Is episodic river acidification affecting wild Atlantic salmon populations in the Maritimes?

河流的间歇性酸化是否会影响滨海省的野生大西洋鲑鱼种群？

• 批准号: 558327-2020
• 负责人: Cremazy, AnneAM
• 金额: $ 1.46万
• 依托单位: Institut national de la recherche scientifique
• 依托单位国家: 加拿大
• 项目类别: Alliance Grants
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751330
• 关键词: episodic; river; acidification; affecting; wild

The Atlantic salmon is an iconic species for the people of Eastern Canada, with important economic, cultural, human subsistence and ecological values. In recent decades, the number of Atlantic Salmon returning to Canadian rivers has declined to unprecedented lows (20% of their historic levels). Despite great restoration and conservation efforts, we have failed to prevent the declines as high fish mortality at sea remains a puzzling issue. Recent studies have raised the possibility that episodic river acidification during spring snowmelt may be an important and overlooked part of the problem. This natural process, which has been exacerbated by acid precipitation from human activities (e.g. coal burning), is known to affect salmonids by increasing aluminum bioavailability in rivers. Under acidic conditions (pH <6), this naturally abundant metal is solubilized into inorganic forms (Ali) that can damage salmonids gills, even in short-term, low-level exposures. A particularly concerning effect is the impairment of smoltification, a critical physiological process for seawater adaptation, occurring during the spring outmigration (smolt) phase. Recent European and American studies have provided evidence that episodic exposure of smolts to acidity/Ali in freshwater can reduce early ocean survival by 20 to 50%, in a dose-dependent matter. This issue has not yet been investigated in Atlantic Canada, despite its potential occurrence. For example, the Miramichi river (NB), which has the largest salmon runs in the world, has a pH that often drops below 6 in the spring. Our project aims at answering the following question: Does episodic river acidification significantly contribute to the low return rates of salmons in Eastern Canada? For four years, we will collect water samples and migrating smolts from various NB and NS rivers. We will notably measure pH and Ali concentrations in water samples, Al bioaccumulation and smoltification biomarkers in fish gills, as well as smolt salinity tolerance.The project is designed to inform management decisions on actionable freshwater factors affecting Atlantic salmon populations, by implementing effective mitigation strategies if applicable (e.g. liming).

大西洋鲑鱼是加拿大东部人民的标志性物种，具有重要的经济、文化、人类生存和生态价值。近几十年来，返回加拿大河流的大西洋鲑鱼数量降至前所未有的低水平(历史水平的20%)。尽管做出了巨大的恢复和保护努力，但我们未能阻止鱼类数量的下降，因为海洋中鱼类的高死亡率仍然是一个令人费解的问题。最近的研究提出了这样一种可能性，即春季融雪期间的间歇性河流酸化可能是这个问题的一个重要而被忽视的部分。这一自然过程因人类活动(如燃煤)的酸沉淀而加剧，已知通过增加河流中铝的生物有效性来影响鲑鱼。在酸性条件下(pH和lt；6)，这种天然丰富的金属被溶解成无机形式(ALI)，即使在短期、低水平的暴露下，也会损害鲑鱼的鳃。一个特别令人担忧的影响是，在春季迁出(SMOLT)阶段，海水适应的一个关键生理过程--嗅化作用受到了损害。最近欧洲和美国的研究提供了证据，表明在一种剂量依赖的物质中，间歇性暴露于淡水中的酸度/ALI可以使早期海洋存活率降低20%至50%。尽管这一问题可能会发生，但在大西洋加拿大尚未对其进行调查。例如，拥有世界上最大鲑鱼流量的米拉米奇河(NB)的PH值在春季经常降至6以下。我们的项目旨在回答以下问题：断断续续的河流酸化是否对加拿大东部鲑鱼的低返回率有重大影响？在四年的时间里，我们将从北冰洋和南北河的不同河流采集水样和迁徙的沼泽。我们将特别测量水样中的pH值和ALI浓度、鱼鳃中的铝生物累积和熏蒸生物标记物，以及对盐分的耐受性。该项目旨在通过实施有效的缓解策略(如石灰)，为管理层就影响大西洋鲑鱼种群的可操作淡水因素做出决策提供信息。