Estimasi Stok Karbon Padaekosistem Lamun Di Perairan Utara Papua (Studi Kasus : Pulau Liki, Pulau Befondi Dan Pulau Meossu)

One of the ecological functions of the seagrass ecosystem is the ability to absorb carbon coming from the atmosphere. The ability of seagrass to absorb carbon is carried out through photosynthesis. The absorbed carbon will then be stored in the form of seagrass biomass in the seagrass body. This study aims to estimate the carbon stock content stored in seagrass ecosystems in the Northern waters of Papua including on Liki Island, Befondi Island, and Meossu Island. The calculation of carbon stock is done by converting seagrass biomass using constants derived from representative values of seagrass carbon content in Indonesian waters. In general, based on the results obtained indicate that the biomass at the bellow ground of the seagrass is greater than the biomass at above ground the seagrass. The value of organic carbon content in seagrasses is influenced by seagrass biomass. The carbon stock content in the seagrass ecosystem in the study area is in the range of 18,04 – 419,46 g C / m2. Stations on Liki Island have generally higher carbon stocks compared to stations on other islands.Salah satu fungsi ekologi dari ekosistem lamun yaitu memiliki kemampuan dalam menyerap karbon yang berasal dari atmosfer. Kemampuan lamun dalam menyerap karbon dilakukan melalui proses fotosintesis. Karbon yang terserap selanjutnya akan disimpan dalam bentuk biomassa lamun  pada tubuh lamun. Penelitian ini bertujuan untuk mengestimasi kandungan stok karbon yang tersimpan pada ekosistem lamun di Perairan Utara Papua tepatnya di Pulau Liki, Pulau Befondi dan Pulau Meossu. Perhitungan stok karbon dilakukan dengan melakukan konversi biomassa lamun menggunakan konstanta yang berasal dari nilai representatif konsentrasi kandungan karbon pada lamun yang berada di Perairan Indonesia. Secara umum berdasarkan hasil yang diperoleh menunjukkan bahwa biomassa pada bagian bawah lamun lebih besar dibandingkan dengan biomassa pada bagian atas lamun. Nilai kandungan karbon organik pada lamun dipengaruhi oleh biomassa lamun. Kandungan stok karbon pada ekosistem lamun di wilayah penelitian  berada pada kisaran 18,04 – 419,46 gC/m2. Stasiun yang berada di Pulau Liki memiliki stok karbon yang umumnya lebih tinggi dibandingkan dengan stasiun yang berada di pulau lainnya.

Ocean connectivity and habitat characteristics predict population genetic structure of seagrass in an extreme tropical setting

Understanding patterns of gene flow and processes driving genetic differentiation is important for a broad range of conservation practices. In marine organisms, genetic differentiation among populations is influenced by a range of spatial, oceanographic, and environmental factors that are attributed to the seascape. The relative influences of these factors may vary in different locations and can be measured using seascape genetic approaches. Here, we applied a seascape genetic approach to populations of the seagrass, Thalassia hemprichii, at a fine spatial scale (~80 km) in the Kimberley coast, western Australia, a complex seascape with strong, multidirectional currents greatly influenced by extreme tidal ranges (up to 11 m, the world\u27s largest tropical tides). We incorporated genetic data from a panel of 16 microsatellite markers, overwater distance, oceanographic data derived from predicted passive dispersal on a 2 km-resolution hydrodynamic model, and habitat characteristics from each meadow sampled. We detected significant spatial genetic structure and asymmetric gene flow, in which meadows 12–14 km apart were less connected than ones 30–50 km apart. This pattern was explained by oceanographic connectivity and differences in habitat characteristics, suggesting a combined scenario of dispersal limitation and facilitation by ocean current with local adaptation. Our findings add to the growing evidence for the key role of seascape attributes in driving spatial patterns of gene flow. Despite the potential for long-distance dispersal, there was significant genetic structuring over small spatial scales implicating dispersal and recruitment bottlenecks and highlighting the importance of implementing local-scale conservation and management measures

