Physico-chemical supporting elements in coastal waters, WFD-MSFD-RSC Links : a review of standards to support good ecological status under the Water Framework Directive, Marine Strategy Framework Directive and Regional Sea Conventions.
Date: 2022-04-19
Institutions: Joint Research Centre
Subjects: EU Member State, chemical element, coastal region, directive (EU), environmental monitoring, environmental standard, eutrophication, exchange of information, research report, territorial waters

Physico-chemical supporting elements in 
coastal waters: WFD-MSFD-RSC Links  

A review of standards to support good ecological status under the Water 
Framework Directive, Marine Strategy Framework Directive and Regional Sea 
Conventions 

Salas Herrero, F., Araujo R., Leujak.,W., Poikane, S 

2022 

EUR 31049 EN 

 
 
 
This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It 
aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a 
policy position of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is 
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of its frontiers or boundaries. 

Contact information  
Name: Fuensanta Salas Herrero 
Address: Via Enrico Fermi 2749, 21027 Ispra (VA), Italy 
Email: Fuensanta.Salas-Herrero@ec.europa.eu 
Tel.: +39 0332 78 5701 

EU Science Hub 
https://ec.europa.eu/jrc 

JRC128107 

EUR 31049 EN 

ISBN 978-92-76-51966-9  

ISSN 1831-9424 

doi:10.2760/58715 

Luxembourg: Publications Office of the European Union, 2022 

© European Union, 2022 

The reuse policy of the European Commission is implemented by the Commission Decision 2011/833/EU of 12 December 2011 on the 
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All content © European Union, 2022 

How to cite this report: Salas Herrero, M.F., Dos Santos Fernandes De Araujo, R., Leujak, W. and Poikane, S., Physico-chemical supporting 
elements in coastal waters: WFD-MSFD-RSC Links, EUR 31049 EN, Publications Office of the European Union, Luxembourg, 2022, ISBN 
978-92-76-51966-9, doi:10.2760/58715, JRC128107.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Contents 

Acknowledgements .........................................................................................................................................................................1 

Executive Summary ........................................................................................................................................................................2 

1 

Introduction ................................................................................................................................................................................3 

1.1 Approach ..............................................................................................................................................................................4 

2. Overview of reported threshold values of physico-chemical quality elements and metrics .................................6 

2.1 Physico-chemical quality elements monitored vs used for assessment ...........................................................6 

2.1.1 Oxygen ................................................................................................................................ 6 

2.1.2 Transparency (Secchi Depth) ............................................................................................. 7 

2.1.3 DIN ...................................................................................................................................... 8 

2.1.4 Total Nitrogen .................................................................................................................... 9 

2.1.5 DIP ..................................................................................................................................... 10 

2.1.6 Total Phosphorus .............................................................................................................. 11 

2.2 Metrics for quality elements ........................................................................................................................................ 16 

1.1.1  2.3 Challenges encountered whilst comparing data................................................... 18 

3  Results ...................................................................................................................................................................................... 19 

3. 1 Comparison of threshold values for supporting elements................................................................................. 19 

3.1.1 Oxygen .............................................................................................................................. 19 

3.1.2 Transparency .................................................................................................................... 22 

3.1.3 Dissolved Inorganic Nitrogen ........................................................................................... 24 

3.1.4 

Total Nitrogen ............................................................................................................... 26 

2.1.5 Dissolved Inorganic Phosphorus (DIP) ............................................................................. 28 

3.6 Total Phosphorus ................................................................................................................. 30 

4  Discussion ................................................................................................................................................................................ 33 

4.1 General comments ......................................................................................................................................................... 33 

4.2 Overview of comparison of GES boundaries and links with RSC....................................................................... 33 

5 Conclusions .............................................................................................................................................................................. 35 

References ...................................................................................................................................................................................... 36 

List of abbreviations and definitions ...................................................................................................................................... 38 

List of Figures ............................................................................................................................................................................... 39 

List of Tables ................................................................................................................................................................................ 41 

i 

 
 
Acknowledgements 

We wish to thank all national experts who reviewed this report 

Authors 

Salas Herrero, F., Araujo R., Leujak., W., Poikane, S 

1 

 
 
 
 
Executive Summary 

This  report  highlights  the  common  trends  and  disagreements  identified  between  the  information  reported  by 
Member  States  (MSs)  to  Water  Framework  Directive  (WFD)  and  Marine  Strategy  Framework  Directive  (MSFD) 
reportings  on  the  standards  for  general  physico-chemical  elements,  including  nutrients,  and  the  methodological 
standards  agreed  and  used  for  the  assessment  of  Eutrophication  criteria  elements  at  regional  sea  level  by  the 
Regional Sea Conventions (RSC). 

For  the  criteria  under  Descriptor  5,  “Eutrophication”,  and  the  physico-chemical  indicators  of  eutrophication,  the 
MSFD Decision ((EU) 2017/848) established that criteria elements, threshold values and methodological standards, 
within coastal waters, should be used, as under the Water Framework Directive 2000/60/EC. On the other hand, 
Coperation between the Member States of one  marine region and with neighbouring countries which share the 
same marine waters, should take place through these Regional Sea Conventions (Article 6 of the MSFD). 

However, a firts outcome (Salas Herrero et al., 2020), showed some gaps in the harmonization of the criteria and 
parameters used by MSs. 

The main aim of the current report is to continue with this comparison and analyse and compare the boundaries 
values of the physico- chemical parameters, for the assessment of Good Status in coastal waters under the WFD, 
MSFD and those included in Regional Sea Conventions (RSC) reports, f highlighting the reasons (i.e local-specific, 
technical) for the lack of harmonization, and to provide recommendations for further work. 

The  first  results  is  that  the  discrepancy  between  the  monitoring  plans  provided  by  MSs  and  the  reporting  of 
threshold values does not allow a comprehensive comparison between WFD and MSFD threshold values.  

Many countries have reported different parameters for both Directives, not being possible the comparison. Dissoved 
Inorganic Nitrogen (DIN) and Total Phosphorus (TP) are the parameters with higher number countries (10) reporting 
threshold values for both Directives.  

In general, when the comparison has been possible between WFD and MSFD reporting, the same threshold values 
have been observed in both  reporting. Some exceptions could be  related to  different  metrics used, or different 
areas  considered,  and  this  should  be  explained  by  the  experts.  Our  recommendation  is  to  consider  the  same 
assessment season, the same metric and the same areas (or national types) to be reported. 

Countries  like  Poland  and  Sweden  are  good  examples  of  harmonization  in  the  monitoring  plans,  criteria  and 
reporting  of  threshold  values  in  the  implementation  of  both  Directives.  These  countries  are  in  line  with  the 
requirements of both Directives and requirements of HELCOM and OSPAR.  

A major exchange of information between the experts participating in the RSC discussions and managers responsible 
of both Directives is recommended to establish common  monitoring programmes, methodologies and threshold 
values to achieve in the same way the good status of coastal waters. 

2 

 
 
 
 
1 

Introduction 

The Water Framework Directive (WFD, Directive 2000/60/EC) and the Marine Strategy Framework Directive (MSFD, 
Directive 2008/56/EC) both aim to establish a framework for community action in the field of freshwater (rivers, 
lakes, coastal, and transitional bodies of water) and marine waters, respectively, in the European Union. 

The WFD relates to improving and protecting the chemical and biological status of surface waters river  catchment, 
lakes, and groundwater, through to estuaries (transitional) and coastal waters up to 1 nautical mile out to sea and 
overlaps with the MSFD in coastal waters (for chemical status, the overlap between WFD and MSFD extends to 12 
nautical miles). 

The WFD stipulates that, at good ecological status, physicochemical elements must not “exceed the ranges or levels 
established, so as to ensure the functioning of the ecosystem and the achievement of values specified (for good 
status) for the biological quality elements” (Annex V, 1.2).  The WFD does not provide specific ranges or levels, but  
requires  Member  States  (MS)  to  determine  type-specific  physicochemical  criteria  ensuring/supporting  good 
ecological status. 

For  the  criteria  under  Descriptor  5,  “Eutrophication”,  and  the  physico-chemical  indicators  of  eutrophication, 
(nutrients in the water column, dissolved oxygen, and photic limit), the MSFD Decision ((EU) 2017/848) establishes 
that criteria elements, threshold values and methodological standards, within coastal waters, should be used, as 
under Directive 2000/60/EC. 

The MSFD lists four European marine regions – the Baltic Sea, the North-east Atlantic Ocean, the Mediterranean 
Sea and the Black Sea – located within the geographical boundaries of the existing Regional Sea Conventions (RSC). 
Cooperation between the Member States of one marine region and with neighbouring countries which share the 
same marine waters, should take place through these Regional Sea Conventions (Article 6 of the MSFD). 

