Marmara Basin Research Articles

Investigation of the variability applying classical (MK-SR) and modern (ITTA-TPSC) trend methods to meteorological parameters of Marmara Basin in Turkey

Scientific studies for countries experiencing climate change have accelerated recently. Turkey is among the countries experiencing climate change. Studies carried out for this country or its basins are of great importance both for the basin and the country. Therefore, Marmara Basin, where Turkey's population density is highest and industrialization is at the most advanced level, is selected in this study. The length of meteorological data is 45 years. The analysis of these data is made with Mann-Kendall (MK) and Spearman Rho (SR), which are classical trend methods, and Innovative Triangle Trend Analysis (ITTA) and Trend Polygon Star Concept (TPSC), which are modern trend methods. When the studies on Marmara basin are examined, there is no study that includes these four methods. Therefore, this study stands out in this respect. Because these analysis methods will reveal a new idea by applying them to hydro-meteorological data within the basin area. Before applying MK method, serial correlation method is applied to the meteorological parameter data of all stations. When the analysis results are examined; a general increasing trend is observed in precipitation data for ITTA and TPSC methods. No trend is observed in precipitation data for MK and SR methods. A general increasing trend is observed in temperature data for ITTA, MK and SR methods. However, a generally decreasing trend is observed in temperature data for TPSC method. While there is generally no trend in relative humidity data for MK and SR methods, an increasing trend is observed for ITTA and TPSC methods.

Evolving a Methodology for Assessing Pesticide Pressure on Water Bodies under Data Scarce Conditions: A Case Study on the Marmara Basin in Türkiye

Evolving a Methodology for Assessing Pesticide Pressure on Water Bodies under Data Scarce Conditions: A Case Study on the Marmara Basin in Türkiye

The effects of salinity on phytoplankton community structure in the 6 lagoons of the Marmara Basin (Türkiye)

The effects of salinity on phytoplankton community structure in the 6 lagoons of the Marmara Basin (Türkiye)

A practical approach to revise the Oxynoemacheilus bergianus species group (Teleostei: Nemacheilidae).

The Oxynoemacheilus bergianus species group is revised based on tree topology (ML, NJ, MP), distance (K2P and ASAP) and Poisson tree process analyses of DNA barcode data tested against morphometric and morphological characters including colour patterns. The O. bergianus species group is distinguished from other Oxynoemacheilus groups based on morphological characters: its constituent species have a slender caudal peduncle, a suborbital flap in the male, a mottled or blotched colour pattern, and lack bold, black spots on the caudal-fin base. It is also supported as a monophyletic unit in our molecular analysis. The O. bergianus group includes 10 molecular clades following congruently well-supported NJ, MP and ML based entities. Species described as O. bergianus, O. banarescui, O. erdali, O. fatsaensis, O. samanticus, and O. simavicus from Turkey, O. lenkoranensis from Azerbaijan, and O. longipinnis and O. parvinae from Iran belong to this species group. The group includes also four unnamed molecular clades. We were unable to detect external differences between any of the molecular clades in colour pattern or any morphometric or morphological characters examined. In the 10 molecular clades in the O. bergianus species group, the intraclade K2P distance ranges from 0.01.8% while the distances between molecular clades ranges from 0.65.9%. To resolve the species diversity of this group, we also analysed the intraspecific and interspecific variability in the K2P distance of DNA barcode data from 53 other Oxynoemacheilus species. Here, the intraspecific variability ranges from 0.02.4% while the interspecific K2P distance ranges from 1.220.8%. In the O. bergianus species group, only four groups are detected by the mPTP species delimitation approach distinguished by a K2P distance of 2.9% or more. We treat these four groups as valid species, corresponding to O. banarescui, O. bergianus, O. fatsaensis, and O. simavicus. Oxynoemacheilus samanticus from the Kzlrmak and Seyhan drainages, O. lenkoranensis from the Caspian basin, O. erdali from the Euphrates, and O. longipinnis and O. parvinae from the Tigris drainage are treated as synonyms of O. bergianus. Fishes from an unnamed molecular clade from the upper Tigris, and from a second unnamed clade from the upper Euphrates, are both identified as O. bergianus. Oxynoemacheilus bergianus might be a junior synonym of O. bergi from the Kura. The distribution range of O. simavicus, described from the Simav drainage in the Marmara basin, is expanded to the east and two molecularly differentiated population groups occur in the Sakarya drainage, the Byk Melen River and potentially in other adjacent coastal streams. Oxynoemacheilus fatsaensis, described from the coastal stream Eleki in northern Anatolia, is also widespread in the Yeilrmak drainage. Morphological characters proposed to distinguish O. fatsaensis from the other species of the O. bergianus group could not be confirmed by our data on fishes from the Yeilrmak. This study also discusses the theoretical background, our reasons for conducting this revision in the way we did, and what the alternatives would be.