Hydrodynamics across seagrass meadows and its impacts on Indonesian coastal ecosystems: A review

Seagrass canopies are important components of the world’s coastal environments providing critical ecological services. Nearshore hydrodynamics, i.e., waves and currents, are essential in controlling the ecological processes across coastal environments. Seagrass meadows can impose more complex hydrodynamics processes by attenuating sea-swell waves and decreasing the impact of nearshore mean water level rise due to wave setup and Infragravity (IG) waves. Consequently, the seagrasses dissipate waves and reduce flows allowing sediments to settle and accrete the shorelines. However, despite their significant roles, knowledge of hydrodynamics in the Indonesian seagrass ecosystems is relatively limited compared to other coastal ecosystems such as sandy beaches, mangroves, and coral reefs. This review highlights the dynamics of waves and currents, and their interaction with sediment transport and ecological processes, including biogeochemical and dispersal processes on the seagrass ecosystem contributing to the existing seagrass research in Indonesia. The associated literature is collected from scientific databases such as Scopus and Google Scholar that range between 1965 and 2021. The result showed that most of the research on hydrodynamic in seagrass ecosystems was carried out in temperate zones. Until recently, there have been limited publications discussing the interaction between the Indonesian (tropical) seagrass ecosystem and hydrodynamics parameters, even though the region has abundant seagrass species. Moreover, Indonesia is strongly influenced by various atmospheric-oceanic forcing, including the Asian monsoon affecting the dynamic of the coastal area with seagrass ecosystems. At a canopy scale, the correlation between the nearshore (tropical) hydrodynamics and ecological processes in the system is yet to be explored. Considering the potential benefit of seagrasses to coastal ecosystems, developing future research in hydrodynamics across the ecosystem is critical to overcoming the knowledge gaps in Indonesia. The knowledge gained could support the Indonesian seagrass ecosystem services and their resilience to potential hazards and climate change

Historical processes and contemporary ocean currents drive genetic structure in the seagrass Thalassia hemprichii in the Indo-Australian Archipelago [dataset]

Understanding spatial patterns of gene flow and genetic structure is essential for the conservation of marine ecosystems. Contemporary ocean currents and historical isolation due to Pleistocene sea-level fluctuations have been predicted to influence the genetic structure in marine populations. In the Indo-Australian Archipelago (IAA), the world\u27s hotspot of marine biodiversity, seagrasses are a vital component but population genetic information is very limited. Here, we reconstructed the phylogeography of the seagrass Thalassia hemprichii in the IAA based on single nucleotide polymorphisms (SNPs) and then characterised the genetic structure based on a panel of 16 microsatellite markers. We further examined the relative importance of historical isolation and contemporary ocean currents in driving the patterns of genetic structure. Results from SNPs revealed three population groups: eastern Indonesia, western Indonesia (Sunda Shelf), and Indian Ocean; while the microsatellites supported five population groups (eastern Indonesia, Sunda Shelf, Lesser Sunda, Western Australia, and Indian Ocean). Both SNPs and microsatellites showed asymmetrical gene flow among population groups with a trend of south-westward migration from eastern Indonesia. Genetic diversity was generally higher in eastern Indonesia and decreased southwestward. The pattern of genetic structure and connectivity is attributed partly to the Pleistocene sea level fluctuations modified to a smaller level by contemporary ocean currents

Historical processes and contemporary ocean currents drive genetic structure in the seagrass Thalassia hemprichii in the Indo-Australian Archipelago [dataset]