The four European Regional Sea Conventions are: 

The Convention for the Protection of the Marine Environment in the North-East Atlantic of 1992 (further to earlier 
versions of 1972 and 1974) – the OSPAR Convention (OSPAR)  

The Convention on the Protection of the Marine Environment in the Baltic Sea Area of 1992 (further to the earlier 
version of 1974) – the Helsinki Convention (HELCOM)  

The Convention for the Protection of Marine Environment and the Coastal Region of the Mediterranean of 1995 
(further to the earlier version of 1976) – the Barcelona Convention (UNEP-MAP)  

Convention on the Protection of the Black Sea against Pollution (Bucharest Convention) signed in 1992 at Bucharest.  

The Working Group on Ecological Status (ECOSTAT), as part of the Common Implementation Strategy for the WFD, 
agreed to address the topic of comparison of nutrient criteria and thershold values set by the Member States and 
the need of establishing appropriate nutrient boundaries to achieve good ecological status. A Best Practice Guide 
(BPG) was elaborated in this context. Its purpose is to help Member States to achieve Good Ecological Status (GES) 
in  surface  waters.  It  complements  the  CIS  Guidance  Document  on  Eutrophication  Assessment  (European 
Commission, 2009) by providing more targeted advice on how to link nutrient concentrations in surface waters to 
specific policy objectives. 

For the continuation of this work, the WFD CIS Work Programme 2019-2021 (approved by Water Directors meeting 
29 November 2018, Vienna) includes the general task “Continuing the exchanges of information on nutrients and 
other physico-chemical elements: nutrient boundaries, links with the Marine Strategy Framework Directive (MSFD) 
and Regional Sea Conventions (RSC), nutrient reduction targets.” 

The objective of the specific task “links with the MSFD and Regional Sea Conventions” is to check and analyse the 
links (correspondence)  between  the eutrophication descriptor  boundaries established by MS  for the WFD, MSFD 
under Descriptor 5 (Eutrophication) and the Regional Seas Conventions. Therefore, the parameters considered for 
the comparison are Nutrient concentration in the water column (Dissolved Inorganic Nitrogen -DIN, Total Nitrogen 

3 

 
 
 
 
(TN), Dissolved Inorganic Phosphorus (DIP), Total Phosphorus (TP), Photic limit (Transparency) of the water column, 
and Dissolved oxygen in the bottom of the water column.  

A first outcome of this work has been the JRC Technical Report “Physico-chemical supporting elements in coastal 
waters: Links between Water and Marine Framework Directives and Regional Sea Conventions “(Salas-Herrero et 
al., 2020) which focused on the comparison of the parameters and criteria adopted by Member States (MS) as 
indicators of eutrophication. 

Objectives 

The aim of the current report is to analyse and compare the boundaries values of the physico- chemical parameters, 
for the assessment of Good status in coastal waters under the WFD, the MSFD and Regional Sea Conventions (RSC), 
with  the  purpose  of  highlighting  the  reasons  (i.e  local-specific, technical)  for  the  lack  of  harmonization,  and  to 
provide recommendations for further work. 

The information has been analysed addressing the following questions: 

Q1. Are the  Member States  using the same threshold  values for assessing the eutrophication status in  coastal 
waters under WFD and MSFD? 

Q2. Are the recommendations on parameters, criteria and threshold values included in the RSC reports in line with 
MSFD and WFD requirements? 

Q3. What is the implication of a lack of harmonization on the assessment of coastal and marine waters in Europe? 

1.1 Approach 

To anwer the question Q1 Are the Member States using the same threshold values for assessing the eutrophication 
status in coastal waters under WFD and MSFD? we have used the answers provided by MSs to a questionnarie sent 
out on the monitoring parameters in coastal waters and the WFD threshold values provided by Peter Kristensen 
(EEA) in the context of the second cycle of the River Basin Plan managements reporting. Following this, ECOSTAT 
representatives were invited to check the entries for their country and the revised database, incorporating these 
revisions. In countries where national type specific boundary values existed, the same type specific boundary was 
replicated several times for each RBD. To avoid giving additional weight to these values only a single national type 
specific boundary value was used. 

The  data  consisted  of  lists  of  physico-chemical  quality  element  (PCQE)  determinants  with  the  values  used  for 
different national types for each water category, together with information on the units and summary metrics used. 
The data provided has been edited to harmonise the different formats used during reporting.  

The MSFD threshod values were provided  by EEA in the  context of the  MSFD 2018 reporting (Article 8,9 &10), 
although values were reported until 2020. The data consisted on reported threshold values for the physico-chemical 
elements used for different Marine Regional Units including coastal and marine waters, together with information 
on the units and summary metrics. Only in the case of few countries (e.g.  Sweden) similar reporting types or areas 
were  specified  and  were  used  for  WFD  and  MSFD  facilitating  the  assessment  of  harmonization  between  both 
Directives.  

To anwer the question Q2 Are the recommendations on parameters, criteria and threshold values included in the 
RSC reports in line with MSFD and WFD requirements? we have used the information included in the following RSC 
reports : 

4 

 
 
 
 
 
 
 
 
The information sources about the parameters and threshold values used by the RSC are: 

OSPAR: Common procedure for the Identification of the Eutrophication Status of the OSPAR Maritime Area (2013); 
OSPAR: third integrated report on the eutrophication status of the OSPAR maritime area (2017)1; 

HELCOM: State of the Baltic Sea report: the integrated assessment of eutrophication (2018); 

HELCOM,  2013.  Approaches  and  methods  for  eutrophication  target  setting  in  the  BalticSea  region.  Baltic  Sea 
Environment Proceedings No. 133 (138 pp). 

HELCOM, 2015. HELCOM Eutrophication Assessment. Http://helcom.fi/helcom-at-work/projects/eutro-oper/. 

UNEP-MAP: United Nations Environmental Programme Mediterranean Action Plan (2018); 

Environmental monitoring of the Black Sea with focus on nutrient pollution” (Acronym: Baltic2Black). Final Report 
for the Grant Agreement No 07.0204/2010/580913/SUB/D2. 2014 

Black Sea Commission (BSC): Black Sea integrated monitoring and assessment programme (2017-2022). 

RSC “threshold values” considered in this work are those included in Table 4 and Annex 6b of the report “Common 
Procedure for the Identification of the Eutrophication Status of the OSPAR Maritime Area”(2013, 2017, and in tables 
5 and 6 of the “Environmental monitoring of the Black Sea with focus on nutrient pollution” (Acronym: Baltic2Black) 
(2014). In the first case, for each parameter agreed by OSPAR, an assessment level was developed by each country, 
based on levels of increased concentrations and trends as well as on shifts, changes, or occurrence. In the second 
case, the threshold values are those provided as “target values “by the Black Sea countries.  

The HELCOM Eutrophication assessment level (HELCOM, 2015) specifies that for all coastal indicators, the indicator 
level  as  well  as  the  GES  boundary  has  been  assigned  nationally  for  each  assessment  unit,  based  on  the 
methodology  agreed  during  the  WFD  work  (for  intercalibrated  indicators)  or  nationally  (for  indicators  not 
intercalibrated). Therefore, theoretically, the HELCOM threshold values in coastal waters, are the same as those 
provided by Baltic countries for the WFD implementation.  

UNEP MAP does not include any threshold value in its reports, and even for nutrients, there is no agreement on 
assessment criteria agreed parameters 

1 OSPAR is currently working on developing a regions wide harmonised assessment of eutrophication. The final outcomes are expected next 
year and will be used for the next OSPAR QSR2023 report. By now, for the purpose of this work, we can only use the outcomes included 
in previous reports (i.e OSPAR 2013, 2017). 

5 

 
 
 
 
 
2. Overview of reported threshold values of physico-chemical quality elements 
and metrics 

2.1 Physico-chemical quality elements monitored vs used for assessment  

This  section  compares  the  information  provided  by  MSs  to  a  questionnarie  on  the  monitoring  of  the  physico- 
chemical elements and the real existence (and therefore actual use of the quality element-QE for eutrophication 
assessment) of threshold values reported to WFS and MSFD reporting.  

In general, while many countries indicated that they monitor the respective physico-chemical quality elements for 
the WFD and MSFD fewer countries indicated that they had set threshold values.  Very few cases occur where a 
country reporting threshold values of a given QE has not given monitoring information for that QE previously. In 
WFD reporting it was the case of RO for TP; BE for Secchi depth. In MSFD, it was the case of EE for DIN; ES and PT 
for dissolved oxygen. 

