Untersuchungen zur Eignung wildlebender Wanderratten (Rattus norvegicus) als Indikatoren der Schwermetallbelastung

Depot compartments which are the primary sites of pollutant enrichment in the organism can be used as bioindicators (targets) in order to identify a burden for certain elements. Background concentrations of eleven elements in tissues and organs of wild-living rats (Rattus norvegicus) obtained from a region (Euroregion Neisse, around the trilateral border region of Germany, Poland and the Czech Republic) distinguished by low to intermediate levels of environmental contaminations are given in part I of this work. In order to identify the most important depot compartments for certain elements, a body burden method was applied. Differences of affinity due to sex and age of analyzed rats are discussed, as are the suitability of specific organs and tissues with regard to bioaccumulation measurements concerning metals. The principal depot compartments for the heavy metals Cu, Mn, Cd (in adult rats) and Tl are the liver and kidneys, whereas the elements Ni, Sr, Pb (for adult animals) and Ti are more affinitivly to bones. Co and Zn displayed a more pronounced affinity towards tissues of the bones and liver. The analysis revealed large differences in Cd and Pb distributions both among young and adult rats, and with respect to sexes. It can be concluded that the distribution of the elements investigated in this study in free-living rats agrees with that in man, except for that of Ni. The above agreement gives proof of the possibility to use depot organs of rats for bioindication which was already mentioned in part I of this work (‘Sex and age-related quantification of Al, As, Cd, Co, Cu, Mn, Ni, Pb, Sr, Ti, Tl and Zn in liver, heart, lung, kidney, muscle, brain and bones and establishment of distribution patterns’).     

Amelioration of fluoride toxicity by vitamins and calcium on reproductive organs of female rat

Normal female rats of Wistar strain (Rattus norvegicus) weighing between 150–200 g were treated with fluoride (Fl) contaminated drinking water (FW, 5.8 ppm), vitamin C (6 mg) and vitamin C (6 mg) + D (6 mg once a week) + calcium (6 mg) for 30 days. Fl water treatment to rats produced reduction in weights of ovaries, uterus, vagina, kidneys, and adrenal glands, circulating levels of estrogen, number of litters, fertility rate, and altered tissue and serum biochemistry compared to control rats. However, cholesterol concentrations of ovaries and adrenals increased significantly. The above altered parameters were restored partially/completely after exogenous feeding with vitamin C and vitamins (C + D) and calcium. The data suggest that Fl-induced adverse effects on reproductive and other organs in female rats, whereas vitamin C, vitamin D and calcium treatment ameliorated Fl toxicity. Therefore, vitamins (C and D) and calcium play an important role in prophylactic treatment of fluorosis.     

Some direct observations on the ecology and behaviour of the Norway lobster Nephrops norvegicus

A detailed investigation of a small area of sea bed occupied by the Norway lobster Nephrops norvegicus (L.) was carried out by diving and television observations at depths of 30 m in Loch Torridon, Scotland. The density of burrows was 1/2 m², but only a proportion of these were occupied by N. norvegicus. Although about 70% of the larger burrows were occupied by N. norvegicus, giving a density of 1 lobster/8 m², very few juveniles (carapace length less than 30 mm) were found in the area. Many of the small burrows were occupied by the gobiid fish Lesueurigobius friesii (Collett). There was evidence that N. norvegicus frequently change their burrows, and fighting for burrows was observed. N. norvegicus remain within their burrows during the day, emerge around sunset to forage for food during the night, and then return to their burrows at dawn. This, and other aspects of their burrowing behaviour, have a marked effect on the commercial trawl catches of N. norvegicus which show large seasonal and diurnal variations in size and sex composition.     

Inter-litter competition and communal nursing among Norway rats: advantages of birth synchrony

Summary The effect of inter-litter competition on pup survival was investigated in pairs of female rats (Rattus norvegicus) living and breeding in the same environment. If a female gave birth when a 0- to 14-day-old litter was already present in the environment, her pups had a very high chance of surviving, similar to the situation in which no other litter was present. Moreover, the mother was likely to nurse communally with the mother of the 0- to 14-day-old litter. This communal nursing benefitted the newborn pups as evidenced by their being heavier at weaning than litters that were not nursed communally. In contrast, if a female gave birth when a 15-to 28-day-old litter was already present in the environment, her newborn pups were likely to die within 3 days postpartum, owing to the fact that they were often prevented from suckling at their mother's teats, resulting in milk deprivation, and were often beneath the older pups, resulting in physical trauma. These findings suggest that inter-litter competition is an important source of pup mortality when litters are born 15-28 days apart. The data are discussed in terms of the advantages of birth synchrony.     

