Biological effects of contaminants in mussels (Mytilus trossulus) transplanted in northern Baltic Sea coastal areas

Biomarkers measured in organisms are sensitive molecular, cellular or individual level biological effects, which can be applied as early-warning signals of environmental contamination before damage occurs at population, community or ecosystem levels. In this thesis, a suite of biomarkers and tissue concentrations of chemicals were measured in mussels (Mytilus trossulus) as indicators of environmental pollution. The mussels were transplanted in specially made cages in coastal areas of the northern Baltic Sea influenced by different types of contamination and environmental factors. The aims of the research were to apply the biomarker approach to (1) assess the impact of contaminants on the health status of mussels, (2) investigate the effects of seasonal variability in biotic and abiotic factors, and low salinity, and (3) validate the usefulness of the mussel caging method for biomonitoring of chemical contamination in the northern Baltic Sea. The results showed marked biomarker responses coinciding with higher concentrations of contaminants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), organotins and trace metals, in mussels caged at the most contaminated study sites. At the contaminated sites, for example the enzymatic biomark¬ers of the antioxidant defense system indicated higher stress level, which was closely linked to elevated level of DNA-damage, increased biotransformation activity and decreased general health status of the cells. Biomarker responses and tissue contaminant concentrations were also related to the seasonal variability in growth and especially in soft tissue weight of the mussels. In the northern Baltic Sea the mussels almost fully deplete their energy stores during the winter; in the spring mussels efficiently feed on the fresh phytoplankton, which forms the main source of energy for their reproduction, energy metabolism and growth. Natural environmental factors caused less variation in the biomarker responses in the late summer and autumn suggesting that this time period is the most suitable for studying contaminant induced effects in mussels. More pronounced effects were observed in mussels exposed jointly to low salinity and chemical contamination, indicating that increased environmental stress reduces the tolerance of mussels towards anthropogenic pressures. This work showed that the mussel caging approach is an efficient biomonitoring method to assess biological effects and tissue accumulation of complex mixtures of contaminants as long as the effects of seasonal variability and low salinity are taken into account.Mereen jatkuvasti päätyvät sekä siellä jo olevat haitalliset kemikaalit huonontavat eliöiden terveyttä. Tässä työssä tutkittiin useita eliöiden terveydentilasta kertovia muuttujia eli ns. biomarkkereita ja haitallisten aineiden kudospitoisuuksia pohjoisen Itämeren sinisimpukoista Turun, Porvoon, Helsingin, Gävlen ja Sundsvallin kaupunkien edustalla. Tutkimuksessa käytettiin simpukkahäkitysmenetelmää, jossa sinisimpukoita kerättiin mahdollisimman puhtaalta alueelta ja ne vietiin häkeissä tutkimusalueille 1-4 kuukauden ajaksi. Jokaisella tutkimusalueella simpukkahäkit ankkuroitiin sekä likaantuneelle ihmistoiminnan lähellä olevalle alueelle että puhtaammalle kuormituslähteistä kauempana olevalle alueelle. Sinisimpukat sopivat tällaiseen tutkimukseen hyvin, sillä häkki toimii niille alustana johon ne luontaisesti kiinnittyvät. Ne myös pumppaavat vettä tehokkaasti kidustensa läpi ja suodattavat näin vedestä kasviplanktonia ravinnokseen, samalla altistuen veden ja ruuan mukana tuleville haitallisille aineille. Sinisimpukoista mitattujen terveyttä kuvaavien biomarkkerien avulla havaittiin esimerkiksi kaupunkien jätevesien, jokien tuoman kuormituksen ja meriliikenteen pöllyttämien likaantuneiden pohjasedimenttien aiheuttaman kemikaalikuormituksen merkittäviä haitallisia vaikutuksia. Likaantuneilla alueilla sinisimpukat olivat myös keränneet kudoksiinsa korkeampia haitallisten aineiden pitoisuuksia. Lisäksi tutkimuksessa havaittiin, että normaali vuodenaikaisvaihtelu keväällä ja alkukesällä vaikutti mitattuihin biomarkkerivasteisiin ja haitallisten aineiden kudospitoisuuksiin. Alhaisen suolapitoisuuden vaikutus näkyi Selkämerellä Gävlessä ja Sundsvallissa häkitetyissä sinisimpukoissa. Loppukesällä ja syksyllä ympäristötekijöiden aiheuttama biomarkkerivasteiden vaihtelu oli vähäisintä, minkä vuoksi tämä ajankohta sopii parhaiten haitallisten aineiden vaikutusten ympäristöseurantaan. Suurimmat biomarkkerivasteet mitattiin sinisimpukoissa, jotka altistuivat yhtä aikaa alhaiselle suolapitoisuudelle ja haitallisille aineille; tämä viittaa siihen, että korkeampi ympäristötekijöiden aiheuttama stressi vähentää niiden kykyä sietää ihmisen toiminnasta johtuvaa kemikaalipainetta. Tutkimus osoitti, että sinisimpukoiden häkitys on tehokas menetelmä Itämeren kemikaalikuormituksen vaikutusten arvioinnissa kun otetaan huomioon vuodenaikaisvaihtelun ja alhaisen suolapitoisuuden vaikutukset mitattaviin muuttujiin

