Temporal and Spatial Distribution of Zooplankton Inhabiting Sandy and Muddy Shore Habitats at Jazan Coastal Area

Few studies were made about zooplankton distribution in Jazan coastal area. The present study dealt with the identification of zooplankton at the sandy shore (AlSalwa coast) and mangrove muddy shore (Turfa peninsula) at the Almarjan coast. Species richness and population density at different seasons were determined for both study areas between May 2016-April 2017. Conductivity, pH, water temperature, and salinity were measured. The relationship between water characters and the seasonal abundance of zooplankton seasons was examined through regression analysis. Ciliates, Rotifers, Nauplius larva, Gammarus sp., Veliger larva, Nematodes, Planaria, Copepods, and Kinorhyncha were recorded for both study areas. The highest species richness and population density were recorded during the summer season for Almarjan sandy shore and Turfa peninsula mangrove. Ciliates were the most abundant zooplankton on the sandy shore, while Kinorhyncha was the least abundant. The zooplankton Nematode was the most abundant at the Turfa Peninsula mangrove, whereas Gnathostomulida was the least abundant. Conductivity, salinity, and water temperature showed a significant regression relationship (P<0.05) with zooplankton abundance. Data was discussed to highlight the role of zooplankton abundance in the mangrove and sandy shore ecosystem.

Effect of WAF crude oil exposure to larvae development of the black-scar oyster Crasosstrea iredalei

Oil spills potentially effect exposed organisms at various stage of life. This work aimed to access health risk of crude oil to larva development of a sessile organism the Black scar oyster Crassostrea iredalei by using water accommodate fraction (WAF) of crude oil. Male and female gametes was collect and fertilized to obtained larvae at cleavage stage. The larvae were then incubate in various concentrations of WAF (0, 6.25, 12.5, 25, 50, and 100 %). After 24 hour of exposure, normal D-shaped veliger larva (D-larva) was observe. The result showed that WAF crude oil affected the development and the successful of D-larva development. Severity of WAF effect was increasing with dosages of exposure. The abnormal larva developments were increasing in the high concentrations. The information obtaining from current work is important for health risk assessment of crude oil contamination incident in marine ecosystem. This study will also contribute valuable knowledge needed for aquaculture to know effect of crude oil spill to oyster farming area.

Study on the Development of Spiral babylonia snail Tiger Snail Juvenil Eggs (Babylonia spirata Linnaeus, 1758) in the Laboratory

Several marine gastropods are known to have high economic value, one of which is the Spiral babylonia snail. They commonly exploited for meat, shell, or operculum. Tiger snail meat is commonly exported and consumed by fishermen. Its shell is used as a material for industrial lime and for omamen. Operculum is commonly used as a medicinal and perfume ingredient). However, the recent production has decreased due to the limited information of seasonal catch. One way to overcome these obstacles is through culture activities. The provision of seeds is an important link in the culture system, therefore the study of the spawning process and larval development is an important requirement for the development of larval rearing techniques. This study aims to determine the development process of juvenil eggs and the survival rate of tiger snails reared in the laboratory.. The study was conducted at the Laboratory of Marine Farm Subdivision in Kudus, Pt Pura Bahari, Jepara Regency. This sudy used experimental method with descriptive data analysis. Adult tiger snails were caught from Bunga waters, Demak. The snails were reared in a rectangular tube filled with 15 cm filtered sea water and 5 cm of sand. Egg capsules were reared in a 4 liters circular tube with continuous aeration. The hatched larvae were reared in a 300 liters circular tube filled with filtered seawater, continuously aerated and fed with Chlorella plankton . Our result showed that tiger snails spawn naturally and produce egg capsules. The incubation period for the capsule is 6 days, then develop into veliger larva for 12 days. The veliger larvae metamorphosed,and become juvenil. The lowest survival rate observed in the veliger stage. The survival rate of the egg and the intracapsular trochopore stages were quite high (tube I = 98.413%; tube II = 98.238%; tube III = 90.476%), then the lowest was in the veliger stage (tube I = 3,468%; tube II = 2.603%; tube III = 2,598%) and the juvenil stage is quite high compared to the previous phase (tube I = 3,413%; tube II = 2,479%; tube III = 2,351%).

Redescription of Larval Development in Cultured Pearl Oyster Pinctada maxima

Larval development plays a major role in efficient pearl culture. The cultured larvae will be later used for recipient and donor oysters in cultured pearl production. Larval developmental stage of silver lip pearl oyster Pinctada maxima has been reported by several studies. Those studies used female and male oyster parents directly taken from natural habitat.This study aimed to redescribe larval development of P. maxima from commercial pearl oyster culture farm in Indonesia. Larval development of this species whose parents are originated from selected groups in the pearl culture farm has not been reported yet, thus it is necessary to be described. This species undergoes specific larval developmental stage. The larvae were observed under microscope, and then the average shell length (SL) and shell height (SH) were measured. D-shaped veliger larva (77.4±0.3 µm SL; 65.4±1.1 µm SH) appeared 20 h after fertilization. Tenday-old larva (156.2±2.8 µm SL; 149.5±5.6 µm SH) had developed umbo region so it was called umbonal larva. Umbonal larva then developed further into plantigrade larva (411.3±9.8 µm SL; 380.5±6.9 µm SH) in 25 days after fertilization. Developmental stage and larval sizein P. maxima is similar with those observed in P. fucata and P. margaritifera. Keywords: growth, larva, plantigrade, shell, umbo, veliger

Commensalism of a Bivalve, Peregrinamor Ohshimai, With a Thalassinidean Burrowing Shrimp, Upogebia Major

Ecological, behavioural and anatomical observations of a commensal bivalve, Peregrinamor ohshimai (Mollusca: Galeommatoidea), were carried out in a tidal mudflat in the Seto Inland Sea, Japan. The bivalve attached specifically to the longitudinal groove of the ventral side of the cephalothorax of thalassinidean burrowing shrimps, Upogebia major and Lf. narutensis (Crustacea: Decapoda), singly, dorso-ventrally and longitudinally, using its byssus, with its anterior part towards the head of the host. The mantle of the commensal bivalve has wide anterior (branchio-pedal) and narrow posterior (exhalant) apertures. In the living organism, the extended anterior edges of the mantle protrude from the shell and are inserted into the host's filtering basket, which is formed by the setal rows of the first two pairs of pereiopods and utilized for intercepting suspended matter. By beating its pleopods in a U-shaped burrow, the filter-feeding Upogebia shrimp creates water currents, which are also utilized by the commensal bivalve for filter-feeding. The shell length of the commensal bivalve was in proportion to the host's carapace length. This suggests that the veliger larva attaches to a young host and grows, thus maintaining the host-commensal morphological matching. The bivalve is a hermaphrodite and individuals of >8–5 mm in shell length were already producing eggs. Anatomical observations suggest that P. ohshimai is most closely related to the Montacutidae in Galeommatoidea.

Size-related variation in the sensitivity of the mussel, Mytilus edulis, to copper

Juvenile mussels (Mytilus edulis, Mollusca: Bivalvia) were subjected to a simple assay to investigate the pattern and timing of the shift from high copper resistance of the veliger larva to the lower resistance of the adult. The level of resistance found in veligers persists in mussels of 1 mm shell length (400 ppb Cu; LT50, 12.5 d) while the lower adult level of resistance is reached at a shell length of 5 mm (400 ppb Cu; LT50 2.8–5.3 d). Resistance declines gradually, being significantly correlated with shell length (P<0.02) such that size differences explain 88% of the variation in copper resistance among juvenile mussels.