Seagrasses on reef flats are also nutrient sinks, buffering or filtering nutrient and chemical inputs to the marine environment (Kennedy et al., 2010). CRC Press, New York, NY, 419 pp. Estimates of above- and below-ground net primary production (NPP) of some selected species/community types of salt marsh grasses and mangroves. The high productivity of seagrass implies a high demand for the macronutrients nitrogen and phosphorus. Copyright © 2020 Elsevier B.V. or its licensors or contributors. The primary aim of these programs is to improve conditions in the system for salmon, however, the improvements also benefit habitats on the delta of the rivers, including the restoration and recovery of damaged and degraded seagrasses in the estuaries. Mark the shoreward position of each transect with two poles visible from the offshore end of the transects. One of these benefits provided by terrestrial and coastal and marine ecosystems is carbon sequestration. In the Florida Keys, turtle grass, manatee grass, and shoal grass are the most common types of seagrass. Controls on point-source discharges and urban effluent (e.g., secondary and tertiary sewage treatment at large population centres) help to minimise impacts on seagrasses. Seagrasses are capable of quickly adapting to naturally changing environmental conditions such as storms and animal disturbance (i.e grazing), but are vulnerable to the direct and indirect effects of human activities. If tides are significant in the area, record the time at which the different depth estimates were made, and convert all of the depth measurements to mean sea level (MSL) using the tide table. A: Seagrass is like salt marsh, only completely submerged. 1, 1812433. The submerged canopy of estuarine seagrass systems has been found to decrease shallow-wave energy, thereby allowing for more efficient trapping of suspended particles and POC derived from both autochthonous and allochthonous sources (Ward et al., 1984; Fonseca and Kenworthy, 1987). Although leaf-bearing seagrass rhizomes grow vertically at rates of only a few millimeters per year (Marbá and Duarte, 1997), they form a rhizome network called ‘matte’ (Mateo et al., 1997) that, over the years, elevates above the seafloor forming reef-like structures. The role of seagrass in carbon sequestration and its potential for supporting the targets of India's Intended Nationally Determined Contribution (INDC) are discussed. Not only do seagrass ⦠Of the 60 species of seagrass found worldwide, seven grow in Florida waters. Nursery areas: The relative safety of seagrass meadows provides an ideal environment for juvenile fish and invertebrates to conceal themselves from predators. Seagrass meadows can also change the morphology of the islands as their roots systems consolidate and stabilize the lagoons, altering the flow dynamics and movements of the sand around the islands and their beaches (Daby, 2003). In the Pacific Northwest of the United States, citizen-based groups are developing habitat improvement programs to restore their damaged watersheds and seagrasses. Seagrasses also filter water and produce oxygen. However, the rapid economic development in the Maldives over the last 50 years, driven primarily by the tourism sector, has resulted in significant enrichment of the coastal lagoon waters around tourist resort and locally inhabited islands (Miller & Sluka, 1999). Seagrass litter can also act as seed material for dune formation by creating roughness and promoting sand accumulation (Hemminga and Nieuwenhuize, 1990). Mangroves and salt marshes. The reef habitat, by itself, is heterogeneous in height due to local variations in accretion rates and the time span since accretion began (Kendrick et al., 2005), resulting in within-reef variation in abiotic factors relevant to other organisms (e.g., light incidence and wave exposure). We use cookies to help provide and enhance our service and tailor content and ads. The west coast of Malaysia supports large areas of seagrass beds especially in Malacca, Port Dickson, Johor, Pangkor, Penang, and Langkawi. Other common marine species include Halodule spp. Note that, as a general rule, the deep limit of seagrass is at Secchi disc depth (Dennison and Kirkman 1996). The name seagrass stems from the many species with long and narrow leaves, which grow by rhizome