The study also showed that individual transplants presented rapid lateral expansion, and that transplant plots in Oyster Harbour closely resembled established P. australis meadows within 5 years (Bastyan and Cambridge, 2008), with shoot densities similar to those previously reported. These categories were determined for the northern GBR, and are likely to apply across the wider Coral Sea region. A review of the direct and indirect effects of fishing activities on the seagrasses of the Atlantic coast of the USA is given in Blaber et al. (Brewer et al., 1995). Seagrass beds are important habitats in temperate and tropical coastal and estuarine areas. Seagrass made up >15% of the IRI in six of seven life stage-area classes, >30% of the IRI in four of the seven classes, and reached a maximum of 62% of the IRI in young-of-the-year bonnethead sharks from northwestern Florida (Bethea et al., 2007). Although we did not measure the flowing out amount of the eelgrass in this study, we observed that only a small amount of eelgrass was deposited inside the bay and that most of it went offshore. From: World Seas: an Environmental Evaluation (Second Edition), 2019, Friedhelm Gltenboth, Peter Widmann, in Ecology of Insular Southeast Asia, 2006. The first particles to settle are the coarser/heavier ones (usually inorganic) followed by finer (inorganic) and lighter (organic) particles. Water Quality:Seagrasses help trap fine sediments and particles that are suspended in the water column, which increases water clarity. A recent estimate of net primary production for seagrasses ranges between 349 and 449gCm2year1 similar to macroalgae communities and lower ranges of salt marshes and mangroves (Duarte, 2017). The mudflats declined by 20% from 1969 to 2006, and the seagrass beds declined by 72% from 1960 to 1990 (Ministry of the Environment Government of Japan, n.d.-b). Ecosystem support:Seagrasses provide food, shelter, and essential nursery areas to commercial and recreational fishery species and to countless invertebrates living in seagrass communities. (Fam. Several species of true apex predatory elasmobranchs, including bull sharks, great hammerheads, and tiger sharks, frequent seagrass habitats. SIS Sawara are important culturally and religiously, as well as economically (about 7% of the oysters in terms of market value) for the SIS Satoumi. Common for both chamber and covariance techniques are large diurnal and seasonal variations in net ecosystem metabolism showing autotrophy during the summer and heterotrophy during winter (Barrn etal., 2006; Apostolaki etal., 2010; Long etal., 2015b). (2002) distinguished four broad categories of seagrass habitat: river estuaries, coastal, deep water, and reef, whereby seagrasses were variously controlled by terrigenous runoff, physical disturbance, low light, and low nutrients, respectively. Bottlenose dolphins are often found feeding on organisms that live in seagrass areas. Paul LA. Dictyotaceae), Starfish Archaster typicus (Fam. Sediment deposition within seagrass beds occurs as a result of the reduction in current velocity and wave energy by the vegetation (Fonseca et al. Areas of various seagrass and seaweed beds in Seto Inland Sea. Fig. Nitrogen balance in the eelgrass beds. Because cownose rays cause the crash of bay scallop populations prior to the scallop spawning season, predation by cownose rays may have substantial impacts on scallop recruitment and population sizes (Myers et al., 2007). A seagrass bed expert, long involved in the ecological systems in the region, said a threshold area exists under which seagrass beds cannot sustain and recover on their own (personal communication with an expert, Takehiro Tanaka, 2015). The plan limits a population threshold (Blimit) below which a restoration plan is implemented (Fisheries Agency of Japan and Fisheries Research Agency, 2014). Blaber, in Treatise on Estuarine and Coastal Science, 2011. The SIS Sawara has a regional population with habitat inside and near the SIS (Uehara and Mineo, 2016), making them relatively immobile and a good ICZM target. In Hinase, junior high school students participated in a seagrass bed restoration project, in which students who had not had contact with the sea nurtured their connection to the area (Hinase Junior High School