Environment Institute
Science Seminar Series 2009
Final Seminar Sem 1: 29 June – 12pm
Policy responses to a drying climate may
save Adelaide’s kelp forests
Presented by: Associate Professor Sean Connell

is playing an increasing role:
 funded and published
 how data are acquired and interpreted

In a race for $ and the headlines needed to lobby $...
“Since the Jamaica story was an anomaly, it makes a poor foundation
for general models of reef ecology” Bruno et al. 2009 Ecology

If theory ladnness can be recognised as a possible model

Policy

1. Reconstruction of a lost-baseline
2. Drivers of habitat-loss
3. Solutions for restoration
4. Contingencies via biogeography
5. Contingencies via climate
an immersion of science

#1. Baseline
N
Australia
Adelaide
Urban 1
South
Australia
Agricultural 1
Victor Harbor
Urban 2
Adelaide
Natural 2
Agricultural 2 Natural 1
25 km
South North
Sites

#1. Baseline
Cape Leeuwin
Encounter Bay

#1. Baseline

# 2. Causes

# 2. Causes
0.80 Heavy rainfall 0.40
Light rainfall
Mean NOx conc. light rainfall (mg L-1)
0.60 0.30
Mean NOx conc. heavy (mg L-1)
0.40 0.20
0.20 0.10
0.00 0.00
Urban Agricultural Natural
Catchment type

# 2. Causes
20
Urban Agricultural Natural
Canopy-formers
mean: 5.9 mean: 9.5 mean: 11.4
PATCH-SIZE FREQUENCY
10
0
20
Turf-formers
mean: 4.1 mean: 3.4 mean: 2.3
10
0
0 10 20 30 0 10 20 30 0 10 20 30 40
Diameter of habitat patches (m)

# 2. Causes
0
Urban Agricultural Natural
12
uptake of urban derived nitrogen
(b)
10
δ15N (‰  SE)
Urban
8
6
Natural Agricultural
4
-22 -21 -20 -19
δ13C (‰  SE)

# 2. Mechanisms

# 2. Mechanisms
Ambient Nutrients
100 Elevated Nutrients
Percentage cover of turf
80
60
40
20
0
Summer Winter Summer Winter
Natural catchment Urban catchment

# 3. Restoration
Non-removal control
Turf removal
100
80
Recovery (%)
60
40
20
0
1 2 3
Turf-dominated sites

#4. Contingencies
Contingencies
Production & consumption via humans & biogeography

#4. Contingencies
• Oceanography
Bigger cities = bigger impacts?
Sydney
Environmental Impact
Perth
Adelaide
Human population

• Oceanography
Western Australia
20 Southern Australia
% cover of turf
Sydney Eastern Australia
10
0
0 0.5 1.0 1.5
Chlorophyll a
20
Chlorophylla (mg l-1)
15
10
5
Sydney
0
Southern Eastern
0.3 insitu sampling at depth of subtidal habitats
NOx (Milligrams/l)
0.2
0.1
Sydney
0.0 a b a b
Southern Eastern

• Oceanography
25 Ambient
Enriched 7.25 %
20
49.64%
Turfs (% cover)
15
1000 Km
10
5
0
south east
coast coast
Cape Jervis

6000
Productivity
5000 SE Alaska
4000
Japan
3000 Norway Central California
S Chile
Southern California
2000 S Africa-South Coast
Gulf of Maine
East Australia
1000 South & West Australia
2 4 6 8 10 12 14
Integrated Monthly NO3 Flux

The poster child
easy ecology

• Consumers

Data courtesy of Nick Shears
75 % (n = 113 sites) have no barrens

70 % (n = 60 sites) have no barrens

• Consumers
100
Grazers present
80 Grazers absent
Percentage Cover
60
1000 Km
40
20
0
south east
coast coast
Cape Jervis

A continuum
Case A: consumption is much coralline
A B
KELP CONSUMPTION
higher than production, and small
variation in either has little
world
impact.
Cases B and C: when
consumption roughly equals
production, small changes in
either can shift the system to a
different state.
Case D: production is much
C D
higher than consumption, and
small variation in either has little kelp
impact.
world
KELP PRODUCTION

coralline
world
KELP CONSUMPTION
Eastern Australia
Productivity is high
and varies little, but
large variation in
consumption is driven
by patchy distributions
of urchins (in both
space and time).
kelp
world
KELP PRODUCTION

coralline
world
KELP CONSUMPTION
Western & South Australia
Variation in herbivory is
relatively low, but large
variation in productivity is
driven by land use
kelp
world
KELP PRODUCTION

Policy: long-term benefits?

Conceptual summary of experiments
Size of Effect
Global Local Global & Local
Stressors

Connell (2007) Oxford University Press

Climate Global
Flindersia
Biogeography
Gulf
Coastal morphology
Depth
Local conditions
Individuals

Percentage cover of rocky habitat

Percentage cover of rocky habitat
year 2050
(550 ppm)

Percentage cover of rocky habitat

“Political decisions are empowered by scientific
evidence in support of policy initiatives” Steve Kennelly
(Director Fisheries, NSW DPI)
....

Bring back the kelp

Policy

Environment Institute
Science Seminar Series 2009
Semester 2 Series begins Friday 31 July
Program to be released shortly
www.adelaide.edu.au/environment