master The influence of ecological processes on the accumulation of persistent organochlorines in aquatic ecosystems Olof Berglund DISTRIBUTION OF THIS DOCUMENT IS IKLOTED FORBGN SALES PROHIBITED eX - Department of Ecology Chemical Ecology and Ecotoxicology Lund University, Sweden Lund 1999 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. The influence of ecologicalprocesses on the accumulation of persistent organochlorinesin aquatic ecosystems Olof Berglund Akademisk avhandling, som for avlaggande av filosofie doktorsexamen vid matematisk-naturvetenskapliga fakulteten vid Lunds Universitet, kommer att offentligen forsvaras i Bla Hallen, Ekologihuset, Solvegatan 37, Lund, fredagen den 17 September 1999 kl. 10. Fakultetens opponent: Prof. Derek C. G. Muir, National Water Research Institute, Environment Canada, Burlington, Canada. Avhandlingen kommer att forsvaras pa engelska. Organization Document name LUND UNIVERSITY DOCTORAL DISSERTATION Department of Ecology Dateofi=" Sept 1,1999 Chemical Ecology and Ecotoxicology S-223 62 Lund CODEN: SE-LUNBDS/NBKE-99/1016+144pp Sweden Authors) Sponsoring organization Olof Berglund Title and subtitle The influence of ecological processes on the accumulation of persistent organochlorines in aquatic ecosystems Abstract Several ecological processes influences the fate, transport, and accumulation of persistent organochlorines (OCs) in aquatic ecosystems. In this thesis, I have focused on two processes, namely (i) the food chain bioaccumulation of OCs, and (ii) the trophic status of the aquatic system. To test the biomagnification theory, I investigated PCB concentrations in planktonic food chains in lakes. The concentra­ tions of PCB on a lipid basis did not increase with increasing trophic level. Hence, I could give no support to the theory of bio­ magnification. Instead, lipid content explained most of the variation in PCB accumulation in these food chains. PCBs were differentially fractionated in the food chains, the relative amount of high molecular weight PCBs increased with increasing trophic level, indicating congener specific differences in either the accumulation or the elimination of PCBs at the different trophic levels. In another study, I investigated the relationship between OC concentrations and trophic level, measured as 3"N, in a specific predatory fish population. The dry weight OC concentrations and were related, indicating effects of prey choice on the OC accumulation. However, here also, lipid content explained the major part of the variation in OC concentrations, independent of trophic level (e. g. 315N). I investigated the effects of trophic status, measured as Tot-P concentration in water, on the concentrations of OCs in water, planktonic food chains and sediment in lakes. The dry weight concentrations of PCBs in phytoplankton were negatively related to the trophic status of the lakes. However, this relationship was explained by the decreasing lipid content of phyto­ plankton with lake trophic status. The phytoplankton in eutrophic lakes had lower lipid content than phytoplakton in oligotrophic lakes, possibly due to inter- and intraspecific differences in lipid content due to nutrient stress. The sediment accumulation and burial of PCB increased with increasing trophic status. Also, the relative amount of freely dissolved PCB in the water was lower in eutrophic lakes than in oligotrophic lakes. These results may be explained by an increased sedimentation of dead algae in eutrophic lakes, purging the water column of the lipophilic PCBs, enhancing sediment contamination. In lotic ecosystems, I found a positive correlation between the OC concentrations in fish and the Tot-P concentrations 1 7 in the stream water. I suggest that this may be a result of one or several processes differing between lotic and lentic systems, none of which are mutually exclusive. Processes likely to cause the observed correlation are; increased periphyton biomass in I lf eutrophic streams (e. g. decreased spiralling length), the shift from heterotrophy to autotrophy in eutrophic streams, and an tO increased load of OCs from the catchment area of eutrophic streams, due to different land use (e.g. agricultural land use). CIC 103 Keywords organochlorines, bioaccumulation, food chain, trophic status, biomass, lipids, plankton, fish, sediment, streams, spiralling Classification system and/or index terms (if any) Supplementary bibliographical information Language English ISSN and key title ISBN 91-7105-114-7 Recipient's notes Number of pages 144 Pike Security classification Distribution by(name and address) Olof Berglund, Chemical Ecology and Ecotoxicology, Ecology Building, S-223 62 Lund, Sweden I, the undersigned, being the copyright