All an ecologist wants to know, but never can find
Peter M.J. Herman
Netherlands Institute of Ecology
Yerseke
Total N vs. Total P
Anorganic N vs.Anorganic P
What makes us jealous ?
Large datasets
Reliably measured data
Covering most of the ocean
Far-reaching interpretations
System primary production (gC.m-2.y-1)
0 100 200 300 400 500 600 700
Sys
tem
-ave
rage
d m
acro
faun
a bi
omas
sg
AF
DW
m-2
0
10
20
30
40
50
60
70
B=-1.5 + 0.105 Pr2=0.77
GR
OS
VM
WS
B1
B2
ED
EW
CBSFBLIS
LY
COL
YT
BF
Cross-system comparisons of benthic biomass and primary production in estuaries
System-averaged benthic biomass relates to system-averaged primary production
Possible implications for effects eutrophication
Possible norm for biomass
But: system coverage poor!
Herman et al. 1999 Adv.Ecol.Res
0
2
4
6
8
10
12
14
0 2000 4000
Depth (m)
Re
sp
ira
tio
n (
gC
.m-2
.y-1
)
SCOC Macro Meio
Benthic data from shelf break
Heip et al. 2001 DSR IIOmex project: benthic fauna and sediment biogeochemisty
0.1
1
10
100
1 10 100 1000
(Estimated) SCOC (gC.m -2 .y-1)
Bio
mas
s m
acro
fau
na
(gA
FD
W.m
-2)
Shelf break data compared with shallow systems
Shallow systemsEstimated as 1/3 PP
Consistent pattern over orders of magnitude of organic loading
What could be mined further ?
More data sets on benthic biomass, PP and sediment oxygen consumption
Breakdown of datasets: regionally, with water depth, with physical conditions, with nature of primary production etc..
Breakdown of benthic biomass into different functional groups, even species.
Better resolution of variability behind the averages – what are determining factors for these
Sediment community oxygen consumption
0 2000 4000 6000Depth [m]
-6
-4
-2
0
2
4
6L
og
e (
SO
C [
mm
ol m
-2 d
-1]
)
Henrik Andersson et al. submitted
Refining with PP-depth gradients
0 2000 4000 6000
Depth [m]
0.05
0.50
5.00
50.00
500.00
Prim
ary
Pro
duct
ion
[ mm
ol C
m-2
d-1
]
Derived: rates of pelagic oxygen consumption with depth
0 100 200 300 400 500
Depth (m)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Oxy
gen
Upt
ake
Rat
e (m
mol
m-3
d-1
)
+ relative role of water column / sediment in mineralisation+ estimate of benthic denitrification
Corrected for lateral production gradient
Uniformly productive ocean
What could be mined further?
Relation with macro/meiobenthic biomass, species composition and diversity
Depth (m) Latitude
Oxygen (ml/l) % Org. Carbon
E.g. Levin & Gage (1998)
Macrobenthic diversity as a function of depth, oxygen, latitude, carbon content of sediment
Danish monitoring: relation mussels – chl a
Kaas et al. (1996)
Bloom
Decay
graz
prod
'mix
prodK
'
Koseff et al., 1993
?-> mixing rates?
1 2 3 40
5
10
15
20
25
30
35
biom
ass
(g A
FD
W/m
² ±
se)
salinity region
intertidal undeep subtidal deep subtidal channel
Macrobenthos Westerschelde: depth & salinity
Tom YsebaertPeter Herman
Biomass (g AFDW.m-2) of feeding groupsIntertidal stratum
salinity zones
zone 1 zone 2 zone 3 zone 4
Bio
mas
s (g
AF
DW
m-2
)
0
5
10
15
20
25
susp surf depo omni pred
Comparison other regional systems
0
20
40
60
80
100
120
140
bio
mas
s (g
AF
DW
.m-2)
intertidalshallow subtidaldeep subtidalchannel
WS OS GR VM
Tom YsebaertPeter Herman
GrevelingenOosterscheldeVeerse MeerWesterschelde
Distribution ~ * macro- vs. micro-
vs. non-tidal* wave vs. current* transparancy* oxygen conditions
Functional guilds and depth distribution : Oosterschelde
0 1 2 3 4
-1 - 2 m
2 - 5 m
5 - 8 m
> 8 m
0 20 40 60
-1 - 2 m
2 - 5 m
5 - 8 m
> 8 m
Biomass (g AFDW.m-2)Deposit feeders
Biomass (g AFDW.m-2)Suspension feeders
Model for suspension feeder occurrence
CPCzz
CK
zt
C
mixing sinking
production - consumption
P
P
P
Phytoplankton growth at depth z:
-> food depletion suspension feeders depends on production, mixing, pelagic losses-> suspension feeders deeper as water gets more transparant
Some common denominators
Data sets must come from both similar and dissimilar systems
Comparability of methods is prerequisiteNot valuable without physical and/or chemical
metadataTaxonomy problems when analysed at species
level ; autecology often lacking when analysed at functional group level
Models needed to make data meaningful
What would we want?
Easily accessible, highly resolved ecological dataGeoreferencedConsistent taxonomyAuto-ecological informationWell-documented methodsPhysical and chemical data (depth, light,
chlorophyll, nutrients, sediment composition, physical stress,…) linked
Spatiotemporal variation represented
What could we do with it?
Inter-system comparison of limiting factors on species / functional guilds / trophic groups
Deriving norms and indicators adapted to local circumstances
Detecting general temporal trends ~ global changeBetter exploitation of remotely sensed variables
Testing ecological hypothesesDetecting patterns that suggest experimental
approach or detailed research