The scaling of parasite biomass with host biomass in lake ecosystems: are parasites limited by host resources?

摘要: The standing crop biomass of different populations or trophic levels reflects patterns energy flow through an ecosystem. contribution parasites to total is often considered negligible; recent evidence suggests otherwise, although it comes from a narrow range natural systems. Quantifying how local parasite biomass, whether that single species assemblage sharing the same host, varies across localities with host population critical determine what constrains populations. We use extensive dataset on all free-living and parasitic metazoan multiple sites in New Zealand lakes measure test covaries biomass. In lakes, trematodes had highest combined among taxa, ranging about 0.01 0.25 g m−2, surpassing minor taxa. Unlike findings other studies, life stage contributing most trematode was metacercarial second intermediate not sporocysts rediae within snail first hosts, possibly due low prevalence small sizes. For species, we found no relationship between for either juvenile adult nematodes. contrast, stages biomasses correlated positively those their hosts. assemblages strong relationships supported. these host–parasite relationships, scaling factor (slope log-log space) may be making full available resources. Host appear capable supporting little more open expansion existing invasion by new ones.