owner of the abstract of the above-mentioned dissertation, hereby grant to all reference sources permission to publish an^isseminate the abstract of the above-mentioned dissertation. l/fn - Tl Signature Date . The influence of ecological processes on the accumulation of persistent organochlorines in aquatic ecosystems Olof Berglund Dissertation Lund, 1999 A doctoral thesis at a university in Sweden is produced either as a monograph or a collection of papers. In the latter case, the introductory part constitutes the formal thesis, which summarises the accompanying papers. These have either already been published or are in manuscripts at various stages (in press, submitted or in ms). © Olof Berglund ISBN 91-7105-114-7 SE-LUNBDS/NBKE-99/1016+144pp 2 This thesis is based on the following papers, which are referred to by their Roman numerals. I. Berglund, O., Larsson, P., Ewald, G., and Okla, L. Bioaccumulation and differential partitioning of PCBs in freshwater, planktonic food webs. (■Submitted) II. Berglund, O., Larsson, P., and Broman, D. Organochlorine accumulation and stable isotopes in an Atlantic salmon (Salmo salar) population from the Baltic Sea - effects of omnivory and reproductive strategies. (Submitted) III. Berglund, O., Larsson, P., Ewald, G., and Okla, L. The effect of lake trophy on lipid content and PCB concentrations in planktonic food webs. (Manuscript) IV. Berglund, O., Larsson, P., Ewald, G., and Okla, L. Influence of trophic status on PCB dynamics in lake sediments and biota. {Manuscript) V. Berglund, O., Larsson, P., Bronmark, C., Greenberg, L., Eklov, A., and Okla, L. 1997. Factors influencing organochlorine uptake in age-0 brown trout {Salmo trutta) in lotic environments. Can. J. Fish. Aquat. Sci. 54: 2767-2774. Paper V is reprinted with permission from the publisher. 3 Till Mor och Far. 4 Contents: Introduction 7 OC accumulation in aquatic organisms 14 Lipid content and composition 15 Elimination 16 Size, age, and growth rate 16 Biomagnification ofOCs 17 Stable isotopes and food chain effects 19 Trophic status and OC accumulation: lakes 21 Biomass 21 Sedimentation 23 Volatilisation 25 Recycling 25 Stratification 26 Trophic status and OC accumulation: streams 27 Spiralling and biomass 27 Heterotrophy vj . autotrophy 29 Watershed influence 29 Conclusions 30 Future research 32 77ze dynamics ofOCs in streams 32 77ze dynamics of lipids in ecosystems 33 References 34 Tack 43 5 6 Introduction The contamination of aquatic ecosystems by persistent organochlorines (OCs) has been of major concern for decades. Due to their persistence to chemical and microbial breakdown, OCs are today distributed worldwide, even in regions were they have never been applied (Muir et al. 1990; Tanabe et al. 1983). The OCs are transported in the atmosphere and redistributed both on a global and local scale via volatilisation and subsequent washout by precipitation, dry deposition, or gas exchange (Bidleman 1988; Simonich and Hites 1994, 1995). The process of global redistribution of OCs has been termed "global distillation”. The global distillation theory predicts that compounds will be fractionated latitudinally, depending on the ambient temperature and the volatility of the compound (Wania and Mackay 1993). Compounds with low volatility will remain in warmer regions, while compounds of higher volatility will be transported to colder regions, far from the source. Polychlorinated biphenyls (PCBs) and DDTs, both considered "semivolatile", are predicted to deposit in temperate regions (Wania and Mackay 1993), where, as an effect, concentrations in organisms may be higher than in the source areas (Larsson et al. 1995). Today, the use and production of most OCs have been banned or severely restricted in most industrialised countries. The main source of OCs to aquatic systems in temperate regions is, therefore, considered to be atmospheric deposition (Swackhamer and Hites 1988; Larsson and Okla 1989; Muir et al. 1990). The atmospherically transported OCs reach the freshwater systems via different routes. A fraction is deposited directly on lake or river surfaces via wet and dry deposition, or air-water gas exchange over the water surface. The major part of the OCs, however, is deposited on land in the watershed areas of the rivers and lakes. Once deposited, several different ecological processes in the watershed area, the streams and rivers, and the lakes affect the transport and fate of the OCs, before reaching the oceans (Fig. 1). After deposition on the ground or soil surface, the OCs can follow several different transport pathways before reaching the freshwater ecosystems. The nature of the watershed area will, therefore, have a major influence on the transport of the OCs to