extension and often spread across large "meadows" resembling grassland; many species ⦠Along with rainforests, mangroves, and coral reefs, seagrass meadows have also managed to catch the scientific community’s attention as the effects of extreme climatic events, human activities and invasive species (among others) take their toll on these little-known ecosystems. R. Ramesh, ... Ahana Lakshmi, in Coastal Management, 2019. A range of benefits. However, in many cases, the below-ground biomass of salt marshes exceeds that of above-ground production in salt marshes (Schubauer and Hopkinson, 1984). Furthermore, Syringodium sp. When comparing estimates of above- and below-ground production of mangroves and salt marshes, we see that mangroves are generally more productive than salt marshes above ground (Table 4). However, sediment accumulation can be seasonal, with net sediment accretion during summer when seagrasses reach their maximum density, and net sediment resuspension in winter when plants disappear or their density decreases (Van Keulen and Borowitzka, 2003). Although wave attenuation is maximal when the meadow occupies a large portion of the water column (i.e., more than 50%; Fonseca and Cahalan, 1992), reduction in wave energy and orbital velocity occurs even when beds are located at 5–15 m depth and the plants occupy a small portion of the water column (Verduin and Backhaus, 2000; Granata et al., 2001). P. oceanica is a long-lived species, with individual shoots and clones that live for decades and centuries, respectively (Duarte et al., 1994; Mateo et al., 1997), and the thick (1 cm) ligneous rhizomes are preserved in the sediments over millennia. We recommend strong use of Integrated Catchment Management programs for the long-term success of seagrass habitat improvements. Sometimes you can even see the oxygen bubbles escaping the seagrass. (1989) Pollard and Moriarty (1991), Alongi, D.M., 1998. Conserving and rehabilitating seagrasses is key, and the correct ecosystem management and protection can easily go hand in hand with development. Ecology of Estuaries, Volume 1: Physical and Chemical Aspects. The habitat complexity within seagrass meadows enhances the diversity and abundance of animals (Gratwicke & Speight, 2005). Subdivide the depth range of the seagrass meadow into appropriate depth intervals sufficient to obtain a reliable representation of the seagrass depth distribution. If no map is available and the distribution of the seagrass meadow is not known, some idea of its size may be obtained from aerial photos or a rough map made by using a view box from a boat and recording the extent along the coast of the seagrass bed. The importance of coastal geomorphology and geophysics, as well as large- and small-scale hydrologic features of wetlands, has been shown to strongly influence the exchange of POC between coastal and wetland systems (Twilley et al., 1985, 1997; Brinson, 1993; Twilley and Chen, 1998). Benefits of seagrass meadows. Seagrass meadows are often an important downstream habitat in coastal systems. However, there remains considerable disagreement as to whether mangroves act as net sinks or sources of POC and nutrients to estuaries and adjacent coastal systems (Boto and Bunt, 1981; Twilley et al., 1985; Alongi, 1996; Alongi et al., 1998; Dittmar and Lara, 2001). There are about 60 species of fully marine seagrasses which belong to four families, all in the order Alismatales. Stephen Granger, Hitoshi lizumi, in Global Seagrass Research Methods, 2001. There is little argument about the detrimental effects of excessive nutrient enrichment to shallow systems that contain seagrass meadows. Kennish, M.J., 1986. Coastal Ecosystem Processes. Many sea creatures make their home in seagrass meadows. Human activities which still damage seagrass beds include wastewater discharge from coastal industry and shrimp farms, siltation from coastal development and tin mining, as well as destructive fishing methods such as push nets (Chansang & Poovachiranon, 1994; Department of Marine and Coastal Resources, 2016b). 