Presence Of Seagrass Research Articles

Seagrass diversity and dugong observation in North Minahasa Regency, North Sulawesi

Dugong is a marine mammal that only eats seagrass. Feeding tracks of dugongs in the seagrass beds indicate their presence. The dugong population is currently experiencing a decline due to habitat destruction and other anthropogenic factors. This study aimed to determine the seagrass diversity and their relationship to the presence of dugongs. The research was conducted in villages of Bahoi, Tarabitan, Bulutui, and Gangga I Island using the seagrass-watch method. Analysis of the data used was the percentage of seagrass cover, density of seagrass species, and indicators of the presence of seagrass, which was carried out by interviewing fishermen and surveying their feeding tracks. The results showed that the waters in the North Minahasa Regency had seven seagrass types. The average percentage of seagrass cover was 61.73% and the density of seagrass species was 766.88 shoots/m2. Feeding tracks observed in three locations, in Bahoi, Tarabitan, and Bulutui villages. The most tracks of feeding tracks were in Bahoi Village, with the type of seagrass that dominated being eaten by dugongs was Halodule pinifolia. Based on the results obtained, it concluded that certain types of seagrass are related to the location of the emergence of dugongs in the North Minahasa Regency.

Assessing the coastal protection role of seagrass meadows along a barrier beach, southern Romanian coast

The presence of seagrass along the Romanian coast is currently seen as an important component of the marine ecosystem. Moreover, seagrass meadows play an additional wave energy dissipation role that has also to be considered among other ecosystem services. Assessing the impact of a seagrass meadow on the local hydrodynamics is needed to present an integrated protection and adaption plan for discussion with local stakeholders and coastal managers. The impact on wave heights of a possible seagrass meadow, located in front of the barrier beach at the Mangalia marsh on the southern Romanian coast, has been analysed using numerical modelling. Several seagrass configurations have been studied, for low and average wave conditions from various directions. The same waves were used after adding a vegetation mask to the analysed domain, to simulate the presence of a seagrass meadow. The results of the numerical simulations were extracted in several output points, located along three transects crossing the vegetation mask. They show the most significant reduction in the calculated wave energy density during a year of 16.6%, occurring within the seagrass meadow. Our results suggest that, for the southern Romanian coast, seagrass could be introduced in coastal protection plans as an additional measure for wave attenuation.

Two temperate seagrass meadows are negligible sources of methane and nitrous oxide

AbstractSeagrasses are globally important ecosystems that can help mitigate climate change by sequestering carbon (C). The net impact seagrass meadows have on the climate, however, also depends on methane (CH4) and nitrous oxide (N2O) fluxes. By not accounting for CH4 and N2O fluxes, we may be overestimating or underestimating the true C sequestration capacity of seagrasses. Yet, few observations of seagrass CH4 and N2O fluxes are available. Here, we quantified summer, dark/light CH4 and N2O fluxes across the sediment–water interface from seagrass meadows (Zostera marina) and adjacent nonvegetated sediments in two temperate bays with different environmental characteristics. On two occasions, we also estimated system wide air‐sea CH4 and N2O fluxes. We found the CH4 fluxes across the sediment–water interface varied between the two sites with one site emitting CH4 from vegetated sediments and a net zero flux at the other site. N2O fluxes across the sediment–water interface were not different from zero regardless of seagrass presence, although when we did measure a flux, there was more often a net uptake of N2O. We estimated that both systems were small net sources of CH4 and N2O to the atmosphere; however, the sediments are not likely the source of CH4 and N2O emitted to the atmosphere in the systems. Although the diffusive fluxes measured here are lower than those reported in the literature, they are consistent with our current understanding of seagrass sediments being variable sources of CH4 and potentially a negligible source or sink of N2O.

