作为鱼类等水生动物的天然饵料, 底栖动物是河流生态系统的一个重要生物类群, 在物质循环、能量流动中发挥着极其重要的作用(蒋小明等, 2011)。底栖动物包含了从最低等的原生动物到昆虫等几乎所有的无脊椎动物门类, 它们具有生命周期较长、迁移能力较弱、分布范围广等特点。同时, 不同种类的底栖动物对水质的敏感性差异大、受外界干扰后群落的变化趋势可预测, 从而对环境有着很好的指示作用, 使该类群成为了解河流生态系统结构、功能及健康状况的指示类群。
有关赤水河底栖动物的研究已见报道, 但仍不充分, 主要表现为: (1)研究的尺度较小。对赤水河底栖动物的研究大多聚焦于干流河段(蒋小明, 2009( 蒋小明 (2009) 赤水河大型无脊椎动物生态学研究. 硕士学位论文, 中国科学院水生生物研究所, 武汉.); 王军, 2018), 缺乏包含干流和支流的全流域调查。(2)缺乏连续性、季节性的调查。所得出的结论并不能充分反映赤水河底栖动物的真实情况。赤水河生境多样、水系复杂, 底栖动物资源十分丰富。在全球气候变化和人为活动加剧的情况下, 开展赤水河全流域的底栖动物多样性调查是科学评价其生态系统健康状况, 实现生物多样性保护和资源可持续开发利用的重要基础, 同时可为长江流域生物多样性的研究和保护提供较为全面的基础资料。
1 材料与方法
1.1 研究区域
赤水河发源于云南省镇雄县赤水源镇, 流经云南省、贵州省和四川省的13个县市, 在四川省泸州市合江县汇入长江。干流全长436.5 km, 流域面积20,440 km2, 天然落差1,274.8 m。赤水河自茅台镇以上的区域为上游, 长224.7 km, 河道多为岩层走向切割, 河谷深邃, 两岸多为悬崖峭壁, 水流湍急; 茅台镇至赤水市为中游, 长54 km, 属山麓地带, 是高原与盆地的倾斜地带, 河谷较宽, 两岸间有台地; 赤水市至河口为下游, 河流长157.8 km, 多为丘陵盆地, 河宽水深, 水流较缓, 险滩明显减少, 是典型的丹霞地貌(秦强, 2021; 夏治俊, 2021①( 夏治俊 (2021) 赤水河流域鱼类多样性格局及集合群落研究. 硕士学位论文, 中国科学院水生生物研究所, 武汉.))。赤水河流域位于云贵高原与四川盆地接壤地带, 属中亚热带大陆性季风气候, 温暖湿润, 无霜期长, 雨量充沛, 夏季湿热而冬季干旱(赵静等, 2015)。
1.2 样点设置及样品采集
赤水河全流域共布设54个样点, 包括上游20个, 中游21个, 下游13个, 调查的支流包括铜车河、倒流河、二道河、桐梓河、古蔺河以及习水河(图1)。分别于2019年10月(秋季)、2019年12月(冬季)、2020年7月(夏季)和2021年3月(春季)开展全流域的调查。根据采样点生境特征, 每个样点均采集2-3个定量样品和1个定性样品。在每个样点周边100 m的河段内, 选取代表性生境(流速、水深和底质组成)进行采集(图1)。定量采集时, 在深水处(水深 > 0.5 m)使用Peterson采泥器(面积0.0625 m2)采集; 浅水处(水深 < 0.5 m)使用Surber网(筛网孔径420 μm, 采样面积0.09 m2)进行。定性采集用D型网。样品经40目分样筛筛洗后, 置入封口袋中, 带回室内进行分拣。将洗净的样品倒入解剖盘中, 逐一将动物标本拣出, 置入50 mL的塑料标本瓶中, 加入75%的酒精保存。在实验室内, 依据相关参考文献(刘月英, 1979; Morse et al, 1994; Epler, 2001; 周长发等, 2003; 王俊才和王新华, 2011; 张浩淼, 2012)完成种类鉴定。其中, 水生寡毛类和摇蚊幼虫的鉴定在显微镜下完成, 蛭类、腹足类和大多数水生昆虫则依靠体视显微镜完成。底栖动物的鉴定尽量到属或种级水平, 少部分鞘翅目物种鉴定到科水平。鉴定完成后, 记录每个物种的个数(条), 并用吸水纸将动物体表的水分吸干, 用1/10000的电子天平称重。在进行数据分析时, 根据采样面积换算为每平方米的密度和生物量。
图1
图1
赤水河流域底栖动物调查样点分布示意图
Fig. 1
Distribution of sampling sites for benthic macroinvertebrates in the Chishui River basin
1.3 环境指标的测定
环境因子的测定包括河流生境特征(物理因子)的现场调查及水质指标(化学因子)的实验室测定。在样本采集时, 现场测定样点的生境指标。采用YSI多参数便携式水质分析仪(YSI6600)测定水温、pH值和电导率等物理因子。海拔和地理坐标用手持式Garmin GPS-76测定。流速用LJD-10流速仪测定。将底质类型分为大石、鹅卵石、圆石、砾石、泥沙和黏土5类, 并估测各底质类型的百分比。在各采样点采集水样1 L, 于低温下避光保存, 24 h内带回实验室, 参照《水和废水监测分析方法(第四版)》(国家环境保护总局, 2002)测定水体的化学指标, 包括高锰酸盐指数(CODMn)、总磷(total phosphate)、铵氮(NH4+-N)、硝酸盐氮(NO3--N)、亚硝酸盐氮(NO2--N)和总氮(total nitrogen)。
1.4 数据处理
式中, S为物种数, Pi为物种i在样本中的相对丰度。
使用单因素方差分析(one-way ANOVA)检测赤水河不同季节和河段的底栖动物密度、生物量和多样性指数的差异。如果方差齐性, 就用HSD (Tukey’s honestly significant difference)检验; 如果方差不齐, 就选用Games-Howell检验。本研究中, 将单个物种密度百分比大于5%的定义为优势种(Bunn et al, 1986; 熊晶等, 2012)。使用主坐标分析(principal co- ordinates analysis, PCoA)和PERMANOVA检验比较不同季节和河段的底栖动物群落结构。单因素方差分析在SPSS 26.0中完成, 主坐标分析和PERMANOVA分别使用R语言pcoa程序包和vegan程序包中的函数“PERMANOVA”完成。
利用IndVal指数(index of valuation)进行指示物种和指示值分析。计算赤水河上、中、下游底栖动物的指示值, 选择指示值高且具有显著性的物种作为不同河段的指示物种。指示值高表明该物种在特定河段更为普遍, 并且在该河段的绝大部分样点均存在。物种指示值计算在R语言中使用labdsv程序包中的函数“indval”实现(Robert, 2016)。指示值的显著性通过置换检验来计算。
