Towards quantifying the structure of the pelagic food web of Northumberland Strait

1

Allan J. Debertin, J.Mark Hanson and Simon C. Courtenay

SOUTHERN GULF OF ST. LAWRENCE COALITION SUSTAINABILITY

Northumberland Strait

What is an Ecosystem?

3

Improving Risk-Assessment

DFO is moving toward Ecosystem-based-management practices:

Improved understanding of ecosystem functions

Improved risk-assessment to manage commercial stocks*

=

EBM requires complex models that focus on multi-species interactions and environmental influences with an overall goal of a sustainable marine ecosystem.

http://www.dfo-mpo.gc.ca/science/Publications/fiveyear-plan-quinquennal/index-eng.html

Structure of research for EBM

Ecosystem Research Initiatives (ERIs) in areas of concern:1) Fish Population and Community Productivity

2) Habitat and Population Linkages,

3) Climate Change / Variability

4) Ecosystem Assessment and Management Strategies

Why is Northumberland Strait important?

•Northumberland Strait is a dynamic productive ecosystem•Lobster is the most valuable fishery in the area. Other fisheries include: scallop, herring, rock crab, American plaice, mackerel, tuna, cod, winter flounder, white hake, alewife, silversides, smelt, oyster, mussel, quahog, soft shell clam, and Irish moss.

•Aquaculture of mussels and oysters

•Tourism and recreational destination – warm summer beaches, boating and sports fishing.

Concerns raised by public and industry in Northumberland Strait

• Declines in commercial fisheries• Invasive Species: Green Crab, species of algae and

tunicates.• Destruction of environment – Scallop dredgers and

construction of Confederation Bridge.• Deteriorating water quality – sediment deposition,

eutrophication, construction of cottages and water barriers.

• Changes in Climate

Before we can begin to understand how human activities impact ecosystem components, we need to first understand how ecosystems function.

??

?

??

?? ??

? ??

Predator – Planktivorous Fish

Bigelow and W.C. Schroeder, 1953 8

Atlantic herring - Clupea harengus

Mackerel - Scomber scombrus

Alewife - Alosa pseudoharengus

Sandlance - Ammodytes americanus

Rainbow smelt - Osmerus mordax

Prey – Zooplankton and small invertebrates

9

Objectives1) Oceanographic conditions of the Northumberland

Strait. – Driving forces of production

2) Distributions of planktivorous fish species and zooplankton. Determine where distinct spatial assemblages occur and if they are explained by environment.

3) Describe the diet composition of planktivorous fish.

11

Sampling

11

Data collected in July-August aboard CCGS Opilio (18.2m). Survey since 2000-2009

12

2009

13

19

Zooplankton Collection

19

Flow Meter

2020

CTD ProbeTemperatureSalinityDensityChl. A Fluor.TurbidityPARO2

Conc.

Environmental Measurements

Data Collected

Data Set Type YearFish Distribution – Biomass and Abundance 2000-09Fish Length Frequencies – Abundance 2005-09

Zooplankton Distribution – Abundance + Biomass 2007-09CTD - Environmental Factors 2008-09

Diet Analysis of Fish Stomachs 2008-09

Objectives1) Oceanographic conditions of the Northumberland

Strait. – Driving forces of production

2) Distributions of planktivorous fish species and zooplankton. Determine where distinct spatial assemblages occur and if they are explained by environment.

3) Describe the diet composition of planktivorous fish.

23

Oceanographic Conditions

0 50 10025 Kilometers

Legend

depthcombined

<VALUE>

<5.0

5.1 - 10.0

10.1 - 15.0

15.1 - 20.0

20.1 - 25.0

25.1 - 50.0

50.1 - 75.0

Depth (m)

Legend

qulandg polygon

Temperature

<VALUE>

20.01 - 22.00

18.01 - 20.00

16.01 - 18.00

14.01 - 16.00

12.01 - 14.00

10.01 - 12.00

8.01 - 10.00

6.01 - 8.00

4.01 - 6.00

2.01 - 4.00

0.00 - 2.00

Temperature (oC)

Bottom-water

Surface-water

Oceanographic Conditions

Summer:July-August

PAR

Turbidity

Chlorophyll a Fluorescence

Dissolved Oxygen

Density

Salinity

Oceanographic Conditions

Legend

Max Fluorescence

<VALUE>

>3.30

3.01 - 3.30

2.71 - 3.00

2.41 - 2.70

2.11 - 2.40

1.81 - 2.10

1.51 - 1.80

1.21 - 1.50

0.91 - 1.20

< 0.90

Chlorophyll a Fluorescence [g/l]

Objectives1) Oceanographic conditions of the Northumberland

Strait. – Driving forces of production

2) Distributions of planktivorous fish species and zooplankton. Determine where distinct spatial assemblages occur and if they are explained by environment.