Glutathione S-transferase activity in rats exposed to methyl parathion

Methyl parathion is an organophosphate insecticide that has been used in agriculture and the domestic sector for several years. This pesticide and others, arriving through different processes, exert significant effects on water quality with serious consequences for environmental and human health. The main objective of this study was to investigate the changes of Glutathione S-transferase enzyme activity in methyl parathion exposed rat tissues. For this purpose, wistar rats (Rattus norvegicus) were injected intraperitoneally with 7 mg kg^?1 dose of methyl parathion, while corn oil was applied to control groups in the same way. The liver, kidneys, brain and small intestine were quickly removed after 0, 2, 4, 8, 16, 32, 64, and 72 hours of injection of methyl parathion and the glutathione S-transferase activity was determined in these tissues. As a result it was seen that glutathione S-transferase activity increases in all tissues in the group of male and female rats to which methyl parathion was given. The increase of glutathione S-transferase activity may be a result of methyl parathion's toxic effect because it is one of the most important enzymes of detoxification metabolism.     

The influence of social experience on cooperative behaviour of rats (Rattus norvegicus): direct vs generalised reciprocity

Cooperation among non-kin has been attributed sometimes to reciprocal altruism: Two or more individuals exchange behaviour that benefits the respective partner. According to direct reciprocity, cooperation is based on past behaviour of a known partner. In contrast, in generalised reciprocity, cooperation is based on anonymous social experience where the identity of the partner is irrelevant. In a previous study, female Norway rats (Rattus norvegicus) were found to cooperate according to a generalised reciprocity mechanism. In this study, we tested whether Norway rats would also cooperate as predicted by a direct reciprocity mechanism and whether direct reciprocity would cause a higher propensity to cooperate than generalised reciprocity. Focal animals were experimentally manipulated to receive social experience from known or unknown, helpful or defecting partners in an instrumental cooperative task. Our first experiment shows that rats are more helpful towards a partner from which they had received help before than towards a partner that had not helped (i.e. direct reciprocity). Our second experiment revealed that after receiving help by others, rats were more helpful towards a partner from which they had received help before than towards a new partner (i.e. direct reciprocity generated a higher cooperation propensity than generalised reciprocity). We conclude that in female Norway rats, the tendency to cooperate is influenced by partner-specific information. To our knowledge, this is the first study to demonstrate direct reciprocity in rodents, and it is the first study testing direct vs generalised reciprocity in animals.     

The role of sample preparation in interpretation of trace element concentration variability in moss bioindication studies

Trace element concentrations in plant bioindicators are often determined to assess the quality of the environment. Instrumental methods used for trace element determination require digestion of samples. There are different methods of sample preparation for trace element analysis, and the selection of the best method should be fitted for the purpose of a study. Our hypothesis is that the method of sample preparation is important for interpretation of the results. Here we compare the results of 36 element determinations performed by ICP-MS on ashed and on acid-digested (HNO₃, H₂O₂) samples of two moss species (Hylocomium splendens and Pleurozium schreberi) collected in Alaska and in south-central Poland. We found that dry ashing of the moss samples prior to analysis resulted in considerably lower detection limits of all the elements examined. We also show that this sample preparation technique facilitated the determination of interregional and interspecies differences in the chemistry of trace elements. Compared to the Polish mosses, the Alaskan mosses displayed more positive correlations of the major rock-forming elements with ash content, reflecting those elements’ geogenic origin. Of the two moss species, P. schreberi from both Alaska and Poland was also highlighted by a larger number of positive element pair correlations. The cluster analysis suggests that the more uniform element distribution pattern of the Polish mosses primarily reflects regional air pollution sources. Our study has shown that the method of sample preparation is an important factor in statistical interpretation of the results of trace element determinations.     

Trace elements and vanadium in tissues and organs of five species of cetaceans from Italian coasts

Trace element concentrations (chromium, copper, zinc, iron, manganese and vanadium) were determined in organs of five species of cetaceans (Stenella coeruleoalba, Tursiops truncatus, Grampus griseus, Physeter macrocephalus, Ziphius cavirostris) that were found stranded along Italian coasts in the period 2000–2009. This dataset represents an important opportunity to verify and assess (particularly for V) patterns of incorporation of trace elements in different organs of cetaceans in a wide spectrum of species and related specimens distributed in all the age classes, and consequently determine the physiological and metabolic effects on the distribution modes of the same chemicals. In particular, Cu, Zn, and Fe accumulate preferentially in the liver of all studied specimens, while Mn and Cr values are found to be nearly constant in the analysed organs and tissues regardless of species. Comparable concentrations of trace elements, in different age classes, were measured for both specimens of S. coeruleoalba and T. truncatus (the most abundant dolphin species in the Mediterranean sea) in all analysed organs. On the other hand, unprecedented reported concentrations of V in tissues and organs of cetaceans from the Mediterranean show higher values when compared to levels measured in other marine mammals from the Atlantic Ocean.     

