This study was carried out in order to determine some biological characteristics of the fish species of Spicara flexuosa, which is distributed on the Eastern Black Sea coast, and to contribute to the management of the picarel in all the seas of our country. Between October 2015 and September 2016, 599 fish samples were obtained and examined in the laboratory. It was determined that the examined individuals were distributed between the ages of I-VII which 31.22% of the population was male and 68.78% was female. The minimum-maximum total length values of the samples were between 8.7 and 21.8 cm; and the weight values ranged from 7.1 to 129.94 g. It has been determined that the mean total length of males is statistically different from that of females (P<0.05). Von Bertalanffy growth equilibrium was calculated as "L∞=22.71 cm TL, K=0.243 year-1, t0=-2.306 year-1; W∞=118.27 g" for females, "L∞=38.34 cm TL, K=0.063 year-1, t0 = -6.381 year-1; W∞=755.37 g" for males, and "L∞=33.42 cm TL, K=0.080 year-1, t0=-5.381 year-1; W∞=401.24 g" for all individuals. The length-weight relation of all individuals was found as W= 0.0118*L2.9727 (R2=0.9487). When the ratio of gonadosomatic index (GSI) data and gonadal maturity stages were examined over the year, it was determined that the reproduction of the picarel in the Black Sea occurred between June and September.

This study was carried out to determine the temporal and spatial distribution of Liocarcinus depurator (Crustacea: Decapod) caught by beam trawl in the southeast Black Sea between December 2012 and November 2013. Sampling was executed at depths from shoreline to deeper 30 m by using a 2 m wide beam trawl from İyidere, Merkez and Çayeli stations. L. depurator was determined most intensely (1000 m2) at 0-5 m depth at Çayeli station and during the summer season. L. depurator started to migrate from shallow to deeper in autumn and left the coast completely in winter. It approached the shore again in the spring and spread at all depths in the summer season. In addition, while it was distributed in three different habitats according to CPUE values, the highest CPUE value was calculated at Çayeli station, which has a macroalgae structure.

The increasing demand for sustainable and multifunctional materials in radiation shielding and optical applications has driven research toward utilizing natural and waste-derived reinforcements in polymer matrices. However, achieving effective attenuation performance across different radiation types using eco-friendly fillers remains a significant challenge. In this study, polyvinyl chloride (PVC)/Polystyrene (PSt) blend composites (1:1 weight ratio) were reinforced with powdered snail shell (SSP) as a biogenic additive, aiming to enhance their shielding and optical performance. Composites containing 5%, 10%, 20%, and 30% SSP (w/v) were fabricated and characterized. Key parameters including linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), mean free path (MFP), half-value layer (HVL), and effective atomic number (Zeff) were measured using a variable-energy X-ray source (13.37–59.54 keV) and ULEGe detector. Fast neutron shielding performance and theoretical values for build-up factor (EBF) and macroscopic neutron cross-sections were also calculated. The results showed a marked improvement in X-ray attenuation with increasing SSP content (SSP30 > SSP20 > SSP10 > SSP5), while neutron shielding declined due to the high oxygen content of SSP. Among the tested samples, the SSP30 composite exhibited the highest X-ray attenuation efficiency, whereas the SSP5 composition showed the greatest enhancement in optical reflectance and neutron absorption, indicating optimal performance in these respective tests. Additionally, 5% SSP incorporation improved optical reflectance by 12%, indicating enhanced photon backscattering at the material surface. This behavior contributes to improved gamma shielding efficiency by reducing photon penetration and enhancing surface-level attenuation. These findings highlight the potential of snail shell-based fillers as low-cost, sustainable reinforcements in multifunctional polymer composites.

A total of 2930 Mullus barbatus individuals collected from the Southeastern Black Sea coast between March 2017 and April 2018 were investigated regarding growth, mortality rates and the distribution determined by depth and season. M. barbatus is abundant along of 30-45 m depth in winter. Total length-weight relationship was determined as W=0.005L3.2344. Von Bertalanffy growth parameters for all individuals were calculated as L∞=28.19 cm, K=0.16 years-1, t0=-0.144 years. The maximum age was 5 years. The total length at 50% maturity was estimated as 11.63 cm in males and 11.68 cm in females. Exponential coefficients of natural mortality, total mortality, and fishing mortality rate of red mullet are estimated as 0.33 year-1, 1.001 year-1 and 0.67 year-1, respectively. The exploitation rate of population was calculated as 0.66 year-1. The fact that exploitation rate is above 0.5 may reflect a high fishing pressure on stock.