Seagrass Condition Research Articles

The role of environment descriptors and seagrass biometrics in shaping macrobenthic assemblages’ structure in intertidal Zostera noltei meadows

The present study describes macroinvertebrate assemblages in three Zostera noltei meadows, following a salinity gradient along the Aveiro lagoon (Portugal). The main environmental descriptors and Z. noltei biometrics were studied to provide a model of the multivariate macroinvertebrate assemblage structure. The macroinvertebrate assemblage structure in the meadow close to the lagoon opening was significantly different. This could be explained by its higher organic matter content and salinity values. Our model highlighted that 72% of the variation on macroinvertebrate assemblage structure was explained by the studied variables, being organic matter, salinity and sediment median grain size the most relevant factors. Moreover, the number of Z. noltei shoots, and cover of the invasive species Agarophyton aff. vermiculophyllum were also significant. The strong relationship between macroinvertebrates, environmental descriptors and Z. noltei biometrics validates the usefulness of macroinvertebrates as indicators of the seagrass condition in intertidal environments. This study provides baseline data that will be crucial to detect anthropogenic disturbances and preserve Z. noltei meadows, including their associated biodiversity. These data will also allow focusing on certain environmental factors and Z. noltei biometrics that have proved shaping the macroinvertebrate assemblages’ structure.

Reduced seagrass resilience due to environmental and anthropogenic effects may lead to future die-off events in Florida Bay

Coastal systems often depend on foundation species such as seagrasses that are supported by self-facilitation. Seagrass meadows, however, are threatened worldwide due to climate change and local human impact, disrupting self-facilitation leading to system instability. Florida Bay is a large seagrass dominated coastal ecosystem that suffered from multiple seagrass mortality events over the last half century driven by hypoxia, high water temperatures, hypersalinity, and high biological oxygen demand. These conditions reduce the amount of photosynthetically-derived oxygen in the plant causing sulphide intrusion into meristematic tissues. Using a bay-wide sampling design and long-term monitoring trends of seagrass condition, we investigated the current state of the meadows, sediment characteristics (e.g., organic matter, sulphide, nutrients) and discuss how climate stressors interact with plant and sediment oxygen dynamics. Our survey revealed that at sites where seagrass had been previously denuded by die-off, the dominant seagrass Thalassia testudinum had not recovered, while the pioneering seagrass Halodule wrightii recolonized the impacted areas. Organic matter and sulphide levels were higher at the impacted sites, apparently a persistent characteristic of the formerly dense T. testudinum meadows in central and western Florida Bay. These sediment conditions promote sulphide intrusion of T. testudinum belowground tissue under anoxic conditions. Plant oxidation initially buffers sulphide intrusion, but disruption of this oxidation mechanism due to changing environmental conditions results in widespread mortality and seagrass community collapse. Climate change cannot be fully mitigated by local management, however, attempts can be made to control critical salinity and oxygen levels by increasing freshwater input, reducing hypersalinity and aiming to keep the internal seagrass oxidation feedback intact. Our study shows that the Florida Bay seagrass ecosystem is still recovering four years post die-off and continues to be susceptible to future climate change and system degradation.

Analisis kondisi padang lamun di Gili Balu, Sumbawa Barat

This research is conducted in seagrass meadow communities on Belang Island, Paserang Island, Kenawa Island, and Namo Island which are located in Gili Balu, West Sumbawa. Exploratory data collection was carried out in January 2022 and data processing was carried out from October to December 2022. The data collection procedure used was a training procedure for seagrass conditions using the line transect and square transect methods referring to the LIPI Seagrass Meadow Monitoring Guidebook. Data collection was carried out at each station by spreading the transect line 100 m long and placing the square transect to the right side of the line transect. Monitoring is carried out every 10 m and is carried out up to a point of 100 m. Data collection was repeated 3 times. Data processing was carried out to obtain categories and conditions of seagrass meadow compared to seagrass cover categories by the LIPI Seagrass Monitoring Guidebook and parameters of seagrass conditions by Decree of the Minister of Environment No. 200 of 2004. From the research conducted, it is found that there are 2 stations in the rare category, which are Namo and Kenawa Island, 4 stations with medium category closure of seagrass meadow, which are Paserang Island, Northwestern Belang Island, Southern Belang Island and Eastern Belang Island. The good closing category is obtained by the West Belang Island station. Seagrass meadow communities that are classified as damaged and poor are Namo Island, Kenawa Island, and Northwest Belang Island. Paserang Island and the southern and eastern parts of Belang Island are classified as damaged and unhealthy seagrass meadow. The western part of Belang Island is classified as in good and healthy seagrass condition status.

