Post on 13-Jul-2018
transcript
Lake phytoplankton
Intercalibration – 40 shades of green?
Gary Free, Wayne Trodd, Deirdre Tierney, Ruth Little,
Caroline Plant, Bryan Kennedy, Caroline Wynne
Water Framework Directive Intercalibration Exercise Update, Marine Institute, Oranmore, Co. Galway, 13/10/11.
Overview of method used in IE to
assign phytoplankton status in lakes
Phytoplankton composition metric
Chlorophyll a
IE Lake Phytoplankton Index
Normalised
Normalised
Averaged
Chlorophyll a
A traditional and long established parameter used to
determine biological response to nutrient enrichment
•SAKAMOTO, M., 1966: Primary production by phytoplankton
community in some Japanese lakes and its dependence on
lake depth. Archiv fur Hydrobiologie, 62, 1-28.
•DILLON, P.J., RIGLER, F.H., 1974: The phosphorus -
chlorophyll relationship in lakes. Limnology and
Oceanography, 19, 767-773.
Plot of log mean total phosphorus concentrations against log
mean chlorophyll a concentrations found in the study lakes
between March 1996 and December 1997. Regression: log y =
0.15 + 0.62 log x; r2 = 0.58; P < 0.01.
Irvine, K., Allott, N., deEyto, E., Free, G., White, J., Caroni, R., Kennelly,
C., Keaney, J., Lennon, C., Kemp, A., Barry, E., Day, S., Mills, P., O' Riain,
G., Quirke, B., Twomey, H., Sweeney, P., 2001: Ecological assessment of
Irish lakes. Environmental Protection Agency, Wexford, 503pp
Phytoplankton composition metric
Chlorophyll a
IE Lake Phytoplankton Index
Normalised
Normalised
Averaged
Composition and abundance must
also be included in assessment of
phytoplankton
0.5 mm
Free, G., Little, R., Tierney,
D., Donnelly, K., Caroni, R.,
2006. A reference based
typology and ecological
assessment system for Irish
lakes. Preliminary
investigations. 266pp. EPA,
Wexford, Ireland. ISBN:1-
84095-215-6. www.epa.ie
Development of
composition metric for lake
phytoplankton
•The assessment system was developed for summer
phytoplankton based on quantitative samples.
•Summer was chosen as it is the period when the
excessive growth of phytoplankton most often occurs.
•Assessment is based on nine groups or genera of
indicator taxa, each of which is awarded a score
ranging from 1 to 0.1 based on abundance. Sample
chlorophyll a is also awarded a score ranging from 1 to
0.1.
Development of composition index
•Reference value for the composition metric was
taken from a set of lakes in reference status
confirmed by a palaeolimnological study of 34
candidate reference lakes.
•These lakes had similar assemblages from a
comparison of top and bottom core samples. The
average reference composition metric value for
these lakes was 0.9383.
•This was used as a denominator to generate an
EQR following guidance document 10 (Tool 3 page
53, REFCOND (2003)).
Taylor et al.,
2006
www.EPA.ie
Reference values
Scores applied to abundance:
R2 0.67
Performance of composition metric
Phytoplankton composition metric
Chlorophyll a
IE Lake Phytoplankton Index
Normalised
Normalised
Averaged
x3 years
mean and
confidence
Normalising EQR
Metric
value
20
0
G/M 11
SG/G 17
7
4
national EQR for the metric
1
0
0,8517/20
11/200,55
7/200,35
4/200,20
Normalised EQR for the metric
1
0
0,80
0,60
0,40
0,20
15 0,75(0,75-0,55)*(0,80-0,60)
(0,85-0,55)+0,60
0,73
M/D
SD/D
REF
Metric
value
20
0
G/M 11
SG/G 17
7
4
national EQR for the metric
1
0
0,8517/20
11/200,55
7/200,35
4/200,20
Normalised EQR for the metric
1
0
0,80
0,60
0,40
0,20
15 0,75(0,75-0,55)*(0,80-0,60)
(0,85-0,55)+0,60(0,75-0,55)*(0,80-0,60)
(0,85-0,55)+0,60
0,73
M/D
SD/D
REF
PreparedPrepared byby: : AAnnenne LycheLyche SolheimSolheim & JRC& JRC
Type Lake Characterisation
Altitude
m
Mean depth
m
Alkalinity
meq l-1
Colour mg l-1
PtCo
Residence
time
L-N1
Lowland, shallow, moderate
alkalinity, clear <200 3 - 15 0.2 - 1 < 30
L-N2a
Lowland, shallow, low
alkalinity, clear <200 3 - 15 < 0.2 < 30
L-N3a
Lowland, shallow, low
alkalinity, meso-humic <200 3 - 15 < 0.2 30 - 90
L-N8a
Lowland, shallow, moderate
alkalinity, meso-humic <200 3 - 15 0.2 - 1 30 - 90
L-CB1
Lowland, shallow calcareous
lakes < 200 3 - 15 > 1
1-10
L-CB2
Lowland, very shallow
calcareous lakes < 200 < 3 > 1
0.1-1
NGIG and CBGIG lake types
intercalibrated for eutrophication pressure
by Ireland.