Habitat suitability of drift macroalgae in two shallow coastal estuaries of the northern Gulf of Mexico

Drift macroalgae, often associated with seagrass habitats, may provide resources and habitat to seagrass associated fauna, increasing faunal abundance and diversity. Yet, excessive amounts of drift macroalgae can be harmful, reducing the abundance of both aquatic angiosperms and animals by causing localized hypoxia. To ascertain the effects of drift macroalgae at biomasses commonly found in the northern Gulf of Mexico, we quantified recruitment into drift macroalgae without the presence of seagrass and measured associated changes to temperature, dissolved oxygen, and flow in Redfish Bay, Texas and Big Lagoon, Florida, USA. These locations comprise different coastal ecosystems with different compositions of drift macroalgae. In both locations, the presence of macroalgae significantly increased recruitment of small nekton, with higher abundances and species richness found within macroalgae relative to adjacent artificial macroalgae. Flow velocity and dissolved oxygen levels were lower in macroalgae than in adjacent artificial or bare substrate, but still remained above hypoxic levels over daily fluctuations. Despite lower oxygen levels at night, and overall lower water flow, organisms readily recruited into drift macroalgae more so than the artificial habitats nearby. However, the reduction in oxygen reveals that in higher biomasses, macroalgae could adversely affect animals.

Compositional stability of sediment microbial communities during a seagrass meadow decline

The presence of seagrass shapes surface sediments and forms a specific environment for diverse and abundant microbial communities. A severe decline of Cymodocea nodosa, a widespread seagrass species in the Mediterranean Sea, has been documented. To characterise and assess the changes in microbial community composition during the decline of a Cymodocea nodosa meadow, Illumina MiSeq sequencing of the V4 region of the 16S rRNA gene was performed. Samples of surface sediments from two sites, one without any vegetation and one with a declining Cymodocea nodosa meadow, were collected at monthly intervals from July 2017 to October 2018. Microbial communities were stratified by sediment depth and differed between the vegetated and the nonvegetated site. Although the Cymodocea nodosa meadow declined to a point where almost no leaves were present, no clear temporal succession in the community was observed. Taxonomic analysis revealed a dominance of bacterial over archaeal sequences, with most archaeal reads classified as Nanoarchaeota, Thermoplasmatota, Crenarchaeota, and Asgardarchaeota. The bacterial community was mainly composed of Desulfobacterota, Gammaproteobacteria, Bacteroidota, Chloroflexi, Planctomycetota, and Campylobacterota. Our results show that sediment microbial communities are remarkably stable and may resist major disturbances such as seagrass meadow decline.

Fine-scale foraging segregation in a green turtle (Chelonia mydas) feeding ground in the Bijagós archipelago, Guinea Bissau

Green turtles (Chelonia mydas) are highly dependent on neritic foraging areas throughout much of their life. Still, knowledge of recruitment dynamics, foraging habits, and habitat use in these areas is limited. Here, we evaluated how the distribution and food preferences of green sea turtles from different life stages varied within a foraging aggregation. We focused on two islands in Guinea-Bissau, Unhocomo and Unhocomozinho, using water captures and survey dives to record habitat use and characteristics, and stable isotopes to infer diet. Additionally, we used stable isotopes to infer their diet. Two habitat types were sampled: deeper (2.26 ± 0.4 m) rocky sites fringed by mangrove with macroalgae, and sandy shallows (1.37 ± 0.12 m) surrounded by rocky reefs with macroalgae and seagrass. The two benthic communities were similar isotopically and in terms of species composition, except for the presence or absence of seagrass, which had unique signatures. We captured 89 turtles ranging from 35 cm to 97 cm in curved carapace length (i.e., juvenile to adult stages). Size distribution was habitat-dependent, with most smaller turtles present in sandy shallows and larger turtles favoring slightly deeper rocky sites. Turtle isotopic signatures differed between the habitat of capture, regardless of size, revealing a marked dichotomy in foraging preference. All turtles fed primarily on macroalgae, mostly rhodophytes. However, individuals captured in sandy habitats had evident seagrass skewed isotopic signatures. Larger turtles may be unable to use the more diverse shallower foraging sites due to increased vulnerability to predation. Despite the proximity of the sampled foraging sites (2.7 km apart), the two foraging subgroups seem to maintain consistently different feeding habits. Our study highlights how heterogeneous green turtle foraging habits can be within populations, even at small geographic scales.

