Supporting information:

Transcription

1 Supporting information: Food web accumulation of cyclic siloxanes in Lake Mjøsa, Norway Katrine Borgå 1 *, Eirik Fjeld 1, Amelie Kierkegaard 2, Michael McLachlan 2 1 Norwegian Institute for Water Research (NIVA), Gaustadallèen 21, N-0349 Oslo, Norway 2 Department of Applied Environmental Science (ITM), Stockholm University, SE Stockholm, Sweden. Content: 16 Pages of Tables, Figures and Text Table S1. Zooplankton sampling information Table S2. Fish sampling information Table S3. Weighting of sample means according to number of samples. Table S4. Content of cvms in the field blanks (ENV+ pouches) Table S5. Concentration on a wet weight basis of cvms in food web samples from Lake Mjösa. Table S6. Product-moment correlation coefficients (r: left triangular matrix) between trophic position (TL). Figure S1. Map of Lake Mjøsa, Norway. Figure S2. The concentration on a wet weight basis of D5.D4 and D6 in samples from a food web in Lake Mjösa. Duplicates are shown in lighter colour. Figure S3. Relationship between size of fish and cvms concentrations (ng/g lipid weight). Text: Comparison to other studies Cannibalism in smelt S1

2 Figure S1. Lake Mjøsa (60 53 N 10 41E), Norway, with the largest cities marked with large dots. Station 1 (St.1) is Helgøya west were trout, vendace and one smelt sample were collected. Station 2 (St. 2) is Ottestad, east of Helgøya, where 4 samples of smelt were collected, and Station 3 (St. 3) is Skreia, south of Helgøya, where the invertebrates were collected. S2

3 Table S1. Zooplankton sampling information Food web component Sampling area NIVA sample ID Date Moisture % 15N, 13C, Trophic level Zooplankton epilimnion Helgøya Vest Zooplankton epilimnion Helgøya Vest Zooplankton epilimnion Helgøya Vest Zooplankton epilimnion Helgøya Vest Zooplankton hypolimnion Helgøya Vest 7263, Zooplankton hypolimnion Helgøya Vest 7263, Zooplankton hypolimnion Helgøya Vest 7263, Zooplankton hypolimnion Helgøya Vest 7263, Mysis relicta Helgøya Vest 7260, 7261, Mysis relicta Helgøya Vest 7260, 7261, Mysis relicta Helgøya Vest 7260, 7261, Mysis relicta Helgøya Vest 7260, 7261, S3

4 Table S2. Sampling information for fish from Lake Mjøsa autumn Species Sampling area Sample Sample jar Date Length (mm) Weigth (g) no ID 15N, 13C, TL a Local Fisher Trout Helgøya Vest Ø1 Ø H. Moen Trout Helgøya Vest Ø2 Ø H. Moen Trout Helgøya Vest Ø3 Ø H. Moen Trout Helgøya Vest Ø4 Ø H. Moen Trout Helgøya Vest Ø5 b Ø H. Moen Smelt Helgøya Vest K1a K H. Moen Smelt Helgøya Vest K1b K H. Moen Smelt Helgøya Vest K1c K H. Moen Smelt Ottestad K2a K O. Nashoug Smelt Ottestad K2b K O. Nashoug Smelt Ottestad K3a K O. Nashoug Smelt Ottestad K3b K O. Nashoug Smelt Ottestad K4a K O. Nashoug Smelt Ottestad K4b K O. Nashoug Smelt Ottestad K5a K O. Nashoug Smelt Ottestad K5b K O. Nashoug Vendace Helgøya Vest S1a S H. Moen Vendace Helgøya Vest S1b S H. Moen Vendace Helgøya Vest S2a S H. Moen Vendace Helgøya Vest S2b S H. Moen Vendace Helgøya Vest S3a S H. Moen Vendace Helgøya Vest S3b S H. Moen Vendace Helgøya Vest S4a S H. Moen Vendace Helgøya Vest S4b S H. Moen Vendace Helgøya Vest S5a S H. Moen S4

5 Vendace Helgøya Vest S5b S H. Moen a TL= trophic level estimated from the 15 N. b Stomach content: 5 vendace S5

6 Table S3. Number of samples analysed (N) and weighting of sample means according to number of samples (Weight). The weighted averages were used in the linear regression of the respective contaminant (D5 or POP) onto trophic level (see Table 2 in main text). Species Zooplankton Mysis Vendace Smelt Trout Epilimnion Hypolimnion N D (5) a 5 8 (5) a Weight D N POPs Weight POPs a For vendace and trout, 2 and 3 respectively, of the 5 fish samples were analysed in replicate S6

