Environmental Pollution 196 (2015) 313e320
Contents lists available at ScienceDirect
Environmental Pollution journal homepage: www.elsevier.com/locate/envpol
Bioaccumulation of hepatotoxins e A considerable risk in the Latvian environment €a € c, 1, Ingrida Purina a, b, Maija Balode a, b, Olli Sjo € vall d, Ieva Barda a, b, *, 1, Harri Kankaanpa Jussi Meriluoto d Latvian Institute of Aquatic Ecology, 8 Daugavgrivas Str., LV-1048 Rıga, Latvia University of Latvia, Faculty of Biology, 4 Kronvalda Blv., LV-1586 Rıga, Latvia c Finnish Environment Institute (SYKE), Marine Research Centre, Hakuninmaantie 6, FIN-00430 Helsinki, Finland d €katu 6, FI-20520 Turku, Finland Åbo Akademi University, Department of Biosciences/Biochemistry, Tykisto a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 July 2014 Received in revised form 1 October 2014 Accepted 15 October 2014 Available online
The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form a dynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002e2007. The freshwater unionids accumulated toxins efficiently, followed by snails. In contrast, Dreissena polymorpha and most lake fishes (except roach) accumulated much less hepatotoxins. Significant nodularin-R concentrations were detected also in marine clams and flounders. No transfer of nodularin-R and microcystins between lake and brackish water systems took place. Lake mussels can transfer hepatotoxins to higher organisms, and also effectively remove toxins from the water column. Obvious health risks to aquatic organisms and humans are discussed. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Hepatotoxins Bioaccumulation Invertebrates Fish Health risks
1. Introduction Cyanobacteria can produce a variety of bioactive compounds that affect aquatic organisms. Among these hepatotoxic microcystins (MCs) are the most common in freshwater environments, and are produced by several species of cyanobacteria of the genera Microcystis, Planktothrix and Anabaena (Sivonen and Jones, 1999). MCs are cyclic heptapeptides, occurring in more than 80 structural congeners of different toxicity (Dietrich and Hoeger, 2005). New MCs are still being discovered. An analogous pentapeptide hepatotoxin nodularin-R (NOD-R) is produced by the cyanobacterium Nodularia spumigena that occurs commonly in brackish waters (Ibelings and Chorus, 2007). In the liver, NOD-R and MCs inhibit the key regulatory enzymes: serineethreonine protein phosphatases (PPs) 1, 2A, and 3 that participate, e.g., in carbohydrate and lipid metabolism, regulation of apoptosis and cell divisions rates (Sipi€ a et al., 2002 and references therein). Baltic Sea cyanobacteria blooms consist of the non-toxic Aphanizomenon, the toxic Nodularia
* Corresponding author. Latvian Institute of Aquatic Ecology, 8 Daugavgrivas Str., LV-1048 Rıga, Latvia. E-mail address: [email protected] (I. Barda). 1 Authors of equal contribution. http://dx.doi.org/10.1016/j.envpol.2014.10.024 0269-7491/© 2014 Elsevier Ltd. All rights reserved.