采用主轴邻距法(principal coordinates of neighbor matrices, PCNM)来度量样点间的空间变量(Borcard & Legendre, 2002), 该方法是基于各样点的空间坐标位置, 计算出多尺度上具有空间正自相关的特征值, 用特征值作为空间变量来解释扩散等随机过程引起的群落变化。共获取空间正自相关的PCNM变量24个, 这些变量被应用于后续的分析中。其中, 拥有较大特征值的PCNM变量(如PCNM1)代表大尺度的空间过程, 拥有较小特征值的PCNM变量(如PCNM24)则代表小尺度的空间过程。PCNM分析在R语言使用vegan程序包中的pcnm()函数实现。
运用束缚型排序方法解析解释变量(环境因子和空间因子)和响应变量(底栖动物群落参数)间的关系。首先对赤水河底栖动物群落数据进行除趋势对应分析(detrended correspondence analysis, DCA), 计算最长梯度值, 结果显示线性模型(gradient length < 3 standard units)更适合群落与环境因子关系的解析, 本研究采用冗余分析(redundancy analysis, RDA) (Leps & Smilauer, 2003)。为了优化分析, 将群落数据进行lg(x + 1)转化。剔除具有较高相关性(r > 0.80)及膨胀因子(inflation factor)大于20的环境因子, 同时在分析中降低稀有物种的权重。DCA和RDA分析在Canoco for Windows 5.0中完成。
利用方差分解(variation partitioning, VPA)分割环境因子和空间因子对响应变量(群落结构)的贡献大小。首先将赤水河底栖动物群落组成之间的变异看作一个整体, 通过偏冗余分析将群落变异分解为4个部分: 被环境因子解释的部分、被空间因子解释的部分、环境因子和空间因子共同解释的部分和未解释的部分, 同时用置换性检验分析其显著性。最后根据各解释模型对应校正R2 (adjust R2)值和P值来确定影响群落结构的因素(Peres-Neto et al, 2006)。方差分解在R语言使用vegan程序包中的varpart函数实现。
2 结果
2.1 环境因子特征
单因素方差分析结果显示, 大部分环境因子如河宽、水深、海拔、总氮、高锰酸盐指数、溶解氧和氧化还原电位(oxidation-reduction potential, ORP)在上中下游之间差异显著(P < 0.05) (表1)。从上游到下游, 河宽、水深和高锰酸盐指数呈现递增趋势。上游位于山区, 底质以大石为主, 溶解氧与ORP较高。中下游底质则多为沙和淤泥, 中游铵氮要高于其他河段, 下游高锰酸盐指数最高。
表1 赤水河不同河段环境因子的均值和标准差
Table 1
| 上游 Upstream | 中游 Midstream | 下游 Downstream | F | P | |
|---|---|---|---|---|---|
| 河宽 Channel width (m) | 36.07 ± 21.55 | 77.69 ± 51.53 | 193.80 ± 43.15 | 18.869 | < 0.001* |
| 流速 Current velocity (m/s) | 1.04 ± 0.39 | 1.32 ± 0.78 | 0.70 ± 0.60 | 2.795 | 0.074 |
| 水深 Water depth (m) | 0.26 ± 0.21 | 0.36 ± 0.14 | 0.63 ± 0.59 | 5.434 | 0.009* |
| 海拔 Altitude (m) | 920.55 ± 463.32 | 314.68 ± 51.60 | 213.55 ± 7.93 | 46.367 | < 0.001* |
| 大石 Boulder (%) | 0.57 ± 0.18 | 0.31 ± 0.37 | 0.01 ± 0.03 | 16.172 | < 0.001* |
| 卵石 Pebble (%) | 0.34 ± 0.89 | 0.04 ± 0.04 | 0.01 ± 0.03 | 6.319 | 0.004* |
| 沙 Grit (%) | 0.46 ± 0.13 | 0.25 ± 0.23 | 0.19 ± 0.38 | 6.036 | 0.005* |
| 淤泥 Silt (%) | 0.21 ± 0.18 | 0.62 ± 0.41 | 0.89 ± 0.22 | 14.465 | < 0.001* |
| 铵氮 Ammonia nitrogen (mg/L) | 0.19 ± 0.06 | 0.21 ± 0.12 | 0.19 ± 0.07 | 0.262 | 0.771 |
| 总氮 Total nitrogen (mg/L) | 3.65 ± 0.85 | 3.24 ± 0.19 | 2.71 ± 0.59 | 3.952 | 0.028* |
| 总磷 Total phosphate (mg/L) | 0.05 ± 0.02 | 0.06 ± 0.02 | 0.05 ± 0.01 | 0.319 | 0.729 |
| 高锰酸盐指数 CODMN (mg/L) | 1.78 ± 0.39 | 2.91 ± 0.78 | 3.58 ± 0.74 | 24.169 | < 0.001* |
| 电导率 Conductivity (μS/cm) | 447.43 ± 164.49 | 590.49 ± 34.42 | 402.01 ± 193.23 | 2.664 | 0.083 |
| 溶解氧 Dissolved oxygen (mg/L) | 15.08 ± 1.68 | 13.50 ± 0.75 | 12.03 ± 1.76 | 9.309 | < 0.001* |
| pH | 7.96 ± 0.41 | 8.04 ± 0.11 | 7.95 ± 0.07 | 0.358 | 0.701 |
| 氧化还原电位 Oxidation-reduction potential (mV) | 73.32 ± 31.37 | 38.95 ± 20.36 | 42.79 ± 21.34 | 5.273 | < 0.001* |
* P < 0.05
2.2 物种组成和结构
2019-2021年记录底栖动物共209种, 隶属于5门9纲22目86科186属209种。其中线形动物门1种, 扁形动物门1种, 环节动物门16种, 软体动物门15种, 节肢动物门176种(图2)。
图2
图2
赤水河流域大型底栖动物物种组成
Fig. 2
Species composition of benthic macroinvertebrates in the Chishui River
赤水河全流域底栖动物群落的平均密度和生物量分别为516.31 ind./m2和13.26 g/m2。全流域优势种为蜉蝣属一种(Ephemera sp.)、扁蜉属一种(Heptagenia sp.)、河花蜉属一种(Polamanthus sp.)、四节蜉属一种(Baetis sp.)、潜水蝽科一种(Naucoridae sp.)、多足摇蚊属一种(Polypedilum sp.)。
