivity of coral reef ecosystems. We investigate how hydrodynamic forcings drive larval retention rates during the bi‐annual mass coral spawning of the coral genus Acropora within a coral reef atoll (Mermaid Reef), located off northwestern Australia. By analyzing hydrodynamic conditions during 41 yr of historical spring and autumn coral spawning events, we identify typical and extreme hydrodynamic forcing conditions. Particle tracking using the output from a fine‐scale coupled wave‐flow hydrodynamic model forced with typical hydrodynamic conditions during coral spawning, revealed a mean transport of larvae eastward across the atoll. Transport was mainly driven by a combination of wave and tidal currents, where the residual tidal flow and unidirectional wave flow increased the net export of particles, and the oscillatory tidal (non‐residual) flow reduced the net export of particles from the reef. Importantly, however, numerical simulations forced with extreme hydrodynamic conditions generated by episodic tropical cyclones (11 out of 41 yr) showed large deviations from the typical eastward flow during autumn spawning, generating different connectivity pathways within the reef. Considering the substantial time larvae can be retained within reef systems, overlooking fine‐scale hydrodynamic processes may greatly overestimate larval transport distances between adjacent coral reef atolls. As a result, we emphasize the need to consider fine‐scale hydrodynamic processes within regional connectivity predictions, which is generally not considered yet critical to understand the capacity of reefs to recover following disturbances. [ABSTRACT FROM AUTHOR]

Background: Repeat colonoscopy may be required for tumour localisation. The aim of the study is to explore the clinical settings it was used and benchmark the quality of initial colonoscopy against standardized guidelines for tumour localisation, tattooing and colonoscopy reporting amongst clinicians. Methods: A retrospective study from 2016 to 2021 has been performed on patients who underwent elective colorectal cancer resections at the Northern Hospital. Patient demographics, colonoscopic and operative details were retrieved from the Bi‐National Colorectal Cancer Audit (BCCA) Registry database and hospital medical records. Primary outcomes: changes in operative approach and delays to operation. Secondary outcomes: reasons for a repeat colonoscopy and complications from repeat colonoscopy. Results: A total of 339 patients were included in this study. 94 (28.6%) underwent a repeat colonoscopy. Re‐scoping rate was 29.6% for surgeons, and 26.2% for non‐operating endoscopists. Surgeons had a 5.9% localisation error rate, and non‐operating endoscopist 6.95% (p = 0.673). Surgeons did not have a lower rate of repeat colonoscopy (p = 0.462). Repeat endoscopy was associated with a longer time to definitive operation (p < 0.001). No complications were associated with a repeat colonoscopy. Conclusion: There was no difference in localisation error rates or repeat colonoscopy amongst surgeons (29.6%) and non‐operating endoscopists (26.2%) (p = 0.462). This could be explained by the standardized endoscopy training in Australia governed by a common training board. Lack of tattooing at index colonoscopy and inadequate documentation often led to a repeat endoscopy, which was associated with a longer time to definitive operation. Standardized guidelines in tattooing of lesions and colonoscopy reporting should be implemented. [ABSTRACT FROM AUTHOR]

Atoll societies have adapted their environments and social systems for thousands of years, but the rapid pace of climate change may bring conditions that exceed their adaptive capacities. There is growing interest in the use of 'nature-based solutions' to facilitate the continuation of dignified and meaningful lives on atolls through a changing climate. However, there remains insufficient evidence to conclude that these can make a significant contribution to adaptation on atolls, let alone to develop standards and guidelines for their implementation. A sustained programme of research to clarify the potential of nature-based solutions to support the habitability of atolls is therefore vital. In this paper, we provide a prospectus to guide this research programme: we explain the challenge climate change poses to atoll societies, discuss past and potential future applications of nature-based solutions and outline an agenda for transdisciplinary research to advance knowledge of the efficacy and feasibility of nature-based solutions to sustain the habitability of atolls. This article is part of the theme issue 'Nurturing resilient marine ecosystems'. [ABSTRACT FROM AUTHOR]

When the fundamental natural frequency of marine structures is comparable to the dominant frequency of incident waves, the response of the load on the structure will be amplified. Accurately quantifying how wave loads can be amplified by incident wave conditions must thus be considered in any structural analysis, given how sensitive these characteristics are to different wave impact types. Systematic physical model tests of wave impacts on the simple horizontal plate and the vertical wall with a horizontal overhanging cantilever slab were performed. By first comparing quasi-static wave load estimates along a simple horizontal plate (obtained by low-pass filtering the pressure time series at different cut-off frequencies) with quasi-static uplift pressures from established predictive formulations, a cut-off frequency of 7 Hz was found to accurately separate the quasi-static component from impulsive wave impacts. By applying the low-pass filtering approach with the selected cut-off frequency to the pressure measurements for the vertical wall with a horizontal cantilever slab case, the impulsive and quasi-static peaks were attained, which were then used to quantify the probabilities of individual impulsive, dynamic, and quasi-static wave impacts. Incoming wave conditions and structural clearance had a significant effect on the probabilities of different wave impacts. With the increasing wave height and wave steepness, wave impacts on the horizontal slab and vertical wall were increasingly of the impulsive type and less frequently of the quasi-static type, while the probability of dynamic impact types were relatively stable. As the overhanging slab was shifted from elevated to submerged, the dominant type of wave impact on the structure was variable, ranging from impulsive to dynamic to quasi-static as its elevation was lowered. The results indicated that up to 90% of the impacts were of the impulsive type when the overhanging slab was on or slightly over the still water level. Moreover, the presence of the vertical wall increased the magnitude of wave loads and the occurring frequency of impulsive wave impacts for the horizontal slab. [ABSTRACT FROM AUTHOR]

