Studi Komunitas Padang Lamun di Kecamatan Tanggetada, Kabupaten Kolaka, Sulawesi Tenggara

Kecamatan Tanggetada memiliki areal padang lamun yang luas dan sering dimannfaatkan oleh masyarakat. Padang lamun di daerah ini belum terkonfimasi secara ilmiah baik itu dari jenis, kerapatan dan komunitas lamunnya. Penelitian ini bertujuan untuk mengetahui jenis dan kerapatan lamun di Kecamatan Tanggetada. Metode yang digunakan pada penelitian ini adalah metode transek kuadrat pada areal 100 m2 ditiap stasiun. Lokasi penelitian berada di 3 stasiun yaitu Stasiun 1 di Kelurahan Tanggetada, Stasiun 2 di Desa Palewai dan Stasiun 3 Kecamatan Anaiwoi. Hasil penelitian, ditemukan 6 jenis lamun tersebar di Kecamatan Tanggetada yaitu Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Halodule uninervis, Halophila ovalis, dan Syringodium isoetifolium. Kerapatan lamun termasuk dalam kategori rapat dan jarang. Stsiun 1 memiliki kerapatan lamun yang tinggi dengan ketegori rapat yaitu 160.46 ind/m2, kemudian Stasiun 2 dengan kerapatan lamun agak rapat yaitu 117.49 ind/m2 dan Stasiun 3 dengan kerapatan lamun yang rendah dengan kategori jarang yaitu 60.59 ind/m2. Thalassia Hempricii merupakan lamun yang memiliki nilai kerapatan paling tinggi dibandingkan jenis lamun lainnya.

Local Victory: Assessing Interspecific Competition in Seagrass From a Trait-Based Perspective

Tropical seagrass meadows are formed by an array of seagrass species that share the same space. Species sharing the same plot are competing for resources, namely light and inorganic nutrients, which results in the capacity of some species to preempt space from others. However, the drivers behind seagrass species competition are not completely understood. In this work, we studied the competitive interactions among tropical seagrass species of Unguja Island (Zanzibar, Tanzania) using a trait-based approach. We quantified the abundance of eight seagrass species under different trophic states, and selected nine traits related to light and inorganic nutrient preemption to characterize the functional strategy of the species (leaf maximum length and width, leaves per shoot, leaf mass area, vertical rhizome length, shoots per meter of ramet, rhizome diameter, roots per meter of ramet, and root maximum length). From the seagrass abundance we calculated the probability of space preemption between pairs of seagrass species and for each individual seagrass species under the different trophic states. Species had different probabilities of space preemption, with the climax species Thalassodendron ciliatum, Enhalus acoroides, Thalassia hemprichii, and the opportunistic Cymodocea serrulata having the highest probability of preemption, while the pioneer and opportunistic species Halophila ovalis, Syringodium isoetifolium, Halodule uninervis, and Cymodocea rotundata had the lowest. Traits determining the functional strategy showed that there was a size gradient across species. For two co-occurring seagrass species, probability of preemption was the highest for the larger species, it increased as the size difference between species increased and was unaffected by the trophic state. Competitive interactions among seagrass species were asymmetrical, i.e., negative effects were not reciprocal, and the driver behind space preemption was determined by plant size. Seagrass space preemption is a consequence of resource competition, and the probability of a species to exert preemption can be calculated using a trait-based approach.

KOMUNITAS LAMUN DI PERAIRAN PANTAI DESA ORI, MALUKU TENGAH

Seagrass communities play an important role in marine environments and estuary area, supporting communities of fish, snails and shellfish and other invertebrates. The diversity of seagrass species in the world is very low (<60 species). The coastal waters of Ori Village have a seagrass community that has never been studied. The purpose of this study was to estimate the structure of the seagrass community in the coastal waters of Ori Village, Central Maluku which includes the composition of type, density, frequency of occurence and percent of coverage. Seagrass sampling uses the line transect method. Five species of seagrass were found during the study grouped into two families: Cymodoceaceae and Hydrocharitaceae. The seagrass species found were Cymodocea rotundata, Halodule pinifolia, Enhalus acoroides Halophila ovalis and Thalassia hemprichii. T. hemprichii and E. acoroides have the highest densities (157 shoots/m2 and 137 shoots/m2, respectively). E. acoroides and T. hemprichii also have the highest frequency of occurence and relative coverage percent compared to other seagrass species found in the waters of Ori Village. Seagrass community in the waters of Ori Village is classified in a tight condition until dense. ABSTRAK Komunitas lamun memegang peranan penting di lingkungan laut dan daerah estuari, menyokong komunitas ikan, siput dan kerang-kerangan serta invertebrata lainnya. Keragaman spesies lamun di dunia sangat rendah (<60 spesies). Perairan pantai Desa Ori memiliki komunitas lamun yang belum pernah diteliti. Tujuan dari penelitian ini adalah untuk mengestimasi struktur komunitas lamun di perairan pantai Desa Ori, Maluku Tengah yang meliputi komposisi jenis, kerapatan, frekuensi kehadiran dan persen penutupan. Pengambilan sampel lamun menggunakan metode transek garis. Lima spesies lamun ditemukan selama penelitian yang dikelompokan dalam dua famili yaitu famili Cymodoceaceae dan Hydrocharitaceae. Spesies-spesies lamun yang ditemukan adalah Cymodocea rotundata, Halodule pinifolia, Enhalus acoroides Halophila ovalis danThalassia hemprichii. T. hemprichii dan E. acoroides memiliki kerapatan tertinggi (masing-masing 157 tegakan/m2 dan 137 tegakan/m2). E. acoroides dan T. hemprichii juga memiliki frekuensi kehadiran serta persen penutupan relatif tertinggi dibanding spesies-spesies lamun lainnya yang ditemukan di perairan Desa Ori. Komunitas lamun di perairan Desa Ori tergolong dalam kondisi rapat sampai padat. Kata Kunci: Lamun, komunitas, kerapatan, penutupan, Maluku Tengah