spumigena (Stal et al., 2003) and Anabaena (the latter is as a potential microcystin producer; Karlsson et al., 2005). The territory of Latvia (64 589 km2) is covered by 2256 natural lakes that are mostly small ( L. stagnalis z P. corneus > R. balthica (Table 2). Generally Viviparus spp. showed higher concentrations than P. corneus, L. stagnalis and R. balthica, although concentrations of MCs tend to rard et al., 2009; be higher in pulmonates than in prosobranchs (Ge Lance et al., 2010). Zurawell et al. (1999) demonstrated a much higher accumulation in L. stagnalis collected from Canadian lakes (up to 140 mg kg1 dw), where concentration of MC-LR equivalents (MC-LReq) in tissues was correlated with toxin levels in phytoplankton. In experimental studies MC-LR concentration in L. stagnalis has been at 0.06e80.4 mg kg1 dw (Lance et al., 2006; rard et al., 2005). Here TEH and MC-LR concentrations in Ge L. stagnalis were lower than reported elsewhere. Comparable MCLReq (ELISA) concentrations in Viviparus contectus (2899e3314 mg MC kg1 dw) have been observed in Greek lakes (Gkelis et al., 2006). 3.5. Hepatotoxins in lake mussels The MC-LR and TEH concentrations accumulated in mussels (whole) varied from lake to lake. In bivalves TEH and MC-LR concentrations fluctuated over wide ranges. The highest hepatotoxin
317
concentrations were present in large filter feeding bivalves A. anatina, U. pictorum and U. tumidus. Besides filtering water above the sediments, Unio and Anodonta also take up suspended material from the upper deposit layers of the sediment. Ingestible particles are directed straight to the mouth, while unwanted particles are embedded in mucus and then expelled as pseudofaeces (Vaughn and Hakenkamp, 2001). Both U. pictorum and A. anatina exhibited similar (extreme) maximum bioaccumulation level (Table 2, Fig. 2) of up to 74,250 ± 530 and 88,440 ± 270 mg TEH kg1 dw respectively in the lakes Raiskums and Mazais Baltezers. Those concentrations clearly exceed the highest MC-LR concentrations reported earlier for same genera. Up to 3271 mg MC-LReq kg1 dw were found in Anodonta sp. (Gkelis et al., 2006) and 1310e1570 mg MC kg1 dw in Unio douglasiae (Watanabe et al., 1997). TEH concentrations in Anodonta and Unio increased in August and stayed high until autumn. For Anodonta the MC-LR and TEH concentrations were usually in line. High hepatotoxin concentrations in larger mussel species underline their ability to act in dual roles. Firstly they act as source (vector) providing dangerous hepatotoxin doses for their consumers and enhancing the risk of exposure of biota higher up in the food web, and secondly bivalves can work as biological clean-up organisms removing hepatotoxins from the water column. Comparably, the invasive bivalve D. polymorpha contained significantly less hepatotoxins than Anodonta and Unio or other mussel species exhibiting maximum TEH concentration at 390 ± 55 mg kg1 dw in lake Mazais Baltezers in September 2007. From experimental studies it is known that Dreissena can accumulate up to 11 mg MC g1 dw within a week (Dionisio Pires et al., 2004) and even 21 mg g1 ww within an hour (100 mg L1 MC-LR exposure; Contardo-Jara et al., 2008). Dreissena, Unio and Anodonta are different in their physiological adaptation to environmental contaminants, including cyanotoxins. D. polymorpha is capable of selective feeding in response to toxic and non-toxic cyanobacteria (Baker et al., 1998; Vanderploeg et al., 2001; Dionisio Pires and Van Donk, 2002) and has strong biotransformation of MCs via glutathione S-transferase and excretion of MCs as less toxic glutathione conjugates (Pflugmacher et al., 1998; Wiegand and Pflugmacher, 2005). In recent laboratory experiments with 50 mg MC-LR l1 Burmester et al. (2012) found that D. polymorpha is capable of much stronger biotransformation of toxin using glutathione S-transferase (detoxification) than U. tumidus. Furthermore, D. polymorpha may be able to protect the cells against oxidative stress by other enzyme activity, like use of superoxide dismutase. Various defense mechanisms in D. polymorpha, including immediate depuration due to high constitutive levels of multi-xenobiotic-resistance protein (Pglycoprotein), increase their survival success even when exposed to high concentrations of MCs (Contardo-Jara et al., 2008). Those factors at least partially explain the much stronger bioaccumulation
