Ecotoxicology,where do you come from and where do you go? (2 pp)

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Does ecotoxicology really contribute to our knowledge about the function of an ecosystem or environment? Is ecotoxicology really a science of its own? The answers to these questions must be NO. The reasons lie in the origin and past of ecotoxicology.Like medicine, ecotoxicology does not have its own scientific theory, but rather borrows from other disciplines: the scientific theory of medicine is biology, and that of ecotoxicology is ecology and pharmacology. Neither medicine nor ecotoxicology see the normal status and routine function of their objects under study. Ecotoxicology regards the environment as being adversely impacted by anthropogenic noxes, mainly chemicals, perhaps based on a paradigm of permanent guilt.

     

Dissipation of oxytetracycline, chlortetracycline, tetracycline and doxycycline using HPLC-UV and LC/MS/MS under aquatic semi-field microcosm conditions

A mixture of four tetracyclines; oxytetracycline (OTC), chlortetracycline (CTC), tetracycline (TC), and doxycycline (DC) was applied in fifteen 12000l outdoor microcosms at four treatment levels plus controls each with three replicates (n = 3). The dissipation times of parent compounds were monitored and half-lives (DT50) of 1-4 days, depending on treatment level were recorded. This is in accordance with half-lives from previous findings in bench-top experiments. Parent compound DT50, were determined using HPLC-UV. Furthermore, the samples were analyzed for ten different tetracycline products using LC/MS/MS. Two products were found for chlortetracycline; 4-epi-anh-chlortetracyline and the iso-chlortetracycline. Iso-forms were only found for CTC and only at the highest treatment (300 microg l(-1)). The half-lives, trajectories, and relative amounts of the products were analogous for all four tetracyclines. DT50 for products were less than 1.2 days. Formation of 4-epi-anh-tetracyclines, occurred at neutral to weak alkaline conditions.     

Occurrence of the carcinogenic Bracken constituent ptaquiloside in fronds,topsoils and organic soil layers in Denmark

Bracken (Pteridium aquilinum (L.) Kuhn) is a common fern found on all continents except Antarctica. It is under suspicion of causing cancer among people who utilizes it as food. The main carcinogenic compound is thought to be the water-soluble compound ptaquiloside. Ptaquiloside-uptake may occur not only through food, but also via drinking water as ptaquiloside might leach from plant material. The purpose of the study was to identify environmental parameters that correlate with the ptaquiloside-content in fronds, and to quantify the amount of ptaquiloside in the soil environment. The ptaquiloside-content in fronds, Oi/Oe-, and Oa/A-horizons was quantified at end of the growth season at 20 sites in Denmark. The fronds had ptaquiloside-contents between 108 and 3795 microgg(-1). The Oi/Oe-horizons had contents between 0.09 and 7.70 microgg(-1), while Oa/A-horizons had contents between 0.01 and 0.09 microgg(-1). The ptaquiloside-content in the standing biomass, which could be transferred to the soil by the end of the growing season, ranged between 10 and 260 mgm(-2), with nine sites having ptaquiloside loads over 100 mgm(-2). The carbon-content in the O-horizon, the precipitation, the amount of Bracken-litter, the turnover rate and the size of Bracken-stands determined the ptaquiloside-content in the soil materials while the content in fronds was found to be a function of the frond-height and the light-exposure in the ecosystem.     

Artificial indoor streams as a method to investigate the impact of chemicals on lotic communities

The potential hazard of chemicals on aquatic communities are generally evaluated by standardised single-species bioassays. Safety assessment is based on results gained from organisms adapted to lentic systems and biological interactions in ecosystems are neglected. While lotic communities are often at first in contact with chemicals, it is astonishing that microcosms with lentic communities are mainly used as a bridge between laboratory bioassays and outdoor aquatic systems. Hence, we established five artificial indoor streams to simulate abiotic factors of small rivers. The closed-circuit system was filled with nutrients added to tap water. Washed pebbles were used as sediment. The dynamics of a simple biocoenoses consisting of aufwuchs, Lumbriculus variegatus Asellus aquaticus and Gammarus fossarum was investigated. The dynamic of aufwuchs and periphyton was determined as dry weight and chlorophyll-a, respectively and qualitatively by pigment pattern. The abundance of different developmental stages of L. variegatus was determined at the end of the experiment as well as the population dynamics of G. fossarum and A. aquaticus. Survival rates of gammarids and juveniles per female were investigated and data were used for modelling the population dynamics. The experiment was carried out to investigate the performance of the established artificial streams and the developed approaches to investigate effects of chemicals on a basic lotic community. The prime reason to establish this approach was to close a gap between complex artificial stream systems and laboratory single species tests to assess the impact of chemicals on the aquatic environment.     

