Northeastern Mediterranean Sea Research Articles

Diversity of polycystine radiolarians in sediment traps from the Ionian, North Aegean and Cretan Seas: A preliminary account: Diversité des radiolaires polycystines dans des pièges à sediments des mers ionienne, nord-égéenne et de Crète: un rapport préliminaire

The presence and diversity of polycystine radiolarians in the North-Eastern Mediterranean Sea is explored for the first time through the analysis of sinking particles obtained from sediment traps moored in three open marine sites. In total, thirty species are identified for which we provide appropriate references and illustrations to clarify the species concept followed in this study; 13 of the identified species are Spumellarians, 16 are Nassellarians and one is an Entactinarian. The highest diversity is recorded in the Ionian site, in which 23 species were observed during November 2014, with approximately as many Nassellarian species as Spumellarians; a large number of species are in common with the fauna reported from the Adriatic Sea, off Dubrovnik, but interestingly, 16 others are not. The lowest levels of radiolarian diversity, with 3 to 4 species at best, were observed in the north Aegean and Cretan Sea sites. Our observations improve also the paleobiogeographic knowledge of two polycystine species, one of which (Gonosphaera primordialis Jørgensen) was known previously from the high latitudes of both the northern and southern hemisphere and the other (Qiuripylolena chikuchik Zhang and Suzuki) from the Pacific ocean.

Riverine Microplastic Loading to Mersin Bay, Turkey on the North-eastern Mediterranean

Microplastics sampled downstream from a total of eight rivers were analysed as the first attempt to determine microplastic composition in rivers and load to Mersin Bay, in the north-eastern Mediterranean Sea. With a share of 83.5%, fibres were the dominant category from all samples. Basic characteristics (form, colour, average size, polymer) of microplastics from these rivers were similar to those reported from the marine environment in Mersin bay. The overall average number of microplastics calculated for the eight rivers was determined as 293±59 particles/m3 equalling a load of 1200 billion items (mainly from the Göksu River) discharged annually to the north-eastern Mediterranean. This value equivalent to twice the total stock of microplastics within the water column in Mersin Bay, demonstrates that rivers are a primary source of microplastics pollution for the coastal seas.

Proximate Composition, Fatty Acid and Amino Acid Profiles of Narrow-Barred Spanish Mackerel (Scomberomorus commerson) Fillets from İskenderun Bay in The North-Eastern Mediterranean Sea

The present study aims to determine the proximate, fatty acid and amino acid profiling of consumed fresh narrow-barred Spanish mackerel (Scomberomorus commerson). Landed fish were freshly sampled (total length 33.7-48.7 cm and weight 617-1260 g) from the Yumurtalık Bay (north-eastern Mediterranean Sea) in Turkey during January, February and March. The protein values were highest in January (22.89%) while the and lowest in February (21.38%) and March (21.73%). Lipid and ash values were not significantly differencing among sampling time. The fatty acid data revealed that the saturated fatty acid values were found higher than the polyunsaturated and monounsaturated fatty acid values. In general, the fillets were abundant in palmitic acid (C16:0), stearic acid (C18:0), oleic acid (18:1n-9) and docosapentaenoic acid (C22:6n-3; DHA) values, regardless of the sampled months. DHA value was recorded as 315.08 mg 100g-1 in January, while it increased to 327.55 mg 100g-1 in the March samples. A total of 16 amino acids were determined from the fresh fillets. Compared with the other essential amino acids, the concentration of lysine and leucine were found to be higher in the fillet. At the same time, the lower rates of tryptophan were detected in examined samples for all months. Consequently, this study shows that the narrow-barred Spanish mackerel as a finfish (commercially valuable) from the north-eastern Mediterranean Sea has precious nutritional values that of the protein, fatty acids and amino acids during the sampling period. This fish can be recommended in terms of detected essential fatty acid and amino acid profile that completely nutritious for the human as well as other organisms’ dietary requirements.

