盐碱池塘围隔生态系统的悬浮物结构及有机碳库储量

1 998年 4～ 7月对高青盐碱池塘单养鲢和罗非鱼围隔生态系统颗粒悬浮物构成和各有机碳库储量及动态进行了研究。结果表明 ,浮游生物的干重 (PZ)占总颗粒悬浮物干物质 (TS)的 4.2 6%～ 2 5 .97% ,平均 1 2 %。各围隔浮游植物干重(DWP)平均值变化范围为 0 .1 6～ 0 .70 mg/L,有鱼围隔均比无鱼围隔的大。浮游动物干重 (DWZ)平均值变化范围为0 .3 2～ 2 .81 mg/L,养鲢围隔中最小 ,小于无鱼对照围隔 ,养罗非鱼围隔明显高于养鲢围隔。颗粒悬浮物的灰分含量平均值为 42 .3 8%。溶解有机碳 (DOC)、颗粒有机碳 (POC)库储量平均值分别为 5 .40± 1 .61 mg C/L和 1 .96± 0 .96mg/L。各处理围隔间颗粒有机物的 C/N比的平均值比较接近 ,总平均值为 6.97± 0 .2 4。 TOC、DOC和 POC比例为 1∶ 0 .73∶0 .2 7。浮游生物碳和腐质颗粒碳占 POC的比例的平均值分别为 3 4.65 %和 65 .3 5 %。腐质颗粒碳、浮游动物碳与浮游植物碳的比例为 9.2 9∶ 3 .71∶ 1。浮游生物碳中浮游动物碳占 78.8% ,浮游植物碳占 2 1 .2 %。浮游动物碳比浮游植物碳高 ,这可能是内陆盐水的通性。盐碱池塘围隔生态系统颗粒有机碳 (POC,mg C/L)与浮游植物叶绿素 a(Chla,μg/L)和悬浮颗粒有机物 (SO,mg/L)之间存在显著的正相关关系 ,其回归方程分别为     

刺参养殖池塘颗粒悬浮物结构及其沉积作用

对不投饵刺参养殖池塘的颗粒悬浮物结构及其沉积量和沉积速度进行了研究.结果表明:(1)各池塘总颗粒悬浮物重量(TS)为(73.1±20.5)mg/L,变动于46.0～132.0mg/L之间;颗粒无机物(IS)含量为(50.6±12.6)mg/L,变动于28.5～76.5mg/L之间,占总颗粒悬浮物的69.13%;浮游生物干重(PZ)为(0.675±0.706)mg/L,变动于0.064～2.814mg/L之间,其中浮游植物干重(DWP)为(0.541±0.622)mg/L,变动于0.062～2.582mg/L之间,浮游动物干重(DWZ) 为(0.135±0.200)mg/L,变动于0.002～1.160mg/L之间;颗粒腐质为(21.91±19.59)mg/L,变动于4.18～83.86mg/L之间,占总颗粒悬浮物的比例为29.95%.(2)总颗粒物沉积量为(19.44±16.34)g·m-2·d-1,变动于6.33～91.98g·m-2·d-1之间,沉降速度为(0.30±0.30)m·d-1,变动于0.08～1.63m·d-1之间,新生态颗粒有机物沉积量为(5.09±7.30)g·m-2·d-1,变化于0.14～31.27g·m-2·d-1之间,总颗粒物沉积量和新生态颗粒物沉积量均是底层高于表层.     

虾池生态系各有机碳库的储量

1997年6～8月于山东省海阳市黄海集团公司养虾场,采用围隔实验生态学方法研究了虾池生态系各有机碳库的储量,结果表明:溶解有机碳(DOC)、颗粒有机碳(POC)库储量(mgC/l)平均分别为9.95±2.04及3.10±1.60,DOC/POC比值平均为3.21.POC库中,腐质颗粒碳为总浮游生物碳的2倍.浮游植物碳、浮游动物碳、浮游细菌碳平均分别占总浮游生物碳的53%、13%及34%.腐质碳、总浮游生物碳平均分别占总有机碳(TOC)的92%及8%,腐质碳为总浮游生物碳的11.08倍.     