2.3 群落时空分布格局
本次调查结果显示, 赤水河底栖动物在不同季节与不同河段间群落组成差异较大。4个季度的优势种均为水生昆虫(表2)。其中, 四节蜉属一种在4个季度中均为优势种; 纹石蛾属一种(Hydropsyche sp.)、扁蜉属一种和多足摇蚊属一种亦是多个季度的优势种; 春季的优势种还有河花蜉属一种, 夏季的优势种还有霍甫水丝蚓(Limnodrilus hoffmeisteri); 秋季的优势种还包括花翅蜉属一种(Baetiella sp.)、柔裳蜉属一种(Habrophlebiodes sp.)、小蜉属一种(Ephemerella sp.)、齿斑摇蚊属一种(Stictochironomus sp.) (表2)。
表2 赤水河不同季节大型底栖动物群落优势种百分比
Table 2
| 物种 Taxa | 春季 Spring (%) | 夏季 Summer (%) | 秋季 Autumn (%) | 冬季 Winter (%) |
|---|---|---|---|---|
| 霍甫水丝蚓 Limnodrilus hoffmeisteri | 6.95 | |||
| 四节蜉属一种 Baetis sp. | 10.19 | 23.12 | 20.63 | 17.94 |
| 花翅蜉属一种 Baetiella sp. | 6.61 | |||
| 柔裳蜉属一种 Habrophlebiodes sp. | 8.34 | |||
| 小蜉属一种 Ephemerella sp. | 5.17 | |||
| 扁蜉属一种 Heptagenia sp. | 13.39 | 27.53 | ||
| 河花蜉属一种 Polamanthus sp. | 11.91 | |||
| 纹石蛾属一种 Hydropsyche sp. | 6.64 | 14.31 | 15.05 | |
| 齿斑摇蚊属一种 Stictochironomus sp. | 5.75 | |||
| 多足摇蚊属一种 Polypedilum sp. | 9.13 | 5.72 |
赤水河上游底栖动物以水生昆虫为主, 占上游密度的95%, 优势种为蜉蝣属一种、扁蜉属一种、河花蜉属一种、四节蜉属一种和潜水蝽科一种; 中游以摇蚊类群、软体动物为主, 优势种为似动蜉属一种(Cinygmula sp.)、枝长跗摇蚊属一种(Cladotanytarsus sp.)、多足摇蚊属一种、环棱螺属一种(Bellamya sp.)以及湖球蚬(Sphaerium lacustre); 下游则以四节蜉属一种、潜水蝽科一种、多足摇蚊属一种和齿斑摇蚊属一种为优势种(表3)。
表3 赤水河不同河段大型底栖动物群落优势种百分比
Table 3
| 物种 Taxa | 全流域 Chishui River (%) | 上游 Upstream (%) | 中游 Midstream (%) | 下游 Downstream (%) |
|---|---|---|---|---|
| 蜉蝣属一种 Ephemera sp. | 8.09 | 11.39 | ||
| 扁蜉属一种 Heptagenia sp. | 7.78 | 10.34 | ||
| 河花蜉属一种 Polamanthus sp. | 6.62 | 9.91 | ||
| 四节蜉属一种 Baetis sp. | 6.70 | 6.98 | 12.36 | |
| 似动蜉属一种 Cinygmula sp. | 7.39 | |||
| 潜水蝽科一种 Naucoridae sp. | 6.62 | 7.39 | 8.13 | |
| 多足摇蚊属一种 Polypedilum sp. | 6.55 | 16.37 | 15.99 | |
| 齿斑摇蚊属一种 Stictochironomus sp. | 27.99 | |||
| 枝长跗摇蚊属一种 Cladotanytarsus sp. | 8.97 | |||
| 环棱螺属一种 Bellamya sp. | 11.54 | |||
| 湖球蚬 Sphaerium lacustre | 7.04 |
指示物种分析结果显示, 上中下游指示生物的种类和数量存在明显差异。总体而言, 水生昆虫是上游主要的指示生物, 部分摇蚊和腹足类是中下游的指示生物(表4)。
表4 赤水河不同河段指示物种
Table 4
| 物种 Taxa | 河段 Reaches | 指示值 Indicator value | 显著性 P |
|---|---|---|---|
| 蜉蝣属一种 Ephemera sp. | 上游 Upstream | 0.721 | 0.004 |
| 细蜉属一种 Caenis sp. | 上游 Upstream | 0.520 | 0.013 |
| 扁蜉属一种 Heptagenia sp. | 上游 Upstream | 0.721 | 0.006 |
| 小蜉属一种 Ephemerella sp. | 上游 Upstream | 0.632 | 0.004 |
| 河花蜉属一种 Polamanthus sp. | 上游 Upstream | 0.782 | 0.001 |
| 亚美蜉属一种 Ameletus sp. | 上游 Upstream | 0.567 | 0.009 |
| 叉襀属一种 Nemoura sp. | 上游 Upstream | 0.368 | 0.030 |
| 角石蛾属一种 Stenopsyche sp. | 上游 Upstream | 0.421 | 0.029 |
| 短脉纹石蛾属一种 Cheumatopsyche sp. | 上游 Upstream | 0.416 | 0.048 |
| 龙虱科一种 Dytiscidae sp. | 上游 Upstream | 0.421 | 0.024 |
| 溪泥甲属一种 Oulimnius sp. | 上游 Upstream | 0.545 | 0.015 |
| 环足摇蚊属一种 Cricotopus sp. | 上游 Upstream | 0.474 | 0.023 |
| 大蚊属一种 Tipula sp. | 上游 Upstream | 0.886 | 0.001 |
| 朝大蚊属一种 Antocha sp. | 上游 Upstream | 0.400 | 0.039 |
| 虻科一种 Tabanidae sp. | 上游 Upstream | 0.316 | 0.025 |
| 水螨 Hydrachnellae sp. | 中游 Midstream | 0.059 | 0.032 |
| 多足摇蚊属一种 Polypedilum sp. | 下游 Downstream | 0.583 | 0.047 |
| 无距摇蚊属一种 Acalcarella sp. | 下游 Downstream | 0.388 | 0.015 |