Effects of seasonal changes and depth on growth parameters of the Mediterranean mussel (Mytilus galloprovincialis) on a shipwreck in the Eastern Mediterranean Sea

AbstractThe study was conducted between July 2018 and May 2020 to compare seasonal changes in growth parameters of the Mediterranean mussel (Mytilus galloprovincialis) at different depths in two different areas of the Northeastern Mediterranean Sea (Aegean Sea). In a preliminary study, mussels were placed in cages at different depths of an artificial reef (AR – shipwreck) and natural reef (NR). Temperature, salinity, pH, and dissolved oxygen were determined seasonally at both sites at a depth of 37 m (deepwater) and 25 m (midwater). Linear increases in length and width of mussels at the AR site were recorded, while no consistent changes were observed for mussels at the NR. There was negative correlation between the specific growth rate (SGR) and salinity (r2= 0.5098) and temperature (r2= 0.1470) at the AR site. Negative correlations were also recorded between pH and the commercial condition index (CCI) at both the AR (r2= 0.3869) and NR (r2= 0.3600) sites. Our findings show that depth had a significant effect (p< 0.05) on theCCIof mussels at the NR site, while its effect was insignificant for this index at the AR site (p> 0.05). This study indicates that natural reefs provide more suitable conditions for the growth of Mediterranean mussels than shipwrecks used as artificial reefs.

Ecosystem trophic structure and fishing effort simulations of a major fishing ground in the northeastern Mediterranean Sea (Thermaikos Gulf)

Ecosystem modelling constitutes a useful tool for the ecosystem approach to fisheries management, which demands a shift to more complex models that include multi-species trophic interactions, environmental and anthropogenic forcing. The Thermaikos Gulf is a shallow gulf in the northwestern Aegean Sea (Greece) and one of the major fishing grounds of the northeastern Mediterranean concentrating high fishing effort of trawlers and purse-seiners and producing more than 20% of the total Greek catches. In the present work, we developed an Ecopath base model and ran Ecosim simulations for 26 years (2000–2025), including the calibration period (2000–2016), aiming to describe the food web structure and function of the Thermaikos Gulf, identify main components and interactions among the 33 functional groups, assess the ecosystem impacts of fishing over time, and compare ecosystem properties with other Mediterranean areas. Overall ecosystem degradation with biomass and catch decline was observed at the end of the calibration period due to the impact of environmental factors and fishing activities. The ecosystem seemed to stabilize in an intermediate state by the end of the projection years, but with an overall biomass and catch decline. Fishing effort reduction after 2016 resulted in higher biomass and catches compared to 2014–2015, that could not however reach the 2000 levels in most cases. The examined fishing effort reduction scenarios clearly showed that the more the fishing effort is reduced, the higher the biomass in the ecosystem and the lower the catches obtained compared to the baseline scenario. In a nutshell, since environmental drivers may be harder to predict or control, lowering the exploitation levels is an important step towards the rebuilding of overfished marine resources and more resilient ecosystems.

Distribution and ten-year temporal trends (2009–2018) of perfluoroalkyl substances in gull eggs from Spanish breeding colonies