OH-initiated oxidation of DMS/DMSO: reaction products at high NOx levels

Dimethylsulphide (DMS) gas phase oxidation with OH radicals was investigated by long path FT-IR spectroscopy and by ion chromatography (IC) and HPLC-MS2 to quantify the reaction products and evaluate heterogeneous processes. The experiments were performed considering two different NOx (NO2+NO) levels. The initial concentration of NO2 was varied from 24 ppbV (NOx=1 ppmV) to 953 ppbV (NOx=10 ppmV). Photolysis of H2O2 was used as the OH-radical source. SO2, dimethylsulphoxide (DMSO), dimethylsulphone (DMSO2), methanesulphonic acid (MSA), methanesulphinic acid (MSIA) and methane sulphonyl peroxynitrate (MSPN) were identified as the main sulphur-containing products. The results indicate that higher NOx levels play a significant role in the chemistry of CH3S(O)x radical, influencing both the SO2/MSPN ratio and the amount of the sulphur species in the condensed phase, and that the NO2/NO ratio could influence the trends in the molar yields of the different products. For this reason the NOx content results a limiting parameter when on measure DMS in atmospheric environment.     

Cyst-based toxicity tests XVI--sensitivity comparison of the solid phase Heterocypris incongruens microbiotest with the Hyalella azteca and Chironomus riparius contact assays on freshwater sediments from Peninsula Harbour (Ontario,Canada)

In view of the complexity and costs of "traditional" whole sediment assays, a "culture/maintenance free" direct contact microbiotest has been developed with the freshwater ostracod Heterocypris incongruens. The new Toxkit assay (named Ostracodtoxkit) has been applied to 33 sediment samples from Peninsula Harbour, located in Lake Superior of the Great Lakes water basin in Ontario, Canada. The microbiotest was applied in parallel to direct contact tests with the amphipod Hyalella azteca and the midge larva Chironomus riparius, to compare its relative sensitivity with that of the two "conventional" assays. The study was undertaken in the framework of remediation action plans for specific areas of concern, to enable decision making by the Canadian authorities for the restoration of impacted aquatic environments. Most sediments were found non-toxic (<20% mortality) to both the conventional test species and the ostracod. For the large majority of samples, a very good correspondence was found between the two crustacean test species for the intensity of the toxic signal "mortality", as reflected by a 0.71 (p<0.05) correlation coefficient. Growth inhibition, which is determined in the ostracod microbiotest as a sublethal effect criterion, allowed the earmarking of some sediment samples, which were apparently more toxic for the amphipod than to the ostracod. For 20% of the samples, substantially higher mortality scores were noted with the ostracod assay than with the midge larvae tests and the overall correlation coefficient between these two tests was lower (r=0.60,p<0.05). The results obtained in the present study corroborate those of previous research on sediments collected from various rivers in Flanders, Belgium, and confirm the potential of the new ostracod microbiotest as a reliable and sensitive low cost alternative for traditional whole sediment assays.     

Reproduction and larval development in three scalpellid barnacles, Scalpellum scalpellum (Linnaeus 1767), Ornatoscalpellum stroemii (M. Sars 1859) and Arcoscalpellum michelottianum (Seguenza 1876), Crustacea: Cirripedia: Thoracica): implications for reproduction and dispersal in the deep sea

We studied reproduction and larval development in three species of pedunculated barnacles with different depth distribution, that is, Scalpellum scalpellum (30–200 m), Ornatoscalpellum stroemii (100–1,600 m) and Arcoscalpellum michelottianum (64–5,190 m). Morphology, position and number of males in the female/hermaphrodite, type of larval development and the number and size of eggs were recorded. All three species have a pair of pocket-like receptacles, each of which can host only a single male in O. stroemii, up to five males in S. scalpellum and up to 12 males in A. michelottianum. Eggs and larvae were smallest in S. scalpellum, intermediately sized in O. stroemii and largest in A. michelottianum. Brood size was comparable for S. scalpellum and O. stroemii, but five times higher in A. michelottianum. The ratio for body/egg size is almost similar in S. scalpellum and A. michelottianum, but much smaller in O. stroemii. Both S. scalpellum and A. michelottianum have nauplii that spend upwards of 10 days in the plankton while the larvae of O. stroemii hatch as cyprids that settle soon after release. All these reproductive data indicate that O. stroemii invests considerably more in each propagule than the other two species. We hypothesize that the observed differences in reproductive system and mode of development in the three species represent adaptations to their different habitats. S. scalpellum are mainly transported by currents in the coastal sublittoral zone. O. stroemii is presumably spread by intermediate deep currents along the shelf and shelf-slope, while A. michelottianum occurs on seamounts and is probably transported by demersal currents over wide areas of inhospitable soft-bottoms. Our observations are in accordance with the general pattern that, egg-size and propagule-size are positively correlated to bathymetric and geographic distribution, and that the continental slope environment represents a high disturbance environment, where a short larval stage is an advantage.     

