The role of winter phenology in shaping the ecology of freshwater fish and their sensitivities to climate change

Thermal preference and performance provide the physiological frame within which fish species seek strategies to cope with the challenges raised by the low temperatures and low levels of oxygen and food that characterize winter. There are two common coping strategies: active utilization of winter conditions or simple toleration of winter conditions. The former is typical of winter specialist species with low preferred temperatures, and the latter is typical of species with higher preferred temperatures. Reproductive strategies are embodied in the phenology of spawning: the approach of winter conditions cues reproductive activity in many coldwater fish species, while the departure of winter conditions cues reproduction in many cool and warmwater fish species. This cuing system promotes temporal partitioning of the food resources available to young-of-year fish and thus supports high diversity in freshwater fish communities. If the zoogeographic distribution of a species covers a broad range of winter conditions, local populations may exhibit differences in their winter survival strategies that reflect adaptation to local conditions. Extreme winter specialists are found in shallow eutrophic lakes where long periods of ice cover cause winter oxygen levels to drop to levels that are lethal to many fish. The fish communities of these lakes are simple and composed of species that exhibit specialized adaptations for extended tolerance of very low temperatures and oxygen levels. Zoogeographic boundaries for some species may be positioned at points on the landscape where the severity of winter overwhelms the species’ repertoire of winter survival strategies. Freshwater fish communities are vulnerable to many of the shifts in environmental conditions expected with climate change. Temperate and northern communities are particularly vulnerable since the repertoires of physiological and behavioural strategies that characterize many of their members have been shaped by the adverse environmental conditions (e.g. cool short summers, long cold winters) that climate change is expected to mitigate. The responses of these strategies to the rapid relaxation of the adversities that shaped them will play a significant role in the overall responses of these fish populations and their communities to climate change.     

Dynamics of the circulation in the Sea of Marmara: numerical modeling experiments and observations from the Turkish straits system experiment

During September 2008 and February 2009, the NR/V Alliance extensively sampled the waters of the Sea of Marmara within the framework of the Turkish Straits System (TSS) experiment coordinated by the NATO Undersea Research Centre. The observational effort provided an opportunity to set up realistic numerical experiments for modeling the observed variability of the Marmara Sea upper layer circulation at mesoscale resolution over the entire basin during the trial period, complementing relevant features and forcing factors revealed by numerical model results with information acquired from in situ and remote sensing datasets. Numerical model solutions from realistic runs using the Regional Ocean Modeling System (ROMS) produce a general circulation in the Sea of Marmara that is consistent with previous knowledge of the circulation drawn from past hydrographic measurements, with a westward meandering current associated with a recurrent large anticyclone. Additional idealized numerical experiments illuminate the role various dynamics play in determining the Sea of Marmara circulation and pycnocline structure. Both the wind curl and the strait flows are found to strongly influence the strength and location of the main mesoscale features. Large displacements of the pycnocline depth were observed during the sea trials. These displacements can be interpreted as storm-driven upwelling/downwelling dynamics associated with northeasterly winds; however, lateral advection associated with flow from the Straits also played a role in some displacements.     

Speciation and Determination of Inorganic Mercury and Methylmercury by Headspace Single Drop Microextraction and Electrothermal Atomic Absorption Spectrometry in Water and Fish

In this study, headspace single drop microextraction (HS‐SDME) method in combination with electrothermal atomic absorption spectrometry (ETAAS) method was developed and validated for the speciation and determination of inorganic mercury (iHg) and methylmercury (MeHg). MeHg and iHg species were reduced to volatile methylmercury hydride (CH₃HgH) and elemental mercury, respectively, in the presence of NaBH₄ and trapped onto a drop of acceptor phase in the tip of a microsyringe. Thiourea and ammonium pyrrolydinedithiocarbamate (APDC) were tested as the acceptor phase. The experimental parameters of the method such as microextraction time, temperature, NaBH₄ concentration, acceptor phase concentration, and pH of the medium were investigated to obtain distinctive conditions for mercury species. Possible interference effects have also been investigated. In order to validation of the method, analytical figures of merits such as accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), and linear working range have been evaluated. Accuracy of the method has been verified by analyzing certified reference materials (BCR 453 Tuna fish) and spiked samples. The proposed method was applied for the speciation and determination of mercury species in water and fish samples. Mercury species (MeHg and iHg) have been determined in the real samples with a relative error less than 10%.     

