Tanya J. Blakely

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) concentrations in Okeover and Waimairi Streams exceeded ANZECC ISQG‐low trigger values (86.9 and 83.7 mg/kg, respectively), whereas Avon River sediment Pb levels (27.3 mg/ kg) were below trigger values. Benthic taxonomic richness did not differ significantly among the three streams. However, Okeover Stream community was dominated by the amphipod Paracalliopefluviatilis, whereas in Waimairi Stream and Avon River the gastropod snails Potamopyrgus antipodarum and Physella acuta were the dominant benthic fauna. A further assessment made at six sites along 1200 m of Okeover Stream showed no distinct longitudinal patterns in physical or chemical conditions, but there was a strong pattern in benthic macroinvertebrate 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.

Vertical stratification in the spatial distribution of the beech scale insect (Ultracoelostoma assimile) in Nothofagus tree canopies in New Zealand

Abstract.  1. The degree of infestation by New Zealand sooty beech scale insects (Ultracoelostoma assimile, Homoptera: Margarodidae) varies dramatically among adjacent southern beech trees (Nothofagus spp., Fagaceae), but has previously been assumed to be uniformly or randomly distributed within individual host trees. In this study, a full‐census survey was conducted from ground level to canopy level on 14 naturally occurring, canopy‐dominant red beech (Nothofagus fusca) trees (size range 38.7–107.6 cm diameter at breast height) to determine the degree of within‐tree heterogeneity in herbivore density.

Container-inhabiting Monopelopia larvae (Diptera: Chironomidae: Tanypodinae) newly recorded in New Zealand

Worldwide, Monopelopia larvae have been found to inhabit small, boggy and often acid waters including phytotelmata, billabongs, and dystrophic lakes, pools and streams. Although Tanypodinae larvae have previously been associated with phytotelmata in Auckland and Wellington, until now Monopelopia has not been reported from New Zealand. Larvae of an undescribed chironomid species belonging to the genus Monopelopia (Tanypodinae: Pentaneurini) were the most abundant insects colonising artificial waterfi lled tree-hole containers attached to red beech trees in Orikaka Ecological Area, north Westland, New Zealand. Here we describe the final-instar larva and comment on the larval diet as indicated by gut contents. In the absence of pupae and adults, larvae were attributed to Monopelopia based on the arrangement of their cephalic setae and ventral sensory pit. Gut contents of 185 final-instar larvae contained sooty mould fungi, fine detritus and animal prey items including small conspecific larvae.

Distinctive aquatic assemblages in water‐filled tree holes: a novel component of freshwater biodiversity in New Zealand temperate rainforests

Abstract.  1. Water‐filled tree holes provide important freshwater microhabitats for a wide array of aquatic species in rainforest canopies. There is extensive indirect evidence of the distinctiveness of water‐filled tree‐hole faunas, but few direct quantitative comparisons with ground‐based freshwater habitats, in either tropical or temperate regions. Here, we explore the importance of water‐filled tree holes for aquatic invertebrate species in the temperate rainforests of New Zealand. It is well documented that freshwaters in New Zealand are dominated by relatively few ubiquitous genera, many of which are habitat generalists. The key question, therefore, is whether water‐filled tree holes in New Zealand’s temperate rainforest are also dominated by habitat generalists that typically utilise ground‐level water bodies, or whether water‐filled tree holes support habitat‐specialist species.

A new species of Zecicindela Larochelle & Larivière (Coleoptera: Carabidae: Cicindelinae) from the Mackenzie Basin, New Zealand

ABSTRACT Zecicindela tekapoensis sp. nov. (Coleoptera: Carabidae: Cicindelinae) is described. It is placed in the endemic genus Zecicindela Larochelle & Larivière, even though it is the only known species in the genus with a tridentate labrum. The specimens were found on a very dry, barren terrace surface near the Tekapo River, in the Mackenzie Basin.