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Understanding how key-species respond to anthropogenic stress such as chemical pollution is critical for predicting ecosystem changes. Little is however known about the intra-specific variability in the physiological and biochemical traits involved in contaminant exposure responses. Here, we explored this idea by exposing the Baltic amphipod Monoporeia affinis from two sites, one moderately polluted and one more pristine, to a sediment spiked with PAHs and PCBs. We evaluated the amphipods responses related to feeding, growth, a stress biomarker (acetylcholinesterase [AChE] inhibition) and stable isotope (delta C-13 and delta N-15) composition including isotope niche analyses. More adverse responses were expected in animals from the low-pollution site than those from the high-pollution site due to tolerance development in the latter. Amphipods from both populations showed a similar to 30% AChE inhibition when exposed to the contaminant spiked sediment. However, both controls and exposed amphipods from the high-pollution site had higher survival, nutrient uptake and condition status than the amphipods from the low-pollution site, which did not feed on the added diatoms as indicated by their isotope values. We found no signs of population-specific responses in physiological adjustments to contaminants with regard to classic ecotoxicological biomarkers such as AChE inhibition and growth status. Instead, isotope niche analyses proved useful in assessing contaminant stress responses at the population level.

Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services.

Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services. © 2024. The Authors.

Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services.

Contaminant monitoring in biota is important for determining environmental status and to detect or prioritize action on hazardous substances. Predators higher up a food chain are often used for monitoring of contaminants that bioaccumulate. However, it is not always possible to find higher predators that are both abundant and have a wide distribution for national or international contaminant monitoring. Great cormorants (Phalocrocorax carbo) are a widespread and increasingly common top predator of fish in fresh, brackish and salt water. We evaluate the suitability of great cormorant eggs as a matrix for contaminant monitoring by using stable isotopes of carbon, nitrogen and sulfur. Despite the fact that cormorants are migratory, egg isotope values showed a significant separation between five breeding colonies in Sweden (1 fresh water lake, 3 Baltic sites and 1 marine site). This high degree of separation indicates that eggs are primarily produced using local resources (not stored body resources) and that contaminants (mercury concentrations in this study) measured in eggs likely reflect levels in fish prey caught close to the breeding area. Compound specific stable isotope analysis was used to estimate cormorant trophic position (TP) and concentrations of mercury in eggs were positively related to TP. The results show that a multi-isotope approach, combined with good ecological diet knowledge allow for meaningful and comparative interpretation of mercury concentrations in biota and that great cormorant eggs appear a suitable matrix to measure locally derived and maternally transferred contaminants.

We present a common-garden experiment to examine the amphipod Monoporeia affinis, a key deposit-feeder in the Baltic Sea, a low diversity system offering a good model for studying local adaptations. In the northern part of this system, the seasonal development of phytoplankton is characterized by a single diatom bloom (high nutritional quality), whereas in the south, the diatom bloom is followed by a cyanobacteria bloom (low nutritional quality) during summer. Therefore, the nutrient input to the benthic system differs between the sea basins. Accordingly, the amphipod populations were expected to be dietary specialists in the north and generalists in the south. We tested this hypothesis using a combination of stable isotope tracers, trophic niche analyses, and various endpoints of growth and health status. We found that when mixed with diatomes, the toxin-producing cyanobacteria, were efficiently incorporated and used for growth by both populations. However, contrary to expectations, the feeding plasticity was more pronounced in the northern population, indicating genetically-based divergence and suggesting that these animals can develop ecological adaptations to the climate-induced northward cyanobacteria expansion in this system. These findings improve our understanding regarding possible adaptations of the deposit-feeders to increasing cyanobacteria under global warming world in both limnic and marine ecosystems. It is possible that the observed effects apply to other consumers facing altered food quality due to environmental changes.

