Hüsamettin Balkis

Role of single-celled organisms in mucilage formation on the shores of Büyükada Island (the Marmara Sea)

This study was implemented to determine the environmental factors and causative organisms of the recent mucilage formation in the Marmara Sea. Samples were taken during the study from 7 different depths (0.5―30 m) of one sampling point of the Buyukada Island shore between January and June 2008. As a result, 6 2 phytoplankton species belonging to 5 different groups were identified. Dinofiagellates were dominant in terms of species number, and diatoms in terms of cell number. In January and February, mucilage formation was very dense, where 5 phytoplankton species (Clindrotheca closterium, Pseudo-nitzschia sp., Skeletonema costatum, Thalassiosira rotula (Bacillariophyceae) and Gonyaulax fragilis (Dinophyceae)) were reported as dominant organisms. Among them, Gonyaulax fragilis has never been reported in the Marmara Sea previously, thus that organism appeared firstly with the formation of dense mucilage and then when the mucilage decayed in May and June 2008, G. fragilis disappeared. Autofluorescent single-celled organisms were classified in three groups depending on their cell sizes (>20 μm, >2 μm, >o.2 μm) by membrane filtration and total count of bacteria were determined by epifluorescence microscope after dying with DAPI. The highest total bacteria was recorded in April at 25 m depth (66 55 ± 44 . 4 cells ml ―1 ) while the lowest count was in June at 0 . 5 m depth ( 1077 ± 2 6. 1 cells ml ―1 ). The seawater temperature ranged between 7.0 and 21.5°C, salinity between 20 . 9 and 37 . 4 ppt and dissolved oxygen amount between 2 . 75 and 12 . 75 mg l ―1 . The chlorophyll-a amount ranged between 0.10 and 6. 35 μg l ―2 , the higher values were recorded in January at 15 m depth (6.35 μg l ―1 ) and in April at 10 m depth ( 4 .8 9 μg l ―1 ). Among the nutrients, the amounts of nitrite + nitrate-N varied between 0 . 02 and 7 .6 7 μg-at N l ―1 , phosphate-P between 0.11 and 0.96 μg-at P l ―1 and silicate-Si between 0.37 and 8. 93 μg-at Si l ―1 . The highest values were determined at a deeper layer where nutrients are accumulated. On the other hand, the N:P ratio interval was found as 0.1―11.3, Si:P ratio as 2.92―52.33 and N:Si ratio as 0.01―1.10 during the sampling period. Nitrogen was the limiting nutrient and the silica amount was enough to enable the development of diatoms.

Toxic metal (Pb, Cd, Cr, and Hg) levels in Rapana venosa (Valenciennes, 1846), Eriphia verrucosa (Forskal, 1775), and sediment samples from the Black Sea littoral (Thrace, Turkey)

Rapana venosa (Valenciennes, 1846) and Eriphia verrucosa (Forskal, 1775) are the dominant benthic invertebrate species along the Thrace Coast of the western Black Sea. The aim of this study was to determine toxic metal (Hg, Cr, Cd, and Pb) accumulation levels in these species, as well as within littoral sediments from this area. Our results showed that all of the metals, except for Cd, were below that in average shale. The measured accumulation levels were mostly within the range of what is naturally found within the earths crust. However, some study stations did have increased concentrations, indicating anthropogenic pollution in these areas. The Cd contents of E. verrucosa collected from all our study stations were well above the limits set by the Turkish Food Codex, especially in Kıyıköy, whereas Pb content was close to the limit at all stations and exceeded the limit in Kıyıköy, but Hg content was below the limit at all stations. Cd content of R. venosa exceeded the limit only in Kumköy. Pb content was below the limit, and Hg was at or slightly above the limit at all stations.

Invasion biology in non-free-living species: interactions between abiotic (climatic) and biotic (host availability) factors in geographical space in crayfish commensals (Ostracoda, Entocytheridae)

In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement-related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non-free-living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum-Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum-Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This approach can also be implemented in other systems where the target species is closely interacting with other taxa.