Subaqueous fault scarps of the North Anatolian Fault in the Gulf of Saros (NE Aegean); where is the western limit of the 1912 Mürefte-Şarköy earthquake rupture?

SUMMARYThe westernmost segment of the North Anatolian fault in NW Turkey lies mostly offshore, in the Sea of Marmara and the Gulf of Saros (NE Aegean), respectively to the E and W of a 45 km inland central portion. The 9 August 1912 Mürefte-Şarköy (Ms 7.4) and 13 September 1912 (Ms 6.8) earthquakes occurred along this segment. To date, the segment was studied mostly onshore although estimated magnitude and location suggest an offshore extension. Recent studies show the eastern rupture extension in the Sea of Marmara, while its western counterpart in the Gulf of Saros remains less documented. Here we use new observations from high-resolution marine geophysical data (multibeam bathymetry, side-scan-sonar, and seismic reflection profiles), to constrain the offshore 1912 ruptures in the Gulf of Saros. Detailed mapping of the subaqueous fine-scale morphology and structure of the fault provides a new insight for the western limit of the two 1912 surface ruptures. Distribution of fresh scarps, 3-D structural reconstructions, the complexity of fault segments, and the recent seismicity, altogether suggest that the western termination of the 1912 rupture(s) ends 37 km offshore in the Gulf of Saros. Following the 1999 Kocaeli earthquake, in the eastern Sea of Marmara, the unruptured segment length between the 1999 and 1912 ruptures became a critical issue, because of its implication for future earthquakes in the so-called Marmara seismic gap. If a 150–160 km total rupture length for the two 1912 earthquakes is assumed, a western rupture termination point at the inner Saros basin margin means that the eastern extension of the 9 August earthquake rupture reached the Central Marmara Basin. This outcome necessarily has implications for the seismic hazard in the Marmara coastal area that includes the Istanbul metropolitan area.

Mapping the Establishment and Invasiveness Potential of Rainbow Trout (Oncorhynchus mykiss) in Turkey: With Special Emphasis on the Conservation of Native Salmonids

Rainbow trout (Oncorhynchus mykiss) has become by far the most frequently farmed freshwater fish species in Turkey, whereas very little is known about its establishment and invasiveness potential. We explored this potential through a combination of Maxent habitat suitability model and the Aquatic Species Invasiveness Screening Kit (AS-ISK) on the river basin scale by generating an overall risk score (ORS). The outcome of this approach was also incorporated with the spatial analysis of native salmonid species by generating a relative vulnerability score (RVS) to prioritize susceptibility of native species (or populations) and to propose risk hotspots by identifying their potential geographic overlap and interaction with O. mykiss. Results suggest that the northern basins (Eastern Black Sea, Western Black Sea and Marmara basins) are the most suitable basins for O. mykiss. According to the Basic Risk Assessment (BRA) threshold scores, O. mykiss is classified as “high risk” for 3 (12.0%) of the 25 river basins screened (Western Black Sea, Eastern Black Sea and Maritza-Ergene), and as “medium risk” for the remaining basins. The climate change assessment (CCA) scores negatively contributed the overall invasiveness potential of O. mykiss in 22 (88.0%) of the river basins and resulted in zero contribution for the remaining three, namely Aras-Kura, Çoruh river and Eastern Black Sea. The ORS score of river basins was lowest for Orontes and highest for Western Black Sea, whereas it was lowest for Konya-closed basin and highest for Eastern Black Sea, when CCA was associated. The micro-basins occupied by Salmo rizeensis had the highest mean habitat suitability with O. mykiss. Among the all species, S. abanticus had the highest RVS, followed by S. munzuricus and S. euphrataeus. The overall outcome of the present study also suggests that the establishment and invasiveness potential of O. mykiss may decrease under future (climate warmer) in Turkey, except for the northeast region. This study can provide environmental managers and policy makers an insight into using multiple tools for decision-making. The proposed RVS can also be considered as a complementary tool to improve IUCN red list assessment protocols of species.

