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Funded by :. Hosted by The Marine Biological Association of the UK. An ecosystem approach to long-term coastal observing – the western English Channel. Frost, M. T., Jenkins, S. R., Hinz, H., Genner, M. J., Sims, D. W., Budd, G., Araújo, J. N., Hart, P. J. B., Southward, A. J. & Hawkins, S. J.

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Hosted by the marine biological association of the uk

Funded by:

Hosted by The Marine Biological Association of the UK

An ecosystem approach to long-term coastal observing – the western English Channel.

Frost, M. T.,Jenkins, S. R., Hinz, H., Genner, M. J., Sims, D. W., Budd, G., Araújo, J. N., Hart, P. J. B., Southward, A. J. & Hawkins, S. J.

Workshop on Coastal Observatories.

Best practice in the synthesis of long-term observations and models

Liverpool University, October 17th – 19th, 2006.


Hosted by the marine biological association of the uk

MBA long-term observations

  • long history (>100 yrs) of MBA in situ observations

1899

The Plymouth research vessels 1902-1953

1936

“Long-Term Oceanographic and Ecological Research in the Western English Channel”. (Southward et al., Adv. Mar. Biol., 2005)


Hosted by the marine biological association of the uk

MBA long-term observations

1975

The Plymouth research vessels 1953-2006

“The biomass figures……are intended to provide basic data for following changes in the bottom fauna in the future”

2006

(Holme, N.A. (1953)). The biomass of the bottom fauna in the English Channel off Plymouth. JMBA. 32:1-49


Hosted by the marine biological association of the uk

Long-term monitoring

  • ‘Growing concern about human influence on marine ecosystems conflicts with our inability to separate man-made from ‘natural’ change. This limitation results from lack of adequate baselines and uncertainty as to whether observed changes are local or on a broad scale. Long-term monitoring programmes should be able to solve both these deficiencies’ (Duarte et al, 1992. Nature)

  • ‘long-term changes, such as those of climate change, can best be understood using long-term data sets, which can be costly and require long-term investment.’ (POST, 2004)


Hosted by the marine biological association of the uk

Long-term monitoring

  • Research definition:

  • “..research occurring over decades or longer”

  • Monitoring definition (Parr et al):

  • “…the time scale which enables signals of environmental change to be distinguished from background noise”

  • practical definition:

  • “..any sites where there is a commitment to maintain scientific and monitoring programmes beyond the usual length of a scientific research programme”.


Hosted by the marine biological association of the uk

Long-term monitoring

  • Specifically we are interested in:

    • what is the current state of the ecosystem?

    • How has the ecosystem changed?

    • How do interactions of climate and fishing effect ecosystems?

    • short term forecasts of ecosystem state

    • (PML, MBA – SO10 document)


Hosted by the marine biological association of the uk

The western English Channel

Major long-term sampling stations off Plymouth

Regular intertidal stations

From Southward et al., Adv. Mar. Biol., 2005


Hosted by the marine biological association of the uk

MBA Time Series: English Channel

Temperature and Salinity E1 1902-1987, 2001-

Nutrients E1 1921-1987, 2001-

Phytoplankton E1 1903-1987, 2001-

Primary production E1 1964-1984

Zooplankton E1, L5 1903-1987, 1995-2000

Planktonic larval fish E1, L5 1924-1987, 1995-2000

Demersal fish L4 1913-1986, 2001-

Intertidal organisms various 1950-1998, 1997-

Infaunal benthos (intermittent) L4 1922-1950

Epifaunal benthos (intermittent) L4 1899-1986

n.b. There are many gaps in these series


Hosted by the marine biological association of the uk

WEC: Physical changes

  • Fluctuations in sea temperature over 20th Century: both warm and cool periods

  • SST may be linked to solar activity- sunspots (Southward, 1980) and intensity of North Atlantic Oscillation (Sims et al., 2001; Stenseth et al., 2003)

  • Acceleration of warming (~ 1 ºC) since 1987 when time series stopped (later slide RSDAS data)

  • Warmer winter minimum temperatures (< 10 ºC now rare)

  • Predicted warming scenarios of 1.4 - 5.8 ºC over the next 100 years (Schneider, 2001)