Biodiversity differentials between seagrass and adjacent bare sediment change along an estuarine gradient

Differentials between the invertebrate biodiversity of seagrass (S) and of adjacent bare sediment (B) were investigated at 8 localities spaced along the axial gradient of an estuarine system, that at Knysna in South Africa; various assemblage metrics being compared at paired S/B stations. Little or no S:B differentials were found near the mouth, but significant increase in those between both levels of overall assemblage abundance and of taxon richness did occur upstream (in abundance from <1 near the mouth to >2 towards the head, and in taxon richness from 1 to 2). The habitat supporting greater abundance therefore switched along the gradient. The differential between numbers of co-dominant species in the assemblages also increased upstream, whereas that between levels of taxonomic distinctness decreased. Functional diversity, evenness and patchiness differentials, however, showed no significant upstream change; neither did values of Bray-Curtis similarity between the two habitat types. Most affected were the epibenthic- and subsurface-feeding assemblage components. As predicted, macrobenthic assemblages of seagrass and bare sediment reacted differently to the gradient, and seagrass enhanced macrobenthic biodiversity much more upstream. However, location along the estuarine gradient appeared an equally important influence on assemblage composition to presence or absence of seagrass. The evident context-dependent nature of such differentials urges considerable caution in the extrapolation of ecological indicators derived from local areas to wider regions.

Non-native red alga Gracilaria vermiculophylla compensates for seagrass loss as blue crab nursery habitat in the emerging Chesapeake Bay ecosystem.

Non-native species can become deleterious or potentially beneficial as components of novel ecosystems. The non-native red macroalga Gracilaria vermiculophylla may provide nursery habitat where eelgrass Zostera marina has been extirpated in Chesapeake Bay. A mensurative experiment was conducted monthly May–October 2013 and 2014 in the York River, Chesapeake Bay, to evaluate hypotheses that Gracilaria (1) can compensate for the loss of seagrass nurseries by colonizing habitats where seagrass has been eliminated by environmental stress, and (2) is utilized by juvenile blue crabs (Callinectes sapidus) as nursery habitat. We quantified Gracilaria presence, percent cover, and biomass as a function of region (upriver, midriver, and downriver) and seagrass presence or absence using stratified random sampling, 20-m transects, and 0.0625-m2 quadrats. Gracilaria volume was measured and converted to dry weight. Effects of the factors and covariates temperature, salinity, dissolved oxygen, month, and year were analyzed using generalized linear models. Juvenile blue crab density was quantified in summer 2013 using suction sampling in Gracilaria and seagrass. A model with the collective effect of region and seagrass presence or absence (downriver seagrass, downriver unvegetated bottom, midriver unvegetated bottom) best predicted Gracilaria abundance. Gracilaria presence, percent cover, and biomass were highest in downriver seagrass, followed by downriver unvegetated bottom, and then midriver unvegetated bottom, where seagrass has been extirpated, supporting hypothesis (1). Gracilaria did not occur upriver, likely due to a lack of recruitment. Seagrass and Gracilaria housed similar densities of juvenile blue crabs, supporting hypothesis (2). We estimated that a single 40-ha cove system with Gracilaria could house 200,000 juvenile crabs as would a single 2.4-ha seagrass bed. Consequently, the numerous midriver and downriver cove systems in the York River could support millions of young juvenile blue crabs and thereby compensate for the loss of seagrass in the river and in other areas of Chesapeake Bay. At present, Gracilaria has no widespread negative impacts on seagrass in the York River or most regions of Chesapeake Bay, likely because percent cover and biomass are not excessively high at present. We posit that Gracilaria has become an important alternative nursery habitat for the blue crab in Chesapeake Bay and can potentially mitigate impacts of climate change on seagrass nursery habitats.

