1. The role of host specificity in explaining the invasion success of the freshwater mussel Anodonta woodiana in Europe K. Douda, M. Vrtílek, O. Slavík, M. Reichard Biological Invasions CrossRef

In the mid 1980s, the Chinese clam Sinanodonta woodiana (Lea, 1834) from SE. Asia was accidentally introduced in the Konin heated lake system (central Poland) from Hungary, along with fish stocking material.Currently, it inhabits abundantly the littoral zones of the five lakes that comprise the system, the initial cooling basin, and most of the associated intake and discharge canals.The considerable heterogeneity of its habitats in the system affects the morphological variation of its shells.The shell morphology, size, colour and growth rate are shaped by environmental factors, of which temperature, water flow intensity, and substrate type are the most important.The largest and heaviest specimens were found in the warmest habitats with the fastest water flow.Specimens with shells up to 160 mm long constituted most of the population, while in moderately heated areas the length was up to 125 mm, and in the coolest areas -115 mm.The maximum individual weight was 900 g.

In the mid 1980s the southeast Asian mussel Sinanodonta woodiana (Lea, 1834) was introduced into a lake system that is heated by power plant discharge waters (near Konin in central Poland) along with fish stocking material from Hungary. Currently, this species is abundant in the littoral zones of the five lakes in the system, the initial water cooling reservoir, as well as most of the intake and discharge canals. This species prefers a habitat with a moderate water flow rate (0.05-0.30 m s(-1)) and a relatively high water temperature (10-30 degrees C), and it usually forms aggregations. It avoids strong water turbulence and coarse sediments, although it does occur sporadically in the direct vicinity of water intake pumps and water discharge as well as on gravel substrates. The largest aggregation of Sinanodonta woodiana occurred at depths of 1.5-2.5 m. The highest number and biomass of this species was noted in the discharge canal and initial cooling reservoir where the water was the warmest. Population density sometimes exceeded 60 ind m(-2), while mussel biomass (including the shell) reached as much as 25 kg m(-2).

The zebra mussel, Dreissena polymorpha (Pall.) inhabits various live and dead substrates of the lotic and lentic zones of the heated Konin lakes. Occurring at depths from 20 cm to 3.5 m, this species showed a preference for Unionidae mussels as a substrate. Aggregations of D. polymorpha varied in number from 2 000 to 2 million individuals per m 2 , while the biomass reached more than 12 kg m -2 . The most numerous were one year old mussels 5 mm in length, which comprised from 60-80% of the population. In the preliminary cooling reservoir, newly settled post-veligers comprised as much as 94% of the total of D. polymorpha numbers. The largest mussels did not exceed 35 mm. Aggregations of D. polymorpha contained 49 invertebrate taxa, and the most frequently occurring subdominants were from the Corophidae and Gammaridae families. The diel destruction of organic matter in the aggregations varied between 20 and 370 kJ m -2 , depending on the number of animals and their biomass. The turnover coefficient (R/B) in the heated zones was 1.5 times higher, on average, than in the non-heated parts of the system.

The Chinese mussel Anodonta woodiana was accidentally introduced into the heated Konin lakes system in the mid 1980's. It inhabits the littoral of the five lakes of the complex, a preliminary cooling reservoir, and most of the discharge and inflow channels. It prefers habitats of an increased flow velocity and of rather high temperature. It has been found to be the dominant benthic species in most of the habitats. At times, its biomass exceeded 10 kg m -2 , and it numbered more than 40 individuals per m 2 .

The individual growth rate of the Chinese mussel population of the genus Anodonta which inhabits the warm channels of the heated Konin lakes system was analysed. Four size and age groups were distinguished. The allometric growth of shells during early developmental stages and the isometric growth of 6-21 cm shells were ascertained. Three to five years old individuals were typical of the Anodonta woodiana found in the Konin channels. The theoretical maximal life span of the mussels is 10 years, while the maximal shell length is 21 cm.

Lepidium sativum (cress) and Lycopersicon esculentum (tomato) plants were grown in peatlite in controlled environments with or without long-term (4 weeks) cadmium stress (Cd) (100 micrograms/ml every fourth day) and with a single exposure (6 hr at 35 parts per hundred million (pphm)) or no exposure to the oxidant ozone (O3). Cress plants which received Cd wilted faster during O3 exposure and became a gray-green color by the end of a 6-hr O3 exposure. Those receiving O3 alone also wilted but were normal in color during wilting. Leaf water content (percentage) significantly declined in both O3 + Cd- and O3-treated plants. However, leaves after Cd + O3 exposure were severely dessicated and necrotic, whereas O3-treated plants recovered their water content completely but had some injury. Increased stomatal aperture in cress but not tomato before O3 exposure and significantly lower water content at 1 and 24 hr after the end of O3 exposure were associated with the higher Cd content of leaves before and subsequent to O3 exposure. These factors contributed to a greater injury and cell death observed in the leaves of combined cadmium-oxidant stress. Dielectric properties of Thlaspi arvense (field penny cress) leaves grown at continuous exposure to Cd and/or nickel (Ni) indicated that there were measurable differences between metal-containing vs control leaves with regard to bound/unbound water status. This indicated that there was more free water under metal stress, and that the bound water content significantly declined in the leaves of these plants.