Hosted by the marine biological association of the uk

Sea-surface temperature

offshore Plymouth 1871-2000

13.5

13.5

13.0

13.0

12.5

12.5

Mean annual SST (ºC)

Mean annual SST (ºC)

12.0

12.0

11.5

11.5

11.0

11.0

1905

1905

1925

1925

1945

1945

1965

1965

1985

1985

2005

2005

Year

Year

Data source: Met Office Hadley Centre

Grid square 50-51ºN, 4-5ºW


Hosted by the marine biological association of the uk

CPR

L5

Source: Coombs & Halliday, 2004

Note: work also carried out on CPR vs L4 (John et al, Journal of Sea Research. 2001)

Monthly abundance of pilchard eggs from CPR sampling in the English Channel and adjacent areas and MBA station L5 sampling off Plymouth 1958-1980


Hosted by the marine biological association of the uk

Sagitta setosa (warm water)

50

12

Sagitta elegans (cold water)

10

40

8

30

S. elegans (monthly mean x1000)

6

S. setosa (monthly mean x1000)

20

4

10

2

0

0

2000

1920

1940

1960

1980

Year

  • Originally thought that changes due to < inorganic nutrients due to reduced Atlantic inflow (Russell cycle) (leading to <PP etc)

  • But now shown nutrients reduced after community changed I.e. symptom not cause (and nutrients not reduced as dramatically as previously thought)


Hosted by the marine biological association of the uk

Source: L5 data

Pilchard eggs

Flatfish larvae

  • Climate signal for egg abundance? – lags behind temp trend by several yrs.

  • Climate signal may then propagate down (top down forcing) as pilchard juveniles and adults prey on other smaller plankton

  • can be difficult to interpret plankton signals


Hosted by the marine biological association of the uk

WEC Fish

8000

Herring - Clupea harengus

  • 1930s (warming) stocks of herring, collapsed Drivers: Climate + fishing?

7000

6000

5000

6000

Pilchard - Sardina pilchardus

Catch (tonnes)

4000

5000

3000

2000

4000

1000

Catch (tonnes)

3000

0

2000

1920

1930

1940

1950

1960

1970

1980

1990

2000

Year

1000

  • Herring ‘replaced’ during warmer 1950s by pilchard - never returned in abundance

  • Driver: over-fishing at regional scale

0

1920

1930

1940

1950

1960

1970

1980

1990

2000

Year

  • Mackerel increase but quickly ‘fished down’

  • Last 20 years: increase in mean annual sea temperature = pilchard catches increased dramatically

  • Drivers: climate & fishing?

80000

Mackerel - Scomber scombrus

70000

60000

50000

Catch (tonnes)

40000

30000

  • evidence of climate influence from phenological studies (squid migrate earlier in warm years with positive NAO; Flounder migrate to sea earlier in cooler years,)

20000

10000

0

1920

1930

1940

1950

1960

1970

1980

1990

2000

Year


Hosted by the marine biological association of the uk

Demersal fish - separating Fishing and climate

Southern Species from English Channel

Mean CPUE [log10(x+1) transformed

Source: MECN Final Report and Genner et al, 2004)

  • a) non-commercial species show +ve response to increase in SST

  • b) commercial species initially show similar response (1913-22 & 1950-57) but then any climate signal is overridden by fishing effects.

  • - Similar pattern observed in Bristol Channel but with different subset of species responding (local interactions / restraints)

  • Bottom-up forcing: abundance linked to temp-dependent resources?


Hosted by the marine biological association of the uk

In Situ observations: Other

  • Long-term data has also been used to look at:

    • nutrient cycles (Joint et al, JMBA. 1997; Jordan & Joint, ECSS. 1998).

    • phytoplankton & Productivity (1964-84 main data collection)

    • Work on benthos is ongoing at present (ALSF)

    • Intertidal ecosystem particularly in response to climate (MarCLIM)

  • Current work now on ecosystem models

  • “Modelling food web interactions, variation in plankton production, and fisheries in the western English Channel ecosystem” Araujo et al (2006)


Hosted by the marine biological association of the uk

Ecosystem Models

  • METHODS (kind of)

  • EwE (Ecopath with Ecosim) software

  • Model built representing ecosystem in 1994 (warm period)

  • structure / basic parameters of 1994 model used as baseline for 1973 (cold period) model and time series data up to 1999. Building past model and running to current allows modeller to monitor how biomasses have changed through time – model predicted biomasses can then be compared with stock assessment estimated biomasses – input parameters are then modified to get better fit (tuning).