Toxin-producing cyanobacteria can be harmful to aquatic biota, although some grazers utilize them with often beneficial effects on their growth and reproduction. It is commonly assumed that gut microbiota facilitates host adaptation to the diet; however, the evidence for adaptation mechanisms is scarce. Here, we investigated the abundance of mlrA genes in the gut of the Baltic copepods Acartia bifilosa and Eurytemora affinis during cyanobacteria bloom season (August) and outside it (February). The mlrA genes are unique to microcystin and nodularin degraders, thus indicating the capacity to break down these toxins by the microbiota. The mlrA genes were expressed in the copepod gut year-round, being >10-fold higher in the summer than in the winter populations. Moreover, they were significantly more abundant in Eurytemora than Acartia. To understand the ecological implications of this variability, we conducted feeding experiments using summer- and winter-collected copepods to examine if/how the mlrA abundance in the microbiota affect: (1) uptake of toxic Nodularia spumigena, (2) uptake of a non-toxic algal food offered in mixtures with N. spumigena, and (3) concomitant growth potential in the copepods. The findings provide empirical evidence that the occurrence of mlrA genes in the copepod microbiome facilitates nutrient uptake and growth when feeding on phytoplankton mixtures containing nodularin-producing cyanobacteria; thus, providing an adaptation mechanism to the cyanobacteria blooms.

Ocean climate change strongly affects organisms and ecosystems, and the causes, consequences, and underlying mechanisms need to be documented. In the Baltic Sea, a marginal sea under severe eutrophication stress, a longer productive season, and changes in the phytoplankton community over the last few decades have likely impacted diet and condition of keystone species, from individual to population level. This study uses stable isotopes (δ13C, δ15N, and derived isotope niche metrics) to trace energy and nutrient flows in archived samples of blue mussel (Mytilus edulis trossulus) spanning 24 yr (1993–2016). We test if long‐term changes in isotope and elemental composition in mussels, as well as population abundance and biomass, can be explained by changes in abiotic and biotic variables, using partial least square regressions and structural equation modeling. We found decreasing trends in δ13C and δ15N as well as in mean size and total biomass of mussels, but no unidirectional changes in their stoichiometry or condition index. Changes in isotope composition were best explained by nitrogen‐fixing cyanobacteria, by increased terrestrial organic carbon from land runoff (reflecting precipitation) and by decreases in dissolved inorganic nitrogen (indicative of successful eutrophication mitigation) and in biomass of a mixotrophic ciliate species. The trophic niche (assessed from isotope niche) was included as the best predictor for both mussel body condition and the observed decline in their total biomass. This study reveals that altered trophic relationships from climate‐induced changes in the productivity base may strongly impact keystone species, with potential knock‐on effects on ecosystem functions.

Ocean climate change strongly affects organisms and ecosystems, and the causes, consequences, and underlying mechanisms need to be documented. In the Baltic Sea, a marginal sea under severe eutrophication stress, a longer productive season, and changes in the phytoplankton community over the last few decades have likely impacted diet and condition of keystone species, from individual to population level. This study uses stable isotopes (δ13C, δ15N, and derived isotope niche metrics) to trace energy and nutrient flows in archived samples of blue mussel (Mytilus edulis trossulus) spanning 24 yr (1993–2016). We test if long‐term changes in isotope and elemental composition in mussels, as well as population abundance and biomass, can be explained by changes in abiotic and biotic variables, using partial least square regressions and structural equation modeling. We found decreasing trends in δ13C and δ15N as well as in mean size and total biomass of mussels, but no unidirectional changes in their stoichiometry or condition index. Changes in isotope composition were best explained by nitrogen‐fixing cyanobacteria, by increased terrestrial organic carbon from land runoff (reflecting precipitation) and by decreases in dissolved inorganic nitrogen (indicative of successful eutrophication mitigation) and in biomass of a mixotrophic ciliate species. The trophic niche (assessed from isotope niche) was included as the best predictor for both mussel body condition and the observed decline in their total biomass. This study reveals that altered trophic relationships from climate‐induced changes in the productivity base may strongly impact keystone species, with potential knock‐on effects on ecosystem functions.