Below we present detailed comparisons for each QE. 

2.1.1 Oxygen 

Figure 2.1 compares the countries informing on monitoring plans for oxygen conditions and the countries reporting 
threshold values to WFD reporting. There are 16 countries informing on monitoring plans, but 5 of them (EE, IT, LV, 
LT, NL) are not reporting values for this QE. Germany has not nationally agreed threshold values, but the experts 
have established threshold values bases on expert judgment and we have considered them for the comparison.  

Figure 2.1 Oxygen  conditions monitoring plans for WFD implementation (left) and countries reporting threshold 
values to WFD reporting (right). 

Figure 2.2 compares the countries informing on monitoring plans for oxygen conditions and the countries 
reporting threshold values to MSFD reporting. There are 18 countries informing on monitoring plans, but 5 of 
them (BG, GR, LT, MT, SI) are not reporting threshold values for this QE. There are 2 countries (ES, PT) reporting 
threshold values but no monitoring plans 

6 

 
 
 
 
 
Figure 2.2 Oxygen conditions monitoring plans for MSFD implementation (left) and countries reporting threshold 
values to MSFD reporting (right). 

2.1.2 Transparency (Secchi Depth) 

Figure 2.3 compares the countries informing on monitoring plans for Secchi depth and the countries reporting 
threshold values to WFD reporting. There are 14 countries informing on monitoring plans, but 5 of them (CY, ES, 
IT, MT, SI) are not reporting threshold values for this QE. There is 1 country (BE) reporting threshold values. 
Germany (DE-Baltic) has not nationally agreed standards but the experts have established target values bases on 
expert judgment and we have considered them for the comparison. For the North Sea, Germany does not consider 
secchi depth to be a suitable assessment parameter (due to naturally high turbidity in coastal waters) and 
therefore has not established any threshold values. 

Figure 2.3 Secchi Depth monitoring plans for WFD implementation (left) and countries reporting threshold values 
to WFD reporting (right). 

Figure 2.4 compares the countries informing on monitoring plans for secchi depth and the countries reporting 
threshold values to MSFD reporting. There are 16 countries informing on monitoring plans, but 4 of them (CY, ES, 
GR, IT) are not reporting threshold values for this QE.  

7 

 
 
 
 
 
 
Figure 2.4 Secchi Depth monitoring plans for MSFD implementation (left) and countries reporting threshold values 
to MSFD reporting (right). 

2.1.3 DIN 

Figure 2.5 compares the countries informing on monitoring plans for DIN and the countries reporting threshold 
values to WFD reporting. There are 16 countries informing on monitoring plans, but 5 of them (BG, CY, FR-MED, 
GR, LV) are not reporting threshold values for this QE.  

Figure 2.5 DIN monitoring plans for WFD implementation (left) and countries reporting threshold values to WFD 
reporting(right). 

Figure 2.6 compares the countries informing on monitoring plans for DIN and the countries reporting threshold 
values to MSFD reporting. There are 17 countries informing on monitoring plans, but 7 of them (BG, CY, ES, GR, IT, 
LT, MT) are not reporting threshold values for this QE. 

8 

 
 
 
 
 
 
 
Figure 2.6 DIN monitoring plans for MSFD implementation (left) and countries reporting threshold values to MSFD 
reporting (right). 

2.1.4 Total Nitrogen 

Figure 2.7 compares the countries informing on monitoring plans for TN and the countries reporting threshold 
values to WFD reporting. There are 12 countries informing on monitoring plans, but 4 of them (FR, IT, LV, MT) are 
not reporting threshold values for this QE.  

Figure 2.7 TN monitoring  plans for WFD implementation (left) and countries reporting  threshold values to WFD 
reporting (right). 

Figure 2.8 compares the countries informing on monitoring plans for TN and the countries reporting threshold 
values to MSFD reporting. There are 15 countries informing on monitoring plans, but 5 of them (BG, FR-NEA, GR, 
IT, RO) are not reporting threshold values for this QE.  

9 

 
 
 
 
 
 
 
Figure 2.8 TN monitoring plans for MSFD implementation (left) and countries reporting threshold values to MSFD 
reporting (right). 

2.1.5 DIP 

Figure 2.9 compares the  countries informing on  monitoring plans for  DIP and the countries reporting threshold 
values to WFD reporting. There are 18 countries informing on monitoring plans, but 6 of them (EE, DE-NEA, FR, IT, 
LV, MT) are not reporting threshold values for this QE.  

Figure 2.9 DIP monitoring plans for WFD implementation (left) and  countries reporting threshold values to WFD 
reporting (right). 

Figure 2.10 compares the countries informing on monitoring plans for DIP and the countries reporting threshold 
values to MSFD reporting. There are 17 countries informing on monitoring plans, but 7 of them (BG, CY, ES, GR, IT, 
LT, RO,) are not reporting threshold values for this QE. There is one country (PT) reporting threshold values for 
this QE. 

10 

 
 
 
 
 
 
Figure 2.10 DIP monitoring plans for MSFD implementation (left) and countries reporting threshold values to MSFD 
reporting (right). 

2.1.6 Total Phosphorus 

Figure 2.11 compares the countries informing on monitoring plans for TP and the countries reporting threshold 
values to WFD reporting. There are 14 countries informing on monitoring plans, but 4 of them (HR, IT, LV, MT) are 
not reporting values for this QE. There is a one country (RO) reporting threshold values for this QE but not 
monitoring plans. 

Figure 2.11 TP monitoring plans for WFD implementation (left) and countries reporting threshold values to WFD 
reporting (right). 

Figure 2.12 compares the countries informing on monitoring plans for TP and the countries reporting threshold 
values to MSFD reporting. There are 15 countries informing on monitoring plans, but 4 of them (BG, DE-NEA, ES-
NEA GR) are not reporting threshold values for this QE.  

11 

 
 
 
 
 
 
 
Figure 2.12 TP monitoring plans for MSFD implementation (left) and countries reporting threshold values to MSFD 
reporting (right). 

Summarizing, the number of countries providing threshold values of the supporting elements is given in Table 2.1 
and Table 2.2, based on revised data reported by countries to WISE for the 2nd RBMPs and for the MSFD 
reporting 2018.  

Table 2.1 General physico-chemical quality elements reported to WFD and MSFD reporting, summarised by number 
of countries. 

QE name 

Parameter specifications 

WFD reporting 

MSFD reporting 

Secchi disk depth 

Secchi disk depth 

Other determinant for transparency 

Turbidity 

Oxygen saturation % 

Oxygen saturation % 

Dissolved oxygen (mg/l) 

Dissolved oxygen (mg/l) 

Total Nitrogen 

Total Phosphorus 

TN 

TP 

Dissolved Inorganic Nitrogen 

TIN, DIN 

Orthophosphate 

Orthophosphate, DIP 

12 

1 

7 

7 

8 

12 

11 

12 

11 

1 

2 

11 

9 

14 

14 

10 

12 

 
 
 
 
 
 
 
 
 
 
 
Table 2.2 Threshold values (in grey) reported to WFD and MSFD reporting by different countries for coastal waters. 

TN 

TP 

DIN 

DIP 

D.0 

 O2 %satur 

Photic 

WFD  MSFD  WFD  MSFD  WFD  MSFD  WFD  MSFD  WFD  MSFD  WFD  MSFD  WFD 

MSFD 

BE 

BG 

CY 

DE 
(Baltic)1 

DE (NEA) 

DK 
(Baltic) 

DK (NEA) 

EE 

ES (NEA) 

ES (MED) 

FI2 

FR (NEA)3 

FR 
(MED)3 

GR 

HR 

IE 

IT 

LT 

LV 

MT 

NL 

NO4 

13 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TN 

TP 

DIN 

DIP 

D.0 

 O2 %satur 

Photic 

PL 

PT 

RO 

SE 
(Baltic)5 

SE (NEA)5 

SI 

1 DE has not reported some threshold values for nutrients and oxygen concentrations, and secchi depth but experts 
have agreed standards based on expert judgement and we have considered those values for comparison. 

2 FI has reported threshold values as Eutrophication Integration values to the MSFD reporting, but experts have 
informed that the absolute values are the same than those reported to WFD reporting. 

3FR France has reported transparency (turbidity) threshold values and not photic limit. 

4 NO has reported threshold values to WFD reporting, but for this country is not mandatory the MSFD reporting 

5  SE  has  provided  threshold  values  as  EQRs  to  WFD  reporting.  Posteriorly,  experts  sent  us  the  nutrients  G/M 
boundaries as absolute values, but not for Secchi depth and dissolved oxygen, not being possible the comparison 
of both elements with those values reported to MSFD reporting.  

