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MarFISH - workshop on Ecosystem functioning relevant to fish biodiversity and fisherieslfremerlfremer

Anik Brind’Amour

IFREMER, Ecologie et Modèles pour l'Halieutique (EMH)Nantes, France ([email protected])

On the assessment of functional diversity incoastal nurseries: the Bay of Biscay case study

© Ifremer.fr


© Wikipedia

Bay of Biscay

Gironde

Pertuis Antioche

Pertuis Breton

BourgneufLoire

Vilaine

Gironde

Pertuis Antioche

Pertuis Breton

BourgneufLoire

Vilaine

Diverse and highly productive habitats: Estuaries, bays, exposed coasts

Coastal habitats: Numerous studies (e.g. flatfish recruitment)

Le Pape 2005


Coastal nursery habitats

Juveniles

inshore

Spawning

offshore

Planktonic

larvae

Typical life-cycle of species using coastal nurseries

Juveniles

inshore

Spawning

offshore

Planktonic

larvae

Typical life-cycle of species using coastal nurseries

Important ecological functions: Nursery habitats for many commercial fish stocks:

Flatfish (common sole, wedge sole, plaice, flounder), sea bass, whiting, pouting…

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Loss of habitat quality and quantity Change in biodiversity

↓Community structure

Changes in resource use patterns between species

↓Ecosystem processes

Functional relationships


Identify indicators of anthropogenic pressures on coastal communities using functional approach (e.g. functional diversity)

Functional approach : Why ?

• Simplify species-rich communities and thus allow the transferabilityof habitat models among ecosystems (Angermeier and Winston 1998)

• Groups of traits form operational units that respond to environmentalchanges in a more predictable way than individual species (Austen et al. 1994)

• Analytical way (first approach) of assessing the groups traits relevant to ecosystem functioning


Figure from Petchey et Gaston (2006)Figure from Petchey et Gaston (2006)

Functional diversity : Which DF measure ?

Common question: Which traits should be included ?

Response traitsEffect traits

All traits important for the function of interest

All traits associated with the forcing of interest (e.g. fishing impact)


Main goals

Verify if we can detect anthropogenic pressures on coastal communities and if functional diversity is a good indicator of bottom

perturbation by trawls and dredges

1) What are the important groups of traits structuring the nursery communities? … Which traits are correlated with bottom trawl/dredge activities ?

2) Do they vary among nurseries ?

3) Do the measures of functional diversity display among-nursery variation ?

Questions


Sampling in 2000-2003 (September)

Six bays/estuaries

3 m beam trawl (n=176 hauls)

Depth range : 3 to 37 m

Biological data (45 species)Fish (25), molluscs (9), arthropods (5), echinoderms (3), annelids (3)

Sampling procedure

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Vilaine

LoireBourgneuf

Gironde

Pert Antioche

Pert Breton


List of species

Species included in the analyses

Acanthocardia echinata Dicologlossa cuneata Phrynorhombus norvegicus

Alloteuthis Gobius niger Platichthys flesus

Amphiura brachiata Hippocampus hippocampus Pleuronectes platessa

Amphiura filiformis Liocarcinus Pomatoschistus minutus

Aphrodita aculeata Loligo vulgaris Psammechinus miliaris

Arnoglossus laterna Merlangius merlangus Raja clavata

Asterias rubens Merluccius merluccius Scyliorhinus canicula

Buglossidium luteum Mullus surmuletus Sepia officinalis

Callionymus lyra Necora puber Solea solea

Carcinus maenas Ophiura ophiura Sparus auratus

Cerastoderma edule Owenia fusiformis Spondyliosoma cantharus

Chelidonichthys gurnardus Paguridae Trachurus trachurus

Chelidonichthys lucernus Palaemon serratus Trisopterus luscus

Ciliata mustela Pectinaria koreni Trisopterus minutus

Crangon crangon Philine aperta Turritella communis

Dicentrarchus labrax


Sampling in 2000-2003 (September)

Six bays/estuaries

3 m beam trawl (n=176 hauls)

Depth range : 3 to 37 m

Biological data (45 species)Fish (25), molluscs (9), arthropods (5), echinoderms (3), annelids (3)

