Yazar "Gozler, Ahmet Mutlu" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    EFFECTS OF PRESERVATION METHODS ON THE ?13C AND ?15N SIGNATURES IN MUSCLE TISSUES OF TWO FRESHWATER FISH SPECIES
    (Parlar Scientific Publications (P S P), 2011) Akin, Senol; Sahin, Cemalettin; Turan, Davut; Gozler, Ahmet Mutlu; Verep, Bulent; Bozkurt, Ahmet; Celik, Kemal
    Stable isotope is a powerful method for characterizing flows of energy through ecosystems. The power of this method, however, may be affected by preservation methods of the samples. We investigated the effects of four common preservatives (salt, formalin, and ethanol and freezing [control] and preservation duration (six and three months) on delta N-15 and delta C-13 values of two freshwater fish species, Perca fluviatilis (perch) and Blicca bjoerkna (silver bream). Six-month preservation caused little enrichment in delta N-15 of both species compared to three month but had almost the same effects on delta C-13 values of both species as in three-month preservation. All methods caused significant shifts (enrichment) in delta N-15 of both species, and the effects in general were greater in perch (range: 0.28 parts per thousand-2.19 parts per thousand) than in bream (range: 0.31 parts per thousand-1.29 parts per thousand), which suggested that preservative induced shifts in delta N-15 was species-specific. The methods caused little enrichment (ethanol-range: 0.03 parts per thousand - 0.26 parts per thousand bream and 0.30 parts per thousand-0.48 parts per thousand perch and salt: 0.18 parts per thousand perch three month) and depletion (salt-range: 0.03 parts per thousand-0.13 parts per thousand bream and 0.13 parts per thousand perch six month) in delta C-13. Of the preservatives, however formalin had significant but consistent effects on delta C-13 in both species (-1.27 parts per thousand and -1.25 parts per thousand) for the entire preservation duration. Preservation-induced shifts in delta C-13 were consistent in direction and magnitude for both species. The results suggested that ethanol and salt could be used without correction factor and formalin with correction factor for preservation of samples solely in delta C-13 studies.. For the studies requiring use of carbon and nitrogen together, however, ethanol at least six month in preservation may be suitable for storing samples when considering detection of changes less than 2 parts per thousand is required in ecological applications.
  • Küçük Resim
    Öğe
    Feeding habits of introduced European perch (Perca fluviatilis) in an impounded large river system in Turkey
    (Academic Journals, 2011) Akin, Senol; Sahin, Cemalettin; Verep, Bulent; Turan, Davut; Gozler, Ahmet Mutlu; Bozkurt, Ahmet; Celik, Kemal
    The feeding habits of perch (Perca fluviatilis) were documented by analyzing gut contents of more than 3300 specimens collected seasonally at nine stations located along the impounded large river in Turkey. Perch largely preferred fish (36%), insects (54%), other crustaceans (16%) and daphnia (13%). Spatial analysis showed that perch substantially preferred fish in the river section above the dam lakes and insects, crustacean and fish in the river section below the dam lake and in dam lakes. The perch at every size seemed to prefer fish with the highest and lowest percentage obtained for 0 to 80 and 141 to 200 mm. Insects and crustaceans were important for 81 to 140 mm and 0 to 120 mm length, respectively. Crustaceans were important in June, November and July. Insects and fish except for June 2009 constituted an important portion of the diets during every sampling month. The perch showed a piscivory feeding habit, a result obtained by trophic level calculated by stomach contents (3.87) and stable isotope (3.91) methods. Trophic level change little during the ontogeny with relatively higher value obtained for the larger length. The perch inhabiting in the river section above the dam lakes had the highest trophic level compared to the other sites. Diet breadth of perch was lower and higher for larger and middle length (101 to 140 mm), respectively. The diet breadth was higher in dam lakes, indicating opportunistic feeding habits in lakes. Being the most abundant fish species in the study system and showing predatory feeding habits suggested that perch may have an effect on local fish assemblage and itself through predation.