Why do biological oceanographers care about planktonic protozoa (i.e., microzooplankton)? And why should the microbial loop be included in models of pelagic ecology?? Dian J. Gifford Graduate School of Oceanography University of Rhode Island Narragansett, RI, USA [email protected]http://gso.uri.edu/faculty/gifford.html
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Why do biological oceanographers care about planktonic protozoa (i.e., microzooplankton)?
Why do biological oceanographers care about planktonic protozoa (i.e., microzooplankton)? And why should the microbial loop be included in models of pelagic ecology??. Dian J. Gifford Graduate School of Oceanography University of Rhode Island Narragansett, RI, USA [email protected] - PowerPoint PPT Presentation
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Why do biological oceanographers care about planktonic protozoa (i.e.,
microzooplankton)?
And why should the microbial loop be included in models of pelagic ecology??
D.J. Gifford Imaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
Ecological Functions of Planktonic ProtozoaEcological Functions of Planktonic Protozoa
Primary Production: retention of functional chloroplasts; mixotrophy
Nutrient Cycling: excretion fuels water column primary production
Grazing: major source of phytoplankton and bacterial mortality
Trophic Coupling: prey of higher trophic levels
D.J. Gifford Imaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
Ciliates Containing Plastids or EndosymbiontsCiliates Containing Plastids or Endosymbionts
Location Depth Season% Ciliate
fauna Author
Woods Hole Surface SpringSummer
FallWinter
51472222
Stoecker et al. 1987
Nantucket Sound 0- 9 m Summer 48 Stoecker et al. 1987
Mediterranean Sea Surface Fall 41 Laval- Peuto &Rassoulzadegan 1988
Georges Bank 0- 1% light Summer 39 Stoecker et al. 1990
D.J. GiffordImaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
StationM. rubra
(ng C f ixed/ h))L. strobila
(ng C f ixed/ h)% Photosynthesis
Total% Photosynthesis
Microplankton
A1 29 20 1 29
A1 71 96 5 14
B1 32 0 6 31
C1 70 71 2 16
C3 0 15 7 >90
Contribution to Water Column PhotosynthesisContribution to Water Column Photosynthesis
D.J. Gifford Imaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
(Stoecker et al. 1990)
Log Dry Weight (mg/organism)
Nit
rogen E
xcr
eti
on R
ate
(ug N
/mg D
ry W
eig
ht/
d)
-10 -8 -6 -4 -2 0 2
100
101
102
103
10-1
10-2
10-3
Protozoa
Metazoan Zooplankton
(Caron 1991)
D.J. Gifford Imaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
GRAZING
d [Chl]u [Chl]u ( k - a - m - s - g + x ) ~ 0 dt
=
cell division
advection
mixin
g
sinkin
g
gra
zing
horizon
tal terms
k a m s g
Subant arct ic 0.25 0.04 0.05 <0.02 0.15
Subarct ic 0.50 <0.01 ~0.03 0.01 ~0.45
Subt ropicalGyre
1.2 <0.01 <0.01 <0.01 ~1.2
Equat orialUpw el l ing
1.0 0.04 0.02 0.01 0.90
D.J. GiffordImaging LaboratoryGraduate School of OceanographyUniversity of Rhode islandImaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
(Banse, 1992)
Protozoan Grazing Impact in Pelagic Ecosystems
Location Season% Primaryproduction
consumed d- 1
Author
Washington Coast Fall 17- 52 Landry & Hassett 1982
Halif ax Harbour MarchAprilJ uneAugustNovember
100554740ns
Gif ford 1988 “ “ “ “
North Atlantic Spring (late bloom)Mid- summerSpring (Phaeocystisbloom)Spring (post- bloom)Summer
25290
10041
Weeks et al. 1993Burkill et al. 1993Gif ford et al. 1995 “ “
Celt ic Sea Annual 16- 35 Burkill et al. 1987
Canadian Arctic Summer 40- 100 Paranj ape 1987
Equatorial Pacif ic WinterFall
~10040- 80%
Landry et al. 1995
Subarctic Pacif ic May ~100 Landry et al. 1993
D.J. Gifford Imaging LaboratoryGraduate School of OceanographyUniversity of Rhode Island
August September January
Microplankton prey category
Cle
ara
nc
e r
ate
(m
l/c
op
ep
od/h
)In
ge
sti
on
ra
te (
ng
C/c
op
ep
od
/h)
0
5
10
1 2 3 4 5 6 7 Chla
1 2 3 4 5 6 7 Chl a 1 2 3 4 5 6 7 Chl a 1 2 3 4 5 6 7 Chl a