Relationship between national final EQRs
(standardised to remove country effects) and total P.
a)SE, b)FI, c)NO, d)UK, e)IE for LN8A lake type
Results from
Geoff Phillips
19/9/2011
Annex2 Milestone 6 Relationship between phytoplankton EQR and mean growing
season total phosphorus (µg/l), regression relationship fitted to data where total
phosphorus <200µg/l, results from Geoff Phillips.
Common metric ‘translates’ a country’s
boundaries into units comparable with other
Member states
H/G Bias as Class Width
-0.14
0.17
0.02
0.21
-0.23
0.43
-0.23 -0.24
0.17
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
UK
DE
EE
(ind
ex)
LV BE
NL
DK PL IR
Countries’ H/G and G/M boundaries
should be within 0.25 of a class width
Harmonised
boundaries
for LCB1
lakes
For most types IE was within the
band
Lake type HG Bias GM bias
L-N1 0.10 -0.08
L-N2a 0.33 0.19
L-N3a 0.21 -0.02
L-N8a 0.25 0.14
L-CB1 0.17 0.21
L-CB2 0.54 0.69
LCB2 - One of these lake
types is doing its own thing
2 v 21 µg l-1
chlorophyll a
Still looking good??
IE reference and boundary values for
chlorophyll a for intercalibrated types
0
3
6
9
12
Ch
loro
ph
yll a
µg
l-1
Lake Type
Good/Moderate
High/Good
Reference
How did IE set boundaries?
Selection of TP bands (- - -) based on the lowess smoothed relationship (──) between
Simpson’s diversity index and transformed (Log x+1) TP. Smoothed relationship of
chlorophyll a with transformed (Log x+1) TP is overlain (green line). Graph refers to lakes >
20 mg l-1 CaCO3 only, TP values were mostly measured in Spring.
Diversity starts to decrease,
therefore resulting in an
‘undesirable disturbance to the
balance of organisms’ which
corresponded to a TP
concentration of 25 mg l-1.
The increase in diversity between
10 and 25 mg l-1 TP may
correspond to normative
definitions of good status in that
the change in not an ‘undesirable’
one.
For marl lakes (part of the LCB types)
stricter standards may need to adopted
nationally
From page 221 of Free, G., Little, R., Tierney, D., Donnelly, K., Caroni, R., 2006. A
reference based typology and ecological assessment system for Irish lakes. Preliminary
investigations. 266pp. EPA, Wexford, Ireland. ISBN:1-84095-215-6. www.epa.ie
OTSUKI, A., WETZEL, R.G., 1972: Coprecipitation of
phosphate with carbonates in a marl lake. Limnology and
Oceanography, 17, 763-767.
Joint Nature Conservation Committee (2007) Second
Report by the UK under Article 17 on the implementation
of the Habitats Directive from January 2001 to December
2006. JNCC, Peterborough.
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0 50 100 150 200
Median MRP mg l-1
Q v
alue
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 10 20 30 40 50 60
Median TP mg l-1
Mac
roph
yte
mult
imet
ric
.
Fig 1 and 2 Comparison of metric response to pressure (Molybdate Reactive
Phosphorus and TP) for the Irish EPA macroinvertebrate Q-Value system for rivers
(McGarrigle, 1998) and the macrophyte multimetric (> 20 mg l-1 CaCO3 alkalinity)
(Free et al., 2006). Logarithmic trend-lines fitted. Fig 3 ILPI and TP with smoothed
line fitted CBGIG dataset.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 20 40 60 80 100
IE L
ake
Ph
yto
pla
nkt
on
In
de
x
TP mg l-1
Most biological change takes place at
initial stage of eutrophication
Implications for IE and future role in
WFD
•Some additional work on boundaries in marl lakes
•Need to translate boundaries from IC types into
national types.
•Classification for phytoplankton in lakes should now
use both chlorophyll a and composition to classify the
BQE and not just one parameter.
•Phytoplankton will be used as part of a OOAO
assessment in assigning status.
•Confidence of assessment critical for status
assignment.
•TP standards
•Zebra mussels