Managing and Rehabilitating Ecosystem Processes in Regional Urban Streams in Australia

Abstract

Urbanization is acknowledged as one of the most severe threats to stream health, spawning recent research efforts into methods to ameliorate these negative impacts. Attention has focused on streams in denselypopulated cities but less populous regional urban centres can be equally prone to some of the same threats yet might not meet the conventional definitions of urban. Several recent reviews have identified the changes to streams that occur during urbanization but they note that few ecological studies have explored ecosystem-level responses, typically focusing instead on state variables such as invertebrate abundance. In many regional urban streams, changes to the extent of impervious drainage have implications for their hydrology and channel morphology but the influence of these changes on fundamental ecosystem processes of leaf litter breakdown and transport compared with those in nearby rural streams are poorly known. The widespread practice of planting exotic trees along riparian zones and street margins draining into urban streams further exacerbates the disruption of natural organic matter dynamics. The combination of seasonal leaf fall by exotic species and the altered drainage patterns through urbanization in Armidale, a regional town in New South Wales, Australia, resulted in contrasting patterns of benthic organic matter storage over 18 months compared to nearby reference and rural streams. Macroinvertebrate detritivore densities were low in the urban stream, implying disruption of the usual biological pathways of leaf breakdown. Understanding the interactions of hydrology, drainage pattern, leaf input and biological attributes of a stream is crucial for managers trying to restore stream ecosystem services without incurring public concern about the appearance of regional urban streams.

Biodiversity, functional roles and ecosystem services of groundwater invertebrates

“…Functional feeding groups could also be considered as ESPs, essential in the ecosystem service of organic matter decomposition. Loss of 'shredders', for example, would inhibit removal of accumulations of leaf litter in streams with concomitant impacts on water quality and reduction of a crucial source of carbon for the stream foodweb, as observed in some streams where urbanisation has markedly reduced shredder biodiversity and densities (Miller and Boulton 2005). Functional classifications of groundwater invertebrates (e.g.…”

Effects of Land Use Types on Community Structure Patterns of Benthic Macroinvertebrates in Streams of Urban Areas in the South of the Korea Peninsula

“…Ecological degradation of stream drainage was especially affected by urbanization, causing the so-called 'urban stream syndrome' [3]. The symptoms of the urban stream syndrome have been broadly characterized in various fields, including physicochemical and ecological processes such as hydrology [3,4], biodiversity conservation [5][6][7], and ecosystem processes [8,9].…”

Setting Goals and Measuring Success: Linking Patterns and Processes in Stream Restoration

“…Ecosystem processes, such as the processing of organic matter and transformation and retention of nutrients have been largely ignored in urban stream research until recently (Paul & Meyer, 2001). Many urban streams in temperate Australia have experienced a proliferation of exotic, deciduous trees within their catchments and along waterways (Miller & Boulton, 2005). Leaves from exotic deciduous trees represent not only a potential 'unnatural' source of DOC, but also a many-fold increase in the total volume of litterfall within a short period relative to native riparian species (Miller, unpublished data).…”

“…Leaves from exotic deciduous trees represent not only a potential 'unnatural' source of DOC, but also a many-fold increase in the total volume of litterfall within a short period relative to native riparian species (Miller, unpublished data). As DOC leached from leaf litter is often the major source of carbon for stream food webs (Findlay & Sinsabaugh, 1999), an alteration to the quantity and quality of litter entering the stream can have profound effects on ecosystem productivity and trophic dynamics (Miller & Boulton, 2005). A technique has been developed which uses the activity of bacterial extracellular enzymes to link bacterial productivity to the concentrations and classes of available DOC.…”