A bilateral gynandromorph of Nephrops norvegicus (Decapoda: Nephropidae)

A bilateral gynandromorph specimen of Nephrops norvegicus (L.) from the Irish Sea is described. Previous records of gynandromorphs within the Nephropidae are discussed, together with other types of sexual abnormality found in N. norvegicus. It is suggested that the bilateral asymmetry is due to a chromosomal aberration in the first embryonic cleavage division, and that further division is determinate. In addition, it appears that the androgenic gland in N. norvegicus, Homarus gammarus and H. americanus does not have the same mode of action as that reported for Orchestia gammarella and O. cavimana.     

Variations in the elemental compositions of plants,and computer‐aided sampling in ecosystems∗

To obtain comparable results of multi‐element analysis of plant materials by different laboratories, a harmonized sampling procedure for terrestrial and marine ecosystems is essential. The heterogeneous distribution of chemical elements in living organisms is influenced by different biological parameters. These parameters are mainly characterized by genetic predetermination, seasonal changes, edaphic and climatic conditions, and delocalization processes of chemical substances by metabolic activities.

The biological variations of the element content in plants were divided into 5 systematic levels, which are: 1. the plant species; 2. the population; 3. the stand (within an ecosystem); 4. the individual; and 5. the plant compartment. Each of these systematic levels can be related to: 1. genetic variabilities; 2. different climatic, edaphic and anthropogenic influences; 3. microclimatic or microedaphic conditions; 4. age of plants (stage of development), exposure to environmental influences (light, wind, pollution etc.), seasonal changes; and 5. transport and deposition of substances within the different plant compartments (organs, tissues, cells, organelles).

An expert system for random and systematic sampling for multi‐element analysis of environmental materials, such as plants, soils and precipitation is presented. After statistical division of the research area, the program provides advice for contamination‐free collection of environmental samples.     

Metal accumulation by three Tilapia spp. from some Egyptian inland waters

Five trace metals (Cu, Zn, Fe, Mn and Cd) were determined in different tissues and organs (muscle, liver, brain, gills, gonads and intestines) of some Tilapia spp. (Oreochromis spp. and Sarotherodon galilaues) collected from two Egyptian Lakes (Edku and Mariut, exposed to different types of pollutants), El-Umum Drain, and from the fishing farm El-Nozha Hydrodrome. Our results indicate that metal accumulation in different organs vary considerably between the same and among different Tilapia spp. There is a preferential accumulation of metals by different organs. Liver is a target organ for Cu accumulation, whereas the brain and flesh tissues clearly accumulate more levels of Zn than the other studied elements. Amongst the studied elements, Cd concentrations in the different organs are the lowest. It was found that edible parts of Tilapia spp. collected from Lake Mariut accumulate the highest levels of the studied elements (Fe, Zn, Mn and Cu for S. galilaues and Cd for Oreochromis niloticus), compared with those in the other studied areas. In general, the levels of Cd (0.0–0.11?ppm), Cu (0.25–1.85?ppm) and Zn (3.58–8.46?ppm) in the edible parts of studied fish cannot be considered as hazardous levels.     

Small-scale spatial and temporal interactions among benthic crustaceans and one fish species in the Bay of Biscay

In the summer of 2004, a video survey was carried out in the northern part of the central mud bank (Grande Vasière) of the Bay of Biscay to study the small scale relationship between the dominant crustacean megafauna Nephrops norvegicus, Munida rugosa and Goneplax rhomboides and juvenile hake (Merluccius merluccius). Using a towed body, high-resolution videos were recorded in six sampling sites. Statistical modelling using generalised additive models (GAM) revealed variations in activity patterns for two species. More N. norvegicus were observed outside their burrows at dawn and somewhat at dusk (no observations during night) while G. rhomboides was less observed in the morning. In addition, reduced spatial overlap between G. rhomboides and N. norvegicus suggested reduced competition for food but also space as both are burrowing species. The observed temporal and spatial activity patterns may contribute to regulating assemblage structure as competing species may be actively foraging at different times and locations thus reducing direct competition.     

