| 1. |
- Dahlgren, Kristin, 1979-, et al.
(författare)
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Influence of plankton structure and temperature on pelagic food web efficiency in a brackish water system
- 2011
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Ingår i: Aquatic Ecology. - : Springer Science and Business Media LLC. - 1386-2588 .- 1573-5125. ; 45, s. 307-323
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Tidskriftsartikel (refereegranskat)abstract
- As part of one climate change scenario, water temperature as well as the ratio between heterotrophic and autotrophic production is expected to increase; the latter at least in higher latitudes. In order to test how this scenario would affect organisms, such as metazooplankton, at higher trophic levels and carbon transfer up the food chain, a mesocosm experiment was performed at two different temperatures; 5 and 10°C, with two food webs; one phytoplankton-based (NP; autotrophic) and one bacteria-based (CNP; heterotrophic). The groups of pelagic organisms included in the mesocosms were bacteria, flagellates, ciliates, phytoplankton and metazooplankton. Metazooplankton production was observed to increase with temperature, but was not significantly affected by food web structure. A change in food web structure, i.e. increased heterotrophy, did however lead to decreased fatty acid content and lower individual weight of the metazooplankton. Food web efficiency (FWE), defined as metazooplankton production divided by basal production, increased with autotrophy and temperature: 5CNP (0.2%) < 10CNP (0.4%) < 5NP (1.2%) < 10NP (7.3%). Our results indicate that in the climate change scenario under consideration, the temperature will have a positive effect on FWE whereas the increase in heterotrophy will have a negative effect on FWE. Furthermore, the quality, in terms of fatty acid content and individual weight of the metazooplankton, will be reduced with possible negative effects on higher trophic levels.
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| 2. |
- Andrén, Cecilia M., et al.
(författare)
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Response of Gammarus pulex and Baetis rhodani to springtime acid episodes in humic brooks
- 2013
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 463, s. 690-699
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Tidskriftsartikel (refereegranskat)abstract
- While chronic acidification of water bodies has been steadily decreasing, episodic acidification continues to affect stream biology by temporarily decreasing pH and mobilizing aluminum. These events are becoming more common as climate change renders more frequent and intense storms and flooding. Throughout Scandinavia, the effects of acidification have been mitigated by liming since the 1980s, but remediation efforts can now be reduced. While transient acidity may reduce fish populations, also other species in streams are affected. In this in-stream study, two macro-invertebrates (Gammarus pulex and Baetis rhodani), both known as salmonid prey organisms, were exposed to snowmelt in six humic brooks with a natural gradient of pH and inorganic monomeric Al (Al-i). We hypothesize that acid toxicity thresholds can be defined using lethal (mortality) and sublethal (changes in body elemental content) metrics. Periodic observations were made of mortality and whole body concentrations of base cations (BC: Ca, Mg, Na and K) and metals (Al, Fe, Zn and Mn). Mortality increased dramatically at pH < 6.0 and Al-i > 15 mu g/L for G. pulex and at pH < 5.7 and Al-i > 20 mu g/L for B. rhodani. No accumulation of Al was found. The invertebrate body Na concentration decreased when pH dropped, suggesting that osmoregulation in both species was affected. In contrast to general BC pattern, Ca concentration in G. pulex and Mg concentration in B. rhodani increased when pH decreased. Although Ali strongly correlates to pH, the Al composition of soil and bedrock also influences Al availability, potentially contributing to toxic Al; episodes. The estimated values calculated in this study can be used to improve water quality criteria and as thresholds to adjust doses of lime compared to old recommendations in ongoing liming programs. Such adjustments may be critical since both Ali and pH levels have to be balanced to mitigate damage to recovering stream ecosystems.
