何 妍,石琬綺,彭鑫鑫,楊 巍,李鍺鐔,文 昕,羅竣瀟,劉華祖,李 偉,2*

藻類對(duì)大型溞抵抗農(nóng)藥的毒理學(xué)影響及其機(jī)制

何 妍1,石琬綺1,彭鑫鑫1,楊 巍1,李鍺鐔1,文 昕1,羅竣瀟1,劉華祖1,李 偉1,2*

(1.重慶大學(xué)環(huán)境與生態(tài)學(xué)院,重慶 400045；2.三峽庫(kù)區(qū)生態(tài)環(huán)境教育部重點(diǎn)實(shí)驗(yàn)室,重慶 400045)

為探究藻類對(duì)大型溞農(nóng)藥抗性的影響及其機(jī)制,分別將5種淡水廣布的甲藻、硅藻、綠藻、隱藻、藍(lán)藻等量培育大型溞后,再將大型溞分別暴露于2種殺蟲(chóng)劑吡蟲(chóng)啉(水溶性)和氰戊菊酯(脂溶性)中,測(cè)定大型溞的半數(shù)致死劑量、化學(xué)計(jì)量比(P/C,N/C)和脂肪酸含量.研究表明:與生源性化學(xué)元素氮磷相比,N3不飽和脂肪酸能更好揭示大型溞對(duì)藻類的捕食關(guān)系;藻類的N3不飽和脂肪酸含量是影響大型溞對(duì)水溶性農(nóng)藥抗性的關(guān)鍵因子;大型溞對(duì)脂溶性農(nóng)藥的抗性差異比暴露在水溶性農(nóng)藥中更明顯.因此,藻類的N3不飽和脂肪酸是預(yù)測(cè)大型溞對(duì)水溶性農(nóng)藥抗性強(qiáng)度的最佳因子,其有助于更準(zhǔn)確地預(yù)測(cè)以不同藻類為食的大型溞食物鏈對(duì)自然環(huán)境中污染物的抗性和風(fēng)險(xiǎn).

藻類；大型溞；氰戊菊酯；吡蟲(chóng)啉；生態(tài)毒理學(xué)；營(yíng)養(yǎng)級(jí)聯(lián)

新煙堿類殺蟲(chóng)劑和菊酯類殺蟲(chóng)劑頻繁在生態(tài)系統(tǒng)中被檢測(cè)出,造成了生物多樣性的下降[1-6].甚至有研究發(fā)現(xiàn)水生生態(tài)系統(tǒng)受到新煙堿殺蟲(chóng)劑的高毒性和持久性的威脅,不僅改變其食物網(wǎng)的結(jié)構(gòu),還影響到更高層次的消費(fèi)者,在“營(yíng)養(yǎng)級(jí)聯(lián)效應(yīng)”作用下,對(duì)生態(tài)環(huán)境造成不可逆轉(zhuǎn)的負(fù)面影響[7-8].菊酯類殺蟲(chóng)劑由于親脂性和和持久性易殘留富集在生物體中,對(duì)生物的生殖系統(tǒng)和神經(jīng)系統(tǒng)均有負(fù)面影響,對(duì)水生環(huán)境造成潛在的高度生態(tài)風(fēng)險(xiǎn)[9-10].目前大量研究主要側(cè)重于從光照、溫度、食物數(shù)量等環(huán)境脅迫因子角度關(guān)注大型溞對(duì)農(nóng)藥抗性的變化,而缺乏對(duì)食物質(zhì)量的毒理學(xué)影響研究.例如Delnat等[11]研究發(fā)現(xiàn)日溫變化會(huì)放大有機(jī)磷和殺菌劑組成的農(nóng)藥混合物的毒性;Naeem等[12]研究了食物數(shù)量能影響氰戊菊酯殺蟲(chóng)劑對(duì)大型溞的毒性.然而,食物質(zhì)量對(duì)于生物種群來(lái)說(shuō)卻是一個(gè)關(guān)鍵的環(huán)境限制因素[13-14],特別是從化學(xué)計(jì)量比和不飽和脂肪酸角度分析食物對(duì)大型溞抗性影響的研究還鮮見(jiàn)報(bào)道.