Fluoride Biomonitoring around a Large Aluminium Smelter Using Foliage from Different Tree Species

In order to study the pollution gradient in the vicinity of a large aluminium production facility in Patagonia (Argentina), a passive biomonitoring was performed employing foliage from three tree species. Primary scope was to identify pollution gradients and to select suitable tree species which can be used as biomonitor plants in the study area. Therefore, leaves of Eucalyptus rostrata, Populus hybridus and different needle ages of Pinus radiata were collected at different distances from the industry and the fluoride concentration was analysed in washed and unwashed samples in order to determine the amount of external fluoride. Washing reduced the F‐concentrations by 24, 39 and 51% on average in E. rostrata, P. hybridus and P. radiata, respectively, indicating that species‐specific characteristics determine the accumulation and wash‐off of dust‐associated fluorine. F‐concentrations varied from 6 to 3652 ppm F in unwashed samples indicating a steep pollution gradient in the study area. The influence of F‐emissions was discernible in all samples up to a distance of 3500 m from the smelter. E. rostrata accumulated more fluorine than the other species at equal distance from the emission source. The present study confirms that aluminium smelting results in high F deposition in the study area. Establishing a biomonitor network around large emitters is suitable and feasible to evaluate the efficiency of air control measures.     

Lentil Straw: A Novel Adsorbent for Removing of Hazardous Dye – Sorption Behavior Studies

Sorption behavior of Lanaset Red (LR) G on lentil straw (LS) was studied as a function of particle size, adsorbent dose, initial pH value, initial dye concentration, and contact time. Sorption kinetics data was well described by logistic model. Modified logistic equation can be used to explain effects of initial dye concentrations and contact time on the sorption of LR G with high R² value. Freundlich model was found to be excellent in representing the equilibrium data. Thermodynamic parameters like free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) were calculated by the use of Langmuir constant. Thermodynamic data showed that the sorption processes were spontaneous and endothermic in nature. Desorption process suggested that strong binding and weak interactions could be formed between adsorbent surface and dye molecules. Results revealed that LS has a remarkable potential for the sorption of LR G.     

Spatial variations of precursory seismic quiescence observed in recent years in the eastern part of Turkey

A statistical analysis is made for the eastern part of Turkey in the beginning of 2009 by studying the phenomenon of seismic quiescence as a potential precursor of the main shocks. The results produced four areas having seismic quiescence in the beginning of 2009. These areas are observed to be centered at 39.96°N–40.69°E (around A?kale, Erzurum), 39.36°N–39.74°E (around Ovac?k, Tunceli), 39.02°N–40.52°E (including Elaz?? and Bingöl), and 38.45°N–42.94°E (Van Lake). Based on the recent results showing 5 ± 1.5 years quiescence before the occurrence of an earthquake in this region, the future earthquake would be expected between 2009.5 and 2010.5. The future earthquake occurrence may reach 2012 if we consider the standard deviation of average seismic quiescence as ±1.5 years. We have found that the M _W = 6.0 Elaz?? earthquake on 8 March 2010, followed a seismic quiescence starting about 5 years before the main shock. Thus, special interest should be given to the other regions where the seismic quiescence is observed.     

A review of EU bio-economic models for fisheries: The value of a diversity of models

The lessons learned from a review of thirteen existing European bio-economic models used in the evaluation of EU policies are presented. How these models compare and differ in terms of their biological and economic components, the integration between the components, which indicators are selected and how they are used, are described and analysed. The article concludes that the multitude of construction differences reflects the necessity of adapting the modelling approach to answer different questions. Since real life questions in fisheries are so diverse, answering them requires a diversity of models.     

Inversion of two-dimensional tidal open boundary conditions of M<Subscript>2</Subscript> constituent in the Bohai and Yellow Seas

Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE) after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.     

Morphometric and molecular data on two mitochondrial genes of a newly discovered chimaeran fish (Hydrolagus melanophasma, Chondrichthyes)

Fresh and preserved (type material) specimens of the black ghost chimaera Hydrolagus melanophasma were compared for morphometric characteristics. A molecular comparison was also performed on two mitochondrial gene sequences (12S rRNA and 16S rRNA gene sequences). While significant differences in measurements were found, the differences were not attributable to sexual dimorphism or the quality of the specimens, but to the sample size and the type of statistical tests. The result of the genetic characterization showed that 12S rRNA and 16S rRNA genes represented robust molecular markers that characterized the species.