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| 3. |
- Andrén, Cecilia M., 1964-
(författare)
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Toxicity of Inorganic Aluminium in Humic Streams
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aluminium (Al) has been recognised as a main toxic factor alongside pH in acidified water ecosystems. The toxic effect of Al has been attributed to inorganic Al (Ali), though there are few in situ studies in ambient humic waters which are the focus of this thesis.The aim was to estimate Ali toxicity and thus also Ali concentrations in Swedish humic streams. Subsequently it is necessary to analyse Ali correctly, which was studied by modelling and method intercalibrations. The hypothesis was that the effect of Ali could be followed via physiological effects and Al accumulation, as well as by mortality. Toxicity was studied by in stream exposures of brown trout (Salmo trutta L.) and two salmonid prey organisms (Gammarus pulex and Baetis rhodani) during spring flood.The modelling of the Ali fraction was performed using monitoring data covering all of Sweden with satisfactory results. The essential variables for Ali modelling were determined; Al, DOC, pH and F, while Fe, Ca and Mg had less effect. The automated analytical procedure for Ali (with cation exchange followed by complexation with pyrocatechol violet) was modified and validated and showed to be the preferred method for laboratory analyses.To avoid detrimental effects for brown trout Ali should be <20 µg/L and pH >5.0; mortality was high when the Ali was above 50 µg/L. The invertebrates were more sensitive, as mortalities occurred at pH <6.0 and Ali >15 µg/L for G. pulex, and at pH <5.7 and Ali >20 µg/L for B. rhodani. It is prudent to use a wide view and let the most sensitive species set the tolerance limits; a pH above 5.7-6.0 and Ali below 15-20 µg/L allows the stream ecosystems to thrive.Today, as waters are recovering from acidification, the aim of mitigating liming is to carefully adjust dosage to avoid suboptimal water quality. The thresholds found in this thesis can be used to efficiently but carefully decrease liming, as both Ali and pH levels have to be balanced to sustain the recovering aquatic biota.
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| 4. |
- Dahlström, Lisen Arnheim, et al.
(författare)
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Prospective seroepidemiologic study of human papillomavirus and other risk factors in cervical cancer
- 2011
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 20:12, s. 2541-2550
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Tidskriftsartikel (refereegranskat)abstract
- Background: Several sexually transmitted infections (STI) have been reported to interact with human papillomavirus (HPV) in the etiology of cervical cancer. A large cohort study is required to obtain a both unbiased and stable estimate of their effects. Methods: Four major biobanks in the Nordic Countries containing samples from about 1,000,000 subjects were linked with nation-wide cancer registries. Serum samples from 604 women with invasive cervical cancer (ICC) diagnosed on average 10 years after sampling and 2,980 matched control women were retrieved and analyzed with serology for key STI. Results: Exposure to HPV16 was the strongest risk factor for cervical cancer [ OR = 2.4; 95% confidence interval (CI), 2.0-3.0], particularly for squamous cell carcinoma (OR = 2.9; 95% CI, 2.2-3.7). HPV18 was strongly associated with increased risk for adenocarcinoma (OR = 2.3; 95% CI, 1.3-4.1). Baseline seropositivity for HPV16 did not confer any increased risk for HPV18 DNA-positive cancer and conversely HPV18 seropositivity had no association with HPV16 DNA-positive cancers. HPV6 had no effect on its own (OR = 1.1; 95% CI, 0.9-1.3), but had an antagonistic effect on the risk conferred by HPV16 (P < 0.01). Herpes simplex virus 2 had little or no association (OR = 1.1; 95% CI, 0.8-1.4). Previous exposure to Chlamydia trachomatis, as indicated by serum antibodies, had a strongly increased risk for cervical cancer (OR = 1.9; 95% CI, 1.5-2.3). Conclusions: A large prospective study has assessed the role of different STIs in cervical cancer. Impact: Prospective evidence supports cofactor role of some STI in cervical cancer. Cancer Epidemiol Biomarkers Prev; 20(12); 2541-50. (C) 2011 AACR.
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| 5. |
- Eriksson Wiklund, Ann-Kristin, et al.
(författare)
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Behavioural and physiological responses to pharmaceutical exposure in macroalgae and grazers from a Baltic Sea littoral community
- 2011
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 14:1, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- Gammarus spp. and Fucus vesiculosus from the Baltic Sea littoral community were exposed to 3 concentrations of the pharmaceuticals ibuprofen and propranolol. Both physiological and behavioural parameters were measured to examine potential effects in the organisms. For Gammarus spp., respiration, feeding rate and activity with and without predator cues were measured, and gross production to respiration ratio (GP/R) and chlorophyll fluorescence were measured for F. vesiculosus. The results showed that propranolol decreased the activity related to movement, and Gammarus spp. could not compensate for the reduced movement when subjected to predator cues. The feeding rates of Gammarus spp. exposed to propranolol were more than 2 times higher at all concentrations compared to the control. Ibuprofen did not significantly affect any of the measured parameters of Gammarus spp. The GP/R was lower in algae exposed to propranolol. The effects of propranolol on both behaviour and physiology of Gammarus spp., in combination with the stress responses in the algae, might cause unexpected indirect and cascade effects which eventually could have implications at both community and ecosystem scales.
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| 6. |
- Eriksson Wiklund, Ann-Kristin, et al.
