Response and recovery potential of temperate benthic marine ecosystems

following human disturbance

Sciencedaily.comNationalgeographic.com Sciencedaily.com

Erin McClelland

Janelle Curtis

Chris Wood

Devon Warawa

devon.warawa@gmail.com

Katrina Poppe

Fishing DisturbanceKukenthal Peak, NE Atlantic

http://www.whoi.edu Before trawling

After trawling

International conservation concern: (Collie, 2000)

• Reduction of productivity and biodiversity

• Poorly understood indirect effects

• Fishing footprint is expanding

Fishing Disturbance

http://www.whoi.edu (Kukenthal Peak, NE Atlantic)

Before trawling

After trawling

Most widespread anthropogenic disturbance in marine ecosystems

(Watling & Norse 1998; Kaiser et al. 2002)

United Nations General Assembly (UNGA) Resolution 61/105 (2006):

•“…determine whether bottom fishing activities would cause significant adverse impacts” (Paragraph 83)

•“protect vulnerable marine ecosystems, …., from destructive fishing practices” (Paragraph 80)

Convention on Biological Diversity (CBD) (2008):•“identify…significant and/or vulnerable marine areas”

(Paragraph 18, Decision IX/20)

•“Identify processes and … activities which have or are likely to have significant adverse impacts…” (Article 7)

Food and Agriculture Organization (FAO) (2008):

•Significant adverse impacts compromise ecosystem integrity over long- term e.g. >20 years (Paragraph 17)

International Commitments and Technical Advice

Ecosystem Response and RecoveryEc

osys

tem

indi

cato

r

Refe

renc

e st

ate

-5 0 5 10 15 20

Time (years)

Disturbance event

Objectives

Focus:

• Use a meta-analysis to examine the response and recovery of benthic marine ecosystems to anthropogenic activities

• Identify factors that affect recovery time

Temperate and polar areas

Subtidal ecosystemsFishing disturbance

Systematic literature review (1999-2010)

Keywords: “(marine OR deep* OR cold-water OR pelagic OR benth*) AND (ecosystem*) AND (trawl* OR fishing OR fisher* OR dredg*) AND (recover* OR vulnerab*)”

Criteria for analysis:

• Empirical measure(s) of species response

• Means and standard deviations reported

• Temporal or spatial reference site comparison

n = 24/674 studies

Factors Influencing Response and Recovery

CATEGORY CLASS

Duration Single Repeated

Gear Otter trawl Beam trawl Whiting net Scallop dredge Box dredge Clam dredge

Depth (m) <20 20-50 50-80 >80

Substrate Silt Sand Pebble Boulder

Taxa 21 taxa

Habitat Infauna Epifauna Pelagic

Feeding Photo. Filter Grazers Scavengers predators

Mobility Fixed Low Moderate High

Lifespan (yrs) <1 2-5 5-10 10-20 >20

Ecosystem Indicators: Species richness, abundance, and diversity

Meta-analysis: Mixed-effects model

Sum of the weighted effect

size for each comparison

within a class

(Gurevitch & Hedges 1999)

=-

Sum of the variance within a class

Sum of the weighted effect size for each comparison

within a class

2

silt sandExamine weighted

effect size, di* di* = -0.149 ± 0.215

Apply fail-safe test, Nfs(Publication bias)

Nfs=664

Test for homogeneity of variance between

classes,

boulderpebble

di* = -0.411 ± 0.163

di* = -0.128 ± 0.357

di* = 0.120 ± 0.153

Q = 21.62; p<0.05

There is a significant negative response of abundance following fishing in sandy habitats

Example: Is sediment type important in predicting change in abundance?

*bQ

*bQ

Response: All ComparisonsE

ffe

ct S

ize

(di*)

Diversity Species Abundance

Richness

0.2

0.0

-0.2

-0.4

-0.6

-0.8

-1.0

-1.2

-1.4

Response: Species RichnessCategory/Class Test Statistic Effect Size 95% CIDuration 2.81

single -0.527 -1.075 – 0.020

repeated -1.142 -1.607 – -0.677

Substrate 2.94 silt -0.335 -1.493 – 0.823

sand -0.670 -1.184 – -0.156

pebble -1.270 -1.899 – -0.641

Depth 1.44 0-20m -0.639 -1.207 – -0.071

20-50m -1.127 -1.738 – -0.516

50-80m -1.103 -1.793 – -0.232

>80m -0.699 -3.175 – 1.777

Gear 10.69 otter trawl -0.023 -0.453 – 0.407

beam trawl -1.471 -2.278 – -0.663

whiting net -0.716 -1.889 – 0.457 clam dredge -0.579 -0.879 – -0.279

box dredge -0.461 -0.913 – -0.008

*bQ

*id

OtterTrawl

BeamTrawl

WhitingNet

ClamDredge

BoxDredge

Effec

t Siz

e (d

i*)