Background: As coronavirus (COVID‐19) cases continue to rise, healthcare workers have been working overtime to ensure that all patients receive care in a timely manner. Our study aims to identify the impact and outcomes of COVID‐19 on colorectal cancers presentations across the five major colorectal units in Melbourne, Australia. Methods: This is a retrospective study from a prospectively collected database from the binational colorectal cancer audit (BCCA) registry, as well as inpatient records. All patients with colorectal cancer between Pre‐COVID‐19 period (1 July 2018–2030 June 2019) and COVID‐19 period (1 July 2020–2030 June 2021) were compared. Benign pathology and other cancer types were excluded. Results: A total of 1609 patients were included in the study (700 Pre‐COVID‐19 period, 906 COVID‐19 period). During COVID‐19 period, there was a higher proportion of emergency surgery (28.1% vs. 19.8%; P < 0.001), a higher nodal (P = 0.024) and metastatic stage (P = 0.018) at presentation, but no increase in the rate of return to operating theatres (P = 0.240), inpatient death (P = 0.019) or 30‐day readmission (P = 0.000). There was also no difference in the post‐operative surgical complications (P = 0.118). Utility of neoadjuvant therapy did not increase during the pandemic (P = 0.613). Conclusion: The heightened measures in the healthcare system ensured CRC patients still received their surgery in a timely fashion. With the current rise in the new strain of COVID‐19 (Omicron), we have to continue to come up with new strategies to provide timely access to CRC care. [ABSTRACT FROM AUTHOR]

Aim: Genetic connectivity is a key component of species resilience to climate change in terms of recovery capacity following disturbance and capacity to disperse to novel locations as the climate warms and isotherms shift poleward. We aimed to strengthen our understanding of resilience in this context by characterizing patterns of connectivity and genetic diversity in a broadcast spawning coral across a tropical-- temperate transition zone. We hypothesize genetic differentiation between tropical and temperate populations and decreasing genetic diversity with higher latitudes. Location: Western Australia (WA). Taxon: Turbinaria species complex. Turbinaria reniformis' Oken, 1815 (Scleractinia: Dendrophylliidae). Methods: A total of 930 target corals were sampled from 10 locations between 13 and 32° latitude spanning a 9°C mean temperature range. In situ species identification of T. reniformis is hindered by morphological plasticity and homoplasy with sister species. We combined Sanger sequencing of two mitochondrial DNA markers and high-throughput genotyping by sequencing (GBS) to isolate a single genetic Turbinaria lineage from our dataset through which patterns of genetic flow and diversity along the WA coastline could be explored using population- and individual-based clustering analyses. Results: Mitochondrial DNA sequence variation was low among Turbinaria samples and could not resolve individual species. Using GBS, we identified three genetically distinct lineages. Subsequent analyses within one of these lineages revealed strong spatial subdivision with 2-3 genetic clusters. While temperate populations were genetically diverged from more tropical sites, we did not observe declines in genetic diversity with latitude. Main conclusions: Tropical populations of T. 'reniformis' in Western Australia exhibit strong genetic connectivity, which extends to a southern limit at sub-tropical Shark Bay. Temperate populations are genetically isolated from their tropical counterparts but have relatively high genetic diversity. While the maintenance of genetic variation in temperate populations may provide some resilience to future climate scenarios, their isolation may increase their vulnerability. [ABSTRACT FROM AUTHOR]

A field experiment study of flow transport around a coral reef was conducted at Scott Reef, an offshore atoll in the Timor Sea. A drifter deployment was designed based on the insight derived from two Lagrangian data analysis approaches, the finite‐time Lyapunov exponent method and the optimized‐parameter spectral clustering method, which were used to analyze the predictions of a numerical model. This analysis predicted the formation of a key transport barrier during a critical time of the tidal cycle that separated two bodies of water, one remaining trapped within the lagoon, and one advected offshore; this transport structure had no clear signature upon inspection of the velocity fields and thus the use of Lagrangian methods was crucial. The observed drifter trajectories confirmed the predictions, with the drifters separating into two clusters, one on each side of the transport barrier. The results demonstrate how Lagrangian approaches elucidate the processes governing connectivity and water exchanges between atolls and the surrounding ocean. [ABSTRACT FROM AUTHOR]

Many users of search systems are multilingual, that is, they are proficient in two or more languages. In order to better understand and support the language preferences and behaviors of such multilingual users, this paper presents a series of five large‐scale studies that specifically elicit language choices regarding search queries and result lists. Overall, the results from the studies indicate that users frequently make use of different languages (i.e., not just their primary language), especially when they are provided with choices (e.g., when provided with a secondary language query or result list choice). In particular, when presented with a mixed‐language list choice, participants choose this option to an almost equal extent compared to primary‐language‐only lists. Important factors leading to language choices are user‐, task‐ and system‐related, including proficiency, task topic, and result layout. Moreover, participants' subjective reasons for making particular choices indicate that their primary language is considered more comfortable, that the secondary language often has more relevant and trustworthy results, and that mixed‐language lists provide a better overview. These results provide crucial insights into multilingual user preferences and behaviors, and may help in the design of systems that can better support the querying and result exploration of multilingual users. [ABSTRACT FROM AUTHOR]

Long waves are generated and transform when short-wave groups propagate into shallow water, but the generation and transformation processes are not fully understood. In this study we develop an analytical solution to the linearized shallow-water equations at the wave-group scale, which decomposes the long waves into a forced solution (a bound long wave) and free solutions (free long waves). The solution relies on the hypothesis that free long waves are continuously generated as short-wave groups propagate over a varying depth. We show that the superposition of free long waves and a bound long wave results in a shift of the phase between the short-wave group and the total long wave, as the depth decreases prior to short-wave breaking. While it is known that short-wave breaking leads to free-long-wave generation, through breakpoint forcing and bound-wave release mechanisms, we highlight the importance of an additional free-long-wave generation mechanism due to depth variations, in the absence of breaking. This mechanism is important because as free long waves of different origins combine, the total free-long-wave amplitude is dependent on their phase relationship. Our free and forced solutions are verified against a linear numerical model, and we show how our solution is consistent with prior theory that does not explicitly decouple free and forced motions. We also validate the results with data from a nonlinear phase-resolving numerical wave model and experimental measurements, demonstrating that our analytical model can explain trends observed in more complete representations of the hydrodynamics. [ABSTRACT FROM AUTHOR]