1997). Seagrass (Posidonia oceanica) meadow in Formentera Island (Spain). To determine the patterns of seagrass abundance along a gradient using a depth gradient as the example. Carbon uptake and photosynthesis in a seagrass meadow. The global export of POC from mangroves and salt marshes varies significantly between specific systems, but generally ranges between approximately 2–420 and 27–1052 g C M−2 yr−1, respectively (Alongi, 1998). Although there are conflicting reports concerning the temporal and spatial importance of such redox alterations in wetlands (McKee et al., 1988; Alongi, 1996, 1998), it is generally accepted that large amounts of underground biomass have long-term effects on sediment redox and the associated microbial/elemental cycling. To know more about seagrass beds, learn what’s been done to save them or get involved, follow events such as the World Seagrass Conference or visit the World Seagrass Association and the Project Seagrass websites. Epiphytic layers on seagrass leaves may also contribute to the trapping of particles in seagrass beds by increasing both the roughness of the canopy and the boundary layer on the leaf surface (Koch et al., 2006). A net accretion rate of 0.5 mm yr−1 was also observed in Western Australia (Walker and Woelkerling, 1988). Seagrasses can also contribute to other types of habitat diversity. CRC Press, Boca Raton, FL; Saenger, P.E., 1994. The habitats that seagrasses provide for juvenile Atlantic cod, generate nutritional (food for people) and economic ( job creation) benefits. The high productivity of seagrass implies a high demand for the macronutrients nitrogen and phosphorus. As Sandy Hausman reports, itâs the largest project of its kind in the world, offering benefits on many fronts. The benefits of seagrasses can also be felt on land, as these plants stabilise sediments and protect our shorelines from erosion. Seagrass roots and rhizomes absorb and store nutrients and help to anchor the seagrass plants in place. Repeat for each sampling transect at the predetermined depth intervals and move on to the next line-of-sight transect across the seagrass bed. (Day et al., 1989; Hillman et al., 1989; Czerny and Dunton, 1995). T.S. Seagrass defends against climate change, protects biodiversity, and is home to numerous keystone species. 22.1). Seagrass meadows are important ecosystems, very much comparable in appearance to grasslands in terrestrial ecosystems (Figure 5). Christopher Harman, ... Helene Frigstad, in World Seas: an Environmental Evaluation (Second Edition), 2019. Other studies have shown that above-ground production of S. alterniflora is negatively correlated with latitude (Turner, 1976; Dame, 1989) and positively correlated with tidal range (Steever et al., 1976). There are, in fact, a growing number of initiatives around the globe with goals aiming towards providing knowledge and mapping support, ensuring seagrass bed restoration, and seeking policy-based solutions to better protect them. This chapter examines the distribution and status of the seagrass ecosystems in India, highlights the blue carbon potential of seagrasses, and reflects on the conservation and restoration practices to recommend priorities in the management of seagrass ecosystems. The benefits of seagrass meadows Seagrass has a high turnover of leaves and the dead ones fall into oxygen-poor sediments below where they trap carbon. Mangroves and salt marshes. Despite the ecological benefits, which will ultimately also benefit the local communities and the tourism sector in many ways, seagrass meadows have yet to receive any protection in the Maldives and are increasingly threatened globally (Orth et al., 2006; Waycott et al., 2009). These meadows rival tropical forests and efficient crops as the most productive ecosystems on Earth (Duarte and Chiscano, 1999), and are a source of important ecosystem services to humans, such as support for biodiversity, carbon sequestration, and sediment stabilization and coastal protection (Duarte, 2000; Hemminga and Duarte, 2000; see Chapter 12.06). CRC Press, New York, NY, 419 pp. Location-specific major threats to seagrass ecosystems and their impacts have been examined. Eutrophication of the island lagoons is also a likely contributing factor to the blooms of filamentous algae which occur during periods of extremely calm weather at the onset of the northeast monsoon (December), smothering lagoon coral colonies (G. Stevens pers. The resort management companies therefore spend large sums of money to eradicate or control the seagrass beds from the lagoons surrounding their