Capacitive sample holders and an automatic network analyzer are used to measure dielectric properties of biological tissues in vivo and in vitro at a controlled temperature in the frequency range of 10 kHz-100 MHz. An analysis of uncertainty is performed leading to the optimization of the sensor and the measurement system. Under optimized conditions, one sample holder can be used over the entire frequency range, and uncertainties below ±3% in the dielectric constant and ±1% in the loss factor are achieved for high water content tissues (blood, muscle, brain, liver, kidney, and spleen).

A computer-controlled scanning system and implantable, nonperturbing electric field probes were used to measure spatial distributions of the electric field in a full scale homogeneous model of a human body. The measurements were performed at three frequencies (160, 350, and 915 MHz) in the far-field and in the near-field of resonant dipoles. The specific absorption rate (SAR) distributions and the averages for body parts and the whole body are analyzed as functions of frequency. In the far-field, the SAR decreases exponentially in the direction of wave propagation in the torso at all frequencies, and large gradients of the SAR are observed along the body main axis, particularly for the E polarization. At 160 and 350 MHz high local SAR's are produced in the neck. It appears that for plane wave exposures the ratio of the peak SAR to the whole-body average SAR does not exceed 20. In the near-field, large SAR gradients are also produced, and the ratios of the peak spatial SAR to the whole-body average SAR vary from about 30 to 250 depending on the frequency and polarization. It is suggested that for near-field exposures the whole-body average SAR is not a proper dosimetric measure, and the SAR averaged over any 0.1 of the tissue volume is recommended instead.

A coaxial cell suitable for exposure of biological substances to electromagnetic fields in the frequency range from dc to 100 MHz is described. The cell provides uniform electric field throughout the exposed sample, requires a relatively small volume of the sample (typically below 1 ml), and allows for convenient control of the sample temperature.

The rate of the radio frequency energy deposition in a block model of the human body exposed in the near-field of a resonant dipole at 350 MHz was calculated using the moment method. Detailed maps of the electric field strength in a homogeneous model of a realistic shape under the same exposure conditions were obtained using a computer-controlled scanning system and an implantable electric field p...

A computer-based scanning system and implantable electric field probes were used to obtain maps of the specific absorption rate (SAR) in various cross-sections of a full-scale model of the human body. The model was exposed to a plane-wave at 350 MHz at E and k polarizations with respect to the body. Enhanced absorption in the neck and the limbs, as previously found by the thermographic method, was observed. Significant differences between the SAR distribution and the SAR values calculated using the block model and those found in this work were observed.

A computer-controlled scanning system and an implantable triaxial electric-field probe have been used to obtain maps of the specific absorption rate (SAR) in various cross sections of a full-scale model of man. The model was exposed to a 350-MHz plane wave that provided various orientations of the electric-field vector with respect to the body. The results obtained are in general agreement with previously published theoretical and experimental data. The SAR distributions in the torso and head were in relatively good agreement with cylindrical and spherical models, respectively. Enhanced absorption in the neck and the limbs, as previously found by the thermographic method, was observed. This study provides much more detailed information than previously available, with an absolute accuracy of +- 1 db.

Distributions of electric fields in lossy spheres and infinite lossy cylinders simulating biological objects were measured at 350, 920 and 2450 MHz. The measurements were performed in a computer-controlled scanning system using three different implantable nonperturbing probes. The results are compared with theory, and use of Iossy spheres and cylinders for calibration of implantable probes is quan...

An improved and modified technique with an open-ended coaxial-line sensor was used for measurement of the dielectric properties of animal tissues in vivo. The permittivity of skeletal muscle, brain cortex, spleen and liver of live cats and rats was measured at frequencies between 0.1 and 10 GHz. The results were compared with various published data on in vivo permittivity of the same and other species. The differences between the properties of the same tissue for various animals are very small. The tissues properties at frequencies above 1 GHz correlate well with the water content. Practically all water in the skeletal muscle is in the free form, while in other tissues both free and bound water are present.