龙须菜对海水氮磷富营养化的响应

龙须菜(Gracilaria lemaneiformis)是红藻门江蓠属大型海藻,已从山东青岛引种到广东省南澳岛等地栽培多年。深入了解其光合作用与环境条件的关系,对龙须菜的合理栽培及其在环境生态中的生物学作用和扩大其开发利用价值,具有重要的理论和现实意义。该文利用人为配置的不同程度N、P污染海水处理龙须菜,研究其生理生态特性对海水氮磷富营养化的响应。结果表明: 处理6 d后,龙须菜叶绿素a及3种藻胆蛋白含量和总抗氧化能力在轻度P(P 0.2 mg·L^-1)及重度N、P复合污染(P 10 mg·L^-1,N 55 mg·L^-1)情况下降低。叶绿素荧光参数的变化也表明上述处理对叶绿体PSⅡ造成不利影响,而在轻度N(N 0.9 mg·L^-1)和轻度N、P复合污染(P 0.2 mg·L^-1,N 0.9 mg·L^-1)海水中上述参数则变化不大,表现出龙须菜对轻度N及轻度N、P复合污染的耐受性。该实验条件下,轻度污染处理后,藻体中不因环境N、P浓度升高而富集N、P。表明龙须菜可以作为轻度富营养化海水水体的净化藻类。

RESPONSE OF GRACILARIA LEMANEIFORMIS TO NITROGEN AND PHOSPHORUS EUTROPHIC SEAWATER

Aims Gracilaria lemaneiformis is a commercially important marine red alga from which agar is extracted for use in food chemistry and in production of tissue culture media. It has been transplanted from Qingdao, Shandong Province to Nan’ao Island, Guangdong Province and other places in South China. Understanding the relationship between its photosynthesis and environmental factors has theoretical and practical importance for growing the macroalga more rationally, understanding its biological functions and increasing its utilization. Methods We cultured G. lemaneiformis seaweeds in Qing’ao Bay of Nan ’ao Island, South Sea, China. The silky samples (immersed in seawater in plastic casks) were taken into a laboratory and provided oxygen by air pumps. We studied their physiological responses to six days of growth in seawater eutrophicated to different degrees by nitrogen and phosphorus alone and in combination.  Important findings Contents of phycobiliprotein and chlorophylla and total antioxidative ability were decreased significantly in mild phosphorus eutrophic sea water (P 0.2 mg·L^－1) and in severe nigrogen+phosphorus eutrophic seawate r (P 10 mg·L^－1, N 55 mg·L^－1). Chlorophyll fluorescence kinetic parameters (F_v/F_m, F_v/F_o, q_P, q_N,ΦPSⅡ, q_o) also showed the harmful effect of such treatments to PSⅡ function. However, no obvious changes in these parameters were found with mild nitrogen (N 0.9 mg·L^－1) and mild nitrogen+phosphorus (P 0.2 mg·L^－1, N 0.9 mg·L^－1) eutrophic seawater. Gracilaria lemaneiformisdid not accumulate more nitrogen or phosphorus in vivo in mild eutrophic seawater than in the control seawater. Because G. lemaneiformisis tolerant to mild N and mild N+P pollution, this species may be used to purify lightly eutrophicated seawater.