沿岸域における水鳥類のベントス採餌量推定 Consumption of Benthic Organisms by Birds in Coastal Ecosystems
As consumers, waterfowl play an important role in the regulation of benthic community structure and nutrient dynamics of coastal ecosystems. In this study, the amount of benthic organisms consumed by birds in a brackish lake, Lake Akkeshi in northeastern Japan, was estimated from direct observation and from energy requirement equations. The 19 avian species observed foraging in the study site were categorized into four guilds: predators foraging on other avian species, piscivores, invertebrate feeders foraging mainly on bivalves, and herbivores consuming seagrass and seaweed. Each guild comprised from one to three tropho-species, three of which were investigated in detail. The dominant piscivore, the grey heron, consumed about 100 kg of fish per day in spring and summer. The dominant invertebrate feeders, diving ducks, consumed about 6500 kg and 2000 kg of clams per day in autumn and winter, respectively. Herbivorous ducks consumed about 9000 kg of seagrass and seaweed per day in autumn and about 900 kg in winter. Nearly all of these amounts estimated from the observations were very similar to those estimated indirectly from energy requirement equations. Even when the agreement was very similar, however, some of the assumptions used for the energy requirement equations did not correspond to the actual energetic requirements of birds in the field. We conclude, therefore, that although the amount of benthic organisms consumed by birds can be estimated using energetic requirement equations, selection of a particular energetic requirement equation must take into account the field condition of the birds.
- 日本ベントス学会誌 = Japanese journal of benthology
日本ベントス学会誌 = Japanese journal of benthology 60, 12-22, 2005-07-28
JAPANESE ASSOCIATION OF BENTHOLOGY