The pinnotherid crab, Pinnothera obesa Dana, 1852, was originally described on the basis of material from Fiji, but its taxonomic status has long been obscure because the original description and figures are too brief and schematic by modern standards and the types are also lost. Examination of newly collected material from Fiji revealed the presence of two intertidal pinnotherid species assignable to the genus Arcotheres Manning, 1993, one of which is herein identified with Dana's taxon. A neotype is designated for Arcotheres obesus n. comb. in the interest of nomenclatural stability, and a detailed redescription is given. Arcotheres obesus is morphologically similar to A. exiguus (Bürger, 1895) and A. rotundatus (Bürger, 1895), and differentiating characters are discussed. The species is also reported from Peninsular Malaysia. The second species is new to science, here described as Arcotheres ocularius, and is most similar to A. palaensis (Bürger, 1895) and A. arcophilus (Bürger, 1895). The new species is also recorded from Lombok, Indonesia. Arcotheres obesus and A. ocularius n. sp. are associated with bivalve mollusks of the genera Gafrarium spp. (Veneridae) and Anadara spp. (Arcidae), respectively.
Fosil radiolaria berusia Perm Awal telah ditemui daripada batuan silika-rijang di Pos Blau, baratdaya Kelantan,
Semenanjung Malaysia. Sebanyak empat puluh spesies radiolaria tergolong dalam lima belas genera dan tujuh famili
telah dikenal pasti. Fauna radiolaria yang diperoleh termasuklah spesies penunjuk usia seperti Pseudoalbaillella
lomentaria, Ps. sakmarensis, Ps. scalprata scalprata, Ps. scalprata postscalprata dan Ps. scalprata rhombothoracata.
Kesemua radiolaria ini mewakili usia Perm awal merujuk kepada Zon Himpunan Pseudoalbaillella lomentaria
(Sakmarian Awal) dan Zon Himpunan Pseudoalbaillella scalprata m. rhombothoracata (Sakmarian Akhir). Keputusan
ini dapat menambah baik maklumat biostratigrafi radiolaria dan usia batuan bersilika-rijang di kawasan Pos Blau
dan di dalam Zon Sutura Bentong-Raub.
Species invasion is an important cause of global biodiversity decline and is often mediated by shifts in environmental conditions such as climate change. To investigate this relationship, a mechanistic Dynamic Energy Budget model (DEB) approach was used to predict how climate change may affect spread of the invasive mussel Mytilopsis sallei, by predicting variation in the total reproductive output of the mussel under different scenarios. To achieve this, the DEB model was forced with present-day satellite data of sea surface temperature (SST) and chlorophyll-a concentration (Chl-a), and SST under two warming RCP scenarios and decreasing current Chl-a levels, to predict future responses. Under both warming scenarios, the DEB model predicted the reproductive output of M. sallei would enhance range extension of the mussel, especially in regions south of the Yangtze River when future declines in Chl-a were reduced by less than 10%, whereas egg production was inhibited when Chl-a decreased by 20-30%. The decrease in SST in the Yangtze River may, however, be a natural barrier to the northward expansion of M. sallei, with colder temperatures resulting in a strong decrease in egg production. Although the invasion path of M. sallei may be inhibited northwards by the Yangtze River, larger geographic regions south of the Yangtze River run the risk of invasion, with subsequent negative impacts on aquaculture through competition for food with farmed bivalves and damaging aquaculture facilities. Using a DEB model approach to characterise the life history traits of M. sallei, therefore, revealed the importance of food availability and temperature on the reproductive output of this mussel and allowed evaluation of the invasion risk for specific regions. DEB is, therefore, a powerful predictive tool for risk management of already established invasive populations and to identify regions with a high potential invasion risk.
