Understanding

seabed ecology:

climate, fisheries and food

Chris Frid,

Peter Garwood & Leonie Robinson

The North Sea is a semi-

enclosed, highly productive

(>300 g C m-2 yr-1), relatively

shallow, temperate sea.

A variety of human activities

affect the marine ecosystem:

• nutrient enrichment,

• coastal developments,

• the fisheries.

The North Sea

Fish as food

World catch Around 85-90 million tonnes per year

Importance as protein Globally accounts for around 15% of the protein in the diet (7-

8% in industrial countries)

Other major health benefits PUFA, Omega-3

Global population Growing at around 1.8% per annum

North Sea accounts for around 5% of global catch

Infamous quotes

"The cod fishery, the herring fishery, the pilchard fishery, the mackerel fishery, and probably all the great sea fisheries, are inexhaustible".

Thomas Henry Huxley, (1825-1895)

President of the Royal Society, 1884.

0

1000

2000

3000

4000

5000

6000

7000

8000

1920

1926

1932

1938

1944

1950

1956

1962

1968

1974

1980

1986

1992

Cod

Haddock

Whiting

North Sea Gadoid population sizes in the 20th Century(biomass 1000‟s tonnes)

Gadoid outburst in 1960’s main change in

terms of numbers.

Continual shift towards smaller size.

Sole and plaice populations fairly stable

Common dab, LR dab and lemon sole increase

1

10

100

1000

10000

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

Plaice Sole

Lemon sole Common dab

Long-rough dab

North Sea flat-fish population sizes in the 20th Century(biomass 1000‟s tonnes)

0

5000

10000

15000

20000

25000

30000

35000

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

Echinodermata CrustaceaAnnelida MolluscaOther benthos

Benthos (103 tonnes) consumed by 8 demersal fish species

Increase in benthos consumed from 23 Mt

in 1970 to 29Mt in 1993

Due to altered stock sizes and size spectrum

Variation

Fishing pressure varies

Fish stocks (predation) varies

Climate varies

Productivity varies

Global Climate Change

•Clear evidence of warming

•Rate of change is increasing

•Kicks off in late 1970s

CPR silk greenness –

index of phytoplanktonM

ea

n G

ree

nn

ess

Year

Month

2000199119821973196419551946

JanJanJanJanJanJanJan

6

5

4

3

2

1

0

Time Series Plot of Mean Greenness

The Dove Time Series:

Macro-

benthos –

two stations

M1 and P

P

M1

PM1

Newcastle

Benthos Buchanan initiated in

1971-72

Two stations remain

from an extensive grid

6 and 12 miles offshore

50 and 70 m deep

M1 sampled March and

September

P sampled March

M1- 35 years of “natural” variationSince September 1972

Have missed 3 September (1987,1991,

2002) and 1 March (1998) sampling

516 taxa recorded

Genera richness: Sept: mean 105 (70-129)

Mar: mean 94 (63-124)

Abundance: Sept: mean 605 (224-1310)

(per grab) Mar: mean 380 (104-720)

Some biology

Worms dominate,

with brittlestars,

burrowing urchins and

clams (bivalve molluscs)

Levinsenia

gracilis

Prionospio

ThyasiraAmphiura

M1 After 35 years: Top generaMean

indiv. m2

1 Prionospio 495.11 10.09%

2 Levinsenia gracilis 257.79 5.26%

3 Chaetozone setosa 198.19 4.04%

4 Amphiura 193.54 3.95%

5 Thyasira 191.03 3.89%

6 Abra 186.98 3.81%

7 Mysella bidentata 158.62 3.23%

8 Phoronis muelleri 153.67 3.13%

9 Pholoe 150.86 3.08%

10 Nuculoma tenuis 140.81 2.87%

TOTAL 4906.64 43.35%

M1 Total Abundance –

altered variability and mean?To

tal N

Year

Month

200520021999199619931990198719841981197819751972

SepSepSepSepSepSepSepSepSepSepSepSep

14000

12000

10000

8000

6000

4000

2000

0

Time Series Plot of Total N

M1 Genera Richness – A shifted baselineG

en

era

ric

hn

ess S

Year

Month

200520021999199619931990198719841981197819751972

SepSepSepSepSepSepSepSepSepSepSepSep

130

120

110

100

90

80

70

60

Time Series Plot of Genera richness S

Changes in time: M1

No significant change in total abundance

over time nor between decades

Indication of altered variability and multi-

annual shifts

Significant change (ANOVA p<0.001) in

genera richness, significantly higher in the

1990s and 2000s.