A comparative study of Seagrasses Species in Regional Seas and QMZ

Seagrasses are flowering monocot green plants that have adapted to marine life, and remain completely immersed in seawater and are primary producers of food for numerous marine animals. Seagrasses are of worldwide distribution and it was earlier estimated that there are approximately 60-72 known species of seagrasses. It is now evident that the number of seagrasses species is almost 200, comprising 25 genera and 5 families, namely Cymodoceaceae, Hydrocharitaceae, Posidoniaceae, Zosteraceae and Ruppiaceae, covering a global area of 300,000-600,000 km2. It is also estimated that they have declined in area by 29%. The Western Indo-Pacific realm encompasses 13 species in two families; the Cymodoceacae with 4 genera and the Hydrocharitaceae with 3 genera. Twelve species extend into the Red Sea, 4 occur in the Arabian/Persian Gulf and 4 in the Arabian Sea. The total area of Qatar marine zone (EEZ) is approximately 35,000km2 and three species of seagrasses are known to occur in this zone. These are Halophila stipulacea, Halophila ovalis and Halodule uninervisis, the most common one. It is established that seagrasses consolidate and stabilize bottom sediments, create and maintain good water quality (clarity), produce oxygen, provide food, nursery ground for many animals and have been proven to be very important in GHG emissions.

Genomics-Based Phylogenetic and Population Genetic Analysis of Global Samples Confirms Halophila johnsonii Eiseman as Halophila ovalis (R.Br.) Hook.f.

Halophila johnsonii is an endangered seagrass species that is restricted to the southeast coast of Florida, United States. Its taxonomic status has been called into question, in particular, given the close morphological and genetic similarity of H. johnsonii and the widely distributed and morphologically variable Halophila ovalis, which is largely restricted to the Indo-Pacific region. While a close relationship to H. ovalis is uncontroversial, it remains uncertain whether H. johnsonii represents a distinct lineage or is a recent introduction to the Florida region. Given the conservation status of H. johnsonii, distinguishing these alternatives has important implications for the management of the species and its habitat. Here, we develop molecular data sets for samples of H. johnsonii and H. ovalis including DNA sequences, genome-wide SNPs and microsatellites with the view to resolving the affinities of H. johnsonii with respect to the wider H. ovalis complex. Phylogenetic hypotheses based upon plastid (∼18000 bp) and low copy nuclear DNA (∼6500 bp) sequences derived from hybrid capture, along with 990 genome-wide ddRAD SNPs consistently resolved H. johnsonii within H. ovalis. Specifically, we found a close affinity between H. johnsonii and H. ovalis sampled from the east coast of Africa. In addition, Halophila specimens collected in Antigua, which are within the range of morphological variation typical for H. ovalis, are virtually identical to H. johnsonii and the East African H. ovalis samples based upon DNA sequence analyses and these group together using Bayesian clustering analyses of microsatellites and ddRAD SNPs. We conducted population genetic analyses using large number of H. johnsonii samples collected over a 17-year period. Genotypic data generated through microsatellites and ddRAD SNPs revealed genetic uniformity for all 132 H. johnsonii samples across the Indian River Lagoon, Florida, while samples of H. ovalis from Antigua shared the same genotype as H. johnsonii. We conclude that the lack of genetic diversity and the absence of sexual reproduction strongly indicates that the total range of H. johnsonii is actually one clone that is closely related to populations in Africa and Antigua and may be derived from a recent introduction from one of those regions.

