Effects of Fish, Water Depth, and Predation Risk on Patch Dynamics in a North-Temperate River Ecosystem
Effects of Fish, Water Depth, and Predation Risk on Patch Dynamics in a North-Temperate River Ecosystem
复制标题
鱼类、水深和捕食风险对北温带河流生态系统斑块动态的影响
DOI：
10.2307/3546606
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发表时间：
1997
期刊：
影响因子：
3.4
通讯作者：
W. J. Matthews
中科院分区：
文献类型：
--
作者：
F. Gelwick;M. Stock;W. J. Matthews
水深的时空变化影响了被捕食鱼类及其捕食者对栖息地的利用，形成了具有不同底栖生态系统特性的斑块的动态马赛克。在美国俄克拉何马州塔勒夸附近的一条高地河流的两个水池中建造了12个4,6米2的围栏（5毫米网），对鱼封闭或开放。鱼类效应主要是底栖藻类Campostoma anomalum、C. oligolepsis和Notrois nubilus，它们占河段鱼类丰度的60%和底栖鱼类的83%。此外，这些鱼的平均每小时底栖有机物去除量（4.4 gm -2 h -1无灰干质量）超过了封闭围栏的平均每日积累量（3.7 gm -2）。在开放的围栏和非封闭的河流中，鱼类保持相对无粉砂的放牧状态，直到在一个水池中占主导地位的大型鱼类放弃栖息地，当水变浅（<28厘米）时，它们的捕食风险变得至关重要。在封闭的围栏和鱼类放弃的区域，底栖藻类生物量最初增加，但随后明显地在藻类基质中积累淤泥，最终在基质中脱落并重新生长。蓝绿色和绿藻在有鱼的地区占主导地位。与基质完整的围栏相比，再生藻封闭围栏的生物量净初级生产力和有机质百分比更高。无脊椎动物丰度在有少量脱落斑块的封闭围栏中高于有鱼类的开放围栏，但在有再生斑块的封闭围栏和有鱼类废弃的开放围栏中相似，无脊椎动物捕食者和采集者在基质完整的封闭围栏中占优势，中底栖颗粒物有机物（BPOM） （157 ~ 507 μm）百分比较高；开放式围栏中以捕集过滤器和刮刮器为主，超细BPOM （0.44 ~ 40 μm）含量较高。在封闭的围栏里，有一块块重新生长的藻类，以及被鱼抛弃的开放围栏里，主要是刮刀和采集者。
Spatial and temporal variation in water depth affected habitat use by prey fish and their predators, generating a dynamic mosaic of patches with different benthic ecosystem properties. Twelve 4,6-m 2 pens (5-mm mesh), closed or open to fish, were built in two pools of an upland river near Tahlequah, Oklahoma, USA. Fish effects were attributed primarily to the benthic algivores Campostoma anomalum, C. oligolepsis and Notrois nubilus, which comprised 60% of fish abundance in the reach and 83% of benthic fish. Furthermore, mean hourly removal of benthic organic matter (4.4 gm -2 h -1 ash-free dry mass) by these fish exceeded the mean daily accumulation (3.7 gm -2 ) in closed pens. Fish maintained a relatively silt-free grazed epilithon in open pens and unenclosed river, until large fish that predominated in one pool abandoned habitats where their predation risk became critical as water became shallow (<28 cm ). In closed pens and areas abandoned by fish, benthic algal biomass initially increased, but then visibly accumulated silt in an algal matrix that eventually sloughed and regrew in patches of substrata. Blue-green and green algae like that in areas with fish predominated in regrown patches. Closed pens with regrown algae had higher biomass-specific net primary productivity and higher percentage of organic matter than ones with an intact matrix. Invertebrate abundance was higher in closed pens with few sloughed patches than in open pens with fish, but similar in closed pens with regrown patches and open pens abandoned by fish, Invertebrate predators and collector-gatherers predominated in closed pens with an intact matrix and higher percentage of medium (157-507 μm) benthic particulate organic matter (BPOM); collector-filterers and scrapers predominated in open pens, which had higher percentage of ultrafine (0.44-40 μm) BPOM. Assemblages in closed pens with patches of regrown algae and open pens abandoned by fish were dominated by scrapers and collector-gatherers.