scholarly journals WAVES ON REEFS: HOW CORAL REEFS TRANSFORM OCEAN WAVES AND HELP PROTECT COASTS

Author(s):  
Ap van Dongeren

Coral reefs help protect tropical islands and coasts against wave-induced flooding. Because ongoing population growth in coastal zones, sea level rise and coral reef degradation, flooding and subsequent damages will likely increase in the future. In this presentation we discuss our current knowledge of the physics of wave transformation on reefs derived from observations and modelling. We will also discuss research questions and data needs.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/JvTmDnoy8E0

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Christopher J. Brown ◽  
William Taylor ◽  
Colette C. C. Wabnitz ◽  
Rod M. Connolly

Abstract Coral reefs have been subject to mass coral bleaching, potentially causing rapid and widespread degradation of ecosystem services that depend on live coral cover, such as fisheries catch. Fisheries species in tropical waters associate with a wide range of habitats, so assessing the dependency of fisheries on coral reefs is important for guiding fishery responses to coral reef degradation. This study aimed to determine how fisheries catches associate with coral reefs in Queensland, Australia. Queensland’s largest fisheries did not target fish associated with reefs, but specific sectors, particularly aquarium fisheries and commercial fisheries in the mid to northern region had a high dependence on species that use coral reefs. Regions that had a greater relative area of coral reefs had higher catches of species that depend on live coral, suggesting that coral area could be used to predict the sensitivity of a jurisdiction’s fisheries to bleaching. Dynamic analysis of stock trends found that coral trout and red throat emperor, the two largest species by catch for the reef line fishery, were at risk of overfishing if habitat loss caused declines in stock productivity. Management of fisheries that are highly dependent on reefs may need to adapt to declining productivity, but further research to support ongoing reforms in Queensland’s fisheries is needed to quantitatively link reef degradation to stock production parameters is needed.


2019 ◽  
Vol 21 (10) ◽  
pp. 1745-1753
Author(s):  
Jing Guo ◽  
Kefu Yu ◽  
Yinghui Wang ◽  
Ruijie Zhang ◽  
Xueyong Huang ◽  
...  

Anthropogenic nutrient enrichment caused macroalgal blooms and further resulted in coral reef degradation in coastal and some remote reef areas of the SCS.


Author(s):  
Joseph J. Webber ◽  
Herbert E. Huppert

AbstractMotivated by shallow ocean waves propagating over coral reefs, we investigate the drift velocities due to surface wave motion in an effectively inviscid fluid that overlies a saturated porous bed of finite depth. Previous work in this area either neglects the large-scale flow between layers (Phillips in Flow and reactions in permeable rocks, Cambridge University Press, Cambridge, 1991) or only considers the drift above the porous layer (Monismith in Ann Rev Fluid Mech 39:37–55, 2007). Overcoming these limitations, we propose a model where flow is described by a velocity potential above the porous layer and by Darcy’s law in the porous bed, with derived matching conditions at the interface between the two layers. Both a horizontal and a novel vertical drift effect arise from the damping of the porous bed, which requires the use of a complex wavenumber k. This is in contrast to the purely horizontal second-order drift first derived by Stokes (Trans Camb Philos Soc 8:441–455, 1847) when working with solely a pure fluid layer. Our work provides a physical model for coral reefs in shallow seas, where fluid drift both above and within the reef is vitally important for maintaining a healthy reef ecosystem (Koehl et al. In: Proceedings of the 8th International Coral Reef Symposium, vol 2, pp 1087–1092, 1997; Monismith in Ann Rev Fluid Mech 39:37–55, 2007). We compare our model with field measurements by Koehl and Hadfield (J Mar Syst 49:75–88, 2004) and also explain the vertical drift effects as documented by Koehl et al. (Mar Ecol Prog Ser 335:1–18, 2007), who measured the exchange between a coral reef layer and the (relatively shallow) sea above.


2010 ◽  
Vol 35 (2) ◽  
pp. 9-14
Author(s):  
Suhartati M. Natsir

Seribu Islands are archipelago within Jakarta Bay built upon the pleistocene coral formation of the Sunda Shelf. The islands are characterized by unique and high biodiversity such as coral reefs. Since coral reef degradation would lead to a decrease of human prosperity, the determination of the coral reef quality is of high importance. Foraminifera offers an early warning system for the coral reef condition, as exemplified by the FORAM Index, i.e. Foraminifera in Reef Assessment and Monitoring Index. This study compared the foraminiferal community structure and the FORAM Index of two islands between the Damar Besar and Jukung. Both islands were dominated by symbiont-bearing foraminifera of the genera Amphistegina, Calcarina, Heterostegina, Marginophora, and Operculina. However, the number of benthic foraminifers at Jukung Island was higher than that at Damar Besar Island, having 17 individuals per species on average. Jukung Island was a conducive site to reef growth, as indicated by a FORAM Index (between 6,48 and 6,57), and Damar Besar Island was liable to environmental change.


