Assessment of Genetic Variation in COI Gene of Horseshoe Crab (Tachypleus Gigas) Population Along the Coast of the Bay of Bengal in Odisha, India

Horseshoe crab (Tachypleus gigas) is an archaic group of marine creature which plays a vital role in the saline ecosystem. Many researchers emphasize and enhance the knowledge about the horseshoe crab's basic biology, morphology, and ecology, whereas very little information is available about its population genetics. We attempted to develop a baseline database about the ecology, phylogeography, and genetic variation among the horseshoe crab population from Odisha, India. We collected 152 samples of horseshoe crab from the coastal area of the Bay of Bengal. The generated Cytochrome C Oxidase Subunit I gene (COI) sequences of T. gigas were compared with the sequences of T. gigas obtained from GenBank. The GenBank sequences were of two populations from South China and Malaysia. A total of 26 unique haplotypes were observed in three populations of T. gigas. Pairwise F-statistic distance (FST) between South China-India was 0.708; Malaysia-India was 0.608, and South China-Malaysia was 0.136. It indicated that the South China population was closely related to the Malaysian population and the Indian population was appeared to be genetically distinct from the other two populations. It signifies the ecological importance of the Indian population. Furthermore, the migrant per generation (Nm) was 0.16, which indicated a low gene flow among T. gigas populations. The haplotype diversity (Hd) and nucleotide diversity (π) were 0.58826 and 0.00476, respectively. This study would help lay future strategy and conservation of horseshoe crab across the Bay of Bengal.

Tri-Spine Horseshoe Crab Aquaculture, Ranching and Stock Enhancement: Perspectives and Challenges

As a well-known example of “living fossil,” horseshoe crabs are ecologically significant macroinvertebrates in coastal and estuarine ecosystems. The tri-spine horseshoe crab, Tachypleus tridentatus, has been widely utilized for Tachypleus amebocyte lysate production and food consumption since the 1980s, which led to considerable population declines along the west coast of the Pacific Ocean. The declining horseshoe crab population is expected to have ecological and social impacts. Stock enhancement through captive rearing of juveniles is cited as an important alternative to repopulate the native T. tridentatus, which in turn supports sustainable resource utilization and research activities. The hatchery production techniques for this species have gradually developed following the mass culture efforts in Japan since the late 1980s. However, the previous studies have primarily concerned the feed types and husbandry conditions to maximize the growth and survival of the juveniles. Little is known about the practicability and effectiveness of releasing large numbers of hatchery-bred individuals through releasing programs. In this review, we (1) summarize the available captive breeding and rearing techniques, (2) discuss the release strategies that could potentially improve the survival of released juveniles, and (3) identify the future opportunities and challenges in establishing technical frameworks to support responsible stock enhancement programs for T. tridentatus. The information should benefit future horseshoe crab fisheries management efforts in the attempt to restore the severely depleted populations.

KEPASTIAN TAKSONOMI DAN SEBARAN BELANGKAS Tachypleus tridentatus Leach 1819 DI PERAIRAN BALIKPAPAN TIMUR

ABSTRAKBelangkas Tachypleus tridentatus adalah salah satu hewan bentik laut yang menghuni perairan pesisir Balikpapan Timur. Informasi tentang populasi belangkas di lokasi masih terbatas, dan IUCN secara luas mengklasifikasikannya dalam kategori data deficient. Penelitian ini bertujuan untuk menjelaskan kepastian taksonomi secara genetik dan sebaran T. tridentatus di perairan pesisir Balikpapan Timur. Belangkas diperoleh menggunakan alat tangkap nelayan setempat (dogol - sejenis pukat dan jaring insang) di daerah Teritip dan Manggar, masing-masing pada jarak sekitar 1 dan 2 mil dari garis pantai. Pengambilan belangkas dilakukan mulai Januari hingga Maret 2018 pada fase bulan berbeda. Belangkas yang tertangkap dihitung dan dicatat lokasi penangkapannya serta diamati karakter morfologinya untuk analisis sebaran dan sebagian belangkas diambil darahnya untuk analisis kepastian taksonomi dengan menggunakan penanda gen CO1. Karakter morfologi utama berupa telson yang berbentuk segitiga dan duri kecil yang banyak terdapat pada ophisthosoma, secara genetis menunjukkan bahwa jenis yang dikumpulkan adalah T. tridentatus. Sebagian besar belangkas yang ditemukan di lokasi penelitian adalah belangkas dewasa yang menyebar secara acak, dengan lebar prosoma berkisar antara 22,5 hingga 30,5 cm untuk jantan dan 28,5 hingga 37,5 cm untuk betina. Jumlah belangkas terbanyak ditemukan di daerah Teritip dan berdasarkan fase bulan terjadi pada kuarter ketiga. Penelitian ini menguatkan kepastian adanya jenis T. tridentatus di lokasi penelitian dengan ciri yang mudah dikenali serta konektivitas pergerakan T. tridentatus ke lokasi lain di sekitar perairan Balikpapan Timur. ABSTRACTThe tri-spine horseshoe crab Tachypleus tridentatus is one of marine benthic animals inhabiting East Balikpapan coastal waters. Information on horseshoe crab population in the location is still limited and IUCN broadly classifies the crab in deficient data category. This study was aimed at elucidating the taxonomic certainty genetically and distribution of T. tridentatus in coastal waters of East Balikpapan. The crabs were collected by local gear of fisherman (dogol – a trawl like fishing-gear and gill net) in the Teritip and Manggar areas, each at a distance of 1 and 2 miles from coastline. Collecting takes place between January to March 2018 at different moon phases, location, number and morphological characters of the crabs was recorded and blood was taken from some individuals. Primary morphological characters in the form of triangular shape of telson and abundant tiny spines on ophisthosoma, genetically ascertained that the collected crab is T. tridentatus. Most of these crabs found was adult and randomly dispersed; with the width of prosoma ranged from 22.5 to 30.5 cm for males and 28.5 to 37.5 cm for females. The highest number of crab was found in the Teritip area and in the third quarter moon phase. This study reinforce the certainty of T. tridentatus in the study site with easily recognized morphological characters and the connectivity with other sites around Eastern Balikpapan waters.