Functional traitsFeeding, reproductive, ecological guilds, biogeo,substrate, commercial

Environmental variables Temperature, bathymetry,substrate, pressure index

Sampling procedure

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emer

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Vilaine

LoireBourgneuf

Gironde

Pert Antioche

Pert Breton


Methodological framework Part I: Selection of functional traits

Matrix of environmental forcingMatrix species-functional traits

List of natural and anthropogenic stresses

LiteratureDatabaseExperts

X 6 nurseries

Traits

Spe

cies

Sites

Env

ironm

ent

SamplingCalculated


Anthropogenic pressure Potential impact Functional trait

Dredging Habitat modification Substrate preferenceReproductive guildVertical distributionTolerance to anoxia

Fisheries DirectBiomass/abundance Body size

Vertical distributionFeeding guildLife-history strategyCommercial (for bycatches)

IndirectHabitat modification Ecological guild

Feeding guildReproductive guildMobility

List of species functional traits

Functional category Attribute Code

Feeding guilds Phytoplankton PLZooplankton ZPInvertebrate (mollusc, crustacean) ISFish FSPlants VSDeposit feeder DSSPlankton + Deposit feeder PDDetritivore DSOmnivore OM

Reproductive guild Pelagic eggs OpEggs guarded OgEggs protected (shed, pouch, case) Os

Ecological guild Marine migrant MAMarine seasonal migrant MSMarine juvenile migrant MJEstuarine resident ERCatadromous CAT

Mobility Swimmer SRCrawler CRBurrower BRPermanent attachment PA+ Substrate pref

+ Commercial+ Biogeography


Estimation of fishing impact

Coastal fisheries surveys

Fishing fleet surveys

Monthly from 11/2000 to 11/2001

Inside the 12 miles

Census of fishing boat (+ type of fisheries)

Bottom trawls and dredges

Others (gillnets, potters, longlines)

Geographical positions

© mar.dfo-mpo.gc.ca© mar.dfo-mpo.gc.ca

From Léauté (2007)


Spatially-based index of bottom perturbation

-1.28 -1.26 -1.24 -1.22 -1.20 -1.18 -1.16

45.9

645

.98

46.0

046

.02

46.0

446

.06

46.0

8

survol.pant$Xlong

surv

ol.p

ant$

Yla

t

density(pant.ppp)

-1.30 -1.25 -1.20 -1.15 -1.10

45.9

546

.00

46.0

546

.10

010

0020

0030

0040

0050

00

0 0 1 2 5 4

0 1 5 3 3 1

0 4 3 4 0 1

density(pant.ppp)

-1.30 -1.25 -1.20 -1.15 -1.10

45.9

546

.00

46.0

546

.10

010

0020

0030

0040

0050

00

0 0 1 2 5 4

0 1 5 3 3 1

0 4 3 4 0 1

Grid size ~16 km2 / sector

Index: Number of observations / cell

0

50

100

150

200

250

vil bou loi pbre pant gir

Tot

al n

umbe

r of

boa

t

0

10

20

30

40

50

60

70

80

90

100

Rat

io (

boat

cel

l/tot

al c

ell*

100)

NbBoat

Ratio


Methodological framework Part I: Selection of functional traits

Fourth-corner analysisSelection of functional traits structuring

each nursery community

X 6 nurseries

Matrices of environmental factorsMatrices functional traits

List of natural and anthropogenic stresses


X 6 nurseries

TraitsS

peci

es

Sites

Env

ironm

ent

Sampling

Matrices of environmental factorsMatrices functional traits

List of natural and anthropogenic stressesList of natural and anthropogenic stresses


X 6 nurseries

TraitsS

peci

esTraits

Spe

cies

Sites

Env

ironm

ent

Sampling


Fourth-corner analysisSelection of functional traits structuring nursery communitiesE

nviro

nmen

tal f

acto

rs

Quantitative

C: pxm

Env

ironm

enta

l fac

tors

Quantitative

C: pxm

Correlations

D: pxn

(D = CA’B )

Correlations

D: pxn

(D = CA’B )

(Legendre et al. 1997, Dray et Legendre submitted)