化學(xué)計(jì)量比是生態(tài)計(jì)量學(xué)的核心,目前主要集中在碳(C)、氮(N)、磷(P)這3種生命化學(xué)基礎(chǔ)元素[15].食物網(wǎng)內(nèi)生物體的化學(xué)計(jì)量比能夠反映元素流動(dòng)循環(huán)狀況;當(dāng)生物體受外界環(huán)境干擾導(dǎo)致體內(nèi)化學(xué)計(jì)量比不平衡、不匹配也會(huì)影響其生長(zhǎng)速率、競(jìng)爭(zhēng)和繁殖,最終影響食物網(wǎng)的物質(zhì)循環(huán)和能量流動(dòng)[16].目前,人類頻繁活動(dòng)帶來(lái)的氮磷等營(yíng)養(yǎng)鹽進(jìn)入水生生態(tài)系統(tǒng),將改變其化學(xué)元素的組成占比,從而影響水生食物網(wǎng)生產(chǎn)者和消費(fèi)者的化學(xué)計(jì)量關(guān)系[17-19],水生生態(tài)系統(tǒng)生物的生態(tài)化學(xué)計(jì)量學(xué)對(duì)污染物的響應(yīng)也需引起重視.

脂肪酸作為生物膜的基本組成部分,是最常見(jiàn)儲(chǔ)存和循環(huán)能量的形式,也參與調(diào)節(jié)多種生物活動(dòng)[20-21].其中N3不飽和脂肪酸主要包括十八碳三烯酸 (ALA)、二十碳五烯酸 (EPA)和二十二碳六烯酸 (DHA),ALA是構(gòu)成腦細(xì)胞膜、神經(jīng)遞質(zhì)、突觸,神經(jīng)遞質(zhì)受體結(jié)構(gòu)的主要成分,通過(guò)脫氫和延長(zhǎng)碳鏈合成EPA和DHA,兩者有利于維持神經(jīng)細(xì)胞膜的完整性和流動(dòng)性,還具有促進(jìn)腦細(xì)胞生長(zhǎng),增強(qiáng)大腦機(jī)能等作用[22],N3不飽和脂肪酸是構(gòu)成細(xì)胞膜結(jié)構(gòu)的磷脂主要成分,在生物體內(nèi)具有穩(wěn)定細(xì)胞膜,增強(qiáng)免疫力等重要生理功能.由于N3不飽和脂肪酸易被氧氣氧化,且氧氣在水中擴(kuò)散速度比在空氣中慢,使得水生生態(tài)系統(tǒng)的初級(jí)生產(chǎn)者群落含有豐富的N3不飽和脂肪酸,而在多數(shù)陸生植物中很難檢測(cè)到.因此水陸生態(tài)系統(tǒng)食物鏈的第一營(yíng)養(yǎng)級(jí)可用性存在差異,進(jìn)一步導(dǎo)致消費(fèi)者的營(yíng)養(yǎng)攝取不平衡從而影響其生長(zhǎng)與繁殖[23-25],N3不飽和脂肪酸在自然界中主要存在于海洋原生物和藻類,通過(guò)食物鏈傳遞給更高營(yíng)養(yǎng)級(jí)的魚(yú)類等[26-29],目前研究多偏向通過(guò)現(xiàn)代生物技術(shù)將其應(yīng)用于保健品、食品和藥品等領(lǐng)域從而改善人體的健康[22].

本研究選取5種自然水體常見(jiàn)的淡水藻類(甲藻、硅藻、綠藻、隱藻、藍(lán)藻)喂養(yǎng)大型溞,分別暴露在目前廣泛使用的殺蟲(chóng)劑吡蟲(chóng)啉(水溶性)和氰戊菊酯(脂溶性)中,以探究食物質(zhì)量對(duì)大型溞的抗性影響; 從化學(xué)計(jì)量比和不飽和脂肪酸角度分析藻類種群引起的大型溞對(duì)農(nóng)藥抗性產(chǎn)生差異的影響機(jī)制.研究將有助于了解高營(yíng)養(yǎng)級(jí)水生生物對(duì)農(nóng)藥抗性的作用規(guī)律,也對(duì)闡明對(duì)水生生態(tài)系統(tǒng)食物網(wǎng)的影響機(jī)制具有重要意義.

