Barrier to Gene Flow of Grey Mangrove Avicennia marina Populations in the Malay Peninsula as Revealed From Nuclear Microsatellites and Chloroplast Haplotypes

Contemporary mangrove forest areas took shape historically and their genetic connectivity depends on sea-faring propagules, subsequent settlement, and persistence in suitable environments. Mangrove species world-wide may experience genetic breaks caused by major land barriers or opposing ocean currents influencing their population genetic structure. For Malay Peninsula, several aquatic species showed strong genetic differentiation between East and West coast regions due to the Sunda shelf flooding since the Last Glacial Maximum. In this study genetic diversity and structure of Avicennia marina populations in Malay Peninsula were assessed using nuclear microsatellite markers and chloroplast sequences. Even though all populations showed identical morphological features of A. marina, three evolutionary significant units were obtained with nuclear and cytoplasmic markers. Avicennia marina along a 586 km stretch of the West coast differed strongly from populations along an 80 km stretch of the East coast featuring chloroplast capture of Avicennia alba in an introgressive A. marina. Over and above this expected East-West division, an intra-regional subdivision was detected among A. marina populations in the narrowest region of the Strait of Malacca. The latter genetic break was supported by an amova, structure, and barrier analysis whereas RST > FST indicated an evolutionary signal of long-lasting divergence. Two different haplotypes along the Western coast showed phylogeographic relationship with either a northern or a putative southern lineage, thereby assuming two Avicennia sources facing each other during Holocene occupation with prolonged separation in the Strait of Malacca. Migrate-n model testing supported a northward unidirectional stepping-stone migration route, although with an unclear directionality at the genetic break position, most likely due to weak oceanic currents. Low levels of genetic diversity and southward connectivity was detected for East coast Avicennia populations. We compared the fine-scale spatial genetic structure (FSGS) of Avicennia populations along the exposed coast in the East vs. the sheltered coast in the West. A majority of transects from both coastlines revealed no within-site kinship-based FSGS, although the remoteness of the open sea is important for Avicennia patches to maintain a neighborhood. The results provide new insights for mangrove researchers and managers for future in-depth ecological-genetic-based species conservation efforts in Malay Peninsula.

South-east Asia outbreaks bring risk and opportunity

Significance In recent months, the region has received jabs manufactured in China, India and Russia -- the key practitioners of ‘vaccine diplomacy’ -- as well as shots made in the West. Meanwhile, some South-east Asian governments have assumed emergency powers to deal with the pandemic. Impacts Cancellation of forums such as the Shangri-La Dialogue, which was due to take place in June, will set back regional security cooperation. Singapore’s ban on shipping crews that have travelled to India will significantly slow trade transit through the Strait of Malacca. ASEAN will try to spur post-pandemic economic recovery in the region through the ASEAN Economic Community.

China-US maritime conflict would do global damage

Significance This is misleading. The real danger arises from China’s intent to supplant the US Navy’s regional dominance and to saturate the region with a Chinese presence in support of Beijing’s territorial claims, and Washington’s resistance to this. Peaceful transit of seaborne trade depends on strategic restraint by both sides and the avoidance of unmanaged escalation. Impacts US freedom of navigation operations are the most likely flashpoint. The United States would probably not need to block the Strait of Malacca; it has more effective ways to blockade Chinese shipping. A conflict resulting in US victory would probably require a permanently elevated US naval presence in the region.

The Occurrence and Distribution of Benthic Foraminifera in Tropical Waters Along the Strait of Malacca

Foraminifera are shelled single-celled protists that are found in all marine environments. Benthic foraminifera either live in sediments or attach to surfaces on the seafloor. Understanding the distribution and ecological response of benthic foraminifera is crucial, as they can indicate past and current ocean conditions. However, the benthic foraminifera distribution along the busy Strait of Malacca, which connects the Indian Ocean (north) to the Java Sea (south), is undersampled. In this study, we collected 24 surface samples from the northern Strait of Malacca to understand the distribution of foraminifera assemblages in shallow tropical waters. A total of 49 species of benthic foraminifera were identified. Calcareous hyaline species dominated the assemblages, with an extremely low occurrence of calcareous porcelaneous species. The common calcareous hyaline taxa were Asterorotalia pulchella, Pseudorotalia schroeteriana, Discorbinella bertheloti, Ammonia tepida, and Heterolepa praecincta. Cluster analysis categorised the foraminiferal assemblages into three major groups. The first cluster (Group A) consisted of a more diverse assemblage of hyaline and agglutinated species that inhabited a mean water depth of 45 m. The second cluster represented a population that inhabited deeper water environments (average water depth of 59 m). Finally, the third cluster (Group C) consisted of a foraminifera assemblage that inhabited shallow coastal environments (average depth of 22 m) with higher organic matter enrichment. The multivariate canonical correspondence analysis (CCA) showed that the foraminiferal assemblages reflected the shallow to deep water transition in the Malacca Strait. Water depth, which defines the depositional environment, had a greater influence on foraminifera distribution here than organic matter and salinity.

Monsoon Islam.

Summarizing how the Ottoman took over the Middle East, the chapters also outlines the boom of the Muslim trade in Europe. Three powerful Muslim empires eventually ringed the Indian Ocean: the Ottomans controlled the Red Sea, the Safavid Dynasty controlled the Persian Gulf route, and the Mughal Empire covered most of India. The chapters also show the flow of the huge Indian Ocean trading network, stating how Muslim communities grew to become trading empires led by powerful sultans who established strong trading by navigating the seas. The terminals of the ocean trade involves: India, Aden, Ormuz, Swahili Coast of Africa, Strait of Malacca and the City of Malacca, Sumatra and Java, Ceylon, and Moluccas. Also, the chapters provide a summary of the ocean trade with Chinese dynasties and other Far East Asian countries.