升温对有沉水植物占优的水体水质影响

Effects of elevated temperature on water quality in an aquatic ecosystem dominated by submerged plants

全球变暖,特别是全球气温升高对生态系统结构、功能、过程和生态服务产生重要影响。为了解升温对以沉水植物为优势的浅水水体水质的影响,构建了以沉水植物苦草(Vallisneria natans)为主要初级生产者的中型水生态系统,设置了升温组和不升温的对照组,通过测定水中营养盐、透明度、浮游藻类及苦草生物量等指标以探究升温对沉水植物占优水体水质的影响。结果表明:升温组水中总磷(TP)、总溶解态磷(TDP)高于对照组,但两组间总氮(TN)、总溶解态氮(TDN)和透明度(SD)的差异不显著,升温组水体总悬浮物(TSS)和溶解氧(DO)显著低于对照组;升温中沉水植物苦草的生物量显著高于对照组,高了72.3%,但浮游藻类的生物量(Chl a)显著低于对照组,降低了25.6%。因此,升温显著增加了水中TP、TDP,但对TN、TDN和SD的影响不显著,降低了水体TSS和DO;升温促进了沉水植物苦草的生长,但降低浮游藻类的生物量(Chl a)。该研究结果可为深入了解气候变暖对浅水生态系统的影响提供参考。

Global warming,especially elevated temperature,has important impacts on ecosystem structure,function,process,and ecological service.To evaluate the effects of warming on water quality of shallow aquatic ecosystem dominated by submerged plants,a medium-sized aquatic ecosystem with the submerged plant Vallis-neria natans as the main primary producer was conducted in mesocosms treated by elevated temperature and am-bient temperature as controls.Water nutrient,transparency,phytoplankton and Vallisneria natans biomass were measured in the controls and in the elevated temperature group and compared to investigate the effects of warming on the water quality.The results showed that:concentrations of total phosphorus(TP)and total dissolved phos-phorus(TDP)were higher in the elevated temperature treatment than in the controls,but there was no significant difference of total nitrogen(TN),total dissolved nitrogen(TDN)and secchi depth(SD)between the two groups.The concentrations of total suspended solids(TSS)and dissolved oxygen(DO)were lower in the elevated tem-perature treatment than in the controls.However,the biomass of submerged plants was higher(increased by 72.3%),while the phytoplankton Chl a was lower(decreased by 25.6%)in the elevated temperature treatment than in the controls.So,elevated temperature increased the total phosphorus(TP)and total dissolved phosphorus(TDP)concentrations,but it did not increase the total nitrogen(TN),total dissolved nitrogen(TDN)and secchi depth(SD).Elevated temperature reduced the total suspended solids(TSS)and dissolved oxygen(DO),but it enhanced the growth of submerged plant Vallisneria natans,while it decreased the biomass of phytoplankton(Chl a).The results of this study may provide an insight into the effects of climate warming on aquatic ecosystems.