西藏达则错盐湖沉积背景与有机沉积结构

以西藏拟溞(Daphniopsis tibetana Sars)为优势浮游动物物种的低盐度盐湖是西藏湖泊的一个重要类型,以达则错为代表,分析了其沉积背景及沉积物组成。结果如下:(1)湖泊敞水区无机沉积以内生化学沉积为主,可代表深水盐湖无机沉积物的自然沉积过程。(2)达则错盐湖浮游植物以蓝藻、硅藻、裸藻、绿藻为主,总生物量11.35 mg/L;浮游动物生物量为4.92 mg/L,其中西藏拟溞占 82.30%;浮游植物残体受盐梯度影响在盐梯度层之上聚集,而浮游动物残体及粪粒(Fecal pellets)因外表有碳酸盐附着可穿过盐梯度层沉积湖底,生物残体与浮游动物代谢产物构成了沉积有机物的物质基础。(3)表层沉积物平均含水量为66.70%,粒径0.004-0.02 mm范围内的颗粒物含量最大,占20.42%,其次为<0.004 mm的粘土,占4.53%。(4)表层沉积物总有机碳(TOC)平均含量为27.99 mg/g(干重),其中颗粒有机碳(POC)约为18.11 mg/g,占TOC的64.70%;在POC中,西藏拟溞粪粒贡献最大,约占POC的60.48%,占TOC的39.06%,占沉积物总量的1.12%,其次为西藏拟溞残体,占POC的38.85%。分析结果表明盐湖因其独特的水化学和生物学特征具有较强的沉积能力,以化学沉积为主的无机沉积及以西藏拟溞粪粒和残肢碎屑为主的有机沉积构成了该类型盐湖颗粒物沉降及沉积的主要过程。     

轮虫培育池生态系统颗粒悬浮物的研究

对两种模式轮虫培育池的悬浮物结构及动态进行了比较研究．结果表明,颗粒悬浮物总量波动在6．76～65．39mg·L^-1之间．静水池塘14#颗粒悬浮物平均值为11．50mg·L^-1,其中颗粒有机物占66．8％,浮游植物占30．5％,浮游动物占5．3％。颗粒腐质和细菌占31％,颗粒无机物占33．2％．流水池塘82#池颗粒悬浮物平均值为41．83mg·L^-1,其中颗粒有机物占70．4％,浮游植物占30％,浮游动物占1．2％,颗粒腐质和细菌占39．2％,颗粒无机物占29．6％．颗粒悬浮物含量静水轮虫池小于流水轮虫池．轮虫培育池是一类特殊类型的生态系统,消费者以褶皱臂尾轮虫为主,群落结构简单,生境易变,这些都会影响水层颗粒悬浮物的动态,造成其含量的较大波动和构成的改变．轮虫培育池生态系统颗粒悬浮物中以颗粒有机物所占比例较大,颗粒腐质和细菌所占份额与浮游生物量相当．     

分区集群式清洁养殖池塘浮游生物群落结构及水环境特征

以传统模式养殖池作对照,研究了分区集群式清洁养殖模式池塘浮游生物群落结构及其水环境特征。结果表明,集群模式池塘网箱内外TN(总氮)分别为1.22 mg/L和1.31 mg/L,TP(总磷)分别为0.169 mg/L和0.170 mg/L,传统模式TN、TP分别为1.76 mg/L和0.689 mg/L。共检出浮游植物6门169种,绿藻门占优。密集养殖区(网箱内)浮游植物生物量为24.54 mg/L,多样性指数2.52,清洁区(网箱外)生物量23.51 mg/L,多样性指数2.47;共检出浮游动物183种,轮虫类占优。密集养殖区浮游动物生物量3.53 mg/L,多样性指数1.82,清洁区生物量2.95 mg/L,多样性指数1.86,传统模式浮游植物、浮游动物生物量分别为49.12、0.53 mg/L,多样性指数分别为2.06、1.79。与传统模式相对比,集群模式池塘TN、TP降低,蓝藻比例下降,浮游植物生物量减少,浮游动物生物量增大,生物多样性指数提高,水环境有一定改善。     

