impact of disturbance on habitat recovery in habitat ...annotators: jinshi chen, phil alatalo, mary...

Impact of Disturbance on Habitat Recovery in Habitat Management Areas on the Northern

Edge of Georges Bank

Ecosystem Perturbation Experiment

Woods Hole Oceanographic InstitutionScott Gallager, Steve Lerner, Cameron Fairclough

Fishing CommunityLund’s Fisheries: Wayne Reichle, Jeff Kaelin,

Captain Brady of the F/V Jersey Cape

Annotators: Jinshi Chen, Phil Alatalo, Mary Carman, Patti Keating

2016 – 2018 Scallop Research Set-AsideNOAA-NMFS-NEFSC-2016-2004548

Objective

To complete a series of high resolution Before-After Control-Impact (BACI) habitat

characterizations at three impact scales (heavy, low, none) to evaluate ecosystem and

habitat resiliency

Survey-HabCamV5

*Stereo machine vision cameras*Side scan sonar (50m either side)*CPICS Plankton Imager*CTD*Roll, pitch yawl*7 kts*8 images/sec*Real-time processing on ship*Deep Learning classifier

Impact-Commercial dredge

Went with one level of impact ~20%

Hypotheses

Northeast Reduced Impact Habitat Management Area (NERIA) Areas surveyed:

NERIA: 349.50 km2

NEHMA: 700.36 km2

EGS: 439.06 km2

# Image pairs taken: 852,145Annotated: 12% manual

100% Automated

Total area imaged: ~ 851,000 m2

All images auto-annotated for habitat

Eastern Georges Shoals (EGS)

Northeast Habitat Management Area (NEHMA)

2017 RSA Survey HabCamV5

Total: 44,977,948 Total: 15,549,936

Total: 851,013

Northeast Reduced Impact Habitat Management Area (NERIA)

Gridded to 30 m squares

Ordinary Krigingwith depth as co-variate

Also comparing withEmpirical Bayesian kriging

Bathymetry with Epifauna Contours

60

7080

90

50

40

30

100

70

Exploitable Scallops with Gravel (white) , Epifauna (black) , Shell Hash (brown) Contours

2017 Survey July 20-24

EGS NEHMA

NERIA

Numbers of Scallops

Exploitable Medium Small All Scallops

All Areas 53,303,486 21,755,609 1,575,510 76,634,605

NERIA 44,977,948 15,549,936 851,013 61,378,897

NEHMA 1,260,245 1,029,840 184,850 2,474,935

EGS 7,065,293 5,175,833 539,647 12,780,773

Biomass of Scallops (MT)

Exploitable Medium Small All Scallops

All Areas 14,731.29 687.75 2.49 15,421.53

NERIA 13,158.13 493.36 1.49 13,652.98

NEHMA 299.06 31.61 0.39 331.06

EGS 1,274.10 162.78 0.60 1,437.48

BACI Experimental Sites2012-2016-2017-2018

Impact

1 nm in length10 m wide

Dredge tracks- 10 passesHabCamV5Control tracks

Impact area under the dredge tracksControl area outside the dredge tracks

HabCamV5Treatment tracks

July 2016 pre-impact broad scale and fine scale surveys

July 2012 Initial broad scale and fine scale surveys, part of RSA project (V2)

October 2016 pre-impact fine scale survey, control surveyImpact with scallop dredge

June 2017 10 mo after impact fine scale survey

July 2018 22 mo after impact fine scale survey

Experimental Design for BACI sitesSite 1

Site 2Site 3

Site 4

Site 5

Site 6

Convolutional Deep Neural NetworkClassification

Two approaches

*Holistic- complete image (substrate)*Targets- segmentation (scallop,

seastar, fish, sand dollar, etc.)

*8 images /sec*15 classes (so far)*90-97% accuracy

(class dependent)*runs on NIVIDIA Jetson TX2

5 classes of substrateScallopSeastarRound fishFlat fish(fish to 31 species manually)

Single variate analyses1. number of species (S)2. number of individuals (A)3. Shannon Weiner diversity (H’)4. Margalef’s Richness (d)5. Pielou’s Eveness index (J’) 6. Simpson’s Dominance (λ)