Biomarker responses and accumulation of polycyclic aromatic hydrocarbons in Mytilus trossulus and Gammarus oceanicus during exposure to crude oil

In the brackish water Baltic Sea, oil pollution is an ever-present and significant environmental threat mainly due to the continuously increasing volume of oil transport in the area. In this study, effects of exposure to crude oil on two common Baltic Sea species, the mussel Mytilus trossulus and the amphipod Gammarus oceanicus, were investigated. The species were exposed for various time periods (M. trossulus 4, 7, and 14 days, G. oceanicus 4 and 11 days) to three oil concentrations (0.003, 0.04, and 0.30 mg L−1 based on water measurements, nominally aimed at 0.015, 0.120, and 0.750 mg L−1) obtained by mechanical dispersion (oil droplets). Biological effects of oil exposure were examined using a battery of biomarkers consisting of enzymes of the antioxidant defense system (ADS), lipid peroxidation, phase II detoxification (glutathione S-transferase), neurotoxicity (acetylcholinesterase inhibition), and geno- and cytotoxicity (micronuclei and other nuclear deformities). In mussels, the results on biomarker responses were examined in connection with data on the tissue accumulation of polycyclic aromatic hydrocarbons (PAH). In M. trossulus, during the first 4 days of exposure the accumulation of all PAHs in the two highest exposure concentrations was high and was thereafter reduced significantly. Significant increase in ADS responses was observed in M. trossulus at 4 and 7 days of exposure. At day 14, significantly elevated levels of geno- and cytotoxicity were detected in mussels. In G. oceanicus, the ADS responses followed a similar pattern to those recorded in M. trossulus at day 4; however, in G. oceanicus, the elevated ADS response was still maintained at day 11. Conclusively, the results obtained show marked biomarker responses in both study species under conceivable, environmentally realistic oil-in-seawater concentrations during an oil spill, and in mussels, they are related to the observed tissue accumulation of oil-derived compounds

Exposure to dissolved TNT causes multilevel biological effects in Baltic mussels (Mytilus spp.)

Highlights • Shell closing as simple defence against acute toxicity of TNT. • Mussels appear to be able to metabolize TNT to 2- and 4-ADNT.Biomarker responses occurred already at the lowest TNT exposure concentrations. • Biomarker responses occurred already at the lowest TNT exposure concentrations.Baltic mussels (Mytilus spp.) were exposed to the explosive trinitrotoluene (TNT) for 96 h (0.31–10.0 mg/L) and 21 d (0.31–2.5 mg/L). Bioaccumulation of TNT and its degradation products (2- and 4-ADNT) as well as biological effects ranging from the gene and cellular levels to behaviour were investigated. Although no mortality occurred in the concentration range tested, uptake and metabolism of TNT and responses in antioxidant enzymes and histochemical biomarkers were observed already at the lowest concentrations. The characteristic shell closure behaviour of bivalves at trigger concentrations led to complex exposure patterns and non-linear responses to the exposure concentrations. Conclusively, exposure to TNT exerts biomarker reponses in mussels already at 0.31 mg/L while effects are recorded also after a prolonged exposure although no mortality occurs. Finally, more attention should be paid on shell closure of bivalves in exposure studies since it plays a marked role in definining toxicity threshold levels

Advanced monitoring of harmful substances and their effects in the Baltic Sea is desired : A comment on Kanwischer et al. (2021)

Comment to: Kanwischer, M., N. Asker, A.S. Wernersson, M.A. Wirth, K. Fisch, E. Dahlgren, H. Osterholz, F. Habedank, et al. 2021. Substances of emerging concern in Baltic Sea water: Review on methodological advances for the environmental assessment and proposal for future monitoring. Ambio. https://doi.org/10.1007/s13280-021-01627-