Global human population has increased dramatically over the past 50 years. As a result, marine fisheries and finfish aquaculture have become increasingly unsustainable, driving bivalve aquaculture to become an important food industry for the production of marine animal protein to support the growing market demand for animal protein. It is projected that the rate of bivalve aquaculture expansion will be greatly accelerated in the near future as the human population continues to increase. Although it is generally believed that unfed bivalve aquaculture has less impact on the environment than finfish aquaculture, the rapid expansion of bivalve aquaculture has raised concerns about its potential negative impact, especially on plankton and benthic community. Therefore, there is an urgent need to update the potential effects of bivalve aquaculture on plankton and benthic community. This article reviews the present state of knowledge on environmental issues related to bivalve aquaculture, and discusses potential mitigation measures for the environmental impacts induced by expansion of bivalve aquaculture. This review provides guidance for scientists and farm managers to clarify the current state of research and identify priority research needs for future bivalve aquaculture research. Therefore, specific management strategies can be formulated for the sustainable development and expansion of bivalve aquaculture.
The objective of this commentary is to promote the use of bivalves as biomonitors, which is a part of the continual efforts of the International Mussel Watch. This commentary is an additional discussion on "Bivalve mollusks in metal pollution studies: From bioaccumulation to biomonitoring" by Zuykov et al., published in Chemosphere 93, 201-208. The present discussion can serve as a platform for further insights to provide new thoughts and novel ideas on how to make better use of bivalves in biomonitoring studies. The certainty of better and more extensive applications of mollusks in environmental monitoring in the future is almost confirmed but more studies are urgently needed. With all the reported studies using bivalves as biomonitors of heavy metal pollution, the effectiveness of using Mussel Watch is beyond any reasonable doubts. The challenge is the development of more accurate methodologies for of heavy metal data interpretation, and the precision of the biomonitoring studies using bivalves as biomonitors, whether in coastal or freshwater ecosystems. Lastly, inclusion of human health risk assessment of heavy metals in commercial bivalves would make the research papers of high public interest.
Dissolved oxygen (DO) is an important parameter that affects the biology, physiology, and immunology of aquatic animals. In recent decades, DO levels in the global oceans have sharply decreased, partly due to an increase in atmospheric carbon dioxide, temperature, and anthropogenic nutrient loads. Although there have been many reports on the effects of hypoxia on the survival, growth, behavior, and immunity of bivalves, this information has not been well organized. Therefore, this article provides a comprehensive review of the effects of hypoxia on bivalves. In general, hypoxia negatively impacts the food consumption rate and assimilation efficiency, as well as increasing respiration rates in many bivalves. As a result, it reduces the energy allocation for bivalve growth, shell formation, and reproduction. In severe cases, prolonged exposure to hypoxia can result in mass mortality in bivalves. Moreover, hypoxia also has adverse effects on the immunity and response of bivalves to predators, including decreased burial depths, sensitivity to predators, impairment of byssus production, and negatively impacts on the integrity, strength, and composition of bivalve shells. The tolerance of bivalves to hypoxia largely depends on size and species, with larger bivalves being more susceptible to hypoxia and intertidal species being relatively more tolerant to hypoxia. The information in this article is very useful for elucidating the current research status of hypoxia on bivalves and determining future research directions.
Kajian ini memberi tumpuan terhadap salah satu kategori lakuan bahasa yang diperkenalkan oleh Searle (1969), iaitu lakuan ekspresi. Lakuan ekspresi ialah ujaran-ujaran yang menunjukkan pernyataan psikologi yang memberi gambaran tentang sikap dan perasaan penutur. Analisis kajian ini dilakukan terhadap ujaran-ujaran yang terdapat dalam 40 artikel kritikan Tun Dr. Mahathir dalam isu 1MDB. Melalui kajian ini, sebanyak lima kategori telah dikenal pasti, iaitu lakuan pernyataan, lakuan kritikan, lakuan rujukan, lakuan arahan, dan lakuan ekspresi. Namun demikian, kajian ini hanya memberi tumpuan terhadap lakuan bahasa ekspresi. Analisis mendapati lakuan ekspresi menunjukkan bilangan ujaran paling sedikit berbanding dengan kategori lakuan bahasa yang lain, iaitu sebanyak 20 kekerapan. Lakuan pernyataan mencatatkan kekerapan tertinggi, dengan jumlah kekerapan sebanyak 1302 ujaran, diikuti oleh lakuan kritikan di tempat kedua dengan kekerapan sebanyak 828. Lakuan rujukan dan lakuan arahan masing-masing dengan kekerapan sebanyak 297 dan 128. Hal ini menunjukkan bahawa Tun Dr. Mahathir melakukan kritikan tanpa mengutamakan ekspresi perasaan atau emosi. Sebanyak tujuh sublakuan ekspresi yang ditemui, iaitu lakuan bimbang, hairan, ucapan selamat, kehendak, enggan, minta maaf, dan ucapan terima kasih. Hal ini merumuskan bahawa dalam kritikan, khususnya kritikan bertulis, Tun Dr. Mahathir tidak menunjukkan ekspresi emosi yang berlebihan.