Functional traits

Quantitative/qualitative

B: kxn

Functional traits


B: kxn

Sampling sites

Spe

cies

Quantitative

A: kxm

Sampling sites

Spe

cies

Quantitative

A: kxm

Spe

cies

Quantitative

A: kxm

Env

ironm

enta

l fac

tors

Quantitative

C: pxm

Env

ironm

enta

l fac

tors

Quantitative

C: pxm

Correlations

D: pxn

(D = CA’B )

Correlations

D: pxn

(D = CA’B )


Functional traits


B: kxn

Functional traits


B: kxn

Sampling sites

Spe

cies

Quantitative

A: kxm

Sampling sites

Spe

cies

Quantitative

A: kxm

Spe

cies

Quantitative

A: kxm

Env

ironm

enta

l fac

tors

Quantitative

C: pxm

Env

ironm

enta

l fac

tors

Quantitative

C: pxm

Correlations

D: pxn

(D = CA’B )

Correlations

D: pxn

(D = CA’B )


Functional traits


B: kxn

Functional traits


B: kxn

Sampling sites

Spe

cies

Quantitative

A: kxm

Sampling sites

Spe

cies

Quantitative

A: kxm

Spe

cies

Quantitative

A: kxm

Select functional traits displaying significant correlations with

environmental factors

Functional traits


B: kxn

Spe

cies

Functional traits


B: kxn

Spe

cies

Functional traits


B: kxn

Spe

cies

Functional traits


B: kxn

Spe

cies

Functional traits


B: kxn

Spe

cies

Functional traits


B: kxn

Spe

cies

X 6 nurseries

Loire Gironde …


New matrices of species-traits … X6

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Methodological framework Part II: Computation of functional diversity

• Weight=0 if trait is not significant

• FD is weighted by the forcings and only the significant traits associated with those forcings (eg fishing impact) are influencing the DF estimate


New matrices of species-traits … X6

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Traits

Spe

cies

Tree-based approach FD = branches length

Functional Diversity … X6

FD = 6 FD = 4

Methodological framework Part II: Computation of functional diversity


Natural variability and fishing impact

Vil loi BouPL sed bathy temp index sed bathy temp index sed bathy temp indexZPISFSVSDSSPDDSOMOpOgOsMAMSMJERCATSRCRBRPATeBoStCOMSFRMVeg

Pbre Pant girsed bathy temp index sed bathy temp index sed bathy temp index

PLZPISFSVSDSSPDDSOMOpOgOsMAMSMJERCATSRCRBRPATeBoStCOMSFRMVeg


Natural variability and fishing impact

Based on PCA/Cluster analyses

Loire and Bourgneuf: Sediment and bathymetry � feeding guild (detritivores and omnivores)

Bourneuf/Antioche/Breton : Fishing index � ecological guild(juvenile migrant and estuarine resident)

Gironde: Low correlations… (burrowers)


5.8

5.0

7.2

6.3

7.3

6.3

If so, do the measures of functional diversity display among-nursery variation ?

•Small differences between nurseries


Conclusions

Methodological framework

Selection of functional traits constrained by species abundance and environmental factors

Evenness and environmental forcings (natural and/or anthropogenic)

Statistical testing of the functional traits structuring the communitiesKey decision in many FD measures

Assessment of the FD using tree-based approachSpecies are not treated binary (continuous measure)

Differences between nurseries

Nurseries seem structured by different factors, but similarities in nearby sectors

Bottom perturbation by bottom trawlers seems to be more important in 3 nurseries and affects mostly ecological guilds


density(vil.ppp)

-2.75 -2.70 -2.65 -2.60 -2.55 -2.50 -2.4547.3

047

.35

47.4

047

.45

47.5

047

.55

050

010

0015

0020

0025

00

density(loi.ppp)

-2.40 -2.35 -2.30 -2.25 -2.20

47.0

647

.10

47.1

447

.18

47.2

2

010

0020

0030

0040

0050

00

density(bou.ppp)

-2.25 -2.20 -2.15 -2.10 -2.05

47.0

047

.02

47.0

447

.06

47.0

847

.10

47.1

2

010

0030

0050

00

Sector comparison

Documents

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