Two-dimensional mean wave-driven flow and setup dynamics were investigated at a reef-lagoon system at Ningaloo Reef, Western Australia, using the numerical wave-flow model, SWASH. Phase-resolved numerical simulations of the wave and flow fields, validated with highly detailed field observations (including >10 sensors through the energetic surf zone), were used to quantify the main mechanisms that govern the mean momentum balances and resulting mean current and setup patterns, with particular attention to the role of nonlinear wave shapes. Momentum balances from the phaseresolved model indicated that onshore flows near the reef crest were primarily driven by the wave force (dominated by radiation stress gradients) due to intense breaking, whereas the flow over the reef flat and inside the lagoon and channels was primarily driven by a pressure gradient. Wave setup inside the lagoon was primarily controlled by the wave force and bottom stress. The bottom stress reduced the setup on the reef flat and inside the lagoon. Excluding the bottom stress contribution in the setup balance resulted in an over prediction of the wave-setup inside the lagoon by up to 200--370%. The bottom stress was found to be caused by the combined presence of onshore directed wave-driven currents and (nonlinear) waves. Exclusion of the bottom stress contribution from nonlinear wave shapes led to an over prediction of the setup inside the lagoon by approximately 20--40%. The inclusion of the nonlinear wave shape contribution to the bottom stress term was found to be particularly relevant in reef regions that experience a net onshore mass flux over the reef crest. [ABSTRACT FROM AUTHOR]

Accurate prediction of coastal flooding requires a detailed understanding of all individual contributions to sea level variability and how they interact to trigger extreme sea level (ESL) events. In this study, we focus on the expansive (∼10,000 km) coastline of Western Australia, a region that experiences large latitudinal gradients in met‐ocean sources of sea level variability, as a case study to investigate the mechanisms responsible for ESLs and trends over the past 54 years (1966–2019). Using long‐term sea level records from tide gauges and satellite altimetry, we explore how different contributions to sea level variability at different time scales (from hourly to interannual) interact to generate ESLs. We observe that all individual, nontidal contributions to ESLs (i.e., atmospheric surge, seasonal and interannual variability) are of similar magnitude (of order 10 cm) along the entire coast and comparable to the tidal variations in the microtidal southwestern region. The results reveal the important role that seasonal and interannual sea level variability plays in generating ESLs, with these low‐frequency contributions being relatively large compared to typical global values. With mean sea level having risen by ∼10 cm over this 54‐year study period, sea level rise was also identified as making an increasingly significant contribution to observed increases in the frequency of ESLs. Overall, due to the comparatively large magnitude of low‐frequency sea level contributions (seasonal and longer), the Western Australia coast provides a useful case study to investigate how sustained periods of elevated sea level will impact coastlines worldwide more broadly in the future. Plain Language Summary: Accurate prediction of coastal flooding requires a detailed understanding of the diverse contributions to sea level variability and how they interact to trigger extreme sea level events. In this study, we focus on the expansive (∼10,000 km) coastline of Western Australia, a region that experiences large differences in the sources of sea level variability, as a case study to investigate the causes of sea level extremes over the past 50 years. We combine coastal tide gauge observations and satellite sea level measurements to explore how different contributions to sea level over different time scales (ranging from hours to decades) generate extreme events, including how these contributions have evolved over time. The results reveal the important role that seasonal and interannual sea level variability plays in generating extreme events, which are relatively large compared to typical global values. With mean sea level having risen by ∼10 cm over the study period, sea level rise was also identified as making an increasingly significant contribution to the elevated frequency of extreme events. The Western Australia coast provides a useful global case study to investigate how sustained periods of elevated sea level will impact coastlines more broadly in the future. Key Points: Coastal sea level records were analyzed to isolate the processes responsible for extreme sea level events along Western AustraliaLow‐frequency contributions to sea level variability (seasonal and interannual) were large and comparable to tides and surgesInterannual variability explained clustering of extremes with strong links to global climate cycles [ABSTRACT FROM AUTHOR]

Coral reefs generate substantial volumes of carbonate sediment, which is redistributed throughout the reef‐lagoon system. However, there is little understanding of the specific processes that transport this sediment produced on the outer portions of coral reefs throughout a reef‐lagoon system. Furthermore, the separate contributions of currents, sea‐swell waves, and infragravity waves to transport, which are all strongly influenced by the presence of a reef, is not fully understood. Here, we show that in reef‐lagoon systems most suspended sediment is transported close to the seabed and can, at times, be suspended higher in the water column during oscillatory flow transitions (i.e., near slack flow) at sea‐swell wave frequencies, and during the peak onshore oscillatory velocity phase at infragravity wave frequencies. While these wave frequencies contribute to the transport of suspended sediment offshore and onshore, respectively, the net flux is small. Mean currents are the primary transport mechanism and responsible for almost 2 orders of magnitude more suspended‐sediment flux than sea‐swell and infragravity waves. Whilst waves may not be the primary mechanism for the transport of sediment, our results suggest they are an important driver of sediment suspension from the seabed, as well as contributing to the partitioning of sediment grain sizes from the reef to the shoreline. As the ocean wave climate changes, sea level rises, and the composition of reef benthic communities change, the relative importance of mean currents, sea‐swell waves, and infragravity waves is likely to change, and this will affect how sediment is redistributed throughout reef‐lagoon systems. Plain Language Summary: Most of the sandy sediment found on coral reef coastlines is produced by organisms living within the reef. This sediment is then transported by waves and currents across the reef and distributed throughout the lagoon. Little is known about these transport processes, including the relative importance of how currents or different types of waves drive transport. This study shows that most of the sediment in the water column (suspended sediment) is transported close to the seabed by mean currents. At times, this sediment can be suspended higher in the water column by short waves (5–25 s) when the flow transitions from being onshore directed to offshore directed, or when the velocities of longer period waves (25–250 s), called infragravity waves, are directed onshore. The timing of the suspension by these waves helps to sort the sediment into different sizes across the system, but the quantity of sediment transported is small. As the ocean wave climate changes, sea level rises, and reefs change, the relative importance of mean currents, sea‐swell waves, and infragravity waves is also likely to change, and this will affect how sediment is redistributed throughout reef‐lagoon systems. This study provides insight into what changes may be expected. Key Points: Sediment transported in suspension is 3–4 times lower than sediment transported as bedloadSediment transported in suspension by mean currents is 2 orders of magnitude greater than sediment transported by wavesSea‐swell waves typically transport sediment offshore and infragravity waves and mean currents typically transport sediment onshore [ABSTRACT FROM AUTHOR]

