| Abstract: | We investigated the impact of abiotic factors and trout density on distribution and abundance of diaptomid copepods in high-elevation
lakes in North Cascades National Park Service Complex (NOCA), Washington, USA. The most common large diaptomid, D. kenai (mean
length = 1.88 mm), was able to persist over a wide range of abiotic factors, but the small herbivorous diaptomid, D. tyrrelli
(mean length = 1.18 mm), was restricted to shallow lakes (maximum depth < ≈ 10 m) with relatively high concentrations of total
Kjeldahl nitrogen and total phosphorous. There was a significant negative relationship between the density of D. tyrrelli
and the density of large diaptomids ( D. kenai and D. arcticus), which could imply interaction between large and small diaptomids.
The abundance of large diaptomids was significantly lower in shallow lakes with high densities of reproducing trout (> 250
fish ha-1) than in fishless lakes, in deep lakes with reproducing trout, or in lakes where trout do not reproduce and are
0periodically stocked with fry at low densities (average 179 fry a-1). In lakes where chemical conditions were suitable for
D. tyrrelli, the small diaptomid was often abundant when trout density was high and large diaptomids were either absent or
in low abundance. Our research suggests that trout density, nutrient concentration, and lake depth influence the abundance
of diaptomid copepods in high lakes in NOCA.
This revised version was published online in July 2006 with corrections to the Cover Date. |