| 齿斑摇蚊属一种 Stictochironomus sp. | 下游 Downstream | 0.587 | 0.005 |
| 贝蠓 Bezzia sp. | 下游 Downstream | 0.663 | 0.001 |
| 凸旋螺 Gyraulus convexiusculus | 下游 Downstream | 0.323 | 0.035 |
从空间尺度上看, 上游底栖动物平均密度(720.27 ind./m2)要高于中游(278.82 ind./m2)与下游(501.19 ind./m2), 上游的平均生物量(11.45 g/m2)要高于中游(6.48 g/m2)和下游(6.28 g/m2) (图3)。从时间尺度看, 冬季底栖动物平均密度(593.83 ind./m2)高于春季(516.31 ind./m2)、秋季(493.11 ind./m2)和夏季(438.38 ind./m2); 春季底栖动物的平均生物量最高(8.94 g/m2), 其次是夏季(8.43 g/m2)、秋季(7.44 g/m2)和冬季(6.29 g/m2) (图4)。
图3
图3
赤水河流域不同河段大型底栖动物群落密度(A)、生物量(B)、物种丰富度指数(C)、Simpson优势度指数(D)、Shannon-Wiener多样性指数(E)和Pielou均匀度指数(F)。不同字母表示存在显著差异(P < 0.05)。
Fig. 3
Density (A), biomass (B), richness (C), Simpson dominance index (D), Shannon-Wiener diversity index (E) and Pielou evenness index (F) of benthic macroinvertebrates communities in different reaches in the Chishui River basin. Different letters indicate significant differences (P < 0.05).
图4
图4
赤水河流域不同季节大型底栖动物群落密度(A)、生物量(B)、物种丰富度指数(C)、Simpson优势度指数(D)、Shannon-Wiener多样性指数(E)和Pielou均匀度指数(F)。不同字母表示存在显著差异(P < 0.05)。
Fig. 4
Density (A), biomass (B), richness (C), Simpson dominance index (D), Shannon-Wiener diversity index (E) and Pielou evenness index (F) of benthic macroinvertebrates communities in different seasons in the Chishui River basin. Different letters indicate significant differences (P < 0.05).
图5
图5
赤水河流域不同河段(a)和不同季节(b)大型底栖动物PCoA分析图
Fig. 5
PCoA analysis of benthic macroinvertebrates in different reaches (a) and seasons (b) of the Chishui River basin
2.4 底栖动物群落与环境和空间因子的关系
表5 赤水河流域底栖动物群落结构与环境因子和空间因子关系的冗余分析(RDA)结果
Table 5
| F | P | 第1轴 Axis 1 | 第2轴 Axis 2 | 第3轴 Axis 3 | 第4轴 Axis 4 | |
|---|---|---|---|---|---|---|
| 环境因子 Environmental factors | ||||||
| 大石 Boulder | 4.77 | 0.001 | -0.76 | -0.59 | 0.04 | 0.25 |
| 海拔 Altitude | 6.24 | 0.001 | -0.91 | 0.22 | 0.07 | 0.02 |
| 流速 Velocity | 1.99 | 0.001 | 0.09 | 0.03 | 0.75 | 0.58 |
| 溶解氧 Dissolved oxygen | 1.91 | 0.001 | 0.37 | -0.80 | 0.08 | -0.16 |
| NH4+-N | 1.74 | 0.001 | -0.05 | -0.02 | 0.90 | -0.23 |
| 空间因子 Spatial factors | ||||||
| 大尺度 PCNM1 | 5.39 | 0.001 | -0.84 | 0.25 | 0.46 | 0.11 |
| 大尺度 PCNM2 | 3.17 | 0.001 | 0.53 | 0.31 | 0.79 | -0.01 |
| 大尺度 PCNM6 | 2.13 | 0.009 | 0.32 | -0.66 | 0.25 | 0.71 |
| 大尺度 PCNM3 | 2.19 | 0.014 | -0.11 | -0.64 | 0.32 | -0.70 |
PCNM为principal coordinates of neighbor matrices的缩写。PCNM stands for principal coordinates of neighbor matrices.
图6
图6
赤水河流域大型底栖动物群落分布与环境因子和空间因子的冗余分析。PCNM 1、PCNM 2、PCNM 3和PCNM 6为大尺度空间因子。
Fig. 6
Redundancy analysis (RDA) ordination plots showing the relationship between benthic macroinvertebrates communities and significant environmental and spatial factors in the Chishui River. PCNM1, PCNM2, PCNM3 and PCNM6 are large-scale spatial factors.
图7
图7
环境因子、空间因子对赤水河流域大型底栖动物群落结构的解释率。*表示存在显著差异(P < 0.05)。
Fig. 7
Benthic macroinvertebrates communities and their environmental and spatial explanations in Chishui River. * indicate significant differences (P < 0.05).