武汉东湖颗粒悬浮物的结构与元素组成

本研究于1989-1990对武汉东湖营养水平不同的二个湖区的颗粒悬浮物的干物质结构和元素组成进行了分析。综合平均值表明,浮游动物的现存量约为浮游植物的1/4,浮游动物群落以小型的原生动物和轮虫占优势。从年平均值来看,浮游生物的干重占颗粒悬浮物干物质的2.5-7.6%,浮游生物碳量占颗粒悬浮物碳量的4.0-9.8%;颗粒悬浮物的碳/氮比与一般浮游植物的比值相似,但明显大于多数浮游动物;颗粒悬浮物的碳与干物重之比约为一般浮游生物的3/4;颗粒悬浮物的灰分含量约为45%,显着高于除硅藻以外的其它浮游生物。从数量上来看,有机碎屑是东湖生态系统颗粒悬浮物最重要的组成部分,而活体浮游生物只占颗粒悬浮物很小的一部分(<10%);这意味着在东湖来自以浮游植物为核心的食物网的有机碎屑的形成速率显着大于有机碎屑的矿化速率。       

沉积再悬浮颗粒物对马氏珠母贝摄食生理影响的室内模拟

采用实验生态学方法室内模拟研究了不同浓度沉积再悬浮颗粒物对马氏珠母贝清滤率、摄食率、吸收率的影响。结果表明:(1)水体中总悬浮颗粒物对马氏珠母贝清滤率的影响极显著(P<0.01)。总悬浮颗粒物由低浓度(12.6 mg/L)趋高浓度(500 mg/L)时,马氏珠母贝的清滤率呈现峰值变化规律。与总悬浮颗粒物浓度50 mg/L时的最大清滤率(1.12 L.个体-1.h-1)比较,悬浮颗粒物浓度为500 mg/L时,清滤率达最小值(0.17 L.个体-1.h-1)),其清滤率降幅达85%。这表明在高浓度悬浮颗粒物的水环境下,贝类受到环境胁迫,其生理和自身摄食机制受到限制,引起摄食减少和机体损伤。马氏珠母贝类的清滤率(CR)与总悬浮颗粒物浓度(TPM)之间的关系可表达为:CR=-0.701+1.627×TPM-0.463×TPM2+0.036×TPM3(R2=0.928)。(2)水体中总悬浮颗粒物对马氏珠母贝摄食率的影响极显著(P<0.01)。马氏珠母贝的摄食率随着总悬浮颗粒物浓度的升高而增加,在50 mg/L时达最大值(38.28 mg/h),当总悬浮颗粒物浓度超过50 mg/L时,摄食率反而下降,在总悬浮颗粒物浓度为500 mg/L时,降为最小值(16.22 mg/h),摄食率降幅为58%。随着悬浮颗粒物浓度的增加,马氏珠母贝摄食率受到的影响小于清滤率受到的影响。马氏珠母贝类的摄食率(IR)与总悬浮颗粒物浓度(TPM)之间的关系可表达为:IR=-46.631+70.957×TPM-18.385×TPM2+1.367×TPM3(R2=0.907)。(3)水体中总悬浮颗粒物对马氏珠母贝吸收率影响极显著(P<0.01)。总悬浮颗粒物由低浓度(12.6 mg/L)趋高浓度(500 mg/L)时,马氏珠母贝的吸收率呈逐渐下降趋势,在总悬浮颗粒物12.6 mg/L时,马氏珠母贝的吸收率最大(48.57%),而总悬浮颗粒物500 mg/L时,马氏珠母贝的吸收率最小(8.56%)。马氏珠母贝的吸收率(AE)与总悬浮颗粒物浓度(TPM)之间的关系可表达为:AE=52.189+0.132×TPM-3.111×TPM2+0.316×TPM3(R2=0.976)。     