Coral bleaching driven by ocean warming is one of the most visible ecological impacts of climate change and perhaps the greatest threat to the persistence of reefs in the coming decades. In the absence of returning atmospheric greenhouse gas concentrations to those compatible with ocean temperatures below the mass coral bleaching temperature thresholds, the most straightforward means to reduce thermal-stress induced bleaching is to cool water at the seabed. The feasibility of reducing the seabed temperature through cool-water injections is considered first by analysing the feasibility of doing so on 19 reefs with differing physical environments using a simple residence time metric in 200 m resolution hydrodynamic model configurations. We then concentrate on the reefs around Lizard Island, the most promising candidate of the 19 locations, and develop a 40 m hydrodynamic model to investigate the effect of the injection of cool water at differing volumetric rates. Injecting 27°C seawater at a rate of 5 m³ s-1 at 4 sites in early 2017 cooled 97 ha of the reef by 0.15°C or more. The power required to pump 5 m³ s-1 through a set of pipes over a distance of 3 km from a nearby channel is*466 kW. This power applied at 4 sites for 3 months achieves a 2 Degree Heating Weeks (DHWs) reduction on 97 ha of reef. A more precise energy costing will require further expert engineering design of the pumping equipment and energy sources. Even for the most physically favourable reefs, cool-water transported through pipes and injected at a reef site is energy expensive and cannot be scaled up to any meaningful fraction of the 3,100 reefs of the GBR. Should priority be given to reducing thermal stress on one or a few high value reefs, this paper provides a framework to identify the most promising sites. [ABSTRACT FROM AUTHOR]

Tropical cyclones generate extreme waves that can damage coral reef communities. Recovery typically requires up to a decade, driving the trajectory of coral community structure. Coral reefs have evolved over millennia with cyclones. Increasingly, however, processes of recovery are interrupted and compromised by additional pressures (thermal stress, pollution, diseases, predators). Understanding how cyclones interact with other pressures to threaten coral reefs underpins spatial prioritization of conservation and management interventions. Models that simulate coral responses to cumulative pressures often assume that the worst cyclone wave damage occurs within ~100 km of the track. However, we show major coral loss at exposed sites up to 800 km from a cyclone that was both strong (high sustained wind speeds >=33 m/s) and big (widespread circulation >~300 km), using numerical wave models and field data from northwest Australia. We then calculate the return time of big and strong cyclones, big cyclones of any strength and strong cyclones of any size, for each of 150 coral reef ecoregions using a global data set of past cyclones from 1985 to 2015. For the coral ecoregions that regularly were exposed to cyclones during that time, we find that 75% of them were exposed to at least one cyclone that was both big and strong. Return intervals of big and strong cyclones are already less than 5 years for 13 ecoregions, primarily in the cyclone‐prone NW Pacific, and less than 10 years for an additional 14 ecoregions. We identify ecoregions likely at higher risk in future given projected changes in cyclone activity. Robust quantification of the spatial distribution of likely cyclone wave damage is vital not only for understanding past coral response to pressures, but also for predicting how this may change as the climate continues to warm and the relative frequency of the strongest cyclones rises. [ABSTRACT FROM AUTHOR]

The article lists 2019 periodical reviewers including Katherine Adams, Sean Bailey, and Scott Bachman.

The Australian marine research, industry, and stakeholder community has recently undertaken an extensive collaborative process to identify the highest national priorities for wind-waves research. This was undertaken under the auspices of the Forum for Operational Oceanography Surface Waves Working Group. The main steps in the process were first, soliciting possible research questions from the community via an online survey; second, reviewing the questions at a face-to-face workshop; and third, online ranking of the research questions by individuals. This process resulted in 15 identified priorities, covering research activities and the development of infrastructure. The top five priorities are 1) enhanced and updated nearshore and coastal bathymetry; 2) improved understanding of extreme sea states; 3) maintain and enhance the in situ buoy network; 4) improved data access and sharing; and 5) ensemble and probabilistic wave modeling and forecasting. In this paper, each of the 15 priorities is discussed in detail, providing insight into why each priority is important, and the current state of the art, both nationally and internationally, where relevant. While this process has been driven by Australian needs, it is likely that the results will be relevant to other marine-focused nations. [ABSTRACT FROM AUTHOR]