The uppermost Pleistocene–Holocene mud drape across the Marmara Sea: Quantification of detrital supply from southern Marmara rivers

The Marmara Sea (area 11,350 km2; volume 3378 km3; central basins >1100 m deep) straddles the North Anatolian Transform Fault separating the Eurasian and Aegean-Anatolian tectonic plates. Along with the shallow straits of Dardanelles and Bosphorus (depths ~63 m and ~40 m, respectively), the Marmara Sea forms the only marine connection between the Black Sea and the eastern Mediterranean. During Pleistocene glacial stages, the modern straits were subaerial valleys and the modern Marmara basin was occupied by the landlocked Propontis Lake. Previous researchers attributed major portions of a widely distributed uppermost Pleistocene–Holocene mud blanket (locally >10–25 m thick; volume 43–47 km3) to transport of suspended load through one or both of the straits, as either the Aegean Sea (at ~13.8 cal ka) or the Neoeuxine Lake (today's Black Sea, at ~11.1 cal ka) began to spill into the Marmara basin. To test these suggestions, the thicknesses and volume of the mud blanket were determined from >5000 line-km of airgun, sparker and boomer profiles and > 100 cores, and compared with the contemporary supply from local rivers to decide, by difference, if the straits might have had a significant role. Volume calculations for the detrital supply from rivers rely on (1) decades of daily water- and sediment-discharge data from gauging stations, acquired before 20th century dam construction and, independently, (2) the BQART model which uses a variety of hydrological, geomorphic, geological and climate data. These calculations demonstrate that >85–90% of the detritus in the offshore mud blanket was supplied by steep rivers (Kocasu River and its tributaries) and mountainous streams draining the highlands of the southern Marmara region. Geochemistry of the <38 μm fraction supports this source. Any input through the Dardanelles has been sporadic and limited to perhaps ~5 Gt of suspended load (equivalent to ~5.2 km3 of porous mud when deposited) because of changing directions and rates of flow since the Last Glacial Maximum. Resedimentation through mass wasting and transgressive shoreface erosion appear to be minor compared with river supply. The isolated nature of the Marmara basin and its supply from mostly a single watershed afford an opportunity to verify the reliability of this type of hindcast analysis, based upon sediment-discharge data and catchment models – analysis which cannot be completed with a comparable level of certainty along open marine coastlines elsewhere.

Could you see the sea?: Upper Pleistocene sea level fluctuation over the Balkan Peninsula: A review

Tectonic movements affected the southern part of the coast the most, while some parts such as Danube delta remained almost untouched through the Upper Pleistocene, covering the last 124.000 years. This is why the reconstruction of the Balkan coast requires multiple proxy data. The chronostratigraphy used in this paper is marine isotope stages, as it allows comparing different records used for paleo environmental reconstruction. The paper is divided into five parts, one for each basin surrounding the Balkan Peninsula: Adriatic, Ionian, Aegean, Marmara and Black Sea basin. All of the basins experienced sudden shrinking in the Last Glacial Maximum, when the sea level fell for ~120 m when the aquatic mollusks entered a population bottleneck, but the terrestrial ones flourished, as their habitat grew. As the Mediterranean territory got submerged again, the migration corridors for the humans disappeared, leaving their traces preserved under the sea level.

The moderate size 2019 September Mw 5.8 Silivri earthquake unveils the complexity of the Main Marmara Fault shear zone

SUMMARYThe unbroken section of the North Anatolian Fault beneath the Sea of Marmara is a major source of seismic hazard for the city of İstanbul. The northern and currently the most active branch, the Main Marmara Fault (MMF), is segmented within a shear zone and exhibits both partially creeping and locked behaviour along its 150 km length. In 2019 September, a seismic activity initiated near MMF, off-coast the town of Silivri, generating 14 earthquakes ≥ Mw 3.5 in a week. The Mw 5.8 Silivri earthquake, is the largest in the Marmara Sea since the 1963 Mw 6.3 Çınarcık earthquake. Our analyses reveal that the activity started in a narrow zone (∼100 m) and spread to ∼7 km following an Mw 4.7 foreshock within ∼2 d. The distribution of relocated aftershocks and the focal mechanisms computed from regional waveforms reveal that the Mw 5.8 earthquake did not occur on the MMF, but it ruptured ∼60° north-dipping oblique strike-slip fault with significant thrust component located on the north of the MMF. Finite-fault slip model of the main shock shows 8 km long rupture with directivity toward east, where the ruptured fault merges to the MMF. The narrow depth range of the slip distribution (10–13 km) and the aftershock zone imply that the causative fault is below the deep sedimentary cover of the Marmara Basin. The distribution of aftershocks of the Mw 5.8 event is consistent with Coulomb stress increase. The stress changes along MMF include zones of both stress decrease due to clamping and right-lateral slip, and stress increase due to loading.

