Water quality limits for Atlantic salmon (<i>Salmo salar</i> L.) exposed to short term reductions in pH and increased aluminum simulating episodes

Abstract

Abstract. Acidification has caused the loss or reduction of numerous Atlantic salmon (Salmo salar L.) populations on both sides of the North Atlantic. Acid deposition peaked in the 1980's and resulted in both chronically and episodically acidified rivers. At present, water quality is improving in all affected rivers due to reduced acid deposition. However, spring snow melt, heavy rainfall and sea salt episodes can still cause short term drops in pH and elevated concentrations of bioavailable aluminum. Technical malfunction in lime dozers will cause short termed episodic spates in the limed rivers. The current situation has prompted a need for dose-response relationships based on short term exposures of Atlantic salmon to assess the potential population effects of episodic acidification. Water quality guidelines for salmon have been lacking, despite a large number of experiments, all demonstrating dose-response relationships between water chemistry and fish health. We have summarized results from 347 short-term (<14 days) exposures of salmon parr and smolt performed between 1990 and 2003 in Norway. The experiments have been performed as bioassays, where fish have been exposed in tanks fed river water, in tanks where the river water quality has been manipulated (added H + and Al) and as Carlin-tagged smolt releases after preexposure to moderately acidic waters. The results from the various bioassays are compared to water quality limits proposed on basis of the relationship between water quality and population status/health in Norwegian rivers. The focus of this article is placed on chemical-biological interactions that can be drawn across experiments and exposure protocols. We propose dose-response relationships for acid neutralizing caCorrespondence to: F. Kroglund (kro@niva.no) pacity (ANC), pH, cationic Al and gill accumulated Al, versus mortality in freshwater, effects on hypo-osmoregulatory capacity in seawater challenge tests and on smolt to adult survival in release experiments. The "no effect" dose depends on the life history stage tested and on the sensitivity of the biomarkers. Parr are more tolerant than smolt. Concentrations of Al that have no significant impact on freshwater life history stages can still have major population effects if they occur prior to smolt migration. While smolt can survive in freshwater for a prolonged period of time (>10 days) at an Al dose resulting in a gill Al concentration of up to 300 µg Alg −1 dw, a 3 day exposure resulting in a gill Al accumulation in the range of 25 to 60 µg Alg −1 dw reduces smolt to adult survival in a dose related manner by 20 to 50%. For smolt to adult survival, the biological significant response is delayed relative to the dose and occurs first after the fish enters the marine environment. In addition to exposure intensity and timing, exposure duration is important for the setting of critical limits.

Sublethal effects in Atlantic salmon (Salmo salar) exposed to mixtures of copper, aluminium and gamma radiation

“…Exposure to Al alone led to accumulation of Al on gills, which was followed by an increase in glucose and a loss of plasma ions as seen elsewhere e.g. (Rosseland and Staurnes, 1994;Kroglund et al, 2008). Interestingly, the increase in glucose and loss of plasma ions were less pronounced in the Al exposure compared to the Cu exposure.…”

“…High concentrations of Al in surface waters are a long recognised problem in Scandinavian waters due to acid rain, and is mainly due to low pH and or high concentrations of dissolved organic carbon (DOC). In low pH waters Al is mainly present as low molecular mass (LMM) cationic species, being highly reactive towards fish gills (Gensemer and Playle, 1999;Kroglund et al, 2008). By increasing pH of acid Al-rich waters, transient high molecular mass (HMM) reactive Al species are formed in the unstable mixing zone, due to hydrolysis and polymerisation of low molecular mass (LMM) cationic Al species (Teien et al, 2004).…”

Aluminum exposure impacts brain plasticity and behavior in Atlantic salmon (Salmo salar)

“…Al toxicity in acidified water has been identified as a major contributor to this decrease (Kroglund et al, 2007;McCormick et al, 2009). An increase in Al concentration in water has been linked to an increase in Al accumulation in the gills (Kroglund et al, 2008). Al is known to affect the function of the gills in both parr and smolts, but there appears to be increased sensitivity to this chemical stress in smolts .…”

“…In water, Al can be present in different physicochemical forms, but it is well established that Al cations are the bioavailable and toxic forms of Al, and that Al associated with organic material such as humic substances are less toxic (Gensemer and Playle, 1999;Teien et al, 2006). Many aquatic organisms are sensitive to such changes in water quality, and the detrimental effects of Al in acidified water have been studied in plants (Lovett et al, 2009), invertebrates (Guerold et al, 2000), amphibians (Brady and Griffiths, 1995) and fish (Kroglund et al, 2008;Poléo et al, 1997). Thus Al toxicity has significant, negative implications for the biodiversity and functioning of many ecosystems (Horne and Dunson, 1995;Lovett et al, 2009).…”

Anthropocene environmental change in an internationally important oligotrophic catchment on the Atlantic seaboard of western Europe

“…For example, reduction in water clarity can restrict autotrophic production while DOC can fuel microbial metabolism (Jasser and Arvola, 2003;Sucker and Krause, 2010). Anthropogenically-exacerbated acidification at these sites can greatly increase aquatic effects, including changes in the quality of primary producers, extirpation of macroinvertebrates and decreased fish spawning efforts and survival rates (Kowalik et al, 2007;Kroglund et al, 2007). Drainage works associated with afforestation (Carling et al, 2001) have precipitated changes in hydrological regimes and increased erosion risk (Mü ller, 2000).…”