Ocean climate change strongly affects organisms and ecosystems, and the causes, consequences, and underlying mechanisms need to be documented. In the Baltic Sea, a marginal sea under severe eutrophication stress, a longer productive season, and changes in the phytoplankton community over the last few decades have likely impacted diet and condition of keystone species, from individual to population level. This study uses stable isotopes (δ13C, δ15N, and derived isotope niche metrics) to trace energy and nutrient flows in archived samples of blue mussel (Mytilus edulis trossulus) spanning 24 yr (1993–2016). We test if long‐term changes in isotope and elemental composition in mussels, as well as population abundance and biomass, can be explained by changes in abiotic and biotic variables, using partial least square regressions and structural equation modeling. We found decreasing trends in δ13C and δ15N as well as in mean size and total biomass of mussels, but no unidirectional changes in their stoichiometry or condition index. Changes in isotope composition were best explained by nitrogen‐fixing cyanobacteria, by increased terrestrial organic carbon from land runoff (reflecting precipitation) and by decreases in dissolved inorganic nitrogen (indicative of successful eutrophication mitigation) and in biomass of a mixotrophic ciliate species. The trophic niche (assessed from isotope niche) was included as the best predictor for both mussel body condition and the observed decline in their total biomass. This study reveals that altered trophic relationships from climate‐induced changes in the productivity base may strongly impact keystone species, with potential knock‐on effects on ecosystem functions.

Ocean climate change strongly affects organisms and ecosystems, and the causes, consequences, and underlying mechanisms need to be documented. In the Baltic Sea, a marginal sea under severe eutrophication stress, a longer productive season, and changes in the phytoplankton community over the last few decades have likely impacted diet and condition of keystone species, from individual to population level. This study uses stable isotopes (δ13C, δ15N, and derived isotope niche metrics) to trace energy and nutrient flows in archived samples of blue mussel (Mytilus edulis trossulus) spanning 24 yr (1993–2016). We test if long‐term changes in isotope and elemental composition in mussels, as well as population abundance and biomass, can be explained by changes in abiotic and biotic variables, using partial least square regressions and structural equation modeling. We found decreasing trends in δ13C and δ15N as well as in mean size and total biomass of mussels, but no unidirectional changes in their stoichiometry or condition index. Changes in isotope composition were best explained by nitrogen‐fixing cyanobacteria, by increased terrestrial organic carbon from land runoff (reflecting precipitation) and by decreases in dissolved inorganic nitrogen (indicative of successful eutrophication mitigation) and in biomass of a mixotrophic ciliate species. The trophic niche (assessed from isotope niche) was included as the best predictor for both mussel body condition and the observed decline in their total biomass. This study reveals that altered trophic relationships from climate‐induced changes in the productivity base may strongly impact keystone species, with potential knock‐on effects on ecosystem functions.

According to ecological theory, two species cannot occupy the same niche. Using nitrogen isotope analyses (delta N-15) of amino acids, we tested the extent to which two sympatric deposit-feeding amphipods,Monoporeia affinisandPontoporeia femorata, partition their trophic resources. We found that trophic position (TP) and resynthesis index ( n-ary sumation V; a proxy for degradation status of ingested material prior to assimilation by the consumer) differ between species. The surface-feedingM. affinishad higher TP and intermediate n-ary sumation V, both pointing to a large contribution of metazoans in its diet.P. femorata, which feeds in the subsurface layers, had lower TP and a bimodal distribution of the n-ary sumation V values, supporting previous experimental evidence of a larger feeding niche. We also evaluated whether TP and n-ary sumation V values have consequences for amphipod fecundity and embryo viability and found that embryo viability inM. affiniswas negatively linked to TP. Our results indicate that the amino acid-delta N-15 data paired with information about reproductive status are useful for detecting differences in the trophic ecology of sympatric amphipods.

