Abstract # 0000

1. Abstract # 0000 TRACE ELEMENTS TROPHODYNAMICS IN FISH FROM NORTH PATAGONIA LAKES Revenga, J.E.1; Campbell, L.M.2; Arribere, M. A..3,4; Perez Catan, S.3; Bubach, D.3 1Universidad Nacional del Comahue-CRUB, Quintral 1250, 8400 Bariloche Argentina;2School of Environmental Studies, Saint Mary’sUniversity, 923 RobieStreet, Halifax, Nova Scotia, Canada B3H-3C3; 3Laboratorio de Análisis por Activación Neutrónica, UAIN, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Bustillo 9500, 8400 Bariloche, Argentina; 4Instituto Balseiro, Universidad Nacional de Cuyo y CNEA, Bustillo 9500, 8400 Bariloche, Argentina Premio Mejor poster Introduction Results Discussion • The potentially toxic elements chromium (Cr), cobalt (Co) and arsenic (As) are studied in fish from lakes Nahuel Huapi and Moreno (Nahuel Huapi National Park) and Futalaufquen (Los Alerces National Park). • Increased Cr and As concentrations in mussels Diplodonchilenis from lakes Nahuel Huapi and Moreno, in Nahuel Huapi National Park, were associated with human settlements (Ribeiro Guevara et al., 2004). • Higher proportions of benthic/littoral preys in diets were associated with higher [Cr] in fish from Lake Moreno, whereas biodilution trends of Cr, Co and As were reported in the whole biota of the same lake (Revenga et al. 2012). • The objective of the present work is to compare, by using carbon (C) and nitrogen (N) stable isotopes, Cr, Co and As pathways and bioaccumulation trends previously described in Lake Moreno, with those of top predator fish from several regional lakes (TPFSL) Question 1: Are higher proportions of benthic/littoral preys (higher 13C values) associated with higher trace elements concentrations ([elements]) in top predator fish from different species and several lakes (TPFSL) ? Hypothesis 1: Recently, a significant positive regression between Log([Cr]) and 13C was reported in fish from Lake Moreno (Revenga et al., 2012) and then, the same pattern (for Cr, and other elements) can be expected in fish from the same species. Result 1: Significant positive regression was found between Log([Cr]) and 13C in top predator fish from several lakes (TPFSL) (Fig. 1 A, B), whereas the regressions were non significant for Log(As) and Log([Co]) and 13C. Question 2: Do top predator fish of lower trophic level (lower 15N values) bioaccumulate more trace elements? Hypothesis 2: Top predator fish from different (and even the same) species can show variables 15N values (Arcagni et al., in press). If biodilution patterns reported in the whole biota of Lake Moreno (Revenga et al., 2012) for Cr, Co and As, are also present in other lakes, top predator fish with lower trophic levels (lower 15N values) should have higher [elements]. Result 2. There was significant positive regression between Log([Cr]) and 15N in TPFSL (Fig. 2, A-B). Nevertheless the regression appeared strongly influenced by a separate cluster of data from Lake Futalaufquen, Fig.2, B). No significant regressions were found for As and Co (Fig. 2, C and D). • The high degree of mixing shown in Figs. 1A, B for both fish species and lakes of provenance along the 13C axis, strongly suggests that these factors are not important. In fact, higher proportion of benthic/littoral prey items (higher 13C values) relative to pelagic prey items in fish diet is a more important factor. The same was not observed for As or Co concentrations in fish. • The importance of benthic/littoral dietary contribution to Cr concentrations in fish is consistent with observations in fish from Lake Moreno (Revenga et al. 2012). • Data from Figs. 2A, B show that a separated cluster of data (Lake Futalaufquen), probably due to different preys composition, could obscure interpretation of biodilution modeling of Cr in fish. • Biodilution trends reported by Revenga et al. (2012) for