14 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 2.3 Threshold values reported by each country and included in the RSC reports. 

HELCOM 

OSPAR 

UNEP 

BESP 

Dissolved Oxygen 

%Oxygen saturation 

Photic limit 

TN 

TP 

DIN 

DIP 

 OSPAR 2013: Annex 6b. Background concentrations and assessment levels of nutrients (winter) and oxygen, OSPAR 
2017: Table 4. Assessment levels of nutrients (winter) and oxygen. 

HELCOM 2013. Target values. Nutrients (winter and annual concentrations). Secchi depth (summer values). 

Baltick2Black Report. Target values in transitional, coastal and marine waters for the different countries sharing 
the Black Sea. 

15 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2.2 Metrics for quality elements  

The most commonly used means of aggregating data are annual averages (AA) and seasonal averages (A) (Table 
2.4 and 2.5). 

Table 2.4 Overview of parameters and metrics included in the RSC reports. 

HELCOM 

OSPAR 

UNEP 

BESP 

Dissolved Oxygen 

AA 

25th 
Summer A 

percentile 

%Oxygen 

Summer A 

Photic limit 

Summer A 

10th  percentile  warm 
season 

Summer A 

TN 

TP 

DIN 

DIP 

AA 

AA 

Winter A 

Winter A 

Winter A 

Winter A 

AA 

AA 

16 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
17 

Table 2.5 Overview of metrics used by the countries for the parameters with threshold values in WFD and MSFD reporting in coastal waters. AA (annual average); A(average); 
AGM (annual geometric median); MAC (Maximum Allowable Concentration).  

TN 

TP 

DIN 

WFD 

MSFD 

WFD 

MSFD 

WFD 

MAC 

MSFD 

MAC 

WFD 

MAC 

BE 

DIP 

MSFD 

MAC 

Oxygen conditions 

Transparency/Photic limit 

WFD 

MSFD 

WFD 

MSFD 

DE (Baltic) 

Median 

Median 

Median 

Median 

Min 
summer 

value 

Min value summer 

Summer A 

Summer A 

AA 

AA 

DE (NEA) 

EE 

ES (NEA) 

AA 

Summer A 

AA 

AA 

AA 

Winter A 

Winter A  

Winter A 

Winter A  

Min value summer 

Summer A 

AA 

Summer A 

FI 

Summer A 

Summer A 

Summer A 

Summer A 

Conc.normailse
d at 33 salinity 

Conc.normailsed 
at 33 salinity 

P10 

P10 

P10 

P10 

Summer A 

Summer A 

P90 

P90 

P90 

P90 

Median 

Median 

Median 

Median 

Median 

Median 

Seasonal M 

Seasonal M 

Median 

Median 

Median 

P95 

P95 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Summer A 

Winter A 

Winter A 

Winter A 

Winter A 

AA 

AA 

AA 

AA 

AA 

AA 

AA 

Summer A 

Summer A 

P10 warm season 

AA 

Summer A 

FR (MED) 

FR (NEA) 

HR 

IE 

LT 

LV 

NL 

PL 

RO 

SE(Baltic) 

Seasonal A  

Seasonal A 

Seasonal A  

Seasonal A 

Seasonal A  

Seasonal A  

Seasonal A  

Seasonal A  

SE (NEA) 

Seasonal A  

Seasonal A  

Seasonal A  

Seasonal A  

Seasonal A 

Seasonal A 

Seasonal A 

Seasonal A 

SI 

AGM 

AGM 

17 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
18 

1.1.1  2.3 Challenges encountered whilst comparing data 

The main challenge encountered is the ambiguity in data reporting. Some countries report different threshold 
values and /or ranges, which could be interpreted as follows: 

• 

• 

In WFD reporting, if ranges are reported for “All” types, the range can be for many national types 2. 
There may, indeed, be no reason to expect variation between types for some supporting elements; 
In WFD Reporting some countries (i.e Germany) monitor physico-chemical quality elements and have 
sent threshold values for these, but do not report them since the biological quality elements failed to 
reach good status and, in this case, the supporting physico-chemical elements are not relevant for the 
final assessment outcome. 
In MSFD reporting, most of the countries do not specify if the different values provided correspond to 
the WFD national types or not. We are assuming that they correspond to the same national types; 
•  A  range  of  statistical  summary  metrics  are  used,  including  annual  averages,  seasonal  averages, 
percentiles  (Table  2.5).    Most  of  the  countries  have  reported  the  same  metrics  to  WFD  and  MSFD 
reporting, but in some cases (i.e Belgium for DIP), they have reported the same threshold values but 
different  metrics.  In  those  cases,  we  have  assumed  that  they  are  using  the  same  metric  for  both 
purposes and it has been a mistake in the reporting process. 

• 

2  

The Water Framework Directive (WFD) (European Commission, 2000), requires EU Member States to develop typologies for all water 
categories based on a set of environmental variables or type descriptors with either predefined or more freely defined ranges for 
each descriptor (WFD Annex II, System A or B respectively). 

18 

 
 
 
 
 
 
3  Results  

3. 1 Comparison of threshold values for supporting elements 

This chapter presents a comparison of results for those physico-chemical quality supporting elements included 
in  the  Annex  of  the  Commission  Decision  (EU)  2017/848  of  17  May.  We  summarise  the  results  for  each, 
focusing on the comparison of the threshold values provided for WFD and MSFD purposes, and those values 
recommend by the RSC. 

3.1.1 Oxygen 

Dissolved oxygen (DO) in waters is reported as percentage saturation or as a concentration, which complicates 
the comparison of threshold values as it is not possible to convert between the two parameters without also 
having  the  temperature  at  the  time  of  measurement.    We  thus  compare  standards  for  each  parameter 
separately. Dissolved oxygen has “two tailed” effects, with low values indicating potential threats to fish and 
invertebrates,  while  high  values  indicate  excess  oxygen  production  from  plant  or  algal  growth.  For  this 
supporting element, where possible, we therefore compare upper and lower standards separately, and interpret 
good status to be at risk for values below the lower value and above the upper value, e.g. 80-120% oxygen 
saturation.  

This parameter is included in the OSPAR’s Common Procedure (COMP) for the assessment of the eutrophication 
status, and its monitoring is mandatory for Black Sea Commission. In HELCOM, an indicator for shallow water 
oxygen concentrations is under development. UNEP-MAP recommends the Oxygen monitoring for a complete 
assessment of eutrophication and GES achievement. 

In the WFD reporting, for coastal waters, similar numbers of countries report DO using concentration (7) and 
percentage (5). In the MSFD reporting, 12 countries use DO using concentration, and 2 percentage. There is a 
lack of harmonization in the case of Spain, Croatia and Netherlands. These countries have reported oxygen 
saturation for WFD and dissolved oxygen for MSFD.  

Dissolved oxygen concentration   

WFD reporting data for Dissolved oxygen provided 56 records from 7 countries (Figure 3.1). Germany (Baltic) 
has not reported threshold values officially but their experts have established target values based on expert 
judgement and we have considered them for the comparison. 

5 countries (BE, BG, FR, NO, PL) use a single value for each national type and 1 country (DE-Baltic) presents 
different values for well mixed waters (6 mg/l) and stratified waters (4 mg/l). Sweden provided EQR values, 
not allowing for a comparison with the absolute values provided to the MSFD reporting. 

19 

 
 
 
 
Figure 3.1Dissolved oxygen standards by country reported to WFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. 

MSFD data for Dissolved Oxygen provided 125 records from 13 countries using single values. Cyprus does not 
provide a value and only specifies “<25% reference value” without giving the reference value. Portugal shows 
a range, and it is assumed that it represents upper and lower threshold values, as dissolved oxygen is a QE 
that might be expected to have a two tailed effect. (Figure 3.2) 

Figure 3.2Dissolved oxygen standards by country reported to MSFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. 

The comparison is only possible between three countries (DE-Baltic, FR, PL).  

In all cases, the same standards have been used for WFD and MSFD. France establishes the same threshold 
values for the North Atlantic and Mediterranean Sea. And this value (3 mg/l) is also provided in OSPAR (2013) 
by France. 

