Summary: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.Keywords: flat oyster; Ostrea edulis; reproductive cycle; biochemical composition; Aegean Sea; Homa Lagoon.Variación estacional de la actividad reproductiva y de la composición bioquímica de ostra plana (Ostrea edulis) en Homa Lagoon, bahía de Izmir, Turquía Resumen: El ciclo reproductivo de la ostra plana, Ostrea edulis Linnaeus, 1758, en Homa Lagoon, Bahía de Izmir, Turquía, fue examinado entre agosto de 2008 y julio de 2009. Las gónadas se analizaron histológicamente para determinar la proporción de sexos y su estado de desarrollo. La proporción de sexos encontrada fue 2.2% hembras, 42.6% machos, 37% hermafroditas y 17.9% inactivos. El contenido de glucógeno mostró considerables variaciones entre agosto y febrero, pero después de estos meses se produjo un aumento gradual. Sin embargo el glucógeno no afectó directamente el ciclo reproductivo. El contenido total de lípidos se correlacionó positivamente con la temperatura e inversamente con la salinidad. Además, este parámetro estuvo influenciado por la actividad reproductiva, que se correlaciona con la fluctuación del índice de condición y del índice gonadal (P<0,05). Sin embargo la relación entre el índice de proteí-na y el índice gonadal fue negativa (P<0,05). Los resultados de este estudio mostraron que la proteína era la principal fuente de energía. El índice de condición varió entre 2.69±0.91 (febrero) y 12.29±1.45 (abril) durante el año. En lo que respecta a la producción de carne, la calidad de las ostras pasó de "fine" to "special", excepto en diciembre y febrero.

This study was carried out to determine the spat efficiency of the smooth scallop Flexopecten glaber (Linnaeus) in surface and bottom water at the Ozbek coast (Türkiye) of the Aegean Sea from September 2017 to August 2018. The environmental parameters (temperature, salinity, chlorophyll-a, and total particulate matter) were also monitored at two depths. The average water temperature at the surface and bottom were 19.79 ± 5.62°C and 19.73 ± 5.24°C, respectively. The lowest chlorophyll-a values were recorded in February (1.12 g l-1) and June (1.23 µg l-1) at the surface and bottom, respectively. The highest chlorophyll-a value was recorded in August at both depths. Throughout the study, the number of F. glaber on the collectors was 270.33 ± 43.54 spat m-2 and 145.66 ± 18.03 spat m-2 were detected on the bottom collectors. A statistically significant difference was found between the growth of the spat attached to the surface and bottom collectors (p < 0.05).

SummaryThe growth and survival of fan mussel (Pinna nobilis, Linnaeus) juveniles, from natural spatfall, were compared in two groups (large and small size) in Karantina Island Izmir, Turkey, between December 2004 and April 2006. Total live weight, shell length, width and thickness of fan mussel were measured monthly during the study period. Small (32 mm) and large (73 mm) size groups of fan mussel individuals reached 140.25±10.46 mm and 154.36±16.12 mm in length and 64.64±17.98 g and 99.74±30.53 g in live weight, respectively. Significant differences were found in increases of shell length and live weight. Environmental parameters such as chlorophyll-a, seawater temperature, salinity, particulate organic matter (POM) and particulate inorganic matter (PIM) were determined during each sampling period. Shell length increase was affected by chlorophyll-a and PIM. However, increases in shell length did not correlate with temperature and POM. Survival rates for small and large groups were 93% and 100%, respectively. Keywords

This research was carried out in Karantina Island to find pearl oyster (Pinctada radiata Leach, 1814) spat collection efficiency of bag and shell collector types. Environmental limits such as temperature, salinity, chlorophyll-a, and total particulate matter (TPM) were monitored during the study period. The abundance of P.radiata spat were found on the bag collector as 11.66±2.08 ind./0.91m 2 at the first time in August. At the same month the highest temperature and salinity were recorded as 27 ºC and 36.5‰, respectively. G2 (group 2/deployed on June 25) performed the highest spat collection for the bag collectors while G4 (deployed on August 29) for the shell collector was more successful during the research. A total of 172±34.39 P. radiata spat were collected during the study. 119±22.60 (69.18%) individuals (ind) were harvested from bag collector and 53±11.78 (30.82%) from shell collector. While the avarege abundance of P. radiata spat were 7.26 ind./m 2 on bag collectors, it was 3.23 ind./m 2 on the shell collectors. A significant difference was determined in the total abundance of P. radiata between the collector groups (p<0.05). The length range of Pinctada spat on the bag collectors was between 4.47-33.9 mm while it was 4.66-18 mm on the shell collectors. Fouling organisms (barnacles, polychaete, bryozoa) and predators (crabs, gastropods) of pearl oyster were also found on the collector groups. Results of the study established that bag collectors were more effective to collect the pearl oyster spat than the shell collectors.

The present study was carried out to determine gonadal stages and quality of pearl oyster meat (Pinctada imbricata radiata, Leach, 1814) in Izmir Bay (Turkey). Pearl oyster samples were collected from the study area at a depth of ~5 m between February 2013 and January 2014. The highest and lowest temperature was measured in July and January as 27°C and 14.2°C, respectively. The maximum chlorophyll a value of 4.640 μg l−1 was calculated in May and the lowest value of 1.009 μg l−1 was recorded in April. Individuals reached their first maturity in April. Spawning activity was observed from June to September and the gonad index (GI) was at the highest level during those months. The development was observed from April to February. The overall female to male ratio was 1.32:1 (p < 0.05) and it did not affect the GI (p > 0.05). There is a strong positive correlation between the GI and temperature (p < 0.05). The highest condition index (CI) was recorded in May as 12.31 ± 0.51, whereas the lowest one in January as 7.37 ± 0.22. As a result, this study revealed that the pearl oyster population in the region is characterized by high reproductive activity, especially during the summer months.