(författare)
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Benthic competition and population dynamics of Monoporeia affinis and Marenzelleria sp in the northern Baltic Sea
- 2014
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 144, s. 46-53
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Tidskriftsartikel (refereegranskat)abstract
- During the last two decades major changes of the benthic fauna have occurred in the northern Baltic Sea, the Gulf of Bothnia. The native amphipod, Monoporeia affinis, has shown a large-scale abundance decrease, while polychaetes, Marenzelleria spp. have invaded the system. Marenzelleria co-exist with the native fauna in the southern Baltic Sea, but in the north the pelagic production might be too low to allow co-existence. Thus, M. affinis might have been out-competed by Marenzelleria in the Gulf of Bothnia. This hypothesis was tested in a competition experiment with a high and a low fresh phytoplankton food supply. When exposed to high food supply both species showed stable or increased biomass over the four week test period. In low food supply, however, M. affinis was found to have a competitive advantage. The experimental data were also related to Baltic Sea monitoring data on primary production, sedimentation and invertebrate abundances. Data from the northern Baltic Sea show that the dominance in the benthic community by M. affinis was replaced by Marenzelleria around 2001. The amphipod decrease might be explained by a marked decrease in primary production during this period. Combining monitoring and experimental data suggests that the invasion of Marenzelleria did not cause the decrease of M. affinis in the northern Baltic Sea; it rather took advantage of the density gap that had occurred. A shift may thus have been established in the Bothnian Sea benthic community.
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| 7. |
- Fernández-Varea, José M., et al.
(författare)
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Limitations (and merits) of PENELOPE as a track-structure code
- 2012
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 88:1-2, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To outline the limitations of PENELOPE (acronym of PENetration and Energy LOss of Positrons and Electrons) as a track-structure code, and to comment on modifications that enable its fruitful use in certain microdosimetry and nanodosimetry applications.Methods: Attention is paid to the way in which inelastic collisions of electrons are modelled and to the ensuing implications for microdosimetry analysis.Results: Inelastic mean free paths and collision stopping powers calculated with PENELOPE and two well-known optical-data models are compared. An ad hoc modification of PENELOPE is summarized where ionization and excitation of liquid water by electron impact is simulated using tables of realistic differential and total cross sections.Conclusions: PENELOPE can be employed advantageously in some track-structure applications provided that the default model for inelastic interactions of electrons is replaced by suitable tables of differential and total cross sections.
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| 8. |
- Furuhagen, Sara
(författare)
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Integrative approaches in ecotoxicological testing: Implications for biomarker development and application
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ecotoxicology aims to understand toxic effects of chemicals in the environment. Effects can be observed at different levels of the biological organization, from molecular to ecosystem level. Biomarkers on molecular and biochemical levels are used in ecotoxicology as early warning signals of chemical exposure, possible toxic effects and underlying mechanisms. As methods and technologies improve, more biomarkers are being implemented in ecotoxicological studies, due to the general interest in early detection and thus efficient prevention of environmental risks. However, to be of value in ecotoxicological assessment, a connection between biomarker response and effects at higher levels of biological organization should be established. Also, baseline variability for the biomarker in question as well as response to natural fluctuations of environmental factors should be evaluated.The aim of this thesis was to increase value and understanding of biomarkers in ecotoxicological assessment by (1) linking responses across different levels of biological organization, and (2) gaining better understanding of the relative importance of ecological and physiological factors affecting oxidative biomarkers.Paper I is focused on evolutionary conserved drug targets and the toxicity of pharmaceuticals for non-target organisms. The main conclusion from this study is that pharmaceuticals with conserved drug targets in non-target organisms have a higher toxicity than pharmaceuticals for which drug-targets have not been identified in the species. The effects were evaluated using end points at molecular, biochemical and individual levels. Consistent with the expected higher sensitivity of molecular and biochemical end points, the effects on the low-level biomarkers were observed at lower concentrations than at the individual level. Paper II is focused on delineating effects of feeding and toxic exposure on oxidative biomarkers commonly used in ecotoxicology. The results are in agreement with the theory of caloric restriction that links enhanced caloric intake to increased pro-oxidative processes in animals. In our experiments with the cladoceran Daphnia magna, we observed positive effects for both antioxidant capacity and oxidized lipids in response to enhanced feeding rates. This have implications for the use of oxidative stress biomarkers in ecotoxicology as many substances have inhibitory effects on feeding rate and thus, changes in oxidative biomarkers can result from the altered feeding rate rather than other toxic mechanisms. Therefore, possible changes in feeding rate should be assessed when conducting exposure experiments or interpreting field data in studies employing oxidative stress biomarkers. However, it was concluded that the ratio between antioxidative capacity and protein content was independent of feeding rate. Thus, this biomarker is suitable for xenobiotic exposure in D. magna. This thesis have contributed to better understanding of molecular and biochemical biomarkers in ecotoxicological studies in regard to the connections between effects at different biological levels and confounding factors in biomarker response.
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