Feeding ecology of portunid crab, Carcinus aestuarii Nardo, 1847 in Çardak Lagoon (The Turkish Straits System)

The aim of the present study was to determine the feeding ecology of portunid crab, Carcinus aestuarii in Çardak Lagoon. For this purpose, a total of 533 crab stomachs were analyzed. Stomach contents were examined under a binocular stereomicroscope and 240 (45%) of the stomach samples were recorded as full (containing at least one food item) and 293 (55%) were recorded as empty. The occupancy rates were 25% in 127 stomachs, 50% in 69, and 100% of 44. The main diet of crab individuals was composed of fragments of fish species. Diatoms were the least consumed food by crabs. A total of 8494 diet fragments were found in the stomachs. Total stomach content was 26.39 g of fish vertebrates having the highest weight (3.58 g).

Population structure, growth and reproduction characteristics of the portunid crab, Carcinus aestuarii Nardo, 1847 (Decapoda, Carcinidae) in Çardak Lagoon, Turkish Straits System

The aim of the present study was to determine the population structure and bioecological characteristics of the portunid crab, Carcinus aestuarii in Çardak Lagoon. In this study, the crabs were sampled by means of fyke-nets at 6 different stations between April 2015 and March 2016. A total of 2458 individuals (686 females, 1755 males, and 17 juveniles) were captured. The average carapace length was measured as 38.85 ± 0.17 mm in females, and 47.65 ± 0.16 mm in males. The highest number of specimens was observed in November with 239 individuals, while the lowest number (125 specimens) was observed in February. The reproductive period in both sexes was between November and February and females with eggs were found in November, February and March. An average number of eggs in a female was 61 390 ± 8.48 and the egg diameter was 345 μm. The female : male ratio was 0.39 : 1. This paper includes the first published data on population structure, growth, and reproduction characteristics of C. aestuarii in a protected lagoon in the Turkish Straits System.

Decapod crustaceans in benthic habitats of the Turkish Straits System with new records

The objective of this study was to investigate decapod species occurring in the Turkish Straits System. For this purpose, benthic samples were collected from six different biotopes (photophilic algae, Cystoseira barbata, meadows, Posidonia oceanica, mussel, Mytilus galloprovincialis, meadows, Zostera marina, serpulid reef, and rocks) at depths ranging from 10 to 1000 m. A total of 60 species of decapod crustaceans were identified, including new records for the Turkish Straits System: Processa elegantula, P. modica, Richardina fredericii, Callianassa subterranea, Gourretia denticulata, Inachus parvirostris and Macropodia linaresi. In addition, some information about the spatial and bathymetric distribution as well as biotope preferences of the decapod community is provided.

Circulation of the Turkish Straits System under interannual atmospheric forcing

A simulation of the Turkish Straits System (TSS) using a high-resolution, three-dimensional, unstructured mesh ocean circulation model with realistic atmospheric forcing for the 2008–2013 period is presented. The depth of the pycnocline between the upper and lower layers remains stationary after 6 years of integration, indicating that despite the limitations of the modelling system, the simulation maintains its realism. The solutions capture important responses to high-frequency atmospheric events such as the reversal of the upper layer flow in the Bosphorus due to southerly severe storms, i.e. blocking events, to the extent that such storms are present in the forcing dataset. The annual average circulations show two distinct patterns in the Sea of Marmara. When the wind stress maximum is localised in the central basin, the Bosphorus jet flows to the south and turns west after reaching the Bozburun Peninsula. In contrast, when the wind stress maximum increases and expands in the north–south direction, the jet deviates to the west before reaching the southern coast and forms a cyclonic gyre in the central basin. In certain years, the mean kinetic energy in the northern Sea of Marmara is found to be comparable to that of the Bosphorus inflow.