Löwenzahn Taraxacum officinale Web. als (städtischer) Bioindikator

Investigations of the dandelion, Taraxacum officinale Web. in Poland, Romania and Germany showed that the species concentrates various elements dependent on the intensity of the pollutants. In this study, we followed up the question of whether T. officinale enriches pollutants by the atmospheric deposition on the leaves or via the soil. Therefore, samples from at least 10 plants and a soil sample at 57 sample sites were collected from a grid of 500 m × 500 m. In addition to the analysis of the total soil sample, the (mobile) ion pool of the soil (DIN V 19739) was analysed. The elements Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, K, Mg, Mn, Mo, Na, Ni, Rb, Sr, Ti, Tl, V, and Zn were determined through the use of spectrometry with inductive coupled plasma (ICP-MS and ICP-OES). The results are compared with the element concentrations of washed and unwashed leaf samples in T. officinale. We could only find two direct correlations (Ti and Zn) between the element content, of the entire soil samples, but 14 correlations (As, Ba, Cd, Cu, Ga, K, Mn, Mo, Na, Ni, Rb, Ti, Tl und Zn) between the ion pool of the soil and the washed samples. The grid point data interpolation by ArcInfo showed a similar distribution pattern for the unwashed leaf elements Al, Ce, Fe, Ti and V (r≥0.75). The elements Al, Ce, Fe, Ti, and V are washed out at the same ratio. Thus, although the concentration of these elements were significantly reduced by the washing procedure, the correlations were not influenced. The admissibility of the grid point data interpolation for a distribution map of the town area was investigated, as well. It is shown that the element content varies with the land use (meadow, field, rural areas), the sampling point and the local pollutants. However, none of the discussed elements, Al, Ce, Fe, Ti, and V, is significantly influenced by the land use. The data allows one to make the conclusion that the elements of Al, Ce, Fe, Ti and V are dependent on the dry and wet deposition on the leaves of T. officinale. These elements are taken up not only by the roots, but also by the surface of the leaves. This is evident because there is no correlation between one of these elements in the leaves and the ion pool of the soil.     

Swimming performance and endurance of the Norway lobster Nephrops norvegicus

The swimming behaviour of the Norway lobster, Nephrops norvegicus (L.), was studied in the laboratory. The lobsters were stimulated to swim repeatedly until they failed to respond to a single tactile stimulus. The position of the initiating stimulus on the body determined the height of the escape path above the bottom of the tank. A stimulus to the rostrum resulted in a low swimming trajectory, rarely exceeding a height of 0.1 m. A similar tactile stimulus to the abdomen produced higher mean swimming trajectories up to 0.5 m. Several parameters of swimming performance and endurance were measured for each swimming sequence, including distance, duration, mean and maximum velocities and the frequency and number of tail beats. Results showed no significant differences in the average swimming performance and endurance of males and females, but there was a sex difference in the relationship between swimming performance and N. norvegicus size.     

Observations on the burrows and burrowing behaviour of two mud-dwelling decapod crustaceans,Nephrops norvegicus and Goneplax rhomboides

The burrows of the Norway lobster Nephrops norvegicus (L.) and of the crab Goneplax rhomboides (L.) were studied in Loch Torridon, Scotland. Polyester resin casts of burrows in the sea were made by divers to reveal their subsurface form. Tunnels made by N. norvegicus were usually simple, with two or more openings on the mud surface, and penetrated to a depth of about 30 cm. G. rhomboides burrows did not descend more than about 15 cm beneath the surface, but were usually more complex than the lobster burrows and had several openings. The methods of burrow construction used by the two crustaceans are described from aquarium observations. Neither N. norvegicus nor G. rhomboides show obvious morphological adaptations for burrowing, and it is suggested that the fossorial habit was adopted very early by decapods. The burrows of N. norvegicus do not seem to have assumed any functions in addition to the original one of providing refuge from predators. There is not sufficient known of the biology of the crab to indicate whether the same is true in its case.     

Survival and growth of the Norway lobster Nephrops norvegicus in relation to light-induced eye damage

 The long-term survival and growth of Norway lobsters, Nephrops norvegicus (L.), were examined in relation to light-induced retina breakdown. The incidence of eye damage was first assessed in tagged N. norvegicus released in Loch Torridon, on the west coast of Scotland between 1978 and 1983. Of 34 recaptures examined, all but four showed evidence of eye damage, varying in extent from 1 to 63% of the retina. Additional tagged N. norvegicus were released in Loch Torridon in 1984 and 1985 in order to compare recapture and growth rates in lobsters with and without eye damage. Three groups of N. norvegicus were released; normal sighted, partially sighted (median retina damage = 68%) and fully blinded (retina damage = 100%). From 1217 lobsters released, 235 were recovered by September 1992, when the experiment was concluded. The final proportions of N. norvegicus recaptured were found to be independent of eye-damage condition, and there was no evidence that growth rate was affected by eye damage. Combining all categories of releases, the overall proportion of females recaptured (0.244) was significantly greater than the proportion of males (0.145), suggesting better long-term survival in females than in males. At the time of release, ∼80% of the females were carrying recently spawned eggs. Although the proportion of berried females in the recaptures was slightly reduced in the two eye-damaged groups compared with the normal sighted group, the difference was not statistically significant. It is concluded that light-induced eye damage in N. norvegicus is irreversible, but such damage does not seem to influence their long-term survival, growth or reproduction. Received: 21 October 1998 / Accepted: 26 October 1999     