and Network for Coexistence with Nature, 2016). The main objective of the study was to assess the feasibility of transplanting P. australis in areas once vegetated by seagrasses, after improving the conditions that caused seagrass loss (eutrophication, sediment and nutrient loads, and turbidity). The production of Z.marina has been measured as far north as at 633565N, where it was about 62.5mmolCm2d1, only slightly lower compared with lower latitudes (Duarte, 2002). When it rained, it was observed that the salinity decreased and DIN concentration increased rapidly. M.B. 2015a, 2015b). com.) In spite of an estimated cover of only<2% of the ocean surface, seagrass beds contribute significantly to the oceanic carbon cycle because of their locally high productivity. Seagrass beds are mainly found in shallow bays and estuaries being especially susceptible to human activities (Reed and Hovel, 2006), but, jointly with their benthic habitat, have been compromised worldwide as a result of fishing (Turner et al., 1999), trampling (harvesting in the intertidal area) (Skilleter et al., 2006), dredging (Erftemeijer and Lewis, 2006), and aquaculture practices (Delgado et al., 1999; Pergent-Martini et al., 2006). We know the DIN concentration in the pore water, but we cannot estimate the DIN contribution from the root, because the DIN uptake rate from the root is unknown. 620 S. Meridian St. Tallahassee, FL (850) 488-4676 Particulate carbon intake by suspension feeders such as Cerastoderma edule and M. balthica is too low to compensate for particle loss due to currents. Vertical markers like poles (Harlin and Thorne-Miller 1982, Kirkman and Kuo 1990) or pins of the sediment-erosion table (SET) developed for marshes by Boumans and Day (1993) and tested in seagrasses by Short (pers. After that, it stops growing, most of the algal bodies are dead and settled or flow out as floating seaweed. 3.13. As already described for dense seagrass beds, productivity is the main regulator to sustain the living biomass within the system. Educational benefits categorized in cultural services are a crucial component for realizing Satoumi. Sparse seagrass beds are sources of carbon. Potamogetonaceae), Nodular Starfish Protoreaster nodosus (Fam. Oreasteridae), Mermaid's Fan Padina sp. Copyright 2022 Elsevier B.V. or its licensors or contributors. 3.11. Growth rates were also reduced compared to the area without such disturbance. In this bay, the biomass of eelgrass reached the maximum (364gdwm2), decreasing when most of the eelgrass is depleted from summer to fall, and increasing biomass the next April. They have been destroyed because of coastal development during the high-growth period of the Japanese economy. (1994) found that southern stingrays were unable to create unvegetated patches within a turtlegrass Thalassia testudinum bed and only southern stingrays with disk widths>0.9m damaged turtlegrass rhizomes at the turtlegrasssand interface. Princess Royal Harbour area, although nearby, presented lower survival rates, with the authors pointing out that bioturbation and currents had some impact on survival with the former being tolerated better (7689% survival) and the latter being a major limitation to successful transplantation (14% survival). In general, the density and assemblage structure of seagrasses in this region vary according to their habitat. Cownose rays have been implicated in the fragmentation of large seagrass beds in Chesapeake Bay (Hovel and Lipcius, 2001) and, in an extreme case, were responsible for the destruction of approximately 90ha of seagrass beds in Chesapeake Bay and the loss of 1530cm of sediment over the following years (Orth, 1975). In the tropics, damage to seagrass beds from fishing activities is reported from Cuba (Quiros-Espinosa et al., 2005), the Philippines (Ferrari et al., 2008), and Indonesia (Nuraini et al., 2007) with negative flow on effects to fisheries productivity. Additionally, DIN release from the bottom sediment to the water column of the bay was estimated as 7mgm2day1 by a core incubation experiment. Ikushima Bay is small bay of 42ha, and almost all the bay is covered by a seagrass bed from spring to summer (Fig.3.9). Although nonteleost species may be of relatively minor importance to the diets of most of the