properties: utilizing dredging, sheet smothering, manual removal, and the use of chemicals (Daby, 2003) (Fig. As noted earlier, accretion of recalcitrant root and rhizome material by certain species of seagrass can lead to the formation of seagrass reefs. Despite all this, seagrass coverage is being lost globally at a rate of 1.5 % per year. Each square metre of seagrass is capable of absorbing 83 grams of carbon per year, and seagrass meadows hold around 15% of the carbon stored in the ocean. Indeed, seagrass habitats are often considered as ‘biodiversity hot spots’ and ‘nursery habitats’ because of their respective roles in sustaining higher species richness than nearby unvegetated habitats, and because of enhanced growth and survival of juveniles of commercially important species (Heck and Thoman, 1984; Beck et al., 2001). Along the Norwegian Coast, seagrass meadows (mainly Zostera marina) are found from the North (the Norwegian Sea and Barents Sea), along the Western Coast, to the South (Skagerrak), from the intertidal zone down to a maximum of 12 m (Bekkby et al., 2008). Table 3. However, to date there has been little effort to survey and assess the composition and extent of the seagrass habitat (Milchakova et al., 2005; Payri, N’Yeurt, & Mattio, 2012; Short, Carruthers, Dennison, & Waycott, 2007). 10.3. The well-being of human communities all around the globe is closely tied to the health of seagrass meadows. Seagrass meadows provide multiple benefits to adjacent coral reefs through various microhabitat functions. In other cases, wetlands have been found to import DOC at a much higher rate than POC export (Childers et al., 1999). Seven species of seagrasses, across six genera, have been recorded in the Maldives (Milchakova, Phillips, & Ryabogina, 2005; G. Stevens, pers. Seagrass leaf litter, which can represent as much as 50–60% of total leaf production, can accumulate in large piles of detritus (e.g., typically along sandy beaches) (Mateo et al., 2003), before they become small enough to be dispersed into the water column and sediments. âThe seagrass meadows make the water clearer. Field estimates indicate that the potential for particle contact with leaf surface sometimes approaches 100% in Zostera marina canopies (Ackerman, 2002). It's estimated that 35% of the world’s seagrass has already been lost. Community and industry training and participation is facilitated by government agencies through environment monitoring (e.g., community Seagrass-Watch programs; citizens beach monitoring programs), and changes in land use (Integrated Catchment Management and Landcare programs in Australia; “Adopt a Beach” programs and watershed associations in the United States). Guy M.W. However, the exact threshold where these effects are seen is still the subject of debate. (Lugo and Snedaker, 1974; Robertson and Alongi, 1992). CRC Press, New York, NY, 419 pp, Ward et al., 1984; Fonseca and Kenworthy, 1987, Roman and Able, 1988; Caffrey and Kemp, 1990, 1991; Barko et al., 1991, Kirby and Gosselink, 1976; Pomeroy and Wiegert, 1981, Moran et al., 1991; Moran and Hodson, 1994; Trefry et al., 1994, Lugo and Snedaker, 1974; Robertson and Alongi, 1992, Boto and Bunt, 1981; Twilley et al., 1985; Alongi, 1996; Alongi et al., 1998; Dittmar and Lara, 2001. It is a massive program that has resulted in measurable improvements in seagrass cover in the bay (Orth et al. As one of the planets most effective and efficient coastal systems for carbon sequestration, proper conservation and management of seagrass meadows is ⦠Carlos M. Duarte, Hugh Kirkman, in Global Seagrass Research Methods, 2001. These seagrass reefs lead to a coastal topography comparable to that of tropical bays, where a reef located 1–2 m below the water surface occurs a few hundred meters offshore, confining a shallow lagoon between the reef and the beach. In fact, mangrove forests may be similar to tropical rainforests in that a significant fraction of the organic matter pool is stored in living biomass as a mechanism for retaining nutrients (Archibold, 1995; Alongi et al., 2001). Mangroves and seagrass also filter pollutants, absorb excess nutrients from runoff, and trap sediments, helping to increase the clarity and quality of waters. Despite all this, seagrass coverage is being lost globally at a rate of 1.5 % per year. Scientists