Evaluating the seagrass ecological condition and habitat extent in Karimunjawa National Park, Jepara Indonesia

In the coastal ecosystem, seagrass meadows play a vital role in delivering ecosystem services such as provision, control, and support. However, this ecosystem is one of the most threatened in the coastal environment, and it has been degraded as a result of anthropogenic disturbance and rapid environmental changes. Furthermore, the extent of the seagrass meadows is unknown, and the health of the meadows is unmonitored and unrecorded. There is little information on the current state of the seagrass extent and health conditions in Karimunjawa National Park. We evaluate the abundance, states, and health conditions of the seagrass meadows based on the ecological quality index in Karimunjawa National Park, Jepara, Indonesia. This district has a vast extent of seagrass meadows but has been affected by the expansion of the industrial/tourism area within the region. This study aimed to assess the seagrass current condition based on the ecological quality index. The result showed that the total seagrass extent area in Karimunjawa National Park was 969,15 ha where seven species were found in this area, including Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Cymodocea serrulate, Halodule pinifolia, Halophila ovalis and Halodule uninervis. Seagrass meadow coverages were moderate and categorized as less healthy. The seagrass ecological quality index value was 0.66 which indicated that the seagrass condition in Karimunjawa National Park was moderate. Ecological factors that affect the seagrass state are epiphyte cover and macroalgal cover.

Nontargeted lipidomics of Florida seagrasses

Seagrasses are one of the most productive foundation species in the world and are important for maintaining ecosystem homeostasis. However, seagrasses have experienced a global decline in areal extent, due in part to environmental stressors. Despite ongoing decline, little is known about the lipidome of most seagrass species. Generally, lipidome profiles closely align with phenotypic changes and can be used to evaluate the condition of an individual. In this study, a nontargeted lipidomics approach, utilizing high-performance liquid chromatography tandem mass spectrometry, was used to assess the lipidome of wild seagrasses in Florida. Overall, 399 individual lipid species, comprised of 33 lipid subclasses, were identified across all specimens. The lipid classes with the highest total concentration, accounting for 75% of total identified lipids in all seagrasses were: monogalactosyldiacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG), and sulfoquinovosyl diacylglycerols (SQDG). Here, the lipidomic profiles of wild seagrasses were identified for the first time, a necessary step toward using lipodomics as a tool for prospective assessments of condition. Once regional and species-specific baselines have been mapped, lipodomic surveys could provide new insight into the effects of environmental stressors on seagrass condition and help to augment ongoing efforts to document and understand seagrass ecosystem status and trends.

Common ecological indicators identify changes in seagrass condition following disturbances in the Gulf of Mexico