Anthropogenic pressures, such as contaminant exposure, may affect stable isotope ratios in biota. These changes are driven by alterations in the nutrient allocation and metabolic pathways induced by specific stressors. In a controlled microcosm study with the amphipod Gammarus spp., we studied effects of the beta-blocker propranolol on stable isotope signatures (delta N-15 and delta C-13), elemental composition (%C and %N), and growth (protein content and body size) as well as biomarkers of oxidative status (antioxidant capacity, ORAC; lipid peroxidation, TBARS) and neurological activity (acetylcholinesterase, AChE). Based on the known effects of propranolol exposure on cellular functions, i.e., its mode of action (MOA), we expected to observe a lower scope for growth, accompanied by a decrease in protein deposition, oxidative processes and AChE inhibition, with a resulting increase in the isotopic signatures. The observed responses in growth, biochemical and elemental variables supported most of these predictions. In particular, an increase in %N was observed in the propranolol exposures, whereas both protein allocation and body size declined. Moreover, both ORAC and TBARS levels decreased with increasing propranolol concentration, with the decrease being more pronounced for TBARS, which indicates the prevalence of the antioxidative processes. These changes resulted in a significant increase of the delta N-15 and delta C-13 values in the propranolol-exposed animals compared to the control. These findings suggest that MOA of beta-blockers may be used to predict sublethal effects in non-target species, including inhibited AChE activity, improved oxidative balance, and elevated stable isotope ratios. The latter also indicates that metabolism-driven responses to environmental contaminants can alter stable isotope signatures, which should be taken into account when interpreting trophic interactions in the food webs.

The evidence regarding BMAA occurrence in the Baltic Sea is contradictory, with benthic sources appearing to be more important than pelagic ones. The latter is counterintuitive considering that the identified sources of this compound in the food webs are pelagic primary producers, such as diatoms, dinoflagellates, and cyanobacteria. To elucidate BMAA distribution, we analyzed BMAA in the pelagic and benthic food webs in the Northern Baltic Proper. As potential sources, phytoplankton communities were used. Pelagic food chain was represented by zooplankton, mysids and zooplanktivorous fish, whereas benthic invertebrates and benthivorous fish comprised the benthic chain. The trophic structure of the system was confirmed by stable isotope analysis. Contrary to the reported ubiquitous occurrence of BMAA in the Baltic food webs, only phytoplankton, zooplankton and mysids tested positive, whereas no measurable levels of this compound occurred in the benthic invertebrates and any of the tested fish species. These findings do not support the widely assumed occurrence and transfer of BMAA to the top consumers in the Baltic food webs. More controlled experiments and field observations are needed to understand the transfer and possible transformation of BMAA in the food web under various environmental settings.

The isotopic niche has become an established concept in trophic ecology. However, the assumptions behind this approach have rarely been evaluated. Evidence is accumulating that physiological stress can affect both magnitude and inter-individual variability of the isotopic signature in consumers via alterations in metabolic pathways. We hypothesized that stress factors (inadequate nutrition, parasite infestations, and exposure to toxic substances or varying oxygen conditions) might lead to suboptimal physiological performance and altered stable isotope signatures. The latter can be misinterpreted as alterations in isotopic niche. This hypothesis was tested by inducing physiological stress in the deposit-feeding amphipod Monoporeia affinis exposed to either different feeding regimes or contaminated sediments. In the amphipods, we measured body condition indices or reproductive output to assess growth status and delta C-13 and delta N-15 values to derive isotope niche metrics. As hypothesized, greater isotopic niche estimates were derived for the stressed animals compared to the control groups. Moreover, the delta N-15 values were influenced by body size, reproductive status and parasite infestations, while delta C-13 values were influenced by body size, oxygen conditions and survival. Using regression analysis with isotope composition and growth variables as predictors, we were able to discriminate between the amphipods exposed to nutritionally or chemically stressful conditions and those in the control groups. Thus, interpretation of isotopic niche can be confounded by natural or anthropogenic stressors that may induce an apparent change in isotopic niche. These findings stress the importance of including measures of growth and health status when evaluating stable isotope data in food web studies.

