Longitudinal patterns in benthic communities in an urban stream under restoration

Abstract

Okeover Stream, on the University of Canterbury campus in Christchurch, New Zealand, has been the subject of restoration efforts since 1998. Our study focused on quantifying the response of this urban stream to current restoration efforts. Initially, physico-chemical conditions and biological communities at three sites along the Okeover Stream were compared with three physically similar sites on each of nearby Waimairi Stream and Avon River. General physical and chemical parameters were similar in all streams with circum-neutral pH, specific conductivity ranging from 167 to 173 µS/cm, dissolved oxygen ranging from 9.0 to 9.2 mg/litre, low turbidity, and similar hydrological conditions. However, analysis of heavy metals in the sediment showed mean lead (Pb) communities. Taxonomic richness and caddisfly diversity increased downstream, with twice as many taxa at the most downstream site than the uppermost sampling site. In upper reaches, copper (Cu), Pb, and zinc (Zn) concentrations in sediments all exceeded ANZECC ISQG-low trigger values. Despite ongoing restoration efforts in Okeover Stream, sedimentation, the presence of high heavy metal concentrations, intermittent flows in headwaters, and possible barriers to adult recolonisation seem to be having a continuing negative impact on benthic communities, especially in the headwaters.

Braided river benthic diversity at multiple spatial scales: a hierarchical analysis of β diversity in complex floodplain systems

“…The density of individuals in braided river main channels (2598 ± 703 individuals/m 2 ) was also considerably lower than that recorded for spring sources (22 982 ± 3413 individuals/m 2 ), mossy forested streams (218 400 ± 15 100 individuals/m 2 ) and urban streams (25 000 ± 8500 individuals/ m 2 ) (Suren 1991;Blakely & Harding 2005).…”

Learning about restoration of urban ecosystems: a case study integrating public participation, stormwater management, and ecological research

“…There is considerable lack of consensus regarding the effectiveness of urban ecological restoration practices and stormwater best management practices (Pennington et al 2003;Blakely and Harding 2005;Kaushal et al 2008). This is particularly true for urban riparian buffers and the benefit of riparian vegetation in urban watersheds in general.…”

Assessing Urban Impacts on Water Quality, Benthic Communities and Fish in Streams of the Andes Mountains, Patagonia (Argentina)

“…Range bars show maxima and minima, boxes are interquartile ranges (25-75%), small squares are medians (*Mann-Whitney U test, p=0.04) expected to have resulted in inputs of nutrients and sediments to the river(Suren 2000;Blakely and Harding 2005). An expansion of the treatment plant facilities is planned for 2008 and monitoring of Esquel Stream should be maintained in order to evaluate its effect on the river.…”

“…The clearing of riparian areas alongside urban rivers, including the modification and/or extirpation of streamside vegetation, can also alter the functioning of river ecosystems and disrupt fluxes of organic matter and energy (Vannote et al 1980;Cummins et al 1984). Urbanization can also result in modified flow regimes that can have major effects on stream communities (Rosenberg and Resh 1993;Death 1995) as increases in the area of impervious surfaces reduce groundwater recharge and increase run-off during storms (Suren 2000;Blakely and Harding 2005).…”