发酵有机肥对主养草鱼池塘水质调控效果研究

在草鱼(Ctenopharyngodon idellus)主养池塘中,对比检测了发酵有机肥实验塘与未施肥对照塘水质理化指标、浮游生物及微生物群落结构差异,以分析发酵有机肥肥效及其对池塘水环境产生的影响。结果如下:发酵有机肥显著提高了浮游生物种类数、生物量和细菌丰度,增加了浮游植物多样性;实验期间,实验塘浮游植物、浮游动物平均生物量和细菌平均丰度分别为(68.21±25.13)mg/L、(9.83±5.74)mg/L和(6.53±2.13)×10~6 ind./mL,分别是对照塘的2.78倍、4.35倍和1.29倍;发酵有机肥促进有益菌增殖作用显著,施肥后期,实验塘乳酸菌、芽孢杆菌和节杆菌属相对比例分别为(0.61±0.17)%、(0.89±0.29)%和(0.04±0.0082)%,分别是对照塘的3倍、3倍和4倍;发酵有机肥平抑NH_4~+-N、NO_2-N效果显著,在NH_4~+-N、NO_2~--N快速积累季节,实验塘NH_4~+-N、NO_2~--N浓度均显著低于对照塘(P0.05);发酵有机肥增氧效果显著,而对pH、TN、TP、NO_3~--N、PO_4~(3-)-P等无显著影响。研究结果表明,发酵有机肥肥效突出,具有显著改善池塘水环境作用。     

雅鲁藏布江湘河流域浮游生物群落结构的探究与多样性分析

为了探究雅鲁藏布江湘河流域生物群落结构及物种多样性现状,为西藏地区湘河流域浮游生物资源的保护及开发利用提供科学依据。本研究于2017年3～4月对湘河流域浮游生物进行了生物采样与调查,共设置采样点8个。本次调查共检出浮游植物6门61种,其中硅藻门为优势种,共41种,占总种类数的67.21%;绿藻门、蓝藻门次之,分别占总种类数的11.48%;甲藻门、隐藻门与金藻门种类较少。浮游植物密度范围为0.43×10~5～7.2×10~5cells/L,生物量范围为0.036～2.03 mg/L。共检出浮游动物3门44种,其中原生动物门为优势种,共30种,占总种类数的68.18%;轮虫13种;枝角类1种。浮游动物密度范围为1.5×10~5～1.66×10~6cells/L,生物量范围为0.9×10~(-3)～5.7×10~(-2)mg/L。各调查点浮游植物/浮游动物Shannon-Wiener多样性指数(H)和均匀度指数(E)平均分别为4.38/3.13和0.93/0.93。多项指数综合评价表明,湘河流域水质处于轻度污染或清洁状态,浮游生物群落结构单一,密度及生物量较低,生态环境较脆弱。     

Influence of Three Contrasting Detrital Carbon Sources on Planktonic Bacterial Metabolism in a Mesotrophic Lake