Wirkung subakuter PCB-Exposition (Aroclor 1254) auf Sauerstoffverbrauch, Schwimmbewegung und Biotransformation (GST-Aktivität) des Karpfens (Cyprinus carpio)

Objective and Background

PCB (polychlorinated biphenyle) are typical man-made environmental pollutants that cause a broad spectrum of effects in vertebrates. Although a lot has been studied about the toxic effects of xenobiotic substances on aquatic organisms, their subacute effects are not yet well known. Fish occupies a central position in freshwater food webs and therefore, carp was chosen to be our test organism. The aim of our study was the investigation of subacute effects of Aroclor 1254 (22μg ^l?1) on respiration, swimming activity, and biotransformation, allowing discussion of changed interaction between the available energy resources.

Methods

The respiration experiments under controlled laboratory conditions were run for 29 days (5 d before, 16 d with and 8 d after chemical exposure) with exposed carp compared to the non-exposed fish. Furthermore, the BehavioQuant system quantitatively monitors the positions of each individual fish before (8 d) and during (21 d) PCB exposure and swimming activity (number of horizontal turnings s^?1) of animals was calculated. Thereafter, liver samples were taken from animals for analysis of the phase 2 enzyme activity (glutathione-S-transferase). In the respiration experiments were 6 exposure, 6 controll, and 3 solubilizer controll groups (12 animals each group); in the behavioral experiments were 9 exposure, 6 controll- und 3 solubilizer controll groups (6 animals each group), and in the enzyme activity measurements were 9 exposure, 6 controll and 3 solubilizer controll groups (6 animals each group) examined.

Results and Discussion

A clearly increased (33%) oxygen consumption due to the PCB-exposure is found to be reversible; after the exposure period the respiration of carp shows a level comparable to the oxygen consumption during non-exposure time. By evaluating quantitative behavioral parameters of animals, it becomes evident that the exposure to PCB also causes a reversible change in their swimming behavior. Chemical stress leads to a decrease of mean daily swimming activity combined with an increase of the mean number of turnings during the night. Thereafter, the swimming activity shifts to the circadian swimming behavior under control conditions. Furthermore, our measurement of soluble and microsomal glutathione-S-transferase activity of fish liver shows a significant elevation after exposure period.

Conclusion

Our results prove that it was feasible to detect sublethal effects of PCB-mixture on all parameters under these conditions successfully. Our findings imply that fish are able to cope with the chemicals and we purse the hypothesis that the higher physiological energy demand caused by increased activity of enzymes, which are involved in biotransformation of foregin substances, may be related to a higher respiration of fish stressed by xenobiotics.

Recommendation and Outlook

Further experiments should investigate the effects of PCB on ecophysiological parameters of carp fed with exposed natural food allowing discussion of ecological consequences.     

Voluntary conservation of endangered species: when does no regulatory assurance mean no conservation?

Voluntary conservation agreements are becoming increasingly important in implementing the Endangered Species Act on private land. We analyze when such agreements arise and what level of conservation they generate in the presence of uncertainty about future conservation benefits and irreversibility of habitat loss and species extinction. Our results suggest that the likelihood of an agreement and the resulting conservation levels depend on the background threat of regulation, the cost advantage offered by voluntary agreements, and the availability of assurances regarding future regulation. Under conditions likely to hold in practice, conservation agreements that offer assurances may generate higher levels of conservation and higher net social benefits than agreements that do not offer assurances. However, the resulting level of conservation will not be optimal, and may be lower than that attainable under regulation.     

Regulation of parental effort in a long-lived seabird an experimental manipulation of the cost of reproduction in the antarctic petrel,Thalassoica antarctica

Summary The fitness of a parent in an altricial bird species is likely to be a function of the proportion of resources allocated to offspring production in relation to the amount spent on its own survival. Here we report an experiment on the Antarctic petrel in which we manipulated the costs of rearing an offspring by placing small lead loads on the legs of one parent. The bird could then either decrease its own body reserves or reduce the food load to the chick. The manipulated birds decreased their food load and increased the feeding interval, compared with unmanipulated birds. Consequently, the rate of chick loss increased. No significant difference was found between the body weights of experimental and control birds during the experiment.Publication no. 113 from the Norwegian Antarctic Research Expedition (NARE) 1989/90 Correspondence to: B.-E. Sæther