7 Lake Mjøsa results The concentrations normalized to wet weight are presented in Figure S2 and in Table S5. The results are not blank corrected. Concentrations below the LOQ are included as measured values. S7

8 S8

9 Figure S2. The D4, D5, and D6 concentrations on a wet weight basis in samples from a food web in Lake Mjösa. Duplicates are shown in lighter color. Black bars are levels <LOQ. S9

10 Table S4. Content of cvms in the field blanks (ENV+ pouches) autumn Sampling dates in brackets. The mean cvms content of the unexposed pouches was subtracted from the cvms content of the field blanks when evaluating the results, as cvms had been observed to slowly leak out of thoroughly pre-cleaned ENV+ during storage. Where 2 field blanks were applied (e.g. for the zooplankton samples) the sum of the contents were applied. Content in field blanks Content in field when unexposed blanks. ng subtracted. ng D4 D5 D6 D4 D5 D6 unexposed freezer ITM unexposed freezer ITM unexposed freezer ITM unexposed NIVA unexposed mean Vendace1-5, Smelt 1, Trout 3 Air (100911) Smelt 2-5 (101028) Trout 5 (101020) Trout 4 (101019) Vendace 1-5, Smelt 1, Trout 3 (100911) Trout 1, Trout 2 (101012) Zooplankton epilimnion (100922) Zooplankton epilimnion (100927) Container epilimnion (100922) Container hypolimnion (100922) Mysis Zooplankton hypolimnion (100922) S10

11 Table S5. Concentration on a wet weight basis of cvms in food web samples from Lake Mjøsa. Levels measured below limit of quantification (LOQ) are presented as measured values preceded by <. Samples D4 D5 D6 ng/g ww ng/g ww ng/g ww Brown trout Brown trout Brown trout 3 < < Brown trout 4 < < < 0.46 Brown trout Smelt 1 < Smelt 2 < Smelt 3 < Smelt Smelt 5 < Vendace Vendace 2 < < Vendace Vendace 4 < Vendace 5 < < Mysis < < 0.77 Mysis < < 1.0 Mysis < < 1.1 Mysis < < 1.2 S11

12 Zooplankton hypo < < 2.1 Zooplankton hypo < < 2.8 Zooplankton hypo < < 2.2 Zooplankton hypo < < 2.4 Zooplankton epi < 1.4 < 3.5 < 1.8 Zooplankton epi < 2.0 < 2.8 < 2.2 Zooplankton epi < 2.9 < Zooplankton epi < 3.7 < 4.0 < 2.0 Control samples Herring homogenate < Herring homogenate < Herring homogenate < < 1.2 Herring homogenate < S12

13 Table S6. Product-moment correlation coefficients (r: left triangular matrix) between trophic position (TL), D5 and selected legacy contaminants, together with their respective significance levels (p: above the main diagonal, in italics). All coefficients are based on log-transformed concentrations and the significance levels are based on n = 18. Variable TL D5 PCB-153 PCB-180 ppdde PBDE-47 PBDE-99 TL < < < < D PCB < < < PCB < < p.p'-dde < BDE BDE Figure S3. Relationship between size of fish and D5 concentrations (ng/g lipid weight). S13