Abstract Lakes receive organic carbon from a diversity of sources which vary in their contribution to planktonic microbial food webs. We conducted a mesocosm study to test the effects of three different detrital carbon sources (algae, aquatic macrophytes, terrestrial leaves) on several measures of microbial metabolism in a small meso-eutrophic lake (DOC ≈ 5 mg/L). Small DOC additions (ΔC < 1 mg/L) affected bacterial numbers, growth, and pathways of carbon acquisition. Macrophyte and leaf detritus significantly increased TDP and color, but bacterial densities initially (+12 h) were unaffected. After 168 h, densities in systems amended with terrestrial detritus were 60% less than in controls, while production rates in mesocosms with macrophyte detritus were 4-fold greater. Detritus treatments resulted in greater per-cell production rates either through stable cell numbers and greater growth rates (macrophyte-C) or lower densities with stable production rates (terrestrial-C). After only 12 h, rates of leucine aminopeptidase (LAPase) activity were 2.5× greater in macrophyte-C systems than in controls, but LAPase and β-N-acetylglucosamindase activities in systems amended with terrestrial-C were only 50% of rates in controls. After 168 h, β-xylosidase rates were significantly greater in communities with terrestrial and phytoplankton detritus. Microbial utilization of >20% of 102 carbon sources tested were affected by at least one detritus addition. Macrophyte-C had positive (6% of substrates) and negative (14%) effects on substrate use; terrestrial detritus had mainly positive effects. An ordination based on carbon-use profiles (+12 h) revealed a cluster of macrophyte-amended communities with greater use of psicose, lactulose, and succinamic acid; controls and algal-detritus systems were more effective in metabolizing two common sugars and cellobiose. After 168 h, communities receiving terrestrial detritus were most tightly clustered, exhibiting greater use of raffinose, pyroglutamic acid, and sebacic acid. Results suggest that pelagic bacterial communities respond to changes in organic carbon source rapidly and by different routes, including shifts in per-cell production rates and variations in degradation of a variety of compounds comprising the DOC pool. Received: 5 June 1998; Accepted: 24 August 1998     

安徽某铁矿不同矿山废水库中微生物群落结构特征

【目的】研究安徽某铁矿不同矿山废水库中微生物群落结构特征及其影响因素。【方法】对比分析了该铁矿3个大型废水库的地球化学特征,并用高通量测序技术研究了水体中微生物群落组成,进而用统计学方法解析了环境因子对微生物群落结构的影响。【结果】3个废水库中有2个为酸性,1个为中性,理化性质有明显的差异。近年形成的塌方采场废水库(TF) pH仅为2.55±0.01,Fe浓度高达154.95±0.78mg/L,SO_4~(2–)浓度为3374.86±3.81mg/L;形成于20世纪70年代的排土场废水库(PT)酸性略弱(pH 2.9±0.02),Fe浓度(34.57±4.00 mg/L)与TF相比明显降低,SO_4~(2–)浓度则高达10398.98±626.70 mg/L;东沙采场废水库(DS)则为中性(pH7.55),但SO_4~(2–)仍高达4162.99mg/L,主要的金属离子为Mg(594.90 mg/L)、Ca (650.10 mg/L)。3个废水库的原核生物多样性随pH的升高而升高。两个酸性废水库的原核生物组成较为接近,但TF的化能自养菌含量较高(69.54%±2.89%),PT的化能异养菌含量较高(64.45%±13.81%)。自养铁氧化菌Ferrovum在TF中的比例高达(64.17±1.84)%,在PT中则下降为(35.39±13.74)%。但PT中含有丰富的化能异养嗜酸菌如Acidicapsa(15.75%±3.99%)、Acidiphilium(10.65%±2.05%)、Acidisphaera (6.34%±1.02%)等。DS中虽然也含有较高的金属离子和SO_4~(2–),但其中的原核生物组成与TF和PT截然不同,主要为Limnohabitans (18.47%)、Rhodobacter (8.42%)等。3个废水库的真核生物群落主要由藻类组成,酸水库TF和PT中主要为棕鞭藻属(Ochromonas)和胶球藻属(Coccomyxa),棕鞭藻属在TF中(53.65%±2.02%)占优势,胶球藻属在PT中(68.84±10.4%)占优势,中性废水库DS中则主要是小环藻属(Cyclotella)(49.85%)。经统计学分析,pH是影响矿山废水微生物多样性和群落组成的主要环境因素。     

<Emphasis Type="Italic">Vibrio cholerae</Emphasis> in waters of the Sunderban mangrove: relationship with biogeochemical parameters and chitin in seston size fractions