Hemigrapsis sanguinea (Gifford & O’Connor, unpubl.)Cancer magister (Sulkin et al. 1998)
Miscellaneous crustaceans
Balanus cf. Crenatus nauplii (Turner et al. 2001)Freshwater cladocera (Wickham & Gilbert 1991; Pace & Vaque 1994; Wiakowsji et a. 1994; Adrian & Schneider-Olt 1999)
Bivalves
Crassostrea gigas (Dupuy et al. 1999)
Gelatinous zooplankton
Aurelia aurita (Stoecker et al. 1987)Mnemiopsis leidyi (Stoecker et al. 1987; Sullivan & Gifford, submitted)
Globec 01: Patterns of Energy Flow and Utilization on Georges Bank
Funding: National Science Foundation: $1,500,000Timeline: 2001-2005
Principal Investigator: Dian Gifford, University of Rhode IslandCo-Investigators: James Bisagni, University of Massachusetts
Jeremy Collie, University of Rhode Island Edward Durbin, University of Rhode island
Michael Fogarty, NMFS, Woods Hole Jason Link, NMFS, Woods Hole Lawrence Madin, Woods Hole Oceanographic Institution David Mountain, NMFS, Woods Hole Debra Palka, NMFS, Woods Hole
Michael Sieracki, Bigelow Laboratory for Ocean Science John Steele, Woods Hole Oceanographic Institution Barbara Sullivan, University of Rhode island
General Objective: To provide a broad ecosystem context for interpretation of the population dynamics of Georges Bank GLOBEC target species.
Specific Objectives:
Examine alternate model outcomes of GLOBEC and GLOBEC-related studies
Examine the mechanisms forcing changing patterns of energy flow on Georges Bank
With explicit consideration of factors not addressed in earlier models of the system:
Sources and fates of new production The role of the microbial food web in production processes Secondary production processes, including the apparent secondary production deficit Changes in invertebrate and vertebrate predator species composition in the context of population dynamics of GLOBEC target organisms Effects of environmental forcing on production processes during contrasting (~decadal) time periods
Scientific approach:
(1) Combine top-down [consumption-based models] and bottom-up [production-based models] approaches to describe Georges Bank food web
(2) Use these analyses as a precursor to dynamic modeling
Principal tools:
Linear network analysis (Vezina, 1999; 2000)
Nonlinear dynamical modeling (Collie and Delong 1999).
Focus on two major issues:
(1) Imbalance between primary production and fish production. “leakage hypothesis” v. microbial web dynamics
(2) Magnitude of top-down [fish] v. bottom-up [microbial web] processes
Locations of three spatial domains on Georges Bank derived from anEOF mode 1 SST map (Bisagani et al. 2000). GBC=Georges Bank Crest. TMF = Tidal Mixing Front. GBSF = Georges Bank Southern Flank. Spatial domains change with season.
A. Spring (open bars) and fall (filled bars) bottom temperature anomalies for Georges Bank. The data are from NMFS spring (1968-2000) and fall (1963-2000) trawl surveys. The anomalies are referenced to the MARMAP data set (1977-1987).
B. Spring (open bars) and fall (filled bars) salinity anomalies for Georges Bank. The data are from NMFS spring (1968-2000) and fall (1963-2000) trawl surveys. The anomalies are referenced to the MARMAP data set (1977-1987).
Temperature
Salinity
Gadoids
0
200
400
600
800
1000
1200
1964 1969 1974 1979 1984 1989
Year
Observed
Multispecies model
Yield
Flatfish
0
10
20
30
40
50
60
70
80
1964 1969 1974 1979 1984 1989
Year
Elasmobranchs
0
50
100
150
200
250
1964 1969 1974 1979 1984 1989
Year
Pelagics
0
100
200
300
400
500
600
700
1964 1969 1974 1979 1984 1989
Year
Changes in fish abundances on Georges Bank since the 1960s (Collie and Delong, 1999):
Decreasing gadoids and flatfish Increasing pelagics and elasmobranchs
Temporal Stanzas: three time periods are defined on the basis of the historicaltemperature record:
Seasons: three seasons are defined on the basis of mixing regime: September-April: well-mixedApril-June: episodic stratificationJune-September: stratified