1 材料與方法

1.1 藻種和大型溞的培養(yǎng)

綠藻門(mén)蛋白核小球藻(),硅藻門(mén)小環(huán)藻(sp.),隱藻門(mén)隱藻(sp.),甲藻門(mén)楯形多甲藻 (),藍(lán)藻門(mén)鈍頂螺旋藻()均購(gòu)于中國(guó)科學(xué)院淡水藻種庫(kù),蛋白核小球藻采用BG11培養(yǎng)基,小環(huán)藻采用CSI培養(yǎng)基,隱藻采用AF6培養(yǎng)基,楯形多甲藻不等變種采用119培養(yǎng)基,鈍頂螺旋藻采用Spirulina 培養(yǎng)基,在光照75μmol/ (m2·s)、光暗比14h:10h,溫度25℃的條件下無(wú)菌培養(yǎng)至對(duì)數(shù)生長(zhǎng)期,通過(guò)沉淀和離心濃縮去除培養(yǎng)基,取下層藻液作為大型溞的食物備用.

本研究采用的大型溞()是一種浮游動(dòng)物枝角類生物,且被廣泛用作指示生物評(píng)價(jià)水體環(huán)境中各種有害化學(xué)物質(zhì)的生物毒性[30].實(shí)驗(yàn)前期用孤雌生殖法獲取大型溞單克隆純品系[31],將其產(chǎn)下的三代及以上的子代作為實(shí)驗(yàn)對(duì)象分別喂食5種藻,在自然光照條件下飼養(yǎng)1個(gè)月以上,飼養(yǎng)溫度(20±1)℃,光暗周期16h:8h,自來(lái)水曝氧48h以上作為培養(yǎng)介質(zhì).

1.2 毒性試驗(yàn)

選用的農(nóng)藥為水溶性的吡蟲(chóng)啉(純度為95%,CAS:138261-41-3)和脂溶性的順式氰戊菊酯(純度為95%,CAS:66230-04-4),購(gòu)于上海源葉技術(shù)有限公司.建立交叉因子設(shè)計(jì)進(jìn)行亞慢性毒性試驗(yàn),通過(guò)預(yù)實(shí)驗(yàn)分別確定農(nóng)藥濃度梯度,共設(shè)置7個(gè)濃度,5個(gè)實(shí)驗(yàn)組,每個(gè)濃度設(shè)5個(gè)平行組,即吡蟲(chóng)啉(0,0.5,1,2,10,25,50mg/L)×5種藻(甲藻、硅藻、綠藻、隱藻、藍(lán)藻),氰戊菊酯(0,0.0001,0.001,0.01,0.1,0.2, 1μg/L)×5種藻(甲藻、硅藻、綠藻、隱藻、藍(lán)藻).實(shí)驗(yàn)期間采用COMBO培養(yǎng)基[32]配制試驗(yàn)溶液,為使脂溶性的氰戊菊酯混合均勻,加入0.02%的二甲基亞砜(DMSO),比最低的可觀察有效濃度(2%)低2個(gè)數(shù)量級(jí)[33],并且低于OECD建議的溶劑限度.每個(gè)平行組用100mL的燒杯裝80mL試液,放15只4～5d的大型溞,每隔1d喂食1mgC/L的藻液,燒杯表面采用保鮮膜包裹防止農(nóng)藥揮發(fā),每24h記錄大型溞存活情況并將幼溞取出,每隔7d更換暴露溶液,暴露時(shí)長(zhǎng)為14d.

1.3 測(cè)定項(xiàng)目及方法

化學(xué)因子的測(cè)定:各取50mL培養(yǎng)藻液和以此為食物的大型溞100只冷凍干燥作為樣品,稱重,使用固體燃燒法在總有機(jī)碳分析儀(TOC-SSM5000,日本島津)中測(cè)定5種藻類和大型溞的總有機(jī)碳含量.用于測(cè)總氮、總磷含量的樣品用濃硫酸和30%過(guò)氧化氫在消煮爐中高溫消解,待溶液冷卻并定容,總磷含量用鉬銻抗分光光度法測(cè)定,總氮含量用總有機(jī)碳分析儀測(cè)定(TOC-L,日本島津);再根據(jù)測(cè)定的各樣品碳、氮、磷含量計(jì)算出3個(gè)元素的化學(xué)計(jì)量比值,即碳氮比、碳磷比和氮磷比[34-35].