shark species within seagrass and mangrove habitats, the elasmobranch community may have a large impact on some prey types, as was observed in Groote Eylandt, Australia, where six carcharhinids (spottail shark, milk shark, Australian sharpnose shark Rhizoprionodon taylori, nervous shark, whitecheek shark Carcharhinus dussumieri, and grey reef shark) joined together accounted for over one-third of the combined impact of all predators on tiger prawns Penaeus spp. (2006) stated that 2400ha of seagrass beds in China are being damaged by trawling, pollution, dredging of shipping channels, and development of shallow-water aquaculture facilities; in southeast Australia, Posidonia and Zostera beds are threatened by the introduction of an invasive green alga, Caulerpa taxifolia, which competitively replaces seagrasses and may then change fish community structure (York et al., 2006); and, in southern New England, the loss of Zostera has severely impacted estuarine fish communities (Hughes et al., 2002). Most of the seagrass beds were located in the central part of the sea, with the largest portion being the area of eelgrass bed (Fig. Fishermen have carefully protected the eelgrass as a fish habitat for a long time. Exclosure experiments in multiple systems will help to elucidate the possible mechanisms of tiger shark-induced cascades. The extensive root system (see diagram below) in seagrasses, which extends both vertically and horizontally, helps stabilize the sea bottom in a manner similar to the way land grasses prevent soil erosion. Additionally, it was shown that leaves and roots are equally important in nutrient acquisition based on a numerical model (Zimmerman et al., 1987). Squillidae), Round tipped seagrass Cymodocea rotundata (Fam. 1994, Bloesch 1996). Seagrass beds (predominately Thalassia testudinum) are some of the most extensive in the Caribbean, if not the world (Ryan & Zapata, 2003). Instead, a food chain depending almost completely on detritus has developed in seagrass beds. In Seto Inland Sea, it reproduces from the winter to spring, and the biomass reaches the maximum at early summer. Aerobic respiration increases pools of CO2 and may also decrease pH, which in carbonate sediments may result in significant carbonate dissolution (Hu and Burdige, 2007; Burdige etal., 2010). The permanent loss of assimilated carbon is reflected in the sediment becoming more and more sandy. Several authors suggest that environmental factors, e.g., increased nutrients and reduced lights, will have stronger negative impact compared with the benefits of increased CO2 in a future climatic setting based on laboratory experiments (P.oceanica Hendriks etal., 2015; Cymodocea nodosa de los Santos et al., 2017). Their light requirements, however, are higher because seagrass tissues support a larger fraction of respiratory organs (rhizomes and roots) (Borum etal., 2006). For example, juvenile rock fish and red seabream live there and bigfin reef squid lay eggs in the eelgrass bed. The 210Pb method uses stable Pb as a geochemical tracer in sediment cores. Food:While some organisms, including the endangered Florida manatee and green sea turtle, graze directly on seagrass leaves, others use seagrasses indirectly to provide nutrients. Economics:Although seagrass is not a commodity that is directly cultivated in Florida, its economic value can be measured through other industries, such as commercial and recreational fisheries and nature and wildlife tourism, which rely on this habitat to survive. While foraging, batoids may disturb and uproot submerged vegetation, such as seagrasses (Orth, 1975; Valentine et al., 1994). From 1987 to 1998, the population declined by 95%, but recovered to 30% of the 1987 level as of 2013, following the implementation of a resource management plan (Fig. A similar cascade appears to have occurred in Bermuda (Heithaus et al., 2008b). Sea horse Hippocampus sp. Evidence from seagrass beds in the southeastern United States suggests that for some prey species the predatory impacts of elasmobranchs may be severe. Recently new methodologies have documented the dynamics of pH in rhizosphere sediments of Zostera marina and Zostera muelleri, where the pH is typically higher compared with bulk sediment (Koren etal., 2015; Brodersen etal., 