All an ecologist wants to know, but never can find

Peter M.J. Herman

Netherlands Institute of Ecology

Yerseke

p.herman@nioo.knaw.nl

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

What would we need for it ?

Linking of existing databases from national / regional monitoring programmes

Quality control on data setsExchange formatsResolution of the taxonomic messBetter linking between ecological, physical and

biogeochemical datasets