Understanding spatial patterns of gene flow and genetic structure is essential for the conservation of marine ecosystems. Contemporary ocean currents and historical isolation due to Pleistocene sea-level fluctuations have been predicted to influence the genetic structure in marine populations. In the Indo-Australian Archipelago (IAA), the world\u27s hotspot of marine biodiversity, seagrasses are a vital component but population genetic information is very limited. Here, we reconstructed the phylogeography of the seagrass Thalassia hemprichii in the IAA based on single nucleotide polymorphisms (SNPs) and then characterised the genetic structure based on a panel of 16 microsatellite markers. We further examined the relative importance of historical isolation and contemporary ocean currents in driving the patterns of genetic structure. Results from SNPs revealed three population groups: eastern Indonesia, western Indonesia (Sunda Shelf), and Indian Ocean; while the microsatellites supported five population groups (eastern Indonesia, Sunda Shelf, Lesser Sunda, Western Australia, and Indian Ocean). Both SNPs and microsatellites showed asymmetrical gene flow among population groups with a trend of south-westward migration from eastern Indonesia. Genetic diversity was generally higher in eastern Indonesia and decreased southwestward. The pattern of genetic structure and connectivity is attributed partly to the Pleistocene sea level fluctuations modified to a smaller level by contemporary ocean currents

Genetic connectivity in tropical and temperate Australian seagrass species

Connectivity among populations influences resilience, genetic diversity , adaptation and speciation, so understanding this process is fundamental for conservation and management. This chapter summarises the main mechanisms of gene flow within and among seagrass meadows, and what we know about the spatial patterns of gene flow around Australia’s coastline. Today a significant body of research on the demographic and genetic connectivity of Australian seagrass meadows has developed. Most studies have focused on the genera Posidonia, Zostera, Heterozostera and Thalassia, in tropical and temperate systems across a range of habitats. These studies have shown overwhelmingly, that sexual reproduction is important for meadow persistence, as in most cases Australian seagrass meadows are genotypically diverse, with moderate to high levels of genotypic diversity. This high diversity could be generated through demographic connectivity, recruitment of individuals sourced from within a meadow, or from dispersal between meadows. Attempts to understand the relative significance of these processes are limited, highlighting a major gap in our understanding. Genetic structure is apparent across a range of spatial scales, from m’s to 100’s to 1000’s km. At local and regional scales, particularly in confined systems such as estuaries and bays, it is not necessarily the dominant oceanographic currents influencing patterns of genetic connectivity, but local eddies, winds and tides. Over larger spatial scales, isolation by distance is consistently significant, with unique genetic clusters spreading over 100s of kilometres. This indicates that regional structure occurs at the limits of long distance dispersal for the species and this is particularly evident where meadows are highly fragmented. The number of genetic studies on Australian seagrasses has increased dramatically recently; however, there are still many opportunities to improve our understanding through focusing on species with different dispersal potentials, more detailed sampling across a range of spatial and temporal scales and combining ecological and modelling approaches

Predictors of marine genetic structure in the Indo-Australian Archipelago

The spatial genetic structure of marine organisms is related to dispersal and life-history traits, historical processes, current oceanographic connectivity and habitat features. Here, we assessed the relative importance of these factors for the genetic structure of a broad range of marine species in the Indo Australian Archipelago (IAA). We collated published data on 99 marine species from eight taxonomic groups (ascidians, fishes, molluscs, crustaceans, echinoderms, corals, reptiles, and marine plants) and used generalized linear models (GLMs) to estimate the best predictors of genetic structure. Genetic structure was characterized by FST and the number of genetic clusters over the study area. Predictors tested were: the type of genetic markers; the number of marine ecoregions which are a proxy for habitat variation, historical processes and oceanographic features; species dispersal-related traits (i.e., pelagic larval duration-PLD, adult life habit, reproductive strategy, and egg type); and geographic distance separating populations. The genetic structure of marine species across the IAA was best predicted by traits related to dispersal of larvae or propagules and the mobility of adults; and the number of marine ecoregions sampled not distance was also an important predictor, especially in sedentary and free-swimming species. Our findings highlighted the importance of these key traits to help guide decision-making in spatial management and conservation. There were still many gaps in our understanding of genetic structure, both spatially and within certain taxa, and we recommended future genetic studies focus on habitat-forming taxa and sample sites that are representatively nested in each ecoregion within a marine province or a marine realm, over the spatial extent of the IAA