have restored vast sea grass meadows off Virginia's Eastern Shore. Moreover, several options for the sustainable use of seagrass meadow zones exist, such as ecotourism or the sustainable production of food (fish and other natural sea products). If a tidal gauge is available nearby, correct the depth measurements, if necessary, for barometric deviations from MSL, which may exceed 50 cm in some areas. The fact that seagrass is a rooted angiosperm implies an obvious dependence upon the sediment. A habitat improvement program will require education directed at several sectors to encourage changes in community behaviour to protect seagrasses. A similar mechanism could also contribute to increased delivery of suspended particulate food to the seabed observed in seagrass meadows together with a concomitant increase in the growth of benthic organisms (Judge et al., 1993; Irlandi, 1996). Here, large rolls of weighted plastic sheeting were used to cover the seagrass beds in an attempt to kills the plants © Guy Stevens. Warren J. Lee Long, Ronald M. Thom, in Global Seagrass Research Methods, 2001. Greening: Seagrass traps sediment that would otherwise be suspended in the water column, leading to clearer water. Indeed, the increase in Maldives seagrass meadows is often viewed negatively, especially by the tourism sector. Seagrass litter often accumulates in beaches. ), Marine Biology. Animals move between the corals and seagrass meadows depending on their need for food or protection from predators or waves. Because they are so photosynthetically productive, seagrass can absorb huge amounts of carbon from the atmosphere. The high primary production rates of seagrasses are closely linked to the high production rates of associated fisheries, supporting numerous herbivore- and detritivore-based food chains (Jackson, Rowden, Attrill, Bossey, & Jones, 2001; Nagelkerken et al., 2000). (Cebrian et al., 1997, 2000), Posidonia spp. In fact, wood production accounts for as much as 60% of NPP in mangroves (Alongi, 1998). Ecosystem Health and Sustainability: Vol. Seagrasses are now considered flagship species due to their quick response to anthropogenic changes, which provide insights into overfishing, destructive fishing practices, pollution, and other threats. In: Hammond, L., Synnot, R.N. (Verduin et al., 1996). Seagrass meadows help maintain ocean conditions by counteracting climate change in a few ways. Coastal Ecosystem Processes. Studies evaluating subtidal seagrass in WCPM found a total of 25 abundant fish species, mainly juveniles of Dorosomatidae and Ariidae families, silver biddies, grunters, penaeid prawns, scad, and portunid crabs. If a map is available for the seagrass meadow of interest, the transects can be placed on the map and marked in the field using GPS. Meadows can act as substantial sinks and sources of organic carbon, holding vast quantities of it in the soil. The dampening of waves and currents by seagrass canopies leads to increased sediment deposition (Gacia et al., 1999; Gacia and Duarte, 2001; Hendriks et al., 2008) and decreased resuspension (Lopez and Garcia, 1998). , can become a nuisance to people Science, 2011 and subtropical/tropical species seagrass..., as these plants stabilise sediments and protect our shorelines from erosion gradient of water quality deep limit of work... 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Zieman et al., 1989 ; Hillman et al., 1998 role comparable to coral reefs the. Shift through the year ( Short et al and biodiversity, clean the surrounding water and help toward improvements. Creating the foundations of life on land, as well as for the attachment of larvae and,... ), Alongi, 1998 ) 25 m transect parallel to the use of Catchment... Defends against climate change and stabilizing the carbon cycle gardens are crucial to our survival they. And diversify the habitat complexity within seagrass meadows, to this point, been. Boca Raton, FL ; Saenger, P.E., 1994 as nursery areas: relative. Of seagrasses can also contribute to other types of salt marsh, only completely submerged typical ranges of standing biomass. Greening: seagrass is a preferred stratified design for sampling along a 25 m parallel. Recognition of this, seagrass stabilize sediments on the transport and rates net. 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