| 1. |
- Gorokhova, Elena, et al.
(författare)
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Nucleic acid levels in copepods : dynamic response to phytoplankton blooms in the northern Baltic proper
- 2007
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 349, s. 213-225
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Tidskriftsartikel (refereegranskat)abstract
- We examined changes in nucleic acids and concomitant population development of the copepods Acartia bifilosa and Eurytemora affinis in relation to the progress of the phytoplankton spring bloom in the northern Baltic proper. Individual RNA and DNA concentrations and their ratios in female copepods as well as copepod abundance and population structure were analyzed in 2 coastal areas that differed in the degree of eutrophication and phytoplankton development. During the study period (February to June 2002), bloom conditions were evident, with chlorophyll (chl) a values being 42% higher in the eutrophic area than in the reference area. In both areas, diatoms dominated; in the reference area, they were replaced by dinoflagellates toward the end of the bloom. Copepod RNA-DNA concentrations increased rapidly at the onset of the bloom and gradually decreased thereafter. Moreover, in the eutrophic area, both copepods had higher RNA content and RNA:DNA ratios throughout the study period, suggesting higher productivity in this area. In both species, we found positive correlations between RNA-based indices and chl a. Thus, as suggested by RNA dynamics, growth rates of A. bifilosa and E. affinis appear to respond rapidly to both temporal variation in spring phytoplankton stock and spatial variation due to the magnitude of the bloom. In addition, we found that species-specific RNA dynamics and RNA-chl a relationships differed between species, indicating possible differences in feeding preferences and growth potential.
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| 2. |
- Abel, Sebastian, 1988-, et al.
(författare)
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Chemical Activity-Based Loading of Artificial Sediments with Organic Pollutants for Bioassays : A Proof of Concept
- 2024
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Ingår i: Environmental Toxicology and Chemistry. - 0730-7268 .- 1552-8618. ; 43:2, s. 279-287
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Tidskriftsartikel (refereegranskat)abstract
- Persistent organic pollutants (POPs) pose a risk in aquatic environments. In sediment, this risk is frequently evaluated using total or organic carbon-normalized concentrations. However, complex physicochemical sediment characteristics affect POP bioavailability in sediment, making its prediction a challenging task. This task can be addressed using chemical activity, which describes a compound's environmentally effective concentration and can generally be approximated by the degree of saturation for each POP in its matrix. We present a proof of concept to load artificial sediments with POPs to reach a target chemical activity. This approach is envisioned to make laboratory ecotoxicological bioassays more reproducible and reduce the impact of sediment characteristics on the risk assessment. The approach uses a constantly replenished, saturated, aqueous POP solution to equilibrate the organic carbon fraction (e.g., peat) of an artificial sediment, which can be further adjusted to target chemical activities by mixing with clean peat. We demonstrate the applicability of this approach using four polycyclic aromatic hydrocarbons (acenaphthene, fluorene, phenanthrene, and fluoranthene). Within 5 to 17 weeks, the peat slurry reached a chemical equilibrium with the saturated loading solution. We used two different peat batches (subsamples from the same source) to evaluate the approach. Variations in loading kinetics and eventual equilibrium concentrations were evident between the batches, which highlights the impact of even minor disparities in organic carbon properties within two samples of peat originating from the same source. This finding underlines the importance of moving away from sediment risk assessments based on total concentrations. The value of the chemical activity-based loading approach lies in its ability to anticipate similar environmental impacts, even with varying contaminant concentrations.
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| 3. |
- Andersson, Agneta, et al.
(författare)
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Microbial food web changes induced by terrestrial organic matter and elevated temperature in the coastal northern Baltic Sea
- 2023
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Climate change has been projected to cause increased temperature and amplified inflows of terrestrial organic matter to coastal areas in northern Europe. Consequently, changes at the base of the food web favoring heterotrophic bacteria over phytoplankton are expected, affecting the food web structure. We tested this hypothesis using an outdoor shallow mesocosm system in the northern Baltic Sea in early summer, where the effects of increased temperature (+ 3°C) and terrestrial matter inputs were studied following the system dynamics and conducting grazing experiments. Juvenile perch constituted the highest trophic level in the system, which exerted strong predation on the zooplankton community. Perch subsequently released the microbial food web from heavy grazing by mesozooplankton. Addition of terrestrial matter had a stronger effect on the microbial food web than the temperature increase, because terrestrial organic matter and accompanying nutrients promoted both heterotrophic bacterial production and phytoplankton primary production. Moreover, due to the shallow water column in the experiment, terrestrial matter addition did not reduce the light below the photosynthesis saturation level, and in these conditions, the net-autotrophy was strengthened by terrestrial matter enrichment. In combination with elevated temperature, the terrestrial matter addition effects were intensified, further shifting the size distribution of the microbial food web base from picoplankton to microphytoplankton. These changes up the food web led to increase in the biomass and proportion of large-sized ciliates (>60 µm) and rotifers. Despite the shifts in the microbial food web size structure, grazing experiments suggested that the pathway from picoplankton to nano- and microzooplankton constituted the major energy flow in all treatments. The study implies that the microbial food web compartments in shallow coastal waters will adjust to climate induced increased inputs of terrestrial matter and elevated temperature, and that the major energy path will flow from picoplankton to large-sized ciliates during the summer period.