Kajian ini menemui faktor-faktor cabaran kempen anti-merokok dari perspektif petugas kesihatan di Kuantan. Objektif kajian ini adalah untuk menerokai cabaran kempen anti-merokok daripada pandangan petugas kesihatan, kesedaran tentang kewujudan Klinik Berhenti Merokok dan cara untuk menambah baik kempen antimerokok. Kajian ini adalah penting untuk membantu pihak berkuasa Malaysia untuk membangunkan strategi yang lebih baik dalam mempromosikan kempen anti-merokok pada masa akan datang. Persampelan “purposive” digunakan dalam pengumpulan data dan wawancara separa berstruktur telah dilakukan di kalangan lima petugas kesihatan dari tiga Klinik Berhenti Merokok yang terpilih. Kajian ini mendapati petugas kesihatan berpendapat bahawa perokok yang menerima rawatan dari Pusat Kesihatan mempunya pemahaman yang rendah mengenai tatacara piawai (SOP) dalam pemberhentian merokok, komitmen yang rendah dan senang dipengaruhi oleh masyarakat. Petugas kesihatan juga berpendapat tugas pelbagai disiplin menyebabkan tumpuan yang rendah terhadap pesakit yang merokok. Di samping itu, responden merasakan bahawa kewujudan Klinik Berhenti Merokok perlu diperluaskan penghebahannya kepada komuniti. Melalui penemuan ini, beberapa strategi dicadangkan untuk menambah baik pendekatan semasa dalam pengurangan bilangan perokok di Malaysia seperti penambahbaikan penghebahan kepada orang ramai, meningkatkan penguatkuasaan undang-undang serta menyediakan insentif.
Tabiat merokok adalah perilaku yang tidak sihat malah membahayakan bukan sahaja diri sendiri malahan masyarakat sekeliling. Walaupun terdapat banyak kempen anti-merokok telah diperkenalkan oleh kerajaan, namun keberkesanannya masih di tahap rendah. Oleh itu objektif kajian ini adalah untuk meneroka faktor utama kegagalan kempen anti-merokok di Malaysia, meneroka keberkesanan “Klinik Berhenti Merokok” dan menemui penyelesaian terbaik untuk memastikan kempen yang dijalankan berkesan pada masa akan datang. Ini adalah kajian rentas kualitatif di mana temuduga dijalankan di kalangan lima sukarela responden yang terdiri dari perokok dan bekas perokok di kawasan awam dan tiga klinik berhenti merokok yang terpilih. Data dianalisis dengan menggunakan analisis bertema. Kajian ini mendapati beberapa faktor penyumbang dari perspektif perokok dan pihak berkuasa perlu diberi keutamaan untuk penambahbaikan iaitu kurang kreativiti yang minimum dalam menguruskan promosi anti-merokok, kurang kreatitivi dah terhadap kesihatan, permintaan bahan pencetus semangat di tempat kerja, dan dalam pengurusan tekanan yang lemah. Hasil kajian mengesyorkan bahawa kempen bermula di sekolah rendah dan menengah, improvisasi tanda amaran penyakit, meluaskan kawasan promosi, memberi ganjaran semasa kempen dan perokok perlu mengambil inisiatif melibatkan diri dalam program ini. Kerajaan perlu menumpukan perhatian kepada program pencegahan merokok terlebih dahulu, daripada program intervensi berhenti merokok yang mungkin melibatkan kos kewangan yang tinggi.
