The Autecology of Eudiaptomus cf drieschi (Poppe & Mrazek 1895 ...

Reproduction is continuous throughout the period that E. drieschi occurs in the
water column, as seen by the presence of nauplii, copepodites, and both sexes in all
samples. Number of eggs per clutch varies greatly (8-26). The highest number of eggs
per female occurs in Jan./Feb. (16-22). (One female, sampled in February, was found
carrying a clutch of 66 eggs.) The number of females carrying eggs increases in spring
with an average clutch size of 12-18. Total annual biomass averaged between 1-1.4
mg/ l (wet weight). The greatest biomass occurred in the spring with values reaching
2.01 mg/l (wet weight). Figure 11 shows the percentage of egg bearing females present
in the water column plotted with average water temperature (r 2 = 0.56, P5) in relation to Lake
Temperature, 1997 - 98
Females with eggs (%)
100%
80%
60%
40%
20%
0%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
28
26
24
22
20
18
16
14
Lake Temperature
12
10
Figure 11: Seasonality of egg-carrying adult female E. drieschi (percent of total
females) versus lake temperature (1997-1998)
There was a tendency for individuals to occur at greater depths as the seasons
progressed. By early to mid summer, very low numbers of organisms were found in the
upper water column (