Conservation planning implications of modeling seagrass habitats with sparse absence data: a balanced random forest approach

This paper presents a species distribution model (SDM) to quantify relationships between environmental variables and habitat suitability using unbalanced presence-absence data common in ecology. The proposed model applies a stratified sample balancing scheme for the random forest classifier where every classification tree receives a balanced sample of presence and absence. The model is applied to the Australian coast's seagrass habitats, where seagrass populations have been on the decline. Australian Centre for Ecological Analysis and Synthesis (ACEAS) seagrass presence-absence data is used to train the model. Seagrasses are observed at 97.6% of the survey locations, and seagrass absence is recorded at only 2.4% of the survey locations. The proposed model's accuracy is validated with an independent dataset on seagrass presence from the Coastal and Marine Resources Information System (CAMRIS). The environmental variables used in the analysis are obtained from the Ecological Marine Units (EMU) dataset. The variables on human-driven stressors to seagrass habitats due to ship traffic are obtained from World Port Index. The proposed model predicts seagrass absence at a recall rate of 80%, whereas the random forest recall rate is 24%. The model's variable importance profile aligns with the main drivers behind seagrass habitats reported in the literature. A case study is conducted for quantifying the impacts of two proposed ports in the Gulf of Carpenteria on the local seagrass habitats. Results show that balancing improves the explanatory and predictive capabilities of an SDM to define conditions resulting in a species' absence, aiding conservation planning with realistic species distributions.

Analisis Kelimpahan Dan Indeks Saprobitas Fitoplankton Pada Ekosistem Padang Lamun Di Pantai Sindhu, Sanur, Bali

Abstract&#x0D; Sindhu Beach is one of the beaches in the Sanur area that is used for various economic activities, such as recreational locations or marine tourism by involving many stakeholders that can affect the aquatic environment which is the habitat of marine biota, is phytoplankton. In addition, the presence of seagrass also affects the abundance and saprobity index of phytoplankton. The research was conducted in May 2021 at Sindhu Beach and the identification process was carried out in the laboratory of the Faculty of Agriculture, Warmadewa University. The method used is the descriptive method. There were 20 types of phytoplankton from five classes, namely Chlorophyceae, Diatomae, Bacillariophyceae, Cyanophyceae, and Dinophyceae classes. The highest abundance of phytoplankton in the third observation was 206.369 ind/l at Station 1 and the lowest at the third observation was 152.866 ind/l at Station 2. At Station 1, the lowest water saprobic index was 0.047 in the first observation, followed by the second observation at 0.130, and the highest at the observation third at 0.307. This value is included in the moderately polluted category. At Station 2, the lowest water saprobic index in the first observation was -0.538, followed by the second observation at 0.28 and the highest at the third observation at 0.523. This value is included in the category of lightly polluted. At Station 3, the lowest water saprobic index in the first observation was 0.307, followed by the second observation at 0.615 and the highest at 0.739. This value is included in the category of lightly polluted.&#x0D; &#x0D;

Shallow surface elevation changes in two tropical seagrass meadows

The ability of seagrass meadows to reduce surface erosion and maintain or increase surface elevation is recognised as an important ecological function, which is expected to help protect coastlines. However, much of the evidence supporting this expectation is limited to large, broad leaf, subtidal populations of seagrass from temperate regions. In this study, we examined the capacity of shorter-stature, intertidal seagrasses to influence sediment deposition and shallow surface elevation change compared to unvegetated surfaces at two locations in Singapore. At each location, sediment supply, sediment deposition and surface elevation change were measured over 270 days, a temporal period covering two monsoonal seasons. The levels of these factors were compared among locations and seasons. Overall, surface elevation in vegetated areas increased by 0.40 ± 0.26 cm, while surface elevation in unvegetated areas declined by 0.34 ± 0.31 cm. We also explored the influence of key meadow characteristics on sediment deposition and surface elevation change, and found that surface elevation increased with aboveground biomass, while sediment deposition increased with areal production, leaf turnover rate and belowground biomass. These results suggest that short-term sediment deposition and broader net surface elevation increases moderately in the presence of seagrass compared to unvegetated areas, and highlight the potential of intertidal, short-stature seagrasses such as Cymodocea rotundata to increase surface elevation.