Table 2 Ranges (minimumemaximum) of TEH (mg kg1 dw) and MC-LR (mg kg1 dw) concentrations in Latvian lake invertebrates in 2002e2007. Error values are omitted for clarity. Water body/species
Anodonta anatina
Babelitis
160e2420 1000e2500a 2590 550 500a 130e1680 100e1700a 80e8120 80e1400a 88,440
Burtnieks Kisezers Lielais Baltezers Mazais Baltezers Raiskums a
Dreissena polymorpha
Lymnaea stagnalis
Planorbarius corneus Radix balthica
Unio pictorum
Unio tumidus
90 70 100 36e50 7e390
Contents lists available at ScienceDirect
Environmental Pollution journal homepage: www.elsevier.com/locate/envpol
Bioaccumulation of hepatotoxins e A considerable risk in the Latvian environment €a € c, 1, Ingrida Purina a, b, Maija Balode a, b, Olli Sjo € vall d, Ieva Barda a, b, *, 1, Harri Kankaanpa Jussi Meriluoto d Latvian Institute of Aquatic Ecology, 8 Daugavgrivas Str., LV-1048 Rıga, Latvia University of Latvia, Faculty of Biology, 4 Kronvalda Blv., LV-1586 Rıga, Latvia c Finnish Environment Institute (SYKE), Marine Research Centre, Hakuninmaantie 6, FIN-00430 Helsinki, Finland d €katu 6, FI-20520 Turku, Finland Åbo Akademi University, Department of Biosciences/Biochemistry, Tykisto a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 July 2014 Received in revised form 1 October 2014 Accepted 15 October 2014 Available online
The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form a dynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002e2007. The freshwater unionids accumulated toxins efficiently, followed by snails. In contrast, Dreissena polymorpha and most lake fishes (except roach) accumulated much less hepatotoxins. Significant nodularin-R concentrations were detected also in marine clams and flounders. No transfer of nodularin-R and microcystins between lake and brackish water systems took place. Lake mussels can transfer hepatotoxins to higher organisms, and also effectively remove toxins from the water column. Obvious health risks to aquatic organisms and humans are discussed. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Hepatotoxins Bioaccumulation Invertebrates Fish Health risks
1. Introduction Cyanobacteria can produce a variety of bioactive compounds that affect aquatic organisms. Among these hepatotoxic microcystins (MCs) are the most common in freshwater environments, and are produced by several species of cyanobacteria of the genera Microcystis, Planktothrix and Anabaena (Sivonen and Jones, 1999). MCs are cyclic heptapeptides, occurring in more than 80 structural congeners of different toxicity (Dietrich and Hoeger, 2005). New MCs are still being discovered. An analogous pentapeptide hepatotoxin nodularin-R (NOD-R) is produced by the cyanobacterium Nodularia spumigena that occurs commonly in brackish waters (Ibelings and Chorus, 2007). In the liver, NOD-R and MCs inhibit the key regulatory enzymes: serineethreonine protein phosphatases (PPs) 1, 2A, and 3 that participate, e.g., in carbohydrate and lipid metabolism, regulation of apoptosis and cell divisions rates (Sipi€ a et al., 2002 and references therein). Baltic Sea cyanobacteria blooms consist of the non-toxic Aphanizomenon, the toxic Nodularia
* Corresponding author. Latvian Institute of Aquatic Ecology, 8 Daugavgrivas Str., LV-1048 Rıga, Latvia. E-mail address: [email protected] (I. Barda). 1 Authors of equal contribution. http://dx.doi.org/10.1016/j.envpol.2014.10.024 0269-7491/© 2014 Elsevier Ltd. All rights reserved.
