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Linking sub-cellular biomarkers to embryo aberrations in the benthic amphipod Monoporeia affinis
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
(English)Manuscript (preprint) (Other academic)
Abstract [en]

To adequately assess and monitor environmental status in the aquatic environment a broad approach is needed that integrates physical variables, chemical analyses and biological effects at different levels of the biological organization. Embryo aberrations in the Baltic Sea key species Monoporeia affinis have shown to be inducible by both metals and organic substances as well as by hypoxia, increasing temperatures and malnutrition. This amphipod have therefore been used for more than three decades as a biological effect indicator in monitoring and assessment of chemical pollution and environmental stress. However, little is known about the sub-cellular mechanisms underlying embryo aberrations. An improved mechanistic understanding may open up the possibility of including sub-cellular alterations as sensitive warning signals of stress-induced embryo aberrations. In the present study, M. affinis was exposed in microcosms to 4 different sediments from the Baltic Sea. After 88-95 days of exposure, survival and fecundity was determined as well as the frequency and type of embryo aberrations. Moreover, oxygen radical absorption capacity (ORAC) was assayed as a proxy for antioxidant defence, thiobarbituric acid reactive substances (TBARS) as a measurement of lipid peroxidation and acetylcholinesterase (AChE) activity as an indicator of neurotoxicity. The results show that AChE and ORAC can be linked to the frequency of malformed embryos and arrested embryo development. The occurrence of dead broods was significantly associated with elevated TBARS levels. It can be concluded that these sub-cellular biomarkers are indicative of effects that could affect Darwinian fitness and that oxidative stress is a likely mechanism in the development of aberrant embryos.

Keyword [en]
Monoporeia affinis, embryo aberrations, oxidative stress, Darwinian fitness
National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
URN: urn:nbn:se:su:diva-111065OAI: oai:DiVA.org:su-111065DiVA: diva2:774043
Available from: 2014-12-21 Created: 2014-12-21 Last updated: 2016-01-29Bibliographically approved
In thesis
1. Improved environmental monitoring and assessment: Establishing links between effects of chemical pollution at different levels of biological organization in a Baltic Sea bioindicator species (Monoporeia affinis)
Open this publication in new window or tab >>Improved environmental monitoring and assessment: Establishing links between effects of chemical pollution at different levels of biological organization in a Baltic Sea bioindicator species (Monoporeia affinis)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A large number of chemicals enters the marine environment via atmospheric deposition, run-off, rivers and streams, industrial effluents and municipal wastewater. To understand how chemicals affect environmental health, monitoring and assessment approaches need to combine physical, chemical and biological effect parameters from different levels of biological organization. Embryo aberrations and reproductive success in the Baltic Sea key species Monoporeia affinis have been linked to various stressors, including chemicals, and have been applied as a bioindicator of chemical pollution since the 1970s. The current thesis aimed to improve this bioindicator by linking effects at different levels of biological organization. Understanding how effects are linked, from sub-cellular effects, to decreased organism fitness and further on to populations, will improve the ability to give early warnings and understand risks that an ecosystem faces. Paper I links point sources of chemical pollution to embryo aberrations, and shows that effects can be detected 20-30 km from point sources. Paper II demonstrates on a sub-cellular level how M. affinis´ ability to cope with hypoxia is adversely affected by chemical stress, and how it could decrease fitness. Paper III link sub-cellular effects to embryo aberrations and suggests a mechanistic link between oxidative stress and embryo aberrations. Paper III also shows that sub-cellular effects respond more distinctly compared to fecundity, survival and embryo aberrations and can thus improve the ability to detect stress at an early stage. In Paper IV, a population model was developed, which shows that populations could be severely affected if levels of embryo aberrations persist at levels commonly observed in Baltic Sea. This thesis contributes to a more holistic understanding of how chemical pollution affects M. affinis, thereby improving our ability to early detect negative effects and understand potential risks that the Baltic Sea faces.

Place, publisher, year, edition, pages
Stockholm: Department of Environmental Science and Analytical Chemistry, Stockholm University, 2015. 32 p.
Keyword
Environmental health assessment, environmental monitoring, chemical pollution, hypoxia, bioindicators, biomarkers, teratogenicity, embryo toxicity, oxidative stress, acetylcholine esterase. Monoporeia affinis, Baltic Sea
National Category
Biological Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-111067 (URN)978-91-7649-078-5 (ISBN)
Public defence
2015-01-30, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2015-01-08 Created: 2014-12-21 Last updated: 2014-12-30Bibliographically approved
2. Application and interpretation of biomarkers in ecotoxicology - from molecular to individual level responses
Open this publication in new window or tab >>Application and interpretation of biomarkers in ecotoxicology - from molecular to individual level responses
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of biomarkers is considered a promising alternative, or complement, to traditional ecotoxicological assays. Toxic effects are often initially manifested at the molecular or biochemical level, biomarkers are therefore used as sensitive indicators of toxic exposure. Ideally, biomarkers would also indicate reduced fitness and possible later effects at the individual or population levels. However, implementing biomarkers in ecotoxicology is challenging and few biomarkers have an established connection to reduced individual fitness. The aim of this thesis was to increase the value and improve the interpretation of biomarker responses in ecotoxicological studies by examining the impact of confounding factors and the relationship between oxidative biomarkers and reproductive effects in crustaceans.

The sensitivity of biomarkers was confirmed in paper I as toxic effects of pharmaceuticals with conserved drug target orthologs were observed at the molecular and biochemical levels both earlier and at lower concentrations than effects on mortality and reproduction. No toxic effects were observed for the pharmaceutical without identified drug target orthologs, thus stressing the importance of considering toxic mechanisms and being aware of the most likely target when evaluating toxic effects also in non-target species. Many xenobiotics and environmental stressors interfere with oxidative processes, making oxidative biomarkers interesting to study in ecotoxicology and stress ecology. Still, feeding rate was identified as a confounding factor for antioxidant capacity (assayed as oxygen radical absorbance capacity, ORAC) and lipid peroxidation in ecotoxicological studies (paper II). However, ORAC normalized to protein was independent of altered feeding rates, hence it can be applied as a suitable exposure biomarker without considering alterations and effects of feeding rate. The connection between reproduction and oxidative stress is dual, as reproduction both can be inhibited by oxidative stress and induce pro-oxidative processes. Further, a positive association was found between ORAC and the occurrence of embryo aberrations in the benthic amphipod Monoporeia affinis (paper III). An association between antioxidant defense and reproduction was also observed for Daphnia magna (paper IV). Threshold values for identification of exposed individuals and prediction of possible later reproductive effects were established for ORAC.

This thesis has contributed to diminishing some of the knowledge gaps limiting the use of oxidative biomarkers in ecotoxicology, by contributing to increased understanding of how oxidative biomarkers relate to important life-traits. Moreover, ORAC has been identified as a suitable biomarker of not only exposure, but also reproductive effects. Future research should continue to establish connections between biomarker responses and effects at higher levels, and focus on providing defined threshold values to enable predictions about later effects.   

Place, publisher, year, edition, pages
Stockholm: Department of Environmental Science and Analytical Chemistry, Stockholm University, 2015. 29 p.
Keyword
biomarkers, oxidative stress, ORAC, reproduction, Daphnia magna, toxicity, environmental stress
National Category
Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-120161 (URN)978-91-7649-252-9 (ISBN)
Public defence
2015-10-16, De Geer-salen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2015-09-24 Created: 2015-09-02 Last updated: 2015-09-16Bibliographically approved

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