COMU Journal of Marine Sciences and Fisheries

39-47

Authors: İldeniz PINAR, Şükran YALÇIN ÖZDİLEK

The present study aims to investigate the anthropogenic impacts of crop farming, fertilizing practices, and pesticide use in riparian zones on detritus decomposition and on feeding of Melanopsis buccinoidea (Olivier, 1801) on detritus by employing the stable isotope method. For this purpose, (1) Non-treated, (2) fertilizer-treated and (3) pesticide-treated apple Malus pumila (Mill) and corn (Zea mays L.) leaves were used in duplicate as detritus material and left to decompose for about two and a half months. During the experiment, samples were collected from the detritus every ten days to conduct stable carbon and nitrogen analyses., M. buccinoidea individuals were then placed in the media containing different detritus types treatments for 25 days and the stable carbon and isotope values in the muscle tissues of M. buccinoidea were measured periodically. The δ13C values measured in the apple and corn leaves over a period of two and a half months were found to fluctuate and increased in each of the three treatments depending on the time of exposure and only in the fertilizer-treated corn leaves. The δ15N values of detrita in both plants were observed to have increased in the natural/non-treated and pesticide-treated conditions but decreased in the fertilizer-administered media during two and a half months. Conductivity and pH values in both plants were found to be high and low, respectively. In this medium, δ15N ratios were lower. The δ13C values of the M. buccinoidea kept in the corn detritus were found to be lower than those of the individuals kept in the apple detritus. It was remarkable to observe during the 25-day experiment that the δ13C values of the M. buccinoidea kept in the corn detritus tended to decrease.

53-58

Authors: Fatih YAVUZ, Alkan ÖZTEKİN

In this study, the selectivity of kirbed steel hooks no 6, 8, 10, 12 used for catching subtropical and lessepsian species the Marbled spinefoot (Siganus rivulatus Forsskål, 1775) in Gulf of Antalya, Kumluca, Finike, Demre and Kemer was calculated by using SELECT method. The total number of Marbled spinefoot caught in 16 operations was 406 individuals. According to log normal modal, the optimum catch lengths of 6, 8, 10, 12 numbers hooks were 20.79 cm, 17.67 cm, 14.91 cm, 12.60 cm and spread value for these hooks were 13.65 cm, 11.60 cm, 9.79 cm and 8.28 cm respectively. Considering the first reproductive length in Marbled spinefoot catching, the use of larger than number 6 size hooks may be recommended.

66-71

Authors: İbrahim Ender Künili, Fatma Arık Çolakoğlu

Holothuria tubulosa is an economic and most harvested sea cucumber species found in Turkey seas. Sea cucumbers are known to be sources of some of bioactive components which are play important roles in human health. In this study, it was aimed to determine the antioxidant and antimicrobial activity of H. tubulosa. The extracts of H. tubulosa were obtained with using different solvents such as, acetonitrile/trifloroacetic acid, methanol, and water/methanol. According to results, antioxidant activity of the extracts was lower than the reference antioxidant agents at all concentrations. However, the activity at higher concentrations of extracts was found to be closer to reference agents. Bacteriostatic effect was observed after the concentration of 12 µg/ml for all bacteria except Bacillus cereus, which has also shown resistance to reference antibiotic. As a consequence, H. tubulosa found in Turkey seas may be regarded as potential source of natural antioxidant agent.