Invertebrate fauna of ephemeral streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand

The invertebrate fauna of five ephemeral forest streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand was assessed in January 2014. Low summer flows restricted benthic sampling largely to pools that would, during periods of ‘normal’ flow, be main-channel riffle/run habitat. Additionally, adult stages of aquatic insects were sampled by light trapping. Fifty-three aquatic species/morphospecies were recorded during the study, including 25 new records, bringing total island species richness to 65. The fauna was dominated by Ephemeroptera and Trichoptera; species richness of Plecoptera and Diptera was low, and only single species of Mollusca and Crustacea were recorded. Species found were either common with broad New Zealand distributions, or species restricted to the North Island. No species was endemic to the island. Faunal comparisons with adjacent mainland streams indicated the island had similar assemblages of core taxa, but generally lower species richness, likely resulting from physiographic differences found there.2014年1月，针对新西兰北部豪图鲁奥托伊岛（Hauturu-o-Toi）/小巴里尔岛（Little Barrier Island）上的5条季节性森林溪流的无脊椎动物区系（invertebrate fauna）开展了调查评估。夏季径流量偏低，导致底栖生物采样（benthic sampling）只能集中于池沼区域——在常规流量时期，这类区域本应属于主河道的浅滩/缓流生境（riffle/run habitat）。此外，研究采用灯光诱捕法（light trapping）采集水生昆虫的成虫样本。本次调查共记录到53种水生类群/形态种（morphospecies），其中25种为该岛的新分布记录，至此该岛的水生类群总物种丰富度（species richness）升至65种。该动物区系以蜉蝣目（Ephemeroptera）和毛翅目（Trichoptera）为优势类群；襀翅目（Plecoptera）和双翅目（Diptera）的物种丰富度较低，软体动物门（Mollusca）与甲壳动物亚门（Crustacea）仅各记录到1个物种。所记录的类群要么是在新西兰全境广泛分布的常见类群，要么是仅分布于北岛的狭布类群。本次调查未发现该岛特有的物种。将该岛溪流的动物区系与邻近大陆溪流进行比对后发现，二者的核心类群（core taxa）组成相似，但该岛的物种丰富度整体更低，这一差异大概率由当地的地形地貌（physiographic）差异所导致。