Penentuan kumpulan bangsa dalam analisis rambut pada kepala adalah satu cabaran yang dihadapi dalam analisis forensik untuk mengenal pasti mangsa, suspek dan tempat kejadian jenayah. Kajian ini bertujuan untuk mengenal pasti perbezaan antara dua kaum terbesar di Malaysia iaitu Melayu dan Cina melalui penelitian ciri-ciri rambut. Ini termasuklah ciri umum rambut, corak kutikel, warna, taburan pigmen kortek dan ciri medula – jenis, ketebalan dan indeks medula. Kajian ini telah dijalankan dengan menggunakan mikroskop cahaya dan terdiri daripada lima langkah iaitu penyediaan sampel, penelitian ciri umum rambut, penyediaan dan penelitian slaid acuan corak sisik kutikel, slaid kortek serta medula. Hasil daripada kajian in mendapati bahawa kebanyakan Melayu mempunyai warna pigmen yang bercoklat gelap manakala Cina mempunyai pigmen coklat cerah. Kami juga mendapati bahawa ketebalan medula boleh juga digunakan untuk membezakan antara Melayu dan Cina di mana nilai purata bagi Melayu dan Cina masing-masing adalah 7.59 ± 1.45 μm dan 9.12 ± 1.85 μm. Nilai purata indeks medula bagi Melayu dan Cina pula adalah 0.17 ± 0.02 μm dan 0.18 ± 0.02 μm masing-masing. Walaupun begitu, ciri-ciri seperti tekstur, ketebalan rambut, corak sisik kutikel, taburan pigmen dan jenis medula pula menunjukkan perbezaan yang tidak ketara antara Melayu dan Cina. Kesimpulannya, kajian ini telah menunjukkan bahawa warna pigmen, ketebalan medula dan indeks medula adalah ciri-ciri penting yang boleh digunakan untuk menentukan bangsa.
Ujian teks bacaan Bahasa Melayu telah dibangunkan untuk menilai prestasi membaca kanak-kanak sekolah rendah.
Seramai 120 pelajar Tahap 1 (purata umur 8.5 ± 0.5 tahun) dan Tahap 2 (purata umur 10.5 ± 0.5 tahun) berpenglihatan
normal telah dipilih secara rawak. Subjek diminta membaca lima teks bacaan secara rawak dengan kuat. Masa selesai
membaca setiap teks bacaan diukur dan sebarang kesalahan menyebut perkataan direkodkan. Purata kelajuan membaca
dan kadar membaca diukur sebagai perkataan per minit (ppm). Kelajuan membaca Tahap 1 adalah 88.81 ± 1.95 {ralat
piawai (RP)} ppm dan kadar membaca pula adalah 87.20 ± 1.98 (RP) ppm. Bagi Tahap 2, kelajuan membaca adalah
108.12 ± 1.66 (RP) ppm manakala kadar membaca adalah 107.22 ± 1.67 (RP) ppm. Kelajuan dan kadar membaca di
antara subjek bagi setiap teks bacaan menunjukkan tiada perbezaan yang signifi kan (p > 0.05) dengan nilai p bagi
kedua-duanya adalah 0.91 manakala bagi tahap 2 pula nilai p adalah 0.57. Perbandingan di antara teks bacaan juga
menunjukkan tiada perbezaan yang signifi kan (p > 0.05). Semua teks bacaan adalah homogen secara statistik maka teks
bacaan yang dibangunkan boleh dipilih secara rawak semasa ujian dan tidak akan memberi kesan kepada penilaian
prestasi membaca di kalangan kanak-kanak sekolah rendah.
Fungsi penglihatan dipengaruhi oleh proses penuaan dan tanpa intervensi yang bersesuaian boleh mengakibatkan kemerosotan tahap penglihatan. Keadaan ini jika berterusan akan mengakibatkan kesukaran melakukan aktiviti kehidupan seharian dan memberi kesan kepada kualiti hidup kepada warga emas. Kajian ini mengkaji kesan gangguan penglihatan terhadap aktiviti harian dan kualiti hidup warga emas. Ukuran yang dilakukan ialah tahap penglihatan jauh menggunakan carta LogMAR untuk menilai gangguan penglihatan. Ujian kualiti hidup dilaksanakan menggunakan soalan kualiti hidup penglihatan terhad (LVQOL) dan ujian keupayaan melakukan aktiviti harian menggunakan indeks Barthel (BI). Dapatan kajian menunjukkan bahawa gangguan fungsi penglihatan bertambah teruk dengan peningkatan umur, begitu juga didapati bahawa BI berkurangan apabila fungsi penglihatan merosot. Skor kualiti hidup LVQOL pula berkurangan bersama-sama kemerosotan tahap penglihatan. Tiga puluh lima peratus warga emas dalam kajian ini memerlukan intervensi optometri dan penglihatan terhad, Kesimpulannya, kemerosotan tahap fungsi penglihatan di kalangan warga emas boleh menyebabkan penurunan keupayaan dalam melakukan aktiviti harian. Di samping itu, akuiti visual yang tidak dibetulkan akan menyebabkan penurunan kualiti hidup warga emas.