The physical roughness (canopies) formed by organisms within aquatic ecosystems (e.g., seagrass, kelp, and mangroves) modifies the local wave‐driven hydrodynamics within coastal and estuarine regions. In wave‐dominated environments, an understanding of the mean wave‐driven flows generated within and above canopies is important, as it governs material transport (e.g., of nutrients, sediment, and biota). However, until recently the effect of submerged canopies on wave‐current interactions and the resulting mean (wave‐averaged) flow dynamics has received relatively little attention. In this study, a combination of wave flume experiments and numerical modeling is used to investigate the wave‐induced mean flow profiles in the presence of a submerged canopy. The measured velocities and vegetation forces were used to derive bulk drag and inertia coefficients, and to validate a nonhydrostatic 2DV wave‐flow model. The numerical model results were used to conduct an in‐depth analysis of the mean horizontal momentum terms responsible for driving the mean (horizontal) flow within and above the submerged canopies. We show that the mean canopy hydrodynamics are driven by vertical gradients in wave and turbulent Reynolds stresses, balanced by the mean canopy drag forces. The wave Reynolds stress gradient is the dominant force driving the in‐canopy mean flow and is directly related to the vorticity that is generated when the wave orbital motions become rotational near the canopy interface. This study provides new insight in the mechanisms responsible for wave‐driven mean flows within submerged canopies and guidance for how these hydrodynamics can be predicted in coastal wave‐circulation models. Plain Language Summary: Aquatic plants that grow in estuaries and coastal oceans (such as seagrass, kelp, and mangroves) have a considerable influence on water flow (currents) and on waves propagating toward the shore. However, mean flows generated by the waves interacting with aquatic vegetation (with time scales much longer than the individual wave periods) have not been comprehensively studied. This study provides a description of how submerged vegetation alters the mean wave‐driven flow structure. A combination of detailed experiments conducted in a wave flume and numerical simulations are used to show that the mean flow just above the vegetation is relatively strong (up to 20% to 50% of the maximum wave velocity above the canopy), while it is considerably weaker inside the vegetation. We identified three forces that govern the mean current profile: the wave Reynolds stress gradient, the turbulent Reynolds stress gradient, and the vegetation drag force. These forces are usually not accurately described in larger‐scale computer simulations of coastal processes. However, reliable simulation of processes in the coastal ocean such as sediment transport and nutrient exchange requires an accurate prediction of mean flows, and thus these forces need to be properly incorporated in computer models when applied to regions with aquatic vegetation. Key Points: Physical and numerical modeling is used to investigate the wave‐induced mean flow profiles in the presence of submerged vegetationThe multilayered phase‐resolving wave‐ flow model was able to accurately reproduce the depth variation of the wave‐driven mean flow profilesWave‐driven mean flows inside vegetation canopies are driven by vertical gradients in the wave and turbulent Reynolds stresses [ABSTRACT FROM AUTHOR]

Purpose: Prior iterative reconstruction (PIR) spatially registers CT image data from multiple phases of enhancement to reduce image noise. We evaluated PIR in contrast-enhanced multiphase liver CT. Methods: Patients with archived projection CT data with proven malignant or benign liver lesions, or without lesions, by reference criteria were included. Lower-dose PIR images were reconstructed using validated noise insertion from multiphase CT exams (50% dose in 2 phases, 25% dose in 1 phase). The phase of enhancement most relevant to the diagnostic task was selected for evaluation. Four radiologists reviewed routine-dose and lower-dose PIR images, circumscribing liver lesions and rating confidence for malignancy (0 to 100) and image quality. JAFROC Figures of Merit (FOM) were calculated. Results: 31 patients had 60 liver lesions (28 primary hepatic malignancies, 6 hepatic metastases, 26 benign lesions). Pooled JAFROC FOM for malignancy for routine-dose CT was 0.615 (95% CI 0.464, 0.767) compared to 0.662 for PIR (95% CI 0.527, 0.797). The estimated FOM difference between the routine-dose and lower-dose PIR images was + 0.047 (95% CI − 0.023, + 0.116). Pooled sensitivity/specificity for routine-dose images was 70%/68% compared to 73%/66% for lower-dose PIR. Lower-dose PIR had lower diagnostic image quality (mean 3.8 vs. 4.2, p = 0.0009) and sharpness (mean 2.3 vs. 2.0, p = 0.0071). Conclusions: PIR is a promising method to reduce radiation dose for multiphase abdominal CT, preserving observer performance despite small reductions in image quality. Further work is warranted. [ABSTRACT FROM AUTHOR]

Seeds of Australian species of the seagrass genus Posidonia are covered by a membranous wing that we hypothesize plays a fundamental role in seed establishment in sandy, wave swept marine environments. Dimensions of the seed and membrane were quantified under electron microscopy and micro-CT scans, and used to model rotational, drag and lift forces. Seeds maintain contact with the seabed in the presence of strong turbulence: the larger the wing, the more stable the seed. Wing surface area increases from P. sinuosa < P. australis < P.coriacea correlating with their ability to establish in increasingly energetic environments. This unique seed trait in a marine angiosperm corresponds to adaptive pressures imposed on seagrass species along 7,500 km of Australia's coastline, from open, high energy coasts to calmer environments in bays and estuaries. [ABSTRACT FROM AUTHOR]

Interactions between oceanic and atmospheric processes within coral reefs can significantly alter local-scale (< km) water temperatures, and consequently drive variations in heat stress and bleaching severity. The Scott Reef atoll system was one of many reefs affected by the 2015–2016 mass coral bleaching event across tropical Australia, and specifically experienced sea surface temperature anomalies of 2 °C that caused severe mass bleaching (> 60%) over most of this system; however, the bleaching patterns were not uniform. Little is known about the processes governing thermodynamic variability within atolls, particularly those that are dominated by large amplitude tides. Here, we identify three mechanisms at Scott Reef that alleviated heat stress during the marine heatwave in 2016: (1) the cool wake of a tropical cyclone that induced temperature drops of 1.3 °C over a period of 8 days; (2) air–sea heat fluxes that interacted with the reef morphology during neap tides at one of the atolls to reduce water temperatures by up to 2.9 °C; (3) internal tidal processes that forced deeper and cooler water (up to 2.7 °C) into some sections of the shallow reefs. The latter two processes created localized areas of reduced temperatures that led to lower incidences of coral bleaching for parts of the reef. We predict these processes are likely to occur in other similar tide-dominated reef environments worldwide. Identifying locations where physical processes reduce heat stress will likely be critical for coral reefs in the future, by maintaining communities that can help facilitate local recovery of reefs following bleaching events that are expected to increase in frequency and severity in the coming decades. [ABSTRACT FROM AUTHOR]