Seagrasses are long-lived, clonal plants that can integrate fluctuations in environmental conditions over a range of temporal scales, from days to years, and can act as barometers of coastal change. There are many estimated seagrass traits and ecosystem parameters that have the potential to reflect ecosystem status, linking seagrass condition to natural and anthropogenic drivers of change. We identified five seagrass indicators and seven metrics that are suitable, affordable and frequently measured by 38 monitoring programs across the Gulf of Mexico (GoM). A specific set of ratings and assessment points were formulated for each measurable metric. We determined metric ratings (Acceptable, Concerning, Alarming) and validated assessment points using long-term monitoring data from Texas and Florida, coupled with existing literature and input from a panel of seagrass biologists. We reported scores using a blue-gray-orange (Acceptable-Concerning-Alarming) scale to summarize information in a format accessible to the public, resource managers, stakeholders, and policymakers. Seagrass percent cover, shoot allometry and species composition were sensitive indicators of large-scale climatic disturbances (droughts, hurricanes). Severe drought led to reductions in total seagrass cover and leaf length in Upper Laguna Madre, Texas, and Florida Bay; however, Syringodium filiforme was disproportionally affected in Texas while Thalassia testudinum beds responded strongly to drought impacts in Florida. Hurricanes Harvey (TX) and Irma (FL) also resulted in loss of seagrass cover and diminished leaf length in the Texas Coastal Bend and Florida Keys; both storms largely impacted T. testudinum and to a lesser extent, S. filiforme. Many of the metrics within these affected bays and basins received either a “Concerning” or “Alarming” rating, driven by the impacts of these disturbances. Our proposed indicators serve as a tool to evaluate seagrass condition at the bay or basin scale. Moreover, the indicators, metrics, and assessment points are amenable to large-scale evaluations of ecosystem condition because they are economically feasible. This framework may provide the foundation for a comprehensive assessment of seagrass status and trends across the entire GoM.

Decadal Remote Sensing Analysis of Seagrass Changes in Palu Bay, Central Sulawesi

Seagrass meadows provide a variety of material, non-material and regulatory coastal ecosystem service; however, as the distribution of seagrass beds changes over time due to both anthropogenic activities and natural factors, it is important to monitor changes in seagrass condition. Seagrass meadows in Palu Bay are threatened by activities such as coastal development and land reclamation. Additionally, the bay was hit by a significant tsunami in 2018, which could have impacted ecosystems in the bay, including seagrass meadows. The aim of this study was to detect changes in seagrass extent and distribution over a 10-year period from 2012 to 2022 and changes in land use over approximately a decade (2010 and 2021) through the use of remote sensing technology. Changes in eagrass meadow areal extent were analyzed using data from a 2012 Landsat 7 Satellite Data Acquisition and a 2022 Landsat 8 Satellite Data Acquisition. Water column correction was implemented using the Lyzenga Algorithm. The results showed a significant decrease in the area of seagrass meadows around the coastal area of Palu Bay. Seagrass meadows in 2012 and 2022 covered 127.08 Ha and 87.79 Ha, respectively, indicating a decrease in extent of 43.29 Ha. As the accuracy of the satellite data classification results was 80%, the results are considered acceptable. Anthropogenic activities (mainly mining and construction related) are strongly suspected as the main drivers of this decline, while earthquake and tsunami events likely aggravated the degradation of coastal ecosystems in Palu Bay, including seagrass meadows.

A report card approach to describe temporal and spatial trends in parameters for coastal seagrass habitats

Report cards that are designed to monitor environmental trends have the potential to provide a powerful communication tool because they are easy to understand and accessible to the general public, scientists, managers and policy makers. Given this functionality, they are increasingly popular in marine ecosystem reporting. We describe a report card method for seagrass that incorporates spatial and temporal variability in three metrics—meadow area, species and biomass—developed using long-term (greater than 10 years) monitoring data. This framework summarises large amounts of spatially and temporally complex data to give a numeric score that provides reliable comparisons of seagrass condition in both persistent and naturally variable meadows. We provide an example of how this is applied to seagrass meadows in an industrial port in the Great Barrier Reef World Heritage Area of north-eastern Australia.

