New Zealand Journal of Marine and Freshwater Research abstracts
Consumption of aquatic bryophytes by alpine stream invertebrates in New Zealand
ALASTAIR M. SUREN*
MICHAEL J. WINTERBOURN
Department of Zoology
University of Canterbury
Private Bag, Christchurch, New Zealand
*Present address: Hydrology Centre, DSIR Marine and Freshwater, Department of Scientific and Industrial Research, P. O. Box 22-037, Christchurch, New Zealand
Abstract Gut contents of 23 invertebrate taxa that dwell among bryophytes in two small New Zealand alpine streams with different riparian vegetation were examined. Bryophyte fragments were found in guts of 14 taxa, but only the tipulid
Limonia hudsoni and the oeconesid caddisflies
Zelandopsyche ingens and
Oeconesus similis commonly consumed bryophytes. Bryophyte-dwelling animals consumed more periphyton at the unshaded site or riparian vegetation at the shaded site than did animals dwelling amongst gravels. Stable carbon isotope ratios were compared between selected animals and plants, and indicated that animals in the unshaded site relied primarily on autochthonous detritus, whereas animals from the shaded site relied on allochthonous detritus. An indication of the food value of five bryophytes
(Fissidens rigidulus, Cratoneuropsis relaxa, Bryum blandum, Plagiochila retrospectans, and
Hepa-tostolonophora paucistipula) and of seven common riparian plants
(Chionochloa pallens, C. flavescens, Hebe subalpina, H. odora, Nothofagus solandri var.
cliffortioides, Blechnum capense, and
Marsippo-spermwn gracile) was obtained by comparing their proximate biochemical composition. This revealed that bryophytes contained more refractory and indigestible compounds than riparian plants and represented a less nutritious food source for animals. Avoidance of bryophyte tissues thus reflects a combination of the presence of alternative foods and their low nutritional value; bryophytes may also contain antifeedant compounds.
Keywords aquatic bryophytes; invertebrates; feeding; bryophagy; stable carbon analysis; autochthonous; allochthonous; food value; antiherbivore compounds
New Zealand Journal of Marine and Freshwater Research, 1991, Vol. 25: 331-343 0028-8330/2503-O331 $2.50/0 © Crown copyright 1991
Received 24 May 1991; accepted 2 August 1991
PDF file of entire paper: medium quality (1008K); (scanned from paper original: notes about this process)
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