Benthic fluxes of dissolved nutrients in reef communities are controlled by oceanographic forcing, including local hydrodynamics and seasonal changes in oceanic nutrient supply. Up to a third of reefs worldwide can be characterized as having circulation that is predominantly tidally forced, yet almost all previous research on reef nutrient fluxes has focused on systems with wave-driven circulation. Fluxes of dissolved nitrogen and phosphorus were measured on a strongly tide-dominated reef platform with a spring tidal range exceeding 8 m. Nutrient fluxes were estimated using a one-dimensional control volume approach, combining flow measurements with modified Eulerian sampling of waters traversing the reef. Measured fluxes were compared to theoretical mass-transfer-limited uptake rates derived from flow speeds. Reef communities released 2.3 mmol m -2 d -1 of nitrate, potentially derived from the remineralization of phytoplankton and dissolved organic nitrogen. Nutrient concentrations and flow speeds varied between the major benthic communities (coral reef and seagrass), resulting in spatial variability in estimated nitrate uptake rates. Rapid changes in flow speed and water depth are key characteristics of tide-dominated reefs, which caused mass-transfer-limited nutrient uptake rates to vary by an order of magnitude on timescales of ∼ minutes–hours. Seasonal nutrient supply was also a strong control on reef mass-transfer-limited uptake rates, and increases in offshore dissolved inorganic nitrogen concentrations during the wet season caused an estimated twofold increase in uptake. [ABSTRACT FROM AUTHOR]

Scott Reef is a remote yet biodiverse coral reef atoll, rising from depths > 1000 m on the edge of the continental shelf of northwestern Australia. An intensive 2‐week field study was conducted to assess how physical oceanographic processes influence reef communities in South Scott's deep (~ 50 m) and expansive (~ 300 km2) semi‐enclosed lagoon. The study covered a spring–neap tidal cycle, during which moored instruments measured temperature and velocities at a lagoon entrance and ship‐based vertical profilers measured water quality parameters. Tidally driven internal bores advected cooler and deeper offshore waters (up to 4.5°C, mean 2.4°C) into the lagoon, which were also richer in nutrients and chlorophyll a than lagoon waters. This offshore water originated from approximately 75 m depth. We used the strong observed relationship between in situ measurements of nitrate and temperature to estimate nitrate concentrations from high temporally and spatially resolved temperature measurements at the lagoon entrance, and then estimated the horizontal nitrate fluxes into the lagoon using the velocity measurements. The depth‐integrated, time‐averaged nitrate flux during spring tides (1.46 kg m−1 d−1) was over three times larger than during neap tides (0.46 kg m−1 d−1), despite a passing tropical storm that temporarily deepened the offshore thermocline and reduced the magnitude of the fluxes. Our observations indicate that colder, deeper, and nutrient‐rich water associated with internal tidal bores during spring tide is likely to be the primary mechanism through which allochtonous nutrients are delivered to benthic and pelagic communities within the lagoon of this isolated atoll. [ABSTRACT FROM AUTHOR]

Reef‐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. Ecological, sedimentological, and sediment transport data were analysed to understand the interconnections between coastal morphology and reef ecology within a fringing reef system. The sediment reservoir is predominantly derived from 'old' source material (≥ 1400 years old) but this material is supplied to the shoreline on modern timescales. These results suggest that sediment budgets of similar reef systems may be more resilient to climate change as contemporary reef health and community composition have limited influence on sediment supply. [ABSTRACT FROM AUTHOR]

Movement is fundamental to the ecology and evolutionary dynamics within species. Understanding movement through seed dispersal in the marine environment can be difficult due to the high spatial and temporal variability of ocean currents. We employed a mutually enriching approach of population genetic assignment procedures and dispersal predictions from a hydrodynamic model to overcome this difficulty and quantify the movement of dispersing floating fruit of the temperate seagrass Posidonia australis Hook.f. across coastal waters in south‐western Australia. Dispersing fruit cohorts were collected from the water surface over two consecutive years, and seeds were genotyped using microsatellite DNA markers. Likelihood‐based genetic assignment tests were used to infer the meadow of origin for seed cohorts and individuals. A three‐dimensional hydrodynamic model was coupled with a particle transport model to simulate the movement of fruit at the water surface. Floating fruit cohorts were mainly assigned genetically to the nearest meadow, but significant genetic differentiation between cohort and most likely meadow of origin suggested a mixed origin. This was confirmed by genetic assignment of individual seeds from the same cohort to multiple meadows. The hydrodynamic model predicted 60% of fruit dispersed within 20 km, but that fruit was physically capable of dispersing beyond the study region. Concordance between these two independent measures of dispersal provides insight into the role of physical transport for long distance dispersal of fruit and the consequences for spatial genetic structuring of seagrass meadows. [ABSTRACT FROM AUTHOR]

Shear stresses on vegetated beds play an important role in driving a wide range of processes at the sediment‐water interface, including sediment transport. Existing methods for the estimation of bed shear stress are not applicable to vegetated beds due to the significant alteration of the near‐bed velocity profile and turbulence intensities by the vegetation. In addition, bed shear stress distributions are highly spatially variable in the presence of vegetation. In this study, computational fluid dynamics simulations were used to investigate the spatial variability of bed shear stresses in the presence of emergent vegetation (modeled as arrays of circular cylinders) and the variation of bed stress with characteristics of both the bulk flow and the array. A recently proposed model that assumes a linear variation of stress in the viscous layer immediately above the bed is shown to be a reliable tool for estimating the spatially averaged bed shear stress over a wide range of flow conditions and vegetation densities. However, application of this model is found to be restrictive due to the lack of a reliable predictive tool for the thickness of the viscous layer. Based on a balance between turbulent kinetic energy production in the vegetation stem wakes and the viscous dissipation of turbulent kinetic energy at the bed, an enhanced formulation is proposed to predict the thickness of the viscous layer, which significantly improves the accuracy of model predictions. This improved model enhances the predictive capability for important benthic processes (such as sediment transport) in vegetated aquatic systems. Key Points: The presence of aquatic vegetation significantly alters the magnitude and spatial variability of bed shear stresses in channel flowsThe Linear Stress Model is found to be a reliable tool for estimating bed stresses within vegetation, modeled as arrays of rigid cylindersModel performance is significantly improved through a new approach for estimating the thickness of the viscous layer immediately above the bed [ABSTRACT FROM AUTHOR]