Gull eggs are excellent bioindicators of environmental pollution as reflect the contamination levels of coastal areas, especially of persistent and bioacumulative compounds such as perfluoroalkyl substances (PFAS). This study aims to evaluate the geographical distribution and 10-year temporal trends (2009–2018) of 17 PFAS in eggs of two gull species (Larus michahellis and Larus audouinii) from 5 main Spanish colonies. ∑PFAS ranged from 13.7 ± 5.9 to 164 ± 17 ng g−1 wet weight and higher concentrations were observed in L. audouinii than in L. michahellis. Perfluorooctane sulfonate (PFOS) was the predominant compound in all samples, followed by perfluoroundecanoic acid (PFUnA) and perfluorotridecanoic acid (PFTriDA). Perfluorododecanoic acid (PFDoA), perfluorodecanoic acid (PFDA) and perfluorooctanoic acid (PFNA) were also found in all studied areas but at lower concentrations, while perfluorooctanoic acid (PFOA) was only detected in the Medes Islands. Principal Component Analysis revealed the co-occurrence of the 6 detected PFAS, and differentiated samples from Ebro Delta and Medes Islands, both located in the North-Eastern Mediterranean Sea, with high contribution of all PFAS, from Chafarinas and Atlantic Islands with lower concentration levels and variability. Also, different patterns were observed among colonies, suggesting the fish-based diet plays an important role in PFAS bioaccumulation. In all colonies, except for the Medes Islands, ∑PFAS decreased through the 10-year study period, with PFOS, PFUnA, and PFTriDA showing a significant concentration reduction in a colony-specific manner. This study demonstrates the usefulness and importance of continuous systematic long-term monitoring to determine the geographical distribution and temporal variations of PFAS in marine protected areas using gull eggs as bioindicators of environmental pollution.

Life-history traits of the marbled electric ray, Torpedo marmorata Risso, 1810, from the Greek Seas, north-eastern Mediterranean Sea

Life-history traits of the marbled electric ray, Torpedo marmorata Risso, 1810, from the Greek Seas, north-eastern Mediterranean Sea

Age and Growth of Red Sea Goatfish, Parupeneus forsskali from Iskenderun Bay, Northeastern Mediterranean Sea

Age and Growth of Red Sea Goatfish, Parupeneus forsskali from Iskenderun Bay, Northeastern Mediterranean Sea

Mapping the seismic noise field in Europe: spatio-temporal variations in wavefield composition and noise source contributions

SUMMARYWe study spatial and temporal characteristics of the microseismic noise field across Europe. Rather than focusing on the areas of noise generation, the scope of this work is to characterize, at the scale of Europe, the spatio-temporal evolution of the noise wavefield that results from the interplay of the seismic noise sources and the propagation effect. To that end, we perform single station analysis in three period bands (PB1: 2.5−5 s; PB2: 5−10 s and PB3: 10−20 s) using three-component seismic data recorded by ∼1000 broad-band stations in the time period 2011–2019. We calculate, for each period band, station and day, a set of parameters that are practically possible to apply to a large data set, yet yields insight into the spatio-temporal evolution of the wavefield. These parameters are: the total energy level, the dominant period of the Primary and Secondary microseismic peaks, the horizontal direction with the most energy, the horizontal direction of the dominant Rayleigh waves and the square root of the energy ratio between the horizontal and vertical components. The analysis of these parameters shows that the noise field in Europe is dominated by surface waves from the North Atlantic Ocean with, in PB1 and PB2, an additional and significant contribution from the eastern part of the Mediterranean Sea. The relative contribution of these two source regions depends on the season, the influence of the eastern Mediterranean Sea being strongest in summer. The map of the peak period of the Primary and Secondary microseismic peaks indicates that the relative contribution of these two source regions is frequency dependent: the period of the Primary microseismic peak exhibits an overall increase with distance to the North Atlantic Sources, because of stronger attenuation of high-frequency wave contents. By contrast, the period of the Secondary microseismic peak is simultaneously influenced by sources in both the North Atlantic Ocean and eastern Mediterranean Sea. We show that in both microseismic peaks (PB2 and PB3), the wavefield is dominated by Love waves, as the horizontal components have the highest energy at approximately 90° angle to the direction of elliptical polarization. Moreover, our results show that lateral heterogeneities in the crust have a major influence on the noise field. In particular, the propagation directions of Love and Rayleigh waves show strong dependency on location (but not on time of year), with very sharp boundaries for example at the edge of the Alps. Thus, the scattering that takes place in the heterogeneous Alpine crust partly randomizes the directions of the microseismic wavefield in particular in PB1 and PB2. Finally, we show that the temporal evolution of the amplitude ratio between the horizontal and vertical components reflects the relative amounts of surface waves from the North Atlantic Ocean with respect to body waves from sources in the Southern Hemisphere. Thus, this ratio can be used as a proxy to identify time periods where body waves are significant in the noise wavefield.

