growth rates of neocalanus species in the northern gulf of alaska russell r. hopcroft alexei...
DESCRIPTION
Typical Life cycleTRANSCRIPT
Growth Rates of Neocalanus Species in the Northern Gulf
of Alaska Russell R. Russell R. HopcroftHopcroft
Alexei PinchukAlexei PinchukCheryl ClarkeCheryl Clarke
NeocalanusNeocalanuscristatuscristatus
NeocalanusNeocalanus plumchrusplumchrus(& flemingeri)(& flemingeri)
3 species:
Typical Life
cycle
Information Gap
Although we know overall life cycle, we lack precise or direct measurements of:
• development times• growth rate• Reproductive output
Approach1.1. Determine direct rates from freshly Determine direct rates from freshly
collected animals at collected animals at in situin situ temperatures throughout the annual temperatures throughout the annual cyclecycle• Single stage incubationsSingle stage incubations• Artificial cohortsArtificial cohorts
2.2. Determine maximal food satiated Determine maximal food satiated rates in the lab at multiple rates in the lab at multiple temperaturestemperatures
3.3. Determine reproductive outputDetermine reproductive output4.4. Compare these measured rates to Compare these measured rates to
those inferred from field observationsthose inferred from field observations
Gulf of Alaska
GLOBEC
Artificial Cohorts
(4-5 days)• Multi-stage/size Multi-stage/size
distribution is cut into distribution is cut into distinct stages/sizes distinct stages/sizes
• Incubated 100-500 Incubated 100-500 NeocalanusNeocalanus in 20-100L in 20-100L
• Change in stage Change in stage and size notedand size noted
• Development Development time and growth time and growth rate calculatedrate calculated
Freq
uenc
y
02468
101214161820
Stage 1 Stage 2Stage 3Stage 4Stage 5FemaleMale
Time 0
Prosome length (µm)0 1000 2000 3000 4000 5000
Freq
uenc
y
02468
1012141618 Time 5
Single stage incubation (4-5 days)
Prosome length (µm)0 1000 2000 3000 4000 5000
Freq
uenc
y
0
2
4
6
8
10
12
14Stage 1 Stage 2Stage 3Stage 4Stage 5FemaleMale
Initial stage1 2 3 4
Stag
e du
ratio
n (d
)
0
5
10
15
20406080
100120
Mar Gak6Mar Gak9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1
Initial stage1 2 3 4
Stag
e du
ratio
n (d
)
0
5
10
15
20406080
100120
Mar Gak6Mar Gak9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1
Stage durations
Initial stage1 2 3 4
Stag
e du
ratio
n (d
)
0
5
10
15
20406080
100120
Mar Gak6Mar Gak9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1 Apr Gak13 cohorts Apr Gak1 cohorts Apr PWS cohortsMay Gak4 cohorts
Mar Gak6MarG9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1 Apr Gak13 cohorts Apr Gak1 cohorts Apr PWS cohortsMay Gak4 cohorts
Initial stage1 2 3 4
Inst
anta
neou
s G
row
th (d
-1)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
Mar Gak6MarG9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1 Apr Gak13 cohorts Apr Gak1 cohorts Apr PWS cohortsMay Gak4 cohorts
Initial stage1 2 3 4
Inst
anta
neou
s G
row
th (d
-1)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
Growth Rate
Mar Gak6MarG9MarPWSApr Gak1Apr Gak4Apr Gak9 Apr Gak13 May Gak1 Apr Gak13 cohorts Apr Gak1 cohorts Apr PWS cohortsMay Gak4 cohorts
Initial stage1 2 3 4
Inst
anta
neou
s G
row
th (d
-1)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
Generation time• Average faster than previous estimates [i.e.
12.6-16.6 days estimated (Miller, 1993), 24-25 days for C3 & C4 determined (Miller and Nielsen, 1988)]
• First 4 copepodite stages would be completed in 30-60 days … populations poorly synchronized
• Assuming N. femingeri/plumchrus naupliar development of 30-40 days (Saito & Tsuda, 2000); it would appear that 70-100 days from hatching are required to reach C5.
• The duration of the longer-lived stage C5 in the upper water column (prior to diapause) remains to be established
Influence of environment
• Temperature relatively constant Temperature relatively constant during all three cruises (4.5-6°C)during all three cruises (4.5-6°C)
• Chlorophyll and degree of Chlorophyll and degree of stratification increased on stratification increased on subsequent cruisessubsequent cruises
• Current task: to explore the Current task: to explore the relationship between measured relationship between measured rates and these variables….rates and these variables….
…move on to egg production