Stable nitrogen isotopes (delta N-15) are used as indicators of trophic position (TP) of consumers. Deriving TP from delta N-15 of individual amino acids (AAs) is becoming popular in ecological studies, because of lower uncertainty than TP based on bulk delta N-15 (TPbulk). This method would also facilitate biomagnification studies provided that isotope fractionation is unaffected by toxic exposure. We compared TPAA and TPbulk estimates for a sediment-dwelling bivalve from two coastal sites, a pristine and a contaminated. Chemical analysis of PCB levels in mussels, sediments, and pore water confirmed the expected difference between sites. Both methods, but in particular the TPAA underestimated the actual TP of bivalves. Using error propagation, the total uncertainty related to the analytical precision and assumptions in the TP calculations was found to be similar between the two methods. Interestingly, the significantly higher intercept for the regression between T-AA, and TPbulk in the contaminated site compared to the pristine site indicates a higher deamination rate due to detoxification as a result of chronic exposure and a higher N-15 fractionation. Hence, there is a need for controlled experiments on assumptions underlying amino acid-specific stable isotope methods in food web and bimagnification studies.

Stable nitrogen isotopes (δ15N) are used as indicators of trophic position (TP) of consumers. Deriving TP from δ15N of individual amino acids (AAs) is becoming popular in ecological studies, because of lower uncertainty than TP based on bulk δ15N (TPbulk). This method would also facilitate biomagnification studies provided that isotope fractionation is unaffected by toxic exposure. We compared TPAA and TPbulk estimates for a sediment-dwelling bivalve from two coastal sites, a pristine and a contaminated. Chemical analysis of PCB levels in mussels, sediments, and pore water confirmed the expected difference between sites. Both methods, but in particular the TPAA underestimated the actual TP of bivalves. Using error propagation, the total uncertainty related to the analytical precision and assumptions in the TP calculations was found to be similar between the two methods. Interestingly, the significantly higher intercept for the regression between TPAA and TPbulk in the contaminated site compared to the pristine site indicates a higher deamination rate due to detoxification as a result of chronic exposure and a higher 15N fractionation. Hence, there is a need for controlled experiments on assumptions underlying amino acid-specific stable isotope methods in food web and bimagnification studies.

Stable nitrogen isotopes (δ15N) are used as indicators of trophic position (TP) of consumers. Deriving TP from δ15N of individual amino acids (AAs) is becoming popular in ecological studies, because of lower uncertainty than TP based on bulk δ15N (TPbulk). This method would also facilitate biomagnification studies provided that isotope fractionation is unaffected by toxic exposure. We compared TPAA and TPbulk estimates for a sediment-dwelling bivalve from two coastal sites, a pristine and a contaminated. Chemical analysis of PCB levels in mussels, sediments, and pore water confirmed the expected difference between sites. Both methods, but in particular the TPAA underestimated the actual TP of bivalves. Using error propagation, the total uncertainty related to the analytical precision and assumptions in the TP calculations was found to be similar between the two methods. Interestingly, the significantly higher intercept for the regression between TPAA and TPbulk in the contaminated site compared to the pristine site indicates a higher deamination rate due to detoxification as a result of chronic exposure and a higher 15N fractionation. Hence, there is a need for controlled experiments on assumptions underlying amino acid-specific stable isotope methods in food web and bimagnification studies.

