Look closely and you’ll find a vast collection of commercially important fish and crustacea. Prepared figures: GG GV. We compute the surge generated by the synthetic hurricane by linearly adding the barometric surge and wind setup produced by the storm  In the presence of live corals and seagrasses, average wave height at the shoreward edge of the submerged forest and mud scour volumes in the forest decrease to 0.05 m and 0.0 m3/m (Fig 7B and 7D, âCoral and Seagrassâ). Profiles of wave height (top subplot), breaking dissipation (second subplot), frictional dissipation (third subplot) over the coral reef profile (bottom subplot), for the maximum offshore wave height (left) and mean wave height (right), for different combination of coral presence and absence. This difference is due, among other bathymetric variations, to the fact that the fringing reef lagoon is shorter than the barrier reef lagoon, so waves do not dissipate as much of their energy through bottom friction. As many communities here in the Philippines struggle with solid waste management and therefore a lot of their trash affects the local marine ecosystems, especially coral reefs. It’s estimated that 20-25% of seagrass has been lost in the last 50 years and we continue to lose an estimated 7% per year. (4) Does seagrass hold the secret to saving the worldâs coral reefs from extinction? In total, 265 species and 15,930 individuals were recorded. Understanding the connectivity of fish among different typical habitats is important for conducting ecosystem-based management, particularly when designing marine protected areas (MPA) or setting MPA networks. They function in reducing surf and shoreline energy. In both profiles, we assume that seagrasses have a typical stem diameter of dv = 0.1 cm, height of hv = 30 cm [32,33], and stem density averages Nv = 250 stems/m2 . âNo CoralâPresentâ data were computed assuming a smooth and dead reef. Mauritius oil spill: how coral reefs, mangroves and seagrass could be affected. Overall, we find again that multiple habitats provide more benefits than any single habitat alone: in the presence of a live reef and seagrasses, the average wave height at the shoreward edge of the submerged forest and the volume of mud scoured in the forest decrease to 0.08 m and 0.3 m3/m, respectively (Fig 7A and 7C âCoral & Seagrassâ). A dead barrier reef also causes average nearshore bed shear stresses to be 85% greater, at 0.48 N/m2, than what would have been observed if the reef were alive (Fig 6). In addition, V is the wind-induced longshore current, and Ïwy and Ïby are surface wind and bed shear stresses . Finally, we quantify the combined and individual effect of live reef, seagrass and mangroves on waves at the shoreward edge of the submerged mangrove forest and on the volume of mud bed scoured from the submerged forest floor. 2015).However, seagrass meadows are in decline globally, with an about 7% annual loss in surface area, on average, since 1990 (Cullen-Unsworth and Unsworth 2018). Such an approach would account for the varied ways in which different habitats reduce risks from coastal hazards and thus improve our ability to manage marine seascapes to protect communities in the future. We find that reefs are natural breakwaters , but their effectiveness varies with their level of coral cover. Mauritius oil spill: How coral reefs, mangroves and seagrass could be affected Mauritius is a biodiversity hotspot and much of the island’s unique wildlife depends on intricate connections between the reefs, lagoons, seagrass meadows and mangroves, so pollution in one … It makes good economic sense to manage these coastal resources sustainably and this book will help managers do this. https://doi.org/10.1371/journal.pone.0158094.g001, https://doi.org/10.1371/journal.pone.0158094.g002, https://doi.org/10.1371/journal.pone.0158094.t001. For the first future profile (âlive reefâ profile), the reef is initially covered with live corals and accretes vertically as sea-level rises. The biggest coral reefs are thousands of years old and usually thrive in warm, shallow water where they receive plenty of sunlight. Asexual Clonal Growth: Similar to grasses on land, seagrass shoots are connected underground by a network of large root-like structures called rhizomes. A similar pattern is observed in the sea-level rise scenario (S6 Fig). In some developing nations, while the men are out fishing, women and children visit seagrass meadows to carry out a fishing practice called gleaning. So some other habitat has to fill this gap for us. Because the barrier reef lagoon is so long, the hurricane generates a 1.2 m surge in the barrier reef profile compared to only a 0.5 m surge in the fringing reef profile. These results suggest that reefs act as dynamic low-pass filters for waves [21,83] (Fig 4), where the transmitted wave height Ht can be computed as Ht = A1 tanh [Ho / A2] (R2 â 0.6 for the âBare Reefâ scenario, black circles Fig 3B, R2 > 0.8 for all other scenarios). Degradation of coral reefs- this can result in lost of tourism revenue in countries that depend on reef-based tourism. Seagrasses, on the other hand, decrease the wave height by 1.5 cm and setup by 5 cm at the landward edge of the mud bed, and reduce the volume of mud scoured from the forest floor by 1 m3/m (Fig 9, âNo Live Habitatâ, âSeagrass Onlyâ and âCoral and Seagrassâ). Consequently, wave heights transmitted by the reefs and observed immediately shoreward of the reef flats are also identical in the two systems. Locations are approximate. The result will be a reduction in food security for developing coastal nations, a decline in commercial fisheries, and a reduction in the ocean’s ability to store man-made carbon dioxide. Yohei Nakamura, Masahiro Horinouchi, Mitsuhiko Sano, Takuro Shibuno, The effects of distance from coral reefs on seagrass nursery use by 5 emperor fishes at the southern Ryukyu Islands, Japan, Fisheries Science, 10.1007/s12562-009-0163-4, 75, 6, (1401-1408), (2009). Consequently, corals on the fringing reef are more effective at moderating the nearshore wave climate than seagrasses, although seagrasses offset the loss of live corals to some extent. Yellow stars indicate the location of profiles measured by Burke ; the red star indicates the âColsonâ profile used herein. where Cf is a friction coefficient corresponding to different bottom roughness values. Consequently, live reefs provide the same amount of wave attenuation in present and future scenarios (Fig 4, Table 3). During non-storm conditions, the wave climate consists of locally generated wind waves and of swells originating from distant storms. https://doi.org/10.1371/journal.pone.0158094.g009. How to choose the best marine conservation volunteer project for you. Accordingly, during non-storm conditions, we compute Cd for Turtle Grass following Bradley et al. Kim, M. Merrifield, K. Oleson, T. Oliver, M. Papenfus, M. Ruckelshaus, J. Left: Average ratio of breaking and frictional dissipation over the reef profiles. They walk onto the meadows collecting sea cucumbers, cuttlefish, octopus and diverse shellfish. Using idealized profiles of fringing and barrier reefs, we quantify the services supplied by these habitats using various metrics of inundation and erosion. Finally, the deep root structures associated with seagrass meadows stabilise and strengthen sediment and so protect the coastline from erosion. Seagrass is one of the most important ecosystems on this planet, vital to the overall health of the ocean. These differences in the nature and location of the main supplier of protection services has rarely been highlighted in the nearshore processes literature and might warrant further investigation, especially if some habitats are expected to be negatively affected by the impacts of climate change. Thus, we only consider cross-shore processes and ignore planform evolution processes. Filipot et al. Seagrasses are marine flowering plants that form ecologically important coastal habitats in tropic and temperate oceans, playing a key role in unison with coral reefs … To quantify the relative protective benefits of the three types of habitats, we first quantify the protection services supplied by coral reefs alone. In the barrier reef lagoon, seagrass meadows reduce average non-storm waves in the nearshore to 0.07 m, or half the mean wave height of the coral only scenario (note that most of the protection supplied by seagrasses comes from the nearshore meadow; the offshore meadow matters lessâS4 Fig). [4â6,8], using a specific set of forcing conditions that are usually storm conditions [1,6,7,17]. Coral reef, ridge or hummock formed in shallow ocean areas by algae and the calcareous skeletons of coral polyps and other coelenterates. Consequently, coral and seagrasses help reduce bed stress nearshore in the fringing reef profile, but not below the threshold of motion, as observed in the longer reef profile. Furthermore, the wave dissipating effect of the seagrasses meadows will protect these same communities from beach erosion. Until recent years most of her diving and conservation experience has been outside of the UK. This type of seagrass is often mistaken for seaweed. Fig 3 indicates the cross-shore locations where the different metrics are computed. The nearshore meadow is the one closest to the shore. We quantify the protective services supplied by the different combinations of habitats by comparing the volume of mud bed scoured from the submerged mud bed. Shoreward of the reef, we re-created the lagoon profiles based on observed and measured characteristics of the Belizean seascape [26,27] (Fig 2): the fringing reef lagoon is 0.3 km long with an average depth of 3 m; the barrier reef lagoon is 25 km long with a maximum depth of 17 m (Fig 2).  