Seismic Hazard and Total Risk of Existing Large Dams in the Marmara Basin, Turkey

Safety evaluation is a fundamental stage of existing dams and their appurtenant structures, which have a high-risk potential for downstream life and property. Turkey is a country, which seismically settled at one of the most active regions in the world, and earthquakes with high magnitude frequently occur here. There are some regions, which are severely under threatening of earthquakes. One of them is the Marmara region with twenty-four million people. This region, namely the Marmara basin, has at least forty-five large dams with different types. This study considered nineteen of them to relieve their seismic hazard parameters for all dam sites and total risk for each structure. The study area is lying in a seismically, very active part of Turkey. The southern part of the basin is structurally cut by the North Anatolian Fault, which is a famous structural feature that produces deathful earthquakes, and its offshoots. The analyses have indicated that peak acceleration widely ranges for the nineteen dam sites of this basin. The total risk analyses have concluded that most of the dams in the metropolitan area have high-risk classes and a significant effect for public safety.

A preliminary phylogenetic analysis of ribbed-pine-borer (Rhagium inquisitor) based on mitochondrial COI sequences

Abstract The increased volume of intercontinental-trade had facilitated the distribution of species, including invaders. Wooden packaging materials, goods and timber are being transported via international ports in East of the Marmara Basin, where has vast forests. That forests provide an appropriate-mediator for the introduction and invasion of wood-boring insects, which are the most common group being transported between continents. One of them is Rhagium inquisitor, which has a pivotal role in wood decay, nevertheless, it is detrimental for industrial wood. We analyzed the 654 bp length of cytochrome c oxidase I (COI) gene, to determine native and introduced haplotypes of the ribbed-pine-borer, to investigate their phylogenetic relationships and possibly cryptic speciation of the morphospecies. It was found out that sixteen haplotypes were divided into five haplogroups. The groups were assembled on two main lineages: Eurasian and American. The genetic distance between the American (Groups 1–3), Asian (Group-4) and European (Group-5) clusters ranged from 3 to 10%; between haplotypes ranged from 0.2 to 10.9%. The distances between the specimens of the Marmara Basin (H9-12, Group-4) were lower compared to H16, which nested in Group-5. That haplotype was sampled on imported timber and was found out that it is shared between France, Germany, Italy, and Austria. Maximum Likelihood, Neighbor-Joining and Bayesian Inference trees showed the same topologies, and Median-Joining network also supported them. Contrary to the usual, our findings point out that some species might have been introduced from Europe to Asia. Furthermore, the high genetic diversity of the bark-runner between continents could be a sign of cryptic-allopatric speciation.

Black Sea Intrapycnocline Lenses according to the Results of a Numerical Simulation of Basin Circulation

The exact scenario of the propagation of highly saline Marmora Sea waters in the Black Sea basin is not clear. Together with river runoff, they form the prevailing haline stratification of the basin. One regime of their propagation can be the formation of lenses similar to highly salted and warm lenses of the Mediterranean Sea water in the Atlantic Ocean basin. The purpose of this study is the numerical modeling and subsequent analysis of these dynamic structures that form in the Black Sea due to water exchange through the Bosphorus strait. In this case, the main difficulty is the need for high spatial resolution in the strait. The paper provides a brief description of the NEMO ocean-modeling framework used and the features of configuration that make it possible to reproduce the circulation in the basins of the Azov, Black, and Marmara seas with a spatial resolution of 1.16 km. Fields from the ERA5 atmospheric reanalysis are used as the atmospheric forcing. The numerical experiment carried out by us allows reproducing a typical structure of the seasonal variability of the Black Sea rim current and the features of the vertical structure of the basin waters for the period of 2008–2009. The spatial resolution of the results of numerical modeling made it possible to accomplish a high-quality reconstruction of the saltwater dynamics in the basin and at the exit of the Bosphorus strait. Five lenses formed near the strait and captured by the rim current jet were simulated for the period of 2008–2009. They are well-pronounced in the seawater salinity field for the period of 1–2 months. Using one of the lenses as an example, it is shown that its core is located at a depth of about 75 m. The vertical size of the structure is almost 40 m and its horizontal scale is 15 km. The simulation results demonstrate that lens formation events are associated with the gain in the saltwater inflow after storms in the Sea of Marmara basin. Verifying the results of the study can be done based on a specialized field experiment in the Bosphorus region during the periods of the most probable formation of the Black Sea intrapycnocline lenses.