3 讨论
3.1 物种组成及多样性
本次赤水河流域调查共鉴定底栖动物209种, 包括线虫动物门1种, 扁形动物门1种, 环节动物门16种, 软体动物门15种, 节肢动物门176种(附录1)。流域内底栖动物整体表现为水生昆虫占绝对优势, 这与前人研究一致。综合历史资料调查可知, 赤水河底栖动物的密度和物种丰富度正在逐渐减少(蒋小明, 2009( 蒋小明 (2009) 赤水河大型无脊椎动物生态学研究. 硕士学位论文, 中国科学院水生生物研究所, 武汉.); 王军, 2018), 优势种也从清洁种逐渐转变为一些耐污类群(寡毛类, 摇蚊类)。这主要是由于赤水河流域人为活动加剧了对底栖动物栖息地的破环, 从而导致赤水河底栖动物多样性的下降。
赤水河底栖动物多样性有着明显的时空变化。从时间上看, 春季底栖动物的多样性要高于其他季节。在春季, 亚热带地区大部分水生昆虫如蜉蝣目(Earle, 1955)、毛翅目(Corbet, 1966)、鞘翅目(Morse et al, 1984)和双翅目(王俊才和王新华, 2011)处于其生活史的水生稚虫阶段, 更易于采集, 因此其多样性相对较高。而夏秋两季降水频繁, 采样月份均处于雨季, 洪水对底栖动物的冲击力度增大, 导致部分物种减少, 甚至消失; 另一方面, 部分水生昆虫逐渐羽化, 其生活史经历了由水生稚虫向陆生成虫的转变, 所以夏秋两季底栖动物多样性较低。在冬季, 经历冲刷后的底栖动物正处在逐步恢复的过程, 因此底栖动物多样性相对较低。
从空间分布来看, 上游物种多样性最高, 中下游物种多样性则相对较低。上游流速快, 底质多为大石, 溶解氧丰富, 为EPT类群(蜉蝣目、襀翅目、毛翅目)等创造了适宜的生存环境。中下游河流水深少石, 流速变缓, 河道变宽, 同时人为干扰严重影响了底栖动物的群落组成, 造成耐污种(如摇蚊类、寡毛类等)增加, 进而导致群落物种数和多样性的下降。赤水河是典型的亚热带山地河流, 地形地貌复杂, 植被类型丰富, 生境异质性高, 为水生昆虫(尤其是EPT类群)提供了重要的栖息地和避难所。与同样为长江流域的赣江(邢圆等, 2019)和湘江( 刘俊 (2006) 湘江软体动物多样性研究. 硕士学位论文, 湖南师范大学, 长沙.)相比, 赤水河软体动物多样性明显偏低。在赤水河全流域仅调查到15种软体动物, 且出现的多为一些耐污种和广布种如尖膀胱螺一种(Physa acuta)和萝卜螺属一种(Radix sp.)。一般认为软体动物的物种起源是在低海拔地区(如海洋), 随着时间的变化, 逐渐向高海拔地区扩散并发生物种分化(王军, 2018)。软体动物的移动能力有限, 且只能依靠水体被动扩散, 因此软体动物难以生存定居。
3.2 底栖动物群落结构与环境和空间因子的关系
冗余分析结果表明, 海拔、底质、溶解氧、流速是影响赤水河流域底栖动物群落的关键环境因子。海拔作为综合性的环境因子, 是生物多样性分布格局的决定性因素之一。不同海拔地区光照、溶解氧和温度不同, 能够直接或间接影响底栖动物的群落结构和多样性的空间分布(Nelson, 2011)。底质是底栖动物进行生命活动的主要场所, 底质的粒径大小、异质性和稳定性等对底栖动物组成有着明显的影响(任海庆等, 2015)。对底栖动物来说, 丰富的群落多样性离不开底质的异质性和稳定性。上游低级别的支流底质一般为大石和鹅卵石, 大石形成的生境较为复杂, 能够为底栖动物提供更多的产卵、捕食和避难场所(Ormerod & Edwards, 1987), 增加了底栖动物的多样性。随着不同支流的汇入, 中下游河道变宽, 水深加深, 底质多为细沙和淤泥, 它们更容易受到河水冲刷使得各种微小生境的稳定性变差, 进而导致群落多样性降低。在本次调查中, EPT昆虫大多出现在底质粒径较大的上游, 而摇蚊类和寡毛类则多在底质粒径较小的中下游环境中生存。溶解氧同样影响着赤水河底栖动物的分布格局。水生生物依靠溶解氧才能在水中生活, 水体中溶解氧的多寡极大程度上影响着生物的新陈代谢、摄食、繁殖等生命活动(Jacobsen, 2008)。赤水河上游河流溶解氧丰富, 为好氧的底栖动物提供了良好的生存条件。襀翅目的密度与溶解氧的含量息息相关, 赤水河中的卷襀属一种(Leuctra sp.)、叉襀属一种(Nemoura sp.)、襀科一种(Perlidae sp.)等类群仅出现在溶解氧含量较高的上游; 与上游不同的是, 中下游的溶解氧逐渐降低, 对溶解氧需求较低的类群如普通仙女虫(Nais communis)、霍甫水丝蚓等在中下游密度更高。流速对于底栖动物的物种组成亦有重要作用, 流速与底栖动物的生活型、摄食方式、体型和氧气需求有着密切的关系(郑文浩等, 2011), 流速可以加快水体的更新并带来丰富的营养物质, 为底栖动物创造适宜的生存条件(Degani et al, 1993)。在适当的流速下底栖动物多样性极为丰富, 但过急的流速亦会导致其密度下降(Alvarez-Cabria et al, 2011)。不同的流速对底栖动物有着一定的筛选作用, 在激流区, 底栖动物进化出流线型(四节蜉属)或扁平型(扁蜉属), 从而避免被水流冲走; 在静水区, 泥沙及有机质不断沉积, 底栖动物多以圆柱体(摇蚊类、寡毛类和蜉蝣属)来适应穴居生活(Li et al, 2019)。
方差分解结果显示环境因子比空间因子对赤水河流域底栖动物的分布有着更大的影响, 表明环境过滤可能是影响赤水河底栖动物群落构建的主导力量。本研究发现一些表征河流生境条件的环境因子(如海拔、流速、底质组成、溶解氧等)是驱动底栖动物群落的关键因素, 这与国内外多数河流底栖动物群落构建研究的结果相似(Heino et al, 2015; Li et al, 2022)。空间因子同样对底栖动物的分布有着一定影响。RDA筛选出影响底栖动物分布的空间因子主要是代表大尺度的PCNM1、PCNM2和PCNM3, 表明扩散限制是驱动赤水河底栖动物群落结构的关键因素。研究表明, 各种生态学过程在群落构建中的相对作用具有明显的空间尺度依赖性(Peeters et al, 2004; Gan et al, 2019; Bruckerhoff et al, 2021)。通常来讲, 扩散限制在群落构建中的作用会随着研究范围变大而增强(Landeiro et al, 2012)。作为长江的一级支流, 赤水河流域较大的空间范围、山脉阻隔以及错综复杂的水系结构使得底栖动物受到扩散限制的强烈影响(Chave, 2004)。另一方面, 赤水河有着较多的被动扩散类群(如摇蚊类和寡毛类), 这些类群大多只能凭借水体、风力或借助其他动物来进行被动迁移(Besemer et al, 2013)。许多研究表明, 相较于主动扩散者, 被动扩散者更容易受到扩散限制的制约(Lester et al, 2007; Cauvy-Fraunié et al, 2015; Li et al, 2016; Li et al, 2019)。
3.3 致危因素
尽管赤水河是长江一级支流中唯一一条干流未修建水坝和水库的河流, 但在其支流仍存在不少水坝(附录2), 如桐梓河修建了近40座梯级水电站。水库及水坝的修建在改变河流健康状况的同时割裂了河流的完整性(Cheng et al, 2015), 改变了河流的水文节律, 使得一些喜流水环境的水生昆虫(如蜉蝣目和毛翅目)减少或者消失, 大量喜静水的物种(如摇蚊类和寡毛类)显著增加。