Pengecaman senjata api semakin serius dan amat penting di dalam bidang penyiasatan jenayah khususnya untuk tempoh dua dekad ini. Dalam makalah ini, suatu sistem untuk pengecaman senjata api berasaskan tapak kelongsong peluru telah diperkenalkan. Tapak kelongsong peluru adalah satu daripada penunjuk yang amat penting dalam membantu menyelesaikan masalah pengecaman pistol. Peluru yang telah digunakan akan meninggalkan lebih daripada 30 ciri yang amat berharga pada tapak kelongsong bagi membantu pihak tertentu mengecam pistol yang telah diguna. Ciri-ciri tersebut sebagai suatu gabungan membentuk apa yang dikenali sebagai kesan cap jari bagi pistol. Lantaran itu, kajian ini adalah untuk mendapatkan fitur yang sesuai bagi pengecaman senjata api. Terlebih dahulu imej tapak kelongsong peluru ini telah ditemberengkan kepada tiga bahagian, membentuk tiga set imej yang berlainan. Imej-imej ini juga dilakukan prapemprosesan untuk membentuk tiga set imej lagi. Fitur-fitur seterusnya disaring daripada imej asal tapak kelongsong peluru dan imej yang telah melalui prapemprosesan. Dua puluh fitur yang berbeza secara signifikan telah diperoleh dan dikirakan untuk imej-imej asal dan yang telah dilakukan prapemprosesan. Kesemua pemprosesan telah dilakukan menggunakan pengaturcaraan MATLAB. Suatu skim berdasarkan analisis korelasi seterusnya telah diperkenalkan untuk pencarian fitur berdasarkan konsep meminimumkan lewahan data tetapi memastikan ciri-ciri unik tersimpan. Fitur-fitur yang berkorelasi tinggi akan digugurkan pasangannya dan hasilnya tinggal cuma tujuh fitur sahaja. Ketujuh-tujuh fitur ini telah diuji sebagai suatu vektor fitur untuk mengelaskan lima pistol daripada model yang sama menggunakan analisis diskriminan. Hasil pengelasan menunjukkan lebih 80% daripada imej-imej tapak kelongsong peluru itu telah dikelaskan dengan jayanya.
Tumbuhan yang mempunyai kelimpahan tinggi dan boleh mengumpul logam berat dengan banyak boleh digunakan sebagai bio-penunjuk. Tujuan kajian ini adalah untuk melihat kesesuaian Melastoma malabathricum sebagai bio-penunjuk bagi pencemar logam berat dalam tanih bekas lombong. Dalam kajian ini, lima belas sampel Melastoma malabathricum dan tanih telah diambil di tapak bekas lombong besi dan timah Pelepah Kanan Kota Tinggi, Johor. Tiga bahagian tumbuhan (akar, batang, daun) telah dianalisis untuk mengkaji penyerapan kandungan logam berat Cu, Fe dan Mn. Parameter tanih yang dikaji meliputi parameter fizikal dan kimia. Hasil kajian taburan saiz partikel tanih menunjukkan kebanyakan tanih di kawasan kajian adalah jenis berpasir dan bertekstur pasir berlom. Kandungan bahan organik adalah sekitar 1.45 hingga 5.91%. Nilai pH bagi tanih di kawasan kajian adalah sekitar 3.55 hingga 5.68 iaitu bersifat sangat asid ke asid. Kekonduksian elektrik tanih adalah antara 2.14 hingga 2.58 mS/cm. Hasil kajian menunjukkan bahawa, kepekatan logam-logam berat dalam tanih ialah 12070 hingga 65545 mg/kg bagi Fe, 1070.3 hingga 11956.3 mg/kg bagi Mn dan 386.5 hingga 4753.2 mg/kg bagi Cu. Kandungan logam-logam berat dalam bahagian-bahagian tumbuhan pula adalah mengikut turutan seperti berikut; Fe>Mn>Cu. Didapati bahawa spesies tumbuhan Melastoma malabathricurn adalah sesuai sebagai penunjuk biologi logam berat Fe dan Mn.