An Investigation on the Trichoptera Fauna of Gönen Stream (Balıkesir-Çanakkale)

Çalışma alanı olarak seçilen Gönen Çayı, Marmara Havzası’nın Çanakkale-Balıkesir kesimindeki en önemli akarsulardan biridir. Yaklaşık uzunluğu 134 km’dir. Özellikle son yıllarda yoğun tarım, hayvancılık ve madencilik faaliyetlerinden olumsuz olarak etkilenmekte ve çeşitli kirletici etkilere maruz kalmaktadır. Bu çalışmada Gönen Çayı’nın Trichoptera faunasının belirlenmesi amaçlanmış, Eylül 2010 ve Temmuz 2012 tarihleri arasında arazi çalışmaları gerçekleştirilmiş ve seçilen 12 istasyondan mevsimsel periyotlarla (8 arazi çalışması) örnekler alınmıştır. Çalışma sonunda, Gönen Çayı’nın Trichoptera (Insecta) faunasının 9 familya ve 16 cinse ait 28 tür tarafından temsil edildiği belirlenmiştir. Belirlenen familyalardan Hydropsychidae en fazla tür çeşitliliğine sahipken (9 tür), bunu sırasıyla Polycentropodidae ve Psychomyiidae (5’er tür), Glossossomatidae (3 tür) ve Limnephilidae (2 tür) izlemiştir. Goeridae, Lepidostomatidae, Rhyacophilidae ve Odontoceridae familyaları ise birer taksonla temsil edilmiştir.

3-D crustal density model of the Sea of Marmara

Abstract. The Sea of Marmara, in northwestern Turkey, is a transition zone where the dextral North Anatolian Fault zone (NAFZ) propagates westward from the Anatolian Plate to the Aegean Sea Plate. The area is of interest in the context of seismic hazard of Istanbul, a metropolitan area with about 15 million inhabitants. Geophysical observations indicate that the crust is heterogeneous beneath the Marmara basin, but a detailed characterization of the crustal heterogeneities is still missing. To assess if and how crustal heterogeneities are related to the NAFZ segmentation below the Sea of Marmara, we develop new crustal-scale 3-D density models which integrate geological and seismological data and that are additionally constrained by 3-D gravity modeling. For the latter, we use two different gravity datasets including global satellite data and local marine gravity observation. Considering the two different datasets and the general non-uniqueness in potential field modeling, we suggest three possible “end-member” solutions that are all consistent with the observed gravity field and illustrate the spectrum of possible solutions. These models indicate that the observed gravitational anomalies originate from significant density heterogeneities within the crust. Two layers of sediments, one syn-kinematic and one pre-kinematic with respect to the Sea of Marmara formation are underlain by a heterogeneous crystalline crust. A felsic upper crystalline crust (average density of 2720 kg m−3) and an intermediate to mafic lower crystalline crust (average density of 2890 kg m−3) appear to be cross-cut by two large, dome-shaped mafic high-density bodies (density of 2890 to 3150 kg m−3) of considerable thickness above a rather uniform lithospheric mantle (3300 kg m−3). The spatial correlation between two major bends of the main Marmara fault and the location of the high-density bodies suggests that the distribution of lithological heterogeneities within the crust controls the rheological behavior along the NAFZ and, consequently, maybe influences fault segmentation and thus the seismic hazard assessment in the region.