脂肪酸的測(cè)定:采用一步法分析測(cè)定藻和大型溞的脂肪酸含量[36-37],將樣品冷凍干燥24h以上,依次加入4mL正己烷,1mL內(nèi)標(biāo)液(1mg二十三烷酸溶于100mL正己烷中)和2mL14%三氟化硼.在100℃下水浴加熱120min使其衍生化,再依次加入1mL正己烷和2mL超純水.離心后取上層液相氮吹至干,濃縮于200μL正己烷,采用氣相色譜/三重四級(jí)桿質(zhì)譜聯(lián)用儀(GCMS-TQ8040,日本島津)定性定量分析樣品的脂肪酸,配備SH-Rxi-5SilMS色譜柱, (30m′0.25mm,0.25mm,日本島津);通過(guò)比較樣品中脂肪酸的峰面積與內(nèi)標(biāo)的峰面積,估算脂肪酸濃度如下:

式中:S是樣品中某一脂肪酸的色譜峰面積;IS是內(nèi)標(biāo)(二十三烷酸)的色譜峰面積;IS是內(nèi)標(biāo)的濃度(mg);S是樣品的重量(g).

在所測(cè)定的37種脂肪酸當(dāng)中,二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)、十八碳三烯酸(ALA)在初級(jí)生產(chǎn)者和消費(fèi)者的碳轉(zhuǎn)移中有至關(guān)重要的作用,因此,在本研究中,脂肪酸的分析集中在這些不飽和脂肪酸種類含量上[38].

1.4 數(shù)據(jù)處理與分析

采用Logistic模型分別計(jì)算大型溞暴露在氰戊菊酯和吡蟲(chóng)啉的LC50值.以大型溞LC50為因變量,以碳氮比、碳磷比、N3不飽和脂肪酸含量為自變量,采用線性混合效應(yīng)模型(LMM)來(lái)評(píng)估與大型溞LC50相關(guān)的因素.采用R4.0.3軟件ANOVA程序進(jìn)行數(shù)據(jù)顯著性差異分析,以=0.05作為統(tǒng)計(jì)學(xué)檢驗(yàn)的顯著性水準(zhǔn).所有統(tǒng)計(jì)分析均在R4.0.3版本中進(jìn)行.