An integrated chemical-biological study using caged mussels (Mytilus trossulus) along a pollution gradient in the Archipelago Sea (SW Finland, Baltic Sea)

International audienceMussels (Mytilus trossulus) were caged along a known pollution gradient in the inner Archipelago Sea (northern Baltic Sea) and retrieved after 71 and 121 d for the measurement of selected chemical contaminants in tissues and biological endpoints including biochemical biomarkers and growth. Additional samples were collected during the growth season from a native mussel population at an alleged reference site. Elevated concentrations of numerous contaminants (e.g., PAH) were observed in spring, apparently due to the loss of tissue mass during the winter, while also the levels of many biomarkers (e.g., glutathione S-transferase activity) were elevated. Spatial and temporal changes in the accumulation of contaminants and biological parameters were observed with some of them (e.g., growth) linked to seasonal changes in environmental factors. The results underline the importance of understanding the effects of seasonal natural factors on the growth dynamics and general condition of mussels when assessing tissue concentrations of contaminants and biological effects

Assessment of the environmental impact of the dumped chemical warfare agents at the Baltic Sea using caged blue mussels (Mytilus trossulus)

Chemical weapons dumped into the sea after World War II possess growing concern for the marine environment; metal shells of different chemical munitions lying on the bottom are severely corroded and dangerous contents pollute the sediments. Chemical warfare agents (CWAs), such as mustard gas and various arsenic-based compounds (e.g., Clark I and Adamsite) and their degradation products have been detected in noticeable concentrations in sediments at the major dumping sites at the Baltic Sea. Blue mussel caging approach was applied to assess environmental impact of thousands of tons of CWAs at the main dumping site at the Bornholm Basin. Due to the patchy occurrence of the CWAs in the sediments mussel caging method was chosen to deploy the organisms exactly at sites where high CWA concentrations were detected in sediments and to one reference site. Biomarkers representing different biological functions including antioxidant defence, biotransformation, neurotoxicity, lysosomal membrane stability, geno- and cytotoxicity, cellular energy allocation and condition index were investigated. Moreover, tissue concentrations of different CWAs and the possible metabolic derivatives of these compounds were analysed in mussels together with “classical” contaminants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and trace metals. Further, mussel cages were equipped with salinity, temperature and oxygen sensors to follow the fluctuations in the environmental parameters during the two and half month caging time. Environmental parameters indicated mixing of the near bottom water in the lower water layer where the cages were deployed (at 60 meters). Significant biomarker responses were observed at the two contaminated sites compared to the reference site indicating CWA induced effect on molecular and cellular level; however the possible anaerobic conditions and lower food availability in deep waters led to decreased bioenergetic status of the caged mussels. Results of the still on-going chemical analysis will be employed together with the biomarker responses and environmental data in the multi-level integrated impact assessment of the area

Influence of Environmental Variables on Biochemical Biomarkers in the Amphipod <i>Monoporeia affinis</i> from the Gulf of Riga (Baltic Sea)

The complexity of the marine environment and the increasing anthropogenic pressure create a necessity to expand existing monitoring approaches. The main goal of this study was to depict the effects of selected, seasonally varying environmental factors on a battery of biomarkers in the benthic amphipod Monoporeia affinis from the Gulf of Riga (GoR). Seasonal variability in acetylcholinesterase (AChE), catalase (CAT), glutathione reductase (GR), and glutathione S-transferase (GST) activities was investigated at six coastal stations (20–30 m) in August and November in 2020 and 2021. In addition, the biomarkers were measured at seven deep-water stations (>30 m) in November 2021. In general, the results indicated no significant influence of the measured environmental variables on the biomarker activities, except for deep-water stations, where chlorophyll a significantly affected enzymatic activity. The current study indicated that M. affinis has a higher GST, CAT and GR activity in summer compared to autumn in coastal stations, showing seasonal variability of these biomarkers. However, summarizing the biomarker levels recorded at each station and season, the integrated biomarker response (IBR) index showed the most stressed health status of the M. affinis populations in the deep-water stations 135 and 107 and coastal regions in the north-eastern part of the GoR (station 160B). This suggests that the impact on enzymatic responses of benthic organisms could be due to port activities leading to the accumulation of pollutants in muddy sediments regionally. Moreover, for the monitoring of biological effects of contaminants there is a need to establish the background levels of biomarkers, i.e., responses to the different natural environmental factors in the GoR region