Author(s):  
Marion Tissier ◽  
Jochem Dekkers ◽  
Ad Reniers ◽  
Stuart Pearson ◽  
Ap Van Dongeren

Several studies have reported the development of undular bores over fringing coral reefs (e.g, Gallagher, 1976; Nwogu and Demirbilek, 2010) but the importance of this phenomenon for reef hydrodynamics has never been studied. Yet, the transformation of a long wave (e.g., swell or infragravity wave) into an undular bore leads to significant modifications of the wave field. The formation of undulations is for example associated to a significant increase of the leading bore height. Moreover, if the undulations have enough time to develop (i.e. if the reef flat is wide enough), the initial long wave will ultimately split into a series of solitons (e.g., Grue et al., 2008). All this is likely to affect wave run-up. As reeffronted coastlines are particularly vulnerable to flooding, a good understanding of long wave transformation over the reef flat, including their possible transformation into undular bores, is crucial. In this study, we investigate undular bore development over reef-type profiles based on a series of laboratory experiments. More specifically, we aim to characterize the conditions under which undular bores develop, and analyse how their development affect the hydrodynamics at the toe of the reef-lined beach and the resulting wave run-up.


2021 ◽  
Author(s):  
Chinglen Meetei Tensubam ◽  
Alexander V. Babanin

<p>The role of surface ocean waves becomes substantial in the upper ocean layer mixing. Due to turbulence induced by the surface waves (both broken and unbroken waves), the upper ocean mixing is enhanced, and important upper ocean parameters are affected such as lowering of sea surface temperature (SST), deepening of mixed layer depth (MLD) and most interestingly, the changes in oceanic biogeochemistry. The main objective of this study is to analyze the effect of wave induced turbulence on oceanic biogeochemistry such as the supply and distribution of nutrients to tiny plants in the ocean called phytoplanktons, and how it affects their concentrations. Marine phytoplanktons formed the basis of marine ecosystem which accounts for about 45 percent of global net primary productivity and play an important part in global carbon cycle. The population of phytoplanktons depends mainly on nutrients (both micro and macro), availability of sunlight and grazing organisms. For this study, we use global coupled ocean-sea ice model ACCESS-OM2 with biogeochemical module called WOMBAT to estimate the effect of wave induced turbulence and study the difference between ‘with waves’ and ‘without waves’ effect on oceanic biogeochemistry. The same effect of wave induced turbulence on oceanic biogeochemistry are also studied by incorporating the change in wave climate such as increase in significant wave height and wind speed. From the investigation of merged satellite ocean color data from ESA’s GlobColour project for the period of 23 years between 1997 and 2019, it was found that chlorophyll-a (Chl-a, an index of phytoplankton biomass) concentration showed increasing trend of 0.015 mg/m3 globally and 0.062 mg/m3 in the Southern Ocean (SO) for the study period with p-value less than 0.01. It was also found that most of the increasing trends are shown spatially in the open ocean and decreasing trend in the coastal regions during the study period.</p>


Author(s):  
Gary T. Moore

This chapter addresses the question of how research on environmental assessment, cognition, and action can be utilized in the professional arenas of public policy, urban planning, and architectural design. Initially a discussion on three papers (Chapters 12, 13, and 14), the chapter attempts to extrapolate policy and design implications for the built environment from current knowledge on life-span developmental issues as represented by these three chapters. Suggestions of other research questions, issues, and strategies that might better inform policy and design are then discussed. In conclusion, the chapter briefly explores six general issues about the interaction of environmental cognition and research utilization. The contributions to this volume by Giovanna Axia, Erminielda Mainardi Peron, and Maria Rosa Baroni, by Lynn Liben, and by Roger Hart and Michael Conn have dealt heavily with child development and very little with aging or life-span development. Little evidence is presented from the gerontological and geriatric literatures, and less from the life-span literature. Liben presents a clear conceptualization of lifespan developmental approaches to environmental cognition, but to date there have been few studies and thus no data specifically on life-span developmental changes in environmental cognition. My chapter, therefore, will be weighted most heavily on the earlier phases of human development though, where feasible, it will comment on implications for the environment of elderly adults and on the environmental context of life-span developmental changes. Despite their titles and intentions, the three chapters focus most heavily on environmental cognition and much less on assessment and action. For example, after discussing the wide variety of possible definitions of assessment, including appraisal, evaluation, preferences, and attachment. Axia et al. focus most heavily on the cognitive aspects of schemata, representation, and organization of knowledge. Similarly, Hart and Conn valiantly take on the challenge of reporting on children's decision making and environmental behavior, but their empirical examples are also limited to cognitive and metacognitive issues. My chapter will thus also focus on environmental knowing. There are many interesting points of a theoretical and conceptual nature to raise about environmental assessment, cognition, and action from these three chapters, but this task is left to the other commentary chapter by Christopher Spencer.


2016 ◽  
Vol 21 (1) ◽  
Author(s):  
Christopher H. R. Goatley ◽  
Roberta M. Bonaldo ◽  
Rebecca J. Fox ◽  
David R. Bellwood

Coral Reefs ◽  
2016 ◽  
Vol 35 (2) ◽  
pp. 451-455 ◽  
Author(s):  
Colin K. C. Wen ◽  
Mary C. Bonin ◽  
Hugo B. Harrison ◽  
David H. Williamson ◽  
Geoffrey P. Jones

Sign in / Sign up

Export Citation Format

Share Document