Recent Occurrence of Shortfin Mako Shark, Isurus oxyrinchus Rafinesque, 1810 (Chondrichthyes: Lamnidae), from the North-Eastern Mediterranean Coast of Turkey

A young individual of Isurus oxyrinchus was caught by a commercial longline off Dana Island (Mersin Bay, northeastern Mediterranean Sea) at a depth of 72 m on May 18th 2020. Morphometric measurements of the specimen were recorded and its photographs were taken. The examined specimen is now being preserved in the Museum of Systematics at Faculty of Fisheries of Mersin University, under the reference number MEUFC-20-11-132. This occurrence of a young female specimen reported in this study is adding a new location (Mersin Bay) from the Mediterranean's Turkish waters.

Assessment of some heavy metal accumulation and potential health risk for three fish species from three consecutive bay in North-Eastern Mediterranean Sea

Due to rapid urbanization and industrialization especially near water resources, heavy metal pollution in both water and inland environments have been studied all around the world. In this study, some selected heavy metals (Al, Sr, Cd, Co, Ni and, Pb) and fish species (Mullus barbatus, Solea solea, and Siganus rivulatus) from three Bays (İskenderun, Mersin, and Antalya from North-Eastern Mediterranean Sea) were used for heavy metal accumulation level evaluation and health risk assessment on both general and fish populations. A variety of accumulation patterns for considered metals were observed in tissues. Significant (p<0.05) inter- and intraspecies/tissues/bays differences were detected. The most stable tissue in terms of Al and Sr accumulation was determined as muscle. For Cd, Co and Ni accumulation the most stable tissue was found as liver. Lastly, for Ni accumulation skin was found to be the moststable tissue. The Target Hazard Quotients (THQ) and Total Target Hazard Quotients (TTHQ) values based on muscle were not exceeded 1.00. Therefore, these results suggest that both general and fish populations are not subjected to the significant potential health risk from those bays.

The First Occurrence of the Pen Shell Pinna nobilis (Linnaeus, 1758) in the Samandağ coast, the northeastern Mediterranean

Pinna nobilis is distributed in the northwest area of the Mediterranean and the Aegean Sea. In this study, on 9 September 2020, one specimen of Pinna nobilis, the pen shell, was observed during scuba diving at a depth of 16 m off Samandag coast (36.259444° N, 35.810111° E), the northeastern Mediterranean Sea. In this study, we observed for the first time P. nobilis from the Mediterranean Coast of Turkey, the Samandag coast. In this region, the presence of P. nobilis has never been previously recorded, and this new record confirms the presence of a new location in the Mediterranean Sea.

Rarely Reported Cryptobenthic Fish in Marine Caves of the Eastern Mediterranean Sea

Data on the distribution and ecology of cryptobenthic fish of marine caves in the Mediterranean Sea are extremely scarce but necessary for scientists and marine managers alike in order to understand these fish’s ecological role and assess their conservation status. Broadscale surveys by implementing underwater visual census and photographic sampling in marine caves of the northeastern Mediterranean Sea, within different expeditions during the last 5 years, brought to light new records of eight rarely reported cryptobenthic fish species. To a smaller extent, complementary citizen science data from diving professionals of Crete were used to fill distribution gaps. A total of 36 new records (66 individuals) from 18 marine caves and caverns of the Aegean and northeastern Levantine Seas were assembled, belonging to the gobies Corcyrogobius liechtensteini, Didogobius splechtnai, Gammogobius steinitzi, and Thorogobius ephippiatus, the blenny Microlipophrys nigriceps, the tripterygiid Tripterygion melanurum, the speleophilic bythitid Grammonus ater, and the gobiesocid Lepadogaster cf. lepadogaster. The above species have been rarely reported from the Eastern Mediterranean Sea, with D. splechtnai and G. steinitzi being recorded for the first and second time from Greek waters, respectively, while L. cf. lepadogaster constitutes the second record of a clingfish species in a marine cave of the Aegean Sea. Interesting behavioral and ecological habits were also noted for some species, based on in situ observations and photographic evidence. Our study contributes to filling gaps in the knowledge of cave fish diversity and demonstrates that cryptobenthic mobile species in understudied cryptic habitats are more common than previously thought in the Mediterranean Sea.

