Patch- and reach-scale dynamics of a macrophyte-invertebrate system in a New Zealand lowland stream

Citation
Kj. Collier et al., Patch- and reach-scale dynamics of a macrophyte-invertebrate system in a New Zealand lowland stream, HYDROBIOL, 392(2), 1999, pp. 89-97
Citations number
29
Categorie Soggetti
Aquatic Sciences
Journal title
HYDROBIOLOGIA
ISSN journal
00188158 → ACNP
Volume
392
Issue
2
Year of publication
1999
Pages
89 - 97
Database
ISI
SICI code
0018-8158(1999)392:2<89:PARDOA>2.0.ZU;2-J
Abstract
Abundant growths of macrophytes are a common feature of streams in open low land areas of New Zealand during summer, but the values of these to aquatic biota are poorly understood. We studied the temporal dynamics of, and asso ciations amongst, elements of a macrophyte-invertebrate system to provide a n improved information base for lowland stream management. The biomass of m acrophytes increased significantly over the four quarterly sampling occasio ns from 43.8 g m(-2) in June to 370.8 g m(-2) in March; biomass was dominat ed by Egeria densa on all dates, except in December when Potamogeton crispu s was dominant. We did not detect strong associations between epiphyton bio mass and invertebrate abundance in our study, but this may reflect the fact that we sampled loosely-adhering epiphyton on young, surface-reaching shoo ts whereas invertebrates were collected from macrophytes growing through th e water column. Density of some invertebrate species per gram dry weight of plant material varied by macrophyte type, with the chironomids Tanytarsus vespertinus and Naonella forsythi displaying positive correlations with Ege ria and Potamogeton biomass, respectively. The shrimp Paratya curvirostris accounted for 50% of phytophilous invertebrate biomass, with Chironomidae t he only other group to comprise more than 9%. Abundance of total phytophilo us invertebrates displayed a positive linear relationship with macrophyte b iomass in a sample (0.1 m(2)), and a humped relationship with species richn ess, such that highest numbers of taxa occurred at macrophyte biomass level s around 400 g dw m(-)2. Our study suggests that intermediate macrophyte bi omass levels are likely to enhance macroinvertebrate biodiversity in sandy- bottomed lowland streams.