Abstract

Competition between aquatic organisms is heavily influenced by abiotic factors in the environment, specifically flow regime in aquatic systems. Flow regime has been shown to significantly affect the way in which a species uses the environmental resources and alterations in flow can exasperate competitive advantages by congenerics. However, little work has concentrated on the competitive outcome between native and invasive organisms as a function of flow regime. Here, we sought to uncover how competition between two crayfish species (the native virile crayfish [Faxonius virilis] and invasive rusty crayfish [Faxonius rusticus]) was affected by varying flow rates. To do this, we size-matched crayfish and quantified three separate behaviors (food use, shelter use, and fights) of crayfish in four different discharge levels (no discharge—0 cm³/s; low discharge—116 cm³/s; intermediate discharge—345 cm³/s; high discharge—450 cm³/s). We found that the number of foraging bouts was significantly (p < 0.001) influenced by discharge levels for both species, where rusty crayfish foraged more often in no and discharge. The number of times crayfish sheltered also varied between species and was significantly (p < 0.001) altered by discharge level, where rusty crayfish sheltered more often in no discharge and virile crayfish sheltered more in low and intermediate discharge levels. Similarly, the number of fights that crayfish engaged in also significantly (p < 0.001) depended upon species and discharge levels. Rusty crayfish engaged in more agonistic activities in no and high discharge levels while virile crayfish participated most often in low and intermediate discharge levels.

摘要

水生生物之间的竞争在很大程度上受到环境中非生物因素的影响，特别是水生系统中的流态。流态已被证明会显着影响一个物种利用环境资源的方式，而流量的改变会加剧同类物种的竞争优势。然而，很少有工作关注本地生物和入侵生物之间的竞争结果作为流态的函数。在这里，我们试图揭示两种小龙虾物种（本地雄性小龙虾 [ Faxonius virilis ] 和入侵的生锈小龙虾 [ Faxonius rusticus ）之间的竞争]) 受不同流速的影响。为此，我们对小龙虾进行了大小匹配，并量化了小龙虾在四种不同放电水平（无放电—0 cm 3 /s；低放电—116 cm 3 /s；低放电—116 cm ³ / ^s；中间放电—345 cm ³ /s；高放电—450 cm ³ /s）。 我们发现这两个物种的觅食次数受排放水平的显着影响 ( p < 0.001)，其中生锈的小龙虾在无排放和排放时觅食的频率更高。小龙虾庇护的次数也因物种而异，并且显着（p < 0.001) 因排放水平而改变，生锈的小龙虾在无排放时更常躲避，而强壮的小龙虾在低和中等排放水平时躲藏得更多。同样，小龙虾参与的战斗次数也显着 ( p  < 0.001) 取决于物种和排放水平。生锈的小龙虾在无和高放电水平下参与更多的竞争性活动，而有活力的小龙虾最常参与低和中等放电水平。