Trophic magnification factor (TMF) analysis employs stable isotope signatures to derive biomagnification potential for environmental contaminants. This approach relies on species delta N-15 values aligning with their trophic position (TP). This, however, may not always be true, because toxic exposure can alter growth and isotope allocation patterns. Here, effects of PCB exposure (mixture of PCB18, PCB40, PCB128, and PCB209) on delta N-15 and delta C-13 as well as processes driving these effects were explored using the cladoceran Daphnia magna. A two-part experiment assessed effects of toxic exposure during and after exposure; juvenile daphnids were exposed during 3 days (accumulation phase) and then allowed to depurate for 4 days (depuration phase). No effects on survival, growth, carbon and nitrogen content, and stable isotope composition were observed after the accumulation phase, whereas significant changes were detected in adults after the depuration phase. In particular, a significantly lower nitrogen content and a growth inhibition were observed, with a concomitant increase in delta N-15 (+0.1 parts per thousand) and decrease in delta C-13 (-0.1 parts per thousand). Although of low magnitude, these changes followed the predicted direction indicating that sublethal effects of contaminant exposure can lead to overestimation of TP and hence underestimated TMF.

Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N-2 allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.

The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on delta N-15 and delta C-13 values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. The cladoceran Daphnia magna was used in two experiments that were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative effect of growth rate and a positive effect of temperature on the consumer-diet discrimination factor for delta N-15 and delta C-13, with no effects on the C:N ratio (Experiment 1). In lindane-exposed daphnids, a significant growth inhibition was observed, with concomitant increase in metabolic costs and significantly elevated size-specific delta N-15 and delta C-13 values. Moreover, a significantly higher incorporation of carbon relative to nitrogen, yet a concomitant decrease in C:N ratio was observed in the exposed animals. Together, these results have methodological implications for determining trophic positions and TMF in polluted environments, where elevated delta N-15 values would translate into overestimated trophic positions and underestimated TMF. Furthermore, altered delta C-13 values may lead to erroneous food-chain assignment of the consumer in question.

Žemės atmosfera yra svarbiausia klimato sferos dalis ir jautriausias antropogeninei taršai aplinkos sandas. Atmosferoje vykstantys procesai pakeičia ekosistemose per šimtmečius nusistovėjusius procesus – stebime įvairias globalinės klimato kaitos sukeltas pasekmes. Mokslinė šio darbo idėja nukreipta į įvairiapusį atmosferos aerozolio dalelių savybių ir prigimties tyrimą bei tyrimo metodų plėtrą, pasiremiant naujausiomis aplinkotyros mokslo žiniomis, akcentuojant pastarojo dešimtmečio masių spektrometrijos pasiekimus. Šio darbo tikslas yra organinių medžiagų ir juodosios anglies atmosferos aerozolio dalelėse kilmės, aerozolio sudėties ir formavimosi tyrimai bei naujų tyrimo metodų plėtra. Darbe eksperimentiškai įrodyta, kad anglies izotopų santykis antropogeninės kilmės aerozolio dalelėse atitinka deginamo kuro izotopų santykį ir šis parametras tinka, identifikuojant aerozolio dalelių šaltinį. Šis izotopų santykis, kaip metodinė priemonė, buvo panaudotas tiriant įvairios prigimties aerozolio sudėtį, savybes ir kilmę. Tiriant aerozolio daleles tolimojoje oro pernašoje stebėjome elementinės anglies δ13C verčių kaitą akumuliacinėje modoje nuo -22,9 ‰ iki -26,3 ‰, organinės anglies δ13C = -28 ‰. Iš δ13C verčių nustatyta, jog elementinės anglies pirmtakai aerozolio dalelėse buvo degimo produktai, organinės anglies šaltinis – lakūs organiniai junginiai iš augalų. Vietinės kilmės dalelių, didesnių už 1 μm, stebėta karbonatinė komponentė. Apjungus masių ir izotopų santykių masių... [toliau žr. visą tekstą], The development of industry, transport, agriculture and power engineering inevitably create problems related to the impact of generated waste on the environment as well as other undesirable processes. The atmosphere is the main component of the Earth’s climate system because changes occurring due to the human economic activity result in serious environmental impacts in all components of the ecosystem as well as the Earth’s climate self-regulation system is disturbed. The objective of this work was to investigate the origin, sources and formation of organic compounds and black carbon in atmospheric aerosol particles and to develop new research methods. To attain this objective the following tasks have been formulated: Development of the identification method for the aerosol origin and source by investigating the carbon isotope mass ratios, illustration of possibilities of the carbon isotope ratio method by identifying the aerosol particle origin during the air mass long-range transport at the Preila Environmental pollution research station, investigation of variation of the black carbon amount in aerosol particles in the diesel engine exhaust depending on the engine working parameters and fuel composition, investigation of the carbon isotope ratio variation in natural aerosol depending on the aerosol particle size distribution, determination of the partial contribution of natural and anthropogenic particles in aerosol by investigation of stable carbon and radiocarbon isotope... [to full text]

