有毒渦鞭毛藻 Alexandrium catenella および Gymnodinium catenatum における PSP の産生とそれらを給餌されたアサリの毒化様式に関する研究

長崎大学学位論文 学位記番号:博(生)乙第8号 学位授与年月日:平成19年2月21日Nagasaki University (長崎大学)論文博

Morphology and Stomach Content Analysis of Green Rough-Backed Pufferfish, Lagocephalus lunaris from Kuching, Sarawak

A total of 101 individuals of green rough-backed pufferfish, Lagocephalus lunaris were collected at two sampling sites and were assessed for their morphological characteristics and diet by stomach content analysis. The physical characteristics were observed and body weight (BW), total length (TL), standard length (SL) and number of fins also had been measured. The results showed that the physical body measurement in all individuals were almost similar in their range of size (TL: 8.6 ± 0.3 cm; SL: 7.0 ± 0.2 cm; BW: 14.3 ± 1.5 g) and most individual had same distribution of spines at the dorsal part which extended to dorsal fin. The numbers of caudal, dorsal, pectoral and anal fin rays were counted, and ranged from 5 to 12, 7 to 11, 9 to 12 and 7 to 17, respectively. Analysis of the diet composition showed the fish is carnivores which prey on crabs, prawns, small fish and squids. The percent index of relative importance analysis was used to determine the important prey item of this species. From the results, crabs was identified as most important prey in Site 1 and Site 2, with value of (47.5, 55.6 %), and followed by prawns (36.3, 38.2 %), fish (5.6, 11.2 %), squids (0.7, 2.9 %) and bivalves (0.1, 1.7 %). To our knowledge, this is the first report to record the morphological characteristics and to determine stomach content of L. lunaris from Sarawak waters

Toxicity Assessment of Cyanobacterial Strains Using Brine Shrimp and Mouse Bioassay

Cyanobacterial samples were collected from aquaculture ponds in Sarawak and Sabah. Strain belonging to Microcystis sp. were isolated and maintained in laboratory cultures. Mass cultures were performed and the cells were harvested in their late exponential phase of growth. Each strain was lypholized and extracted using methanol to get the crude extract. Five different concentrations were tested in brine shrimp assay and the extracts were toxic with a LC50 of less than 50 μg/ml within 24 hrs observation. Mouse bioassay was done via intraperitoneal injection of 1.0 ml of a lysate of toxin extract into ±20 g white mice. The preliminary screening of toxin extracts using brine shrimp and mouse bioassay indicates that the strains are potentially toxin producer species and subjected to further examine using high performance liquid chromatography method

Aliphatic Hydrocarbons In Surface Sediments From South China Sea Off Kuching Division, Sarawak

Eighteen surface sediment samples collected from South China Sea off Kuching Division, Sarawak were analyzed for aliphatic hydrocarbons. These hydrocarbons were recovered from sediment by Soxhlet extraction method and then analyzed using gas chromatography equipped with mass spectrometer (GC/MS). Total concentrations of aliphatic hydrocarbons in surface sediments from South China Sea off Kuching division are ranged from 35.6 ug/g to 1466.1 ug/g dry weights. The sediments collected from Bako Bay, Kuching showed high concentrations of total aliphatic hydrocarbons. Several molecular indices were used to predict the predominant sources of hydrocarbons. Carbon preference index (CPI) value revealed widespread anthropogenic input in this study area (CPI= 0 to 4.1). The ratio of C31/C19and C29/C31indicated that major input of aliphatic hydrocarbon mostly transfer by lateral input to the marine environment than atmospheric movements. Generally, the concentrations of aliphatic hydrocarbons in sediment from South China Sea off Kuching division are generally higher compare to other area in the world

The status of yellow pufferfish, Xenopterus naritus (Richardson, 1848) from the Southwest coast of Sarawak, Northwestern Borneo, Malaysia