Effect of aerial exposure on concentrations of selected metabolites in blood of the Norwegian lobsterNephrops norvegicus (Crustacea: Nephropidae)

The Norwegian lobsterNephrops norvegicus (L.) collected from Firth of Clyde, Scotland between December 1987 and March 1988, was unable to survive longer than 18 h experimental emersion at 10°C. During this time the partial pressure of oxygen (P O₂) in the venous blood decreased rapidly and the lobster supplemented cellular energy requirements by anaerobic metabolism. This was indicated by the rapid accumulation ofL-lactate in the blood. Although the survival rate increased (to ca 36 to 48 h) if lobsters were kept on ice, the accumulation ofL-lactate in the blood was not significantly different from lobsters at 10°C, despite the temperature difference. There was no indication thatN. norvegicus was able to further metabolize circulatingL-lactate during emersion. On emersion there was also a marked hyperglycemia in the blood due to the stress of handling and asphyxiation. There was fairly good agreement between results obtained during laboratory studies and simulated fishing activity in the Firth of Clyde. Both sets of results are discussed in the context of adaptation to air breathing within the Crustacea and an assesment of post-harvest treatment of lobsters.     

Locomotory behaviour and swimming performance of the Norway lobster,Nephrops norvegicus,in the presence of an acoustic tag

Observations have been made on the locomotory behaviour and swimming performances of the Norway lobster, Nephrops norvegicus (L.), fitted with an acoustic transmitter ventrally under the cephalothorax. The walking behaviour of adult males (44 mm carapace length) appeared to be unaffected, but the tag caused significant reductions in certain measures of tail-flip swimming performance such as swimming speed and endurance. Flume-tank experiments in low water currents suggested that the transmitter would increase hydrodynamic drag during swimming by 9 to 32%, depending on lobster size. Given the weight and dimensions of the acoustic transmitters currently available, it is considered advisable to confine acoustic tracking studies to relatively large N. norvegicus.Correspondence to: C. J. Chapman     

Between-individual variation in haemocyanin concentrations in the Norway lobster<Emphasis Type="Italic"> Nephrops norvegicus</Emphasis> following exposure to hypoxia and manganese

Environmental hypoxia and the release of reduced manganese (Mn) are often combined stress factors in marine sediments. Previous investigations have shown that hypoxia induces variable responses in the concentration of the respiratory pigment haemocyanin (Hc) of crustaceans. A recent study demonstrated that the magnitude and direction of the changes was dependent on the initial level of Hc in individuals of the Norway lobster Nephrops norvegicus. The changes also took place within 24 h rather than days as suggested by previous studies. In this present study we investigated changes of Hc in individual N. norvegicus in uncontaminated sea water after exposure to and release from realistic hypoxic stress (PO ₂=6.0 kPa). Furthermore we investigated how concomitant exposure to realistic concentrations of manganese (20 mg l ^-1) modified the responses we observed. We confirmed a between-individual variation in response and a change in Hc towards an optimum level after hypoxia, but also showed that changes that took place post-hypoxic exposure occurred over a timescale similar to that of the hypoxic response itself. Manganese exposure resulted in no significant changes in Hc whereas Mn exposure combined with hypoxia resulted in a significant decrease (15%) in all individuals independent of initial Hc. N. norvegicus was thus unable to compensate for the effects of hypoxia by synthesis of Hc after exposure to naturally occurring Mn concentrations.     

High copper concentrations in squid livers in association with elevated levels of silver,cadmium, and zinc

Livers from 43 Loligo opalescens, 14 Ommastrephes bartrami, and 7 Symplectoteuthis oualaniensis were analyzed for their silver, cadmium, copper, zinc and iron contents. Copper concentrations of up to 15,000 μg/g dry weight were found in L. opalescens in conjunction with significant correlations between this element and Ag, Cd and Zn. The latter elements are known to affect Cu metabolism in terrestrial organisms; however, whether the correlations occurring in marine organisms represent casual, or cause and effect, relationships is as yet unknown.