Yazar "Mavruk, Sinan" seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Coastal Plankton Assemblages in the Vicinity of Galindez Island and Neumayer Channel (Western Antarctic Peninsula) during the First Joint Turkish - Ukrainian Antarctic Research Expedition(Central Fisheries Research Inst, 2018) Yilmaz, Izzet Noyan; Ergul, Halim Aytekin; Mavruk, Sinan; Tas, Seyfettin; Aker, Halim Vedat; Yildiz, Melek; Ozturk, BayramWestern Antarctic Peninsula is one of the fastest warming areas on Earth and coastal areas of the region are foremost affected. Here we present the state of coastal plankton assemblages of the Galindez Island and Neumayer Channel, Western Antarctic Peninsula in austral autumn (April 2016). Surface water temperatures were ranged between -0.12 degrees C and -0.97 degrees C and average chlorophyll-a concentrations were 0.65 mu g/l. A total of 50 phytoplankton and 24 zooplankton taxa (15 copepods and 9 meroplanktonic species) were identified during the sampling period. Diatom species (78%) predominated phytoplankton and the highest abundance was 820 cells l(-1), while the highest number of phytoplankton species was 42. Zooplankton was prevailed by the dominance of copepods, except contribution of meroplankton at the Neumayer channel. Highest zooplankton abundance was 101 ind.m(-3). The sampling season was the transition period from the productive spring-summer to dormant winter conditions, which explains the low abundances registered, however, on contrary to low cell abundances, diversity was high within plankton.Öğe Descriptive Capability of Datasets as Proxy of Sea Water Temperature in Coastal Systems: An Evaluation from the Aegean Sea(Central Fisheries Research Inst, 2021) Bengil, Fethi; Mavruk, Sinan; Kizilkaya, Zafer; Bengil, Elizabeth G. T.; Alan, Vahit; Kizilkaya, Inci TuneyScientific and technological progresses have introduced diverse data sources for seawater temperature over broad temporal and spatial ranges. Here, we investigated the performance of satellite and model-based seawater temperature data for different temporal composites and depths. We applied an in-situ temperature time-series obtained in a coastal bottom in the Aegean Sea over three years, as the reference. Both datasets showed largely significant relationships based on cross-correlation analyses and presented descriptive properties of the in-situ conditions at corresponding depths. Based on the results of analyses, the modeling datasets presented more reliable results and representations of in-situ conditions than the datasets obtained from satellite for the coastal region. However, the datasets obtained from the satellite also provided reliable data for all time frames investigated, particularly in the mixed surface layer. Monthly datasets were more effective in providing descriptive values in long term studies. This is the first detailed study to explore the descriptive capacities of modeling for water temperature in coastal environments. According to the results, the selection of a dataset as a proxy for seawater temperature requires careful consideration. The present study provides an extensive baseline for evaluating the suitability of the application of specific datasets as proxies in coastal ecosystems.Öğe Feeding Ecology of Four Demersal Shark Species (Etmopterus spinax, Galeus melastomus, Scyliorhinus canicula and Squalus blainville) from the Eastern Aegean Sea(Central Fisheries Research Inst, 2019) Bengil, Fethi; Bengil, Elizabeth G. T.; Mavruk, Sinan; Heral, Ogulcan; Karaman, Ozan D.; Ozaydin, OkanIn this study, the diet composition and trophic ecology of four demersal chondrichthyan species; Etmopterus spinax, Galeus melastomus, Scyliorhinus canicula and Squalus blainville were studied in the eastern Aegean Sea. In the stomachs of the samples which mostly consisted of juvenile individuals, a total of 97 prey taxa were identified. Teleost fishes were the most important prey group. The diversity of stomach content ranged between 15 species in E. spinax. and 70 species in S. canicula. The dietary breadth of G. melastomus and S. canicula were found to be narrower than the other two species examined. In addition, high niche overlap scores were detected amongst the species. All of the examined species had trophic levels higher than 4; with the highest trophic level being 4.20 and belonging to E. spinax. Comparisons among calculated trophic levels by global methods and a regional weighted method, which is proposed in this study, showed that the regional method offers remarkable advantages that can be used to reduce the uncertainty of the estimations.Öğe Retention probability of purse seine grating sieve based on fish morphology(Ege Univ, Fac Fisheries, 2021) Tosunoglu, Zafer; Mavruk, Sinan; Kasapoglu, NazliThe retention-releasing patterns of the double-grid grating sieve placed on the deck of the purse seiners were revealed for four case species (Sardina pilchardus, Sardinella aurita, Engraulis encrasicolus and Boops boops) using a simulated data predicted from total length (TL) - maximum height (Hmax) and TL - maximum width (Wmax) regressions. To calculate these relationships, samples were collected during commercial purse seine operations between 3 April 2017 and 21 March 2018 in Izmir Bay, Aegean Sea (Turkey). Optimal Bar Spacing (OBS) values corresponding to minimum landing sizes or the length at first maturity were calculated separately for each species. OBS values were found 10.97 mm for sardine (Sardina pilchardus), 11.29 mm for round sardine (Sardinella aurita), 7.78 mm for anchovy (Engraulis encrasicolus) and 17.89 mm for bogue (Boops boops). The bar spacing regulations may constitute a promising management measure to release undersized fish for the purse seine fishery in the Aegean Sea.