Image analysis reveals environmental influences on the seagrass-epiphyte dynamic relationship for Thalassia testudinum in the northwestern Gulf of Mexico

Spatiotemporal patterns in seagrass-epiphyte dynamics for Thalassia testudinum in the northwestern Gulf of Mexico were evaluated through biomass measurements and scanned-image based metrics to investigate the potentially harmful impact of excessive epiphyte accumulations on seagrass condition. Image analysis with Spectral Angle Mapper algorithms distinguished epiphyte and uncovered seagrass leaf pixels to generate a normalized metric of leaf area coverage (epiphyte pixels/total leaf pixels). Imaging metrics were compared to biomass-based metrics seasonally, among three locations with different environmental conditions (depth, salinity, temperature and nutrient levels inferred from sediment porewater measurements) near Redfish Bay, Texas, USA. Image analysis, in conjunction with biomass measures, provides enhanced insight into the seagrass-epiphyte dynamic relationship and how it varies with environmental conditions. Compared with the biomass and morphological measures, image analysis may be more informative as an indicator of environmental changes. Variation in linear regressions of epiphyte biomass vs. epiphyte area (pixels) suggested changes in the thickness and/or density of accumulated epiphytes across environmental contexts and seasons. Two different epiphyte colonization patterns were presented based on the correlation between the normalized metrics of epiphyte load and epiphyte leaf coverage. The epiphyte load was highest at low temperatures and locations with elevated DIN:P ratio in sediment porewater. Conversely, the mean leaf coverage by epiphytes stayed relatively constant (± 10%) across seasons but differed by location (25% ~55% in this case), suggesting that leaf growth in this study is regulated to maintain the proportion of uncolonized leaf surface and that epiphyte coverage plays a role in its regulation.

Current status of seagrass condition in coastal waters of Kendari Southeast Sulawesi Indonesia

Seagrass is one of the most productive ecosystems in the shallow waters and has a significant role as shelter and nurseries for marine biotas. The coastal region of Kendari has seagrass, mangrove, and coral reef ecosystems. However, this ecosystem tends to be decreasing due to coastal development activities in the coastal area. This study aims to find out the seagrass condition in Kendari from 2015 to 2021. To analyze species composition and seagrass percent coverage the transect method refers to the Guideline of seagrass monitoring was applied. The determination of seagrass conditions refers to the Decree of Indonesia’s state the Minister for the Environment no. 200 of 2004. The extant benthic habitats of seagrass were analyzed using satellite imagery data. Based on the analysis of the area of benthic habitat from the year 2015 to 2021, the data obtained in shows an increase from the year 2015 to 2017, and then decrease the year 2021.There were eight species recorded in the area such as Enhalus acoroides, Thalassia hemprichii, Cymodocea rutondata, Cymodocea serrulta, Halophila ovalis, Halodule uninervis, Halodule pinifolia, and Syringodium isoetifolium. Based on its percentage cover four sites of seagrass are classified as “poor” (15%-24%) and two sites are classified as “healthy” (67%) and “less healthy” (59,3%) respectively. Overall, the condition of seagrass in the coastal waters of Kendari is “less healthy”.

Seasonal links between metabolites and traditional seagrass metrics in the seagrass Halophila ovalis in an estuarine system

Monitoring of seagrasses has mainly relied on traditional seagrass metrics (e.g., biomass), which deliver reliable information about mortality but are unable to inform about impacts on seagrass health at the very early stages of stress exposure. Metabolomics is a novel molecular technique which can be used for early stress-detection in plants and also for unravelling the underlying mechanisms of stress response. In the Swan-Canning Estuary, south-west Australia, the seagrass Halophila ovalis is impacted by seasonal changes in sediment-and nutrient-stress. To date, it is unknown how H. ovalis responds to these seasonal stressors on a molecular level. Here, we used a combined approach of traditional seagrass metrics and metabolomics to create a holistic picture of seasonal influences on seagrass condition. Leaf samples of H. ovalis were collected from six different locations in the Swan-Canning Estuary in both summer and spring. We detected strong differences in metabolite profiles and relative metabolite abundance between seasons, with growth- and/or development-related metabolites being up-regulated in spring and stress-related (secondary) metabolites being up-regulated in summer. Metabolites were mostly related to leaf δ13C signatures, a metric that has been previously associated with variation in light and pH in the Swan-Canning. We demonstrate that a holistic approach which includes metabolomics into ecological monitoring can help to improve our understanding of the mechanisms underlying molecular (stress) responses in seagrasses which is crucial knowledge for management and conservation measures locally and globally.