The development of industry, transport, agriculture and power engineering inevitably create problems related to the impact of generated waste on the environment as well as other undesirable processes. The atmosphere is the main component of the Earth’s climate system because changes occurring due to the human economic activity result in serious environmental impacts in all components of the ecosystem as well as the Earth’s climate self-regulation system is disturbed. The objective of this work was to investigate the origin, sources and formation of organic compounds and black carbon in atmospheric aerosol particles and to develop new research methods. To attain this objective the following tasks have been formulated: Development of the identification method for the aerosol origin and source by investigating the carbon isotope mass ratios, illustration of possibilities of the carbon isotope ratio method by identifying the aerosol particle origin during the air mass long-range transport at the Preila Environmental pollution research station, investigation of variation of the black carbon amount in aerosol particles in the diesel engine exhaust depending on the engine working parameters and fuel composition, investigation of the carbon isotope ratio variation in natural aerosol depending on the aerosol particle size distribution, determination of the partial contribution of natural and anthropogenic particles in aerosol by investigation of stable carbon and radiocarbon isotope... [to full text], Žemės atmosfera yra svarbiausia klimato sferos dalis ir jautriausias antropogeninei taršai aplinkos sandas. Atmosferoje vykstantys procesai pakeičia ekosistemose per šimtmečius nusistovėjusius procesus – stebime įvairias globalinės klimato kaitos sukeltas pasekmes. Mokslinė šio darbo idėja nukreipta į įvairiapusį atmosferos aerozolio dalelių savybių ir prigimties tyrimą bei tyrimo metodų plėtrą, pasiremiant naujausiomis aplinkotyros mokslo žiniomis, akcentuojant pastarojo dešimtmečio masių spektrometrijos pasiekimus. Šio darbo tikslas yra organinių medžiagų ir juodosios anglies atmosferos aerozolio dalelėse kilmės, aerozolio sudėties ir formavimosi tyrimai bei naujų tyrimo metodų plėtra. Darbe eksperimentiškai įrodyta, kad anglies izotopų santykis antropogeninės kilmės aerozolio dalelėse atitinka deginamo kuro izotopų santykį ir šis parametras tinka, identifikuojant aerozolio dalelių šaltinį. Šis izotopų santykis, kaip metodinė priemonė, buvo panaudotas tiriant įvairios prigimties aerozolio sudėtį, savybes ir kilmę. Tiriant aerozolio daleles tolimojoje oro pernašoje stebėjome elementinės anglies δ13C verčių kaitą akumuliacinėje modoje nuo -22,9 ‰ iki -26,3 ‰, organinės anglies δ13C = -28 ‰. Iš δ13C verčių nustatyta, jog elementinės anglies pirmtakai aerozolio dalelėse buvo degimo produktai, organinės anglies šaltinis – lakūs organiniai junginiai iš augalų. Vietinės kilmės dalelių, didesnių už 1 μm, stebėta karbonatinė komponentė. Apjungus masių ir izotopų santykių masių... [toliau žr. visą tekstą]