Download Variability and shifts in marine ecosystems

Variability and shifts in
marine ecosytems
Keith Brander
ICES/GLOBEC Coordinator
Keith Brander IMBER-GODAE 12 June 2007
People are interested in
climate change and in
changes in marine
ecosystems.
Keith Brander IMBER-GODAE 12 June 2007
Keith Brander IMBER-GODAE 12 June 2007
Rapid spread of tropical species
along the continental slope
Is the rate of biological shift
commensurate with the rate of ocean
climate shift?
Should we say:
“the ecosystem is changing”
or
“the ecosystem is moving”?
What about the conservation of
ecosystem functions? Is that
allowed to move too?
Is fish production affected?
Should we be managing differently?
Keith Brander IMBER-GODAE 12 June 2007
1 Biogeographic shifts of ~
50km y-1 in NE Atlantic
2 Increases in number of
warm water species
Attributed to (i) advection and (ii) change in local properties
i.e transport of both biota and heat, salt etc.
(Issue of Eulerian vs Lagrangian
observation)
Keith Brander IMBER-GODAE 12 June 2007
Other taxa have also shifted at similar rates
Changes in range of copepod species - Beaugrand et al. 2002 Science
Based on 176,778 CPR samples.
Southern shelf edge species
Psuedo-oceanic temperate species
Euchaeta gracilis, Euchaeta hebes, Ctenocalanus
vanus, Calanoides carinatus
Rhincalanus nasutus, Eucalanus crassus, Centropages
typicus, Candacia armata, C. helgolandicus
Keith Brander IMBER-GODAE 12 June 2007
Other areas have shown similar rates
Sea Surface Temperature
Northward spread of cod at West
Greenland from 1917-1939
3
2.5
2
1.5
1
0.5
1910 1915 1920 1925 1930 1935 1940
Keith Brander IMBER-GODAE 12 June 2007
The cod stock at Greenland is recovering as
conditions there get warmer.
A positive effect which poses some management
questions:
• How should it be managed?
• What about the shrimp fishery?
• What about sharing with Iceland?
• Could Greenland help recovery of Canadian stocks?
• IPCC predicts slow warming at Greenland
Keith Brander IMBER-GODAE 12 June 2007
Keith Brander IMBER-GODAE 12 June 2007
Keith Brander IMBER-GODAE 12 June 2007
Keith Brander IMBER-GODAE 12 June 2007
Cod recruitment at Greenland
Years 1971-97
From ICES CM 2001/ACFM:20
300
84
Greenland R
250
200
73
150
85
100
50
0
0
2
4
6
8
10
0 group abundance Dohrn Bank
Keith Brander IMBER-GODAE 12 June 2007
and E Greenland
12
Decline of the Baltic cod stock
will this continue?
• Less inflow of Atlantic water
• Falling salinity
Keith Brander IMBER-GODAE 12 June 2007
Recovery of Gulf of St Lawrence cod stock
– has begun now the environment has improved
Recent rise in
temperature
• 2004 year class is biggest
since 1980
• Survival is higher
• Seal predation is lower
Keith Brander IMBER-GODAE 12 June 2007
Profondeur – Depth (m)
Mois - Month
Figure 2: Monthly temperatures by depth for the Northern Gulf with
recaptures of tagged cod (yellow box-plots).
Keith Brander IMBER-GODAE 12 June 2007
Regime shifts in N Pacific – are the (physical and
biological) processes non-linear?
Note use of regional synoptic indices
Keith Brander IMBER-GODAE 12 June 2007
Data sources, current trends, attribution of
causes
Sources
•Time series of commercial fish species for many areas
•Time series (near-surface mesozooplankton) from CPR for some areas
Trends
•Northward distribution shifts (fish, plankton) in NE Atlantic
•Decline in abundance of many fish species
Attribution
•Physical forcing is both local and via large scale advection
•Biological forcing could be top-down or bottom-up
•Very strong direct human impact through fishing
Keith Brander IMBER-GODAE 12 June 2007
Data and analyses needed
•
Improved availability and presentation of trends and
changes in ocean properties (at many scales)
•
Climate scenarios which include ocean properties
(temperature, salinity, advection, upwelling, stratification)
•
Compilation and interpretation of comparative regional data
to test the attribution of change
Keith Brander IMBER-GODAE 12 June 2007
Gaps
•
•
•
Few time series of marine biota are suitable for detecting
and attributing effects of climate change (whether in
distribution, abundance or phenology)
(mention Perkinsus – oyster parasite, as a good example
which combines observation and modelling to determine
causes)
The geographic and biotic coverage of this presentation is
itself limited
Keith Brander IMBER-GODAE 12 June 2007
Sensitivity/vulnerability
•
Some marine ecosystems are topographically bounded, but
others (e.g. planktonic systems) are not, therefore they can
shift distributions quickly.
•
Shallow areas are more vulnerable to changes in
temperature and salinity (the communities there are also
more adapted to extremes)
•
Coastal areas are vulnerable (and relatively well studied),
but are usually impacted by many anthropogenic factors
other than climate change
Keith Brander IMBER-GODAE 12 June 2007