Formasi Singa yang tersingkap di Kepulauan Langkawi terdiri daripada jujukan batuan sedimen argilit dan boleh dibahagikan kepada empat ahli iaitu Rebak, Kentut, Ular dan Selang. Formasi Singa kaya dengan fosil terutamanya daripada jenis brakiopod, bryozoa dan bivalvia yang boleh ditemui dalam Ahli Rebak dan Ahli Selang. Fosil yang ditemui semasa kajian dijalankan serta fosil yang pernah dilaporkan oleh penyelidik terdahulu telah dibuat penelitian semula untuk menentukan usia Formasi Singa dengan lebih tepat. Himpunan fosil Formasi Singa boleh dibahagikan kepada tiga julat usia, iaitu Visean, Asselian Akhir - Sakmarian Awal dan Sakmarian Akhir. Jujukan berusia Visean diwakili oleh Ahli Rebak, manakala jujukan Asselian Akhir - Sakmarian Awal dan jujukan Sakmarian Akhir diwakili oleh Ahli Selang. Dalam Ahli Ular dan Ahli Kentut tidak ditemui sebarang fosil. Keputusan daripada kertas ini memerlukan satu kajian semula dijalankan terhadap litostratigrafi Formasi Singa.
Since historical times, the inherent human fascination with pearls turned the freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758) into a highly valuable cultural and economic resource. Although pearl harvesting in M. margaritifera is nowadays residual, other human threats have aggravated the species conservation status, especially in Europe. This mussel presents a myriad of rare biological features, e.g. high longevity coupled with low senescence and Doubly Uniparental Inheritance of mitochondrial DNA, for which the underlying molecular mechanisms are poorly known. Here, the first draft genome assembly of M. margaritifera was produced using a combination of Illumina Paired-end and Mate-pair approaches. The genome assembly was 2.4 Gb long, possessing 105,185 scaffolds and a scaffold N50 length of 288,726 bp. The ab initio gene prediction allowed the identification of 35,119 protein-coding genes. This genome represents an essential resource for studying this species' unique biological and evolutionary features and ultimately will help to develop new tools to promote its conservation.
Landfill leachate is a liquid generated due to rainwater percolation through the waste in a landfill or dumping site that may contain high levels of organic matter, both biodegradable and non-biodegradable, which are the major sources of water pollution. Chemical oxygen demand (COD) and Ammoniacal Nitrogen (NH3-N) contents have been relevant indicators of severity and pollution potential of landfill leachate. The reductions of COD and NH3-N were investigated in this study using different combinations of media ratios of green mussel (GM) and zeolite (ZEO). Generally, ZEO is considered as a renowned adsorbent but with a relatively high in cost. In Malaysia, mussel shell is abundantly available as a by-product from the seafood industry, is regarded as waste, and is mostly left at the dumpsite to naturally deteriorate. Its quality and availability make GMs a cost-effective material. In this research study, leachate samples were characterized and found to contain high concentrations of COD and NH3-N. The adsorption process was conducted to find out the best combination media ratio between GM and ZEO. The removing efficiency was determined at different amounts of composite media ratios. The optimal adsorbent mixture ratios between (GM: ZEO) of 1.0:3.0 and 1.5:2.5 were considered as a more efficient technique in removing COD and NH3-N compared to exploiting these adsorbents individually. The optimal extenuation removal reduction was found at an approximately 65% of COD and 78% of NH3-N. The adsorption Isotherm Langmuir model exhibited a better fit with high regression coefficient for COD (R2 = 0.9998) and NH3-N (R2 = 0.9875), respectively. This means that the combination of GM: ZEO adsorption of landfill leachate in this analysis is homogeneous with the monolayer. The mixture of GMs and ZEO was observed to provide an alternative medium for the reduction of COD and NH3-N with comparatively lower cost.Implications: The concentration of organic constituents (COD) and ammoniacal nitrogen in stabilized landfill leachate have significantly strong influences of human health and the environment. The combination of mixing media green mussel and zeolite adsorbent enhancing organic constituents (COD) and ammoniacal nitrogen reduction efficiency from leachate. This would be greatly applicable in future research as well as conventionally minimizing high cost materials like zeolite, thereby lowering the operating cost of leachate treatment.