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| 4. |
- Andriukonis, Eivydas, et al.
(författare)
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Kinetic N-15-isotope effects on algal growth
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Stable isotope labeling is a standard technique for tracing material transfer in molecular, ecological and biogeochemical studies. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism metabolism and growth, which is not consistent with current theoretical and empirical knowledge on kinetic isotope effects. Here, we demonstrate profound changes in growth dynamics of the green alga Raphidocelis subcapitata grown in N-15-enriched media. With increasing N-15 concentration (0.37 to 50 at%), the lag phase increased, whereas maximal growth rate and total yield decreased; moreover, there was a negative relationship between the growth and the lag phase across the treatments. The latter suggests that a trade-off between growth rate and the ability to adapt to the high N-15 environment may exist. Remarkably, the lag-phase response at 3.5 at% N-15 was the shortest and deviated from the overall trend, thus providing partial support to the recently proposed Isotopic Resonance hypothesis, which predicts that certain isotopic composition is particularly favorable for living organisms. These findings confirm the occurrence of KIE in isotopically enriched algae and underline the importance of considering these effects when using stable isotope labeling in field and experimental studies.
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| 5. |
- Berglund, Åsa M. M., 1978-, et al.
(författare)
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Effects on the food-web structure and bioaccumulation patterns of organic contaminants in a climate-altered Bothnian Sea mesocosms
- 2023
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is expected to alter global temperature and precipitation patterns resulting in complex environmental impacts. The proposed higher precipitation in northern Scandinavia would increase runoff from land, hence increase the inflow of terrestrial dissolved organic matter (tDOM) in coastal regions. This could promote heterotrophic bacterial production and shift the food web structure, by favoring the microbial food web. The altered climate is also expected to affect transport and availability of organic micropollutants (MPs), with downstream effects on exposure and accumulation in biota. This study aimed to assess climate-induced changes in a Bothnian Sea food web structure as well as bioaccumulation patterns of MPs. We performed a mesocosms-study, focusing on aquatic food webs with fish as top predator. Alongside increased temperature, mesocosm treatments included tDOM and MP addition. The tDOM addition affected nutrient availability and boosted both phytoplankton and heterotrophic bacteria in our fairly shallow mesocosms. The increased tDOM further benefitted flagellates, ciliates and mesozooplankton, while the temperature increase and MP addition had minor effect on those organism groups. Temperature, on the other hand, had a negative impact on fish growth and survival, whereas tDOM and MP addition only had minor impact on fish. Moreover, there were indications that bioaccumulation of MPs in fish either increased with tDOM addition or decreased at higher temperatures. If there was an impact on bioaccumulation, moderately lipophilic MPs (log Kow 3.6 - 4.6) were generally affected by tDOM addition and more lipophilic MPs (log Kow 3.8 to 6.4) were generally affected by increased temperature. This study suggest that both increased temperatures and addition of tDOM likely will affect bioaccumulation patterns of MPs in shallow coastal regions, albeit with counteracting effects.
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| 6. |
- Bighiu, Maria Alexandra, et al.
(författare)
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Metal contamination in harbours impacts life-history traits and metallothionein levels in snails
- 2017
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Harbours with limited water exchange are hotspots of contaminant accumulation. Antifouling paints (AF) contribute to this accumulation by leaching biocides that may affect non-target species. In several leisure boat harbours and reference areas in the Baltic Sea, chronic exposure effects were evaluated using caging experiments with the snail Theodoxus fluviatilis. We analysed variations in ecologically relevant endpoints (mortality, growth and reproduction) in concert with variation in metallothionein-like proteins (MTLP) levels. The latter is a biomarker of exposure to metals, such as copper (Cu) and zinc (Zn), which are used in AF paints as active ingredient and stabilizer, respectively. In addition, environmental samples (water, sediment) were analysed for metal (Cu and Zn) and nutrient (total phosphorous and nitrogen) concentrations. All life-history endpoints were negatively affected by the exposure, with higher mortality, reduced growth and lower fecundity in the harbours compared to the reference sites. Metal concentrations were the key explanatory variables for all observed adverse effects, suggesting that metal-driven toxicity, which is likely to stem from AF paints, is a source of anthropogenic stress for biota in the harbours.
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| 7. |
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| 8. |
- Breitholtz, Magnus, et al.
