Impacts of short-term acid and aluminum exposure on Atlantic salmon (Salmo salar) physiology: A direct comparison of parr and smolts

Abstract

Episodic acidification resulting in increased acidity and inorganic aluminum (Al i ) is known to impact anadromous salmonids and has been identified as a possible cause of Atlantic salmon population decline. Sensitive life-stages such as smolts may be particularly vulnerable to impacts of short-term (days-week) acid/Al exposure, however the extent and mechanism(s) of this remain unknown. To determine if Atlantic salmon smolts are more sensitive than parr to short-term acid/Al, parr and smolts held in the same experimental tanks were exposed to control (pH 6.3-6.6, 11-37 g l −1 Al i ) and acid/Al (pH 5.0-5.4, 43-68 g l −1 Al i ) conditions in the lab, and impacts on ion regulation, stress response and gill Al accumulation were examined after 2 and 6 days. Parr and smolts were also held in cages for 2 and 6 days in a reference (Rock River, RR) and an acid/Al-impacted tributary (Ball Mountain Brook, BMB) of the West River in Southern Vermont. In the lab, losses in plasma Cl − levels occurred in both control parr and smolts as compared to fish sampled prior to the start of the study, however smolts exposed to acid/Al experienced additional losses in plasma Cl − levels (9-14 mM) after 2 and 6 days, and increases in plasma cortisol (4.3-fold) and glucose (2.9-fold) levels after 6 days, whereas these parameters were not significantly affected by acid/Al in parr. Gill Na + ,K + -ATPase (NKA) activity was not affected by acid/Al in either life-stage. Both parr and smolts held at BMB (but not RR) exhibited declines in plasma Cl − , and increases in plasma cortisol and glucose levels; these differences were significantly greater in smolts after 2 days but similar in parr and smolts after 6 days. Gill NKA activity was reduced 45-54% in both life-stages held at BMB for 6 days compared to reference fish at RR. In both studies, exposure to acid/Al resulted in gill Al accumulation in parr and smolts, with parr exhibiting two-fold greater gill Al than smolts after 6 days. Our results indicate that smolts are more sensitive than parr to short-term acid/Al. Increased sensitivity of smolts appears to be independent of a reduction in gill NKA activity and greater gill Al accumulation. Instead, increased sensitivity of smolts is likely a result of both the acquisition of seawater tolerance while still in freshwater and heightened stress responsiveness in preparation for seawater entry and residence.

Aluminum exposure alters behavioral parameters and increases acetylcholinesterase activity in zebrafish (Danio rerio) brain

“…The control groups were maintained in the 5-L test aquarium water at pH 6.8 or acidified with HCl to reach pH 5.8. The treated fish were maintained in the 5-L test aquarium containing 50 μg/L AlCl 3 at pH 5.8 or pH 6.8 for 24 h (acute treatment) or 96 h (subchronic treatment) because there is evidence that soft water acidification associated with aluminum induces changes in swimming activity, higher sensitivity to stress, and the decline in the Atlantic salmon population (Brodeur et al 2001;Monette and McCormick 2008). For this reason, we evaluated the effect of aluminum on circumneutral pH=6.8 and acid pH=5.8.…”

“…Aluminum is innocuous under alkaline or circumneutral conditions whereas in acidic environments, it presents severe risks to the aquatic biota, including fish (Waring et al 1996). Studies have postulated that chronic water acidification associated with aluminum is involved in the decline in the Atlantic salmon population (Monette and McCormick 2008). Furthermore, aluminum is known to have toxic effects on a variety of organ systems including the brain (Oteiza et al 1993).…”

Fish kill caused by aluminium and iron contamination in a natural pond used for fish rearing: a case report

“…The negative effect of aluminium on fish has been described (Lydersen et al 1990;Gensemer and Playle 1999;McCartney et al 2003;Monette and McCormick 2008). Aluminium toxicity depends on water pH, and on the concentration of calcium and organic substances (Freda 1991;Wauer and Teien 2010).…”

Locomotor activity and learning and memory abilities in Alzheimer’s disease induced by Aluminum in an acid environment in Zebrafish

“…铝是一种地壳中含量较多的人体非必需金属 元素, 适量摄入对人体无害, 积聚在人体内有助于 金属离子平衡; 具有生物活性的铝不能进入大脑, 极少量的铝有助于大脑组织的选择性吸收, 但是离 子 形 式 铝 的 大 量 积 累 将 导 致 新 陈 代 谢 的 紊 乱 (Tomljenovic, 2011;Senger et al, 2011)。铝对于生 活在酸性和碱性环境中的水生生物有很大危害。 研究表明，土壤酸化导致水中铝离子积累进而致使 大西洋鲑鱼数量减少、生殖功能急剧衰退, 且对于 组 织 和 大 脑 均 存 在 毒 性 效 应 (Monette & McCormick, 2008;Oteiza et al, 1993)。 流行病学研究 也揭示污水中所存在的过量的铝与神经变性有极 大 关 联 (Rondeau et al, 2009;Shcherbatykh & Carpemter, 2007)。铝在鱼类中产生毒性大多数与水 的 pH 值相关, 可溶性铝能够降低水的 pH 值和升高 无机铝的含量, 无机铝对鱼类有很强毒性作用, 而 水的酸性对鱼类血液循环、内分泌、代谢和生殖功 能都有影响 (Camargo et al, 2009； Nilsen et al, 2010)。 但是, 到目前为止，铝导致神经毒性的作用机理还 不清楚。 金属元素(主要为铝)能够潜伏在人体或动物体 内, 积累到一定量诱发神经毒性, 表现为：(1)淀粉 样 蛋 白 增 加 (Walton & Wang, 2009;Chen & Penington, 2000); (2)神经纤维出现异常, 轴突运输 出现停滞 (Walton, 2006;Perl & Moalem, 2006); (3) 神经传递过程中胆碱等神经递质和 G-蛋白信号级 联损伤 (Cowburn et al, 2001 …”