The yellow pufferfish, Xenopterus naritus is a commercially important target species for the artisanal fishermen in Sarawak. There is concern over its conservation and population structure. Therefore we provided a baseline data on size distribution, sex ratio, length-weight relationship and condition factor of 65 specimens of this species, landed from May 2015 to July 2014 from eight distinct locations (Kabong, Sematan, Buntal, Paloh, Sadong Jaya, Pusa, Sebangan and Spaoh) representing the Southwest coast of Sarawak waters. Specimens were obtained by hiring local fishermen to catch them and purchasing from fish markets. Generally, males were significantly smaller and lighter than females. Total length, standard length and body weight of combined sexes of X. naritus was found in the size range of 10.6–29.5 cm, 8.8–26.7 cm and 20.16–646.76 g respectively. Male to female sex ratio was 1M:2.8F. Length–weight relationships of X. naritus exhibited positive growth allometry in males but negative growth allometry in females, whereas positive growth allometry in combined sexes. Condition factor in overall specimens was 2.279±0.434 which reflects the healthiness of X. naritus and favorable environmental conditions in Sarawak waters. Findings of the present study contribute as important baseline data for future studies not only on the fisheries and stock management of X. naritus but also on conservation and aquaculture development of this commercially important species

CE (Cost Effective) Crab House

At present, Mud Crab demand is high and Sarawak being blessed with many rivers and potentially fulfil the demand of mud crab locally. The mud crab that is from Santubong and Sematan are known to be in one of the top quality produce. In Sarawak, there are some locals who deal with mud crab farming and most of them doing a conventional mud crab farming such as pond farming. Hence, the CE-Crab House is innovated to help the lower income community to generate their income. The CE-Crab House is a cost effective crab fattening house that is newly improved design for the purpose of high volume production. The CE-Crab House is able to fatten mud crabs using a DIY design, low cost with a systematic monitoring process

The first reported artificial propagation of yellow puffer, Xenopterus naritus (Richardson, 1848) from Sarawak, Northwestern Borneo

Pufferfish from family Tetraodontidae consists of 28 genera and 199 species worldwide, distributed in tropical and subtropical areas of Atlantic, Indian and Pacific Ocean (Nelson 1994). Some pufferfish species has become targeted species for aquaculture industry in various country including Japan, China, South Korea and Mexico. Reproductive biology of these valuable aquaculture species including tawny puffer (Shi, Zhang, Liu & Zang 2011), obscure puffer (Won, Kim & Park 2009; Kim, Dahms & Han 2013), tiger puffer (Wu, Tang, Yuan, Shi, Shakeela & Zhang 2015) and bullseye puffer (Sanchez, Alvarez-Lajonchere, Abdo De La Parra & Garcia 2008; Abdo-de La Parra, Garc�ıa- Ortega, Mart�ınez-Rodr�ıguez, Gonz�alez-Rodr�ıguez, Velasco-Blanco, Hern�andez & Duncan 2010) has been studied extensively for optimizing the production in aquaculture. In Sarawak coastal waters, there are 13 species of six genera of marine pufferfish species that has been reported (Vidthayanon 1998). Most of these species are non-target species in capture fisheries and has been considered as trash fish. However, there is one native pufferfish species that is widely consumed by the locals which is yellow puffer, X. naritus. Despite its lethality (Mohd Nor Azman, Samsur & Othman 2014), this species is considered as highly sought after delicacy due to the tenderness of their meat according to the locals

Accumulation and depuration profiles of PSP toxins in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Alexandrium catenella

A toxic dinoflagellate responsible for paralytic shellfish poisoning (PSP), Alexandrium catenella (Ac) was fed to the short-necked clam Tapes japonica, and the accumulation and depuration profiles of PSP toxins were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested more than 99% of the Ac cells (4_107 cells) supplied once at the beginning of experiment, and accumulated a maximal amount of toxin (185 nmol/10 clams) after 12 h. The rate of toxin accumulation at that time was 23%, which rapidly decreased thereafter. Composition of the PSP toxin accumulated in the clams obviously different from that of Ac even 0.5 h after the cell supply, the proportion of C1+2 being much higher than in Ac, although the reason remains to be elucidated. In contrast, a higher ratio of gonyautoxin (GTX)1+4 than in Ac was detected in the toxin profiles of clam excrements. The variation in toxin composition derived presumably from the transformation of toxin analogues in clams was observed from 0.5 h, such as reversal of the ratio of C1 to C2, and appearance of carbamate (saxitoxin (STX), neoSTX and GTX2, 3) and decarbamoyl (dc) derivatives (dcSTX and dcGTX2, 3), which were undetectable in Ac cells. The total amount of toxin distributed over Ac cells, clams and their excrements gradually declined, and only 1% of supplied toxin was detected at the end of experiment