2 結(jié)果與討論

2.1 5種藻類與大型溞的化學(xué)計(jì)量比、N3不飽和脂肪酸含量關(guān)系

如圖1所示,不同藻類和與之飼養(yǎng)的大型溞P:C(<0.05,2=0.7227),N:C(<0.05,2=0.8141)和N3不飽和脂肪酸含量(<0.05,2=0.9267)在雙對(duì)數(shù)尺度上均呈顯著的正相關(guān)關(guān)系,這說(shuō)明大型溞取食的藻類決定了大型溞的P:C、N:C和N3不飽和脂肪酸含量.且藻類與大型溞的N3不飽和脂肪酸含量比P:C和N:C擬合度高,這說(shuō)明藻類里的碳氮磷元素和N3不飽和脂肪酸通過(guò)食物鏈有效地傳遞給了大型溞,而其中N3不飽和脂肪酸比碳氮磷元素在能量流動(dòng)和物質(zhì)循環(huán)過(guò)程中傳遞效率更穩(wěn)定.C、N、P是藻類和大型溞中重要的有機(jī)化合物組成元素,其中碳是構(gòu)成生物原生質(zhì)的基本元素,氮作為蛋白質(zhì)、核酸和ATP的主要成份,磷作為核酸、ATP和生物膜主要組成元素,N3不飽和脂肪酸作為構(gòu)成脂肪和磷脂的主要成分,其組成及分配是相互聯(lián)系、不可分割的一個(gè)整體,它們的相互作用及與外界環(huán)境的關(guān)系共同決定著生物營(yíng)養(yǎng)的水平和生長(zhǎng)發(fā)育的過(guò)程,同時(shí)還決定了能量流動(dòng)和物質(zhì)循環(huán)的主要過(guò)程[39].例如植物的光合能力與葉片的氮含量密切相關(guān),而氮素又依賴于光合作用提供能量給植物根系吸收運(yùn)輸?shù)豙40];凋落物的分解速率與其C:N比率呈負(fù)相關(guān)關(guān)系;土壤的C:N比率與有機(jī)質(zhì)的分解、土壤呼吸等密切相關(guān)[41].藻類與大型溞之間的能量傳遞效率與C:P比呈負(fù)相關(guān)關(guān)系,即碳氮磷含量的分配會(huì)影響物質(zhì)和能量在食物鏈中的傳遞效率[15].相比之下N3不飽和脂肪酸則以更穩(wěn)定的形式通過(guò)食物鏈從第一營(yíng)養(yǎng)級(jí)向第二營(yíng)養(yǎng)級(jí)傳遞,其中,N3不飽和脂肪酸含量由低到高依次是藍(lán)藻、隱藻、綠藻、硅藻、甲藻,藻類的N3不飽和脂肪酸含量直接影響大型溞的N3不飽和脂肪酸含量.Müller等[42]研究發(fā)現(xiàn)藍(lán)藻的EPA含量遠(yuǎn)低于隱藻,Li等[36]研究也發(fā)現(xiàn)藍(lán)藻的N3不飽和脂肪酸含量低于綠藻和硅藻,與本研究結(jié)果一致.

2.2 5種藻類飼育下大型溞對(duì)農(nóng)藥的抗性差異

將不同藻類飼育下的大型溞分別暴露在脂溶性農(nóng)藥(氰戊菊酯)和水溶性農(nóng)藥(吡蟲(chóng)啉)14d的死亡率做比較(圖2),研究結(jié)果表明暴露在脂溶性農(nóng)藥中(圖2a),抗性強(qiáng)度由強(qiáng)到弱依次為綠藻(LC50= 0.016μg/L)>硅藻(LC50=1.03×10-3μg/L)>隱藻(LC50= 3.02×10-5μg/L)>藍(lán)藻(LC50=2.70×10-5μg/L)>甲藻(LC50=1.79×10-5μg/L);暴露在水溶性農(nóng)藥中,以硅藻為食的大型溞抗性最強(qiáng),14d時(shí)LC50值為0.95mg/L, 以藍(lán)藻為食的大型溞抗性最弱,14d時(shí)LC50值為1.27×10-3mg/L,其抗性強(qiáng)度由強(qiáng)到弱依次為硅藻(LC50=0.95mg/L)>綠藻(LC50=0.74mg/L)>甲藻(LC50=0.26mg/L)>隱藻(LC50=7.16×10-3mg/L)>藍(lán)藻(LC50=1.27×10-3mg/L),以綠藻和硅藻為食的大型溞對(duì)農(nóng)藥的抗性顯然比以甲藻、隱藻、藍(lán)藻為食的大型溞強(qiáng),在農(nóng)藥低濃度梯度,甲藻、隱藻、藍(lán)藻飼育下的大型溞14d后的死亡率就已超過(guò)了80%.大型溞暴露在不同性質(zhì)的農(nóng)藥中的抗性強(qiáng)度不同,對(duì)脂溶性農(nóng)藥的抗性差異比暴露在水溶性農(nóng)藥中更明顯,即農(nóng)藥性質(zhì)不同,以不同藻類為食的大型溞所表現(xiàn)的抗性強(qiáng)度也不同.