2016), affecting the biogeochemistry of sediments on short timescales and further studies are recommended for seagrasses growing in carbonate sediments. It can give present and past sedimentation rates but the sample analysis is labor intensive and requires a flame atomic absorption spectrometer (Benoy and Kalff 1999). A vital part of the marine ecosystem due to their productivity level, seagrasses provide food, habitat, and nursery areas for numerous vertebrate and invertebrate species. As just described, our results demonstrated that the DIN supply (1559mgNm2day1) from the DIN inflow into the bay by the tidal current and DIN release from the bottom sediment were only 10% to 40% of the DIN demand (160mgNm2day1) of the eelgrass during its growth period. 1984). (1995) for Halophila ovalis in an estuary in Western Australia. Erftemeijer, Evamaria W. Koch, in Global Seagrass Research Methods, 2001. Eelgrass is a flowering plant, and the length of its leaf is generally 60 to 100cm. Furthermore, seagrasses are generally considered to be carbon limited because of the low availability of CO2 at seawater pH (Larkum etal., 2006b). Although we do not directly eat it as brown seaweed, the eelgrass bed is a habitat for many organisms. Data was from Nature Conservation Bureau, Environment Agency and Marine Parks Center of Japan, 1994 and was modified. 2014a, 2014b; Long etal. 3.1). Some scientists, however, view seagrass areas more as a part of the reef-associated communities rather than a separate ecosystem due to the great variation in areal dimension (Shepphard et al., 1992). 1984, Almasi et al. S.J.M. The seaweed communities of eelgrass (Zostera marina) grow in shallow water areas with calm waves 5 to 10m under the low-tide line with a sand and mud bottom. These involve the mechanical damage inflicted by fishing gear such as trawls, dredges, and rakes used for catching fish, removing oysters, and collecting clams. (2000). Sawara is a management target because its population has declined rapidly. Copyright 1999 - 2022 State of Florida. In fragmented seagrass beds, the number of fish species and the density of juveniles are lower, and cryptic species are correlated to canopy height (Jackson et al., 2006). Nurturing a connection with an area is crucial in the long term where decline in the number of the residents is severe. Our results suggest that the eelgrass can uptake efficiently the DIN that supplies the bay water intermittently and can accumulate nitrogen in its tissues. The most common species in the Coral Sea region are Cymodocea serrulata, Thalassia hemprichii, Halodule uninervis and Halophila ovalis (Irving, Jackson, & Hendry, 2016; Van Wynsberge, Gilbert, Guillemot, Payri, & Andrefouet, 2013). During the eelgrass growth period, its nitrogen demand is extremely large (160mgNm2day1), and its biomass is also large (364gNm2), making it the nitrogen stock in the bay. The authors have been conducting observations in the eelgrass bed at Ikushima Bay adjacent the Bisan-Seto, central part of Seto Inland Sea. Seagrass leaves provide a place of anchor for seaweeds and for filter-feeding animals like bryozoans, sponges, and forams. Extensive literature exists describing and commenting on the methods used in seagrass restoration (Fonseca et al., 1998; Calumpong and Fonseca, 2001; Seddon, 2004; Larkum et al., 2006). While terrestrial grasslands abound with grazing animals, remarkably few specialized herbivores directly feed on the living biomass of seagrasses. Recent studies simulating higher CO2 in the atmosphere show variable response reflecting complex interactions between environmental factors and seagrass productivity and that it is far from likely that seagrasses will benefit from ocean acidification (Apostolaki etal., 2014; Ow etal. The main carbon export is via organism drift. For all of these reasons, the eelgrass contributes greatly to the nitrogen cycle of the coastal water. In this section, we will focus on nitrogen inflow and outflow in the eelgrass bed in Ikushima Bay. Most eelgrass is distributed in the temperate and tropical regions, and it reproduces in two ways: by seed and by a horizontal expansion of the root in the sand mud bottom to establish a new leaf sheath. Seagrass beds and mangrove habitats are used by a wide variety of elasmobranchs and individuals of many species are likely to move between these often-neighboring habitat types. Eelgrass can uptake nutrients from both the leaf sheath and root. Potamogestonaceae), H. Asmus, R. Asmus, in Treatise on Estuarine and Coastal Science, 2011. 