spumigena (Stal et al., 2003) and Anabaena (the latter is as a potential microcystin producer; Karlsson et al., 2005). The territory of Latvia (64 589 km2) is covered by 2256 natural lakes that are mostly small ( L. stagnalis z P. corneus > R. balthica (Table 2). Generally Viviparus spp. showed higher concentrations than P. corneus, L. stagnalis and R. balthica, although concentrations of MCs tend to rard et al., 2009; be higher in pulmonates than in prosobranchs (Ge Lance et al., 2010). Zurawell et al. (1999) demonstrated a much higher accumulation in L. stagnalis collected from Canadian lakes (up to 140 mg kg1 dw), where concentration of MC-LR equivalents (MC-LReq) in tissues was correlated with toxin levels in phytoplankton. In experimental studies MC-LR concentration in L. stagnalis has been at 0.06e80.4 mg kg1 dw (Lance et al., 2006; rard et al., 2005). Here TEH and MC-LR concentrations in Ge L. stagnalis were lower than reported elsewhere. Comparable MCLReq (ELISA) concentrations in Viviparus contectus (2899e3314 mg MC kg1 dw) have been observed in Greek lakes (Gkelis et al., 2006). 3.5. Hepatotoxins in lake mussels The MC-LR and TEH concentrations accumulated in mussels (whole) varied from lake to lake. In bivalves TEH and MC-LR concentrations fluctuated over wide ranges. The highest hepatotoxin
317
concentrations were present in large filter feeding bivalves A. anatina, U. pictorum and U. tumidus. Besides filtering water above the sediments, Unio and Anodonta also take up suspended material from the upper deposit layers of the sediment. Ingestible particles are directed straight to the mouth, while unwanted particles are embedded in mucus and then expelled as pseudofaeces (Vaughn and Hakenkamp, 2001). Both U. pictorum and A. anatina exhibited similar (extreme) maximum bioaccumulation level (Table 2, Fig. 2) of up to 74,250 ± 530 and 88,440 ± 270 mg TEH kg1 dw respectively in the lakes Raiskums and Mazais Baltezers. Those concentrations clearly exceed the highest MC-LR concentrations reported earlier for same genera. Up to 3271 mg MC-LReq kg1 dw were found in Anodonta sp. (Gkelis et al., 2006) and 1310e1570 mg MC kg1 dw in Unio douglasiae (Watanabe et al., 1997). TEH concentrations in Anodonta and Unio increased in August and stayed high until autumn. For Anodonta the MC-LR and TEH concentrations were usually in line. High hepatotoxin concentrations in larger mussel species underline their ability to act in dual roles. Firstly they act as source (vector) providing dangerous hepatotoxin doses for their consumers and enhancing the risk of exposure of biota higher up in the food web, and secondly bivalves can work as biological clean-up organisms removing hepatotoxins from the water column. Comparably, the invasive bivalve D. polymorpha contained significantly less hepatotoxins than Anodonta and Unio or other mussel species exhibiting maximum TEH concentration at 390 ± 55 mg kg1 dw in lake Mazais Baltezers in September 2007. From experimental studies it is known that Dreissena can accumulate up to 11 mg MC g1 dw within a week (Dionisio Pires et al., 2004) and even 21 mg g1 ww within an hour (100 mg L1 MC-LR exposure; Contardo-Jara et al., 2008). Dreissena, Unio and Anodonta are different in their physiological adaptation to environmental contaminants, including cyanotoxins. D. polymorpha is capable of selective feeding in response to toxic and non-toxic cyanobacteria (Baker et al., 1998; Vanderploeg et al., 2001; Dionisio Pires and Van Donk, 2002) and has strong biotransformation of MCs via glutathione S-transferase and excretion of MCs as less toxic glutathione conjugates (Pflugmacher et al., 1998; Wiegand and Pflugmacher, 2005). In recent laboratory experiments with 50 mg MC-LR l1 Burmester et al. (2012) found that D. polymorpha is capable of much stronger biotransformation of toxin using glutathione S-transferase (detoxification) than U. tumidus. Furthermore, D. polymorpha may be able to protect the cells against oxidative stress by other enzyme activity, like use of superoxide dismutase. Various defense mechanisms in D. polymorpha, including immediate depuration due to high constitutive levels of multi-xenobiotic-resistance protein (Pglycoprotein), increase their survival success even when exposed to high concentrations of MCs (Contardo-Jara et al., 2008). Those factors at least partially explain the much stronger bioaccumulation
Table 2 Ranges (minimumemaximum) of TEH (mg kg1 dw) and MC-LR (mg kg1 dw) concentrations in Latvian lake invertebrates in 2002e2007. Error values are omitted for clarity. Water body/species
Anodonta anatina
Babelitis
160e2420 1000e2500a 2590 550 500a 130e1680 100e1700a 80e8120 80e1400a 88,440
Burtnieks Kisezers Lielais Baltezers Mazais Baltezers Raiskums a
Dreissena polymorpha
Lymnaea stagnalis
Planorbarius corneus Radix balthica
Unio pictorum
Unio tumidus
90 70 100 36e50 7e390