Distinct Endophytic Bacterial Communities Inhabiting Seagrass Seeds

Seagrasses are marine angiosperms that can live completely or partially submerged in water and perform a variety of significant ecosystem services. Like terrestrial angiosperms, seagrasses can reproduce sexually and, the pollinated female flower develop into fruits and seeds, which represent a critical stage in the life of plants. Seed microbiomes include endophytic microorganisms that in terrestrial plants can affect seed germination and seedling health through phytohormone production, enhanced nutrient availability and defence against pathogens. However, the characteristics and origins of the seagrass seed microbiomes is unknown. Here, we examined the endophytic bacterial community of six microenvironments (flowers, fruits, and seeds, together with leaves, roots, and rhizospheric sediment) of the seagrass Halophila ovalis collected from the Swan Estuary, in southwestern Australia. An amplicon sequencing approach (16S rRNA) was used to characterize the diversity and composition of H. ovalis bacterial microbiomes and identify core microbiome bacteria that were conserved across microenvironments. Distinct communities of bacteria were observed within specific seagrass microenvironments, including the reproductive tissues (flowers, fruits, and seeds). In particular, bacteria previously associated with plant growth promoting characteristics were mainly found within reproductive tissues. Seagrass seed-borne bacteria that exhibit growth promoting traits, the ability to fix nitrogen and anti-pathogenic potential activity, may play a pivotal role in seed survival, as is common for terrestrial plants. We present the endophytic community of the seagrass seeds as foundation for the identification of potential beneficial bacteria and their selection in order to improve seagrass restoration.

POTENSI SIMPANAN KARBON PADANG LAMUN DI PANTAI POKEMON, KARIMUNJAWA

Peningkatan emisi Gas Rumah Kaca (GRK) terutama karbondioksida (CO2) menyebabkan pemanasan global. Oleh karena itu diperlukan mitigasi emisi CO2 dengan memanfaatkan potensi lamun sebagai penyimpan karbon dalam bentuk biomassa. Tujuan penelitian ini untuk mengetahui kemampuan lamun jaringan atas dan jaringan bawah dalam menyimpan karbon di perairan Pantai Pokemon pada Agustus 2020. Metode penelitian yang digunakan yaitu metode survei dan deskriptif eksploratif. Sampel diambil dari 3 stasiun pengamatan dengan line dan kuadrant transect menggunakan metode purposive sampling. Pengukuran parameter kualitas perairan dilakukan secara insitu. Analisis simpanan karbon lamun diukur menggunakan metode pengabuan atau loss on ignition (LOI). Hasil penelitian menunjukkan terdapat 4 jenis lamun yaitu Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, dan Halophila ovalis dengan jenis T. hemprichii yang mendominasi. Total kerapatan sebesar 295,62 ind/m2 dan total penutupan yaitu 21,29%. Biomassa secara keseluruhan sebesar 74,42 gbk/m2 dengan biomassa jaringan atas sebesar 35,80 gbk/m2 dan jaringan bawah sebesar 38,62 gbk/m2. Simpanan karbon sebesar 0,23 ton C/ha dengan jaringan atas sebesar 0,10 ton C/ha dan jaringan bawah 0,13 ton C/ha. Total stok karbon mencapai 1,13 ton C dalam luasan padang lamun sebesar 4,903 ha dengan stok karbon jaringan atas bernilai 0,51 ton C dan jaringan bawah sebesar 0,62 ton C. Secara umum lamun jaringan bawah di Pantai Pokemon lebih besar menyimpan karbon.

The Status of Seagrass Health: Supporting Sustainable Small-Scale Fisheries in Misool Marine Protected Area, Raja Ampat, Indonesia

Seagrass plays an important role in aquatic resources, such as to support the sustainable management of small-scale fisheries, ensuring the availability of seagrass stocks for generations of local communities to cultivate in a sustainable manner. The purpose of this study is to provide information on the seagrass health status to support sustainable small-scale fisheries in the South Misool Regional Waters Conservation Areas which is located within the Raja Ampat Marine Protected Area of West Papua. The research was conducted in January 2019 in the Yefgag, Yellu and Harapan Jaya island. A total of ten quadratic transects measuring 1x1 m were laid perpendicularly to the coastline adapted from the seagrass watch method to collect the seagrass data, i.e. the species and the frequency of seagrass found, the dominance and the percentage of seagrass cover. Additional data on fish species were collected by interviewing the local fishermen directly. The relationship between seagrass cover and the number of fish species was analyzed. Th results showed that there were eight species of seagrass found in three observation stations, i.e. Halophila ovalis, Halodule uninervis, Halodule pinifolia, Halophila minor, Syringodium isoetifolium, Cymodocea serrulata, Cymodocea rotundata and Enhalus acoroides. According to the standard criteria for the health status of seagrass beds, the three locations are classified as less rich/less healthy. It because the seagrass coverage was in the range of 30-59%. The relationship between the percentage of seagrass cover and the number of fish species resulted equation of Y = 15,923x + 0,3174 with R2 = 0,763. It means that the percentage of seagrass cover affects the abundance of fish species by 76,3% with the remaining being influenced by other variables, such as water quality.