赤水河部分乡镇的生活污水未经处理就直接排入干流及部分支流(附录2)。导致赤水河水体营养盐(TN、TP、NH4+-N)增加和透明度降低。在检测出的关键环境因子中(表5, 图6), 包含了表征水体营养程度的环境因子NH4+-N, 可能与流域内生活污水及生活垃圾的排放有关。铜车河因硫铁矿、硫磺矿及煤炭开采而受到干扰(附录2), 硫磺矿渣大量堆积危害了矿区环境, 直接威胁到赤水河乃至长江上游的水质, 同时采矿业改变了赤水河的底质, 使底栖动物失去了避难所, 造成底栖动物多样性的下降。酿酒业作为赤水河流域的支柱产业, 为当地带来了可观的经济效益, 但沿江众多酒厂大量取水酿酒, 使得赤水河流量降低, 同时白酒工业产生的工业污水和生活污水的无序排放加剧了河水污染(杨丽芳, 2014)。
3.4 保护对策
影响赤水河底栖动物群落结构的环境因子如底质类型、流速、溶解氧和NH4+-N等与流域的人类活动如采矿业、酿酒业和旅游业快速大量发展、沿岸带无节制的土地开发和利用、支流梯级水电站的建设、生活污水、生活垃圾的大量排放和堆积以及外来入侵种的影响等息息相关。针对此, 应毫不动摇地坚持退耕还林工程(冉景丞和蒙文萍, 2018), 保护河流沿岸带植被自然景观; 阻止生活污水和工业污水偷排入河流, 对其进行定点无害化的处理; 相关部门应管控合法达标的酒厂, 整治非法违规酒厂, 在底栖动物资源丰富的地区应适量采水; 加强旅游环境保护知识的宣传, 提高人们的环境保护意识; 提高对底栖动物多样性重要性的认知, 为保护工作提供更坚实的基础; 针对福寿螺的入侵泛滥应采用生物防治(如稻鸭共育技术)和物理防治(如在产卵高峰期捣毁卵块、破坏其产卵场所)等多种措施共同作用。但由于目前的防控方法很难将福寿螺彻底根除, 少量的福寿螺就有造成暴发的可能, 因此在进一步优化防治技术的同时, 也应当建立有效的预测和风险评估机制, 最终建立有效的防控体系, 彻底根除福寿螺危害。
附录 Supplementary Material
附录1 赤水河大型底栖动物物种名录
Appendix 1 List of benthic macrobenthos in the Chishui River
附录2 赤水河人为干扰情况
Appendix 2 Situation of Human disturbance in the Chishui River basin
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PMID:17960424
[本文引用: 1]
The objective of this study was to explore the altitudinal decrease in local richness of stream macroinvertebrates. I compared the explicatory power of a mid-domain effect (MDE) null model and a number of selected contemporary ecological variables, with a special emphasis on the altitude-mediated decrease in temperature and oxygen availability as possible driving factors for the observed pattern. Benthic macroinvertebrates were sampled at 30 stream sites between 2,600 and 4,000 m a.s.l. in northern Ecuador. All four measures of local richness (total number of taxa, taxa in Surber samples, Fisher's alpha index and rarefied richness) decreased with increasing altitude. The MDE null model, water temperature and dissolved oxygen also decreased with altitude, while other measured variables were uncorrelated with altitude. Minimum oxygen saturation had the highest explanatory power of the density-corrected Fisher's alpha and rarefied richness (R = 0.48 and 0.52, respectively), but also minimum temperature (R = 0.48 and 0.41) and the MDE null model (R = 0.48 and 0.46) correlated significantly. Multiple regression analyses using several predictive variables showed that oxygen saturation had the greatest and only significant effect on density-corrected richness. The relationship between richness and oxygen corrected for the effect of altitude (using analyses of double residuals) was significant, whereas that of richness versus temperature was not. The results indicate that the decrease in richness with increasing altitude is mainly caused by a decrease in oxygen saturation rather than by a decrease in temperature. Levels of oxygen saturation such as those found at high altitudes do not appear to be lethal to any species, but could affect macroinvertebrates through long-term, sub-lethal effects. I suggest that low oxygen availability may limit biodiversity at high altitudes not only in the aquatic, but also in the terrestrial environment.