A Lessepsian invader round herring (Etrumeus golanii) with high genetic diversity without bottlenecking in the northeastern Mediterranean Sea

A Lessepsian invader round herring (Etrumeus golanii) with high genetic diversity without bottlenecking in the northeastern Mediterranean Sea

Lithistid Demosponges of Deep-Water Origin in Marine Caves of the North-Eastern Mediterranean Sea

Desmas-bearing demosponges known as lithistids have heavily silicified skeleton and occur typically in bathyal environments of warm and tropical areas but may be found in certain shallow marine caves. Here we report, for the first time two lithistid species, i.e., Neophrissospongia endoumensis, and N. cf. nana, that were earlier known from Western Mediterranean marine caves, from four marine caves in the north-eastern Mediterranean, and their congener Neophrissospongia nolitangere from deep waters (ca. 300 m) of the Aegean Sea. All marine caves, and sections within these caves, where lithistids occur, have freshwater springs. We interpret this surprising association between lithistids and freshwater input by elevated concentration of silica in water in cave sections where such springs occur, being 8–11 times higher in comparison with shallow water outside caves, and comparable to that of deep waters, that promoted lithistids’ development. One of the studied caves harbored an abundant population of N. endoumensis which formed large masses. The age estimation of these lithistids, based on known growth rate of related deep-water sponges, suggest that they could be approximately 769–909 years old in the case of the largest specimen observed, about 100 cm large. These sponges could have colonized the caves from adjacent deep-water areas not earlier than 7,000–3,000 years ago, after the last glaciation, because earlier they were emerged. High variability of spicules, especially microscleres, and underdevelopment of megascleres may be related to silicic acid concentration.

Some Deep-Sea Cephalopods from the Northeastern Mediterranean Sea (Mersin Bay, Turkey)

Some Deep-Sea Cephalopods from the Northeastern Mediterranean Sea (Mersin Bay, Turkey)

Some Deep-Sea Cephalopods from the Northeastern Mediterranean Sea (Mersin Bay, Turkey)

Deep-sea sampling was conducted by a commercial trawl in the International Waters of Mersin Bay between 14 and 17 May 2018. The sampling depth ranged between 274 and 641 meters. A total of 13 trawling operations were performed, and each trawling operation lasted approximately 4 hours. During the sampling, six of the deep-sea cephalopods species were caught. All specimens were preserved in ethyl alcohol and were deposited in the Museum of the Systematic, Faculty of Fisheries, Mersin University (Catalog no: MEUCC-18-11-2- MEUCC-18-11-7). A total of two cuttlefish species belonging to the families of Sepiidae were identified. The others were represented by the families of Sepiolidae, Octopodidae, Bathypolypodidae, and Ommastrephidae.