Magnitudes of future large earthquakes near Istanbul quantified from 1500 years of historical earthquakes, present-day microseismicity and GPS slip rates

In the past 1500 years, seven sequences of significant earthquakes have occurred on a 160-km-long segment of the North Anatolian Fault zone (NAFZ) centered on Istanbul. The most recent of these sequences will be complete with the future occurrence of one or more Mw ≥ 7.0 earthquakes near the city. From a summation of the seismic moment released by historical earthquakes between 500 and 2000 CE we calculate a mean slip deficit rate of 9.9 mm/year. Our moment summation procedure sums the seismic moment associated with known historical earthquakes in the past 1500 years based on rupture length and assumed seismogenic depth. We observed that in the 1999 Izmit earthquake, strongly coupled fault patches were associated with the highest co-seismic slip. In our calculated map of present-day slip-potential, we recognize several such patches from their low present-day rate of microseismicity, e.g. segments beneath the Kumburgaz and Eastern (Çınarcık) Marmara Basins. In contrast, intervening weakly coupled patches host high present-day background seismicity, e.g. the segment beneath the Western (Tekirdağ) Basin. This lends credibility to an interpretation of future earthquakes occurring in three seismogenic segments of the NAFZ corresponding to three deep basins in the Sea of Marmara. The present-day slip deficits reach up to 1.7 m beneath the Western (Tekirdağ Basin) segment, and 4.0 m and 5.4 m beneath the Central (Central High and Kumburgaz Basin) and Eastern (Çınarcık Basin) segments, respectively. These segments most recently ruptured in August 1766, May 1766 and October 1509 and currently have a potential to generate Mw 7.2, Mw 7.4 and Mw 7.5, earthquakes respectively. Although contiguous ruptures have not occurred historically, ruptures of contiguous segments could occur as a Mw 7.5 earthquake in the west, or a Mw 7.6 earthquake in the east or as a single through-going Mw 7.7 rupture.

Upward migration of gas in an active tectonic basin: An example from the sea of Marmara

Gases of various sources were collected at the seafloor of the Marmara basin suggesting that the gases expelled have experienced multiple sequences of upward migration, from multiple sources. The pathways of upward migration of gas can be reconstructed by considering the distribution of gas seeps with respect to the near-surface geomorphostructure and the regional stratigraphic architecture of the Marmara Basin. Gas seeps appear to be more favourably localized within a 1–2 km swath around active faults where sediment permeability is probably enhanced by deformation. In the fault zones, fault intersections between sets of transtensive and transpressive subsidiary faults, or between subsidiary faults and main faults, are the preferred gas pathways. These subsidiary structures localize methane seeps, observed as elongated black patches with bacterial mats, gas bubble emission sites, and chemoherms associated with buried mud volcanoes. Gas seeps are, however, rare along active faults segments crossing basin depocenters but focus along basin edges and along topographic highs. Considering the role of sedimentary layers as gas migration pathways can explain this characteristic of the distribution of gas seeps. Fault zones that cross updip gas migration pathways will vent comparatively more gas than fault zones on the downdip side. Moreover, gas accumulation and resulting overpressuring along the western fault segment crossing the Western High may be associated with aseismic fault creep and intense gas emissions at the seafloor. In contrast, the poorly focused seepage along the fault segment crossing the Central High may be linked to the locked state of this fault segment.

Stress modeling to determine the through-going active fault geometry of the Western North Anatolian Fault, Turkey

The North Anatolian Fault (NAF) is a 1200 km long dextral strike-slip fault which is part of an east-west trending dextral shear zone (NAF system) between the Anatolian and Eurasian plates. The North Anatolian shear zone widens to the west, complicating potential earthquake rupture paths and highlighting the importance of understanding the geometry of active fault systems. In the central portion of the NAF system, just west of the town of Bolu, the NAF bifurcates into the northern and southern strands, which converge, then diverge to border the Marmara Sea. At their convergence east of the Marmara Sea, these two faults are linked through the Mudurnu Valley. The westward continuation of these two fault traces is marked by further complexities in potential active fault geometry, particularly in the Marmara Sea for the northern strand, and towards the Biga Peninsula for the southern strand. Potential active fault geometries for both strands of the NAF are evaluated by comparing stress models of various fault geometries in these regions to a record of focal mechanisms and inferred paleostress from a lineament analysis. For the Marmara region, the best-fit active fault geometry consists of the northern and southern bounding faults of the Marmara basin, as the model representing this geometry better replicated primary stress orientations seen in focal mechanism data and stress field interpretations. In the Biga Peninsula region, the active geometry of the southern strand has the southern fault merging with the northern fault through a linking fault in a narrow topographic valley. This geometry was selected over the other two as it best replicated the maximum horizontal stresses determined from focal mechanism data and a lineament analysis.

