copepodite stages (∼5 days), these issues are less important. There will be strong
changes in length, changes that can be checked at several time intervals. Hopcroft et
al. (1998) made multiple such estimates in Jamaican coastal waters at 28°C for five
calanoid and three cyclopoid species:
SPECIES g ± SE (N) (d−1) AT KINGSTON HARBOR
(MORE FOOD)g ± SE (N) (d−1) AT LIME CAY
(LESS FOOD)
Acartia spp. 0.81 ± 0.17 (6) 0.59 ± 0.13 (4)
Centropages velificatus — 0.85 ± 0.15 (2)
Parvocalanus crassirostris0.73 ± 0.06 (13) 0.69 ± 0.12 (6)
Paracalanus aculeatus — 0.78 ± 0.06 (15)
Temora turbinata 0.93 ± 0.10 (5) 0.72 ± 0.23 (8)
Corycaeus spp. — 0.23 ± 0.04 (6)
Oithona nana 0.65 ± 0.05 (8) 0.46 ± 0.03 (4)
Oithona simplex 0.35 ± 0.04 (8) 0.35 ± 0.03 (7)(^) The last three are cyclopoids, which grow relatively slowly. The others (calanoids)
all have rates at or greater than one doubling in mass per day. That is realistic for
small, tropical copepods, since they can go from egg to adult in less than 2 weeks. In
the slightly larger species like Temora, for which stage-by-stage growth can be
estimated, there can be slowing of both relative weight gain in successive stages (from
2-fold for C2/C1 vs. 1.5-fold for C5/C4) and, thus, growth rate varies despite
relatively constant stage durations. Larger copepods of more temperate areas like
Calanus finmarchicus in the North Atlantic grow at overall average rates (Campbell et
al. 2001) that vary with temperature and rations:
(^) TEMPERATUREFOOD GROWTH RATE (d−1)
12°C High 0.28
8°C High 0.21
8°C Medium0.13
8°C Low 0.09
4°C High 0.13
(^) Those are laboratory rearing data, but some field data show similar rates and
relationships: both food and temperature are determining factors for growth, which is
secondary production.
(^) There are other variants of the AC technique; for a worked example, see Renz et al.
(2008). However, most applications have severe statistical issues and suffer from
uncontrolled effects of sample sieving and unnatural maintenance of collected
animals.
(^) Boyson’s (1919) equation, given above, also referred to as Ricker’s (1946) equation,
is usually converted to symbols: