Department of Biology, FI-20014, University of Turku, Finland; Department of Forest Sciences, P.O. Box 27, University of Helsinki, FI-00014 Helsinki, Finland.
Department of Biology, FI-20014, University of Turku, Finland.
Sci Total Environ. 2022 Mar 15;812:152420. doi: 10.1016/j.scitotenv.2021.152420. Epub 2021 Dec 22.
Water browning or brownification refers to increasing water color, often related to increasing dissolved organic matter (DOM) and carbon (DOC) content in freshwaters. Browning has been recognized as a significant physicochemical phenomenon altering boreal lakes, but our understanding of its ecological consequences in different freshwater habitats and regions is limited. Here, we review the consequences of browning on different freshwater habitats, food webs and aquatic-terrestrial habitat coupling. We examine global trends of browning and DOM/DOC, and the use of remote sensing as a tool to investigate browning from local to global scales. Studies have focused on lakes and rivers while seldom addressing effects at the catchment scale. Other freshwater habitats such as small and temporary waterbodies have been overlooked, making the study of the entire network of the catchment incomplete. While past research investigated the response of primary producers, aquatic invertebrates and fishes, the effects of browning on macrophytes, invasive species, and food webs have been understudied. Research has focused on freshwater habitats without considering the fluxes between aquatic and terrestrial habitats. We highlight the importance of understanding how the changes in one habitat may cascade to another. Browning is a broader phenomenon than the heretofore concentration on the boreal region. Overall, we propose that future studies improve the ecological understanding of browning through the following research actions: 1) increasing our knowledge of ecological processes of browning in other wetland types than lakes and rivers, 2) assessing the impact of browning on aquatic food webs at multiple scales, 3) examining the effects of browning on aquatic-terrestrial habitat coupling, 4) expanding our knowledge of browning from the local to global scale, and 5) using remote sensing to examine browning and its ecological consequences.
水变色或褐变是指水体颜色的增加，通常与淡水中溶解有机物（DOM）和碳（DOC）含量的增加有关。褐变已被认为是改变北方湖泊的重要物理化学现象，但我们对其在不同淡水生境和地区的生态后果的理解是有限的。在这里，我们回顾了褐变对不同淡水生境、食物网和水-陆栖息地耦合的影响。我们研究了褐变和 DOM/DOC 的全球趋势，以及遥感作为一种从局部到全球尺度调查褐变的工具的使用。研究主要集中在湖泊和河流上，而很少涉及集水区尺度的影响。其他淡水生境，如小型和临时性水体，被忽视了，使得集水区整个网络的研究不完整。虽然过去的研究调查了初级生产者、水生无脊椎动物和鱼类的反应，但褐变对大型藻类、入侵物种和食物网的影响还没有得到充分的研究。研究主要集中在淡水生境上，而没有考虑到水-陆栖息地之间的通量。我们强调了理解一个栖息地的变化如何可能级联到另一个栖息地的重要性。褐变是一个比以前集中在北方地区更广泛的现象。总的来说，我们建议未来的研究通过以下研究行动来提高对褐变的生态理解：1）增加我们对湖泊和河流以外的其他湿地类型中褐变生态过程的了解；2）评估褐变对多个尺度上的水生食物网的影响；3）研究褐变对水-陆栖息地耦合的影响；4）扩大我们对从局部到全球尺度的褐变的了解；5）使用遥感来研究褐变及其生态后果。
