Akademik Veri Yönetim Sistemi
1st International Symposium on "Sustainable Aquatic Research", İzmir, Türkiye, 21 - 25 Mayıs 2024
Abstract
Light intensity is a critical environmental variable affecting the
presence, abundance and behaviour of many organisms throughout the diel cycle.
Depending on changing light levels by the time of day, possible changes in the
activity and position of the demersal organisms may affect their catchability
to the bottom trawl. From this point of view, the effects of the diel period on
bottom-trawl species diversity were investigated during seven experimental
surveys carried out by R/V K. Piri Reis within the same locality at depths ranging
between 50 and 58 m in İzmir Bay. A total of 56 trawl samplings were
performed that covered the morning, noon, afternoon, dusk, early night (between
dusk and midnight), midnight, late night (between midnight and dawn) and dawn
periods of the day in each seasonal survey. Overall, 80
species were captured, including 3 crustaceans, 9 cephalopods, 11 cartilaginous
fish, and 57 bony fish. The
number of species by the trawl hauls ranged from 12 to 31 species, and species
diversity ranged from 1.07 to 2.86. Although it was generally observed that the
number and diversity of species in trawls towed during the daylight periods
were relatively higher than in trawl samples towed during twilight and night
periods, no clear diel pattern was found.
Keywords: Bottom-trawl, diel, day period,
dark period, twilight, İzmir Bay.