Wetland dynamics are probably linked to cholera endemicity in South Asia. We focus on links between Vibrio cholerae abundance, chitin content and suspended particle load in size fractions of suspended particulate matter (SPM) along the salinity gradient of Sunderban mangrove waters. SPM decreased downstream, while salinity increased from 0.2 to 4. Particulate organic carbon (90 ± 25 μM) and nitrogen (9.1 ± 3.3 μM) highly correlated with SPM and turbidity, suggesting a significant contribution of fine particles to organic matter. Total chitin ranged 1–2 mg/l and decreased downstream. The distribution among size fractions of SPM, chitin and V. cholerae O1 (the bacterial serogroup mainly associated with cholera epidemics) was similar, with ~98% of the total in the fraction <20 μm. In comparison, the number of V. cholerae O1 attached to zooplankton and microplankton size classes >20 μm was almost negligible, in contrast to usual assumptions. Thus, microdetritus, nanoplankton and fungal cells in size classes <20 μm represent a chitinaceous substrate on which V. cholerae can grow and survive. Total bacteria, cultivable vibrios and V. cholera O1 increased 5–10 times downstream, together with salinity and nitrite concentration. Overall, nitrate and silicate concentrations were relatively constant (>22 μM N and 100 μM Si). However, nitrite increased ~9 times in the outer sector, reaching ~1.2 μM N, probably as a result of increased abundance of nitrate-reducing vibrios. A characterization of Vibrio habitats that takes account of the presence of nitrate-reducing bacteria could improve the understanding of both mangrove nitrogen cycling and cholera seasonality.     

Nitrifying granules cultivation in a sequencing batch reactor at a low organics-to-total nitrogen ratio in wastewater

It is possible to cultivate aerobic granular sludge at a low organic loading rate and organics-to-total nitrogen (COD/N) ratio in wastewater in the reactor with typical geometry (height/diameter = 2.1, superficial air velocity = 6 mm/s). The noted nitrification efficiency was very high (99%). At the highest applied ammonia load (0.3 ± 0.002 mg NH₄⁺–N g total suspended solids (TSS)⁻¹ day⁻¹, COD/N = 1), the dominating oxidized form of nitrogen was nitrite. Despite a constant aeration in the reactor, denitrification occurred in the structure of granules. Applied molecular techniques allowed the changes in the ammonia-oxidizing bacteria (AOB) community in granular sludge to be tracked. The major factor influencing AOB number and species composition was ammonia load. At the ammonia load of 0.3 ± 0.002 mg NH₄⁺–N g TSS⁻¹ day⁻¹, a highly diverse AOB community covering bacteria belonging to both the Nitrosospira and Nitrosomonas genera accounted for ca. 40% of the total bacteria in the biomass.     

Spatial and seasonal distribution of heterotrophic bacteria in pond water and sediments under different management practices

Population densities and generation time of heterotrophic bacteria were estimated in water and sediments of fish ponds used for polyculture, monoculture and traditional systems of fish farming over a period of two and a half years. Spatial differences in microbial densities in the ponds were related to the organic loadings of the farm site and farm management. A number of environmental factors such as nitrogen, dissolved organic carbon, bicarbonate and phosphate of water were found to be responsible for the seasonal changes of heterotrophic bacteria in these ponds.     