Diversity Pattern and Environmental Assessment of Macroinvertebrates in Rivers in Central and Western China
中西部河流大型无脊椎动物多样性格局及其环境评价
Macroinvertebrate community structure and bioassessment of water quality in Pohe stream, one of the headwater streams of Huanggai Lake water-network
黄盖湖水系河源区——皤河大型无脊椎动物群落与水质评价
The roles of dispersal limitation and environmental conditions in controlling caddisfly (Trichoptera) assemblages
DOI:10.1111/fwb.2012.57.issue-8 URL [本文引用: 1]
The relationship between dispersal ability and geographic range size
DOI:10.1111/j.1461-0248.2007.01070.x
PMID:17594430
[本文引用: 1]
There are a variety of proposed evolutionary and ecological explanations for why some species have more extensive geographical ranges than others. One of the most common explanations is variation in species' dispersal ability. However, the purported relationship between dispersal distance and range size has been subjected to few theoretical investigations, and empirical tests reach conflicting conclusions. We attempt to reconcile the equivocal results of previous studies by reviewing and synthesizing quantitative dispersal data, examining the relationship between average dispersal ability and range size for different spatial scales, regions and taxonomic groups. We use extensive data from marine taxa whose average dispersal varies by seven orders of magnitude. Our results suggest dispersal is not a general determinant of range size, but can play an important role in some circumstances. We also review the mechanistic theories proposed to explain a positive relationship between range size and dispersal and explore their underlying rationales and supporting or refuting evidence. Despite numerous studies assuming a priori that dispersal influences range size, this is the first comprehensive conceptual evaluation of these ideas. Overall, our results indicate that although dispersal can be an important process moderating species' distributions, increased attention should be paid to other processes responsible for range size variation.
A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers
Species diversity and driving factors of benthic macroinvertebrate assemblages in the middle and lower reaches of the Yarlung Zangbo River
DOI:10.17520/biods.2021431
[本文引用: 1]
<p id="p00005"><strong>Aims:</strong> The Yarlung Zangbo River basin supports rich and unique biological resources, which makes it a global biodiversity hotspot. However, surveys on benthic macroinvertebrates in this river basin are far from sufficient. To fill this gap, this study focused on the middle and lower reaches of the Yarlung Zangbo River, where macroinvertebrates were sampled from the main stream and tributaries in autumn (October 2015) and spring (March 2016). <br><strong>Methods:</strong> One-way ANOVA was used to examine the differences of abundance, biomass and ecological indices between the main stream and tributaries. Canonical analysis of principal coordinates (CAP) was adopted to test if community structures varied among different site groups. Canonical correspondence analysis (CCA) was Applied to identify the key environmental factors that significantly influence the community structure of macroinvertebrates during each season. <br><strong>Results:</strong> A total of 270 species were identified, belonging to 5 phyla 8 classes 20 orders and 92 families. The community included 246 aquatic insects, 14 oligochaetes, 4 mollusks and 6 others. The average density was 939.1 ind./m<sup>2</sup>, and the average biomass was 5.44 g/m<sup>2</sup>. 184 and 214 macroinvertebrate species were collected in spring and autumn, respectively. The dominant species were aquatic insects that preferred clean and cold water, including <i>Baetis </i>sp., <i>Baetiella </i>sp., <i>Simulium </i>sp., <i>Micropsetra</i> sp. and <i>Brachycentrus </i>sp. The community structure, density and diversity indices exhibited significant temporal and spatial variation, and the diversity in tributaries was significantly higher than that of the main stream. CCA analysis indicated that environmental factors including altitude, velocity, river width and substrate types were key factors structuring the benthic community in the Yarlung Zangbo River. <br><strong>Conclusion:</strong> The variation in community structure and diversity pattern were mainly derived from the variable climate types and geological barriers in the Grand Canyon area. This study can provide important basis and reference for macroinvertebrate diversity assessments and environmental monitoring in the Yarlung Zangbo River basin.</p>
雅鲁藏布江中下游底栖动物物种多样性及其影响因素
DOI:10.17520/biods.2021431
[本文引用: 1]
雅鲁藏布江流域维系着丰富而独特的生物资源, 是全球生物多样性研究的热点区域。然而, 该流域底栖动物多样性的调查却极不充分。本文于2015年10月和2016年3月对雅鲁藏布江干流(朗县至墨脱段)和主要支流的底栖动物进行了调查, 并采用单因素方差分析(one-way ANOVA)和典范对应分析(canonical correspondence analysis)等对群落多样性格局进行解析。共采集到底栖动物270种, 隶属于5门8纲20目92科, 包括昆虫纲246种, 寡毛纲14种, 腹足纲4种, 其他动物6种。春季和秋季分别采集到底栖动物184种和214种, 优势种均以喜清洁和冷水的水生昆虫为主, 包括四节蜉属一种(Baetis sp.)、花翅蜉属一种(Baetiella sp.)、蚋属一种(Simulium sp.)、小突摇蚊属一种(Micropsetra sp.)和短石蛾属一种(Brachycentrus sp.)等。全流域平均密度为939.1 ind./m<sup>2</sup>,sp.)等。平均生物量为5.44 g/m<sup>2</sup>。底栖动物的物种组成、密度和多样性在季节和区域之间存在一定差异, 支流的多样性显著高于干流。典范对应分析显示, 海拔、流速、河宽和底质类型等环境因子是影响雅鲁藏布江流域底栖动物群落结构的关键环境因素, 而大峡谷地区多变的气候类型和地理阻隔是造成群落变化的根本原因。本研究可为雅鲁藏布江流域底栖动物多样性评估和环境监测提供重要的基础和参考。
Disentangling the effects of dispersal mode on the assembly of macroinvertebrate assemblages in a heterogeneous highland region
DOI:10.1086/701755 URL [本文引用: 2]
Ecological squeezing effect of the invasive species Pomacea canaliculata on the indigenous species Bellamya purificata
入侵种小管福寿螺对本土物种梨形环棱螺的生态挤压作用
