Processes controlling copepod distribution in Processes controlling copepod distribution in the Gulf of Maine - Georges Bank regionthe Gulf of Maine - Georges Bank region

R. Ji & C. DavisR. Ji & C. DavisDepartment of BiologyDepartment of BiologyWoods Hole Oceanographic InstitutionWoods Hole Oceanographic Institution

Working with:Working with: PI team:PI team: Chen, Beardsley, Townsend, Runge, Durbin, FlaggChen, Beardsley, Townsend, Runge, Durbin, FlaggUMASS-D modeling group:UMASS-D modeling group: Q. Xu, G. Cowles, R. Tian, S. Hu, D. StuebeQ. Xu, G. Cowles, R. Tian, S. Hu, D. StuebeDavis Lab:Davis Lab: Q. Hu, C. PetrikQ. Hu, C. Petrik NMFS:NMFS: D. Mountain, J. Hare, M. TaylorD. Mountain, J. Hare, M. Taylor

GLOBEC GB-4B PI Meeting (6/23/2008)GLOBEC GB-4B PI Meeting (6/23/2008)

Pm, Os

Cf, Pn Cf, Pn

Cham, Ctyp, Tl

Ctyp

Cfin: Calanus finmarchicusPcal: Pseudocalansu spp.Pm: Pseudocalanus moultoniPn: Pseudocalanus newmaniOs: Oithona spp.Cham: Centropages hamatusCtyp: Centropages typicusTl: Temora longicornis

Yellow: abundant in summer/fallWhite: abundant in winter/spring

Food-limit Resting egg

CfinPcal

Os

ChamCtypTl

x

x

xx x

x

Egg carrier

x

x

(Based on Davis 1984, 1987; Durbin&Casas, 2006)

- Peak in different season- Different external sources- Difference in life history traits

Dominant Dominant copepodscopepods Ctyp

PcalPcal

Jan-Feb Mar-Apr

May-Jun

Sep-Oct

Jul-Aug

Nov-Dec

PcalPcal ““Cold-water” species, peak in spring and early summerCold-water” species, peak in spring and early summer Higher development rate in lower temperatureHigher development rate in lower temperature Lower EPR compare to Ctyp, Cfin, similar to ChamLower EPR compare to Ctyp, Cfin, similar to Cham Lower egg mortality (egg carrier)Lower egg mortality (egg carrier) High concentration in shallow area (food limitation?)High concentration in shallow area (food limitation?) Maintain population size on the Bank, supply from Maintain population size on the Bank, supply from

upstream (match Davis 1984)upstream (match Davis 1984) Decrease of abundance after summer: Decrease of abundance after summer:

1.1. high mortality rate in the model (T-dependent, high mortality rate in the model (T-dependent, increase of predator in summer, Q10, visual increase of predator in summer, Q10, visual predator)predator)

2.2. other possible reason: less food (tested, false), less other possible reason: less food (tested, false), less EPR in warmer water (no exp support)EPR in warmer water (no exp support)

CtypCtyp

Jan-Feb Mar-Apr

May-Jun

Sep-Oct

Jul-Aug

Nov-Dec

CtypCtyp

““Warm-water” species, peak in later summer and fallWarm-water” species, peak in later summer and fall Lower development rate in cold temperatureLower development rate in cold temperature higher EPR compare to Pcal and Chamhigher EPR compare to Pcal and Cham Higher egg mortality (“broadcaster”)Higher egg mortality (“broadcaster”) Higher concentration in shallow area, but not confined Higher concentration in shallow area, but not confined

in shallow area (food limitation less obvious, in shallow area (food limitation less obvious, dispersive?)dispersive?)