Spatially Explicit Seagrass Extent Mapping Across the Entire Mediterranean

The seagrass Posidonia oceanica is the main habitat-forming species of the coastal Mediterranean, providing millennial-scale ecosystem services including habitat provisioning, biodiversity maintenance, food security, coastal protection, and carbon sequestration. Meadows of this endemic seagrass species represent the largest carbon storage among seagrasses around the world, largely contributing to global blue carbon stocks. Yet, the slow growth of this temperate species and the extreme projected temperature and sea-level rise due to climate change increase the risk of reduction and loss of these services. Currently, there are knowledge gaps in its basin-wide spatially explicit extent and relevant accounting, therefore accurate and efficient mapping of its distribution and trajectories of change is needed. Here, we leveraged contemporary advances in Earth Observation—cloud computing, open satellite data, and machine learning—with field observations through a cloud-native geoprocessing framework to account the spatially explicit ecosystem extent of P. oceanica seagrass across its full bioregional scale. Employing 279,186 Sentinel-2 satellite images between 2015 and 2019, and a human-labeled training dataset of 62,928 pixels, we mapped 19,020 km2 of P. oceanica meadows up to 25 m of depth in 22 Mediterranean countries, across a total seabed area of 56,783 km2. Using 2,480 independent, field-based points, we observe an overall accuracy of 72%. We include and discuss global and region-specific seagrass blue carbon stocks using our bioregional seagrass extent estimate. As reference data collections, remote sensing technology and biophysical modelling improve and coalesce, such spatial ecosystem extent accounts could further support physical and monetary accounting of seagrass condition and ecosystem services, like blue carbon and coastal biodiversity. We envisage that effective policy uptake of these holistic seagrass accounts in national climate strategies and financing could accelerate transparent natural climate solutions and coastal resilience, far beyond the physical location of seagrass beds.

Predicting and Scoring Estuary Ecological Health Using a Bayesian Belief Network

Excessive nutrient and sediment inputs threaten ecological condition in many estuaries. We describe a Bayesian Belief Network (BBN) that calculates an Estuary Trophic Index (ETI) score ranging between 0 (no symptoms of eutrophication) to 1 (grossly eutrophic) for estuaries in Aotearoa New Zealand (NZ). The ETI BBN includes estuary physiographic characteristics (estuary type, flushing time, intertidal area, estuary closure state, water column stratification) and nutrient and sediment loads available from existing geospatial tools and databases, that drive responses of ‘primary’ indicators (macroalgae and phytoplankton biomass) and ‘secondary’ indicators (or symptoms) of estuary ecological impairment (sediment carbon, sediment apparent redox potential discontinuity depth, water column oxygen, macrobenthos and seagrass condition). Relationships between the BBN nodes are based primarily on observational and model-based information from NZ and international studies rather than expert opinion. The model can be used in a purely predictive manner under knowledge-poor situations, using only the physiographic drivers and nutrient/sediment loads, or refined using field-derived observations of indicator values to reduce the uncertainty associated with the probabilistic BBN score. It is designed for shallow tidal lagoons, tidal river estuaries and coastal lakes; systems which are sensitive to eutrophication and sedimentation pressure and are common in NZ and globally. Modelled ETI BBN scores agreed well with ETI scores calculated from observed indicator values for 11 well-studied NZ estuaries. We predict ecological condition of 291 NZ estuaries, most of which have no monitored information on trophic state. We illustrate capabilities of the ETI BBN with two case studies: to evaluate improvements in estuary health arising from diversion of wastewater from an estuary via an ocean outfall, and to estimate catchment diffuse nutrient load reductions required to meet estuary health objectives. The ETI BBN may serve as a template for other agencies wishing to develop similar tools.