20 

 
 
 
 
 
France and Poland establish threshold values lower than those considered in the literature. Vaquer-Sunyer and 
Duarte (2008) found strong  global evidence that, in  marine waters, the threshold of  4.6 mg O2/L could be 
taken as a precautionary limit to avoid catastrophic mortality events, but it would still not protect the most 
sensitive species (e.g., most fish and crustaceans, particularly early life-cycle stages).In the marine environment 
chronic and acute oxygen deficiency occurs when levels fall between 2 and 6 mg O2/L and below 2 mg O2/L, 
respectively  (OSPAR,  2013),  while  concentrations  less  than  2  mg  O2/L  (hypoxia,  i.e.  oxygen  deficiency)  are 
considered to cause severe problems (OSPAR, 2013). However, some countries (i.e Sweden, Italy,  Croatia or 
Slovenia) have reported values to MSFD reporting lower than 4 mg/l. In the case of Sweden, this is in accordance 
with the values suggested  by HELCOM  (2013) for Baltic Proper and Gulf of Finland (3,11  mg/l).   Probably, 
these values are related to the water column stratification. The presence of stratification limits the downward 
mixing of well-oxygenated surface waters with the result that oxygen near the bottom can become depleted 
as  a  result  of  biological  consumption  (O’Boyle  and  Nolan,  2010).  In  this  sense,  German  experts  have 
differentiated target values for stratified (4mg/l) and none stratified stations (6 mg/l).  

Percent oxygen saturation  

The use of standards based on saturation, rather than concentration, has the added advantage that the value 
takes  into  account  salinity  or  temperature  –  which  have  a  profound  effect  on  oxygen  solubility  and  hence 
concentration (Boyle et al., 2009). However, it has been argued that saturation values should not be used as a 
standard as they can give a misleading interpretation of the amount of oxygen available for marine life (Best 
et al., 2007). 

WFD data for % oxygen saturation provided 19 records from 7 countries (Figure 3.2). 3 countries (ES, NL, NO) 
use a single value for each national type while 4 countries (HR, IE, PL, RO) present standards as a range.  

Of these none specifies that the ranges represent sub-types and it is assumed that the range represents upper 
and lower boundary values, as % oxygen saturation is a QE that might be expected to have a two tailed effect.  

Figure 3.3Comparison of coastal % oxygen saturation standards by country. (single value black, minimum blue, 
maximum red symbols, dotted lines show median values for the upper (red) and lower (blue) groups. (Source: 
Teixeira et al., 2021) 

MSFD reporting shows only two countries providing threshold values for oxygen saturation (IE, MT). Ireland is 
also providing threshold values to WFD reporting. In WFD reporting, Ireland provides a range as threshold value: 
Lower limit (95th%ile < 70-80%) and upper limit (95th%ile < 120-130) ranges as limit. The value range is 

21 

 
 
 
 
the same as those provided by Ireland in OSPAR (2013). However, in the MSFD reporting, only a single value 
(120 %), is specified. 

 3.1.2 Transparency  

The estimation of water clarity in terms of Secchi disk depth is important for assessing water quality in coastal 
and transitional waters. High values regarding Secchi depth mean clear water where sunlight can penetrate. 
Lowest Secchi depth values mean turbid waters and a difficult biological regeneration in shallow water. 

Secchi depth monitoring (4 times a year) is mandatory in the Black Sea Commission. UNEP-MAP recommends 
the  secchi  depth  monitoring  for  a  complete  assessment  of  eutrophication  and  GES  achievement.  OSPAR 
recommends include it in the OSPAR’s Common Procedure (COMP) for the assessment of the eutrophication 
status as part of a holistic assessment. In the Baltic Sea, the monitoring of secchi depth has a long tradition 
and it’s a mandatory HELCOM parameter. 

WFD data for Secchi disk depth provided 54 records from 11 countries (Figure 3.4). Germany (Baltic) has not 
reported values officially but experts have established target values based on expert judgement and we have 
considered them for the comparison. 

Most countries use the annual mean (“AA-EQS”) or summer mean as summary metric. 8 countries (DE, EE, FI, 
HR, LV,  NO, PL, PT) use a single value for each national type, while 3 countries (BG, LT, RO) present standards 
as a range. Sweden provided EQR values, not allowing for a comparison with the absolute values provided to 
the MSFD reporting. 

Figure 3.4 Secchi  depth standards by country reported to WFD reporting.  Box plots  correspond to  countries 
reporting different threshold values for each national type or presenting a range of values. 

Similarly, MSFD reporting provided 68 records from 12 countries (Figure 3.5). All the countries use a single 
value for each area reported.  

22 

 
 
 
Figure 3.5 Secchi depth standards by country reported to MSFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. 

From these 10 (WFD) and 12 (MSFD) countries, only 7 have reported threshold values for both purposes (Figure 
3.6). 4 countries (DE, FI, LV, PL) have provided the same values for WFD and MSFD reporting. Lithuania has 
reported a  range to WISE, with the upper standard being  the same value than the single value reported to 
MSFD. Estonia ad Romania have reported lower values to MSFD reporting than to WFD reporting.  Germany 
considers that transparency is not regarded as a suitable indicator in the North Sea coastal waters due to high 
natural turbidity in the Wadden Sea.  

France has reported turbidity, providing the same threshold values to WFD and MSFD. 

Figure 3.6 Comparison of range/single values of Secchi depth (m) reported to WFD and MSFD reporting. 

The Romanian coastal zone is influenced by the outflow of the Danube river, with the river runoff having a 
significant  impact  on  both  formation  of  surface  water  masses,  and  biochemical  features  of  the  shelf.  The 
reference condition and target values presented under the Black Sea Commission (BlackSeaBaltic report, 2014) 
for coastal waters are the same than those provided to the WDF reporting. The difference encountered between 
the threshold values reported by Romania to WFD and MSFD reporting is very significant, being very lenient in 
the case of the MSFD reporting.  

23 

 
 
 
 
 
3.1.3 Dissolved Inorganic Nitrogen  

DIN is generally regarded as the single most important contributor to anthropogenically-induced changes in 
phytoplankton communities (Devlin &  Bonne, 2016). Winter measurements indicate the size of the nutrient 
pool available for the spring phytoplankton bloom (Andersen and Cowly, 2006). The use of winter means of 
dissolved inorganic nitrogen and phosphorus is common practice in the northern regional seas (Baltic Sea, North 
Sea) but may be less suitable to describe the nutrient levels in southern seas like the Mediterranean Sea and 
the Black Sea where the growing season is longer (OSPAR, 2013). 
DIN is a mandatory parameter in the OSPAR and HELCOM Eutrophication Monitoring Programs. The assessment 
criteria  are  partly  agreed  at  regional  level  for  the  Black  Sea  Commission.  For  the  UNEP  MAP  there  is  no 
agreement on assessment criteria. 

WFD data show 105 records from 9 countries. The majority of the countries use the winter or summer as the 
summary metric. 8 countries (BE, DE, FR, HR, IE, NL, PL, SE) use a single value for each national type and 1 
country (RO) presents standards as a range, which refer to subtype specific boundaries. Four countries (BE, IE, 
NL, SE) present threshold values which refer to salinity or reflect an adjustment to the salinity gradient. (Figure 
3.7) 

Figure 3.7 DIN standards by country reported to WFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

MSFD reporting shows 115 records from 12 countries. The majority of countries use the same metric than for 
the WFD. All countries use a single value for each coastal area reported. As for WFD, four countries (BE, IE, NL, 
SE) present threshold values which refer to salinity (Figure 3.8). 

24 

 
 
 
 
 
 
Figure 3.8 DIN standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

From the 9 countries that reported to WFD and 11 that reported to MSFD, only 8 have reported to both (Figure 
3.9). 5 countries (DE, FR, IE, PL, SE) have reported the same values. Croatia has given the same upper value for 
both purposes. Belgium has provided a more restrictive threshold value (15 µmol/l) to WFD reporting which 
cannot  be  related  to  the  different  metrics  used.  Maximum  concentration  in  winter for WFD  winter  average 
concentration. This value reported to WFD is the same than the target for outer coastal waters included in 
OSPAR (2013).  

The Netherlands provides the same value included in OSPAR (2013) (30 µmol/l) to MSFD reporting, with the 
value given for the WFD (33 µmol/l) being a bit more lenient. 

Romania provides more restricted values (2.14 µmol/l; 7.14 µmol/l) to MSFD reporting than to WFD reporting 
(9-11.5 µmol/l), with the WFD values being even lower than the value provided for marine waters (10,5 µmol/l). 
Boundaries provided to WFD reporting are in accordance to the reference and target values included in the 
BlackBaltic report. We suggest that Romanian experts check the threshold values reported to MSFD reporting. 

25 

 
 
 
 
Figure 3.9 Comparison of range/single threshold values of DIN (µmol/l) reported to WFD and MSFD reporting. 