2014a, 2014b; Long etal. Heithaus, in Treatise on Estuarine and Coastal Science, 2011. Organisms show a net export of carbon from the sparse and dense seagrass beds. Superficially, seagrass beds resemble mixed or monospecific meadows, but their only common feature with terrestrial meadows is their high primary productivity. In temperate regions, Tudela (2004) reported that Posidonia beds in the Mediterranean have been dramatically impacted by trawling; Huang et al. Fig. Sparse seagrass bed generally acts as a source for POC. The studies available from subtropical and tropical seagrasses show that the belowground production (3.6130gDWm2year1) can account for half of the aboveground production (9.52323gDWm2year1, Duarte etal., 1998). 2015a, 2015b, Barrn etal., 2006; Apostolaki etal., 2010; Long etal., 2015b, Apostolaki etal., 2014; Ow etal. Further decomposition releases nutrients (such as nitrogen and phosphorus), which, when dissolved in water, are re-absorbed by seagrasses and phytoplankton.Nursery areas:The relative safety of seagrass meadows provides an ideal environment for juvenile fish and invertebrates to conceal themselves from predators. Differences in nutrient availability between the water column and sediments may stimulate relative growth of leaves versus roots, respectively, as reported by Hillman etal. ScienceDirect is a registered trademark of Elsevier B.V. ScienceDirect is a registered trademark of Elsevier B.V. World Seas: an Environmental Evaluation (Second Edition), Estuarine and Coastal Ecosystem Modelling, Treatise on Estuarine and Coastal Science, Van Wynsberge, Gilbert, Guillemot, Payri, & Andrefouet, 2013, Sediment geology methods for seagrass habitat, Trophic Relationships of Coastal and Estuarine Ecosystems, Feldheim et al., 2002; White and Potter, 2004; DeAngelis et al., 2008; Powter and Gladstone, 2009, Brewer et al., 1995; White et al., 2004; Newman et al., 2010, Brewer et al., 1995; White et al., 2004; Taylor and Bennett, 2008, Corts and Gruber, 1990; Brewer et al., 1995; White et al., 2004; Collins et al., 2007, Knowles and Bell, 1998; Travers and Potter, 2002, Heithaus et al., 2008a, 2008b; Wirsing et al., 2008, Heithaus and Dill, 2002, 2006; Heithaus, 2005; Heithaus et al., 2007b, 2009b; Wirsing et al., 2007a, 2007b, 2008; Kerford et al., 2008; Wirsing and Heithaus, 2009, Delgado et al., 1999; Pergent-Martini et al., 2006, Reed and Hovel, 2006; Skilleter et al., 2006, Fonseca et al., 1998; Calumpong and Fonseca, 2001; Seddon, 2004; Larkum et al., 2006, Productivity and Biogeochemical Cycling in Seagrass Ecosystems, Hauxwell etal., 2001; Kopecky and Dunton, 2006, Holmer etal., 2009a; Drouin etal., 2016, Barrn etal., 2006; Castorani etal., 2015, Rheuban etal. Because Sawara is cooked for both hare (special days for religious and cultural events) and ke (average days), it is both sacred and soul food (Innami, 2015). Estimated population and catch of Seto Inland Sea Sawara (Setonaikai Fisheries Coordination Office, 2012). The antipredator responses of large grazers to tiger sharks in this system may impact seagrass communities (see Heithaus et al., 2008, 2010); the spatial pattern of seagrass leaf nutrient composition is consistent with shifts in the spatial pattern of herbivory induced by tiger shark predation risk (Heithaus et al., 2007b). Sedimentation/erosion rates can also be calculated via 210Pb dating. Many of the seagrass beds are in sheltered lagoons, especially throughout the Solomon Islands and New Caledonia, which have well-developed lagoonal systems where seagrasses occur in close proximity to reefs and mangroves (Irving et al., 2016; Olds et al., 2013). Seagrasses also work to filter nutrients that come from land-based industrial discharge and stormwater runoff before these nutrients are washed out to sea and to other sensitive habitats such as coral reefs. At that time, the nitrogen content of the leaf sheath doubled, from 16.3mgNg1 to 35.1mgNg1 over 6 days, and the C/N ratio decreased from 22.6 to 14.2. Fig. By continuing you agree to the use of cookies. Similarly, total seagrass ecosystem metabolism of seagrass beds is measured insitu by using benthic chambers or eddy covariance techniques. We think there are a number of nitrogen absorption mechanisms. 