response and recovery potential of benthic marine ecosystems
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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
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