The hydrodynamics of a tidally forced semi‐enclosed coral reef atoll (North Scott) at the edge of the continental shelf of northwestern Australia were investigated by combining field observations and numerical modeling. The observations revealed that the spring tidal range outside the atoll reaches 4 m, and as the water level drops below mean sea level, the reef rim surrounding the shallow (~10–15 m) lagoon becomes exposed. During this time, the lagoon can only exchange with the open ocean through two narrow channels, resulting in highly asymmetric water levels and velocities that were most pronounced during spring tide. On average, the ebb tide duration was ~2 hr longer than the flood, with rapid flood velocities in the channel reaching 2 m/s. We applied an unstructured grid model Delft3D‐Flexible Mesh to simulate the atoll hydrodynamics and were able to replicate the asymmetric water levels and complex velocities in the lagoon. The results revealed that at higher tidal stages, a dominant momentum balance exists between the pressure gradient (established by the propagation of the tide on the shelf) and the local flow acceleration of water throughout the interior of the atoll. At lower tidal stages, which coincided with a reversal of the offshore tidal pressure gradient, the lagoon became isolated from offshore dynamics and all momentum terms were negligible. This resulted in a tidally averaged residual westward flow within the lagoon that drove an asymmetric flushing pattern within the atoll, which we propose would be a common flushing mechanism within other tide‐dominated atolls worldwide. Key Points: The hydrodynamics of a tide‐dominated atoll reef system were assessed with field observations and numerical modelingThe semi‐enclosed atoll morphology and large tidal range resulted in highly asymmetric water levels, velocities, and residual flowsA residual east‐west flow, caused by interactions between the phasing of the ocean tide and lagoon water levels, dominated flushing [ABSTRACT FROM AUTHOR]

Benthic fluxes of dissolved nutrients in reef communities are controlled by oceanographic forcing including hydrodynamic regime and seasonal changes in oceanic nutrient supply. Up to a third of reefs worldwide can be characterised as having circulation that is tidally-driven, yet almost all previous research on reef nutrient fluxes has focused on systems with wave-driven circulation. Fluxes of dissolved nitrogen and phosphorus were measured on a strongly tide-dominated (spring range > 8 m) reef platform located in the Kimberley region of northwest Australia. A one-dimensional control volume approach was used, which combines continuous measurements of flow with modified Eulerian sampling of waters traversing the reef. Measured fluxes were compared to theoretical mass-transfer-limited uptake rates derived from flow speeds. Reef communities released a moderate amount of nitrate, potentially derived from the remineralization of phytoplankton and dissolved organic nitrogen. Nutrient concentrations and flow speeds varied between the major benthic communities (coral reef and seagrass), resulting in spatial variability in estimated nitrate uptake rates. Rapid changes in flow speed and water depth are key characteristics of tide-dominated reefs, which caused mass-transfer-limited nutrient uptake rates to vary by an order of magnitude on time scales of ~minutes-hours. Seasonal nutrient supply was also a strong control on reef mass-transfer-limited uptake rates, and increases in offshore dissolved inorganic nitrogen concentrations during the wet season caused an estimated twofold increase in uptake. [ABSTRACT FROM AUTHOR]

Similar to the construction of physical ships and laboratory buildings, scientific knowledge is built incrementally and requires solid components of data, theory, and methodology at each phase of the "construction." The peer‐review process provides the necessary "inspection" and the assurance that every step of the construction is solid, particularly in regard to the proper use of the scientific method. The peer‐review process helps improve the published work by providing constructive suggestions and by safeguarding against scientific work that could later be found to be built on shaky foundations. Because no single scientist has intimate knowledge of today's many aspects of the Ocean Sciences, we rely on each other's expertise to serve as unbiased "inspectors" of published articles. Your considerable time and effort, spent reviewing JGR‐Oceans manuscript(s) during 2017, are sincerely appreciated by our editorial board and by the Ocean Science community at large. We thank you for rising to this professional challenge and for your wisdom, commitment, skill, and service. Plain Language Summary: Similar to the construction of physical ships and laboratory buildings, scientific knowledge is built incrementally and requires solid components of data, theory, and methodology at each phase of the "construction". The peer review process provides the necessary "inspection" and the assurance that every step of the construction is solid, particularly in regard to the proper use of the scientific method. The peer‐review process helps improve the published work by providing constructive suggestions, and by safe‐guarding against scientific work that could later found to be built on shaky foundations. Because no single scientist has intimate knowledge of today's many aspects of the Ocean Sciences, we rely on each other's expertise to serve as unbiased "inspectors" of published articles. Your considerable time and effort, spent reviewing JGR‐Oceans manuscript(s) during 2017, are sincerely appreciated by our editorial board, and by the Ocean Science community at large. We thank you for rising to this professional challenge, and for your wisdom, commitment, skill, and service. Key Point: The JGR‐Oceans Editors thank all the peer reviewers from 2017 [ABSTRACT FROM AUTHOR]

Abstract: Owing to their strong forcing of the ocean surface, tropical cyclones strongly modify the hydrodynamics of Australia's North West Shelf (one of the world's tropical cyclone hot spots), which in turn plays a dominant role in its sediment dynamics. Previous modeling studies have focused on describing the short‐term sediment dynamics during individual tropical cyclones but have lacked validation of the responses using field observations. As a consequence, the long‐term cumulative impact of the tropical cyclones on the residual sediment transport pathways at the shelf scale remains unclear. In this study we apply a sediment transport model over the North West Shelf, validate its performance using an extensive field data set, and implement a 14‐year‐long model simulation to assess the sediment fluxes. The model results confirm the overwhelming role tropical cyclones play on sediment transport processes over most of the shelf, despite each cyclone only influencing a small portion of the shelf at a particular time. Overall, we identified 19 tropical cyclone events over the 14‐year period, which, despite accounting for less than 5% of time, were found to drive the majority of both the suspended sediment alongshore and seaward cross‐shore transport. The results revealed significant interannual variability of the tropical cyclone‐induced sediment dynamics with greater suspended transport during the three consecutive Ningaloo Niño years (2011–2013) where sea surface temperatures off northwestern Australia were anomalously warm with elevated tropical cyclone activity. [ABSTRACT FROM AUTHOR]