3.12. A more recent study examining bonnethead shark diets across the gulf coast of Florida found that seagrass might even be a more important item in stomach contents. The productivity and structural complexity of the habitat, however, allow for a wide breadth of abundant prey species and, as a result, other prey types, especially crustaceans and cephalopods, are also commonly found in the stomachs of sharks within these systems (e.g., Brewer et al., 1995; White et al., 2004; Taylor and Bennett, 2008), and some species even specialize in nonteleost prey, such as the bonnethead shark, which feeds almost exclusively on crustaceans (Corts et al., 1996; Bethea et al., 2007), and the Australian weasel shark, which specializes on cephalopods (Taylor and Bennett, 2008). 3.11; Nature Conservation Bureau, Environment Agency and Marine Parks Center of Japan, 1994). The ecological importance of seagrass meadows for coastal areas led to the development of several restoration initiatives worldwide. In comparison with macroalgae, seagrasses take advantage of their ability to acquire nutrients from the sediments and the water column. This resemblence ends when we look at the herbivores. Because of the large size variation in seagrasses, production (gDWm2d1) varies by a factor of 500 between the least (Halophila ovalis; 0.01g dry weight (DW)m2d1) and the most productive species (Phyllospadix torreyi; 11.3gDWm2d1) (Duarte and Chiscano, 1999). can also be used to quantify sedimentation processes within seagrass beds. The impacts caused by these predators, however, may vary with location. This review concluded that there is ample evidence that the removal and alteration of these habitats have major impacts on the ability of such areas to act as nursery grounds for juvenile fish and other invertebrates. Light is the most important controlling parameter of seagrass productivity (Zimmerman, 2006), whereas nutrients are most important for tropical seagrasses growing under oligotrophic conditions (Romero etal., 2006). The importance of seagrass and mangroves as nursery grounds may be shown in the decreasing juvenile survival rate of lemon sharks in the North Sound of Bimini, Bahamas, that corresponds to losses of mangrove and seagrass habitats due to coastal development (Jennings et al., 2008). There are many different types of epiphytes from small calcareous algae to large thread-like macroalgae. Seagrass is frequently found in the stomachs of sharks foraging in seagrass beds, but it usually makes up a very small proportion of the mass or volume of stomach contents and likely is consumed incidentally (Corts and Gruber, 1990; Brewer et al., 1995; White et al., 2004; Collins et al., 2007). Corts et al. Seagrass beds are also potentially crucial in terms of thresholds. The impacts of foraging cownose schools, however, are not limited to their prey. Marianne Holmer, in Coastal Wetlands (Second Edition), 2019. Strong risk effects of tiger sharks on several of their prey species have been observed in Shark Bay, Western Australia and these risk effects, combined with direct predation, could influence equilibrium population sizes (see Heithaus et al., 2008a, 2008b; Wirsing et al., 2008 for summaries). It is important to note that the success of the transplantation trials in Oyster Harbour increased the general interest in restoring seagrass meadows, with Bastyan and Cambridge (2008) stating that local communities have participated in transplanting initiatives (several hectares, large scale) in areas where natural recovery by seedling recruitment and patch expansion has been poor. By altering these habitats, which provide habitation to many species (e.g., Knowles and Bell, 1998; Travers and Potter, 2002), batoids can be an important indirect influence on the distribution and abundance of seagrass-associated species (e.g., Hovel and Lipcius, 2001). Pursuant to section 120.74, Florida Statutes, the Fish and Wildlife Conservation Commission has published its2019 Agency Regulatory Plan.
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