3.1.4  Total Nitrogen  

Total nitrogen (TN) is a useful assessment parameter in addition to the winter DIN since they include all phases 
of the elements N and bridge  as all-season-values the time-gap  between winter and algal growing  season 
(OSPAR, 2013). Total nutrients are essential for determining nutrient budgets, which have particular importance 
in coastal and marine waters that are influenced by transboundary nutrient transports and receive nutrient 
inputs from other countries. Furthermore, total nutrients are also essential parameters for establishing nutrient 
reduction targets (Poikane et al., 2019).  

However, it is not an obligatory parameter in the OSPAR-Eutrophication Monitoring program and there is not a 
general assessment criterion agreed in UNEP-MAP. For the Black Sea Commission and HELCOM TN monitoring 
is mandatory. 

 WFD  data  include  144  records  from  9  countries.  The  majority  of  the  countries  use  the  summer  mean 
(“summer”) as a summary metric. 6 countries (DE, EE, FI, GR, NO, PL, SE) use a single value for each national 
type and 1 country (LT) presents standards as a range, which refer to subtype specific boundaries. 2 countries 
(SE, NO) present threshold values which refer to salinity or reflect an adjustment to the salinity gradient. (Figure 
3.10) 

26 

 
 
 
 
Figure 3.10 TN standards by country reported to WFD monitoring. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

MSFD reporting includes 116 records from 9 countries (DE, EE, ES, FI, MT, LT, LV, PL, SE). All of them use a 
single value for each national type and 1 country (SE) present threshold values which refer to salinity or reflect 
an  adjustment  to  the  salinity  gradient  (Figure  3.11).  The  high  value  reported  by  Latvia  is  remarkable  in 
comparison with the values reported by neighbouring countries (Lithuania and Estonia) sharing similar coastal 
areas.  

Figure 3.11 TN standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

Only 6 countries (DE, EE, FI, LT, PL, SE) have reported threshold values for both purposes; 5 countries (DE, FI, 
LT, PL, SE) have reported the same threshold values (Figure 3.6). Estonia has provided more lenient values for 

27 

 
 
 
 
MSFD  which  can  be  related  to  the  metrics  used  (annual  average  for  WFD  and  summer  average  for  MSFD 
reporting (Figure 3.12). 

Figure 3.12 Comparison of range/single threshold values of TN (µmol/l) reported to WFD and MSFD reporting. 

2.1.5 Dissolved Inorganic Phosphorus (DIP) 

Dissolved inorganic phosphorus, commonly referred to as orthophosphate or more correctly as soluble reactive 
phosphorus (SRP)  (Wetzel, 2001)  often  constitutes a  relatively  small  fraction  of  the  total  P  pool  in  aquatic 
systems, but its bioavailability makes it an important determinant of ecosystem function (Harrison et al., 2010). 
Giovanardi et al. (2018), argued that the TP concentrations observed at sea are closely and functionally related 
to freshwater inputs from the continent, and then to be referred to the amount of nutrient loads generated 
and  delivered  from  the  basins  burdening  on  the  coastal  areas.  But  the  phosphorus  associated  with  the 
freshwater inputs from the continent is a less ”conservative” substance than inorganic parameters, since its 
decay in seawater must be related not only to physical dilution, but also to removal from the system due to 
sedimentation and/or chemical precipitation (Giovanardi and Tromellini, 1992).  

Winter  DIP  concentrations  are  included  as  a  mandatory  parameter  in  OSPAR  and  HELCOM  monitoring 
requirements; DIP monitoring is also mandatory in the Black Sea Commission. There is no general assessment 
criterion agreed in UNEP-MAP. 

WFD  data  present  records  from  12  countries  (Figure  3.13).  The  majority  of  countries  use  the  winter  mean 
(“winter”) as a summary metric. 12 countries (BE, BG, ES, GR, HR, LV, NO, PL, PT, SE, SI) use a single value for 
each national type and 3 countries (CY, PT, RO) present standards as a range, which refer to subtype specific 
boundaries. Other countries (SE, NO, PT) present threshold values which refer to salinity or reflect an adjustment 
to the salinity gradient.  

28 

 
 
 
Figure 3.13 DIP standards by country reported to WFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. One of the values provided 
by Portugal has not been considered(outlier). 

MSFD reporting  presents  81  records from  13 countries (Fig 3.14). The  majority of  countries use the winter 
mean (“winter”) as a summary metric. All countries use a single value for each national type and 1 country (SE) 
presents threshold values or set of values which refer salinity or reflect an adjustment to the salinity gradient.  

Figure 3.14: DIP standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

From these 13 (WFD) and 13 (MSFD) countries, only 8 have reported threshold vales for both purposes. All of 
them have reported the same threshold values except Spain (Figure 3.15). The high value presented by Spain 
to the MSFD reporting is similar to the target included in OSPAR (2013) for “Spain western Iberian upwelling 

29 

 
 
 
 
 
coast”. This national type has not been reported to WFD reporting, and this could be the reason for this 
difference.  

Figure 3.15 Comparison of range/single threshold values of DIP (µmol/l) reported to WFD and MSFD reporting. 

3.6 Total Phosphorus  

HELCOM (2013) considers TP (and TN) are indicators to be more robust, albeit not entirely, to seasonal changes 
particularly  the  length  of  the  productive  period,  since  they  are  independent  of  the  internal  transformations 
between the inorganic and organic pools. Therefore, fulfilment of the nutrient ecological objective should mainly 
be based on targets for total nutrients. Monitoring of TP is mandatory in HELCOM. 

TP is not an obligatory parameter in the OSPAR-Eutrophication Monitoring program and there is no general 
assessment criterion agreed in UNEP-MAP. 

WFD data include 157 records from 12 countries (Figure 3.16). The majority of the countries use the summer 
mean (“summer”) as a summary metric. 10 countries (DE, EE, FI, GR, HR, NO, PL, PT, SE, SI) use a single value 
for each national type and 4 countries (DE, EE, LT, RO) present standards as a range, which refer to subtype 
specific  boundaries.  Other  countries  (NO,  SE)  present  threshold  values  which  refer  to  salinity  or  reflect  an 
adjustment to the salinity gradient. 

30 

 
 
 
 
 
Figure 3.16 TP standards by country reported to WFD  reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

MSFD reporting includes 100 records from 14 countries (Figure 3.17). All countries use a single value for each 
national type except Sweden, which presents threshold values or a set of boundaries referring to salinity or 
reflecting an adjustment to the salinity gradient. 

Figure 3.17 TP standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. 

From  these  12  (WFD)  and  14  (MSFD)  countries,  only  7  have  reported  for  both  purposes  (Figure  3.18).  The 
differences  between  the  values  reported  by  Estonia  can  be  related  to  the  different  metrics  used  (annual 
average for WFD and summer average for MSFD reporting). 

31 

 
 
 
 
Figure 3.18Comparison of range/single threshold values of TP (µmol/l) reported to WFD and MSFD reporting. 

32 

 
 
 
 
 
4  Discussion 

4.1 General comments 

The  previous  chapter  showed  threshols  values  used  by  Member  States  for  different  physico-chemical 
supporting elements and made some tentative comparisons between threshold values reported to WFD and 
MFD reporting by each country.  In few cases, there are clear differences.  These might be due to differences 
in aggregation rules, the summary statistics used, the assessment season or boundaries adjustment to other 
factors (for example, salinity ranges). All these differences can be due to the different national experts working 
in the implementation of the WFD and MSFD in coastal areas, or different monitoring areas used. All of this 
complicate the harmonization of the eutrophication assessment in coastal areas.    

We give a summary on the main differences encountered between the threshold values reported to WFD and 
MSFD  reporting,  the  links  with  the  Regional  Sea  Conventions,  and  the  consequences  of  the  lack  of 
harmonization.  

4.2 Overview of comparison of GES boundaries and links with RSC 

Eutrophication is of concern in European marine waters and legal instruments have been developed at the EU 
level to ensure the protection of marine water quality. This was firstly through the introduction of the Water 
Framework Directive (2000/60/EC), which addresses transitional, coastal, groundwater and inland surface 
waters and it was followed by the Marine Strategy Framework Directive (MSFD) (20078/56/EC) which 
establishes a framework for the protection, conservation and sustainable use of the marine environment and 
ecosystems at the Union level (Araujo et al., 2018). 

Setting consistent eutrophication criteria and boundaries under the WFD and the MSFD is therefore essential 
for consistent management across the continuum of transitional, coastal and marine waters.  

Salas  et  al.  (2020)  shows  some  significant  differences  in  the  parameters  assessed  and  the  current  work 
presents  some  differences  between  the  threshold  values  of  the  same  elements  considered  across  both 
Directives. 