suggest values of Î³ = 0.69 and b = 1.09 for waves travelling over reefs faces, rims and flats. Species richness and abundance of fishes were significantly higher in coral reefs (234 species, 12,306 individuals) than in seagrass (38 species, 1,198 individuals) and mangrove (47 species, 2,426 individuals) habitats. Interestingly, regardless of the presence of habitats, nearshore wave height and bed shear stress values in the fringing reef profile are higher than in the barrier reef profile. In the presence of corals, waves still dissipate their energy via breaking, but the importance of frictional dissipation increases, as previously observed by Lowe et al. Results of this study demonstrate the importance of taking integrated and place-based approaches when quantifying and managing for the coastal protection services supplied by ecosystems. As observed by Zeller et al. This expression has been extensively validated against multiple datasets [51,66]. In this paper, we investigate the contribution of coral reefs, seagrass meadows and mangroves to the protection of coastal areas in two idealized reef systems (i.e., barrier and fringing reef), under present day and future (+1 m) sea-level conditions, and during both non-storm and storm conditions. In both the barrier and fringing reef profiles, once waves pass the reef, they encounter and propagate through seagrass meadows that further attenuate the incoming waves, resulting in lower wave heights and bed stresses nearshore than the no live habitat and the coral only scenarios (Fig 6). Bacteria and fungi are responsible for the decomposition of dead seagrass blades. The coral reefs and seagrass meadows of Florida Keys National Marine Sanctuary are productive habitats that support the fishing, diving, and tourism industries of the Florida Keys. Mangroves and seagrass provide food and shelter for a range of organisms M angrove and seagrass habitats are intricately connected to the coral reef ecosystem. At the coast, we compute inundation extent with a bathtub approach, where any land area below the surge elevation at the shoreline is flooded. Bar plot of average wave height at the shoreward edge of the submerged mangrove forest (top subplots) and bed scour volume over the submerged mangrove forest (bottom subplots) computed for different combinations of live reef, seagrass meadows and mangroves presence, under present sea-level conditions. However, if the reef is alive and seagrasses are absent, those quantities increase to 0.09 m and 0.3 m3/m (Fig 7A and 7C, âCoral Onlyâ). The results showed that the highest abundance in the seagrass ecosystem is Ophiolepis superba with a value of 36.48%, in the coral reef ecosystem was the type of Diadema sp with a value of 52.73%. Current address: The Nature Conservancy, Coral Gables, FL, United States of America, Affiliation The effectiveness of the mangroves can be partially, but not entirely, explained by the fact that they are the only habitat in this study that is able to moderate storm surge . At the coast, we assume the mud flat and mangrove forest migrate landward by 500 m to keep pace with sea-level rise (we assumed a 1V:500H mangrove floor slope). Vector images of corals, mangroves and seagrasses in were obtained from the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary/). Consequently, in the barrier reef profile, seagrasses provide more protection benefits than coral reefs when mangroves are absent, and, once again, seagrasses can at least partially compensate for the degradation of the reef. We measure their ability to reduce inundation levels (including surge height, wave height and wave setup) shoreward of the mangrove forest, and to reduce mud bed scour in the mangrove forest. You can find out more about which cookies we are using or switch them off in settings. Seagrass beds form an important nursery habitat for several species of fishes and invertebrates that move to coral reefs and other ecosystems as they mature. The Natural Capital Project, Stanford University, Stanford, CA, United States of America, Affiliation It provides food and shelter for many different underwater creatures. As a marine scientist and ocean lover I would be lying if I said I didn’t have moments where I become overwhelmed by the sate of our oceans. Box plots of wave height (top subplots) and bed scour (bottom subplots) values computed as a function of different combination of presence or absence of live coral, seagrasses and mangroves. ; Table 1). There is another very important element of the reef ecosystem that is often over looked: the land. Turtle feeding in a seagrass meadow. , seagrass stems sway under the action of moderately energetic waves and are fully bent under the action of larger waves. The effectiveness of mangroves can be partially attributed to the fact that waves entering the forest are relatively small, having previously