Methodological considerationsfor defining historical baselines for marine ecosystem status

1. Methodological considerations
for defining historical baselines
Dr. Laura Uusitalo
Finnish Environment Institute
Marine ecosystem baselines as the basis for
reference points
ICES ASC, Wednesday 23 September 2015

2. Develop historical baselines of population and
community structure and production
to be used as the basis for population and
system level reference points
ICES Science Plan:

3. I. Defining historical baselines based on available data
II. From baselines to reference levels: Finding out the causes
for change
III. System level: Compatibility of multiple baselines /
reference levels
Methodological considerations for

4. ● Is sampling comparable?
○ Sampling sites & times (seasonal cycle!)
○ Changes in sampling equipment & methodology
● Is the sample treatment / analysis comparable?
○ Identification of species/stages
○ Ageing
○ Laboratory methods
I. Things to check when using historical
data

5. I. Example: Hällfors et al. 2013, Baltic Sea
phytoplankton comparison across 100
years
- Sampling equipment
- No information on
preservation &
analysis methods
- Nomenclature changes
- Identification issues

6. ● Choose variables with little identification / determination
issues
○ species that are easy to identify
○ variables that have been easy to measure also in the
past
● Choose parameters that are robust to changes in sampling
○ E.g. maximum size instead of mean size of size-at-age?
○ Presence-absence rather than abundance or biomass?
○ Little spatial or temporal variation
I. Recommendations for developing
historical baselines

7. ● Multiple causes of change: what are they?
○ We’re not likely to see them all!
● The causes are likely to be correlated ((multi)collinearity):
Disentangling their effects impossible or very uncertain!
● Interaction between explanatory factors may turn the initial
results upside down!
II. From baselines to reference levels:
Identifying the causes of change

8. Source: http://www.tylervigen.com/spurious-correlations

9. no yes
0.100.200.30
management
survival
Example of
correlated
causes that
may turn
the initial
results
upside
down2 3 4 5
0.100.200.30
temperature
survival

10. 2 3 4 5
0.100.150.200.250.30
Water temperature
survival
No management
Management

11. ● What are the dates of the historical baselines? Did they
actually occur at the same time in history?
● Could they have co-occurred?
○ considering energy flows, predation rates, etc?
○ Single vs multi-species MSY
● Could that ecosystem function be reached still today?
○ Cyclic climate patterns, climate change
○ Land / marine space use changes
○ Alien species
III. Ecosystem level:
Are multiple baselines mutually consistent?

12. ● A (comprehensive) list of mutually consistent reference
levels  vision of the desired ecosystem state
○ Check: Does the desired state provide us with the
ecosystem services we need?
● Can we see a path from current to desired state?
○ How long would this journey take?
 Basis for the management plan!
 Workshop for “historical IEA” to consider
mutually consistent baselines / reference
levels?
Food for thought

13. Zooplankton
sampling onboard
R/V Aranda in
2012. Photo:
Laura Uusitalo
Thank you for your attention!