POPULATION STRUCTURE AND MORPHOMETRY OF HORSESHOE CRAB Carcinoscorpius rotundicauda, Latreille 1802 IN KAMPUNG GISI COASTAL AREA OF BINTAN BAY OF RIAU ISLANDS PROVINCE

Horseshoe crab, Carcinoscorpius rotundicauda is frequently found in the coastal zone of Bintan Bay of Riau Islands Province. The study was conducted from August to September 2016 in coastal area of Kampung Gisi, Bintan bay. The aims of the study were to analyse the population structure and morphometric characters of horseshoe crab and its relation to the coastal environmental characteristics. Sampling of horseshoe crab was taken using belt transect method, and coastal environmental parameters were measured in-situ. The results show that b values of length-weight relationship were found to be 3.3 (male) and 2.6 (female) respectively. Furthermore, the growth pattern of males were positive allometric, and females were negative allometric. Horseshoe crab are closely related to sandy mudflats sediment, brackish water salinity and mangrove habitat distribution. Keywords: horseshoe crab, population structure, morphometry, environmental characteristics, Bintan Bay

POPULATION STRUCTURE AND MORPHOMETRY OF HORSESHOE CRAB Carcinoscorpius rotundicauda, Latreille 1802 IN KAMPUNG GISI COASTAL AREA OF BINTAN BAY OF RIAU ISLANDS PROVINCE

<p><em>Horseshoe crab, <span style="text-decoration: underline;">Carcinoscorpius</span> <span style="text-decoration: underline;">rotundicauda</span> is frequently found in the coastal zone of Bintan Bay of Riau Islands Province. The study was conducted from August to September 2016 in coastal area of Kampung Gisi, Bintan bay. The aims of the study were to analyse the population structure and morphometric characters of horseshoe crab and its relation to the coastal environmental characteristics. Sampling of horseshoe crab was taken using belt transect method, and coastal environmental parameters were measured in-situ. The results show that b values of length-weight relationship were found to be 3.3 (male) and 2.6 (female) respectively. Furthermore, the growth pattern of males were positive allometric, and females were negative allometric. Horseshoe crab are closely related to sandy mudflats sediment, brackish water salinity and mangrove habitat distribution. </em></p><p> </p><p><strong>Keywords</strong>: <em>horseshoe crab, population structure, morphometry, environmental</em> <em>characteristics, Bintan </em><em>B</em><em>ay</em></p>

The consequences of climate change at an avian influenza ‘hotspot’

Avian influenza viruses (AIVs) pose significant danger to human health. A key step in managing this threat is understanding the maintenance of AIVs in wild birds, their natural reservoir. Ruddy turnstones ( Arenaria interpres ) are an atypical bird species in this regard, annually experiencing high AIV prevalence in only one location—Delaware Bay, USA, during their spring migration. While there, they congregate on beaches, attracted by the super-abundance of horseshoe crab eggs. A relationship between ruddy turnstone and horseshoe crab ( Limulus polyphemus ) population sizes has been established, with a declining horseshoe crab population linked to a corresponding drop in ruddy turnstone population sizes. The effect of this interaction on AIV prevalence in ruddy turnstones has also been addressed. Here, we employ a transmission model to investigate how the interaction between these two species is likely to be altered by climate change. We explore the consequences of this modified interaction on both ruddy turnstone population size and AIV prevalence and show that, if climate change leads to a large enough mismatch in species phenology, AIV prevalence in ruddy turnstones will increase even as their population size decreases.