Morphology of Testis and vas Deferens in the Xanthoid Crab, Eriphia verrucosa (Forskål, 1775) (Decapoda: brachyura)

Abstract The anatomy of the male reproductive organs of the brachyuran crab Eriphia verrucosa is presented, with a detailed analysis of the histology and histochemistry of the regional structure of the testis and vas deferens. The H-shaped testis is subdivided into three distinct parts: anterior, intermediate and posterior. The vas deferens is continuous with the posterior part of the testis, ends at the gonopore, and is subdivided into three distinct regions: proximal, medial and distal. The anterior part of the testis exhibits convoluted lobules including seminiferous tubules. Whereas the intermediate part of the testis has a simple columnar epithelium, the posterior part of the testis has a simple squamous epithelium. In the proximal and medial regions of the vas deferens, there is a simple cubic epithelium, while in the distal region of the vas deferens there is a high columnar epithelium. Spermatophores are first formed in the convoluted proximal region of the vas deferens and are encapsulated by mainly protein secretions in the distal region. These results suggest that the testis and vas deferens of Eriphia show similarity to the testis and vas deferens of other brachyuran crabs except for some slight differences. During formation of the spermatophores in the vas deferens the spermatozoa are prepared for successful fertilization.

The crab species found on the coasts of Gökçeada (Imbroz) Island in the Aegean Sea

In this study, 32 crab species belonging to 13 families are recorded from Gökçeada Island, based on bottom material collected at 39 stations around the island at depths between 0 and 70 m, using dredges, drift nets and scoop nets. Ecological properties of the species are provided.

Distributions of total metals in the surface sediments of the Bandirma and Erdek Gulfs, Marmara Sea, Turkey

The aim of this study is to determine the contents of aluminum, iron, manganese, nickel, copper, zinc, chromium, cadmium, lead, and mercury in sediments at 1–30 m depths of the Bandırma and Erdek Gulfs in the Southern Inner Shelf of the Marmara Sea. Sediment samples were collected from different depths (1 m, 5 m, 10 m, 20 m, 30 m) at each region in February 2008. Primary hydrographic conditions, such as temperature (6.6–14.5°C), salinity (22.6–26.875 psu), percentage of dissolved oxygen saturation (35–83 %), and pH (8.0–8.4) were recorded for each sampling point. Moreover the total organic carbon (0.5–2.9%) and the total calcium carbonate contents (0.8–60%) of sediment samples were determined. In surface sediments of both gulfs, Pb (21–62 mg kg−1) and Cd (0.52–0.86 mg kg−1) contents were determined to be higher than the shale average (Pb 20 mg kg−1, Cd 0.2 mg kg−1) while the other metal contents were measured to be lower in general. On the other hand, generally Hg (0.06–1.1 mg kg−1) contents were higher than the shale average (0.3 mg kg−1)at all of the examined stations in the Bandırma Gulf and lower than the shale average in the Erdek Gulf.

Distribution, diversity and some ecological characteristics of benthic amphipods in the Kapidağ Peninsula (Marmara Sea, Turkey)

Abstract The aim of this study was to determine the environmental factors affecting the fauna and the distribution of benthic amphipod species occurring on the Kapıdağ Peninsula, which is located in the south of the Marmara Sea. A total of 31 amphipod species were identified during the course of this study. In both seasons, Jassa marmorata (Holmes, 1905) and Protohyale schmidtii (Heller, 1866) were the most abundant species. During the study, temperature varied between 11.0 and 17.8°C, while salinity varied between 12.5 and 18.7 PSU; values of dissolved oxygen and pH ranged from 7.2 to 11.4 mg l-1 and 7.2 to 8.5 respectively at the coastal sites where hard bottom sampling was conducted. However, with regard to other sites where soft bottom sampling was carried out, the temperature varied between 8.0 and 18.0°C, salinity between 17.7 and 29.2 PSU, while values for dissolved oxygen and pH ranged from 5.1 to 11.4 mg l-1 and 7.8 to 8.7, respectively. In addition, the study of the amphipod species distribution revealed that the number of species was higher in spring compared to autumn while the number of individuals was higher in autumn compared to spring.

Decapod crustacean fauna of the Black Sea coasts of Istanbul

This study was carried out as a survey of the species of decapod Crustacea found along the Black Sea coasts of Istanbul. It also aims to report on some of their ecological properties. Samples were collected at 36 stations during 2000 and 2001 from depths of 0.5-65 m using a scoop net, dredge, beam-trawl, or trammel net. A total of 15 species of decapod crustaceans was identified. One of these, Philocheras fasciatus (Risso, 1816), is herein reported for the first time from the Turkish coastal waters of the Black Sea. Primary hydrographic conditions such as temperature (range 8.0-21.8°C), salinity (16.7-17.8‰), and dissolved oxygen (4.5-9.0 mg/l) were recorded at each sampling occasion.