<b>Background and Objective:</b> Bamboo clam <i>Solen lamarckii</i> is one of the bivalve's species that have important economic value in Indonesian waters. Knowledge of the reproductive biology of a species is essential for proper and sustainable fisheries management. Monthly variations in the gonad maturity level of the clams from the coastal waters of Bengkalis Island Indonesia, were examined. <b>Materials and Methods:</b> Samples of the clam were collected monthly at the intertidal zone during low tide from May to September, 2020. A total of 239 specimens of which 116 females and 123 males were examined. Reproductive aspects observed in this study included sex ratio, gonadosomatic index, monthly gonadal maturity level and female fecundity. Mature female or near spawning phases were used for fecundity estimation. The sex ratios were analysed using a Chi-quadrat-Test, whereas to determine differences in fecundity between female individuals tested by Analysis of Variance. <b>Results:</b> Based on the gonadosomatic index (GSI) and histological observation of both sexes's gonads, it can be concluded that early spawning occurred in August and the peak seemed to take place during October-November. The sex ratios were analysed using a Chi-quadrat-Test which was not different from parity. Gonad maturation time between males and females indicates synchrony and no hermaphrodites were observed in the collection. Females shell length range of 75.5 to 89.3 mm produced 4.63×103-7.43×103 eggs ind-1 female (N = 10). Females with a shell length between 75.5 and 89.3 mm had varying fecundities, but analysis of variance showed no significant difference (Sig>0.05). <b>Conclusion:</b> Based on the gonadosomatic index (GSI) and histological analysis, <i>S. lamarckii</i> in Bengkalis waters spawned in August. Males and females showed spawning synchrony.
Two Unionida (freshwater mussel) families are present in the Northern Hemisphere; the Margaritiferidae, representing the most threatened of unionid families, and the Unionidae, which include several genera of unresolved taxonomic placement. The recent reassignment of the poorly studied Lamprotula rochechouartii from the Unionidae to the Margaritiferidae motivated a new search for other potential species of margaritiferids from members of Gibbosula and Lamprotula. Based on molecular and morphological analyses conducted on newly collected specimens from Vietnam, we here assign Gibbosula crassa to the Margaritiferidae. Additionally, we reanalyzed all diagnostic characteristics of the Margaritiferidae and examined museum specimens of Lamprotula and Gibbosula. As a result, two additional species are also moved to the Margaritiferidae, i.e. Gibbosula confragosa and Gibbosula polysticta. We performed a robust five marker phylogeny with all available margaritiferid species and discuss the taxonomy within the family. The present phylogeny reveals the division of Margaritiferidae into four ancient clades with distinct morphological, biogeographical and ecological characteristics that justify the division of the Margaritiferidae into two subfamilies (Gibbosulinae and Margaritiferinae) and four genera (Gibbosula, Cumberlandia, Margaritifera, and Pseudunio). The systematics of the Margaritiferidae family is re-defined as well as their distribution, potential origin and main biogeographic patterns.
The morphology and 12 shell morphometric features proportionate to shell length were analysed between local hard clam; Meretrix lyrata, M. meretrix and M. lusoria from Sarawak, Malaysia. Meretrix spp. was observed to comprise a unique feature of a pallial sinus scar for each species. Analysis of variance revealed significant differences among Meretrix spp. using proportion ratios of SL for SW; LL; AL; LCT; AW; PW and PS (p<0.05). Cluster analysis among morphometric features of M. lyrata, M. meretrix and M. lusoria were discriminated at 98.5% similarities and supported by the principal component analysis. The present study suggests that pallial sinus scar shape, together with interior and exterior morphometric features, were suitable as identification keys for Meretrix spp. Hence, the present study emphasizes on the application of interior, rather than exterior morphology and morphometric features in hard clam identification before further investigation can be performed through genetic identification means.