2.3 5種藻類飼育下大型溞對(duì)農(nóng)藥的抗性與其化學(xué)計(jì)量比、N3不飽和脂肪酸含量關(guān)系

如圖3所示,不同藻類飼育下分別暴露在脂溶性和水溶性農(nóng)藥的大型溞14d時(shí)LC50值與其對(duì)應(yīng)的大型溞P:C,N:C相關(guān)性不顯著(>0.05),即大型溞對(duì)農(nóng)藥的抗性與其P:C和N:C不具有顯著相關(guān)性;與化學(xué)計(jì)量比這些測(cè)量因子相比,大型溞雖然對(duì)脂溶性農(nóng)藥的抗性強(qiáng)度與其N3不飽和脂肪酸含量無(wú)顯著相關(guān)性(>0.05),但是對(duì)水溶性農(nóng)藥的抗性強(qiáng)度與其N3不飽和脂肪酸成顯著正相關(guān)關(guān)系(=2.536- 1.2289,<0.05),這說(shuō)明N3不飽和脂肪酸含量是預(yù)測(cè)大型溞對(duì)水溶性農(nóng)藥抗性強(qiáng)度的最佳測(cè)量因子.

以不同藻類為食的大型溞對(duì)水溶性農(nóng)藥的抗性具有差異,而N3不飽和脂肪酸是影響關(guān)鍵因子.隨著藻類的N3不飽和脂肪酸含量上升,通過(guò)食物鏈傳遞給大型溞的N3不飽和脂肪酸含量隨之增加,N3不飽和脂肪酸不僅可以促進(jìn)生物的生長(zhǎng)發(fā)育與繁殖[42-44],還影響調(diào)節(jié)從免疫功能到神經(jīng)發(fā)育的一系列關(guān)鍵過(guò)程[45-47],從而使大型溞對(duì)水溶性農(nóng)藥的抗性增強(qiáng),這表明N3不飽和脂肪酸可能成為判定大型溞對(duì)水溶性農(nóng)藥抗性強(qiáng)度的依據(jù).目前關(guān)于N3不飽和脂肪酸的研究多側(cè)重于其對(duì)生物體生長(zhǎng)繁殖的影響,例如Müller等[42]研究發(fā)現(xiàn)藻類N3不飽和脂肪酸含量的下降會(huì)抑制大型溞的生長(zhǎng)與繁殖.Twining等[44]發(fā)現(xiàn)與陸生昆蟲(chóng)相比,雛鳥(niǎo)的成活率與富含N3不飽和脂肪酸的水生昆蟲(chóng)生物量顯著正相關(guān),是雛鳥(niǎo)發(fā)育過(guò)程的重要指標(biāo),N3不飽和脂肪酸也促進(jìn)蟹類和魚(yú)類的生長(zhǎng)繁殖,改善其健康狀況[48-49].

陰影部分表示實(shí)驗(yàn)變量與擬合回歸線的誤差

本研究從大型溞對(duì)農(nóng)藥的抗性變化中發(fā)現(xiàn)N3不飽和脂肪酸是其重要的影響機(jī)制因子而非化學(xué)計(jì)量比,N3不飽和脂肪酸作為細(xì)胞膜磷脂的主要組成部分,影響細(xì)胞膜的流動(dòng)性和鑲嵌在脂質(zhì)雙層中蛋白質(zhì)的功能(包括受體、通道和酶類等)[50],N3不飽和脂肪酸通過(guò)增強(qiáng)細(xì)胞膜磷脂的水平從而增強(qiáng)抵抗環(huán)境水溶性農(nóng)藥進(jìn)入細(xì)胞的能力,由于水溶性農(nóng)藥的抗性強(qiáng)度與其N3不飽和脂肪酸成顯著正相關(guān)關(guān)系(圖3f),這說(shuō)明N3不飽和脂肪酸含量是預(yù)測(cè)大型溞對(duì)水溶性農(nóng)藥抗性強(qiáng)度的有效測(cè)量因子,且大型溞的N3不飽和脂肪酸含量越高,對(duì)水溶性農(nóng)藥的抗性越強(qiáng).而另一方面,盡管在細(xì)胞膜的功能上具有重大作用,包含較多不飽和鍵的N3不飽和脂肪酸更容易受到自由基的攻擊,從而影響細(xì)胞膜的結(jié)構(gòu)和流動(dòng)性以及細(xì)胞和組織的生理狀態(tài),具有自由基的脂溶性農(nóng)藥比水溶性農(nóng)藥更容易通過(guò)細(xì)胞膜進(jìn)入細(xì)胞[51].脂溶性污染物的累積也會(huì)影響DHA和EPA的品質(zhì),進(jìn)一步影響細(xì)胞膜受體的活性和生物體的脂類代謝[52],暴露在脂溶性農(nóng)藥的大型溞其N3不飽和脂肪酸含量與抗性不具有顯著相關(guān)性,因此N3不飽和脂肪酸含量不能作為判斷大型溞對(duì)脂溶性農(nóng)藥抗性強(qiáng)度的關(guān)鍵因子.