Composition of Seagrass Root Associated Bacterial Communities Are Linked to Nutrients and Heavy Metal Concentrations in an Anthropogenically Influenced Estuary

Seagrasses are globally recognized as bioindicators of marine eutrophication and contamination. Seagrasses also harbor a distinct root microbial community that largely reflects the conditions of the surrounding environment as well as the condition of the seagrass. Hence monitoring changes in the root microbial community could act as an additional biological indicator that reflects both the seagrass health condition, as well as potential deterioration in coastal waters. We used 16S rRNA gene sequencing combined with analysis of seagrass nutrients (C, N, δ15N, δ13C) and tissue metal concentrations to investigate potential links between seagrass (Halophila ovalis) root bacteria and seagrass nutrient and metal concentrations within an anthropogenically influenced estuary. We found seagrass tissue nitrogen (%) and δ15N values were 2–5 times higher than global averages for this species. Seagrass root associated bacteria formed distinct communities that clustered by site and were correlated to both seagrass nutrient and metal concentration, with some putative sulfide oxidizing bacteria (Sulfurimonas and Sulfurovum) correlated with greater nutrient concentrations, and putative iron cycling bacteria (Lewinella and Woeseia) correlated with greater Fe and As concentrations. Our findings shed further light on the relationship between seagrass and their microbes, as well as provide additional assessment of the use of both seagrass and their microbes as indicators of estuarine and seagrass condition.

Seagrass rehabilitation in Thousand Islands, Jakarta: step to restore

Seagrass plays an essential role in coastal areas with ecological functions as a marine habitat, sediment trap, sediment stabilizer, nutrients filter, and dampen current. Fisheries and tourism are the seagrass ecosystem services that are the primary community livelihood in Thousand Island. However, seagrass condition has decreased in the last decade, influenced by coastal development, mass tourism, and climate change. This study aims to assessed the seagrass status and identify the threat in the last decade. Seagrass coverage was assessed in 2007 and 2018 using plot transect, and then seagrass threats were documented and collected from research articles, manuscripts, proceedings, and unpublished reports. Seagrass coverage has significantly decreased on Thousand Islands. Seagrass threats include pollution, reclamation, vessel activities, mass tourism, coastal development, climate change, and biotic factors (macroalgae and epiphyte coverage). The threats impact seagrass conditions, such as species diversity, area, and ecosystem services. Rehabilitation is needed to recover seagrass conditions using a direct or indirect approach. These findings recommend that managers should arrange the seagrass rehabilitation action plan to minimize seagrass degradation.

Epiphytic hydroid community as sentinels of seagrass condition and human impacts

Negative human actions on seagrasses affect habitat condition and its associated fauna. Epiphytic hydroid's assemblage response to seagrass condition, water quality, and human impacts was evaluated in two bays of the Sabana-Camagüey Ecosystem of Cuba, using the presence of contamination, causeways, and trawling fishing as impact level proxies to the seagrass meadows. Thirty-eight species composed the hydroid's assemblage including five new records. Symmetroscyphus intermedius was the most abundant species and sensitive to indicators of the seagrass condition. Dynamena disticha and Gastroblasta sp. were sensitive to water quality predictors. Obelia bidentata was exclusive to the most impacted sites. Species richness and abundance were low in impacted sites and were highly affected by fishing trawling and causeways construction. Salinity, depth, NO2, pH, SSV, macroalgae cover, shoot density, and wet weight of Thalassia testudinum were the best predictors for hydroid's assemblages. Results suggest epiphytic hydroids on tropical seagrass meadows as sentinel organisms.

Seagrass Condition at Some Small Islands in The Taka Bonerate National Marine Park, South Sulawesi Indonesia

