Upload
philippa-francis
View
224
Download
0
Embed Size (px)
Citation preview
Northern copepod biomass anomalies and copepod species richness as indicators of trophic
structure in the NCC
Bill Peterson, Senior ScientistNOAA Fisheries
Jennifer Fisher, CIMRS/Oregon State UnivNewport OR
We have been sampling the Newport Line every two weeks for 19.5 years to try to understand:a) the causes of interannual variability in planktonb) how this variability translates into differences in food web structure upon which juvenile fish feed such as salmon, sardines, sablefish and rockfish
Circulation off thePacific Northwest
1. Subarctic Coastal Currents bringcold water and ”northern” copepodspecies to the N. California Current
2. A weak California Current,onshore flow of the West Wind Drift and Davidson Current (in winter)brings subtropical water and subtropical “southern” copepod species to the NCC = increased species richness
3. Therefore, food chain structure is affected by the source waterswhich feed the California Current
Different climate modes and associated differences in transport are important for three reasons:
Data on the abundance or biomass of ‘northern’ copepods and species richness is important because…
• Warm-water subtropical southern species- (from offshore OR and S. California) are small in size and have minimal high energy wax ester lipid depots
• Cold-water northern species – (boreal coastal species) are large and store high-energy wax esters as an over-wintering strategy
Therefore, significantly different food chains result from changes in transport
A fat _____ is a happy ______
PDO and Northern Copepod Anomaly
PDO and ONI
PD
O &
ON
I (°C)
-3
-2
-1
0
1
2
3
Biom
ass Anom
aly (Log10)
Northern Copepod Anomaly
Year
97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
PDO and Copepod Species Richness Anomaly
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 PD
O (colors) and O
NI (line)
-3
-2
-1
0
1
2
3
4
YEAR
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
Copepod S
peciesR
ichness Anom
aly
-6
-4
-2
0
2
4
6
8
Subtropical species
Boreal species
Copepod indices vs salmon returns
Fall ChinookR2 = 0.42; p = 0.01
excl. 2011*
Copepod Species Richness Anomaly (Log 10 May-September Average)
-4 -2 0 2 4 6
200
400
600
800
10002011Fall Chinook
R2 = 0.79; p < 0.001
Northern Copepod Biomass Anomaly
(Log10 May - September average)
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6Counts of A
dult Salm
on at Bonneville D
am(thousands; 2 year lag)
0
200
400
600
800
1000
Northern copepod anomaly (May - Sept)
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
Sa
rdine recruitm
ent (age 0)
0
5
10
15
20
25R2 = 0.65p < 0.001excl. 2003
2003
Northern copepod anomaly (May - Sept)
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
Sa
blefish recruitment
(age 0; thousa
nds)
0
10
20
30
40R2 = 0.40p = 0.01excl. 1999
1999
Northern copepod anomaly vs Sardine and Sablefish recruitment
PDO (bars) and ONI (black line)
96 98 00 02 04 06 08 10 12 14
Val
ues
(PD
O,
ON
I)
-3
-2
-1
0
1
2
3
4
Climate modes: PDO, ONI, HFCCTI, NPGO
• CC had lower flows in 03-07, and 10
• CC had higher flows in 02, 08-09 and 10-13
• Matches PDO closely(except 2014)
Howard Freelan's California Current Transport Index (Anomaly)
Year
96 98 00 02 04 06 08 10 12 14
Valu
es
-0.10
-0.05
0.00
0.05
0.10
0.15