14 Comparison to other studies Zooplankton (Arctic and Humber Estuary UK): The D5 concentrations (ng/g ww) in hypolimnion zooplankton and Mysis were 2-10 times higher than the Arctic zooplankton MDL. The D5 levels (ng/g ww) in zooplankton were lower than levels in the benthic estuarine ragworm 1. Fish (Svalbard, Arctic and Humber Estuary,UK): The D4 levels in Lake Mjøsa fish were lower than the reported MDL for Arctic fish and LOQ for estuarine benthic flounder, which were also all below the MDL 2 or LOQ 1, respectively. The Lake Mjøsa fish D5 concentrations (ng/g ww) are in the same range as in the benthic estuarine flounder (UK) 1, and in the same range as the benthic sculpin, but higher than the benthopelagic Atlantic cod (Svalbard) 2. On a lipid weight basis however, fish from Lake Mjøsa have 1-2 orders of magnitude higher cvms levels than the Svalbard fish, which reflects the much lower lipid content in Lake Mjøsa fish than the Arctic fish ( % compared to %). The D6 levels in fish from Lake Mjøsa were comparable to cod and sculpin from Svalbard 2, and to flounder from the Humber Estuary (UK) 1. Zooplankton and fish (outer Oslofjord): D5 concentrations (ng/g ww) varied from being similar between Mysis and Oslofjord zooplankton, to 3-4 times higher levels in Lake Mjøsa hypolimnion and 2-3 times lower levels in Lake Mjøsa epilimnion zooplankton compared to the outer Oslofjord 3. The Lake Mjøsa fish had greater D4 and D5 concentrations (ng/g ww) than outer Oslofjord fish, 3-10 times, and 2-3 orders of magnitude, respectively (Haddock and Atlantic cod chosen for comparison, with comparable lipid content to Lake Mjøsa biota) 3. If the comparison is done on a lipid weight basis, the Lake Mjøsa Mysis have comparable D5 levels as plankton from the Oslofjord, whereas zooplankton from epi and hypolimnion have 2-3 times higher levels than the marine plankton. Lipid normalized concentrations in fish were higher in Lake Mjøsa fish than haddock and cod from Oslofjord (D4: 5-10 times, D5: times, D6: from comparable to 6 times) 3. Zooplankton and fish (inner Oslofjord): The cvms levels were higher in the inner Oslofjord than in the outer, and thereby, the Lake Mjøsa levels (ng/g lw) were more comparable to these; In fish D4 and D6 were generally in a comparable range (depending on species), whereas D5 was from comparable to 5 times higher in Lake Mjøsa than haddock and S14

15 cod. In zooplankton, D5 levels (ng/g lw) were lower in Lake Mjøsa than Oslofjord, with the highest Lake Mjøsa zooplankton concentrations approaching the Oslofjord levels. In Lake Mjøsa fish, the concentrations (ng/g ww) of D4, D5 and D6 were generally comparable to fish from the inner Oslofjord, with some exceptions; D4 levels were times greater in Lake Mjøsa than inner Oslofjord, and Haddock from inner Oslofjord had greater D6 levels than Lake Mjøsa fish (and cod). On a lipid weight basis, Lake Mjøsa fish had comparable cvms levels as cod and haddock from the inner Oslofjord, with the exception of smelt, which had high levels that were comparable to herring. Cannibalism in smelt One hypothesis to the shift of smelt around the regression line depending on compound was that the smelt had higher accumulation due to cannibalism; in other Nordic lakes, smelt has shown a shift in diet from predominantly zooplankton at younger and smaller sizes, and with increased degree of cannibalism in year 3+ and approximately 10 cm 4. Whereas the predominant diet of smaller smelt is on Mysis relicta and zooplankton such as D. galeata and L.macrurus 5, the present study included large smelt ( cm, g), thus it is likely that other smelt were parts of their diet. For compounds well-known to biomagnify, such as PCB-153 and PCB-180, however, cannibalism would result in higher trophic level compared to zooplanktivorous smelt, and also to higher contaminant concentrations. The potential shift in diet to increased cannibalism with increasing size would therefore not explain the sensitivity in TMF to inclusion or exclusion of smelt. In fact, for PCBs, smelt are on the regression line, and the TMF is not sensitive to its inclusion or not. References 1. Kierkegaard, A.; van Egmond, R.; McLachlan, M. S., Cyclic Volatile Methylsiloxane Bioaccumulation in Flounder and Ragworm in the Humber Estuary. Environmental Science & Technology 2011, 45, Warner, N. A.; Evenset, A.; Christensen, G.; Gabrielsen, G. W.; Borga, K.; Leknes, H., Volatile Siloxanes in the European Arctic: Assessment of Sources and Spatial Distribution. Environmental Science & Technology 2010, 44, S15

16 3. Powell, D. E.; Durham, J.; Huff, D. W.; Böhmer, T.; Gerhards, R.; Koerner, M., Bioaccumulation and trophic transfer of cyclic volatile methylsiloxane (cvms) materials in the aqiuatic marine food webs of the inner and outer Oslofjord, Norway. 2010, Final Report, Dow Corning, HES study no , 40 p. Accessed December Vinni, M.; Lappalainen, J.; Malinen, T.; Peltonen, H., Seasonal bottlenecks in diet shifts and growth of smelt in a large eutrophic lake. J. Fish Biol. 2004, 64, Sandlund, O. T.; Klyve, L.; Hagen, H.; Næsje, T. F., Krøkje i Mjøsa. Alderssammensetning, vekst og ernæring (Smelt in Lake Mjøsa. Age-composition, growth and diet). DVF-Mjøsundersøkelsen 1980, 2, S16