Future losses of ecosystem services due to coastal erosion in Europe

Coastal erosion is a major issue facing Europe that will only worsen under future climate change and the resulting sea level rise. One effect of erosion is the loss of ecosystem services, which are provided by coastal areas, such as provisioning, regulating, habitat, and cultural services. These services can be quantified in monetary terms. Here, we present comprehensive estimates of future decline in coastal ecosystem services due to the erosion of sandy coastlines. We used datasets derived from remote sensing products: a pan-European land cover/use dataset (Corine Land Cover) and new global probabilistic coastal erosion projections constrained by artificial and topographical barriers to erosion. The results include historical changes (2000–2018) and projections under two emission scenarios (RCP4.5 and RCP8.5) for 2050 and 2100 together with uncertainty bounds. We estimate that in 2018, the coastal zone (excluding open sea) included 579,700 km2 of habitats generating 494 billion euros of services annually. The future sea-level rise could erode 1.0% [90% confidence interval 0.7–1.5%] of the 2018 area under RCP4.5, and 1.2% [0.7–2.2%] under RCP8.5. The decline in services would be even greater: 4.2% [3.0–6.1%] under RCP4.5, and 5.1% [3.3–8.5%] under RCP8.5. The highest absolute losses would be sustained by salt marshes, while relative losses would be highest in beaches, sands, and dunes. The most affected countries in relative economic terms would be Denmark, Albania, Greece, Estonia, and Finland, but countries such as Germany, the Netherlands, and France would be among those losing the largest share of their coastal ecosystem services. Regional analysis using NUTS 3 regions shows high diversity of the impacts, with many regions along the North Sea and eastern Mediterranean Sea that are heavily affected by coastal erosion-induced loss of ecosystem services. The study highlights the urgency of undertaking mitigation actions.

Evidence of a second nursery area of the sandbar shar, Carcharhinus plumbeus (Nardo, 1827) in the Eastern Mediterranean Sea

The sandbar shark (Carcharhinus plumbeus) is a large coastal species with a cosmopolitan distribution that has been listed as Endangered in the Mediterranean Sea and as Vulnerable for the rest of the world on the IUCN Red List of threatened species. The Gökova's Boncuk Cove in south-western Turkey and the Gulf of Gabès in southern Tunisia are the only known nursery area for the Mediterranean population. On 24 – 27 July 2017, eight specimens, four males and four females, of sandbar sharks were accidentally caught at a depth of 7 to 9 m by a pelagic bluefish longline off the coast of Yumurtalik Bight in the Gulf of Iskenderun. The total length and weight of males and females were 54.5 – 61.0 cm, 930 – 1,484 g and 49.6 – 62.4 cm, 918 – 1,568 g, respectively. They all had unhealed umbilical scars that were still open as a narrow slit, measuring 4.35 and 5.39 mm in lengths. This study thus provides the records of the neonate sandbar sharks from the Yumurtalik Bight. Consequently, this occurrence represents that this area of the north-eastern Mediterranean Sea can be the second breeding and nursery grounds for this species after the Boncuk Cove in Gökova Bay in Turkey.

The Comparison of Heavy Metal Level in Surface Water, Sediment and Biota Sampled from the Polluted and Unpolluted Sites in the Northeastern Mediterranean Sea

The determination of heavy metal level (aluminium, iron, zinc, arsenic strontium) in surface water, sediment, and biota in Iskenderun Bay, polluted site, and Mersin Bay, unpolluted site, in 2018–2019 seasonally were aimed. The muscle and liver (viscera for shrimp) tissue of three fish (Saurida lessepsianus, Nemipterus randalli, Mullus barbatus) and an invertebrate (Penaus semisulcatus) species, which have different habitats and diet, were used to detection of biota metal level. Sediment samples were analyzed in four different particle sizes which were Fe > As>Al > Zn and Sr > Fe > As>Zn > Al respectively. (p Al > Sr > Zn > As in both sampling sites. The sediment Zn levels were a negative relationships between biota, particle size, sampling sites and season (p As> Zn > Sr > Al and As≥ Fe > Zn > Sr > Al, while the liver metal level sampled from polluted and unpolluted sites were Fe > Zn > As>Al > Sr and Fe > Zn > As>Sr > Al, respectively. There were significant of metals between species and tissues (p 0.05). Iron accumulated in the liver more than the muscle tissue while arsenic accumulated in the muscle more than the liver tissues due to the functional difference of tissues (p < 0.05). The tissue metal level was high abundant in the polluted site. Fe was at the highest level in biota and sediment from both regions may be due to industrial activities in the polluted site whereas agricultural activities or discharged by the Goksu River in the unpolluted site.