Response of stream macroinvertebrate assemblages to erosion control structures in a wastewater dominated urban stream in the southwestern U.S
DOI:10.1007/s10750-010-0550-y URL [本文引用: 1]
The ordination and classification of macroinvertebrate assemblages in the catchment of the River Wye in relation to environmental factors
DOI:10.1111/fwb.1987.17.issue-3 URL [本文引用: 1]
Benthic macroinvertebrate community structure in relation to food and environmental variables
DOI:10.1023/B:HYDR.0000026497.48827.70 URL [本文引用: 1]
Variation partitioning of species data matrices: Estimation and comparison of fractions
DOI:10.1890/0012-9658(2006)87[2614:vposdm]2.0.co;2
PMID:17089669
[本文引用: 1]
Establishing relationships between species distributions and environmental characteristics is a major goal in the search for forces driving species distributions. Canonical ordinations such as redundancy analysis and canonical correspondence analysis are invaluable tools for modeling communities through environmental predictors. They provide the means for conducting direct explanatory analysis in which the association among species can be studied according to their common and unique relationships with the environmental variables and other sets of predictors of interest, such as spatial variables. Variation partitioning can then be used to test and determine the likelihood of these sets of predictors in explaining patterns in community structure. Although variation partitioning in canonical analysis is routinely used in ecological analysis, no effort has been reported in the literature to consider appropriate estimators so that comparisons between fractions or, eventually, between different canonical models are meaningful. In this paper, we show that variation partitioning as currently applied in canonical analysis is biased. We present appropriate unbiased estimators. In addition, we outline a statistical test to compare fractions in canonical analysis. The question addressed by the test is whether two fractions of variation are significantly different from each other. Such assessment provides an important step toward attaining an understanding of the factors patterning community structure. The test is shown to have correct Type I. error rates and good power for both redundancy analysis and canonical correspondence analysis.
The measurement of diversity in different types of biological collections
DOI:10.1016/0022-5193(66)90013-0 URL
Spatial Pattern, Formation Mechanism and Temporal Dynamics of Fish Community in Chishui River
赤水河鱼类群落空间格局、群聚形成机制及时间动态研究
Discussion on ecological protection strategy of Guizhou Chishui River
贵州赤水河流域生态保护策略探讨
The effects of environment factors on community structure of benthic invertebrate in rivers
环境因子对河流底栖无脊椎动物群落结构的影响
A mathematical theory of communication
DOI:10.1002/bltj.1948.27.issue-3 URL [本文引用: 1]
Diversity of Macroinvertebrates and Health Assessment of River Ecosystem in Chishui River
赤水河大型无脊椎动物多样性与河流生态系统健康评价
Assessment of macrobenthos biodiversity and potential human-induced stressors in the Ganjiang River system
DOI:10.17520/biods.2018296
[本文引用: 1]
The Ganjiang River is the seventh-largest first-level tributary of the Yangtze River, and knowledge is limited about the river’s macrobenthos assemblages. Here, we carried out a comprehensive assessment of macrobenthos species diversity in the river system, and then identified the potential drivers of the observed community patterns based on combined datasets of available historical records and field investigations from 2016-2017. A total of 330 species have been recorded to date, including 138 from the historical record and an additional 267 from the 2016-2017 investigations. In particular, this river network harbors a high array of mollusk diversity, with 17 gastropods and 31 bivalves endemic to China while 32 molluscs endemic to China were recorded in the 2016-2017 investigations. The dominant species in the Ganjiang River can tolerate pollutants. The density, biomass and richness index of branches of midstream were all higher than those of main stream, branches of the upstream and branches of the downstream. The canonical correspondence analysis (CCA) showed that five environmental factors (substrate, sand-excavating, altitude, turbidity, velocity) and four spatial factors (PCNM1, PCNM11, PCNM12, PCNM15) were the key drivers structuring macrobenthos community variation. The variation partitioning analysis indicated that the environmental factors had a stronger effect on macrobenthos communities than the spatial factors. This study provides useful information to enhance the conservation of benthic biodiversity in the Ganjiang River.
赣江水系大型底栖动物多样性与受胁因子初探
DOI:10.17520/biods.2018296
[本文引用: 1]
赣江是长江的第七大支流, 孕育了极为丰富的大型底栖动物多样性, 而相关的研究明显不足。基于文献调研和2016-2017年现场调查, 本研究系统评估了赣江水系大型底栖动物多样性及其受胁因素。共记录底栖动物5门10纲27目95科204属330种(历史记录138种, 2016-2017年记录267种)。历史记录中国特有软体动物计48种(腹足类17种, 双壳类31种), 目前记录32种。优势种主要是一些耐污种和广布种。中游支流的密度、生物量和丰富度指数要高于赣江干流、上游支流和下游支流。典范对应分析结果表明, 底栖动物的分布主要受海拔、基质、流速、浊度、挖沙等环境因子以及不同尺度空间因子的驱动。偏CCA结果显示, 环境过滤对群落结构的影响高于空间过程。本研究结果可为赣江流域水生生物的保护和管理提供科学依据。
Community variation of macrozoobenthos and bioassessment of Dongqian Lake, Ningbo
宁波东钱湖大型底栖动物群落动态及水质生物学评价
The current situations of Baijiu (liquor) industry in Chishui River Basin in Guizhou and analysis of the approaches to its sustainable development
贵州赤水河流域白酒产业经济现况及可持续发展途径分析
A Taxonomic Study on the Larvae of Heteroptera in China (Insecta: Odonata)
中国差翅亚目稚虫的分类学研究(昆虫纲: 蜻蜓目)
Study on the categories of soil erosion of Chishui River Basin and corresponding measures for soil and water conservation
赤水河流域水土流失类型区划分及防治对策
Habitat suitability of macroinvertebrates in the Taizi River basin, northeast China
太子河流域大型底栖动物栖境适宜性