Post-Hurricane Sandy Benthic Habitat Mapping at Fire Island National Seashore, New York, USA, Utilizing the Coastal and Marine Ecological Classification Standard (CMECS)

In 2012, Hurricane Sandy created a new tidal inlet at Fire Island National Seashore (FIIS) in New York, USA, consequently altering environmental conditions within Great South Bay. This event presented a unique opportunity to establish new ecological baselines, assess resulting ecological change, and explore management implications. This study focuses on benthic mapping within the bayside of FIIS using acoustic, grab sample, and imagery data. Biotope (habitat) maps were developed describing relationships between macrofaunal communities and their environment. Additionally, biotopes were prioritized by “ecological value” based on user-defined criteria (presence of seagrass and potential for higher trophic level interactions) to guide management. While there are limited pre-Sandy data for comparison, findings from this study suggest the inlet has been a positive ecological influence on the nearby area. Dense concentrations of mature blue mussels (Mytilus edulis) documented near the inlet are considered ecologically beneficial and represent a post-Sandy distinction in ecosystem structure; M. edulis was last common when the inlet was previously open (early 1800s). The inlet is also likely responsible for seagrass expansion near the inlet but decline in other areas. This study advances the utility of the Coastal and Marine Ecological Classification Standard (CMECS) by including CMECS-defined data in analyses and expanding the definition of “dominance.” CMECS played a key role in developing map units, interpreting biotopes, and establishing statistically significant and ecologically meaningful biotic–abiotic relationships. This study also highlights the value and management applications of benthic mapping specific to FIIS and more broadly and advocates for similar studies elsewhere.

Can seagrass modify the effects of ocean acidification on oysters?

Solutions are being sought to ameliorate the impacts of anthropogenic climate change. Seagrass may be a solution to provide refugia from climate change for marine organisms. This study aimed to determine if the seagrass Zostera muelleri sub spp. capricorni benefits the Sydney rock oyster Saccostrea glomerata, and if these benefits can modify any anticipated negative impacts of ocean acidification. Future and ambient ocean acidification conditions were simulated in 52 L mesocosms at control (381 μatm) and elevated (848 μatm) CO2 with and without Z. muelleri. Oyster growth, physiology and microbiomes of oysters and seagrass were measured. Seagrass was beneficial to oyster growth at ambient pCO2, but did not positively modify the impacts of ocean acidification on oysters at elevated pCO2. Oyster microbiomes were altered by the presence of seagrass but not by elevated pCO2. Our results indicate seagrasses may not be a panacea for the impacts of climate change.

Benthos response to nutrient enrichment and functional consequences in coastal ecosystems

As land use intensifies, many coastal waters are becoming enriched with otherwise limiting nutrients, leading to eutrophication. While the extreme effects of eutrophication on benthic communities are well documented, there is still a lack of knowledge about how nutrient enrichment alters biogeochemical interactions occurring at the sediment-water interface. Using ex-situ experiments, this study explores the consequences of nutrient enrichment on sediment characteristics, macrofauna community and benthic fluxes. The quantity of sedimentary organic matter and porewater concentration of NH4+, NOx and PO43− increased in enriched treatments. These changes did not affect the macrobenthic community structure. However, macroinfauna buried less deep and increased their ventilation activity. As consequences, nutrient efflux increased, thereby favouring eutrophication processes. These effects were reduced in presence of seagrass, thus illustrating the buffering capacity of seagrass in the context of environmental changes, and particularly, of eutrophication. Overall, this study highlights that the functional consequences of nutrient enrichment involve interconnected processes that are variable in space and time.

Seagrass meadows mixed with calcareous algae have higher plant productivity and sedimentary blue carbon storage.