travelled over a shallow, mildly sloping bed. , we use Cf = 0.2 for live reefs in Eq (6) and Cf = 0.1 for dead reefs that still have coral skeletons in place or scattered around (Table 1). Yes Human practices such as coastal development, destructive fishing practices such as trawling, anchoring and mooring damage, poor sewage treatment and pollution all negatively impact seagrass meadows. Increasingly, coastal and marine ecosystems are perceived, promoted and used as alternatives to... Methods. We also use a drag coefficient of Cdr,t = 1 for mangroves  since roots and trunks are not flexible. Conversely, surge and maximum wave height during hurricanes are larger in the barrier reef profile than in the fringing reef profile. No, Is the Subject Area "Mangrove swamps" applicable to this article? Indeed, this approach overlooks the fact that natural systems can help protect coasts from a host of hazards that occur under different forcing conditions. Many seagrass species live in depths of 3 to 9 feet (1 to 3 meters), but the deepest growing seagrass (Halophila decipiens) has been found at depths of 190 feet (58 meters). This seagrass can mostly be found growing in areas where there are many rocks or coral reefs. https://doi.org/10.1371/journal.pone.0158094.s001. No, Is the Subject Area "Shores" applicable to this article? Adapting the approach of Sheppard et al. No dependence between year and habitat type was detected for absolute counts of corals. Wave rose of non-storm record is similar. Although coral cover was higher in the back-reefs, there was a greater density of corals in the seagrass meadows than in the back-reefs (back-reef 119.5 ± 12.8, seagrass 236 ± 95.6 per 20 m 2). We also quantify the combined and individual importance of live corals and seagrasses at reducing the potential for sand erosion just offshore of the mangrove forest. Natural habitats have the ability to protect coastal communities against the impacts of waves and storms, yet it is unclear how different habitats complement each other to reduce those impacts. We also evaluate the importance of live corals on reefs by conducting the analyses under two sea-level scenarios: a present day sea-level and a future 1 m sea-level rise (SLR) scenario, assuming that reefs covered with live corals will accrete as sea-level rises. On the other hand, in the barrier reef, nearshore seagrasses supply more protection services than live corals, and under certain circumstances, seagrasses can compensate for the impacts of short-or long-term degradation of the reef. A barracuda stalks prey in a seagrass meadow in Dry Tortugas National Park, Florida. Finally, results presented herein also illustrate the importance of clearly identifying the metrics used to quantify protection services. Seagrasses are key to healthy coral reefs. During the hurricane, we compute the evolution of the offshore wave in the presence and absence of one or more habitats, assuming that waves travel over the computed storm surge. Microbial populations may be shared within the ecosystem of sediments, seagrasses and reef fish. Right: scatter plot of frictional dissipation; solid line represents an approximation of the best fit (R2>0.8). Seagrass and coral reefs of the eastern Aegean are in desperate need of protection. As a result, the dataset used in the modeling effort was reduced from more than 24,000 records to just over 14,000 (S1 Fig). [23â25]. As a consequence, habitats in the barrier reef profile cannot protect coastal regions to the same degree as habitats in the fringing reef profile (Fig 9). Dugong enjoying lunch in a seagrass meadow in the Red Sea, Egypt. Often called ârainforests of the sea,â coral reefs are home to a spectacular variety of organisms. Final Report ES-2 Specifically, we find that, while mangroves are the most effective at protecting the coast under non-storm and storm conditions, live corals and seagrasses also moderate the impact of waves and storms, thereby further reducing the vulnerability of coastal regions. Hence the drag coefficient associated with seagrasses varies widely under different hydrodynamic conditions (see, e.g, Refs [51,66] for more details). And as sea level rises, the far field impacts of coral reef degradation are even more pronounced : nearshore waves and bed shear stresses in a future dead and bare barrier reef profile are, on average, respectively 3.5 and 13 times higher than what would have been observed if the reef were still alive. 2008; Nagelkerken 2009; Du et al. The coral reef may be a barrier reef, a fringing reef or an atoll, and is covered by coral colonies. Corals on the reefs further dissipate incoming wave energy: a dead reef transmits only 6% and 17% (0.24 and 0.23 m) of the incoming maximum and mean offshore wave heights, and a live reef further reduces these two waves to 0.4% and 12% (0.18 and 0.16 m) of their initial offshore values.