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.

The population of Pinna nobilis (Linnaeus, 1758) has been severely damaged, especially by the effect of the disease, in addition to the causes such as fishing activities, overexploitation, environmental pollution, habitat degradation, tourism, and human impacts. Particularly, Haplosporidium pinnae caused gigantic destruction in the P. nobilis population. Accordingly, the present study aimed to determine the current status of the P. nobilis populations in the Çanakkale Strait. Samplings were carried out between July and August 2020 at 9 different stations in the Çanakkale Strait. The results revealed that mass mortality was observed at the two stations (Abide Beach and Kumkale Village Beach) located near the Aegean Sea. On the other hand, it has been determined that the lowest mortality rate (9.62%) has been found at Ilgardere station. Juvenile individuals have been observed in healthy and uninfected populations with high survival rates. This paper is the first document on the spatial distribution of P. nobilis in Çanakkale Strait. Therefore, the P. nobilis population should be continuously monitored to ensure the sustainability of the species.

This study was conducted in Dardanelles between October 2007 and August 2009 when condition index, meat yield, biochemical compositions and environmental parameters of seawater were investigated and the study area was found to have available conditions for cultivation. Investigation of the study area showed a positive correlation in particular among condition index, seasonal variation of temperature, protein, fat and chlorophyll-a; a negative correlation was seen between them and carbohydrate value. It was clear from the two years study that the most ideal period for oyster harvest is April and August especially when condition index was maximum followed by a winter with no oyster yield is available in terms of the related processes involving oyster cultivation.

The growth and mortality rate of different size of mussels, Mytilus galloprovincialis, were compared in Mersin bay, Izmir. Mussel sampling was performed on a monthly basis over 1 year, together with hyrobiological parameters. Water temperature, salinity, chlorophyll a, total particulate matter (TPM) and particulate organic carbon (POC) were determined. Average chlorophyll a, TPM and POC values were 3.88±1.62 μg L−1, 13.12±3.68 mg L−1 and 252±121.89 μg L−1 respectively. Initial mean lengths of mussels for each size group were 10 mm (9.91±0.25 mm), 20 mm (20.14±0.29 mm), 30 mm (30.66±0.21 mm), 40 mm (40.14±0.21 mm), 50 mm (50.62±0.21 mm), 60 mm (59.77±0.21 mm) and 70 mm (69.47±0.62 mm). Maximum growth in length occurred during the spring–summer months. The annual length increments of mussel size groups were 46.22, 41.42, 30.3, 28.03, 20.63, 16.34 and 12.03 mm from small to large size groups respectively. Small mussels grew faster than large mussels and reached commercial size at the same time. Mortality was <5% for all groups at the end of the experiment.

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