It is difficult to do a good comparison when a significant percentage of countries have included  the physico 
chemical parameters in their monitoring plans, but they have not reported threshold values. This is more evident 
in the case of the WFD implementation (Figures 2.1-2.12). 

Therefore, the comparison has been only possible between few countries. A clear example of this situation is 
the comparison of the values of dissolved oxygen. Although oxygen conditions is a mandatory parameter for 
WFD  and  MSFD,  the  comparison  has  been  only  possible  for  3  countries  (DE,  FR  and  PL).  Sweden  has  also 
reported threshold values, but in the case of WFD the boundaries are reported as Ecological Quality Ratio (EQR) 
values, and in the  case of  MSFD as absolute values. Similarly, Finland has reported the threshold  value as 
absolute values to WFD and as an “integrative eutrophication value” to MSFD reporting (although during the 
review of this report Finish experts have provided information about the values behind these integrative values). 
Our recommendation is that all Member States should report threshold values of the physico chemical elements 
as absolute  values,  allowing  for  a  comparison  not  only  between  Directives,  but  also  between  neighbouring 
countries. 

In  general,  where  the  comparison  has  been  possible,  we  have  observed  the  same  or  similar  values.  When 
differences have been encountered, less restrictive values have been reported, in the majority of the cases, to 
MSFD reporting. These differences can be due to the different metrics used (e.g Estonia for TN), or different 
national types reported (e.g ES for DIP), but this should be confirmed by national experts.   

Romanian experts should explain in their MSFD reporti the reasons for providing in some cases more restrictive 
threshold values in coastal than in marine waters to MSFD reporting. 

Regarding the links with the Regional Sea Conventions, HELCOM seems the RSC more in accordance with the 
WFD and MSFD implementation. For the eutrophication assessment HELCOM recommends the monitoring of 
all the physico chemical elements included in the Commission Decision (EU) 2017/848 of 17 May, suggesting 
the use of the national threshold values proposed by each country in the assessment in coastal areas for the 

33 

 
 
 
WFD implementation. Poland, Germany and Sweden are the countries with most similarities n the use of the 
same parameters and threshold values between WFD and MSFD. 

Like HELCOM, OSPAR does not establish threshold values in coastal waters; these values are provided by each 
country, without considering the harmonization of these values between neighbouring countries. Most of the 
countries report the same values included in OSPAR reports to WISE and/or MSFD reporting’s. Although TP and 
TN are parameters included in the Annex of the MSFD, OSPAR considers their monitoring for eutrophication 
assessment  on  a  voluntary  basis.  OSPAR  is  currently  working  on  developing  a  region  wide  harmonised 
assessment of eutrophication including the derivation of the new harmonized threshold values for use in the 
4th application of the Common Procedure and the OSPAR QSR 2023.  

The updated Black Sea Integrated Monitoring and Assessment Programme is in line with the requirements of 
the MSFD, but there is no agreement on the establishment of threshold values. The values considered in this 
report are those presented in the context of the project “Baltic2Black” and are provided by each country, without 
their harmonization. Bulgaria has not reported any value to the MSFD reporting, and Romania has only reported 
threshold values in coastal waters for DIN, TP and Secchi depth to the MSFD reporting, not following the BESP 
recommendations for the eutrophication assessment. 

In UNEP MAP, there are no nutrients assessment criteria agreed, but it recommends transparency of the water 
column  and  dissolved  oxygen  for  a  complete  assessment  of  eutrophication  and  GES  assessment.  Oxygen 
condition is considered by all countries for both Directives in the monitoring programs but only 3 Mediterranean 
countries (HR, FR, ES) have reported threshold values to WFD, and 5 have reported threshold values to MSFD. 
In the case of transparency, only Croatia has reported values for secchi depth to WFD, and Malta and Slovenia 
to MSFD reporting. France have also reported transparency threshold values for both purposes, but for turbidity.  

34 

 
 
  
 5 Conclusions 

1.  The  discrepancy  between  the  monitoring  plans  and  the  reporting  of  threshold  values  does not  allow  a 
comprehensive comparison between WFD and MSFD. Experts should explain the reasons for not reporting 
threshold values, and in the case they have done it to WFD but not to MSFD reporting or vice versa, to 
provide  the  reasons  why  they  have  not  considered  to  report  those  values  to  both  Directives.    It  often 
remains unclear which parameters are really used in the assessment. 

2.  The Annex of the Commission Decision (EU) 2017/848 of 17 May specifies the nutrient criteria (TN, TP, 
TDIN and DIP) required for eutrophication assessment, saying that “Within coastal waters, as used under 
Directive 2000/60/EC” but it seems that this t is not considered by many countries, opening the door to 
different interpretations and the existence of gaps in the reporting for both Directives. For example, Spain 
(Mediterranean) has reported only threshold values of nitrate, nitrite  and ammonium to WFD but it has 
reported values of TN, TP, and DIN to MSFD reporting, which are parameters not used by this country under 
WFD.  

3. 

In general, when the comparison has been possible between WFD and MSFD reporting, the same threshold 
values have been observed in both reporting. Some exceptions could be related to different metrics used, 
or  different  areas  considered,  and  this  should  be  explained  by  the  experts.  Our  recommendation  is  to 
consider  the  same  assessment  season,  the  same  metric  and the  same  areas  (or  national  types)  to  be 
reported. 

4.  Poland and Sweden are good examples of harmonization in the monitoring plans and reporting of threshold 
values in the implementation of both Directives. These countries are in line with the requirements of both 
Directives and requirements of HELCOM and OSPAR.  

5.  HELCOM and BSC are more in line with the WFD and MSFD requirements, than OSPAR and UNEP_MAP. The 
annex of the MSFD Decision, specifies the nutrients parameters to be considered, but for OSPAR TN and 
TP are not obligatory parameters, and for UNEP-MAP there are no nutrients assessment criteria agreed 

6.  HELCOM,  OSPAR  countries  follow  the  recommendations  of  the  RSC,  but  in  the  case  UNEP-MAP,  not  all 
recommendations are followed by Mediterranean countries (UNEP MAP). Romania and Bulgaria performed 
their duties under WFD, MSFD and the Black Sea Integrated Monitoring and Assessment Pollution (BSIMAP). 
A better collaboration between RSCs and MS is recommended in order to harmonize the eutrophication 
assessment  in  line  with  the  requirements  of  WFD  and  MSFD,  making  better  use  of  existing  data  and 
methods.  

35 

 
 
 
References 

Andersen and Cowly, 2006. Andersen, J.H. and Conley, D.J. (eds) (2006). Eutrophication in coastal Ecosystems: 
selected  papers  from  the  second  International  Symposium  on  Research  Management  of  Eutrophication  in 
Coastal ecosystems, 20-23 June 2006, Nyborg, Denmark. 

Araújo, R., Somma, F., Aigars, J., Axe, P., Bartolo, A., De Cauwer, K., Devreker, D., Fleming-Lehtinen, V., García-
Denche, L.M., Knudsen-Leerbeck, H., Kraśniewski, W., Lazar, L., Lefebvre, A., Lips, I., Magaletti, E., Moncheva, S., 
Pagou,  K.,  Precali,  R.,  Ruiter,  H.,  Wilkes,  R.    2019.  Eutrophication  in  marine  waters:  harmonization  of  MSFD 
methodological standards at EU level. JRC Technical Report. Publications Office of the European Union. 

Environmental  monitoring  of  the  Black  Sea  with  focus  on  nutrient  pollution”  (Acronym:  Baltic2Black).  Final 
Report for the Grant Agreement No 07.0204/2010/580913/SUB/D2. 2014 

Best, M., Wither, A., Coates, S., 2006. Dissolved oxygen as a physico-chemical supporting element in the water 
framework directive. Mar.Pollut. Bull. 55:53-64. 

Black Sea Commission, 2008. State of the environment of the Black Sea (2001–2006/7). Publications of the 
Commission on the Protection of the Black Sea against Pollution (BSC) 2008-3. Istanbul, Turkey. 

Claussen, U., Zevenboom, W., Brockmann, U., Topcu, D., Bot, P., 2009. Assessment of the eutrophication status 
of transitional, coastal and marine waters within OSPAR. Hydrobiologia, 629(1), 49.  

O’Boyle, S., McDermott, G., Wilkes, R. 2009. Dissolved oxygen levels in estuarine and coastal waters around 
Ireland. Marine Pollution Bulletin, 58: 1657-1663. 