The assessment of seagrass bed condition in Indonesia still refers to the Decree of the State Minister for the Environment (KMNLH) no. 200 of 2004, which considers only one variable, namely the percentage of seagrass cover. To assess the seagrass beds condition to be more in-depth and meaningful, it is necessary to consider the addition of several variables, such as the biotic variables (seagrass species diversity including macroalgae and macro-benthos components) as well as the abiotic variables (reef flat areas and the substrate components). The purpose of this study is to determine the seagrass beds condition in several small islands in the Taka Bonerate National Marine Park by considering the additional analysis using both biotic and abiotic variables as mentioned above. The methodology used in this study is a combination of the use of the standard seagrass transect method, interpretation of satellite imagery related to the seagrass bottom habitat area, and its components on the reef flat of a particular island, as well as weighting and scoring based on those considered additional variables. By applying the criteria in the method, the seagrass bed conditions were then classified into three categories, namely seagrass in good, moderate, and unfavorable conditions, respectively. The results of the total score assessment on several small islands in Taka Bonerate Islands show that the seagrass bed in Latondu Besar Island is in good conditions with the highest score of (316) compared to Tarupa Besar, Jinato, Rajuni Kecil, and Tinabo Besar Islands with an average score of (173). The results of this study indicate that the assessment of seagrass conditions is more meaningful in terms of seagrass ecology than based on seagrass cover alone. However, this study requires a lot of validation for its application in assessing the condition of seagrass beds in other islands in Indonesia.

Connecting targets for catchment sediment loads to ecological outcomes for seagrass using multiple lines of evidence

Catchment impacts on downstream ecosystems are difficult to quantify, but important for setting management targets. Here we compared 12 years of monitoring data of seagrass area and biomass in Cleveland Bay, northeast Australia, with discharge and associated sediment loads from nearby rivers. Seagrass biomass and area exhibited different trajectories in response to river inputs. River discharge was a slightly better predictor of seagrass indicators than total suspended solid (TSS) loads, indicating that catchment effects on seagrass are not restricted to sediment. Linear relationships between Burdekin River TSS loads delivered over 1–4 years and seagrass condition in Cleveland Bay generated Ecologically Relevant Targets (ERT) for catchment sediment inputs. Our predicted ERTs were comparable to those previously estimated using mechanistic models. This study highlights the challenges of linking catchment inputs to condition of downstream ecosystems, and the importance of integrating a variety of metrics and approaches to increase confidence in ERTs.

Preliminary assessment of Tripneustes gratilla populations in Seagrass Beds of the Spermonde Archipelago, South Sulawesi, Indonesia

Many sea urchins, including the collector urchin Tripneustes gratilla, are well known for their role as herbivores, contributing to the control of fast growing macroalgae that can potentially overgrow and dominate seagrass beds and reef flats. Tripneustes gratilla is a short-spined sea urchin that can be easily found and collected by hand from the seagrass meadows which are their main habitat, especially during low tide. The exploitation of this species in Indonesia began to expand several years ago when the demand for T. gratilla gonads started to rise, for both commercial purposes and household consumption. This study aimed to determine the population and distribution of T. gratilla in seagrass ecosystems with different conditions across the Spermonde Archipelago, South Sulawesi, Indonesia. The results indicate that T. gratilla population abundance and size distribution are affected by several factors: seagrass condition, water quality, and the intensity of sea urchin collection. The results also emphasize the urgent need for developing and implementing effective management to ensure the sustainability of this important sea urchin species.

Seagrass ecosystems of the Pacific Island Countries and Territories: A global bright spot

Seagrass ecosystems exist throughout Pacific Island Countries and Territories (PICTs). Despite this area covering nearly 8% of the global ocean, information on seagrass distribution, biogeography, and status remains largely absent from the scientific literature. We confirm 16 seagrass species occur across 17 of the 22 PICTs with the highest number in Melanesia, followed by Micronesia and Polynesia respectively. The greatest diversity of seagrass occurs in Papua New Guinea (13 species), and attenuates eastward across the Pacific to two species in French Polynesia. We conservatively estimate seagrass extent to be 1446.2 km2, with the greatest extent (84%) in Melanesia. We find seagrass condition in 65% of PICTs increasing or displaying no discernible trend since records began. Marine conservation across the region overwhelmingly focuses on coral reefs, with seagrass ecosystems marginalised in conservation legislation and policy. Traditional knowledge is playing a greater role in managing local seagrass resources and these approaches are having greater success than contemporary conservation approaches. In a world where the future of seagrass ecosystems is looking progressively dire, the Pacific Islands appears as a global bright spot, where pressures remain relatively low and seagrass more resilient.