Invasive floating macrophytes reduce greenhouse gas emissions from a small tropical lake

Floating macrophytes, including water hyacinth (Eichhornia crassipes), are dominant invasive organisms in tropical aquatic systems, and they may play an important role in modifying the gas exchange between water and the atmosphere. However, these systems are underrepresented in global datasets of greenhouse gas (GHG) emissions. This study investigated the carbon (C) turnover and GHG emissions from a small (0.6 km²) water-harvesting lake in South India and analysed the effect of floating macrophytes on these emissions. We measured carbon dioxide (CO₂) and methane (CH₄) emissions with gas chambers in the field as well as water C mineralization rates and physicochemical variables in both the open water and in water within stands of water hyacinths. The CO₂ and CH₄ emissions from areas covered by water hyacinths were reduced by 57% compared with that of open water. However, the C mineralization rates were not significantly different in the water between the two areas. We conclude that the increased invasion of water hyacinths and other floating macrophytes has the potential to change GHG emissions, a process that might be relevant in regional C budgets.

 

大型水生植物，包括水風(fēng)信子(Eichhornia crassipes)，是熱帶水生系統(tǒng)中主要的入侵生物之一，它們在改變水與大氣之間的氣體交換方面可能起著重要的作用。然而，這個(gè)系統(tǒng)在溫室氣體(GHG)排放的全球數(shù)據(jù)中起到的作用被部分忽視了。本文研究了南印度一個(gè)小(0.6 km2)水收集湖的碳(C)流動和溫室氣體排放，并分析了水生植物對這些排放的影響。我們測量了二氧化碳(CO₂)和甲烷(CH₄)的排放量，以及在水葫蘆群落附近的水分與開放水域中水分的C礦化率和物理化學(xué)變量。水葫蘆群落附近的CO₂和CH₄排放量比開放水域減少了57%。然而，在這兩個(gè)區(qū)域的水中，C礦化率沒有明顯的差異。我們的結(jié)論是，水風(fēng)信子和其他漂浮的大型植物的入侵有可能改變溫室氣體排放，這一過程可能與區(qū)域的C預(yù)算有關(guān)。