Abstract
1. Population dynamics and production of Jesogammarus annandalei, an endemic amphipod in Lake Biwa, were examined from April 1997 to June 1998. The life cycle of this species was 1 year with the new generation beginning 7 in early autumn. They preferred low temperature (<12 °C) and their spatial distribution varied seasonally and accordingly. 2. In deep water, the abundance of J. annandalei ranged from 200 to 63 000 m-2 and decreased towards summer and the biomass (0.01 - 3.6 g C m-2) was on average comparable that of zooplankton. The density was much higher than that recorded by a study conducted 35 years ago. 3. Individual growth rate of this amphipod was high in winter and spring but decreased in summer. Annual production of J. annandalei (6.2 g C m-2 year-1) was only 2% of primary production but was at the higher end of the range reported for amphipods in oligo- and mesotrophic lakes. 4. These results are consistent with the view that Lake Biwa is becoming more eutrophic, with a consequent decrease in the abundance of predatory fish in the profundal zone.
Original language | English |
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Pages (from-to) | 1935-1943 |
Number of pages | 9 |
Journal | Freshwater Biology |
Volume | 47 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2002 Oct 1 |
Externally published | Yes |
Keywords
- Amphipod
- Endemic species
- Large lake
- Macrobenthos
- Secondary production
ASJC Scopus subject areas
- Aquatic Science