Effects of climate variability on Calanus dormancy patterns and population dynamics in the Northwest Atlantic

J.A. Runge, A. Leising, C. Johnson

• Mechanistic explanation of dormancy in species of Calanus

• Development of Calanus life cycle model

• Evaluate how year-to-year variability in environmental conditions interacts with dormancy-control mechanisms to control Calanus population dynamics.

Lipid accumulation window hypothesis

• Individual Calanus can only enter diapause if their food and temperature history allows them to accumulate sufficient lipid for overwintering and gonad development

• Decision to proceed to dormancy is initiated when lipid stores reach a preset threshold (% by weight in stage CIV)

• Exit from dormancy by endogenous timer or when lipid stores decrease below a preset threshold

Life cycle model with lipid diapause rule:

comparison with observations

Data sources

Data from:

DFO – AZMP: 1999 – 2005 (E.Head, P.Pepin)

DFO – IML:1990 – 1991 (S. Plourde, P. Joly)

US-GLOBEC: 1995 – 1999 (E. Durbin, M. Casas)

PULSE – NEC: 2003 – 2005 (R. Jones)

UNH COOA (Center for Coastal Ocean Observation and Analysis) (triangles) and Northeast Consortium PULSE fixed stations, (red circles: 2003-05 and 2007)

Western Gulf of Maine fixed station sampling: 2003-2007

0 %

2 0 %

4 0 %

6 0 %

8 0 %

1 0 0 %

J F M A M J J A S O N D J F M A M J J A S O N D J F M AM J J A S O N J F M AM J J A S O D

2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 7

Calanus_finm archicus O ithona_sim ilis Pseudocalanus_spp.Centropages_sp T em ora_longicornus O ikopleura_sp.Balanus M eroplankton O ther Copep

Zooplankton Species CompositionJeffreys Ledge

2003 2004 2005 2007

Cfin

J F M A M J J A S O N D

A decline in the abundance of Calanus finmarchicus in 2004-2005

Abundance of Calanus finmarchicus

CV

Total

summer

Adults

May June

Oct-Dec

Spawning

Cod

Herring

Northwest Atlantic Marine Alliance (NAMA)-UNH Western Gulf of Maine Inshore Fisheries

and Ecosystems Project

Cartographer: A. Holt Cline

NH

Cape Ann

28.5

29.0

29.5

30.0

30.5

31.0

31.5

32.0

32.5

33.0

Salinity by 1m depth for New Scantum (2003-2005)

365 730

-50

-40

-30

-20

-10

0

2003 2004 2005

Ma

r

Ma

y

Ju

ly

Se

pt

No

v

Ma

r

Ma

y

Ju

ly

Se

pt

No

v

Ma

r

Ma

y

Ju

ly

Se

pt

No

v

Ja

n

Ja

n

Salinity on Jeffreys Ledge: 2003-2005

2003 20052004M M MM MJ JS SN NS N

Chlorophyll a standing stock“B”

Jeffreys Ledge

2003

2005

Hypothetical metapopulation structure of Atlantic Cod in the GoM/GGB system

Based on Wirgin et al. 2007; A. Kovach, UNH, G. Sherwood and S. Tallack, GMRI