P- 36 years of variation

Since 1971

Have missed sampling once (1998)

262 taxa recorded from 183 genera (or

higher)

Genera richness: mean 53 (35-76)

Abundance: mean 454 (165-1023)

(per grab)

The Top Ten

Taxon Mean

Abundance

(ind. m-2)

SD %

contribution

cumulative

%

contribution

1 Heteromastus 659.44 360.87 29.01 29.01

2 Levinsenia 208.09 190.38 9.15 38.16

3 Prinospio 151.11 136.02 6.65 44.81

4 Chaetozone 101.60 89.67 4.47 49.28

5 Paramphinome 97.77 243.66 4.30 53.58

6 Ophelina 90.21 69.99 3.97 57.55

7 Nemertea spp. 73.99 51.24 3.25 60.80

8 Harpinia 73.40 52.79 3.23 64.03

9 Abra 70.24 56.15 3.09 67.12

10 Amphiura 61.46 97.22 2.70 69.83

P Total abundance (ind. m2)

Year

N

200119951989198319771971

5000

4000

3000

2000

1000

Time Series Plot of N

P Genera Richness

Year

S

200119951989198319771971

80

70

60

50

40

30

Time Series Plot of S

Changes in time: P

Abundance was high in the early 1980s

Both abundance and richness show a

decline in the late 1980s-early 1990s

(?regime shift)

Both abundance and richness in the 00s

were similar to the 70s

Biological detail

Top 2 taxa at M1D

ata

Year

Month

200520021999199619931990198719841981197819751972

SepSepSepSepSepSepSepSepSepSepSepSep

2000

1500

1000

500

0

Variable

Prionospio all

Levinsenia gracilis

Time Series Plot of Prionospio all, Levinsenia gracilis

The top three at P

Year

Da

ta

200119951989198319771971

1800

1600

1400

1200

1000

800

600

400

200

0

Variable

Prinospio total

Heteromastus filiformis

Levinsenia gracilis

The North Sea Phase Shift

A widely described change in the

planktonic components occurred around

1987-8

Was there a phase shift in the benthos?

Journey into Phase Space..

Looking in Phase Space

A search in n-dimensional phase space

1983

1986

2001

1977

MDS ordination for PStn P 1971-2006

Transform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

19711972

1973

197419751976

19771978

1979

1980

19811982

1983

1984

1985

1986

1987

1988

19891990

1991 1992

1993

1994

19951996

1997

1999

2000

2001

2002

2003

2004

2005

2006

2D Stress: 0.16

Shifts in community structure at P

The clearest pattern is the trend

from 1970s to 2000s from left to

right

The 1980s are the most dispersed

decade with 1988 an outlier

The biological assemblage has

changed over time and is now

distinct from that at the

start of the series

Drivers of Change Food

Fishing

Climate variation

Climate change

Food as a driver?Stn P 1971-2006

Transform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

Green-22

3

1

2D Stress: 0.16

Fishing History - ICES 39E8 (Stn P)

Year

Sw

ep

t a

rea

200119951989198319771971

25000

20000

15000

10000

5000

Time Series Plot of Swept area

Fishing Pressure

Stn P 1971-2006Transform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

Fishing History1

2

3

4

5

6

2D Stress: 0.16

Climate change - SSTStn P 1971-2006

Transform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

SST LMH2

1

3

2D Stress: 0.16

MDS ordination for M1Transform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

Month9

3

19721973

1973

1974

1974

1975

1975

1976

1976

1977

1977

1978

1978

1979

1979

1980

1980

1981

1981

1982

1982

1983

1983

1984

1984

1985

1985

1986

1986

19871988

19881989

1989

1990

1990

1991

1992

1992

1993

1993

1994

1994

1995

1995

1996

1996

1997

19971998

1999

1999

2000

2000

2001

2001

2002

2003

2003

20042004

2005

2005

2D Stress: 0.16

March – Decadal progressionTransform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

Decade7

8

9

0

1973 1974

1975

1976

1977

1978

1979

1980

19811982

19831984

1985

1986

1987

1988

1989

1990

1991

199219931994

199519961997

199920002001

2002

2003

2004

2005

2D Stress: 0.14

September – Decadal progressionTransform: Log(X+1)

Resemblance: S17 Bray Curtis similarity

Decade7

8

9

0

1972

19731974

1975

19761977

1978

19791980

1981

1982

1983

1984

1985

1986

1988

1989

1990

1992

1993

1994

1995

199619971998

1999

2000

2001

2003

2004

2005

2D Stress: 0.14

35 years of study shows..•Decadal scale variation in total abundance,

species richness and community

composition at both stations

•No trend in abundance i.e. due to warming

or eutrophication at either station

•„Trend‟ in community composition and

hence deliver of ecological functions at both

stations

•Indication of importance of fishing (P),

climatic drivers and/or food supply in

setting limits on abundance and richness

And where next?

We continue, in conjunction with

Newcastle University, to extend

the time series

We have also, in 2006, initiated

benthic sampling twice a year at

two of the Coastal Observatory

stations

Acknowledgements For initiating the series Jack Buchanan

and for collecting the data: various PhD students and Peter Garwood, masters and crew of the RV Bernicia

For funding it at various times: DEFRA (DoEnv, DETR), NERC, University of Newcastle

For intellectual input: Robin Clark, Kirsty Nicholas, Odette Paramor.