Devlin, M. and Bonne, W. (2016). NEA GIG Intercalibration Report. Phytoplankton element. Common type NEA 
1/26 (Available at CIRCA) 

Giomi, F., Barausse, A., Duarte, C. M., Booth, J., Agusti, S., Saderne, V., .& Fusi, M. (2019). Oxygen supersaturation 
from  ocean  warming. Science  advances, 5(9),  eaax1814.  doi: 
protects  coastal  marine 
10.1126/sciadv.aax1814 

fauna 

D. Gilbert, N. N. Rabalais, R. J. Diaz, and J. Zhang. 2010. Evidence for greater oxygen decline rates in the coastal 
oceanthan in the open ocean. Biogeosciences, 7, 2283–2296 

Giovanardi, F. and E. Tromellini, (1992). Statistical Assessment of Trophic Conditions. Application of the OECD 
Methodology to the Marine Environment.Proc. Int. Conf. Marine Coastal Eutrophication. Sci.Total Environ. Suppl. 
1992: 211-233. 
Giovanardi, F., France, J., Mozeric, P., Precalli, R. (2018). Development of ecological classification criteria for the 
Biological Quality Element phytoplankton for Adriatic and Tyrrhenian coastal waters by means of chlorophyll a 
(2000/60/EC WFD). Ecological Indicators, 93: 316-332.  

HELCOM, 2013.Approaches and methods for eutrophication target setting in the BalticSea region. Baltic Sea 
Environment Proceedings No. 133 (138 pp). 

HELCOM, 2015. HELCOM Eutrophication Assessment.http://helcom.fi/helcom-at-work/projects/eutro-oper/. 

HELCOM, 2017. HELCOM core indicator report. Online.ww.helcom.fi 

O’Boyle, S and Nolan, G. 2010. The influence of water column stratification on dissolved oxygen levels in coastal 
and shelf waters around Ireland.  

OSPAR [The Convention for the Protection of the Marine Environment of the North-East Atlantic] EUR 30383 
ISBN  978-92-76-22418-1, 
EN,  Publications  Office  of  the  European  Union,  Luxembourg,  2020, 
doi:10.2760/444388, JRC121759.www.ospar.org/work-areas/hasec/eutrophication/common-procedure. 

Salas Herrero, F., Aráujo, R., Claussen, U., Leujak, W., Boughaba, J., Dellsaea, J., Somma, F., Poikane, S. 2020. 
Physico chemical supoorting element. in costal waters: Links between Water and Marine Framework Directives 
and Regional Sea Conventions . EUR 30383 EN, Publications Office of the European Union, Luxembourg, 2020, 
ISBN 978-92-76-22418-1, doi:10.2760/444388, JRC121759. 

Schindler, D. E., Jankowski, K., A'mar, Z. T., & Holtgrieve, G. W. (2017). Two‐stage metabolism inferred from diel 
oxygen dynamics in aquatic ecosystems. Ecosphere, 8(6), e01867.https://doi.org/10.1002/ecs2.1867 

Topping, G. 1976. Sewage and the Sea. In: Johnston, R (ed). Marine Pollution:303-348. 

36 

 
 
Vaquer-Sunyer, R., & Duarte, C. M. (2008). Thresholds of hypoxia for marine biodiversity. Proceedings of the 
National Academy of Sciences, 105(40), 15452-15457. 

37 

 
 
 
 
 
List of abbreviations and definitions 

CIS: Common Implementation Strategy 

CW: Coastal waters  

D.O: Dissolved Oxygen 

ECOSTAT: WFD CIS working group dedicated to the ecological status of surface water bodies 

MS: Member State  

MSFD: Marine Strategy Framework Directive  

PHC: Physico- Chemical 

QE: Quality elemments 

RBMP: River Basin Management Plan  

TraC: Transitional and Coastal waters  

TW: Transitional waters 

WFD: Water Framework Directive

38 

 
 
 
 
 
 
 
 
List of Figures 

Figure 2.1 Oxygen conditions monitoring plans for WFD implementation (left) and countries reporting 
threshold values to WFD reporting (right). ............................................................................ 6 

Figure 2.2 Oxygen conditions monitoring plans for MSFD implementation (left) and countries reporting 
threshold values to MSFD reporting (right). .......................................................................... 7 

Figure 2.3 Secchi Depth monitoring plans for WFD implementation (left) and countries reporting threshold 
values to WFD reporting (right). ....................................................................................... 7 

Figure 2.4 Secchi Depth monitoring plans for MSFD implementation (left) and countries reporting threshold 
values to MSFD reporting (right). ...................................................................................... 8 

Figure 2.5 DIN monitoring plans for WFD implementation (left) and countries reporting threshold values to 
WFD reporting(right). ................................................................................................... 8 

Figure 2.6 DIN monitoring plans for MSFD implementation (left) and countries reporting threshold values to 
MSFD reporting (right). ................................................................................................. 9 

Figure 2.7 TN monitoring plans for WFD implementation (left) and countries reporting threshold values to 
WFD reporting (right). .................................................................................................. 9 

Figure 2.8 TN monitoring plans for MSFD implementation (left) and countries reporting threshold values to 
MSFD reporting (right). ................................................................................................10 

Figure 2.9 DIP monitoring plans for WFD implementation (left) and countries reporting threshold values to 
WFD reporting (right). .................................................................................................10 

Figure 2.10 DIP monitoring plans for MSFD implementation (left) and countries reporting threshold values to 
MSFD reporting (right). ................................................................................................11 

Figure 2.11 TP monitoring plans for WFD implementation (left) and countries reporting threshold values to 
WFD reporting (right). .................................................................................................11 

Figure 2.12 TP monitoring plans for MSFD implementation (left) and countries reporting threshold values to 
MSFD reporting (right). ................................................................................................12 

Figure 3.1Dissolved oxygen standards by country reported to WFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. 

20 

Figure 3.2Dissolved oxygen standards by country reported to MSFD reporting. Box plots correspond to 
countries reporting different threshold values for each national type or presenting a range of values. .......20 

Figure 3.3Comparison of coastal % oxygen saturation standards by country. (single value black, minimum 
blue, maximum red symbols, dotted lines show median values for the upper (red) and lower (blue) groups. 
(Source: Teixeira et al., 2021) .........................................................................................21 

Figure 3.4 Secchi depth standards by country reported to WFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. ..................22 

Figure 3.5 Secchi depth standards by country reported to MSFD reporting. Box plots correspond to countries 
reporting different threshold values for each national type or presenting a range of values. ..................23 

Figure 3.6 Comparison of range/single values of Secchi depth (m) reported to WFD and MSFD reporting. ....23 

Figure 3.7 DIN standards by country reported to WFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................24 

Figure 3.8 DIN standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................25 

Figure 3.9 Comparison of range/single threshold values of DIN (µmol/l) reported to WFD and MSFD reporting.
 ..........................................................................................................................26 

Figure 3.10 TN standards by country reported to WFD monitoring. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................27 

39 

 
 
Figure 3.11 TN standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................27 

Figure 3.12 Comparison of range/single threshold values of TN (µmol/l) reported to WFD and MSFD reporting.
 ..........................................................................................................................28 

Figure 3.13 DIP standards by country reported to WFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. One of the values provided 
by Portugal has not been considered(outlier). .......................................................................29 

Figure 3.14: DIP standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................29 

Figure 3.15 Comparison of range/single threshold values of DIP (µmol/l) reported to WFD and MSFD reporting.
 ..........................................................................................................................30 

Figure 3.16 TP standards by country reported to WFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................31 

Figure 3.17 TP standards by country reported to MSFD reporting. Box plots correspond to countries reporting 
different threshold values for each national type or presenting a range of values. .............................31 

Figure 3.18Comparison of range/single threshold values of TP (µmol/l) reported to WFD and MSFD reporting.
 ..........................................................................................................................32 

40 

 
 
 
 
 
 
 
List of Tables 

Table 2.1 General physico-chemical quality elements reported to WFD and MSFD reporting, summarised by 
number of countries. ..................................................................................................12 

Table 2.2 Threshold values (in grey) reported to WFD and MSFD reporting by different countries for coastal 
waters. ..................................................................................................................13 

Table 2.3 Threshold values reported by each country and included in the RSC reports. .........................15 

Table 2.4 Overview of parameters and metrics included in the RSC reports. .....................................16 

Table 2.5 Overview of metrics used by the countries for the parameters with threshold values in WFD and 
MSFD reporting in coastal waters. AA (annual average); A(average); AGM (annual geometric median); MAC 
(Maximum Allowable Concentration). ................................................................................17 

41 

 
 
 
 
 
 
 
 
 
 
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