Seagrass meadows capture and store large amounts of carbon in the sediment beneath, thereby serving as efficient sinks of atmospheric CO2. Carbon sequestration levels may however differ greatly among meadows depending on, among other factors, the plant community composition. Tropical seagrass meadows are often intermixed with macroalgae, many of which are calcareous, which may compete with seagrass for nutrients, light, and space. While the photosynthetic CO2 uptake by both seagrasses and calcareous algae may increase the overall calcification in the system (by increasing the calcium carbonate saturation state, Ω), the calcification process of calcareous algae may lead to a release of CO2, thereby affecting both productivity and calcification, and eventually also the meadows’ carbon storage. This study estimated how plant productivity, CaCO3 production, and sediment carbon levels were affected by plant community composition (seagrass and calcareous algae) in a tropical seagrass‐dominated embayment (Zanzibar, Tanzania). Overall, the patterns of variability in productivity differed between the plant types, with net areal biomass productivity being highest in meadows containing both seagrass and calcareous algae. Low and moderate densities of calcareous algae enhanced seagrass biomass growth, while the presence of seagrass reduced the productivity of calcareous algae but increased their CaCO3 content. Sedimentary carbon levels were highest when seagrasses were mixed with low or moderate cover of calcareous algae. The findings show that plant community composition can be an important driver for ecosystem productivity and blue carbon sequestration.

First characterization of seagrasses at Sámara Bay, Pacific coast of Costa Rica

Seagrasses are found at limited locations in the Eastern Tropical Pacific (ETP). Here, we provide the first characterization of seagrasses at Sámara Bay, on the northern Pacific coast of Costa Rica. Sampling was carried out in August 2018 and March 2019. We measured seagrass biomass, shoot density, leaf area, stable isotope composition (δ13C, δ15N), carbon content, bulk density, and grain size. We also measured water clarity, temperature, dissolved oxygen, salinity, and nutrient concentrations. Two seagrass species were found, Halophila baillonii and Halodule beaudettei, which are commonly found in the ETP. Sediment grain size at Sámara was mostly composed of fine and very fine sand. Total seagrass biomass was 31.9 ± 28.7 g DW m−2 and density was 2136 ± 1576 shoots m−2. Halophila bailloni leaf blade length (1.1 ± 0.3 cm) and width (0.5 ± 0.1 cm) were within ranges for the sizes reported for this species, and were similar to other locations. Halodule beaudettei leaf length (5.0 ± 3.8 cm) and width (0.09 ± 0.02 cm), were larger than at other seagrass meadows on the Pacific coast of Costa Rica yet smaller than in Brazil. Seagrass biomass and density at Sámara were higher in the sampling during the dry season, a pattern also found on the Pacific coast of Costa Rica and in Brazil. We recommend further study of seagrasses at this site and the ETP, including temporal and spatial variability and associated environmental factors. Seagrass presence at Sámara should be considered in local management and conservation initiatives.

Geomorphic gradients in shallow seagrass carbon stocks

Seagrass meadows are important sinks of organic carbon (Corg), in particular the near-surface Corg pool (≤ 15 cm) compared to deeper sediments. Near-surface carbon is highly susceptible to disturbance and loss to the atmosphere, however, inadequate accounting for variability in this pool of carbon limits their uptake into carbon accounting frameworks. We therefore investigated the spatial variability in seagrass near-surface Corg and biomass Corg across different geomorphic (estuary, lagoonal and reef-associated) and community typologies (pioneer and persistent). Near-surface Corg stock in vegetated areas (25.78 Mg Corg ha−1 ± 26.64) was twice that from unvegetated areas (14.27 Mg Corg ha−1 ± 15.86), reinforcing the paradigm that the presence of seagrass enhances carbon stocks. Lagoonal and reef-associated meadows showed similar Corg stocks (p > 0.05), which were substantially higher (p < 0.05) than estuary meadows. Likewise, persistent seagrass communities (Cymodocea dominance) stored higher (p < 0.05) stocks of Corg than pioneer communities (Halophila and Halodule dominance). Linear regression models showed significant but weak relationships between seagrass cover, shoot density and standing biomass with near-surface Corg stocks, whereas significant and strong relationships were observed for organic matter, dry bulk density and median grain size. The results highlight the need for higher resolution carbon assessments to better understand local and regional variability, in order to better inform carbon accounting and conservation policy.

