Comparison of Isochrysis galbana and Chlorella sp. microalgae on growth and survival rate of European flat oyster (Ostrea edulis, Linnaeus 1758) larvae

Influence of microalgal feeding with Isochrysis galbana and Chlorella sp. on the growth and survival rate of larvae of European flat oyster, Ostrea edulis, was investigated. Larvae were reared with four food regimes: I. galbana, Chlorella sp., mixture of both and unfed for 16 days. After 16 days, it was observed that the larvae reached the umbo stage with a mean size in length 220±4.12 µm and 219±5.76 µm (initial length, 159 µm) (P > 0.05). Larvae were fed on I. galbana and mixture diet. At this stage, survival rate was 30% and 24%, respectively (P > 0.05). Growth and survival rates for the feeding regimes were significantly higher than the Chlorella sp. and unfed groups (P < 0.05)

Preliminary spat settlement of fan mussel Pinna nobilis linnaeus 1758 on a mesh bag collector in Karantina Island (eastern aegean sea, Turkey)

The study regarding the annual pattern of Pinna nobilis settlement in Karantina Island (Izmir Bay, Turkey) was conducted using artificial polyethylene-mesh bag collectors (onion bag). The samples were collected by a SCUBA diver at intervals of 4 weeks, also replacing the collectors during 12 months at 8-m depth. In addition, environmental parameters, such as temperature, salinity, chlorophyll-a, particulate organic matter and particulate inorganic matter in water column, were monthly measured. Fifteen bivalve species were recorded, and among these, Ostrea edulis, Pinctada radiata, Chlamys varia, Chlamys glabra Modiolus barbatus, Mytilus galloprovincialis, Area noae, and Anadara inaequivalvis have a commercial value. P. nobilis represented 0.84% of total amount. Settlement was observed only in August (122 individuals/0.4 m 2) and spat data showed significant variations between outside (8%) and inside (92%) of each mesh bag collector but also the deployed time (P&lt;0.05). Length of spat ranged between 0.3 and 15.3 mm. These results showed that reproduction period of fan mussel was during summer months in Izmir Bay, and fan mussel was collected especially in August from natural area. © by PSP

Comparison of gonadal development of carpet shell clam (tapes decussatus, linnaeus 1758) in inside and outside of çakalburnu lagoon, izmir bay

A study of the gametogenic cycle of the carpet shell clam, Tapes decussatus, was undertaken in the inside and outside of Çakalburnu Lagoon, Izmir Bay, Aegean Sea from August 2006 to July 2007. Histological evidence showed that gametogenesis of T. decussatus continued throughout the year and six stages of gonadal development were observed in two sites. In males, except for November in inside and December and January in outside of lagoon ripeness (Stage III) clam was observed during a year. In addition, spawning (Stage IV or Stage V) continued throughout the year in inside and except for February and March in outside. In females, ripe clam (Stage III) was observed similar time with male in two sites. It was observed that Stage 0 (inactive or resting) was only 3.0-5.0% ratio in November, December and January in two sites. The male/female sex ratio for inside and outside of lagoon was 1:1.06 and 1:1.10, respectively (P>0.05). © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey

Seasonal variation in reproductive activity and biochemical composition of flat oyster (Ostrea edulis) in the Homa Lagoon, Izmir Bay, Turkey [Variación estacional de la actividad reproductiva y de la composición bioquímica de ostra plana (Ostrea edulis) en Homa Lagoon, bahía de Izmir, Turquía]

The reproductive cycle of the flat oyster, Ostrea edulis Linnaeus, 1758, in Homa Lagoon, Izmir Bay, Turkey was examined from August 2008 to July 2009. Gonad samples were analysed histologically in order to determine the sex ratio and gonad development stage. Overall, the sex ratio was recorded as 2.2% female, 42.6% male, 37% hermaphrodite and 17.9% inactive. Glycogen content showed considerable variations between August and February, but decreased gradually thereafter. However, glycogen did not directly affect the reproductive cycle. Total lipid content was positively correlated with temperature and inversely correlated with salinity. In addition, this parameter was influenced by the reproductive activity, which is correlated with the fluctuation of the condition index and gonad index (P<0.05). However, the relationship between the protein index and the gonad index was negative (P<0.05). The results of this study showed that protein was the major energy resource. The condition index varied between 2.69±0.91 (February) and 12.29±1.45 (April) during the year. With respect to meat yield, oyster quality changed from “fine” to “special”, except in December and February. © 2015 CSIC