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- Olsson, Björne, et al.
(författare)
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Physiological and proteomic responses in Mytilus edulis exposed to PCBs and PAHs extracted from Baltic Sea sediments
- 2004
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Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. ; 514:1-3, s. 15-27
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Tidskriftsartikel (refereegranskat)abstract
- Stress responses in blue mussels (Mytilus edulis. L.) exposed to organic pollutants were measured using several physiological measures and as changes in protein expression. Blue mussels from the Baltic Sea were exposed for 6 days in a flow-through system to two fractions of extracted Baltic sediments (containing primarily PAHs or PCBs) from one industrially impacted site and one off-shore site. Exposure to Aroclor1248 (a commercial PCB mixture) was included as a reference treatment. Physiological response was measured as changes in respiration, excretion, clearance rates and scope for growth. Of the physiological responses, only clearance rate and scope for growth in the Aroclor and impacted site PCB treatments differed significantly (p < 0.05) from control organisms, perhaps due to a large variation among individuals. Seven proteins were observed, presumed to be from stress protein families (hsp60, hsp70 and hsp90) on one-dimensional electrophoresis gels. All protein levels, except three proteins, 62, 73 and 90 kDa, in response to PCB exposure from the industrial site, were significantly higher (p < 0.05) in treated than in control organisms, suggesting the use of stress-inducible proteins as diagnostics in risk assessment. A wider sample of proteins was observed using two-dimensional gel electrophoresis. The presence or absence of protein spots compared to control organisms was used as an indication of stress. Between 23 and 76 proteins or spots were present and 15 to 23 absent compared to controls, and the results supported the physiological and one-dimensional gel results, suggesting that the mussels were indeed suffering from stress. The methods used here represent stress monitoring at two different levels of biological organization; the cellular- and the level of individual organisms. In this experiment the protein response showed less variation among individuals compared to the physiological parameters. The protein response, however, still suffers from the lack of interpretation into commonly used monitoring terms, which emphasizes the need for more knowledge of whether the response is a momentary reflection of exposure or an early warning of higher order effects.
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| 2. |
- Blidberg, Eva, 1968-
(författare)
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Ecotoxicological studies on giant clams (Tridacnidae) : Environmental problems and future concerns
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Giant clams (Tridacnidae; Bivalvia) are described as important framework builders on coral reefs in the Indo-Pacific region. They are phototrophic as they are associated with primary producing zooxanthellae. Populations are low due to over-exploitation and most species are now endangered in many areas. Also the general degradation of coral reef habitats and marine pollution related disturbances are threatening local giant clam populations. The aim of my thesis is to provide information of physiological and ecological requirements of giant clams to improve the management of these species. By using mainly physiological methods and lethality tests, the responses to anthropogenic stress and natural disturbance were studied. In Paper I, the effect of elevated temperature was tested for in three different species of clams in order to rank the relative sensitivity. Using the end-point production to respiration ratio (Pg/R), we concluded Hippopus hippopus to be the most sensitive species. Paper II compares two different methods measuring copper stress on the photosynthetic efficiency. It was evident that fluorescence measurements and whole animal physiology gave different results. In Paper III Tridacna gigas were transplanted to sites with increased turbidity due to human activities during 6 months. Clearly, the actual growth rate decreased compared to a “clean” site. The clams from turbid waters on the other hand developed a somewhat higher tolerance to copper exposure. Tridacna gigas larvae were exposed to a combination of copper and low salinity in Paper IV, and it was shown that reduced salinity increases mortality, and synergistic effects were obvious. In Paper V and Paper VI effects of oil pollution on juveniles and larvae were studied. Juvenile clams displayed a reduction in the Energy Balance Equation due to reduced filter feeding and absorption efficiency. The larval stage had low tolerance to benzo[a]pyrene, and there was a negative trend in settlement success. Overall, the studies acknowledge harmful effects of pollutants found in tropical coastal areas. The importance of taking this into account when discussing the future of wild giant clams is indisputable.
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| 6. |
- Kautsky, Nils, et al.