Diversity, coverage, distribution and ecosystem services of seagrass in three small islands of northern Papua, Indonesia: Liki Island, Meossu Island and Befondi Island

Nugraha AH, Tasabaramo IA, Hernawan UE, Rahmawati S, Putra RD, Darus RF. 2021. Diversity, coverage, distribution and ecosystem services of seagrass in three small islands of northern Papua, Indonesia: Liki Island, Meossu Island and Befondi Island. Biodiversitas 22: 5544-5549. Papua waters are one of the hot spot areas with high marine biodiversity in the world. Yet, the less accessible location and varying geographical conditions become the significant constraints of biodiversity study in this region, resulting in limited information about the diversity of marine resources, including the seagrass ecosystem. This research aims to investigate the diversity, coverage and distribution of seagrass in three small islands in the northern waters of Papua, namely Liki Island, Befondi Island, and Meossu Island, as well as to study the ecosystem services provided by the seagrass. This research is part of the Nusa Manggala Expedition, which was carried out in November 2018, consisted of seven observation stations. Data collection was conducted using the transect line method combined with plot quadrat. Information regarding seagrass ecosystem services was gathered through observation and direct interviews to the community. The results showed that there were seven species of seagrass in the studied sites, namely Cymodocea rotundata, Enhalus acoroides, Halodule uninervis, Halodule pinifolia, Halophila ovalis, Thalassia hemprichii, and Syringodium isoetifolium. Liki Island had the highest seagrass cover value of 82.24%, followed by Meossu Island and Befondi Island with seagrass cover of 63.23% and 31.25%, respectively. There were 13 seagrass ecosystem services identified in this research. The people of Liki Island and Meossu Island get the benefits of the existence of the seagrass ecosystem. The direct benefits are the presence of seagrass is associated with biota commonly used as food sources such as Siganus sp and sea cucumbers. There are efforts made by the community to maintain the sustainability of the seagrass ecosystem, which is known as sasi.

Using Artificial Seagrass for Promoting Positive Feedback Mechanisms in Seagrass Restoration

Worldwide, seagrass meadows are under threat. Consequently, there is a strong need for seagrass restoration to guarantee the provision of related ecosystem services such as nutrient cycling, carbon sequestration and habitat provision. Seagrass often grows in vast meadows in which the presence of seagrass itself leads to a reduction of hydrodynamic energy. By modifying the environment, seagrass thus serves as foundation species and ecosystem engineer improving habitat quality for itself and other species as well as positively affecting its own fitness. On the downside, this positive feedback mechanism can render natural recovery of vanished and destroyed seagrass meadows impossible. An innovative approach to promote positive feedback mechanisms in seagrass restoration is to create an artificial seagrass (ASG) that mimics the facilitation function of natural seagrass. ASG could provide a window of opportunity with respect to suitable hydrodynamic and light conditions as well as sediment stabilization to allow natural seagrass to re-establish. Here, we give an overview of challenges and open questions for the application of ASG to promote seagrass restoration based on experimental studies and restoration trials and we propose a general approach for the design of an ASG produced from biodegradable materials. Considering positive feedback mechanisms is crucial to support restoration attempts. ASG provides promising benefits when habitat conditions are too harsh for seagrass meadows to re-establish themselves.

Struktur Komunitas Padang Lamun Di Perairan Gili Air, Lombok Utara

Seagrass is a coastal ecosystem that has important role as a feeding ground, a spawning ground and a nursery ground for various marine biota. This study aims to examine the biodiversity of seagrass at Gili Air, North Lombok Regency, West Nusa Tenggara. This study was conducted to observe the cover percentage of seagrass, it's composition, the number of seagrass stands, canopy's height, frequency of seagrass presence, and index of importance of seagrass. Seagrass data was collected using a 50cm x 50cm quadrant transect, with a total area of 100 m2, referring to the monitoring standards set by SeagrassNet. Water quality analysis was carried out at the Bioecology Laboratory of the Aquaculture Study Program, University of Mataram, and at the Laboratory of the Marine Aquaculture Center (BPBL) of Sekotong, West Lombok. The results showed that the seagrass communities in Gili Air waters were composed of 5 (five) species: Halophila ovalis, Thalassia hemperichii, Cymodocea rotundata, Halodulea pinifolia, and Halodule uninervis, with the percentage of coverage ranging from 26.88-39.17%, and the average coverage by 31.53%. Thalassia hemperichii is the species that has the highest contribution to the seagrass community at Gili Air.