Carbon sources and trophic structure in a macrophyte‐dominated polyculture pond assessed by stable‐isotope analysis

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Microbial and decomposition efficiencies of monoculture and polyculture vermireactors,based on epigeic and anecic earthworms

Efforts have been made to evaluate the microbial and decomposition efficiency of three different vermireactors: (i) polyculture (introducing equal numbers of anecic and epigeic earthworms), (ii) monoculture (anecic) and (iii) monoculture (epigeic), designed by using earthworms of two different ecological categories i.e. anecic (Lampito mauritii Kinberg) and epigeic (Eisenia fetida (Savigny)). The microbial load of vermireactors was measured through substrate-induced respiration rate (SIR), microbial biomass N content and rate of dehydrogenase activity, while mineralization rate was evaluated measuring some chemical parameters of the substrate. Earthworms caused a decrease (as compared to initial value) in pH (41.9–80.7%), organic C (10.3–14.2%) and C:N ratio (41.9–80.7%) and an increase in total N (29.1–58.8%), NH₄-N (876.1–1485.7%), NO₃-N (29081.8–56792.6%), available P (16–19.4%) and exchangeable K (9.8–13.5%) contents of the substrate. The mineralization efficiency of the reactors was in the order: polyculture (epigeic + anecic) > monoculture (anecic) > monoculture (epigeic). The polyculture reactor showed the maximum rate of SIR (2.91 ± 0.2 mg CO₂ g⁻¹ substrate), microbial biomass N (3108.1 ± 289.2 mg N g⁻¹ substrate), and dehydrogenase activity (2453.3 ± 379.8 μg g⁻¹ substrate 24 h), while in the monoculture (epigeic) the lowest values of the same parameters were observed. It is concluded that the observed differences among reactors were due to different feeding behaviour and niche structures of epigeic and anecic earthworms. Data suggests that burrowing earthworms in waste-decomposing-system not only enhance the microbial efficiencies, but at the same time also accelerate the organic matter mineralization in a vermireactor. However, most of the previous studies were based on monoculture reactors (using epigeic earthworms) which have been recommended for waste decomposition operations, but this study revealed that polyculture vermicomposting (adding of burrowing worms with epigeic earthworms in vermicomposting system) might be beneficial for rapid decomposition of organic wastes.     

Beaver invasion alters terrestrial subsidies to subantarctic stream food webs

North American beavers (Castor canadensis) were introduced to Tierra del Fuego Island in 1946 for their fur, and have since spread across the archipelago and onto the South American mainland. We assessed the impact of invasive beavers on streams of these forested watersheds by quantifying the trophic basis of production (TBP) and consumptive organic matter flows of benthic macroinvertebrate assemblages. TBP was determined in two streams: clear- and black-water. Stable isotopes were used across four streams to further elucidate food web structure and dominant pathways. TBP and stable isotopes showed that terrestrially derived organic matter (amorphous detritus, leaves, and wood) supported a majority of secondary production in the benthic food webs at all sites (forested reaches, beaver ponds, and sections downstream of ponds with foraged riparian zones). The magnitude of these flows was enhanced in beaver-modified sites compared with forested habitats (4.0–5.3× increase g AFDM m⁻² year⁻¹ in pond habitats, 1.1–2.1× increase in downstream habitats). Diatoms were the only autochthonous resource identified in macroinvertebrate guts, but their contribution to secondary production was small. Consumptive flows mirrored trends in TBP (i.e., dominance of terrestrial sources and greater magnitude in beaver ponds). Collector–gatherer consumption of amorphous detrital material dominated food web flows in all habitats, but was higher in beaver ponds relative to other habitats. Food web structure was simplified in beaver ponds; only two of the five possible functional groups contributed >1% of total organic matter flow in ponds (collector–gatherers and predators). Consumptive flows to predators increased in ponds, and stable isotopes of nitrogen and carbon (δ¹⁵N and δ¹³C) corroborated a relatively greater importance of predators (greater trophic distance), as well as less diversity of basal resources (less variation in δ¹³C) in ponds. Our findings indicate that invasive beaver’s engineering activities resulted in greater flows of terrestrial organic matter subsidies to in-stream food webs, which had a relatively greater change in the clear-water than in the black-water stream. Owing to the fact that these streams were naturally dependent on allochthonous resources for a majority of production and material flows, changes wrought by beavers to streams in forested environments are probably less than in watersheds with inherently greater dependence on autochthonous production such as the adjacent steppe biome.