3) Describe the diet composition of planktivorous fish.

Biota Distributions

Biomass Volume

<VALUE>

0.15 - 0.2

0.1 - 0.15

0.075 - 0.1

0.05 - 0.075

0.025 - 0.05

0.015 - 0.025

0.005 - 0.015

0.002 - 0.005

0.001 - 0.002

0.000 - 0.001

Zooplankton Biomass [g/m3]

29

2008

2009

Legend

qulandg polygon

Copepods (small)

<VALUE>

1,000.01 - 2,000.00

750.01 - 1,000.00

500.01 - 750.00

250.01 - 500.00

100.01 - 250.00

75.01 - 100.00

50.01 - 75.00

25.01 - 50.00

10.00 - 25.00

<10

# individuals/m3

Large-sized copepods Calanus spp.

30

Nova Scotia

New Brunswick

Prince Edward Island

Adult Herring (>22cm)

Nova Scotia

New Brunswick

Prince Edward Island

2008

2009

Legend

qulandg polygon

Copepods (small)

<VALUE>

1,000.01 - 2,000.00

750.01 - 1,000.00

500.01 - 750.00

250.01 - 500.00

100.01 - 250.00

75.01 - 100.00

50.01 - 75.00

25.01 - 50.00

10.00 - 25.00

<10

# individuals/ha

Crab Zoea

Axius-like

Pteropods

Podon sp.

Echinoderm Larvae

Evadne sp.

Legend

qulandg polygon

Copepods (small)

<VALUE>

1,000.01 - 2,000.00

750.01 - 1,000.00

500.01 - 750.00

250.01 - 500.00

100.01 - 250.00

75.01 - 100.00

50.01 - 75.00

25.01 - 50.00

10.00 - 25.00

<10

# individuals/m3

Cheatognaths

<VALUE>

100.01 - 200.00

50.01 - 100.00

25.01 - 50.00

5.01 - 25.00

1.01 - 5.00

0.00 - 1.00

# individuals/m3

Crab Zoea

Axius-like

Pteropods

Podon sp.

Echinoderm Larva Stage I

Evadne sp.

Legend

qulandg polygon

Copepods (small)

<VALUE>

1,000.01 - 2,000.00

750.01 - 1,000.00

500.01 - 750.00

250.01 - 500.00

100.01 - 250.00

75.01 - 100.00

50.01 - 75.00

25.01 - 50.00

10.00 - 25.00

<10

# individuals/m3

Cheatognaths

<VALUE>

100.01 - 200.00

50.01 - 100.00

25.01 - 50.00

5.01 - 25.00

1.01 - 5.00

0.00 - 1.00

# individuals/m3

Patterns in zooplankton composition

Multivariate Data analysis – via PRIMER v 6.0CLUSTER routine. Species assemblages = groups of animals that

co-occur in similar patterns which may be influenced by environmental or biotic variables

-Determines where most significant change occur in species composition - SIMPROF

33

Group average

10

1

10

9

95

75

67

48

9

49

08

01

74

0

83

99

32

87

9

86

18

56

92

2

90

89

61

24

9

16

48

51

75

2

90

18

33

69

0

66

66

19

58

1

66

87

77

83

1

77

48

16

73

6

62

55

3

15

6

23

25

32

60

97

74

78

12

7

15

0

13

51

25

24 5

21

3

39

2

35

93

45

39

0

42

94

74

49

7

52

51

47

42

3

50

02

47

32

0

18

92

03 3

17

5

18

01

07

11

8

20

12

54

31

2

21

03

68

32

5

27

62

35

28

8

28

72

93

34

2

18

33

72

25

0

33

33

22

35

8

40

27

9

40

7

19

22

83

30

1

46

54

45

26

7

21

72

06

48

4

41

84

59

46

7

41

43

79

38

0

50

81

99

97

6

29

64

76

89

5

96

99

52

98

2

94

0

Samples

100

80

60

40

20

0

Sim

ilarit

yTransform: Square rootResemblance: S17 Bray Curtis similarity

2

3 4 5 67 8 9

Legend

assemblagezoo09 60

Assem_60a

D 2

3

4

E 5

6

k 7

8

9

Assemblage Group

Zooplankton Assemblages

k

E

ED

BEST Routine on Primerw = weighted Spearman rank correlation coefficient0 = no correlation 1,-1 = complete correlation

Variables used:

1 – B. Temperature2 – B. Salinity 3 – B. Density4 – S. Temperature 5 – S. Salinity 6 – S. Density 7 - Max Chl. A Fluor.