Multivariate analyses (in progress)1. Square root transformed2. Hierarchical clustering to identify sample groupings based on the Bray-Curtis index of similarity and Euclidean distance3. non-metric Multi-dimensional Scaling plots, nMDS4. ANOSIM (Analysis of Similarity) routine was used to test the null hypothesis that there are no differences between biological communities among controls and different times before and after impacts5. significance testing on selected abiotic and biotic variables using two-way Analysis of Variance (ANOVA)

bu

shel

sb

ush

els

bu

shel

s

Tow #

Tow #

Tow #

Bushels removed = 6.5

Bushels removed = 470


Bushels removed = 2



Scallops removed at each Site

SubstrateEpifaunaSandGravel

1-D Habitat Suitability Model for scallop

Organism54 Seastar122 Fish2 Sculpin108 Cod92 Haddock8 Skate

October 2016 -Before Impact- Site 1

SubstrateGravelSandEpifauna

3340.2/m2

100%epifauna

October 2016 -Immediately After Impact - Site 1



200.004/m2

23%epifauna

Removed 6.5 bushels scallops

July 2017 -10 mo After- Site 1



4340.17/m2

92%epifauna

Site 2

Site 3 Site 1

Site 4

Site 5

Site 631 species of fish

BACI Experimental Sites- HAPC 2016-2018

~1 nm boxesas Control

Treatment1 nm x 10m

Site 6Site 3

Site 1

Site 2

Site 4

Site 5

HabCam Survey Tracks-10 passes inside Treatment rectangles, 0.5 nm grid outside Treatment

Surveyed 2016 (Before), 2016 (After), 2017 (After), 2018 (After)

Haddock(Before)

Atlantic Cod(Before)

Little Skate(Before)

Site 1: Epifauna Site 2: Gravel Site 3: Gravel

Site 4: Gravel/Epifauna Site 5: Sand Site 6: Sand/Gravel

Before After 10 mo 22 mo

Co

ntr

ol

Trea

tmen

t

Site 1 only significant change, after 10 mo > 90% recovery

Mean +/- 1 SD

Before After 10 mo 22 mo Before After 10 mo 22 mo




Impact on Dominant SubstrateRecovery to 90%in 1 year

Site 1: Haddock Site 1: Atlantic Cod

Site 1: Monkfish Site 1: All Fish



# /

m2

# /

m2

# /

m2

# /

m2

Trea

tmen

tC

on

tro

l

Recovery to x4in 1 year

Mean +/- 1 SD

substrate scallop seastar fish sculpin cod haddock skate

Site 1 Before 100% epi 0.2 54 122 2 108 92 8

After 44% epi 0.004 40 15 1 12 21 2

10 mo 92% epi 0.17 139 10 5 28 15 1

22 mo 100% epi 0.07 36 1 10 0 1 1

Site 2 Before 55% grav 0.80 10 31 15 19 48 18

After 52% grav 0.03 6 0 0 0 0 0

10 mo 41% grav 0.93 86 19 3 4 21 10

22 mo 55% grav 0.88 50 11 1 10 10 8

Site 3 Before 96% grav 4.17 89 203 0 4 11 14

After 90% grav 0.47 30 1 1 1 3 1

10 mo 88% grav 5.82 106 20 4 2 113 3

22 mo 91% grav 3.18 329 0 1 4 9 0

Site 4 Before 56% grav 0.001 11 107 0 6 43 27

After 52% grav 0.0004 0 0 0 0 0 2

10 mo

22 mo 58% grav 0.002 9 29 1 3 10 1

Site 5 Before 44% sand 0.29 70 1 1 1 5 10

After 53% sand 0.02 0 3 1 1 0 1

10 mo 46% sand 0.31 0 3 1 0 0 1

22 mo 28% sand 0.29 5 10 0 2 3 4

Site 6 Before 98% grav 0.31 0 6 1 0 0 2

After 97% grav 0.002 0 0 0 0 0 0

10 mo 62% grav 0.70 92 55 2 5 161 22

22 mo 91% sand 0.55 26 87 0 0 50 15

Strong evidence of scallop movement intoImpact sites

No evidence of new scallop recruitment within the two years

Summary and ConclusionsSummary1) A BACI whole ecosystem experiment was started in 2016 in Closed Area II, HAPC for the purpose of

examining what level of impact from scallop dredges would cause irreputable damage in anarea that is considered essential fish habitat for Gadids and other commercially important species.

2) Six sites were established in different habitats, 1 nm in length and 10 m wide, and intensively surveyed multiple times before impact and three times ( ~once per year) following impact. Impact consisted of towing a commercial dredge 10 times down the same transect.

Conclusions1) Only Site 1 in a 100% epifauna/mussel/tunicate community was severely impacted as

observed by stereo optical imaging and side scan sonar.2) Biodiversity was significantly reduced (p < .001) from a H’ score of 12.1 to 1.3.3) Within 10 months biodiversity returned to 93% of original form: H’= 11.64) Some species appeared to be stimulated by the impact (cod ^ by factor of 4) while haddock

rebounded to ~ 0.5x original level.

5) Limited trips may be possible in all areas of the HAPC except Site 1, where the epifaunal cover is extremely sensitive to mechanical damage.

impact of disturbance on habitat recovery in habitat ...annotators: jinshi chen, phil alatalo, mary...

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