3 結(jié)論

3.1 作為食物的藻類與大型溞的P:C、N:C和N3不飽和脂肪酸含量成顯著正相關(guān)關(guān)系,即藻類的碳氮磷元素和N3不飽和脂肪酸通過(guò)食物鏈有效地傳遞給了大型溞,其中N3不飽和脂肪酸比生源性元素在能量流動(dòng)和物質(zhì)循環(huán)過(guò)程中傳遞效率更穩(wěn)定.

3.2 以不同藻類種群為食的大型溞暴露在同一農(nóng)藥中呈現(xiàn)不同程度的抗性,這說(shuō)明藻類的質(zhì)量會(huì)影響大型溞對(duì)農(nóng)藥的抗性強(qiáng)度.大型溞暴露在不同性質(zhì)的農(nóng)藥中的抗性強(qiáng)度不同,對(duì)脂溶性農(nóng)藥的抗性差異比暴露在水溶性農(nóng)藥中更明顯,即:農(nóng)藥性質(zhì)不同,以不同藻類為食的大型溞所表現(xiàn)的抗性強(qiáng)度也不同.

3.3 藻類的N3不飽和脂肪酸含量越高,以其為食的大型溞N3不飽和脂肪酸越高,對(duì)水溶性農(nóng)藥的抗性越強(qiáng).但暴露在脂溶性農(nóng)藥的大型溞其N3不飽和脂肪酸含量與抗性不具有顯著相關(guān)性,大型溞對(duì)農(nóng)藥的抗性與其P:C和N:C也不具有顯著相關(guān)性.因此,N3不飽和脂肪酸含量可作為判斷大型溞對(duì)水溶性農(nóng)藥抗性強(qiáng)度的關(guān)鍵因子.

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Ecotoxicological effects and mechanism of algae on's resistance to pesticides.

HE Yan1, SHI Wan-qi1, PENG Xing-xing1, YANG Wei1, LI Zhe-xing1, WEN Xin1, LUO Jun-xiao1, LIU Hua-zu1, LI Wei1,2*

(1.College of Environment and Ecology, Chongqing University, Chongqing 400045, China；2.Key Laboratory of the Three Gorges Reservoir Rigon’s Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China)., 2022,42(9)：4416～4422

To explore the effects and mechanisms of algae on's resistance to pesticides, five algal species (Pyrrophyta, Bacillariophyta, Chlorophyta, Cryptophyta and Cyanophyta) were fed in equal amount to zooplankton, which was then exposed to two insecticides: imidacloprid (water-soluble) and esfenvalerate (fat-soluble). The median lethal concentration (LC50), stoichiometric ratio (P:C, N:C) and fatty acid content ofwere determined.The results show that, compared with biogenic chemical elements such as nitrogen and phosphorus, N3 unsaturated fatty acids can better reveal the predation ofon planktonic algae. The content of N3 unsaturated fatty acids in algae was a key factor affecting the resistance ofto water-soluble pesticides. The difference inresistance was more obvious to fat-soluble pesticides than to water-soluble pesticides. Therefore, the N3 unsaturated fatty acids is the best predictor of the resistance ofto water-soluble pesticides, and can be used to monitor the resistance and risk offood chain to pesticides in a natural environment.

algae；；esfenvalerate；imidacloprid；ecotoxicology；trophic cascade

X171.5

A

1000-6923(2022)09-4416-07

2022-02-14

國(guó)家自然科學(xué)基金資助項(xiàng)目(31700401)、廣西重點(diǎn)研發(fā)計(jì)劃(2018AB36010)

*責(zé)任作者, 副教授, liweieco@cqu.edu.cn

何 妍(1997-),女,貴州遵義人,重慶大學(xué)碩士研究生,主要研究方向?yàn)樯鷳B(tài)毒理學(xué)與水生態(tài)修復(fù).