Response: Species Richness

Type of Gear1.0

0.5

0.0

-0.5

-1.0

-1.5

-2.0

-2.5

Category

Duration 0.11

Substrate 21.62

Depth 12.38

Gear 18.65

Taxa: class 67.63

Position 1.27

Feeding 31.19

Mobility 0.649

Life-span 5.58

*bQ*id*bQ*id*bQ*id*bQ*id*bQ*id

*bQ

Response: Species Abundance

Response: Species AbundanceEff

ect S

ize

(di*

)

Otter Beam Whiting Scallop Clam Box Trawl Trawl Net Dredge Dredge Dredge

Type of Gear0.4

0.2

0.0

-0.2

-0.4

-0.6

-0.8

-1.0

-1.2

-1.4

Response: Species Abundance

Silt Sand Pebble Boulder

Substrate

Effec

t Siz

e (d

i*)

0.4

0.2

0.0

-0.2

-0.4

-0.6

-0.8

Response: Species AbundanceEff

ect S

ize

(di*

)

0-20m 20-50m 50-80m >80m

Depth0.2

0.0

-0.2

-0.4

-0.6

-0.8

*bQ*id*bQ*id*bQ*id

Taxanomic Class: 95%CI

Taxonomic class: 95% CI

Actinopterygii -0.02 -0.314 – 0.275 Gastropoda 0.602 0.164 – 1.039

Agnatha 2.703 -0.062 – 5.467 Holothuroidea 0.38 -0.075 – 0.835

Anthozoa -0.192 -0.557 – 0.173 Hydrozoa 0.251 -0.387 – 0.888

Articulata 0.564 -1.009 – 2.138 Malacostraca -0.374 -0.576 – -0.172

Ascidiacea -0.429 -0.987 – 0.129 Maxillopoda 0.385 -0.524 – 1.294

Asteroidea 0.127 -0.342 – 0.596 Ophiuroidea -0.647 -1.336 – 0.041

Bivalvia -0.128 -0.384 – 0.128 Polychaeta -0.323 -0.553 – -0.092

Cephalopoda 0.462 -1.856 – 2.780 Rhodophyceae -4.04 -5.498 – -2.583

Chondricthyes -0.04 -1.206 – 1.126 Staurozoa 0.47 -1.103 – 2.043

Demospongiae 0.135 -0.652 – 0.922 Stelleroidea 0.153 -0.755 – 1.062

Echinodea -0.523 -1.020 – -0.025

*id

*id

Marlin.ac.uk

UWPhoto.no©Erling Svensenafsc.noaa.gov

Eol.org

Marlin.ac.uk

© OCEANA Juan Carlos Calvín

Response: Species Abundance

Response: Species AbundanceEff

ect S

ize

(di*

)

Photosynth. Filter/ Grazer Scavenger Predator Deposit

1

0

-1

-2

-3

-4

-5

-6

Recovery

<1year 1-2 years >2years

Observation Time

DiversityRichnessAbundance

2.00

1.50

1.00

0.50

0.00

-0.50

-1.00

-1.50

-2.00

-2.50

Effec

t Siz

e (d

i*)

•Type of fishing gear is an important predictor of species richness and abundance

•Despite 5 years since UNGA 61/105, insufficient data to measure recovery times

• Ecosystem indicators to represent ecosystem state and functionality as a whole

•Need for interim measures to identify and protect VMEs

Concluding Remarks

Collaborators:

Erin McClelland

Janelle Curtis

Chris Wood

Katrina Poppe

Acknowledgements

Special thanks to:

Jim Boutillier

Michael Kaiser

Jon Schnute

Buzz Holling

Funding: International Governance Strategy

Sciencedaily.comNationalgeographic.com Sciencedaily.com

Publication bias arises from a variety of sources:

•Not all published studies are included in the analysis

•Some studies never get published

•Some systems have not been studied

Fail-Safe Number:

To determine if publication bias is a potential problem in our meta-analysis we calculated a fail-safe number for each class and for each category which indicates the weight an additional study would need to be to change a finding of significance

•Large fail-safe numbers mean the finding is not prone to publication bias

•Small numbers mean that there may be publication bias

Fail-safe # =

# comparisons

Sum of the reciprocal of the variances for each comparison

sum of squares of the weighted effect size divided by the critical value of a t-test with significance

level 0.05

Publication Bias: Fail-Safe Number

• Only as good as the studies within the meta-analysis• Other factors we did not measure, nor did the studies we used• Very subject to publication bias which may exaggerate outcomes (We

used ‘Fail safe N’ – see other slide)• Personal bias (we made a-priori search and inclusion criteria to try and

reduce this)• Lack of independence between effect sizes