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Communication at the NABS Annual meeting, Keystone, 2000
(74) RIPARIAN DETRITUS IN A HAWAIIAN STREAM ECOSYSTEM: A COMPARISON OF DROUGHT AND POST-DROUGHT DYNAMICS.
S.T. Larned1. 1Hawaii Institute of Marine Biology, Kaneohe, Hawaii, 96744, 2Coastal Ecology Branch, United States Environmental Protection Agency, Newport, Oregon 97365
Input, standing crop and export of CPOM was monitored in a low elevation forested stream on the windward coast of the Island of Hawaii. The study was conducted during and after a drought associated with the 1997-1998 El Niņo/Southern Oscillation. Discharge was reduced by 70% during the drought and no spates occurred. Under normal flow conditions, > 20 spates/year occur in windward Hawaiian streams. During the drought, CPOM exported to the stream's estuary was 8% of the mean input rate; following the drought, export increased to 40% of input. Leaf and stem transport rates during the drought were 2 - 10% of transport rates following the drought. Reduced export and transport during the drought suggested that CPOM availability to detritivores had increased. CPOM input increased following the drought, however, and differences in CPOM standing crops and turnover times during and after the drought were not significant. Consequently, CPOM availability did not change substantially. Litter bag experiments indicated that detritivores did not affect leaf processing rates, but detritivores consumed fruit rapidly. These results, and high rates of detrital fruit input, suggest that fruit is an important allochthonous food in low elevation Hawaiian streams.
Presented at 9:00 AM on Tuesday, May 30, 2000 in Food Webs and Communities I
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