Increase of abundance after summer (EPR increase)Increase of abundance after summer (EPR increase)

ChamCham

Jan-Feb Mar-Apr

May-Jun

Sep-Oct

Jul-Aug

Nov-Dec

ChamCham

““Warm-water?” species, peak in mid-summer, Warm-water?” species, peak in mid-summer, relatively high population in fall than winter/springrelatively high population in fall than winter/spring

Lower development rate in cold temperatureLower development rate in cold temperature Lower EPR compare to Cfin and Ctype, similar to PcalLower EPR compare to Cfin and Ctype, similar to Pcal High egg mortality (“broadcaster”)High egg mortality (“broadcaster”) High concentration in shallow area only (especially High concentration in shallow area only (especially

GB): Resting egg strategy + food limitationGB): Resting egg strategy + food limitation

Working hypothesisWorking hypothesis(from proposal)(from proposal)

“… The same model structure will be used for all species, changing only the parameter values (temperature/food/life-stage dependent egg production rate, development rate, growth rate, and normalized stage-dependent mortality) and behaviors, and thus expediting the model runs. The inputs of The inputs of characteristic life history traits of each species characteristic life history traits of each species together with its initial abundance patterns should together with its initial abundance patterns should generate its observed characteristic seasonal/spatial generate its observed characteristic seasonal/spatial patternspatterns…”…”

Model FrameworkModel Framework

Fully 3-D coupling

FVCOM-based(fvcom.smast.umassd.edu)

Food web model - NPZD (Ji et al., in press)

Mean-age zoop model(Hu et al., 2007)

Zooplankton model

Egg

Nauplii

Copepodite

Zooplankton

PhytoplanktonNitrogen

Food web model

Adult

Physical models

Atmospheric Model MM5/WRF

Ocean Model (FVCOM)

Ocean GCM

Global Tidal Model

FreshwaterInput

Satellite SST, U,V

BuoysT,S,U,VAltimeter

Detritus

Major features

A Generic Copepod ModelA Generic Copepod Model*Dimensionless, change parameters only

Belehradek function (egg)Belehradek function (egg)

Belehradek function (Nauplii)Belehradek function (Nauplii)

Belehradek function (Copepodite)Belehradek function (Copepodite)

EPR (T dependent)EPR (T dependent)

cfin

EPR (Food dependent)EPR (Food dependent)

Pcal (vavg) Pcal (vavg)

GB Crest

Jordan Basin

Exp. 1Exp. 1

Change D=f(T) to Cham/Ctyp

Population can’t be maintained

To maintain population:1. increase EPR (Ctyp) 2. Resting egg (Cham)

GB Crest

Jordan Basin

Exp. 2Exp. 2

Follow Exp. 1, but increase EPR

Population peak in summer/fall

Population size explodedpossible reason: egg mortality“broadcaster” vs “carrier”

GB Crest

Jordan Basin

Exp. 3Exp. 3

Follow Exp. 2, but increase egg mortality (from 3% to 15%)

Population peak in summer, not in fall, similar to Pcal in Exp. 1 (mortality issue?, see Exp. 4)

GB Crest

Jordan Basin

Exp. 4Exp. 4

Follow Exp. 3, decrease Q10m

Population peak in summer/fall

GB Crest

Jordan Basin

Mortality T-dependent might be different between Ctyp and Pcal.Any biological reason?

Exp. 5: Pcal GoM contributionExp. 5: Pcal GoM contribution

Increase initial concentration of Pcal in GoM by 10x

Examine the contribution of GoM population from last year

Ex. 6: Self-sustainability on GBEx. 6: Self-sustainability on GB

No GB initial population

Initialize GB only

Ex. 7: Effect of upstream inputEx. 7: Effect of upstream input

Yr 1

Yr 2

Yr 3

A: Baseline runB: No upstream input from Nova Scotia

Resting egg strategy (no mortality)

Resting egg strategy (with mortality)

SummarySummary

Different life history traits + environmental condition Different life history traits + environmental condition determine the spatiotemporal distributional patterns of determine the spatiotemporal distributional patterns of dominant copepod speciesdominant copepod species

Different reproduction strategies are used to maintain Different reproduction strategies are used to maintain population in GoM or on GB, including r-strategy (e.g. population in GoM or on GB, including r-strategy (e.g. “broadcaster” for Ctyp) and prolonged life history (e.g. “broadcaster” for Ctyp) and prolonged life history (e.g. resting egg for Cham). resting egg for Cham).

Pcal population is difficult to maintain in GoM/GB Pcal population is difficult to maintain in GoM/GB without upstream input, posibily due to k-strategy (“egg without upstream input, posibily due to k-strategy (“egg carrier”, less dispersive)carrier”, less dispersive)

Mortality control the population size, a sensitive Mortality control the population size, a sensitive parameter but difficult to estimateparameter but difficult to estimate