  • 50 functional groups used to represent ecosystem*

  • time series of biomass ‘built’ + on PCI (used to estimate biomass forcing function driving PP) and zooplankton abundance (from CPR).

  • series of model runs with and without PP and with variations in parameters to assess relative roles of fishing, trophic interactions (v) + system productivity

  • v = maximum mortality predator can inflict on prey relative to baseline mortalities. low values = bottom-up control , high values = classic predator prey dynamics (Lotka-Volterra)


Hosted by the marine biological association of the uk

Ecosystem Models

  • Results

  • Best fit for model included PBF (increases accuracy of model estimates by 25% compared with fishing only) - bottom-up mechanism contributing to production at high trophic levels.

  • including V (vulnerability) also improved accuracy of model

  • Biomass model of PP shows oscillations / peaks in early 1980s / late 1990s.

  • zooplankton similar trend but peak at end of 1980s (coincides with small peak in phytoplankton)

Source: Araujo et al, 2006. Figure 2


Hosted by the marine biological association of the uk

  • Conclusions

  • although PP kept increasing, many fish groups decreased after 1980s as did zooplankton

  • zooplankton not ‘tightly controlled’ by PP but correlated with SST.

+ve - not Sig.

+ve + Sig.


Hosted by the marine biological association of the uk

Ecosystem Models

many fish groups also increased in these years peaking during the 1980s e.g sole, plaice, cod increased (but catch) increased showing factors other than fishing as important

Biomass (Thousands of tonnes)

Catches (Thousands of tonnes)

Source: Araujo et al, 2006. Figure 2


Hosted by the marine biological association of the uk

Conclusions & WEC observatory

  • mixture of bottom-up and top down forcing on WEC ecosystem with climate playing increasingly important role

  • total ecosystem approach required in order to gain and understanding of ‘system drivers’ (e.g. Cushing (1961)) - observatory will aim to provide measurements of wide range of parameters

  • Linking in situ measurements to other observatory measurements enables:

  • filling in gaps (e.g. temp)

Satellite data (RSDAS)

E1 restarted in 2001


Hosted by the marine biological association of the uk

Web (Webmap server)

NERC datagrid interface

Western Channel Observatory

Data archive (BODC / DASSH, local SQL / Access)

Virtual Observatory

Modelling

ERSEM

Met Office (NCOF)

Data

Knowledge Transfer (via MECN)

Remote Observatory

in situ sampling (L4, E1, L5, buoy, etc.)

long-term time-series

scientific investigation (focus on ecosystem based studies)

Remote Sensing

SST, Ocean Colour

Other sensors


Hosted by the marine biological association of the uk

Observatory benefits

  • ground truthing for remote measurements (e.g. John, 2001 for L4:CPR). Issues with remote measurements of productivity/chlorophyll.

  • coordination and synthesis – modelling often reliant on fairly disparate datasets (various places collected in various ways at various times).

  • needs to be standardisation and methodological / technological audit trail.

  • WIDER NETWORKING TO INCREASE CAPACITY FOR DATA SYNTHESIS BEYOND WEC i.e.

    • Other NERC observatories

    • Other monitoring bodies (MECN)


Hosted by the marine biological association of the uk

MECN NETWORK

  • 18 Partners:

    • DEFRA*

    • MBA

    • SAHFOS

    • PML

    • PEML

    • Dove ML

    • SAMS

    • SOS Bangor

    • DARD

    • CEFAS

    • FRS

    • POL

    • SOC

    • SMRU

    • JNCC*

    • BODC*

    • Met Office

    • EA*


Hosted by the marine biological association of the uk

Observatory benefits

  • synthesis of data beyond WEC (continued)

    • European (MarBEF): Largenet

e.g. Long-term pelagic stations in Europe. (Source: Karen Wiltshire, MECN Workshop, DEC 2005)