Cr, Co and As in the whole biota of Lake Moreno were not reflected in TPFSL as indicated by non significant regressions (Figs. 2C, D). More homogeneous excretory abilities in all top predator fish species relative to invertebrates could be a possible explanation. Figure 1. Linear regression between Log([Cr]) and 13C (as C source indicator) in top predator fish from lakes Futalaufquen, Nahuel Huapi and Moreno West (slope= 0.22, intercept = 4.96, r2 = 0.11, p < 0.007, N = 65. A: fish shown by species; B: fish shown by lake. Notice fish species and lakes of origin intermixed along 13C axis. Material and Methods Conclusions Study site. Sampling Lakes Nahuel Huapi and Moreno West, (40º 8´-41º 35´ S, 71º 2´-71º 57´ W) and Lake Futalaufquen (42º 56´-43º 12´ S, 71º 34 -72º 07´ W). Lake Nahuel Huapi receives sewage from the town of S.C. de Bariloche in one main site. Samples were taken between 2004 and 2009. Submerged macrophytes, biofilm and macroinvertebrates were hand-picked. Fish species were caught with gill nets and included brook trout (Salvelinusfontinalis), rainbow trout (Oncorhynchusmykiss), brown trout (Salmotrutta) and creole perch (Percichthyssp.). Plankton was separated by size fractions in “Phytoplankton” (<53µm) (nanoglagellates, small ciliates, diatoms and dinoflagellates); “mixed plankton” (53-200µm) (small copepods nauplii, large mixotrophic ciliates and larger algae) and zooplankton (>200µm) (copepods and cladocerans). Analysis [Cr], [Co] and [As] were measured by using Instrumental Neutron Activation Analysis (INAA) at Centro AtómicoBariloche, Argentina. Muscle concentrations were measured in fish whereas whole body concentrations were determined for invertebrates except for molluscs and crabs (shell and digestive tract removed). Stable carbon (13C) and nitrogen (15N) isotope values were obtained by using Isotopic Ratio Mass Spectrometer (IRMS) at Queen’s University, Canada. • The results strongly suggest that benthic/littoral prey species are important for Cr pathway to TPFSL but not for As and Co, in a consistent way with fish from Lake Moreno • Biodiliution trends for Cr, Co and As reported in the whole biota of Lake Moreno are not reflected in TPFSL communities. • The lake of provenance could obscure results on Cr (and probably other elements) trophodynamics. References • Arcagni, M., Campbell, L.M., Arribere, M.A., Kyser, K., Klasse, K., Casaux, Miserendino, M.L., R., Ribeiro Guevara, S. Food web structure of Lake Moreno (Northwest Patagonia, Argentina) usingcarbon and nitrogenstableisotopes. Limnologica, in press • Revenga, J., Campbell, L., Arribere, M., Ribeiro Guevara, S. 2012. Arsenic, cobalt and chromium food web biodilution in a Patagonia mountainlake. Ecotoxicol. Environ. Safe. 81, 1-10. • Ribeiro Guevara, S., Bubach, D.F., Vigliano, P.H., Lippolt, G., Arribere, M.A. 2004. Heavy metal and other trace elements in native mussel Diplodonchilensis from Northern Patagonia Lakes, Argentina. Biol. Trace Elem. Res. 102, 245–263. Acknoledgements Figure 2. Linear regressions between Log([elements]) and 15N(as a trophic level indicator) in top predator fish from lakes Futalaufquen, Nahuel Huapi and Moreno West . Figs. 2 A-B: slope = 0.26, intercept = -2.61, p < 0.002, N = 65; C-D: non significant . We thank the assistance of Lic. Marina Arcagni and Mr. Ricardo Sanchez in all the field work; the RA-6 reactor staff, Centro AtomicoBariloche, for the irradiation of the samples; Dr. KurtKyser and Ms. Kerry KlassenfromQueen’s Facility for Isotope Research, Queen’s University, for isotopes measurements. Thisworkwaspartially funded by projects PICT2005 33838 and PICT2003 1051 of theANPCyT (Agencia Nacional de PromocionCientıfica y Tecnologica) of Argentina and The Canadian Government Department of Foreign Affairs and Trade Emerging Leaders in the Americas ELAP program.