Three new species of Alburnoides from the southern Black Sea basin (Teleostei: Cyprinidae).

Three new Alburnoides species are described from the southern Black Sea basin. Alburnoides kurui, new species, from the Yeşilırmak drainage, is distinguished from other species of Alburnoides in the southern Black Sea basin, the Marmara basin and the Anatolian Aegean basin by having a scaleless keel between the posterior pelvic fin base and the anus or with rarely 1 scale covering the anterior part of the keel; 50-59 total lateral-line scales; 13½-15½ branched anal-fin rays and 7-9 gill rakers. Alburnoides freyhofi, new species, from the Kızılırmak drainage, is distinguished by having a scaleless keel between the posterior pelvic fin base and the anus, 44-53 total lateral-line scales; 14½-16½ branched anal-fin rays and 5-7 gill rakers. Alburnoides kosswigi, new species, from the Sakarya drainage, is distinguished by having a scaleless keel between the posterior pelvic fin base and the anus or rarely with 1-3 scales covering the anterior part of the keel; 43-57 total lateral-line scales; 11½-13 (14)½ branched anal-fin rays and 5-7 gill rakers.

Role of forest cover, land use change and climate change on water resources in Marmara basin of Turkey

We evaluated the influence of climate change and land use changes on water resources in the Marmara Region (Turkey) using the watershed runoff coefficients (RC) and trend analysis techniques on long-term (30 years) hydrometerological data. Land use changes in the selected sub-watersheds were obtained from CORINE land use maps for 1990, 2000, and 2006, and interpolated for annual changes. Forty-two land use types of Corine maps were grouped in four basic classes (forests, rangelands, farmlands, settlements). Principal component analysis was used to identify the most relevant land use types influencing RC since 1990. Results showed that changes in the proportion of forestlands, farmlands, and rangelands significantly affected RC. Settlements also affected RC, but to a lesser extent. RCs values for the different land use types were optimized on a subset of 28 out of the 48 sub-watersheds analyzed by minimizing the sum of least-square errors, while the remaining subset of 20 sub-watersheds was used to validate the models obtained. The R2 values for optimization and validation were 0.80 and 0.70, respectively. RCs of all watersheds were estimated for the period 1990-2012. Long-term trends in mean annual precipitation and temperature were examined by Mann-Kendall test based on time series from eight weather stations with records since 1930s. Contrasting significant trends of variation through time were found only for two stations as for precipitation, and for one station as for temperature. Overall, our results suggest that significant land use changes occurred in the region since 1990, but only slight variations in climate parameters. However, we conclude that neither land use changes nor the variation in climate parameters caused statistically significant effects on RCs and water resources.

The region of the Strandja Sill (North Turkey) and the Messinian events

The two sides of the Strandja Sill show a highly discontinuous stratigraphic succession since the Late Oligocene. This area, together with the Sea of Marmara Basin, is usually proposed as the gateway for the Paratethyan freshwaters and organisms that constituted the Lago Mare facies in the Mediterranean Sea during the Messinian Salinity Crisis (MSC). Our investigations involving new field observations and datings, together with previous studies, suggest that the sill has possibly experienced such a connection at around 8Ma, i.e. significantly before the crisis. The proposal of a sea-level drop of the Black Sea before 7Ma is not supported by our data on dinoflagellate cysts. Consistency of calcareous nannofossil succession at DSDP Site 380 is reinforced, allowing to reassert that subaerial erosion impacted both the southwestern Black Sea and the central Marmara – Dardanelles area during the peak of the MSC. At that time, this region was crossed by two oppositely directed fluvial networks, further supporting the absence of a marine gateway through the Strandja Sill. It is concluded that none of the Lago Mare events recorded in the Mediterranean during the MSC were the consequence of the passage of Paratethyan waters and organisms through this area. In the Black Sea, the well-dated Messinian fluvial erosion can be followed offshore. The overlying prograding deltaic deposits attest to a fast marine reflooding after the crisis. This constitutes a comprehensive erosion – sedimentation model in an area intensively explored for hydrocarbons.