BEST Routine on Primerw = weighted Spearman rank correlation coefficient0 = no correlation 1,-1 = complete correlation

BEST Variable Match

No. of Var. Variables w 3 B. Temperature, Salinity, Max CHL A Fluor 0.3072 B. Temperature, Max Chl A Fluor 0.3053 B. Temperature, Density, Max Chl A Fluor 0.34 B. Temp, Salinity, Density, Max Chl A Fluor 0.2952 B. Density, Max Chl A Fluor 0.2853 B. Salinity, Density, Max Chl A Fluor 0.284

BEST Routine on Primerw = weighted Spearman rank correlation coefficient0 = no correlation 1,-1 = complete correlation

BEST Variable Match

No. of Var. Variables w 3 B. Temperature, Salinity, Max CHL A Fluor 0.3072 B. Temperature, Max Chl A Fluor 0.3053 B. Temperature, Density, Max Chl A Fluor 0.34 B. Temp, Salinity, Density, Max Chl A Fluor 0.2952 B. Density, Max Chl A Fluor 0.2853 B. Salinity, Density, Max Chl A Fluor 0.284

Nova Scotia

New Brunswick

Prince Edward Island

Rainbow Smelt

Nova Scotia

New Brunswick

Prince Edward Island

Mackerel

Nova Scotia

New Brunswick

Prince Edward Island

A. Sandlance

Gaspereau

Group average

73 490

624

207

793

961

817

408

451

567

587

625

690

692

668

760

839

947

666

881

908

860

856

779

821

801

861

858 29 777

368

404

936

199

301

403

499

444

392

418

217

206

987

833

850

159

898

374

468

164

405

922

180

489

402

423

467

191

152

445

775

643

740

967

831

120

254

504

283

325

109

413

358

360

359

377

379

380

429

901

201

269

410

237

414

459

213

247

312

302

118

965

275

271

952

194

334

226

209

407

311

278

253

276

399

233

169

235

425

267

182

174

288

333

295

372

222

250

293

341

282

212

332

330

287

320

296

303

220

347

192

384

156 37 79 439

190

976

474

168

316

326

189

142

502

733

774

688

940

773

122

471

150

175

619

475

345

484

497

130

508

249

500

476

342

752

454

203

215

921

971

957

816 9 13 24 156 74 124 78 25 3 35 107 83 101

127

932

736

581

583

148 75 125

982

110 23 134

140 53 5 97 22 7 99 60 138 66 135

137

895

853

851

852 47 969

877

737

959

942

879

407 21 525

480

481

483

322

210

390

183

317

939

Samples100

80

60

40

20

0S

imila

rity

Transform: Square rootResemblance: S17 Bray Curtis similarity

2

3

4

5

6

7

1

simproffishassemblage09

Simprof

1

E 2

D 3

4

5

6

7

Assemblage group

E

DD E

E

E E

E

Fish Assemblages

Discussion• Oceanographic conditions in the Strait are complex.

There is three dimensional structuring of the Strait, providing different aquatic habitat at small spatial scale.

• Phytoplankton occurs in highest levels in west and east.

• Distinct zooplankton and fish communities exist, and there is close spatial association between them.

• Zonation of biota could provide a means for fisheries managers to determine how detrimental disturbance will influence particular communities of zooplankton and fish. 42

Discussion• Diet Analysis of Fish – Will provide primary

estimate of consumption towards mass-balanced modelling of NS.

• Other Communities need to be quantified – I.E. Benthic invertebrates in Northumberland Strait.

• Other Seasons – How does the Ecosystem function in Fall, spring, winter?

• Need to continue to monitor Northumberland Strait for future changes.

Acknowledgements

This study would not be possible without the efforts of the captains and crew of the CCGS Opilio, supporting survey staff, and hired students.

SOUTHERN GULF OF ST. LAWRENCE COALITION SUSTAINABILITY