This document summarizes a study on imposex in dog whelks (Nucella lapillus) in French harbors along the English Channel from 2005-2012. The study found:
1) Imposex levels were highest in Brest harbor and lowest in Boulogne harbor, indicating Brest had the most TBT contamination.
2) Imposex levels decreased over time in all three harbors from 2005-2012, consistent with reduced TBT usage after its ban.
3) However, female dog whelk populations dropped in 2012, possibly due to other environmental or climate factors interacting with TBT in non-linear ways.
4) Adherence to standardized sampling and analysis protocols is important for quality
3. French Harbours along the English Channel
Brest
Cherbourg
Boulogne
France
England 3 Locations
Annual sampling
2005
2008
2012
Parameters
Sex*
VDS
Penis length
Shell height*
4. French Harbours along the English Channel
Brest
CherbourgBoulogne
Brest
Cherbourg
Boulogne
9. QUASIMEME – What is it about?
Provide quality assurances procedures
Critically determine sex status in neogastropod molluscs
To record relevant parameters
Contribute data to the first international project on the
biological effects of TBT compounds
Conduct international laboratory performance studies
for imposex and intersex using live marine snails
standardisation of
analytical techniques
training of
scientists
inter-laboratory
studies
Quality Assurance of Information for Marine Environmental Monitoring in Europe Project
10. QUASIMEME – Protocol
Parameters
Bioindicator species
Collection method
of samples
Number of
samples collected
Number of
samples analysed
Holding time
Preservation of
samples
Examination
Type
Exclusion of individuals
affected by parasites
Shell height
Sex
determination
Vas deferens
stage (VDS)
description
Measurement of
penis length
Calculation of
summary indices
11. QUASIMEME – Protocol
Standardized processes of
sample collection, preservation,
analysis and calculations
Proper preparation of samples after
collection, during transport and
before analysis
Should be done at the same
period of the year
More difficult to determine the sex
of the sub-adults than of toothed
adults
S T A N D A R D P R O T O C O L M O N I T O R I N G P E R I O D
T Y P E O F S P E C I M E N S
(SUB-ADULT/ADULT)
H A N D L I N G O F S A M P L E S
All measurements should be
carried out according to
defined protocols
by trained staff
The quality of dataset should be
assured: consistent, complete,
and stored properly
Q U A L I T Y C O N T R O L
O F M E T H O D S F O R
M O R P H O L O G I C A L
A N A L Y S I SQ U A L I T Y C O N T R O L O F
D A T A A N D R E P O R T I N G
12. QUASIMEME – Indices
VDSI RPSI RPLI Sex Ratio
Average VDS Percentage of female
vs male penis bulk
Percentage of female
vs male penis length
Self-explanatory!
Habitat
Habitat affects food
supply and penis length
Physical
Deformations on subject
organ at high concentrations
Time-Dependence
Maturity rate
Sensitivity periods
Mortality rate
Dependent on the organ and
characteristics of species
Surely then there are limitations!
14. QUASIMEME – Results [Performance]
Some laboratories produced the following:
Miscalculations
VDSI & RPSI using the
formula in the OSPAR
Guidelines
Conversion errors from
graticule units
Measurement Errors
in the reported
shell height
Misidentification
Of imposex females
as males
Wrong VDSI!
15.
16. QUASIMEME – Results [Biological]
Homogeneity of
samples
Penis length Sex identification VDSI
QUASIMEME
Paper ✓
Lowest value: 14.74
Highest value: 59.52
Generally proportional:
(47.2%) and females (52.8%)
Overall value
3.8
English
Channel
Dataset
X
Lowest value: 0.03
Highest value: 20
Not proportional pick of
males or females
Overall values
Brest: 3.65
Cherbourg: 2.90
Boulogne: 1.55
Lack of data on
the shell height Small
Possibility of
Misidentification
Nucella
Results
17. Our Final Conclusion!
• All VDSI values seem to reduce in all three stations.
• Brest is the most polluted, then Cherbourg, and Boulogne is the least.
• Reduction in females in 2012 could be explained by a non-linear
response to climate change / other environmental disturbances
• Quality control and adherence to protocol is important!
• Imposex indices are not perfect other parameters and novel
measurments
• Despite of ban on TBT usage, some in France could still use it.
• More awareness and regulation needed!
TBT levels are known to result in imposex occurrence in indicator gastropods like Nucella lapillus
Data from each location is provided for 2005, 2008 and 2012
We have to note that the data for Brest 2005 and Brest 2008 is inconsistent with the others, Phare du Portzic was selected
Main parameters provided were:
Location coordinates
Date of collection (March, May, June)
Sex
Vas Deferens stage (VDS)
Penis length
Shell height (only for 2005 in Cherbourg and Boulogne)
Indicate dockyard, bay,
VDSI – sterility to come automatically
Brest comes first
Boulogne
Then Cherbourg and roscoff
Indicate marina
Make it automatic
Put in images of bioindicators
All VDSI values seem to reduce in all three stations.
Brest is the most polluted, then Cherbourg, and Boulogne is the least.
Reduction in females in 2012 could be explained by a non-linear response to climate change / other environmental disturbances
The quality control for the use of standard protocols on the method of analysis, data analysis and reporting must be strictly and properly applied.
Imposex indices are not perfect for all habitats and are time-dependent innovative quantification methods are needed to fill in the gaps
Despite of ban on use of TBT upon boats under 25 meters in Europe, some users in France continue to use this product. Therefore it is necessary to increase awareness of people about danger for the environment and even for their health.
