Can a naturally impoverished boreal Ephemeroptera, Plecoptera, and Trichoptera (EPT) fauna serve as an indicator of water quality?

Lomond, T. M. (Tammy M.) (1997) Can a naturally impoverished boreal Ephemeroptera, Plecoptera, and Trichoptera (EPT) fauna serve as an indicator of water quality? Masters thesis, Memorial University of Newfoundland.

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Abstract

Biomonitoring of small boreal water-catchments has become increasingly important for small human communities in Newfoundland, Canada. Benthic macroinvertebrate fauna are commonly used to assess conditions of water-catchments. However, Newfoundland has a very impoverished freshwater fauna due to isolation of the island from the mainland (faunal source), reduced habitat diversity and recent glaciation of the island. Questions addressed by the study were: how sensitive is this fauna to different environmental gradients, and will the fauna be useful in biomonitoring programs on the island? -- The study examined the relative diversity and abundance of the Ephemeroptera, Plecoptera and Trichoptera (EPT) component of the benthic macroinvertebrate fauna in 23 lake-outlets in six water-catchments of northeastern Newfoundland. Faunal composition and structure were related to gradients of natural and human impacted environmental variables of the sites sampled. Sixteen environmental variables were measured during May and July 1995, and May and July 1996 collection trips. -- Principal Components Analysis (PCA) of the environmental data indicated that the 23 sites represented a broad range of stream and drainage basin characteristics. This was expected from sites that ranged from highly urbanized sites to sites with little human disturbance. Concentrations of several chemicals, conductivity, and pH were correlated with disturbance on axis one. -- Analysis of the EPT data showed shifts in community structure related to chemical variables, disturbance level, and study area. Generally, EPT diversity and abundance were lower in the physically disturbed and polluted urban sites, and were highest in physically disturbed but relatively unpolluted rural sites. Principle Components Analysis also showed trends in taxa diversity and abundance. Taxa correlated with presence-absence PC-I included B. pygmaeus, B. macdunnoughi, E. prudentalis, Paraleptophlebia spp., S. vicarium, Leuctra spp., Polycentropus spp. and Platycentropus sp., which occur in a wide variety of running water habitats, but have low tolerances of disturbance (Edmunds et al. 1976; Larson and Colbo 1983; Lenat 1993; Lang and Reymond 1995). These taxa tended to be absent from the highly disturbed St. John's sites, but present at most remaining sites. Taxa correlated with relative abundance PC-II were H. sparna and Chimarra sp., which have low tolerances to pollution (Bargos et al. 1990; Lenat 1993). These taxa had low abundances at St. John's sites. Therefore, it was concluded that the impoverished EPT fauna of Newfoundland can serve as an indicator of water quality.

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