(författare)
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Calmodulin inhibition as a mode of action of antifungal imidazole pharmaceuticals in non-target organisms
- 2020
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Ingår i: Toxicology Research. - : Oxford University Press (OUP). - 2045-452X .- 2045-4538. ; 9:4, s. 425-430
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Tidskriftsartikel (refereegranskat)abstract
- To improve assessment of risks associated with pharmaceutical contamination of the environment, it is crucial to understand effects and mode of action of drugs in non-target species. The evidence is accumulating that species with well-conserved drug targets are prone to be at risk when exposed to pharmaceuticals. An interesting group of pharmaceuticals released into the environment is imidazoles, antifungal agents with inhibition of ergosterol synthesis as a primary mode of action in fungi. However, imidazoles have also been identified as competitive antagonists of calmodulin (CaM), a calcium-binding protein with phylogenetically conserved structure and function. Therefore, imidazoles would act as CaM inhibitors in various organisms, including those with limited capacity to synthesize sterols, such as arthropods. We hypothesized that effects observed in crustaceans exposed to imidazoles are related to the CaM inhibition and CaM-dependent nitric oxide (NO) synthesis. To test this hypothesis, we measured (i) CaM levels and its gene expression, (ii) NO accumulation and (iii) gene expression of NO synthase (NOS1 and NOS2), in the cladoceran Daphnia magna exposed to miconazole, a model imidazole drug. Whereas significantly increased CaM gene expression and its cellular allocation were observed, supporting the hypothesized mode of action, no changes occurred in either NO synthase expression or NO levels in the exposed animals. These findings suggest that CaM inhibition by miconazole leads to protein overexpression that compensates for the loss in the protein activity, with no measurable downstream effects on NO pathways. The inhibition of CaM in D. magna may have implications for effect assessment of exposure to mixtures of imidazoles in aquatic non-target species.
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| 9. |
- Brutemark, Andreas, et al.
(författare)
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Growth, toxicity and oxidative stress of a cultured cyanobacterium (Dolichospermum sp.) under different CO2/pH and temperature conditions
- 2015
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Ingår i: Phycological Research. - : Wiley. - 1322-0829 .- 1440-1835. ; 63:1, s. 56-63
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Tidskriftsartikel (refereegranskat)abstract
- Cyanobacteria blooms are a worldwide nuisance in fresh, brackish and marine waters. Changing environmental conditions due to upwelling, changed mixing conditions or climate change are likely to influence cyanobacteria growth and toxicity. In this study, the response of the toxic cyanobacterium Dolichospermum sp. to lowered pH (-0.4 units by adding CO2) and elevated temperature (+4 degrees C) in an experimental set-up was examined. Growth rate, microcystin concentration and oxidative stress were measured. The growth rate and intracellular toxin concentration increased significantly as a response to temperature. When Dolichospermum was exposed to the combination of elevated temperature and high CO2/low pH, lipid peroxidation increased and antioxidant levels decreased. Microcystin concentrations were significantly correlated with growth rates. Our results show, although oxidative stress increases when exposed to a combination of high CO2/low pH and high temperature, that growth and toxicity increase at high temperature, suggesting that the cyanobacterium in general seems to be fairly tolerant to changes in pH and temperature. Further progress in identifying biological responses and predicting climate change consequences in estuaries experiencing cyanobacteria blooms requires a better understanding of the interplay between stressors such as pH and temperature.
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| 10. |
- Calliari, Danilo, 1969, et al.
(författare)
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Instantaneous salinity reductions affect the survival and feeding rates of the co-occurring copepods Acartia tonsa Dana and A-clausi Giesbrecht differently
- 2008
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 362:1, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- Salinity variability at short time scales constitutes a severe restriction to marine life in coastal and estuarine ecosystems. In these environments zooplankters may experience rapid salinity variations due to diverse processes, yet lethal or sub-lethal responses to such changes have been scarcely studied. We assessed short-term (12 h) survival and time-integrated clearance (F; mL ind(-1) h(-1)) and ingestion rates (1, mu gC ind(-1) h(-1)) after 1, 2, 4, 8 and 12 h of two widespread and abundant coastal copepods, Acartia tonsa and A. clausi, subjected to instant salinity changes from 32 PSU to 26, 20,14, 8 and 4 PSU (A. tonsa) and from 32 to 26, 20 and 14 PSU (A. clausi). We expected that A. tonsa, which occur naturally in environments where sharp salinity gradients are common would tolerate wider salinity changes than A. clausi, which less frequently encounter sharp gradients in nature. For A. tonsa mortality for the extreme haline shock (change from 32 to 4 PSU) was 31%, whereas A. clausi reached 22% Mortality already at a change from 32 to 14 PSU; in comparison, mortality for A. tonsa at the 32/14 PSU treatment was only 3%. F and I decreased significantly at extreme treatments, and the total clearance in experimental bottles with salinity shocked animals (F-tot, mL h(-1)) was only 5% of rates measured in non-shocked control bottles for A. tonsa (32/4 PSU change) and 20% for A. clausi (32/14 PSU change); corresponding total ingestion (I-tot, mu gC h(-1)) represented 9.5% of that in control bottles for A. tonsa and 24% for A. clausi. In comparison, the 32/14 PSU treatment did not affect either clearance or ingestion rates in A. tonsa. Results suggest that in the field A. tonsa is not likely to suffer significant mortalities due to sudden salinity reductions in the Surrounding medium - except under extreme circumstances- while A. clausi cannot tolerate changes > 18 PSU. However, in both species feeding activity could be severely compromised by salinity reductions. The decreased feeding rate may have direct implications for processes ranging from energy acquisition at individual level to organic matter transfers at ecosystem level and thus deserves more attention in experimental studies and population modelling. (C) 2008 Elsevier B.V. All rights reserved.
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