(författare)
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Ecosystem perspectives on management of disease in shrimp pond farming
- 2000
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Ingår i: Aquaculture. - Amsterdam : Elsevier. - 0044-8486 .- 1873-5622. ; 191:1-3, s. 145-161
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews and discusses, from an ecological perspective, the causes behind the development and spreading of pathogens in shrimp aquaculture. The risk of disease in shrimp farming often increases with culture intensity and high stocking densities, and when polyculture is replaced by monoculture. High pond densities will facilitate the spread of pathogens between ponds. Shortage of clean water supply and insufficient waste removal lead to overloading of metabolites, environmental degradation, and to the shrimp becoming stressed by bad water quality, and thus more prone to becoming affected by disease. Excessive fluctuations in abiotic factors like oxygen, salinity, and temperature may also increase stress and susceptibility to disease. The location of farms in mangrove environments can lead to acidification that may directly, or indirectly, through release of heavy metals from the sediments, lower disease resistance. The use of hatchery-reared larvae will increase genetic uniformity and thus disease risk in comparison to the collection of wild larvae where selection has already favored the most viable individuals. Global and regional transportation of seed larvae and broodstock will facilitate the spread of pathogens. Apart from the above factors, which are all dependant on the farming itself, contamination by pesticides and pollutants from agriculture and industrial activities may lower disease resistance of the shrimp, especially if combined with other environmental factors.We show that shrimp farming is, to a large extent, dependent on ecological services supplied by nature, and discuss the carrying capacity of shrimp pond farming from an ecosystem perspective, including aspects like culture intensity, pond density and sustainability. Since aquaculture is basically a natural ecological process, although in intensive shrimp farming it reaches industrial proportions, it is essential that we do not forget the underlying ecological principles, as this may help us to understand and contribute to the solution of some of the disease problems faced by shrimp farming.
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| 7. |
- Nordemar, Ingrid, 1968-
(författare)
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Human Abuses of Coral Reefs- Adaptive Responses and Regime Transitions
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last few decades, coral reefs have become a disappearing feature of tropical marine environments, and those reefs that do remain are severely threatened. It is understood that humans have greately altered the environment under which these ecosystems previously have thrived and evoloved. Overharvesting of fish stocks, global warming and pollution are some of the most prominent threats, acting on coral reefs at several spatial and temporal scales. Presently, it is common that coral reefs have been degraded into alternative ecosystem regimes, such as macroalgae-dominated or sea urchin-barren. Although these ecosystems could potentially return to coral dominance in a long-term perspective, when considdering current conditions, it seems likely that they will persist in their degraded states. Thus, recovery of coral reefs cannot be taken for granted on a human timescale. Multiple stressors and disturbances, which are increasingly characteristic of coral reef environments today, are believed to act synergistically and produce ecological surprises. However, current knowledge of effects of compounded disturbances and stress is limited. Based on five papers, this thesis investigates the sublethal response of multiple stressors on coral physiology, as well as the effects of compounded stress and disturbance on coral reef structure and function. Adaptive responses to stress and disturbance in relation to prior experience are highlighted. The thesis further explores how inherent characteristics (traits) of corals and macroalgae may influence regime expression when faced with altered disturbance regimes, in particular overfishing, eutrophication, elevated temperature, and enhanced substrate availability. Finally, possibilities of affecting the resilience of macroalgae-dominaed reefs and shifting the community composition towards a coral-dominated regime are explored.
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| 8. |
- Tedengren, Michael, et al.
(författare)
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Heat pretreatment increase cadmium resistance and HSP 70 levels in Baltic Sea mussels
- 2000
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Ingår i: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 48:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The effects of heat treatment and cadmium exposure on the synthesis of a major stress inducible protein (hsp 70) and on the metabolism of the blue mussel Mytilus edulis L. from the Baltic Sea, were studied in a laboratory experiment. The mussels were kept in sea water of ambient salinity (6.3‰) and temperature (4°C). The effects of cadmium (20 μg l−1), measured as changes in physiological rates (oxygen consumption, ammonia excretion, clearance rates and scope for growth) and hsp 70 expression were studied at 4°C and in combination with a rapid rise in temperature to 20°C. Relatively low levels of hsp 70 were detected but the negative effect was reflected in a reduction of scope for growth of the exposed mussels compared to controls. This effect was more pronounced at 20°C. Mussels not exposed to cadmium in the first experiment were used in a second set of experiments. Heat shocked mussels were allowed to reacclimatise to 4°C for 5 days and then, along with the mussels already at 4°C, exposed to cadmium (20 μg l−1). The results clearly indicated that the mussels exposed to 20°C in the first experiment more rapidly induced synthesis of hsp 70 after cadmium exposure in the second experiment. Also the reacclimatised mussels exposed to heat shock but not to cadmium in the first experiment, induced some hsp 70 in the second experiment. This suggests that the rate of induction of heat shock or stress proteins in Baltic mussels is slower than what has been described for mussels from more marine environments. The mussels kept at 4°C throughout the experiment and exposed to cadmium showed low levels of hsp 70, again indicating a low rate of induction. The increasing levels of hsp 70 correlated well with a maintained level of physiological fitness, in terms of scope for growth, although the mussels showed increasing body burdens of cadmium.
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