Abstract: Benthic fluxes of chlorophyll a (Chl a) and particulate organic carbon (POC) and nitrogen (PON) were quantified on Tallon reef, a strongly tide‐dominated (spring range > 8 m) reef located in the Kimberley region of northwestern Australia, over a 2‐week period. Extensive hydrodynamic observations were used to construct a reef‐scale mass balance to estimate material exchange between the reef and ocean over individual tidal cycles. Additionally, a one‐dimensional control volume approach was used to estimate fluxes of Chl a in waters traversing the reef platform. Particulate material was delivered to the reef platform in a pulse during flood tide, and benthic uptake of Chl a declined to negligible values toward the end of ebb tide. On the scale of tidal cycles, a net uptake of Chl a was observed on the reef platform (on average 1.3 mg Chl a m−2 d−1), which was lower than previous studies of many reef communities. Fluxes showed variability depending on the magnitude of individual tidal cycles, which was likely related to volumes of oceanic Chl a inputs. Tallon reef was a net source of detrital POC and PON to the surrounding coastal ocean, with average POC exports ∼ 3% of the reef's benthic gross primary production. Seasonal measurements of water quality reported here are among the first records for the coastal Kimberley, and suggest that reefs in the west Kimberley may experience naturally elevated levels of phytoplankton and particulate nutrients, especially during the wet season. [ABSTRACT FROM AUTHOR]

Abstract: Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea‐swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea‐swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross‐reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave‐driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave‐driven currents. [ABSTRACT FROM AUTHOR]

Abstract: Two marine heat wave events along Western Australia (WA) during the alternate austral summer periods of 2010/2011 and 2012/2013, both linked to La Niña conditions, severely impacted marine ecosystems over more than 12° of latitude, which included the unprecedented bleaching of many coral reefs. Although these two heat waves were forced by similar large‐scale climate drivers, the warming patterns differed substantially between events. The central coast of WA (south of 22°S) experienced greater warming in 2010/2011, whereas the northwestern coast of WA experienced greater warming in 2012/2013. To investigate how oceanic and atmospheric heat exchange processes drove these different spatial patterns, an analysis of the ocean heat budget was conducted by integrating remote sensing observations, in situ mooring data, and a high‐resolution (∼1 km) ocean circulation model (Regional Ocean Modeling System). The results revealed substantial spatial differences in the relative contributions made by heat advection and air‐sea heat exchange between the two heat wave events. During 2010/2011, anomalous warming driven by heat advection was present throughout the region but was much stronger south of 22°S where the poleward‐flowing Leeuwin Current strengthens. During 2012/2013, air‐sea heat exchange had a much more positive (warming) influence on sea surface temperatures (especially in the northwest), and when combined with a more positive contribution of heat advection in the north, this can explain the regional differences in warming between these two La Niña‐associated marine heat wave events. [ABSTRACT FROM AUTHOR]

Clonality is common in many aquatic plant species, including seagrasses, where populations are maintained through a combination of asexual and sexual reproduction. One common measure used to describe the clonal structure of populations is clonal richness. Clonal richness is strongly dependent on the biological characteristics of the species, and how these interact with the environment but can also reflect evolutionary scale processes especially at the edge of species ranges. However, little is known about the spatial patterns and drivers of clonal richness in tropical seagrasses. This study assessed the spatial patterns of clonal richness in meadows of three tropical seagrass species, Thalassia hemprichii, Halodule uninervis, and Halophila ovalis, spanning a range of life-history strategies and spatial scales (2.5-4,711 km) in Indonesia and NW Australia. We further investigated the drivers of clonal richness using general additive mixed models for two of the species, H. uninervis and H. ovalis, over 8° latitude. No significant patterns were observed in clonal richness with latitude, yet disturbance combined with sea surface temperature strongly predicted spatial patterns of clonal richness. Sites with a high probability of cyclone disturbance had low clonal richness, whereas an intermediate probability of cyclone disturbance and the presence of dugong grazing combined with higher sea surface temperatures resulted in higher levels of clonal richness. We propose potential mechanisms for these patterns related to the recruitment and mortality rates of individuals as well as reproductive effort. Under a changing climate, increased severity of tropical cyclones and the decline in populations of mega-grazers have the potential to reduce clonal richness leading to less genetically diverse populations. [ABSTRACT FROM AUTHOR]

Abstract: Owing to their strong forcing at the air‐sea interface, tropical cyclones are a major driver of hydrodynamics and sediment dynamics of continental shelves, strongly impacting marine habitats and offshore industries. Despite the North West Shelf of Australia being one of the most frequently impacted tropical cyclone regions worldwide, there is limited knowledge of how tropical cyclones influence the sediment dynamics of this shelf region, including the significance of these episodic extreme events to the normal background conditions that occur. Using an extensive 2 year data set of the in situ sediment dynamics and 14 yearlong calibrated satellite ocean‐color data set, we demonstrate that alongshore propagating cyclones are responsible for simultaneously generating both strong wave‐induced sediment resuspension events and significant southwestward subtidal currents. Over the 2 year study period, two particular cyclones (Iggy and Narelle) dominated the sediment fluxes resulting in a residual southwestward sediment transport over the southern part of the shelf. By analyzing results from a long‐term (37 year) wind and wave hindcast, our results suggest that at least 16 tropical cyclones had a strong potential to contribute to that southwestward sediment pathway in a similar way to Iggy and Narelle. [ABSTRACT FROM AUTHOR]